U.S. patent application number 12/878448 was filed with the patent office on 2011-03-17 for valve timing control apparatus for internal combustion engine, and method of producing same.
This patent application is currently assigned to Hitachi Automotive Systems, Ltd.. Invention is credited to Atsushi WATANABE.
Application Number | 20110061616 12/878448 |
Document ID | / |
Family ID | 43729240 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110061616 |
Kind Code |
A1 |
WATANABE; Atsushi |
March 17, 2011 |
Valve Timing Control Apparatus for Internal Combustion Engine, and
Method of Producing Same
Abstract
A valve timing control apparatus for an internal combustion
engine, includes a housing body, a sealing plate, a vane rotor, and
a sealing ring. The housing body includes an opening at an axial
end which is closed by the sealing plate. The sealing ring is
disposed between the housing body and the sealing plate. The
housing body is formed of an aluminum-based metal material and
anodized, wherein the housing body includes a base layer and an
anodic oxide coating film layer. The sealing ring abuts on the base
layer of the housing body at the axial end.
Inventors: |
WATANABE; Atsushi;
(Atsugi-shi, JP) |
Assignee: |
Hitachi Automotive Systems,
Ltd.
Hitachinaka-shi
JP
|
Family ID: |
43729240 |
Appl. No.: |
12/878448 |
Filed: |
September 9, 2010 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 2001/34479
20130101; F01L 2303/00 20200501; F01L 1/024 20130101; F01L 1/3442
20130101; F01L 1/02 20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2009 |
JP |
2009-214723 |
Claims
1. A valve timing control apparatus for an internal combustion
engine, comprising: a housing body having a hollow cylindrical
shape including an opening at an axial end, wherein the housing
body is formed integrally with a pulley at an outside periphery of
the housing body, and formed integrally with a shoe at an inside
periphery of the housing body, wherein the pulley is adapted to
receive torque from a crankshaft of the internal combustion engine,
and wherein the shoe projects inwardly in a radial direction of the
housing body; a sealing plate fixed to the axial end of the housing
body, the sealing plate closing the opening of the housing body; a
vane rotor adapted to be fixed to a camshaft of the internal
combustion engine, and rotatably mounted in the housing body,
wherein the vane rotor includes a vane, wherein the vane defines a
working fluid chamber between the vane and the shoe, and wherein
the working fluid chamber is adapted to supply and drainage of
working fluid; and a sealing ring disposed between the housing body
and the sealing plate, the sealing ring sealing the working fluid
chamber, wherein: the housing body is formed of an aluminum-based
metal material and anodized, wherein the housing body includes a
base layer and an anodic oxide coating film layer; the anodic oxide
coating film layer is present at the outside periphery; and the
sealing ring abuts on the base layer at the axial end.
2. A valve timing control apparatus for an internal combustion
engine, comprising: a housing body having a tubular shape including
an opening at an axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; a sealing plate
facing an axial end surface of the housing body, and closing the
opening of the housing body; a phase change mechanism mounted in
the housing body, and adapted to change a rotational phase of a
camshaft of the internal combustion engine with respect to the
housing body in response to supply and drainage of working fluid;
and a sealing ring disposed between the housing body and the
sealing plate, wherein: the housing body is formed of an
aluminum-based metal material and anodized, wherein the housing
body includes a base layer and an anodic oxide coating film layer;
and the anodic oxide coating film layer is present at the outside
periphery and an inside periphery of the housing body, and absent
at the axial end surface of the housing body facing the sealing
plate.
3. A valve timing control apparatus for an internal combustion
engine, comprising: a housing body having a tubular shape including
an opening at an axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; a sealing plate fixed
to the axial end of the housing body, the sealing plate closing the
opening of the housing body; a phase change mechanism mounted in
the housing body, and adapted to change a rotational phase of a
camshaft of the internal combustion engine with respect to the
housing body in response to supply and drainage of working fluid;
and a sealing ring disposed between the housing body and the
sealing plate, wherein: the housing body is formed of an
aluminum-based metal material and anodized, wherein the housing
body includes a base layer and an anodic oxide coating film layer;
and the anodic oxide coating film layer is present at the outside
periphery of the housing body, and absent at a surface of the
housing body on which the sealing ring abuts.
4. The valve timing control apparatus as claimed in claim 3,
wherein: the housing body has a hollow cylindrical shape, wherein
the housing body is formed integrally with a shoe at an inside
periphery of the housing body, and wherein the shoe projects
inwardly in a radial direction of the housing body; the phase
change mechanism includes a vane rotor adapted to be fixed to a
camshaft of the internal combustion engine, and rotatably mounted
in the housing body, wherein the vane rotor includes a vane,
wherein the vane defines a working fluid chamber between the vane
and the shoe, and wherein the working fluid chamber is adapted to
supply and drainage of working fluid; and the sealing ring seals
the working fluid chamber at the axial end of the housing body.
5. The valve timing control apparatus as claimed in claim 3,
wherein the sealing ring abuts on the base layer at the axial
end.
6. The valve timing control apparatus as claimed in claim 3,
wherein the anodic oxide coating film layer is present also at an
inside periphery of the housing body.
7. The valve timing control apparatus as claimed in claim 3,
further comprising a plurality of bolts extending in an axial
direction of the housing body, and fixing the sealing plate to the
housing body.
8. The valve timing control apparatus as claimed in claim 7,
wherein the sealing plate is formed of a harder material than the
housing body.
9. The valve timing control apparatus as claimed in claim 3,
wherein: the housing body includes an opening at another axial end;
and the valve timing control apparatus further comprises another
sealing plate fixed to the other axial end.
10. The valve timing control apparatus as claimed in claim 3,
wherein the sealing plate includes a sealing ring groove that
retains the sealing ring.
11. A method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a hollow cylindrical shape
including an opening at each axial end, wherein the housing body is
formed integrally with a pulley at an outside periphery of the
housing body, and formed integrally with a shoe at an inside
periphery of the housing body, wherein the pulley is adapted to
receive torque from a crankshaft of the internal combustion engine,
and wherein the shoe projects inwardly in a radial direction of the
housing body; at least one sealing plate fixed to an axial end
surface of the housing body, the sealing plate closing a
corresponding one of the openings of the housing body; a vane rotor
adapted to be fixed to a camshaft of the internal combustion
engine, and rotatably mounted in the housing body, wherein the vane
rotor includes a vane, wherein the vane and the shoe define an
advance chamber and a retard chamber between the vane rotor and
housing body, and wherein the advance chamber and the retard
chamber are adapted to supply and drainage of fluid; and at least
one sealing ring disposed between the sealing plate and the axial
end surface of the housing body, the method comprising a process of
producing the housing body, the process comprising: an extruding
operation of forming a first workpiece by extruding an
aluminum-based metal material, wherein the first workpiece extends
in a direction of extrusion; a coating operation of forming a
second workpiece by anodizing an entire surface of the first
workpiece; and a cutting-off operation of forming a third workpiece
by cutting out of the second workpiece to a predetermined length so
as to form the third workpiece with a cut surface forming the axial
end surface of the housing body on which the sealing ring
abuts.
12. A method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a hollow cylindrical shape
including an opening at each axial end, wherein the housing body is
formed integrally with a pulley at an outside periphery of the
housing body, and formed integrally with a shoe at an inside
periphery of the housing body, wherein the pulley is adapted to
receive torque from a crankshaft of the internal combustion engine,
and wherein the shoe projects inwardly in a radial direction of the
housing body; at least one sealing plate fixed to one of the axial
ends of the housing body, the sealing plate closing a corresponding
one of the openings of the housing body; a vane rotor adapted to be
fixed to a camshaft of the internal combustion engine, and
rotatably mounted in the housing body, wherein the vane rotor
includes a vane, wherein the vane and the shoe define an advance
chamber and a retard chamber between the vane rotor and housing
body, and wherein the advance chamber and the retard chamber are
adapted to supply and drainage of fluid; and at least one sealing
ring disposed between the sealing plate and the housing body, the
method comprising a process of producing the housing body, the
process comprising: an extruding operation of forming a first
workpiece by extruding an aluminum-based metal material, wherein
the first workpiece extends in a direction of extrusion; a coating
operation of forming a second workpiece by anodizing an entire
surface of the first workpiece; a cutting-off operation of forming
a third workpiece by cutting out of the second workpiece to a
predetermined length; and a carving operation of carving a
longitudinal end surface of the third workpiece so as to form the
third workpiece with a cut surface forming a surface of the housing
body on which the sealing ring abuts.
13. A method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a tubular shape including an
opening at each axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; at least one sealing
plate fixed to one of the axial ends of the housing body, the
sealing plate closing a corresponding one of the openings of the
housing body; a phase change mechanism mounted in the housing body,
and adapted to change a rotational phase of a camshaft of the
internal combustion engine with respect to the housing body in
response to supply and drainage of working fluid; and at least one
sealing ring disposed between the sealing plate and the housing
body, the method comprising a process of producing the housing
body, the process comprising: an extruding operation of forming a
first workpiece by extruding an aluminum-based metal material,
wherein the first workpiece extends in a direction of extrusion; a
coating operation of forming a second workpiece by anodizing an
entire surface of the first workpiece; and a cutting-off operation
of forming a third workpiece by cutting out of the second workpiece
to a predetermined length so as to form the third workpiece with a
cut surface forming a surface of the housing body on which the
sealing ring abuts.
14. The method as claimed in claim 13, wherein: the housing body
has a hollow cylindrical shape, wherein the housing body is formed
integrally with a shoe at an inside periphery of the housing body,
and wherein the shoe projects inwardly in a radial direction of the
housing body; the phase change mechanism includes a vane rotor
adapted to be fixed to a camshaft of the internal combustion
engine, and rotatably mounted in the housing body, wherein the vane
rotor includes a vane, wherein the vane defines a working fluid
chamber between the vane and the shoe, and wherein the working
fluid chamber is adapted to supply and drainage of working fluid;
and the sealing ring seals the working fluid chamber at the
corresponding axial end of the housing body.
15. The method as claimed in claim 13, wherein the pulley includes
a plurality of projections arranged in a circumferential direction
of the housing body, and wherein each projection extends in an
axial direction of the housing body.
16. A method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a tubular shape including an
opening at each axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; at least one sealing
plate fixed to one of the axial ends of the housing body, the
sealing plate closing a corresponding one of the openings of the
housing body; a phase change mechanism mounted in the housing body,
and adapted to change a rotational phase of a camshaft of the
internal combustion engine with respect to the housing body in
response to supply and drainage of working fluid; and at least one
sealing ring disposed between the sealing plate and the housing
body, the method comprising a process of producing the housing
body, the process comprising: an extruding operation of forming a
first workpiece by extruding an aluminum-based metal material,
wherein the first workpiece extends in a direction of extrusion; a
coating operation of forming a second workpiece by anodizing an
entire surface of the first workpiece; a cutting-off operation of
forming a third workpiece by cutting out of the second workpiece to
a predetermined length; and a carving operation of carving a
longitudinal end surface of the third workpiece so as to form the
third workpiece with a cut surface forming a surface of the housing
body on which the sealing ring abuts.
17. The method as claimed in claim 16, wherein the carving
operation is implemented by carving the longitudinal end surface of
the third workpiece so as to form the third workpiece with a
fitting recess, wherein the fitting recess includes the cut
surface, and wherein the sealing plate is fixed in the fitting
recess.
18. The method as claimed in claim 17, further comprising providing
the sealing ring between an inside periphery of the fitting recess
and an outside periphery of the sealing plate.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to valve timing control
apparatuses for internal combustion engines, and methods of
producing same.
[0002] Japanese Patent Application Publication No. 5-113112
discloses a valve timing control apparatus for an internal
combustion engine, which includes a housing connected to a
crankshaft, and a phase change mechanism mounted in the housing,
and connected to a camshaft. The housing is formed with a pulley at
its outside periphery to which torque is transmitted from the
crankshaft through a timing belt that is wound around the pulley,
so that the housing rotates in synchronization with the crankshaft.
The phase change mechanism operates in response to supply and
drainage of working fluid, for changing valve timing, i.e.
rotational phase of the camshaft with respect to the
crankshaft.
SUMMARY OF THE INVENTION
[0003] The valve timing control apparatus described above is
subject to a problem that the timing belt may be degraded by
adhesion of working fluid exiting out of the housing. Accordingly,
it is desirable to provide a valve timing control apparatus for an
internal combustion engine in which such a problem is solved by
suitable sealing.
[0004] According to one aspect of the present invention, a valve
timing control apparatus for an internal combustion engine,
comprises: a housing body having a hollow cylindrical shape
including an opening at an axial end, wherein the housing body is
formed integrally with a pulley at an outside periphery of the
housing body, and formed integrally with a shoe at an inside
periphery of the housing body, wherein the pulley is adapted to
receive torque from a crankshaft of the internal combustion engine,
and wherein the shoe projects inwardly in a radial direction of the
housing body; a sealing plate fixed to the axial end of the housing
body, the sealing plate closing the opening of the housing body; a
vane rotor adapted to be fixed to a camshaft of the internal
combustion engine, and rotatably mounted in the housing body,
wherein the vane rotor includes a vane, wherein the vane defines a
working fluid chamber between the vane and the shoe, and wherein
the working fluid chamber is adapted to supply and drainage of
working fluid; and a sealing ring disposed between the housing body
and the sealing plate, the sealing ring sealing the working fluid
chamber, wherein: the housing body is formed of an aluminum-based
metal material and anodized, wherein the housing body includes a
base layer and an anodic oxide coating film layer; the anodic oxide
coating film layer is present at the outside periphery; and the
sealing ring abuts on the base layer at the axial end.
[0005] According to another aspect of the present invention, a
valve timing control apparatus for an internal combustion engine,
comprises: a housing body having a tubular shape including an
opening at an axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; a sealing plate
facing an axial end surface of the housing body, and closing the
opening of the housing body; a phase change mechanism mounted in
the housing body, and adapted to change a rotational phase of a
camshaft of the internal combustion engine with respect to the
housing body in response to supply and drainage of working fluid;
and a sealing ring disposed between the housing body and the
sealing plate, wherein: the housing body is formed of an
aluminum-based metal material and anodized, wherein the housing
body includes a base layer and an anodic oxide coating film layer;
and the anodic oxide coating film layer is present at the outside
periphery and an inside periphery of the housing body, and absent
at the axial end surface of the housing body facing the sealing
plate.
[0006] According to a further aspect of the present invention, a
valve timing control apparatus for an internal combustion engine,
comprises: a housing body having a tubular shape including an
opening at an axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; a sealing plate fixed
to the axial end of the housing body, the sealing plate closing the
opening of the housing body; a phase change mechanism mounted in
the housing body, and adapted to change a rotational phase of a
camshaft of the internal combustion engine with respect to the
housing body in response to supply and drainage of working fluid;
and a sealing ring disposed between the housing body and the
sealing plate, wherein: the housing body is formed of an
aluminum-based metal material and anodized, wherein the housing
body includes a base layer and an anodic oxide coating film layer;
and the anodic oxide coating film layer is present at the outside
periphery of the housing body, and absent at a surface of the
housing body on which the sealing ring abuts.
[0007] According to a still further aspect of the present
invention, a method of producing a valve timing control apparatus
for an internal combustion engine, the valve timing control
apparatus comprising: a housing body having a hollow cylindrical
shape including an opening at each axial end, wherein the housing
body is formed integrally with a pulley at an outside periphery of
the housing body, and formed integrally with a shoe at an inside
periphery of the housing body, wherein the pulley is adapted to
receive torque from a crankshaft of the internal combustion engine,
and wherein the shoe projects inwardly in a radial direction of the
housing body; at least one sealing plate fixed to an axial end
surface of the housing body, the sealing plate closing a
corresponding one of the openings of the housing body; a vane rotor
adapted to be fixed to a camshaft of the internal combustion
engine, and rotatably mounted in the housing body, wherein the vane
rotor includes a vane, wherein the vane and the shoe define an
advance chamber and a retard chamber between the vane rotor and
housing body, and wherein the advance chamber and the retard
chamber are adapted to supply and drainage of fluid; and at least
one sealing ring disposed between the sealing plate and the axial
end surface of the housing body, the method comprises a process of
producing the housing body, the process comprising: an extruding
operation of forming a first workpiece by extruding an
aluminum-based metal material, wherein the first workpiece extends
in a direction of extrusion; a coating operation of forming a
second workpiece by anodizing an entire surface of the first
workpiece; and a cutting-off operation of forming a third workpiece
by cutting out of the second workpiece to a predetermined length so
as to form the third workpiece with a cut surface forming the axial
end surface of the housing body on which the sealing ring
abuts.
[0008] According to another aspect of the present invention, a
method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a hollow cylindrical shape
including an opening at each axial end, wherein the housing body is
formed integrally with a pulley at an outside periphery of the
housing body, and formed integrally with a shoe at an inside
periphery of the housing body, wherein the pulley is adapted to
receive torque from a crankshaft of the internal combustion engine,
and wherein the shoe projects inwardly in a radial direction of the
housing body; at least one sealing plate fixed to one of the axial
ends of the housing body, the sealing plate closing a corresponding
one of the openings of the housing body; a vane rotor adapted to be
fixed to a camshaft of the internal combustion engine, and
rotatably mounted in the housing body, wherein the vane rotor
includes a vane, wherein the vane and the shoe define an advance
chamber and a retard chamber between the vane rotor and housing
body, and wherein the advance chamber and the retard chamber are
adapted to supply and drainage of fluid; and at least one sealing
ring disposed between the sealing plate and the housing body, the
method comprises a process of producing the housing body, the
process comprising: an extruding operation of forming a first
workpiece by extruding an aluminum-based metal material, wherein
the first workpiece extends in a direction of extrusion; a coating
operation of forming a second workpiece by anodizing an entire
surface of the first workpiece; a cutting-off operation of forming
a third workpiece by cutting out of the second workpiece to a
predetermined length; and a carving operation of carving a
longitudinal end surface of the third workpiece so as to form the
third workpiece with a cut surface forming a surface of the housing
body on which the sealing ring abuts.
[0009] According to another aspect of the present invention, a
method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a tubular shape including an
opening at each axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; at least one sealing
plate fixed to one of the axial ends of the housing body, the
sealing plate closing a corresponding one of the openings of the
housing body; a phase change mechanism mounted in the housing body,
and adapted to change a rotational phase of a camshaft of the
internal combustion engine with respect to the housing body in
response to supply and drainage of working fluid; and at least one
sealing ring disposed between the sealing plate and the housing
body, the method comprises a process of producing the housing body,
the process comprising: an extruding operation of forming a first
workpiece by extruding an aluminum-based metal material, wherein
the first workpiece extends in a direction of extrusion; a coating
operation of forming a second workpiece by anodizing an entire
surface of the first workpiece; and a cutting-off operation of
forming a third workpiece by cutting out of the second workpiece to
a predetermined length so as to form the third workpiece with a cut
surface forming a surface of the housing body on which the sealing
ring abuts.
[0010] According to another aspect of the present invention, a
method of producing a valve timing control apparatus for an
internal combustion engine, the valve timing control apparatus
comprising: a housing body having a tubular shape including an
opening at each axial end, wherein the housing body is formed
integrally with a pulley at an outside periphery of the housing
body, and wherein the pulley is adapted to receive torque from a
crankshaft of the internal combustion engine; at least one sealing
plate fixed to one of the axial ends of the housing body, the
sealing plate closing a corresponding one of the openings of the
housing body; a phase change mechanism mounted in the housing body,
and adapted to change a rotational phase of a camshaft of the
internal combustion engine with respect to the housing body in
response to supply and drainage of working fluid; and at least one
sealing ring disposed between the sealing plate and the housing
body, the method comprises a process of producing the housing body,
the process comprising: an extruding operation of forming a first
workpiece by extruding an aluminum-based metal material, wherein
the first workpiece extends in a direction of extrusion; a coating
operation of forming a second workpiece by anodizing an entire
surface of the first workpiece; a cutting-off operation of forming
a third workpiece by cutting out of the second workpiece to a
predetermined length; and a carving operation of carving a
longitudinal end surface of the third workpiece so as to form the
third workpiece with a cut surface forming a surface of the housing
body on which the sealing ring abuts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a front view of a valve timing control apparatus
according to an embodiment of the present invention in which a pair
of intake valve timing control apparatuses and a pair of exhaust
valve timing control apparatuses are mounted to an internal
combustion engine, as viewed in an axial direction of the internal
combustion engine.
[0012] FIG. 2 is an exploded perspective view of the intake valve
timing control apparatus.
[0013] FIG. 3 is a partial side sectional view of the intake valve
timing control apparatus, taken along a plane passing through an
axis of rotation of the intake valve timing control apparatus.
[0014] FIG. 4 is a front view of the intake valve timing control
apparatus in a most retarded state, as viewed along the axis of
rotation.
[0015] FIG. 5 is a front view of the intake valve timing control
apparatus in a most advanced state, as viewed along the axis of
rotation.
[0016] FIGS. 6A, 6B and 6C are views of a housing body of the
intake valve timing control apparatus, where FIG. 6A is a front
view along the axis of rotation, FIG. 6B is a side sectional view
taken along a plane indicated by F6B-F6B in FIG. 6A, and FIG. 6C is
a rear view along the axis of rotation.
[0017] FIG. 7 is a perspective view of a first workpiece for the
housing body of the intake valve timing control apparatus or a
housing body of the exhaust valve timing control apparatus.
[0018] FIG. 8 is a perspective view of a third workpiece for the
housing body of the intake valve timing control apparatus or
exhaust valve timing control apparatus.
[0019] FIGS. 9A and 9B are views of a vane rotor of the intake
valve timing control apparatus, where FIG. 9A is a front view along
the axis of rotation, and FIG. 9B is a side sectional view taken
along a plane indicated by F9B-F9B in FIG. 9A.
[0020] FIG. 10 is a perspective view of a first workpiece for the
vane rotor of the intake valve timing control apparatus or a vane
rotor of the exhaust valve timing control apparatus.
[0021] FIG. 11 is a perspective view of a second workpiece for the
vane rotor of the intake valve timing control apparatus or exhaust
valve timing control apparatus.
[0022] FIG. 12 is a perspective view of a front plate of the intake
valve timing control apparatus.
[0023] FIG. 13 is a partial side sectional view taken along a plane
passing through a central longitudinal axis of a positioning pin
according to the embodiment that is fixed to an axial end surface
of an intake camshaft.
[0024] FIG. 14 is a partial side sectional view taken along a plane
passing through a central longitudinal axis of a lock mechanism
according to the embodiment.
[0025] FIG. 15 is a partial side sectional view of the exhaust
valve timing control apparatus, taken along a plane passing through
an axis of rotation of the exhaust valve timing control
apparatus.
[0026] FIG. 16 is a front view of the exhaust valve timing control
apparatus in a most advanced state, as viewed along the axis of
rotation.
[0027] FIG. 17 is a front view of the exhaust valve timing control
apparatus in a most retarded state, as viewed along the axis of
rotation.
[0028] FIGS. 18A, 18B and 18C are views of the housing body of the
exhaust valve timing control apparatus, where FIG. 18A is a front
view along the axis of rotation, FIG. 18B is a side sectional view
taken along a plane indicated by F18B-F18B in FIG. 18A, and FIG.
18C is a rear view along the axis of rotation.
[0029] FIGS. 19A and 19B are views of the vane rotor of the exhaust
valve timing control apparatus, where FIG. 19A is a front view
along the axis of rotation, and FIG. 19B is a side sectional view
taken along a plane indicated by F19B-F19B in FIG. 19A.
DETAILED DESCRIPTION OF THE INVENTION
[0030] <<Construction of Valve Timing Control
Apparatus>> FIG. 1 is a front view of a valve timing control
apparatus according to an embodiment of the present invention in
which a pair of intake valve timing control apparatuses 1a and a
pair of exhaust valve timing control apparatuses 1b are mounted to
an internal combustion engine, as viewed in an axial direction of
the internal combustion engine. The axial direction is an axial
direction of a crankshaft of the internal combustion engine, which
is identical to an axial direction of intake camshafts or exhaust
camshafts. The intake valve timing control apparatus 1a and exhaust
valve timing control apparatus 1b are individually or collectively
referred to as valve timing control apparatus or system 1. The
internal combustion engine is arranged in a vehicle engine room so
that the axial directions of the crankshafts and camshafts are
perpendicular to a vehicle longitudinal direction. In other words,
FIG. 1 is a view of valve timing control apparatus 1 in a vehicle
lateral direction. In a typical motor vehicle, an engine room has a
unique three-dimensional curved side wall because of provision of
frames (structural members or skeletal members), so that the side
wall has a portion projecting inwardly in the engine room. FIGS. 1
and 15 show an example in which a projection W1 projects from an
engine room side wall W close to one exhaust valve timing control
apparatus 1b, as schematically shown by a long-dashed short-dashed
line. FIG. 1 shows a section of engine room side wall W (projection
W1) taken along the plane indicated by F1-F1 in FIG. 15, which is a
view in the vehicle lateral direction. FIG. 15 shows a section of
projection W1 of engine room side wall W taken along the plane
indicated by F15-F15 in FIG. 1 and parallel to the axial direction
of the internal combustion engine (X-axis), which is a view in the
vehicle lateral direction. The internal combustion engine is a
V-type DOHC engine in which a pair of cylinder banks are arranged
in a V-shape spreading from the crankshaft as viewed in the axial
direction, and each cylinder bank is provided with a camshaft for
actuating intake valves, or intake camshaft 3a, and a camshaft for
actuating exhaust valves, or exhaust camshaft 3b. Intake camshafts
3a and 3a are arranged inside of exhaust camshafts 3b and 3b in a
lateral direction of a cylinder block of the internal combustion
engine, as shown in FIG. 1.
[0031] Valve timing control apparatus 1 is mounted to one axial end
of the internal combustion engine. Specifically, each intake valve
timing control apparatus 1a is fixedly mounted to an axial end of
respective intake camshaft 3a, whereas each exhaust valve timing
control apparatus 1b is fixedly mounted to an axial end of
respective exhaust camshaft 3b. Valve timing control apparatus 1
may be provided with only one of intake valve timing control
apparatus 1a and exhaust valve timing control apparatus 1b.
However, provision of both of intake valve timing control apparatus
1a and exhaust valve timing control apparatus 1b makes it possible
to control the valve timing in a more flexible manner. Each intake
valve timing control apparatus 1a is provided with a pulley 100.
Similarly, each exhaust valve timing control apparatus 1b is
provided with a pulley 100. A timing belt 1010 is put over pulleys
100, as indicated by long dashed double-short dashed lines in FIG.
1, so that intake valve timing control apparatus 1a and exhaust
valve timing control apparatus 1b are connected to one another.
Timing belt 1010 is a toothed belt (or cogged belt) made of rubber,
but may be alternatively made of a material preferable for weight
reduction and cost reduction, such as a synthetic resin. Timing
belt 1010 transmits torque from the crankshaft to pulleys 100. Each
of intake valve timing control apparatuses 1a and exhaust valve
timing control apparatuses 1b is rotated by the torque transmitted
through the pulley 100. While rotating, each of intake valve timing
control apparatuses 1a and exhaust valve timing control apparatuses
1b optimally controls variable opening and closing timings of
respective intake valves or exhaust valves according to a state of
operation of the internal combustion engine. The combination of
pulley 100 and timing belt 1010 may be replaced with a combination
of a sprocket and a chain as a means for transmitting torque from
the crankshaft to a housing "HSG" of intake valve timing control
apparatus 1a or exhaust valve timing control apparatus 1b.
Alternatively, the torque from the crankshaft may be transmitted
indirectly, for example, in such a manner that the torque from the
crankshaft is transmitted directly to one of intake valve timing
control apparatus 1a and exhaust valve timing control apparatus 1b,
and transmitted through the one to the other.
[0032] In the following, an X-axis is assumed to extend in the
axial direction of the internal combustion engine, or in the axial
direction of camshaft 3a or 3b. Along the X-axis, a positive
direction is defined as a direction from an axial end of camshaft
3a or 3b where no intake valve timing control apparatus 1a or no
exhaust valve timing control apparatus 1b is provided to an axial
end of camshaft 3a or 3b where intake valve timing control
apparatuses 1a and exhaust valve timing control apparatuses 1b are
mounted.
[0033] <Construction of Intake Valve Timing Control
Apparatus> The following describes construction of intake valve
timing control apparatus 1a with reference to FIGS. 2 to 14. FIG. 2
is an exploded perspective view of intake valve timing control
apparatus 1a, where parts are arranged in the axial direction. FIG.
3 is a partial side sectional view of intake valve timing control
apparatus 1a, taken along a plane passing through an axis of
rotation "O" (shown in FIG. 4) of intake valve timing control
apparatus 1a, i.e. taken along a plane indicated by a long dashed
short dashed line F3-F3 in FIG. 4. FIGS. 4 and 5 are front views of
intake valve timing control apparatus 1a under a condition that a
front plate 8, etc. are removed, as viewed from the X-axis positive
side. In FIGS. 3 and 4, fluid passages and grooves which are formed
in intake camshaft 3a, etc. are indicated by broken lines.
[0034] Intake camshaft 3a is made of an iron-based material, and
rotatably supported on bearings in a laterally-inside portion of an
upper end portion of the cylinder head of the internal combustion
engine. Intake camshaft 3a is formed with drive cams (intake cams)
at the outside peripheral surface, which are located to face or
conform to positions of the intake valves. When intake camshaft 3a
is rotated, the intake cams open and close the intake valves via
valve lifters, rocker arms, etc. Intake valve timing control
apparatus 1a is fixedly attached to an X-axis positive side axial
end portion 30 of intake camshaft 3a by three camshaft bolts 33, 34
and 35. Each camshaft bolt 33, 34 or 35 is a hexagonal-head bolt
having a head 331, 341 or 351 in the form of a regular hexagonal
prism, and a shank formed with a male thread at its outside
periphery. Each head 331, 341 or 351 is formed integrally with a
plane washer 332, 342 or 352, for protection of a bearing surface,
etc. The hexagonal-head bolt may be replaced with another fixing
means. Each washer 332, 342 or 352 is optional. The axial end
portion 30 of intake camshaft 3a is formed with: three bolt holes
32 through which camshaft bolts 33, 34 and 35 are inserted; a
portion constituting a retard passage 20; and a portion
constituting an advance passage 21. Each bolt hole 32 is formed
with a female thread at its inside periphery, and substantially
evenly spaced with one another in the circumferential direction
around the axis of rotation O, extending from an X-axis positive
side axial end surface 300 of axial end portion 30 to a
predetermined depth in the X-axis direction. The axial end portion
30 of intake camshaft 3a is formed with grooves 200, 204, 210 and
214, first fluid passages 202 and 212, and second fluid passages
201, 203, 211 and 213. Each groove 200, 204, 210 or 214 is an
annular circumferential groove formed at the outside periphery of
the axial end portion 30 to a predetermined depth, extending all
around the outside periphery in the circumferential direction.
Grooves 200 and 204 constitute retard passage 20, whereas grooves
210 and 214 constitute advance passage 21. Grooves 210 and 200 are
arranged in this order as followed from the X-axis negative side to
the X-axis positive side, and located in the cylinder head and
outside of intake valve timing control apparatus 1a. Grooves 214
and 204 are arranged in this order as followed from the X-axis
negative side to the X-axis positive side, and located at an X-axis
positive side portion of the axial end portion 30 to which a vane
rotor 4 is attached. Each first fluid passage 202 or 212 is an
axial fluid passage formed in the axial end portion 30, extending
in the X-axis direction. First fluid passage 202 constitutes retard
passage 20, whereas first fluid passage 212 constitutes advance
passage 21. Each second fluid passage 201, 203, 211 or 213 is a
radial fluid passage formed in the axial end portion 30, extending
in a radial direction perpendicular to the X-axis. Second fluid
passages 201 and 203 constitute retard passage 20, whereas second
fluid passages 211 and 213 constitute advance passage 21. Each
first fluid passage 202 or 212 has a smaller diameter than bolt
hole 32, extending from the axial end surface 300 in the negative
x-axis direction. In other words, each first fluid passage 202 or
212 extends in the axial end portion 30, and has an opening at the
axial end surface 300. First fluid passage 202 is arranged between
bolt hole 32 for camshaft bolt 34 and bolt hole 32 for camshaft
bolt 35 in the circumferential direction around the axis of
rotation O. Specifically, the distance from the axis of rotation O
to the central axis of first fluid passage 202 is substantially
equal to the distance from the axis of rotation O to the central
axis of each bolt hole 32, and the central axis of first fluid
passage 202 is located on a circular line passing through the
central axis of each bolt hole 32, and in a substantially central
position between camshaft bolts 34 and 35. The size of first fluid
passage 202 in the X-axis direction is set so that first fluid
passage 202 overlaps with groove 200 in the X-axis direction, and
further extends to a position slightly on the X-axis negative side
of groove 200. On the other hand, first fluid passage 212 is
arranged between bolt hole 32 for camshaft bolt 33 and bolt hole 32
for camshaft bolt 35 in the circumferential direction, similar to
first fluid passage 202. The size of first fluid passage 212 in the
X-axis direction is set so that first fluid passage 212 overlaps
with groove 210 in the X-axis direction, and further extends to a
position slightly on the X-axis negative side of groove 210. Second
fluid passage 201 extends through between groove 200 and first
fluid passage 202, for fluid communication therebetween. Second
fluid passage 203 extends through between groove 204 and first
fluid passage 202, for fluid communication therebetween. Second
fluid passage 213 extends through between groove 214 and first
fluid passage 212, for fluid communication therebetween.
[0035] Intake valve timing control apparatus 1a controls variable
valve timing of the intake valves by continuously changing a
rotational phase of intake camshaft 3a with respect to the
crankshaft by supplied working fluid. Intake valve timing control
apparatus 1a includes housing HSG formed with pulley 100, and a
vane rotor 4 as a driven member mounted in housing HSG. Pulley 100
transmits torque from the crankshaft to housing HSG. Vane rotor 4
is mounted inside of housing HSG for relative rotation with respect
to housing HSG. The torque is transmitted from housing HSG to vane
rotor 4 through working fluid. Vane rotor 4 transmits the torque to
intake camshaft 3a. Vane rotor 4 constitutes a phase change
mechanism for changing the rotational phase of intake camshaft 3a
with respect to housing HSG or the crankshaft by supply and
drainage of working fluid. The phase change mechanism may be of
another type, such as a trochoid type. In other words, the driven
member of intake valve timing control apparatus 1a is not limited
to a vane rotor. For example, the relative rotational phase between
the housing and the camshaft may be changed according to movement
of a member in the axial direction of the valve timing control
apparatus, wherein the member has a helical gear (spline). Intake
valve timing control apparatus 1a is a hydraulic actuator or
hydraulically driven type phase actuation mechanism which is
operated by receipt of supply of working fluid from a hydraulic
fluid supply and drainage mechanism 2 or drainage of working fluid
to hydraulic fluid supply and drainage mechanism 2. Supply and
drainage of working fluid by hydraulic fluid supply and drainage
mechanism 2 is controlled by a controller "CU" as a control
means.
[0036] Housing HSG includes a housing body 10, a front plate 8 as a
sealing plate, and a rear plate 9 as a sealing plate. Housing body
10 has a hollow cylindrical shape with open longitudinal ends. This
is because housing body 10 is formed by extrusion as described in
detail below. Front plate 8 has a disc shape, which is fixed to a
front longitudinal end (X-axis positive side end) of housing body
10, for sealing and closing the opening of housing body 10. Rear
plate 9 has a disc shape, which is fixed to a rear longitudinal end
(X-axis negative side end) of housing body 10, for sealing and
closing the opening of housing body 10. Housing body 10 may be
alternatively formed with an opening only at one longitudinal end.
Namely, housing body 10 may have a hollow cylindrical shape with a
closed bottom, or a cup-shape. In other words, one of the sealing
plates may be formed integrally with housing body 10. Housing body
10 is not limited to a cylindrical shape. Housing body 10 is formed
integrally with pulley 100 extending over the entire length of the
outside periphery of housing body 10 in the X-axis direction.
Pulley 100 includes a plurality of projections (teeth) and recesses
extending in the X-axis direction, which are arranged in the
circumferential direction, and substantially evenly spaced, thus
forming a gear or cogged belt wheel over which timing belt 1010 is
wound. Pulley 100 is not limited to the integral forming with
housing body 10, but may be formed separately from and coupled to
housing body 10. The torque transmission based on tooth meshing may
be replaced with a construction in which torque is transmitted
frictionally through surface-to-surface contact between a belt and
a pulley. For example, a housing body is formed with a pulley that
has a groove at a central position in its width direction, and a
belt that has no tooth and has a cross section fitted to the pulley
having the groove. The combination of pulley 100 and toothed timing
belt 1010 according to the embodiment is advantageous in
enhancement in the efficiency of power transmission. When pulley
100 is rotated by the crankshaft, pulley 100 and housing body 10
rotate as a solid unit in a clockwise direction as viewed in FIG. 4
or in a direction of an arrow shown in FIG. 1.
[0037] FIGS. 6A, 6B and 6C are views of housing body 10, where FIG.
6A is a front view along the axis of rotation from the X-axis
positive side, FIG. 6B is a side sectional view taken along a plane
indicated by F6B-F6B in FIG. 6A, and FIG. 6C is a rear view along
the axis of rotation from the X-axis negative side. FIGS. 7 and 8
are perspective views of workpieces during a process of
manufacturing the housing body 10. Housing body 10 is manufactured
by a process including an extrusion operation, a coating operation,
a cutting-off operation, and a carving operation, which are carried
out in this order. First, in the extrusion operation, an
aluminum-based metal material, such as aluminum, or aluminum alloy
such as A6000 or A7000, is heated and extruded from a mold, to form
an aluminum extrusion or first workpiece P1 shown in FIG. 7, which
extends in the direction of extrusion, and in which continuous
shapes of first, second and third shoes 11, 12 and 13 are formed at
an inside periphery, and a continuous shape of pulley 100 is formed
at an outside periphery. Second, in the coating operation, the
entire surface, i.e. the inside and outside peripheral surfaces of
first workpiece P1 are applied with anodic oxidation treatment or
alumilite treatment, to form a second workpiece P2 which has anodic
oxide coating films at the inside and outside peripheries. Third,
in the cutting-off operation, second workpiece P2 is cut laterally
at intervals of a predetermined distance along the axial direction,
to form a plurality of identically-shaped third workpieces P3, as
shown in FIG. 8. Finally, in the carving operation, each third
workpiece P3 is applied with carving or cutting, to form a fitting
recess 101, bolt holes 110, 120 and 130, and a positioning recess
114, as described in detail below, and thereby form a final shape
of housing body 10 shown in FIGS. 6A, 6B and 6C. In this way, each
housing body 10 in the final shape is formed with an anodic oxide
coating film layer at the inside and outside peripheral surfaces,
but the cut surfaces obtained by the cutting-off operation (the
axial end surfaces in the X-axis direction) are formed with no
anodic oxide coating film layer. Instead, a base layer of the
aluminum-based metal material is exposed at the cut surfaces. As
shown in FIGS. 6B and 6C, the open X-axis negative side end of
housing body 10 is formed with fitting recess 101 which is a
cylindrical recess having a center at the axis of rotation O, and
extending to a predetermined depth in the X-axis direction.
Specifically, fitting recess 101 is formed by cutting away a part
of third workpiece P3, into a cylindrical shape having a
predetermined radius R about the axis of rotation O, and having a
predetermined depth in the X-axis positive direction. Fitting
recess 101 includes a bottom surface 102 having a circular shape,
and an inside peripheral surface 103 surrounding the bottom surface
102. Inside peripheral surface 103 has the radius R with respect to
the axis of rotation O. Where Ri represents a radius of the inside
peripheral surface of housing body 10 about the axis of rotation O,
and Ro represents a maximum radius of housing body 10 which is a
distance between a tooth tip of pulley 100 and the axis of rotation
O, it holds that Ro:Ri.apprxeq.10:8. It also holds that
(Ro+Ri)/2.apprxeq.R. In other words, fitting recess 101 extends in
the radial direction of housing body 10 substantially to a midpoint
between the inside and outside peripheral surfaces of housing body
10. On the other hand, where L represents an axial length L of
housing body 10, and L2 represents a distance between the bottom
surface 102 of fitting recess 101 and the X-axis negative end
surface 104 of housing body 10, it holds that L:L2.apprxeq.10:2. In
other words, fitting recess 101 is formed to extend in the X-axis
direction over a range of about 20% or more of the axial length of
housing body 10. The axial length of the inside periphery of
housing body 10, L1, is shorter than that of the outside periphery,
or that of pulley 100, L (L1<L). In other words, the axial
length of pulley 100 in the X-axis direction, L, is set longer than
that of the inside periphery of housing body 10, L1. The inside
periphery of housing body 10 is formed integrally with first,
second and third shoes 11, 12 and 13 which extend inwardly in the
radial direction. Specifically, first, second and third shoes 11,
12 and 13 are arranged in a circumferential direction or direction
of rotation about the axis of rotation O, at substantially even
intervals, extending from the inside periphery of housing body 10
inwardly toward the axis of rotation O. First, second and third
shoes 11, 12 and 13 are arranged in this order in the clockwise
direction in FIG. 4. Each of first, second and third shoes 11, 12
and 13 extends in the X-axis direction, and has a cross section
having a substantially trapezoidal shape. The width of each of
first, second and third shoes 11, 12 and 13 in the circumferential
direction is set substantially equal to each other. The space
between second shoe 12 and third shoe 13, and the space between
third shoe 13 and first shoe 11, are set substantially equal to
each other. The space between first shoe 11 and second shoe 12 is
set slightly larger than the other spaces, for accommodating a
first vane 41 having a wider width, which is described in detail
below. First shoe 11 is formed with a bolt hole 110 substantially
at the center of the trapezoidal cross section, where bolt hole 110
extends through the first shoe 11. Similarly, second shoe 12 and
third shoe 13 are formed with a through bolt hole 120 and a through
bolt hole 130 respectively. The X-axis positive side end surface of
each of first, second and third shoes 11, 12 and 13 is fixedly
attached to front plate 8. The X-axis negative side end surface of
each of first, second and third shoes 11, 12 and 13, which is a
part of the bottom surface 102 of fitting recess 101, is fixedly
attached to rear plate 9. As viewed from the X-axis positive side,
or as shown in FIG. 6A, second shoe 12 and third shoe 13 are formed
with a flat portion 121 and a flat portion 131 in their clockwise
sides, respectively. Each of flat portion 121 and flat portion 131
is in a straight line passing through the axis of rotation O of
housing body 10, as viewed in the X-axis direction. On the other
hand, the clockwise side of first shoe 11 is formed with a rounded
portion 112 at a root portion in an outward position in the radial
direction of housing body 10, and formed with a recess 113 at a tip
portion in an inward position in the radial direction of housing
body 10, as viewed in FIG. 6B. First shoe 11 is formed with a flat
portion 111 between rounded portion 112 and recess 113, similar to
second shoe 12 and third shoe 13. Rounded portion 112 has an
inwardly curved and substantially arced edge, as viewed in the
X-axis direction. The edge of rounded portion 112 gradually rises
from the inside peripheral surface of housing body 10 to merge into
the clockwise side edge of first shoe 11. As shown in FIG. 6C, on
the X-axis negative side of first shoe 11, rounded portion 112 in
bottom surface 102 of fitting recess 101 is formed with a
positioning recess 114 adjacent to bolt hole 110. Positioning
recess 114 has a smaller diameter than bolt hole 110. Rounded
portion 112 serves to allow arrangement of positioning recess 114
in first shoe 11, and enhance rigidity of the root portion of first
shoe 11 in the circumferential direction, so as to bear a stress
resulting from contact between first vane 41 and first shoe 11. As
viewed from the X-axis positive side, or as viewed in FIG. 6A, the
counterclockwise sides of first, second and third shoes 11, 12 and
13 are formed with recesses 115, 125 and 135, respectively.
Recesses 115, 125 and 135 are relatively wide grooves extending
over the entire axial length of housing body 10 in the X-axis
direction. As shown in FIG. 6A, as viewed in the X-axis direction,
the tips 116, 126 and 136 of first, second and third shoes 11, 12
and 13 have radially inside surfaces facing the axis of rotation O,
which are inwardly curved like an arc fitted with an outside
peripheral surface of a rotor 40 of vane rotor 4, which is
described in detail below. The tip 116 of first shoe 11 is formed
with a sealing groove 117 which extends in the X-axis direction. A
sealing member 118 and a sealing spring such as a leaf spring 119
not shown are fitted and retained in sealing groove 117. Sealing
member 118 is in liquid-tight sliding contact with the outside
peripheral surface of rotor 40. Leaf spring 119 presses the sealing
member 118 onto the outside peripheral surface of rotor 40. Sealing
member 118 is formed of a grass fiber plastic, having a
substantially U-shape. Similarly, the tips 126 and 136 of second
shoe 12 and third shoe 13 are formed with sealing grooves 127 and
137, sealing members 128 and 138, and leaf springs 129 and 139,
respectively, as shown in FIGS. 3 and 4.
[0038] Front plate 8 is formed by forging an iron-based metal
material, such as an iron alloy, into a thinner disc shape than
rear plate 9, wherein the iron-based metal material is harder than
aluminum-based metal materials. Front plate 8 closes and seals the
front axial end of housing body 10, namely closes and seals the
X-axis positive side ends of first, second and third advance
chambers A1, A2 and A3, and first, second and third retard chambers
R1, R2 and R3 defined in housing body 10. In the present
description, "hardness" of an object means a degree of difficulty
of changing the outline of the object, and can be measured by a
commonly known hardness test. "Wear" of an object means that a
surface of the object is worn, and can be categorized in terms of
dynamics into sliding wear, collision wear, etc. "Wear resistance"
of an object can be measured by a suitable test selected according
to the category, or may be determined indirectly based on the
hardness test. As shown in FIG. 3, the diameter of front plate 8 is
set slightly larger than the diameter (specifically, the diameter
of tooth top circle) of pulley 100, so that over the entire
circumference of pulley 100, an outside periphery 80 of front plate
8 projects from pulley 100 outwardly in the radial direction as
viewed in the X-axis direction. As shown in FIG. 2, front plate 8
is formed with a female thread portion 82 located substantially at
the center of the X-axis positive side surface of front plate 8.
Female thread portion 82 projects in the X-axis positive direction.
Female thread portion 82 is formed with a large-diameter hole 81 at
its center, which extends through front plate 8 in the X-axis
direction, and through which camshaft bolts 33, 34 and 35 (see FIG.
4) are inserted to pass, when intake valve timing control apparatus
1a is assembled. Large-diameter hole 81 of female thread portion 82
is formed with a female thread 820 to which a male thread 700 of a
cap 7 is screwed. The annular X-axis positive side surface of
female thread portion 82 is formed with an annular sealing ring
groove 821. Front plate 8 is formed with bolt holes 83, 84 and 85
located between female thread portion 82 and outside periphery 80.
Bolt holes 83, 84 and 85 are arranged and evenly spaced in the
circumferential direction as viewed in the X-axis direction,
through which bolts b1, b2 and b3 inserted to pass. In the X-axis
direction, bolt holes 83, 84 and 85 are located to face or conform
to bolt holes 110, 120 and 130, which are formed in first, second
and third shoes 11, 12 and 13 of housing body 10, respectively.
Front plate 8 is formed with thicker portions 86, 87 and 88 around
bolt holes 83, 84 and 85 respectively. Thicker portions 86, 87 and
88 are slightly thicker than the other portion in the X-axis
direction, in order to bear the axial force applied by bolts b1, b2
and b3. Each of thicker portions 86, 87 and 88 has a shape that is
spreading inwardly in the radial direction, and continuous with
female thread portion 82. In other words, front plate 8 is formed
as thin as possible, except thicker portions 86, 87 and 88 for
providing a strength enough to bear the axial force applied by
bolts b1, b2 and b3. FIG. 12 is a perspective view of front plate 8
as viewed from the X-axis negative side. The X-axis negative side
surface of front plate 8 is formed with an annular sealing ring
groove 89. Annular sealing ring groove 89 has a shape including
three inwardly curved sections like a three-leaved clover, so that
annular sealing ring groove 89 extends circumferentially along the
outside periphery 80 with a slight radial clearance r, and passes
inside of bolt holes 83, 84 and 85, i.e. passes between the axis of
rotation O and each of bolt holes 83, 84 and 85.
[0039] Cap 7 is formed by forging an iron-based metal material into
a hollow cylindrical shape with a bottom, and detachably attached
to front plate 8, thus constituting a front plate (in a broad
sense) together with front plate 8. Cap 7 includes a male thread
portion 70, a division wall portion 71, and a flange 72. Male
thread portion 70 has a hollow cylindrical shape, extending in the
X-axis direction. Division wall portion 71 closes the opening of
male thread portion 70. Flange 72 spreads outwardly in the radial
direction from the X-axis positive side end of male thread portion
70. Male thread portion 70 is formed with a male thread 700 at the
outside periphery. Division wall portion 71 is formed integrally
with a bolt head portion 710 substantially at the center of the
X-axis positive side surface, which has the form of a regular
hexagonal prism. Bolt head portion 710 is turned so that cap 7 is
screwed into front plate 8, i.e. male thread 700 of cap 7 is
screwed into female thread 820 of front plate 8, and that
large-diameter hole 81 of front plate 8 is closed and sealed. Under
this condition, the X-axis negative side surface of flange 72 faces
the X-axis positive side axial end surface of female thread portion
82, and the X-axis negative side axial end surface of male thread
portion 70 is located slightly on the X-axis positive side of the
X-axis negative side surface of front plate 8, as shown in FIG. 3.
Cap 7 is formed with a recess 73 at the X-axis negative side,
wherein recess 73 is defined by the X-axis negative side surface of
division wall portion 71 as a bottom surface, and the inside
periphery of the X-axis negative side portion of male thread
portion 70 as a side wall. The depth or size in the X-axis
direction, of recess 73, is half or more of the height or size in
the X-axis direction, of head 331, 341 or 351 of each camshaft bolt
33, 34 or 35.
[0040] Rear plate 9 is fixedly inserted in fitting recess 101 of
housing body 10, so as to close and seal the rear axial open end of
housing body 10 closer to intake camshaft 3a, i.e. the X-axis
negative side open end of first, second and third advance chambers
A1, A2 and A3, and first, second and third retard chambers R1, R2
and R3 which are defined in housing body 10. Rear plate 9 is formed
by forging an iron-based metal material such as S45C or S48 that is
harder than the aluminum-based metal material of vane rotor 4. Rear
plate 9 includes a plate body 90 and a cylindrical portion 91.
Cylindrical portion 91 has a cylindrical shape extending in the
X-axis negative direction from the X-axis negative side of plate
body 90. As viewed in the X-axis direction, cylindrical portion 91
is located substantially at the center of plate body 90, coaxially
with the axis of rotation O. Cylindrical portion 91 is formed with
a through hole 92 inside, through which intake camshaft 3a is
inserted to pass. Through hole 92 is formed to extend in the X-axis
direction, and pass through rear plate 9, substantially coaxially
with the axis of rotation O. The diameter of through hole 92 is set
slightly smaller than that of large-diameter hole 81 of front plate
8. The length of plate body 90 in the X-axis direction is set at
most slightly larger than the depth of fitting recess 101 (the
length in the X-axis direction, L2). The length of an outside
peripheral surface 93 of plate body 90 in the X-axis direction is
set substantially equal to the depth of fitting recess 101 (L2).
The diameter of plate body 90 is set substantially equal to the
diameter of fitting recess 101 (R.times.2). Plate body 90 is formed
with female thread portions 901, 902 and 903 around cylindrical
portion 91, which are arranged and evenly spaced in the
circumferential direction. Female thread portions 901, 902 and 903
are formed with bolt holes extending through plate body 90 in the
X-axis direction. The bolt holes are formed with female threads in
the inside peripheral surfaces, respectively. Male threads of an
X-axis negative side end portions of bolts b1, b2 and b3 are
screwed into the female threads respectively. As viewed in the
X-axis direction, female thread portions 901, 902 and 903 (bolt
holes) are located to face or conform to the bolt holes 110, 120
and 130 of first, second and third shoes 11, 12 and 13, and bolt
holes 83, 84 and 85 of front plate 8. As shown in FIG. 2, plate
body 90 is formed with a recess 900 which is located adjacent to
and in the clockwise direction from one female thread portion 901
which faces bolt hole 110 of first shoe 11, as viewed from the
X-axis positive side. Recess 900 is formed to extend in the X-axis
negative direction to a predetermined depth in plate body 90. The
outside peripheral surface 93 of plate body 90 is formed with a
sealing ring groove 906 which extends in the circumferential
direction. The X-axis positive side surface of plate body 90 is
formed with annular sealing ring grooves 907, 908 and 909 which
extend circumferentially around female thread portions 901, 902 and
903 respectively. Plate body 90 is formed with a pin hole 904
having a bottom, which is located at the outside periphery of the
X-axis positive side surface of plate body 90, and adjacent to and
in the counterclockwise direction from recess 900. Pin hole 904 is
located between recess 900 and female thread portion 901, and in a
position in the radial direction of plate body 90 which faces
positioning recess 114 of housing body 10 shown in FIG. 6C. A
positioning pin 905 is press-fitted and fixed in pin hole 904.
Positioning pin 905 is a dowel pin whose longitudinal end projects
to a predetermined height in the X-axis positive direction from the
X-axis positive side surface of plate body 90. The diameter of the
longitudinal end of positioning pin 905 is set slightly smaller
than positioning recess 114, and adapted to be inserted and fitted
from the X-axis negative side into positioning recess 114. The
diameter of the longitudinal end of positioning pin 905 and the
diameter of positioning recess 114 are set so as to prevent play
between housing body 10 and rear plate 9 in the circumferential
direction under a condition that positioning pin 905 is inserted
and fitted in positioning recess 114. Pin hole 904 is located in
rear plate 9 so that under the condition that positioning pin 905
is inserted and fitted in positioning recess 114, bolt hole 110 of
first shoe 11 of housing body 10 is in substantially the same
position as female thread portion 901 of rear plate 9 as viewed in
the X-axis direction, and that when flat portion 415 of first vane
41 of vane rotor 4 is in contact with flat portion 111 of first
shoe 11 as shown in FIG. 4, a slide hole 501 of first vane 41 is in
substantially the same position as recess 900 of rear plate 9, as
viewed in the X-axis direction. Pin hole 904 is located closer to
first retard chamber R1 than sealing ring grooves 906 and 907, and
positioning pin 905 is located adjacent to recess 900.
[0041] Front plate 8, housing body 10, and rear plate 9 are fixed
together in the X-axis direction by bolts b1, b2 and b3. Bolts b1,
b2 and b3 are inserted from the X-axis positive side to pass
through bolt holes 83, 84 and 85 of front plate 8, and bolt holes
110, 120 and 130 of housing body 10, and screwed into female thread
portions 901, 902 and 903 of rear plate 9, so as to fix front plate
8 and rear plate 9 to housing body 10. Sealing rings S1, S2 and S3
are inserted between housing body 10 and rear plate 9, and between
front plate 8 and housing body 10. A sealing ring S4 is inserted
between cap 7 and front plate 8. Sealing rings S1, S2, S3 and S4
are annular sealing members to be mounted, each of which is an
O-ring having a circular cross section in this example. Sealing
rings S1, S2, S3 and S4 are formed of a rubber such as an acrylic
rubber or fluorine rubber, which is superior in durability against
working fluid. The rubber may be a nitrile rubber, etc. Each
sealing rings S1, S2, S3 or S4 is not limited to O-rings, but may
have a different cross section. Sealing rings S1 and S2 are
disposed between rear plate 9 and housing body 10. Sealing ring S1
is arranged between the inside peripheral surface 103 of fitting
recess 101 of housing body 10 and outside peripheral surface 93 of
plate body 90 of rear plate 9. Each sealing ring S2 is arranged
between a portion surrounding a respective one of female thread
portions 901, 902 and 903 in the X-axis positive side end surface
of rear plate 9 and the X-axis negative side end surface (bottom
surface 102 of fitting recess 101) of a respective one of first,
second and third shoes 11, 12 and 13 of housing body 10. Sealing
ring S3 is arranged between portions of front plate 8 and housing
body 10 which face each other, i.e. between the X-axis negative
side end surface of front plate 8 and the X-axis positive side end
surface 105 of housing body 10 (first, second and third shoes 11,
12 and 13). Sealing ring S3 has the form of a three-leaved clover
which is substantially identical to the form of annular sealing
ring groove 89 of front plate 8. Sealing ring S4 is arranged
between the X-axis positive side end surface of female thread
portion 82 of front plate 8 and the X-axis negative side end
surface of flange 72 of cap 7.
[0042] As shown in FIG. 3, cylindrical portion 91 of rear plate 9
is provided with an oil seal "OS" at the outside peripheral surface
of its X-axis negative side portion, and is rotatably supported
through the oil seal OS by the cylinder block of the internal
combustion engine.
[0043] FIGS. 9A and 9B are views of vane rotor 4, where FIG. 9A is
a front view along the axis of rotation from the X-axis positive
side, and FIG. 9B is a side sectional view taken along a plane
indicated by F9B-F9B in FIG. 9A. In FIG. 9A, fluid passages 408 and
409 formed inside the vane rotor 4, and a recess 44 formed the
X-axis negative side of vane rotor 4 are indicated by broken lines.
In FIG. 9B, the opening of one of retard fluid passages 408 and the
opening of one of advance fluid passages 409 are shown. FIGS. 10
and 11 are perspective views of workpieces during a process of
manufacturing the vane rotor 4. Vane rotor 4 is manufactured by a
process including an extrusion operation, a cutting-off operation,
a carving operation, and a coating operation, which are carried out
in this order. First, in the extrusion operation, an aluminum-based
metal material as used for housing body 10 is extruded from a mold,
to form a first workpiece Q1 shown in FIG. 10, which extends in the
direction of extrusion, in which continuous shapes of rotor 40 and
first, second and third vanes 41, 42 and 43 are formed. Second, in
the cutting-off operation, first workpiece Q1 is cut laterally at
intervals of a predetermined distance along the axial direction, to
form a plurality of identically-shaped second workpieces Q2
including a rotor and vanes, as shown in FIG. 11. Third, in the
carving operation, second workpiece Q2 is applied with carving or
cutting, to form a boss portion 401, a camshaft insertion hole 402,
a slide hole 501, etc., and thereby form a final shape of vane
rotor 4 shown in FIGS. 9A and 9B. Finally, in the coating
operation, the entire surface of second workpiece Q2 is applied
with anodic oxidation treatment, to form a third workpiece Q3 which
has an anodic oxide coating film layer. When vane rotor 4 is
finalized, the anodic oxide coating film layer is formed in the
axial end surfaces of vane rotor 4, and also in the surface of boss
portion 401, camshaft insertion hole 402, slide hole 501, etc. Vane
rotor 4 is a driven member or driven rotator which can rotate
relative to pulley 100 or housing HSG, and serves as a vane member
which rotates in the clockwise direction in FIG. 4 as a solid unit
with intake camshaft 3a. Vane rotor 4 includes: rotor 40 fixed to
intake camshaft 3a with three camshaft bolts 33, 34 and 35,
substantially coaxially with intake camshaft 3a; and first, second
and third vanes 41, 42 and 43 projecting outwardly in radial
directions from rotor 40, wherein first, second and third vanes 41,
42 and 43 are adapted to receive hydraulic pressure.
[0044] Rotor 40 includes a rotor body 400 and a boss portion 401
which are arranged coaxially. Rotor body 400 is a body of rotor 40,
having a cylindrical shape. In the X-axis direction, the length of
rotor body 400 is substantially equal to the length of housing body
10 excluding the length of the fitting recess 101, L1. The outside
diameter (i.e. the diameter of the outside periphery) of rotor body
400 is slightly larger than the diameter of large-diameter hole 81
of front plate 8. Boss portion 401 is cylindrically formed to
project from rotor body 400 in the axial direction, or in the
X-axis negative direction. The length of boss portion 401 in the
X-axis direction, L3, is slightly shorter than the length of
fitting recess 101 of housing body 10 in the X-axis direction, L2.
Boss portion 401 has a slightly smaller outer diameter than rotor
body 400, which is slightly smaller than the diameter of through
hole 92 of rear plate 9. The surface of boss portion 401, including
the inside and outside peripheral surfaces of boss portion 401, is
formed with the anodic oxide coating film layer, as described
above. Rotor 40 is formed with a camshaft insertion hole 402 having
a bottom, which is positioned coaxially with rotor 40, and extends
inside of boss portion 401 and rotor body 400, where camshaft
insertion hole 402 has a diameter that is substantially equal to
and slightly larger than the diameter of intake camshaft 3a.
Camshaft insertion hole 402 extends over the entire axial length of
boss portion 401 and a range of two thirds or less of the axial
length of rotor body 400, as shown in FIG. 9B. Camshaft insertion
hole 402 is adapted to intake camshaft 3a so that an inserted
portion 301 of intake camshaft 3a (an X-axis positive side portion
of axial end portion 30 of intake camshaft 3a) is inserted and
mounted in camshaft insertion hole 402. Rotor body 400 is formed
with bolt holes 403, 404 and 405 at the bottom of camshaft
insertion hole 402, wherein each bolt hole 403, 404 or 405 extends
through rotor body 400. Bolt holes 403, 404 and 405 are arranged in
the circumferential direction around the axis of rotation O, in
this order in the clockwise direction, and substantially evenly
spaced from one another. The positions of bolt holes 403, 404 and
405 are set to face and conform to bolt holes 32 of axial end
portion 30 of intake camshaft 3a in the X-axis direction, so that
the central axes of bolt holes 403, 404 and 405 are substantially
identical to the central axes of bolt holes 32 as viewed in the
X-axis direction. Namely, the distance between each bolt hole 403,
404 or 405 and the axis of rotation O is substantially equal to the
distance between the corresponding bolt hole 32 and the axis of
rotation O, and the angle defined by the line connecting the axis
of rotation O and one of bolt holes 403, 404 and 405 and the line
connecting the axis of rotation O and another one of bolt holes
403, 404 and 405 is substantially equal to the angle defined by the
line connecting the axis of rotation O and one of bolt holes 32 and
the line connecting the axis of rotation O and another one of bolt
holes 32. Rotor body 400 is formed also with a pin hole having a
bottom (recess 44 for positioning) at the bottom of camshaft
insertion hole 402, wherein recess 44 extends to a predetermined
depth. As viewed in the X-axis direction, recess 44 has an elliptic
shape whose outline includes two straight line sections extending
in a radial direction of rotor 40 and facing one another in the
circumferential direction, and two curved sections having the form
of semicircles and facing one another in the radial direction of
rotor 40. Recess 44 is positioned between bolt hole 404 and bolt
hole 405. Specifically, the distance between the axis of rotation O
and the central axis of recess 44 is substantially equal to the
distance between the axis of rotation O and each bolt hole 403, 404
or 405, and recess 44 has a central axis at a substantially central
position between bolt holes 404 and 405, on the circle passing
through the central axes of bolt holes 403, 404 and 405. On the
other hand, in intake camshaft 3a, first fluid passage 212 opens at
axial end surface 300, constituting a pin hole or recess. FIG. 13
is a partial side sectional view taken along a plane passing
through a central longitudinal axis of a positioning pin 45. As
shown in FIG. 13, positioning pin 45 is press-fitted and fixed to
the open end of first fluid passage 212. Positioning pin 45 is a
dowel pin whose longitudinal end portion projects to a
predetermined height in the X-axis positive direction from axial
end surface 300 of intake camshaft 3a. Positioning pin 45 may be of
a type other than a dowel pin. The longitudinal end portion of
positioning pin 45 has a slightly smaller diameter than the size of
recess 44 in the circumferential direction, namely, than the
distance between the two straight line sections of recess 44, and
adapted to be inserted and fitted from the X-axis negative side
into recess 44. The diameter of the longitudinal end portion of
positioning pin 45 and the size of recess 44 are set so that when
positioning pin 45 is inserted and fitted in recess 44, no backlash
occurs between vane rotor 4 and intake camshaft 3a in the
circumferential direction. Recess 44 is located in vane rotor 4 so
that when positioning pin 45 is inserted and fitted in recess 44,
bolt holes 403, 404 and 405 of rotor 40 are located coaxially with
bolt holes 32 of intake camshaft 3a. Camshaft bolts 33, 34 and 35
are inserted from the X-axis positive side into corresponding ones
of bolt holes 403, 404 and 405, under condition that inserted
portion 301 is inserted and fitted in camshaft insertion hole 402,
and positioning pin 45 is inserted and fitted in recess 44, thereby
positioning the vane rotor 4 and intake camshaft 3a with respect to
one another in the circumferential direction. The head 331, 341 or
351 of each camshaft bolt 33, 34 or 35 is located at the X-axis
positive side of rotor 40, whereas a portion of the shank of each
camshaft bolt 33, 34 or 35 projecting from the X-axis negative side
of rotor 40 is inserted into the corresponding bolt hole 32, and
the male thread of each camshaft bolt 33, 34 or 35 is screwed with
the female thread of bolt hole 32. In this way, rotor 40 is fixed
to the axial end surface 300 of intake camshaft 3a so that the
axial end portion 30 of intake camshaft 3a is fixedly mounted to
vane rotor 4. Bolt holes 403, 404 and 405 thus constitute a
plurality of fixing portions for fixing the rotor 40 to the axial
end surface 300 of intake camshaft 3a.
[0045] As shown in FIG. 3, boss portion 401 of rotor 40 is inserted
from the X-axis positive side into the through hole 92 of
cylindrical portion 91 of rear plate 9. Boss portion 401 is mounted
with a slight clearance with through hole 92. The insertion of boss
portion 401 in through hole 92 serves to make the axes of rotation
of rear plate 9 and vane rotor 4 substantially identical to one
another, position the axis of rotation of vane rotor 4 at the axis
of rotation O, and make the boss portion 401 to bear the rear plate
9. Namely, vane rotor 4 is positioned with respect to housing HSG
through the boss portion 401 and cylindrical portion 91, while
housing HSG is rotatably supported with respect to vane rotor 4 or
intake camshaft 3a. Boss portion 401 serves as a bearing (slide
bearing) for bearing a load from housing HSG through the
cylindrical portion 91, and supporting the housing HSG for free
rotation thereof. The outside peripheral surface of boss portion
401 is in sliding contact with the inside peripheral surface of
through hole 92. The sliding outside peripheral surface of boss
portion 401 is provided with an anodic oxide coating film, as
described above.
[0046] Rotor body 400 is formed with first, second and third vanes
41, 42 and 43 at the outside periphery, which are arranged and
substantially evenly spaced in the circumferential direction,
extending outwardly in the radial direction from the axis of
rotation O. First, second and third vanes 41, 42 and 43 are
arranged in this order in the clockwise direction in FIG. 4.
Specifically, first vane 41 is disposed between bolt holes 403 and
404, second vane 42 is disposed between bolt holes 404 and 405, and
third vane 43 is disposed between bolt holes 405 and 403. First,
second and third vanes 41, 42 and 43 are formed integrally with
rotor 40 (rotor body 400), and have a cross section having a
substantially trapezoidal shape spreading outwardly in the radial
direction, as viewed in the X-axis direction. The length of first,
second and third vanes 41, 42 and 43 in the X-axis direction is set
equal to the length of rotor body 400 in the X-axis direction, L1.
When vane rotor 4 is mounted in housing HSG, the X-axis positive
side surfaces (formed with an anodic oxide coating film) of first,
second and third vanes 41, 42 and 43 face with a quite slight
clearance the X-axis negative side surface of front plate 8. On the
other hand, the X-axis negative side surfaces (formed with an
anodic oxide coating film) of first, second and third vanes 41, 42
and 43 face with a quite slight clearance the X-axis positive side
surface of rear plate 9. The lengths of second vane 42 and third
vane 43 in the circumferential direction of vane rotor 4 are
substantially equal to each other. The circumferential length of
first vane 41 is set larger that those of second vane 42 and third
vane 43, so as to provide a space where a lock mechanism 5 is
mounted. The centers of gravity of first, second and third vanes
41, 42 and 43 are arranged and substantially evenly spaced in the
circumferential direction. However, first vane 41 is slightly
heavier than the other vanes, because first vane 41 is large and
provided with lock mechanism 5. Accordingly, the space between
first vane 41 and second vane 42, and the space between third vane
43 and first vane 41, are set slightly larger than the space
between second vane 42 and third vane 43, so that the center of
gravity of the entire vane rotor 4 is conformed to the axis of
rotation O. When vane rotor 4 is mounted in housing HSG, first vane
41 is mounted between first shoe 11 and second shoe 12, second vane
42 is mounted between second shoe 12 and third shoe 13, and third
vane 43 is mounted between third shoe 13 and first shoe 11. Outside
peripheral surfaces 411, 421 and 431 of first, second and third
vanes 41, 42 and 43 are curved to have arced shapes which are
fitted with the inside peripheral surface of housing body 10, as
viewed in the X-axis direction, as shown in FIG. 4. Outside
peripheral surface 411 of first vane 41 is formed with a groove 412
which extends in the X-axis direction. A sealing member 413 and a
sealing spring such as a leaf spring 414 not shown are fitted and
retained in groove 412. Sealing member 413 is in liquid-tight
sliding contact with the inside peripheral surface of housing body
10. Leaf spring 414 presses the sealing member 413 onto the inside
peripheral surface of housing body 10. Similarly, outside
peripheral surfaces 421 and 431 of second vane 42 and third vane 43
are formed with grooves 422 and 432, sealing members 423 and 433,
and leaf springs 424 and 434, respectively. The counterclockwise
side of first vane 41 is formed with a flat portion 415 as viewed
from the X-axis positive side, as shown in FIG. 9A. Flat portion
415 is substantially in a straight line passing through the axis of
rotation O of rotor 40 as viewed in the X-axis direction. First
vane 41 is formed with a recess 416 between flat portion 415 and
the root of first vane 41. Recess 416 has an inwardly curved and
substantially arced edge, as viewed in the X-axis direction.
Similarly, second vane 42 and third vane 43 are formed with flat
portions 425 and 435, and recesses 426 and 436, respectively. As
viewed from the X-axis positive side, the counterclockwise side of
first vane 41 is formed with a rounded portion 417 at a tip portion
outside of flat portion 415. Rounded portion 417 has an outwardly
curved and substantially arced edge having a predetermined
curvature that is slightly smaller than the curvature of rounded
portion 112 of first shoe 11. Rounded portion 417 serves to allow
the flat portion 415 of first vane 41 to be in surface-to-surface
contact with the flat portion 111 of first shoe 11 as shown in FIG.
4, and serves to reduce the weight of first vane 41. On the other
hand, as viewed from the X-axis positive side, the clockwise sides
of first, second and third vanes 41, 42 and 43 are formed with
recesses 418, 428 and 438 respectively, where recesses 418, 428 and
438 are relatively wide recesses extending over the entire axial
length of vane rotor 4. As viewed from the X-axis positive side,
the clockwise side of first vane 41 is formed integrally with a
projection 419 that is located at the root and extends over a
predetermined distance, along the outside periphery of rotor 40
(rotor body 400) in the clockwise direction. The projection 419 is
formed continuous with the root of first vane 41, and projects from
the outside periphery of rotor 40 (rotor body 400) outwardly in the
radial direction. Similarly, the clockwise side of the root of
second vane 42 is formed integrally with a radial projection
429.
[0047] Vane rotor 4 defines, in the space between vane rotor 4 and
housing HSG, a plurality of working fluid chambers, namely, first,
second and third advance chambers A1, A2 and A3, and first, second
and third retard chambers R1, R2 and R3, which working fluid is
supplied to or drained from. Namely, as viewed in the X-axis
direction, three chambers are formed by two adjacent shoes and the
outside peripheral surface of rotor 40 (rotor body 400), and each
of the three chambers is divided by vane 41, 42 or 43 into one
advance chamber and one retard chamber. First, second and third
advance chambers A1, A2 and A3, and first, second and third retard
chambers R1, R2 and R3 are separated liquid-tightly from each other
by sealing member 413, etc. Working fluid is supplied from an oil
pump 1020 to first, second and third advance chambers A1, A2 and
A3, and first, second and third retard chambers R1, R2 and R3, and
serves to transmit torque between vane rotor 4 and housing HSG.
More specifically, first, second and third advance chambers A1, A2
and A3, and first, second and third retard chambers R1, R2 and R3
are defined by the X-axis negative side surface of front plate 8,
the X-axis positive side surface of rear plate 9, the
circumferentially-facing surfaces of first, second and third vanes
41, 42 and 43, and the circumferentially-facing surfaces of first,
second and third shoes 11, 12 and 13. For example, first advance
chamber A1 is defined between the clockwise surface of first shoe
11, the counterclockwise surface of first vane 41, whereas first
retard chamber R1 is defined between the clockwise surface of first
vane 41 and the counterclockwise surface of second shoe 12, as
shown in FIG. 4. Similarly, second advance chamber A2 is defined
between second shoe 12 and second vane 42, second retard chamber R2
is defined between second vane 42 and third shoe 13, third advance
chamber A3 is defined between third shoe 13 and third vane 43, and
third retard chamber R3 is defined between third vane 43 and first
shoe 11. Alternatively, one of the set of first, second and third
advance chambers A1, A2 and A3 and the set of first, second and
third retard chambers R1, R2 and R3 may be omitted. For example,
valve timing control apparatus 1 may include a single advance
chamber or a single retard chamber. The number of advance chambers
and the number of retard chambers are not limited to three, but may
be more or less than three. The shoes of the housing body may be
omitted, so that the working fluid chambers are defined between the
inside peripheral surface of the housing body and the vanes without
the shoes. The cylindrical rotor may be omitted so that the vane
member is constituted only by the vanes.
[0048] The range of relative rotation of vane rotor 4 with respect
to housing HSG is defined by first and second stopper mechanisms as
follows. When vane rotor 4 rotates with respect to housing HSG in
the counterclockwise direction by a predetermined angle as viewed
from the X-axis positive side, the flat portion 111 of first shoe
11, which is formed in the clockwise surface of first shoe 11, is
brought into surface-to-surface contact with flat portion 415 of
first vane 41, which is formed in the counterclockwise surface of
first vane 41, as shown in FIG. 4. Under this condition, the flat
portion 121 of second shoe 12 and the flat portion 425 of second
vane 42 face each other with a slight clearance, namely the
circumferentially-facing surfaces of second shoe 12 and second vane
42 are kept out of contact with each other. Similarly, flat portion
131 of third shoe 13 and flat portion 435 of third vane 43 face
each other with a slight clearance, and are kept out of contact
with each other. In this way, rotation of vane rotor 4 with respect
to housing HSG in the counterclockwise direction is restricted by
contact between flat portion 111 of first shoe 11 and flat portion
415 of first vane 41. Flat portion 111 of the
circumferentially-facing surface of first shoe 11 and flat portion
415 of the circumferentially-facing surface of 41 serve as first
stopper portions constituting a first stopper mechanism for
restricting relative rotation of vane rotor 4 in the
counterclockwise direction (in the retard direction). In FIG. 4
where relative rotation between vane rotor 4 and housing HSG is
restricted, an angle .alpha., which is defined about the axis of
rotation O by the clockwise side end surface of radial projection
419 and the counterclockwise side end surface of tip 126 of second
shoe 12, is slightly smaller than an angle .beta., which is defined
about the axis of rotation O by the clockwise side end surface of
radial projection 429 and the counterclockwise side end surface of
tip 136 of third shoe 13. According to the above relationship, when
vane rotor 4 rotates with respect to housing HSG from the position
shown in FIG. 4 by the angle .alpha. in the clockwise direction,
the tip 126 of second shoe 12 and the radial projection 419 of
first vane 41 are brought into surface-to-surface contact with each
other as shown in FIG. 5. Under this condition, the tip 136 of
third shoe 13 and the radial projection 429 of second vane 42 face
each other with a predetermined slight clearance in the
circumferential direction, so that third shoe 13 and second vane 42
are kept out of contact with each other. Similarly, first shoe 11
and third vane 43 face each other with a predetermined slight
clearance, and thus kept out of contact with each other. In this
way, rotation of vane rotor 4 with respect to housing HSG in the
clockwise direction is restricted by contact between tip 126 of
second shoe 12 and radial projection 419 of first shoe 11. The
clockwise surface of radial projection 419 and the counterclockwise
surface of tip 126 of second shoe 12 serve as second stopper
portions constituting a second stopper mechanism for restricting
relative rotation of vane rotor 4 in the clockwise direction (in
the advance direction). The contact area between tip 126 of second
shoe 12 and radial projection 419 of first shoe 11, i.e. the
contact area of the second stopper mechanism, SS2, is set smaller
than the contact area between flat portion 111 of first shoe 11 and
the flat portion 415 of first vane 41, i.e. the contact area of the
first stopper mechanism, SS1 (SS1>SS2). Incidentally, all over a
possible range of the rotational angle of vane rotor 4 with respect
to housing HSG, the volumetric capacities of first, second and
third advance chambers A1, A2 and A3, and first, second and third
retard chambers R1, R2 and R3 are prevented from becoming zero.
Also, the openings of retard fluid passages 408 and advance fluid
passages 409 in first, second and third advance chambers A1, A2 and
A3, and first, second and third retard chambers R1, R2 and R3 are
constantly prevented from being closed. For example, in FIG. 4, the
volumetric capacity of first advance chamber A1 and the opening of
advance fluid passage 409 are provided by the space defined between
recess 113 of first shoe 11 and recess 416 of first vane 41.
Similarly, the volumetric capacity of second advance chamber A2 and
the opening of advance fluid passage 409 are provided by the space,
i.e. the clearance described above, which is defined by flat
portion 121 of second shoe 12, and recess 426 and flat portion 425
of second vane 42. Similarly, the volumetric capacity of third
advance chamber A3 and the opening of advance fluid passage 409 are
provided by the space, i.e. the clearance described above, which is
defined by flat portion 131 of third shoe 13, and recess 436 and
flat portion 435 of third vane 43.
[0049] Hydraulic fluid supply and drainage mechanism 2 supplies
working fluid to or drains working fluid from first, second and
third advance chambers A1, A2 and A3, and first, second and third
retard chambers R1, R2 and R3, so that vane rotor 4 rotates with
respect to housing HSG by a predetermined angle in the advance
direction or retard direction. Specifically, supply and drainage of
working fluid causes changes in the volumetric capacities of first,
second and third advance chambers A1, A2 and A3, and first, second
and third retard chambers R1, R2 and R3, to generate a torque to
rotate vane rotor 4 with respect to housing HSG, so that the torque
is transmitted therebetween, and the phase of rotation of intake
camshaft 3a with respect to rotation of the crankshaft is changed.
Hydraulic fluid supply and drainage mechanism 2 includes an oil
pump 1020 as a hydraulic pressure source, and a directional control
valve 24 as a hydraulic control actuator. The hydraulic circuit
includes a retard passage 20 through which working fluid is
supplied to or drained from first, second and third retard chambers
R1, R2 and R3, and an advance passage 21 through which working
fluid is supplied to or drained from first, second and third
advance chambers A1, A2 and A3. Retard passage 20 and advance
passage 21 are connected through the directional control valve 24
to a supply passage 22 and a drain passage 23. Oil pump 1020 is
provided in supply passage 22 for pressurizing and supplying
working fluid from oil pan 25 to directional control valve 24. Oil
pump 1020 is mounted to the crankshaft, and may be implemented by a
unidirectional variable displacement vane pump. The downstream end
of drain passage 23 is hydraulically connected to oil pan 25.
Intake camshaft 3a and vane rotor 4 (rotor 40) include portions
constituting the retard passage 20 and advance passage 21. Rotor
body 400 is formed with three retard fluid passages 408 and three
advance fluid passages 409. Each fluid passage 408 or 409 extends
through the rotor body 400 in a radial direction of rotor body 400,
and hydraulically connects the inside periphery of camshaft
insertion hole 402 and the outside periphery of rotor 40 to one
another, so that when vane rotor 4 is fixed to intake camshaft 3a,
the fluid passage 408 or 409 hydraulically connects the
corresponding one of first, second and third advance chambers A1,
A2 and A3 and first, second and third retard chambers R1, R2 and R3
to corresponding ones of first fluid passages 202 and 212 and
second fluid passages 201, 203, 211 and 213. As viewed from the
X-axis positive side, each retard fluid passage 408 is located at
the root of the clockwise side of vane 41, 42 or 43, and each
advance fluid passage 409 is located at the root of the
counterclockwise side of vane 41, 42 or 43, as shown in FIGS. 4 and
9A. In the X-axis direction, each retard fluid passage 408 is
located at an X-axis positive side portion of camshaft insertion
hole 402 or at a substantially central position of rotor body 400
in the axial direction, and each advance fluid passage 409 is
located at an X-axis negative side portion of camshaft insertion
hole 402 or at an X-axis negative side portion of rotor body 400,
as shown in FIGS. 3 and 9B. Under condition that the axial end
portion 30 of intake camshaft 3a is fixedly inserted in camshaft
insertion hole 402, the position of each retard fluid passage 408
is substantially identical to the position of groove 204 in the
X-axis direction, so that the retard fluid passage 408
hydraulically communicates at the inside periphery of rotor 40 with
groove 204, and hydraulically communicates at the outside periphery
of rotor 40 with retard chamber R1, R2 or R3. Similarly, the
position of each advance fluid passage 409 is substantially
identical to the position of groove 214 in the X-axis direction, so
that the advance fluid passage 409 hydraulically communicates at
the inside periphery of rotor 40 with groove 214, and hydraulically
communicates at the outside periphery of rotor 40 with advance
chamber A1, A2 or A3. Extending from directional control valve 24,
retard passage 20 includes groove 200 which is located at the
X-axis negative side portion of axial end portion 30 of intake
camshaft 3a, wherein intake camshaft 3a is a rotating member.
Groove 200 is hydraulically connected to first fluid passage 202
through the second fluid passage 201, and first fluid passage 202
is hydraulically connected to groove 204 through the second fluid
passage 203, and groove 204 hydraulically communicates with first,
second and third retard chambers R1, R2 and R3 through retard fluid
passages 408. Incidentally, the opening of first fluid passage 202
at the axial end surface 300 of intake camshaft 3a is closed by the
bottom surface of camshaft insertion hole 402 when intake camshaft
3a is fixed to vane rotor 4 by camshaft bolts 33, 34 and 35.
Similar to retard passage 20, extending from directional control
valve 24, advance passage 21 includes groove 210 which is located
at the X-axis negative side portion of axial end portion 30 of
intake camshaft 3a. Groove 210 is hydraulically connected to first
fluid passage 212 through the second fluid passage 211, and first
fluid passage 212 is hydraulically connected to groove 214 through
the second fluid passage 213, and groove 214 hydraulically
communicates with first, second and third advance chambers A1, A2
and A3 through advance fluid passage 409. Incidentally, the opening
of first fluid passage 212 at the axial end surface 300 of intake
camshaft 3a is closed by positioning pin 45. The annular shape of
each groove 204 or 214 extending in the circumferential direction
serves to enhance the flexibility of layout of retard fluid
passages 408 and advance fluid passages 409 in vane rotor 4. Each
groove 204 or 214 may be replaced with an annular groove that is
formed in the inside periphery of camshaft insertion hole 402 of
vane rotor 4 to extend in the circumferential direction. However,
the arrangement of each groove 204 or 214 in intake camshaft 3a is
advantageous in easiness of forming or machining same. Directional
control valve 24 is a direct-acting type solenoid valve with four
ports and three positions, for controlling the hydraulic pressures
of working fluid which is supplied to or drained from first, second
and third advance chambers A1, A2 and A3, and first, second and
third retard chambers R1, R2 and R3. Directional control valve 24
includes a valve body fixed to the cylinder head, a solenoid "SOL"
fixed to the valve body, and a spool valve element slidably mounted
inside the valve body. The valve body is formed with a supply port
240 hydraulically connected to supply passage 22, a first port 241
hydraulically connected to retard passage 20, a second port 242
hydraulically connected to advance passage 21, and a drain port 243
hydraulically connected to drain passage 23. When an
electromagnetic coil of solenoid SOL is energized, then solenoid
SOL presses the spool valve element to move. The electromagnetic
coil is electrically connected to controller CU through a harness.
Each of first port 241 and second port 242 opens or closes
according to movement of the spool valve element. When solenoid SOL
is de-energized, the spool valve element is biased by return spring
RS to a position such that the supply port 240 (supply passage 22)
and second port 242 (advance passage 21) are hydraulically
connected to each other, and first port 241 (retard passage 20) and
drain port 243 (drain passage 23) are hydraulically connected to
each other. On the other hand, when solenoid SOL is energized, the
spool valve element is controlled according to a control current
from controller CU, to move against the elastic force of return
spring RS to a predetermined intermediate position such that the
supply port 240 (supply passage 22) and first port 241 (retard
passage 20) are hydraulically connected to each other, and second
port 242 (advance passage 21) and drain port 243 (drain passage 23)
are hydraulically connected to each other. Controller CU is an
electrical control unit which is configured to measure a current
operating state of the internal combustion engine on the basis of
signals from sensors such as a crank angle sensor for measuring
engine rotational speed, an air flow meter for measuring a quantity
of intake air, a throttle valve opening sensor, and a coolant
temperature sensor for measuring a coolant temperature of the
internal combustion engine. Moreover, controller CU performs a flow
direction control of selectively supplying working fluid to or
draining working fluid from first, second and third advance
chambers A1, A2 and A3, and first, second and third retard chambers
R1, R2 and R3, by energizing or de-energizing the solenoid SOL of
directional control valve 24 with a pulse control signal, according
to the measured operating state of the internal combustion
engine.
[0050] Intake valve timing control apparatus 1a is provided with an
arrangement that a lock piston 51 locks relative rotation between
vane rotor 4 and housing HSG when vane rotor 4 is in a most
retarded position which is defined by the first stopper mechanism.
Lock piston 51 is an engagement member which is provided in vane
rotor 4, and arranged to move forward or rearward in the X-axis
direction according to a state of operation of the internal
combustion engine. Lock mechanism 5 is arranged between first vane
41 and rear plate 9, for locking or releasing relative rotation of
vane rotor 4 with respect to rear plate 9 (or housing HSG). Lock
mechanism 5 includes slide hole 501, lock piston 51, a sleeve 52,
and a coil spring 53. FIG. 14 is a partial side sectional view
taken along a plane passing through a central longitudinal axis of
lock mechanism 5, showing a state of operation of lock piston 51
when the internal combustion engine is at rest, or the internal
combustion engine is being started.
[0051] First vane 41 is formed with slide hole 501 which extends
through first vane 41 in the X-axis direction. Slide hole 501 is a
hollow cylindrical portion or cylinder formed to extend in the
axial direction of vane rotor 4. The surface (inside peripheral
surface) of slide hole 501 is anodized as described above. A
sealing member 502, which has an annular shape or a hollow
cylindrical shape, is formed separately from vane rotor 4, and
pressed-fitted in an X-axis negative side portion of slide hole
501. Sealing member 502 is a hollow cylindrical member (or
ring-shaped member) having a smaller longitudinal size than slide
hole 501, specifically half or less of the longitudinal size of
slide hole 501, wherein sealing member 502 is inserted from the
X-axis negative side end of slide hole 501 and press-fitted into
the inside of slide hole 501. Slide hole 501 may be set and fixed
in an alternative manner other than press-fitting. Sealing member
502 is formed of a material having a higher wear resistance than
anodic oxide coating. Specifically, sealing member 502 is formed of
an iron alloy such as a carbon steel such as S45C, into a ring
shape, and carburized.
[0052] Lock piston 51 as a lock member is formed of iron into a
pin, having a hollow cylindrical shape with a bottom portion 510 at
the X-axis negative side. Lock piston 51 is mounted in slide hole
501 for sliding in the X-axis direction, and projecting from the
X-axis negative side of slide hole 501 closer to intake camshaft 3a
or retreating into the X-axis negative side of slide hole 501. Lock
piston 51 includes a smaller-diameter portion and a larger-diameter
portion. The smaller-diameter portion is a distal-side portion of
lock piston 51 that is disposed in slide hole 501, and arranged to
move out of and into slide hole 501. The smaller-diameter portion
includes a sliding portion 512, and an engaging portion 511.
Sliding portion 512 has a hollow cylindrical shape having a closed
bottom. Engaging portion 511 is adjacent to and in the X-axis
negative direction from bottom portion 510, where a step is formed
between bottom portion 510 and engaging portion 511. Engaging
portion 511 has the form of a substantially truncated cone having a
substantially trapezoidal longitudinal section. In this way,
engaging portion 511 has an inclined surface or tapered surface
with respect to the longitudinal direction, wherein the diameter of
the tapered surface decreases as followed toward the tip at the
X-axis negative side. The larger-diameter portion is a
proximal-side portion of lock piston 51 that is disposed in slide
hole 501. The larger-diameter portion includes an annular flange
513 at the X-axis positive side end, which is adjacent to and on
the X-axis positive side of sliding portion 512. The
larger-diameter portion (or flange 513) has a larger diameter than
the smaller-diameter portion (or sliding portion 512 and engaging
portion 511). The outside periphery of sliding portion 512 has a
slightly smaller diameter than the inside periphery of sealing
member 502. Sliding portion 512 includes an X-axis negative side
portion that is accommodated in sealing member 502 so that the
outside periphery of sliding portion 512 is in sliding contact with
the inside periphery of sealing member 502. The outside periphery
of flange 513 has a slightly smaller diameter than the inside
periphery of slide hole 501. Flange 513 is accommodated in slide
hole 501 so that the outside periphery of flange 513 is in sliding
contact with the inside periphery of slide hole 501. The radial
clearance between the outside periphery of sliding portion 512 and
the inside periphery of sealing member 502 is set smaller than that
between the outside periphery of flange 513 and the inside
periphery of slide hole 501. In this way, lock piston 51 has a
portion (sliding portion 512) in sliding contact with the inside
periphery of sealing member 502, another portion (flange 513) in
sliding contact with the inside periphery of slide hole 501, and a
tip (engaging portion 511) arranged to move forward and rearward in
the axial direction (in the X-axis direction) with respect to vane
rotor 4 according to the state of operation of the internal
combustion engine.
[0053] On the other hand, rear plate 9 is formed with recess 900 in
the X-axis positive side surface. Recess 900 is located in the
chamber between first shoe 11 and second shoe 12, and more adjacent
to first shoe 11 on the clockwise side of first shoe 11. Recess 900
has a bottom in rear plate 9, without passing through rear plate 9.
Recess 900 is located to face or conform to the tip (engaging
portion 511) of lock piston 51 as viewed in the X-axis direction,
when intake valve timing control apparatus 1a is in the most
retarded state shown in FIG. 4. Sleeve 52, which is formed in a
hollow cylindrical shape separately from rear plate 9, and referred
to as lock recess constituent member, is press-fitted in recess 900
of rear plate 9. Sleeve 52 may be fixed in an alternative manner
other than press-fitting. Sleeve 52 is formed of an iron-based
metal material. The inside peripheral surface of sleeve 52 defines
engaging recess 521. Engaging recess 521 is a lock recess in which
the smaller-diameter portion (engaging portion 511) of lock piston
51 can be inserted. The longitudinal size of engaging recess 521
(sleeve 52) is substantially equal to the longitudinal size of
engaging portion 511. Engaging recess 521 has a slightly larger
diameter than engaging portion 511. Engaging recess 521 has a
substantially trapezoidal section taken along a plane passing
through the central longitudinal axis of sleeve 52, and gradually
spreads toward the X-axis positive side opening. Namely, engaging
recess 521 has an inclined surface or tapered surface with respect
to the longitudinal direction, wherein the diameter of the tapered
surface gradually decreases as followed toward the X-axis negative
side bottom. The angle of inclination of the inside peripheral
surface (inclined surface) of engaging recess 521 with respect to
the X-axis is substantially equal to that of engaging portion 511.
Engaging recess 521 is provided in housing HSG, and on the X-axis
positive side surface of rear plate 9, or on the axial end of
housing HSG closer to intake camshaft 3a, similar to recess 900.
When vane rotor 4 is relatively rotated toward the most retarded
position and the rotation of vane rotor 4 is restricted by the
first stopper mechanism, namely, when the volumetric capacity of
first advance chamber A1 is minimized, the position of lock piston
51 (engaging portion 511) overlaps or is identical with the
position of engaging recess 521 as viewed in the X-axis direction,
since recess 900 is located as described above. In other words, the
rotational position of vane rotor 4 with respect to housing HSG is
set to the most retarded position which is optimal at start of the
internal combustion engine, under the condition that lock piston 51
is engaged with engaging recess 521 of sleeve 52. Under this
condition, the central axis of engaging recess 521 is located with
a slight offset from the central axis of engaging portion 511 in
the counterclockwise direction shown in FIG. 4 (toward first shoe
11) of vane rotor 4.
[0054] The inside of slide hole 501 is formed with a back pressure
chamber 50 for lock piston 51. Back pressure chamber 50 is a low
pressure chamber that is defined in slide hole 501 by lock piston
51, and is located opposite to sleeve 52 (or rear plate 9 or intake
camshaft 3a) with respect to lock piston 51. Specifically, back
pressure chamber 50 is defined by the X-axis negative side surface
of front plate 8, and the inside periphery of lock piston 51
(sliding portion 512, flange 513).
[0055] Coil spring 53 is a biasing member that constantly biases
lock piston 51 in the X-axis negative direction, i.e. toward rear
plate 9, specifically toward engaging recess 521 of sleeve 52. Coil
spring 53 is mounted in a compressed state in back pressure chamber
50, wherein the X-axis positive side end of coil spring 53 is in
contact with the X-axis negative side surface of front plate 8, and
the X-axis negative side end of coil spring 53 is in contact with
the bottom portion 510 of lock piston 51. Namely, in slide hole
501, coil spring 53 is provided on one side (larger-diameter side
or X-axis positive side) of lock piston 51, and arranged to bias
the lock piston 51 toward the other side (smaller-diameter side or
X-axis negative side) of lock piston 51. A spring retainer 54 is
mounted in the X-axis positive side of back pressure chamber 50.
Spring retainer 54 has an annular shape, and retains coil spring
53. The outer diameter of spring retainer 54 is substantially equal
to the diameter of the inside peripheral surface of slide hole 501.
The X-axis positive side surface of spring retainer 54 faces the
X-axis negative side surface of front plate 8, whereas the X-axis
negative side surface of spring retainer 54 faces the X-axis
positive side surface of flange 513 of lock piston 51. The X-axis
positive side end portion of coil spring 53 is fitted with the
inside periphery of spring retainer 54, so as to prevent coil
spring 53 from deviating with respect to slide hole 501 in the
lateral direction of lock piston 51.
[0056] Slide hole 501 is formed with first and second
pressure-receiving chambers 55 and 59 for applying hydraulic
pressure to lock piston 51. In slide hole 501, first
pressure-receiving chamber 55 is defined by the X-axis positive
side end surface of sealing member 502, the X-axis negative side
surface of flange 513, the outside peripheral surface of sliding
portion 512, and the inside peripheral surface of slide hole 501.
Second pressure-receiving chamber 59 is defined by the surface (the
X-axis negative side tip surface, and inclined surface) of engaging
portion 511, the X-axis positive side surface of rear plate 9 (or
the inside peripheral surface of sleeve 52 and the bottom of recess
900, in the lock state in which engaging portion 511 engages with
engaging recess 521). First vane 41 is formed with fluid passages
for guiding hydraulic pressure from the working fluid chambers to
first and second pressure-receiving chambers 55 and 59. A
communication hole 56 is formed to extend in first vane 41 in the
circumferential direction of first vane 41. First retard chamber R1
is constantly hydraulically connected to first pressure-receiving
chamber 55 through the communication hole 56, so that the hydraulic
pressure in first retard chamber R1 is constantly supplied to first
pressure-receiving chamber 55. The X-axis negative side surface of
first vane 41 is formed with a communication groove 57 that extends
in the circumferential direction of first vane 41. First advance
chamber A1 is constantly hydraulically connected to the X-axis
negative side end of slide hole 501 through the communication
groove 57, so that the hydraulic pressure in first advance chamber
A1 is constantly supplied to second pressure-receiving chamber 59
(engaging recess 521 in the lock state).
[0057] Communication hole 56 and communication groove 57 constitute
a mechanism for engaging and disengaging the lock piston 51,
together with coil spring 53 as an elastic member for engagement.
When vane rotor 4 relatively rotates to the most retard side, and
rotation of vane rotor 4 is restricted by the first stopper
mechanism, then the position of lock piston 51 is identical to the
position of engaging recess 521 as viewed in the X-axis direction,
so as to allow lock piston 51 to move in the X-axis negative
direction. Under this condition, the biasing force of coil spring
53 serves to assist the lock piston 51 in moving in the X-axis
negative direction so that the engaging portion 511 moves out of
slide hole 501 of first vane 41, and engages with engaging recess
521. The engagement of lock piston 51 with engaging recess 521
restricts or locks relative rotation between rear plate 9 and vane
rotor 4, or relative rotation between housing HSG and intake
camshaft 3a. On the other hand, lock piston 51 is subject to a
hydraulic force at the flange 513 in the X-axis positive direction,
wherein the hydraulic force is based on the hydraulic pressure
supplied from first retard chamber R1 to first pressure-receiving
chamber 55 through the communication hole 56. Lock piston 51 is
also subject to a hydraulic force at the engaging portion 511 in
the X-axis positive direction, wherein the hydraulic force is based
on the hydraulic pressure supplied from first advance chamber A1 to
second pressure-receiving chamber 59 through the communication
groove 57. Both of the hydraulic forces serve to assist the lock
piston 51 in moving in the X-axis positive direction against the
biasing force of coil spring 53, so that the engaging portion 511
moves out of engaging recess 521, and into slide hole 501 of rear
plate 9. The engagement of lock piston 51 with engaging recess 521
is thus released. In this way, coil spring 53 serves to maintain
the lock state, while communication hole 56 and communication
groove 57 serve as a hydraulic circuit for releasing the lock
state.
[0058] Intake valve timing control apparatus 1a is provided with a
back pressure relief section for relieving pressure in back
pressure chamber 50 and keeping same low. The back pressure relief
section includes a first back pressure passage 31, a back pressure
hole 407, and a second back pressure passage. First back pressure
passage 31 is formed in intake camshaft 3a, whereas back pressure
hole 407 and the second back pressure passage are formed in vane
rotor 4. These constituents serve as a passage for relieving the
pressure in back pressure chamber 50 to a space in the internal
combustion engine. The space in the internal combustion engine is a
low pressure space that is defined by a housing (cylinder head,
cylinder block, etc.) of the internal combustion engine, and
separated liquid-tightly from timing belt 1010. First back pressure
passage 31 is a breathing hole formed in intake camshaft 3a to
extend in the X-axis direction, from the X-axis positive side axial
end surface 300 to a predetermined depth in the X-axis direction.
First back pressure passage 31 has an opening at the axial end
surface 300, and hydraulically communicates the axial end surface
300 with an oil-lubricated space in the internal combustion engine.
First back pressure passage 31 is located at the axis of rotation
of intake camshaft 3a, namely, the axis of rotation O, having the
same diameter as first fluid passages 202 and 212. First back
pressure passage 31 may be formed to communicate with a low
pressure section of hydraulic fluid supply and drainage mechanism
2, instead of or in addition to the oil-lubricated space in the
internal combustion engine. In other words, the space in the
internal combustion engine which is related to first back pressure
passage 31 includes a hydraulic circuit of hydraulic fluid supply
and drainage mechanism 2. For example, back pressure chamber 50 may
be hydraulically connected to directional control valve 24, so that
the working fluid in back pressure chamber 50 is drained to oil pan
25 through the drain passage 23. If intake valve timing control
apparatus 1a is constructed so that only first, second and third
advance chambers A1, A2 and A3 are supplied with working fluid, and
first, second and third retard chambers R1, R2 and R3 are supplied
with no working fluid, the working fluid in back pressure chamber
50 may be released to a passage that is hydraulically connected to
first, second and third retard chambers R1, R2 and R3. Back
pressure hole 407 is a breathing hole extending through the rotor
40 along the axis of rotation of rotor 40 (axis of rotation O) in
the X-axis direction, having a smaller diameter than first back
pressure passage 31, as shown in FIG. 4. Back pressure hole 407
faces first back pressure passage 31 in the X-axis direction,
wherein the central axis of back pressure hole 407 is identical to
the central axis of first back pressure passage 31 as viewed in the
X-axis direction. The opening of back pressure hole 407 at the
X-axis negative side surface of rotor 40 (at the bottom surface of
camshaft insertion hole 402) is located to face the opening of
first back pressure passage 31 at the axial end surface 300 of
intake camshaft 3a. As shown in FIG. 9A, the second back pressure
passage is a recess for breathing that is formed in the X-axis
positive side end surface of vane rotor 4, including a circular
recess 406 and a radial groove 58. Circular recess 406 is a shallow
cylindrical recess having a central axis that is substantially
identical to the central axis of rotor 40, wherein circular recess
406 extends from the X-axis positive side in the X-axis negative
direction to a depth of about 13% of the axial size of rotor body
400. The bottom of circular recess 406 is formed with bolt holes
403, 404 and 405, and back pressure hole 407. The depth (size in
the X-axis direction) of circular recess 406 is about half or more
of the height (size in the X-axis direction) of each head 331, 341
or 351. The diameter of circular recess 406 is slightly smaller
than the outside diameter of rotor body 400, slightly smaller than
the diameter of large-diameter hole 81 of front plate 8, and
substantially equal to the diameter of recess 73 of cap 7. Circular
recess 406 is located to face the recess 73 in the X-axis
direction. Radial groove 58 is a rectangular groove for
hydraulically communicating the circular recess 406 and back
pressure chamber 50 with one another, extending from circular
recess 406 through the root of first vane 41 outwardly in a radial
direction of rotor 40, and including an end connected to the X-axis
positive side end of slide hole 501. The depth (size in the X-axis
direction) of radial groove 58 is substantially equal to that of
circular recess 406. Back pressure chamber 50 is hydraulically
connected to back pressure hole 407 and first back pressure passage
31 through the second back pressure passage, and thereby
hydraulically connected to the inside of the internal combustion
engine. Namely, back pressure chamber 50 is hydraulically connected
to circular recess 406 and back pressure hole 407 through the
radial groove 58, and further connected to the low pressure space
in the internal combustion engine through the first back pressure
passage 31, as shown in FIG. 3.
[0059] <Construction of Exhaust Valve Timing Control
Apparatus> The following describes construction of exhaust valve
timing control apparatus 1b which is provided for the exhaust
valves of the internal combustion engine, with reference to FIGS.
15 to 19. In the following, constituent parts of exhaust valve
timing control apparatus 1b, which are identical or similar to
those of intake valve timing control apparatus 1a, are provided
with identical reference characters, and with no duplicate
description, and only different constituent parts are described.
FIG. 15 is a partial side sectional view of exhaust valve timing
control apparatus 1b, taken along a plane passing through an axis
of rotation "O" (shown in FIG. 16) of exhaust valve timing control
apparatus 1b, i.e. taken along a plane indicated by a long dashed
short dashed line F15-F15 in FIG. 16. FIGS. 16 and 17 are front
views of exhaust valve timing control apparatus 1b under the
condition that the front plate 8, etc. are removed, as viewed from
the X-axis positive side. Exhaust valve timing control apparatus 1b
controls variable valve timing of the exhaust valves by
continuously changing a rotational phase of exhaust camshaft 3b
with respect to the crankshaft by supplied working fluid. Pulley
100, as well as housing body 10, is rotated by the crankshaft of
the internal combustion engine, in the clockwise direction in FIG.
16, according to movement of timing belt 1010 shown by the arrow in
FIG. 1. As shown in FIG. 15, front plate 8 of exhaust valve timing
control apparatus 1b is provided with no outside periphery 80 which
is provided in intake valve timing control apparatus 1a, so that
the diameter of front plate 8 of exhaust valve timing control
apparatus 1b is smaller than the diameter (specifically, the
diameter of tooth bottom circle) of pulley 100. The outside
periphery of front plate 8 is more adjacent to annular sealing ring
groove 89 with a shorter distance than distance r shown in FIG. 12.
Accordingly, as shown in FIG. 1, as viewed in the X-axis direction,
the outside periphery (i.e. teeth) of pulley 100 of exhaust valve
timing control apparatus 1b projects radially outwardly from the
outside periphery of front plate 8. In other words, the diameter of
exhaust valve timing control apparatus 1b is set smaller than that
of intake valve timing control apparatus 1a where outside periphery
80 of front plate 8 projects radially outwardly from the outside
periphery of pulley 100. Housing body 10 of exhaust valve timing
control apparatus 1b is a mirror image of the housing body of
intake valve timing control apparatus 1a with respect to a plane
perpendicular to the X-axis. FIGS. 18A, 18B and 18C are views of
housing body 10 of exhaust valve timing control apparatus 1b, where
FIG. 18A is a front view as viewed from the X-axis positive side,
FIG. 18B is a side sectional view taken along a plane indicated by
F18B-F18B in FIG. 18A, and FIG. 18C is a rear view as viewed from
the X-axis negative side. FIGS. 7 and 8 are perspective views of
workpieces during a process of manufacturing the housing body 10
also for exhaust valve timing control apparatus 1b. Housing body 10
of exhaust valve timing control apparatus 1b is formed from an
aluminum extrusion shown in FIG. 7, similar to intake valve timing
control apparatus 1a. Third workpiece P3 shown in FIG. 8 is
obtained through the second workpiece P2 from first workpiece P1.
Finally, third workpiece P3 is applied with carving or cutting, to
form a fitting recess 101, bolt hole 110, etc., and thereby form a
final shape of housing body 10 shown in FIGS. 18A, 18B and 18C. In
contrast to intake valve timing control apparatus 1a where fitting
recess 101 and positioning recess 114 are formed in the side "A"
(shown in FIG. 8) of third workpiece P3 as shown in FIGS. 6A, 6B
and 6C, fitting recess 101 and positioning recess 114 are formed in
the side "B" (shown in FIG. 8) of third workpiece P3 for exhaust
valve timing control apparatus 1b, as shown in FIGS. 18A, 18B and
18C. Also, vane rotor 4 of exhaust valve timing control apparatus
1b is a mirror image of the vane rotor of intake valve timing
control apparatus 1a with respect to a plane perpendicular to the
X-axis. FIGS. 19A and 19B are views of vane rotor 4 of exhaust
valve timing control apparatus 1b, where FIG. 19A is a front view
as viewed from the X-axis positive side, and FIG. 19B is a side
sectional view taken along a plane indicated by F19B-F19B in FIG.
19A. FIGS. 10 and 11 are perspective views of workpieces during a
process of manufacturing the vane rotor 4 also for exhaust valve
timing control apparatus 1b. Vane rotor 4 of exhaust valve timing
control apparatus 1b is formed from an aluminum extrusion (first
workpiece Q1) shown in FIG. 10, similar to intake valve timing
control apparatus 1a. Then, second workpiece Q2, which is obtained
from first workpiece Q1, is applied with carving or cutting, to
form a boss portion 401, a camshaft insertion hole 402, etc., and
thereby form a final shape of vane rotor 4 shown in FIGS. 19A and
19B. In contrast to intake valve timing control apparatus 1a where
boss portion 401 and camshaft insertion hole 402 are formed on the
side "A" of second workpiece Q2, boss portion 401 and camshaft
insertion hole 402 are formed on the side "B" of second workpiece
Q2 for exhaust valve timing control apparatus 1b, as shown in FIGS.
19A and 19B. Finally, the entire outside surfaces of second
workpiece Q2 are applied with anodic oxidation treatment, to form a
third workpiece Q3 which has hardened surfaces. In this way,
housing bodies 10 and vane rotors 4 of intake valve timing control
apparatus 1a and exhaust valve timing control apparatus 1b are
mirror images which are formed from the identical or common
workpieces P3 and Q2 which are formed before the application of
carving. As shown in FIGS. 16 and 4, the shapes and relative
positions of housing body 10 and vane rotor 4 of exhaust valve
timing control apparatus 1b are mirror images of those of intake
valve timing control apparatus 1a as viewed from the X-axis
positive side. First, second and third shoes 11, 12 and 13 are
arranged in this order in the counterclockwise direction in FIG.
16. As viewed from the X-axis positive side, the clockwise surfaces
of first, second and third shoes 11, 12 and 13 are formed with
recesses 115, 125 and 135 respectively. The counterclockwise
surfaces of first, second and third shoes 11, 12 and 13 are formed
with flat portions 111, 121 and 131 respectively. First, second and
third vanes 41, 42 and 43 are arranged in this order in the
counterclockwise direction in FIG. 16. As viewed from the X-axis
positive side, the clockwise surfaces of first, second and third
vanes 41, 42 and 43 are formed with flat portions 415, 425 and 435
respectively. The counterclockwise surfaces of first, second and
third vanes 41, 42 and 43 are formed with recesses 418, 428 and 438
respectively. The counterclockwise surfaces of the roots of first
and second vanes 41 and 42 are formed with radial projections 419
and 429 respectively. Under the condition that the vane rotor 4 is
mounted in housing HSG, first vane 41 is mounted in the space
between first shoe 11 and second shoe 12, second vane 42 is mounted
in the space between second shoe 12 and third shoe 13, and third
vane 43 is mounted in the space between third shoe 13 and first
shoe 11. Rotor body 400 is formed with three retard fluid passages
408 and three advance fluid passages 409 which are connected
between camshaft insertion hole 402 and the outside peripheral
surface of rotor 40 (rotor body 400). In the case of first vane 41,
retard fluid passage 408 is formed substantially in a midpoint in
the X-axis direction as shown in FIG. 19B, and in the clockwise
side of the root of first vane 41 as viewed from the X-axis
positive side, as shown in FIG. 16, where retard fluid passage 408
is formed to extend through in the radial direction, as shown in
FIG. 16. On the other hand, advance fluid passage 409 is formed in
the X-axis negative side in first vane 41, and in the
counterclockwise side of the root of first vane 41 as viewed from
the X-axis positive side, as shown in FIG. 16, where advance fluid
passage 409 is formed to extend through in the radial direction, as
shown in FIG. 16. Similarly, retard fluid passages 408 and advance
fluid passages 409 are formed in the roots of second vane 42 and
third vane 43, extending through in the radial direction. First,
second and third advance chambers A1, A2 and A3, and first, second
and third retard chambers R1, R2 and R3 are defined by the X-axis
negative side surface of front plate 8, the X-axis positive side
surface of rear plate 9, the circumferentially-facing surfaces of
first, second and third vanes 41, 42 and 43, and the
circumferentially-facing surfaces of first, second and third shoes
11, 12 and 13. For example, first advance chamber A1 is defined
between the clockwise surface of second shoe 12, the
counterclockwise surface of first vane 41, whereas first retard
chamber R1 is defined between the clockwise surface of first vane
41 and the counterclockwise surface of first shoe 11, as shown in
FIG. 16. Similarly, second advance chamber A2 is defined between
first shoe 11 and third vane 43, second retard chamber R2 is
defined between third vane 43 and third shoe 13, third advance
chamber A3 is defined between third shoe 13 and second vane 42, and
third retard chamber R3 is defined between second vane 42 and
second shoe 12. Rotation of vane rotor 4 with respect to housing
HSG in the clockwise direction is restricted by contact between
flat portion 111 of first shoe 11 and flat portion 415 of first
vane 41, where rotation of vane rotor 4 is locked by lock piston
51, similar to intake valve timing control apparatus 1a, as shown
in FIG. 16. Flat portion 111 of the circumferentially-facing
surface of first shoe 11 and flat portion 415 of the
circumferentially-facing surface of 41 serve as first stopper
portions constituting a first stopper mechanism for restricting
relative rotation of vane rotor 4 in the clockwise direction (in
the advance direction). On the other hand, rotation of vane rotor 4
with respect to housing HSG in the counterclockwise direction is
restricted by contact between tip 126 of second shoe 12 and radial
projection 419 of first shoe 11, where vane rotor 4 is in the end
position in the direction away from the position where rotation of
vane rotor 4 is locked by lock piston 51, similar to intake valve
timing control apparatus 1a, as shown in FIG. 17. The
counterclockwise surface of radial projection 419 and the clockwise
surface of tip 126 of second shoe 12 serve as second stopper
portions constituting a second stopper mechanism for restricting
relative rotation of vane rotor 4 in the counterclockwise direction
(in the retard direction). The first and second stopper mechanisms
define a range of relative rotation of vane rotor 4 with respect to
housing HSG. As in intake valve timing control apparatus 1a, the
contact area between tip 126 of second shoe 12 and radial
projection 419 of first shoe 11, i.e. the contact area of the
second stopper mechanism, SS2, is set smaller than the contact area
between flat portion 111 of first shoe 11 and the flat portion 415
of first vane 41, i.e. the contact area of the first stopper
mechanism, SS1 (SS1>SS2).
[0060] Exhaust camshaft 3b is made of iron, and rotatably supported
on bearings in a laterally-outside portion of the upper end portion
of the cylinder head of the internal combustion engine. Exhaust
camshaft 3b is formed with drive cams (exhaust cams) at the outside
peripheral surface, which are located to face or conform to
positions of the exhaust valves. When exhaust camshaft 3b is
rotated, the exhaust cams open and close the exhaust valves via
valve lifters, rocker arms, etc. Exhaust valve timing control
apparatus 1b, which is fixed to exhaust camshaft 3b, is constructed
to be locked by lock piston 51 as an engagement member, under the
condition that rotation of vane rotor 4 is restricted by the first
stopper mechanism at the most advanced position.
[0061] In contrast to intake valve timing control apparatus 1a,
exhaust valve timing control apparatus 1b is provided with a
biasing member for biasing the vane rotor 4 with respect to housing
HSG in the advance direction. The biasing member, which is
collectively referred to as biasing member 6, includes three spring
units, i.e. first, second and third spring units 61, 62 and 63.
First, second and third spring units 61, 62 and 63 are mounted in
first, second and third advance chambers A1, A2 and A3
respectively, for biasing the first, second and third vanes 41, 42
and 43 of vane rotor 4 with respect to first, second and third
shoes 11, 12 and 13 of housing body 10 in the clockwise direction.
Biasing member 6 may be provided in part of first, second and third
advance chambers A1, A2 and A3. Biasing member 6 may be provided in
first, second and third retard chambers R1, R2 and R3. This
construction may be used in cases where vane rotor 4 needs to be
biased with respect to housing HSG in the retard direction, which
cases are possible according to the form of transmitting torque
from the crankshaft to the camshaft. Specifically, first spring
unit 61 is mounted in first advance chamber A1 between second shoe
12 and first vane 41, second spring unit 62 is mounted in second
advance chamber A2 between first shoe 11 and third vane 43, and
third spring unit 63 is mounted in third advance chamber A3 between
third shoe 13 and second vane 42. The longitudinal ends of first,
second and third spring units 61, 62 and 63 are mounted in recesses
418, 428 and 438, and recesses 115, 125 and 135, where recesses
418, 428 and 438 are formed in the counterclockwise surfaces of
first, second and third vanes 41, 42 and 43, respectively, and
recesses 115, 125 and 135 are formed in the opposite clockwise
surfaces of first, second and third shoes 11, 12 and 13,
respectively. First spring unit 61 includes a coil spring 610, and
retaining portions 611 and 612 which are spring retainers provided
at the longitudinal ends of coil spring 610. Retaining portion 611
includes a plate portion in which a through hole is formed, and a
hollow cylindrical portion which projects from one side surface of
the plate portion, and surrounds the through hole. One longitudinal
end of coil spring 610 is fitted with the outside periphery of the
hollow cylindrical portion of retaining portion 611. The plate
portion of retaining portion 611 has a rectangular shape adapted to
be fitted in recess 125 of second shoe 12 without play, and is
fitted in recess 125. Recess 125 restricts movement of retaining
portion 611 with respect to second shoe 12 of housing HSG in the
radial direction of housing HSG. Front plate 8 and rear plate 9,
which are in contact with the X-axis ends of the plate portion of
retaining portion 611, restrict movement of retaining portion 611
in recess 125 in the X-axis direction within a predetermined range.
First advance chamber A1 is hydraulically connected to first
pressure-receiving chamber 55 of lock mechanism 5 shown in FIG. 14
through the through hole of retaining portion 611 and communication
hole 56 of first vane 41. First retard chamber R1 is hydraulically
connected to engaging recess 521 of lock mechanism 5 through the
communication groove 57 of first vane 41. Retaining portion 612 of
first spring unit 61 is constructed similar to retaining portion
611. Specifically, the hollow cylindrical portion of retaining
portion 612 retains the other longitudinal end of coil spring 610,
and the plate portion of retaining portion 612 is supported in
recess 418 of first vane 41 so that the recess 418 restricts
movement of retaining portion 612 of first spring unit 61 with
respect to first vane 41 of vane rotor 4 in the radial direction
and in the axial direction of housing HSG. In this way, the
positions of the longitudinal ends of coil spring 610 in the radial
direction and the axial direction of housing HSG are restricted.
During assembling operation, first spring unit 61 is inserted in
the X-axis direction into first advance chamber A1, so that the
retaining portion 611 is fitted in recess 125, and retaining
portion 612 is fitted in recess 418. Coil spring 610 is mounted in
first advance chamber A1 in a compressed state, so as to constantly
bias first vane 41 with respect to second shoe 12 of housing body
10 in the clockwise direction. Second spring unit 62, and third
spring unit 63 are constructed and mounted similar to first spring
unit 61. Second spring unit 62 includes a coil spring 620, and
retaining portions 621 and 622, and third spring unit 63 includes a
coil spring 630, and retaining portions 631 and 632. The biasing
forces of coil springs 610, 620 and 630 are set substantially equal
to each other. The diameters of coil springs 610, 620 and 630 are
equal to about 70% of the maximum widths of first, second and third
advance chambers A1, A2 and A3 in the radial direction,
respectively. As compared to cases where another biasing member
such as a leaf spring is used, the use of coil springs is effective
for easily adjusting the biasing force, and enhancing the
mountability to first, second and third advance chambers A1, A2 and
A3. The construction that a single coil spring is mounted in each
of first, second and third advance chambers A1, A2 and A3, is
effective for making the exhaust valve timing control apparatus 1b
compact in the axial direction, as compared to cases where two coil
springs are arranged in double layers in the X-axis direction in
each of first, second and third advance chambers A1, A2 and A3. In
cases where double coil springs are mounted in each of first,
second and third advance chambers A1, A2 and A3, it may be
difficult to assemble the coil springs to first, second and third
advance chambers A1, A2 and A3, unless the double coil springs are
mounted to retaining portions to form a single spring unit. On the
other hand, according to the present embodiment where a single coil
spring is mounted in each of first, second and third advance
chambers A1, A2 and A3, it is easy to mount the coil spring to from
a spring unit. Moreover, it is also possible as an alternative to
directly mount the coil spring in first, second and third advance
chambers A1, A2 and A3 (recesses 418, 125, etc.), without mounting
each of coil springs 610, 620 and 630 to retaining portions to form
a spring unit. Since recesses 418, 428 and 438, and recesses 115,
125 and 135 restrict deviations of first, second and third spring
units 61, 62 and 63 during operation of exhaust valve timing
control apparatus 1b, this achieves normal operations of biasing
member 6 and exhaust valve timing control apparatus 1b, with no
special support member. For example, retaining portions 611 and 612
may be omitted. However, the provision of retaining portions 611
and 612 according to the present embodiment is effective for more
securely preventing deviations of first, second and third spring
units 61, 62 and 63. When vane rotor 4 rotates with respect to
housing HSG in the counterclockwise direction, coil springs 610,
620 and 630 are compressed. The clockwise side portion of coil
spring 610 is located outside of radial projection 419 of first
vane 41 in the radial direction of housing HSG. The height of
radial projection 419 in the radial direction of vane rotor 4 is
set so that the outside periphery of radial projection 419 is close
to the outside periphery of coil spring 610 with a slight
clearance. Accordingly, when coil spring 610 is compressed and
deformed, the periphery of coil spring 610 facing the radial
projection 419 is brought into contact with the outside peripheral
surface of radial projection 419, so that coil spring 610 is
prevented from deforming over a predetermined distance inwardly in
the radial direction of vane rotor 4. Namely, radial projection 419
serves to guide the coil spring 610. Radial projection 429 of
second vane 42 is constructed similar to radial projection 419, so
as to guide coil spring 630 when vane rotor 4 relatively rotates so
as to compress coil spring 630. As shown in FIG. 17, when rotation
of vane rotor 4 in the counterclockwise direction is restricted by
contact between tip 126 of second shoe 12 and radial projection 419
of first shoe 11, the opposite shoe-side and vane-side retaining
portions 611 and 612 or 621 and 622 or 631 and 632 of each of
first, second and third spring units 61, 62 and 63 are out of
contact with each other, and wounded wires of each of coil springs
610, 620 and 630 are out of contact with each other. In other
words, when the counterclockwise rotation is restricted by the
second stopper mechanism, the circumferential length of each of
first, second and third advance chambers A1, A2 and A3 is set
larger than the length of the respective one of coil springs 610,
620 and 630 under the condition the wounded wires are completely in
contact with each other.
[0062] Hydraulic fluid supply and drainage mechanism 2 of exhaust
valve timing control apparatus 1b is constructed similar to intake
valve timing control apparatus 1a. Exhaust valve timing control
apparatus 1b includes directional control valve 24 other than
directional control valve 24 of intake valve timing control
apparatus 1a, but shares oil pump 1020 and oil pan 25 with intake
valve timing control apparatus 1a.
[0063] <<Operations and Produced Effects by Valve Timing
Control Apparatus>> The following describes operations of
intake valve timing control apparatus 1a and exhaust valve timing
control apparatus 1b.
[0064] <Operations and Produced Effects Related to Phase
Change> The following describes control operations and produced
effects related to phase change by intake valve timing control
apparatus 1a and exhaust valve timing control apparatus 1b.
However, the control operations may be adjusted or modified as
appropriate. First, the following describes how intake valve timing
control apparatus 1a performs a phase change control. FIG. 4 shows
the most retarded state when the internal combustion engine is at
rest or at start. FIG. 5 shows the most advanced state when the
internal combustion engine is operating. At start of the internal
combustion engine, lock mechanism 5 keeps vane rotor 4 locked in
the most retarded position as an initial position which is optimal
for cranking the internal combustion engine, as shown in FIG. 4.
When an ignition switch is turned on, intake valve timing control
apparatus 1a achieves smooth cranking operation, improving the
startability of the internal combustion engine. In a predetermined
low speed and low load region after start of the internal
combustion engine, the controller CU maintains a condition that no
control current is outputted to directional control valve 24.
Accordingly, in directional control valve 24, the spool valve
element is maintained by the elastic force of return spring RS at
the position such that the supply port 240 is hydraulically
connected to second port 242, and first port 241 is hydraulically
connected to drain port 243. Accordingly, working fluid, which is
discharged by oil pump 1020, flows in supply passage 22, enters the
valve body through supply port 240, flows through the second port
242 into advance passage 21, flows in the first and second fluid
passages of intake camshaft 3a and the advance fluid passages 409
of vane rotor 4, and finally flows into first, second and third
advance chambers A1, A2 and A3. The internal pressures of first,
second and third advance chambers A1, A2 and A3 increase with an
increase in the discharge pressure of oil pump 1020. On the other
hand, working fluid is drained from first, second and third retard
chambers R1, R2 and R3 to oil pan 25 through retard passage 20 and
drain passage 23, so that the internal pressures of first, second
and third retard chambers R1, R2 and R3 are held low (at
atmospheric pressure). As the internal pressure of first advance
chamber A1 rises, this hydraulic pressure is supplied through the
communication groove 57 shown in FIG. 14 to second
pressure-receiving chamber 59, so that the engaging portion 511 of
lock piston 51 is subject to a hydraulic force in the X-axis
positive direction. When the hydraulic force is above the elastic
force of coil spring 53, lock piston 51 moves in the X-axis
positive direction. When engaging portion 511 has moved completely
out of engaging recess 521, the lock state is canceled. This allows
vane rotor 4 to rotate freely, so that the valve timing can be
changed arbitrarily. Under the hydraulic pressures supplied to
first, second and third advance chambers A1, A2 and A3, vane rotor
4 rotates with respect to housing HSG from the position shown in
FIG. 4, so as to change the rotational phase (relative rotational
change angle) of intake camshaft 3a with respect to the crankshaft
in the advance direction. This advances the opening and closing
timing of the intake valves, and thereby increases a valve overlap
which is a period when both of the intake valves and exhaust valves
are opened. As a result, in the low speed and low load region, the
combustion efficiency is improved because of use of inertial
charge, thereby stabilizing the rotation of the internal combustion
engine, and improving the fuel efficiency. As shown in FIG. 5, when
vane rotor 4 rotates with respect to housing HSG and reaches the
most advanced position such that the volumetric capacities of
first, second and third advance chambers A1, A2 and A3 are
maximized, and the volumetric capacities of first, second and third
retard chambers R1, R2 and R3 are minimized, then the valve overlap
is maximized. On the other hand, when the internal combustion
engine shifts to an operating state in a predetermined high speed
and high load region, the controller CU outputs a control current
to directional control valve 24. In directional control valve 24,
the spool valve element moves against the elastic force of return
spring RS to the position such that the supply port 240 is
hydraulically connected to first port 241, and second port 242 is
hydraulically connected to drain port 243. Accordingly, working
fluid, which is discharged by oil pump 1020, flows through the
first port 241 of directional control valve 24 into retard passage
20, and flows through the first and second fluid passages of intake
camshaft 3a and the retard fluid passages 408 of vane rotor 4 to
first, second and third retard chambers R1, R2 and R3, so that the
internal pressures of first, second and third retard chambers R1,
R2 and R3 rise. On the other hand, working fluid is drained from
first, second and third advance chambers A1, A2 and A3 to oil pan
25 through the advance passage 21 and drain passage 23, so that the
internal pressures of first, second and third advance chambers A1,
A2 and A3 fall. Under the condition described above, the hydraulic
pressure in second pressure-receiving chamber 59 falls in lock
mechanism 5. On the other hand, as the internal pressure of first
retard chamber R1 increases, this hydraulic pressure is supplied
through the communication hole 56 shown in FIG. 14 to first
pressure-receiving chamber 55, so as to apply a hydraulic force to
a pressure-receiving surface of flange 513 of lock piston 51.
Accordingly, lock mechanism 5 is maintained in a released state in
which lock piston 51 is brought out of engaging recess 521 against
the elastic force of coil spring 53. When the internal pressures of
first, second and third retard chambers R1, R2 and R3 are above the
internal pressures of first, second and third advance chambers A1,
A2 and A3, then the vane rotor 4 rotates with respect to housing
HSG in the counterclockwise direction which is opposite to the
direction of rotation of housing HSG indicated by the arrow in FIG.
4, so as to change the rotational phase (relative rotational change
angle) of intake camshaft 3a with respect to the crankshaft in the
retard direction. This retards the opening and closing timing of
the intake valves, and thereby reduces the valve overlap so as to
enhance the output of the internal combustion engine in the high
speed and high load region. As shown in FIG. 4, when vane rotor 4
rotates with respect to housing HSG and reaches the most retarded
position such that the volumetric capacities of first, second and
third advance chambers A1, A2 and A3 are minimized, and the
volumetric capacities of first, second and third retard chambers
R1, R2 and R3 are maximized, the valve overlap is minimized.
Moreover, for example, when the internal combustion engine shifts
into a predetermined middle speed and middle load region, the
controller CU controls directional control valve 24 so as to hold
the spool valve element in the intermediate operation position such
that the supply passage 22 and drain passage 23 are hydraulically
disconnected from each other. Accordingly, the internal pressures
of first, second and third retard chambers R1, R2 and R3, and
first, second and third advance chambers A1, A2 and A3 are held
constant, and vane rotor 4 is set in an intermediate rotational
position. This serves to achieve a suitable valve timing control in
the middle speed and middle load region, and a suitable balance
between the fuel efficiency and the output of the internal
combustion engine.
[0065] When the internal combustion engine is operating, and intake
camshaft 3a is rotating, an alternating torque (or reverse torque)
acts on intake camshaft 3a due to a reaction torque that is
transmitted to the intake cams of intake camshaft 3a from the valve
springs which bias the intake valves in a closing direction.
Namely, depending on the shape of the intake cams, intake camshaft
3a is subject to alternately a negative torque which is a
counterclockwise torque against clockwise rotation of intake
camshaft 3a, and a positive torque which is a clockwise torque
against counterclockwise rotation of intake camshaft 3a. The
alternating toque is offset to the negative side as a whole.
Namely, if the positive torques and negative torques, which are
generated in each period of rotation of intake camshaft 3a, are
integrated with time, the integral is negative. Accordingly, intake
camshaft 3a is subject to a negative torque as a whole. When the
internal combustion engine is stopped, then operation of oil pump
1020 is stopped, and energization of directional control valve 24
by controller CU is turned off. Accordingly, supply of working
fluid to first, second and third advance chambers A1, A2 and A3,
and first, second and third retard chambers R1, R2 and R3 is
stopped. In summary, immediately after the internal combustion
engine is stopped, the friction or alternating torque offset to the
negative side, which is applied to intake camshaft 3a, serves to
rotate vane rotor 4 with respect to housing HSG in the direction
opposite to the direction of rotation of housing HSG indicated by
the arrow in FIG. 4, i.e. serves to rotate vane rotor 4 with
respect to housing HSG in the retard direction. As a result, after
the internal combustion engine is stopped, vane rotor 4
mechanically moves to the predetermined initial position suitable
for start or restart of the internal combustion engine, i.e. vane
rotor 4 mechanically moves to the most retarded position shown in
FIG. 4, under the friction or alternating torque applied to intake
camshaft 3a. In other words, after the internal combustion engine
is stopped, the valve timing is mechanically brought to a phase
suitable for start or restart of the internal combustion engine.
When vane rotor 4 rotates with respect to housing HSG, and reaches
the most retarded position, then lock piston 51 overlaps with
engaging recess 521 in lock mechanism 5 as viewed in the X-axis
direction. When the internal combustion engine is stopped, the
engaging portion 511 of lock piston 51 fits and engages with
engaging recess 521 by the elastic force of coil spring 53, so that
the lock piston 51 prevents free rotation of vane rotor 4. As
discussed above, in intake valve timing control apparatus 1a, vane
rotor 4 is mechanically rotated to the most retarded position with
respect to housing HSG as an initial position, when the internal
combustion engine is stopped. This is effective for setting the
intake valve timing control apparatus 1a in the initial position
when the internal combustion engine is restarted, and achieving a
stable start and operation of intake valve timing control apparatus
1a.
[0066] The following describes how exhaust valve timing control
apparatus 1b performs a phase change control. Exhaust valve timing
control apparatus 1b operates similar to intake valve timing
control apparatus 1a, except that the advance side and the retard
side are reversed. FIG. 16 shows the most advanced state when the
internal combustion engine is at rest or at start. FIG. 17 shows
the most retarded state when the internal combustion engine is
operating. At start of the internal combustion engine, lock
mechanism 5 holds vane rotor 4 in the most advanced position as an
initial position which is optimal for cranking the internal
combustion engine, as shown in FIG. 16. When the ignition switch is
turned on, exhaust valve timing control apparatus 1b achieves
smooth cranking operation, improving the startability of the
internal combustion engine. In the predetermined low speed and low
load region after start of the internal combustion engine, first,
second and third retard chambers R1, R2 and R3 are supplied with
hydraulic pressures. When the hydraulic force based on the
hydraulic pressures exceeds the biasing force of first, second and
third spring units 61, 62 and 63, then vane rotor 4 rotates in the
retard direction with respect to housing HSG. This retards the
rotational phase of exhaust camshaft 3b, so as to increase the
valve overlap. As shown in FIG. 17, when vane rotor 4 rotates with
respect to housing HSG and reaches the most retarded position such
that the volumetric capacities of first, second and third advance
chambers A1, A2 and A3 are minimized, and the volumetric capacities
of first, second and third retard chambers R1, R2 and R3 are
maximized, the valve overlap is maximized. On the other hand, when
the internal combustion engine shifts to an operating state in the
high speed and high load region, working fluid is supplied to
first, second and third advance chambers A1, A2 and A3. When the
sum of a torque resulting from the hydraulic pressures of first,
second and third advance chambers A1, A2 and A3, and a torque
resulting from the biasing forces of first, second and third spring
units 61, 62 and 63 is above a torque resulting from the hydraulic
pressures of first, second and third retard chambers R1, R2 and R3,
then the vane rotor 4 relatively rotates in the advance direction.
Accordingly, the rotational phase (relative rotational angle) of
exhaust camshaft 3b is advanced so as to reduce the valve overlap.
In other words, first, second and third spring units 61, 62 and 63
also serve to assist the phase change in the advance direction. As
shown in FIG. 16, when vane rotor 4 rotates with respect to housing
HSG and reaches the most advanced position such that the volumetric
capacities of first, second and third advance chambers A1, A2 and
A3 are maximized, and the volumetric capacities of first, second
and third retard chambers R1, R2 and R3 are minimized, the valve
overlap is minimized. When the internal combustion engine is
operating, exhaust camshaft 3b is subject to an alternating torque
which is a negative torque or counterclockwise torque as a whole
against clockwise rotation of exhaust camshaft 3b. When the
internal combustion engine is stopped so as to turn off
energization of directional control valve 24, then the alternating
torque acts on the vane rotor 4 in the counterclockwise direction
or in the retard direction with respect to housing HSG. On the
other hand, biasing member 6 (first, second and third spring units
61, 62 and 63) constantly biases vane rotor 4 with respect to
housing HSG in the clockwise direction or advance direction.
Accordingly, after the internal combustion engine is stopped, vane
rotor 4 is moved by the biasing force of biasing member 6 under
little influence of the alternating torque, to the initial position
suitable for start or restart of the internal combustion engine,
i.e. to the most advanced position. In other words, the valve
timing is mechanically brought to the phase suitable for start or
restart of the internal combustion engine. When vane rotor 4
rotates with respect to housing HSG, and reaches the most advanced
position, then lock piston 51 overlaps with engaging recess 521 in
lock mechanism 5 as viewed in the X-axis direction. When the
internal combustion engine is stopped, engaging portion 511 of lock
piston 51 fits and engages with engaging recess 521 by the elastic
force of coil spring 53, so that lock piston 51 prevents free
rotation of vane rotor 4. As discussed above, in exhaust valve
timing control apparatus 1b, vane rotor 4 is rotated by the biasing
force of biasing member 6 to the most advanced position as an
initial position with respect to housing HSG, when the internal
combustion engine is stopped. This is effective for setting the
exhaust valve timing control apparatus 1b in the initial position
when the internal combustion engine is restarted, and achieving a
stable start and operation of exhaust valve timing control
apparatus 1b.
[0067] <Operation and Produced Effects by Lock Mechanism> As
discussed above, each lock mechanism 5 operates to allow a
corresponding one of intake valve timing control apparatus 1a and
exhaust valve timing control apparatus 1b to start from its initial
position shown in FIG. 4 or 16, independently of presence or
absence of hydraulic pressures. This serves to suppress vibration
of vane rotor 4 which may result from the alternating torque
applied to camshaft 3a or 3b, and thereby suppress abnormal noise
due to collision between first, second and third shoes 11, 12 and
13 of housing HSG and first, second and third vanes 41, 42 and 43
of vane rotor 4, when the internal combustion engine is started.
Moreover, it is possible to prevent knocking, etc., and thereby
achieve stable operations of the internal combustion engine, intake
valve timing control apparatus 1a, and exhaust valve timing control
apparatus 1b. These effects are produced, not only when the
internal combustion engine is at start, but also when the internal
combustion engine is at idle when no high hydraulic pressure is
generated and supplied. The lock position is located at the most
retarded position or the most advanced position in the present
embodiment, but may be modified to a position between the most
retarded position and the most advanced position which is suitable
for start, etc., of the internal combustion engine, and used as an
initial position of intake valve timing control apparatus 1a or
exhaust valve timing control apparatus 1b.
[0068] As described above, lock mechanism 5 includes: slide hole
501 formed in vane rotor 4; lock piston 51; engaging recess 521
formed in the inside surface of housing HSG; and coil spring 53.
Lock piston 51 moves out of and into vane rotor 4 according to the
operating state of the internal combustion engine, and thereby
allows or prevents relative rotation between housing HSG and vane
rotor 4. For example, when vane rotor 4 is rotated to the
predetermined initial position by the biasing force of biasing
member 6 and/or the alternating torque, then lock piston 51 is
mechanically engaged with engaging recess 521 by the biasing force
of coil spring 53. This eliminates the necessity of provision of an
actuator for actuating the locking operation. This is also
effective for simplifying the mechanism, and reducing the
manufacturing cost, and enhancing the reliability of the locking
operation, as compared to cases where the locking means is
implemented by a clutch mechanism or lever mechanism. Instead of or
in addition to coil spring 53, another elastic member, such as a
leaf spring, may be used as a biasing member for biasing the lock
piston 51. Although the lock state is released by application of
hydraulic pressure to lock piston 51 in the present embodiment,
another releasing mechanism may be provided to release the lock
piston 51 from engaging recess 521. Although the lock mechanism
(i.e. lock piston 51) is provided in first vane 41 of vane rotor 4
in the present embodiment, the lock mechanism may be provided in
rotor 40 of vane rotor 4. However, the provision in first vane 41
is advantageous in reducing the diameter of rotor 40.
Alternatively, the lock mechanism (i.e. lock piston 51) may be
provided in housing HSG, for locking the vane rotor 4 with respect
to housing HSG. However, the provision in vane rotor 4 is
advantageous in reducing the size of housing HSG.
[0069] <Locking Operation Smoothed by Suitable Direction of
Movement of Lock Piston> Lock piston 51 may be arranged to move
forward and rearward in a direction other than the direction of the
axis of rotation O, for example, in a radial direction of housing
HSG. In other words, the cylinder accommodating the lock piston 51
may be formed to extend in a direction other than the direction of
the axis of rotation O, for example, in a radial direction of
housing HSG. However, in the present embodiment, slide hole 501 is
formed to extend in the direction of the axis of rotation O (or in
the X-axis direction), wherein the tip (engaging portion 511) of
lock piston 51 moves into or out of slide hole 501 in the direction
of the axis of rotation O. This construction is advantageous in
reducing the diameter of intake valve timing control apparatus 1a
or exhaust valve timing control apparatus 1b. Moreover, the
construction is effective for preventing the operation of lock
mechanism 5 from being influenced by the centrifugal force
resulting form rotation of vane rotor 4. For example, if lock
piston 51 is arranged to move in a radial direction of housing HSG,
lock piston 51 is applied with the centrifugal force resulting form
rotation of vane rotor 4 which acts in the direction of movement of
lock piston 51. In such cases, when engine speed changes so as to
change the magnitude of the centrifugal force, then the force
required to actuate the lock piston 51 also changes. The
construction according to the present embodiment is however subject
to no such problem, and thereby serves to stabilize the locking
operation of intake valve timing control apparatus 1a or exhaust
valve timing control apparatus 1b.
[0070] <Locking Operation Smoothed by Back Pressure Relief
Section> The back pressure relief section serves to smooth the
movement of lock piston 51 by eliminating the effect of pressure in
back pressure chamber 50, when intake valve timing control
apparatus 1a or exhaust valve timing control apparatus 1b is in
operation. Specifically, when engaging portion 511 moves out of
engaging recess 521 so that lock piston 51 moves in the X-axis
positive direction, and the volumetric capacity of back pressure
chamber 50 decreases, then air in back pressure chamber 50 escapes
through the back pressure relief section to the low pressure space
in the internal combustion engine. This serves to keep the internal
pressure of back pressure chamber 50 low. On the other hand,
working fluid leaks through the clearance around the back pressure
chamber 50, and flows into back pressure chamber 50. This working
fluid is also drained through the back pressure relief section to
the oil-lubricated space in the internal combustion engine.
Accordingly, when back pressure chamber 50 is contracting, the
movement of lock piston 51 is prevented from being disturbed by
such air and oil, and the back pressure of lock piston 51 is
relieved. In this way, the back pressure relief section serves to
achieve smooth operation of lock piston 51, i.e. smooth sliding
motion of lock piston 51 in slide hole 501, and allow the lock
state to be smoothly released.
[0071] <Locking Operation Smoothed by Wedging Effect> Since
the tip (or engaging portion 511) of lock piston 51 has the form of
a truncated cone, and has a diameter that gradually decreases as
followed in the X-axis negative direction toward engaging recess
521 as described above, lock piston 51 can easily engage with
engaging recess 521. This effect is enhanced by the shape of
engaging recess 521 whose diameter gradually increases as followed
in the X-axis positive direction toward the opening of engaging
recess 521. The locking operation is thus smoothed. Moreover, each
of engaging portion 511 and engaging recess 521 has an inclined
surface or tapered surface. Specifically, the outside periphery of
engaging portion 511 is formed with the inclined surface whose
diameter gradually decreases as followed in the X-axis negative
direction toward the tip of engaging portion 511, whereas the
inside periphery of engaging recess 521 is formed with the inclined
surface whose diameter gradually decreases as followed in the
X-axis negative direction toward the bottom of engaging recess 521.
Under the condition shown in FIG. 4 that the relative rotation
between housing HSG and vane rotor 4 is restricted by the first
stopper mechanism, the central axis of engaging recess 521 is
located with a slight offset with respect to the central axis of
engaging portion 511 in the counterclockwise direction toward first
shoe 11, as shown in FIG. 14. Accordingly, when lock piston 51 is
inserted in engaging recess 521 to establish the lock state, the
inclined surfaces of engaging portion 511 and engaging recess 521
are brought into contact with one another on the clockwise side,
thereby causing a component of force for pressing the first vane 41
in the counterclockwise direction toward the first shoe 11. This is
a wedging effect. Namely, when engaging portion 511 is moved in the
X-axis negative direction, and engaged with engaging recess 521
under the biasing force of coil spring 53, the clockwise side
inclined surface of engaging portion 511 is brought into sliding
and pressing contact with the clockwise side inclined surface of
engaging recess 521, while engaging portion 511 of lock piston 51
is subject to a reaction force in the counterclockwise direction.
Accordingly, first vane 41 accommodating the lock piston 51 is also
subject to the reaction force in the counterclockwise direction
toward the first shoe 11. As a result, the engagement of lock
piston 51 with engaging recess 521 is effective for pressing the
first vane 41 onto first shoe 11, and thereby ensuring that the
vane rotor 4 is retained at the bound defined by the first stopper
mechanism (i.e. the most retarded position as the initial
position). The contact between the inclined surfaces of engaging
portion 511 and engaging recess 521 described above is thus
achieved by the provision of the offset between the central axes of
engaging portion 511 and engaging recess 521, but may be achieved
by suitably modifying the shapes of engaging portion 511 and
engaging recess 521. However, the provision of the offset between
the central axes of engaging portion 511 and engaging recess 521 is
advantageous in simplifying the structure. Although both of
engaging portion 511 and engaging recess 521 are formed with the
inclined surfaces in the present embodiment, this construction may
be modified so that only one of engaging portion 511 and engaging
recess 521 is provided with the inclined surface. This alternative
construction can produce a wedging effect as in the present
embodiment. However, the construction according to the present
embodiment is effective for reducing friction between engaging
portion 511 and engaging recess 521, while effectively producing a
wedging effect.
[0072] <Locking Operation Smoothed by Positioning Means> The
positioning between lock piston 51 and engaging recess 521 is
accurately implemented by a positioning means including the
positioning pin 905, etc., so as to achieve smooth engaging
operation of lock piston 51. The following describes operation of
the positioning means including the positioning pin 905, etc.
First, the following briefly describes a process of assembling the
intake valve timing control apparatus 1a and exhaust valve timing
control apparatus 1b. First, rear plate 9 is inserted and mounted
in fitting recess 101 of housing body 10. This is implemented by:
mounting the sleeve 52 in recess 900 of rear plate 9; setting the
rear plate 9 so that the X-axis positive side surface of rear plate
9 is directed upwardly in the vertical direction; mounting and
holding the sealing ring S1 in sealing ring groove 906, and sealing
rings S2 in annular sealing ring grooves 907, 908 and 909 in rear
plate 9; and assembling the housing body 10 from the X-axis
positive side (from above in the vertical direction) to rear plate
9 so that the rear plate 9 is fitted in fitting recess 101. In
assembling the housing body 10 to rear plate 9, the rotational
position of housing body 10 with respect to rear plate 9 is
adjusted so that the positioning recess 114 of housing body 10
faces or conforms to positioning pin 905 of rear plate 9. Then,
positioning pin 905 is fixedly fitted in positioning recess 114. In
this way, the position of housing body 10 with respect to rear
plate 9 in the circumferential direction is set suitably. Under
this condition, the bolt holes of female thread portions 901, 902
and 903 of rear plate 9 face or conform to bolt holes 110, 120 and
130 of housing body 10, respectively, as viewed in the X-axis
direction. Next, vane rotor 4 is inserted and mounted in housing
body 10. Simultaneously, sealing members 118, 128 and 138, and
sealing members 413, 423 and 433 for sealing between the working
fluid chambers A1, A2, A3, R1, R2 and R3 are also mounted. For
exhaust valve timing control apparatus 1b, biasing member 6 is also
mounted. Moreover, lock mechanism 5 is mounted by: inserting the
lock piston 51 in sealing member 502 press-fitted in slide hole 501
of vane rotor 4; inserting the coil spring 53 into the inside of
lock piston 51; and inserting the spring retainer 54 into slide
hole 501. According to the positioning by positioning pin 905, the
sleeve 52, which is fixed in engaging recess 521 in rear plate 9,
faces and conforms to lock piston 51 in slide hole 501 with a
slight offset, under the condition that first vane 41 of vane rotor
4 is in contact with first shoe 11 of housing body 10. Then, front
plate 8 is brought from the X-axis positive side (from above in the
vertical direction), and attached to housing body 10, and bolts b1,
b2 and b3 are used to fix the front plate 8, housing body 10, and
rear plate 9 together. Front plate 8 is mounted to housing body 10
under the condition that the sealing ring S3 is mounted in annular
sealing ring groove 89 of front plate 8. The provision of sealing
ring grooves 906, 907, 908, 909 and 89 is effective for easily
retaining the sealing rings S1, S2 and S3, and thereby easily
assembling the intake valve timing control apparatus 1a or exhaust
valve timing control apparatus 1b. As described above, positioning
pin 905 in pin hole 904 and positioning recess 114 serve as a
positioning means for adjusting and defining the rotational
position of rear plate 9 with respect to housing body 10 by
adjusting relative circumferential position between lock piston 51
and engaging recess 521 during assembling operation of intake valve
timing control apparatus 1a or exhaust valve timing control
apparatus 1b. The radial positions of lock piston 51 and engaging
recess 521 are set substantially identical, when rear plate 9 is
fitted in fitting recess 101 of housing body 10. In this way, lock
piston 51 and sleeve 52 are correctly positioned, so that the lock
piston 51 can smoothly engage with sleeve 52. The construction that
the positioning pin 905 is located adjacent to recess 900 (engaging
recess 521) is effective for correctly positioning the lock piston
51 and engaging recess 521. The construction that the pin hole 904
is located on the side of sealing ring grooves 906 and 907 where
first retard chamber R1 is located, is effective for preventing the
sealing performance of the sealing rings S1 and S2 from being
adversely affected. Vane rotor 4 is supported in through hole 92
which is formed in the center of rear plate 9 and through which
intake camshaft 3a passes, and fixed to the axial end portion 30 of
intake camshaft 3a. Accordingly, under the influence of a force
applied from timing belt 1010 which is wound around pulley 100 of
housing HSG, housing HSG may be inclined within a slight angle
range with respect to the axis of rotation of vane rotor 4 (i.e.
the X-axis), and swing about cylindrical portion 91 of rear plate 9
in which through hole 92 is formed. As a result, engaging recess
521 provided in housing HSG may be deviated with respect to lock
piston 51 provided in vane rotor 4. However, according to the
present embodiment where rear plate 9 is formed with engaging
recess 521, the distance (moment arm) between engaging recess 521
and cylindrical portion 91 as a fulcrum, is shorter than in the
case where the engaging recess is formed in front plate 8
alternatively. Accordingly, displacement of engaging recess 521 due
to swinging motion of housing HSG in a direction perpendicular to
the X-axis, is smaller, so that deviation of lock piston 51 from
engaging recess 521 is smaller or suppressed. Moreover, the
construction that the boss portion 401 of vane rotor 4 is inserted
in through hole 92, is effective for suppressing the inclination
and displacement of vane rotor 4 with respect to housing HSG within
a predetermined range.
[0073] <Produced Effects by Timing Belt and Pulley> In the
present embodiment, the torque from the crankshaft is transmitted
to intake valve timing control apparatus 1a or exhaust valve timing
control apparatus 1b by the combination of timing belt 1010 and
pulley 100 driven by timing belt 1010. As compared to an
alternative combination of a timing chain and a sprocket driven by
the timing chain, the construction according to the present
embodiment is advantageous in the quietness, manufacturing cost,
and lightness of intake valve timing control apparatus 1a or
exhaust valve timing control apparatus 1b.
[0074] <Produced Effects by Weight Reduction> Housing HSG and
vane rotor 4 may be formed of a material other than aluminum-based
metal materials, for example, an iron-based metal material.
However, in a typical valve timing control apparatus using a timing
belt and a pulley, the width of the timing belt needs to be wide
enough to transmit adequate torque. Accordingly, the width of the
pulley needs to be wide enough to engage with the timing belt. This
results in an increase in the size of the valve timing control
apparatus in the axial direction (the width direction of the
pulley), and thereby results in an increase in the weight of the
valve timing control apparatus. In contrast, intake valve timing
control apparatus 1a or exhaust valve timing control apparatus 1b
according to the present embodiment is formed light in weight,
because both of housing body 10 and vane rotor 4 are formed of a
light metal material, specifically, an aluminum-based metal
material. Conversely, the combination of the timing belt and the
pulley can be adapted in intake valve timing control apparatus 1a
or exhaust valve timing control apparatus 1b, because the moment of
inertia of housing body 10 and vane rotor 4 is small so that the
load applied to the torque transmitting section is low.
[0075] <Durability of Apparatus Enhanced by Features of Form of
Fixing Vane Rotor> A typical valve timing control apparatus of
so-called a vane type may be subject to a problem that when a vane
rotor mounted in a housing is fixed to a camshaft by a single
fixing portion, the strength of fixation between the vane rotor and
the camshaft is insufficient. For example, in cases where a vane
rotor is fixed to a camshaft by a single camshaft bolt that is
provided at the axis of rotation, an alternating torque is
transmitted from valve springs and applied to the camshaft around
the central axis of the camshaft (or camshaft bolt), so that the
camshaft bolt tends to be easily loosed. On the other hand, if the
camshaft is fixed to the vane rotor by tightly screwing the single
camshaft bolt for preventing the looseness, the axial force of the
camshaft bolt may cause a large contact pressure to act on the vane
rotor. This may result in deforming the vane rotor, when the vane
rotor is made of a soft material, such as an aluminum material. In
contrast, according to the present embodiment, the fixation is
implemented by forming the rotor 40 of vane rotor 4 with a
plurality of fixing portions (bolt holes 403, 404 and 405) for
fixing the vane rotor 4 to camshaft 3a or 3b. In this construction,
the applied torque around the central axis of camshaft 3a or 3b is
distributed to the fixing portions (bolt holes 403, 404 and 405)
arranged in the circumferential direction around the central axis
of camshaft 3a or 3b, so that the load to each fixing portion is
reduced, and the direction of the force applied to each fixing
portion is changed, as compared to cases where the fixation between
vane rotor 4 and camshaft 3a or 3b is implemented by a single
fixing portion. Therefore, the strength of fixation between vane
rotor 4 and camshaft 3a or 3b can be enhanced in the present
embodiment. The number of the fixing portions is three in the
present embodiment, but may be changed to another number greater
than or equal to two. However, the fixation based on the three
fixing portions is advantageous in enhancing the strength of
fixation, while reducing the number of parts, and enhancing the
ease of processing and assembling. Each fixing portion is not
limited to the form of bolt hole 403, 404 or 405, but may be
implemented by swaging, welding, etc. However, the construction
according to the present embodiment is advantageous in simplifying
the attachment of the valve timing control apparatus to the
camshaft, and simplifying the management of fixing force.
Specifically, the construction that vane rotor 4 is fixed by three
camshaft bolts 33, 34 and 35, is effective for preventing the
alternating torque around the axis of rotation O from applying each
camshaft bolt 33, 34 or 35 with a torque applied around the central
axis of camshaft bolt 33, 34 or 35. This prevents camshaft bolt 33,
34 or 35 from being loosed. This also serves to provide a
sufficient fixing force as a whole, while reducing the axial force
of each camshaft bolt 33, 34 or 35. This results in reducing the
contact pressure applied to vane rotor 4, and thereby reducing the
deformation of vane rotor 4. These advantageous effects may be
produced by an alternative construction that the fixing portions
are spaced from one another, but arranged in the radial direction
as different from the present embodiment. However, the construction
according to the present embodiment that the fixing portions are
arranged in the circumferential direction is advantageous in
reliably and evenly distributing the load in the circumferential
direction around the axis of rotation O to the plurality of fixing
portions, as compared to the alternative construction. In this way,
the construction according to the present embodiment is effective
for efficiently enhancing the entire strength of fixing, while
reducing the load to each fixing portion. The plurality of fixing
portions may be unevenly spaced from one another as different from
the present embodiment. However, the construction according to the
present embodiment that the fixing portions (bolt holes 403, 404
and 405) are substantially evenly spaced from one another is
advantageous in easily keeping the vane rotor 4 in balance around
its axis of rotation. This is also advantageous in easily keeping
the camshaft 3a or 3b in balance around its axis of rotation,
because the fixing portions (bolt holes 32) of camshaft 3a or 3b
are also substantially evenly spaced in conformance with the
positions of bolt holes 403, 404 and 405. In addition, according to
the present embodiment, each portion between adjacent two of the
fixing portions can be formed to have an even and relatively large
thickness. This serves to ensure the strength of rotor 40, even
when the fixing portions are formed by removing parts from the base
product of rotor 40, like the bolt hole 403, 404 or 405 in the
present embodiment, which tends to adversely affect the strength of
rotor 40. The even spacing is also advantageous in effectively
preventing the interference among the heads 331, 341 and 351 of
camshaft bolts 33, 34 and 35 that are inserted in bolt holes 403,
404 and 405.
[0076] <Durability of Apparatus Enhanced by Features of Anodic
Oxide Coating Film> Each of housing body 10 and vane rotor 4 is
formed of an aluminum-based metal material, and thereby relatively
soft. Accordingly, each of housing body 10 and vane rotor 4 is
applied with surface treatment, for enhancing the wear resistance
and durability. The surface treatment is implemented by anodic
oxidation treatment, which is advantageous in rust resistance, wear
resistance, evenness of coating thickness, operating facility, etc.
Each aluminum-based metal material may be selected from materials
that are advantageous in enhancing the wear resistance of the oxide
coating film. An anodic oxide coating film is a kind of oxide
coating film, which has a relatively high surface roughness, and
which is formed with a lot of pores (or projections and recesses).
The pores may be sealed or filled by pore-sealing treatment after
the anodic oxidation treatment, so that the anodic oxide coating
film loses adsorptive activity. In such cases, half pore-sealing
treatment is more desirable than full pore-sealing treatment, in
order to avoid complicated management, and avoid the occurrence of
cracks. In cases of half pore-sealing treatment, each pore still
has an opening, and is capable to hold oil therein, thus
maintaining a lubricated state, as in cases where no pore-sealing
treatment is performed. In order to further enhance the wear
resistance, the surface treatment may be implemented by hard
alumilite treatment. In such cases, it is desirable that no
pore-sealing treatment is performed, because pore-sealing treatment
may adversely affect the enhanced wear resistance. The enhancement
of wear resistance may be implemented by surface treatment other
than anodic oxidation treatment, such as hard chrome plating, or
nickel electroless plating. With regard to housing body 10, the
pulley 100 is formed of an aluminum-based metal material, as part
of housing body 10. It is highly desirable to enhance the wear
resistance of pulley 100, because pulley 100 is subject to a
driving torque transmitted through the timing belt 1010. On the
other hand, the aluminum-based metal material of housing body 10 is
implemented by a relatively soft material, so that it becomes easy
to accurately form the teeth of pulley 100. In the present
embodiment, the outside periphery of housing body 10, i.e. the
surface of pulley 100, is anodized, so that an anodic oxide coating
film layer is present at the outside periphery of housing body 10.
This feature is effective for enhancing the hardness and wear
resistance of the surface of pulley 100 in meshing contact with
timing belt 1010. On the other hand, the inside periphery of
housing body 10 is formed with an anodic oxide coating film layer.
This feature serves to enhance the hardness and wear resistance of
the inside periphery of housing body 10 that is in sliding contact
with first, second and third vanes 41, 42 and 43, and rotor 40, and
in contact with biasing member 6. Incidentally, at both axial ends
of housing body 10, all of longitudinal end surface 105, bottom
surface 102, inside peripheral surface 103, and longitudinal end
surface 104 are applied with no anodic oxidation treatment. There
is however no problem, because the longitudinal end surface 105,
bottom surface 102, and inside peripheral surface 103 are in fixed
contact with the sealing plates (front plate 8, and rear plate 9),
and the longitudinal end surface 104 is in contact with no other
member, so that all of longitudinal end surface 105, bottom surface
102, inside peripheral surface 103, and longitudinal end surface
104 are not in sliding contact. With regard to vane rotor 4, the
outside peripheral surface of first, second and third vanes 41, 42
and 43, and rotor 40 (the outside peripheral surface 411, etc.) is
applied with anodic oxidation treatment. This is effective for
enhancing the wear resistance of the surface of vane rotor 4 in
sliding contact with the inside periphery of housing body 10. The
axial end surfaces of vane rotor 4 are also applied with anodic
oxidation treatment. This enhances the wear resistance of the
surface of vane rotor 4 in sliding contact with the sealing plates
(front plate 8, and rear plate 9) at the axial ends of housing body
10. Vane rotor 4 may be formed of a slightly harder material than
housing body 10, because the requirement about hardness is lower
for vane rotor 4 than for housing body 10 for which it is desirable
to use a soft material for accurately forming the teeth of pulley
100. More specifically, the first stopper mechanism, which is
constituted by flat portion 111 of housing body 10 and flat portion
415 of vane rotor 4, and the second stopper mechanism, which is
constituted by tip 126 of housing body 10 and radial projection 419
of vane rotor 4, are applied with anodic oxidation treatment. This
feature is effective for ensuring the hardness of the contact
surfaces of each stopper mechanism, and thereby preventing the
deformation thereof, enhancing the wear resistance, and enhancing
the operation of the stopper mechanisms as described in detail
below. Moreover, in valve timing control apparatus 1, boss portion
401 of vane rotor 4 is subject to a relatively high load in the
radial directions, when housing HSG is rotating under condition
that torque is transmitted through the timing belt 1010 so that the
tension of timing belt 1010 is applied to pulley 100, because boss
portion 401 pivotally supports the housing HSG. This may cause wear
in boss portion 401, if vane rotor 4 including the boss portion 401
is formed of a relatively soft material, such as an aluminum-based
metal material. Specifically, it tends to cause adhesion between
the inside periphery of through hole 92 of housing HSG and the
outside periphery of boss portion 401 in sliding contact with one
another, and thereby cause adhesion wear in boss portion 401. In
contrast, in the present embodiment, vane rotor 4 is formed of an
aluminum-based material, and the outside periphery of boss portion
401 is formed with an anodic oxide coating film. This serves to
suppress such adhesion at the surface of boss portion 401 in
sliding contact with housing HSG, and thereby suppress wear of boss
portion 401. The pores of anodic oxide coating film can hold
lubricating oil for a long period of time. For example, even in
situations where the internal combustion engine is at rest for a
period from some days to some months so that the valve timing
control apparatus 1 is also at rest, the lubricating oil is held at
the sliding contact surface of boss portion 401, and the held
lubricating oil functions well at restart of the internal
combustion engine, and serves to suppress wear of boss portion 401.
Namely, the effect of reducing wear of boss portion 401 is further
enhanced by the characteristic shape of the anodic oxide coating
film. In this way, valve timing control apparatus 1 is maintained
in a preferable condition where wear is suppressed by a synergy of
the effect of reducing adhesion and the effect of holding
lubricating oil.
[0077] <Durability of Apparatus Enhanced by Features of
Materials> Each sealing plate (front plate 8, rear plate 9) are
formed of a harder material (iron-based metal material) than
housing body 10 (aluminum-based metal material). This feature
serves to enhance the strength of front plate 8 that serves as a
seat receiving the bolts b1, b2 and b3, and enhance the strength of
each female thread portion 901, 902 or 903 of rear plate 9 in which
bolt b1, b2 or b3 is screwed, thus enhancing the durability of
valve timing control apparatus 1. This feature also serves to
suppress wear that may be caused by sliding contact between coil
spring 53 of lock mechanism 5 and the X-axis negative side surface
of front plate 8. Moreover, each sealing plate 8, 9 is formed of a
material (iron-based metal material) having a higher wear
resistance than vane rotor 4 (aluminum-based metal material). This
feature serves to enhance the durability of the portions of the
sealing plates in sliding contact with vane rotor 4 (axial end
surfaces, and boss portion 401). In other words, the durability of
valve timing control apparatus 1 is enhanced, because the sliding
surface of vane rotor 4 (axial end surfaces, and boss portion 401)
is hardened by anodic oxidation treatment, and also the
corresponding sliding surface of housing HSG is hardened.
Specifically, each sealing plate 8, 9 is formed of an iron-based
metal material, such as stainless steel, and thereby has a high
hardness, high wear resistance, and high durability. This feature
is advantageous also in the processing facility, manufacturing
cost, etc. More specifically, each sealing plate 8, 9 is formed by
forging, which is advantageous in strengthening. However, each
sealing plate 8, 9 may be formed by another processing, such as
stamping, casting, etc. Each sealing plate 8, 9 may be formed of a
material having a higher hardness or higher wear resistance than
aluminum-based metal materials, for example, a metal material such
as magnesium, or a non-metal material such as ceramics. Sealing
plates 8, 9 may be formed of an aluminum-based metal material, and
anodized at the contact axial end surfaces and the inside periphery
of through hole 92 so as to enhance the wear resistance of the
portion in sliding contact with vane rotor 4 (axial end surfaces,
and boss portion 401).
[0078] <Durability of Apparatus Enhanced by Features of Lock
Mechanism> The construction that the vane rotor 4 is formed of
an aluminum-based metal material may cause a concern about wear of
the cylinder (slide hole 501) that is formed in vane rotor 4 and
accommodates the lock piston 51. This is because lock piston 51
moves forward and backward in the cylinder during operation of lock
mechanism 5, and because first, second and third vanes 41, 42 and
43 may vibrate due to the alternating torque from camshaft 3a or
3b, so as to cause fluctuations in hydraulic pressures in the
working fluid chambers A1, R1, and thereby cause fluctuations in
hydraulic pressures in first pressure-receiving chamber 55 and
second pressure-receiving chamber 59, even when lock mechanism 5 is
not operated. In order to solve this problem, in the present
embodiment, sealing member 502 is fixed in slide hole 501, and lock
piston 51 is slidably mounted in sealing member 502. Sealing member
502 is formed of a material having a higher wear resistance than
aluminum-based metal materials, specifically, formed of an
iron-based metal material. Namely, sealing member 502 having a
higher wear resistance than slide hole 501 is in sliding contact
with lock piston 51. This feature serves to suppress wear of the
cylinder (slide hole 501) which may be caused by forward and
backward movement of lock piston 51 without sealing member 502.
Sealing member 502 is provided separately from vane rotor 4. This
feature is advantageous in enhancing the forming accuracy of the
sliding surface of the cylinder, because it is possible to select a
material that is highly desirable for sealing member 502
constituting the sliding surface. Sealing member 502 may be formed
small, if sealing member 502 remains in contact with lock piston
51. If lock piston 51 moves in the entire range of slide hole 501,
the size of sealing member 502 in the longitudinal direction may be
set equal to that of slide hole 501. The cross-sectional shape
(inside periphery, outside periphery) of sealing member 502 may be
other than a circular shape, for example, an elliptic shape or a
rectangular shape. In such cases, the cross-sectional shape of
slide hole 501 is conformed to the shape of sealing member 502.
[0079] On the other hand, the feature that the sealing member 502
is formed of a material having a higher wear resistance and
hardness than vane rotor 4 (slide hole 501) may cause a concern
that during assembling operation, sealing member 502 is fixed in
slide hole 501 under condition that the sealing member 502 is
inclined with respect to the longitudinal axis of slide hole 501
(which is called galling). In such cases, lock piston 51, which is
slidably mounted in sealing member 502, is also inclined with
respect to the longitudinal axis of slide hole 501, so that lock
piston 51 may be in unbalanced contact with housing HSG (engaging
recess 521). The unbalanced contact may cause friction, or cause a
trouble that lock piston 51 tends to be undesirably easily moved
out of engaging recess 521, thus adversely affecting the operation
of lock mechanism 5. This tends to be more significant in the
present embodiment where each of engaging portion 511 and engaging
recess 521 is formed with an inclined surface to produce a wedging
effect. This may cause a trouble that lock piston 51 tends to be
undesirably more easily moved out of engaging recess 521. In order
to solve this problem, in the present embodiment, the surface of
slide hole 501 is anodized so as to enhance the hardness. This
feature serves to prevent the inclination of sealing member 502
when sealing member 502 is fixed in slide hole 501, thereby
suppressing the occurrence of unbalanced contact, keeping the
operation of lock mechanism 5 normal, and keeping the
controllability of valve timing control apparatus 1 normal. This
advantageous effect is further significant, because each of
engaging portion 511 and engaging recess 521 is formed with an
inclined surface to produce a wedging effect. Incidentally, the
anodic oxidation treatment may be applied only to a portion of the
surface of slide hole 501 with which sealing member 502 is in fixed
contact. The form of fixing the sealing member 502 to slide hole
501 may be easily implemented by press-fitting. However, the
fixation based on press-fitting may cause a relatively high
possibility that the sealing member 502 is set with inclination
(galling of sealing member 502 is caused against vane rotor 4). In
contrast, in the present embodiment, sealing member 502 is
press-fitted in slide hole 501 that is anodized, namely, sealing
member 502 is press-fitted in slide hole 501 whose surface is
hardened by anodic oxidation treatment. This feature serves to
suppress the inclination of sealing member 502, while making it
easy to mount and fix the sealing member 502 to slide hole 501. In
addition, in the present embodiment, sealing member 502 is formed
of a material having a higher hardness or wear resistance than
anodic oxidation coating, specifically, formed of an iron-based
metal material. This feature serves to enhance the effect of
suppressing wear of the cylinder (slide hole 501) as compared to
cases where the anodized slide hole 501 is directly in sliding
contact with lock piston 51. The feature further serves to suppress
the deformation of sealing member 502, when sealing member 502 is
press-fitted in the anodized slide hole 501.
[0080] Moreover, the durability of lock mechanism 5 is further
enhanced by suppressing the frequency of operation of lock piston
51. Specifically, lock mechanism 5 is configured so that lock
piston 51 operates against the biasing force of coil spring 53 in
response to hydraulic pressures in first and second
pressure-receiving chambers 55 and 59 which are supplied according
to the operating state of the internal combustion engine.
Specifically, first pressure-receiving chamber 55 is supplied with
the hydraulic pressure in first retard chamber R1, whereas second
pressure-receiving chamber 59 is supplied with the hydraulic
pressure in first advance chamber A1. Accordingly, during operation
of valve timing control apparatus 1, lock piston 51 is maintained
in its released state, constantly when at least one of the
hydraulic pressures in first advance chamber A1 and first retard
chamber R1 is supplied to lock mechanism 5. This feature serves to
eliminate the necessity of provision of an additional actuator for
canceling the lock state, simplify the construction, maintain the
reliability of the locking operation, lower the manufacturing cost,
and prevent that the locking operation and the releasing operation
are frequently repeated in response to movement of vane rotor 4 in
the advance direction and the retard direction. This serves to
reduce the frequency of operation of lock piston 51, and thereby
enhance the durability of valve timing control apparatus 1. The
construction may be modified so that first pressure-receiving
chamber 55 is supplied with the hydraulic pressure from first
advance chamber A1, and second pressure-receiving chamber 59 is
supplied with the hydraulic pressure from first retard chamber R1.
More specifically, slide hole 501 and sealing member 502 constitute
a stepped cylinder having a larger-diameter portion and a
smaller-diameter portion, wherein sealing member 502 is inserted
and mounted in slide hole 501, and wherein the size of sealing
member 502 in the X-axis direction is smaller than slide hole 501.
In conformance with this shape, lock piston 51 has the form of a
stepped pin having a larger-diameter portion (flange 513) and a
smaller-diameter portion (sliding portion 512, engaging portion
511). The smaller-diameter portion (sliding portion 512) of lock
piston 51 is disposed in sliding contact with the inside periphery
of sealing member 502, whereas the larger-diameter portion (flange
513) of lock piston 51 is disposed in sliding contact with the
inside periphery of slide hole 501. This construction defines the
first pressure-receiving chamber 55 in slide hole 501 between
sealing member 502 and the larger-diameter portion (flange 513) of
lock piston 51. In this way, the provision of sealing member 502
makes it possible to easily define the first pressure-receiving
chamber 55 and second pressure-receiving chamber 59 liquid-tightly
separated from one another, and apply the lock piston 51 with
hydraulic forces which are produced by first advance chamber A1 and
first retard chamber R1 independently of one another.
Alternatively, the shapes of the cylinder (slide hole 501) and lock
piston 51, and the arrangement of communication hole 56 and
communication groove 57 may be modified so as to modify the shapes
and positions of the first and second pressure-receiving chambers
55 and 59 as desired. For example, sealing member 502 may be
inserted and mounted from either one of the longitudinal ends of
slide hole 501. The larger-diameter portion (part of flange 513) of
lock piston 51 may be constructed to move out of vane rotor 4, and
move into engaging recess 521, whereas the smaller-diameter portion
of lock piston 51 constantly remains in slide hole 501. In such
cases, the larger-diameter portion of lock piston 51 serves as the
distal end portion of lock piston 51, whereas the smaller-diameter
portion of lock piston 51 serves as the proximal end portion of
lock piston 51. In such cases, the biasing member (coil spring 53)
may be arranged to bias the lock piston 51 in a direction from the
smaller-diameter portion (proximal end) to the larger-diameter
portion (distal end).
[0081] The feature that the slide hole 501 is formed with an anodic
oxidation coating film serves to suppress wear of slide hole 501
that may be caused by sliding motion of flange 513 of lock piston
51. Moreover, the many pores of the anodic oxidation coating film
hold lubricating oil for a long period of time. The lubricating oil
held at slide hole 501 serves to suppress wear of slide hole 501,
even when the internal combustion engine is restarted so that valve
timing control apparatus 1 operates and the rear end corner of
flange 513 of lock piston 51 slides on the inside peripheral
surface of slide hole 501 after the condition that the internal
combustion engine is at rest for a period from some days to some
months so that the valve timing control apparatus 1 is also at
rest. Namely, the effect of reducing wear of slide hole 501 is
further enhanced by the function of holding lubricating oil which
is based on the characteristic shape of the anodic oxide coating
film. In this way, the anodic oxidation treatment serves to
suppress the inclination of sealing member 502 (and the inclination
of lock piston 51), and enhance the wear resistance and lubrication
of the portion of slide hole 501 in sliding contact with flange 513
of lock piston 51. Moreover, sealing member 502 is formed of a
material having a higher wear resistance than anodic oxidation
coating, and the clearance between the smaller-diameter portion
(sliding portion 512) of lock piston 51 and the inside periphery of
sealing member 502 is set smaller than the clearance between the
larger-diameter portion (flange 513) of lock piston 51 and the
inside periphery of slide hole 501. Namely, the frequency or degree
of contact between the smaller-diameter portion (sliding portion
512) of lock piston 51 and the inside periphery of sealing member
502 is relatively increased, in consideration that the wear
resistance of the inside periphery of sealing member 502 is higher
than the inside periphery of slide hole 501. This feature is
effective for suppressing wear of the portion of the inside
periphery of the cylinder in sliding contact with lock piston 51.
Although sealing member 502 is provided separately from vane rotor
4 in the present embodiment, sealing member 502 may be formed
integrally with vane rotor 4 into a stepped shape, and the entire
inside peripheral surface of slide hole 501 may be applied with
anodic oxidation treatment. This alternative construction also
serves to enhance the wear resistance, while defining the first and
second pressure-receiving chambers 55 and 59. However, the
construction according to the present embodiment that sealing
member 502 is formed separately and mounted in slide hole 501 is
advantageous in enhancing the wear resistance of the cylinder
against the sliding motion of lock piston 51, and simply defining
the first and second pressure-receiving chambers 55 and 59.
[0082] Lock piston 51 is formed of a material having a higher wear
resistance than anodic oxidation coating, specifically, formed of
an iron-based metal material. This feature serves to enhance the
hardness of lock piston 51, and suppress wear of lock piston 51
effectively. The construction that the slide hole 501 is formed
with an anodic oxidation coating film, and sealing member 502 is
formed of a material having a higher wear resistance than anodic
oxidation coating, is also effective for suppressing wear of lock
piston 51 that is in sliding contact with slide hole 501 and
sealing member 502. Sleeve 52 is formed of a material having a high
wear resistance, such as an iron-based metal material. This feature
is effective for enhancing the hardness of engaging recess 521 that
is the inclined surface in sliding contact with engaging portion
511, and suppressing wear of engaging recess 521. Although sleeve
52 may be formed integrally with rear plate 9, the feature
according to the present embodiment that the sleeve 52 is provided
separately from rear plate 9 makes it possible to adjust the shape,
material, etc., of engaging recess 521 so as to allow the lock
piston 51 to smoothly engage or disengage with engaging recess 521,
and serves to suppress wear and deformation of rear plate 9
resulting from engagement and disengagement of lock piston 51.
Namely, the feature according to the present embodiment is
advantageous in making it possible to use a material particularly
suited for high wear resistance, and enhancing the forming accuracy
of the inclined surface of engaging recess 521.
[0083] <Durability of Apparatus Enhanced by Features of Stopper
Mechanism> Contact between the first stopper portions of the
first stopper mechanism is frequently repeated, when vane rotor 4
is in the initial position where vane rotor 4. Moreover, this
contact is generally hard, because hydraulic control is at rest
when the internal combustion engine is being stopped. Accordingly,
the first stopper mechanism may deform due to frequency and
hardness of contact in the first stopper mechanism, so that the
limit of rotation of vane rotor 4, i.e. the initial position of
vane rotor 4 may change or deviate. In intake valve timing control
apparatus 1a and exhaust valve timing control apparatus 1b, the
contact area of the first stopper mechanism SS1 is set larger than
the contact area of the second stopper mechanism SS2 (SS1>SS2).
This prevents the first stopper mechanism from deforming or
deviating the position within which rotation of vane rotor 4 is
restricted. The first stopper mechanism is constituted by the
circumferentially-facing surface of first vane 41. Accordingly, the
root of first vane 41 has a longer circumferential length, which is
advantageous because first vane 41 has a high rigidity, and has a
strength enough to restrict and receive relative rotation of vane
rotor 4. On the other hand, radial projection 419 of the second
stopper mechanism is formed at the root of first vane 41, extending
outwardly in the radial direction from rotor 40. As compared to
cases where the second stopper mechanism is constituted by the tip
of first vane 41, the bending moment or moment arm about the root
of first vane 41 in the circumferential direction when the second
stopper mechanism functions to restrict rotation of vane rotor 4,
is smaller so that the root of first vane 41 is generally subject
to no excessive force. This is advantageous for enhancing the
durability of first vane 41. In this way, these features according
to the present embodiment serve to enhance the rigidity of the
first and second stopper mechanisms, suitably restrict the relative
rotation, and thereby enhance the durability of valve timing
control apparatus 1. Incidentally, one or more combinations of
contact portions of second and third vanes 42 and 43, and first,
second and third shoes 11, 12 and 13 may be modified to form first
and second stopper mechanisms. In exhaust valve timing control
apparatus 1b, the second stopper mechanism also serves to limit the
amount of displacement (amount of compression) of biasing member 6
(coil springs 610, 620 and 630) to a predetermined amount. This
prevents plastic deformation of biasing member 6 (coil springs 610,
620 and 630), and prevents the biasing force of biasing member 6
from changing in an irreversible form. Radial projection 429 of
second vane 42 and the tip of third shoe 13 serve as a backup
stopper mechanism instead of the second stopper mechanism, even
when errors occur during manufacturing and assembling operations,
or when the stopper portions of the second stopper mechanism are
worn. This improves the reliability and accuracy of intake valve
timing control apparatus 1a and exhaust valve timing control
apparatus 1b. Especially in exhaust valve timing control apparatus
1b, this is effective for securely preventing the biasing member 6
from plastically deforming. Coil springs 610 and 630 are arranged
outside of radial projections 419 and 429 of first and second vanes
41 and 42, respectively, so that radial projections 419 and 429,
which constitute the second stopper mechanism and backup stopper
mechanism respectively, guide the coil springs 610 and 630 of
biasing member 6. This ensures normal operations of biasing member
6 and exhaust valve timing control apparatus 1b.
[0084] <Sealing Performance Enhanced by Features of Forming>
In general, a device including a housing formed with a pulley to
which torque is transmitted through a timing belt that is formed of
rubber or synthetic resin and is wound around the pulley, is
subject to a problem that the timing belt may be degraded by
adhesion of working fluid exiting out of the housing. The housing
has to be suitably sealed to solve the problem. This is true for
valve timing control apparatus 1. The feature according to the
present embodiment that the housing body 10 is formed by extruding
an aluminum-based metal material, serves to prevent working fluid
from seeping and leaking through the inside of housing body 10 and
arriving at the outside periphery (pulley 100) of housing body 10,
as compared to cases where housing body 10 is formed by another
processing, for example, by sintering an aluminum-based metal
material. The feature that the sealing plates (cap 7, front plate
8, and rear plate 9) are formed by forging an iron-based metal
material, serves to prevent working fluid from seeping and leaking
through the inside of the sealing plates (cap 7, front plate 8, and
rear plate 9), as compared to cases where the sealing plates (cap
7, front plate 8, and rear plate 9) are formed by another
processing, for example, by sintering an iron-based metal
material.
[0085] <Sealing Performance Enhanced by Features of Sealing
Members> The feature that the sealing rings S1, S2, S3 and S4
are provided in housing HSG serves to prevent working fluid from
leaking through clearances, and thus ensure liquid-tightness of
housing HSG. Each sealing ring may be replaced with a sealing
compound. For example, sealing rings S2 may be replaced with an
adhesive that serves also as a sealing compound, which serves to
strengthen the fixing force of each bolt b1, b2 or b3. However, the
construction according to the present embodiment is advantageous in
simply implementing the sealing function. In the present
embodiment, with regard to sealing ring S1 between housing body 10
and rear plate 9, under the condition that the sealing ring S1 is
mounted in sealing ring groove 906 of rear plate 9, the inside
peripheral surface 103 of fitting recess 101 of housing body 10 is
pressed onto sealing ring S1, so that sealing ring S1 is
compressed. This construction provides a function of sealing, so as
to prevent working fluid from leaking through the boundary between
rear plate 9 and housing body 10, and thus seal the working fluid
chambers. With regard to sealing rings S2, under the condition that
sealing rings S2 are mounted in annular sealing ring grooves 907,
908 and 909 around female thread portions 901, 902 and 903, the
X-axis negative side end surface 102 of housing body 10 (first,
second and third shoes 11, 12 and 13) is pressed onto sealing rings
S2, so that sealing rings S2 are compressed. This configuration
provides a function of sealing, so as to prevent working fluid from
leaking through the boundary between rear plate 9 and housing body
10, and the bolt holes of female thread portions 901, 902 and 903,
and thus seal the working fluid chambers. With regard to sealing
ring S3 between housing body 10 and front plate 8, under the
condition that sealing ring S3 is mounted in annular sealing ring
groove 89 of front plate 8, the X-axis positive side end surface
105 of housing body 10 is pressed onto sealing ring S3, so that
sealing ring S3 is compressed. This construction provides a
function of sealing, so as to prevent working fluid from leaking
through the boundary between front plate 8 and housing body 10, and
thus seal the working fluid chambers. The feature that the sealing
ring S3 and annular sealing ring groove 89 have the form of a
three-leaved clover, passing inside of bolt holes 83, 84 and 85, so
that the bolt holes 83, 84 and 85 are hydraulically separated from
the inside of housing HSG, is effective for reducing the number of
parts, and improving the facility of assembling, because no
individual sealing members are required for bolt holes 83, 84 and
85. Incidentally, sealing ring S3 may be replaced with a plurality
of sealing rings, i.e. a sealing ring that seals the inside portion
of front plate 8 and passes outside of bolt holes 83, 84 and 85,
and sealing rings each of which surrounds the bolt hole 83, 84 or
85 for sealing. With regard to sealing ring S4, under the condition
that sealing ring S4 is mounted in annular sealing ring groove 821
of female thread portion 82 of front plate 8, the X-axis negative
side end surface of flange 72 of cap 7 is pressed onto sealing ring
S4, so that sealing ring S4 is compressed. This construction
provides a function of sealing, so as to prevent working fluid from
leaking through the boundary between cap 7 and front plate 8, and
thus sealing the back pressure relief section. Incidentally,
sealing ring grooves are optional, and the sealing rings may be
mounted for sealing with no annular sealing ring groove formed.
Housing body 10, front plate 8, and rear plate 9 are fixed together
with the plurality of bolts b1, b2 and b3 which extend in the axial
direction of housing HSG. Each bolt b1, b2 or b3 formed with the
male thread is screwed in the female thread formed in the inside
periphery of female thread portion 901, 902 or 903 of rear plate 9.
The axial force of each bolt b1, b2 or b3 presses the X-axis
negative side end surface (bottom surface 102) of housing body 10
(first, second and third shoes 11, 12 and 13) on sealing rings S2
around female thread portion 901, 902 or 903, thereby compresses
sealing rings S2 in the X-axis direction. Similarly, the axial
force of each bolt b1, b2 or b3 presses the X-axis positive side
end surface 105 of housing body 10 (first, second and third shoes
11, 12 and 13) on sealing ring S3 around bolt holes 83, 84 and 85,
thereby compresses sealing ring S3 in the X-axis direction. These
features further enhance the sealing of housing HSG. The reaction
force of sealing rings S2 and S3 serves to strengthen the fixation
of bolt b1, b2 and b3, and prevent bolts b1, b2 and b3 from being
released. Each female thread portion 901, 902 or 903 may be in the
form of a recess. Although rear plate 9 is formed with female
threads in the present embodiment, this construction may be
modified so that each bolt b1, b2 or b3 extends through and
projects from the rear plate 9, and the projected portion of bolt
b1, b2 or b3 is engaged with a nut. The female threads may be
formed in front plate 8 not in rear plate 9, wherein each bolt b1,
b2 or b3 is inserted from the X-axis negative side to fix the front
plate 8, rear plate 9, and housing body 10 together. The feature
that each sealing ring S1, S2, S3 or S4 is an O-ring having a
circular cross-section, makes it easy to mount each sealing ring
S1, S2, S3 or S4 in sealing ring groove 906, etc. When compressed
between two contact surfaces, each sealing ring S1, S2, S3 or S4 is
brought into intimate contact with the contact surfaces, thereby
enhancing the sealing performance. For sealing, it is sufficient
that the surfaces of housing body 10 and sealing plate 8 or 9
facing one another abut on the sealing rings, and it is optional
that the surfaces of housing body 10 and sealing plate 8 or 9 are
in direct contact with one another. Specifically, it is sufficient
that the X-axis negative side surface of front plate 8 (i.e. the
bottom of sealing ring groove 89) abuts on sealing ring S3, and the
X-axis positive side surface 105 of housing body 10 abuts on
sealing ring S3, and it is optional that the X-axis negative side
surface of front plate 8 and the X-axis positive side surface 105
of housing body 10 abut on one another. Similarly, it is sufficient
that the X-axis positive side surface of rear plate 9 (i.e. the
bottom of each annular sealing ring groove 907, 908 or 909) abuts
on sealing ring S2, and the X-axis negative side surface 102 of
housing body 10 abuts on sealing rings S2, and it is optional that
the X-axis positive side surface of rear plate 9 and the X-axis
negative side surface 102 of housing body 10 abut on one another.
Further, it is sufficient that the bottom of sealing ring groove
906 abuts on sealing ring S1, and the inside peripheral surface 103
of fitting recess 101 of housing body 10 abuts on sealing ring S1,
and it is optional that the bottom of sealing ring groove 906 and
the inside peripheral surface 103 of fitting recess 101 of housing
body 10 abut on one another.
[0086] <Sealing Performance Enhanced by Portion Applied with No
Anodic Oxidation Coating> If the surfaces 102, 103 and 105 of
housing body 10 on which sealing rings S1, S2 and S3 abut are
formed with an anodic oxidation coating film, the valve timing
control apparatus 1 may be subject to a problem that the sealing
rings S1, S2 and S3 are not completely in intimate contact with the
surfaces 102, 103 and 105, which adversely affects the sealing
performance of housing body 10 at the surfaces 102, 103 and 105.
This is because an anodic oxidation coating film is an oxidation
coating film, having a relatively high surface roughness. Namely,
that is because an anodic oxidation coating film is a porous
coating film provided with a lot of pores at the surface, unless
full pore-sealing treatment is applied after anodic oxidation
treatment. In contrast, in the present embodiment, the axial end
surfaces of housing body 10 to which the sealing plates 8 and 9 are
fixed, namely, the surfaces 102, 103 and 105 of housing body 10 to
which the sealing rings S1, S2 and S3 are mounted, are formed with
no anodic oxidation coating film. This serves to allow intimate
contact between sealing rings S1, S2 and S3 and surfaces 102, 103
and 105 with no clearance therebetween, and thereby enhance the
sealing performance of sealing rings S1, S2 and S3. The surfaces
102, 103 and 105 of housing body 10 are sealed by the sealing
plates 8 and 9, and in sliding contact with no other member.
Accordingly, it is unnecessary to enhance the wear resistance of
surfaces 102, 103 and 105. The feature that the surface 102, 103 or
105 is provided with no anodic oxidation coating film and with the
base layer of aluminum-based metal material exposed, is effective
for eliminating the necessity of further treatment or processing
for surfaces 102, 103 and 105, and thereby reducing the
manufacturing cost, while maintaining the sealing performance of
housing body 10. Specifically, the surface of housing body 10
abutting on sealing ring S3 is a cut surface (X-axis positive side
axial end surface 105) that is obtained by the cutting-off
operation, and the surfaces of housing body 10 abutting on sealing
rings S1 and S2 are surfaces (bottom surface 102 and inside
peripheral surface 103 of fitting recess 101 at the X-axis negative
side of housing body 10) that are obtained by the carving operation
of carving the axial end surface of housing body 10. Since the
cutting-off operation and the carving operation are performed after
the coating operation, the surfaces 102, 103 and 105 of housing
body 10 are formed with no anodic oxidation coating film, so that
the base layer is exposed on the surfaces 102, 103 and 105. The
surfaces 102, 103 and 105 of housing body 10 are thus adapted to be
in intimate contact with sealing rings S1, S2 and S3. The surfaces
102, 103 and 105 of housing body 10, on which the base layer is
exposed, may be formed with a coating film other than anodic
oxidation coating films, which coating film does not adversely
affect the sealing performance, although such construction
increases the manufacturing cost due to additional treatment. Even
in cases where the surfaces 102, 103 and 105 of housing body 10 to
which sealing rings S1, S2 and S3 are mounted are formed with an
anodic oxidation coating film, the sealing may be maintained by
applying pore-sealing treatment so as to seal the openings of the
pores, and thereby reduce the surface roughness. Such construction
is disadvantageous in that the additional treatment causes an
increase in the manufacturing cost. Moreover, if the pore-sealing
treatment is undesirably applied to other portions, the required
characteristics of the other portions may be adversely affected. In
contrast, the feature according to the present embodiment that at
least the open axial ends of housing body 10 are applied with no
pore-sealing treatment, is advantageous in reducing the
manufacturing cost, while maintaining the sealing performance.
[0087] It is sufficient that the open axial ends of housing body 10
abut on the sealing rings, and it is optional that the open axial
ends of housing body 10 directly abut on the sealing plates 8 and
9, as discussed above. However, the optional feature is
advantageous as follows. Each surface 102 or 105 of housing body 10
is formed with no anodic oxidation coating film, and thereby not
hardened, whereas each sealing plate 8 or 9 is formed of a harder
material (iron-based metal material) than housing body 10
(aluminum-based metal material). When the sealing plate 8 or 9 are
fixed to housing body 10, the intimateness of contact between
housing body 10 and sealing plate 8 or 9 can be enhanced by
screwing the bolts b1, b2 and b3 tightly so as to bring the housing
body 10 and sealing plate 8 or 9 into direct contact with one
another. Specifically, the axial end surfaces of the sealing plates
(the X-axis negative side surface of front plate 8, and the X-axis
positive side surface of rear plate 9) may be formed with slight
roughness (with fine projections and depressions) by the
manufacturing process, but the projections and depressions at the
relatively hard surface are pressed on the relatively soft surface
102 or 105 of housing body 10, so that the relatively soft surface
102 or 105 deforms slightly in conformance with the shape of the
projections and recesses. This enhances the intimateness of contact
between housing body 10 and sealing plate 8 or 9, and thereby
further enhances the sealing performance.
[0088] <Sealing Performance Enhanced by Sealing at Journal
Portion of Housing> The oil seal OS provided at the outside
periphery of cylindrical portion 91 of rear plate 9 of housing HSG
serves to seal the clearance between the cylinder head and the
outside periphery of the cylindrical portion 91. This serves to
prevent that working fluid leaking out to the cylinder head side
through the clearance CL shown in FIG. 3 between the inside
periphery of cylindrical portion 91 and the outside periphery of
camshaft 3a or 3b, or working fluid in the internal combustion
engine, leaks through the clearance at the outside periphery of
cylindrical portion 91 into contact with timing belt 1010 or other
equipment. The feature that the cylindrical portion 91 of rear
plate 9 is formed of an iron-based metal material and thereby has a
higher wear resistance, is effective for suppressing wear of the
outside peripheral surface of cylindrical portion 91 resulting from
sliding contact with oil seal OS, and thereby reliably sealing the
outside periphery of cylindrical portion 91.
[0089] <Sealing Performance Enhanced by Arrangement of Back
Pressure Relief Section> In general, in a valve timing control
apparatus in which an engaging member in a housing functions to
lock the valve timing at engine start, the engaging member can be
smoothly released from its engaged state by suitably lowering the
back pressure of the engaging member. If the back pressure is
lowered by relieving the back pressure directly to the outside of
the housing, then working fluid may get in touch with a timing belt
that drives the valve timing control apparatus. In order to solve
this problem, the back pressure relief section is provided, which
relieves the pressure in back pressure chamber 50 into the internal
space of the internal combustion engine, and keeps the pressure in
back pressure chamber 50 low, while maintaining the sealing
performance of housing HSG. The fluid passage for reliving the back
pressure of back pressure chamber 50 communicates with the inside
of the internal combustion engine, but has no intermediate point
that communicates directly with the outside of housing HSG. The
back pressure relief section serves to discharge working fluid of
back pressure chamber 50 to the internal space of the internal
combustion engine, so as to prevent the timing belt 1010 from being
degraded by oil, and thereby enhance the durability of timing belt
1010.
[0090] <Apparatus Made Compact in Radial Direction by Features
of Pulley> The outside periphery of housing body 10 is formed
integrally with pulley 100. This feature makes it possible to
reduce the diameter of valve timing control apparatus 1, as
compared to cases in which a pulley is provided separately from a
housing body. The construction that the pulley 100 is formed over
the entire axial length of the outside periphery of housing body
10, makes it possible to provide the teeth of pulley 100 with a
width enough to engage with timing belt 1010, even if the width of
timing belt 1010 is required to be above a predetermined lower
limit. Namely, even when the axial length of housing HSG is set as
small as the width of timing belt 1010 where rear plate 9 is
fixedly inserted in fitting recess 101 of housing body 10, it is
possible to provide the teeth of pulley 100 with a width enough to
engage with timing belt 1010 and transmit a torque to timing belt
1010
[0091] <Apparatus Made Compact in Axial Direction by Formation
of Fitting Recess in Housing Body> In valve timing control
apparatus 1, the axial ends of housing body 10 are closed and
sealed by front plate 8 and rear plate 9 respectively. The
construction that the rear plate 9 is fixedly inserted in fitting
recess 101 of housing body 10 which is formed at one axial end of
housing body 10, makes it possible to reduce the axial size of
valve timing control apparatus 1, as compared to cases where front
plate 8 and rear plate 9 are simply fixed to the axial end surfaces
104 and 105 of housing body 10 respectively. The construction that
the entire axial length of the outside periphery of rear plate 9 in
the X-axis direction, i.e. the entire axial length of plate body 90
in the X-axis direction, is fixedly inserted in fitting recess 101,
is further advantageous in minimizing the axial size of valve
timing control apparatus 1. Rear plate 9 is formed with engaging
recess 521 (or recess 900 for fixing the sleeve 52) which extends
in the X-axis direction, where engaging recess 521 engages with
lock piston 51 which is mounted to move in and out from vane rotor
4 in the X-axis direction. Accordingly, the axial length of rear
plate 9 is set larger than that of front plate 8. If the thicker
rear plate 9 is simply fixed to the axial end surface of housing
body 10, the axial length of the entire valve timing control
apparatus 1. According to the present embodiment, the construction
that the fitting recess 101 is formed in one axial end of housing
body 10, and rear plate 9 (not front plate 8) is fixedly inserted
in fitting recess 101, makes it possible to efficiently reduce the
axial size of valve timing control apparatus 1. This enhances the
flexibility of layout of an engine room to which valve timing
control apparatus 1 is mounted. Front plate 8, rear plate 9 and
housing body 10 are fixed by the plurality of bolts b1, b2 and b3.
The female thread hole into which the male thread of each of bolts
b1, b2 and b3 is screwed is required to have a some length. The
construction according to the present embodiment that all of
engaging recess 521 and the female thread holes are formed in rear
plate 9, is further advantageous in minimizing the axial size of
valve timing control apparatus 1. Front plate 8 may be formed
thinner than rear plate 9, because front plate 8 is formed with no
female thread hole, etc. Accordingly, even when front plate 8 is
simply fixed to the axial end surface 105 of housing body 10, the
axial length of valve timing control apparatus 1 is little
increased. On the other hand, the construction that the female
thread holes are formed in rear plate 9 which is formed thicker
because rear plate 9 is formed with engaging recess 521, and the
thicker rear plate 9 is fixedly inserted in fitting recess 101, is
advantageous in minimizing the axial size of valve timing control
apparatus 1. Engaging recess 521 may be formed in front plate 8,
not in rear plate 9. Moreover, housing body 10 may be formed with
another fitting recess to which front plate 8 is fixedly inserted.
However, in the present embodiment, front plate 8 is simply fixed
to the axial side surface 105 of housing body 10, in order to
provide lock piston 51 with a required range of movement in the
axial direction or provide slide hole 501 of vane rotor 4 with a
required length in the X-axis direction.
[0092] <Apparatus Made Compact in Radial Direction by Features
of Sealing Structure> It is generally difficult to provide a
space for a sealing member, in cases where the boundary between the
axial end surfaces of housing body 10 and rear plate 9 is sealed,
i.e. the boundary between the bottom surface 102 of fitting recess
101 and the X-axis negative side surface of rear plate 9 is sealed.
Specifically, as shown in FIG. 6C, the radial length of bottom
surface 102 of fitting recess 101 except the portions where first,
second and third shoes 11, 12 and 13 are formed, (R-Ri), is short
to form a sealing groove where a sealing member is mounted.
Accordingly, when the boundary (bottom surface 102 of fitting
recess 101) where the axial end surfaces are in contact with each
other is provided with an adequate space where a sealing member is
mounted or a sealing groove is formed, the diameter of housing body
10 in the radial direction is increased. On the other hand, the
length of fitting recess 101 in the X-axis direction and the length
of rear plate 9 in the X-axis direction are relatively large so
that a sealing member can be mounted or a sealing groove can be
formed. Accordingly, the problem described above can be solved by
providing a sealing member between the inside periphery of fitting
recess 101 and the outside periphery of rear plate 9. However, the
radial length (Ro-R) of housing body 10 is small to form a sealing
groove in the inside peripheral surface of housing body 10 (inside
peripheral surface 103 of fitting recess 101). Accordingly, if the
sealing groove is formed in the inside peripheral surface of
housing body 10 (inside peripheral surface 103 of fitting recess
101), the radial size of housing body 10 must be increased so as to
increase the radial length (Ro-R). In order to solve this problem,
the outside periphery of rear plate 9 is formed with sealing ring
groove 906 to which sealing ring S1 is mounted, so as to seal the
boundary between fitting recess 101 and rear plate 9. This sealing
structure makes it possible to reduce the radial length (Ro-R),
i.e. the radial thickness of housing body 10, and thereby minimize
increase in the radial size of valve timing control apparatus 1,
while minimizing the axial size of valve timing control apparatus 1
by the provision of fitting recess 101. On the other hand, the
X-axis negative side surfaces of first, second and third shoes 11,
12 and 13 have adequate spaces where sealing members are mounted
around bolt holes 110, 120 and 130. Accordingly, rear plate 9 is
formed with annular sealing ring grooves 907, 908 and 909 around
female thread portions 901, 902 and 903, where annular sealing ring
grooves 907, 908 and 909 faces bolt holes 110, 120 and 130, and
sealing rings S2 are mounted in annular sealing ring grooves 907,
908 and 909. It is possible as an alternative to prevent working
fluid from leaking through the bolt holes of female thread portions
901, 902 and 903 by a construction that the bolt holes of female
thread portions 901, 902 and 903 are formed with bottoms, without
passing through the rear plate 9. In this case, however, the
provision of the bottoms may cause an increase in the axial length
of rear plate 9, because the lengths of female thread portions 901,
902 and 903 are increased to maintain the axial lengths of the
female threads for bolts b1, b2 and b3. In contrast, according to
the present embodiment, the construction that the bolt holes of
female thread portions 901, 902 and 903 are formed to extend
through the rear plate 9 with no bottoms, is effective for reducing
the axial length of rear plate 9. Incidentally, the construction
that the recess 900 of rear plate 9 and pin hole 904 have bottoms,
causes no increase in the axial length of rear plate 9, because the
length of recess 900 in the X-axis direction is only required to
allow engagement of lock piston 51, and the length of pin hole 904
in the X-axis direction is only required to allow fixation of the
positioning pin 905. This feature is effective for preventing
working fluid from leaking from housing HSG to outside without
sealing for recess 900 and pin hole 904. On the other hand, the
boundary between front plate 8 and housing body 10 includes a space
having an adequate radial size where a sealing member can be
mounted, because the X-axis positive side surface of housing body
10 is formed with no fitting recess. Specifically, as shown in FIG.
6A, the radial length Ro-Ri of housing body 10 is large enough to
mount a sealing member or form a sealing groove. Accordingly,
sealing ring S3 is arranged between the contact axial end surfaces
of housing body 10 and front plate 8, i.e. between the X-axis
negative side surface 105 of housing body 10 and the X-axis
positive side surface of front plate 8. For mounting the sealing
ring S3, front plate 8 is formed with annular sealing ring groove
89. The sealing groove may be formed in housing body 10, not in
front plate 8. However, housing body 10 has an inside space for
accommodating the phase change mechanism, and thereby has only a
small space (area or thickness) at the axial end which can be
formed with a sealing groove, without adversely affecting the
strength of housing body 10. On the other hand, sealing plate 8 or
9 is subject to no such requirement, so that it is easy to form the
sealing plate 8 or 9 with a sealing groove. The feature according
to the present embodiment that the annular sealing ring grooves
907, 908, 909 and 89 are formed in sealing plates 8 and 9, serves
to reduce the manufacturing cost of valve timing control apparatus
1. If sealing plates 8 and 9 are formed integrally with sealing
grooves by casting, the manufacturing cost is further lowered.
[0093] <Apparatus Made Compact by Arrangement of Back Pressure
Relief Section> Back pressure chamber 50 is formed at the X-axis
positive side of slide hole 501 of vane rotor 4, wherein the tip
(or engaging portion 511) of lock piston 51 is arranged to move and
project in the X-axis negative direction from vane rotor 4. On the
other hand, the internal combustion engine is located on the X-axis
negative side of vane rotor 4 and rear plate 9. Accordingly, in
order to relieve the internal pressure (oil or air) of back
pressure chamber 50 while ensuring the sealing performance of
housing HSG, the back pressure relief section needs to include a
fluid passage (back pressure hole 407) that passes through the vane
rotor 4 in housing HSG from the X-axis positive side axial end to
the X-axis negative side axial end. In valve timing control
apparatus 1, the fixing portions (bolt holes 403, 404 and 405) are
formed in rotor 40 and arranged and spaced from one another in the
circumferential direction, which fixing portions serve to fix the
vane rotor 4 to camshaft 3a or 3b. Accordingly, the fluid passage
(back pressure hole 407) of the back pressure relief section needs
to be arranged with no interference with the fixing portions (bolt
holes 403, 404 and 405). Moreover, camshaft bolts 33, 34 and 35,
which are inserted in bolt holes 403, 404 and 405, respectively,
have heads 331, 341 and 351 (including the washers 332, 342 and
352) located at the X-axis positive side surface of vane rotor 4.
Accordingly, in cases where the fluid passage (back pressure hole
407) is formed to have an opening at the X-axis positive side
surface of vane rotor 4, the fluid passage of the back pressure
relief section needs to be arranged with no interference with the
heads 331, 341 and 351. In order to satisfy these requirements, it
may be conceived that the back pressure hole 407 is located in an
annular outside space surrounding the fixing portions (i.e. in a
space farther from the axis of rotation O than the farthest point
of the inside periphery of each bolt hole 403, 404 or 405, or in a
space outside a circle containing and circumscribing the bolt holes
403, 404 and 405 as viewed in the X-axis direction), specifically,
in an annular outside space surrounding the heads 331, 341 and 351
of camshaft bolts 33, 34 and 35 (i.e. in a space outside a circle
circumscribing the heads 331, 341 and 351). This construction tends
to result in an increase in the radial size of rotor 40. In
contrast, in the present embodiment, back pressure hole 407 is
located radially inside of or closer to the axis of rotation O than
the fixing portions (bolt holes 403, 404 and 405), or in the space
inside the circle circumscribing the bolt holes 403, 404 and 405,
and specifically at the axis of rotation of rotor 40 (at the axis
of rotation O). Specifically, since the fixing portions are
implemented by bolt holes 403, 404 and 405, camshaft bolts 33, 34
and 35 have heads 331, 341 and 351, and back pressure hole 407 has
an opening at the X-axis positive side of rotor 40 in the present
embodiment, back pressure hole 407 needs to be located with no
interference with heads 331, 341 and 351. The construction
according to the present embodiment makes it possible to make the
valve timing control apparatus 1 compact, because no space for back
pressure hole 407 is needed at the outside space of rotor 40. In
other words, the construction according to the present embodiment
that the plurality of bolt holes 403, 404 and 405 are formed for
insertion of camshaft bolts 33, 34 and 35, provides rotor 40 and
camshaft 3a or 3b with a space for back pressure hole 407 at the
inside space (including the axis of rotation O) surrounded by the
bolt holes 403, 404 and 405, in contrast to cases where a single
bolt hole is formed at the axis of rotation. Although back pressure
hole 407 is formed in rotor 40 so as to extend through the rotor 40
in the X-axis direction, and located to face the first back
pressure passage 31 of camshaft 3a or 3b in the X-axis direction in
the present embodiment, this construction may be modified so that
the back pressure hole 407 is inclined with respect to the X-axis,
and the opening of back pressure hole 407 at the X-axis negative
side of rotor 40 faces the first back pressure passage 31 of
camshaft 3a or 3b in the X-axis direction. Although the second back
pressure passage communicating the back pressure chamber 50 and
back pressure hole 407 with one another is composed of radial
groove 58 and circular recess 406 in the present embodiment, this
construction may be modified so that the second back pressure
passage is constituted by a hole extending in vane rotor 4 with
inclination. In the modification, back pressure hole 407 may be
constructed to have no opening facing the circular recess 406 at
the X-axis positive side of rotor 40. The construction according to
the present embodiment may be modified so that the X-axis negative
side opening of back pressure hole 407 is located distant from the
first back pressure passage 31, and one of the X-axis negative side
end surface of rotor 40 and the X-axis positive side end surface of
camshaft 3a or 3b is formed with a portion such as a groove or
recess for communicating the X-axis negative side opening of back
pressure hole 407 and the first back pressure passage 31 with one
another. This modification makes it possible to locate the back
pressure hole 407 independently of the position of first back
pressure passage 31, and thereby enhances the flexibility of
design. The construction according to the present embodiment that
the back pressure hole 407 is formed to extend in the X-axis
direction, is advantageous because it is unnecessary to intricately
form an inclined hole constituting the back pressure hole 407. The
construction that the X-axis negative side opening of back pressure
hole 407 is located to face the first back pressure passage 31, is
advantageous in the facility of forming and the manufacturing cost,
because it is unnecessary to form a groove or recess connecting the
back pressure hole 407 and first back pressure passage 31 to one
another. However, the construction that the X-axis negative side
opening of back pressure hole 407 is located to face the first back
pressure passage 31, is subject to a requirement that back pressure
hole 407 must be located in consideration of a positional
relationship with the fluid passages formed in camshaft 3a or 3b
other than first back pressure passage 31. Namely, the first back
pressure passage 31, which is formed in camshaft 3a or 3b to extend
in the X-axis direction, is required not to overlap with first
fluid passages 202 and 212, and second fluid passages 201, 203, 211
and 213 (see FIG. 3) as viewed in the X-axis direction.
Accordingly, the X-axis negative side opening of back pressure hole
407 facing the first back pressure passage 31 in the X-axis
direction is also required to be located to satisfy the same
requirement. For example, if the arrangement that the X-axis
negative side opening of back pressure hole 407 is located in the
inside space surrounded by bolt holes 403, 404 and 405, is
implemented by a construction that that the X-axis negative side
opening of back pressure hole 407 is located between bolt holes 404
and 405, or between bolt holes 405 and 403, then it is possible
that the first back pressure passage 31 facing the X-axis negative
side opening of back pressure hole 407 interferes with first fluid
passages 202 and 212, and second fluid passages 201, 203, 211 and
213 in camshaft 3a or 3b. In this viewpoint, the construction that
the back pressure hole 407 is located between bolt holes 403 and
404 where first fluid passages 202 and 212, and second fluid
passages 201, 203, 211 and 213 are not located, is advantageous. In
the present embodiment, first fluid passages 202 and 212 are the
closest to the axis of rotation O among all the fluid passages
formed in camshaft 3a or 3b, wherein the central axes of first
fluid passages 202 and 212, and the central axes of bolt holes 403,
404 and 405 are arranged substantially on the same circle having a
center at the axis of rotation O. Accordingly, the construction
that the back pressure hole 407 is located in the space that is
inside the above circle, and excludes the space of first fluid
passages 202 and 212, and bolt holes 403, 404 and 405, makes it
possible to avoid interference between back pressure hole 407 and
the fluid passages of camshaft 3a or 3b. Specifically, if the
X-axis negative side opening of back pressure hole 407 is located
radially inside of or closer to the axis of rotation O than first
fluid passages 202 and 212, or in the space inside the circle
containing and circumscribing the first fluid passages 202 and 212
about the axis of rotation O as viewed in the X-axis direction,
then it is unnecessary to adjust the arrangement of fluid passages
202, etc. of camshaft 3a or 3b, wherein the strength of fixation is
ensured by the plurality of fixing portions, while expansion of the
radial size of rotor 40 is suppressed. In other words, in cases
where three or more fixing portions (bolt holes) are arranged and
spaced from one another in the circumferential direction so that
three or more intermediate spaces are defined between the fixing
portions as in the present embodiment, a pair of advance-side and
retard-side fluid passages formed in camshaft 3a or 3b are located
in two of the intermediate spaces so that one intermediate space
remains in which no fluid passage is formed. The remaining
intermediate space is available for provision of back pressure hole
407 (and first back pressure passage 31). For example, back
pressure hole 407 (and first back pressure passage 31) may be
located between bolt holes 403 and 404 in the circumferential
direction, which is advantageous in reducing the distance between
back pressure hole 407 and back pressure chamber 50. For example,
circular recess 406 may be omitted, wherein radial groove 58 is
extended inwardly in the radial direction and connected to both of
back pressure hole 407 and back pressure chamber 50. More
specifically, in the present embodiment, back pressure hole 407 is
located at the axis of rotation of rotor 40. This feature serves to
enhance the balance of vane rotor 4 around the axis of rotation O.
This feature further makes it possible to ensure the radial
thickness of rotor 40, and thereby enhance the strength of rotor 40
formed with bolt holes 403, 404 and 405, because the distance
between back pressure hole 407 and the outside periphery of rotor
40 is constant as followed along the outside periphery of rotor 40.
The feature still further makes it possible to easily arrange the
bolt holes 403, 404 and 405 evenly spaced in the circumferential
direction around the axis of rotation, and thereby further enhance
the balance of vane rotor 4 around the axis of rotation.
[0094] It is advantageous that the diameter of back pressure hole
407 is set as small as possible, because the small diameter of back
pressure hole 407 makes it possible to enhance the flexibility of
layout of back pressure hole 407, and make rotor 40 compact.
However, if the size of back pressure hole 407 in the X-axis
direction in rotor 40 is large, the facility of forming is lowed
because it is generally difficult to form a narrow long hole. In
the present embodiment, rotor 40 is formed with circular recess 406
and camshaft insertion hole 402 having a bottom, wherein back
pressure hole 407 extends through the rotor 40, and has an opening
at the bottom of each of circular recess 406 and camshaft insertion
hole 402. Namely, the length of back pressure hole 407 in the
X-axis direction is reduced by the depth of camshaft insertion hole
402 and the depth of circular recess 406, which makes it easy to
form the rotor 40 with back pressure hole 407. In this way, the
construction according to the present embodiment is advantageous in
enhancing the facility of forming of back pressure hole 407, and
makes rotor 40 compact by forming the back pressure hole 407 with a
relatively small diameter (smaller than the diameter of first back
pressure passage 31 of camshaft 3a or 3b).
[0095] The feature that the first back pressure passage 31
communicating with the oil-lubricated space of the internal
combustion engine is formed in camshaft 3a or 3b, makes it possible
to make valve timing control apparatus 1 compact, as compared to
cases where a back pressure passage is provided separately and
arranged outside (for example, at the outside periphery) of
camshaft 3a or 3b. This feature serves to eliminate the necessity
of increasing the diameter of the portion of valve timing control
apparatus 1 that is connected to the internal combustion engine,
i.e. the diameter of the cylindrical portion 91 provided with oil
seal OS that is disposed between cylindrical portion 91 and the
cylinder head. Moreover, it is possible to avoid interference
between first back pressure passage 31 and groove 204 or 214.
Specifically, first back pressure passage 31 is formed at the axis
of rotation (axis of rotation O) of camshaft 3a or 3b so to face
the X-axis negative side opening of back pressure hole 407. This
feature serves to maintain the balance of camshaft 3a or 3b about
the axis of rotation, and makes it possible to easily connect the
first back pressure passage 31 and the fluid passages that are
formed in camshaft 3a or 3b for lubrication, because the fluid
passages are located at the axis of rotation O in many cases.
Moreover, the location of first back pressure passage 31 according
to the present embodiment is advantageous in the strength of
camshaft 3a or 3b, and makes it easy to form the first back
pressure passage 31, even if the length of first back pressure
passage 31 is relatively large. This feature enhances the
flexibility of layout of first fluid passages 202, etc. in camshaft
3a or 3b. Namely, since there are remaining a lot of even spaces
around first back pressure passage 31 in camshaft 3a or 3b, the
first fluid passage 202, etc. can be located in any space of the
remaining spaces. Incidentally, in contrast to rotor 40 that is
subject to demand for compactness, camshaft 3a or 3b is subject to
no such demand, so that the diameter of first back pressure passage
31 may be larger than that of back pressure hole 407, which is
advantageous in that first back pressure passage 31 can be more
easily formed than back pressure hole 407.
[0096] With regard to the back pressure relief section, the second
back pressure relief passage is formed in vane rotor 4, so that
valve timing control apparatus 1 can be made compact. Specifically,
radial groove 58 and circular recess 406 constituting the second
back pressure relief passage are formed at the X-axis positive side
axial end surface of vane rotor 4. On the other hand, front plate 8
is formed with no recess nor groove constituting the second back
pressure relief passage. Accordingly, the axial size of valve
timing control apparatus 1 can be reduced, because it is
unnecessary to increase the thickness of housing HSG for formation
of such a recess or groove. On the other hand, the size of vane 41,
42 or 43 in the X-axis direction is unchanged through formation of
the second back pressure relief passage. This serves to maintain
the pressure-receiving area of vane rotor 4 against working fluid,
and thereby maintain the ability of operation of vane rotor 4.
Circular recess 406 is formed with bolt holes 403, 404 and 405 in
addition to back pressure hole 407. In other words, circular recess
406 serves to provide a space accommodating the heads 331, 341 and
351, and constitute the back pressure relief section. The
construction that the heads 331, 341 and 351 are accommodated in
circular recess 406 is advantageous because the heads 331, 341 and
351 do not project excessively from the axial end surface of vane
rotor 4 in the X-axis positive direction toward the front plate 8.
Cap 7 is formed with recess 73 at the surface facing the circular
recess 406, wherein the recess 73 accommodates the heads 331, 341
and 351 that project from the axial end surface of vane rotor 4.
Namely, as shown in FIG. 3, part of each head 331, 341 or 351
extends into recess 73. This feature makes it possible to reduce
the axial size of valve timing control apparatus 1. Circular recess
406 may be replaced by forming the rotor 40 with a plurality of
recesses each of which accommodates a corresponding one of heads
331, 341 and 351. In other words, circular recess 406 may be
modified to have a non-circular shape. However, circular recess 406
is advantageous in the facility of forming, and in reducing the
inertial mass of vane rotor 4, because a relatively large portion
is removed to form the circular recess 406. Circular recess 406 may
be omitted, wherein the back pressure relief section is
implemented, for example, by a construction that the radial groove
58 is extended toward the axis of rotation O, and connected to back
pressure hole 407.
[0097] <Guiding for Timing Belt> A pulley that includes
projections and depressions extending in the axial direction can be
subject to a problem that a timing belt tends to move in the axial
direction with respect to the pulley. In intake valve timing
control apparatus 1a, the front plate 8, which is provided at the
X-axis positive side of housing HSG, serves as a belt guide to
restrict movement of timing belt 1010 in the X-axis direction.
Specifically, the construction that the outside periphery 80 of
front plate 8 projects outwardly in radial directions with respect
to the bottom of each depression of pulley 100, and has an outside
edge that is located outside of the roots of teeth of pulley 100,
serves to prevent the timing belt 1010 from moving in the X-axis
positive direction, wherein the movement of timing belt 1010 is
obstructed by the outside periphery 80 of front plate 8. The
outside edge of the outside periphery 80 of front plate 8 is
located radially outside of the outside edge of timing belt 1010
putted on pulley 100, so that front plate 8 serves more effectively
as a belt guide to restrict the movement or deviation of timing
belt 1010. This feature is optional, because it is sufficient that
the construction that the outside periphery 80 of front plate 8
projects outwardly in radial directions with respect to the bottom
of each depression of pulley 100. It is sufficient that the outside
periphery 80 of front plate 8 includes at least a portion
projecting outwardly in radial directions with respect to the
bottom of a depression of pulley 100, where the portion is within a
range where timing belt 1010 and pulley 100 are in contact with one
another (in an angular range of about 90 degrees in intake valve
timing control apparatus 1a in FIG. 1). It is optional that the
entire outside periphery 80 of front plate 8 projects outwardly in
radial directions with respect to the bottom of each depression of
pulley 100. The restriction of movement of timing belt 1010 in the
X-axis positive direction results also in restricting the movement
of timing belt 1010 in the X-axis negative direction, and
preventing the timing belt 1010 from dropping from pulley 100.
Namely, it is sufficient that the belt guide is provided at at
least one axial end of pulley 100, and it is optional that the belt
guide is provided at another axial end of pulley 100. Although
exhaust valve timing control apparatus 1b is provided with no belt
guide, the movement of timing belt 1010 can be restricted by the
belt guide of intake valve timing control apparatus 1a, wherein
timing belt 1010 is putted on both of intake valve timing control
apparatus 1a and exhaust valve timing control apparatus 1b.
[0098] <Mountability Enhanced> In recent years, motor
vehicles are subject to increasing demand for compactness in size,
while internal combustion engines are provided with an increasing
number of auxiliary devices. For compactness, an engine and
auxiliary devices are arranged efficiently in an engine room,
wherein the remaining space is minimized. Accordingly, it is
desirable to make a valve timing control apparatus compact by
designing dimensions in millimeter so that the valve timing control
apparatus can be mounted efficiently in an engine room. For
example, if a valve timing control apparatus is arranged close to a
side wall of an engine, and is provided with a belt guide that can
interfere with the side wall, it is desirable to enhance the
mountability of the valve timing control apparatus. In order to
solve this problem, in the present embodiment, the belt guide is
provided in intake valve timing control apparatus 1a which is
farther from the engine room side wall W than exhaust valve timing
control apparatus 1b, and is attached to intake camshaft 3a which
is farther from the engine room side wall W than exhaust camshaft
3b. In other words, no belt guide is provided in exhaust valve
timing control apparatus 1b which is closer to the engine room side
wall W than intake valve timing control apparatus 1a, and is
attached to exhaust camshaft 3b which is closer to the engine room
side wall W than intake camshaft 3a. This feature serves to avoid
interference with the engine room side wall W, and thereby enhance
the mountability of valve timing control apparatus 1. In the
present embodiment, where the engine room side wall W includes the
projection W1, the exhaust valve timing control apparatus 1b, which
is disposed outside in the width direction of the cylinder block,
tends to be close to the projection W1 in the X-axis direction as
shown in FIG. 15, or in the direction perpendicular to the X-axis
direction as shown in FIG. 1. Particularly, the ends of exhaust
valve timing control apparatus 1b in the X-axis direction tend to
interfere with the projection W1. This problem is solved by the
construction according to the present embodiment that each
depression of pulley 100 of exhaust valve timing control apparatus
1b is opened at both ends in the X-axis direction. This
construction serves to reduce the possibility of interference
between the outside portion (specifically, the ends in the X-axis
direction) of exhaust valve timing control apparatus 1b and the
projection W1 of engine room side wall W, however the projection W1
is shaped. In contrast to the case of intake valve timing control
apparatus 1a, the construction that the front plate 8 of exhaust
valve timing control apparatus 1b has no portion or no belt guide
that projects outwardly in a radial direction with respect to the
bottom of a depression of pulley 100, and each depression of pulley
100 is fully opened at the X-axis positive side end, serves to
avoid interference with the projection W1. Each depression of
pulley 100 of exhaust valve timing control apparatus 1b is fully
opened also at the X-axis negative side end, which serves to avoid
interference with the projection W1. These features serve to
enhance the flexibility of layout of the engine room in which valve
timing control apparatus 1 is mounted. According to the present
embodiment, the mountability of exhaust valve timing control
apparatus 1b is enhanced, especially for vehicles in which severe
dimensional requirements are present about the X-axis positive side
of exhaust valve timing control apparatus 1b (the side farther from
the cylinder block, or the camshaft tip side). This is because the
movement of timing belt 1010 in the X-axis positive direction is
restricted more effectively than in the X-axis negative direction,
where intake valve timing control apparatus 1a is provided with the
belt guide closer to front plate 8 at the X-axis positive side. If
intake valve timing control apparatus 1a is provided with the belt
guide closer to rear plate 9 at the X-axis negative side, then the
mountability of exhaust valve timing control apparatus 1b is
enhanced especially for vehicles in which severe dimensional
requirements are present about the X-axis negative side of exhaust
valve timing control apparatus 1b (the side closer to the cylinder
block, or the camshaft root side). Incidentally, even if each
depression of pulley 100 is not fully but partly opened at the
X-axis positive side end, the advantageous effect described above
can be achieved to some extent, although it is smaller.
Specifically, even in cases where the diameter of front plate 8 of
exhaust valve timing control apparatus 1b is larger than in the
present embodiment, so as to form a belt guide, the interference
between the projection W1 and the belt guide can be avoided to some
extent, if the maximum diameter of the belt guide is smaller than
the diameter of tooth top circle of pulley 100. Moreover, even in
cases where the diameter of front plate 8 of exhaust valve timing
control apparatus 1b is larger than in the present embodiment, so
as to form a belt guide for completely closing the X-axis positive
side of each depression of pulley 100, the interference between the
projection W1 and the belt guide can be avoided to some extent, if
the belt guide does not project outwardly with respect to the
outside surface of timing belt 1010 putted on pulley 100, although
the effect is smaller. This is because the diameter of this exhaust
valve timing control apparatus 1b is still smaller than that of
intake valve timing control apparatus 1a, so as to make it possible
to reduce the width of the unit of the internal combustion engine,
intake valve timing control apparatus 1a and exhaust valve timing
control apparatus 1b are mounted, and thereby enhance the
flexibility of layout in the engine room, as compared to cases
where exhaust valve timing control apparatus 1b is provided with a
belt guide that is identical to that of intake valve timing control
apparatus 1a, i.e. a belt guide projecting outwardly with respect
to timing belt 1010.
[0099] The construction according to the present embodiment that
the intake valve timing control apparatus 1a farther from the
engine room side wall is provided with the belt guide is adapted to
a V-type DOHC engine in which a pair of cylinder banks are arranged
in a V-shape spreading from the crankshaft, and each cylinder bank
is provided with an intake camshaft and an exhaust camshaft,
wherein intake valve timing control apparatus 1a is attached to the
intake camshaft, and exhaust valve timing control apparatus 1b is
attached to the exhaust camshaft. However, this construction may be
adapted to another type engine, such as a straight-type engine,
thus producing similar advantageous effects. As in the present
embodiment, a general V-type engine is subject to more severe
requirements than other type engines, because auxiliary devices
mounted to the sides of the V-type engine project toward an engine
room side wall, and the size of the V-type engine itself tends to
increase in recent years. The present embodiment is adapted to such
a V-type engine, in which intake valve timing control apparatus 1a
farther from the engine room side wall W is provided with a belt
guide. This feature is effective for enhancing the mountability of
the valve timing control apparatus, especially for V-type engines
that are subject to more severe requirements. Specifically, in each
cylinder bank, only intake valve timing control apparatus 1a, which
is attached to one of intake camshaft 3a and exhaust camshaft 3b
closer to the other cylinder bank, i.e. attached to intake camshaft
3a, is provided with a belt guide, wherein intake camshaft 3a
closer to the other cylinder bank is inside of exhaust camshaft 3b
in the width direction of the cylinder block, and farther from the
engine room side wall W. In other words, exhaust valve timing
control apparatus 1b, which is attached to exhaust camshaft 3b that
is outside of intake camshaft 3a in the width direction of the
cylinder block, is provided with no belt guide, so that each
depression of pulley 100 is opened at both longitudinal ends. This
construction is applied to each cylinder bank in the present
embodiment, but may be applied only one cylinder bank. Although the
single timing belt 1010 is wound around intake valve timing control
apparatuses 1a and exhaust valve timing control apparatuses 1b at
both cylinder banks so that the timing belt 1010 drives both of
intake camshaft 3a and exhaust camshaft 3b in the present
embodiment, this construction may be modified so that two timing
belts are provided each of which is driven by the crankshaft and
wound around intake valve timing control apparatus 1a and exhaust
valve timing control apparatus 1b of a corresponding one of the
cylinder banks, and each of which drives intake camshaft 3a and
exhaust camshaft 3b of the corresponding cylinder bank. In cases
where a V-type engine is mounted in an engine room so that
camshafts extend in a direction that crosses a vehicle longitudinal
direction, for example, the camshafts extend in a direction
perpendicular to the vehicle longitudinal direction as in the
present embodiment, exhaust valve timing control apparatus 1b,
which is provided outside in the width direction of the cylinder
block, projects toward a front or rear side wall of the engine
room. This construction is subject to severe requirements for
dimensional management. In the present embodiment, of intake valve
timing control apparatus 1a and exhaust valve timing control
apparatus 1b attached to the V-type engine, only intake valve
timing control apparatus 1a is provided with a belt guide, which
serves to solve the disadvantage in the mountability. Incidentally,
the construction according to the present embodiment may be adapted
to an engine of an arbitrary type in which a camshaft extends in a
vehicle longitudinal direction, or extends in a diagonal direction
with respect to the vehicle longitudinal direction.
[0100] <Manufacturing Cost Reduced by Mirror Image
Arrangement> Intake valve timing control apparatus 1a and
exhaust valve timing control apparatus 1b are constituted by the
common third workpiece P3 for housing body 10, and the common
second workpiece Q2 for vane rotor 4. Housing body 10 and vane
rotor 4 of intake valve timing control apparatus 1a, and housing
body 10 and vane rotor 4 of exhaust valve timing control apparatus
1b, are formed as mirror images of each other, by application of
carving to respective ones of the opposite surfaces (side A, or
side B) of the common extrusions (P3, Q2). This feature serves to
simplify the process of manufacturing, and thereby reduce the
manufacturing cost. Moreover, vane rotor 4 and housing body 10 of
exhaust valve timing control apparatus 1b are transformed into
mirror images, and the stoppers are arranged in mirror positions,
to constitute the intake valve timing control apparatus 1a. This
feature allows the first stopper mechanism of each of intake valve
timing control apparatus 1a and exhaust valve timing control
apparatus 1b functions at the initial position, where the first
stopper mechanism has a larger contact area, as shown in FIGS. 4
and 16, and thereby prevents the stopper mechanisms from deforming
and changing the rotation limit position.
[0101] <Manufacturing Cost Reduced by Extrusion Forming> The
components (housing HSG, vane rotor 4) of valve timing control
apparatus 1 may be formed by an operation other than extrusion,
such as die-casting. The formation by extrusion according to the
present embodiment makes mass production easy. In the case of
housing body 10, a plurality of base workpieces (third workpieces
P3) are formed simultaneously by obtaining a long continuous member
(first workpiece P1, second workpiece P2), and dividing it. In this
way, many base workpieces (third workpieces P3) are obtained by a
few steps, and commonly used to construct the intake valve timing
control apparatus 1a and exhaust valve timing control apparatus 1b.
This is effective for further simplifying the process of
manufacturing, and thereby reducing the manufacturing cost. The
feature according to the present embodiment that the pulley 100 of
housing body 10 is constituted by a plurality of projections which
are arranged in the circumferential direction, and extend in the
axial direction, makes it possible to form the pulleys 100 of a
plurality of housing bodies 10 simultaneously by the extrusion
operation in the form of first workpiece P1, where it is
unnecessary to form the pulley 100 of each housing body 10 one by
one. This feature makes it possible to reduce the workload, and
make the forming easy, and reduce the cost of forming. For example,
if die-casting such as high-pressure die-casting is used for
forming the housing body 10, it is impossible to eliminate a
tapered shape which is provided so that a formed material can be
drawn from a mold. If the outside periphery of housing body 10 has
a tapered shape, when housing body 10 is formed integrally with
pulley 100, it is difficult to form the projections or teeth of
pulley 100 with high accuracy. On the other hand, according to the
present embodiment, housing body 10 is formed by extrusion, and
formed with no tapered shape, so that it is possible to form the
pulley 100, etc. with high accuracy. In the case of vane rotor 4, a
plurality of base workpieces (second workpieces Q2) are formed
simultaneously by obtaining a long continuous member (first
workpiece Q1), and dividing it. In this way, many base workpieces
(second workpieces Q2) are obtained by a few steps, and commonly
used to construct the intake valve timing control apparatus 1a and
exhaust valve timing control apparatus 1b. This is effective for
further simplifying the process of manufacturing, and thereby
reducing the manufacturing cost.
[0102] <Manufacturing Cost Reduced by Features of Manufacturing
Process> The manufacturing process for manufacturing the
components of valve timing control apparatus 1 according to the
present embodiment is characterized at least in the order of
operations constituting the manufacturing process, and serves to
reduce the manufacturing cost as follows. According to the present
embodiment, housing body 10 is manufactured by the process
including the extrusion operation, the coating operation, and the
cutting-off operation (and the carving operation) which are
performed in this order. Accordingly, first workpiece P1 is applied
with surface treatment, before first workpiece P1 is cut and
divided into a plurality of second workpieces P2. If the extrusion
operation, the cutting-off operation (and the carving operation),
and the coating operation are performed in this order, it is
necessary to apply each second workpiece P2 with anodic oxidation
treatment one by one, which increases the workload and time, and
thereby increases the manufacturing cost. This supposed process is
subject to a further problem that for maintaining the sealing
performance by ensuring the intimate contact between housing body
10 and sealing rings S1, S2 and S3, the open end surfaces 105, 102
and 103 of housing body 10 need to be applied with full
pore-sealing treatment at the anodic oxidation coating film or
treatment of removing the anodic oxidation coating film. Namely, it
is necessary to apply surface treatment to the surfaces of each
second workpiece P2 one by one, which surfaces face the sealing
plates 8 and 9, and abut on the sealing rings S1, S2 and S3. This
increases the cost of forming (workload, and time). In contrast,
the forming process according to the present embodiment that the
entire first workpiece P1 which is obtained by extrusion is applied
with anodic oxidation treatment at one time, is advantageous in
reducing the cost of forming. Moreover, the feature according to
the present embodiment that the cut surfaces obtained by the
cutting-off operation are used without further treatment, to
constitute surfaces abutting on the sealing rings S1, S2 and S3.
Specifically, housing body 10 is formed in a shape having openings
at axial ends by the extrusion operation and the cutting-off
operation. For sealing the openings of housing body 10, sealing
rings S1, S2 and S3 are provided between housing body 10 and
respective ones of sealing plates 8 and 9. One axial end surface
(the X-axis positive side cut surface 105) of housing body 10
obtained by the cutting-off operation is used as a surface abutting
on the sealing ring S3. The feature that the cut surface 105 is
formed with no anodic oxidation coating film, serves to ensure the
intimate contact with sealing ring S3, and thereby maintain the
sealing performance. This feature serves to eliminate the necessity
of full pore-sealing treatment or the like for the anodic oxidation
coating film at the X-axis positive side end of housing body 10,
and further reduce the cost of forming. The feature that the cut
surface 105 where the base layer of aluminum-based metal material
is exposed is applied with no further surface treatment, and used
to abut on the sealing ring S3, is advantageous in eliminating the
necessity of treatment for forming a coating film for maintaining
the sealing performance, and thereby further reducing the cost of
forming. The forming process according to the present embodiment
includes the carving operation of carving the other axial end
surface (the X-axis negative side open end surface) of housing body
10. Similar to the cut surfaces obtained by the cutting-off
operation, the cut surfaces obtained by the carving operation are
formed with no anodic oxidation coating film, so that the sealing
rings can be arranged to abut on any place in the cut surfaces.
This serves to reduce the cost of forming, while maintaining the
sealing performance. In other words, this feature serves to
maintain the sealing performance however the axial end surface of
housing body 10 is shaped, and thereby enhance the flexibility of
design. In the present embodiment, the X-axis negative side
longitudinal end surface 104 of housing body 10 is applied with
carving to form the fitting recess 101 in which rear plate 9 is
fixedly inserted. This is advantageous in making the valve timing
control apparatus 1 compact in the axial direction. Since the
fitting recess 101 obtained by carving is formed with no anodic
oxidation coating film, the intimate contact with sealing ring S1
is well maintained. Of second workpieces P2 of housing bodies 10
obtained through the cutting-off operation, the second workpiece P2
of housing body 10 that is obtained from one longitudinal end of
first workpiece P1 is formed with an anodic oxidation coating film
at one axial end through the coating operation. For this housing
body 10, at least part of this anodic oxidation coating film is
removed during the carving operation at the axial end surface, and
adapted to abut on the sealing rings S1 and S2, thus maintaining
the sealing performance. Incidentally, both of the axial end
surfaces of housing body 10 may be applied with carving for forming
a recess in which a sealing plate is inserted. The carving
operation may be omitted, where the cut surfaces obtained by the
cutting-off operation can be used as surfaces abutting on the
sealing rings. On the other hand, vane rotor 4 is manufactured by
the process including the extrusion operation, the cutting-off
operation, the carving operation, and the coating operation, which
are performed in this order. This feature is advantageous in that
the sliding portions of the surface of vane rotor 4 can be formed
with an anodic oxidation coating film simultaneously, and the vane
rotor 4 can be thus easily formed to have enhanced hardness and
wear resistance. Specifically, during the forming process, first,
second and third vanes 41, 42 and 43, and boss portion 401 of rotor
40 are formed, and thereafter the entire surface of vane rotor 4 is
applied with anodic oxidation treatment. Accordingly, the single
coating operation is sufficient for applying anodic oxidation
treatment to the surface of each vane 41, 42 or 43 in sliding
contact with housing HSG, the surface of each axial end surface of
vane rotor 4 in sliding contact with sealing plate 8 or 9, and the
surface of boss portion 401 in sliding contact with housing HSG.
This makes it possible to easily manufacture the valve timing
control apparatus 1 in which the sealing member 502 is prevented
from being mounted in slide hole 501 with inclination, or wear of
vane rotor 4 resulting from sliding motion of flange 513 of lock
piston 51 is suppressed. Incidentally, it is conceivable that the
sealing performance at the boundary between advance chamber A1, A2
or A3 and retard chamber R1, R2 or R3 may be lowered due to the
feature that the outside periphery of vane rotor 4 and the inside
periphery of housing body 10, including the portions in sliding
contact with sealing member 118 and sealing member 413, are formed
with anodic oxidation coating. However, this feature is relatively
insignificant, because this sealing place is not subject to severe
requirements as the boundary between the inside and outside of
housing HSG (at the axial ends of housing body 10).
[0103] <Manufacturing Cost Reduced by Facility of Attachment>
The initial phase of camshaft 3a or 3b with respect to the
crankshaft is set by the positioning means (positioning pin 45,
etc.) during attachment of valve timing control apparatus 1. First,
the following describes a process of attaching the valve timing
control apparatus 1 to the internal combustion engine, before
describing advantageous effects. The attaching process is
implemented by attaching an assembly unit without cap 7 to camshaft
3a or 3b, and then fixing the cap 7 to the assembly unit. The
attaching process is started by an operation of inserting the axial
end portion 30 of camshaft 3a or 3b from the X-axis negative side
into the through hole 92 of housing HSG, and inserting and setting
same into camshaft insertion hole 402 of vane rotor 4 mounted in
housing HSG of the assembly unit. The attaching process proceeds to
an operation of inserting and setting the camshaft bolts 33, 34 and
35 from the X-axis positive side through the large-diameter hole 81
of housing HSG into bolt holes 403, 404 and 405 of vane rotor 4,
and into bolt holes 32 of camshaft 3a or 3b. Then, the attaching
process proceeds to an operation of setting the sealing ring S4 in
annular sealing ring groove 821, and fixing the cap 7 to the female
thread portion 82 of housing HSG so as to close the large-diameter
hole 81. The provision of annular sealing ring groove 821 serves to
easily retain the sealing ring S4 in position, and enhance the
facility of assembling. The bottom of camshaft insertion hole 402
is formed with recess 44. The axial end surface 300 includes the
opening of first fluid passage 212 in which positioning pin 45 is
fixedly inserted, thus forming a projection. When the axial end
portion 30 of camshaft 3a or 3b is set in camshaft insertion hole
402, the projection (positioning pin 45) is fitted in recess 44,
and the axial end portion 30 is inserted toward the bottom of
camshaft insertion hole 402, so as to make the axial end surface
300 abut on the bottom of camshaft insertion hole 402. The fitting
between positioning pin 45 and recess 44 serves to restrict the
relative rotation between vane rotor 4 and camshaft 3a or 3b, and
thus position the vane rotor 4 and camshaft 3a or 3b with one
another in the rotational direction, and thereby set the rotational
phase of camshaft 3a or 3b (vane rotor 4) with respect to the
crankshaft (housing HSG). In this way, positioning pin 45 serves as
a blind plug closing the first fluid passage 212, and also serves
as a positioning means in combination with recess 44. Positioning
pin 45 (in first fluid passage 212) and recess 44 constitute a
positioning means for the rotational position of vane rotor 4 with
respect to camshaft 3a or 3b, i.e. the rotational phase of camshaft
3a or 3b with respect to the crankshaft, when valve timing control
apparatus 1 is attached to camshaft 3a or 3b. Incidentally, the
cross-section of recess 44 is not limited to an elliptic shape, but
may have a different shape, such as a circular shape, if recess 44
is adapted to be fitted to positioning pin 45 for restricting the
relative rotation. However, the construction according to the
present embodiment that recess 44 has an elliptic cross-section,
makes it easy to fit the positioning pin 45 with recess 44, because
recess 44 is provided with a margin in the radial direction of
rotor 40 so that errors in manufacturing and the like can be
absorbed. First fluid passage 212 serves as a passage of working
fluid, and also serves as a hole for fixing the positioning pin 45.
This feature is advantageous in eliminating the necessity of an
additional operation of forming the axial end portion 30 with a
projection for positioning, and thereby reducing the manufacturing
cost. Since the opening of first fluid passage 202 of camshaft 3a
or 3b at the axial end surface 300 is in intimate contact with and
closed by the bottom of camshaft insertion hole 402, it is
unnecessary to provide a blind plug for closing the opening. This
serves to reduce the number of parts, and the manufacturing cost.
Incidentally, the positioning means may be implemented by a
construction that the bottom of camshaft insertion hole 402 is
formed with a projection which is adapted to be fitted in a recess
of the axial end surface 300 (for example, the opening of first
fluid passage 212). However, the construction according to the
present embodiment that the axial end surface 300 is formed with
the projection for positioning is advantageous in ease of
assembling operation, as compared to the case of the construction
that the bottom of camshaft insertion hole 402 is formed with a
projection. The projection for positioning is implemented by a
combination of a pin hole and a pin in the present embodiment, but
may be implemented by machining or the like. However, the form
according to the present embodiment is advantageous in making it
possible to arbitrarily select a pin that is suitable for
positioning, as compared to the case of direct formation based on
machining or the like. The recess for positioning is constituted by
the opening of the fluid passage in the present embodiment, but may
be implemented by a recess that is formed by machining or the
like.
[0104] The provision of boss portion 401 makes it easy to attach
the valve timing control apparatus 1 to an existing engine. In
cases where a housing is directly rotatably supported by a
camshaft, attachment of a valve timing control apparatus to an
engine needs to be implemented by attaching a vane rotor to the
camshaft while checking a clearance between the housing and the
camshaft, which may be disadvantageous in ease of assembling
operation. Moreover, it is further necessary to change the design
in conformance with the attachment, for example, by extending the
end portion of the camshaft, so that the housing is suitably
rotatably supported by the end portion of the camshaft, and thereby
it is difficult to attach the valve timing control apparatus 1 to
an existing engine. In contrast, the feature according to the
present embodiment that the attachment of the valve timing control
apparatus 1 to the engine is implemented by inserting the boss
portion 401 into the through hole 92, and then inserting the axial
end portion 30 of camshaft 3a or 3b, is advantageous in ease of
inserting operation, because the axis of rotation of vane rotor 4
is suitably positioned to be identical to the axis of rotation of
housing HSG. Namely, it is unnecessary to care about whether
camshaft 3a or 3b is accurately positioned with a predetermined
clearance with housing HSG, because the insertion of axial end
portion 30 into camshaft insertion hole 402 serves to mechanically
position the axis of rotation of vane rotor 4 to be identical to
the axis of rotation of housing HSG, and thereby it is easy to
attach the vane rotor 4 to camshaft 3a or 3b. Moreover, the feature
that the housing HSG is rotatably supported by boss portion 401 in
a predetermined angular range beforehand, makes it unnecessary to
change the design in conformance with the attachment, for example,
by extending the end portion of the camshaft, so that the housing
is suitably rotatably supported by the end portion of the camshaft.
In this way, valve timing control apparatus 1 can be easily
attached to an existing engine.
[0105] The feature that the front plate 8 is provided with the
detachable cap 7, makes it easy to turn and engage the camshaft
bolts 33, 34 and 35. Specifically, while valve timing control
apparatus 1 is being attached, the assembly unit without cap 7 is
attached to camshaft 3a or 3b so that housing HSG has an opening
(large-diameter hole 81) at one axial end, through which the
camshaft bolts 33, 34 and 35 can be inserted, and turned to fix the
assembly unit (vane rotor 4) to camshaft 3a or 3b. Thereafter, the
opening of housing HSG is closed by cap 7. Incidentally, when
attached to housing HSG, the cap 7 faces the circular recess 406 of
vane rotor 4, and faces the heads 331, 341 and 351 of camshaft
bolts 33, 34 and 35, and thereby serves to prevent working fluid
from leaking from the back pressure relief section, and serves with
the recess 73 to accommodate the heads 331, 341 and 351 of camshaft
bolts 33, 34 and 35.
[0106] The following describes a first group of technical features,
and advantageous effects produced by the features. Japanese Patent
Application Publication No. 5-113112 discloses a valve timing
control apparatus for an internal combustion engine, which includes
a housing connected to a crankshaft, and a phase change mechanism
mounted in the housing, and connected to a camshaft. The housing is
formed with a pulley at its outside periphery to which torque is
transmitted from the crankshaft through a timing belt that is wound
around the pulley, so that the housing rotates in synchronization
with the crankshaft. The phase change mechanism operates in
response to supply and drainage of working fluid, for changing
valve timing, i.e. rotational phase of the camshaft with respect to
the crankshaft. The valve timing control apparatus described above
is subject to a problem that the timing belt may be degraded by
adhesion of working fluid exiting out of the housing. Accordingly,
it is desirable to provide a valve timing control apparatus for an
internal combustion engine in which such a problem is solved by
suitable sealing. The problem is solved by a valve timing control
apparatus comprising: a housing body having a tubular shape
including an opening at an axial end; a sealing plate closing the
opening of the housing body; and a sealing ring disposed between
the housing body and the sealing plate; wherein an anodic oxide
coating film layer is absent at a surface of the housing body in
contact with the sealing ring. This feature serves to suitably
maintain the sealing performance. The following describes each
technical feature, and advantageous effects produced by the feature
in detail.
[0107] <1-1> A valve timing control apparatus for an internal
combustion engine, comprises: a housing body (10) having a tubular
shape including an opening at an axial end (105), wherein the
housing body (10) is formed integrally with a pulley (100) at an
outside periphery of the housing body (10), and wherein the pulley
(100) is adapted to receive torque from a crankshaft of the
internal combustion engine; a sealing plate (8, 9) fixed to the
axial end (104, 105) of the housing body (10), the sealing plate
(8, 9) closing the opening of the housing body (10); a phase change
mechanism (vane rotor 4) mounted in the housing body (10), and
adapted to change a rotational phase of a camshaft (3a, 3b) of the
internal combustion engine with respect to the housing body (10) in
response to supply and drainage of working fluid; and a sealing
ring (S1, S2, S3) disposed between the housing body (10) and the
sealing plate (8, 9), wherein: the housing body (10) is formed of
an aluminum-based metal material and anodized, wherein the housing
body (10) includes a base layer and an anodic oxide coating film
layer; and the anodic oxide coating film layer is present at the
outside periphery of the housing body (10), and absent at a surface
(axial end surface 105, bottom surface 102, inside peripheral
surface 103) of the housing body (10) on which the sealing ring
(S1, S2, S3) abuts. The feature that the housing body (10) is
formed integrally with the pulley (100), serves to reduce the
radial size of the valve timing control apparatus (1). The feature
that the housing body (10) is formed of the aluminum-based metal
material, serves to reduce the weight of the valve timing control
apparatus (1). The feature that the housing body (10) is anodized
and the anodic oxide coating film layer is present at the outside
periphery of the housing body (10), serves to enhance the wear
resistance of the pulley (100). The feature that the anodic oxide
coating film layer is absent at the surface (axial end surface 105,
bottom surface 102, inside peripheral surface 103) of the housing
body (10) on which the sealing ring (S1, S2, S3) abuts, serves to
maintain the sealing performance, and suppress degradation of a
timing belt (1010) put over the pulley (100).
[0108] <1-2> In addition to the feature <1-1>: the
housing body (10) has a hollow cylindrical shape, wherein the
housing body (10) is formed integrally with a shoe (11, 12, 13) at
an inside periphery of the housing body (10), and wherein the shoe
(11, 12, 13) projects inwardly in a radial direction of the housing
body (10); the phase change mechanism (4) includes a vane rotor (4)
adapted to be fixed to a camshaft (3a, 3b) of the internal
combustion engine, and rotatably mounted in the housing body (10),
wherein the vane rotor (4) includes a vane (41, 42, 43), wherein
the vane (41, 42, 43) defines a working fluid chamber (advance
chamber A1, A2 or A3, retard chamber R1, R2 or R3) between the vane
(41, 42, 43) and the shoe (11, 12, 13), and wherein the working
fluid chamber (A1, A2, A3, R1, R2, R3) is adapted to supply and
drainage of working fluid; and the sealing ring (S1, S2) seals the
working fluid chamber (A1, A2, A3, R1, R2, R3) at the axial end
(104, 105) of the housing body (10). The feature <1-1> can be
thus adapted to the valve timing control apparatus provided with
the vane-type phase change mechanism (4).
[0109] <1-3> In addition to the feature <1-1>, the
sealing ring (S1, S2, S3) abuts on the base layer at the axial end
(104, 105). This feature serves to reduce the workload of
manufacturing the housing body (10), and thereby reduce the
manufacturing cost.
[0110] <1-4> In addition to the feature <1-1>, the
anodic oxide coating film layer is present also at an inside
periphery of the housing body (10). This feature serves to enhance
the wear resistance of the inside periphery of the housing body
(10) in sliding contact with the phase change mechanism (vane rotor
4).
[0111] <1-5> In addition to the feature <1-1>, the
valve timing control apparatus further comprises a plurality of
bolts (b1, b2, b3) extending in an axial direction of the housing
body (10), and fixing the sealing plate (8, 9) to the housing body
(10). This feature serves to compress the sealing ring (S1, S2, S3)
by the axial force of the bolts (b1, b2, b3), and thereby further
enhance the sealing performance.
[0112] <1-6> In addition to the feature <1-5>, the
sealing plate (8, 9) is formed of a harder material than the
housing body (10, aluminum-based metal material). This feature
serves to enhance the durability of the sealing plate (8, 9), and
enhance the intimateness of contact between the housing body (10)
and the sealing plate (8, 9), thereby further enhancing the sealing
performance. Specifically, the feature that the sealing plate (8,
9) is formed of an iron-based metal material, serves to further
enhance this advantageous effect.
[0113] <1-7> In addition to the feature <1-1>: the
housing body (10) includes an opening at another axial end (104,
105); and the valve timing control apparatus further comprises
another sealing plate (8, 9) fixed to the other axial end (104,
105). This feature serves to maintain the sealing performance of
the housing body (10) at its both axial ends.
[0114] <1-8> In addition to the feature <1-1>, the
sealing plate (8, 9) includes a sealing ring groove (906, 907, 908,
909, 89) that retains the sealing ring (S1, S2, S3). This feature
serves to easily retain the sealing ring (S1, S2, S3), and thereby
enhance the facility of assembling the valve timing control
apparatus. The feature that the sealing plate (8, 9) includes the
sealing ring groove (906, 907, 908, 909, 89), serves to make the
valve timing control apparatus compact, and reduce the
manufacturing cost.
[0115] <1-9> A method of producing a valve timing control
apparatus for an internal combustion engine, the valve timing
control apparatus comprising: a housing body (10) having a tubular
shape including an opening at each axial end (104, 105), wherein
the housing body (10) is formed integrally with a pulley (100) at
an outside periphery of the housing body (10), and wherein the
pulley (100) is adapted to receive torque from a crankshaft of the
internal combustion engine; at least one sealing plate (8) fixed to
one of the axial ends (105) of the housing body (10), the sealing
plate (8) closing a corresponding one of the openings of the
housing body (10); a phase change mechanism (vane rotor 4) mounted
in the housing body (10), and adapted to change a rotational phase
of a camshaft (3a, 3b) of the internal combustion engine with
respect to the housing body (10) in response to supply and drainage
of working fluid; and at least one sealing ring (S3) disposed
between the sealing plate (8) and the housing body (10), the method
comprises a process of producing the housing body (10), the process
comprising: an extruding operation of forming a first workpiece
(P1) by extruding an aluminum-based metal material, wherein the
first workpiece (P1) extends in a direction of extrusion; a coating
operation of forming a second workpiece (P2) by anodizing an entire
surface of the first workpiece (P1); and a cutting-off operation of
forming a third workpiece (P3) by cutting out of the second
workpiece (P2) to a predetermined length so as to form the third
workpiece (P3) with a cut surface (axial end surface 105) forming a
surface (105) of the housing body (10) on which the sealing ring
(S3) abuts. This feature allows to form a plurality of the third
workpieces (P3) of the housing body (10) by dividing the first
workpiece (P1) that is obtained by extrusion, and thereby serves to
enhance the production efficiency. The feature that the process
comprises the coating operation of forming the second workpiece
(P2) by anodizing the entire surface of the first workpiece (P1),
serves to reduce the cost of anodic oxidation treatment. The
feature that the process comprises the cutting-off operation of
forming the third workpiece (P3) with the cut surface (105) forming
the surface (105) of the housing body (10) on which the sealing
ring (S3) abuts, serves to further reduce the cost of anodic
oxidation treatment.
[0116] <1-10> In addition to the feature <1-9>: the
housing body (10) has a hollow cylindrical shape, wherein the
housing body (10) is formed integrally with a shoe (11, 12, 13) at
an inside periphery of the housing body (10), and wherein the shoe
(11, 12, 13) projects inwardly in a radial direction of the housing
body (10); the phase change mechanism (4) includes a vane rotor (4)
adapted to be fixed to a camshaft (3a, 3b) of the internal
combustion engine, and rotatably mounted in the housing body (10),
wherein the vane rotor (4) includes a vane (41, 42, 43), wherein
the vane (41, 42, 43) defines a working fluid chamber (advance
chamber A1, A2 or A3, retard chamber R1, R2 or R3) between the vane
(41, 42, 43) and the shoe (11, 12, 13), and wherein the working
fluid chamber (A1, A2, A3, R1, R2, R3) is adapted to supply and
drainage of working fluid; and the sealing ring (S1, S2) seals the
working fluid chamber (A1, A2, A3, R1, R2, R3) at the corresponding
axial end (104, 105) of the housing body (10). The feature
<1-9> can be thus adapted to the valve timing control
apparatus provided with the vane-type phase change mechanism
(4).
[0117] <1-11> In addition to the feature <1-9>, the
pulley (100) includes a plurality of projections arranged in a
circumferential direction of the housing body (10), and wherein
each projection extends in an axial direction of the housing body
(10). This feature makes it possible to form a plurality of the
housing bodies (10) with the pulleys (100) simultaneously with high
accuracy, and thereby reduce the manufacturing cost.
[0118] <1-12> A method of producing a valve timing control
apparatus for an internal combustion engine, the valve timing
control apparatus comprising: a housing body (10) having a tubular
shape including an opening at each axial end (104, 105), wherein
the housing body (10) is formed integrally with a pulley (100) at
an outside periphery of the housing body (10), and wherein the
pulley (100) is adapted to receive torque from a crankshaft of the
internal combustion engine; at least one sealing plate (9) fixed to
one of the axial ends (104) of the housing body (10), the sealing
plate (9) closing a corresponding one of the openings of the
housing body (10); a phase change mechanism (vane rotor 4) mounted
in the housing body (10), and adapted to change a rotational phase
of a camshaft (3a, 3b) of the internal combustion engine with
respect to the housing body (10) in response to supply and drainage
of working fluid; and at least one sealing ring (S1, S2) disposed
between the sealing plate (9) and the housing body (10), the method
comprises a process of producing the housing body (10), the process
comprising: an extruding operation of forming a first workpiece
(P1) by extruding an aluminum-based metal material, wherein the
first workpiece (P1) extends in a direction of extrusion; a coating
operation of forming a second workpiece (P2) by anodizing an entire
surface of the first workpiece (P1); a cutting-off operation of
forming a third workpiece (P3) by cutting out of the second
workpiece (P2) to a predetermined length; and a carving operation
of carving a longitudinal end surface of the third workpiece (P3)
so as to form the third workpiece (P3) with a cut surface (inside
peripheral surface 103, bottom surface 102) forming a surface of
the housing body (10) on which the sealing ring (S1, S2) abuts.
This feature serves to maintain the sealing performance while
allowing the open axial end of the housing body (10) to be carved
into an arbitrary shape, and thereby serves to enhance the
flexibility of design of the valve timing control apparatus while
reducing the cost of anodic oxidation treatment.
[0119] <1-13> In addition to the feature <1-12>, the
carving operation is implemented by carving the longitudinal end
surface of the third workpiece (P3) so as to form the third
workpiece (P3) with a fitting recess (101), wherein the fitting
recess (101) includes the cut surface (103, 102), and wherein the
sealing plate (9) is fixed in the fitting recess (101). The feature
that the sealing ring (S1, S2) is mounted in the fitting recess
(101) including the cut surface (103, 102), serves to maintain the
sealing performance, while reducing the axial size of the valve
timing control apparatus, and thereby enhancing the mountability of
the valve timing control apparatus.
[0120] <1-14> In addition to the feature <1-13>, the
method further comprises providing the sealing ring (S1) between an
inside periphery of the fitting recess (101) and an outside
periphery of the sealing plate (9). This feature serves to reduce
the radial size of the valve timing control apparatus in addition
to the axial size.
[0121] <Second Group of Technical Features> The following
describes a second group of technical features, and advantageous
effects produced by the features. Japanese Patent Application
Publication No. 2001-115807 discloses a valve timing control
apparatus for an internal combustion engine, which includes a
housing connected to a crankshaft, and includes a vane rotor
including a boss portion, wherein the boss portion serves as a
bearing for the housing. In this valve timing control apparatus,
the housing is rotating, while being subject to a torque
transmitted from the crankshaft, so that the boss portion is
subject to a high load from the housing. If the vane rotor
including the boss portion is formed of a relatively soft material,
such as an aluminum-based metal material, the boss portion may be
worn heavily. In view of the foregoing, it is desirable to provide
a valve timing control apparatus for an internal combustion engine,
in which wear of a boss portion can be reduced. The problem is
solved by a valve timing control apparatus in which a portion of a
boss portion in sliding contact with a housing is applied with
anodic oxidation treatment. This feature serves to reduce the wear
of the boss portion. The following describes each technical
feature, and advantageous effects produced by the feature in
detail.
[0122] <2-1> A valve timing control apparatus for an internal
combustion engine, comprises: a housing (HSG) adapted to receive
torque from a crankshaft of the internal combustion engine, and
formed with a through hole (92) extending along an axis of rotation
(O); and a vane rotor (4) rotatably mounted in the housing (HSG),
wherein the vane rotor (4) includes a boss portion (401) adapted to
be fixed to a camshaft (3a, 3b) of the internal combustion engine,
and wherein the boss portion (401) extends along the axis of
rotation (O), and includes a portion in sliding contact with the
through hole (92), wherein the vane rotor (4) is formed of an
aluminum-based metal material, and the portion of the boss portion
(401) is anodized. The feature that the boss portion (401) bears
the housing (HSG) through the through hole 92, serves to enhance
the facility of attaching the valve timing control apparatus to the
camshaft (3a, 3b) of an existing internal combustion engine. The
feature that the vane rotor (4) is formed of the aluminum-based
metal material, serves to reduce the weight of the valve timing
control apparatus. The feature that the boss portion (401) includes
a portion in sliding contact with the through hole (92), wherein
the portion of the boss portion (401) is anodized, serves to
suppress wear of the boss portion (401).
[0123] <2-2> In addition to the feature <2-1>: the
housing (HSG) includes: a housing body (10) having a hollow
cylindrical shape including an opening at an axial end (104),
wherein the housing body (10) is adapted to receive torque from the
crankshaft, and formed integrally with a shoe (11, 12, 13) at an
inside periphery of the housing body (10), and wherein the shoe
(11, 12, 13) projects inwardly in a radial direction of the housing
body (10); and a sealing plate (rear plate 9) fixed to the axial
end (104) of the housing body (10), the sealing plate (9) closing
the opening of the housing body (10), wherein the sealing plate (9)
is formed with the through hole (92) at a central portion (91); and
the vane rotor (4) includes: a rotor (40) from which the boss
portion (401) projects along the axis of rotation (O); and a vane
(41, 42, 43) projecting outwardly in the radial direction of the
housing body (10) with respect to the rotor (40), and defining a
working fluid chamber (advance chamber A1, A2 or A3, or retard
chamber R1, R2 or R3) between the vane (41, 42, 43) and the shoe
(11, 12, 13), wherein the working fluid chamber (A1, A2, A3, R1,
R2, R3) is adapted to supply and drainage of working fluid.
[0124] <2-3> In addition to the feature <2-1>, the vane
rotor (4) has an anodized axial end surface in sliding contact with
the housing (HSG). This feature serves to enhance the wear
resistance of the portion of the vane rotor (4) in sliding contact
with the housing (HSG: sealing plate 8, 9).
[0125] <2-4> In addition to the feature <2-2>, the
sealing plate (9) is formed of a harder material than the vane
rotor (4). This serves to enhance the durability of the valve
timing control apparatus. Specifically, the sealing plate (9) is
formed of an iron-based metal material. This feature is
advantageous in the facility of processing, the manufacturing cost,
etc.
[0126] <2-5> In addition to the feature <2-1>, an
entire surface of the vane rotor (4) is anodized. This feature
serves to enhance the facility of manufacturing the valve timing
control apparatus which produces the advantageous effects according
to the features <2-1> and <2-3>, because it is
sufficient to apply surface treatment once to the entire surface of
the vane rotor (4) that includes portions in sliding contact with
the housing (HSG).
[0127] <2-6> A method of producing the valve timing control
apparatus according to the feature <2-1>, the method
comprises a process of producing the vane rotor (4), the process
comprising anodizing an entire surface of the vane rotor (4). This
feature serves similar to the feature <2-5>. Specifically,
the method is a method of producing the valve timing control
apparatus according to the feature <2-2> that is provided
with the housing (HSG) and the vane rotor (4), the method
comprising a process of producing the vane rotor (4), the process
comprising: forming the vane (41, 42, 43) and the rotor (40); and
then anodizing an entire surface of the vane rotor (4).
[0128] <2-7> In addition to the feature <2-6>, the
process comprises: an extruding operation of forming a first
workpiece (Q1) by extruding an aluminum-based metal material,
wherein the first workpiece (Q1) extends in a direction of
extrusion; a cutting-off operation of forming a second workpiece
(Q2) by cutting out of the first workpiece (Q1) to a predetermined
length; and a carving operation of forming the second workpiece
(Q2) with the boss portion (401) by carving. This feature makes it
possible to produce many vane rotors (4) at one time, and thereby
serves to reduce the manufacturing cost.
[0129] <Third Group of Technical Features> The following
describes a third group of technical features, and advantageous
effects produced by the features. Japanese Patent Application
Publication No. 2005-520084 discloses a valve timing control
apparatus for an internal combustion engine, which is adapted to be
fixed to a camshaft, and to which torque is transmitted through a
belt, and which includes a belt guide for restricting movement of
the belt in an axial direction of the camshaft. This valve timing
control apparatus is subject to a problem that in an engine room of
a motor vehicle to which the internal combustion engine is mounted,
the belt guide is close to a side wall of the engine room so that
the mountability of the valve timing control apparatus is low. In
view of the foregoing, it is desirable to provide a valve timing
control apparatus for an internal combustion engine, whose
mountability is maintained in spite of provision of a belt guide.
This problem is solved by a valve timing control system which
includes an intake valve timing control apparatus fixed to an
intake camshaft and an exhaust valve timing control apparatus fixed
to an exhaust camshaft, and includes a belt wound over the intake
camshaft and the exhaust camshaft for transmitting torque
therebetween, wherein one of the intake valve timing control
apparatus and the exhaust valve timing control apparatus farther
from an engine room side wall is provided with a belt guide. This
feature serves to maintain the mountability of the valve timing
control apparatus. The following describes each technical feature,
and advantageous effects produced by the feature in detail.
[0130] <3-1> A valve timing control system for an internal
combustion engine, wherein the internal combustion engine includes
an intake camshaft (3a) adapted to drive an intake valve, an
exhaust camshaft (3b) adapted to drive an exhaust valve, and a belt
(1010) wound over the intake camshaft (3a) and the exhaust camshaft
(3b) for transmitting torque therebetween, the valve timing control
system comprising: a first valve timing control apparatus (1a)
adapted to be fixed to one of the intake camshaft (3a) and the
exhaust camshaft (3b); and a second valve timing control apparatus
(1b) adapted to be fixed to another one of the intake camshaft (3a)
and the exhaust camshaft (3b), and adapted to be located closer to
a side wall (W) of an engine room in which the internal combustion
engine is mounted than the first valve timing control apparatus
(1a), wherein: the first valve timing control apparatus (1a)
includes a belt guide (80) adapted to restrict movement of the belt
(1010) in at least one axial direction (in the X-axis positive
direction); and the movement of the belt (1010) is free with
respect to the second valve timing control apparatus (1b). Namely,
only the first valve timing control apparatus (1a) farther from the
side wall (W) is provided with a belt guide (80). This feature
serves to maintain the mountability of the valve timing control
system.
[0131] <3-2> In addition to the feature <3-1>: each of
the first and second valve timing control apparatuses (1a, 1b)
includes a pulley (100) including a projection and a recess,
wherein the projection and recess extend in the axial direction;
and the belt (1010) is wound around each pulley (100) for
transmitting torque. This feature serves to effectively restrict
the movement of the belt (1010) by the belt guide (80), although
the belt guide (80) tends to move in the axial direction with
respect to the pulley (100) because the projection and recess of
pulley (100) extend in the axial direction.
[0132] <3-3> In addition to the feature <3-2>: the belt
guide (80) is disposed at an axial end of the pulley (100) of the
first valve timing control apparatus (1a), wherein the belt guide
(80) projects outwardly with respect to a bottom of the recess in a
radial direction of the pulley (100); and the recess of the pulley
(100) of the second valve timing control apparatus (1b) is open at
both axial ends. This feature serves to prevent each axial end of
the second valve timing control apparatus (1b) from interfering
with the side wall (W: projection W1), and thereby maintain the
mountability of the valve timing control apparatus further
effectively.
[0133] <3-4> In addition to the feature <3-3>, the belt
guide (80) extends outside of the belt (1010) in the radial
direction of the pulley (100) in the first valve timing control
apparatus (1a). This feature serves to enhance the function of the
belt guide (80).
[0134] <3-5> In addition to the feature <3-3>: each of
the first and second valve timing control apparatuses (1a, 1b)
includes: a housing body (10) adapted to be attached to an axial
end of the corresponding one of the intake camshaft (3a) and the
exhaust camshaft (3b), and formed integrally with the pulley (100)
at an outside periphery of the housing body (10); a front plate (8)
sealing a first axial end (X-axis positive side axial end) of the
housing body (10); and a rear plate (9) sealing a second axial end
(X-axis negative side axial end) of the housing body (10) closer to
the corresponding one of the intake camshaft (3a) and the exhaust
camshaft (3b); and the front plate (8) of the first valve timing
control apparatus (1a) forms the belt guide (80). The feature that
the housing body (10) is formed integrally with the pulley (100),
serves to reduce the radial size of each of the first and second
valve timing control apparatuses (1a, 1b), and thereby enhance the
mountability of the valve timing control system. The feature that
the front plate (8) of the first valve timing control apparatus
(1a) forms the belt guide (80), serves to maintain the mountability
of the valve timing control system, especially for a motor vehicle
where the axial end (the X-axis positive side axial end) of the
camshaft farther from the camshaft is subject to severe dimensional
requirements in an engine room.
[0135] <3-6> In addition to the feature <3-1>, axial
directions of the intake camshaft (3a) and the exhaust camshaft
(3b) cross a vehicle longitudinal direction. Specifically, the
axial directions of the intake camshaft (3a) and the exhaust
camshaft (3b) are substantially perpendicular to the vehicle
longitudinal direction.
[0136] <3-7> In addition to any one of the features
<3-1> to <3-6>: the internal combustion engine is a
V-type engine; and the first and second valve timing control
apparatuses (1a, 1b) are adapted to the intake camshaft (3a) and
the exhaust camshaft (3b) that are provided at least one bank of
the internal combustion engine. The produced effects <3-1> to
<3-6> are more significant for V-type engines which are
subject to severe dimensional requirements. Especially, the
features <3-1> to <3-5> serve to maintain the
mountability of the valve timing control system more significantly
for V-type engines applied with the feature <3-6> where the
axial directions of the intake camshaft (3a) and the exhaust
camshaft (3b) cross (specifically, substantially perpendicular to)
the vehicle longitudinal direction. Specifically, of the first and
second valve timing control apparatuses (1a, 1b) of one cylinder
bank, only the first valve timing control apparatus (1a) is
provided with the belt guide (80) according to the feature
<3-1>, wherein the first valve timing control apparatus (1a)
is attached to one of the intake camshaft (3a) and the exhaust
camshaft (3b) closer to the other cylinder bank. More specifically,
each of the first and second valve timing control apparatuses (1a,
1b) includes a pulley (100) including a projection and a recess,
wherein the projection and recess extend in the axial direction;
and the belt (1010) is wound around each pulley (100) for
transmitting torque. The belt guide (80) is disposed at an axial
end of the pulley (100) of the first valve timing control apparatus
(1a), wherein the first valve timing control apparatus (1a) is
attached to the intake camshaft (3a) closer to the other cylinder
bank, wherein the belt guide (80) projects outwardly from a bottom
of the recess in a radial direction of the pulley (100); and the
recess of the pulley (100) of the second valve timing control
apparatus (1b) is open at both axial ends, wherein the second valve
timing control apparatus (1b) is attached to one of the intake
camshaft (3a) and the exhaust camshaft (3b) that is located outside
of the cylinder bank (farther from the other cylinder bank).
[0137] <Fourth Group of Technical Features> The following
describes a fourth group of technical features, and advantageous
effects produced by the features. Japanese Patent Application
Publication No. 11-218008 discloses a valve timing control
apparatus of a vane type for an internal combustion engine, which
includes a housing to which torque is transmitted form outside, and
a vane rotor rotatably mounted in the housing, wherein the vane
rotor is fixed to a camshaft by a single bolt at the axis of
rotation of the vane rotor. This valve timing control apparatus is
subject to a problem that the bolt tends to be released, for
example, by an alternating torque from valve springs. In view of
the foregoing, it is desirable to provide a valve timing control
apparatus in which fixation of a vane rotor to a camshaft is
strengthened. This problem is solved by a valve timing control
apparatus in which a rotor of a vane rotor includes a plurality of
fixing portions which are arranged and spaced from one another in a
circumferential direction. This feature serves to strengthen the
fixation of the vane rotor. The following describes each technical
feature, and advantageous effects produced by the feature in
detail.
[0138] <4-1> A valve timing control apparatus for an internal
combustion engine, comprises: a hollow housing (HSG) adapted to
receive torque; and a vane rotor (4) rotatably mounted in the
housing (HSG), including a rotor (40) adapted to be fixed to a
camshaft (3a, 3b) of the internal combustion engine, wherein the
rotor (40) includes a plurality of fixing portions (bolt holes 403,
404 and 405) adapted to be fixed to the camshaft (3a, 3b), and
wherein the fixing portions (403, 404, 405) are arranged in a
circumferential direction of the rotor (40), and separated from one
another. The feature that the rotor (40) includes the plurality of
fixing portions (403, 404, 405), serves to strengthen the fixation
of the vane rotor (4) to the camshaft (3a, 3b). The feature that
the fixing portions (403, 404, 405) are arranged in the
circumferential direction of the rotor (40), and separated from one
another, serves to strengthen the fixation of the vane rotor (4)
effectively.
[0139] <4-2> In addition to the feature <4-1>: the
torque is transmitted to the housing (HSG) through a belt (1010);
the vane rotor (4) includes: a plurality of vanes (41, 42, 43)
projecting outwardly in radial directions of the rotor (40) with
respect to the rotor (40), and defining at least one working fluid
chamber (first, second and third advance chambers A1, A2 and A3,
and first, second and third retard chambers R1, R2 and R3) in the
housing (HSG), wherein the working fluid chamber (A1, A2, A3, R1,
R2, R3) is adapted to supply and drainage of working fluid; and a
cylinder (slide hole 501) formed in the vane rotor (4), extending
in a direction of an axis of rotation (O) of the vane rotor (4);
and the valve timing control apparatus further comprises: an
engaging member (lock piston 51) slidably mounted in the cylinder
(501), and arranged to move forward and rearward in the cylinder
(501) according to an operating state of the internal combustion
engine; an engaging recess (521) provided in an axial end portion
of the housing (HSG) closer to the camshaft (3a, 3b); a biasing
member (coil spring 53) mounted in a back pressure chamber (50)
formed in the cylinder (501), and arranged to bias the engaging
member (51) toward the engaging recess (521); and a back pressure
relief section (back pressure hole 407) formed in a central portion
of the rotor (40) surrounded by and closer to the axis of rotation
(O) than the fixing portions (bolt holes 403, 404 and 405), for
relieving pressure from the back pressure chamber (50) to a space
within the internal combustion engine. The feature that the torque
is transmitted through the belt (1010), serves to reduce the
manufacturing cost, and reduce the weight of the valve timing
control apparatus. The feature that the cylinder (501), engaging
member (51), engaging recess (521), and biasing member (coil spring
53) constitute a lock mechanism, serves to suppress, by the
simply-constructed lock mechanism, noise that may be caused by the
valve timing control apparatus at start of the internal combustion
engine. The feature that the cylinder (slide hole 501) extends in
the direction of the axis of rotation (O) of the vane rotor (4),
serves to stabilize the locking operation. The feature that the
back pressure relief section (407) is formed for relieving pressure
from the back pressure chamber (50), serves to smooth the lock
release operation of the lock mechanism, namely, smooth the
disengaging motion of the engaging member (51) from the engaging
recess (521). The feature that the back pressure relief section
(407) is formed for relieving pressure from the back pressure
chamber (50) to the space within the internal combustion engine,
where the back pressure chamber (50) is formed in the cylinder
(501) and located at a side (the X-axis positive side) farther from
the camshaft (3a, 3b) or the internal combustion engine, serves to
enhance the durability of the belt (1010). The feature that the
back pressure relief section (407) is formed in the central portion
of the rotor (40) surrounded by and closer to the axis of rotation
(O) than the fixing portions (403, 404, 405), serves to reduce the
radial size of the rotor (40) or the vane rotor (4), and thereby
make the valve timing control apparatus compact in size. The
plurality of vanes (41, 42, 43) define at least one advance chamber
(A1, A2 or A3) and at least one retard chamber (R1, R2 or R3)
between the vanes (41, 42, 43) and shoes (11, 12 and 13), wherein
the advance chamber and the retard chamber (A1, A2, A3, R1, R2, R3)
are adapted to supply and drainage of working fluid.
[0140] <4-3> In addition to the feature <4-2>: the
rotor (40) is formed with a communication hole (retard fluid
passage 408, advance fluid passage 409) hydraulically connected
between the working fluid chamber (A1, A2, A3, R1, R2, R3) and a
fluid passage (first fluid passages 202 and 212; second fluid
passages 201, 203, 211 and 213) formed in the camshaft (3a, 3b),
wherein the fluid passage (202, 212; 201, 203, 211, 213) is located
between adjacent two of the fixing portions (403, 404, 405) in a
circumferential direction of the rotor (40); and the back pressure
relief section (back pressure hole 407) is located closer to the
axis of rotation (O) than the fluid passage (202, 212; 201, 203,
211, 213). This feature serves to make the valve timing control
apparatus compact in size, wherein it is unnecessary to rearrange
the passages (first fluid passage 202, etc.) for supply and
drainage of working fluid.
[0141] <4-4> In addition to the feature <4-1>, each of
the fixing portions (bolt holes 403, 404 and 405) is a bolt
insertion hole extending through the rotor (40), wherein a camshaft
bolt (33, 34, 35) extends through the bolt insertion hole, and
fixes the rotor (40) to an axial end surface (300) of the camshaft
(3a, 3b). This feature makes it possible to easily assemble the
valve timing control apparatus, and easily manage the strength of
fixation, as compared to another manner such as swaging or
welding.
[0142] <4-5> In addition to the feature <4-2>: the
camshaft (3a, 3b) is formed with a first back pressure passage (31)
inside, wherein the first back pressure passage (31) is
hydraulically connected between the axial end surface (300) of the
camshaft (3a, 3b) and the space within the internal combustion
engine; and the back pressure relief section (407) is a back
pressure hole that is hydraulically connected to the back pressure
chamber (50), and arranged in such a position at a surface closer
to the camshaft (3a, 3b) as to face the first back pressure passage
(31). The feature that the camshaft (3a, 3b) is formed with a first
back pressure passage (31) inside, serves to make the valve timing
control apparatus compact in size. The feature that the opening of
the back pressure relief section (407) faces the first back
pressure passage (31), is advantageous in the facility of
processing, and the manufacturing cost.
[0143] <4-6> In addition to the feature <4-5>, the back
pressure hole (407) is located at the axis of rotation (O) of the
rotor (40). This feature serves to enhance the balance of the vane
rotor (4) around the axis of rotation, and serves to ensure the
radial thickness of the rotor (40), and thereby ensure the strength
of the vane rotor (4).
[0144] <4-7> In addition to the feature <4-5>: the
first back pressure passage (31) is located at an axis of rotation
(O) of the camshaft (3a, 3b); and the back pressure hole (407)
extends through the rotor (40), and faces the first back pressure
passage (31). This feature serves to enhance the balance of the
camshaft (3a, 3b) around the axis of rotation, and also produces
the same effect according to the feature <4-6>.
[0145] <4-8> In addition to the feature <4-1>, the
fixing portions (bolt holes 403, 404 and 405) are substantially
evenly spaced in the circumferential direction. This feature makes
it easy to maintain the balance of each of the vane rotor (4) and
the camshaft (3a, 3b) around the axis of rotation. The further
feature that each fixing portion is a bolt insertion hole (bolt
hole 403, 404 or 405), serves to maintain the strength of the rotor
(40).
[0146] <4-9> In addition to the feature <4-2>: the
rotor (40) is formed with a communication hole (retard fluid
passage 408, advance fluid passage 409) hydraulically connected
between the working fluid chamber (A1, A2, A3, R1, R2, R3) and a
fluid passage (202, 212; 201, 203, 211, 213) formed in the camshaft
(3a, 3b), wherein the fluid passage (202, 212; 201, 203, 211, 213)
is located between adjacent two of the fixing portions (403, 404,
405) in a circumferential direction of the rotor (40); the rotor
(40) is formed with a camshaft insertion hole (402) having a
bottom, wherein the camshaft (3a, 3b) is inserted in the camshaft
insertion hole (402); and the communication hole (retard fluid
passage 408, advance fluid passage 409) extends through the rotor
(40) in a radial direction of the rotor (40). This feature serves
to enhance the facility of processing and the flexibility of layout
of the back pressure relief section (back pressure hole 407), and
makes it easy to make the rotor (40) compact in size.
[0147] <4-10> In addition to the feature <4-9>: the
fluid passage (202, 212; 201, 203, 211, 213) includes: a first
fluid passage (202, 212) extending in an axial direction of the
camshaft (3a, 3b); and a second fluid passage (201, 203, 211, 213)
extending from the first fluid passage (202, 212) in a radial
direction of the camshaft (3a, 3b) and communicating with the
communication hole (retard fluid passage 408, advance fluid passage
409); and the first fluid passage (202) has an opening at an axial
end surface (300) of the camshaft (3a, 3b), wherein the opening of
the first fluid passage (202) is closed by the bottom of the
camshaft insertion hole (402). This feature serves to eliminate the
necessity of providing the first fluid passage (202) with a blind
plug, and thereby reduce the number of parts and the manufacturing
cost.
[0148] <4-11> In addition to the feature <4-10>, the
valve timing control apparatus further comprises a positioning pin
(45) fixedly inserted in the opening of the first fluid passage
(202), and inserted in a recess (44) formed in the bottom of the
camshaft insertion hole (402), so as to position the rotor (40) and
the camshaft (3a, 3b) with respect to one another in a rotational
direction. The feature that the opening of the first fluid passage
(202) is used to fix the positioning pin (45), and thereby
constitutes a positioning means, serves to reduce the manufacturing
cost.
[0149] <4-12> In addition to the feature <4-2>: the
vane rotor (4) is formed with a second back pressure passage (58,
406) that includes a recess formed in an axial end surface (X-axis
positive side axial end surface) of the vane rotor (4) farther from
the camshaft (3a, 3b); and the back pressure relief section (407)
is a back pressure hole that is hydraulically connected to the back
pressure chamber (50) through the second back pressure passage
(radial groove 58, circular recess 406). This feature serves to
reduce the axial size of the housing (HSG), while maintaining the
working ability of the vane rotor (4).
[0150] <4-13> In addition to the feature <4-12>: each
of the fixing portions (bolt holes 403, 404 and 405) is a bolt
insertion hole extending through the rotor (40), wherein a camshaft
bolt (33, 34, 35) extends through the bolt insertion hole, and
fixes the rotor (40) to an axial end surface (300) of the camshaft
(3a, 3b); the second back pressure passage (58, 406) includes: a
circular recess (406) formed in the axial end surface of the vane
rotor (4); and a radial groove (58) extending from the circular
recess (406) outwardly in a radial direction of the rotor (40), and
hydraulically communicating with the back pressure chamber (50);
and the circular recess (406) is formed with the bolt insertion
holes (403, 404, 405) and the back pressure hole (407). This
feature serves to suppress projection of the head (331, 341 or 351)
of the camshaft bolt (33, 34 or 35), and thereby reduce the axial
size of the valve timing control apparatus. This feature also
serves to enhance the facility of processing and the flexibility of
layout of the back pressure hole (407), and thereby makes it easy
to make the rotor (40) compact in size.
[0151] <4-14> In addition to the feature <4-13>, the
housing (HSG) includes: a housing body (10) having a hollow
cylindrical shape; a front plate (8) sealing a first axial end of
the housing body (10), and including a detachable cap (7) in a
position to face the circular recess (406) of the vane rotor (4);
and a rear plate (9) sealing a second axial end of the housing body
(10) closer to the camshaft (3a, 3b), wherein the camshaft (3a, 3b)
is inserted in the rear plate (9). This feature serves to suppress
degradation of the belt (1010), while enhancing the mountability of
the valve timing control apparatus.
[0152] <4-15> In addition to the feature <4-14>, the
cap (7) is formed with a recess (73) at a surface facing the
circular recess (406), wherein the recess (73) accommodates at
least a part of a head (331, 341, 351) of the camshaft bolt (33,
34, 35). This feature serves to absorb the projection of the head
(331, 341, 351) of the camshaft bolt (33, 34, 35), and thereby
serves to make the valve timing control apparatus compact in
size.
[0153] <Fifth Group of Technical Features> The following
describes a fifth group of technical features, and advantageous
effects produced by the features. Japanese Patent Application
Publication No. 2000-002104 discloses a valve timing control
apparatus of a vane type for an internal combustion engine, which
includes an engaging member for restricting relative rotation
between a vane rotor and a housing, wherein: the vane rotor is
formed with a cylinder in which a hollow cylindrical member is
fixed; and the engaging member is mounted in the cylinder, in
sliding contact with an inside periphery of the hollow cylindrical
member. This valve timing control apparatus is subject to a problem
that the hollow cylindrical member may be fixed with inclination
with respect to the cylinder, and thereby the engaging member may
be mounted with inclination with respect to the cylinder. In view
of the foregoing, it is desirable to provide a valve timing control
apparatus for an internal combustion engine, in which inclination
of an engaging member is suppressed. This problem is solved by a
valve timing control apparatus in which a cylinder to which a
cylindrical member is fixed is applied with anodic oxidation
treatment. This feature serves to suppress inclination of the
engaging member. The following describes each technical feature,
and advantageous effects produced by the feature in detail.
[0154] <5-1> A valve timing control apparatus for an internal
combustion engine, comprises: a hollow housing (HSG) adapted to
receive torque; a vane rotor (4) formed of an aluminum-based metal
material, and rotatably mounted in the housing (HSG), the vane
rotor (4) including: a plurality of vanes (41, 42, 43) defining at
least one working fluid chamber (first, second and third advance
chambers A1, A2 and A3, first, second and third retard chambers R1,
R2 and R3) in the housing (HSG), wherein the working fluid chamber
(A1, A2, A3, R1, R2, R3) is adapted to supply and drainage of
working fluid; and a cylinder (slide hole 501) formed in the vane
rotor (4), and anodized; a hollow cylindrical member (sealing
member 502) fixed in the cylinder (501); a lock member (lock piston
51) slidably mounted in the hollow cylindrical member (502), the
lock member (51) including a tip arranged to move forward and
rearward with respect to the vane rotor (4) according to an
operating state of the internal combustion engine; a lock recess
(engaging recess 521) provided in an axial end portion of the
housing (HSG) facing the tip of the lock member (51), wherein the
tip of the lock member (51) is adapted to be inserted in the lock
recess (521); and a biasing member (coil spring 53) mounted in the
cylinder (501), and arranged to bias the lock member (51) toward
the lock recess (521). The feature that the cylinder (501), lock
member (51), lock recess (521), and biasing member (coil spring 53)
constitute a lock mechanism, serves to suppress, by the
simply-constructed lock mechanism, noise that may be caused by the
valve timing control apparatus at start of the internal combustion
engine. The feature that the vane rotor (4) is formed of the
aluminum-based metal material, serves to reduce the weight of the
valve timing control apparatus (1). The feature that the hollow
cylindrical member is fixed in the cylinder whose surface is
hardened by anodic oxidation treatment, serves to suppress
inclination of the hollow cylindrical member, and thereby maintain
the working ability of the lock member, and maintain the
controllability of the valve timing control apparatus. The feature
<5-1> is implemented so that: the torque is transmitted from
a crankshaft to the housing (HSG); the housing (HSG) is formed
integrally with a shoe (11, 12, 13) at an inside periphery of the
housing (HSG), and wherein the shoe (11, 12, 13) projects inwardly
in a radial direction of the housing (HSG); the plurality of vanes
(41, 42, 43) define an advance chamber (A1, A2 or A3) and a retard
chamber (R1, R2 or R3) in cooperation with the shoe (11, 12, 13); a
rotor (40) is disposed in a position surrounded by and closer to an
axis of rotation than the vanes (41, 42, 43); the lock member is a
lock pin (51); and the hollow cylindrical member (sealing member
502) is a ring-shaped member.
[0155] <5-2> In addition to the feature <5-1>, the
cylinder (slide hole 501) extends in an axial direction of the vane
rotor (4) so that the tip of the lock member (lock piston 51) moves
forward and rearward in the cylinder (501) in the axial direction
of the vane rotor (4). This feature serves to stabilize the locking
operation.
[0156] <5-3> In addition to the feature <5-1>, the
hollow cylindrical member (sealing member 502) is formed of a
material having a higher wear resistance than anodic oxide coating.
This feature serves to suppress wear of the cylinder (slide hole
501) effectively.
[0157] <5-4> In addition to the feature <5-1>, the
hollow cylindrical member (sealing member 502) is press-fitted in
the cylinder (slide hole 501). This feature makes it easy to set
and fix the hollow cylindrical member, and prevent the hollow
cylindrical member from being fixed with inclination.
[0158] <5-5> In addition to the feature <5-1>, a
surface of the vane rotor (4) including an inside peripheral
surface of the cylinder (slide hole 501) is anodized. This feature
makes it possible to easily manufacture the valve timing control
apparatus according to the feature <5-1>, while enhancing the
wear resistance of a portion of the vane rotor (4) in sliding
contact with the housing (HSG).
[0159] <5-6> In addition to the feature <5-1>: the
hollow cylindrical member (sealing member 502) has a shorter
longitudinal size than the cylinder (slide hole 501), and extends
from a longitudinal end of the cylinder (501); the lock member
(lock piston 51) includes a small-diameter portion (sliding portion
512, engaging portion 511) and a large-diameter portion (flange
513); the small-diameter portion (512, 511) is slidably fitted to
an inside periphery of the hollow cylindrical member (502); and the
large-diameter portion (513) is slidably fitted to an inside
periphery of the cylinder (501). This feature serves to simply
define a plurality of chambers for applying individual forces to
the lock member. The feature <5-6> is implemented so that:
the small-diameter portion (engaging portion 511) of the lock
member (lock piston 51) is adapted to move forward and backward
with respect to the vane rotor (4), and move into the lock recess
(engaging recess 521). The small-diameter portion (512, 511) is a
distal end portion of the lock member, whereas the large-diameter
portion (513) is a proximal end portion of the lock member, wherein
the biasing member is arranged to bias the lock member from the
large-diameter portion (proximal end portion) to the small-diameter
portion (distal end portion).
[0160] <5-7> In addition to the feature <5-6>: the
vanes (41, 42, 43) define at least two of the working fluid
chambers as an advance chamber (first advance chamber A1) and a
retard chamber (first retard chamber R1) in the housing (HSG); one
of the advance chamber and the retard chamber (A1) is hydraulically
connected for hydraulic pressure supply to a space (second
pressure-receiving chamber 59) between the tip of the lock member
(lock piston 51) and the axial end portion (the X-axis positive
side surface of rear plate 9) of the housing (HSG) facing the tip
of the lock member (51); and another one of the advance chamber and
the retard chamber (R1) is hydraulically connected for hydraulic
pressure supply to a space (first pressure-receiving chamber 55)
between the large-diameter portion (flange 513) of the lock member
(51) and the hollow cylindrical member (sealing member 502). This
feature serves to reduce the frequency of operation of the lock
member, and thereby enhance the durability of the valve timing
control apparatus.
[0161] <5-8> In addition to the feature <5-6>: the
hollow cylindrical member (sealing member 502) is formed of a
material having a higher wear resistance than anodic oxide coating;
and a smaller clearance is provided between the small-diameter
portion (sliding portion 512) of the lock member (lock piston 51)
and the inside periphery of the hollow cylindrical member (502)
than between the large-diameter portion (flange 513) of the lock
member (51) and the inside periphery of the cylinder (slide hole
501). This feature serves to further suppress wear of the sliding
portion in sliding contact with the lock member.
[0162] <5-9> In addition to the feature <5-1>: the
housing (HSG) is formed with a shoe (11) at an inside periphery of
the housing (HSG); and one of the tip (engaging portion 511) of the
lock member (lock piston 51) and the lock recess (engaging recess
521) has an inclined surface through which the biasing member (coil
spring 53) applies a biasing force so as to press one of the vanes
(41) to the shoe (11). This feature serves to produce a wedging
effect by which the vane rotor (4) can be reliably fixed in a lock
position, while maintaining the working ability of the lock member
according to the feature <5-1>. The feature <5-9> is
implemented so that the tip (engaging portion 511) of the lock
member is formed with a tapered surface whose diameter gradually
decreases as followed toward the tip end, whereas the lock recess
(engaging recess 521) is formed with a tapered surface whose
diameter gradually decreases as followed toward the bottom end.
This feature serves to reduce wear of the surfaces of the lock
member and the lock recess, while enhancing the wedging effect,
because both of the lock member and the lock recess are formed with
inclined surfaces.
[0163] <5-10> A method of producing a valve timing control
apparatus for an internal combustion engine, the valve timing
control apparatus comprising: a hollow housing (HSG) adapted to
receive torque, and is formed with a shoe (11, 12, 13) at an inside
periphery of the housing (HSG), wherein the shoe (11, 12, 13)
projects inwardly in a radial direction of the housing (HSG); a
vane rotor (4) formed of an aluminum-based metal material, and
rotatably mounted in the housing (HSG), the vane rotor (4)
including: a rotor (40); a plurality of vanes (41, 42, 43)
projecting outwardly with respect to the rotor (40), and defining
at least one working fluid chamber (advance chamber A1, A2 or A3,
or retard chamber R1, R2 or R3) together with the shoe (11, 12,
13), wherein the working fluid chamber (A1, A2, A3, R1, R2, R3) is
adapted to supply and drainage of working fluid; and a cylinder
(slide hole 501) extending in an axial direction of the vane rotor
(4); a ring-shaped member (sealing member 502) formed of a material
having a higher wear resistance than anodic oxide coating, and
fixed in the cylinder (501); a lock pin (lock piston 51) including
a tip (sliding portion 512) slidably mounted in the ring-shaped
member (502), wherein the tip (engaging portion 511) is arranged to
move forward and rearward in the axial direction with respect to
the vane rotor (4) according to an operating state of the internal
combustion engine; a lock recess (engaging recess 521) provided in
an axial end portion of the housing (HSG) facing the tip of the
lock pin (51), wherein the tip of the lock pin (51) is adapted to
be inserted in the lock recess (521); and a biasing member (coil
spring 53) mounted in the cylinder (501), and arranged to bias the
lock pin (51) toward the lock recess (521), the method comprises: a
first operation of forming the cylinder (501) in the vane rotor
(4); a second operation of anodizing an entire surface of the vane
rotor (4) after the first operation; and a third operation of
press-fitting the ring-shaped member (502) into the cylinder (501)
so as to fix the ring-shaped member (502) to the cylinder (501),
after the second operation. This feature makes it possible to
easily manufacture the valve timing control apparatus according to
the features <5-1> to <5-5>.
[0164] The entire contents of Japanese Patent Application No.
2009-214723 filed Sep. 16, 2009 are incorporated herein by
reference.
[0165] Although the invention has been described above by reference
to certain embodiments of the invention, the invention is not
limited to the embodiments described above. Modifications and
variations of the embodiments described above will occur to those
skilled in the art in light of the above teachings. The scope of
the invention is defined with reference to the following
claims.
* * * * *