U.S. patent application number 11/389020 was filed with the patent office on 2006-11-23 for valve timing control apparatus and internal combustion engine.
This patent application is currently assigned to HITACHI, LTD.. Invention is credited to Seiji Suga, Tomoya Tsukada, Hidekazu Yoshida.
Application Number | 20060260577 11/389020 |
Document ID | / |
Family ID | 37311261 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260577 |
Kind Code |
A1 |
Suga; Seiji ; et
al. |
November 23, 2006 |
Valve timing control apparatus and internal combustion engine
Abstract
A valve timing control apparatus includes a driving rotary
member driven by an engine, and a driven rotary member to drive a
camshaft of the engine. The driven member is rotatable relative to
the driving rotary member. A first movable member is provided in
one of the rotary members, and arranged to move forwards and
backwards. A second movable member is provided in the other of the
rotary members, and arranged to move forwards and backwards. The
first and second movable members are arranged to limit a relative
rotation between the driving rotary member and the driven rotary
member when both the first movable member and the second movable
member are moved forwards, and to allow the relative rotation when
at least one of the first and second movable members is moved
backwards.
Inventors: |
Suga; Seiji; (Kanagawa,
JP) ; Yoshida; Hidekazu; (Kanagawa, JP) ;
Tsukada; Tomoya; (Kanagawa, JP) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
HITACHI, LTD.
|
Family ID: |
37311261 |
Appl. No.: |
11/389020 |
Filed: |
March 27, 2006 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 1/022 20130101;
F01L 2001/34473 20130101; F01L 1/024 20130101; F01L 2001/34459
20130101; F01L 2001/34469 20130101; F01L 1/3442 20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2005 |
JP |
2005-143354 |
Claims
1. A valve timing control apparatus for an internal combustion
engine, comprising: a driving rotary member adapted to be driven by
the engine; a driven rotary member arranged to rotate relative to
the driving rotary member and adapted to rotate a camshaft of the
engine; a first movable member provided in a first rotary member,
and arranged to move forwards and backwards, the first rotary
member being one of the driving rotary member and the driven rotary
member; and a second movable member provided in a second rotary
member and arranged to move forwards and backwards, the second
rotary member being the other of the driving rotary member and the
driven rotary member, the first and second movable members being
arranged to limit a relative rotation between the driving rotary
member and the driven rotary member when both the first movable
member and the second movable member are moved forwards, and to
allow the relative rotation between the driving rotary member and
the driven rotary member when at least one of the first and second
movable members is moved backwards.
2. The valve timing control apparatus as claimed in claim 1,
wherein the driving rotary member is adapted to be driven by a
crankshaft of the engine; the driven rotary member is adapted to
rotate as a unit with the camshaft; and the valve timing control
apparatus further comprises: a first bias member arranged to bias
the first movable member forwards toward the second rotary member;
a second bias member arranged to bias the second movable member
forwards toward the first rotary member; and a control section to
alter a relative rotational position of the driven rotary member
relative to the driving rotary member.
3. The valve timing control apparatus as claimed in claim 1,
wherein the valve timing control apparatus further comprises a
first bias member arranged to bias the first movable member to move
the first movable member forwards toward the second movable member,
and a second bias member arranged to bias the second movable member
to move the second movable member forwards toward the first movable
member; and wherein the first movable member and second movable
member are arranged to abut against each other to limit the
relative rotation between the driving rotary member and the driven
rotary member when the first and second movable members are
projected forwards.
4. The valve timing control apparatus as claimed in claim 3,
wherein the valve timing control apparatus further comprises an
actuating device to force at least one of the first and second
movable members backwards to allow the relative rotation between
the driving rotary member and the driven rotary member.
5. The valve timing control apparatus as claimed in claim 3,
wherein the first and second movable members are so arranged that
the first and second movable members are moved forwards to limit
the relative rotation between the driving rotary member and the
driven rotary member at the time of start of the engine, and that
at least one of the first and second movable members is moved
backwards to allow the relative rotation between the driving rotary
member and the driven rotary member after the start of the
engine.
6. The valve timing control apparatus as claimed in claim 3:
wherein the driving rotary member and the driven rotary member are
arranged to define an advance fluid pressure chamber to rotate the
driven rotary member in an advance direction relative to the
driving rotary member when an advance fluid pressure is supplied to
the advance fluid pressure chamber, and a retard fluid pressure
chamber to rotate the driven rotary member in a retard direction
relative to the driving member when a retard fluid pressure is
supplied to the retard fluid pressure chamber; and wherein at least
one of the first and second movable members is arranged to move
backwards in accordance with one of the advance fluid pressure and
the retard fluid pressure.
7. The valve timing control apparatus as claimed in claim 6,
wherein the driven rotary member includes a vane projecting
radially outwards and separating the advance fluid pressure chamber
and the retard fluid pressure chamber; and the driving rotary
member enclosing the driven rotary member and defining the advance
and retard fluid pressure chambers between the driving rotary
member and the driven rotary member.
8. The valve timing control apparatus as claimed in claim 6,
wherein at least one of the first and second movable members is
bared in one of the advance fluid pressure chamber and the retard
fluid pressure chamber to move backwards in accordance with one of
the advance fluid pressure and the retard fluid pressure.
9. The valve timing control apparatus as claimed in claim 6,
wherein at least one of the driving rotary member and the driven
rotary member is formed with a communication passage to convey one
of the advance fluid pressure and the retard fluid pressure to move
one of the first and second movable members backwards.
10. The valve timing control apparatus as claimed in claim 6,
wherein the first movable member is arranged to move backwards in
accordance with the advance fluid pressure against a biasing force
of the first bias member; and the second movable member is arranged
to move backwards in accordance with the retard fluid pressure
against a biasing force of the second bias member.
11. The valve timing control apparatus as claimed in claim 6,
wherein the first movable member is arranged to move backwards in
accordance with one of the advance fluid pressure and the retard
fluid pressure against a biasing force of the first bias member;
and the second movable member is arranged to move backwards in a
radial outward direction by a centrifugal force.
12. The valve timing control apparatus as claimed in claim 6,
wherein the first and second movable members are both exposed to a
hydraulic pressure in one of the advance fluid pressure chamber and
the retard fluid pressure chamber; and the first movable member is
arranged to be forced backwards by the hydraulic pressure whereas
the second movable member is not forced by the hydraulic
pressure.
13. The valve timing control apparatus as claimed in claim 12,
wherein the first movable member includes a forward end portion
arranged to receive the hydraulic pressure only on a forward side
to be pushed backwards by the hydraulic pressure; and the second
movable member includes a forward end portionformed with a through
hole so that the second movable member receives the hydraulic
pressure on both of a forward side and a back side of the second
movable member.
14. The valve timing control apparatus as claimed in claim 6,
wherein one of the first and second movable members includes an
outside circumferential surface and a pressure receiving outward
flange surface which projects outwards from the outside
circumferential surface and which is arranged to receive one of the
advance fluid pressure and the retard fluid pressure.
15. The valve timing control apparatus as claimed in claim 14,
wherein the second movable member includes the pressure receiving
outward flange surface which is annular; and the second rotary
member includes a portion defining an annular pressure chamber
which is formed around the second movable member, and which is
connected with one of the advance fluid pressure chamber and the
retard fluid pressure chamber.
16. The valve timing control apparatus as claimed in claim 3,
wherein one of the first and second movable members includes a
projection and the other of the first and second movable members
includes a recess to receive the projection to limit the relative
rotation between the driving and driven rotary members when the
first and second movable members are moved forwards toward each
other.
17. The valve timing control apparatus as claimed in claim 3,
wherein the first rotary member includes a support portion
supporting the first movable member and allowing the first movable
member to move radially around an axis of the camshaft; and the
second rotary member includes a support portion supporting the
second movable member and allowing the second movable member to
move radially around the axis of the camshaft.
18. The valve timing control apparatus as claimed in claim 3,
wherein the first rotary member includes a support portion
supporting the first movable member and allowing the first movable
member to move axially along an axis of the camshaft; and the
second rotary member includes a support portion supporting the
second movable member and allowing the second movable member to
move axially along the axis of the camshaft.
19. The valve timing control apparatus as claimed in claim 1,
wherein the first and second movable member are arranged to move
into a lock state to prevent the relative rotation between the
driving and driven rotary members when the driven member is at a
predetermined first rotational position relative to the driving
member, and at least one of the first and second movable members is
arranged to be moved backwards by a relative rotation of the driven
member relative to the driving member from a second rotational
position away from the predetermined first rotational position, to
the predetermined first rotational position.
20. The valve timing control apparatus as claimed in claim 19,
wherein the valve timing control apparatus further comprises a
guide portion to guide the first and second movable members into
the lock state when the driven rotary member rotates from a
rotational position away from the first rotational position, to the
first rotational position relative to the driving member with at
least one of the first and second movable members being projected
forwards.
21. The valve timing control apparatus as claimed in claim 20,
wherein the guide portion is arranged to guide the first and second
movable members into the lock state by receiving an operating force
produced when the crankshaft of the engine is rotating.
22. The valve timing control apparatus as claimed in claim 19,
wherein one of the first and second movable members is formed with
a guide portion to guide the first and second movable members into
the lock state when the driven rotary member rotates from a
rotational position away from the first rotational position, to the
first rotational position relative to the driving member.
23. The valve timing control apparatus as claimed in claim 19,
wherein the first and second movable members includes,
respectively, first and second abutting portions which are arranged
to abut against each other when the driven rotary member rotates
from a rotational position away from the first rotational position
toward the first rotational position relative to the driving member
with the first and second movable members are projected forwards;
and at least one of the first and second abutting portions includes
an inclined surface to guide the first and second movable members
into the lock position.
24. The valve timing control apparatus as claimed in claim 23,
wherein one of the first and second abutting portions includes the
inclined surface which is a tapered surface, and the other of the
first and second abutting portions includes a non-tapered surface
abutting on the tapered surface.
25. The valve timing control apparatus as claimed in claim 2,
wherein the valve timing control apparatus further comprises a
control section to alter a rotational position of the driven rotary
member relative to the driving rotary member.
26. The valve timing control apparatus as claimed in claim 25,
wherein the control section includes a hydraulic section to rotate
the driven rotary member in an advance direction relative to the
driving rotary member by supplying an advance fluid pressure to an
advance chamber, and to rotate the driven rotary member in a retard
direction relative to the driving rotary member by supplying a
retard fluid pressure to a retard chamber; the first movable member
is arranged to move backwards in accordance with the advance fluid
pressure against a biasing force of the first bias member; and the
second movable member is arranged to move backwards in accordance
with the retard fluid pressure against a biasing force of the first
bias member.
27. The valve timing control apparatus as claimed in claim 26,
wherein one of the first and second bias members is a spring so set
as to allow the movable member biased by the spring, to move
backwards when a hydraulic pressure is applied the movable member
biased by the spring, and as to prevent a backward movement of the
movable member biased by the spring when a pressure of air is
applied; and wherein the movable member biased, by the spring is
acted upon by a hydraulic pressure which is one of the advance
fluid pressure and the retard fluid pressure and which is supplied
to a corresponding one of the advance fluid chamber and the retard
fluid chamber first after the engine is started.
28. The valve timing control apparatus as claimed in claim 26,
wherein one of the first and second bias members is a greater bias
member having a biasing force greater than a biasing force of the
other of the first and second bias members; and wherein the movable
member biased by the greater bias member is acted upon by a
hydraulic pressure which is one of the advance fluid pressure and
the retard fluid pressure and which is supplied to a corresponding
one of the advance fluid chamber and the retard fluid chamber first
after the engine is started.
29. The valve timing control apparatus as claimed in claim 25,
wherein the control section includes a controller to cause the
first and second movable members to move forwards to limit the
relative rotation between the driving rotary member and the driven
rotary member at the time of start of the engine, and to cause at
least one of the first and second movable members to be moved
backwards to allow the relative rotation between the driving rotary
member and the driven rotary member after the start of the
engine.
30. The valve timing control apparatus as claimed in claim 3,
wherein the first movable member is arranged to move backwards
against a biasing force of the first bias member in accordance with
a fluid pressure produced by a fluid pump driven by the engine; and
the second movable member is arranged to move backwards against a
biasing force of the first bias member in accordance with a fluid
pressure produced by the fluid pump.
31. An internal combustion engine comprising: a crankshaft; a
camshaft; a valve timing control rotary mechanism including, a
driving rotary member driven by the crankshaft of the engine, and a
driven rotary member) which is arranged to be driven by the driving
rotary member and to drive the camshaft, and which is arranged to
rotate relative to the driving rotary member to alter a rotational
position of the driven rotary member relative to the driving rotary
member; and a lock mechanism including, a first movable member
mounted in the driven rotary member and arranged to move forwards
toward the driving rotary member and backwards away from the
driving rotary member, and a second movable member mounted in the
driving rotary member and arranged to move forwards toward the
driven rotary member and backwards away from the driven rotary
member, the second movable member being arranged to abut against
the first movable member and thereby to limit a relative rotation
between the driving rotary member and the driven rotary member when
both the first movable member and the second movable member are
moved forwards.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an internal combustion
engine equipped with a valve timing control apparatus and/or a
valve timing control apparatus for controlling a valve timing of an
internal combustion engine such as opening and closing timings of
intake or exhaust valve.
[0002] A published Japanese Patent Specification Publication No.
2000-002104 shows a valve timing control apparatus (VTC) of a vane
type including a rotary unit of a timing sprocket member and a vane
member, and a lock mechanism including a lock pin to limit a
relative rotation between the timing sprocket member and vane
member. The lock pin includes a small diameter pressure receiving
section and a large diameter pressure receiving portion.
SUMMARY OF THE INVENTION
[0003] In the valve timing control apparatus of this document, the
lock pin receives tow different hydraulic pressures at the two
different pressure receiving portions. Therefore, it is difficult
to minutely adjust the spring force of a spring biasing the lock
pin to the lock position.
[0004] According to one aspect of the present invention, a valve
timing control apparatus for an internal combustion engine,
comprises: a driving rotary member adapted to be driven by the
engine; a driven rotary member arranged to rotate relative to the
driving rotary member and adapted to rotate a camshaft of the
engine; a first movable member provided in a first rotary member,
and arranged to move forwards and backwards, the first rotary
member being one of the driving rotary member and the driven rotary
member; and a second movable member provided in a second rotary
member and arranged to move forwards and backwards, the second
rotary member being the other of the driving rotary member and the
driven rotary member. The first and second movable members are
arranged to limit a relative rotation between the driving rotary
member and the driven rotary member when both the first movable
member and the second movable member are moved forwards, and to
allow the relative rotation between the driving rotary member and
the driven rotary member when at least one of the first and second
movable members is moved backwards.
[0005] According to another aspect of the invention, an internal
combustion engine comprises: a crankshaft; a camshaft; a valve
timing control rotary mechanism including, a driving rotary member
driven by the crankshaft of the engine, and a driven rotary member
which is arranged to be driven by the driving rotary member and to
drive the camshaft, and which is arranged to rotate relative to the
driving rotary member to alter a rotational position of the driven
rotary member relative to the driving rotary member; and a lock
mechanism including, a first movable member mounted in the driven
rotary member and arranged to move forwards toward the driving
rotary member and backwards away from the driving rotary member,
and a second movable member mounted in the driving rotary member
and arranged to move forwards toward the driven rotary member and
backwards away from the driven rotary member. The second movable
member is arranged to abut against the first movable member and
thereby to limit a relative rotation between the driving rotary
member and the driven rotary member when both the first movable
member and the second movable member are moved forwards.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a sectional view taken across a line F1-F1 in FIG.
2, for showing an internal combustion engine provided with a valve
timing control system according to a first embodiment of the
present invention.
[0007] FIG. 2 is a sectional view taken across a line F2-F2 in FIG.
1, for showing the valve timing control system of FIG. 1.
[0008] FIG. 3A is a sectional view taken across the line F2-F2 in
FIG. 1, for showing the valve timing control system of FIG. 1 at
the time of a start of the engine. FIG. 3B is an enlarged view of a
part of FIG. 3A.
[0009] FIG. 4A is a sectional view taken across the line F2-F2 in
FIG. 1, for showing the valve timing control system of FIG. 1 at
the time of an idling operation of the engine. FIG. 4B is an
enlarged view of a part of FIG. 4A.
[0010] FIG. 5A is a sectional view taken across the line F2-F2 in
FIG. 1, for showing the valve timing control system of FIG. 1 at
the time of an operation in a low speed, low load region of the
engine. FIG. 5B is an enlarged view of a part of FIG. 5A.
[0011] FIG. 6A is a sectional view taken across the line F2-F2 in
FIG. 1, for showing the valve timing control system of FIG. 1 at
the time of an operation in a medium speed, medium load region of
the engine. FIG. 6B is an enlarged view of a part of FIG. 6A.
[0012] FIG. 7 is a partial cutaway view showing a valve timing
control apparatus according to a second embodiment of the present
invention.
[0013] FIG. 8 is a partial cutaway view for illustrating operation
of the valve timing control apparatus of FIG. 7 with a vane member
at a most retarded position.
[0014] FIG. 9 is a partial cutaway view for illustrating operation
of the valve timing control apparatus of FIG. 7 with the vane
member at an intermediate rotational position.
[0015] FIG. 10 is a partial cutaway view for illustrating operation
of the valve timing control apparatus of FIG. 7 with the vane
member at a most advanced position.
[0016] FIG. 11 is a schematic view showing a valve timing control
apparatus including a hydraulic circuit according to a third
embodiment of the present invention.
[0017] FIG. 12 is a partial cutaway view showing a valve timing
control apparatus according to a fourth embodiment of the present
invention.
[0018] FIG. 13 is a partial cutaway view for illustrating operation
of the valve timing control apparatus of FIG. 12 with a vane member
at the most retarded position.
[0019] FIG. 14 is a partial cutaway view for illustrating operation
of the valve timing control apparatus of FIG. 12 with the vane
member at the intermediate rotational position.
[0020] FIG. 15 is a partial cutaway view for illustrating operation
of the valve timing control apparatus of FIG. 12 with the vane
member at the most advanced position.
[0021] FIG. 16 is a sectional view taken across a line F16-F16
shown in FIG. 17, showing a valve timing control apparatus
according to a fifth embodiment of the present invention.
[0022] FIG. 17 is a sectional view taken across a line F17-F17
shown in FIG. 16.
DETAILED DESCRIPTION OF THE INVENTION
[0023] FIG. 1 shows an internal combustion engine equipped with a
valve timing control apparatus or system according to a first
embodiment of the present invention. FIG. 2 shows the valve timing
control apparatus in section taken across a line F2-F2 in FIG. 1
whereas FIG. 1 is a sectional view taken across a line F1-F1 shown
in FIG. 2. In this embodiment, the present invention is applied to
an intake valve's side. However, it is possible to apply the
invention to an exhaust valve's side.
[0024] A timing sprocket member 1 is a driving rotary member driven
through a timing chain 61 by a crankshaft 62 of the internal
combustion engine. A camshaft 2 is rotatable relative to sprocket
member 1. A vane member 3 is a driven rotary member which is fixed
at an end of camshaft 2 so that they rotate as a unit, and which is
encased rotatably in sprocket member 1. A hydraulic circuit 4 is a
component of a control section to rotate vane member 3 in a forward
rotational direction and a reverse rotational direction in sprocket
member 1 by the action of oil pressure.
[0025] Timing sprocket member 1 includes a sprocket housing 5, a
front cover 6 and a rear cover 7 which are joined together by
fastening devices which, in this example, are three small-diameter
bolts 8. Housing 5 is a hollow cylindrical member extending axially
from a front open end to a rear open end. Housing 5 includes a
toothed portion 5a formed integrally on the periphery of housing 5,
and arranged to engage in links of timing chain 61. Vane member 3
is enclosed rotatably in housing 5. Front cover 6 is in the form of
a circular disk, and arranged to close the front open end of
housing 5. Rear cover 7 is in the form of an approximately circular
disk and arranged to close the rear open end of housing 5. Front
cover 6, housing 5 and rear cover 7 are joined together to form a
housing encasing the vane member 3, by the before-mentioned bolts 8
extending in the axial direction of camshaft 2.
[0026] Housing 5 is approximately in the form of a hollow cylinder
open at both ends. Housing 5 includes a plurality of partitions 10
projecting radially inwards from an inside circumferential wall
surface of cylindrical housing 5. Projecting partitions 10 serve as
housing shoes. In this example, the number of partitions 10 is
three, and these three partitions 10 are arranged at angular
intervals of approximately 120.degree., circumferentially in the
inside circumference of housing 5. Each partition 10 extends
axially from the front open end to the rear open end of housing 5,
and has an approximately trapezoidal cross section as viewed in
FIG. 2. In this example, housing 5 includes a front end surface
which is substantially flat and which is joined with front cover 6,
and a rear end surface which is substantially flat and which is
joined with rear cover 7. Each partition 10 of this example
includes a front end surface which is flat, and flush and
continuous with the flat front end surface of housing 5, and a rear
end surface which is flat, and flush and continuous with the flat
rear end surface of housing 5. A bolt hole 11 is formed
approximately at the center of each partition 10. Each bolt hole 11
passes axially through one of partitions 10, and receives one of
the axially extending bolts 8. Each partition 10 includes an inner
end surface which is sloping in conformity with the outer shape of
a later-mentioned vane rotor (14) of vane member 3. A retaining
groove 11 extends axially in the form of cutout in the inner end
surface of each partition at a higher position. A U-shaped seal
member 12 is fit in each retaining groove 11, and urged radially
inwards by a leaf spring (not shown) fit in the retaining groove
11.
[0027] Front cover 6 includes a center bolt hole 6a having a
relatively large inside diameter; and three bolt holes 6b each
receiving one of the axially extending bolts 8. These three bolt
holes 6b are arranged around the center bolt hole 6a.
[0028] Rear cover 7 includes a center bearing hole 7a supporting
rotatably a front end portion 2a of camshaft 2; and three threaded
holes 7b into which three bolts 8 are screwed, respectively.
[0029] Camshaft 2 is rotatably supported through a cam bearing 13
on an upper portion of a cylinder head S of the engine. Camshaft 2
includes one or more cams formed integrally on the outer
circumference of camshaft 2 at predetermined positions. Each cam is
arranged to open an intake valve of the engine through a valve
lifter.
[0030] Vane member 3 of this example is a jointless single member
made of sintered alloy. Vane member 3 includes a central vane rotor
14 and a plurality of vanes 15 projecting radially outwards. In
this example, the number of vanes 15 is three, and these three
vanes 15 are arranged at angular intervals of approximately
120.degree. circumferentially around vane rotor 14. Vane rotor 14
is annular and includes a center bolt hole 14a at the center. Vane
member 3 is fixed to a front end 2a of camshaft 2 by a cam bolt 16
extending axially through the center bolt hole 14a.
[0031] The three vanes 15 are approximately rectangular, and these
vanes 15 are unequal in circumferential width L measured in the
circumferential direction around a common center axis of a rotary
mechanism composed of vane member 3 and timing sprocket 1. A first
one of the three vanes 15 is a smaller vane having a smallest
circumferential width L1, a second one is a medium vane having an
intermediate circumferential width L2 greater than L1, and a third
one is a larger vane having a largest circumferential width L3
greater than L2. These vanes are formed so that a weight balance is
attained as a whole of the vane member 3. The three vanes 15 of
vane member 3 and the three partitions 10 of timing sprocket member
1 are arranged alternately in the circumferential direction around
the center axis, as shown in FIG. 2. Namely, each vane 15 is
located circumferentially between adjacent two of the partitions
10. Each vane 15 includes a retaining groove receiving a U-shaped
seal member 16 in sliding contact with the inside cylindrical
surface of housing 5, and a leaf spring (not shown) for urging the
seal member 16 radially outward and thereby pressing the seal
member 16 to the inside cylindrical surface of housing 5.
[0032] Each vane 15 includes a first side surface facing in the
rotational direction of vane member 3 and a second side surface
facing in a rotational direction opposite to the rotational
direction. In the case of the smaller vane having the smallest
width L1, the retaining groove is formed at a middle of an outer
end of the vane. In the medium vane 15 having the intermediate
width L2, the retaining groove is formed in the outer end of the
vane at a position closer to the first side surface of the vane. In
the greater vane 15 having the greater width L3, the retaining
groove is formed in the outer end of the vane at a position closer
to the second side surface of the vane.
[0033] An advance fluid pressure chamber 17 and a retard fluid
pressure chamber 18 are formed on both sides of each vane 15.
Advance pressure chamber 17 is defined between the second side
surface of each vane 15 and the adjacent partition 10 to which the
second side surface of the vane faces. Retard pressure chamber 18
is defined between the first side surface of each vane 15 and the
adjacent partition 10 to which the first side surface of the vane
faces.
[0034] Hydraulic circuit 4 includes a first fluid pressure passage
or advance fluid pressure passage 19 leading to the advance
chambers 17 to supply and drain an advance fluid pressure of an
operating oil to and from advance chambers 17; a second fluid
pressure passage or retard fluid pressure passage 20 leading to the
retard chambers 18 to supply and drain a retard fluid pressure of
the operating oil to and from retard chambers 18, and a directional
control valve or selector valve 23 connecting the advance pressure
passage 17 and retard pressure passage 18 selectively with a supply
passage 21 and a drain passage 22. In this example, control valve
23 is a solenoid valve. A fluid pump 25 is connected with supply
passage 21, and arranged to draw the hydraulic operating fluid or
oil from an oil pan 24 of the engine, and to force the fluid into
supply passage 21. Directional control valve 23 of this example is
a one-way type pump. Drain passage 22 is connected to oil pan 24,
and arranged to drain the fluid to oil pan 24. At least one of
directional control valve 23 and pump 25 can serve as an actuating
device for forcing one of first and second movable (lock) members
backwards, as mentioned later.
[0035] Advance fluid pressure passage 19 includes a first passage
section 19a, a second passage section 19b serving as a pressure
chamber, and three branch passages (not shown) connecting second
passage section 19b, respectively, with the three advance chambers
17. Passage section 19a extends in cylinder head S, and further
extends axially in camshaft 2, to second passage section 19b.
Second passage section 19b is formed by vane member 3, at a
position between vane rotor 14 and the front end of camshaft 2. The
three branch passages are formed in vane member 3 and extend
radially in vane member 3.
[0036] Retard fluid pressure passage 20 includes a first passage
section 20a extending in cylinder head S and axially in camshaft 2,
and a second passage section 20b formed in vane rotor 14. Second
passage section 20b is approximately L-shaped, and connected with
each retard pressure chamber 18.
[0037] Directional control valve 45 of this example is a solenoid
valve having four ports and two positions. A valve element inside
the control valve 45 is arranged to alter the connection between
the passages 19 and 20 and the supply and drain passages 21 and
22.
[0038] A controller 26 produces a control signal, and controls the
solenoid control valve 45 by sending the control signal to the
valve 45. A sensor section 63 collects input information on
operating conditions of the engine and a vehicle in which this
timing control apparatus is installed. Input information is
supplied to controller 26. The sensor section 63 of this example
includes a crank angle sensor 64 for sensing a speed of the engine,
an air flowmeter 65 for sensing an intake air quantity of the
engine, a cam angle sensor 66 and an input device 67, such as an
ignition switch or a vehicle main switch, to sense a start of the
engine. Controller 26 determines a current operating state from the
signals from crank angle sensor 64 and air flowmeter 65, and
further determines a relative rotational position between sprocket
member 1 and camshaft 2.
[0039] Vane member 3, advance and retard chambers 17 and 18 and
hydraulic circuit 4 form a varying mechanism varying the relative
rotational position between the driving rotary member such as
sprocket member 1 and the driven rotary member such as vane member
3. Sprocket member 1 and vane member 3 form a valve timing control
rotary mechanism. A control section for controlling the relative
displacement between the driving rotary member such as sprocket
member 1 and the driven rotary member such as vane member 3 may
include at least one of the hydraulic circuit 4 and controller 26.
The control section may further include the sensor section 63.
[0040] A lock mechanism is a mechanism to prevent and allow the
relative rotation between the driving rotary member that is
sprocket member 1 in this example and the driven rotary member that
is vane member 3 in this example. The lock mechanism is provided
between the sprocket member 1 and vane member 3. In this example,
the lock mechanism is formed between housing 5 and a portion of
vane rotor 14 adjacent to the smaller vane 15 having the
circumferential width L1. The lock mechanism includes a first lock
unit or mechanism 27 provided in vane rotor 14 of vane member 3 and
a second lock unit or mechanism 28 provided in housing 5 of
sprocket member 3.
[0041] First lock unit or mechanism 27 (which is a driven-side lock
unit in this example), as shown in FIGS. 1.about.3, includes a
first (or driven-side) lock member 30 which can serve as one of
first and second movable members. First lock member 30 is slidably
received in a first slide hole 29 formed in vane member 3. In this
example, first slide hole 29 is formed in a boss portion 14b formed
in vane rotor 14. Boss portion 14b is located on an advance
chamber's side of the smaller vane 15 having the smallest width L1.
As shown in FIG. 2, boss portion 14b is located circumferentially
between the smaller vane 15 and the adjacent partition 10 defining
and bounding the advance chamber 17 for the smaller vane 15. First
slide hole 29 extends radially in vane member 3, and first lock
member 30 is movable radially in the radially extending first slide
hole 29. First lock member 30 is a cup-shaped member in the form of
a hollow cylinder having one end closed. First lock member 30
includes a circumferential wall extending in a radial outward
direction of vane member 3 from an open inner end to an outer end,
and a forward end portion 30a closing the outer end of the
circumferential wall.
[0042] First lock unit 27 on the driven side further includes a
first (or driven-side) spring 31 which can serve as one of first
and second bias members. First spring 31 is disposed between vane
member 3 and first lock member 30 and arranged to bias or urge
first lock member 30 forwards toward the sprocket member 1 in a
radial outward direction which may not be an exact direction of a
radius emanating from the center axis of vane member 3. In this
example, first spring 31 is a coil spring disposed between the
inside surface of the forward end portion 30a of first lock member
30 and the bottom of first slide hole 29 formed in boss portion 14b
of vane member 3. An outer portion of first spring 31 is inserted
into the inside of first lock member 30 and enclosed by the
circumferential wall of first lock member 30.
[0043] First slide hole 29 of this example extends radially from
the bottom to an outer end opening into the advance fluid pressure
chamber 17 for the vane 15 of the smallest width L1. The depth of
first slide hole 29 is longer than the length of first lock member
30.
[0044] The forward end portion 30a of first lock member 30 is
exposed to the advance fluid pressure in the advance chamber 17, so
that the advance fluid pressure is applied to the forward end
portion 30a so as to force the first lock member 30 backwards
toward the bottom of first slide hole 29, in a radial inward
direction away from the sprocket member 1. The forward end portion
30a of first lock member 30 of this example has an outside convex
surface which is spherical or shaped like a circular arc in
section. First lock member 30 further includes an outward flange
30b formed at the inner or backward end of the circumferential wall
of first lock member 30. A hollow cylindrical stopper 35 is fixed
in the first slide hole by press fitting, and arranged to limit a
radial outward movement of first lock member 30 by abutting against
the outward flange 30b of first lock member 30, as shown in FIG.
3A. Therefore, stopper 35 and outward flange 30b determines a
forward limit position beyond which first movable member 30 can not
be moved and projected by first spring 31.
[0045] First (or driven-side) spring 31 is set at such a spring
force that first spring 31 can push the first lock member 30
forwards when the hydraulic pressure in the advance fluid pressure
chamber 17 is low without the supply of the advance fluid pressure,
and that first spring 31 is compressed by the advance fluid
pressure in the advance fluid pressure chamber 17, to allow the
first lock member 30 to be moved backwards deeper in the first
slide hole 29 toward the bottom of first slide hole 29 when the
hydraulic pressure in the advance fluid pressure chamber 17 becomes
high by receiving the supply of the advance fluid pressure.
[0046] Second lock unit or mechanism 28 (which is a driving-side
lock unit in this example), as shown in FIGS. 1.about.3, includes a
second (or driving-side) lock member 33 which can serve as the
other of the first and second movable members. Second lock member
33 is slidably received in a second slide hole 32 formed in
sprocket member 1. In this example, second slide hole 32 is formed
in a boss portion 5b formed integrally at the side of the partition
15 defining the advance chamber 17 of the vane 15 having the
smallest width L1. Boss portion 5b is located circumferentially
between the smaller vane 15 and the adjacent partition 10 defining
and bounding the advance chamber 17 for the smaller vane 15. Second
slide hole 32 extends radially in sprocket member 1, and second
lock member 33 is movable radially in the radially extending slide
hole 32. Second lock member 33 is shaped approximately like a cup,
and includes a circumferential wall extending in a radial inward
direction of sprocket member 1, from an outer end to an inner end,
and a forward end portion formed so as to close the inner end of
the circumferential wall.
[0047] Second lock unit 37 on the driving side further includes a
second (or driving-side) spring 34 which can serve as the other of
the second and first bias members. Second spring 34 is disposed
between sprocket member 1 and second lock member 33, and arranged
to bias or urge second lock member 33 forwards toward the vane
member 3 in a radial inward direction which may not be an exact
direction of a radius converging to the center axis of vane member
3. In this example, second spring 34 is a coil spring disposed
between the inside surface of the forward end portion of second
lock member 33 and the bottom of second slide hole 32 formed in
boss portion 5b of sprocket member 1. An inner portion of second
spring 34 is inserted into the inside of second lock member 33 and
enclosed by the circumferential wall of second lock member 33.
[0048] Second slide hole 32 of this example extends radially inward
from an outer open hole end to an inner open hole end. A plug or
cover member 40 closes the outer open hole end of second slide hole
32, and thereby forms the bottom of second slide hole 32. Second
spring 34 is disposed between plug member 40 and the forward end
portion of second lock member 33. Plug member 40 of this example is
a circular plate and fixed to sprocket member 1. Second slide hole
32 includes an outer large-diameter section extending from the
outer hole end closed by plug member 40, toward the inner hole end
of second slide hole 32; an inner small-diameter section extending
from the inner hole end toward the outer hole end of second slide
hole 32; and an annular step shoulder surface 32a formed between
the large-diameter section and the small-diameter section. Annular
step shoulder surface 32a faces approximately in the radial outward
direction toward the outer hole end.
[0049] Second lock member 33 includes an outer large-diameter
section slidably received in the outer large-diameter portion of
second slide hole 32; an inner small-diameter section slidably
received in the inner small-diameter section of second slide hole
32; and an annular step shoulder surface 33a formed between the
large-diameter section and the small-diameter section of second
lock member 33. The inner small-diameter section of second lock
member 33 is greater in diameter than the forward end portion 30a
of first lock member 30. Annular shoulder surface 33a faces
approximately in the radial inward direction. Annular step shoulder
surface 33a serves as a pressure receiving surface of an outward
flange.
[0050] An annular pressure chamber 33b is formed around the second
lock member 33 between the annular shoulder surface 33a and annular
shoulder surface 32a. The annular shoulder surface 33a of second
lock member 33 is arranged to receive the pressure in the annular
pressure chamber 33b. Sprocket member 1 is formed with a
communication passage 36 for introducing one of the advance fluid
pressure and the retard fluid pressure to the annular pressure
chamber 33b to apply the hydraulic pressure to second lock member
33 to move the second lock member 33 backwards. In this example,
communication passage 36 extends from a first end opening in the
retard fluid pressure chamber 18, through the vane 15, to a second
end 36a opening into the annular pressure chamber 33, as shown in
FIG. 2. Therefore, second lock member 33 is arranged to move
backwards toward the bottom of second slide hole 32 in the radial
outward direction by the application of the retard fluid pressure
introduced from the retard fluid pressure chamber 18 into the
annular pressure chamber 33b. The annular step shoulder surface 32a
faces approximately in the radial outward direction, and functions
to limit a radial inward movement of second lock member 33 by
abutting on the annular step shoulder surface 33a of second lock
member 33.
[0051] Second (or driving-side) spring 34 is set at such a spring
force that second spring 34 can push the second lock member 33
forwards when the hydraulic pressure in the retard fluid pressure
chamber 18 is low without supply of the retard fluid pressure, and
that second spring 34 is compressed by the retard fluid pressure in
the retard fluid pressure chamber 18, to allow the second lock
member 33 to be moved backwards deeper in the second slide hole 32
toward the bottom of second slide hole 32 when the hydraulic
pressure in the annular pressure chamber 33b becomes high by
receiving the supply of the retard fluid pressure. The spring force
of second spring 34 is set greater than the spring force of first
spring 31.
[0052] The forward end portion of second lock member 33 is formed
with a (lock) recess 37. On the other hand, the forward end portion
of first lock member 30 is in the form of a (lock) projection which
can engage in the recess 37 of second lock member 33. The forward
end portion of second lock member 33 includes an end wall forming
the bottom of recess 37, and separating the inside cavity of the
circumferential wall of second lock member 33 and the inside of
recess 37. This end wall is formed with a through hole 38 extending
through this end wall and thereby fluidly connecting the inside of
recess 37 and the inside of the circumferential wall or the inside
of the second slide hole 32. The inside diameter of recess 37
(which is a circular recess in this example) is set greater than
the outside diameter of the forward end portion (projection) 30a of
first lock member 30. Therefore, the forward end portion 30a of
first lock member 30 is loosely fit in recess 37 of second lock
member 33 in a lock state in which the forward end portion 30a of
first lock member 30 is received in recess 37 of second lock member
33 as shown in FIG. 2 and FIGS. 3A and 3B.
[0053] The forward end portion of second lock member 33 is further
formed with a guide surface 39 serving as guide means for guiding
first and second lock members 30 and 33 into the lock state in
which the projection (30a) of first lock member 30 is fit loosely
in the recess 37 of second lock member 33. In this example, the
guide surface 39 is in the form of an annular tapered surface or
conical surface.
[0054] In the state in which no hydraulic pressures are supplied to
the advance and retard fluid pressure chambers 17 and 18 for
example at the time of engine stoppage, the vane member 3 is set at
a predetermined (lockable) rotational position (which is the most
retarded position in this example) as shown in FIGS. 1, 2, 3A and
3B. In this state, the vane 15 having the greatest circumferential
width L3 abuts against the adjacent partition 10 of sprocket member
1 in the retard rotational direction. In this state, the vane 15 of
the medium width L2 is spaced by a minute clearance C from the
adjacent partition 10 in the retard rotational direction. The vane
15 having the medium width L2 does not abut on the adjacent
partition 10. Similarly, the vane 15 of the smallest width L1 is
spaced by a minute clearance C from the adjacent partition 10
without abutting on the partition 10. When vane member 3 is located
at this predetermined (lockable or most retarded) position relative
to sprocket member 1, the forward end portion 30a of first lock
member 30 can enter the recess 37 of second lock member 33, and the
first and second lock members 30 and 33 can shift into the lock
state.
[0055] The minute clearance C of each of these vanes 15 (of the
medium and smallest widths) is determined in accordance with the
average torque, sliding friction and the size of the vane 15. These
minute clearances C are effective for preventing adhesion of the
vanes to partitions 10 and thereby improving the response speed of
vane rotation. It is possible set a clearance for each of all the
three vanes 15 so that, in the predetermined lockable rotational
position, each of all the vanes is set apart from the corresponding
partition 10.
[0056] The thus-constructed valve timing control apparatus is
operated as follows: At the time of start of the engine, controller
26 produces the control signal, and solenoid directional control
valve 23 is set to the position to connect the supply passage 21
with second (retard) fluid passage 20 and connect the drain passage
22 with first (advance) fluid passage 19. Therefore, the fluid
pressure produced by pump 25 is supplied through second passage 20
to retard chambers 18 whereas the advance chambers 17 are held in
the low pressure state with no supply of hydraulic pressure as in
the engine stop state.
[0057] Therefore, first lock member 30 projects forwards in the
radial outward direction by the force of first spring 31 until the
forward limit position is reached by abutment of flange 30b against
the inner end of stopper 35. On the other hand, second lock member
33 projects forwards in the radial inward direction by the force of
second spring 34 until the forward limit position is reached by
abutment of flange 33a against shoulder surface 32a since the
hydraulic pressure inside the retard chambers 18 is not increased
sufficiently. Therefore, the forward end portion 30a of first lock
member 30 is engaged in the recess 37 of second lock member 33. In
this state, the outside circumferential surface of forward end
portion 30a of first lock member 30 abuts against the inner side
surface of lock recess 37 of second lock member 33, and thereby
prevent the relative rotation between vane member 3 and sprocket
member 1.
[0058] Therefore, as shown in FIG. 2 and FIGS. 3A and 3B, the wide
vane having the greatest width L3 abuts against the adjacent
partition 10 on the advance chamber's side, and the first and
second lock members 30 and 33 are put in the lock state to prevent
the relative rotation between vane member 3 and sprocket member
1
[0059] In this state, the relative rotational angle of camshaft 2
relative to timing sprocket member 1 is held on the retard side,
and the opening and closing timings of the intake valve are
controlled to the retard side. By so doing, this valve timing
control system can improve the combustion efficiency by utilizing
inertial intake air, and improve the engine cranking performance.
Moreover, the lock mechanism of first and second lock members 30
and 33 in the lock state can prevent vibrations or flapping of vane
member 3 due to alternating torque of camshaft 2 between the
positive and negative sides in the engine starting operation.
[0060] In an idling operation, the solenoid directional control
valve 23 is held in the existing state and the hydraulic pressure
in retard fluid pressure chambers 18 becomes higher. When the
hydraulic pressure in retard chambers 18 becomes higher than the
level of the alternating torque, the flange portion 33a of second
lock member is acted upon by the fluid pressure introduced into the
pressure chamber 33b through communication passage 36; and the
second lock member 33 compresses second spring 34 and moves
backwards, so that the recess 37 of second lock member 33 moves
away from the forward end portion 30a of first lock member 30, as
shown in FIGS. 4A and 4B. Thus, first and second lock members 30
and 33 are put in an unlock state allowing the relative rotation of
vane member 3. However, the hydraulic pressure in retard chambers
18 is high, and the vane member 3 is held in the most retarded
position shown in FIGS. 4A and 4B (this state is called a standby
state).
[0061] When the vehicle starts moving, and the engine operating
point enters a predetermined low speed, low load region, the
controller 26 sends the control signal and switches the directional
control valve 23 to the state connecting the supply passage 21 with
first (advance) passage 19, and the drain passage 22 with second
(retard) passage 20. Therefore, the fluid is returned from retard
chambers 18 through second passage 20 and drain passage 22 to oil
pan 24, and the hydraulic pressure in retard chambers 18 becomes
low. On the other hand, the hydraulic pressure in advance chambers
17 becomes high by the supply of the fluid pressure.
[0062] Therefore, second lock member 33 moves forwards by the force
of second spring 34 to the forward limit position determined by
abutment between flange surface 33a and step surface S32a, as shown
in FIGS. 5A and 5B. On the other hand, first lock member 30 moves
backwards by the hydraulic pressure in the advance chamber 17
against the first spring 31 into the first slide hole 29.
Therefore, vane member 3 rotates in the clockwise direction from
the rotational position shown in FIGS. 4A and 4B, to the rotational
position shown in FIGS. 5A and 5B, intermediate between the most
retarded position and the most advanced position.
[0063] When the engine operating point shifts into a medium speed,
medium load region, and the supply pressure to advance chambers 17
becomes high, the vane member 3 is further rotated in the advance
direction (that is, the clockwise direction as viewed in FIGS. 6A
and 6B) until the greater vane 15 abuts against the adjacent
partition 15 on the retard chamber's side as shown in FIG. 6A and
the most advanced position shown in FIGS. 6A and 6B is reached by
vane member 3. Therefore, camshaft 2 is rotated relative to timing
sprocket member 1 in the advance direction, and the opening and
closing timings of the intake valve are controlled to the advance
side. Therefore, the valve timing control system can decrease the
pumping loss of the engine and thereby improve the engine
output.
[0064] When the engine operating point further shifts into a high
speed region, the controller 26 switches the solenoid valve 23 to
the state connecting the supply passage 21 with second passage 20,
and the drain passage 22 with first passage 19 as in the idling
operation. By so doing, controller 26 decreases the hydraulic
pressure in advance chambers 17 and increases the hydraulic
pressure in retard chambers 18. Therefore, vane member 3 is
returned in the counterclockwise direction to the most retarded
position shown in FIG. 4A, and the camshaft 2 is rotated in the
retard direction relative to timing sprocket member 1, so that the
opening and closing timings of the intake valve are controlled to
the retard side. Thus, the valve timing control system can improve
the intake charging efficiency and improve the engine output.
[0065] In this case, first lock member 30 is projected forwards by
the force of first spring 31. However, second lock member 33 is
withdrawn backwards in second slide hole 32 by the force of the
retard fluid pressure in retard chambers 18 introduced into the
annular pressure chamber 33b through communication passage 36, as
shown in FIGS. 4A and 4B. First and second lock members 30 and 33
are out of the lock state.
[0066] In the stop state of the engine, the vane member 3 is
restored to the most retarded position shown in FIGS. 2 and 3A by
the idling operation before the stoppage of the engine. That is,
the vane member 3 returns to the most retarded position while
fluctuating by the effect of alternating torque. On the other hand,
with a decrease in the hydraulic pressure in retard chambers 18,
the second lock member 33 is projected forward until the forward
end portion 30a of first lock member 30 engages in the recess 37 of
second lock member 33.
[0067] If the engine is stopped by an engine stall without
experiencing the idling operation, the vane member 3 is rotated by
the effect of the alternating torque to the most retarded position,
and the first lock member 30 engages into the lock recess 37 of
second lock member 33 automatically.
[0068] At the same time with the engine stall, the oil pump 25 is
stopped, and stops the supply of hydraulic pressure to the advance
and retard chambers. Therefore, the first and second lock members
30 and 33 are both projected forwards by first and second springs
31 and 34, respectively. When the vane member 3 is rotated from the
position shown in FIG. 6A toward the position shown in FIG. 4A by
the action of the alternating torque, the first lock member 10
remaining in the projected position collides against the second
lock member 33 in the projected position. In this case, the forward
end portion 30a of first lock member 30 abuts against the annular
tapered guide surface 39, and moves backwards gradually by being
pushed by the guide surface 39 against the force of first spring 31
until the forward end portion 30a of first lock member 30 enters
the lock recess 37 of second lock member 37.
[0069] Therefore, at the time of a restart of the engine, the vane
member 3 is locked against rotation relative to sprocket member 1,
and the engine can be started smoothly as in the normal engine
starting operation.
[0070] By controlling the supply and drainage of the hydraulic
pressure to and from the advance and retard chambers 17 and 18 in
accordance with the engine operating conditions, this valve timing
control system can hold the vane member 3 at a desired intermediate
rotational position as shown in FIG. 5A.
[0071] Thus, in addition to the valve timing control mechanism (1,
3 etc.) capable of controlling the valve timing by controlling the
hydraulic pressures in advance and retard chambers 17 and 18; the
valve timing control system according to this embodiment has the
lock mechanism including the first and second lock members 30 and
33 which are arranged to confront each other and to move toward and
away from each; and the first and second springs 31 and 34 for
urging the first and second lock members forwards toward each
other. Therefore, it is possible to select and set the urging
forces and set loads of first and second springs 31 and 34
individually. Accordingly, it is possible to finely adjust various
conditions such as conditions for canceling the limitation on the
relative rotation between the timing sprocket member 1 and camshaft
2. Moreover, it is possible to set the areas of the pressure
receiving portions 30a and 33a of first and second lock members 30
and 33 individually. Accordingly, more minute adjustment of various
conditions is possible.
[0072] When the engine is held for a long time in the stop state,
the operating oil is drained from the advance and retard chambers
17 and 18, and air flows into advance and retard chambers 17 and
18. Therefore, when the engine is started again and the oil is
supplied selectively to the advance or retard chambers 17 or 18 by
the pump 25, the air pressure is increased in the advance or retard
chambers by the supply of the oil. By this increase of the air
pressure, one of the lock members might be moved backwards away
from the other, and the lock mechanism might be unlocked.
[0073] In this embodiment, however, the spring forces of first and
second springs 31 and 34 and the pressure receiving area of flange
surface 33a can be set individually, and hence the adjustment is
readily attainable such that the lock mechanism is not unlocked by
the pressure of air, but the lock mechanism is unlocked only by the
application of hydraulic oil pressure. By such adjustment, it is
possible to prevent undesired noises from being produced by
preventing the lock mechanism from being unlocked by the compressed
air in the advance or retard chambers.
[0074] Moreover, the flexibility of the layout is increased since
the unlocking conditions can be determined by the setting of the
spring forces of first and second springs 31 and 34 independently
from the pressure receiving area of the front end surface of first
lock member 30 and the pressure receiving area of annular flange
surface 33a of second lock member 33. j0071
[0075] Even in the case of engine stall, the guide surface 39 can
guide first and second lock members 30 and 33 reliably into the
lock state. Even if the first and second lock members 30 and 33
fail to engage with each other in a normal engine stopping, the
guide surface 39 can guide the first lock member 30 into the lock
recess 37 by pushing first lock member 30 slightly backwards when
vane member 3 fluctuates by the alternating torque produced during
an engine cranking operation.
[0076] In the illustrated embodiment, the forward end portion 30a
of first lock member 30 includes a circumferential side wall
surface which is not tapered but extends straight substantially in
parallel to the longitudinal axis of first lock member 30 along
which first lock member 30 can move forwards and backwards.
Therefore, in the lock recess 37 of second lock member 33, the
non-tapered circumferential side wall surface of the forward end
portion 30a of first lock member 30 abuts against the upright
inside side wall surface of lock recess 37 of second lock member 33
with a broader contact surface area ensuring reliable
engagement.
[0077] In this embodiment, as shown in FIGS. 4A and 4B as in the
idling operation, the lock mechanism can be unlocked by moving only
the second lock member 33 backwards by the application of hydraulic
pressure in retard chambers 18. Thus, the valve timing control
system can disengage the first and second lock members 30 and 33 in
a stable and reliable manner.
[0078] Through hole 38 is formed in the bottom wall of lock recess
37 of second lock member 33. Through this through hole 38, the
hydraulic fluid supplied to advance chambers 17 flows into the
inside of second lock member 33 when second lock member 33 moves
backwards and forwards. In this case, the through hole 38 serves as
means for producing damping effect by the throttling, and thereby
preventing flapping movement of second lock member 33.
[0079] FIGS. 7.about.10 show a valve timing control apparatus
according to a second embodiment of the present invention. In the
second embodiment, second lock member 33 is arranged to move
backwards against the spring force of second spring 34 by the
effect of a centrifugal force, instead of the hydraulic pressure in
retard chambers 18. The spring force of second spring 34 is set
smaller than a centrifugal force of a predetermined magnitude
produced in housing 5 during rotation. In this example, second
spring 34 is so set that second spring 34 starts compression by the
centrifugal force of housing 5 when the engine rotational speed
becomes equal to or higher than an idle speed of about 900 rpm.
[0080] An air release passage 41 is formed in the circumferential
wall of housing 5 of sprocket member 1. Air release passage 41
connects the annular pressure chamber 33b with the outside, and
thereby opens the inside of the annular pressure chamber 33a to the
atmosphere to allow free movement of second lock member 33 in
second slide hole 32. Therefore, second lock member 33 can compress
the second spring 34 and move smoothly backwards by receiving a
centrifugal force of a predetermined magnitude or more during
engine operation. In this embodiment, the communication passage 36
connecting the retard chamber 18 with the second slide hole 32 is
eliminated.
[0081] When the centrifugal force of housing 5 is still weak after
a start of the engine, the second lock member 33 is held projected
forwards by second spring 34, and engaged with first lock member
30.
[0082] Thereafter, when the engine speed enters an idling operation
of about 900 rpm, the centrifugal force of housing 5 increases, and
forces the second lock member 33 backwards into second slide hole
32 by compressing the second spring 34 gradually as shown in FIG.
8. Consequently, the first and second lock members 30 and 33 are
disengaged from each other, and the lock mechanism is brought to
the unlock state allowing vane member 3 to rotate. However, vane
member 3 is held at the most retarded position shown in FIG. 8 by
the continuation of supply of hydraulic pressure to retard chambers
18.
[0083] When the engine speed increases from the low speed low load
region above, 900 rpm to the medium speed medium load region, the
directional control valve 23 is switched by controller 26 to the
state to supply the hydraulic pressure to the advance chambers 17
instead of the retard chambers 18, so the hydraulic pressure in
retard chamber 18 decreases and the hydraulic pressure in advance
chambers 17 increases. Therefore, first lock member 30 moves
backwards into first slide hole 29 by the hydraulic pressure of the
advance chambers 17 acting on the forward end portion 30a, and vane
member 3 rotates in the clockwise direction as viewed in FIG. 8 or
the advance direction, from the most retarded position of FIG. 8,
to an intermediate position or to the most advanced position. Thus,
camshaft 2 is rotated in the advance direction with respect to
timing sprocket member 1, and the same effects as in the first
embodiment can be obtained.
[0084] In this state, second lock member 33 receives the
centrifugal force. However, the hydraulic pressure supplied to
advance chamber 17 is introduced to the inside of second lock
member 33 through the through hole 38. This hydraulic pressure acts
on the relatively large pressure receiving area inside second lock
member 33, and the resulting force of this pressure and the spring
force of second spring 34 becomes greater than the centrifugal
force, and pushes the second lock member 33 forwards into the
projected position as shown in FIGS. 9 and 10.
[0085] Thus, in the second embodiment, by utilizing the centrifugal
force to move second lock member 33 backwards, the lock mechanism
is simplified to the advantage of cost reduction.
[0086] FIG. 11 shows a valve timing control apparatus according to
a third embodiment of the present invention. The hydraulic circuit
4 including the solenoid direction control valve 23 is constructed
in the same manner as in the first embodiment, for supplying the
hydraulic pressure to advance chambers 17 and retard chambers 18.
In addition to this hydraulic circuit section for supplying the
hydraulic pressure selectively to the advance and retard chambers
17 and 18, the hydraulic section of the valve timing control
apparatus according to the third embodiment further includes a
hydraulic circuit section for supplying the hydraulic pressure to
the pressure chamber 33b of second slide hole 34.
[0087] On the downstream side of the oil pump 25, there is provided
a third fluid pressure passage 42 having one end opening into the
pressure chamber 33b. A second solenoid direction control (or
selector) valve 43 is arranged to connected the third pressure
passage 42 selectively with a supply passage 44 connected to the
downstream side of the oil pump 25, and a drain passage 45
connected to the oil pan 24.
[0088] With the circuit section including second control valve 43
for controlling the fluid pressure in the pressure chamber 33b
independently from the fluid pressures in the advance and retard
chambers 17 and 18, the valve timing control system according to
the third embodiment can move the second lock member 33 forwards
and backwards quickly by supplying and draining the hydraulic
pressure directly to and from the pressure chamber 33b. Thus, the
locking and unlocking operations of first and second lock members
30 and 33 are quick, and the response in the valve timing control
is improved.
[0089] FIGS. 12.about.15 show a valve timing control apparatus or
system according to a fourth embodiment of the present invention.
In the fourth embodiment, the first and second lock members 30 and
33 are in the form of a pin. In this embodiment, the first and
second lock members or lock pins 30 and 33 are identical in size
and shape. Each of first and second lock pins 30 and 33 includes a
flange or slide portion 30c or 33c formed integrally at the back
end of the pin.
[0090] Slide holes 29 and 32 are formed so that the axes of slide
holes 29 and 32 overlap each other in the circumferential direction
of vane member 3. Each slide hole 29 or 32 includes a front small
diameter section, a rear large diameter section, and a step
shoulder surface 29a or 32a formed between the small and large
diameter sections. The flange 30c or 33c of each lock pin 30 or 33
is slidably received in the rear large diameter section of the
corresponding slide hole 29 or 32. The step shoulder surface 29a or
32a of each slide hole 29 or 32 faces backwards toward the bottom
of the slide hole, and limits the forward movement of the
corresponding lock member 30 or 33 by abutting against the flange
30c or 33c of the lock pin, thereby to determine the most projected
position of the lock member.
[0091] At the most retarded position as shown in FIG. 12, the
forward portions of first and second lock pins 30 and 33 abut
against each other, and thereby the first and second lock pins 30
and 33 prevent rotation of vane member 3 in the clockwise (advance)
direction as viewed in FIG. 12. On the other hand, the vane 15
having the greatest circumferential width L3 abuts on the adjacent
partition 10. Therefore, the vane member 3 is held at the most
retarded position.
[0092] First and second springs 31 and 34 are set small relatively
in diameter. A back end portion of first spring 31 is received in a
spring retaining hole formed in the bottom of first slide hole 29.
A back end portion of second spring 34 is received in a spring
retaining hole formed in a cover member or plug member 40 closing
the back end of the second slide hole 32. In the other respects,
the third embodiment is substantially identical in construction to
the first embodiment.
[0093] In an engine starting operation, the first lock pin 30 abuts
against second lock pin 33 as shown in FIG. 12 and thereby prevents
rotation of vane member 3. In an idling operation, the hydraulic
pressure supplied from retard chambers 18 to the pressure chamber
33b is still low. Therefore, though second lock pin 33 is retracted
backwards slightly as shown in FIG. 13, the first and second lock
pins 30 and 33 are held engaged.
[0094] When the engine speed is further increased, and the engine
operating point enters the low speed low load region, the solenoid
valve 23 is switched to the state supplying the hydraulic pressure
to advance chambers 17, and the pressure in advance chambers 17
become high. Therefore, as shown in FIG. 14, first lock pin 30 is
retracted backwards in first slide hole 29 by the hydraulic
pressure acting on the forward end of first lock pin 30, and
thereby disengaged from second lock pin 33; and the vane member 3
is rotated in the advance (clockwise) direction by the hydraulic
pressure in advance chambers 17. In a medium speed high load
region, for example, the hydraulic pressure in advance chambers 17
is further increased, and the vane member 3 is held at the most
advanced position at which the vane 15 having the greatest
circumferential width L3 abuts on the adjacent partition 10.
[0095] In the high speed high load region, the operating oil is
drained from advance chambers 17 and the vane member 3 is rotated
in the retard (counterclockwise) direction. However, immediately
after this switching operation, the hydraulic pressure is supplied
to retard chambers 18 and the hydraulic pressure in advance
chambers 17 is not abruptly decreased. Therefore, first lock pin 30
is not projected so much, and second lock pin 33 is slightly
retracted, so that the vane member 3 can rotate to the most
retarded position without interference between first and second
lock pins 30 and 33.
[0096] In the fourth embodiment, the first and second lock members
30 and 33 are identical to each other, so that the manufacturing
cost can be reduced. The valve timing control apparatus according
to the fourth embodiment can improve the fuel consumption and other
engine performance as in the preceding embodiments.
[0097] FIGS. 16 and 17 show a valve timing control apparatus or
system according to a fifth embodiment of the present invention. In
the fifth embodiment, first and second lock members 30 and 33 are
arranged in the axial direction instead of the radial
direction.
[0098] An axial first slide hole 29 is formed in the vane 15 having
a larger circumferential width. First slide hole 29 extends in the
axial direction along the center axis of vane member 3. First slide
hole 29 is a stepped hole having a larger section and a smaller
section having a cross sectional size smaller than the cross
sectional size of the larger section. An axial second slide hole 32
is formed in a thick wall portion of rear plate 7 of timing
sprocket member 1 at a position confronting the first slide hole
when vane member 3 is at a predetermined (most retarded) rotational
position. Second slide hole 32 extends in the axial direction along
the common center axis of vane member 3 and timing sprocket member
1. A back end of second slide hole 32 is closed by a cover or plug
member 40. Cover member 40 is shaped like a thin circular disk, and
fixed to rear plate 7 so as to form the bottom of second slide hole
32. An air release hole is formed approximately at the center of
cover member 40 to ensure smooth movement of second lock member 33
in second slide hole 32.
[0099] First lock member 30 is a cup-shaped member including a
cylindrical wall extending from a backward end to a forward end
toward rear cover 7, and a forward end portion 30a closing the
forward end of the cylindrical wall. Second lock member 33 is a
cup-shaped member including a cylindrical wall extending from a
backward end to a forward end toward front cover 6, and a forward
end portion closing the forward end of the cylindrical wall. First
lock member 30 is slidably received in first slide hole 29 so that
first lock member 30 can move forwards and backwards in the axial
direction. Second lock member 33 is slidably received in second
slide hole 32 so that second lock member 33 can move forwards and
backwards in the axial direction.
[0100] The forward end portion 30a of first lock member 30 is
formed with a (lock) projection which is a cylindrical projection
projected axially, in this example. First lock member 30 further
includes an outward flange formed integrally at the backward end
and arranged to abut on a step 29c formed in first slide hole 29 to
limit the forward movement of first lock member 30.
[0101] The forward end portion of second lock member 33 is formed
with a (lock) recess 37 in which the projection formed in forward
end portion 30a of first lock member 30 can be fit loosely. Recess
37 of FIG. 16 is axially depressed. The outside surface of
cylindrical wall of second lock member 33 is stepped, and there is
formed an annular step shoulder surface 33 receiving the hydraulic
pressure in an annular pressure chamber 33b formed around second
lock member 33. The pressure receiving area of the annular step
shoulder surface 33 is set at an appropriate value.
[0102] A communication passage 36 extends from one of retard
chambers 18 to the annular pressure chamber 33b to supply the
hydraulic pressure from the retard chamber 18 to pressure chamber
33b. In the other respects, the fifth embodiment is substantially
identical to the first embodiment.
[0103] Therefore, the fifth embodiment can provide the same effects
as the first embodiment. In an engine starting operation, the
hydraulic pressure in annular pressure chamber 33b is not increased
yet, and the second lock member 33 is held engaged with first lock
member 30. In an idling operation, the hydraulic pressure supplied
in pressure chamber 33b is slightly increased, and second lock
member 33 is retracted backwards and disengaged from first lock
member. However, the hydraulic pressure is still insufficient, and
the vane member 3 is held at the most retarded position.
[0104] When, for example, the engine speed is increased from the
low speed low load region to the medium speed high load region, the
solenoid valve 23 is switched to the state supplying the hydraulic
pressure to advance chambers 17, and the vane member 3 is rotated
in the advance (clockwise) direction by the hydraulic pressure in
advance chambers 17. Thus, the valve timing control system can
improve the engine performance sufficiently as in the first
embodiment.
[0105] In the fifth embodiment, first and second lock members 30
and 33 are arranged axially along the axis of camshaft 2.
Therefore, the lock mechanism receives no influence of the
centrifugal force of housing 5, and the first and second lock
members 30 and 33 can be moved only by the hydraulic pressures.
Thus, the fifth embodiment can improve the control response to
control the relative rotation between timing sprocket member 1 and
camshaft 2.
[0106] The present invention is not limited to the illustrated
embodiments. Various variations and modifications are possible. For
example, instead of the timing sprocket member 1, the driving
member may be a timing pulley driven through a timing belt of
rubber. This arrangement is advantageous for reduction of
vibrations and noises.
[0107] Moreover, the driving member may be a gear member driven by
a gear mechanism transmitting motion by a combination of two or
more gears. In this case, the driving force can be transmitted
securely. Furthermore, as the gear mechanism, it is possible to
employ scissors gear to reduce backlash noises.
[0108] The valve timing control actuator may be a helical type VTC
actuator, instead of the vane type VTC actuator. In the helical
type, the relative rotational phase is shifted with axial movement
of a tubular toothed member.
[0109] The valve timing control actuator may be electric or
electromagnetic, instead of the hydraulic actuator. In this case,
the relative rotational phase between the driving and driven
members is altered by an electric device such as an electric motor
or an electromagnetic brake.
[0110] It is sufficient to provide only one pair of the advance
fluid pressure chamber and retard fluid pressure chamber. The
number of pairs of the advance and retard chambers may be one, or
may be two, three or four or more. When the number of pairs is
increased especially in the case of the vane type VTC actuator, the
pressure receiving areas are increased, and the response
characteristic of the VTC actuator is improved.
[0111] It is not always necessary to dispose the first and second
movable members in one of the advance and retard fluid pressure
chambers. The first and second movable members may be placed at a
position separate from the advance and retard chambers.
[0112] The first and second movable members may be placed at
various portions of the driving and driven rotary members which are
arranged to rotate relative to each other. The first and second
movable members need not be placed between a member, such as a
sprocket, driven directly by a crankshaft, and a member, such as a
vane member, driving directly a camshaft. At least one of the first
and second movable members may be mounted in a member (such as the
above-mentioned tubular toothed member of the helical VTC actuator)
interposed between the member directly driven by the crankshaft and
the member directly driving the camshaft.
[0113] The first and second movable member may be shaped in various
forms. Either or both of the first and second movable members may
be in the form of a cylindrical pin, a polygonal pin polygonal in
cross section, a ring-shaped member, or a plate-shaped member, or
in the form of a lever.
[0114] Instead of the engagement between the (lock) recess 37 and
the (lock) projection like tenon and mortise, it is possible to
employ various forms for abutting portions of first and second
movable members. When the relative rotation of the rotary mechanism
of driving rotary member and driven rotary member is limited within
a predetermined range, it is possible to arrange the first and
second movable members to prevent the relative rotation between the
driving and driven members only in one direction by abutment
between the first and second movable members in the circumferential
direction, and to prevent the relative rotation in the opposite
direction by the rotary mechanism of the driving and driven
members.
[0115] Instead of a coil spring, it is possible to employ, as at
least one of the first and second bias members, a leaf spring or a
disk spring. The directions of forward and backward movement of the
first and second movable members are not limited to the radial
direction and the axial direction. It is possible to employ various
directions as the directions of the first and second movable
members.
[0116] Instead of the tapered or conical surface around the recess
37, it is possible to employ various forms of the guide portion for
guiding the first and second movable member into engagement or into
the lock state. For example, a tapered surface may be formed around
the projection of one movable member to be engaged in the recess of
the other movable member. Moreover, it is possible to form a
tapered surface only in a part of the circumference of the recess
37. In this case, the movable member formed with the recess is
arranged so that the rotation about its own axis is limited or
prevented. Furthermore, it is possible to employ, as the guide
portion or guide means, a mechanism using one or more links, or a
cam mechanism or other shaped portion or device for moving at least
one of the first and second movable members backwards by using a
relative rotation between the driving and driven rotary members, or
translating a relative rotation between the driving and driven
rotary members into a linear motion of at least one of the first
and second movable members.
[0117] One of the first and second movable members is a first
released member which is first moved backwards first by the
application of a hydraulic pressure when the engine is started. In
the first embodiment, for example, the second lock member is the
first released member which is first acted upon by the application
of the retard fluid pressure after the engine is started. At least
the bias member (such as second spring 34) of the first release
member (such as second lock member 32) is so set that the bias
member can hold the first release member in the projected position
to prevent the relative rotation between the driving rotary member
and driven rotary member when an air pressure is applied to the
first release member and that the bias member allows the first
release member to be moved backwards when a hydraulic pressure is
applied. Moreover, the bias member (such as second spring 34) of
the first release member (such as second lock member 32) is so set
that the biasing force or spring force of the first release member
is greater than that of the other bias member.
[0118] This application is based on a prior Japanese Patent
Application No. 2005-143354 filed on May 17, 2005. The entire
contents of this Japanese Patent Application No. 2005-143354 are
hereby incorporated by reference.
[0119] 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.
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