U.S. patent application number 11/290532 was filed with the patent office on 2006-06-15 for valve timing control apparatus for internal combustion engine.
This patent application is currently assigned to Aisin Seiki Kabushiki Kaisha. Invention is credited to Katsuhiko Eguchi, Yoji Kanada.
Application Number | 20060124094 11/290532 |
Document ID | / |
Family ID | 36097230 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060124094 |
Kind Code |
A1 |
Kanada; Yoji ; et
al. |
June 15, 2006 |
Valve timing control apparatus for internal combustion engine
Abstract
A valve timing control apparatus includes a driving side
rotational member synchronously rotated with a crankshaft, a driven
side rotational member provided coaxially with the driving side
rotational member and synchronously rotated with a camshaft, a
fluid pressure chamber being separated into an advanced angle
chamber and a retarded angle chamber, a phase control apparatus
controlling an operation fluid to be supplied to and discharged
from one of, or both of the advanced angle chamber and the retarded
angle chamber, for displacing a relative rotational phase between
the driving side rotational member and the driven side rotational
member within a range from a most advanced angle phase to a most
retarded angle phase, a locking mechanism restraining the relative
rotational phase at a lock phase between the most advanced angle
phase and the most retarded angle phase.
Inventors: |
Kanada; Yoji; (Gamagori-shi,
JP) ; Eguchi; Katsuhiko; (Kariya-shi, JP) |
Correspondence
Address: |
REED SMITH LLP
Suite 1400
3110 Fairview Park Drive
Falls Church
VA
22042
US
|
Assignee: |
Aisin Seiki Kabushiki
Kaisha
|
Family ID: |
36097230 |
Appl. No.: |
11/290532 |
Filed: |
December 1, 2005 |
Current U.S.
Class: |
123/90.17 ;
123/90.15 |
Current CPC
Class: |
F01L 2001/34426
20130101; F01L 2001/34463 20130101; F01L 2001/34453 20130101; F01L
1/3442 20130101; F01L 2001/34483 20130101; F01L 2001/34466
20130101; F01L 2001/34476 20130101; F01L 2001/34473 20130101; F01L
2001/34456 20130101 |
Class at
Publication: |
123/090.17 ;
123/090.15 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2004 |
JP |
2004-361972 |
Claims
1. A valve timing control apparatus comprising: a driving side
rotational member synchronously rotated with a crankshaft; a driven
side rotational member provided coaxially with the driving side
rotational member and synchronously rotated with a camshaft; a
fluid pressure chamber formed on at least one of the driving side
rotational member and the driven side rotational member, the fluid
pressure chamber being separated into an advanced angle chamber and
a retarded angle chamber; a phase control apparatus controlling an
operation fluid to be supplied to and discharged from one of, or
both of the advanced angle chamber and the retarded angle chamber,
for displacing a relative rotational phase between the driving side
rotational member and the driven side rotational member within a
range from a most advanced angle phase to a most retarded angle
phase; and a locking mechanism restraining the relative rotational
phase between the driving side rotational member and the driven
side rotational member at a lock phase between the most advanced
angle phase and the most retarded angle phase, wherein during
cranking, the relative rotational phase is displaced relatively in
one of an advanced angle direction and a retarded angle direction
while oscillating, and wherein the phase control apparatus performs
a starting point control for discharging the operation fluid from
the advanced angle chamber and the retarded angle chamber during a
predetermined period of time after a starting of cranking, and
supplying the operation fluid into one of the advanced angle
chamber and the retarded angle chamber for displacing the relative
rotational phase to the other of the advanced angle direction and
the retarded angle direction after the predetermined period of time
is elapsed.
2. The valve timing control apparatus according to claim 1, wherein
the predetermined period of time is set, in a condition where
cranking is started with the fluid pressure chamber filled with the
operation fluid, longer than, or equal to, a time required for a
center of an oscillation of the relative rotational phase during
cranking to be displaced to the lock phase from one of the most
advanced angle phase and the most retarded angle phase positioned
in the other of the advanced angle direction and the retarded angle
direction.
3. The valve timing control apparatus according to claim 1, wherein
the phase control apparatus discontinues the starting point control
when the internal combustion engine is started, and starts a
control after an engine starting.
4. The valve timing control apparatus according to claim 1, wherein
The phase control apparatus includes: a biasing mechanism set for
displacing the relative rotational phase between the driving side
rotational member and the driven side rotational member to the
advanced angle direction, wherein by means of the biasing mechanism
and a pressure of the operation fluid supplied into one of the
advanced angle chamber and the retarded angle chamber, the phase
control apparatus displaces the relative rotational phase
relatively in one of the advanced angle direction and the retarded
angle direction while oscillating during cranking.
Description
[0001] This application is based on and claims priority under 35
U.S.C. .sctn.119 to Japanese Patent Application 2004-361972, filed
on Dec. 14, 2004, the entire content of which is incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a valve timing control apparatus
for controlling an opening and closing timing of valves of an
internal combustion engine for a vehicle engine, or the like.
BACKGROUND
[0003] A valve timing control apparatus is known which
appropriately adjusts an opening and closing timing of a valve, and
achieves optimal driving conditions by means of a displacement of a
relative rotational phase between a driving side rotational member,
which rotates in synchronization with a crankshaft, and a driven
side rotational member, which rotates in synchronization with a
camshaft. A known valve timing control apparatus is disclosed in
JP2002-097912A (see pp. 2-3 FIGS. 2-5).
[0004] The disclosed valve timing control apparatus includes a
housing member synchronously rotatable with the crankshaft, a rotor
member synchronously rotatable with the camshaft, a relative
rotation controlling mechanism actuated in response to supply and
discharge of operation fluid, a fluid pressure circuit for
controlling the operation fluid to be supplied to and discharged
from an advanced angle fluid chamber, a retarded angle fluid
chamber, and the relative rotation controlling mechanism, and an
auxiliary controlling mechanism actuated in response to the
operation fluid supplied to and discharged from the fluid pressure
circuit. The rotor is relatively rotatably assembled on a shoe
portion provided at the housing member and forms the advanced angle
fluid chamber and the retarded angle fluid chamber at a vane
portion in the housing member. The relative rotation controlling
mechanism allows a relative rotation of the housing member and the
rotor member under an unlock state, and restricts the relative
rotation of the housing member and the rotor member at a lock phase
between a most advanced angle phase and a most retarded angle phase
under a lock state. The auxiliary controlling mechanism allows the
relative rotation of the housing member and the rotor member under
the unlock state, and restricts the relative rotation of the rotor
member only to the retarded angle side (or to the advanced angle
side) relative to the housing member at a set phase between the
most retarded angle phase (or the most advanced angle phase) and
the lock phase under the lock state.
[0005] According to this known valve timing control apparatus, when
the relative rotational phase between the housing member and the
rotor member is displaced from the most retarded angle phase (or
the most advanced angle phase) to the set phase by means of a
torque fluctuation applied to the camshaft, the auxiliary
controlling mechanism comes into the lock state. Then, the
auxiliary controlling mechanism restricts the relative rotation of
the rotor member only to the retarded angle side (or to the
advanced angle side) relative to the housing member, and an initial
value of the relative rotational phase is held at the set phase.
Accordingly, thereafter, the relative rotational phase between the
housing member and the rotor member is displaced to the lock phase
by means of the torque fluctuation applied to the camshaft, and the
relative rotation of the housing member and the rotor member is
restricted at the lock phase by means of the relative rotation
controlling mechanism. Thereby, the time required for the relative
rotation of the housing member and the rotor member to be
restricted at the lock phase from the point of the internal
combustion engine starting by means of the relative rotation
controlling mechanism can be reduced. Further, an occurrence of a
hitting sound and difficulties associated with a startability of
the internal combustion engine can be reduced.
[0006] The valve timing control apparatus disclosed in
JP2002-097912A, oscillates the relative rotational phase to
displace its posture to the set phase by means of the torque
fluctuation applied to the camshaft, and then makes the auxiliary
controlling mechanism into the lock state. Therefore, depending on,
for example, conditions of the operation fluid in the valve timing
control apparatus, or types of the operation fluid at the time of
the displacement of the relative rotational phase, a sufficient
oscillation of the relative rotational phase cannot be ensured
because of a resistance of the operation fluid, and the valve
timing control apparatus may occasionally fail to displace the
relative rotational phase to the set phase. For example, shortly
after a stop of the internal combustion engine, when the advanced
angle fluid chamber, the retarded angle fluid chamber, and the
fluid pressure circuit communicating therewith are filled with the
operation fluid, or when a temperature of the operation fluid is at
a lower degree, the resistance of the operation fluid at the time
of the oscillation of the relative rotational phase is increased.
On this occasion, the valve timing control apparatus may
occasionally fail to displace the relative rotational phase to the
set phase. In such a case, the relative rotation controlling
mechanism might fail to restrain the relative rotational phase at
the lock phase, and a startability of the internal combustion
engine may occasionally be adversely affected.
[0007] A need thus exists for a valve timing control apparatus,
which, notwithstanding the conditions of the operation fluid in the
valve timing control apparatus, or types of the operation fluid,
certainly restrains the relative rotational phase between the
driving side rotational member and the driven side rotational
member at the lock phase, and improves the startability of the
internal combustion engine.
SUMMARY OF THE INVENTION
[0008] According to an aspect of the present invention, a valve
timing control apparatus includes a driving side rotational member
synchronously rotated with a crankshaft, a driven side rotational
member provided coaxially with the driving side rotational member
and synchronously rotated with a camshaft, a fluid pressure chamber
formed on at least one of the driving side rotational member and
the driven side rotational member, the fluid pressure chamber being
separated into an advanced angle chamber and a retarded angle
chamber, a phase control apparatus controlling an operation fluid
to be supplied to and discharged from one of, or both of the
advanced angle chamber and the retarded angle chamber, for
displacing a relative rotational phase between the driving side
rotational member and the driven side rotational member within a
range from a most advanced angle phase to a most retarded angle
phase, a locking mechanism restraining the relative rotational
phase between the driving side rotational member and the driven
side rotational member at a lock phase between the most advanced
angle phase and the most retarded angle phase. During cranking, the
relative rotational phase is displaced relatively in one of an
advanced angle direction and a retarded angle direction while
oscillating. The phase control apparatus performs a starting point
control for draining the operation fluid from the advanced angle
chamber and the retarded angle chamber during a predetermined
period of time after a starting of cranking, and supplying the
operation fluid into one of the advanced angle chamber and the
retarded angle chamber for displacing the relative rotational phase
to the other of the advanced angle direction and the retarded angle
direction after the predetermined period of time is elapsed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The foregoing and additional features and characteristics of
the present invention will become more apparent from the following
detailed description considered with reference to the accompanying
drawings, wherein:
[0010] FIG. 1 is a sectional view of a valve timing control
apparatus according to an embodiment of the present invention.
[0011] FIG. 2 is a sectional view of the valve timing control
apparatus illustrating a condition where a relative rotational
phase is at a lock phase and a locking mechanism is at a lock
state, the sectional view which is taken along line II-II of FIG.
1.
[0012] FIG. 3 is a sectional view of the valve timing control
apparatus illustrating a condition where the relative rotational
phase is at the lock phase and the locking mechanism is at an
unlock state of the sectional view which is taken along line
III-III of FIG. 1.
[0013] FIG. 4 is a sectional view of the valve timing control
apparatus illustrating a condition where the relative rotational
phase is at a restriction phase, the sectional view which is taken
along line IV-IV of FIG. 1.
[0014] FIG. 5 is a sectional view of the valve timing control
apparatus illustrating a condition where the relative rotational
phase is at a most retarded angle phase, the sectional view which
is taken along line V-V of FIG. 1.
[0015] FIG. 6 is a sectional view of the valve timing control
apparatus illustrating a condition where the relative rotational
phase is at a most advanced angle phase, the sectional view which
is taken along line VI-VI of FIG. 1.
[0016] FIG. 7 is a view for explaining a relation between a stroke
degree of a spool and operating conditions of a control valve
according to the embodiment of the present invention.
[0017] FIG. 8 is a block diagram illustrating an electrical
connection structure of a control unit according to the embodiment
of the present invention.
[0018] FIG. 9 is a flowchart illustrating an operation control of
the valve timing control apparatus at a starting of an engine.
[0019] FIG. 10 is a timing chart illustrating an operation of the
valve timing control apparatus in a condition where the relative
rotational phase at a starting of cranking is at the most advanced
angle phase.
[0020] FIG. 11 is a timing chart illustrating an operation of the
valve timing control apparatus in a condition where the relative
rotational phase at the starting of cranking is at the most
retarded angle phase.
DETAILED DESCRIPTION
[0021] An embodiment of the present invention will be explained
hereinbelow with reference to the attached drawings.
[0022] As illustrated in FIGS. 1-3, a valve timing control
apparatus according to the embodiment of the present invention
includes an outer rotor 2 (i.e., a driving side rotational member),
and an inner rotor 1 (i.e., a driven side rotational member). The
outer rotor 2 rotates in synchronization with a crankshaft of an
engine (not shown), and the inner rotor 1 is coaxially provided
with the outer rotor 2 and rotates in synchronization with a
camshaft 3.
[0023] The inner rotor 1 is integrally assembled at an end portion
of the camshaft 3, which configures a rotational shaft of a cam for
controlling an opening and closing timing of an intake valve and an
exhaust valve of the engine. The camshaft 3 is rotatably assembled
to a cylinder head of the engine.
[0024] Relative to the inner rotor 1, the outer rotor 2 is
externally attached, and relatively rotatable within a
predetermined relative rotational phase range. The outer rotor 2 is
integrally provided with, at a side in which the camshaft 3 is
connected, a rear plate 23, and is integrally provided with, at the
other side, a front plate 22. Further, the outer rotor 2 is
integrally provided with, at an outer circumference, a timing
sprocket 20. A transmission member 24 such as a timing chain, a
timing belt, or the like, is hung across the timing sprocket 20 and
a sprocket assembled to the crankshaft of the engine.
[0025] When the crankshaft of the engine is rotated, a rotational
force is transmitted to the timing sprocket 20 through the
transmission member 24, then the outer rotor 2 rotates in a
rotational direction S as illustrated in FIG. 2. Consequently, the
inner rotor 1 rotates in the rotational direction S, then the
camshaft 3 rotates, and then the cam provided at the camshaft 3
pushes down the intake valve or the exhaust valve of the engine to
open the valve.
[0026] As illustrated in FIG. 2, the outer rotor 2 is arranged with
plural protruding portions 4 along a rotational direction in such a
manner to separate from each other. Each protruding portion 4
(i.e., a shoe) is protruded in a radial direction. Between each
adjacent protruding portion 4 of the outer rotor 2, a fluid
pressure chamber 40, defined by the outer rotor 2 and the inner
rotor 1, is provided. According to the embodiment of the present
invention, four fluid pressure chambers 40 are provided.
[0027] The inner rotor 1 is formed with, at a part of an outer
circumferential portion facing the fluid pressure chamber 40, a
vane groove 41. A vane 5, which separates the fluid pressure
chamber 40 into an advanced angle chamber 43 and a retarded angle
chamber 42 in a relative rotational direction (a direction of
arrows S1 and S2 in FIG. 2), is slidably inserted into the vane
groove 41 in a radial direction. As illustrated in FIG. 1, the vane
5 is biased toward an inner wall surface w of the fluid pressure
chamber 40 by means of a spring 51 provided at a side of an inner
diameter of the vane 5.
[0028] The advanced angle chamber 43 of the fluid pressure chamber
40 is communicated with an advanced angle passage 11 formed in the
inner rotor 1, the retarded angle chamber 42 is communicated with a
retarded angle passage 10 formed in the inner rotor 1, and the both
of the advanced and retarded angle passages 11 and 10 are connected
to a fluid pressure circuit 7. By supplying or discharging the
operation fluid through the fluid pressure circuit 7 relative to
one of, or both of the advanced angle chamber 43 and the retarded
angle chamber 42, a biasing force is generated. The biasing force
displaces a relative rotational phase between the inner rotor 1 and
the outer rotor 2 within a range from a most advanced angle phase
to a most retarded angle phase, or holds the relative rotational
phase between the inner rotor 1 and the outer rotor 2 at a given
phase.
[0029] As illustrated in FIG. 1, between the inner rotor 1 and the
front plate 22 of the outer rotor 2, a torsion spring 27 serving as
a biasing mechanism is provided that biases the relative rotational
phase between the inner rotor 1 and the outer rotor 2 in the
advanced angle direction. More particularly, the torsion spring 27
applies a torque, which normally biases the inner rotor 1 and the
outer rotor 2, in a direction in which the vane 5 is displaced in
the advanced angle direction (a direction of S2 in FIG. 2). A
torque setting of the torsion spring 27 is set so as to displace
the relative rotational phase between the outer rotor 2 and the
inner rotor 1 (hereinafter, the relative rotational phase)
relatively in the retarded angle direction while oscillating during
cranking for starting the engine. More particularly, according to
the embodiment of the present invention, a torque fluctuation
applied to the camshaft 3 during cranking is large in the retarded
angle direction, and is small in the advanced angle direction.
Therefore, by means of the torque fluctuation, the relative
rotational phase is displaced relatively in the retarded angle
direction while oscillating. The torque setting of the torsion
spring 27 is set for biasing the relative rotational phase in the
advanced angle direction within a range in which the displacement
of the relative rotation in the retarded angle direction is not
interrupted. The torque fluctuation, which is applied to the
camshaft 3 during cranking, is generated by means of, for example,
a resistance of a valve spring in a condition where the cam
provided at the camshaft 3 performs an opening and closing
operation of the engine valve against the biasing force of the
valve spring.
[0030] Further, between the inner rotor 1 and the outer rotor 2,
the locking mechanism 6 is provided that is capable of restraining
the relative rotation of the inner rotor 1 and the outer rotor 2 in
a condition where the relative rotational phase is at a
predetermined lock phase (a phase illustrated in FIG. 2) between
the most advanced angle phase and the most retarded angle phase.
The locking mechanism 6 includes a retarded angle locking portion
6A and an advanced angle locking portion 6B both of which are
provided at the outer rotor 2. The locking mechanism 6 further
includes a recess formed locking chamber 62 provided at a part of
the outer circumference portion of the inner rotor 1. The locking
chamber 62 communicates with a locking passage 63 formed in the
inner rotor 1, and the locking passage 63 is connected to the fluid
pressure circuit 7.
[0031] Each retarded angle locking portion 6A and the advanced
angle locking portion 6B includes a locking member 60, which is
provided at the outer rotor 2 and slidable in the radial direction,
and a spring 61, which biases the locking member 60 inwardly in the
radial direction. According to various usages, the locking member
60 may adopt various shapes such as a plate shape, and a pin
shape.
[0032] The retarded angle locking portion 6A prevents the inner
rotor 1 from relatively rotating in the retarded angle direction
relative to the outer rotor 2 by protruding the locking member 60
into the locking chamber 62. In contrast, the advanced angle
locking portion 6B prevents the inner rotor 1 from relatively
rotating in the advanced angle direction relative to the outer
rotor 2 by protruding the locking member 60 into the locking
chamber 62. More particularly, by protruding one of the retarded
angle locking portion 6A and the advanced angle locking portion 6B
into the locking chamber 62, a displacement of the relative
rotational phase into one of the retarded angle direction and the
advanced angle direction is restricted, and the displacement of the
relative rotational phase into the other of the retarded angle
direction and the advanced angle direction is allowed. On this
occasion, a protruding operation of the locking member 60 into the
locking chamber 62 is performed, by means of a biasing force of the
spring 61, in a drain condition where the operation fluid is not
supplied into the locking chamber 62.
[0033] According to the embodiment of the present invention, the
locking chamber 62 is provided with, at a retarded angle side, a
restricting step portion 64. The restricting step portion 64 is
formed stepwise on an outer circumferential surface of the inner
rotor 1. The restricting step portion 64 is provided at a wall
portion extending in the radial direction at the retarded angle
side of the locking chamber 62 into which the retarded angle
locking portion 6A is insertable. According to the embodiment of
the present invention, a restriction phase is defined between the
most retarded angle phase (a phase illustrated in FIG. 5) and the
lock phase (phases illustrated in FIGS. 2-3). When the retarded
angle locking portion 6A of the locking mechanism 6 is protruded
and engaged with the restricting step portion 64 as illustrated in
FIG. 4, the restricting step portion 64 restricts the displacement
of the relative rotational phase to the retarded angle side from
the restriction phase, and allows the displacement of the relative
rotational phase to the advanced angle side.
[0034] As illustrated in FIG. 2, in a condition where the locking
member 60 of the retarded angle locking portion 6A and the locking
member 60 of the advanced angle locking portion 6B are protruded
into the locking chamber 62, a lock state is achieved for
restraining the displacement of the relative rotational phase
between the inner rotor 1 and the outer rotor 2 at the
predetermined lock phase, which is set between the most advanced
angle phase (a phase illustrated in FIG. 6) and the most retarded
angle phase. Regarding a valve opening and closing timing of the
engine, the lock phase is set for obtaining a smooth startability
of the engine.
[0035] The locking member 60 is retracted from the locking chamber
62 by supplying the operation fluid into the locking chamber 62
through the locking passage 63. More particularly, when the locking
chamber 62 is filled with the operation fluid, because of a
pressure of the operation fluid in the locking chamber 62, a
biasing force, which is applied in a direction in which the locking
member 60 is housed in the outer rotor 2 (a direction in which the
locking member 60 is retracted from the locking chamber 62) is
generated. In a condition where the biasing force generated by the
pressure of the operation fluid becomes greater degree than the
biasing force of the spring 61, which is applied in a direction in
which the locking member 60 is protruded into the locking chamber
62, the locking member 60 is retracted from the locking chamber 62
as illustrated in FIG. 3. Accordingly, the locking mechanism 6
achieves an unlock state, which allows the displacement of the
relative rotational phase between the inner rotor 1 and the outer
rotor 2.
[0036] The fluid pressure circuit 7 includes an oil pump 70, a
control valve 76, and an oil pan 75. The oil pump 70 supplies the
operation fluid relative to the control valve 76 by means of a
driving force of the engine, the control valve 76 controls supply
and discharge of the operation fluid at plural ports by means of a
control of a control unit 9 (ECU: Electric Control Unit), and the
oil pan 75 stores the operation fluid therein. According to the
embodiment of the present invention, an electromagnetic spool valve
is used as the control valve 76 that operates and displaces a spool
76b against a spring 76g by means of an energization from the
control unit 9 to a solenoid 76a.
[0037] A first port 76c of the control valve 76 is connected to the
advanced angle passage 11 communicating with the advanced angle
chamber 43, a second port 76d of the control valve 76 is connected
to the retarded angle passage 10 communicating with the retarded
angle chamber 42, and a third port 76e of the control valve 76 is
connected to the locking passage 63 communicating with the locking
chamber 62. Further, a drain port 76f of the control valve 76 is
communicated with the oil pan 75.
[0038] By means of the control of the control unit 9, the control
valve 76 controls, through the advanced angle passage 11 and the
retarded angle passage 10, supply and discharge of the operation
fluid relative to one of, or both of the advanced angle chamber 43
and the retarded angle chamber 42, and varies the relative position
of the vane 5 in the fluid pressure chamber 40, and thereby
controls the displacement of the relative rotational phase between
the outer rotor 2 and the inner rotor 1 within the range from the
most advanced angle phase (a phase in which a volume of the
advanced angle chamber 43 is maximized) as illustrated in FIG. 6 to
the most retarded angle phase (a phase in which a volume of the
retarded angle chamber 42 is maximized) as illustrated in FIG. 5.
Accordingly, the control valve 76 and the control unit 9 for
controlling the control valve 76 both represent a phase control
apparatus 71 according to the embodiment of the present
invention.
[0039] According to the embodiment of the present invention, the
control valve 76 also serves as a lock control apparatus 72, which
controls an operation for varying a position of the locking
mechanism 6 between the lock state and the unlock state. More
particularly, by means of the control of the control unit 9, the
control valve 76 controls supply and discharge of the operation
fluid relative to the locking chamber 62 through the locking
passage 63, and controls the protruding operation and a retracting
operation of the locking member 60 relative to the locking chamber
62.
[0040] As illustrated in FIG. 7, by controlling an amount of
electricity supplied from the control unit 9 to the solenoid 76a,
the control valve 76 of the fluid pressure circuit 7 controls a
degree of a stroke of the spool 76b, and changes a spool position
from position W1 to position W5, and thereby switches operations of
supply, discharge (drain), and stop (close) of the operation fluid
relative to the advanced angle chamber 43, the retarded angle
chamber 42, and the locking chamber 62. According to the embodiment
of the present invention, a control for the amount of electricity
supplied to the solenoid 76a is performed by varying a duty value
(%) of current for supplying to the solenoid 76e. The degree of the
stroke of the spool 76b is proportional to the amount of
electricity supplied to the solenoid 76a (the duty value of
current). However the invention is not limited thereto.
Alternatively, or in addition, the control for the amount of
electricity supplied to the solenoid 76a may be performed by
various methods such as, by varying a current value, by varying a
duty value (%) of an electrical pressure, and by varying an
electrical pressure value. Control operations of the control valve
76 at each predetermined spool position is explained with reference
to FIG. 7. However, the control operation is not limited as
described below, and variations and changes may be made by
others.
[0041] In a condition where the spool position is at the position
W1, the control valve 76 supplies the operation fluid into the
locking chamber 62, retracts the locking member 60 from the locking
chamber 62, and makes the locking mechanism 6 into a unlock state.
Further, by supplying the operation fluid into the retarded angle
chamber 42 while draining the operation fluid from the advanced
angle chamber 43, the control valve 76 performs a retarded angle
direction displacement operation for displacing the relative
rotational phase between the outer rotor 2 and the inner rotor 1 in
a retarded angle direction S1.
[0042] In a condition where the spool position is at position W2,
the control valve 76 stops supply and discharge of the operation
fluid relative to both of the advanced angle chamber 43 and the
retarded angle chamber 42 (closes the first port 76c and the second
port 76d), and performs a phase holding operation for holding the
relative rotational phase between the outer rotor 2 and the inner
rotor 1 at a given time at a given position.
[0043] In a condition where the spool position is at position W3,
the control valve 76 supplies the operation fluid into the locking
chamber 62, and makes the locking mechanism 6 into the unlock
state. Further, by supplying the operation fluid into the advanced
angle chamber 43 while draining the operation fluid from the
retarded angle chamber 42, the control valve 76 performs an
advanced angle direction displacement operation for displacing the
relative rotational phase between the outer rotor 2 and the inner
rotor 1 in an advanced angle direction S2.
[0044] In a condition where the spool position is at position W4,
the control valve 76 drains the operation fluid from the locking
chamber 62, and when the relative rotational phase becomes the lock
phase, the control valve 76 makes the locking mechanism 6 into a
lockable position. Further, the control valve 76 supplies the
operation fluid into the advanced angle chamber 43 while draining
the operation fluid from the retarded angle chamber 42. Thereby,
the control valve 76 performs an advanced angle biasing operation
for biasing the relative rotational phase in the advanced angle
direction S2 in a condition where the locking mechanism 6 is at the
lockable position. This operation is performed, as described below,
for making the relative rotational phase into the lock phase and
making the locking mechanism 6 into the lock state in a starting
point control.
[0045] In a condition where the spool position is at the position
W5, a drain operation is performed for making a condition in which
the operation fluid of the advanced angle chamber 43, the retarded
angle chamber 42, and the locking chamber 62 can be discharged to
the oil pan 75. Because of this operation, all of the first port
76c, the second port 76d, and the third port 76e of the control
valve 76 communicate with the drain port 76f.
[0046] As illustrated in FIG. 8, the control unit 9 includes a
central processing unit 91 (i.e., a CPU) for calculation, a memory
92 for storing predetermined programs, data tables, or the like, an
input/output interface 93. The control unit 9 receives signals
detected by various sensors such as a cam angle sensor 101 for
detecting a camshaft phase, a crank angle sensor 102 for detecting
a crankshaft phase, an ignition switch 103, a fluid temperature
sensor 104 for detecting a temperature of the operation fluid, a
rotational speed sensor 105 for detecting a rotational speed of the
crankshaft (a rotational speed of the engine), a coolant
temperature sensor 106 for detecting a temperature of a cooling
water of the engine. The control unit 9 further receives the
signals detected by various sensors such as a vehicle speed sensor
(not shown) and a throttle angle sensor (not shown). On the basis
of the signals detected by the various sensors, the control unit 9
detects operating conditions of the engine.
[0047] On the basis of a phase of the camshaft 3 detected by the
cam angle sensor 101 and a phase of the crankshaft detected by the
crank angle sensor 102, the control unit 9 can calculate a present
value of a relative rotational phase between the camshaft 3 and the
crankshaft (i.e., the relative rotational phase between the inner
rotor 1 and the outer rotor 2 of the valve timing control
apparatus).
[0048] On the basis of operating conditions of the engine such as a
temperature of an engine fluid, a rotational speed of the
crankshaft, a vehicle speed, a throttle angle, or the like,
detected by the various sensors, the control unit 9 controls the
amount of electricity supplied to the control valve 76. Thereby,
the control unit 9 controls supply and discharge of the operation
fluid relative to the advanced angle chamber 43, the retarded angle
chamber 42, and the locking chamber 62, by means of the control
valve 76. Accordingly the control unit 9 appropriately varies the
relative rotational phase between the inner rotor 1 and the outer
rotor 2, and conditions of the locking mechanism 6 so as to be
suitable for the operating conditions of the engine of that
time.
[0049] With reference to a flowchart illustrated in FIG. 9, an
operation control of the valve timing control apparatus according
to the embodiment of the present invention is explained by focusing
a control at a starting of the engine (the starting point
control).
[0050] When the control unit 9 receives an engine starting signal
from the ignition switch 103, cranking is started (step S1: YES).
Then, the control unit 9 changes the spool position of the control
valve 76 to the position W5 for performing a drain operation so
that the operation fluid in both of the advanced angle chamber 43
and the retarded angle chamber 42 is drainable (step S2). At the
position W5, the operation fluid in the locking chamber 62 is also
drainable. In this condition, by means of the torque fluctuation
supplied to the camshaft 3 during cranking, the vane 5 is
oscillated in the advanced angle direction and in the retarded
angle direction one after the other. In case the advanced angle
chamber 43 and the retarded angle chamber 42 are filled with the
operation fluid at a starting of cranking, by means of an
oscillation of the vane 5, the operation fluid in the advanced
angle chamber 43 and the retarded angle chamber 42 is discharged.
Thereby, a facility of an operation of the vane 5 by means of the
torque fluctuation, i.e., a flexibility of the oscillation and the
displacement of the relative rotational phase between the outer
rotor 2 and the inner rotor 1 can be well ensured.
[0051] The torque fluctuation applied to the camshaft 3 during
cranking in the retarded angle direction is larger degree than that
of in the advanced angle direction. Further, the torque setting of
the torsion spring 27 is set in such a manner not to interrupt the
displacement of the relative rotational phase in the retarded
direction. Therefore, when the flexibility of the oscillation and
the displacement of the relative rotational phase is ensured, the
relative rotational phase is displaced relatively in the retarded
angle direction while oscillating during cranking. Accordingly,
when the relative rotational phase at the starting of cranking is
positioned at the advanced angle side position relative to the lock
phase, the relative rotational phase is displaced in the retarded
angle direction by means of the torque fluctuation and achieves the
lock phase during cranking. On this occasion, because the operation
fluid in the locking chamber 62 is also drainable, the locking
mechanism 6 comes into the lock state when the relative rotational
phase reaches the lock phase. Thereby a condition is achieved where
the engine can be well started. Then, when the engine is started
(step S3: YES), a control after an engine starting is started (step
S7).
[0052] FIG. 10 illustrates an example in case the relative
rotational phase at the starting of cranking is positioned at the
advanced angle side position relative to the lock phase. A timing
chart illustrated in FIG. 10 indicates an operation of the valve
timing control apparatus according to the embodiment of the present
invention in a condition where the relative rotational phase at the
starting of cranking is positioned at the most advanced angle phase
as shown in FIG. 6. In this case, when the engine starting signal
is inputted, the crankshaft is rotated by means of an electrical
motor, or the like, and then cranking is started, and thereby the
relative rotational phase is displaced relatively in the retarded
angle direction while oscillating by means of the torque
fluctuation applied to the camshaft 3. Then, the locking mechanism
6 comes into the lock state when the relative rotational phase
reaches the lock phase, and the relative rotational phase is
thereby restrained at the lock phase. FIG. 10 illustrates an
example in case the advanced angle chamber 43 and the retarded
angle chamber 42 are filled with operation fluid at the starting of
cranking, and an oscillation level of the relative rotational phase
is increased in response to a degree of the operation fluid to be
discharged from the advanced angle chamber 43 and the retarded
angle chamber 42 by means of the oscillation of the vane 5.
[0053] According to FIG. 10, the spool position of the control
valve 76 is changed to the position W4 after a predetermined period
of time T is elapsed. However, normally, the relative rotational
phase is restrained at the lock phase and the engine is started
(step S3: YES) before the predetermined period of time T is
elapsed, and the operation control of the valve timing control
apparatus progresses the control after the engine starting (step
S7). Therefore, a control after a termination of the predetermined
period of time T (step S5), is not usually performed.
[0054] In contrast, when the relative rotational phase at the
starting of cranking is positioned at the retarded angle side
position relative to the lock phase, even if the relative
rotational phase is displaced in the retarded angle direction by
means of the torque fluctuation applied to the camshaft 3 during
cranking, because the lock phase is positioned in the advanced
angle side relative to the present relative rotational phase, the
locking mechanism 6 does not come into the lock state. On this
occasion, the relative rotational phase is oscillated in the
vicinity of the most retarded angle phase. In such a condition, a
startability of the engine may be adversely affected, and the
engine m ay occasionally fail to start.
[0055] In a condition where the engine is not started (step S3: NO)
and the predetermined period of time T is elapsed (step S4: YES),
the control unit 9 changes the spool position of the control valve
76 to the position W4 and performs the advanced angle biasing
operation, and supplies the operation fluid into the advanced angle
chamber 43 while draining the operation fluid from the retarded
angle chamber 42 (step S5). On this occasion, the operation fluid
of the locking chamber 62 is also drained. Therefore, the relative
rotational phase is displaced relatively in the retarded angle
direction by means of the pressure of the operation fluid supplied
into the advanced angle chamber 43 while oscillating by means of
the torque fluctuation applied to the camshaft 3 during cranking.
Accordingly, when the relative rotational phase at the starting of
cranking is positioned at the retarded angle side position relative
to the lock phase, the relative rotational phase is displaced in
the advanced angle direction by means of the pressure of the
operation fluid supplied in the advanced angle chamber 43 and
achieves the lock phase. On this occasion, because the operation
fluid in the locking chamber 62 is also dischargeable, the locking
mechanism 6 comes into the lock state when the relative rotational
phase reaches the lock phase. Thereby the condition in which the
engine can be well started is achieved. Then, when the engine is
started (step S6: YES), the control after the engine starting is
started (step S7).
[0056] The predetermined period of time T is set, in a condition
where cranking is started with the advanced angle chamber 43 and
the retarded angle chamber 42 filled with the operation fluid
longer than, or equal to, a time required for a center of the
oscillation of the relative rotational phase during cranking to be
displaced to the lock phase from the most advanced angle phase. In
other words, the predetermined period of time T is set, in a
condition where the lock phase is positioned in a direction
(retarded angle direction) in which the relative rotational phase
is displaced by means of the torque fluctuation applied to the
camshaft 3 during cranking relative to the relative rotational
phase at the starting of cranking (in a condition where the
relative rotational phase at the starting of cranking is positioned
at the advanced angle side position relative to the lock phase)
longer than, or equal to, an estimated longest time required for
the relative rotational phase to be displaced to the lock phase by
means of the torque fluctuation. According to the embodiment of the
present invention, the valve timing control apparatus at the
estimated longest time is in a condition where the advanced angle
chamber 43 and the retarded angle chamber 42 are filled with the
operation fluid, and the relative rotational phase is positioned at
the most advanced angle phase. The predetermined period of time T
can be statistically calculated by means of a regression analysis
on the basis of a test.
[0057] FIG. 11 illustrates an example in case of the relative
rotational phase at the starting of cranking is positioned at the
retarded angle side position relative to the lock phase. A timing
chart illustrated in FIG. 11 indicates an operation of the valve
timing control apparatus according to the embodiment of the present
invention in a condition where the relative rotational phase at the
starting of cranking is positioned at the most retarded angle phase
as shown in FIG. 5. In this case, when the engine starting signal
is inputted, the crankshaft is rotated by means of an electrical
motor, or the like, and then cranking is started. According to this
operation, the relative rotational phase is oscillated by means of
the torque fluctuation applied to the camshaft 3. However, because
the relative rotational phase cannot be displaced in the retarded
direction more than the present position, the relative rotational
phase is oscillated in the vicinity of the most retarded angle
phase. Therefore, on this occasion, the relative rotational phase
does not reach the lock phase. Thus, after the predetermined period
of time T is elapsed, the control unit 9 changes the spool position
of the control valve 76 to the position W4 (step S5). Thereby, the
relative rotational phase is displaced relatively in the advanced
angle direction by means of the pressure of the operation fluid
supplied into the advanced angle chamber 43 while oscillating by
means of the torque fluctuation. Then, when the relative rotational
phase reaches the restriction phase, the locking member 60 of the
locking mechanism 6 protrudes and engages with the restricting step
portion 64, and thereby the displacement of the relative rotational
phase in the retarded direction is restricted. Further, the locking
mechanism 6 comes into the lock state when the relative rotational
phase is displaced in the advanced angle direction and reached the
lock phase. Thereby the relative rotational phase is restrained at
the lock phase and the condition in which the engine can be well
started is achieved. Then, when the engine is started (step S6:
YES), the control after the engine starting is started (step S7).
FIG. 11 illustrates an example in case cranking is started with the
advanced angle chamber 43 and the retarded angle chamber 42 are
filled with the operation fluid, and the oscillation level of the
relative rotational phase is increased in response to a degree of
the operation fluid to be discharged from the advanced angle
chamber 43 and the retarded angle chamber 42 by means of the
oscillation of the vane 5.
[0058] According to the embodiment of the present invention, by
means of the torque fluctuation applied to the camshaft 3 during
cranking, the relative rotational phase between the outer rotor 2
and the inner rotor 1 is displaced relatively in the retarded angle
direction while oscillating. However the invention is not limited
thereto. Alternatively, or in addition, the relative rotational
phase may be displaced relatively in the advanced angle direction
while oscillating during cranking by means of the torque
fluctuation applied to the camshaft 3 during cranking. In such a
case the torsion spring 27 is provided for biasing the relative
rotational phase in the retarded angle direction. The
aforementioned explanation for the operation control at the
starting of the engine (the starting point control) can be applied
to this variation on a condition that the words advanced and
retarded are switched.
[0059] According to the embodiment of the present invention, the
locking chamber 62 is provided with, at the retarded angle side,
the restricting step portion 64. The restricting step portion 64,
at the restriction phase defined between the most retarded angle
phase and the lock phase, restricts the displacement of the
relative rotational phase to the retarded angle side from the
restriction phase, and allows the displacement of the relative
rotational phase to the advanced angle side. Thereby, a reliability
of a restraint of the relative rotational phase by means of the
locking mechanism 6 can be improved. However the invention is not
limited thereto. Alternatively, or in addition, the valve timing
control apparatus may be configured without the restricting step
portion 64. It is because, according to the embodiment of the
present invention, the displacement of the rotational phase from
the most retarded angle phase to the lock phase can be certainly
performed by forcibly displacing the relative rotation in the
advanced angle direction by supplying the operation fluid into the
advanced angle chamber 43 after the predetermined period of time T
is elapsed.
[0060] According to the embodiment of the present invention, during
the predetermined period of time after the staring of cranking, the
cranking is performed in a condition where the operation fluid in
both of the advanced angle chamber and the retarded angle chamber
is drainable. Therefore, by means of the oscillation of the
relative rotational phase, the relative rotational phase can be
displaced in one of the advanced angle direction and the retarded
angle direction while draining the operation fluid from the
advanced angle chamber and the retarded angle chamber. Accordingly,
in a condition where the lock phase is positioned at one of the
advanced angle side and the retarded angle side relative to the
relative rotational phase at the starting of cranking, the relative
rotational phase can be restrained by means of the locking
mechanism. In contrast, in a condition where the lock phase is not
positioned at the one of the advanced angle side and the retarded
angle side, the operational fluid is supplied into one of the
advanced angle chamber and the retarded angle chamber for
displacing the relative rotational phase to the other of the
advanced angle side and the retarded angle side after the
predetermined period of time is elapsed, thus the relative
rotational phase can be restrained by means of the locking
mechanism. Accordingly, the reliability of the restraint of the
relative rotational phase by means of the locking mechanism at the
starting of the internal combustion engine can be improved.
[0061] The present invention is applicable as long as the
predetermined period of time is set, in a condition where cranking
is started with the fluid pressure chamber filled with the
operation fluid, longer than, or equal to, the time required for
the center of the oscillation of the relative rotational phase
during cranking to be displaced to the lock phase from one of the
most advanced angle phase and the most retarded angle phase
positioned in the other of the advanced angle direction and the
retarded angle direction. In such a condition, the relative
rotational phase can certainly be reached to the lock phase in a
condition where the lock phase is positioned at the one of the
advanced angle side and the retarded angle side. Accordingly, the
reliability of the restraint by means of the locking mechanism can
be improved.
[0062] The present invention is applicable as long as the phase
control apparatus discontinues the starting point control when the
internal combustion engine is started, and starts the control after
the engine starting.
[0063] The principles, preferred embodiment and mode of operation
of the present invention have been described in the foregoing
specification. However, the invention which is intended to be
protected is not to be construed as limited to the particular
embodiment disclosed. Further, the embodiment described herein are
to be regarded as illustrative rather than restrictive. Variations
and changes may be made by others, and equivalents employed,
without departing from the spirit of the present invention.
Accordingly, it is expressly intended that all such variations,
changes and equivalents which fall within the spirit and scope of
the present invention as defined in the claims, be embraced
thereby.
* * * * *