U.S. patent application number 09/875180 was filed with the patent office on 2001-12-20 for valve timing adjusting device.
Invention is credited to Adachi, Michio, Hattori, Isao, Takenaka, Akihiko.
Application Number | 20010052330 09/875180 |
Document ID | / |
Family ID | 18676208 |
Filed Date | 2001-12-20 |
United States Patent
Application |
20010052330 |
Kind Code |
A1 |
Takenaka, Akihiko ; et
al. |
December 20, 2001 |
Valve timing adjusting device
Abstract
A spool is moved by controlling the amount of electric current
supplied to a linear solenoid of a changeover valve, and selects
any one of valve sections. The state of communication between fluid
passages connected to the changeover valve is determined by the
valve section and selected. With the selection of the valve
section, the hydraulic fluid is discharged from the advance oil
pressure chamber while being supplied to the advance oil pressure
chamber, and also is discharged from the retard oil pressure
chamber. The oil pressure in the advance oil pressure chamber
remains low even when the oil is filled in the advance oil pressure
chamber.
Inventors: |
Takenaka, Akihiko;
(Anjo-city, JP) ; Hattori, Isao; (Gifu-city,
JP) ; Adachi, Michio; (Obu-city, JP) |
Correspondence
Address: |
Larry S. Nixon, Esq.
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Rd.
Arlington
VA
22201-4714
US
|
Family ID: |
18676208 |
Appl. No.: |
09/875180 |
Filed: |
June 7, 2001 |
Current U.S.
Class: |
123/90.17 ;
123/90.15 |
Current CPC
Class: |
F01L 2001/3443 20130101;
F01L 2001/34483 20130101; F01L 2001/34426 20130101; F01L 2001/34479
20130101; F01L 2800/03 20130101; F01L 1/3442 20130101 |
Class at
Publication: |
123/90.17 ;
123/90.15 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2000 |
JP |
2000-174104 |
Claims
What is claimed is:
1. A valve timing adjusting device provided in a driving force
transmission system which transmits a driving force from a driving
shaft of an internal combustion engine to a camshaft which drives
to open and close at least one of an intake valve and an exhaust
valve, for adjusting opening-closing timing of at least one of said
intake valve and said exhaust valve, comprising: a driving-side
rotor rotating together with said driving shaft of the internal
combustion engine, said driving-side rotor including a housing
chamber therein; a driven-side rotor provided in said housing
chamber and rotating together with said camshaft, said driven-side
rotor including vanes partitioning said housing chamber into retard
chambers and advance chambers, said driven-side rotor driven to
rotate with respect to said driving-side rotor within a
predetermined range of angle by a fluid pressure in said retard
chambers and said advance chambers; a restraining means including a
contacting portion provided within said driven-side rotor and a
contacted portion provided within said driving-side rotor, said
restraining means restrains a relative rotation of said driven-side
rotor with respect to said driving-side rotor when said contacting
portion contacts said contacted portion while said driven-side
rotor is at an intermediate position between both ends in a
circumferential direction of the predetermined range of angle, said
restraining means further including an urging means for urging said
contacting portion toward said contacted portion; an advance fluid
passage being capable of supplying the fluid into said advance
chambers and discharging the fluid therefrom; a retard fluid
passage being capable of supplying the fluid into said retard
chambers and to discharging the fluid therefrom; and a changeover
means for changing over connection between said advance fluid
passage and a fluid supply source or a drain, and for changing over
connection between a retard fluid passage and said fluid supply
source or said drain, wherein said changeover means is capable of
simultaneously connecting said advance fluid passage with said
fluid supply source, and said advance fluid passage with said
drain.
2. A valve timing adjusting device according to claim 1, further
including an advance control means for supplying the fluid to said
advance chamber when the engine is stopped.
3. A valve timing adjusting device according to claim 1, wherein
said changeover means is a valve device having a cylindrical
housing and a valve member, said cylindrical housing has a
plurality of through holes for connection of said advance fluid
passage, said retard fluid passage, said fluid supply source, and
said drain said valve member is reciprocally movably housed in said
cylindrical housing and is moved to change communication positions
among said through holes, and said valve device is capable of
selecting, by moving said valve member, a fluid passage structure
connecting said advance fluid passage with said fluid supply
source, and said advance fluid passage with said drain.
4. A valve timing adjusting device according to claim 3, wherein
said valve device includes a valve operating means for urging said
valve member in one direction, and an electromagnetically driving
portion for driving said valve member in an opposite direction of
said valve operating means, and when an electric current is not
supplied to said electromagnetically driving portion, said valve
member simultaneously connects said advance fluid passage with said
fluid supply source, and said advance fluid passage with said drain
by an urging force of said valve operating means.
5. A valve timing adjusting device according to claim 3, wherein
said through holes of said cylindrical housing include an advance
port and a communication port communicating with said advance flow
passage, a retard port communicating with said retard flow passage,
an input port connected to said fluid supply source, and a drain
port connected to said drain, and said advance port communicates
with said input port, and said communication port communicates with
said drain port in accordance with a moving position of said valve
member.
6. A valve timing adjusting device according to claim 5, wherein
said cylindrical housing has a communication passage formed on an
outer peripheral wall thereof, and said communication passage
allows said advance port to communicate with said communication
port.
7. A valve timing adjusting device according to claim 5, wherein
said drain port that can communicate with said advance port and
said communication port are common.
8. A valve timing adjusting device according to claim 1, further
including a control means to control said changeover means so as to
connect said advance fluid passage with said fluid supply source
and said drain for a predetermined period when the engine
starts.
9. A valve timing adjusting device according to claim 1, wherein in
said changeover means, a fluid passage area for connection between
said advance fluid passage and said drain is less than a fluid
passage area for connection between said advance fluid passage and
said fluid supply source.
10. A valve timing adjusting device provided in a driving force
transmission system which transmits a driving force from a driving
shaft of an internal combustion engine to a camshaft which drives
to open and close at least one of an intake valve and an exhaust
valve, for adjusting opening-closing timing of at least one of said
intake valve and said exhaust valve, comprising: a driving-side
rotor rotating together with said driving shaft of the internal
combustion engine, said driving-side rotor including a housing
chamber therein; a driven-side rotor provided in said housing
chamber and rotating together with said camshaft, said driven-side
rotor including vanes partitioning said housing chamber into retard
chambers and advance chambers, said driven-side rotor driven to
rotate with respect to said driving-side rotor within a
predetermined range of angle by a fluid pressure in said retard
chambers and said advance chambers; a restraining means including a
contacting portion provided within said driven-side rotor and a
contacted portion provided within said driving-side rotor, said
restraining means restrains a relative rotation of said driven-side
rotor with respect to said driving-side rotor when said contacting
portion contacts said contacted portion while said driven-side
rotor is at an intermediate position between both ends in a
circumferential direction of the predetermined range of angle, said
restraining means further including an urging means for urging said
contacting portion toward said contacted portion; an advance fluid
passage being capable of supplying the fluid into said advance
chambers and discharging the fluid therefrom; a retard fluid
passage being capable of supplying the fluid into said retard
chambers and to discharging the fluid therefrom; and a changeover
means for changing over connection between said advance fluid
passage and a fluid supply source or a drain, and for changing over
connection between a retard fluid passage and said fluid supply
source or said drain, wherein said changeover means is capable of
simultaneously connecting said retard fluid passage with said fluid
supply source, and said retard fluid passage with said drain.
11. A valve timing adjusting device according to claim 10, further
including an advance control means for supplying the fluid to said
advance chamber when the engine is stopped.
12. A valve timing adjusting device according to claim 10, wherein
said changeover means is a valve device having a cylindrical
housing and a valve member, said cylindrical housing has a
plurality of through holes for connection of said advance fluid
passage, said retard fluid passage, said fluid supply source, and
said drain said valve member is reciprocally movably housed in said
cylindrical housing and is moved to change communication positions
among said through holes, and said valve device is capable of
selecting, by moving said valve member, a fluid passage structure
connecting said retard fluid passage with said fluid supply source,
and said retard fluid passage with said drain.
13. A valve timing adjusting device according to claim 12, wherein
said valve device includes a valve operating means for urging said
valve member in one direction, and an electromagnetically driving
portion for driving said valve member in an opposite direction of
said valve operating means, and when an electric current is not
supplied to said electromagnetically driving portion, said valve
member simultaneously connects said retard fluid passage with said
fluid supply source, and said retard fluid passage with said drain
by an urging force of said valve operating means.
14. A valve timing adjusting device according to claim 12, wherein
said through holes of said cylindrical housing include an retard
port and a communication port communicating with said retard flow
passage, an advance port communicating with said advance flow
passage, an input port connected to said fluid supply source, and a
drain port connected to said drain, and said retard port
communicates with said input port, and said communication port
communicates with said drain port in accordance with a moving
position of said valve member.
15. A valve timing adjusting device according to claim 14, wherein
said cylindrical housing has a communication passage formed on an
outer peripheral wall thereof, and said communication passage
allows said retard port to communicate with said communication
port.
16. A valve timing adjusting device according to claim 14, wherein
said drain port that can communicate with said retard port and said
communication port are common.
17. A valve timing adjusting device according to claim 10, further
including a control means to control said changeover means so as to
connect said retard fluid passage with said fluid supply source and
said drain for a predetermined period when the engine starts.
18. A valve timing adjusting device according to claim 1, wherein
in said changeover means, a fluid passage area for connection
between said retard fluid passage and said drain is less than a
fluid passage area for connection between said retard fluid passage
and said fluid supply source.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2000-174104 filed on Jun.
9, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a valve timing adjusting
device for changing valve opening-closing timing suitable for use
in intake and exhaust valves of an internal combustion engine.
[0004] 2. Description of Related Art
[0005] As a conventional valve timing adjusting device, there is a
well known vane-type device in which a camshaft is driven through a
timing pulley, a chain sprocket, etc. which turn synchronously with
an engine crankshaft. The valve timing of at least any one of an
intake valve and an exhaust valve is hydraulically controlled by a
phase difference of relative rotation of the timing pulley, the
chain sprocket, and the camshaft. Engine output and fuel
consumption ratio are improved by adjusting the phase difference
between the crankshaft and the camshaft to an optimum value in
accordance with engine operating state.
[0006] In such a vane-type valve timing adjusting device using
operation oil, when at least any one of the intake valve and the
exhaust valve is actuated, the camshaft receives a load torque
which varies between positive and negative loads. Therefore, when
the operation oil is not sufficiently supplied during cranking of
the engine, there might arise such a problem that a vane member
oscillates with respect to a housing member containing the vane
member, thereby hitting against the housing member to produce
knocks. The positive load torque is applied in the retarding
direction of the camshaft with respect to the crankshaft, and the
negative load torque is added in the advancing direction of the
camshaft with respect to the crankshaft. Average positive and
negative load torques is added in the retarding direction of the
camshaft with respect to the crankshaft.
[0007] There has been such a well known device that, in case of
insufficient supply of operation oil to the valve timing adjusting
device, occurrence of knocks is prevented by preventing the vane
member from oscillating with respect to the housing member by
fitting a stopper piston in a fitting hole formed in the housing
member. Therefore, when the operation oil is sufficiently supplied,
the stopper piston is moved by the oil pressure out of the housing
member, thereby enabling the control of rotation of the vane member
with respect to the housing member.
[0008] Here, it is possible to reduce a pumping loss of the engine
for improving the fuel consumption ratio by retarding the intake
valve closing timing over the BDC position of a piston. However,
when the intake valve closing timing is retarded over the BDC
position of the piston, the fuel consumption ratio is improved
after an engine warm-up, but a real compression ratio becomes lower
at the time of cold engine, so that the air temperature does not
sufficiently rise at the top dead center (TDC) of the piston. Thus,
the engine might fail in starting. In this case, an optimum valve
timing of the intake valve during the period of engine cooling is
at the advance side of an optimum valve timing after the engine
warm-up.
[0009] Therefore, it is considered to start the engine with
certainty by fitting the stopper pin in the fitting hole to stop
the engine when the vane member is in an intermediate position
between the most advanced angle and the most retarded angle with
respect to the housing member, and then by starting the engine when
the vane member is in the intermediate position. As the valve
timing adjusting device described above are disclosed in
JP-A-9-324613 and JP-A-11-343819.
[0010] Generally, when the engine is stopped, the oil pressure
added to each oil pressure chamber drops, and the vane member is
turned to the retard side with respect to the housing member by a
load torque applied to the camshaft. Therefore, when the vane
member is positioned at the advance side over the intermediate
position with respect to the housing member, the vane member is
rotated to the retard side by the load torque when the engine is
stopped and reaches the intermediate position to allow the stopper
piston to fit in the fitting hole.
[0011] However, when the vane member is at the advance side of the
intermediate position with respect to the housing member, the
engine might stop due to increased viscosity of the operation oil
during a cold engine even when the load torque is applied to the
camshaft while an engine does not operate. Even when the engine is
stopped in such a condition that the vane member is at the advance
side of the intermediate position with respect to the housing
member, the load torque is applied to the camshaft during the
engine cranking, and the vane member rotates to the retard side
with respect to the housing member when the engine starts. Then,
the stopper piston fits in the fitting hole, thereby starting the
engine at the intermediate position.
[0012] However, when the engine is started up immediately after the
engine stop, the oil pressure is added to the oil pressure chamber
because the oil is filled in an oil passage. When the operation oil
is supplied to the advance oil pressure chamber after the engine
startup, the oil pressure in the advance oil pressure chamber
increases before the vane member receiving the load torque turns to
the retard side, thereby causing the vane member to be placed at
the advance side of the intermediate position. In the case of the
intake valve for example, when the engine is started up while the
intake valve opening timing is advanced, the exhaust valve opening
timing and the intake valve opening timing overlap each other,
thereby failing in starting the engine up.
[0013] In the valve timing adjusting device disclosed in
JP-A-11-343819, the operation oil is discharged out of the advance
oil pressure chamber and the retard oil pressure chamber during
engine startup, thereby allowing the vane member to rotate to the
retard side at the time of engine startup.
[0014] However, since no operation oil is supplied to both the
advance oil pressure chamber and the retard oil pressure chamber,
sliding parts of members are not be supplied with the operation oil
at the time of engine startup, so that the sliding parts of members
are likely to be seized up. Further, while no operation oil is
supplied to both oil pressure chambers, when the stopper piston
comes out of the fitting hole, the vane member is likely to turn to
the advance side by the load torque, so that the vane member hits
against the housing member.
SUMMARY OF THE INVENTION
[0015] An object of the present invention is to provide a valve
timing adjusting device in which a driven-side rotor is held at an
intermediate position with respect to a driving-side rotor when the
engine starts, for preventing seizure of sliding parts during
engine startup operation and occurrence of knocks.
[0016] According to the valve timing adjusting device in the
present invention, when the engine is stopped when the drive-side
rotor is at an advance side of the intermediate position with
respect to the driving-side rotor, the hydraulic fluid can be
discharged from an advance chamber to a drain while supplying the
hydraulic fluid from a fluid supply source to the advance chamber
by simultaneously connecting the advance fluid passage to the fluid
supply source, and the advance fluid passage to the drain, at the
time of engine startup. Since the advance chamber fluid pressure
remains low even when the hydraulic fluid is filled in the advance
chamber, the driven-side rotor rotates to the retard side with
respect to the driving-side rotor when the load torque is applied
to the driven-side rotor at the time of engine startup. When the
driven-side rotor reaches the intermediate position, a contacting
portion contacts a contacted portion, thereby holding the
driven-side rotor at the intermediate position with respect to the
driving-side rotor. By setting the intermediate position at the
optimum phase, the engine can be reliably started up. Upon engine
starting up, the hydraulic fluid pressure rises to move the
contacting portion away from the contacted portion, so that
rotation of the driven-side rotor with respect to the driving-side
rotor is controlled.
[0017] Since the hydraulic fluid can be discharged out of the
advance chamber while supplying the hydraulic fluid into the
advance chamber during engine startup, the hydraulic fluid
circulates in the advance fluid passage and the advance chamber.
Since the hydraulic fluid lubricates sliding parts of each member
from just after the beginning of engine startup, it is possible to
prevent seizure of the member at the time of engine startup.
[0018] Since the advance chamber is full of the hydraulic fluid,
though at a low pressure, at the time of engine startup, the
driven-side rotor is prevented from rotating to the retard side to
hit against the driving-side rotor even when the contacting portion
is released from the contacted portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Additional objects and advantages of the present invention
will be more readily apparent from the following detailed
description of preferred embodiments thereof when taken together
with the accompanying drawings in which:
[0020] FIG. 1 is a schematic view showing a cross-sectional view
taken along line I-I in FIG. 2 showing a valve timing adjusting
device and showing a changeover valve (first embodiment);
[0021] FIG. 2 is a cross-sectional showing the valve timing
adjusting device (first example);
[0022] FIG. 3 is a cross-sectional view taken along line III-III in
FIG. 2 (first embodiment);
[0023] FIG. 4 is a cross-sectional view taken long line IV-IV in
FIG. 2 (first embodiment);
[0024] FIG. 5 is a cross-sectional view showing an operating state
of the changeover valve (first embodiment);
[0025] FIG. 6 is a cross-sectional view showing the operating state
of the changeover valve (first embodiment);
[0026] FIG. 7 is a cross-sectional view showing the operating state
of the changeover valve (first embodiment);
[0027] FIG. 8 is a cross-sectional view showing an operating state
of a changeover valve (second embodiment);
[0028] FIG. 9 is a schematic view showing a cross-sectional view
showing a stopper piston and its vicinity of the valve timing
adjusting device and showing a changeover valve (third
embodiment);
[0029] FIG. 10 is a cross-sectional view showing an operating state
of the changeover valve (third embodiment);
[0030] FIG. 11 is a cross-sectional view showing an operating state
of the changeover valve (third embodiment);
[0031] FIG. 12 is a cross-sectional view showing an operating state
of the changeover valve (third embodiment);
[0032] FIG. 13 is a cross-sectional view showing an operating state
of a changeover valve (fourth embodiment), and
[0033] FIG. 14 is a schematic view showing a cross-sectional view
showing a stopper piston and its vicinity of the valve timing
adjusting device and showing a changeover valve (fifth
embodiment).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0034] First Embodiment
[0035] FIG. 3 shows an engine valve timing adjusting device 1 of
the first embodiment. The valve timing adjusting device 1 is of a
hydraulic pressure control type and controls an intake valve
timing.
[0036] A chain sprocket 10 is connected to a crankshaft as a drive
shaft of the engine and receives a driving force through a chain.
The chain sprocket 10 rotates in synchronization with the
crankshaft. The driving force is transmitted to the camshaft 2 as a
driven shaft through the chain sprocket 10. The camshaft opens and
closes the intake valve. The camshaft 2 is rotatable with respect
to the chain sprocket 10 by a predetermined phase difference. The
chain sprocket 10 and the camshaft 2 rotate clockwise as viewed in
the direction of the arrow X in FIG. 3. Hereinafter, this
rotational direction defines an advance direction.
[0037] Between the chain sprocket 10 and a set of shoe housing 12
and vane rotors 15, a disk-shaped intermediate plate 17 is
provided. The intermediate plate 17 prevents oil leaks from between
the chain sprocket 10 and the set of shoe housing 12 and vane
rotors 15. The chain sprocket 10, the shoe housing 12, and the
intermediate plate 17 forms a housing member and works as a
driving-side rotor, and coaxially secured by a bolt 20.
[0038] The shoe housing 12 integrally includes a side wall 13 and a
front plate 14. As shown in FIG. 2, the shoe housing 12 includes
shoes 12a, 12b and 12c formed in a trapezoidal shape and
circumferentially arranged at approximately equal spacing
intervals. In three spaces provided in the circumferential
direction of the shoes 12a, 12b and 12c, housing chambers 50 for
containing vanes 15a, 15b and 15c are formed. The inner peripheral
surfaces of the shoes 12a, 12b and 12c are formed in an arc in
cross section.
[0039] The vane rotor 15 includes vanes 15a, 15b and 15c arranged
at approximately equal spacing intervals in the circumferential
direction. The vanes 15a, 15b and 15c are rotatably accommodated
within each of housing chambers 50. Each vane divides the housing
chamber 50 into a retard hydraulic fluid chamber and an advance
hydraulic fluid chamber. Arrows in FIG. 2 indicating retard and
advance directions indicate the retard and advance directions of
the vane rotor 15 with respect to the shoe housing 12. The most
retarded position of the vane rotor 15 with respect to the shoe
housing 12 is determined by contact of the vane 15b with the shoe
12a. The most advanced position of the vane rotor 15 with respect
to the shoe housing 12 is determined by contact of the vane 15b
with the shoe 12b. As shown in FIG. 3, the vane rotor 15 and a
bushing 22 are integrally fixed by a bolt 21 on the camshaft 2, and
form a driven-side rotor. A pin 23 determines the positioning of
the vane rotor 15 in the rotational direction with respect to the
camshaft 2.
[0040] The camshaft 2 and the bushing 22 are correlatively
rotatably fitted in the inner wall 10a of the chain sprocket 10 and
in the inner wall 14a of the front plate 14. Therefore, the
camshaft 2 and the vane rotor 15 are coaxially correlatively
rotatable with respect to the chain sprocket 10 and the shoe
housing 12. The inner wall 10a of the chain sprocket 10 and the
inner wall 14a of the front plate 14 work as bearings for
supporting the driven-side rotor.
[0041] A spring 24 is installed in a cylindrical recess 11 formed
in the chain sprocket 10. The spring 24 is retained at one end by
the retaining portion 11a of the recess 11 and at the other end by
the vane rotor 15 as shown in FIG. 4 through a long hole 17a formed
in the intermediate plate 17 shown in FIGS. 2 and 4.
[0042] The load torque which the camshaft 2 receives while driving
the intake valve varies to both positive and negative sides. Here,
the positive direction of the load torque is the retard direction
of the vane rotor 15 with respect to the shoe housing 12, while the
negative direction of the load torque is the advance direction of
the vane rotor 15 with respect to the shoe housing 12. An average
load torque is applied in the positive direction, that is, in the
retard direction. The urging force of the spring 24 works as a
torque to rotate the vane rotor 15 to the advance side with respect
to the shoe housing 12. The torque of the spring 24 acting on the
vane rotor 15 in the advance direction is almost the same as the
average load torque acting on the camshaft 2.
[0043] A seal member 26 is fitted in the outer peripheral wall of
the vane rotor 15 as shown in FIG. 2. Between the outer peripheral
wall of the vane rotor 15 and the inner peripheral wall of the side
wall 13, a very small clearance is provided. The seal member 26
prevents the hydraulic fluid from leaking between the hydraulic
fluid chambers through the clearance. The seal member 26 is pressed
toward the side wall 13 by the force of the plate spring 27 shown
in FIG. 3.
[0044] A guide ring 30 is pressed and retained in the inner wall of
the vane 15a forming the housing hole 38. A guide ring 31 is
pressed and retained in the inner wall of the guide ring 30. A
cylindrical stopper piston 32 as a contacting portion is provided
in the guide rings 30 and 31, and is slidable in the axial
direction of the camshaft 2. A fitting member 40 as a contacted
portion formed in a circle in cross section is pressed and retained
in recess 14b formed in the front plate 14. As shown in FIG. 1, in
the fitting member 40, a fitting hole 41 in which the stopper
piston 32 can be fitted to contact the fitting member 40, and an
enlarged hole 43 extended on the advance side which is shallower
than the fitting hole 41, and has a retard-side end face on the
same plane as the retard-side end face of the fitting hole 41.
[0045] The stopper piston 32 is formed in a cylindrical shape
having a bottom and has a first small-diameter portion 33, a
large-diameter portion 34, and a second small-diameter portion 35
as viewed from the fitting member 40. The first small-diameter
portion 33 is tapered as it goes toward the fitting direction.
Since the fitting hole 41 is also tapered at approximately the same
angle of taper as the inclination of the first small-diameter
portion 33, the stopper piston 32 can smoothly fit in the fitting
hole 41. Furthermore, since the stopper piston 32 tightly fits in
the fitting hole 41, it is possible to prevent occurrence of knocks
likely to be produced by load torque variations. Furthermore, since
the first small-diameter portion 33 being in contact with the
fitting hole 41, has a large contact surface area, the first
small-diameter portion 33 receives small stress, thereby improving
a durability of the stopper piston 32.
[0046] A spring 37 in FIG. 1 urges the stopper piston 32 toward the
fitting member 40. A restraining means in the present invention
includes the stopper piston 32, the fitting member 40 and the
spring 37.
[0047] The first small-diameter portion 33 of the stopper piston 32
can fit in the fitting hole 41 when the vane rotor 15 is nearly in
the intermediate position between the most retarded position and
the most advanced position with respect to the shoe housing 12 as
shown in FIG. 2. When the stopper piston 32 is fitted in the
fitting hole 41, the relative rotation of the vane rotor 15 with
respect to the shoe housing 12 is restrained. In the intermediate
position, the relative rotation of the vane rotor 15 with respect
to the shoe housing 12 is restrained with the stopper piston 32
fitted in the fitting hole 41. In this intermediate position, the
phase difference of the camshaft 2 from the crankshaft, that is,
the intake valve timing is set in optimum such that the engine can
be reliably started up.
[0048] When the stopper piston 32 is withdrawn out of the fitting
hole 41, the vane rotor 15 is relatively rotatable with respect to
the shoe housing 12.
[0049] As shown in FIG. 1, the front end face of the first
small-diameter portion 33 receives the retard oil pressure from an
oil pressure chamber 42. Annular surface formed on the fitting hole
41 side of the large-diameter portion 34 receives an advance oil
pressure from an oil pressure chamber 45 when an oil passage 47
formed by the oil pressure chamber 45 and the vane 15a is not
closed by the large-diameter portion 34. The oil pressure that the
stopper piston 32 receives from the oil pressure chambers 42 and 45
are applied in the direction in which the stopper piston 32 moves
out of the fitting hole 41. The oil pressure chamber 42
communicates with a retard oil pressure chamber 51 through an oil
passage (not illustrated) formed in the front plate 14. The oil
pressure chamber 45 communicates with an advance oil pressure
chamber 54 through a through hole 30a formed in the guide ring 30
and an oil passage.
[0050] A damper chamber 46 communicates with an oil passage 48
through a through hole 30b formed in the guide ring 30. A recess
space 49 is formed on the sliding side of the intermediate plate 17
on which the vane 15a slides. The recess space 49 can communicate
with the advance oil pressure chamber 54 and the oil passage 48,
that is, with the damper chamber 46, in accordance with the
relative rotational position of the vane rotor 15 with respect to
the shoe housing 12. The connection of the advance oil pressure
chamber 54 with the damper chamber 46 is interrupted by the sliding
surface of the vane rotor 15 and the intermediate plate 17. The
advance oil pressure chamber 54 communicates with the damper
chamber 46 through the recess space 49 when the vane rotor 15
rotates to the advance side with respect to the shoe housing 12
over the intermediate position where the stopper piston 32 fits in
the fitting hole 41.
[0051] When the damper chamber 46 is disconnected from the advance
oil pressure chamber 54, the damper chamber 46 is hermetically
sealed. When the damper chamber 46 is hermetically sealed, the
damper chamber 46 operates as a damper to decrease the speed of
movement of the stopper piston 32 toward the fitting hole 41. The
damper chamber 46 is opened when the damper chamber 46 communicates
with the advance oil pressure chamber 54. When the damper chamber
46 is opened and ceases to function as a damper, the stopper piston
32 can easily move toward the fitting hole 41. In this way, the
opening and hermetically sealing of the damper chamber 46 is
changed over by the relative rotational position of the vane rotor
15.
[0052] As shown in FIG. 3, the housing hole 38 formed on the
opposite side of the fitting member of the stopper piston 32 is
constantly open to the atmosphere within the range of relative
rotation angle of the vane rotor 15 through a through hole 39
formed in the vane 15a, a communicating hole 17b extending in the
peripheral direction formed in the intermediate plate 17, and an
oil passage 10b formed in the chain sprocket 10. Therefore, the
reciprocating movement of the stopper piston 32 will not be
disturbed.
[0053] As shown in FIG. 2, the retard oil pressure chamber 51 is
formed between the shoe 12a and the vane 15a; a retard oil pressure
chamber 52 is formed between the shoe 12b and the vane 15b; and a
retard oil pressure chamber 53 is formed between the shoe 12c and
the vane 15c. Similarly, the advance oil pressure chamber 54 is
formed between the shoe 12c and the vane 15a; an advance oil
pressure chamber 55 is formed between the shoe 12a and the vane
15b; and an advance oil pressure chamber 56 is formed between the
shoe 12b and the vane 15c.
[0054] The retard oil pressure chamber 51 communicates with an oil
passage 61. And the retard hydraulic fluid chambers 52 and 53
communicate with an oil passage 60 shown in FIG. 2 formed in a
C-letter shape in the end face of the camshaft 2 side of the boss
portion 15d through oil passages 62 and 63. Furthermore, the retard
oil pressure chambers 51, 52 and 53 communicate with an oil passage
200 formed in the camshaft 2 shown in FIG. 3 through the oil
passages 60 and 61. The advance oil pressure chamber 55, as shown
in FIG. 2, communicates with an oil passage 72. The advance oil
pressure chambers 54 and 56 communicate with an oil passage 70
formed in a C-letter shape in the end face on the bushing 22 side
of the boss portion 15d through oil passages 71 and 73.
Furthermore, the advance oil pressure chambers 54, 55 and 56
communicate, from the oil passages 70 and 72, with an oil passage
201 formed in the camshaft 2 shown in FIG. 3, through an oil
passage (not illustrated) formed in the axial direction of the boss
portion 15d.
[0055] The oil passage 200 communicates with a groove passage 202
formed in the outer peripheral wall of the camshaft 2; and the oil
passage 201 communicates with a groove passage 203 formed in the
outer peripheral wall of the camshaft 2. The groove passage 202 is
connected with a changeover valve 212 as a changeover means through
a retard oil passage 104; and a groove passage 203 is connected
with the changeover valve 212 through an advance oil passage 205.
An oil supply passage 206 is connected to an oil pump 210. An oil
discharge passage 207 is open to a drain 211. The oil pump 210
supplies the operation oil drawn up from the drain 211 to each oil
pressure chamber through the changeover valve 212.
[0056] The changeover valve 212 is an electromagnetically-driven
valve device having one spool 213 as a valve member. Valve sections
213a, 213b, 213c, and 213d indicate a position of the spool 213
with respect to a housing 231 (see FIG. 5) which reciprocally
movably houses the spool 213, determining the state of connection
between oil passages connected to the changeover valve 212. The
spool 213 of the changeover valve 212 is urged in one direction by
the spring 214, to slide reciprocally by controlling the supply of
the electric current to the linear solenoid 215 as an
electromagnetic driving section. The electric current to be
supplied to the linear solenoid 215 is controlled by the engine
control unit (ECU) 300. The ECU 300 receives signals of detection
from various sensors, and sends signals to each device of the
engine. As the spool 213 reciprocally moves, the combination of
connection and disconnection among the oil passages 204, 205, the
oil supply passage 206 and the oil discharge passage 207 is changed
over.
[0057] Detailed structure of the changeover valve 212 is shown in
FIG. 5. FIG. 5 shows a state that the linear solenoid 215 supplying
the maximum electric current to a coil 223. A moving core 220 moves
reciprocally together with a rod 221. When the coil 223 is
energized, there is produced a magnetic force across a stationary
core 222 and the moving core 220, and therefore the moving core 220
is attracted toward the stationary core 222.
[0058] On the spool 213, a plurality of lands are formed, each of
which slides against the inner peripheral wall of the housing 231.
The spring 214 urges the spool 213 in the opposite direction of the
moving core 220 is attracted. The spool 213 is reciprocally movably
supported by the housing 231, which is provided with a plurality of
ports, or through holes, formed through the peripheral wall. In the
housing 231, input port 232 through which the hydraulic fluid is
fed, drain ports 233 and 234 through which the fluid is discharged,
a retard port 240, an advance port 241, and a communication port
242 are formed. The input port 232 communicates with the fluid
supply passage 206, through which the oil is supplied into the
input port 232 by the oil pump 210. The drain ports 233 and 234
communicate with the oil discharge passage 207, and open to the
drain 211. The retard port 240 communicates with each of the retard
oil pressure chambers, and the advance port 241 communicates with
each of the advance oil pressure chambers. Within the outer
peripheral wall of the housing 231, a communication passage 243
through which the advance port 241 communicates with the
communication port 242.
[0059] The ECU 300 controls the amount of the electric current to
be supplied to the coil 223, thereby controlling the position of
movement of the spool 213. With the increase in the amount of
current to be supplied to the coil 223, the spool 213 moves toward
the stationary core 222, that is, leftwardly in FIG. 5. When the
maximum amount of current is supplied to the coil 223, the spool
213 is in a position shown in FIG. 5 against the urging force of
the spring 214. At this time, the retard port 240 communicates with
the drain port 233, and the advance port 241 communicates with the
input port 232. The communication port 242 communicates with the
drain port 234. The advance port 241 communicates with the
communication port 242 through the communication passage 243, so
that the oil is supplied by the oil pump 210 and is discharged from
each advance oil pressure chamber.
[0060] When the amount of the electric current supplied into the
coil 223 decreases more than the state shown in FIG. 5, the
magnetic force attracting the moving core 220 toward the stationary
core 222 decreases, and the spool 213 comes to a position shown in
FIG. 6. The retard port 240 communicates with the drain port 233,
and the advance port 241 communicates with the input port 232.
However, the communication port 242 is shut off from communication
with the drain port 234. Since the oil is supplied to the advance
oil pressure chamber and is not discharged, the oil pressure in the
advance oil pressure chamber increases.
[0061] When the coil 223 is de-energized, the spool 213 is urged by
the force of the spring 214 to a position shown in FIG. 7. The
retard port 240 communicates with the input port 232, and the
advance port 241 communicates with the drain port 234. The
communication port 242 is shut off from communication with the
drain port 234. Therefore, the oil pressure in each retard oil
pressure chamber increases, and the oil pressure in each advance
oil pressure chamber decreases.
[0062] The position of movement of the spool 213 is changed by
controlling the amount of the electric current supplied into the
coil 223, to adjust the oil pressure in each oil pressure chamber
and each retard oil pressure chamber, thereby controlling the
relative rotational position the vane rotor 15 with respect to the
shoe housing 12.
[0063] The use of the above-described oil supply structure enables
the supply of the operation oil from the oil pump 210 to the retard
oil pressure chambers 51, 52 and 53, the advance oil pressure
chambers 54, 55, and 56, and the oil pressure chambers 42, 45, and
also enables the discharge of the operation oil from each oil
pressure chamber to the drain 211.
[0064] Next, an operation of the valve timing adjusting device 1
will be explained.
[0065] When the ignition key is turned off to stop the engine, the
interruption of supply of the electric current to the ECU 300 is
retarded by the relay circuit. When the ECU 300 detects the
ignition key turned off, the ECU 300 turns on the power supply to
the linear solenoid 215, so that the valve section 213c will be
selected, thereby operating in the state shown in FIG. 6. The oil
is supplied to each advance oil pressure chamber and the oil
pressure chamber 45, and each retard oil pressure chamber and the
oil pressure chamber 42 open to the drain. Therefore, the vane
rotor 15 rotates to the advance side with respect to the shoe
housing 12. An advance control means in the present invention
includes the ECU 300 and the changeover valve 212.
[0066] The oil passage 48 does not communicate with the recess
space 49 even when the stopper piston 32 has reached the
intermediate position in which the stopper piston 32 fits in the
fitting hole 41 from the retard side. Therefore, the damper chamber
46 is tightly closed, thereby working as a damper. Therefore, the
stopper piston 32 does not move toward the fitting hole 41. When
the stopper piston 32 rotates to the advance side over the
intermediate position, the damper chamber 46 communicates with
advance oil pressure chamber 54 through the recess space 49, so
that the damper chamber 46 is opened and therefore does not work as
a damper.
[0067] When the damper chamber 46 is opened, the stopper piston 32
is moved by the urging force of the spring 37 toward the fitting
hole 41. On the way of movement of the stopper piston 32 toward the
fitting hole 41, the large-diameter portion 34 shuts off a
communication between the through hole 30a and the oil pressure
chamber 45. However, the oil pressure chamber 45 communicates with
the oil pressure chamber 42 through grooves formed on the inner
peripheral wall of the first small-diameter portion 33 and on the
inner peripheral wall of the guide ring 30, so that the oil
pressure chamber 45 is not hermetically sealed. Therefore, the
hydraulic fluid chamber 45 does not work as a damper chamber. When
the oil pressure chamber 45 communicates with the oil pressure
chamber 42, no advance oil pressure is not applied to the oil
pressure chamber 45. Therefore, the stopper piston 32 is rapidly
moved by the advance oil pressure in the damper chamber 46 toward
the fitting member 40. The stopper piston 32 that has moved toward
the fitting member 40 first fits in the enlarged hole 43. Then, the
vane rotor 15 rotates to the retard side due to the load torque
which the camshaft 2 receives until the engine stops, and the
stopper piston 32 fits in the fitting hole 41.
[0068] When the stopper piston 32 fits in the fitting hole 41
before an engine startup, the phase difference of the vane rotor 15
with respect to the shoe housing 12, that is, the phase difference
of the camshaft 2 with respect to the crankshaft, is held at the
optimum phase for starting the engine. Thus, the engine can
reliably start up within a short time.
[0069] When the engine is started during a cold state and when the
engine is stopped before the operation oil temperature rises, the
operation oil is low in temperature and has high viscosity.
Therefore, when the vane rotor 15 is rotated to the advance side
over the intermediate position with respect to the shoe housing 12
when the engine is stopped, the engine might stall due to the
operation oil viscosity before the vane rotor 15 reaches the
intermediate position. That is, the engine stalls when the vane
rotor 15 is positioned at the advance side over the intermediate
position with respect to the shoe housing 12.
[0070] When the engine is left unstarted after a stall, the
operation oil might leak out at the seal and might not be filled in
each oil pressure chamber and the oil passage. Therefore, when the
engine is started when the stopper piston 32 remains out of the
fitting hole 41, the vane rotor 15 is turned to the retard side by
the load torque acting on the camshaft 2, thereby allowing the
stopper piston 32 to fit in the fitting hole 41.
[0071] However, when the engine is started immediately from the
state that the vane rotor 15 is positioned at the advance side over
the intermediate position with respect to the shoe housing 12, the
oil pressure in each advance oil pressure chamber rises immediately
because the oil passage and each advance oil pressure chamber are
full of the operation oil. Therefore, the vane rotor 15 does not
rotate to the retard side even when the load torque at the time of
engine startup acts on the vane rotor 15. Thus, the engine starts
when the vane rotor 15 is at the advance side over the intermediate
position with respect to the shoe housing 12, that is, when the
camshaft 2 is at the advance side over the intermediate position
with respect to the crankshaft. For example, when the engine is
started at an advanced valve timing of intake valve, the valve
timings to open the intake and exhaust valves overlap each other,
thereby resulting in a failure of engine startup.
[0072] In the first embodiment, however, the valve section 213d is
selected for a predetermined period by an instruction from the ECU
300 at the engine start. In this state, the operation oil is
discharged from each advance oil pressure chamber while being
supplied to each advance oil pressure chamber, and at the same time
the operation oil is discharged from each retard oil pressure
chamber. Also, the fluid passage area of the changeover valve 212
through which the drain port 234 and the communication port 242 are
connected is smaller, or slightly smaller, than that of the
changeover valve 212 connecting the input port 232 with the advance
port 241. Therefore, the oil pressure is low although the operation
oil is filled in each advance oil pressure chamber. When the engine
is started while the vane rotor 15 is positioned at the advance
side over the intermediate position with respect to the shoe
housing 12, the vane rotor 15 rotates to the retard side with
respect to the shoe housing 12 when the load torque on the retard
side is applied, because the oil pressure in each advance oil
pressure chamber is low. Then, when the vane rotor 15 reaches the
intermediate position, the stopper piston 32 fits in the fitting
hole 41, thereby holding the rotational position of the vane rotor
15 with respect to the shoe housing 12 at the intermediate
position, and accordingly properly stating the engine.
[0073] After engine startup with the valve section 213d selected
for a predetermined time, the ECU 300 selects the valve section
213c. The operation oil is supplied to each advance oil pressure
chamber and the oil pressure chamber 45, and each retard oil
pressure chamber and the oil pressure chamber 42 are opened to the
drain. However, the stopper piston 32 remains in the fitting hole
41 until the advance oil pressure reaches a predetermined pressure,
so that the relative rotation of the vane rotor 15 is locked with
respect to the shoe housing 12.
[0074] After the engine is started, when the oil pressure in each
advance oil pressure chamber and the oil pressure chamber 45
increases to a predetermined pressure, the stopper piston 32 goes
out of the fitting hole 41, thereby allowing the relative rotation,
that is, the phase control, of the vane rotor 15 with respect to
the shoe housing 12.
[0075] After the engine startup, when the oil pressure increases
sufficiently, any one of the valve sections 213a, 213b, and 213c of
the spool 213 is selected by an instruction of the ECU 300. By
this, supply of the operation oil to each oil pressure chamber and
draining of the oil from each oil pressure chamber is controlled,
and the relation rotation of the vane rotor 15 with respect to the
shoe housing 12 is controlled.
[0076] In the first embodiment, when the engine is started in a low
oil pressure, the stopper piston 32 might sometimes come out of the
fitting hole 41 due to oil pressure fluctuation. However, since
each advance hydraulic fluid chamber is full of the operation oil,
the vane rotor 15 does not suddenly rotate to the retard side even
when the camshaft 2 receives the load torque. Therefore, the vane
rotor 15 is prevented from hitting against the shoe housing 12.
Furthermore, since the operation oil is circulating in each advance
chamber and oil passage, sliding surfaces of these members are
lubricated, thereby preventing seizure of sliding portions during
engine startup operation.
[0077] In the first embodiment, when the ignition key is turned off
to stop the engine, electric power supply to the ECU 300 is
continued for a predetermined period, so that the ECU 300 energizes
the linear solenoid 215, thereby selecting the valve section 213d
to supply the operation oil to each advance oil pressure chamber to
perform an advance control. Alternatively, it is possible to
accomplish the advance control by adopting such an oil supply
structure that when the valve section 213c is selected, the
operation oil is supplied to each advance oil pressure chamber, and
when the valve section 213a is selected, the operation oil is
supplied to each retard oil pressure chamber. In this case, when
the supply of the electric current to the ECU 300 is interrupted
simultaneously with turning off the ignition key, the valve section
213c is selected by the urging force of the spring 214, and the
operation oil is supplied to each advance oil pressure chamber.
[0078] Second Embodiment
[0079] The second embodiment of the present invention is shown in
FIG. 8. In a changeover valve 250 of the second embodiment, the
retard port 240, advance port 241, and communication port 242 are
axially arranged in a reversed order of the first embodiment. The
changeover valve 250 is substantially the same in other structure
as the first embodiment.
[0080] When supply of the electric current to the coil 223 is
interrupted, the spool 213 is moved to the position shown in FIG. 8
by the urging force of the spring 214. Then, the input port 232
communicates with the advance port 241, and the communication port
242 communicates with the drain port 233. The retard port 240
communicates with the drain port 234. Therefore, in such an
electric system failure that the supply of the electric current to
the coil 223 from the ECU 300 fails, the operation oil is
discharged from each advance oil pressure chamber while being
supplied to each advance oil pressure chamber, and the operation
oil is discharged from each retard oil pressure chamber.
[0081] For example, when the valve timing of the intake valve is
controlled by the valve timing adjusting device which has the
changeover valve 250, the operation oil is discharged from each
advance oil pressure chamber while being supplied to each advance
oil pressure chamber in the event of a failure, thereby preventing
the valve timing of the intake valve from becoming the most
retarded timing.
[0082] Third Embodiment
[0083] The third embodiment of the present invention is shown in
FIGS. 9-12. Substantially same members as those in the first
embodiment are designated by the same reference numerals.
[0084] The changeover valve 250 of the third embodiment is of the
same configuration as the changeover valve 250 of the second
embodiment, with the exception that the retard port 240 of the
second embodiment is the advance port 241 in the third embodiment,
and the advance port 241 of the second embodiment is the retard
port 240 in the third embodiment. The retard port 240 communicates
with the communication port 242 through the communication passage
243 formed on the outer peripheral wall of the housing 251.
[0085] FIG. 10 shows a de-energized state of the coil 223. The
spool 213 comes to the position shown in FIG. 12 due to the urging
force of the spring 214. The retard port 240 communicates with the
input port 232, and the communication port 242 communicates with
the drain port 233. The advance port 241 communicates with the
drain port 234. Therefore, the operation oil is discharged from
each retard oil pressure chamber while being supplied to each
retard oil pressure chamber, and also being discharged from each
advance oil pressure chamber. The fluid passage area of the
changeover valve 250 connecting between the drain port 233 and the
communication port 242 is smaller, or a little smaller, than the
fluid passage area of the changeover valve 250 connecting between
the inlet port 232 and the retard port 240. Therefore, the
operation oil pressure remains low though the oil is filled in each
retard oil pressure chamber.
[0086] When the coil 223 is energized, the spool 213 comes to the
position shown in FIG. 11. The retard port 240 communicates with
the input port 232, and the communication port 242 is shut off from
communication with the drain port 233. The advance port 241
communicates with the drain port 234. Therefore the oil pressure in
each retard oil pressure chamber increases.
[0087] When the maximum electric current is supplied to the coil
223, the spool 213 comes to the position shown in FIG. 12. At this
time, the retard port 240 communicates with the drain port 233, and
the communication port 242 is shut off from communication with the
drain port 233. The advance port 241 communicates with the input
port 232. Therefore, the oil pressure in each advance oil pressure
chamber increases.
[0088] Fourth Embodiment
[0089] The fourth embodiment of the present invention is shown in
FIG. 13. The changeover valve 212 of the fourth embodiment is of
the same configuration as the changeover valve 212 of the first
embodiment. However, the retard port 240 of the first embodiment is
the retard port 241 of the fourth embodiment, and the advance port
241 of the first embodiment is the retard port 240 in the fourth
embodiment. The retard port 240 communicates with the communication
port 242 through the communication passage 243 formed on the outer
peripheral wall of the housing 251.
[0090] When the coil 223 is de-energized, the spool 213 is moved by
the urging force of the spring 214 to the position shown in FIG.
13. The retard port 240 communicates with the drain port 234, and
the communication port 242 is shut off from communication with the
drain port 234. The advance port 241 communicates with the input
port 232. Therefore, in the event of such a failure as
disconnection of the coil 223 and inability to supply the electric
current to the coil 223, the operation oil is supplied to each
advance oil pressure chamber, and simultaneously is discharged from
each retard oil pressure chamber. Therefore, the valve timing is
prevented from becoming to the most retarded angle at the failure
of the electric system.
[0091] In the above-described first through fourth embodiments, the
retard port 240 or the advance port 241 and the communication port
242 are connected by a communication passage 243 formed on the
outer peripheral wall of the housing of the changeover valve.
Therefore, there is no need to form a communication passage in
other part for connecting the advance port 240 or the advance port
241 with the communication port 242.
[0092] Fifth Embodiment
[0093] The fifth embodiment of the present invention is shown in
FIG. 14, in which substantially same members as those in the first
embodiment are designated by the same reference numerals.
[0094] A changeover valve 270 and a changeover valve 280 are
electromagnetically-driven valve devices having a spool 271 and a
spool 280 respectively, and forming a changeover means. During
normal engine operation, the supply of the electric current to a
solenoid 283 of the changeover valve 280 is interrupted, and a
valve section 281 of the changeover valve 280 is selected.
Therefore, it is possible to control the oil pressure in each
advance oil pressure chamber and each retard oil pressure chamber
by selecting valve sections 271a, 271b, and 271c of the spool 271
through the control of the electric current to be supplied to a
solenoid 273 of the changeover valve 271.
[0095] At the engine start, the electric current is supplied to the
solenoid 273 of the changeover valve 270 for a predetermined period
to select the valve section 271c against the urging force of a
spring 272. At the same time, the electric current is also supplied
to the solenoid 283 of the changeover valve 280 to select the valve
section 281b against the urging force of a spring 282. Then, the
operation oil is supplied to each advance oil pressure chamber
while being discharged from each advance oil pressure chamber, and
also from each retard oil pressure chamber.
[0096] Modifications
[0097] In the above-described embodiments of the present invention,
the enlarged hole 43 was formed in the fitting member 40 in
addition to the fitting hole 41. Alternatively, there may be
provided only the fitting hole 41 without forming the enlarged hole
43.
[0098] In the above-described embodiments, the valve timing
adjusting device for driving the intake valve was explained.
Alternatively, only the exhaust valve or both the intake valve and
the exhaust valve may be driven by the valve timing adjusting
device in the embodiments.
[0099] In the above-described embodiments, the stopper piston moves
axially to fit into the fitting hole. Alternatively, the stopper
piston may move radially to fit into the fitting hole. Further, the
stopper piston may be held within the housing member, and a fitting
hole and an enlarged hole may be formed within the vane rotor.
[0100] In the above-described embodiments, the rotation of the
crankshaft is transmitted to the camshaft through the chain
sprocket. Alternatively, a timing pulley or a timing gear may be
used. Further, a vane may receive a driving force of the crankshaft
as a driving shaft, and the camshaft as a driven shaft and the
housing member may be rotated with together.
* * * * *