Valve timing control apparatus

A springless check valve enables flow of hydraulic fluid from a supply port toward a corresponding one of an advancing port and a retarding port in a connection passage upon lifting of a valve member from a valve seat and limits flow of the hydraulic fluid from the corresponding one of the advancing port and the retarding port toward the supply port upon seating of the valve member against the valve seat. In a synchronously rotatable member, a drain passage is circumferentially displaced from the drain port, and an advancing passage is placed at a corresponding circumferential position, which coincides with a circumferential position of the advancing port. Furthermore, a retarding passage is placed at a corresponding circumferential position, which coincides with a circumferential position of the retarding port.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2010-276009 filed on Dec. 10, 2010 and Japanese Patent Application No. 2010-276010 filed on Dec. 10, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve timing control apparatus of an internal combustion engine.

2. Description of Related Art

A previously proposed valve timing control apparatus includes a housing, which is rotated synchronously with a crankshaft, and a vane rotor, which is rotated synchronously with a camshaft. For example, Japanese Unexamined Patent Publication JP2005-325841A (corresponding to U.S. Pat. No. 7,533,695 B2) teaches such a valve timing control apparatus, which changes the rotational phase of the vane rotor relative to the housing toward one of an advancing side and a retarding side by supplying hydraulic fluid into a corresponding one of an advancing chamber and a retarding chamber, which are arranged one after another in a rotational direction and are partitioned by the vane rotor in an inside of the housing. This valve timing control apparatus has a control valve, which controls input and output of the hydraulic fluid relative to the advancing chamber and the retarding chamber.

Specifically, during an operation in a phase change mode (advancing mode or retarding mode) for changing the rotational phase, the control valve feeds the hydraulic fluid, which is supplied from a supply source to a supply port of the control valve, to one of the advancing chamber and the retarding chamber through a feed port (advancing port or retarding port) connected to the supply port. At this time, in a connection passage, which connects the supply port to the feed port, a check valve is operated in response to alternation in an oscillating torque, which is applied from the camshaft to the vane rotor.

First of all, when the oscillating torque is exerted in a direction for increasing a volume of a subject one of the advancing chamber and the retarding chamber, to which the hydraulic fluid is fed from the feed port, a negative pressure is generated in the subject one of the advancing chamber and the retarding chamber. Therefore, in the connection passage, which is connected to the subject one of the advancing chamber and the retarding chamber, the flow of the hydraulic fluid from the supply port to the feed port is enabled by the check valve. Therefore, the hydraulic fluid, which is supplied from the supply source to the supply port, is fed to the subject one of the advancing chamber and the retarding chamber through the feed port, so that the rotational phase of the vane rotor relative to the housing is changed. In contrast, when the oscillating torque is exerted in a direction for reducing the volume of the subject one of the advancing chamber and the retarding chamber, the hydraulic fluid of the subject one of the advancing chamber and the retarding chamber is discharged to the connection passage through the feed port. Thus, in the connection passage, the flow of the hydraulic fluid from the feed port to the supply port is limited by the check valve. Thereby, returning of the rotational phase, which would be caused by the discharge of the hydraulic fluid from the subject one of the advancing chamber and the retarding chamber, is limited.

In JP2005-325841A (corresponding to U.S. Pat. No. 7,533,695 B2), the check valve of the control valve is a spring equipped check valve, in which a valve member is urged by a spring against a valve seat. Therefore, a valve closing speed of the check valve at the time of seating the valve member against the valve seat using a restoring force of the spring is high. However, a valve opening speed of the check valve at the time of lifting the valve member away from the valve seat against the restoring force of the spring is low. Furthermore, the valve member of the check valve of the valve timing control apparatus recited in JP2005-325841A (corresponding to U.S. Pat. No. 7,533,695 B2) is formed as a solid spherical ball. Therefore, in the lifted state of the valve member away from the valve seat, when the hydraulic fluid, which flows toward the feed port in the connection passage, collides against the valve member, a substantial reduction in the amount of pressure loss of the hydraulic fluid may possibly occur. Thereby, the supply of the hydraulic fluid to the subject one of the advancing chamber and the retarding chamber may be delayed, thereby resulting in a reduction in a response speed for adjusting the valve timing, which corresponds to the rotational phase.

Furthermore, Japanese Unexamined Patent Publication JP2009-138611A (corresponding to US2009/0145386A1) teaches another valve timing control apparatus. In this valve timing control apparatus, a sleeve has a supply port, a drain port, an advancing port and a retarding port. The supply port receives the hydraulic fluid from a supply source. The drain port is open to the atmosphere and discharges the hydraulic fluid. The hydraulic fluid is fed to or discharged from the advancing chamber through the advancing port. Also, the hydraulic fluid is fed to or discharged from the retarding chamber through the retarding port. During the operation of the valve timing control apparatus in an advancing mode, which changes the rotational phase to an advancing side, the advancing port and the supply port are communicated with each other to feed the hydraulic fluid to the advancing chamber, and the retarding port is communicated with the drain port to discharge the hydraulic fluid from the retarding chamber. During the operation of the valve timing control apparatus in a retarding mode, which changes the rotational phase to a retarding side, the retarding port and the supply port are communicated with each other to feed the hydraulic fluid to the retarding chamber, and the advancing port is communicated with the drain port to discharge the hydraulic fluid from the advancing chamber.

In the valve timing control apparatus of JP2009-138611A (corresponding to US2009/0145386A1), the drain port, which is formed in the sleeve of the control valve received in the camshaft on the radially inner side of the vane rotor, is opened to the atmosphere through a drain passage that extends through the camshaft. The drain port, which is displaced from the advancing port and the retarding port in the axial direction of the sleeve, is formed such that a circumferential position of the drain port in a circumferential direction of the sleeve coincides with a circumferential position of the drain passage. Therefore, a length of a discharge passage of the hydraulic fluid from the retarding port or the advancing port to the drain passage may possibly become insufficient to cause a reduction in the amount of pressure loss in the discharge passage during the operation in the advancing mode or the retarding mode. In such a case where the amount of the pressure loss at the discharge passage is reduced, i.e., becomes small, an excessive quantity of the hydraulic fluid is discharged from the corresponding one of the advancing chamber and the retarding chamber through the discharge passage. Thereby, a negative pressure is generated in the other one of the advancing chamber and the retarding chamber, to which the hydraulic fluid is currently fed, due to an increase in the volume of the other one of the advancing chamber and the retarding chamber. When the air is drawn into the other one of the advancing chamber and the retarding chamber, an apparent elastic modulus of a mixture of the air and the hydraulic fluid becomes small in the other one of the advancing chamber and the retarding chamber to cause fluctuating movement of the vane rotor. Therefore, it is difficult to achieve a high response speed for adjusting the valve timing, which corresponds to the rotational phase.

Furthermore, in the valve timing control apparatus of JP2009-138611A (corresponding to US2009/0145386A1), an advancing passage extends through the vane rotor and the camshaft to communicate between the advancing chamber and the advancing port, and the advancing port is displaced from the advancing passage in the circumferential direction of the sleeve. Therefore, during the operation in the retarding mode, the amount of pressure loss is increased in the discharge passage, which extends from the advancing passage to the advancing port, so that the response speed for adjusting the valve timing can be improved. However, during the operation in the advancing mode, this discharge passage is used as a feed passage of the hydraulic fluid, which extends from the advancing port to the advancing passage, and the increased amount of pressure loss in this feed passage disadvantageously causes a reduction in the response speed for adjusting the valve timing.

SUMMARY OF THE INVENTION

The present invention is made in view of the above disadvantages. Thus, it is an objective of the present invention to provide a valve timing control apparatus, which improves a response speed for adjusting valve timing.

According to the present invention, there is provided a valve timing control apparatus, which includes a housing, a vane rotor and a control valve. The housing is rotatable synchronously with a crankshaft of an internal combustion engine. The vane rotor is rotatable synchronously with a camshaft of the internal combustion engine. The vane rotor partitions between an advancing chamber and a retarding chamber in a rotational direction in an inside of the housing. A rotational phase of the vane rotor relative to the housing is changeable in one of an advancing side and a retarding side by feeding hydraulic fluid, which is supplied from a supply source, into a corresponding one of the advancing chamber and the retarding chamber. The control valve controls input and output of the hydraulic fluid relative to the advancing chamber and the retarding chamber. Valve timing of a valve, which is opened or closed by the camshaft, is adjusted by transmission of a torque from the crankshaft. The control valve includes a supply port, a feed port, a connection passage and a springless check valve. The hydraulic fluid is supplied to the supply port from the supply source during an operation in a phase change mode, which changes the rotational phase. The hydraulic fluid is fed to the one of the advancing chamber and the retarding chamber through the feed port during the operation in the phase change mode. The connection passage is connected to the supply port and the feed port during the operation in the phase change mode. The springless check valve enables flow of the hydraulic fluid from the supply port toward the feed port in the connection passage upon lifting of a valve member from a valve seat at the springless check valve during the operation in the phase change mode and limits flow of the hydraulic fluid from the feed port toward the supply port in the connection passage upon seating of the valve member against the valve seat during the operation in the phase change mode. The valve member includes a spherical plate portion, an annular ring portion and a plurality of bridge portions. The spherical plate portion includes a convex plate surface and a concave plate surface, which are opposed to each other and are configured into partial spherical surfaces, respectively, each having a circular outer peripheral edge. The convex plate surface is seatable and liftable relative the valve seat. The annular ring portion includes an inner peripheral surface and an outer peripheral surface. The inner peripheral surface of the annular ring portion has a diameter larger than that of the spherical plate portion. The outer peripheral surface of the annular ring portion is guided by a wall surface of the connection passage. The bridge portions are spaced from each other in a circumferential direction. The bridge portions coaxially connect the annular ring portion to the spherical plate portion.

According to the present invention, there is also provided a valve timing control apparatus, which includes a housing, a vane rotor and a control valve. The housing is rotatable synchronously with a crankshaft of an internal combustion engine. The vane rotor is rotatable synchronously with a camshaft of the internal combustion engine and thereby cooperates with the camshaft to form a synchronously rotatable member. The vane rotor partitions between an advancing chamber and a retarding chamber in a rotational direction in an inside of the housing. A rotational phase of the vane rotor relative to the housing is changeable in one of an advancing side and a retarding side by feeding hydraulic fluid, which is supplied from a supply source, into a corresponding one of the advancing chamber and the retarding chamber. The control valve is received in the synchronously rotatable member and controls input and output of the hydraulic fluid relative to the advancing chamber and the retarding chamber in response to an operational position of a spool, which is received in a sleeve. Valve timing of a valve, which is opened or closed by the camshaft, is adjusted by transmission of a torque from the crankshaft. The sleeve includes a supply port, a drain port, an advancing port and a retarding port. The hydraulic fluid is supplied from the supply source to the supply port. The drain port is opened to atmosphere, and the hydraulic fluid is discharged from the drain port. The advancing port is adapted to be communicated with the supply port to feed the hydraulic fluid to the advancing chamber during an operation in an advancing mode, which changes the rotational phase toward an advancing side. The advancing port is adapted to be communicated with the drain port to discharge the hydraulic fluid from the advancing chamber during an operation in a retarding mode, which changes the rotational phase toward a retarding side. The retarding port is adapted to be communicated with the supply port to feed the hydraulic fluid to the retarding chamber during the operation in the retarding mode. The retarding port is adapted to be communicated with the drain port to discharge the hydraulic fluid from the retarding chamber during the operation in the advancing mode. The drain port, the advancing port and the retarding port are displaced from each other in an axial direction of the sleeve. The synchronously rotatable member includes a drain passage, an advancing passage and a retarding passage. The drain passage is circumferentially displaced in a circumferential direction of the sleeve from the drain port, which is located on a radially inner side of the drain passage. The drain passage is formed as a through-hole and opens the drain port to the atmosphere. The advancing passage is placed in the circumferential direction of the sleeve at a corresponding circumferential position, which coincides with a circumferential position of the advancing port located on a radially inner side of the advancing passage. The advancing passage is formed as a through-hole and communicates the advancing port to the advancing chamber. The retarding passage is placed in the circumferential direction of the sleeve at a corresponding circumferential position, which coincides with a circumferential position of the retarding port located on a radially inner side of the retarding passage. The retarding passage is formed as a through-hole and communicates the retarding port to the retarding chamber.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described with reference to the accompanying drawings.FIG. 1shows a valve timing control apparatus1of the present embodiment installed to an internal combustion engine of a vehicle (e.g., an automobile). The valve timing control apparatus1is a hydraulically controlled type, which uses hydraulic oil as hydraulic fluid (also referred to as working fluid). The valve timing control apparatus1adjusts the valve timing of intake valves.

Hereinafter, a basic structure of the valve timing control apparatus1will be described. As shown inFIGS. 1 and 2, the valve timing control apparatus1includes a drive device10and a control device30. The drive device10is installed in a transmission system that transmits an engine torque, which is outputted from a crankshaft (not shown) of the engine, to a camshaft2. The control device30controls input and output of the hydraulic oil, which drives the drive, device10.

The drive device10includes a housing11and a vane rotor15. The housing11includes a shoe casing12, a front plate13and a rear plate14. The front plate13and the rear plate14are securely connected to two opposed axial end portions, respectively, of the shoe casing12. The shoe casing12includes a casing main body12a, a plurality of shoes12band a sprocket portion12c. The shoes12bare arranged one after another at predetermined intervals in a rotational direction (circumferential direction) of the casing main body12a, which is configured into a cylindrical tubular form, and the shoes12bradially inwardly project from the casing main body12a. A receiving chamber20is formed between each adjacent two of the shoes12b, which are adjacent to each other in the rotational direction.

The sprocket portion12cis connected to the crankshaft through a timing chain (not shown). When the engine is driven to rotate the crankshaft, the engine torque is transmitted from the crankshaft to the sprocket portion12c. Therefore, the housing11is rotated synchronously with the crankshaft in a predetermined direction (clockwise direction inFIG. 2).

The vane rotor15is placed in an inside of the housing11such that the vane rotor15is coaxial with the housing11. The vane rotor15includes a rotatable shaft15aand a plurality of vanes15b. The rotatable shaft15a, which is configured into a cylindrical tubular form, is coaxially fixed to the camshaft2. Thereby, the vane rotor15is rotatable synchronously with the camshaft2in the predetermined direction (clockwise direction inFIG. 2) and is rotatable relative to the housing11. The vanes15bare arranged one after another at predetermined intervals along the rotatable shaft15aand radially outwardly project from the rotatable shaft15a, so that the vanes15bare received in the receiving chambers20, respectively. Each vane15bdivides the corresponding receiving chamber20into an advancing chamber22and a retarding chamber23, which are placed one after another in the rotational direction. Thereby, the multiple advancing chambers22and the multiple retarding chambers23are formed in the inside of the housing11. In the present embodiment, each vane15bforms the advancing chamber22relative to the adjacent shoe12blocated on a rear side of the vane15bin the rotational direction and also forms the retarding chamber23relative to the other adjacent shoe12blocated on a front side of the vane15bin the rotational direction.

One of the vanes15bhas a lock member16. When the engine is stopped, the lock member16is fitted into a lock hole14aof the rear plate14, so that a rotational phase of the vane rotor15relative to the housing11is locked. At the time of starting the engine, the lock member16is removed from the lock hole14a, so that a change in the rotational phase of the vane rotor15relative to the housing11is enabled during the time of steady operation of the engine.

With the above structure, at the time of steady operation of the engine, the rotational phase of the vane rotor15is changed by inputting or outputting the hydraulic oil relative to each corresponding advancing chamber22and each corresponding retarding chamber23, and thereby the valve timing, which corresponds to the rotational phase, is implemented. Specifically, the rotational phase of the vane rotor15is changed to the advancing side thereof by inputting the hydraulic oil into each advancing chamber22to increase the volume of the advancing chamber22and outputting the hydraulic oil from each retarding chamber23to reduce the volume of the retarding chamber23. Thereby, the valve timing is advanced. In contrast, the rotational phase of the vane rotor15is changed to the retarding side thereof by inputting the hydraulic oil into each retarding chamber23to increase the volume of the retarding chamber23and outputting the hydraulic oil from each advancing chamber22to reduce the volume of the advancing chamber22. Thereby, the valve timing is retarded.

With reference toFIGS. 1 to 4, the control device30includes a supply passage40, a plurality of drain passages41, a plurality of advancing passages42, a plurality of retarding passages43, a control valve50and a control circuit90. The supply passage40is communicated with an outlet of a pump (serving as a supply source)4. Thus, the hydraulic oil, which is drawn from a drain pan5into an inlet of the pump4, is discharged into the supply passage40through the outlet of the pump4. The pump4is a mechanical pump, which is driven by the rotation of the crankshaft of the engine. During the rotation of the pump4, the hydraulic oil is continuously supplied from the pump4to the supply passage40. The hydraulic oil can be drained from the drain passages41into the drain pan (serving as a drain recovery storage)5, and the drain passages41and the drain pan5are both open to the atmosphere. Each of the advancing passages42is communicated with a corresponding one of the advancing chambers22. Each of the retarding passages43is communicated with a corresponding one of the retarding chambers23.

The control valve50is a solenoid spool valve, which includes a spool53that is received in a sleeve54and is reciprocated in the sleeve54by a drive force generated from a solenoid51upon energization thereof and a restoring force generated by a spring52. Supply ports60, drain ports61, advancing ports (also referred to as feed ports)62and retarding ports (also referred to as feed ports)63are formed in the sleeve54of the control valve50. The supply ports60are communicated with the supply passage40. The drain ports61are communicated with the drain passages41. Furthermore, the advancing ports62are communicated with the advancing passages42, and the retarding ports63are communicated with the retarding passages43. At the control valve50, an axial moving position (axial position), i.e., an operational position (hereinafter, also simply referred to as a spool position) of the spool53is changed in response to the energization of the solenoid51to change the connecting state of each of these ports60-63.

The control circuit90is an electronic circuit, which includes, for example, a microcomputer as its main component. The control circuit90is electrically connected to the control valve50, the solenoid51and the various electric components (not shown) of the engine. The control circuit90controls the energization of the solenoid51and the rotation of the engine through a computer program stored in an internal memory of the control circuit90.

Next, an oscillating torque applied to the vane rotor15will be described.

During the rotation of the engine, the oscillating torque is generated at the camshaft2due to a spring reaction force applied from the intake valves, which are opened or closed by the camshaft2. This oscillating torque is transmitted to the vane rotor15of the drive device10through the camshaft2. As shown inFIG. 5, the oscillating torque is an alternating torque that changes between a negative torque, which is exerted to the vane rotor15in an advancing direction relative to the housing11, and a positive torque, which is exerted to the vane rotor15in a retarding direction relative to the housing11.

An absolute value of a peak (peak torque) T+ of the positive torque may be larger than an absolute value of a peak (peak torque) T− of the negative torque, so that the average (average torque) of the oscillating torque may be biased on the positive torque side. Alternatively, the absolute value of the peak T+ of the positive torque may be substantially equal to the absolute value of the peak T− of the negative torque, so that the average (average torque) may become substantially zero.

Next, the detail of the structure of the valve timing control apparatus1will be described.

As shown inFIGS. 1 and 2, the camshaft2coaxially extends through the vane rotor15from the rear plate14side to the front plate13side. A projecting portion2aof the camshaft2, which projects from the front plate13, is supported by a bearing6of the engine. The camshaft2includes an axial hole2b, which is configured into a cylindrical hole and opens in an end surface of the projecting portion2a. The sleeve54, which is configured into a cylindrical tubular form, is coaxially inserted into the axial hole2b, so that the portion of the control valve50is received in the camshaft2on a radially inner side of the vane rotor15.

In the present embodiment, a fixing portion2cof the camshaft2made of metal is located on a rear plate14side of the projecting portion2aand is securely press fitted into the rotatable shaft15aof the vane rotor15made of metal. Furthermore, the spool53made of metal and the spring52made of metal are received in the sleeve54made of metal, and the sleeve54is threadably fixed to the hole2bof the camshaft2. Since the sleeve54is fixed in the above describe manner, the sleeve54is rotated integrally with the camshaft2and the vane rotor15, which forms a synchronously rotatable member17, and also with the spool53and the spring52, which form the received member. Therefore, the spool53is slidably rotatable relative to a drive shaft51aof the solenoid51, which is installed to a stationary member (e.g., a chain cover) of the engine and drives the spool53to reciprocate the spool53along the axis.

The sleeve54of the control valve50includes the ports60-63, each of which is provided in the predetermined corresponding number. As shown inFIG. 6, the supply ports60are arranged one after another at predetermined intervals in a circumferential direction of the sleeve54. Each supply port60is communicated with the supply passage40(see alsoFIG. 1), which extends through the projecting portion2aof the camshaft2and the bearing6, through a supply opening70, which is configured as an annular groove that opens in the outer peripheral surface54aof the sleeve54.

As shown inFIGS. 2 and 6, in the sleeve54, the drain ports61are placed at an axial location, which is displaced from the supply ports60in the axial direction of the sleeve54, such that the drain ports61are arranged one after another at predetermined intervals in the circumferential direction of the sleeve54. Each drain port61is communicated with the drain passages41(see alsoFIG. 1), which extend through the projecting portion2aof the camshaft2and the bearing6, through a drain opening71, which is configured as an annular groove that opens in the outer peripheral surface54aof the sleeve54. In the present embodiment, the drain passages41are located on the radially outer side of the drain ports61, and each of the drain ports61is displaced from all of the drain passages41in the circumferential direction of the sleeve54.

As shown inFIGS. 3 and 6, the advancing ports62are placed at an axial location, which is displaced from the drain ports61in the axial direction of the sleeve54, such that the advancing ports62are arranged one after another at predetermined intervals in the circumferential direction of the sleeve54. Each advancing port62is communicated with the advancing passages42(see alsoFIG. 1), which extend through the fixing portion2cof the camshaft2and the rotatable shaft15aof the vane rotor15and are respectively configured as a hole, through an advancing opening72, which is configured as an annular groove that opens in the outer peripheral surface54aof the sleeve54. In the present embodiment, the advancing passages42are located on the radially outer side of the advancing ports62, and each of the advancing ports62is placed in the circumferential direction of the sleeve54at a corresponding circumferential position, which coincides with a circumferential position of the corresponding one of the advancing passages42. Thereby, each of the advancing ports62and the corresponding advancing passage42are located along a corresponding imaginary radial line.

As shown inFIGS. 4 and 6, the retarding ports63are placed at an axial location, which is displaced from the drain ports61in the axial direction of the sleeve54on an axial side of the drain ports61that is opposite from the advancing ports62, such that the retarding ports63are arranged one after another at predetermined intervals in the circumferential direction of the sleeve54. Each retarding port63is communicated with the retarding passages43(see alsoFIG. 1), which extend through the fixing portion2cof the camshaft2and the rotatable shaft15aof the vane rotor15and are respectively configured as a hole, through a retarding opening73, which is configured as an annular groove that opens in the outer peripheral surface54aof the sleeve54.

In the present embodiment, with reference toFIG. 6, the axial location of each retarding port63and the axial location of each advancing port62are displaced from the axial location of each drain port61in the axial direction of the sleeve54. Specifically, the amount of axial positional displacement ΔRa between the axial location of the retarding port63and the axial location of the drain port61is substantially the same as the amount of axial positional displacement ΔAa between the axial location of the advancing port62and the axial location of the drain port61. The retarding passages43are located on the radially outer side of the retarding ports63, and each of the retarding ports63is placed in the circumferential direction of the sleeve54at a corresponding circumferential position, which coincides with a circumferential position of a corresponding one of the retarding passages43. Thereby, each of the retarding ports63and the corresponding retarding passage43are located along a corresponding imaginary radial line.

FIG. 11is a schematic diagram indicating the positional relationships among the drain passages41, the advancing passages42and the retarding passages43. More specifically,FIG. 11shows an axially projected shadow (axially projected area)42aof each of the advancing passages42, which is formed by axially projecting the advancing passage42on the drain passage41side, i.e., by axially projecting the advancing passage42on an imaginary plane that extends in a direction perpendicular to the axial direction of the sleeve54through the drain passages41.FIG. 11also shows an axially projected shadow (axially projected area)43aof each of the retarding passages43, which is formed by axially projecting the retarding passage43on the drain passage41side, i.e., by axially projecting the retarding passage43on the imaginary plane that extends in the direction perpendicular to the axial direction of the sleeve54through the drain passages41. As shown inFIG. 11, the axially projected shadow42aof each advancing passage42is located on one circumferential side of a corresponding one of the drain passages41, and the axially projected shadow43aof a corresponding one of the retarding passages43is located on the other circumferential side of this drain passage41. Thereby, each drain passage41is circumferentially held between the axially projected shadow42aof the corresponding advancing passage42and the axially projected shadow43aof the corresponding retarding passage43. In the present embodiment, the amount of circumferential positional displacement ΔAc between the axially projected shadow42aof the advancing passage42and the drain passage41measured in the circumferential direction of the sleeve54is substantially the same as the amount of circumferential positional displacement ΔRc between the axially projected shadow43aof the retarding passage43and the drain passage41measured in the circumferential direction of the sleeve54.

In the control valve50, as shown inFIG. 6, the spool53includes a communication passage55and a connection passage56. The communication passage55is configured as an annular groove that opens in the outer peripheral surface53aof the spool53. The connection passage56is configured as a cylindrical hole that has two end portions56a,56band an intermediate portion56clocated therebetween, and the end portions56a,56band the intermediate portion56cof the connection passage56are opened to the outer peripheral surface53aof the spool53.

With the above structure, at the operational position (axial position) of the spool53during the operation in the advancing mode A shown inFIGS. 7A and 7B, the communication passage55is connected to each drain port61and each retarding port63. Also, at the operational position of the spool53during the operation in the advancing mode A shown inFIGS. 7A and 7B, the one end portion56aof the connection passage56is connected to each supply port60, and the intermediate portion56cof the connection passage56is connected to each advancing port62. Furthermore, the other end portion56bof the connection passage56is closed by the sleeve54.

In contrast, at the operational position of the spool53during the operation in the retarding mode R shown inFIGS. 8A and 8B, the communication passage55is connected to each drain port61and each advancing port62. Also, at the operational position of the spool53during the operation in the retarding mode R, the one end portion56aof the connection passage56is connected to each supply port60, and the intermediate portion56cof the connection passage56is closed by the sleeve54. Furthermore, the other end portion56bof the connection passage56is connected to each retarding port63.

In the control valve50, as shown inFIGS. 1 to 4, a check valve80is installed in the connection passage56of the spool53. As shown inFIG. 6, in the present embodiment, the check valve80is a springless check valve and includes a valve seat81, a guide82, a stopper83and a valve member84.

The valve seat81is formed by a tapered surface (conical surface), which is formed by a wall surface56dof the connection passage56and has a progressively reducing diameter that is axially progressively reduced toward the one end portion56aof the connection passage56. The guide82is formed by a cylindrical surface of the wall surface56dof the connection passage56, which forms the intermediate portion56cand is located on an axial side of the valve seat81where the other end portion56bis located. The stopper83is formed by a step surface of the wall surface56dof the connection passage56, which is axially opposed to the valve seat81and is located on an axial side of the guide82where the other end portion56bis located. The valve member84is made of metal and is configured into a cylindrical tubular body having a bottom. The valve member84is received in the intermediate portion56cof the connection passage56at a location radially inward of the guide82, such that the valve member84is adapted to reciprocate in the axial direction.

In the present embodiment, the valve member84is formed by processing a metal plate through, for example, a press working process. As shown inFIGS. 6 and 9Ato9C, the valve member84includes a spherical plate portion85, an annular ring portion86and a plurality (three in this instance) of bridge portions87. The spherical plate portion85forms an axial end portion of the valve member84at the bottom side of the valve member84. The spherical plate portion85includes a convex plate surface (bottom surface)85aand a concave plate surface85b, which are axially opposed to each other. The convex plate surface85ais a partial spherical surface that is convex toward the valve seat81. The concave plate surface85bis a partial spherical surface that is concave toward the convex plate surface85a. The convex plate surface85aand the concave plate surface85bhave circular outer peripheral edges, respectively, which are coaxial with each other. A thickness of the spherical plate portion85, which is measured between the convex plate surface85aand the concave plate surface85b, is substantially uniform throughout the spherical plate portion85. In the present embodiment, the convex plate surface85ais adapted to seat against the valve seat81, which is coaxial with the convex plate surface85a, such that the convex plate surface85amakes line contact with the conical surface of the valve seat81.

As shown inFIGS. 6 and 9Ato9C, the annular ring portion86forms an axial end portion of the valve member84at an opening side of the valve member84, which is opposite from the bottom side of the valve member84. The annular ring portion86includes an outer peripheral surface86aand an inner peripheral surface86b. The outer peripheral surface86aof the annular ring portion86is a cylindrical surface that is guided by the guide82such that the outer peripheral surface86ais axially slidable along the guide82. The inner peripheral surface86bof the annular ring portion86is a cylindrical surface that has a diameter smaller than that of the outer peripheral surface86a. A thickness of the annular ring portion86, which is measured between the outer peripheral surface86aand the inner peripheral surface86b, is substantially uniform throughout the annular ring portion86and is substantially the same as that of the spherical plate portion85. In the annular ring portion86of the present embodiment, the diameter of the inner peripheral surface86b, which is coaxial with the spherical plate portion85having the circular outer peripheral edge, is made larger than the diameter of the spherical plate portion85. Therefore, as shown inFIG. 10, the inner peripheral surface86bis located on a radially outer side of an axially projected shadow, i.e., an axially projected area85c(see a cross-hatching shown inFIG. 10) of the spherical plate portion85, which is axially projected on the annular ring portion86side, i.e., is axially projected on an imaginary plane that extends in a direction perpendicular to the axial direction of the valve member84through the annular ring portion86.

As shown inFIGS. 6 and 9Ato9C, the three bridge portions87, which form an axial intermediate portion of the valve member84, are spaced from each other in the circumferential direction, i.e., are arranged one after another at generally equal intervals in the circumferential direction that is also the circumferential direction of the spherical plate portion85and the annular ring portion86, such that the bridge portions87coaxially connect the spherical plate portion85to the annular ring portion86. As shown inFIGS. 9A to 9C, each bridge portion87includes a first bridge plate portion88and a second bridge plate portion89, which are continuously formed one after another in the axial direction. The first bridge plate portion88is located adjacent to the spherical plate portion85in the axial direction, and the second bridge plate portion89is located adjacent to the annular ring portion86in the axial direction.

The first bridge plate portion88includes an outer peripheral surface88aand an inner peripheral surface88b, which are opposed to each other. The outer peripheral surface88ais continuous from the convex plate surface85aof the spherical plate portion85and is formed as a partial spherical surface. The inner peripheral surface88bis continuous from the concave plate surface85bof the spherical plate portion85and is formed as a partial spherical surface. A radius of curvature of the outer peripheral surface88aand a radius of curvature of the inner peripheral surface88bare substantially the same as the radius of curvature of the convex plate surface85aand the radius of curvature of the concave plate surface85b, respectively. Therefore, a thickness of the first bridge plate portion88, which is measured between the outer peripheral surface88aand the inner peripheral surface88b, is substantially uniform throughout the first bridge plate portion88and is substantially the same as the thickness of the spherical plate portion85.

The second bridge plate portion89includes an outer peripheral surface89aand an inner peripheral surface89b. The outer peripheral surface89ais continuous from the outer peripheral surface86aof the annular ring portion86and is formed as a partial cylindrical surface. The inner peripheral surface89bis continuous from the inner peripheral surface86bof the annular ring portion86and is formed as a partial cylindrical surface. A diameter of the outer peripheral surface (more specifically, a diameter of an imaginary circle, along which the outer peripheral surface extends in the circumferential direction)89aand a diameter of the inner peripheral surface (more specifically, a diameter of an imaginary circle, along which the inner peripheral surface extends in the circumferential direction)89bare substantially the same as the diameter of the outer peripheral surface86aand the diameter of the inner peripheral surface86b, respectively. Therefore, a thickness of the second bridge plate portion89, which is measured between the outer peripheral surface89aand the inner peripheral surface89b, is substantially uniform throughout the second bridge plate portion89and is substantially the same as that of the annular ring portion86(i.e., the thickness of the second bridge plate portion89being substantially the same as that of the spherical plate portion85).

A circumferential side lateral surface88cof the first bridge plate portion88and a circumferential side lateral surface89cof the second bridge plate portion89are continuous one after another in the axial direction to form a planar continuous surface that is continuous in the axial direction. A slit87ais circumferentially defined between the lateral surfaces88c,89cof one of each adjacent two of the bridge portions87and the lateral surfaces88c,89cof the other one of each adjacent two of the bridge portions87to axially extend from an outer peripheral side of the spherical plate portion85to the annular ring portion86.

The check valve80, which has the above structure, is operated in response to a pressure relationship, i.e., a pressure difference between a pressure on the one end portion56aside of the valve seat81and a pressure on the other end portion56bside of the valve seat81in the connection passage56. Specifically, when the pressure on the one end portion56aside of the valve seat81becomes higher than the pressure on the other end portion56bside of the valve seat81in the connection passage56, the valve member84is moved toward the other end portion56bside in the connection passage56until the valve member84abuts against the stopper83, as shown inFIGS. 7A and 8A, so that the convex plate surface85ais lifted away from the valve seat81, and thereby the check valve80is opened. Thus, in the connection passage56, during the operation in the advancing mode A shown inFIG. 7A, the flow of the hydraulic oil from each supply port60to each advancing port62side is enabled by the opening of the check valve80. Furthermore, in the connection passage56, during the operation in the retarding mode R shown inFIG. 8A, the flow of the hydraulic oil from each supply port60to each retarding port63side is enabled by the opening of the check valve80.

In contrast, when the pressure on the other end portion56bside of the valve seat81becomes higher than the pressure on the one end portion56aside of the valve seat81in the connection passage56, the valve member84is moved toward the one end portion56aside in the connection passage56, and thereby the convex plate surface85ais seated against the valve seat81, as shown inFIGS. 7B and 8B. Thereby, the check valve80is closed. Thus, in the connection passage56during the operation in the advancing mode A shown inFIG. 7B, the flow of the hydraulic oil from each advancing port62to each supply port60side is limited by the closing of the check valve80. Furthermore, in the connection passage56during the operation in the retarding mode R shown inFIG. 8B, the flow of the hydraulic oil from each retarding port63to each supply port60side is limited by the closing of the check valve80.

Next, the control operation (adjusting operation) of the valve timing with the valve timing control apparatus1will be described.

At the time of steady operation of the engine, in which the supply of the hydraulic oil from the pump4is maintained, the operational position of the spool53is selected by the control circuit90such that the control circuit90controls the energization of the solenoid51in a manner that implements the valve timing suitable for the operational state of the engine. Therefore, the input and output of the hydraulic oil relative to each advancing chamber22and each retarding chamber23are controlled in response to the selected operational position of the spool53. The valve timing control operation for each of the advancing mode A and the retarding mode R at the time of steady operation of the engine will be described. At the time of starting the steady operation of the engine, each advancing chamber22is filled with the corresponding quantity of the hydraulic oil that corresponds to the volume of the advancing chamber22, and each retarding chamber23is filled with the corresponding quantity of the hydraulic oil that corresponds to the volume of the retarding chamber23.

(1) Advancing Mode A

At the time of the steady operation of the engine, when an operational condition, such as presence of an actual rotational phase on a retarding side of a target rotational phase beyond an allowable deviation, is satisfied, the operational position (axial position) of the spool53during the operation in the advancing mode A shown inFIGS. 7A and 7Bis selected. At this operational position of the spool53, each advancing port62, which is communicated with each advancing chamber22through each advancing passage42, is connected to each supply port60, which is communicated with the supply passage40, through the connection passage56. At the same time, each retarding port63, which is communicated with each retarding chamber23through each retarding passage43, is connected to each drain port61that is opened to the atmosphere through the communication with each drain passage41, through the communication passage55.

In this connection state, when a negative torque, which increases the volume of each advancing chamber22, is exerted, a negative pressure is generated in each advancing chamber22. Thereby, in the connection passage56, which is connected to each advancing chamber22through each advancing port62, the check valve80is opened, as shown inFIG. 7A, and thereby the flow of the hydraulic oil toward each advancing port62is enabled. Thus, the hydraulic oil, which is supplied from the pump4to each supply port60, is guided from the connection passage56into each advancing chamber22through each advancing port62. At the same time, the hydraulic oil of each retarding chamber23is discharged from each retarding port63into each drain passage41through the communication passage55and each drain port61. As a result, the rotational phase is changed to the advancing side to advance the valve timing.

Furthermore, when the direction of the oscillating torque is reversed to exert the positive torque, which reduces the volume of each advancing chamber22, the hydraulic oil of each advancing chamber22is discharged into the connection passage56through each advancing port62. In this way, in the connection passage56, the check valve80is closed, as shown inFIG. 7B, and thereby the flow of the hydraulic oil from each advancing port62toward each supply port60is limited. As a result, the discharge of the hydraulic oil from each advancing chamber22is stopped, and thereby the returning of the rotational phase, which causes an increase in the volume of each retarding chamber23and thereby limits the discharge of the hydraulic oil into each drain passage41, is limited regardless of the exertion of the positive torque.

(2) Retarding Mode R

At the time of the steady operation of the engine, when an operational condition, such as presence of the actual rotational phase on an advancing side of the target rotational phase beyond an allowable deviation, is satisfied, the operational position (axial position) of the spool53during the operation in the retarding mode R shown inFIGS. 8A and 8Bis selected. At this operational position of the spool53, each retarding port63, which is communicated with each retarding chamber23through each retarding passage43, is connected to each supply port60, which is communicated with the supply passage40, through the connection passage56. At the same time, each advancing port62, which is communicated with each advancing chamber22through each advancing passage42, is connected to each drain port61that is opened to the atmosphere through the communication with each drain passage41, through the communication passage55.

In this connection state, when a positive torque, which increases the volume of each retarding chamber23, is exerted, a negative pressure is generated in each retarding chamber23. Thereby, in the connection passage56, which is connected to each retarding chamber23through each retarding port63, the check valve80is opened, as shown inFIG. 8A, and thereby the flow of the hydraulic oil toward each retarding port63is enabled. Thus, the hydraulic oil, which is supplied from the pump4to each supply port60, is guided from the connection passage56into each retarding chamber23through each retarding port63. At the same time, the hydraulic oil of each advancing chamber22is discharged from each advancing port62into each drain passage41through the communication passage55and each drain port61. As a result, the rotational phase is changed to the retarding side to retard the valve timing.

Furthermore, when the direction of the oscillating torque is reversed to exert the negative torque, which reduces the volume of each retarding chamber23, the hydraulic oil of each retarding chamber23is discharged into the connection passage56through each retarding port63. In this way, in the connection passage56, the check valve80is closed, as shown inFIG. 8B, and thereby the flow of the hydraulic oil from each retarding port63toward each supply port60is limited. As a result, the discharge of the hydraulic oil from each retarding chamber23is stopped, and thereby the returning of the rotational phase, which causes an increase in the volume of each advancing chamber22and thereby limits the discharge of the hydraulic oil into each drain passage41, is limited regardless of the exertion of the negative torque.

Now, advantages of the present embodiment will be described.

In the check valve80of the valve timing control apparatus1, a restoring force of a spring is not applied to the valve member84. Therefore, the valve opening speed of the valve member84at the time of lifting the valve member84from the valve seat81and the valve closing speed of the valve member84at the time of seating the valve member84against the valve seat81depend on the pressure of the hydraulic oil. In the spherical plate portion85of the valve member84, the convex plate surface85a, which is lifted away from or is seated against the valve seat81, and the concave plate surface85b, which is located on the opposite side of the convex plate surface85a, are formed as the partial spherical surfaces, each having the circular outer peripheral edge. Therefore, a sufficient surface area of each of the convex plate surface85aand the concave plate surface85bis provided to effectively receive the pressure of the hydraulic oil. With these pressure receiving actions of the convex plate surface85aand the concave plate surface85b, the valve opening speed is increased to rapidly change the rotational phase, and the valve closing speed is increased to rapidly limit the returning of the rotational phase. Therefore, it is possible to improve the response speed for adjusting the valve timing, which corresponds to the rotational phase.

Furthermore, in the valve member84of the valve timing control apparatus1, the annular ring portion86has the inner peripheral surface86b, which is opposite from the outer peripheral surface86athat is guided by the guide82, and the diameter of the inner peripheral surface86bis made larger than that of the spherical plate portion85. Furthermore, the annular ring portion86is coaxially connected to the spherical plate portion85through the three bridge portions87, each two of which are circumferentially spaced from each other by the corresponding slit87a. With the above construction, a portion of the hydraulic oil, which flows through the connection passage56in the lifted state of the valve member84away from the valve seat81, flows from the radially outer side of the circular outer peripheral edge of the spherical plate portion85into the slits87a, each of which is circumferentially defined between the adjacent two of the bridge portions87. Then, this portion of the hydraulic oil, which flows into the slits87a, passes through the inside of the annular ring portion86, which has the diameter larger than that of the circular outer peripheral edge of the spherical plate portion85, without substantial collision against the valve member84. Here, the annular ring portion86is located on the radially outer side of the axially projected shadow85cof the spherical plate portion85, which is axially projected toward the annular ring portion86side. This annular ring portion86enables the effective limitation of the collision of the hydraulic oil, which passes from the radially outer side of the spherical plate portion85into the slits87a, against the valve member84, so that the amount of pressure loss of the hydraulic oil can be sufficiently reduced. Thereby, in each of the advancing mode A and the retarding mode R, the supply of the hydraulic oil to each advancing chamber22or each retarding chamber23through each advancing port62or each retarding port63can be rapidly performed to reliably implement the rapid change in the rotational phase, so that it is possible to improve the response speed for adjusting the valve timing, which corresponds to the rotational phase.

Furthermore, in the valve member84of the valve timing control apparatus1, each of the outer peripheral surface88aand the inner peripheral surface88bof the first bridge plate portion88of each bridge portion87, is formed as the partial spherical surface, which is continuous from the corresponding one of the convex plate surface85aand the concave plate surface85bof the spherical plate portion85. Therefore, the pressure of the hydraulic oil can be easily received with each of the outer peripheral surface88aand the inner peripheral surface88bof the first bridge plate portion88of each bridge portion87in corporation with the corresponding one of the convex plate surface85aand the concave plate surface85bof the spherical plate portion85. Furthermore, in the second bridge plate portion89of each bridge portion87, the outer peripheral surface89a, which is formed as the partial cylindrical surface that is continuous from the outer peripheral surface86aof the annular ring portion86, can be guided by the guiding function of the guide82, and the inner peripheral surface89b, which is formed as the partial cylindrical surface that is continuous from the inner peripheral surface86bof the annular ring portion86, can perform the guiding function for guiding the hydraulic oil. The guiding function of the inner peripheral surface89bof the second bridge plate portion89for guiding the hydraulic oil will not likely interfere with the flow of the hydraulic oil, which passes from the radially outer side of the spherical plate portion85into the slits87aand then flows through the inside of the annular ring portion86in the lifted state of the valve member84away from the valve seat81. Thereby, both of the rapid change in the rotational phase and the rapid limitation of the returning of the rotational phase are implemented, and thereby it is possible to improve the response speed for adjusting the valve timing.

Furthermore, in the valve member84of the valve timing control apparatus1, the circumferential side lateral surface88cof the first bridge plate portion88and the circumferential side lateral surface89cof the second bridge plate portion89are continuously formed one after another in the axial direction as the continuous planar surface in each bridge portion87, so that the circumferential side lateral surface88cand the circumferential lateral surface89ccan cooperate with each other to effectively guide the hydraulic oil in the axial direction. The hydraulic oil, which passes from the radially outer side of the spherical plate portion85into the slits87ain the lifted state of the valve member84away from the valve seat81, is easily directed toward the inside of the annular ring portion86located on the downstream side of the slits87ain the axial direction, so that the amount of pressure loss can be sufficiently reduced. Thereby, the rapid change in the rotational phase can be reliably implemented, and thereby it is possible to improve the response speed for adjusting the valve timing.

In the valve timing control apparatus1, each drain port61is axially displaced from each advancing port62on one axial side thereof in the axial direction of the sleeve54and is also axially displaced from each retarding port63on the other axial side thereof in the axial direction of the sleeve54. Furthermore, each drain port61is circumferentially displaced from each drain passage41located on the radially outer side of the drain port61in the circumferential direction of the sleeve54. Because of the above displacement of each drain port61, the length of the passage, which serves as the discharge passage extending from each retarding port63or each advancing port62to each drain passage41, becomes sufficient during the operation in the advancing mode A or the retarding mode R, and thereby the amount of pressure loss in this passage is advantageously increased (maximized). Thus, it is possible to limit the fluctuating movement of the vane rotor15that would be caused by the feeding of the air into one of each advancing chamber22and each retarding chamber23, to which the hydraulic fluid is currently fed, upon the excessive discharging of the hydraulic oil during the operation in each of the advancing mode A and the retarding mode R. Thereby, the response speed for adjusting the valve timing, which corresponds to the rotational phase, can be improved.

Furthermore, in the valve timing control apparatus1, each advancing port62, which is communicated with each advancing chamber22through each advancing passage42formed as the through-hole in the synchronously rotatable member17(i.e., the camshaft2and the vane rotor15), is formed such that the circumferential position of each advancing port62in the circumferential direction of the sleeve54coincides with the circumferential position of the corresponding advancing passage42. Because of the above positional relationship of the advancing port62, during the operation in the advancing mode A, the passage, which is now used as the feed passage extending from each advancing port62to each advancing passage42, can implement the rapid feeding of the hydraulic oil by reducing the amount of pressure loss, and thereby it is possible to increase the response speed for adjusting the valve timing. In contrast, during the operation in the retarding mode R, the passage, which is now used as the discharge passage extending from each advancing passage42to each advancing port62, causes the reduction in the amount of pressure loss. However, at this time, the amount of pressure loss can be increased in the passage, which is used as the discharge passage extending from each advancing port62to each drain passage41. Thereby, it is possible to increase the response speed for adjusting the valve timing.

Furthermore, in the valve timing control apparatus1, each retarding port63, which is communicated with each retarding chamber23through each retarding passage43formed as the through-hole in the synchronously rotatable member17(i.e., the camshaft2and the vane rotor15), is formed such that the circumferential position of each retarding port63in the circumferential direction of the sleeve54coincides with the circumferential position of the corresponding retarding passage43. Because of the above positional relationship of the retarding port63, during the operation in the retarding mode R, the passage, which is used as the feed passage extending from each retarding port63to each retarding passage43, can implement the rapid feeding of the hydraulic oil by reducing the amount of pressure loss, and thereby it is possible to increase the response speed for adjusting the valve timing in the retarding mode R. In contrast, during the operation in the advancing mode A, the passage, which is now used as the discharge passage extending from each retarding passage43to each retarding port63, causes the reduction in the amount of pressure loss. However, at this time, the amount of pressure loss can be increased in the passage, which is used as the discharge passage extending from each retarding port63to each drain passage41. Thereby, it is possible to increase the response speed for adjusting the valve timing in the advancing mode A.

In addition, during the operation of the valve timing control apparatus1in each of the advancing mode A and the retarding mode R, the discharge passage is formed from the corresponding one of each retarding port63and each advancing port62to each drain passage41through each drain port61, which is equally axially displaced from each of the retarding port63and the advancing port62in the axial direction of the sleeve54by the corresponding amount of axial positional displacement ΔRa, ΔAa. Furthermore, during the operation of the valve timing control apparatus1in each of the advancing mode A and the retarding mode R, the discharge passage is formed from the corresponding one of each retarding passage43and each advancing passage42to each drain passage41, which is equally circumferentially displaced from each of the retarding passage43and the advancing passage42in the circumferential direction of the sleeve54by the corresponding amount of circumferential positional displacement ΔRc, ΔAc. With the above discharge passages, it is possible to reduce (minimize) the difference in the length of the discharge passage as well as the difference in the amount of pressure loss in the discharge passage at each of the advancing mode A and the retarding mode R. Therefore, the response speed can be increased in each of the advancing mode A and the retarding mode R.

Now, modifications of the above embodiment will be described.

The present invention has been described with respect to the one embodiment of the present invention. However, the present invention is not limited to the above embodiment, and the above embodiment may be modified in various ways within a spirit and scope of the present invention.

Specifically, the bridge portions87may be other than the bridge portions87, each of which has the first and second bridge plate portions88,89. For example, the bridge portions87, each of which is tilted relative to the axial direction, may be used to connect between the spherical plate portion85and the annular ring portion86, which have a diameter difference therebetween. Furthermore, the number of the bridge portions87may be changed to any other appropriate number. For example, as shown inFIGS. 12A to 12C, the number of the bridge portions87may be changed to four. Furthermore, in the control valve50, at least a portion of the sleeve54, which receives the spool53and the spring52, may be directly received in the vane rotor15. The present invention is also applicable to any other type of valve timing control apparatus, which controls valve timing of exhaust valves or which controls both of the valve timing of the intake valves and the valve timing of the exhaust valves.

The number of each of the above ports60-63is not limited to the above-described number and can be changed to one or can be increased further depending on a need. Furthermore, the amount of axial positional displacement ΔRa of the retarding port63from the drain port61in the axial direction of the sleeve54and the amount of axial positional displacement ΔAa of the advancing port62from the drain port61in the axial direction of the sleeve54may be set to be different from each other. Also, the amount of circumferential positional displacement ΔRc of the retarding passage43from the drain passage41in the circumferential direction of the sleeve54and the amount of circumferential positional displacement ΔAc of the advancing passage42from the drain passage41in the circumferential direction of the sleeve54may be set to be different from each other. Furthermore, as shown inFIGS. 13 and 14, which indicates a modification of the drain passages41of the above embodiment, an annular groove41amay be formed between the portion of the camshaft2, which is located on the side communicated with the drain ports61, and the atmosphere communicated side (atmosphere open side) of the vane rotor15, which is communicated with the atmosphere, such that the annular groove41aopens in the inner peripheral surface of the vane rotor15. In this way, the processing operation of the drain passages41at the time of manufacturing can be improved.