WO2010061936A1

WO2010061936A1 - Variable valve device for internal combustion engine

Info

Publication number: WO2010061936A1
Application number: PCT/JP2009/070068
Authority: WO
Inventors: Yoshiro Kamo; Yuu Yokoyama; Masaki Numakura
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2008-11-28
Filing date: 2009-11-20
Publication date: 2010-06-03
Also published as: JP2010127252A

Abstract

A variable valve device includes a variable valve timing mechanism, which varies a valve timing, an intermediate lock mechanism, which locks the valve timing at an intermediate timing, and an oil pressure supply unit, which controls the state in which oil is supplied to these mechanisms. The oil pressure supply unit supplies and discharges oil through an intermediate oil passage, which connects an oil control valve and an intermediate chamber without extending through an advancing chamber and a retarding chamber. The state in which oil is supplied is controlled by a single oil control valve. The operation state of the intermediate lock mechanism is switched by changing the state in which oil is supplied to the intermediate chamber when the engine is operating.

Description

DESCRIPTION

VARIABLE VALVE DEVICE FOR INTERNAL COMBUSTION ENGINE

BACKGROUND OF THE INVENTION

The present invention relates to a variable valve device for an internal combustion engine including a variable mechanism, which varies the valve timing of engine valves between a most advanced timing and a most retarded timing, a restriction mechanism, which locks the valve timing of the engine valves at a specific intermediate timing between the most advanced timing and the most retarded timing, and an oil pressure mechanism, which controls the supply of oil to the variable mechanism and restriction mechanism.

Japanese Laid-Open Patent Publication No. 2001-50064 describes an example of a variable valve device. The variable valve device includes a variable mechanism provided with a vane rotor (output rotation member) and a housing (input rotation member), which are rotatable relative to each other. The vane rotor rotates in synchronism with a camshaft for engine valves, and the housing rotates in synchronism with a crankshaft. An advancing chamber and a retarding chamber are formed between the vane rotor and housing. The variable valve device controls the supply of oil to the advancing and retarding chambers with the oil pressure mechanism to change the relative rotational phases of the vane rotor and housing and vary the valve timing of the engine valve.

The vane rotor includes a lock pin (restriction member) , and the housing includes a lock hole (restriction hole) , which receives the lock pin. The lock pin is fitted to the lock hole when the engine stops operating. This fixes the valve timing of the engine valve at the intermediate timing. Thus, when the engine is started the next time, the engine valve operates at the intermediate timing.

More specifically, as described in paragraphs [0035] to [0043] and Figs. 3 to 6 of the above-mentioned patent publication, the variable mechanism includes a spring, which presses the lock pin in the direction the lock pin projects out of the vane rotor, and a lock release chamber (intermediate chamber), which is in communication with the retarding chamber. When the engine is operating, the oil supplied to the retarding chamber is also supplied to the lock release chamber. While the oil is being supplied to the lock release and retarding chambers during the operation of the engine, the oil in the lock release chamber generates a force that prevents the lock pin from projecting out of the vane rotor. This keeps the lock pin retracted in the vane rotor.

After the engine stops operating and the supply of oil to the advancing and retarding chamber is stopped, the supply of oil to the lock release chamber is also stopped. This eliminates the force generated by the oil of the lock release chamber and prevents the lock pin from projecting out of the vane rotor. Further, when the supply of oil to the advancing and retarding chambers is stopped, the housing and the vane rotor each rotate relative to each other in a single direction. When the rotational phases of the lock pin and the lock hole become the same as a result of the relative rotation, the resilient force of the spring forces the lock pin into the lock hole. Thus, the lock pin restricts the relative rotation of the housing and the vane rotor. This holds the valve timing at the intermediate timing, which corresponds to the present relative rotational phases of the vane rotor and the housing.

[Problem 1] In the variable valve device of the above- mentioned patent publication, the retarding chamber and the lock release chamber are in communication with each other. Thus, the state of the lock pin cannot be switched when the engine is operating. The above-described variable valve device is used so that the valve timing is fixed at the intermediate timing when the engine is started. Thus, there is no need to lock the valve timing at the intermediate timing when the engine is operating. As a result, although the lock pin state cannot be switched during operation of the engine, this is not a serious problem for the variable valve device. Nevertheless, it is desirable that this problem be resolved so as to allow for the functions of the lock pin to be effectively implemented and thereby widen the range of valve timing control.

To resolve this problem, for example, the structure described in paragraphs [0076] to [0078] and Figs. 19 to 21 of the above-mentioned patent publication may be employed. That is, a first oil pressure control valve, which controls the supply of oil to the advancing and retarding chambers, and a second oil pressure control valve, which controls the supply of oil to the lock release chamber, may be separately provided. However, this requires two oil pressure control valves and is thus not practical and not preferable.

Accordingly, a first object of the present invention is to provide a variable valve device for an internal combustion engine that switches the operation state of a restriction mechanism with a single oil pressure control valve regardless of the state of the oil supplied to an advancing chamber or retarding chamber when the engine is operating.

[Problem 2] As described in the above-mentioned patent publication, when the engine stops operating, the relative rotation of the housing and the vane rotor fits the lock pin into the lock hole. In this case, the lock pin is moved under a situation in which the rotation speed relative to the vane rotor is relatively low. Thus, although the mechanism for fitting the lock pin into the lock hole is simple, a situation in which the lock pin passes by the lock hole and cannot be fitted into the lock hole is unlikely to occur .

However, when the engine is operating, the vane rotor and the housing rotate relative to each other at a rotational speed that is higher than when the engine is not operating. If a control for fitting the lock pin into the lock hole were to be implemented during operation of the engine, the lock pin would more likely pass by the lock hole and not be fitted to the lock hole due to the high relative rotational speed.

Accordingly, it is a second object of the present invention to provide a variable valve device for an internal combustion engine that allows for a restriction member to be accurately fitted into a restriction hole when the engine is operating.

DISCLOSURE OF THE INVENTION One aspect of the present invention is a variable valve device for an internal combustion engine. The variable valve device includes a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing. A restriction mechanism locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing. An oil pressure mechanism includes an oil pressure control valve and controls the state in which oil is supplied to the variable mechanism and the restriction mechanism by the oil pressure control valve. In accordance with the state in which oil is supplied by the oil pressure mechanism, the restriction mechanism is switched between a lock state in which the valve timing is locked at the intermediate timing and a release state in which the valve timing is released from the lock state. The oil pressure mechanism supplies oil to the restriction mechanism and discharges oil from the restriction mechanism through an intermediate oil passage connecting the oil pressure control valve and the restriction mechanism without extending through an advancing chamber and a retarding chamber of the variable mechanism. The oil pressure mechanism controls the state in which oil is supplied to the advancing and retarding chambers of the variable mechanism and the restriction mechanism with the single oil control valve. The oil pressure mechanism changes the state in which oil is supplied to the restriction mechanism when the engine is operating to switch between the lock state and the release state.

A further aspect of the present invention is a variable valve device for an internal combustion engine. The variable valve device includes a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing. A restriction mechanism locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing. An oil pressure mechanism includes an oil pressure control valve and controls the state in which oil is supplied to the variable mechanism and the restriction mechanism by the oil pressure control valve. The variable mechanism includes an input rotation member, which is rotated by force transmitted from a crankshaft of the internal combustion engine, and an output rotation member, which is rotated together with a camshaft of the engine valve by force transmitted from the input rotation member. The input rotation member and the output rotation member define therebetween an advancing chamber and a retarding chamber. The restriction mechanism includes a restriction member and an intermediate chamber arranged in a first rotation member, which is either one of the input rotation member and the output rotation member, and a restriction hole formed in a second rotation member, which is the other one of the input rotation member and the output rotation member. The restriction member is operated in a state projected out of the first rotation member and a state retracted into the^' first rotation member. The intermediate chamber is supplied with oil from the oil pressure mechanism. The restriction mechanism projects the restriction member out of the first rotation member when oil is supplied to the intermediate chamber in a first supply state by the oil pressure mechanism. The restriction mechanism projects the restriction member out of the first rotation member so that the restriction member is fitted into the restriction hole of the second rotation member to lock the valve timing of the engine valve at the intermediate timing. The restriction mechanism separates the restriction member from the restriction hole and retracts the restriction member into the first rotation member when oil is supplied to the intermediate chamber in a second supply state by the oil pressure mechanism to release the valve timing from the intermediate timing. The oil pressure mechanism supplies oil to the intermediate chamber and discharges oil from the intermediate chamber through an intermediate oil passage, which is connected to the oil pressure control valve and the intermediate chamber without extending through the advancing chamber and the retarding chamber. The oil pressure mechanism controls the state in which oil is supplied to the advancing chamber, the retarding chamber, and the intermediate chamber with the single oil pressure control valve. The oil pressure mechanism changes the state in which oil is supplied to the intermediate chamber when the engine is operating to switch the state in which the restriction member is operated.

Another aspect of the present invention is a variable valve device for an internal combustion engine. The variable valve device includes a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing. A restriction mechanism locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing. An oil pressure mechanism controls the state in which oil is supplied to the variable mechanism and the restriction mechanism. The restriction mechanism includes a restriction member and an intermediate chamber arranged in a first rotation member, which is either one of an input rotation member and an output rotation member of the variable mechanism, and a restriction hole formed in a second rotation member, which is the other one of the input rotation member and the output rotation member. The restriction member is operated in a state projected out of the first rotation member and a state retracted into the first rotation member. The intermediate chamber is supplied with oil from the oil pressure mechanism. The restriction mechanism projects the restriction member out of the first rotation member when oil is supplied to the intermediate chamber in a first supply state by the oil pressure mechanism. The restriction mechanism projects the restriction member out of the first rotation member so that the restriction member is fitted into the restriction hole of the second rotation member to lock the valve timing of the engine valve at the intermediate timing. The restriction mechanism separates the restriction member from the restriction hole and retracts the restriction member into the first rotation member when oil is supplied to the intermediate chamber in a second supply state by the oil pressure mechanism to release the valve timing from the intermediate timing. The first rotation member includes a restriction groove having a smaller depth than the restriction hole. The restriction groove extends along a circumferential path of the restriction member from the restriction hole toward a retarding side. When the oil pressure mechanism applies force to the restriction member acting to project the restriction member out of the first rotation member in a state in which the restriction member is located at a position retarded from a retarding side end of the restriction groove, the output rotation member is driven toward an advancing side relative to the input rotation member so that a distal portion of the restriction member first moves into the restriction groove and the output rotation member is then continuously driven toward the advancing side relative to the input rotation member so that the distal portion of the restriction member is moved toward the advancing side in the restriction groove and subsequently fitted into the restriction hole. The oil pressure mechanism changes the state in which oil is supplied to the intermediate chamber when the engine is operating to switch the state in which the restriction member is operated.

Still a further aspect of the present invention is a variable valve device for an internal combustion engine. The variable valve device including a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing. A restriction mechanism locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing. An oil pressure mechanism controls the state in which oil is supplied to the variable mechanism and the restriction mechanism. The restriction mechanism includes a restriction member and an intermediate chamber arranged in a first rotation member, which is either one of an input rotation member and an output rotation member of the variable mechanism. A restriction hole is formed in a second rotation member, which is the other one of the input rotation member and the output rotation member. The restriction member is operated in a state projected out of the first rotation member and a state retracted into the first rotation member. The intermediate chamber is supplied with oil from the oil pressure mechanism. The restriction mechanism projects the restriction member out of the first rotation member when oil is supplied to the intermediate chamber in a first supply state by the oil pressure mechanism. The restriction mechanism projects the restriction member out of the first rotation member so that the restriction member is fitted into the restriction hole of the second rotation member to lock the valve timing of the engine valve at the intermediate timing. The restriction mechanism separates the restriction member from the restriction hole and retracts the restriction member into the first rotation member when oil is supplied to the intermediate chamber in a second supply state by the oil pressure mechanism to release the valve timing from the intermediate timing. The first rotation member includes a restriction groove having a smaller depth than the restriction hole. The restriction groove extends along a circumferential path of the restriction member from the restriction hole toward an advancing side. When the oil pressure mechanism applies force to the restriction member acting to project the restriction member out of the first rotation member in a state in which the restriction member is located at a position advanced from an advancing side end of the restriction groove, the output rotation member is driven toward a retarding side relative to the input rotation member so that a distal portion of the restriction member first moves into the restriction groove and the output rotation member is then continuously driven toward the retarding side relative to the input rotation member so that the distal portion of the restriction member is moved toward the retarding side in the restriction groove and subsequently fitted into the restriction hole. The oil pressure mechanism changes the state in which oil is supplied to the intermediate chamber when the engine is operating to switch the state in which the restriction member is operated. Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

Fig. 1 is a cross-sectional view of an internal combustion engine including a variable valve device according to a first embodiment of the present invention;

Fig. 2(A) is a plan view showing a variable valve timing mechanism;

Fig. 2 (B) is a cross-sectional view of the variable valve timing mechanism taken along line 2B-2B in Fig. 2(A); Fig. 3 is a schematic cross-sectional view of a housing and a vane rotor taken along line 3-3 in Fig. 2(A);

Fig. 4 is a schematic diagram showing lubricating oil passages between an oil pressure supply unit and a variable valve timing mechanism; Fig. 5 is a schematic cross-sectional view showing the state of an oil control valve in a first operation mode;

Fig. 6 is a schematic cross-sectional view showing the state of the oil control valve in a second operation mode;

Fig. 7 is a schematic cross-sectional view showing the state of the oil control valve in a third operation mode;

Fig. 8 is a schematic cross-sectional view showing the state of the oil control valve in a fourth operation mode;

Fig. 9(A) is a table showing the relationship of the operation modes of the oil control valve and the state of the lubricating oil supplied to the variable valve timing mechanism;

Fig. 9(B) is a table showing the relationship of operation modes of the oil control valve and the operation of the variable valve timing mechanism;

Fig. 10 is a flowchart showing the procedures for an "intermediate lock process" executed by an electronic control unit; Fig. 11 is a schematic cross-sectional view of the housing and the vane rotor taken along line 3-3 in Fig. 2 (A) ;

Fig. 12 is a schematic cross-sectional view showing an oil control valve in a first operation mode in a variable valve device according to a second embodiment of the present invention;

Fig. 13 is a schematic cross-sectional view showing the oil control valve in a second operation mode;

Fig. 14 is a schematic cross-sectional view showing the oil control valve in a third operation mode;

Fig. 15 is a schematic cross-sectional view showing the oil control valve in a fourth operation mode;

Fig. 16(A) is a table showing the relationship of the operation modes of the oil control valve and the state of the lubricating oil supplied to the variable valve timing mechanism;

Fig. 16(B) is a table showing the relationship of the operation modes of the oil control valve and the operation of the variable valve timing mechanism; Fig. 17 is a flowchart showing the procedures for an "intermediate lock process" executed by the electronic control unit;

Fig. 18 is a schematic cross-sectional view of the housing and the vane rotor taken along line 3-3 in Fig. 2(A) .

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment]

An internal combustion engine according to a first embodiment of the present invention will now be discussed with reference to Figs. 1 to 11.

As shown in Fig. 1, an engine 1 includes an engine body 10, a variable valve timing mechanism 30, an oil pressure supply unit (oil pressure mechanism) 50, and an electronic control unit 80. The engine body 10 generates power by burning a mixture of air and fuel. The variable valve timing mechanism 30 varies the valve timing of an intake valve 21 (engine valve) . The oil pressure supply unit 50 supplies the engine body 10 and the variable valve timing mechanism 30 with lubricating oil. The electronic control unit 80 centrally controls these devices.

The engine body 10 includes a cylinder block 11, in which a combustion chamber 14 is formed. The mixture of fuel, which is injected from an injector 17, and air, which flows through an intake air passage, is combusted in the combustion chamber 14. The combustion produces linear motion with a piston 15. The linear motion is converted to a rotary motion of a crankshaft 16. The cylinder block 11 has a lower portion attached to an oil pan 12. The oil pan 12 contains lubricating oil that is supplied to various parts of the engine 1. The cylinder block 11 has an upper portion attached to a cylinder head 13. Valve components are arranged on the cylinder head 13.

The cylinder head 13 includes an intake valve 21, which opens and closes the combustion chamber 14 relative to the intake air passage, and an intake cam shaft 22, which drives the intake valve 21. The cylinder head 13 further includes an exhaust valve 23 (engine valve) , which opens and closes the combustion chamber 14 relative to an exhaust air passage, and an exhaust cam shaft 24, which drives the exhaust valve 23.

The crankshaft 16 is connected to an oil pump 18, which pumps out the lubricating oil from the oil pan 12. The lubricating oil pumped out of the oil pump 18 is supplied to various parts of the engine 1 through a lubricating oil passage 52. Some of the lubricating oil is supplied to the variable valve timing mechanism 30 for oil pressure purposes through an oil control valve 51 (oil pressure control valve) . The lubricating oil circulated to various parts of the engine 1 and the lubricating oil discharged from the variable valve timing mechanism 30 are returned again to the oil pan 12. The variable valve device of this embodiment includes the variable valve timing mechanism 30, the oil control valve 51, and the electronic control unit 80.

The electronic control unit 80 is connected to various sensors, which assist control. The sensors include a crank position sensor 81, a cam position sensor 82, and a coolant temperature sensor 83. The crank position sensor 81, which is arranged near the crankshaft 16, outputs a signal that is in accordance with rotation angle of the crankshaft 16. The cam position sensor 82, which is arranged near the intake cam shaft 22, outputs a signal that is in accordance with rotation angle of the shaft 22. The coolant temperature sensor 83, which is arranged in the cylinder block 11, outputs a signal that is in accordance with the temperature of an engine coolant, which is for cooling the engine body 10. The electronic control unit 80 calculates valve timing of the intake valve 21 (hereinafter "valve timing INVT") based on the outputs of the crank position sensor 81 and the cam position sensor 82.

Based on the outputs from the sensors or the like, the electronic control unit 80 executes various controls, such as fuel injection control for adjusting the fuel injection amount through control of the injector 17 and valve timing control for adjusting the valve timing INVT by controlling the oil control valve 51.

The structure of the variable valve timing mechanism 30 will now be discussed with reference to Fig. 2. Fig. 2(A) is a plan view showing the variable mechanism 30 in a state in which a cover 34 is removed from a housing 31. Arrow A in Fig 2 (A) indicates the rotation direction of the shaft 22 and the variable valve timing mechanism 30.

The variable valve timing mechanism 30 includes a sprocket 32 and a vane rotor 33. The sprocket 32 is coupled to the crankshaft 16 by a timing chain so as to rotate in synchronism with the crankshaft 16. The vane rotor 33 is fixed to one end of the intake cam shaft 22 so as to rotate in synchronism with the shaft 22. The housing 31 is arranged in the sprocket 32 so as to rotate integrally with the sprocket 32. The vane rotor 33 is received in a cavity formed in the housing 31. The cover 34 is attached to the housing 31 to hold the vane rotor 33 in a cavity of the hous ing 31 .

The housing 31 includes three partition walls 32A, which extend radially toward the vane rotor 33. The vane rotor 33 includes three vanes 33A extending toward the housing 31. A gap is formed between each pair of adjacent partition walls 32A to receive one of the vane 33A. An advancing chamber 35 and a retarding chamber 36 are defined on opposite sides of the vane 33A in the gap formed between the corresponding adjacent partition walls 32A.

The advancing chamber 35 is located rearward from the vane 33A in the rotation direction of the intake cam shaft 22. The retarding chamber 36 is located frontward from the vane 33A in the rotation direction of the intake cam shaft

22. The volume of the advancing chamber 35 and the volume of the retarding chamber 36 change in accordance with the state of the lubricating oil supplied to the variable valve timing mechanism 30 by the oil pressure supply unit 50.

With the structure described above, the variable valve timing mechanism 30 varies the valve timing INVT by changing the rotational phase of the vane rotor 33 relative to the housing 31 and the sprocket 32. In detail, the variable mechanism 30 varies the valve timing INVT as described below.

Lubricating oil is supplied to the advancing chambers 35 and discharged from the retarding chambers 36 to rotate the vane rotor 33 relative to the housing 31 toward the advancing side, i.e., in the rotation direction of the intake cam shaft 22. This advances the valve timing INVT. When the vane rotor 33 is rotated to its advancing side limit relative to the housing 31, that is, when the vanes 33A come into contact with the partition walls 32A in the retarding chambers 36, the valve timing INVT is set to the most advanced timing (hereinafter "most advanced timing INVTmax") . The rotational phase of the vane rotor 33 relative to the housing 31 in this state is hereinafter referred to as the most advanced phase PH.

Lubricating oil is discharged from the advancing chambers 35 and supplied to the retarding chambers 36 to rotate the vane rotor 33 relative to the housing 31 toward the retarding side, i.e., in the direction reverse to the rotation direction of the intake cam shaft 22. This retards the valve timing INVT. When the vane rotor 33 is rotated to its retarding side limit relative to the housing 31, that is, when the vanes 33A come into contact with the partition walls 32A in the advancing chambers 35, the valve timing INVT is set to the most retarded timing (hereinafter "most retarded timing INVTmin") . The rotational phase of the vane rotor 33 relative to the housing 31 in this state is hereinafter referred to as the most retarded phase PL.

When the circulation of lubricating oil between the oil pressure supply unit 50 and the advancing chambers 35 and retarding chambers 36 is stopped, the lubricating oil is held in the advancing chambers 35 and retarding chambers 36. This fixes and stops rotation of the vane rotor 33 relative to the housing 31. Thus, the valve timing INVT is maintained at the present timing.

The variable valve timing mechanism 30 includes an intermediate lock mechanism 40. The intermediate lock mechanism restricts rotation of the vane rotor 33 relative to the housing 31 irrespective of the oil pressure in the advancing chambers 35 and retarding chambers 36. This locks the valve timing INVT at a specific timing between the most advanced timing INVTmax and the most retarded timing INVTmin (hereinafter "intermediate timing INVTmdl") . The intermediate timing INVTmdl is set to a suitable timing for starting the engine. In other words, the highest startability is obtained if the valve timing INVT is set to the intermediate timing INVTmdl when the engine is started.

The supply of lubricating oil from the oil pressure supply unit 50 operates the vane rotor 33. When the vane rotor 33 is rotated relative to the housing 31 to a rotational phase corresponding to the intermediate timing INVTmdll (hereinafter "intermediate phase PM") , the housing 31 and the vane rotor 33 are locked to each other. This holds the valve timing at the intermediate timing INVTmdl .

The intermediate lock mechanism 40 includes an intermediate lock pin 41, an intermediate chamber 42, and a lock spring 43, which are arranged in one of the vanes 33A, and an intermediate lock hole 44, which is formed in the housing 31. The oil pressure supply unit 50 supplies the intermediate chamber 42 with lubricating oil. The lock spring 43 presses the intermediate lock pin 41 in one direction.

Oil pressure in the intermediate chamber 42 generates a force applied to the intermediate lock pin 41 in the retracting direction. The lock spring 43 generates a force that is applied to the intermediate lock pin 41 in the projecting direction. The intermediate lock pin 41 moves along a direction in which it is projected out of the vane 33A (hereinafter "projecting direction") or a direction in which it is retracted into the vane 33A (hereinafter "retracting direction") depending on the resultant of the force generated by the lubricating oil in the intermediate chamber 42 and the force generated by the lock spring 43.

When the oil pressure supply unit 50 supplies and fills the intermediate chamber 42 with lubricating oil, the state of the lubricating oil supplied to the intermediate chamber 42 is referred to as a first supply state. In this state, the force generated by the lubricating oil in the intermediate chamber 42 in the projecting direction exceeds the force of the lock spring 43 in the retracting direction. Accordingly, the resultant of the force generated by the lubricating oil in the intermediate chamber 42 and the force generated by the lock spring 43 acts to move the intermediate lock pin 41 in the projecting direction. In this state, when the rotational phase of the vane rotor 33 relative to the housing 31 reaches the intermediate phase PM, the intermediate lock pin 41 is aligned with the intermediate lock hole 44. As a result, the intermediate lock pin 41 is projected from the vane 33A and fitted into the intermediate lock hole 44. The engagement of the intermediate lock pin 41 and the intermediate lock hole 44 locks the housing 31 and the vane rotor 33 to each other and holds the relative rotational phases at the intermediate phase PM.

When the oil pressure supply unit 50 discharges and removes lubricating oil from the intermediate chamber 42, the state of the lubricating oil supplied to the intermediate chamber 42 is referred to as a second supply state. In this state, the resultant of the force generated by the lubricating oil in the intermediate chamber 42 and the force generated by the lock spring 43 acts to move the intermediate lock pin 41 in the retracting direction. When the force in the retracting direction acts on the intermediate lock pin 41 in a state in which the intermediate lock pin 41 is fitted to the intermediate lock hole 44, the intermediate lock pin 41 is moved out of the intermediate lock hole 44 and retracted into the vane 33A. This disengages the intermediate lock pin 41 from the intermediate lock hole 44 and allows for the vane rotor 33 to rotate relative to the housing 31.

Fig. 3 is a schematic cross-sectional view of the variable valve timing mechanism 30 taken along line 3-3 in Fig. 2 (A) .

Fig. 3(A) shows a state in which the rotational phase of the vane rotor 33 relative to the housing 31 is at the most advanced phase PH. Fig. 3 (B) shows a state in which the rotational phase of the vane rotor 33 relative to the housing 31 is at the most retarded phase PL. When the rotational phase of the vane rotor 33 is shifted between the most advanced phase PH and the most retarded phase PL, the intermediate lock pin 41 is kept retracted in the vane 33A. Even if the rotational phase of the vane rotor 33 reaches the intermediate phase PM as shown in the state of Fig. 3 (C) , the rotational phase of the vane rotor 33 does not become locked at the intermediate phase PM as long as the intermediate lock pin 41 is retracted in the vane 33A by the supply of lubricating oil to the intermediate chamber 42.

When lubricating oil is discharged from the intermediate chamber 42 in a state in which the rotational phase of the vane rotor 33 is at the intermediate phase PM, the intermediate lock pin 41 is urged in the projecting direction. In this state, as shown in Fig. 3(D), the intermediate lock pin 41 is projected out of the vane 33A and fitted into the intermediate lock hole 44. This holds the vane rotor 33 at the intermediate phase PM.

The housing 31 includes an intermediate lock groove (restriction groove 45) . The intermediate lock groove 45 extends along a circumferential path of the intermediate lock pin 41 from the lock hole 44 toward the retarding side. The intermediate lock groove 45 has a smaller depth than the intermediate lock hole 44.

The intermediate lock mechanism 40 includes the intermediate lock groove 45. The intermediate lock pin 41 may be fitted into the intermediate lock hole 44 in the following manner. When a force acts on the intermediate lock pin 41 in the projecting direction and the intermediate lock pin 41 is located further toward the retarding side than the retarding side end of the intermediate lock groove 45, by driving the vane rotor 33 toward the advancing side relative to the housing 31, the distal portion of the intermediate lock pin 41 moves into the intermediate lock groove 45. By further driving the vane rotor 33 toward the advancing side relative to the housing 31, the distal portion of the intermediate lock pin 41 moves toward the advancing side in the intermediate lock groove 45 and is then fitted into the intermediate lock hole 44.

The circulation of the lubricating oil between the variable valve timing mechanism 30 and the oil pressure supply unit 50 will now be discussed with reference to Fig. 4. Fig. 4 schematically shows the structure of an oil passage between these devices.

The oil pressure supply unit 50 includes the oil pan 12, the oil pump 18, an oil control valve 51, and oil passages 52 through which the lubricating oil circulates between these components. The oil passages 52 include a supply oil passage 53, a discharge oil passage 54, an advancing oil passage 55, a retarding oil passage 56, and an intermediate oil passage 57. The supply oil passage 53 supplies lubricating oil from the oil pan 12 to the oil control valve 51. The discharge oil passage 54 returns the lubricating oil from the oil control valve 51 to the oil pan 12. The advancing oil passage 55 circulates lubricating oil between the oil control valve 51 and each of the advancing chambers 35. The retarding oil passage 56 circulates lubricating oil between the oil control valve 51 and each of the retarding chambers 36. The intermediate oil passage 57 circulates lubricating oil between the oil control valve 51 and the intermediate chamber 42.

The oil control valve 51 is directly connected to each of the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42 by the advancing oil passage 55, the retarding oil passage 56, and the intermediate oil passage 57. That is, the intermediate oil passage 57 circulates lubricating oil between the oil control valve 51 and the intermediate chamber 42 without the oil flowing through any of the advancing chambers 35 or the retarding chambers 36.

The oil control valve 51 switches the passages connected to the supply oil passage 53 and discharge oil passage 54 between the advancing oil passage 55, the retarding oil passage 56, and the intermediate oil passage 57 to change the state of the lubricating oil supplied to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42.

The structure and operation modes of the oil control valve 51 will be described with reference to Figs. 5 to 8. Figs. 5 to 8 are cross-sectional views taken along the axial direction of the valve 51, each showing different operation modes. Arrows in the drawings indicate the flow of lubricating oil.

The oil control valve 51 includes a single housing 70, which has a plurality of ports, and a single spool 60, which is arranged in the housing 70. The spool 60 is moved relative to the housing 70 to switch the ports that are in communication with each other. This changes the state in which lubricating oil is supplied to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42.

The housing 70 includes first and second supply ports 71 and 72 connected to the supply oil passage 53, first and second discharge ports 73 and 74 connected to the discharge oil passage 54, an advancing port 75 connected to the advancing oil passage 55, a retarding port 76 connected to the retarding oil passage 56, and an intermediate port 77 connected to the intermediate oil passage 57. An intermediate communication passage 78 is formed in the wall of the housing 70 between the second supply port 72 and the second discharge port 74 to connect the second supply port 72 and the intermediate port 77. The spool 60 includes a first partition wall 61, which corresponds to the advancing port 75, a second partition wall 62, which corresponds to the retarding port 76, and third, fourth, and fifth partition walls 63, 64, and 65, which correspond to the intermediate port 77. Based on the positional relationship of the partition walls of the spool 60 and the ports of the housing 70, the communication state of the ports located at the side of the supply oil passage 53 and discharge oil passage 54 and the ports located at the side of the variable valve timing mechanism 30 changes as described below.

The advancing port 75 communicates with only either one of the first supply port 71 and the first discharge port 73. The retarding port 76 communicates with only either one of the first supply port 71 and the second discharge port 74. The intermediate port 77 communicates with only either one of the second supply port 72 and the second discharge port 74.

The operation mode of the oil control valve 51 may be set to any one of first to fourth modes in accordance with the axial position of the spool 60 relative to the housing 70.

Fig. 5 shows the oil control valve 51 in the first operation mode (mode Al), in which the spool 60 is located at a first position in the housing 70. The communication state of the ports in this case will now be described. The advancing port 75 is in communication with the first supply port 71, while the first partition wall 61 blocks communication between the advancing port 75 and the first discharge port 73. The retarding port 76 is in communication with the second discharge port 74, while the second partition wall 62 blocks communication between the retarding port 76 and the first supply port 71. The intermediate port 77 is in communication with the second discharge port 74 via the intermediate communication passage 78, while the fifth partition wall 65 blocks communication between the intermediate port 77 and the second supply port 72.

When the ports are in the communication state described above, the lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the first supply port 71, the advancing port 75, and the advancing oil passage 55 to be supplied to the advancing chambers 35. The lubricating oil in the retarding chambers 36 sequentially flows through the retarding oil passage 56, the retarding port 76, the second discharge port 74, and the discharge oil passage 54 to be returned to the oil pan 12. The lubricating oil in the intermediate chamber 42 sequentially flows through the intermediate oil passage 57, the intermediate port 77, the intermediate communication passage 78, the second discharge port 74, and the discharge oil passage 54 to be returned to the oil pan 12.

Fig. 6 shows the oil control valve 51 in the second operation mode (mode A2), in which the spool 60 is located at a second position in the housing 70. The communication state of the ports in this case will now be described. The advancing port 75 is in communication with the first supply port 71, while the first partition wall 61 blocks communication between the advancing port 75 and the first discharge port 73. The retarding port 76 is in communication with the second discharge port 74, while the second partition wall 62 blocks communication between the retarding port 76 and the first supply port 71. The intermediate port 77 is in communication with the second supply port 72, while the third partition wall 63 blocks communication between the intermediate port 77 and the second discharge port 74.

When the ports are in the communication state described above, the lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the first supply port 71, the advancing port 75, and the advancing oil passage 55 to be supplied to the advancing chambers 35. The lubricating oil in the retarding chambers 36 sequentially flows through the retarding oil passage 56, the retarding port 76, the second discharge port 74, and the discharge oil passage 54 to be returned to the oil pan 12. The lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the second supply port 72, the intermediate port 77, and the intermediate oil passage 57 to be supplied to the intermediate chamber 42.

Fig. 7 shows the oil control valve 51 in the third operation mode (mode A3), in which the spool 60 is located at a third position in the housing 70. The communication state of the ports in this case will now be described. The first partition wall 61 blocks communication of the advancing port 75 with the first supply port 71 and first discharge port 73. The second partition wall 62 blocks communication of the retarding port 76 with the first supply port 71 and second discharge port 74. The intermediate port 77 is in communication with the second supply port 72, while the fourth partition wall 64 blocks communication between the intermediate port 77 and the intermediate communication passage 78 as well as the second discharge port 74. The port communication state described above restricts the flow of lubricating oil from the oil pump 18 via the oil control valve 51 to the advancing chambers 35 and the flow from the advancing chambers 35 via the oil control valve 51 to the oil pan 12. This also restricts the flow of lubricating oil from the oil pump 18 via the oil control valve 51 to the retarding chambers 36 and the flow from the retarding chambers 36 via the oil control valve 51 to the oil pan 12. At the same time, the intermediate chamber 42 is supplied with the lubricating oil from the oil pump 18 that flows sequentially through the supply oil passage 53, the second supply port 72, the intermediate port 77, and the intermediate oil passage 57.

Fig. 8 shows the oil control valve 51 in the fourth operation mode (mode AA), in which the spool 60 is located at a fourth position in the housing 70. The communication state of the ports in this case will now be described. The advancing port 75 is in communication with the first discharge port 73, while the first partition wall 61 blocks communication between the advancing port 75 and the first supply port 71. The retarding port 76 is in communication with the first supply port 71, while the second partition wall 62 blocks communication between the retarding port 76 and the second discharge port 74. The intermediate port 77 is in communication with the second supply port 72, while the third partition wall 63 blocks communication between the intermediate port 77 and the intermediate communication passage 78 as well as the second discharge port 74.

When the ports are in the communication state described above, the lubricating oil in the advancing chambers 35 sequentially flows through the advancing oil passage 55, the advancing port 75, the first discharge port 73, and the discharge oil passage 54 to be returned to the oil pan 12. The lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the first supply port 71, the retarding port 76, and the retarding oil passage 56 to be supplied to the retarding chambers 36. The lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the second supply port 72, the intermediate port 77, and the intermediate oil passage 57 to be supplied to the intermediate chamber 42.

Fig. 9(A) shows the relationship of the operation modes of the oil control valve 51 and the state of the lubricating oil supplied to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42. Fig. 9(B) shows the relationship of the operation modes and the operation of the variable valve timing mechanism 30 (indicated as WT in Fig. 9(B)) and the intermediate lock pin 41. In Fig. 9(B), the label of "project" indicates a state in which the intermediate lock pin 41 is projectable from the vane 33A. Such a projectable state includes both a state in which the lubricating oil applies force to the intermediate lock pin 41 in the projecting direction and a state in which the intermediate lock pin 41 is projected out of the vane 33A.

The procedures for an "intermediate lock process" will now be described in detail with reference to Fig. 10. The intermediate lock process is executed to lock the valve timing INVT at the intermediate timing INVTmdl with the intermediate lock mechanism 40. With further reference to Fig. 11, an example of operation of the vane rotor 33 and the intermediate lock mechanism 40 based on the process will now be described. The "intermediate lock process" is executed by the electronic control unit 80 when the engine is operating. Once the process is completed, the same process is repetitively executed in order from step SIlO as long as the engine continues to operate.

In this process, first, at step SIlO, the electronic control unit 80 determines whether or not a request for locking the valve timing INVT at the intermediate timing INVTmdl (hereinafter the "lock request") has been issued. The lock request is issued or cancelled through another control process executed by the electronic control unit 80. Specifically, if it is determined that the warming of the engine 1 has not been completed, the issuance of the lock request is prohibited. If it is determined that the warming of the engine 1 has been completed and the engine 1 is idling, the electronic control unit 80 issues the lock request. When the engine switches from an idle state to a normal driving state, the electronic control unit 80 cancels the lock request. The output from the coolant temperature sensor 83 is used to determine whether or not the engine 1 is warm.

When determining that the lock request has not been issued in step SIlO, the electronic control unit 80 performs the same determination process again after a predetermined control interval elapses. When determining that the lock request has been issued, the electronic control unit 80 proceeds to step S120 and determines whether or not the rotational phase of the vane rotor 33 relative to the housing 31 is retarded from the intermediate phase PM. This determination is based on the valve timing INVT obtained from the outputs from the crank position sensor 81 and the cam position sensor 82.

When determined in step S120 that the rotational phase of the vane rotor 33 is retarded from the intermediate phase PM, as shown in the state of Fig. 11 (B) , the electronic control unit 80 skips step S130 and proceeds to step S140. On the other hand, when determined that the rotational phase of the vane rotor 33 is advanced from the intermediate phase PM, as shown in the state of Fig. 11 (A) , the electronic control unit 80 performs step S130 and then step S140.

At step S130, the rotational phase of the vane rotor 33 relative to the housing 31 is shifted to a rotational phase that is retarded from the intermediate phase PM and retarded from a rotational phase corresponding to the retarding side end of the intermediate lock groove 45 (hereinafter "intermediate retard phase PLM") . Here, the intermediate retard phase PLM is arranged between the retarding side end of the intermediate lock groove 45 and the most retarded phase PL and set in the proximity of the retarding side end of the intermediate lock groove 45. Thus, for example, when the vane rotor 33 is located at the rotational phase shown in Fig. 11 (A) before the process of step S130 is performed, the rotational phase of the vane rotor 33 is shifted to the rotational phase shown in Fig. 11 (B) .

At step S140, the spool 60 of the oil control valve 51 is moved relative to the housing 70 to switch the operation mode of the valve 51 to the first mode. This supplies lubricating oil to the advancing chambers 35 and discharges lubricating oil from the retarding chambers 36. Thus, the vane rotor 33 is driven toward the advancing side relative to the housing 31. In this state, lubricating oil is discharged from the intermediate chamber 42 so that force is applied to the intermediate lock pin 41 in the projecting direction. As the vane rotor 33 is advanced and the intermediate lock pin 41 reaches a position corresponding to the intermediate lock groove 45, the distal portion of the intermediate lock pin 41 projects out of the vane 33A and enters the intermediate lock groove 45. That is, as the rotational phase of the vane rotor 33 shifts from the state shown in Fig. 11 (B) to the state shown in Fig. 11 (C) , the distal portion of the intermediate lock pin 41 comes into contact with the bottom surface of the intermediate lock groove 45 as shown in the state of Fig 11 (C) .

The vane rotor 33 is further advanced from the state of Fig. 11 (C) by maintaining the oil control valve 51 in the first mode with the distal portion of the intermediate lock pin 41 being arranged in the intermediate lock groove 45. As a result, the intermediate lock pin 41 moves along the intermediate lock groove 45 toward the advancing side. When the rotational phase of the vane rotor 33 relative to the housing 31 reaches the intermediate phase PM, the side of the intermediate lock pin 41 comes into contact with a wall surface defining the intermediate lock hole 44. The intermediate lock pin 41 then projects to its full extent from the vane 33A and is fitted in the intermediate lock hole 44 as shown in the state of Fig. 11 (D) .

Next, at step S150, the electronic control unit 80 determines whether or not the lock request has been cancelled. When determining that the lock request is being issued, the electronic control unit 80 performs the same determination after a predetermined interval elapses. Thus, after the intermediate lock pin 41 is fitted into the intermediate lock hole 44, the oil control valve 51 is maintained in the first mode as long as the intermediate lock request is continuously issued. This keeps the lubricating oil in the advancing chambers 35 applying force to the vane rotor 33 acting toward the advancing side. In other words, the intermediate lock pin 41 is maintained in a state in which its side is pressed against the wall surface of the intermediate lock hole 44.

If it is determined that the lock request has been cancelled, the operation mode of the oil control valve 51 is switched to one of the second, third, and operation modes based on the present request for the valve timing INVT. That is, if there is a request for advancing the valve timing

INVT, the second mode is selected. If there is a request for retarding the valve timing INVT, the fourth mode is selected. If there is a request for holding the valve timing INVT, the third mode is selected.

As described above, when a lock request is issued, that is, when the engine is idling in a warm state, the valve timing INVT is locked at the intermediate timing INVTmdl . This maintains the valve timing INVT at the intermediate timing INVTmdl when the idle engine 1 stops operating. Thus, when the engine 1 is subsequently started, the valve timing INVT is set at the intermediate timing INVTmdl. This improves the startability .

The variable valve device for an internal combustion engine according to the present embodiment has the advantages described below. (1) In the present embodiment, the intermediate oil passage 57 is used to supply lubricating oil to the intermediate chamber 42 and discharge lubricating oil from the intermediate chamber 42. Therefore, the operation state of the intermediate lock mechanism 40 is switchable regardless of the state of the lubricating oil supplied to the advancing chambers 35 and the retarding chambers 36 during operation of the engine. That is, the single oil control valve 51 switches the operation state of the intermediate lock mechanism 40 regardless of the state in which lubricating oil is supplied to the advancing chambers 35 and the retarding chambers 36 during operation of the engine .

(2) In the present embodiment, the variable valve device includes the oil control valve 51, which is selectively operable in the first to fourth modes. When using such a conventional variable valve device, if the operation mode of the oil control valve 51 is switched to the first mode based on the lock request when the rotational phase of the vane rotor 33 relative to the housing 31 is advanced from the intermediate phase PM, the intermediate lock pin 41 is not fitted into the intermediate lock hole 44. That is, in the first mode, although the intermediate lock pin 41 is capable of projecting out of the vane rotor 33, the vane rotor 33 is driven toward the advancing side relative to the housing 31. This increases the circumferential distance between the intermediate lock pin 41 and the intermediate lock hole 44. As a result, although the intermediate lock pin 41 can be projected out the vane rotor 33, the intermediate lock pin 41 is not fitted into the intermediate lock hole 44.

In contrast, in the present embodiment, the rotational phase of the vane rotor 33 is shifted to the intermediate retard phase PLM when the rotational phase of the vane rotor 33 relative to the housing 31 is advanced from the intermediate phase PM. Then, the vane rotor 33 is driven toward the advancing side relative to the housing 31 to reduce the circumferential distance between the intermediate lock pin 41 and the intermediate lock hole 44. When the intermediate lock pin 41 is aligned with the intermediate lock hole 44, the intermediate lock pin 41 is fitted into the intermediate lock hole 44. Therefore, the valve timing INVT is locked at the intermediate timing INVTmdl in accordance with a lock request.

(3) In the present embodiment, when the intermediate lock pin 41 is fitted into the intermediate lock hole 44, the lubricating oil in the advancing chambers 35 continuously applies to the vane rotor 33 force for driving the vane rotor toward the advancing side relative to the housing 31. This continuously maintains the side of the intermediate lock pin 41 pressed against the wall surface of the intermediate lock hole 44. Thus, the intermediate lock pin 41 and the intermediate lock hole 44 are held engaged with each other in a further preferable manner.

(4) The present embodiment includes the intermediate lock groove 45, the area of which is large enough to receive the distal portion of the intermediate lock pin 41 and which is greater than that of the intermediate lock hole 44. Therefore, even if the rotation speed of the housing 31 and the vane rotor 33 relative to each other is relatively high, the intermediate lock pin 41 is fitted into the intermediate lock groove 45. Since the intermediate lock groove 45 has a smaller depth than the intermediate lock hole 44, the side of the intermediate lock pin 41, which moves along the intermediate lock groove 45 toward the intermediate lock hole 44, comes into contact with the wall surface that forms the intermediate lock hole 44. That is, after the distal portion of the intermediate lock pin 41 is fitted into the intermediate lock groove 45, the intermediate lock pin 41 does not pass by the intermediate lock hole 44 even if the vane rotor 33 is driven toward the advancing side relative to the housing 31 at a high speed. Accordingly, contact between the side of the intermediate lock pin 41 and the wall surface of the intermediate lock hole 44 ensures that the intermediate lock pin 41 is fitted into the intermediate lock hole 44.

[Second Embodiment]

A variable valve device for an internal combustion engine according to a second embodiment of the present invention will now be discussed with reference to Figs. 12 to 18.

The way in which the variable valve device of the present embodiment differs from the first embodiment will now be described. A housing 90 is used in lieu of the housing 70 of the oil control valve 51 in the first embodiment, and the positions of the advancing port and retarding port in this housing 90 are reversed from the housing 70. The intermediate lock groove 45 in the first embodiment extends from the intermediate lock hole 44 toward the retarding side. In the present embodiment, an intermediate lock groove 46 is used in lieu of the intermediate lock groove 45. The intermediate lock groove 46 extends from the intermediate lock hole 44 toward the advancing side. The difference from the first embodiment associated with such changes will now be described in further detail. Like or same reference numerals are given to those components that are the same as the corresponding components of the first embodiment. Such elements will not be described.

The structure and operation modes of the oil control valve 51 will now be described with reference to Figs. 12 to 15. Figs. 12 to 15 are cross-sectional views taken along the axial direction of the valve 51, each showing different operation modes. Arrows in the drawings indicate the flow of lubricating oil.

The oil control valve 51 includes a single housing 90, which has a plurality of ports, and a single spool 60, which is arranged in the housing 90. The spool 60 is moved relative to the housing 90 to switch the ports that are in communication with each other. This changes the state in which lubricating oil is supplied to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42.

The housing 90 includes first and a second supply ports 91 and 92 connected to the supply oil passage 53, first and second discharge ports 93 and 94 connected to the discharge oil passage 54, a retarding port 96 connected to the retarding oil passage 56, an advancing port 95 connected to the advancing oil passage 55, and an intermediate port 97 connected to the intermediate oil passage 57. An intermediate communication passage 98 is formed in the wall of the housing 90 between the second supply port 92 and the second discharge port 94 to connecting the second supply port 92 and the intermediate port 97.

The spool 60 includes a first partition wall 61 corresponding to the retarding port 96, a second partition wall 62 corresponding to the advancing port 95, and a third, fourth, and fifth partition wall 63, 64, and 65 corresponding to the intermediate port 97. Based on the positional relationship of the partition walls of the spool 60 and the ports of the housing 90, the communication state of the ports located at the side of the supply oil passage

53 and discharge oil passage 54 and the ports located at the side of the variable valve timing mechanism 30 changes as described below.

The retarding port 96 communicates with only either one of the first supply port 91 and the first discharge port 93. The advancing port 95 communicates with only either one of the first supply port 91 and the second discharge port 94. The intermediate port 97 communicates with only either one of the second supply port 92 and the second discharge port 94.

The operation mode of the oil control valve 51 may be set to any one of first to fourth modes in accordance with the axial position of the spool 60 relative to the housing 90.

Fig. 12 shows the oil control valve 51 in the first operation mode (mode Bl), in which the spool 60 is positioned at a first position in the housing 90. The communication state of the ports in this case will now be described. The retarding port 96 is in communication with the first supply port 91, while the first partition wall 61 blocks communication between the retarding port 96 and the first discharge port 93. The advancing port 95 is in communication with the second discharge port 94, while the second partition wall 62 blocks communication between the advancing port 95 and the first supply port 91. The intermediate port 97 is in communication with the second discharge port 94 through the intermediate communication passage 98, while the fifth partition wall 65 blocks communication between the intermediate port 97 and the second supply port 92.

When the ports are in the communication state described above, the lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the first supply port 91, the retarding port 96, and the retarding oil passage 56 to be supplied to the retarding chambers 36. The lubricating oil in the advancing chambers 35 sequentially flows through the advancing oil passage 55, the advancing port 95, the second discharge port 94, and the discharge oil passage 54 to be returned to the oil pan 12. The lubricating oil in the intermediate chamber 42 sequentially flows through the intermediate oil passage 57, the intermediate port 97, the intermediate communication passage 98, the second discharge port 94, and the discharge oil passage 54 to be returned to the oil pan 12.

Fig. 13 shows the oil control valve 51 in the second mode (mode B2), in which the spool 60 is located at a second position in the housing 90. The communication state of the ports in this case will now be described. The retarding port 96 is in communication with the first supply port 91, while the first partition wall 61 blocks communication between the retarding port 96 and the first discharge port 93. The advancing port 95 is in communication with the second discharge port 94, while the second partition wall 62 blocks communication between the advancing port 95 and the first supply port 91. The intermediate port 97 is in communication with the second supply port 92, while the third partition wall 63 blocks communication between the intermediate port 97 and the second discharge port 94.

When the ports are in the communication state described above, the lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the first supply port 91, the retarding port 96, and the retarding oil passage 56 to be supplied to the retarding chambers 36. The lubricating oil in the advancing chambers 35 sequentially flows through the advancing oil passage 55, the advancing port 95, the second discharge port 94, and the discharge oil passage 54 to be returned to the oil pan 12. The lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the second supply port 92, the intermediate port 97, and the intermediate oil passage 57 to be supplied to the intermediate chamber 42.

Fig. 14 shows the oil control valve 51 in the third operation mode (mode B3), in which the spool 60 is located at a third position in the housing 90. The communication state of the ports in this case will now be described. The first partition wall 61 blocks communication of the retarding port 96 with the first supply port 91 and the first discharge port 93. The second partition wall 62 blocks communication of the advancing port 95 with the first supply port 91 and the second discharge port 94. The intermediate port 97 is in communication with the second supply port 92, while the fourth partition wall 64 blocks communication between the intermediate port 97 and the intermediate communication passage 98 as well as the second discharge port 94.

The port communication state described above restricts the flow of lubricating oil from the oil pump 18 via the oil control valve 51 to the retarding chambers 36 and the flow from the retarding chambers 36 via the oil control valve 51 to the oil pan 12. This also restricts the flow of lubricating oil from the oil pump 18 via the oil control valve 51 to the advancing chambers 35 and the flow from the advancing chambers 35 via the oil control valve 51 to the oil pan 12. At the same time, the intermediate chamber 42 is supplied with the lubricating oil from the oil pump 18 that flow sequentially through the supply oil passage 53, the second supply port 92, the intermediate port 97, and the intermediate oil passage 57.

Fig. 15 shows the oil control valve 51 in the fourth operation mode (mode B4), in which the spool 60 is located at a fourth position in the housing 90. The communication state of the ports in this case will now be described. The retarding port 96 is in communication with the first discharge port 93, while the first partition wall 61 blocks communication between the retarding port 96 and the first supply port 91. The advancing port 95 is in communication with the first supply port 91, while the second partition wall 62 blocks communication between the advancing port 95 and the second discharge port 94. The intermediate port 97 is in communication with the second supply port 92, while the third partition wall 63 blocks communication between the intermediate port 97 and the intermediate communication passage 98 as well as the second discharge port 94. When the ports are in the communication state described above, the lubricating oil in the retarding chambers 36 sequentially flows through the retarding oil passage 56, the retarding port 96, the first discharge port 93, and the discharge oil passage 54 to be returned to the oil pan 12. The lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the first supply port 91, the advancing port 95, and the advancing oil passage 55 to be supplied to the advancing chambers 35. The lubricating oil from the oil pump 18 sequentially flows through the supply oil passage 53, the second supply port 92, the intermediate port 97, and the intermediate oil passage 57 to be supplied to the intermediate chamber 42.

Fig. 16(A) shows the relationship of the operation modes of the oil control valve 51 and the state of the lubricating oil supplied to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42. Fig. 16(B) shows the relationship of the operation modes and the operation of the variable valve timing mechanism 30 (indicated as WT in Fig. 16(B)) and the intermediate lock pin 41. In Fig. 16(B), the label of "project" indicates a state in which the intermediate lock pin 41 is projectable from the vane 33A. Such a projectable state includes both a state in which the lubricating oil applies force to the intermediate lock pin 41 in the projecting direction and a state in which the intermediate lock pin 41 is projected out of the vane 33A.

The procedures for an "intermediate lock process" will now be described in detail with reference to Fig. 17. The intermediate lock process is executed to lock the valve timing INVT at the intermediate timing INVTmdl with the intermediate lock mechanism 40. With further reference to Fig. 18, an example of operation of the vane rotor 33 and the intermediate lock mechanism 40 based on the process will now be described. The "intermediate lock process" is executed by the electronic control unit 80 when the engine is operating. Once the process is completed, the same process is repetitively executed in order from step S210 as long as the engine continues to operate.

In this process, first, at step S210, the electronic control unit 80 determines whether or not a lock request has been issued. The lock request is issued or cancelled in the same manner as in the first embodiment.

When determining that the lock request has not been issued in step S210, the electronic control unit 80 performs the same determination process again after a predetermined control interval elapses. When determining that the lock request has been issued, the electronic control unit 80 proceeds to step S220 and determines whether or not the rotational phase of the vane rotor 33 relative to the housing 31 is advanced from the intermediate phase PM. This determination is based on the valve timing INVT obtained from the outputs of the crank position sensor 81 and the cam position sensor 82.

When determined in step S220 that the rotational phase of the vane rotor 33 is advanced from the intermediate phase PM, as shown in the state of Fig. 18(B), the electronic control unit 80 skips step S230 and proceeds to step S240. On the other hand, when determined that the rotational phase of the vane rotor 33 is advanced from the intermediate phase PM, as shown in the state of Fig. 18(A), the electronic control unit 80 performs step S230 and then step S240.

At step S230, the rotational phase of the vane rotor 33 relative to the housing 31 is shifted to a rotational phase that is advanced from the intermediate phase PM and advanced from a rotational phase corresponding to the advancing side end of the intermediate lock groove 45 (hereinafter "intermediate advance phase PHM") . Here, the intermediate advance phase PHM is arranged between the advancing side end of the intermediate lock groove 45 and the most advanced phase PH and set in the proximity of the advancing side end of the intermediate lock groove 45. Thus, for example, when the vane rotor 33 is located at the rotational phase shown in Fig. 18(A) before the process of step S230 is performed, the rotational phase of the vane rotor 33 is shifted to the rotational phase shown in Fig. 18(B) .

At step S240, the spool 60 of the oil control valve 51 is moved relative to the housing 90 to switch the operation mode of the valve 51 to the first mode. This supplies lubricating oil to the retarding chambers 36 and discharges lubricating oil from the advancing chambers 35. Thus, the vane rotor 33 is driven toward the retarding side relative to the housing 31. In this state, lubricating oil is discharged from the intermediate chamber 42 so that force is applied to the intermediate lock pin 41 in the projecting direction. As the vane rotor 33 is retarded and the intermediate lock pin 41 reaches a position corresponding to the intermediate lock groove 45, the distal portion of the intermediate lock pin 41 projects out of the vane 33A and enters the intermediate lock groove 45. That is, as the rotational phase of the vane rotor 33 shifts from the state shown in Fig. 18 (B) to the state shown in Fig. 18(C), the distal portion of the intermediate lock pin 41 comes into contact with the bottom surface of the intermediate lock groove 45 as shown in the state of Fig 18 (C) .

The vane rotor 33 is further retarded from the state of Fig. 18(C) by maintaining the oil control valve 51 in the first mode with the distal portion of the intermediate lock pin 41 being arranged in the intermediate lock groove 45. As a result, the intermediate lock pin 41 moves along the intermediate lock groove 45 toward the retarding side. When the rotational phase of the vane rotor 33 relative to the housing 31 reaches the intermediate phase PM, the side of the intermediate lock pin 41 comes into contact with a wall surface defining the intermediate lock hole 44. The intermediate lock pin 41 then projects to its full extent from the vane 33A and is fitted in the intermediate lock hole 44 as shown in the state of Fig. 18(D) .

Next, at step S250, the electronic control unit 80 determines whether or not the lock request has been cancelled. When determining that the lock request is being issued, the electronic control unit 80 performs the same determination after a predetermined interval elapses. Thus, after the intermediate lock pin 41 is fitted into the intermediate lock hole 44, the oil control valve 51 is maintained in the first mode as long as the intermediate lock request is continuously issued. This keeps the lubricating oil in the retarding chambers 36 applying force to the vane rotor 33 that is acting toward the retarding side. In other words, the intermediate lock pin 41 is maintained in a state in which its side is pressed against the wall surface of the intermediate lock hole 44. If it is determined that the lock request has been cancelled, the operation mode of the oil control valve 51 is switched to one of the second, third, and operation modes based on the present request for the valve timing INVT. That is, if there is a request for retarding the valve timing INVT, the second mode is selected. If there is a request for advancing the valve timing INVT, the fourth mode is selected. If there is a request for holding the valve timing INVT, the third mode is selected.

As described above, when the engine is idling in a warm state, the valve timing INVT is locked at the intermediate timing INVTmdl . This maintains the valve timing INVT at the intermediate timing INVTmdl when the idle engine 1 stops operating. Thus, when the engine 1 is subsequently started, the valve timing INVT is set at the intermediate timing INVTmdl. This improves the startability . The variable valve device for an internal combustion engine according to the present embodiment has the same advantages as advantages (1) to (4) of the first embodiment.

[Other Embodiments]

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the present invention may be embodied in the following forms.

The oil control valve 51 of the first embodiment may additionally operate in a fifth mode (mode A5) . When the oil control valve 51 operates in the fifth mode, the advancing chambers 35 are supplied with lubricating oil, the retarding chambers 36 discharge lubricating oil, and the supply and discharge of lubricating oil to and from the intermediate chamber 42 are stopped.

The intermediate lock groove 45 in the first embodiment may be omitted. This would still obtain advantage (1) of the above embodiments and achieve the first object of the present invention.

In the first embodiment, the supply of lubricating oil to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42 may be controlled by more than one oil control valve 51. This would still obtain advantage (4) of the above embodiments and achieve the second object of the present invention.

The oil control valve 51 of the second embodiment may additionally operate in a fifth mode (mode A5) . When the oil control valve 51 operates in the fifth mode, the advancing chambers 35 discharge lubricating oil, the retarding chambers 36 are supplied with lubricating oil, and the supply and discharge of lubricating oil to and from the intermediate chamber 42 are stopped.

The intermediate lock groove 46 in the second embodiment may be omitted. This would still obtain advantage (1) of the above embodiments and achieve the first object of the present invention.

In the second embodiment, the supply of lubricating oil to the advancing chambers 35, the retarding chambers 36, and the intermediate chamber 42 may be controlled by more than one oil control valve 51. This would still obtain advantage (4) of the above embodiments and achieve the second object of the present invention.

The intermediate lock mechanism 40 of each of the above- described embodiments includes the intermediate lock pin 41, which is arranged in the vane rotor 33, and the intermediate lock hole 44, which is arranged in the housing 31. However, the structure of the intermediate lock mechanism 40 is not limited in such a manner. For example, the intermediate lock pin 41 may be arranged in the housing 31, and the intermediate lock hole 44 may be arranged in the vane rotor 33.

The lubricating oil in the intermediate chamber 42 may generate a force for projecting the intermediate lock pin 41, and the lock spring 43 may generate a force for retracting the intermediate lock pin 41.

The present invention may be applied to a variable valve device having a variable valve timing mechanism for the exhaust valve 23.

The structure of the variable valve device to which the present invention is applied is not limited to the contents illustrated in the above-described embodiments. The present invention may be applied to any type of variable valve device as long as it includes a variable valve timing mechanism that varies the valve timing, an intermediate lock mechanism that locks the valve timing at a specific intermediate timing, and an oil pressure supply unit that controls the state of the oil supplied to these mechanisms with an oil control valve. In such a case, advantages that are the same as or similar to the above-described embodiments are obtained.

The present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

Claims

CLAIMS :

1. A variable valve device for an internal combustion engine, the variable valve device comprising: a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing; a restriction mechanism that locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing; and an oil pressure mechanism that includes an oil pressure control valve and controls the state in which oil is supplied to the variable mechanism and the restriction mechanism by the oil pressure control valve; wherein in accordance with the state in which oil is supplied by the oil pressure mechanism, the restriction mechanism is switched between a lock state in which the valve timing is locked at the intermediate timing and a release state in which the valve timing is released from the lock state, the variable valve device being characterized in that: the oil pressure mechanism supplies oil to the restriction mechanism and discharges oil from the restriction mechanism through an intermediate oil passage connecting the oil pressure control valve and the restriction mechanism without extending through an advancing chamber and a retarding chamber of the variable mechanism; the oil pressure mechanism controls the state in which oil is supplied to the advancing and retarding chambers of the variable mechanism and the restriction mechanism with the single oil control valve; and the oil pressure mechanism changes the state in which oil is supplied to the restriction mechanism when the engine is operating to switch between the lock state and the release state.

2. A variable valve device for an internal combustion engine, the variable valve device comprising: a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing; a restriction mechanism that locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing; and an oil pressure mechanism that includes an oil pressure control valve and controls the state in which oil is supplied to the variable mechanism and the restriction mechanism by the oil pressure control valve, wherein: the variable mechanism includes an input rotation member, which is rotated by force transmitted from a crankshaft of the internal combustion engine, and an output rotation member, which is rotated together with a camshaft of the engine valve by force transmitted from the input rotation member, with the input rotation member and the output rotation member defining therebetween an advancing chamber and a retarding chamber; the restriction mechanism includes a restriction member and an intermediate chamber arranged in a first rotation member, which is either one of the input rotation member and the output rotation member, and a restriction hole formed in a second rotation member, which is the other one of the input rotation member and the output rotation member, the restriction member being operated in a state projected out of the first rotation member and a state retracted into the first rotation member, and the intermediate chamber being supplied with oil from the oil pressure mechanism; the restriction mechanism projects the restriction member out of the first rotation member when oil is supplied to the intermediate chamber in a first supply state by the oil pressure mechanism; the restriction mechanism projects the restriction member out of the first rotation member so that the restriction member is fitted into the restriction hole of the second rotation member to lock the valve timing of the engine valve at the intermediate timing; the restriction mechanism separates the restriction member from the restriction hole and retracts the restriction member into the first rotation member when oil is supplied to the intermediate chamber in a second supply state by the oil pressure mechanism to release the valve timing from the intermediate timing, the variable valve device being characterized in that: the oil pressure mechanism supplies oil to the intermediate chamber and discharges oil from the intermediate chamber through an intermediate oil passage, which is connected to the oil pressure control valve and the intermediate chamber without extending through the advancing chamber and the retarding chamber; the oil pressure mechanism controls the state in which oil is supplied to the advancing chamber, the retarding chamber, and the intermediate chamber with the single oil pressure control valve; and the oil pressure mechanism changes the state in which oil is supplied to the intermediate chamber when the engine is operating to switch the state in which the restriction member is operated.

3. The variable valve device according to claim 2, being characterized in that: the oil pressure mechanism includes oil passages through which oil is circulated between the oil pressure control valve and the variable mechanism, the oil passages including an advancing oil passage connecting the oil pressure control valve and the advancing chamber, a retarding oil passage connecting the oil pressure control valve and the retarding chamber, and the intermediate oil passage connecting the oil pressure control valve and the intermediate chamber.

4. The variable valve device according to claim 2 or 3, being characterized in that: the oil pressure control valve operates in operation modes that set the state in which oil is supplied to the advancing chamber, the retarding chamber, and the intermediate chamber, the operation modes including: mode Al, which is for supplying oil to the advancing chamber, discharging oil from the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the first supply state; mode A2, which is for supplying oil to the advancing chamber, discharging oil from the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the second supply state; mode A3, which is for stopping the supply and discharge of oil to and from the advancing chamber, stopping the supply and discharge of oil to and from the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the second supply state; and mode A4 , which is for discharging oil out of the advancing chamber, supplying oil to the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the second supply state.

5. The variable valve device according to claim 4, being characterized in that: the oil pressure control valve further operates in an operation mode, which sets the state in which oil is supplied to the advancing chamber, the retarding chamber, and the intermediate chamber, of mode A5, which is for supplying oil to the advancing chamber, discharging oil from the retarding chamber, and stopping the supply and discharge of oil to and from the intermediate chamber.

6. The variable valve device according to claim 4 or 5, being characterized in that: when a request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the output rotation member is located relative to the input rotation member at a rotational phase advanced from an intermediate phase corresponding to the intermediate timing, the variable valve device retards the rotational phase of the output rotation member relative to the input rotation member from the intermediate phase and then drives the output rotation member toward an advancing side relative to the input rotation member while applying force acting to project the restriction member out of the first rotation member with the oil pressure mechanism so that the restriction member is fitted into the restriction hole.

7. The variable valve device according to any one of claims 4 to 6, being characterized in that: when the request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the restriction member is fitted in the restriction hole, the variable valve device maintains the operation mode of the oil pressure control valve in the mode Al .

8. The variable valve device according to any one of claims 4 to 7, being characterized in that: the first rotation member includes a restriction groove having a smaller depth than the restriction hole; the restriction groove extends along a circumferential path of the restriction member from the restriction hole toward a retarding side; and when force acting to project the restriction member out of the first rotation member is applied to the restriction member in a state in which the restriction member is located at a position retarded from a retarding side end of the restriction groove, the output rotation member is driven toward an advancing side relative to the input rotation member so that a distal portion of the restriction member first moves into the restriction groove and the output rotation member is then continuously driven toward the advancing side relative to the input rotation member so that the distal portion of the restriction member is moved toward the advancing side in the restriction groove and subsequently fitted into the restriction hole.

9. The variable valve device according to claim 2 or 3, being characterized in that: the oil pressure control valve operates in operation modes that set the state in which oil is supplied to the advancing chamber, the retarding chamber, and the intermediate chamber, the operation modes including: mode Bl, which is for discharging oil from the advancing chamber, supplying oil to the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the first supply state; mode B2, which is for discharging oil from the advancing chamber, supplying oil to the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the second supply state; mode B3, which is for stopping the supply and discharge of oil to and from the advancing chamber, stopping the supply and discharge of oil to and from the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the second supply state; and mode B4, which is for supplying oil to the advancing chamber, discharging oil out of the retarding chamber, and maintaining the state in which oil is supplied to the intermediate chamber in the second supply state.

10. The variable valve device according to claim 9, being characterized in that: the oil pressure control valve further operates in an operation mode, which sets the state in which oil is supplied to the advancing chamber, the retarding chamber, and the intermediate chamber, of mode B5, which is for discharging oil from the advancing chamber, supplying oil to the retarding chamber, and stopping the supply and discharge of oil to and from the intermediate chamber.

11. The variable valve device according to claim 9 or 10, being characterized in that: when a request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the output rotation member is located relative to the input rotation member at a rotational phase retarded from an intermediate phase corresponding to the intermediate timing, the variable valve device advances the rotational phase of the output rotation member relative to the input rotation member from the intermediate phase and then drives the output rotation member toward a retarding side relative to the input rotation member while applying force acting to project the restriction member out of the first rotation member with the oil pressure mechanism so that the restriction member is fitted into the restriction hole.

12. The variable valve device according to any one of claims 9 to 11, being characterized in that: when the request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the restriction member is fitted in the restriction hole, the variable valve device maintains the operation mode of the oil pressure control valve in the mode Bl.

13. The variable valve device according to any one of claims 9 to 12, being characterized in that: the first rotation member includes a restriction groove having a smaller depth than the restriction hole; the restriction groove extends along a circumferential path of the restriction member from the restriction hole toward an advancing side; and when force acting to project the restriction member out of the first rotation member is applied to the restriction member in a state in which the restriction member is located at a position advanced from an advancing side end of the restriction groove, the output rotation member is driven toward a retarding side relative to the input rotation member so that a distal portion of the restriction member first moves into the restriction groove and the output rotation member is then continuously driven toward the retarding side relative to the input rotation member so that the distal portion of the restriction member is moved toward the retarding side in the restriction groove and subsequently fitted into the restriction hole.

14. A variable valve device for an internal combustion engine, the variable valve device comprising: a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing; a restriction mechanism that locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing; and an oil pressure mechanism that controls the state in which oil is supplied to the variable mechanism and the restriction mechanism, wherein: the restriction mechanism includes a restriction member and an intermediate chamber arranged in a first rotation member, which is either one of an input rotation member and an output rotation member of the variable mechanism, and a restriction hole formed in a second rotation member, which is the other one of the input rotation member and the output rotation member, the restriction member being operated in a state projected out of the first rotation member and a state retracted into the first rotation member, and the intermediate chamber being supplied with oil from the oil pressure mechanism; the restriction mechanism projects the restriction member out of the first rotation member when oil is supplied to the intermediate chamber in a first supply state by the oil pressure mechanism; the restriction mechanism projects the restriction member out of the first rotation member so that the restriction member is fitted into the restriction hole of the second rotation member to lock the valve timing of the engine valve at the intermediate timing; the restriction mechanism separates the restriction member from the restriction hole and retracts the restriction member into the first rotation member when oil is supplied to the intermediate chamber in a second supply state by the oil pressure mechanism to release the valve timing from the intermediate timing, the variable valve device being characterized in that: the first rotation member includes a restriction groove having a smaller depth than the restriction hole; the restriction groove extends along a circumferential path of the restriction member from the restriction hole toward a retarding side; when the oil pressure mechanism applies force to the restriction member acting to project the restriction member out of the first rotation member in a state in which the restriction member is located at a position retarded from a retarding side end of the restriction groove, the output rotation member is driven toward an advancing side relative to the input rotation member so that a distal portion of the restriction member first moves into the restriction groove and the output rotation member is then continuously driven toward the advancing side relative to the input rotation member so that the distal portion of the restriction member is moved toward the advancing side in the restriction groove and subsequently fitted into the restriction hole; and the oil pressure mechanism changes the state in which oil is supplied to the intermediate chamber when the engine is operating to switch the state in which the restriction member is operated.

15. The variable valve device according to claim 14, being characterized in that: when a request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the output rotation member is located relative to the input rotation member at a rotational phase advanced from an intermediate phase corresponding to the intermediate timing, the variable valve device retards the rotational phase of the output rotation member relative to the input rotation member from a rotational phase corresponding to the retarding side end of the restriction groove and then drives the output rotation member toward the advancing side relative to the input rotation member while applying force acting to project the restriction member out of the first rotation member with the oil pressure mechanism so that the restriction member is fitted into the restriction hole.

16. A variable valve device for an internal combustion engine, the variable valve device comprising: a variable mechanism that varies a valve timing of an engine valve between a most advanced timing and a most retarded timing; a restriction mechanism that locks the valve timing of the engine valve at a specific intermediate timing between the most advanced timing and the most retarded timing; and an oil pressure mechanism that controls the state in which oil is supplied to the variable mechanism and the restriction mechanism, wherein: the restriction mechanism includes a restriction member and an intermediate chamber arranged in a first rotation member, which is either one of an input rotation member and an output rotation member of the variable mechanism, and a restriction hole formed in a second rotation member, which is the other one of the input rotation member and the output rotation member, the restriction member being operated in a state projected out of the first rotation member and a state retracted into the first rotation member, and the intermediate chamber being supplied with oil from the oil pressure mechanism; the restriction mechanism projects the restriction member out of the first rotation member when oil is supplied to the intermediate chamber in a first supply state by the oil pressure mechanism; the restriction mechanism projects the restriction member out of the first rotation member so that the restriction member is fitted into the restriction hole of the second rotation member to lock the valve timing of the engine valve at the intermediate timing; the restriction mechanism separates the restriction member from the restriction hole and retracts the restriction member into the first rotation member when oil is supplied to the intermediate chamber in a second supply state by the oil pressure mechanism to release the valve timing from the intermediate timing, the variable valve device being characterized in that: the first rotation member includes a restriction groove having a smaller depth than the restriction hole; the restriction groove extends along a circumferential path of the restriction member from the restriction hole toward an advancing side; when the oil pressure mechanism applies force to the restriction member acting to project the restriction member out of the first rotation member in a state in which the restriction member is located at a position advanced from an advancing side end of the restriction groove, the output rotation member is driven toward a retarding side relative to the input rotation member so that a distal portion of the restriction member first moves into the restriction groove and the output rotation member is then continuously driven toward the retarding side relative to the input rotation member so that the distal portion of the restriction member is moved toward the retarding side in the restriction groove and subsequently fitted into the restriction hole; and the oil pressure mechanism changes the state in which oil is supplied to the intermediate chamber when the engine is operating to switch the state in which the restriction member is operated.

17. The variable valve device according to claim 16, being characterized in that: when a request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the output rotation member is located relative to the input rotation member at a rotational phase retarded from an intermediate phase corresponding to the intermediate timing, the variable valve device advances the rotational phase of the output rotation member relative to the input rotation member from a rotational phase corresponding to the advancing side end of the restriction groove and then drives the output rotation member toward the retarding side relative to the input rotation member while applying force acting to project the restriction member out of the first rotation member with the oil pressure mechanism so that the restriction member is fitted into the restriction hole.

18. The variable valve device according to any one of claims 2 to 17, being characterized in that: when a request for locking the valve timing of the engine valve at the intermediate timing is issued in a state in which the restriction member is fitted in the restriction hole, the variable valve device generates force for driving the output rotation member toward either one of an advancing side and a retarding side relative to the input rotation member with the oil pressure mechanism.

19. The variable valve device according to any one of claims 2 to 18, being characterized in that: the restriction mechanism switches the restriction member between a projectable state and a retracted state in accordance with a resultant of a force generated by a spring and acting to retract the restriction member into the first rotation member and a force generated by the oil in the intermediate chamber and acting to project the restriction member out of the first rotation member; and the oil pressure mechanism supplies oil to the intermediate chamber in the first supply state and discharges oil from the intermediate chamber in the second supply state.

20. The variable valve device according to any one of claims 2 to 19, being characterized in that: the oil pressure mechanism supplies oil to the advancing chamber and discharges oil from the retarding chamber so as to drive the output rotation member toward an advancing side relative to the input rotation member and thereby advance the valve timing of the engine valve; the oil pressure mechanism discharges oil from the advancing chamber and supplies oil to the retarding chamber so as to drive the output rotation member toward a retarding side relative to the input rotation member and thereby retard the valve timing of the engine valve; and the oil pressure mechanism stops the supply and discharge of oil to and from both the advancing chamber and the retarding chamber so as to hold the rotational phase of the output rotation member relative to the input rotation member and thereby keeping the valve timing of the engine valve fixed.