VALVE TIMING CONTROL APPARATUS

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2013-048412, filed on Mar. 11, 2013, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to a valve timing control apparatus.

BACKGROUND DISCUSSION

A known valve timing control apparatus including a lock mechanism locking a relative rotation phase between a driving-side rotation member and a driven-side rotation member is disclosed, for example, in JP2004-257313A, which will be hereinafter referred to as Reference 1. In the valve timing control apparatus disclosed in Reference 1, a driven-side rotation member is provided at a radially inner side of a driving-side rotation member in a state where a relative rotation phase between the driven-side rotation member and the driving-side rotation member is changeable. In addition, a rotation phase lock mechanism (lock mechanism) is provided to lock or secure the relative rotation phase between the driving-side rotation member and the driven-side rotation member at a lock phase.

The valve timing control apparatus disclosed in Reference 1 includes movable bodies serving as lock members which are projectable and retractable relative to an inner peripheral surface side of the driving-side rotation member. Two grooves serving as recess portions with which respective projection ends of the lock members engage are formed at portions at an outer periphery of the driven-side rotation member so as to constitute a lock mechanism. The relative rotation phase between the driving-side rotation member and the driven-side rotation member is locked in a state where the lock members engage with the corresponding recess portions, which leads to a locked state of the relative rotation phase.

Each of the two recess portions in Reference 1 includes a stepped portion that includes a shallower depth than a depth of the entire recess portion. In a state where the lock member engages with the stepped portion, the relative rotation phase between the driving-side rotation member and the driven-side rotation member is inhibited from being locked, i.e., the relative rotation phase is brought to a restricted state in which an available range of the relative rotation between the driving-side rotation member and the driven-side rotation member is reduced. Specifically, in a case where the relative rotation phase is shifted to an advanced angle side, the lock member for an advanced angle lock portion engages with the stepped portion of the corresponding recess portion. In a case where the relative rotation phase is further shifted to the advanced angle side in the aforementioned engagement state between the lock member and the stepped portion, the lock member for a retarded angle lock portion engages with the stepped portion of the corresponding recess portion. Thereafter, in a case where the relative rotation phase is further shifted to the advanced angle side, the two lock members simultaneously engage with the respective two entire recess portions so that the relative rotation phase is brought to the locked state.

In the valve timing control apparatus disclosed in Reference 1, the depth of the stepped portion to the bottom thereof from the outer peripheral surface of the driven-side rotation member is specified to be substantially a half of the depth of the entire recess portion to the bottom thereof from the outer peripheral surface of the driven-side rotation member.

The lock mechanism of the valve timing control apparatus is provided for determining the valve opening and closing timing so as to smoothly start an internal combustion engine. In a case where an operation for stopping the engine, for example, an operation of an ignition key, is performed, the relative rotation phase of the valve timing control apparatus is shifted to the lock phase so that the engine is stopped after the locked state of the relative rotation is obtained.

In addition, the driven-side rotation member of the valve timing control apparatus is connected to a camshaft of the internal combustion engine. Thus, because of a reaction force from the camshaft, the relative rotation phase changes (vibrates) alternately by a small amount in an advanced angle direction and a retarded angle direction. Therefore, in the valve timing control apparatus disclosed in Reference 1, in a case where the relative rotation phase is shifted in a direction of the lock phase so as to lock or secure the relative rotation phase at the lock phase, the lock member engages with the stepped portion before the lock member engages with the entire recess portion. As a result, the change of the relative rotation phase is reduced to achieve secure and prompt shifting to the lock phase.

Nevertheless, even in a state where the lock member engages with the stepped portion, a possible weak engagement between the lock member and the stepped portion may cause the lock member to disengage from the stepped portion, which may result in wasting time for the shifting of the relative rotation phase to the locked state.

A need thus exists for a valve timing control apparatus which is not susceptible to the drawback mentioned above.

SUMMARY

According to an aspect of this disclosure, a valve timing control apparatus includes a driving-side rotation member receiving a rotation power from a crankshaft of an internal combustion engine, a driven-side rotation member arranged at a radially inner side of the driving-side rotation member and forming a void including an advanced angle chamber and a retarded angle chamber relative to an inner side surface of the driving-side rotation member, the driven-side rotation member arranged coaxially with the driving-side rotation member and rotating integrally with a camshaft for opening and closing a valve of the internal combustion engine, and a lock mechanism including a recess portion formed at one of the driving-side rotation member and the driven-side rotation member, a lock member provided at the other of the driving-side rotation member and the driven-side rotation member to be engageable and disengageable relative to the recess portion, and a biasing member biasing the lock member in a direction in which the lock member engages with the recess portion. The recess portion includes a lock groove portion with which the lock member is configured to engage to lock a relative rotation phase between the driving-side rotation member and the driven-side rotation member at a lock phase, and a restriction groove portion formed at a position connected to the lock groove portion to allow the relative rotation phase to change in a direction approaching the lock phase and to prohibit the relative rotation phase to change in a direction away from the lock phase. The lock groove portion includes a lock bottom surface with which a projecting end portion of the lock member is configured to make contact. The restriction groove portion includes a restriction bottom surface with which the projecting end portion of the lock member is configured to make contact. A second depth from an opening position of the recess portion to the restriction bottom surface is smaller than a first depth from the opening position to the lock bottom surface. The second depth from the opening position to the restriction bottom surface is smaller than a third depth from the restriction bottom surface to the lock bottom surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal section view of a valve timing control apparatus according to an embodiment disclosed here;

FIG. 2 is a cross-sectional view of the valve timing control apparatus taken along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view of the valve timing control apparatus in which each lock member is in a lock released state;

FIG. 4 is a cross-sectional view of the valve timing control apparatus in a most retarded angle lock phase;

FIG. 5 is an explanatory diagram explaining a dimensional relationship of a first lock recess portion;

FIG. 6 is an enlarged cross-sectional view illustrating a state in which the lock member engages with a restriction groove portion;

FIG. 7 is an enlarged cross-sectional view illustrating a locked state of a relative rotation phase at an intermediate lock phase;

FIG. 8 is a cross-sectional view of the valve timing control apparatus according to a first modified embodiment disclosed here;

FIG. 9 is a cross-sectional view illustrating a state in which the lock member engages with the restriction groove portion according to the first modified embodiment;

FIG. 10 is an enlarged cross-sectional view illustrating a state in which the lock member engages with a lock groove portion according to the first modified embodiment;

FIG. 11 is an explanatory diagram explaining a dimensional relationship of the first lock recess portion according to a second modified embodiment disclosed here;

FIG. 12 is an enlarged cross-sectional view illustrating the locked state of the relative rotation phase at the intermediate lock phase according to the second modified embodiment; and

FIG. 13 is an enlarged cross-sectional view illustrating the locked state of the relative rotation phase at the intermediate lock phase according to a third modified embodiment disclosed here.

DETAILED DESCRIPTION

An embodiment will be explained with reference to the attached drawings. As illustrated in FIGS. 1 and 2, a valve timing control apparatus of the embodiment controls an opening and closing timing of an intake valve 2 by changing a relative rotation phase between an outer rotor 10 serving as a driving-side rotation member and an inner rotor 20 serving as a driven-side rotation member (which will be hereinafter simply referred to as a relative rotation phase). The outer rotor 10 rotates in synchronization with a crankshaft 1 of an engine E serving as an internal combustion engine. The inner rotor 20 is connected to a camshaft 3 for opening and closing the intake valve 2 of the engine E. The outer rotor 10 and the inner rotor 20 are coaxially arranged with each other.

The engine E is provided at a vehicle, for example, a passenger car. The valve timing control apparatus is controlled by an engine control unit 5 serving as an electronic control unit (ECU). The engine control unit 5, which will be hereinafter referred to as the ECU 5, acquires feedback information from the engine E or driver's operation information, for example, and operates an electromagnetic phase control valve 31 and an electromagnetic lock control valve 32. The phase control valve 31 and the lock control valve 32 are accommodated within a single valve unit V. A portion of the valve unit V is inserted to be positioned within the valve timing control apparatus.

As illustrated in FIGS. 1 to 4, the valve timing control apparatus includes the outer rotor 10 rotating in synchronization with the crankshaft 1 of the engine E and the inner rotor 20 connected via a connection bolt 23 to the camshaft 3 that opens and closes the intake valve 2 provided at a combustion chamber of the engine E. The outer rotor 10 and the inner rotor 20 are coaxially arranged with a rotation axis X of the camshaft 3. The outer rotor 10 and the inner rotor 20 are relatively rotatable around the rotation axis X.

The outer rotor 10 includes a rotor body 11 in a cylindrical form, a rear block 12, and a front plate 13 all of which are tightened to one another by plural fastening bolts 14. The rear block 12 is arranged in contact with a first end portion of the rotor body 11 along the rotation axis X. The front plate 13 is arranged in contact with a second end portion of the rotor body 11 along the rotation axis X. The rear block 12 is positioned to close an opening of the outer rotor 10 at a first side while the front plate 13 is positioned to close an opening of the outer rotor 10 at a second side. A sprocket 12S is formed at an outer periphery of the rear block 12 so as to serves as a passive portion to which a rotation power is transmitted from the crankshaft 1. The rotor body 11 includes an inner wall surface in a cylindrical form (i.e., a cylindrical inner wall surface) and plural projecting portions 11T projecting in a direction to approach the rotation axis X, i.e., to a radially inner side, the cylindrical inner wall surface and the projecting portions 11T being integrally formed each other.

A pair of guide grooves is formed at the projecting portion 11T radially from the rotation axis X. Lock members 15 each in a plate form are inserted to the respective guide grooves so as to be projectable and retractable, i.e., slidable. Lock springs 16 each serving as a biasing member are provided at an inner portion of the rotor body 11 to bias the respective lock members 15 to come close to the rotation axis X. One of the lock members 15 and the lock spring 16 that biases the aforementioned lock member 15 in a projecting direction thereof constitute a first lock mechanism L1. The other of the lock members 15 and the lock spring 16 that biases the aforementioned lock member 15 in a projecting direction thereof constitute a second lock mechanism L2. Each of the lock members 15 is not limited to include a plate form and may include a rod form, for example.

The inner rotor 20 includes an inner peripheral surface 20S in a cylindrical form coaxial with the rotation axis X and an outer peripheral surface 20T relative to (coaxial with) the rotation axis X. Plural vanes 21 projecting radially outwardly are fitted into the outer peripheral surface 20T. As illustrated in FIG. 1, a flange portion 22 is formed at one end portion of the inner rotor 20 along the rotation axis X. The inner rotor 20 is connected to the camshaft 3 by the connection bolt 23 that is inserted to be positioned within a bore coaxial with the rotation shaft X and formed at a radially inner side of the flange portion 22. As illustrated in FIGS. 2 to 4, advanced angle flow passages 24 connected to respective advanced angle chambers Ca, retarded angle flow passages 25 connected to respective retarded angle chambers Cb, and a pair of lock release flow passages 26 are formed at the inner rotor 20. The inner rotor 20 forms voids relative to an inner side surface of the outer rotor 10, each of the voids including the advanced angle chamber Ca and the retarded angle chamber Cb.

An outer diameter of the outer peripheral surface 20T of the inner rotor 20 is specified to be a value so that the outer peripheral surface 20T of the inner rotor 20 is fitted to projecting ends of the respective projecting portions 11T of the rotor body 11 of the outer rotor 10 in a tightly contacting manner. In addition, a projection length of each of the vanes 21 is specified so that a projecting end of each of the vanes 21 is in contact with the cylindrical inner wall surface of the rotor body 11. Accordingly, the inner rotor 20 is fitted to the outer rotor 10 to form fluid chambers C at an area surrounded by an inner side surface of the rotor body 11, i.e., the cylindrical inner wall surface and the plural projecting portions 11T, and the outer peripheral surface 20T of the inner rotor 20. Further, the vane 21 divides each of the fluid chambers C into the advanced angle chamber Ca and the retarded angle chamber Cb.

A first lock recess portion 27 serving as a recess portion relative to which the lock member 15 of the first lock mechanism L1 is engageable and disengageable, and a second lock recess portion 28 relative to which the lock member 15 of the second lock mechanism L2 is engageable and disengageable are formed at an outer periphery of the inner rotor 20. Specifically, the first lock recess portion 27, the second lock recess portion 28, and a most retarded angle lock recess portion 29 serve as recess portions formed at the outer peripheral surface 20T of the inner rotor 20 to be recessed towards the rotation axis X as illustrated in FIGS. 2 to 5. One of the lock release flow passages 26 is connected to the first lock recess portion 27 while the other of the lock release flow passages 26 is connected to the second lock recess portion 28. One of the advanced angle flow passages 24 connected to the advanced angle chamber Ca is formed in the vicinity of the first lock recess portion 27. The most retarded angle lock recess portion 29 is formed at an opening portion of the aforementioned advanced angle flow passage 24 positioned in the vicinity of the first lock recess portion 27. A connection flow passage 24A is formed in a groove at the outer periphery of the inner rotor 20 for allowing hydraulic oil to flow between the advanced angle flow passage 24 and the advanced angle chamber Ca adjacent to the advanced angle flow passage 24.

As illustrated in FIG. 2, the lock member 15 of the first lock mechanism L1 is fitted to the first lock recess portion 27 and at the same time the lock member 15 of the second lock mechanism L2 is fitted to the second lock recess portion 28 to thereby obtain an intermediate lock phase serving as a lock phase. In addition, as illustrated in FIG. 4, the lock member 15 of the second lock mechanism L2 is fitted to the most retarded angle lock recess portion 29 to thereby obtain a most retarded angle lock phase.

The valve timing control apparatus is configured in a state where the inner rotor 20 is fitted to the inner side of the rotor body 11 of the outer rotor 10, and the rear block 12 and the front plate 13 are arranged at positions to sandwich and dispose the rotor body 11 and the inner rotor 20. The rotor body 11, the rear block 12, and the front plate 13 are connected to one another by the fastening bolts 14. The plural vanes 21 and the two lock members 15 are arranged to contact with an inner side surface of the rear block 12 and an inner side surface of the front plate 13.

A torsion spring 17 is arranged between the rear block 12 of the outer rotor 10 and the inner rotor 20. The torsion spring 17 applies a biasing force until the relative rotation phase at least reaches the intermediate lock phase from a state in which the relative rotation phase is at the most retarded angle, for example.

As mentioned above, in the valve timing control apparatus, the inner rotor 20 is positioned at the radially inner side of the outer rotor 10 to thereby form the fluid chambers C. Each of the fluid chambers C is divided by the vane 21 to the advanced angle chamber Ca and the retarded angle chamber Cb. The advanced angle flow passage 24 is connected to the advanced angle chamber Ca while the retarded angle flow passage 25 is connected to the retarded angle chamber Cb. The lock members 15 of the first lock mechanism L1 and the second lock mechanism L2 are configured to be arranged at positions at which the lock members 15 are fitted to the first lock recess portion 27 and the second lock recess portion 28, respectively.

In the valve timing control apparatus, a timing chain 4 is arranged and wound between an output sprocket 1S provided at the crankshaft 1 of the engine E and the sprocket 12S of the outer rotor 10. Accordingly, the outer rotor 10 rotates in synchronization with the crankshaft 1. In the embodiment, the sprocket 12S is formed at the outer rotor 10. Alternatively, a timing pulley may be formed at the outer rotor 10. Then, the rotation power of the crankshaft 1 may be transmitted to the timing pulley via a timing belt. Further alternatively, a gear portion may be formed at an outer surface of the outer rotor 10. Then, the rotation power of the crankshaft 1 may be transmitted to the gear portion via a gear train. The valve timing control apparatus of the embodiment is not limited to control the opening and closing timing of the intake valve 2 and may control the opening and closing timing of an exhaust valve of the engine E. Alternatively, the valve timing control apparatus of the embodiment may control the opening and closing timing of both the intake valve 2 and the exhaust valve.

In the valve unit V, the phase control valve 31 and the lock control valve 32 are accommodated in a unit case. A flow passage forming shaft portion 33 that is integrally formed at the unit case is inserted to the inner peripheral surface 20S of the inner rotor 20. A groove portion in an annular form connected to a port of the phase control valve 31 and a groove portion in an annular form connected to a port of the lock control valve 32 are formed at an outer periphery of the flow passage forming shaft portion 33. Then, plural seals 34 each in a ring form are provided between the outer periphery of the flow passage forming shaft portion 33 and the inner peripheral surface 20S of the inner rotor 20 so as to separate the aforementioned groove portions from each other.

The engine E includes a hydraulic pump P driven to supply oil stored in an oil pan as hydraulic oil. A flow passage is formed to supply the hydraulic oil from the hydraulic pump P to the phase control valve 31 and the lock control valve 32.

As illustrated in FIG. 5, the first lock recess portion 27 includes a lock groove portion Ta, and a restriction groove portion Tb (stepped portion) at a position connected to an opening of the lock groove portion Ta so as to be formed in a stepped manner by including a shallower depth than a depth of the lock groove portion Ta. In a state where the relative rotation phase is at the intermediate lock phase, the lock member 15 of the first lock mechanism L1 engages with the lock groove portion Ta so as to fix or lock the relative rotation phase at the intermediate lock phase (lock phase). The restriction groove portion Tb is configured to engage with the lock member 15 to thereby allow the relative rotation phase to be shifted in a direction approaching the intermediate lock phase from a retarded angle phase and restrict the relative rotation phase to be shifted in a direction away from the intermediate lock phase. At this time, a positional relation between the restriction groove portion Tb and the lock groove portion Ta may be specified so that the restriction groove portion Tb allows the relative rotation phase to be shifted in a direction approaching the intermediate lock phase from an advanced angle phase.

In a state where the lock member 15 of the first lock mechanism L1 engages with the lock groove portion Ta of the first lock recess portion 27, the lock member 15 of the second lock mechanism L2 engages with the second lock recess portion 28 as illustrated in FIG. 2.

The lock groove portion Ta includes a lock bottom surface Ua with which a projecting end portion 115 of the lock member 15 is contactable. In addition, the lock groove portion Ta includes a main vertical wall surface Wa with which the lock member 15 is contactable, and a sub vertical wall surface Wb with which the lock member 15 makes contact in the intermediate lock phase. Specifically, in the lock groove portion Ta, the main vertical wall surface Wa is formed at a wall portion in a raised manner relative to the lock bottom surface Ua at a position facing the advanced angle side, i.e., a position adjacent to the restriction groove portion Tb. The sub vertical wall surface Wb is formed at a wall portion in a raised manner relative to the lock bottom surface Ua at a position opposite from the aforementioned position adjacent to the restriction groove portion Tb. The main vertical wall surface Wa and the sub vertical wall surface Wb are formed to extend along the depth direction of the first lock recess portion 27. The main vertical wall surface Wa is formed at a portion of an area along the depth direction from an end portion of the lock groove portion Ta at a side of the opening position of the first lock recess portion 27.

The restriction groove portion Tb includes a restriction bottom surface Ub with which the projecting end portion 115 of the lock member 15 is contactable. The restriction groove portion Tb includes a restriction wall Wr formed in a raised manner relative to the restriction bottom surface Ub at a position facing the advanced angle side.

In the embodiment, a projection is formed at the lock bottom surface Ua for easily supplying the hydraulic oil to the projecting end portion 115 of the lock member 15 in a case where the locked state of the relative rotation is released in a state where the lock member 15 engages with the lock bottom surface Ua. In the following explanation, a projection end of the projection is defined as the position of the lock bottom surface Ua. Without forming the projection, a groove may be formed at the lock bottom surface Ua so that the hydraulic oil is supplied to the projecting end portion 115 of the lock member 15 in engagement with the lock bottom surface Ua. In such case, a flat portion of the lock bottom surface Ua serves as the position of the lock bottom surface Ua.

Specifically, a depth (i.e., a distance in a depth direction) from the outer peripheral surface 20T of the inner rotor 20 corresponding to an opening position of the lock groove portion Ta (the first lock recess portion 27) to the lock bottom surface Ua of the first lock recess portion 27 is specified to be a predetermined depth (distance), which will be hereinafter referred to as a first depth D1 serving as a first depth. A depth from the outer peripheral surface 20T of the inner rotor 20 corresponding to the opening position of the lock groove portion Ta (the first lock recess portion 27) to the restriction bottom surface Ub of the first lock recess portion 27, which will be hereinafter referred to as a restriction depth Db serving as a second depth, is specified to be smaller than a depth from the restriction bottom surface Ub to the lock bottom surface Ua, which will be hereinafter referred to as a lock depth Da serving as a third depth. According to the aforementioned depth relationship, the restriction depth Db is smaller than a half of the first depth D1.

A depth from the outer peripheral surface 20T of the inner rotor 20 to a second bottom surface 28U of the second lock recess portion 28, and a depth from the outer peripheral surface 20T of the inner rotor 20 to a third bottom surface 29U of the most retarded angle lock recess portion 29 are specified to be the same. In addition, one of a pair of vertical wall surfaces formed at the second lock recess portion 28 at the advanced angle side forms an advanced angle side vertical wall surface Va with which the lock member 15 makes contact in the intermediate lock phase. The other of the pair of vertical wall surfaces formed at the second lock recess portion 28 at the retarded angle side forms a retarded angle side vertical wall surface Vb with which the lock member 15 is contactable.

A depth of the main vertical wall surface Wa, a depth of the restriction wall Wr, a depth of the sub vertical wall surface Wb of the first lock recess portion 27, a depth of the advanced angle side vertical wall surface Va and a depth of the retarded angle side vertical wall surfaces Vb of the second lock recess portion 28 are specified to be the same. That is, portions of a pair of wall surfaces of the first lock recess portion 27 connected to the lock bottom surface Ua are partially cut and removed, for example, to form the main vertical wall surface Wa and the sub vertical wall surface Wb. In the same way, the advanced angle side vertical wall surface Va and the retarded angle side vertical wall surface Vb are formed.

As illustrated in FIGS. 1 and 2, in the valve timing control apparatus, the outer rotor 10 rotates in a driving rotation direction S by a driving force transmitted from the crankshaft 1 via the timing chain 4. The direction same as the driving rotation direction S in which the inner rotor 20 rotates relative to the outer rotor 10 is referred to as an advanced angle direction Sa. The direction opposite from the advanced angle direction Sa is referred to as a retarded angle direction Sb. In the valve timing control apparatus, a relationship between the crankshaft 1 and the camshaft 3 is specified so that an intake air compression ratio increases in association with an increase of a displacement amount of the relative rotation phase in the advanced angle direction Sa, and the intake air compression ratio decreases in association with the increase of the displacement amount of the relative rotation phase in the retarded angle direction Sb.

Each of the fluid chambers C is divided by the vane 21 into the advanced angle chamber Ca to which the hydraulic fluid is supplied to displace the relative rotation phase in the advanced angle direction Sa, and the retarded angle chamber Cb to which the hydraulic fluid is supplied to displace the relative rotation phase in the retarded angle direction Sb. The relative rotation phase in a state where the vane 21 reaches a moving end (i.e., a rotation limit relative to the rotation axis X) in the advanced angle direction Sa is referred to as the most advanced angle phase. The relative rotation phase in a state where the vane 21 reaches a moving end (i.e., the rotation limit relative to the rotation axis X) in the retarded angle direction Sb is referred to as the most retarded angle phase.

The most retarded angle phase includes not only the moving end in the retarded angle direction Sb but also the vicinity of the moving end in the retarded angle direction Sb. In the same way, the most advanced angle phase includes not only the moving end in the advanced angle direction Sa but also the vicinity of the moving end in the advanced direction Sa.

In the valve timing control apparatus, as illustrated in FIGS. 2 and 7, the lock member 15 of the first lock mechanism L1 engages with the lock groove portion Ta of the first lock recess portion 27 by the biasing force of the lock spring 16 and at the same time the lock member 15 of the second lock mechanism L2 engages with the second lock recess portion 28 by the biasing force of the lock spring 16 so as to restrict and stop the relative rotation between the outer rotor 10 and the inner rotor 20. Such rotation phase is the intermediate lock phase in which optimal intake air timing is obtained for the start of the engine E in a state where the engine E radiates heat.

In addition, as illustrated in FIG. 4, in a state where the lock member 15 of the second lock mechanism L2 engages with the most retarded angle lock recess portion 29 by the biasing force of the lock spring 16, the relative rotation between the outer rotor 10 and the inner rotor 20 is restricted. The thus obtained relative rotation phase is the most retarded angle lock phase serving as the relative rotation phase closer to the most retarded angle. In the most retarded angle lock phase, optimal intake air timing is specified for the start of the engine E in a state where the engine E is inhibited from radiating heat, for example, when the engine E is restarted in the idling stop state.

In a case where the relative rotation phase is changed from the most retarded angle lock phase to the intermediate lock phase, the phase control valve 31 is operated to supply the hydraulic oil to the advanced angle flow passage 24 so that the engagement of the lock member 15 with the most retarded angle lock recess portion 29 is released and the relative rotation phase is shifted in the advanced angle direction Sa. The shifting of the relative rotation phase in the advanced angle direction Sa proceeds so that the lock member 15 of the first lock mechanism L1 first engages with the restriction groove portion Tb of the first lock recess portion 27 by the biasing force of the lock spring 16 as illustrated in FIG. 6.

In a case where the relative rotation phase is shifted in the advanced angle direction Sa, a reaction force from the camshaft 3 is applied to the inner rotor 20. Thus, the relative rotation phase changes (vibrates) by a small amount alternately in the advanced angle direction Sa and the retarded angle direction Sb.

As mentioned above, the restriction depth Db is specified to be smaller than a half of the first depth D1 of the first lock recess portion 27. Thus, as compared to a case where the restriction depth Db is specified to be a half of the first depth D1, for example, a time period may be reduced for the projecting end portion 115 of the lock member 15 of the first lock mechanism L1 to move to a boundary position (i.e., an edge-shaped portion) between the restriction bottom surface Ub and the lock groove portion Ta from the restriction groove portion Tb after the projecting end portion 115 of the lock member 15 enters the restriction groove portion Tb in a case where the relative rotation phase is shifted in the advanced angle direction Sa. The lock member 15 may be promptly brought to a state engaging with the lock groove portion Ta. In addition, in a state where the projecting end portion 115 of the lock member 15 engages with the restriction groove portion Tb, the strong biasing force of the lock spring 16 is maintained, thereby maintaining the strong engagement state of the lock member 15 with the restriction groove portion Tb.

In a case where the reaction force from the camshaft 3 is applied to the inner rotor 20 in the retarded angle direction Sb in a state where the projecting end portion 115 of the lock member 15 engages with the restriction groove portion Tb, the lock member 15 strongly makes contact with the restriction wall Wr. Even in the aforementioned strong contact state, the lock member 15 is maintained in engagement with the restriction groove portion Tb by the strong biasing force of the lock spring 16. As a result, the lock member 15 is inhibited from disengaging from the restriction groove portion Tb.

Then, the relative rotation phase is shifted in the advanced angle direction Sa so that the lock member 15 of the second lock mechanism L2 is brought to a state engaging with the second lock recess portion 28. Afterwards, the lock member 15 of the first lock mechanism L1 is brought to a state engaging with the lock groove portion Ta. Consequently, as illustrated in FIG. 7, the relative rotation phase is locked at the intermediate lock phase. In the aforementioned configuration, the lock depth Da is specified to be greater than the restriction depth Db. Thus, even in a case where dirt or dust enters the lock bottom surface Ua, for example, the engagement of the lock member 15 relative to the lock groove portion Ta may be secured.

In a state where the relative rotation phase reaches the intermediate lock phase, the lock member 15 of the first lock mechanism L1 is positioned close to the sub vertical wall surface Wb of the first lock recess portion 27 with a predetermined clearance. The lock member 15 of the second lock mechanism L2 is positioned close to the advanced angle side vertical wall surface Va of the second lock recess portion 28 with a predetermined clearance. Consequently, the relative rotation phase is securely locked at the intermediate lock phase.

The engine E is stopped in a state where the relative rotation phase is at the intermediate lock phase. At the start of the engine E that is stopped, the locked state of the relative rotation phase at the intermediate lock phase is released to thereby change the relative rotation phase. In the case of releasing the locked state of the relative rotation phase, the hydraulic oil is supplied to the lock release flow passage 26 by the operation of the lock control valve 32.

Because an area at which the lock member 15 of the first lock mechanism L1 is in contact with the sub vertical wall surface Wb of the first lock recess portion 27 is small and an area at which the lock member 15 is in contact with the advanced angle side vertical wall surface Va of the second lock recess portion 28 is small, a small friction force is applied to each of the lock members 15 of the first and second lock mechanisms L1 and L2 when the locked state of the relative rotation phase is released. Thus, a smooth release of the locked state of the relative rotation phase is achievable.

The aforementioned embodiment may be modified or changed as follows. The modified embodiments bear the same reference numerals as the aforementioned embodiment for members including the similar functions.

As illustrated in FIGS. 8 to 10, according to a first modified embodiment, the plural vanes (vane portions) 21 are integrally formed at the inner rotor 20 so that the fluid chamber C is divided into the advanced angle chamber Ca and the retarded angle chamber Cb by each of the vanes 21. A lock mechanism L includes the lock member 15 provided at one of the vanes 21, the lock member 15 moving along the rotation axis X.

In the modified embodiment, the lock member 15 is formed in a column. The lock member 15 is accommodated in a bore portion 21A formed at the vane 21 so as to be slidably movable in the direction along the rotation axis X. The lock member 15 is biased by the lock spring 16 in a direction to project. In addition, the lock member 15 includes a large diameter portion 15A at a first end and a small diameter portion 15B at a second end to thereby form a stepped portion at an intermediate portion. A void is formed at the large diameter portion 15A to accommodate a portion of the lock spring 16.

A penetration bore is formed at the vane 21 so that the small diameter portion 15B of the lock member 15 is inserted to be positioned within the penetration bore. In addition, the lock release flow passage 26 is formed at the vane 21 for operating the lock member 15 in a lock release direction by the supply of the hydraulic oil to the stepped portion of the lock member 15. The first lock recess portion 27 is formed at the rear block 12 so that the projecting end portion 115 of the small diameter portion 15B of the lock member 15 is engageable and disengageable relative to the first lock recess portion 27. At this time, alternatively, a recess portion relative to which the lock member 15 is engageable and disengageable may be formed at the front plate 13.

In the first modified embodiment, in the same way as the aforementioned embodiment, the first lock recess portion 27 includes the lock groove portion Ta and the restriction groove portion Tb that is formed at a position connected to the opening of the lock groove portion Ta so as to be formed in a stepped manner by including a shallower depth than a depth of the lock groove portion Ta. The lock groove portion Ta functions so that the relative rotation phase is locked at the intermediate lock phase (lock phase) by the engagement with the lock member 15 in a state where the relative rotation phase is at the intermediate lock phase. The restriction groove portion Tb functions so as to allow the relative rotation phase to change in a direction approaching the intermediate lock phase and to prohibit the relative rotation phase to change in a direction away from the intermediate lock phase.

The lock groove portion Ta includes the lock bottom surface Ua with which the projecting end portion 115 of the lock member 15 is contactable. The restriction groove portion Tb includes the restriction bottom surface Ub with which the projecting end portion 115 of the lock member 15 is contactable. The depth from the opening position to the lock bottom surface Ua of the first lock recess portion 27 is specified to be a predetermined depth (depth value), i.e., the first depth D1. The depth from the opening position to the restriction bottom surface Ub of the first lock recess portion 27, i.e., the restriction depth Db, is specified to be smaller than the depth from the restriction bottom surface Ub to the lock bottom surface Ua, i.e., the lock depth Da. According to the aforementioned depth relationship, the restriction depth Db is smaller than a half of the first depth D1.

In the first modified embodiment, as compared to a case where the restriction depth Db is specified to be a half of the first depth D1, for example, a time period may be reduced for the projecting end portion 115 of the lock member 15 to move to a boundary position (i.e., an edge-shaped portion) between the restriction bottom surface Ub and the lock groove portion Ta from the restriction groove portion Tb after the projecting end portion 115 of the lock member 15 enters the restriction groove portion Tb in a case where the relative rotation phase is shifted in the advanced angle direction Sa because the restriction depth Db is smaller than the lock depth Da. The lock member 15 may be promptly brought to a state engaging with the lock groove portion Ta. In addition, in a state where the projecting end portion 115 of the lock member 15 engages with the restriction groove portion Tb, the strong biasing force of the lock spring 16 is maintained, thereby maintaining the strong engagement state of the lock member 15 with the restriction groove portion Tb. In a case where the relative rotation phase is shifted in the advanced angle direction Sa, the projecting end portion 115 of the lock member 15 is securely guided and inserted to the lock groove portion Ta to hold the intermediate lock phase.

As illustrated in FIGS. 11 and 12, according to a second modified embodiment, the first lock recess portion 27 includes the lock groove portion Ta and the restriction groove portion Tb that is formed at a position connected to the opening of the lock groove portion Ta so as to be formed in a stepped manner by including a shallower depth than a depth of the lock groove portion Ta in the same way as the aforementioned embodiments. The lock groove portion Ta functions so that the relative rotation phase is locked at the intermediate lock phase (lock phase) by the engagement with the lock member 15 of the first lock mechanism L1 in a state where the relative rotation phase is at the intermediate lock phase. The restriction groove portion Tb functions so as to allow the relative rotation phase to change in a direction approaching the intermediate lock phase from the retarded angle phase and to prohibit the relative rotation phase to change in a direction away from the intermediate lock phase.

In a state where the relative rotation phase reaches the intermediate lock phase, the lock member 15 of the first lock mechanism L1 is positioned close to the main vertical wall surface Wa of the first lock recess portion 27 with a predetermined clearance. The lock member 15 of the second lock mechanism L2 is positioned close to the retarded angle side vertical wall surface Vb of the second lock recess portion 28 with a predetermined clearance. Consequently, the relative rotation phase is securely locked at the intermediate lock phase.

In the second modified embodiment in which the engagement state between the lock members 15 and the first and second recess portions 27 and 28 at the intermediate lock phase is differently specified, a time period may be reduced for the projecting end portion 115 of the lock member 15 of the first lock mechanism L1 to move to a boundary position (i.e., an edge-shaped portion) between the restriction bottom surface Ub and the lock groove portion Ta from the restriction groove portion Tb after the projecting end portion 115 of the lock member 15 enters the restriction groove portion Tb in a case where the relative rotation phase is shifted in the advanced angle direction Sa from the retarded angle side. The lock member 15 may be promptly brought to a state engaging with the lock groove portion Ta. In addition, in a state where the projecting end portion 115 of the lock member 15 engages with the restriction groove portion Tb, the strong biasing force of the lock spring 16 is maintained, thereby maintaining the strong engagement state of the lock member 15 with the restriction groove portion Tb.

As illustrated in FIG. 13, in a third modified embodiment, the second lock recess portion 28 may include a lock groove portion Tc and a restriction groove portion Td including the same depths as the lock groove portion Ta and the restriction groove portion Tb of the first lock recess portion 27 as in the aforementioned embodiments. The lock member 15 of the first lock mechanism L1 engages with the restriction groove portion Tb of the first lock recess portion 27 and thereafter the lock member 15 of the second lock mechanism L2 engages with the restriction groove portion Td of the second lock recess portion 28. In the aforementioned configuration, the lock member 15 at the second lock recess portion 28 operates in the same way as the lock member 15 at the first lock recess portion 27.

Instead of the pair of lock members 15, a single lock member 15 may be provided. Even in such configuration, the relative rotation phase may be locked at a desired phase.

The lock member 15 may be supported to be projectable and retractable relative to the inner rotor 20 (driven-side rotation member) and a recess portion may be formed at the outer rotor 10 (driving-side rotation member). The projecting end portion 115 of the lock member 15 is configured to be engageable and disengageable relative to the recess portion. According to the aforementioned configuration, the secure engagement of the lock member 15 with the recess portion may be achieved, the recess portion at which the lock groove portion Ta and the restriction groove portion Tb are formed adjacent to each other.

According to the aforementioned embodiments, the depth from the opening position of the first lock recess portion 27 corresponding to the outer peripheral surface 20T of the inner rotor 20 to the restriction bottom surface Ub, i.e., the restriction depth Db, is smaller than a half of the depth from the opening position of the first lock recess portion 27 to the lock bottom surface Ua, i.e., the first depth D1. Thus, as compared to a case where the restriction depth Db is specified to be a half of the first depth D1, for example, a time period may be reduced for the projecting end portion 115 of the lock member 15 to move to a boundary position between the restriction bottom surface Ub and the lock groove portion Ta from the restriction groove portion Tb after the projecting end portion 115 of the lock member 15 enters the restriction groove portion Tb in a case where the relative rotation phase between the outer rotor 10 (driving-side rotation member) and the inner rotor 20 (driven-side rotation member) changes in a direction in which the lock member 15 moves to engage with the lock groove portion Ta. The lock member 15 may be promptly brought to a state engaging with the lock groove portion Ta. In addition, in a case where an elastic deformation, for example, the lock spring 16, is used as the biasing member, the biasing force applied to the lock member 15 from the lock spring 16 is large in a state where the lock member 15 is in contact with the restriction bottom surface Ub, as compared to a case where the restriction depth Db is specified to be a half of the first depth D1. The lock member 15 may be maintained in contact with the restriction bottom surface Ub by a strong force. Therefore, in a case where the relative rotation phase between the outer rotor 10 and the inner rotor 20 is shifted in a direction of the intermediate lock phase, the strong engagement state in which the lock member 15 is in engagement with the restriction groove portion Tb is maintained. The relative rotation phase may be also easily brought to the locked state. As a result, a state in which the lock member 15 engages with the restriction groove portion Tb (stepped portion) of the first lock recess portion 27 is securely maintained to smoothly obtain the locked state of the relative rotation phase.

According to the aforementioned embodiments, the lock groove portion Ta of the first lock recess portion 27 includes the main vertical wall surface Wa and the sub vertical wall surface Wb formed to extend along the depth direction of the first lock recess portion 27, and the main vertical wall surface Wa which is positioned adjacent to the restriction groove portion Tb and with which the lock member 15 is contactable is formed at a portion of an area along the depth direction from an end portion of the lock groove portion Ta at a side of the opening position of the first lock recess portion 27.

Accordingly, a contact area between the lock member 15 and the wall portion of the lock groove portion Ta at which the main vertical wall surface Wa is formed may be reduced in a state where the lock member 15 engages with the lock groove portion Ta. As a result, a contact resistance between the lock member 15 and the wall portion in a case where the lock member 15 moves in the lock release direction is reduced to thereby easily release the locked state of the relative rotation.

The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.

VALVE TIMING CONTROL APPARATUS

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Priority Claims (1)