Valve Timing Control Apparatus

Abstract

A valve timing control apparatus includes a driving rotary member to receive a rotational force from a crankshaft of an engine, and a vane rotor connected with a camshaft and arranged to rotate relative to the driving rotary member, with at least one vane defining a retard pressure chamber and an advance pressure chamber in the inside of the driving rotary member. A lock member is received slidably in the vane of the vane rotor and arranged to engage with a lock hole when the vane is rotated to a predetermined angular position. The lock member includes forward and rearward end portions arranged to receive equal fluid pressures. The lock member further includes a pressure receiving portion to which an operating fluid pressure is selectively applied to force the lock member away from the lock hole.

1 . A valve timing control apparatus comprising:
 a driving rotary member adapted to receive a rotational force from a crankshaft of an internal combustion engine;   a vane rotor which is adapted to be fixed to a camshaft, which is arranged to rotate relative to the driving rotary member within a predetermined angular range, and which includes a vane defining a retard pressure chamber and an advance pressure chamber in an inside of the driving rotary member;   a lock member received in the vane and arranged to slide forwards and rearwards in an axial direction;   a lock hole to receive a forward end of the lock member when the vane is rotated relatively to a predetermined intermediate position between a most retard position and a most advance position; and   a biasing member to urge the lock member toward the lock hole;   wherein the lock member includes a forward end portion to receive a first fluid pressure which is one of a fluid pressure in the retard pressure chamber and a fluid pressure in the advance pressure chamber, in a pressure receiving area, and a rearward end portion to receive the first fluid pressure in a pressure receiving area, the forward and rearward end portions being so shaped that the pressure receiving area of the forward end portion receiving the first fluid pressure is equal to the pressure receiving area of the rearward end portion receiving the first pressure; and   wherein the lock member further includes a pressure receiving portion including a first surface to which an operating fluid pressure is selectively applied, and a second surface which is opened through an air passage formed in the vane rotor, to atmosphere.   
     
     
         2 . The valve timing control apparatus as claimed in  claim 1 , wherein the lock hole is provided with a lock guide groove elongated circumferentially from the lock hole and arranged to allow the vane rotor to rotate relative to the driving rotary member in a state in which the forward end of the lock member is received in the lock guide groove. 
     
     
         3 . The valve timing control apparatus as claimed in  claim 1 , wherein the apparatus further comprises a canceling section to move the lock member out of the lock hole selectively. 
     
     
         4 . The valve timing control apparatus as claimed in  claim 1 , wherein the lock member is a lock pin including an outward flange serving as the pressure receiving portion. 
     
     
         5 . The valve timing control apparatus as claimed in  claim 1 , wherein the driving rotary member includes a cylindrical housing including a shoe projecting radially inwards, and a cover member closing an open end of the housing and including a through hole formed on a radial inner side of an outside circumference of the vane, the vane is formed with the air passage extending to the though hole of the cover member and thereby opening the second surface of the pressure receiving portion to the atmosphere. 
     
     
         6 . The valve timing control apparatus as claimed in  claim 1 , wherein the valve timing control apparatus further comprises a first hydraulic circuit to regulate the fluid pressure in the retard pressure chamber and the fluid pressure in the advance pressure chamber, and a second hydraulic circuit to supply the operating fluid pressure different from the fluid pressure in the retard pressure chamber and the fluid pressure in the advance pressure chamber. 
     
     
         7 . The valve timing control apparatus as claimed in  claim 6 , wherein the first hydraulic circuit includes a first control valve to regulate the fluid pressure in the retard pressure chamber and the fluid pressure in the advance pressure chamber, and the second hydraulic circuit includes a second control valve to regulate the operating fluid pressure applied to the first surface of the pressure receiving portion of the lock member. 
     
     
         8 . The valve timing control apparatus as claimed in  claim 7 , wherein the first control valve is a proportional control valve, and the second control valve has a first valve position to increase the operating fluid pressure and a second valve position to decrease the operating fluid pressure. 
     
     
         9 . The valve timing control apparatus as claimed in  claim 1 , wherein the first fluid pressure received by the forward end portion and the rearward end portion of the lock member is the fluid pressure in the advance pressure chamber. 
     
     
         10 . The valve timing control apparatus as claimed in  claim 2 , wherein the lock guide groove includes a stepped bottom descending stepwise toward the lock hole. 
     
     
         11 . The valve timing control apparatus as claimed in  claim 1 , wherein the vane is a first vane, the lock member is a first lock member received in the first vane, the lock hole is a first lock hole, the biasing member is a first biasing member, the vane rotor further includes a second vane defining a retard pressure chamber and an advance pressure chamber in the inside of the driving rotary member; the valve timing control apparatus further comprises a second lock member received in the second vane and arranged to slide forwards and rearwards in the axial direction, a second lock hole to receive a forward end of the second lock member when the second vane is at a predetermined intermediate position, and a second biasing member to urge the second lock member toward the second lock hole;
 wherein the second lock member includes a forward end portion to receive a second fluid pressure which is one of the fluid pressure in the retard pressure chamber and the fluid pressure in the advance pressure chamber in a pressure receiving area, and a rearward end portion to receive the second fluid pressure in a pressure receiving area, the forward and rearward portions being so shaped that the pressure receiving area of the forward end portion of the second lock member is equal to the pressure receiving area of the rearward end portion of the second lock member; and   wherein the second lock member further includes a pressure receiving portion including a first surface to which an operating fluid pressure is selectively applied, and a second surface which is opened through an air passage formed in the vane rotor, to the atmosphere.   
     
     
         12 . The valve timing control apparatus as claimed in  claim 11 , wherein the first lock hole is provided with a first lock guide groove elongated in a circumferential direction around a rotation axis of the vane rotor from the first lock hole and arranged to allow the vane rotor to rotate relative to the driving rotary member in a state in which the forward end of the first lock member is received in the first lock guide groove, and the second lock hole is provided with a second lock guide groove elongated in the circumferential direction around the rotation axis of the vane rotor from the second lock hole and arranged to allow the vane rotor to rotate relative to the driving rotary member in a state in which the forward end of the second lock member is received in the second lock guide groove. 
     
     
         13 . The valve timing control apparatus as claimed in  claim 12 , wherein the first lock member and the first lock hole are arranged to allow rotation of the vane rotor relative to the driving rotary member within a predetermined angular range in a state in which the first lock member is engaged with the first lock hole; and the second lock member and the second lock hole are arranged to lock the vane rotor to prevent rotation of the vane rotor relative to the driving rotary member when the second lock member is engaged with the second lock hole in the state in which the first lock member is engaged with the first lock hole. 
     
     
         14 . The valve timing control apparatus as claimed in  claim 13 , wherein the second lock guide groove includes a stepped bottom descending stepwise toward the second lock hole. 
     
     
         15 . The valve timing control apparatus as claimed in  claim 14 , wherein the first lock guide groove includes a stepped bottom descending stepwise toward the first lock hole, and the first and second lock holes are so arranged that the second lock member descends the stepped bottom of the second lock guide groove and engages in the second lock hole after the first lock member descends the stepped bottom of the first lock guide groove and engages in the first lock hole. 
     
     
         16 . The valve timing control apparatus as claimed in  claim 15 , wherein a number of steps of the stepped bottom of the first lock guide groove is greater than a number of steps of the stepped bottom of the second lock guide groove. 
     
     
         17 . The valve timing control apparatus as claimed in  claim 16 , wherein a height of a riser wall surface rising from a lowest bottom surface of the second guide groove is greater than a height of a riser wall surface rising from a lowest bottom surface of the first lock guide groove. 
     
     
         18 . The valve timing control apparatus as claimed in  claim 13 , wherein at least one of the first lock hole, the first lock guide groove, the second lock hole and the second lock guide groove is elongated circumferentially. 
     
     
         19 . A valve timing control apparatus comprising:
 a driving rotary member adapted to receive a rotational force from a crankshaft;   a vane rotor which is adapted to be fixed to a camshaft, which is arranged to rotate relative to the driving rotary member within a predetermined angular range, and which includes a vane defining a retard pressure chamber and an advance pressure chamber in an inside of the driving rotary member;   a lock member received in the vane and arranged to slide axially;   a lock receiving portion to receive a forward end of the lock member when the vane is rotated relatively to a predetermined intermediate position between a most retard position and a most advance position; and   a biasing member to urge the lock member toward the lock receiving portion;   wherein the lock member includes a forward end portion to receive a first fluid pressure which is one of a fluid pressure in the retard pressure chamber and a fluid pressure in the advance pressure chamber, and a rearward end portion to receive the first fluid pressure, the forward and rearward end portions being so shaped that a pressure receiving area of the forward end portion receiving the first fluid pressure is equal to a pressure receiving area of the rearward end portion receiving the first pressure; and   wherein the valve timing control apparatus further comprises a canceling section to release the lock member from the lock receiving portion selectively.   
     
     
         20 . The valve timing control apparatus as claimed in  claim 19 , wherein the cancelling section includes a cancelling hydraulic circuit to supply a cancel fluid pressure to a cancel pressure chamber to apply the cancel pressure to a pressure receiving portion of the lock member to move the lock member against an urging force of the biasing member.