Valve timing control device for internal combustion engine

Abstract

A valve timing control device for an internal combustion engine, the valve timing control device includes: a housing; a vane rotor; a lock hole; a lock member; an urging member; a connection passage provided to the vane rotor, and connected to the bolt insertion hole and the back pressure chamber; and an annular passage which is formed between an inner circumference surface of the bolt insertion hole, and an outer circumference surface of a shaft portion of the cam bolt, and which includes one end portion connected to the connection passage, and the other end portion connected to a drain hole formed in the cam shaft.

1 . A valve timing control device for an internal combustion engine, the valve timing control device comprising:
 a housing to which a rotational force is transmitted from a crank shaft, and which includes an operation hydraulic chamber formed therein;   a vane rotor which includes a bolt insertion hole, which is fixed at one end portion of a cam shaft by a cam bolt inserted through the bolt insertion hole, which is received within the housing, which is arranged to be rotated relative to the housing, and which separates the operation hydraulic chamber to a retard angle operation chamber and an advance angle operation chamber;   a lock hole formed on an inner end surface of the housing;   a lock member which is disposed within a sliding movement hole formed in the vane rotor in an axial direction, which is arranged to be moved within the sliding movement hole, and which includes an axial tip end portion that is arranged to be engaged with the lock hole to lock a relative rotation position of the vane rotor with respect to the housing, or to be disengaged from the lock hole to release the lock;   an urging member which is disposed within a back pressure chamber provided on a front side of the sliding movement hole that is opposite to the cam shaft, and which is arranged to urge the lock member toward the lock hole;   a connection passage provided to the vane rotor, and connected to the bolt insertion hole and the back pressure chamber; and   an annular passage which is formed between an inner circumference surface of the bolt insertion hole, and an outer circumference surface of a shaft portion of the cam bolt, and which includes one end portion connected to the connection passage, and the other end portion connected to a drain hole formed in the cam shaft.   
     
     
         2 . The valve timing control device for the internal combustion engine as claimed in  claim 1 , wherein the connection passage includes a first connection groove that is formed in a radial direction on a seat surface which is a front end surface of the vane rotor, on which a head portion of the cam bolt is seated, and that includes one end connected to the back pressure chamber, and the other end connected to the annular passage. 
     
     
         3 . The valve timing control device for the internal combustion engine as claimed in  claim 2 , wherein the connection passage includes a second connection groove which is formed in the radial direction on the front end surface of the vane rotor in the radial direction, and which includes one end connected to the back pressure chamber, and the other end connected to the first connection groove. 
     
     
         4 . The valve timing control device for the internal combustion engine as claimed in  claim 3 , wherein the first connection groove is formed to penetrate in the axial direction; a positioning pin fixed to the one end portion of the cam shaft extends to the first connection groove. 
     
     
         5 . The valve timing control device for the internal combustion engine as claimed in  claim 3 , wherein the first connection groove and the second connection groove are formed to be bent into a crank shape in a longitudinal section; and the first connection groove and the second connection groove are formed between an inner surface of a front plate closing a front end opening of a housing main body of the housing, and an inner surface of a flange-shaped seat portion of a head portion of the cam bolt. 
     
     
         6 . The valve timing control device for the internal combustion engine as claimed in  claim 1 , wherein the cam shaft includes a bolt hole which is formed in the cam shaft in the axial direction, and through which the shaft portion of the cam bolt is inserted, and a discharge passage which is formed between an inner circumference surface of the bolt hole, and an outer circumference surface of the shaft portion of the cam bolt, and which includes one end portion connected to the annular passage, and the other end portion connected to the drain hole; and the discharge passage is constituted by a cylindrical gap formed between the inner circumference surface of the bolt hole and the outer circumference surface of the shaft portion of the cam bolt. 
     
     
         7 . The valve timing control device for the internal combustion engine as claimed in  claim 6 , wherein the bolt hole is formed at a position to confront the bolt insertion hole of the vane rotor in the axial direction. 
     
     
         8 . The valve timing control device for the internal combustion engine as claimed in  claim 7 , wherein the housing includes a cylindrical portion that is formed on an opening edge of an insertion hole into which the cam shaft is inserted, and that extends in the axial direction along the outer circumference surface of the cam shaft, and a groove portion formed on an inner circumference surface of the cylindrical portion; the drain hole is formed from a side of the discharge passage in a radially outward direction of the cam shaft; and the drain hole includes an outer end opening confronting the groove portion. 
     
     
         9 . The valve timing control device for the internal combustion engine as claimed in  claim 1 , wherein the cam shaft includes a retard angle passage and an advance angle passage which are formed in the cam shaft; the vane rotor includes a first oil passage arranged to connect one of the retard angle passage and the advance angle passage, and one of the retard angle operation chamber and the advance angle operation chamber; and the housing includes a second oil passage arranged to connect the other of the retard angle passage and the advance angle passage, and the other of the retard angle operation chamber and the advance angle operation chamber.