Variable valve timing control apparatus of internal combustion engine

Abstract

A variable valve timing control apparatus of an internal combustion engine, has a housing having a plurality of shoes and a vane member having a plurality of vanes dividing each working fluid chamber formed between adjacent two shoes into advance and retard oil chambers. The vane member rotates to an advanced angle side and to a retarded angle side relative to the housing by selectively supplying or exhausting hydraulic pressure in or from the advance oil chamber and the retard oil chamber. A most-advanced angle position and a most-retarded angle position are limited by the fact that one vane touches one shoe from a circumferential direction. Radius of curvature of one of both corners of a base part of the one shoe, which is a corner located at a side where the one vane does not touch, is set to be greater than those of corners of the other shoes.

1 . A variable valve timing control apparatus of an internal combustion engine, comprising:
 a cylindrical housing having, on an inner peripheral surface thereof, a plurality of shoes which protrude in a radially inward direction; and   a vane member secured to a camshaft and having a plurality of vanes which divide each working fluid chamber formed between the adjacent two shoes into an advance oil chamber and a retard oil chamber, the vane member rotating to an advanced angle side and to a retarded angle side relative to the housing by selectively supplying or exhausting a hydraulic pressure in or from the advance oil chamber and the retard oil chamber, and   a most-advanced angle rotational position and a most-retarded angle rotational position being limited by the fact that one certain vane touches one certain shoe from a circumferential direction with the one certain vane pressed against the one certain shoe, and   radius of curvature of one of both corners of a base part of the one certain shoe, which is a corner located at a side where the one certain vane does not touch, being set to be greater than those of corners of the other shoes except the one certain shoe, in a structure in which the most-advanced angle rotational position or the most-retarded angle rotational position is limited with the one certain vane pressed against the one certain shoe.   
     
     
         2 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 1 , wherein:
 radius of curvature of one of both corners of a base part of the one certain shoe, which is a corner located at a side where the one certain vane does not touch, is set to be greater than those of corners of the other shoes except the one certain shoe, in a structure in which the most-advanced angle rotational position and the most-retarded angle rotational position are limited with the one certain vane pressed against the one certain shoe.   
     
     
         3 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 1 , wherein:
 the vane member is configured so that one of a plurality of the vanes is thicker, in the circumferential direction, than the other vanes and the thicker one vane touches at least one of two shoes which are adjacent to each other in the circumferential direction of the thicker one vane, and   radius of curvature of one of both corners of a base part of the one shoe which the thicker one vane touches, which is a corner located at a side where the thicker one vane does not touch, is set to be greater than those of corners of the other shoes which the thicker one vane does not touch.   
     
     
         4 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 3 , wherein:
 the thicker one vane is provided with a lock pin that can protrude and retract in a rotation axis direction of the camshaft,   the housing is provided with a locking hole that receives therein the lock pin, and   a relative rotation of the vane member with respect to the housing is limited by the fact that the lock pin protrudes and engages with the locking hole in accordance with an engine operating condition.   
     
     
         5 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 4 , wherein:
 an outer peripheral surface of the lock pin is circular in cross section,   the thicker one vane provided with the lock pin has an arc cutting portion at at least one side in the circumferential direction on an outer peripheral surface of the thicker one vane, and   a thick part is formed at a base part side corner of the shoe which is an opposite side to the cutting portion.   
     
     
         6 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 5 , wherein:
 the shoe, against which a side of the cutting portion of the thicker one vane provided with the lock pin is pressed, touches the thicker one vane at one side surface of an inner peripheral side of the shoe, and   radius of curvature of one of both corners of a base part of the shoe, which is a corner located at a side where the thicker one vane does not touch, is set to be greater than those of corners of the other shoes except the one certain shoe.   
     
     
         7 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 5 , wherein:
 each of the vanes has, on a top end surface thereof, a seal member that makes sliding contact with an inner circumferential surface of the housing, and   the thicker one vane is provided with not the cutting portion but the seal member at the other side in the circumferential direction on the outer peripheral surface of the thicker one vane.   
     
     
         8 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 5 , wherein:
 the housing has a cylindrical shaped housing main body having both opening ends in an axial direction, a first plate closing one of the both opening ends of the housing main body and having the locking hole, and a second plate closing the other opening end of the housing main body, and   a positioning mechanism, which performs a function of fixing rotational positions in the circumferential direction of the housing main body and the first plate, is provided at the thick part of the shoe which is the opposite side to the cutting portion of the thicker one vane.   
     
     
         9 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 8 , wherein:
 the positioning mechanism has a positioning recessed portion formed at the shoe and a positioning protrusion formed at the first plate, and   the positioning between the housing main body and the first plate is made by inserting the positioning protrusion in the positioning recessed portion.   
     
     
         10 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 1 , wherein:
 the housing has a cylindrical shaped housing main body having both opening ends in an axial direction and a pair of plates closing the both opening ends of the housing main body, and   each of the shoes has a bolt insertion hole into which a bolt is inserted in a rotation axis direction of the camshaft for fixedly connecting the housing main body and a pair of the plates together.   
     
     
         11 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 1 , wherein:
 when the rotation of the vane member relative to the housing is limited to the most-advanced angle rotational position or the most-retarded angle rotational position, the one certain vane touches the base part of the one certain shoe which is located at an outer peripheral side of the one certain shoe.   
     
     
         12 . A variable valve timing control apparatus of an internal combustion engine, comprising:
 a cylindrical housing having, on an inner peripheral surface thereof, a plurality of shoes which protrude in a radially inward direction; and   a vane member secured to a camshaft and having a plurality of vanes which divide each working fluid chamber formed between the adjacent two shoes into an advance oil chamber and a retard oil chamber, the vane member rotating to an advanced angle side and to a retarded angle side relative to the housing by selectively supplying or exhausting a hydraulic pressure in or from the advance oil chamber and the retard oil chamber, and   a most-advanced angle rotational position and a most-retarded angle rotational position being limited by the fact that one certain vane touches one certain shoe from a circumferential direction with the one certain vane pressed against the one certain shoe, and   at least one of both corners of a base part of the one certain shoe which the one certain vane touches, which is a corner located at a side where the one certain vane does not touch, being provided with a thick portion, in a structure in which the most-advanced angle rotational position or the most-retarded angle rotational position is limited with the one certain vane pressed against the one certain shoe.   
     
     
         13 . The variable valve timing control apparatus of the internal combustion engine as claimed in  claim 12 , wherein:
 one of a plurality of the vanes is provided with a lock pin whose outer peripheral surface is circular in cross section and which can move forward and backward in a rotation axis direction of the camshaft,   the housing is provided with a locking hole that receives therein the lock pin,   a relative rotation of the vane member with respect to the housing is limited by the fact that the lock pin protrudes and engages with the locking hole in accordance with an engine operating condition,   the vane provided with the lock pin has an arc cutting portion at at least one side in the circumferential direction on an outer peripheral surface of the vane,   a thick part is formed at the shoe which is an opposite side to the cutting portion,   the thick portion is formed at both corners of a base part of the shoe which the vane touches, and   the vane touches both sides in the circumferential direction of the shoe.   
     
     
         14 . A variable valve timing control apparatus of an internal combustion engine, comprising:
 a cylindrical housing having, at an inner peripheral side of a main body thereof, a plurality of shoes which protrude in a radially inward direction; and   a vane rotor secured to a camshaft and having a plurality of vanes which divide each working fluid chamber formed between the adjacent two shoes into an advance oil chamber and a retard oil chamber, the vane rotor rotating to an advanced angle side and to a retarded angle side relative to the housing by selectively supplying or exhausting a hydraulic pressure in or from the advance oil chamber and the retard oil chamber, and   a most-advanced angle rotational position and a most-retarded angle rotational position being limited by the fact that one certain vane touches one certain shoe from a circumferential direction with the one certain vane pressed against the one certain shoe, and   strength of the one certain shoe which the one certain vane touches being set to be greater than those of the other shoes which no vanes touch, in a structure in which the most-advanced angle rotational position or the most-retarded angle rotational position is limited with the one certain vane pressed against the one certain shoe.