Valve opening/closing timing control apparatus

Abstract

Configured is a valve opening/closing timing control apparatus that supports a torsion spring to an external position in a stable manner. In the valve opening/closing timing control apparatus, a spring holder is supported to a driven side rotary body and the spring holder forms a first engaging portion to which a first arm of the torsion spring is engaged. Further, in an outer wall of a driving side rotary body, there is formed a spring holding portion formed concave in a circumferential region centering around a rotational axis for allowing fitting-in of a part of an inner end of a coil portion of the torsion spring in a direction along the rotational axis.

1 . A valve opening/closing timing control apparatus comprising:
 a driving side rotary body rotatable in synchronism with a crank shaft of an internal combustion engine and a driven side rotary body rotatable in unison and coaxially with a valve opening/closing cam shaft;   a fluid pressure type phase control mechanism for displacing a relative rotational phase between the driving side rotary body and the driven side rotary body in either an advancing direction or a retarding direction; and   an urging mechanism for applying an urging force between the driving side rotary body and the driven side rotary body for displacing the relative rotational phase in a predetermined direction;   wherein the urging mechanism includes a spring holder protruding along the rotational axis and connected to the driven side rotary body and a torsion spring for providing an urging force to the spring holder and the driving side rotary body;   wherein the torsion spring includes a wound-around coil portion, a first arm extending from one end of the coil portion and engaged with the spring holder and a second arm extending from the other end of the coil portion in a radial direction; and   wherein in an outer wall of the driving side rotary body, there are formed a concave spring holding portion supporting an end of the torsion spring and a groove-like arm holding portion holding the second arm.   
     
     
         2 . The valve opening/closing timing control apparatus according to  claim 1 , wherein the spring holding portion is formed spirally along a shape of the end portion of the coil portion of the torsion spring. 
     
     
         3 . The valve opening/closing timing control apparatus according to  claim 1 , wherein the spring holding portion has a shape that holds a portion smaller than or equal to one turn amount of the end of the torsion spring.