Patent ID: 8210142

Claim:
A valve opening/closing timing control apparatus comprising: a phase displacing mechanism for displacing relative phase between a drive-side rotational member rotatable in synchronism with a crank shaft of an internal combustion engine and a driven-side rotational member arranged coaxially relative to the drive-side rotational member and rotatable in unison with a cam shaft for opening/closing at least one of an intake valve and an exhaust valve of the internal combustion engine, by feeding/discharging a work fluid to/from each one of two kinds of pressure chambers whose capacities are variable in complementing manner with each other by means of a movable partition; a locking mechanism capable of locking said relative phase to an intermediate locking phase suitable for starting the internal combustion engine and releasing this lock by a work fluid when needed; an urging mechanism configured to provide an urging function for urging said phase displacing mechanism toward an advancing side in a restricted range between an intermediate restricting phase located more on the retarding side than said intermediate locking phase and a most retarding phase; and wherein said locking mechanism includes: a first locking piece and a second locking piece which are provided on one of said drive-side rotational member and said driven-side rotational member in a spaced apart relationship in the phase displacing direction; a retaining recess provided in the other rotational member for allowing insertion therein of said first locking piece and said second locking piece so as to lock said relative phase; and a restriction assisting retaining recess having opposed ends and having a shallower depth than said retaining recess at an advancing side end thereof and configured for allowing relative displacement of said first locking piece in the retarding direction in a region from said intermediate locking phase to said intermediate restricting phase.