Patent ID: 7497194

Claim:
An automatic tappet clearance adjusting apparatus for adjusting a clearance between a valve and an adjustment screw in an engine, in which said valve that is closed by a spring is opened by being pressed by said adjustment screw on a distal end of a rocker arm, comprising: an adjustment unit for advancing and retracting said adjustment screw from the distal end of said rocker arm to adjust a projection of said adjustment screw; a torque detector for detecting a torque to rotate said adjustment screw; and a control mechanism for controlling said adjustment unit based on a bidirectional torque value successively measured by said torque detector, wherein said control mechanism determines a filtering value produced by smoothing said torque value applied to retract said adjustment screw to close said valve from a state in which said valve is open, identifies, as the reference point, either a location at which a valve head of said valve first contacts a valve seat of said engine, in order to start reducing said filtering value, or a location at which after said valve head of said valve contacts said valve seat of said engine, said adjustment screw is spaced from an end of said valve to thereby hold said filtering value at a constant value, and retracts said adjustment screw from the current position to a position retracted by a set quantity based on said clearance from said reference point.