US Patent 7556005 Automatic tappet clearance adjusting device and method

An automatic tappet clearance adjuster comprising a unit for adjusting the projection by advancing/retracting an adjust screw from the forward end of a rocker arm, a section for detecting the torque by rotating the adjust screw, and a control mechanism section for controlling the adjusting unit according to the torque value measured by the torque detecting section. The control mechanism section measures the torque value continuously when a valve is closed by retracting the adjust screw from the open state of the valve. A rotation reference position corresponding to the intersection of a first approximation line and a second approximation line approximating the sections immediately before and after the inflection point of differential value of the torque value is detected as a reference point, and the adjust screw is retracted by a set amount from the reference point.