Valve timing control apparatus and method for setting minimum torque

Abstract

In a valve timing control apparatus, a relative rotational phase between a drive rotational member rotated with a crankshaft and a driven rotational member rotated with a camshaft is controlled by a relative rotational phase-controlling mechanism utilizing a fluid pressure in a fluid pressure chamber divided by a vane. The relative rotational phase can be restrained by a locking mechanism at an intermediate phase between most advanced and most retarded angle phases. As a minimum set torque applied by a biasing mechanism to the drive rotational member relative to the driven rotational member, a larger minimum torque required for change from the most retarded angle phase to the intermediate phase during cranking, at a temperature before warming up while fluid pressure is discharged, or at a minimum temperature for relative rotational phase control while a fluid pressure remains, is selected.