Valve timing control apparatus of an internal combustion engine

Abstract

A valve timing control apparatus for adjusting a rotational relation of a camshaft relative to a drive unit of an internal combustion engine, includes a clutch unit positioned between the drive unit and the camshaft and including first and second sections connected to the camshaft and movable relative to one another. A freewheel mechanism is placed between the first and second sections, whereby the first and second sections and the freewheel mechanism form each a clamping surface for interaction with confronting surfaces of the camshaft and the drive unit. The clutch unit is actuated by a force-applying unit such as to permit a movement of the camshaft relative to the drive unit from the base position in two opposite directions to respective end positions commensurate with two switching positions, wherein in the base position, the clamping surfaces of the first and second sections is in fixed rotative engagement with the confronting surfaces of the drive unit, thereby blocking a movement of the camshaft relative to the drive unit, whereas in the end positions, the freewheel mechanism so interacts with the confronting surfaces of the camshaft and the drive unit that a movement of the camshaft in one direction is blocked while a movement of the camshaft in the other direction is cleared to allow a changing moment acting on the camshaft to move the camshaft.