Valve rotating apparatus of internal-combustion engine

Abstract

A valve rotating apparatus of an internal-combustion engine comprises a valve biased in the closing direction by a coil spring, a valve lifter disposed on an engine head in such manner as to be vertically movable together with the valve, a cam formed on a cam shaft for directly driving the valve through the valve lifter, and a thrust rolling bearing retaining the coil spring, the thrust roller bearing comprising an upper washer, a lower washer, and balls held by a cage between the upper and lower washers. The cage is provided between its inner and outer circumferences with a plurality of pockets at regular spatial intervals, a plurality of balls being housing in each pocket; and the inner or outer periphery of each of the upper and lower washers is provided with an axially extending cylindrical portion. The upper washer has the degree of freedom for movement in all directions including X and Y directions, within the same plane. Accordingly, the thrust rolling bearing follows the radial displacement of the coil spring caused by its bending or the like, so that the thrust rolling bearing is moved together with the coil spring, and the intake/exhaust valve can be smoothly rotated. The thrust rolling bearing can also be applied between the valve lifter and a pad disposed thereon.