Variable valve timing mechanism for internal combustion engine

摘要

The variable valve timing gear (1) is used in an internal combustion engine. The drive gear or sprocket (2) is bolted to a housing (15) which has a cylindrical portion and a flat end. The housing contains a piston (7) which can slide axially. The piston moves on helical splines (5) on an axial extension of a drive wheel (3) bolted to the drive gear and the housing. The piston is urged axially towards the end of the housing and away from the camshaft by a coil spring. Balls (20) in the outside portion of the piston may engage in cutouts (17) in the inner diameter of the cylindrical part of the housing there are further meshing helical splines (8,9) on the inner diameter of the annular piston. There are pressure chambers at either end of the piston which may be filled with oil to move it axially.