Hydraulic tensioner having a plunger with a self-contained reservoir and high pressure chamber for buffering

摘要

A hydraulic tensioner device, which is compact in size, simple in construction and can be manufactured efficiently, has a shoe (4) for applying a tensioning force to a chain (3) or belt. The shoe has a plunger (5) which has a hollow portion (6) in which a valve block (7), a spring (9) and an inner sleeve (10) are slidably disposed. The upper end of the inner sleeve is supported within a cylindrical chamber (2) in a tensioner body (1). The tensioner body has an oil passage (11) communicating with an internal space of the inner sleeve. The bottom surface (6A) of the hollow portion and the valve block jointly define therebetween a high pressure chamber (8) filled with an oil supplied from the internal space of the inner sleeve via a check valve (7A) in the valve block. When the plunger is forced upwardly, the oil in the high pressure chamber is discharged through a clearance (S) of a small cross-sectional area defined between the respective outside surfaces of the valve block and the inner sleeve and the inside surface of the hollow portion of the plunger. By virtue of a flow resistance created during the passage of the oil through the clearance, an impact force applied from a chain (3) to a shoe (4) is absorbed.