TENSIONING DEVICE FOR THE ENDLESS DRIVE IN A TIMING SYSTEM ON A MOTOR VEHICLE

摘要

The invention relates to a tensioning device (1) for the endless drive in a timing system on a motor vehicle, comprising a tensioning piston (5) which can move along a path axis (9) in a housing (3), within (13) which a pressure chamber (15) is located which houses a working medium (17) which brings about a movement of the tensioning piston (5) in the housing (3) and comprises a valve seat (21), connected to the exterior (25) of the tensioning piston (5) by means of an outlet (23) and accommodating a valve body (27) essentially matching the shape of the valve seat (21). The invention is characterised in that the valve body (27) is designed with a shape tapering along the axial path axis (9) to the outlet (23). By means of said tapering off the valve body (27) a chamber (33) between the valve body (27) and the valve seat (21) is larger than in conventional solutions. The path that the working medium (17), on bleeding gas bubbles (37) from the same, takes from the pressure chamber (15) to the outlet (23) is longer which increases the hydraulic resistance and restricts and limits the emptying of working medium (17) from the tensioning piston (5). The above improves the leakage properties of the tensioning device (1).