Patent ID: 6810907
Filing Date: 2004-11-02
Classification: F16H,Y10T

Abstract:
A hydraulic tensioner comprising a tensioner housing, a plunger for exerting a tensioning force on a flexible transmission medium, the plunger being disposed in a blind hole in the tensioner body and projecting therefrom, said blind hole and said plunger together defining a high pressure oil chamber, a passage for delivering oil into said chamber from a high pressure oil supply, and a relief valve, connected to said high pressure oil chamber, for effecting immediate pressure reduction to avoid excessive high pressure in said chamber;wherein said relief valve comprises a valve element receiving bore communicating with an oil supply opening, a valve element, slidable forward and backward in the valve element receiving bore, a spring, biasing the valve element toward the oil supply opening, and an oil relief hole in a peripheral wall of said valve element receiving bore, at a position where it is closed by said valve element when said valve element is moved backward by a rapid increase in oil pressure at said oil supply opening, whereby a quantity of oil is trapped in said valve element receiving bore for damping of the movement of said valve element.