Patent ID: 6435993
Filing Date: 2002-08-20
Classification: F16H

Abstract:
A hydraulic chain tensioner comprising:a housing having a bore; a hollow plunger slidably received within said bore and defining a pressure chamber therebetween, said hollow plunger having inner walls and an upper end with an aperture, said inner walls defining an inner diameter of said hollow plunger; a piston spring biasing said hollow plunger in a protruding direction from said bore; a pressure relief valve assembly provided inside said chamber, said valve assembly having a valve housing comprising an inner chamber and a first valve housing aperture connecting said inner chamber of said valve housing to said pressure chamber such that fluid may flow between said pressure chamber and said inner chamber; said pressure relief valve assembly having a ball and a valve spring positioned inside said inner chamber biasing said ball against said first valve aperture, said ball allowing fluid to enter said inner chamber from said pressure chamber when the fluid pressure inside said pressure chamber reaches a predetermined value; said valve housing having a second valve aperture such that fluid from said inner chamber may flow from said inner chamber; a vent located adjacent to and integral with said valve housing, said vent having a radial diameter, said radial diameter being less than said plunger inner diameter to permit passage of fluid between said vent and said plunger inner wall, said vent including a disc having a first surface, a second surface, and a periphery and a channel formed on said first surface of said disc, said channel having a first end terminating at said periphery of said disc and a second end terminating in a central position of said first surface in a position to establish a connection between the atmosphere and said pressure relief valve through said aperture said passage of fluid being along the entire periphery of said vent.