Patent ID: 6322468
Filing Date: 2001-11-27
Classification: F16H

Abstract:
A hydraulic tensioner for a chain extending between two rotating members, comprising:a tensioner housing having an open bore,a piston having an open lower end and a closed upper end, said piston lower end slidably positioned within said bore and forming a fluid chamber therebetween, said fluid chamber communicating with an external source of pressurized fluid, said piston upper end having an exhaust vent formed therein to permit air and fluid to escape said fluid chamber,a piston spring member biasing said piston in a direction extending from said housing,a check valve positioned to allow the transfer of fluid from said source of pressurized fluid to said chamber and to block return of fluid from said chamber,a pressure relief valve, said pressure relief valve including a valve body positioned in said fluid chamber, said pressure relief valve body including an opening in communication with said fluid chamber, a valve member biased against said opening by a valve spring member, said pressure relief valve member and said valve spring member being adapted under specified maximum pressure conditions within said fluid chamber to permit passage of fluid from said opening through a fluid exit passage and to said exhaust vent,a vent disc adjacent said upper end of said piston between said pressure relief valve and said exhaust vent,said vent disc having a first tortuous vent path in communication with said fluid exit passage and said exhaust vent to permit controlled fluid exit from said pressure relief valve to said exhaust vent,said vent disc having a second tortuous path in communication with said fluid chamber and said exhaust vent to permit controlled fluid exit from said chamber to said exhaust vent.