Patent ID: 6086497
Filing Date: 2000-07-11
Classification: F16H

Abstract:
A hydraulic tensioner device for a chain, comprisinga hollow plunger having an upper end and a lower end, the upper end having an outer cylindrical surface, and an internal hollow portion between said upper and lower ends, said hollow portion of the plunger being bounded by an inside surface and a plunger bottom surface and being open at the upper end of said plunger;a shoe attached to the plunger at the lower end of said plunger and adapted to slidably engage the chain;a tensioner body having a cylindrical chamber in which the cylindrical upper end of said plunger is slidably engaged, said chamber having a lower end which is open and is facing the shoe so that said plunger projects downwardly from said cylindrical chamber to enable said shoe to engage the chain; said chamber having an upper end with an oil passage for supplying an oil to the cylindrical chamber;a valve block having a block outside surface conforming to and slidably engaged with said inside surface of said hollow portion, a block bottom surface facing the plunger bottom surface, and a check valve;a spring disposed in said hollow portion and bearing between said plunger bottom surface and said block bottom surface;an inner sleeve having a sleeve outside surface conforming to and slidably engaged with said inside surface of the hollow portion at said upper end of the hollow plunger and extending beyond the plunger into the cylindrical chamber to a stop which engages and limits movement of the sleeve relative to the tensioner body, said inner sleeve engages and limits movement of said valve block into said cylindrical chamber;said inner sleeve having an internal space communicating with said oil passage and serving as an oil reservoir, said block and plunger bottom surfaces defining a high pressure chamber and having a spacing therebetween to define upper and lower bounds of said high pressure chamber, said high pressure chamber adapted to be filled with the oil supplied from said oil passage through said internal space and said check valve when said plunger is displaced in a direction to enlarge the spacing between the block bottom surface and the plunger bottom surface;a first limited clearance between said block outside surface and said inside surface of the hollow portion and a second restricted clearance between the inside surface of the hollow portion and the inner sleeve for discharging oil in said high pressure chamber through said first and second clearances when the plunger is displaced in a direction to reduce the spacing between the block bottom surface and the plunger bottom surface, the attachment of said shoe to said plunger causing said plunger displacement to follow displacement of the shoe.