Hydraulic tensioner with modular inlet check valve with pressure relief
AssigneeBorg-Warner Automotive, Inc.
InventorRoger T. Simpson
Life of this patent
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Abstract
A hydraulic tensioner for a wrapped power transmission device designed to minimize the amount of air present in the pressure chamber. The hydraulic tensioner includes a combination pressure relief-check valve for use with a hollow piston pressure chamber containing a spring within the pressure chamber to bias the piston outward from the bore. The valve housing is designed to reduce the volume of fluid contained within the pressure chamber minimizing the amount of air which may become trapped in the pressure chamber thus improving the performance of the tensioner.
Claims19
A hydraulic tensioner for a wrapped power transmission device between rotating members comprising:
- a housing having a bore, said bore having an inner surface;
- said housing having an aperture in communication with a source of pressurized fluid;
- a hollow piston slidably received within said bore, said piston having an inner surface and an outer surface;
- a piston spring biasing said piston in a direction toward said power transmission device;
- a valve housing comprising a hollow structure having an inner chamber, said valve housing having a plurality of valve housing apertures;
- a fluid filled pressure chamber of annular shape, said pressure chamber having an outer surface defined by said piston inner surface and said bore inner surface, said chamber having an inner surface defined by said valve housing;
- said valve housing having a first valve housing aperture connecting said inner chamber of said valve housing and said pressure chamber, such that fluid may flow between said inner chamber and said pressure chamber;
- and
- said valve housing having a second valve housing aperture arranged adjacent to and connected with said first housing aperture, said second valve housing aperture connecting said inner chamber of said valve housing and said source of pressurized fluid such that fluid may flow between said inner chamber and said source of pressurized fluid.
A method of manufacture of a hydraulic tensioner, said tensioner including a housing with a bore, a hollow piston slidably received within said bore, to define a fluid chamber, a first spring biasing said piston against said housing in a protruding direction, a valve housing positioned within said fluid chamber, and a spring biased check valve including a valve member, a first biasing spring, a first seat, a second biasing spring, and second seat, and a spring retaining member, said method comprising:
- selecting a first minimum pressure in said fluid chamber at which said inlet check valve will open;
- selecting a translatable first valve member, a first spring, and a first valve seat to permit fluid flow through said first valve seat at said first minimum pressure;
- selecting a first maximum pressure in said fluid chamber at which to permit fluid flow through said pressure relief valve, said pressure relief valve including a second valve seat and a second spring, said first valve being biased against said second valve seat by a second spring, said second valve seat and said second spring permitting fluid to flow out of said fluid chamber through said second valve seat a fluid pressure in said fluid chamber exceeding said first maximum pressure;
- assembling said valve within said valve housing;
- and
- arranging said valve housing within said fluid chamber such that said valve housing displaces fluid in said fluid chamber.
A method of manufacture of a hydraulic tensioner, said tensioner including an integral inlet and pressure relief valve housed in a hollow structure, said integral inlet and pressure relief valve comprising an inlet check spring, an inlet check valve member, spring retainer washer, a pressure relief spring seated against said washer, a pressure relief disk adjacent to said pressure relief disk, and a pressure relief seat fixed in relation to said hollow structure, said method comprising:
- selecting a certain amount of pressure at which said pressure relief valve should open;
- calculating the force required to exert such pressure over the face of said disk;
- selecting a length to which said spring must be compressed to achieve said force;
- inserting said pressure relief seat into said hollow structure;
- inserting said inlet check spring into said hollow structure such that said inlet check spring has a first end longitudinally fixed with respect to said valve housing;
- inserting said inlet check valve member into said hollow structure such that said inlet check spring biases said inlet check valve member in the direction away from the closed end of said hollow structure;
- inserting said pressure relief disk into said hollow structure such that said disk is slidably positioned adjacent to said pressure relief seat;
- inserting said pressure relief spring into said hollow structure such that said pressure relief spring is positioned adjacent to said pressure relief disk;
- inserting said spring retainer washer into said hollow structure such that said spring retainer washer is in contact with said pressure relief spring, and such that said pressure relief spring is compressed to said length;
- and
- positioning said spring retainer washer such that its longitudinal location in said hollow structure is fixed.
Dependencies are inferred from the claim text.