Hydraulic tensioner with internal pressure relief
AssigneeBorg-Warner Automotive, Inc.
InventorPhilip J. Mott
Life of this patent
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Abstract
A hydraulic tensioner having a hollow plunger slidably fitted in a cavity in a housing and biased in a protruding direction by a spring and fluid. A check valve permits fluid to only flow into the cavity, and thereby protrude the plunger, but not out of the cavity. A sleeve slidably fits within the plunger hollow forming a small clearance between the lower end of the plunger and sleeve. The plunger is made of an elastic material capable of expanding in diameter upon increases in internal pressure to permit increased fluid flow through the increased clearance and thus release cavity fluid pressure to allow the plunger to recede into the cavity.
Claims15
A hydraulic tensioner for a wrapped power transmission device between two rotating members, comprising:
- a housing with a fluid chamber, said chamber communicating with an external source of pressurized fluid,
- a hollow sleeve positioned within said chamber,
- a hollow plunger positioned within said chamber and capable of extending outward therefrom for bearing against a power transmission device to regulate tension between rotating members, said plunger having a cylindrical outside portion defining an interior space and positioned radially outwardly from and against said sleeve within said interior space, said plunger outside portion being capable of small movement radially away from contact with said sleeve under specified pressure conditions in said interior space,
- a spring member in said chamber biasing said plunger in a direction extending from said chamber,
- a check valve positioned to allow the transfer of pressurized fluid from said source of pressurized fluid to said interior space through said sleeve and to block the transfer of fluid from said interior space to said source,
- a conduit in fluid communication with said chamber to permit passage of fluid from said interior space and through a clearance formed between said plunger outside portion and said sleeve under said specified pressure conditions in said interior space.
In a hydraulic tensioner having a housing with a first fluid chamber and a second fluid chamber, said second chamber communicating with an external source of pressurized fluid, said tensioner having a hollow plunger positioned within said first chamber and biased in a direction extending therefrom by a spring member, said tensioner having a check valve positioned to allow the transfer of pressurized fluid from said second chamber to said hollow plunger in said first chamber, and said tensioner having a pressure relief system to permit release of pressurized fluid from said hollow plunger under specified pressure conditions, said pressure relief system comprising:
- a cylindrical sleeve within said first chamber, wherein said hollow plunger has a cylindrical outside portion positioned radially outwardly from and against said sleeve, said plunger outside portion being capable of small movement radially away from contact with said sleeve under specified pressure conditions in said hollow plunger to permit fluid transfer from said hollow plunger through a clearance formed between said plunger outside portion and said sleeve under said specified pressure conditions.
A hydraulic chain tensioner comprising:
- a housing having a fluid chamber, an inlet passageway, and an exhaust passageway in communication with said fluid chamber;
- a hollow plunger slidably received within the fluid chamber, said plunger having a lower end defining an interior space;
- a spring biasing the plunger in a direction extending from the fluid chamber;
- a cylindrical sleeve in the fluid chamber positioned around said inlet passageway, said sleeve extending upwards from said inlet passageway into said plunger interior space, with said plunger lower end positioned radially outward from said sleeve.
Dependencies are inferred from the claim text.