Fluid handling – With means for separating solid material from the fluid – Planar strainer normal to flow path
Reexamination Certificate
1999-02-04
2001-11-06
Rivell, John (Department: 3753)
Fluid handling
With means for separating solid material from the fluid
Planar strainer normal to flow path
C137S576000, C060S329000, C060S454000
Reexamination Certificate
active
06311724
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to reservoirs for power steering systems and more particularly, to reservoirs having fluid flow control features for cold temperature environments.
BACKGROUND OF THE INVENTION
A reservoir is provided in a power steering system to hold a predetermined quantity of hydraulic fluid. Typically, the reservoir has an outlet port that communicates fluid to a power steering pump and an inlet port that returns fluid from a power steering gear back into the reservoir. It is also known to provide a filter inside the reservoir to filter the fluid as it flows from the inlet port to the outlet port.
However, one draw back of such known reservoirs is that hydraulic fluid does not flow fast enough through the filter during cold temperature operation. The colder the hydraulic fluid, the greater the resistance to flow. Such increased viscosity greatly reduces the ability of the fluid to pass through the filter. As a result, an insufficient amount of fluid is supplied to the pump. The insufficient amount of fluid causes cavitation within the pump, which produces undesirable noise and sound.
One known reservoir design has attempted to diminish cold weather effects. The known reservoir utilizes a relatively complex series of angled guide members and a series of filter elements to control the directional flow of fluid returning from the inlet port to the outlet port. However, the elaborate guide system is costly to manufacture and has an unnecessarily large number of parts.
SUMMARY OF THE INVENTION
The present invention is directed to a reservoir for a power steering system having an upper reservoir body connected to a lower reservoir body and has a removable cap for accessing the interior of the reservoir. A filter is disposed within the reservoir at a location to filter fluid entering from an inlet port and exiting through an outlet port. In addition, a re-circulating cover is provided having first and second passages that limit communication between fluid in a main reservoir chamber and fluid in a re-circulating chamber.
In operation, relatively warm fluid from the inlet port flows into the re-circulating chamber and passes through the filter before traveling through the outlet port to a pump. During cold weather operation, the same fluid from the inlet port is continuously re-circulated through the re-circulating chamber to the outlet port, resulting in warming of the fluid as it passes through the power steering system. The re-circulating cover includes venturi slots having predetermined configurations that limit the flow of relatively cold hydraulic fluid in the main reservoir chamber into the re-circulating chamber. Further, at least one orifice is provided in the re-circulating cover that allows flow of warm fluid in the re-circulating chamber into the relatively colder fluid contained in the main reservoir chamber.
According to another embodiment of the present invention, a re-circulating cover is provided having spiral or vortex shaped channels for efficiently delivering re-circulating fluid from the inlet port to the filter, and ultimately to the outlet port and pump.
Therefore, according to the present invention, a sufficient amount of fluid is supplied to the steering pump, even during initial cold weather operation, to greatly reduce, minimize or eliminate unwanted noise.
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patent: 5513490 (1996-05-01), Howell et al.
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patent: 6220283 (2001-04-01), Saarinen et al.
Hagan Thomas W.
Rubin Donald P.
Tracey Robert A.
Key Plastics, Inc.
Rader & Fishman & Grauer, PLLC
Rivell John
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