Patent US3572508A successfully refreshed from Google Patents.
US3572508A
Expired / Lapsed
US
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Filter system for hydraulic circuit
Assignee: Caterpillar Inc
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Filing: 1969-06-30
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Granted: 1971-03-30
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Expires: 1989-06-30
Abstract
Abstract A hydraulic circuit including a reservoir, a pump for withdrawing fluid therefrom and for directing it under pressure through a control valve and to a hydraulic motor and means for directing return fluid back to the reservoir and through a filter which is disposed entirely within the reservoir. The filter has no external fluidtight housing and fluid is filtered by passing outwardly through a hollow filter unit so that the filtered fluid passes at relatively low pressure and velocity into the body of fluid in the reservoir to avoid agitating and aeration of the fluid supply therein.
Inventors
- 👤 Roger A Rice
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:01
CPC Classifications
B; B01; B01D; B01D35/00; B01D35/14; B01D35/147; B01D29/00; B01D29/11; B01D29/13; B01D29/23; B01D35/02; B01D35/027; B01D35/0273; B01D2201/00; B01D2201/04; B01D2201/0407
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
140 words
In a hydraulic circuit which includes a reservoir, a pump for withdrawing hydraulic fluid from the reservoir, a motor to which the fluid may be directed from the pump and a return line from the motor to the reservoir, wherein the improvement comprises a filter disposed within the reservoir and operably associated with the end of the return line, said filter having an element of generally cylindrical configuration with a hollow center, first and second closure means at either end of the element, means to introduce fluid to be filtered through said first closure means, the outer surface of the filter element being exposed to the interior of the reservoir, and relief valve means associated with said first closure means for communicating said hollow center of said filter element with said reservoir when excessive pressure buildup occurs in said filter.
Claim 2
Dependent Claim
140 words
In a hydraulic circuit which includes a reservoir, a pump for withdrawing hydraulic fluid from the reservoir, a motor to which the fluid may be directed from the pump and a return line from the motor to the reservoir, wherein the improvement comprises a filter disposed within the reservoir and operably associated with the end of the return line, said filter having an element of generally cylindrical configuration with a hollow center, first and second closure means at either end of the element, means to introduce fluid to be filtered through said first closure means, the outer surface of the filter element being exposed to the interior of the reservoir, and relief valve means associated with said first closure means for communicating said hollow center of said filter element with said reservoir when excessive pressure buildup occurs in said filter.
Claim 3
Dependent Claim
25 words
The improvement of claim 1 in which the filter has no external housing and fluid passing through the filter element flows directly into the reservoir.
Claim 4
Dependent Claim
57 words
The improvement of claim 1 in which a wall of the reservoir is provided with an opening, means securing an end of the filter to the wall to close said opening, a closure for the opposite end of the filter, and threaded securing means extending through said first end and into the closure at the opposite end.
Claim 5
Dependent Claim
41 words
The improvement of claim 1 wherein said relief valve means comprises a relief valve in the form of a valve element and a spring biasing said valve element against the end of said filter element associated with said first closure means.
Claim 6
Dependent Claim
31 words
The improvement of claim 4 wherein said means to introduce fluid through the first closure means comprises a tubular member and wherein said valve element is slidable on said tubular member.
Claim 7
Dependent Claim
24 words
The improvement of claim 5 wherein said tubular member extends into the hollow center of said element, thereby communicating fluid to said hollow center.
Claim 8
Dependent Claim
43 words
The improvement of claim 6 further including means closing the end of tubular element which extends into said hollow center and at least one perforation in the side of said tubular member intercommunicating the interior of said tubular Member with said hollow center.
Claim 9
Dependent Claim
31 words
The improvement of claim 7 wherein said means closing the end of tubular element comprises a centrally disposed screw extending part way through the filter and threadably engaging said tubular element.
Claim 10
Dependent Claim
25 words
The improvement of claim 4 further including a relief line intercommunicating the spring side of said relief valve element with the interior of said reservoir.
References Cited (Backward Citations)
US2747743A
Cited
US3214023A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-29 | 1974-09-28 | 1975-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-29 | 1978-09-28 | 1979-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-29 | 1982-09-28 | 1983-03-30 | $7700.00 | Window Closed / Lapsed |