US3979292A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Duplex filter system
Assignee: Caterpillar Inc
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Filing: 1973-08-10
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Granted: 1976-09-07
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Expires: 1993-08-10
Abstract
Abstract A duplex filter system having two filterized fluid flow circuits for maintaining continuous fluid flow to an engine or similar liquid utilizing device during a filter change operation. A fluid control system is provided including liquid-obstructing air vent means for selectively venting air under pressure from an empty one of said two circuits while retaining fluid under pressure within the other said circuit during charging of said empty circuit, whereby fluid pressure within the system is regulated, and the fluid flow controlled. Detection means for detecting pressure within each of the two circuits.
Inventors
- 👤 Charles W. Kuhn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:23
CPC Classifications
B; B01; B01D; B01D36/00; B01D36/001; B01D35/00; B01D35/12; B01D35/14; B01D35/147; B01D35/18
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
250 words
In a duplex filter system having two fluid circuits, of the type used in an internal combustion engine, said system including, a working fluid circuit, an alternate fluid circuit, fluid conduit means connecting said circuits to said engine, filter means for filtering foreign materials from said fluid passing through each circuit check valve means proximate an outlet of each of said filter means for preventing reversal of fluid flow in said circuits, by-pass means in each of said circuits for selectively by-passing fluid around said filter means, valve means for redirecting fluid flow through the alternate circuit from said working circuit, means for charging said alternate circuit with liquid while draining fluid from said working circuit to permit a change of filter means in said working circuit, the improvement comprising; a fluid flow control system including liquid obstructing air vent means for selectively venting air from said alternate circuit while charging said circuit with liquid, said air vent means operative to cause liquid pressure to build-up within said alternate circuit sufficiently to open said check valve means associated with said alternate circuit and to permit fluid flow through said check valve to a junction of said alternate circuit and said working circuit, and pressure-detecting means for detecting and registering the pressure in each of said circuits and for indicating when said alternate circuit is fully charged with liquid, and for detecting and registering the pressure level in said working circuit after fluid flow has been redirected to said alternate circuit.
Claim 2
Dependent Claim
250 words
In a duplex filter system having two fluid circuits, of the type used in an internal combustion engine, said system including, a working fluid circuit, an alternate fluid circuit, fluid conduit means connecting said circuits to said engine, filter means for filtering foreign materials from said fluid passing through each circuit check valve means proximate an outlet of each of said filter means for preventing reversal of fluid flow in said circuits, by-pass means in each of said circuits for selectively by-passing fluid around said filter means, valve means for redirecting fluid flow through the alternate circuit from said working circuit, means for charging said alternate circuit with liquid while draining fluid from said working circuit to permit a change of filter means in said working circuit, the improvement comprising; a fluid flow control system including liquid obstructing air vent means for selectively venting air from said alternate circuit while charging said circuit with liquid, said air vent means operative to cause liquid pressure to build-up within said alternate circuit sufficiently to open said check valve means associated with said alternate circuit and to permit fluid flow through said check valve to a junction of said alternate circuit and said working circuit, and pressure-detecting means for detecting and registering the pressure in each of said circuits and for indicating when said alternate circuit is fully charged with liquid, and for detecting and registering the pressure level in said working circuit after fluid flow has been redirected to said alternate circuit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-07 | 1980-03-08 | 1980-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-07 | 1984-03-08 | 1984-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-07 | 1988-03-08 | 1988-09-07 | $7700.00 | Window Closed / Lapsed |