US3707984A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic valve with leakage control
Assignee: Caterpillar Inc
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Filing: 1971-09-02
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Granted: 1973-01-02
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Expires: 1991-09-02
Abstract
Abstract A hydraulic valve of the spool type with means to trap hydraulic fluid which tends to leak between the spool and the bore of the valve in which it slides and to bypass said fluid to atmosphere or a tank in order to prevent it from flowing past the spool to actuate a hydraulic motor causing it to move or creep when it should be at rest.
Inventors
- 👤 C Bantz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:14
CPC Classifications
F; F16; F16K; F16K27/00; F16K27/04; F16K27/041; F16K27/042; Y; Y10; Y10T; Y10T137/00; Y10T137/5762; Y10T137/7722; Y10T137/7837; Y10T137/7869; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/8667; Y10T137/86694; Y10T137/8671
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
137 words
In a spool valve having a bore and spaced inlet and outlet ports communicating with said bore, a spool reciprocable in said bore and having land means forming a closure between the inlet and outlet ports when the valve is closed, the improvement which comprises: means to prevent leakage of fluid under pressure to said outlet ports when the valve is closed including drain passage means communicating with said bore intermediate said inlet and outlet ports for directing leaked fluid to a low pressure area, and check valve means in said drain passage means, said check valve means being responsive to pressure at the area of communication of said drain passage means with said bore to close said drain passage means when said valve is open and open said drain passage means when said valve is closed.
Claim 2
Dependent Claim
137 words
In a spool valve having a bore and spaced inlet and outlet ports communicating with said bore, a spool reciprocable in said bore and having land means forming a closure between the inlet and outlet ports when the valve is closed, the improvement which comprises: means to prevent leakage of fluid under pressure to said outlet ports when the valve is closed including drain passage means communicating with said bore intermediate said inlet and outlet ports for directing leaked fluid to a low pressure area, and check valve means in said drain passage means, said check valve means being responsive to pressure at the area of communication of said drain passage means with said bore to close said drain passage means when said valve is open and open said drain passage means when said valve is closed.
Claim 3
Dependent Claim
96 words
The invention of claim 1 wherein said check valve means includes a valve element which is biased to an open position by spring means, and piston means reciprocably mounted in said drain passage means and having a port therethrough to permit escape of leaking fluid, said port being dimensioned so as to be too small to pass full fluid flow when the valve is open, and said piston being subject to said full flow and arranged to engage and close the valve element when the valve is open and the piston is subjected to such flow.
Claim 4
Dependent Claim
85 words
The invention of claim 1 wherein said spaced inlet and outlet ports comprise an inlet port and a pair of outlet ports located on opposite sides of said inlet port, said land means comprising a pair of lands on said spool each one of said lands operating to close one of said outlet ports, and wherein said drain passage means comprise a pair of drain passages, each one of said drain passages communicating with said bore and having check valve means in each drain passage.
Claim 5
Dependent Claim
36 words
The invention of claim 3 further including annular chamber means in the wall of said bore to entrap fluid cooperating with each drain passage so as to entrap leaked fluid around the circumference of the bore.
Claim 6
Dependent Claim
115 words
The invention of claim 1 wherein said drain passage means comprise a drain passage and wherein said check valve means comprises a valve element in the form of a ball adapted to sealingly close against a seat and which is urged to the open position by a spring, and further including a piston reciprocably mounted in said drain passage and having means therein for passing leaked fluid when the valve is closed, said means in said piston operating to not pass the full flow of fluid when said valve is open whereby said piston is shifted by the pressure of said full fluid flow to motivate and thereby close said valve element against said seat.
Claim 7
Dependent Claim
16 words
The invention of claim 5 wherein said means in said piston comprise a port extending therethrough.
Claim 8
Dependent Claim
131 words
In a spool valve having a bore with spaced inlet and outlet passages communicating therewith, a spool reciprocable in the bore and having a land forming a closure between the inlet and outlet passages when the valve is closed, the improvement which comprises means to prevent leakage of fluid under pressure to the outlet passage when the valve is closed including an annular chamber in the wall of the bore between the inlet and outlet passages to entrap fluid before it enters the outlet passage, a drain passage to direct such fluid to a low pressure area, and check valve means which is responsive to inlet pressure within the annular chamber to close said drain passage when said valve is open and open said drain passage when said valve is closed.
Claim 9
Dependent Claim
131 words
In a spool valve having a bore with spaced inlet and outlet passages communicating therewith, a spool reciprocable in the bore and having a land forming a closure between the inlet and outlet passages when the valve is closed, the improvement which comprises means to prevent leakage of fluid under pressure to the outlet passage when the valve is closed including an annular chamber in the wall of the bore between the inlet and outlet passages to entrap fluid before it enters the outlet passage, a drain passage to direct such fluid to a low pressure area, and check valve means which is responsive to inlet pressure within the annular chamber to close said drain passage when said valve is open and open said drain passage when said valve is closed.
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) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |