Patent US3751190A successfully refreshed from Google Patents.
US3751190A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self regulating fluid pump
Assignee: Fiat SpA
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Filing: 1971-11-15
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Granted: 1973-08-07
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Expires: 1991-11-15
Abstract
Abstract A fluid pressure pump of the type in which fluid is pumped by pairs of rotating gears, in which there are provided two pairs of gears and a control valve for by-passing one pair of gears if the delivery pressure of the pump exceeds a threshold value. This reduces the fluid flow through the pump and allows it to create a higher delivery pressure without requiring more power from the input shaft. The control valve is of the slide type and operates to short circuit the delivery side of one of the pairs of gears to its own induction side so that this pair of gears is inoperative when the valve is moved to its intervention position. The main slide of the valve has an auxiliary slide which enables the main slide to operate with a snap action to avoid hunting.
Inventors
- 👤 C Cecchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:14
CPC Classifications
F; F04; F04C; F04C14/00; F04C14/24; F04C14/26; F04C14/02; Y; Y10; Y10T; Y10T137/00; Y10T137/2496; Y10T137/2559; Y10T137/2574; Y10T137/2605; Y10T137/2617
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
449 words
A fluid pump for a hydraulic system comprising: a housing for said pump, two pairs of cooperating gears in said housing, said two pairs of gears being of the same diameter and driven by a single shaft, an induction conduit in said housing leading to one of said pairs of gears, a first passageway in said housing connecting said induction conduit to the other of said pairs of gears, a delivery conduit in said housing leading from said one of said pairs of gears, a second passageway in said housing communicating with said delivery conduit, a bore in said housing, said bore being closed at each end thereof, a number of annular chambers spaced along said bore, a first one of said chambers communicating with said first passageway and a second one of said chambers communicating with said second passageway. a third passageway in said housing communicating with the delivery side of said other pair of gears and a third one of said chambers com-municating with said third passageway, a main slide movable in said bore between first and second positions; said main slide being shaped to allow communication between said third one of said chambers and said second one of said chambers in said first position of the main slide and to allow communication between said first one of said chambers and said third one of said chambers in said second position of the maiN slide, means resiliently biasing said main slide to said first position, a fluid flow path extending between said first and second chambers and communicating with the opposite ends of the main slide, an auxiliary slide movably mounted in said main slide between a first and second position, means resiliently biasing said auxiliary slide to its first position against fluid pressure in said delivery conduit to close said fluid path when the pressure in said delivery conduit is below a predetermined threshold pressure, said auxiliary slide being movable to its second position under pressure in said delivery conduit above said threshold pressure to open said path and to subject one of said ends of the main slide to the delivery conduit pressure to move said main slide to its second position, said main slide, in moving from its said first to its said second position, occupying a third position in which said communication between said first and third chambers and said communication between said second and third chambers are interrupted, a fourth passageway connecting said second and third annular chambers in said bore and a pressure relief valve disposed in said fourth passageway to permit fluid flow from said third chamber to said second chamber when said main slide is in said third position.
Claim 2
Dependent Claim
449 words
A fluid pump for a hydraulic system comprising: a housing for said pump, two pairs of cooperating gears in said housing, said two pairs of gears being of the same diameter and driven by a single shaft, an induction conduit in said housing leading to one of said pairs of gears, a first passageway in said housing connecting said induction conduit to the other of said pairs of gears, a delivery conduit in said housing leading from said one of said pairs of gears, a second passageway in said housing communicating with said delivery conduit, a bore in said housing, said bore being closed at each end thereof, a number of annular chambers spaced along said bore, a first one of said chambers communicating with said first passageway and a second one of said chambers communicating with said second passageway. a third passageway in said housing communicating with the delivery side of said other pair of gears and a third one of said chambers com-municating with said third passageway, a main slide movable in said bore between first and second positions; said main slide being shaped to allow communication between said third one of said chambers and said second one of said chambers in said first position of the main slide and to allow communication between said first one of said chambers and said third one of said chambers in said second position of the maiN slide, means resiliently biasing said main slide to said first position, a fluid flow path extending between said first and second chambers and communicating with the opposite ends of the main slide, an auxiliary slide movably mounted in said main slide between a first and second position, means resiliently biasing said auxiliary slide to its first position against fluid pressure in said delivery conduit to close said fluid path when the pressure in said delivery conduit is below a predetermined threshold pressure, said auxiliary slide being movable to its second position under pressure in said delivery conduit above said threshold pressure to open said path and to subject one of said ends of the main slide to the delivery conduit pressure to move said main slide to its second position, said main slide, in moving from its said first to its said second position, occupying a third position in which said communication between said first and third chambers and said communication between said second and third chambers are interrupted, a fourth passageway connecting said second and third annular chambers in said bore and a pressure relief valve disposed in said fourth passageway to permit fluid flow from said third chamber to said second chamber when said main slide is in said third position.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |