Patent US4112285A successfully refreshed from Google Patents.
US4420937A
Expired / Lapsed
US
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Hydraulic circuit for a variable displacement pump
Assignee: Komatsu Ltd
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Filing: 1981-07-24
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Granted: 1983-12-20
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Expires: 2001-07-24
Abstract
Abstract A hydraulic circuit for a so called feathering control of a variable displacement pump in which displacement of the variable displacement pump is controlled to a minimum when every actuator in a system is not in operation thereby keeping a power loss to a minimum. The hydraulic circuit includes a jet flow sensor for detecting a dynamic pressure of fluid. The jet flow sensor is disposed in a circuit for connecting a system pressure line to a reservoir and is adapted to convert static pressure of the fluid to dynamic pressure thereof. This detected dynamic pressure is introduced into a servo mechanism for the variable displacement pump for effecting feathering control.
Inventors
- 👤 Toshihiro Naruse
- 👤 Kazuo Uehara
- 👤 Hideaki Saito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:11
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/46; F16H61/465; F04; F04B; F04B49/00; F04B49/08
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
152 words
A hydraulic circuit for controlling displacement of a variable displacement pump including a servo mechanism connected thereto for controlling the same, comprising: an actuator driven by said variable displacement pump; a control valve disposed between said variable displacement pump and said actuator for controlling the latter; and means for converting static pressure of a fluid into a dynamic pressure thereof, said means being disposed in a circuit for connecting a system pressure line of the hydraulic circuit to a reservoir when said control valve occupies its neutral position and comprising a body having formed therein an inlet port connected to the system pressure line and an outlet port connected to the reservoir, said body also having formed therein a nozzle provided between said inlet and outlet ports for producing a jet flow of the fluid and a dynamic pressure sensing means operatively connected to the servo mechanism for said variable displacement pump.
Claim 2
Dependent Claim
152 words
A hydraulic circuit for controlling displacement of a variable displacement pump including a servo mechanism connected thereto for controlling the same, comprising: an actuator driven by said variable displacement pump; a control valve disposed between said variable displacement pump and said actuator for controlling the latter; and means for converting static pressure of a fluid into a dynamic pressure thereof, said means being disposed in a circuit for connecting a system pressure line of the hydraulic circuit to a reservoir when said control valve occupies its neutral position and comprising a body having formed therein an inlet port connected to the system pressure line and an outlet port connected to the reservoir, said body also having formed therein a nozzle provided between said inlet and outlet ports for producing a jet flow of the fluid and a dynamic pressure sensing means operatively connected to the servo mechanism for said variable displacement pump.
Claim 3
Dependent Claim
52 words
A hydraulic circuit for controlling displacement of a variable displacement pump as recited in claim 1 wherein said control valve has formed therein a bypass passage in the neutral position thereof and said circuit for connecting the system pressure line to the reservoir is a bypass circuit connected to said bypass passage.
Claim 4
Dependent Claim
42 words
A hydraulic circuit for controlling displacement of a variable displacement pump as recited in claim 1 wherein said circuit for connecting the system pressure line to the reservoir includes a relief valve circuit for relieving a system pressure fluid to the reservoir.
Claim 5
Dependent Claim
40 words
A hydraulic circuit for controlling displacement of a variable displacement pump as recited in claim 1, 2 or 3 further comprising a relief valve for connecting the inlet port of said static to dynamic pressure converting means to the reservoir.
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) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |