US4395878A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for hydraulically driven vehicle
Assignee: Komatsu Ltd
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Filing: 1980-04-25
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Granted: 1983-08-02
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Expires: 2000-04-25
Abstract
Abstract A control system for a hydraulically driven vehicle having a pair of closed loop each including a variable displacement hydraulic pump driven by an engine and a variable displacement hydraulic motor, the control system comprising a charge pump driven by the engine, a directional control valve for speed control and forward and reverse change-over of the vehicle connected with the charge pump, a pair of steering valves connected with the directional control valve, a pair of servo controls each operatively connected with the respective variable displacement hydraulic pumps for controlling the displacement volume thereof, another charge pump driven by the engine, and a manually operated selector valve connected with the another charge pump and the servo controls, the selector valve having formed therein a throttling position and a communication position and normally held in the throttling position and being interlocked with the operation of the steering valves, whereby the selector valve is changed-over to its communication position when either one of the steering valves is manually operated.
Inventors
- 👤 Koichi Morita
- 👤 Kenzo Hoashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:57
CPC Classifications
F; F16; F16H; F16H61/00; F16H61/38; F16H61/40; F16H61/42; B; B60; B60W; B60W10/00; B60W10/04; B60W10/10; B60W10/101; B60W10/103; B60W30/00; B60W30/18; B62; B62D; B62D11/00; B62D11/02; B62D11/06; B62D11/10; B62D11/14; B62D11/18; B62D11/183; F16H61/433
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
276 words
A control system for a hydraulically driven vehicle including a pair of variable displacement hydraulic pumps driven by a prime mover, and a pair of variable displacement hydraulic motors each being connected with the respective variable displacement hydraulic pumps in a closed loop and driven thereby, said control system comprising in combination: a first fixed displacement charge pump driven by said prime mover; directional control valve means for speed control and forward and reverse change-over of the vehicle connected at its input side with said first charge pump; a pair of manually operated steering valve means each connected at its input side with the output side of said directional control valve means; a pair of servo control means each operatively connected with said respective variable displacement hydraulic pumps for controlling the displacement volume thereof and comprising a double acting servo cylinder and a pilot-operated directional control valve associated with said servo cylinder, pilot ports of said pilot-operated directional control valves being connected with said respective steering valve means; a second fixed displacement charge pump driven by said prime mover; selector valve means connected at its input side with said second charge pump and at its output side with said pilot-operated directional control valves for providing hydraulic fluid to said servo cylinders, said selector valve means having formed therein a throttling position and a communication position; means for normally holding said selector valve means in the throttling position; and means for interlocking said selector valve means with the operation of said manually operated steering valve means; whereby said selector valve means is changed-over to its communication position when either one of said steering valve means is operated.
Claim 2
Dependent Claim
276 words
A control system for a hydraulically driven vehicle including a pair of variable displacement hydraulic pumps driven by a prime mover, and a pair of variable displacement hydraulic motors each being connected with the respective variable displacement hydraulic pumps in a closed loop and driven thereby, said control system comprising in combination: a first fixed displacement charge pump driven by said prime mover; directional control valve means for speed control and forward and reverse change-over of the vehicle connected at its input side with said first charge pump; a pair of manually operated steering valve means each connected at its input side with the output side of said directional control valve means; a pair of servo control means each operatively connected with said respective variable displacement hydraulic pumps for controlling the displacement volume thereof and comprising a double acting servo cylinder and a pilot-operated directional control valve associated with said servo cylinder, pilot ports of said pilot-operated directional control valves being connected with said respective steering valve means; a second fixed displacement charge pump driven by said prime mover; selector valve means connected at its input side with said second charge pump and at its output side with said pilot-operated directional control valves for providing hydraulic fluid to said servo cylinders, said selector valve means having formed therein a throttling position and a communication position; means for normally holding said selector valve means in the throttling position; and means for interlocking said selector valve means with the operation of said manually operated steering valve means; whereby said selector valve means is changed-over to its communication position when either one of said steering valve means is operated.
Claim 3
Dependent Claim
41 words
A control system for a hydraulically driven vehicle as recited in claim 1, further comprising: means operatively connected with said selector valve means for reducing the return speed of said selector valve means from the communication position to the throttling position.
Claim 4
Dependent Claim
295 words
A control system for a hydraulically driven vehicle including a pair of variable displacement hydraulic motors each being connected with the respective variable displacement hydraulic pumps in a closed loop and driven thereby, said control system comprising in combination: a first fixed displacement charge pump driven by said prime mover; directional control valve means for speed control and forward and reverse change-over of the vehicle connected at its input side with said first charge pump; a pair of manually operated steering valve means each connected at its input side with the output side of said directional control valve means; a pair of servo control means each operatively connected with said respective variable displacement hydraulic pumps for controlling the displacement volume thereof and comprising a double acting servo cylinder and a pilot-operated directional control valve associated with said servo cylinder, pilot ports of said pilot-operated directional control valves being connected with said respective steering valve means; a second fixed displacement charge pump driven by said prime mover; pilot-operated first selector valve means connected at its input side with said second charge pump and at its output side with said pilot-operated directional control valves, said first selector valve means having formed therein a throttling position and a communication position; means for normally holding said first selector valve means in the throttling position; manually operated second selector valve means connected at its input side with said second charge pump and at its output side with a pilot port of said pilot-operated first selector valve means; and means for interlocking said manually operated selector valve means with the operation of said manually operated steering valve means; whereby said pilot-operated first selector valve means is changed-over to its communication position when either one of said steering valve means is operated.
Claim 5
Dependent Claim
295 words
A control system for a hydraulically driven vehicle including a pair of variable displacement hydraulic motors each being connected with the respective variable displacement hydraulic pumps in a closed loop and driven thereby, said control system comprising in combination: a first fixed displacement charge pump driven by said prime mover; directional control valve means for speed control and forward and reverse change-over of the vehicle connected at its input side with said first charge pump; a pair of manually operated steering valve means each connected at its input side with the output side of said directional control valve means; a pair of servo control means each operatively connected with said respective variable displacement hydraulic pumps for controlling the displacement volume thereof and comprising a double acting servo cylinder and a pilot-operated directional control valve associated with said servo cylinder, pilot ports of said pilot-operated directional control valves being connected with said respective steering valve means; a second fixed displacement charge pump driven by said prime mover; pilot-operated first selector valve means connected at its input side with said second charge pump and at its output side with said pilot-operated directional control valves, said first selector valve means having formed therein a throttling position and a communication position; means for normally holding said first selector valve means in the throttling position; manually operated second selector valve means connected at its input side with said second charge pump and at its output side with a pilot port of said pilot-operated first selector valve means; and means for interlocking said manually operated selector valve means with the operation of said manually operated steering valve means; whereby said pilot-operated first selector valve means is changed-over to its communication position when either one of said steering valve means is operated.
Claim 6
Dependent Claim
68 words
A control system for a hydraulically driven vehicle as recited in claim 3 wherein said manually operated second selector valve means has a restrictor formed therein and the pilot port of said pilot-operated first selector valve means is connected with a reservoir through said restrictor thereby allowing the return speed of said pilot-operated first selector valve means from the communication position to the throttling position to be reduced.
References Cited (Backward Citations)
US3788773A
Cited
DE2165527A1
Cited
US3788774A
Cited
US3946560A
Cited
US3999387A
Cited
US4188789A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |