US 4,395,878 AGranted

Control system for hydraulically driven vehicle

AssigneeKabushiki Kaisha Komatsu Seisakusho

InventorsKoichi Morita, Kenzo Hoashi

Life of this patent

Estimating the term…

Loading patent…

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.

Claims4

Dependent claims

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.

7 more elements

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.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/144,165Filed 25 Apr 1980
Priority: JP 54/55950[U]27 Apr 1979
Granted: 2 Aug 1983
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

F16H 61/42
Hydrostatic: involving adjustment of a pump or motor with adjustable output or capacity
B60W 10/04
Conjoint control of vehicle sub-units of different type or different function: including control of propulsion units
B60W 10/103
Infinitely variable gearings: of fluid type
B60W 30/18
Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of…:…