US 5,857,330 AGranted

Travelling control circuit for a hydraulically driven type of travelling apparatus

AssigneeKomatsu Ltd.

InventorsNaoki Ishizaki, Toshiro Takano

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Abstract

A travelling control circuit for a hydraulically driven type of travelling apparatus is provided. The circuit has a hydraulic pump, left and right hand side directional control valves provided parallel to each other in a discharge path of the hydraulic pump, a left hand side first and second circuit and a right hand side first and second circuit. Furthermore, the output sides of the left hand side and right hand side directional control valves are connected with a left and right hand side travelling purpose hydraulic motor, respectively. In addition, a pressure compensating valve is provided with each of the first and second circuits to control the opening between an inlet port and an outlet port in response to a difference in pressure between a self load pressure and a maximum load pressure of the load pressures of the left and right hand side travelling purpose hydraulic motors, thereby compensating a pressure in the fluid. When the pressurized fluid is compensated, the pressure compensating valves establish communication between the left hand side and the right hand first circuits and between the left hand side and the right hand side second circuits. When communication between the inlet port an the outlet port is blocked or substantially blocked, the pressure compensating valves block communication between the left hand side and the right hand side first circuits and communication between the left hand side and the right hand side second circuits, respectively.

Claims9

Dependent claims

A control valve system, comprising:

a hydraulic pump having a discharge path;
a first directional control valve operably provided in said discharge path;
a second directional control valve operably provided in said discharge path in parallel with said first directional control valve;
a first circuit fluidically connected to said first directional control valve;
a second circuit fluidically connected to said first directional control valve;
a third circuit fluidically connected to said second directional control valve;
a fourth circuit fluidically connected to said second directional control valve;
a first motor fluidically connected to said first and said second circuits;
a second motor fluidically connected to said third and said fourth circuits;
a first pressure compensating valve operably provided in said first circuit;
a second pressure compensating valve operably provided in said second circuit;
a third pressure compensating valve operably provided in said third circuit;
a fourth pressure compensating valve operably provided in said fourth circuit;
a first path of communication connecting said first pressure compensating valve to said third pressure compensating valve;
a second path of communication connecting said second pressure compensating valve to said fourth pressure compensating valve;
wherein said first and said third pressure compensating valves are adapted to connect said first path of communication with said first and said third circuits when said first and said third pressure compensating valves open communication in said first and said third circuits, and to disconnect said first path of communication from one of said first and third circuits when one of said first and said third pressure compensating valves blocks communication in said first and said third circuits, respectively;
and
wherein said second and said fourth pressure compensating valves are adapted to connect said second path of communication with said second and said fourth circuits when said second and said fourth pressure compensating valves open communication in said second and said fourth circuits, and to disconnect said second path of communication from one of said second and said fourth circuits when one of said second and said fourth pressure compensating valves blocks communication in said second and said fourth circuits, respectively.

15 more elements

A travelling control circuit for a hydraulically driven travelling apparatus, comprising:

a hydraulic pump having a discharge path;
a first directional control valve operably provided in said discharge path and having an output side;
a second directional control valve operably provided in said discharge path in parallel with said first directional control valve and having an output side;
a first circuit fluidically connected to said output side of said first directional control valve;
a second circuit fluidically connected to said output side of said first directional control valve;
a third circuit fluidically connected to said output side of said second directional control valve;
a fourth circuit fluidically connected to said output side of said second directional control valve;
a first motor fluidically connected to said first and said second circuits;
a second motor fluidically connected to said third and said fourth circuits;
a first pressure compensating valve operably provided in said first circuit, having an inlet port fluidically connected to said first circuit, and an outlet port fluidically connected to said first circuit;
a second pressure compensating valve operably provided in said second circuit, having an inlet port fluidically connected to said second circuit, and an outlet port fluidically connected to said second circuit;
a third pressure compensating valve operably provided in said third circuit, having an inlet port fluidically connected to said third circuit, and an outlet port fluidically connected to said third circuit;
a fourth pressure compensating valve operably provided in said fourth circuit, having an inlet port fluidically connected to said first circuit, and an outlet port fluidically connected to said first circuit;
a first path of communication connecting said first pressure compensating valve to said third pressure compensating valve;
a second path of communication connecting said second pressure compensating valve to said fourth pressure compensating valve;
wherein said first and said third pressure compensating valves are adapted to connect said first path of communication with said first and third circuits when said first and said third pressure compensating valves open communication in said first and said third circuits, and to disconnect said first path of communication from one of said first and third circuits when one of said first and said third pressure compensating valves blocks communication in said first and said third circuits, respectively;
and
wherein said second and said fourth pressure compensating valves are adapted to connect said second path of communication with said second and said fourth circuits when said second and said fourth pressure compensating valves open communication in said second and said fourth circuits, and to disconnect said second path of communication from one of said second and said fourth circuits when one of said second and said fourth pressure compensating valves blocks communication in said second and said fourth circuits, respectively.

15 more elements

Dependencies are inferred from the claim text.