Hydraulic pressure control circuit for a working machine
AssigneeShin Caterpillar Mitsubishi Ltd.
InventorsHidetake Motomura, Hiroaki Tada
Life of this patent
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Abstract
When a working implement comes close to a cab during operation, for efficiency, the operation should continue insofar as possible yet it is essential the working implement be prevented from striking the cab. To that end, a pilot pump oil line capable of supplying pilot pressurized oil to a solenoid proportional pressure reducing valve in a state where a control member is not manipulated, is provided in a stick contraction-side pilot oil line. When the working implement enters an interference prevention area, defined around the cab, the stick is automatically moved out so that the operation can continue yet the working element avoids the interference prevention area.
Claims14
A hydraulic control circuit for a working machine comprising a hydraulic actuator operated to move a working implement, and a pilot-operated directional control valve for controlling supply of pressurized oil to said hydraulic actuator, said hydraulic control circuit including:
- a pressure control valve for controlling supply of pilot pressurized oil to said directional control valve in accordance with a command from a control unit;
- a pilot valve for delivering the pilot pressurized oil to said pressure control valve in accordance with manipulation of a control member;
- a pilot pump oil line capable of supplying the pilot pressurized oil to said pressure control valve from a pilot oil pressure source without passing said pilot valve;
- and
- a selector valve for supplying the pilot pressurized oil delivered from said pilot valve to said pressure control valve when said control member is manipulated, and supplying the pilot pressurized oil from said pilot pump oil line to said pressure control valve when said control member is not manipulated, said control unit including:
- determining means for determining whether said working implement has entered a preset interference prevention area based on input signals from attitude detecting means for detecting an attitude of said working implement;
- and
- interference prevention control means for outputting a control command to said pressure control valve, causing the pilot pressurized oil to be supplied to said pilot-operated directional control valve in the direction to move said working implement away from the interference prevention area, when said determining means determines that said working implement has entered the preset interference prevention area.
A hydraulic control circuit for a working machine comprising first and second hydraulic actuators for operating a working implement, and first and second pilot-operated directional control valves for respectively controlling supply of pressurized oil to said hydraulic actuators, wherein said hydraulic control circuit includes:
- interference prevention control means for preventing said working implement from entering an interference prevention area set in advance to prevent interference between a body of said working machine and said working implement, and said interference prevention control means includes a mechanism for operating said first hydraulic actuator in the direction away from the interference prevention area, thereby continuing operation of said second hydraulic actuator while said working implement is prevented from entering the interference prevention area when it is determined, at least in a state of said second hydraulic actuator being operated, that said working implement has reached the interference prevention area,
- said mechanism including valve means for switching over the circuit such that pilot pressurized oil for operating said second hydraulic actuator is also supplied to a pilot oil line for operating said first hydraulic actuator in the direction away from the interference prevention area.
Dependencies are inferred from the claim text.