HYDRAULIC DRIVING SYSTEM FOR CONSTRUCTION MACHINE

WIPO Patent Application WO/2023/188642

A1

This hydraulic driving system for a construction machine comprises a pump control device that performs load sensing control of a hydraulic pump such that the discharge pressure of the hydraulic pump is higher than the maximum load pressure of an actuator by a target differential pressure that depends on the rotation speed of the engine, and an unload valve that opens to return the oil discharged by the hydraulic pump to the tank when the discharge pressure of the hydraulic pump becomes higher than the pressure obtained by adding an unload setting pressure to the maximum load pressure. The unload valve has a pressure receiving part of closing-direction actuation that sets the unload setting pressure in corporation with a spring of closing-direction actuation. The hydraulic driving system for a construction machine comprises an unload valve control device that guides a hydraulic signal as the target differential pressure that depends on the rotation speed of the engine to the pressure receiving part of the unload valve when the operation for activating a flow control valve is performed, and guides a tank pressure to the pressure receiving part of the unload valve when the operation for activating the flow control valve is not performed.

TAKEBAYASHI YOSHIFUMI (JP)
NOGUCHI SHUUHEI (JP)

PCT/JP2022/047711

October 05, 2023

December 23, 2022

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HITACHI CONSTRUCTION MACHINERY TIERRA CO LTD (JP)

E02F9/22; F15B11/00

WO2013051551A1

2013-04-11

JP2012241742A	2012-12-10
JP2010071425A	2010-04-02
JP2007046712A	2007-02-22
JP2019002451A	2019-01-10
JP2007285329A	2007-11-01
JP2007321908A	2007-12-13

KAICHI IP (JP)

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