HYDRAULIC DEVICE FOR A WORKING MACHINE

WIPO Patent Application WO/1995/004227

A1

A hydraulic device for operating an actuator for a working machine such as a hydraulic shovel wherein a proportional solenoid flow rate control valve (6) is provided on a pipeline between a direction selector valve (3) for selecting a direction in which an actuator operates and a hydraulic pump (2), and a discharging pressure controlling means (25) for controlling the discharging pressure of the hydraulic pump (2) is also provided for maintaining constant the pressure difference across the control valve (6). The flow rate characteristics of a pressure oil to the actuator (1) relative to the control input of an operating lever (5) are set by means of a flow rate setting means (24) in accordance with the loading pressure of the actuator (1) and the revolution speed of an engine (10) for driving the hydraulic pump (2), and the valve travel of the control valve (6) is controlled by means of a solenoid valve controlling means (23) in accordance with the control input of the operating lever (5), whereby it is possible to properly obtain the flow rate characteristics of a pressure oil to the actuator in accordance with a choice of an operator or the type of work to be done, and it is also possible for the operator to easily identify the loaded condition of the actuator through the operation of the operating lever.

KOBAYASHI TAKAHIRO (JP)

PCT/JP1994/001213

February 09, 1995

July 22, 1994

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KOBE STEEL LTD (JP)
KOBAYASHI TAKAHIRO (JP)

E02F9/22; F15B11/04; F15B11/05; E02F9/20; (IPC1-7): F15B11/042; F15B11/08; E02F9/22

JPS63186004A	1988-08-01
JPS6343004A	1988-02-24
JPS5979604U	1984-05-29
JPH04100198U	1992-08-28
JPH01312202A	1989-12-18
JPS61191504U	1986-11-28
JPS60175804A	1985-09-10

See also references of EP 0681106A4

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