Motors: expansible chamber type – With motive fluid valve – Relatively movable serial valves
Patent
1996-09-10
1998-09-29
Nguyen, Hoang
Motors: expansible chamber type
With motive fluid valve
Relatively movable serial valves
91448, F15B 1108
Patent
active
058133097
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a pressure compensation valve unit of a pressure oil supply system for supplying a discharge pressure oil from one hydraulic pump to a plurality of actuators and a pressure oil supply system utilizing the pressure compensation valve unit.
BACKGROUND ART
As a pressure oil supply system for supplying discharge pressure oil from one hydraulic pump to a plurality of actuators, there is known a system shown in, for example, Japanese Patent Laid-open Publication No. HEI 4-244604.
In such system, as shown in FIG. 1, a plurality of pressure compensation valve units 3 are connected in parallel to a discharge passage 2 of one hydraulic pump 1, and a plurality of actuators 5 are connected respectively to outlet sides of the respective pressure compensation valve units through a plurality of directional control valves 4 in a manner such that when the plurality of actuators 5 are simultaneously actuated, the respective pressure compensation valve units 3 are set in accordance with the highest load pressure to thereby to be able to supply the discharge pressure oil from one hydraulic pump 1 to the actuators 5 which are of different loads, respectively.
Each of the pressure compensation valve units 3 is provided with a check valve 6 and a pressure reducing valve 7. The check valve 6 is pushed in a valve opening direction by a inlet pressure introduced into a pressure chamber a and in a valve closing direction by an outlet pressure introduced into pressure chamber b, and the outlet side of the check valve 6 is communicated with a pump port 4a of the directional control valve 4. The pressure reducing valve 7 is pushed in a valve opening direction by a load pressure of a corresponding actuator 5 introduced into a pressure chamber c via a load pressure introducing passage 8 and is pushed in a valve closing direction by a spring force of a spring 9 having a weak spring force and an outlet pressure introduced into a pressure chamber d. The pressure reducing valve 7 is provided with a push rod 10 for pushing the check valve 6 in its closing direction, so that the communication between the inlet side and the outlet side thereof is established and blocked and the check valve 6 is pushed in its closing direction by the pressure difference between a load pressure of an actuator 5 acting on a pressure receiving portion c and a pressure acting on a pressure receiving portion d the communication between the inlet side and the outlet side thereof is established and blocked.
The outlet sides of the respective pressure reducing valves 7 are communicated with load pressure detection passages 11, respectively, which are communicated with a tank 13 through a throttle passage 12.
The hydraulic pump 1 has a variable capacity structure, and an angle of a swash plate 14 of the hydraulic pump 1 is changed by an adjusting cylinder 15 to which pump discharge pressure is supplied by the directional control valve 16 for a pump operation adjustment. The directional control valve 16 for pump operation adjustment is pushed to the discharge side by the spring force of a spring 17 and a load pressure in the load pressure detection passage 11 and is pushed to the communication side by the pump discharge pressure.
As mentioned above, when a plurality of actuators 5 are operated all at once, the pressure reducing valve 7 of the pressure compensation valve unit 3 connected to one actuator 5 having a large load (for example, an actuator 5, lefthand one as viewed in FIG. 1) is pushed rightward to establish communication between the inlet and outlet sides thereof, whereby the large load pressure acts on the pressure receiving portion d of the pressure reducing valve 7 of the pressure compensation valve unit 3 connected to another one actuator 5 having a small load (for example, an actuator 5, righthand one, as viewed in FIG. 1). At this time, since the load pressure acting on the pressure receiving portion c of the pressure reduction valve 7 is small, this pressure reduction valve 7 is pushed leftward to bloc
REFERENCES:
patent: 5067389 (1991-11-01), Germain
patent: 5447093 (1995-09-01), Budzich
patent: 5533334 (1996-07-01), Takeuchi et al.
Ikei Kazunori
Taka Keisuke
Kananen Ronald P.
Komatsu Ltd.
Nguyen Hoang
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