Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – Condition responsive means for modifying working member...
Patent
1996-03-15
1998-08-18
Lopez, F. Daniel
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
Condition responsive means for modifying working member...
91446, F15B 1116
Patent
active
057945101
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a pressurized fluid feed system for supplying a pressurized discharge fluid(s) from a single hydraulic pump or a plurality of hydraulic pumps to a plurality of hydraulic actuators, especially to a turning motor for a power shovel and a cylinder for a boom.
BACKGROUND OF THE INVENTION
A pressurized discharge fluid from a hydraulic pump, when it is supplied simultaneously into a plurality of hydraulic actuators, is forced to flow preferentially into an actuator of a lowest external load among various external loads acting on the respective actuators and hence cannot be supplied into a plurality of hydraulic actuators with varied external loads simultaneously.
In order to resolve this problem, there has hitherto been known, for example, a pressurized fluid feed apparatus as shown in FIG. 1 of the accompanying drawings hereof.
As shown in the Figure, the apparatus is provided in the discharge path 2 of a hydraulic pump 1 with a plurality of pressure compensating valves 3, each of the pressure compensating valves 3 being connected at its outlet side to an actuator 5 via a directional control valve 4. By setting these respective pressure compensating valves 3 at a highest load pressure, the actuators 5 having varying loads can be supplied simultaneously with a pressurized discharge fluid from the hydraulic pump 1.
More specifically, each pressure compensating valve 3 as mentioned above comprises a check valve section 6 and a pressure reduction valve section 7. The check valve section 6 is designed to increase and decrease the area of aperture between an inlet port 8 and an outlet port 9 whereas the pressure reduction valve section 7 is designed to establish and block a communication between a first port 10 and a second port 11. A spool in the pressure reduction valve section 7 is operatively thrusted in the communicating direction under a pressure at a first pressure receiving section 12 and is operatively thrusted in the blocking direction under a pressure at a second pressure receiving section 13. In addition, it is operative to act, by way of a rod 14, to push the check valve section 6 in the direction in which the the area of the aperture is reduced. The first port 10 of the respective pressure reduction valve section 7 is connected to the discharge path 2 of the hydraulic pump 1, the second port 11 has a self communication passage between the pressure reduction valve sections 7 and the first pressure receiving section 12 is connected to a respective load pressure detection circuit 15.
This being the case, where the load pressure of the left hand side actuator 5 is high and the load pressure of the right hand side actuator 5 is low in the construction in FIG. 1, the spool in the pressure reduction valve section 7 of the left hand side pressure compensation valve 3 will be thrusted in the communicating direction under a load pressure at the first pressure receiving section 12 and a pressurized fluid as commensurate with that load pressure will be delivered to the second port 11 and will act on the second pressure receiving section 13 of the pressure reduction valve section 7 of the right hand side pressure compensating valve 3. And, a low pressure load acts on the first pressure receiving section 12. Therefore, the spool in that pressure reduction valve section 7 will be thrusted in a direction tending to block a communication between the first port 10 and the second port 11. Then, since the area of the aperture of the right hand side check valve 6 under the action of the rod 14 is reduced smaller than the area of the aperture of the check valve section 6 of the left hand side pressure compensating valve 3, the pressurized discharge fluid from the hydraulic pump 1 can be delivered to each of the actuators of varying load pressures.
In a pressurized fluid feed apparatus as mentioned above, each pressure compensating valve 3 ought to be set at a highest load pressure. Thus, for example, in a case where a turning motor for a power shovel and a cylinder
REFERENCES:
patent: 4508013 (1985-04-01), Barbagli
patent: 5062350 (1991-11-01), Tanaka et al.
patent: 5134853 (1992-08-01), Hirata et al.
Akashi Mitsumasa
Netsu Yoichi
Takano Toshiro
Kananen Ronald P.
Komatsu Ltd.
Lopez F. Daniel
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