Power plants – Pressure fluid source and motor – Having correlated or joint actuation of controller of input...
Patent
1992-06-03
1995-03-21
Lopez, F. Daniel
Power plants
Pressure fluid source and motor
Having correlated or joint actuation of controller of input...
60452, F16D 3102
Patent
active
053985079
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a hydraulic circuit system for supplying fluid under pressure discharged by a hydraulic pump into a plurality of hydraulic actuators.
BACKTROUND ART OF THE INVENTION
To supply fluid under pressure discharged by a hydraulic pump into a plurality of hydraulic actuators, it is only necessary to provide a plurality of operating or controlling valves in a discharge conduit of the hydraulic pump and switch over the operating valves to supply the fluid under pressure into each of the hydraulic actuators. In such an arrangement, however, upon supply of pressurized fluid into the plurality of hydraulic actuators at the same time, there is a tendency of the fluid being supplied only into hydraulic actuators with low loading, but not into those with high loading.
As a hydraulic circuit system arranged to eliminate such a disadvantage, a system as shown in FIG. 4, for example, has heretofore been proposed.
A hydraulic pump 10 shown in FIG. 4 is of a variable displacement type whose displacement or discharge flowrate per one complete revolution is varied by changing the angle of its swash plate 11, the swash plate 11 being arranged to be tilted by a large diameter piston 12 in such a direction as to reduce the displacement of the pump, and also tilted by a small diameter piston 13 in such a direction as to increase the displacement.
The above-mentioned large diameter piston 12 has a pressure receiving chamber 12a which is connected or disconnected by a change-over valve 14 with or from a discharge conduit 10a of the hydraulic pump 10, whilst the small diameter piston 13 has a pressure receiving chamber 13a which is connected with the above-mentioned discharge conduit 10a.
The discharge pipe 10a of the above-mentioned hydraulic pump 10 has a plurality of operating valves 15 connected therewith. Each of conduits 17 connecting the operating valves 15 with the hydraulic actuators 16 is provided with a pressure compensating valve 18. The pressure compensating valve 18 is arranged to be urged to the low pressure set side by the fluid under pressure in a first pressure receiving portion 19, and also urged to the high pressure set side by the fluid under pressure in a second pressure receiving portion 20. The first pressure receiving portion 19 is connected with an outlet of the operating valve 15, and is supplied with the fluid pressure at the outlet thereof, whilst the second pressure receiving portion 20 is connected through a shuttle valve 21 with the conduit 17, and is supplied with the highest load pressure.
The above-mentioned change-over valve 14 is adapted to be urged by the discharge pressure P1 developed by the pump which prevails in the dischage conduit 10a in a such a direction as to permit communication, and also urged by combination of the resilient force of a spring 22 and the aforementioned load pressure in such a direction as to allow drainage. The arrangement is made such that as the pump discharge pressure P1 becomes higher the pump discharge pressure is supplied into the pressure receiving chamber 12a of the large diameter piston 12 so as to tilt the swash plate 11 in such a direction as to reduce the displacement, whilst as the pump dischage pressure P1 becomes lower the pressure receiving chamber 12a of the large diameter pump 12 is connected to a fluid tank, thereby tilting the swash plate 11 in such a direction as to increase the displacement of the hydraulic pump.
Each of the operating valves 15 is arranged to be actuated in such a direction as to increase the area of opening thereof in proportion to the pressure of the pilot fluid under pressure from a pilot control valve 23, the pressure of the pilot fluid under pressure being proportional to the operating stroke of an operating lever 24 associated therewith.
In such a hydraulic circuit system, since fluid flow-rate distribution in proportion to the area of opening of the operating valve 15 can be conducted by dint of the function of the pressure compensating valve 18 and irrespective of
REFERENCES:
patent: 4425759 (1984-01-01), Krusche
patent: 4738279 (1988-04-01), Kropp
patent: 4967554 (1990-11-01), Kauss
Akiyama Teruo
Ishizaki Naoki
Shinozaki Shin-ichi
Shirai Kiyoshi
Yamashita Koji
Kabushiki Kaisha Komatsu Seisakusho
Lopez F. Daniel
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