Fluid handling – Systems – Supply and exhaust
Patent
1996-12-24
1998-07-14
Michalsky, Gerald A.
Fluid handling
Systems
Supply and exhaust
91446, 13759613, F15B 1105
Patent
active
057789290
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a directional control valve assembly provided with a pressure compensation valve that can be used for feeding a pressurized discharge fluid from one or more hydraulic pumps to a plurality of actuators.
BACKGROUND ART
In a hydraulic circuit that is designed to feed a pressurized discharge fluid from one or more hydraulic pumps to a plurality of actuators using a plurality of directional control valves, it has been known that when a plurality of actuators are simultaneously fed with a pressurized discharge fluid, only an actuator of a low load pressure can be supplied with the pressurized discharge fluid and an actuator of a high load pressure cannot be supplied with any pressurized discharge fluid.
In an attempt to overcome this problem, there has been known a hydraulic circuit in which each directional control valve is provided with a pressure compensation valve and each of all the pressure compensation valves is set according to the highest load pressure to enable the actuators of different load pressures to be simultaneously supplied with a pressurized discharge fluid.
A directional control valve assembly that combines directional control valves with pressure compensation valves in this manner is disclosed in Japanese Unexamined Patent Publication No. Hei 05-332306.
Specifically, as shown in FIG. 1 of the accompanying hereof, the prior art directional control assembly disclosed in the above mentioned Patent Publication has a valve block 30 which is formed therein with a spool bore 31, a check valve bore 37 and a pressure reducing valve bore 38. The above mentioned valve block 30 is also formed therein with a pump port 44 that is open to the spool bore 31, with a first and a second load pressure detecting port 45 and 46, with a first and a second actuator port 34 and 35 and with a first and a second tank port 47 and 48. And, the spool bore 31 has a main spool 49 slidably inserted therein that is designed to establish and block communication between one of these ports and another, thus constituting a directional control valve 22.
The above mentioned valve block 30 is further formed therein with a first port 39 that is open to the check valve bore 37 and with a fluid path 56 for communicating the check valve bore 37 with the said pump port 44. And, the check valve bore 37 has a spool 60 slidably inserted therein that is designed to establish and block communication between the first port 39 and the fluid path 56 and that is stopped at its blocking position, thus constituting a check valve section 23.
The valve block 30 is further formed therein with a second and a third port 42 and 43 that are open to the pressure reducing valve bore 38. The pressure reducing valve bore 38 has a spool 64 slidably inserted therein that is provided with a rod 71 to form a first pressure chamber 65 and a second pressure chamber 66 so as to communicate the first pressure chamber 65 with the second load pressure detecting port 46 and to communicate the second pressure chamber 66 with the third port 43 via a small bore 64a that is provided in the spool 64. And, the above mentioned spool 64 is adapted to be energized by a spring 69 to displace in a given direction and to cause the rod 71 to penetrate through a bore 72 and to be brought into an abutting engagement with the spool 60 of the above mentioned check valve section 23 and to cause the spool 60 to be thrustedly held to its blocking position, thereby providing a pressure reducing valve section 24 and providing a pressure compensation valve 25 with the pressure reducing valve section 24 and the check valve section 23.
An interstice formed between the thrusting rod 71 and the bore 72 mentioned above, is designed to be greater than an interstice formed between the spool 31 and the main spool 49 and an interstice formed between the pressure reducing valve bore 38 and the spool 64 and is designed to communicate with a reservoir 86.
And, the directional control assembly with a pressure compensation valve in the prior art is thus
REFERENCES:
patent: 5161575 (1992-11-01), Morikawa et al.
patent: 5651390 (1997-07-01), Ishihama et al.
Akashi Mitsumasa
Ishizaki Naoki
Komatsu Ltd.
Michalsky Gerald A.
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