Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Patent
1997-01-03
1998-04-14
Michalsky, Gerald A.
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
60452, 91446, 137596, F15B 1105
Patent
active
057381348
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a pressure compensation valve to be employed in a hydraulic circuit for distributing in flow rate for supplying a discharged pressurized fluid of one or more hydraulic pumps in a constructional machine to a plurality of actuators.
BACKGROUND ART
When a discharged pressurized fluid of one hydraulic pump is supplied to a plurality of actuators, the pressurized fluid tends to be supplied only to the actuator having lower load pressure. As a solution for this, a hydraulic circuit shown in Japanese Unexamined Patent Publication (Kokai) No. Sho 60-11706, for example, has been known. This is a hydraulic circuit, in which a pressure compensation valves are provided at respective inlet sides of direction control valves connected to respective actuators, respective pressure compensation valves are set at the highest load pressure among load pressures of all of the actuators for distributing in flow rate for supplying the discharged pressurized fluid of the hydraulic pump to a plurality of actuators having different load pressures.
As such pressure compensation valve for a hydraulic circuit, there is one disclosed in Japanese Unexamined Patent Publication (Kokai) No. Hei 4-244605 has been known, for example.
As shown in FIG. 1, this is constructed by providing a check valve bore 1a having an inlet port 2 and an outlet port 3 in a valve body, and slidably disposing a valve 4 within the check valve bore 1a for establishing and blocking communication between the inlet port 2 and the outlet port 3, for forming a check valve portion. Also, a pressure reduction valve bore 1b with a first port 6, a second port 8 and a third port 9 is provided in the valve body. A spool 11 is slidably disposed within the pressure reduction valve bore 1b for defining a first pressure chamber 7 communicating with the first port 6 and a second pressure chamber communicating with the third port 9 at both end sides so that the spool 11 is shifted toward the right by the pressure within the first pressure chamber 7 to establish communication between the second port 8 and the third port 9 and shifted toward the left by the pressure within the second pressure chamber 10 for blocking communication between the second port 8 and the third port 9. It should be noted that, the spool 11 is biased in a direction for blocking communication between the second port 8 and the third port 8 by a spring 13 to contact with the valve 4. Then, with these components, a pressure compensation valve is constructed.
With such pressure compensation valve, when the pressure in the first pressure chamber 7 is higher than the pressure in the second pressure chamber 10, the spool 11 is shifted toward the right away from the valve 4. The valve 4 is then placed at a position where the pressure in the inlet port 2 and the pressure in the outlet port 3 becomes equal to each other. On the other hand, as a result, the pressure in the first pressure chamber 7 and the pressure in the second pressure chamber 10 becomes equal to each other. On the other hand, when the pressure in the first pressure chamber 7 is lower than the pressure in the second pressure chamber 10, the spool 11 is shifted toward the left. Thus, the valve 4 is pushed in a direction for blocking communication by the spool 11 so that the pressure of the outlet port 3 becomes higher than the pressure in the inlet port 2 to the extent corresponding to a pressure difference between the second pressure chamber 10 and the first pressure chamber 7.
With such construction, by connecting the outlet port 3 to a pump port 15 of a direction control valve 14, connecting the first port 6 to an outlet port 16 of the direction control valve 14 to introduce an own load pressure into the first pressure chamber 7, connecting the third port 9 to a load pressure detecting line 17 for introducing a control pressure P.sub.LS into the second pressure chamber 10, and making a discharge passage 19 of the hydraulic pump 18 communicate with the inlet port 2 and the second port 8, a pump disch
Akashi Mitsumasa
Ishizaki Naoki
Kananen Ronald P.
Komatsu Ltd.
Michalsky Gerald A.
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