Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – Condition responsive means for modifying working member...
Patent
1994-10-07
1996-07-16
Lopez, F. Daniel
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
Condition responsive means for modifying working member...
91518, 91447, 60426, 60452, F15B 1116
Patent
active
055356630
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an operating valve assembly with a pressure compensation valve.
When a pressurized fluid discharged from a single hydraulic pump is distributed to a plurality of actuators, it is typical to provide a plurality of operating valves in a discharge line of the hydraulic pump and to supply a pressurized fluid to respective actuators by switching operating valves. In such a hydraulic circuit, if the pressurized fluid is to be supplied to a plurality o:5 hydraulic actuators simultaneously, the pressurized fluid may be supplied only to the actuator having smaller load and cannot be supplied to the actuator having the greater load. As a solution for such problem, there have been proposed hydraulic circuits, such as that disclosed in Japanese Examined Patent Publication (Kokoku) No. Heisei 2-49405.
FIG. 1 shows one example of the conventional hydraulic circuit. The shown hydraulic circuit includes plurality of operating valves 2 in a discharge line 1a of a hydraulic pump. A pressure compensation valve 5 is provided in each circuit 4 connecting each operating valve to a hydraulic actuator 3. The highest pressure among the pressures in the respective circuits, i.e. among the load pressures, is detected by a load pressure detecting path 7 incorporating check valves 6. The detected highest load pressure acts on each of the pressure compensation valves 5 for setting a set pressure at a pressure level corresponding to the detecting load pressure. In conjunction therewith, an outlet side pressure of each operating valve is controlled to be lower than the set pressure so that when the operating valves 2 are operating simultaneously, the pressurized fluid may be distributed to respective actuators at a distribution ratio proportional to the open areas of the operating valves.
The hydraulic circuit of the type set forth above is complicated since it requires the operating valve 2, the pressure compensation valve 5, and the load pressure detecting path 7 in the circuit 4. Furthermore, such a hydraulic circuit is bulky and thus requires a wide space for installation. In order to solve this problem, it may be considered to provide the operating valve 2, the pressure compensation valve 5 and the load pressure detecting path 7 within a single block. However, if these components are simply aggregated within the single block, the block inherently becomes large and cannot be made compact.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an operating, valve assembly with a built-in pressure compensation valve which renders a hydraulic circuit compact.
In order to accomplish the above-mentioned and other objects, according to the first aspect of the present invention, an operating valve assembly comprises: laterally through the vertically intermediate portion of a valve body extending laterally therethrough, forming a load pressure detecting port at a laterally intermediate portion of the spool, forming pump ports, actuator ports and tank ports at both sides of the load pressure detecting port, and slidably inserting a spool within the spool bore; upper portion of the valve body; and supplying the detected load pressure to the load pressure detecting port is, formed in the spool.
It should be noted that the auxiliary valves may be arranged at left and right sides of the lower portion of the valve body. Also, it is desirable that the pressure compensation valves each comprise a valve establishing and blocking communication between an outlet port and a control passage connecting the actuator port to a hydraulic load and means for biasing the valve in a valve closing direction, and the biasing means for biasing the valve in the valve closing direction includes an actuation chamber generating a biasing force by receiving the load pressure. In this case, it is preferred that the operating valve assembly further comprises means for introducing a holding pressure of the hydraulic load into the actuation chamber at a neutral position of the
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patent: 4617798 (1986-10-01), Krusche
patent: 4787294 (1988-11-01), Bowden
patent: 4986071 (1991-01-01), Voss et al.
patent: 5271227 (1993-12-01), Akiyama et al.
patent: 5273069 (1993-12-01), Akiyama et al.
Akiyama Teruo
Saito Kouji
Shinozaki Shin-ichi
Yamashita Koji
Kabushiki Kaisha Komatsu Seisakusho
Lopez F. Daniel
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