Fluid handling – Systems – Supply and exhaust
Patent
1992-03-16
1993-12-28
Michalsky, Gerald A.
Fluid handling
Systems
Supply and exhaust
60452, 91447, 13759613, F15B 1302
Patent
active
052730697
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an operation valve with a pressure compensation valve which is incorporated in an hydraulic circuit for supplying a hydraulic oil from an hydraulic source to a plurality of hydraulic actuators.
BACKGROUND OF THE ART
To supply a hydraulic oil of a single hydraulic source, i.e. an hydraulic pump to a plurality of hydraulic actuators, it is sufficient to provide a plurality of operation valves in a discharge passage from the hydraulic pump and change the operation valves to supply the hydraulic oil to each of the hydraulic actuators. According to the arrangement, however, it becomes to present a tendency that the hydraulic oil is supplied to only an actuator having a small load and not supplied to an hydraulic actuator of heavy load when the hydraulic oil is supplied to a plurality of the hydraulic actuators at a time and where the hydraulic actuators are not under such circumstances that they are actuated with substantially the same load.
For instance, Japanese Patent Laid Open Publication No. 59-197603 of Showa 59 (the year 1984) proposed an hydraulic circuit as one for solving the above mentioned problem.
The hydraulic circuit of the hydraulic control means in the prior art, which the present invention is subjected to, will be shown in FIG. 3, where it is shown diagrammatically.
In the prior art, an operation valve 2 is provided with a plurality of flow passages respectively which are divided from a discharge passage 1a of an hydraulic pump 1 and a pressure compensation valve 5 are provided respectively with hydraulic oil passages 4 for connecting each of the operation valves 2 and each of hydraulic actuators 3. The pressure of each of the hydraulic oil passages 4, i.e. the most high pressure of that among each of the hydraulic actuators 3 under load, is detected by means of a shuttle valve 6 and each of the detected load pressures acts on each of the compensation valves 5 so that the compensation valves 5 are set in a pressure corresponding to the load pressure. As the result, the pressures at the outlets of the operation valves 2 becomes equal to each other and when each of the operation valves 2 are operated simultaneously, a hydraulic oil may be supplied to each of the hydraulic actuators 3 at a divided flow ratio which is in proportion to an opening area of each of the operation valves 2.
According to the above mentioned hydraulic circuit, with function of the pressure compensation valves 5, it is possible to carry out a division of the flow amount in proportion to the opening areas of the operation valves 2 regardless of a heavy or light load acting on each of the hydraulic actuators 3. Therefore, the hydraulic oil from the single hydraulic pump 1, may be supplied to each of the hydraulic actuators 3 in proportion to an amount of operation of each of the operation valves 2.
However, according to such a prior art, where the operation valves 2 and the compensation valves 5 are constructed separately, piping therefore becomes complex and therefore the operation valves 2 and the compensation valves 5 are assembled. However, the compensation valve 5 is incorporated in the operation valve 2 provided in its valve body and oil openings for detecting a load pressure have to be formed and therefore it cannot evade that its construction becomes complex. Of course, it requires a precision in processing the valve.
DISCLOSURE OF THE INVENTION
The present invention has an object to solve the abovementioned problems and to provide an operation valve with a pressure compensation valve without making the interior of the valve body thereof complex.
In an operation valve with a pressure compensation valve in which a changeable spool and the pressure compensation valve are incorporated therein, the present invention is characterized by that an end of an oil hole formed along an axis of the spool is opened on the side of a load pressure detecting port and another end thereof provides a check valve and further a thin opening is formed on another end of the check valve
REFERENCES:
patent: 3707988 (1973-01-01), Hodgson
patent: 3878864 (1975-04-01), Schurger
patent: 5000001 (1991-03-01), Christensen et al.
patent: 5188147 (1993-02-01), Shirai et al.
Akiyama Teruo
Ishizaki Naoki
Shinozaki Shin-ichi
Shirai Kiyoshi
Yamashita Koji
Komatsu Ltd.
Michalsky Gerald A.
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