Motors: expansible chamber type – Multiple expansion – Dual – rigidly connected high and low pressure faces
Patent
1995-04-26
1996-09-24
Nguyen, Hoang
Motors: expansible chamber type
Multiple expansion
Dual, rigidly connected high and low pressure faces
91519, 91535, F01B 100, F15B 1100
Patent
active
055580009
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a high speed and high load cylinder device applicable for driving a power source for a press machine, a machine tool and so forth.
BACKGROUND OF THE INVENTION
In the prior art, there is a known high speed and high load cylinder device applicable for a press machine, such as a turret punch press and so forth, a machine tool and so forth, which is illustrated in FIG. 1, for example.
The above-mentioned cylinder device is constructed by connecting a piston of a high speed cylinder a, to be operated at high speed, and a piston of a pressurizing cylinder b bearing a high load, via a piston rod, and by communicating upper and lower chambers of the pressurizing cylinder b via an externally provided piping d and a valve c provided in the piping. Upon high speed operation, the upper and lower chambers of the pressurizing cylinder b communicate by opening the valve c so that a pressure difference is not caused even when a hydraulic pressure is supplied from a hydraulic circuit f to enable high speed operation of the high speed cylinder. Upon generating a large pressure force, the valve c is closed so that a pressure difference may be generated between the upper and lower chambers of the pressurizing cylinder b so as to cope with high load by the pressurizing cylinder b. It should be noted that, in FIG. 1, g denotes a hydraulic pump, h denotes a switching valve and i denotes a tank.
However, since the above-mentioned conventional cylinder device is provided externally of the valve c and the piping d, the stroke of the pressurizing cylinder b becomes long so as to expand the length of piping d in association therewith. This causes a problem of creating a high fluid path resistance during high speed operation when a large amount of a working fluid at one time is to be fed.
Also, for permitting flow of a large amount of the working fluid, a large diameter piping and large size valve c become necessary to make the device per se costly. Furthermore, since the construction becomes complicated, it may cause leakage.
The present invention is worked out for improving such defects in the prior art. It is an object of the present invention to provide a high speed and high load cylinder device which enables operation corresponding to high speed operation and high load operation without requiring an external piping.
DISCLOSURE OF THE INVENTION
In order to accomplish the above-mentioned and other objects, a high speed and high load cylinder device constructed by connecting a piston of a high speed cylinder having a smaller pressure receiving area and a piston of a pressurizing cylinder having a large pressurizing area, and providing a hydraulic circuit for supplying a hydraulic pressure to the high speed cylinder and the pressurizing cylinder, comprises:
a sequence valve being provided at an intermediate position in a passage providing in the piston of the pressurizing cylinder for communicating an upper chamber and a lower chamber of the pressurizing cylinder for opening and closing the passage depending upon a pilot pressure, and a pilot pressure being provided for closing the sequence valve by supplying the pilot pressure to the sequence valve;
a high speed/pressurizing switching valve being provided at an intermediate position in a piping supplying the hydraulic pressure to the upper chamber of the pressurizing cylinder in the hydraulic circuit;
the high speed/pressurizing switching valve being closed when high speed operation is required, by not submitting the pilot pressure to the sequence valve; and
the high speed/pressurizing switching valve being open when high pressurizing force is required by supplying the pilot pressure to the sequence valve.
With the construction, it becomes possible to perform high speed operation by the high speed cylinder and operation coping with high load by the pressurizing fluid without providing the external piping and valve.
Preferably, the pistons of both cylinders are connected via a piston rod and a pilot pressure supply passag
REFERENCES:
patent: 2661726 (1953-12-01), Alfieri
patent: 4286929 (1981-09-01), Heath et al.
patent: 4638718 (1987-01-01), Nakamura
patent: 5031509 (1991-07-01), Cowan
patent: 5191825 (1993-03-01), Beneteau et al.
Kabushiki Kaisha Komatsu Seisakusho
Nguyen Hoang
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