Motors: expansible chamber type – With correlated control of motive fluid and locking means
Patent
1997-01-21
1998-08-18
Denion, Thomas E.
Motors: expansible chamber type
With correlated control of motive fluid and locking means
91448, F15B 1526
Patent
active
057945055
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention concerns from a positioning drive which is used, in particular, on machine tools and which has the features set forth in the preamble of the independent claim.
Such a positioning drive is used, in particular, in order to bring a machine part for which several different positions are preferably possible, into a given position. The machine part can, for instance, be a multi-spindle turret of a boring machine or a tool holder of a machine having several machining stations.
A positioning drive having the features introductory-mentioned is known from the Japanese utility model application published under 62/195435. In that positioning drive, the housing part of the control valve is fastened to the housing part of the hydraulic motor in such a manner that the axis of the valve piston extends perpendicular and tangential to the axis of the motor shaft. The control element is a double-arm lever which is so mounted in the motor housing that it is swingable around an axis which extends parallel to the motor shaft. At the end of the one lever arm, the control element can act on the cam on the cam disk which is fastened, fixed for rotation, on the motor shaft, the lever arm extending approximately perpendicular to a radius vector between the axis of the motor shaft and the place of contact between cam disk and control element. At the end of the other lever arm, the control element grips in fork-shaped manner around a setting element which is fastened to the valve piston. The setting element is developed as a bushing which has, on its outer side, two driver pins which are located diametrically opposite each other and which are gripped around by the control element, the bushing being screwed by an internal thread on a section of the valve piston which is provided with an external thread. The relative position between valve piston and setting element is secured by means of a lock nut.
Another positioning drive is known from Federal Republic of Germany AS 23 49 099. In that positioning drive, the control element is a control bolt which is developed in one piece with the valve. Control bolt and valve piston are movable radially with respect to the cam disk. Finally, in the senior German Patent Application P 43 12 581.6 a positioning drive is described in which a control piston and a valve piston are arranged, also aligned with each other, radially to the cam disk. Control piston and valve piston are to be sure two separate parts.
In the positioning drives indicated, the valve piston can be displaced hydraulically in both directions of movement. By movement in one direction, the control element is lifted off from the cam. In this position of the control element and of the valve piston the motor turns with the maximum speed provided. Movement of the valve piston in the other direction is possible only until the control element comes against the cam and is then determined by the shape of the cam as long as the valve piston is subjected to a force acting in the corresponding direction. If the control element lies against the cam in a region in which the latter is at a constant distance from the axis of the motor shaft then the valve piston remains at rest. In a region in which the distance of the cam from the axis of the motor shaft is reduced, the valve piston moves in the direction of the force acting on it. In positions of the valve piston in which the latter rests via the control element against the cam, a throttle is connected on the discharge side in the hydraulic circuit, the throttling action of which is dependent within a limited region on the position of the valve piston. The motor now moves at creep feed in order to reach the selected position. When the selected position is reached, the control element falls into an indentation in the cam which is associated one or more positions of the machine part, and the valve piston enters into a position in which the hydraulic motor is no longer supplied with pressurized fluid.
In the positioning drive known from Fed
REFERENCES:
Patent Abstracts of Japan, vol. 10 No. 304 (M-526) Oct. 16, 1986 & JP,A,61 117039 (Toshiba) Jun. 4, 1986, JP,U,62 195 435 (None) Dec. 12, 1987.
Fischer Gunter
Knoll Rainer
Denion Thomas E.
Farber Martin A.
Karimi Bijan N.
Mannesmann Rexroth AG
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