Fluid-driven rotational device

Technical Pield

The present invention relates to a fluid-driven rotatio¬ nal device having an outgoing turning shaft, mounted in a hous¬ ing, a plate displaceable in the housing, a motion-translating mechanism between plate and turning shaft and a pressure chamber, at least on one side of the plate, connected to a pressure fluid source. Background Art

Λ means of the kind described is known, e.g. from DE-OS 1 939 158. The motion-translating mechanism in this case comprises a lead screw rigidly adapted on the turning shaft and in mesh with a nut fixed to the plate. The pressure chamber is defined and sealed by a metal bellows. This rotational device is relatively complicated and is expensive to manufacture. In particular, the screw mechanism requires great machining accuracy, which increases production costs. The metal bellows is another detail which is impractical and makes manufacture more expensive. Disclosure of Invention

The object of the invention is simply and cheaply to provide turning motion for pneumatic or hydraulic forces without great demands on machining accuracy, and to avoid the sealing problems occurring in enclosing air or other fluid in metal cylinders having sealed components.

This object is fulfilled by the motion translating mecha¬ nism of the rotational device according to the invention comprising a pin rigidly attached to the plate and a slot, axially twisted in relation to the shaft, accommodating the pin and extending through the torque shaft.

In a particularly suitable embodiment of the rotational means in accordance with the invention, the pressure chamber is defined by a bellows.

In another suitable embodiment of the inventive rotational device, a pressure chamber is arranged solely on

one side o the plate, while a compression spring is arranged on the other side _*

Brief Description of Drawing

One embodiment of the torque means in accordance with the invention is illustrated in a longitudinal section on the drawing. Best Mode of Carrying out the Invention

In the illustrated embodiment, the rotational means includes a housing comprising two halves 1 and 2. There is a horizontal plate 3 in the housing, this plate being displace- able upwards and downwards _* A turning shaft 6 extends through the plate and is jour alled in the halves 1 and 2. In the shaft there is a through slot 5» which is axially twisted in relation the shaft, a pin 4 being accommodated in the slot 5 and rigidly attached to the plate 3»

The plate 3 is moved upwards and downwards with the aid of two bellows 7 and 8, which can be connected via nipples 13 to a pressurised fluid source, e.g. a compressed air source. The housing halves 1 and 2 are kept together with the aid of through-going, hollow tension members 9 and 10. The material in the members is not ferromagnetic. The tension members further function as holders and guards for different types of indication means 11. For example one of the hollow members can carry a setable position limit indicator for controlling the motion of the rotational device.

Por obtaining an automatic return motion on pressure failure in the fluid system one of the bellows 7, 8 can be exchanged for any suitable kind of compression spring arranged round the turning shaft. To simplify manufacture, instead of being moulded conventionally between a core and mould, the bellows can be made by immersing a block of foamed polymer in a solution of the elastomer of which the bellows is to consist, or by spray¬ ing the block with the elastomer in question. The block is made to conform v/ith the interior of one half of the housing, and is sufficiently soft and porous for it to remain in the

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bellows without disadvantageously affecting the ability of the latter to be compressed and to expand.