| 摘要 |
The present invention relates to a diaphragm actuator for control valves, wherein the gear rack is arranged so that the points of contact of the gear rack/gear wheel system are situated on the straight line connecting the centers of the movable walls of the pressure spaces effecting the movement. Thereby, no torsion forces act on the diaphragm backing plates or on the diaphragms, but the forces effecting the movement of the reciprocating elements are substantially parallel with the path of motion and symmetrical. Additionally, the clearance between the gear rack and the gear wheel is substantially eliminated by means of a support roll with bearings. According to the invention, a lightly movable actuator is provided, in which the delays caused by clearances or wall friction of the cylinder-piston arrangement are substantially eliminated. The actuator can be implemented either as double-acting or single-acting.
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