| 摘要 |
An infinitely variable, double-acting positioning linear actuator which responds proportionally to fluid pressure includes a hollow cylindrical housing and an actuating rod axially movable through the housing. Two partitions cooperate with the actuating rod for movement therewith and define within the housing a spring chamber and first and second actuating chambers which are at opposite ends of the spring chamber. A compression spring is mounted within the spring chamber and each actuating chamber has a fluid port to communicate with pressurized fluid. First and second retaining structures within the spring chamber cooperate with respective ends of the spring and each have a respective stop. The spring chamber has a limiting structure which cooperates with the stops to hold the stops spaced apart at a particular spacing when the actuator is centered. The limiting structure also permits limited axial movement of one of the stops relative to the housing and the remaining stop during actuating rod stroke, which stroke is no greater than the particular spacing between the stops. The actuator is relatively compact and simple, uses one spring, and preferably the partitions are rolling diaphragms extending between the actuating rod and the housing.
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