| 摘要 |
A control valve has a body with an orifice open to an inlet port and to an outlet port. A valve sleeve is movable along an axis in the body to move a valve needle into and out of the orifice. A first bellows engages the body and valve sleeve to preclude leakage between them. An actuator housing on the body defines a first compartment and a second compartment spaced apart along the axis. There is a packing stem and an actuator stem secured to the valve sleeves and together extending through the first compartment into the second compartment. The stems carry devices to engage electrical circuit control mechanism in the first compartment. The end of the second compartment is closed by a mounting disc, and leakage between the actuator stem and the mounting disc is precluded by a packing. A recessed disc spans an end of the second compartment. There is a flexible diaphragm in the recessed disc partially spanning a chamber therein. Movement is transmitted along the axis between the flexible diaphragm and the actuator stem. A cap overlies the diaphragm and also partially defines the chamber. A pilot valve is in the cap and assists in conducting pressure fluid to and from the compartment. The diaphragm and the pilot valve are interconnected for conjoint action.
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