| 摘要 |
A chamber (24) is filled with a fluid whose pressure is to be regulated to a predetermined value. A valve (30) is disposed between the chamber (24) and a high pressure source of the fluid. A rolling diaphragm (18) has a face (18c) exposed to the fluid in the chamber (24), and actuates the valve (30) to connect the chamber (24) to the source when the chamber pressure drops below the predetermined value and to disconnect the chamber (24) from the source when the chamber pressure rises to substantially the predetermined value. A spring (26) urges the diaphragm (18) against the chamber pressure with a force corresponding to the predetermined pressure value. A piston (14) is connected between the spring (26) and the diaphragm (18) and is formed with a ramp portion (14b) over which a rolling portion (18b) of the diaphragm (18) extends and varies the effective diameter of the diaphragm (18) as a predetermined function of the longitudinal position of the diaphragm such that the force exerted on the diaphragm (18) by the chamber pressure is maintained substantially equal to the force exerted on the diaphragm (18) by the spring (26). This compensates for variation of the spring force as the fluid flow rate through the valve (30) and thereby the position of the diaphragm (18) change and maintains the regulated pressure constant. A bistable element (42) may be provided to urge the diaphragm (18) toward first and second longitudinal positions in which the valve (30) is open and closed respectively.
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