| 摘要 |
<p>PCT No. PCT/GB94/00691 Sec. 371 Date Nov. 21, 1994 Sec. 102(e) Date Nov. 21, 1994 PCT Filed Mar. 31, 1994 PCT Pub. No. WO94/23230 PCT Pub. Date Oct. 13, 1994A solenoid actuator for a fluid flow valve comprises a closure member (64) adapted to engage a fluid flow orifice (16), and includes a magnetic plunger (46) under the control of a solenoid, for moving the closure member (64) into or out of engagement with the orifice (16). To assist the opening of the valve, a diaphragm spring (66) aids the downward force upon plunger (46) at changeover, being deflected during the upward stroke of plunger (46) and held deflected until changeover. The solenoid plunger (46) is stable at either end of its travel to maintain the selected state of the valve, change of state to open or close orifice (16) being by means of an magnetic pulse generated by solenoid coil (43), the plunger (46) being latched at closure by permanent magnets (32,34). The diaphragm spring (66) may form part of an assembly (62) including a membrane switch (70), responsive to the state of the valve, the assembly (62) fitting into the body of the closure member (64). Alternatively a reed switch responsive to magnetic flux may provide valve status indication. The use of a diaphragm spring to assist in valve opening, enables provision of an axially more compact, and electromagnetically more efficient actuator, able with appropriate intrinsic safety protection, to be enclosed within a gas meter housing to control an incoming gas supply under control of electronic switching circuits.</p> |
