| 摘要 |
A fast-acting reliable electrically operated normally opened or normally closed valve includes a piston which is spring-biased open and which is actuable by pressurized actuating fluid to drive a plug against a valve seat to terminate working fluid flow. Operating current is passed through stainless steel and copper tubes which are connected in series and contain actuating fluid. The stainless steel tube is heated by the current and vaporizes the actuating fluid-generating pressure which forces the cooler fluid from the copper tube into driving relation with the piston. When current is turned off, the stainless steel tube cools decreasing the vapor pressure. The cooler fluid from the copper tube is forced into the stainless tube by the biasing spring and accelerates condensation in the stainless steel tube to lower the pressure and quickly re-open the valve. A unique seal arrangement includes an elastomeric sleeve disposed about a portion of the piston and secured at its ends to the piston and piston housing, respectively. The piston housing wall is arranged to restrain bulging of the seal at any one location during the piston stroke, thereby preventing rupture of the seal.
|
