| 摘要 |
<p>A solenoid operated shutoff valve for compressed air has a tubular ferromagnetic core which is surrounded by an excitable coil and confines a reciprocable ferromagnetic plunger movable into and from sealing engagement with a fixedly mounted valve seat. The seat is installed in one of two coaxial tubular sections of the core and the other section has an axial opening for admission of compressed air to one end face of the plunger so that the other end face of the plunger normally bears against and seals the fluid evacuating opening in the seat. The periphery of the plunger is formed with straight and/or helical grooves defining discrete paths for the flow of compressed gas from the other section of the core into the opening of the seat when the coil is energized to propel the plunger away from the seat. The plunger may be formed with an axial bore which establishes a further path for the flow of compressed air into the opening of the seat. The opening of the seat may consist of an annulus of discrete ports or of a circumferentially complete channel in that end face of the seat which is adjacent to the respective end face of the plunger. The surfaces of the plunger are coated with nickel to reduce friction between such surfaces and the internal surface of the respective section of the core. If at least one of the peripheral grooves of the plunger is a helix, the plunger rotates in response to opening of the valve to thus prevent the accumulation of contaminants in the grooves and/or along the internal surface of the respective core section.</p> |
