| 摘要 |
A tri-stable, solenoid-operated valve defines an internal chamber communicating with an outlet passageway and an inlet passageway, with a valve seat surrounding the outlet passageway. A first piston reciprocates toward and away from the valve seat and supports a closure adapted to close the valve when the first piston is in a first position, and to be spaced away from the valve when the first piston is in a second position. A second piston is mounted to the first piston and can reciprocate toward and away from the valve seat. The second piston has a portionwhich projects into the outlet causing partial occlusion when the first piston is in its second position and the second piston is in its first position. The portion of the second position causing the outlet to be occluded is substantially withdrawn when both pistons are at their respective second positions.
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