| 摘要 |
A device and a system for controlling a fluid pressure are provided. The device comprises a spooltype pilot valve including a housing, a spring-biased displaceable elongated member having an innermost and an outermost sealing means defining at least one fluid-tight annular chamber between an outer surface of the member and an inner surface of the housing and having shoulder means dividing the housing into two further, substantially cylindrical chambers. The pilot valve further includes a first opening communicating with one of said cylindrical chambers at one side of said shoulder means for effecting the displacement of said member, a second opening communicating with said annular chamber, a third opening situated in very close proximity to, and on one side of, the outermost sealing means, and two venting openings. The arrangement being such that when the fluid pressure at the first opening exceeds a predetermined value, the displaceable member is moved to create a flow path between the third opening and one of the other openings of the housing, via the annular chamber to thereby cause the pressure at the first opening to recede to its predetermined value, to allow the spring bias to return the member to its original position.
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