| 摘要 |
A self-closing valve assembly has a main valve having a seat between a high-pressure input conduit and a low-pressure output conduit, a main valve element movable into and out of engagement with the seat to block and permit flow from the input conduit to the output conduit, and a chamber behind the main valve element pressurizable to press the main valve element against the seat. A small-diameter passage extends from the input conduit to the chamber so that the chamber can be pressurized via the passage from the input conduit to hold the valve element against the seat. A pilot or control valve connected between the chamber and the output conduit can be opened to depressurize the chamber and thereby lift the valve element off the seat. A throttle valve has a throttle body having an outer face exposed to pressurized liquid in the input conduit and an inner face turned toward a mouth of the passage, a formation on the inner face blockingly engageable with the passage mouth, an abutment adjacent the mouth of the passage and operatively engageable with the throttle body so that the pressurized liquid in the input conduit will urge the body toward the mouth of the passage and toward the abutment, a weak spring for holding the throttle body at a spacing from the mouth and from the abutment, and a strong spring effective when the body inner face is against the abutment for urging the body away from the mouth of the passage.
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