Patent ID: 6029945
Filing Date: 2000-02-29
Classification: F16K

Abstract:
A self-closing valve assembly comprising:a main valve havinga 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, anda chamber behind the main valve element pressurizable to press the main valve element against the seat;a small-diameter passage extending from the input conduit to the chamber, whereby the chamber can be pressurized via the passage from the input conduit to hold the valve element against the seat;a control valve connected between the chamber and the output conduit and openable for depressurizing the chamber and thereby lifting the valve element off the seat; anda throttle valve havinga 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, whereby the pressurized liquid in the input conduit will urge the body toward the mouth of the passage and toward the abutment,weak spring means for holding the throttle body at a spacing from the mouth and from the abutment, andstrong spring means effective when the body inner face is against the abutment for urging the body away from the mouth of the passage.