Check valve pull assembly

In a check valve of a type having a housing defining an axially extending cavity divided by a valve orifice into a first portion and a second portion, first and second axially spaced ports communicating with said first and second portions of said cavity, respectively, a primary valve seat surrounding said orifice, a valve member positioned to be urged against said seat by pressure in said first port and to be moved away from said seat by pressure in said second port, and a control member positioned to engage said valve member to mechanically move said valve member away from said seat, the improvement comprising a passageway communicating said first and second portions;

• a closure surface carried by said control member;
• and a spring normally biasing said closure surface to close said passageway;
• said control member being movable to move said closure surface to open said passageway and thereby allow pressure on opposite ends of said valve member to substantially equalize, to facilitate movement of said valve member away from said seat in response to continued movement of said control member;
• said valve further comprising a sleeve slidably received in said second portion of said cavity;
• said sleeve having an end opening that faces said orifice and telescopically receives an end portion of said valve member, and a pressure surface that faces away from said orifice and is in communication with said passageway when said passageway is open;
• and said control member engaging said sleeve to move said sleeve and said valve member as a unit.

In a check valve of a type having a housing defining an axially extending cavity, first and second axially spaced ports communicating with said cavity, a primary valve seat surrounding said cavity between said ports, a valve member positioned to be urged against said seat by pressure in said first port and to be moved away from said seat by pressure in said second port, and a control member positioned to engage said valve member to mechanically move said valve member away from said seat, the improvement comprising an axial passageway through said valve member, said passageway having a predetermined length and including opposite ends, and said control member extending through said passageway;

• a secondary valve plug;
• a pull block;
• said valve plug and said pull block being carried by said control member spaced apart a distance greater than said length, and being adjacent to said opposite ends, respectively;
• and a spring normally biasing said valve plug against said valve member to close said passageway;
• said control member being movable to move said valve plug away from said valve member to open said passageway and thereby allow pressure on opposite ends of said valve member to substantially equalize, to facilitate movement of said valve member away from said seat in response to continued movement of said control member and accompanying engagement of said valve member by said pull block.

A valve, comprising:

• a valve housing including an axially elongated valve cavity divided by a primary valve orifice into a first portion and a second portion;
• a primary valve seat surrounding the primary valve orifice, said primary valve seat being directed toward the first portion of the valve cavity;
• said second portion of the valve cavity having a closed end distal the primary valve orifice;
• a tubular valve member in the housing, said valve member having a primary valve plug at one end, said primary valve plug being located in the first portion of the valve cavity and including a closure surface directed toward the valve seat, and said valve member further including a tubular stem extending axially from the primary valve plug, through the primary valve orifice, into the second portion of the valve cavity, said stem having a tubular end portion distal the primary valve plug;
• said tubular valve member including a longitudinal passageway, said longitudinal passageway having a first end in the first portion of the valve cavity and an opposite second end in the second portion of the valve cavity;
• said first end of the longitudinal passageway defining a secondary valve orifice;
• said primary valve plug including a secondary valve seat surrounding the secondary valve orifice;
• a tubular sleeve within the second portion of the valve cavity, said sleeve including a first end socket opening toward the primary valve orifice, said first end socket including a first base shoulder, said sleeve also including an oppositely directed second end socket opening toward the closed end of the second portion of the valve cavity and including a second base shoulder, and said tubular end portion of the stem of the tubular valve member being telescopically received within the first end socket;
• a mechanical valve operator including an elongated axially movable control member extending axially into the valve cavity;
• a secondary valve plug within the first portion of the valve cavity, connected to the control member and including a closure surface directed toward the secondary valve seat;
• a pull block within the second end socket of the tubular sleeve, said pull block being connected to the elongated control member, and presenting an end directed toward the second base shoulder;
• a first fluid port communicating with the first portion of the valve cavity;
• a second fluid port communicating with the second portion of the valve cavity, axially between the primary valve orifice and the tubular sleeve;
• and
• a spring having a first end pressing against the secondary valve plug, and an opposite end pressing against a fixed support;
• said spring normally biasing the closure surface of the secondary valve plug into seated engagement with the secondary valve seat, and also normally biasing the closure surface of the primary valve plug into seated engagement with the primary valve seat;
• wherein the axial spacing of said end of the pull block from the closure surface of the secondary valve plug is greater than the axial spacing of the second base shoulder from the secondary valve orifice, so that, when the closure surface of the secondary valve plug is seated or the secondary valve seat, said end of the pull block is spaced axially from the second base shoulder, and, when said end of the pull block is against the second base shoulder, the closure surface of the secondary valve plug is spaced axially from the secondary valve seat;
• and
• wherein pressure introduction through the first port into the first portion of the valve cavity, when the control member is extended to axially space said end of the pull block from the second base shoulder, and the second portion of the valve cavity is connected via the second part, to return, will result in the secondary valve plug being seated on the secondary valve seat and the primary valve plug being seated on the primary valve seat, by action of the spring and pressure forces acting on the secondary and primary valve plugs;
• wherein connection of the second port to pressure and the first port to return, while the control member remains extended, will result in pressure acting on the primary valve plug to move it and the secondary valve plug together, against the force of the spring, to move the primary valve plug away from the primary valve seat and open the primary valve orifice, and allow pressure to move from the second portion of the valve cavity, through the primary valve orifice to the first portion of the valve cavity, and to the first port;
• wherein a pull on the control member when the first portion of the valve cavity is connected to pressure and the second portion of the valve cavity is connected to return, will move the secondary valve plug away from the secondary valve seat, and allow pressure movement axially through the passageway in the tubular valve member to the closed end of the second portion of the valve cavity, with pressure in the second portion of the valve cavity, between said closed end and the tubular sleeve, exerting a pressure force on the tubular sleeve and the tubular valve member in opposition to a pressure force in the first portion of the valve cavity acting on the tubular valve member;
• and wherein an additional pull on the control member will move the pull block against the second base shoulder and the first base shoulder against said tubular end portion of the stem, and move the tubular sleeve and the tubular valve member together against the force of the spring, to move the primary valve plug away from the primary valve seat and open the primary valve orifice and allow pressure movement from the first portion of the valve cavity, through the primary valve orifice, and through the second portion of the valve cavity to the second port.