Shutoff valve with needle element therein and valve seating construction

Claim 1

A VALVE, INCLUDING IN COMBINATION, A VALVE BODY HAVING A PORT AND A FLAT VALVE SEAT SURROUNDING THE PORT, A VALVE ASSEMBLY MOVABLE IN OPPOSITE DIRECTIONS RELATIVE TO SAID SEAT AND PORT TO CONTROL FLOW THROUGH THE PORT, SAID ASSEMBLY COMPRISING A STEM EXTENDING COAXIALLY WITH THE PORT AND AXIALLY MOVABLE TOWARDS AND AWAY FROM THE VALVE SEAT AND HAVING AT ITS LOWER END A NEEDLE VALVE ELEMENT MOVABLE INTO SAID PORT AND HAVING A REGION DIMENSIONED TO FIT CLOSELY WITHIN THE PORT, SAID STEM HAVING A LONGITUDINALLY EXTENDING PORTION LYING IMMEDIATELY ADJACENT SAID ELEMENT AND ALSO DIMENSIONED TO FIT CLOSELY WITHIN THE PORT, PISTON MEANS CARRIED BY SAID STEM IN FIXED POSITION SPACED FROM SAID NEEDLE VALVE ELEMENT, MEANS INCLUDING A SUBSTANTIALLY CYLINDRICAL ELEMENT SURROUNDING SAID PISTON MEANS AND AT LEAST PART OF SAID PORTION OF SAID STEM TO DEFINE AN ANNULAR PACKING CHAMBER EXTENDING AROUND SAID STEM AND AT LEAST PART OF SAID STEM PORTION, SAID CYLINDRICAL ELEMENT HAVING LIMITED MOVEMENT AXIALLY WITH RESPECT TO THE VALVE STEM AND PISTON MEANS AND INCLUDING STRUCTURE AT ONE END FORMING A RESTRICTED ANNULAR OPENING FROM SAID PACKING CHAMBER ENCIRCLING SAID STEM OPPOSITE THE VALVE SEAT AND AN EXTERIOR FLAT SEATING SURFACE ENCIRCLING SAID OPENING FOR ENGAGING THE VALVE SEAT, SAID CYLINDRICAL ELEMENT ALSO HAVING A BEVELLED PORTION THEREIN ADJACENT SAID ANNULAR OPENING AND EXTENDING RADIALLY OUTWARDLY AND AWAY FROM SAID ONE END, A PACKING OF RESILIENT, EXTRUDABLE MATERIAL SUBSTANTIALLY FILLING AND CONFINED WITHIN SAID CHAMBER, SAID STEM, PISTON AND PACKING EFFECTING MOVEMENT OF SAID CYLINDRICAL ELEMENT DURING INITIAL CLOSING MOVEMENT OF SAID ASSEMBLY TO ENGAGE SAID EXTERIOR SURFACE WITH SAID VALVE SEAT AROUND SAID PORT, AND SAID STEM AND PISTON MEANS THEREAFTER ACTING THROUGH SAID PACKING ONLY TO FORCE THE EXTERIOR SEATING SURFACE OF SAID CYLINDRICAL ELEMENT AGAINST THE VALVE SEAT AND ALSO EXTRUDING SAID PACKING THROUGH SAID ANNULAR OPENING AND LONGITUDINALLY ALONG THE PERIPHERY OF SAID PORTION OF SAID STEM DURING SUBSEQUENT CLOSING MOVEMENT THEREOF DUE TO CONTINUED AXIAL MOVEMENT OF THE STEM IN CLOSING DIRECTION AFTER ENGAGEMENT OF SAID SURFACE WITH SAID VALVE SEAT, THEREBY TO FORCE THE PACKING AGAINST THE VALVE SEAT TO COMPLETE A SEAL WITH SAID PACKING CONFINED WITHIN SAID CHAMBER BY THE CHAMBER DEFINING MEANS, THE SAID STEM PORTION FITTING CLOSELY WITHIN THE PORT AND THE VALVE SEAT.