Patent GB-840897-A (GB)
Title: Improvements relating to fluid-flow control valves
IPC: F16K29/02
Filed: 1957-06-07
Abstract: 840,897. Valves. CAMERON IRON WORKS Inc. June 7, 1957 [April 9, 1957; May 6, 1957], No. 18191/57. Class 135. In a valve comprising a body having a flow-way therethrough intersected by a cavity, a valve member movable in the cavity by operating means between flow-way opening and closing positions, a seat element having an opening aligned with the flow-way and located between the valve member and a body surface surrounding the flow-way, and means responsive to actuation of the operating means for rotating the seat element about the axis of its opening from one definite seating position to another. In one embodiment, a ported valve gate 33, Fig. 2, operable by a non - rising, screw - threaded stem 37 is movable in a cavity 28 between guide plates 47 carrying removable seat elements 48, thicker than the plates, to open and close a flow-way 27 through the valve body 26. The plates 47 are held against the gate by a U- shaped spring clip 50 and in the cavity 28 between a bonnet 30 and a screw-threaded plug 26a. Links 60, Fig. 5, one for each plate, are pivotally mounted on pins 61 carried by the plates and connected together by a pin 59 which passes cut-away portions 62 in the plates whilst a lower pin 58 connects the plates together. The edges 54 ... 57 are curved concentrically about the flow-way axis to permit slight rocking of the plates about this axis. When the gate is moved downwardly into its closed position its lower tapered portion 63 engages the pin 58 so that the plates 47 are rocked counterclockwise. At its closed or nearly closed position the differential pressure acting on opposite faces of the gate urges the gate against the down-stream seat element and in so doing holds this seat element stationary whilst the associated plate is allowed to rock. Upon movement of the gate from closed to open position the plate will remain in its rocked position until the upper tapered portion 63 of the gate engages the pin 59 whence bearing surfaces 64 on the links 60 frictionally engage the outer peripheries of the seat elements to rock the plates 4 and rotate the seat elements clockwise, since there is no differential pressure acting on the gate in its open position. This slight rotation of the seat element occurs every time the valve is opened. In another embodiment, a rotary spherical plug 102, Fig. 14, is rotatable in a cavity 100 by a valve stem 104 to open and close a throughway 99. The stem 104 is formed with a flange 114 having a pair of recesses providing shoulders 119, 120, Fig. 16, engageable with surfaces 121, 122 on a part 118, carried on a pivot-pin 117 mounted on a seat carrier ring 110. The ring 110 is recessed to receive the part 118 and has a bore in which the seat element 112 fits. Toward the end of the closing movement of the plug 102 the shoulders 119 engage the surfaces 122 to rotate each of the carriers counterclockwise but since a differential pressure exists between the upstream and downstream sides of the plug the downstream seat element is held firmly against rotation. Toward the end of the opening movement of the plug 102 the shoulders 120 engage the surfaces 121 whence a surface 123 on the part 118 is urged into engagement with the peripheral surface of the seat element 112 and since there is now no pressure differential the seat elements will be rotated with their carriers to a new position. In a further embodiment, a lift valve member 128, Fig. 19, is operable by a non-rising, screw-threaded spindle 129 to move it towards and away from a seat element 149. The seat carrier ring 148 in this case carries an inclined arm 155 mounted on a vertically disposed pivot-pin (not shown), and movable into and out of a slot 157, Fig. 22, in the valve member. As the valve member moves into closed position shoulder 159 in the slot 157 engages surface 161 on the arm 155 to rotate the carrier in one direction and as it moves into open position the shoulder 158 and surface 160 are engaged to rotate the carrier in the opposite direction. As before, the arm 155 has a bearing surface 162 engageable with the peripheral surface of the seat element 149. Specification 841,019 is referred to.