EXPANDING GATE VALVE

Abstract: An expanding valve assembly (40) which includes a closure member (18A) supporting at least one segment (30A) supported on one side thereof for movement toward a valve seating surface (10) upon movement of the closure member (18A) in selective response to valve stem (14A) movement. Each segment (30A) carries two spaced-apart, parallel wedging-camming surfaces (44A, 44B) configured to cooperate with complementary spaced-apart, parallel wedging-camming surfaces (42A, 42B) on the closure member (18A) to effect expansion of the segment (30A) during closure of the valve (40). In one embodiment (200) a lift-and-turn mechanism (410) provides selective rotational and axial movement of a closure member (230) during different intervals of movement thereof.

Description: EXPANDING GATE VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to valves having an expanding valve assembly, and more particularly but not by way of limitation, to an expanding valve which includes a valve closure member carrying one or more movable segments which move relative to the valve closure member to effect sealed closure of the valve. 2. Brief Description of the Prior Art Valves with expanding gates have been taught in the prior art, wherein such valves comprise a gate having a female V-surface formed in the upstream side of the gate, a floating segment mounted on the gate, with a complementary male V-surface disposed thereon to engage and coact with the female V-surface on the gate. This gate assembly is usually positioned adjacent seating surfaces within the valve body to move transverse to the conduit axis (direction of fluid flow through the valve) . Sealing during opening and closure is effected by the segment being wedged outwardly from the gate perpendicularly to the stem axis to effect sealing engagement with the seat faces. Examples of such valves are taught by U.S. 4,189,127 (Constantino) U.S. 4,530,488 (Kemp); U.S. 4,334,666 (Alvarez et al.); U.S. 4,341,369 (Meyer); U.S. 4,279,404 (Levin); U.S. 4,188,014 (Alvarez); U.S. 3,823,911 (Natho et al.); U.S. 4,188,016 (Whaley); U.S. 4,179,099 (Pierce, Jr.); U.S. 4,531,710 (Tort 0.); U.S. 1,995,727 (Wetherbee); U.S. 556,006 (Fletcher); U.S. 1,521,531 (Trowe); U.S. 880,674 (Ladd); U.S. 4,405,113 (Erwin); Danish Patent 50,251 (Lindberg); and United Kingdom Patent 1,022,571. In expanding valves of the type described, movement of the gate transverse to the conduit axis causes the floating segment to contact a stop structure which arrests further movement of the segment as the gate continues to move. The seg ent is thereby wedged outwardly so that it sealingly contacts the valve seat. This movement of the segment sub¬ stantially perpendicularly to the stem axis is effected by the wedging action of the cooperating V-surfaces of the gat and segment. The wedging action causing expanding movement of the segment occurs in the fully closed or the fully opened posi tion of the valve, and, as indicated, results from predetermined, selectively located fixed segment stops interposed in the path of the segment as it moves with the gate. These segment stops arrest further movement of the segment in a direction parallel to the stem axis. When the gate is moved between the open and the closed positions, th segment is caused to collapse upon, or nest with, the gate as a result to the complementary interfitting v-surfaces. For smooth and easy operation, and to avoid damage to the valve, it is important that the wedging action of the gate segment occur in only the open and/or closed positions and that the segment remain in the collapsed condition when the gate valve is moving between the open and closed posi¬ tions within the valve body. This prevents unnecessary dragging or binding of the gate assembly against the valve seats at a time when high integrity sealing is not required Pre-expansion of the segment during travel, referred to as back-wedging, can require excessive torque on the stem to operate the valve, causing the valve assembly to jam, or twist-off and failure of the stem. The Wetherbee patent (U.S. 1,995,727) is an early expanding valve for low pressure gas mains. A reciprocable gate is provided with a wedge member which coacts with inclined surfaces on the gate. The wedge member is carried by the gate and is caused to engage a shoulder stop to arrest its movement therebeyond, and further movement of th gate effects wedging, expanding movement of the gate assem- bly into its sealing position. In the Erwin patent (U.S. 4,405,113), a complex expanda ble gate valve is disclosed having a first main stem which moves an entire multiple part gate as a unit in reciproca- tion upwardly and downwardly with respect to the fluid flow passageway, transversely across the valve body. The main stem has a coaxially aligned cam drive shaft having first and second oppositely threaded sections which function to respectively engage the main stem and a central gate block. The central gate block carries a plurality of cam surfaces thereon which are contiguous to each other, and which coop¬ erate with seal blocks which also carry cooperating contigu ous cam surfaces that interfit with the cam surfaces on the gate block. The seal blocks are moved outwardly as a resul of movement of the central gate block, and the coaxial cam drive shaft is moved by rotation after the entire valve assembly has been positioned across the fluid flow passageway. The cam surfaces formed on the gate block con- sist of a plurality of contiguous saw-tooth indentations, o triangular steps, in the gate block which cooperate with complementary cam surfaces on the seal blocks. The compli¬ cated compound or dual stem structure disclosed in this pat ent is the mechanism by which the upper central gate block is caused to undergo a reciprocating up-and-down movement within a certain limited range previously established by movement of the main stream to set the gate into position within the valve body. In the Erwin valve, the outer seal blocks will fre- quently ride upon, and bear primarily on, only one or at most two of the triangular camming surfaces for the reason that one of the camming surfaces is the highest, and pro¬ jects out further than the others. This frequently occurs due to the difficulty of machining precisely identical mat- ing saw-tooth surfaces over all of the gate that cooperates equally with all the seal block camming surfaces. The seal blocks consequently will frequently ride on, and bear pri¬ marily upon, only a single one of the camming surfaces. It is simply not possible, because of manufacturing tolerances to predict which of the triangular wedge teeth will protrud out slightly further than the others. Thus, there will be an unpredictable rocking movement of the gate in relation t the seal block due to this very localized support. closure member and the floating segment to expand the clo¬ sure member/floating segment to seal the valve seating surface. In one embodiment, the travel assembly has a lift-and- turn assembly which selectively rotates or axially moves the closure member such that opening and closing operations of the valve assembly can be performed with less effort. An object of the present invention is to provide an expanding valve having one or more segments on a gate wherein the movable segments have improved collapsing abil¬ ity and less resistance to movement between the valve open and closed positions. A further object of the present invention is to provide an expanding valve assembly which requires less torque to operate. Another object of the present invention is to provide an expanding valve assembly which has a long operating life during which fugitive emissions are minimized. Yet another object of the present invention is to pro- vide a valve operating mechanism which insures high integrity-sealing. An additional object of the present invention is to pro¬ vide a bidirectional expanding valve assembly. Another object of the present invention is to provide an expanding valve assembly of thinner dimension along the fluid flow axis. One further object of the present invention is to pro¬ vide an expanding valve assembly which facilitates inline repairs. Other objects and advantages of the present invention will become apparent as the following detailed description of the invention is read in conjunction with the accompany¬ ing drawings and the appended claims. Brief Description of the Drawings FIG. 1 is a diagrammatic representation of a prior art expanding valve assembly of the type having a gate attached to, and movable by, a stem member, the gate carrying a sin- gle upstream movable segment which coacts with the gate via male-female V-shaped contact surfaces on the segment and gate, respectively. FIG. 2 is a side elevational, diagrammatic view of an expanding gate structure constructed in accordance with the present invention having two, spaced truncated V-shaped con tact surfaces. FIG. 3 depicts, in side elevational, diagrammatical vie similar to FIG. 2, an expanding gate valve constructed in accordance with the present invention having two movable 5 segments which expand in the valve open position as well as in the valve closed position. FIG. 4 depicts an expanding gate valve which incorpo¬ rates two segments which expand to seal the valve in the closed position and a full conduit bore in the valve open o position. FIG. 5 depicts, in side elevational, partial cross- sectioned view, a bidirectional expanding valve assembly constructed in accordance with the present invention in which a gate carries a movable segment on each of its oppos 5 ing sides, so that fluid pressure can act in either direc¬ tion on either of the two segments, and the gate will function to seal in either direction. A novel turning mech anism is provided to move the gate/segment assembly. Detailed Description 0 With reference to FIGS. 1-3, the valve seats will gen¬ erally carry the reference numeral 10 for the upstream seat of the valve, and the reference numeral 12 for the down¬ stream seat of the valve. The valve seats 10, 12 generally extend around the fluid flow passageway through the valve 5 body in an annular configuration, and in the case of the present invention, can be a part of the valve body. The valve stem will be denominated by reference numeral 14. Stop elements which function to arrest the reciprocat- In order to facilitate an understanding of the differ¬ ences which characterize the construction of valves accord¬ ing to the present invention, as compared to the expanding gate valves of the prior art, an expanding gate valve 40, constructed in accordance with the present invention and shown in FIG. 2, is superimposed upon the prior art valve 20 in FIG. 1. The profile of the expanding gate valve 40 is depicted in chain dotted lines in FIG. 1. From this it is clear that the expanding gate valve 40 of the present inven- tion can be made much thinner along the fluid flow axis than the prior art gate valve 20 having but a single, large, female V-surface in the gate, and a corresponding male V- surface on the single segment. An examination of the gate valve 40 in FIG. 2 shows that a gate 18A, which is connected to a stem 14A includes a first imaginary female v-surface 42 which is truncated so as to provide inclined legs 42A and 42B which are spaced from each other in a direction parallel to the axis of the stem 14A. The legs 42A and 42B extend substantially parallel to, and coact with, correspondingly spaced legs 44A and 44B, respectively, formed on the movable segment 30A. These inclined legs 42A, 42B, 44A, 44B constitute, and are also described as, wedging-camming surfaces. In order to permit relatively shallow indentations in the gate 18A to form the two pairs of short inclined wedging-camming legs 42A and 42B, a second truncated V- surface having a pair of inclined wedging-camming legs is provided to form the second points of support for balanced and uncanted movement of the segment 30A. A second female truncated V-surface 46 is provided on the face of the gate 18A and has a first wedging-camming leg 46A and a second wedging-camming leg 46B; also a pair of spaced legs 48A and 48B are formed on the movable segment 30A, corresponding to wedging-camming legs 46A and 46B. It should be noted that, with the gate 18A thus con¬ structed to provide the relatively short inclined wedging- camming legs 42A, 42B, 46A and 46B, the thinnest point of the gate 18A has a dimensional thickness which is substan- supported at the two spaced points where the wedging legs 42B and 46B are located. The valve 40 is now in its fully open status. A bidirectional gate valve assembly 50 is shown in FIG. 3 and has a gate 18B which carries an upstream segment 52 and a downstream segment 54. The gate 18B is connected at its upper end to a suitable stem 14B. The segments 52 and 54 carry stop flanges 56 and 58, respectively, at the upper ends thereof. The stop flanges 56, 58 are disposed to con- tact stop elements 16B which are connected to, and remain stationary with, the valve body (not shown) during operation. The upstream valve seat 10 is contacted by an upstream sealing face 60 of the segment 52 during sealing operation, and the downstream seat 12 is positioned to be contacted by a downstream sealing face 62 of the downstream segment 54 during sealing operation. The two segments 52 and 54 are nearly identical, and can therefore be placed either on the upstream side or the downstream side of the gate 18B. The pressure differential of the fluid can act in either direc¬ tion across the gate 18B, and can be brought to bear on either segment 52 or segment 54, since the segments are of identical design and coact with gate 18B in the same way. In FIG. 3, the bidirectional gate valve assembly 50 is shown in the closed position as a result of the movement of the gate 18B downwardly (with the page bottom as a reference) and transversely to the direction of the fluid flow until the stop flanges 56 and 58 of the segments 52 and 54, respectively, have contacted the stop elements 16B and cannot continue to move with the gate 18B. At this time, continued movement of the gate 18B downwardly in the valve body causes the segments 52 and 54 to be wedged outwardly towards the seats 10 and 12, respectively. This results from the wedging of wedging-camming legs 64 and 66 carried on the gate 18B and corresponding parallel wedging-camming legs 68, 70 carried on the segment 52. Similar wedging action occurs between the wedging-camming legs carried on the downstream side of the gate 18B against corresponding parallel wedging-camming legs carried on the segment 62. It will be noted that the wedging-camming leg 64 is rel¬ atively widely spaced from the wedging-camming leg 66 along a line which extends parallel to the axis of the stem 14B. Also, it will be noted that the cooperating legs 64 and 66 at the upper end of the gate 18B and the legs 68 and 70 are spaced so that the force wedging the segment 52 axially to effect the closure of the valve is preferably distributed uniformly opposite the seat surfaces against which the seg- ent 52 is forced in sealing engagement. When the bidirectional gate valve assembly 50 of FIG. 3 is to be opened, the stem 14B is moved upwardly, causing the gate 18B to retract. As soon as this movement commences, the segments 52 and 54 can collapse to nest in the recesses defined between the wedging-camming legs formed on the gate 18B. This reduces the frictional drag exerted by the seg¬ ments 52 and 54 against the seating surfaces of the seats 10 and 12 of the valve 50, permitting gate-segment movement from the closed to the open position to proceed smoothly without excessive torque. When the bidirectional gate valve assembly 50 is opened, fluid flow passageway 34B through the segments 52, 54 and the gate 18B is raised into alignment with the fluid flow passageway through the valve body and through the two opposed seating surfaces of the seats 10 and 12. At this time, in order to seal the valve 50 in the open position where such is desired, a pair of second stop elements (not shown and which can be located above the stop elements 16B) arrest further upward movement of the stop flanges 56 and 58 which contact the second stops. Continued upward movement of the gate 18B causes it to move to the point where wedging-camming legs 72, 74 on the lower part of the segment 52 contact, and wedge outwardly, parallel wedging-camming legs 76, 78 on the gate 18B. Similar wedging action occurs on the downstream segment 54.* The spacing of the parallel, spaced wedging-camming legs or surfaces has been previously discussed and is applicable to these legs. These wedging actions again force the segments 12, respectively, to seal the valve in the closed position via the pairs of wedging-camming legs carried by the gate 102 and segments 104, 106. The gate 102 of the expanding valve assembly 100 has a lower conduit portion 120 through which the flow conduit 122 extends. The valve body 108 has a lower cavity portion 124 into which the lower conduit portion 120 extends when the expanding valve assembly 100 is closed. In the open posi¬ tion of the expanding valve assembly 100, the lower conduit portion 120 is raised to align the flow conduit 122 with the flow passageway of the expanding valve assembly 100. Each of the upstream sealing faces 117 and 118 prefera¬ bly carry a sealing ring 130 disposed in an annular sealing ring groove 132. The sealing rings 130 engage the sealing surfaces of the upstream and downstream valve seats 10, 12 when the segments 104, 106 are expanded axially outward from the gate 102 when the expanding valve assembly 100 is closed. The advantages of the present invention become clearly apparent with reference to the expanding valve assembly 100 of FIG. 4. The location of the wedging-camming surfaces interacting between the gate 102 and the wedge segments 104, 106 provides uniform force or pressure transferred from the stem 110 to the sealing faces of the valve seats 10, 12 to give bubble tight sealing. Also, the wedge angles are so chosen as to provide excellent collapsing ability to the segments to nest with the gate, essentially minimizing drag on the sealing surfaces of the valve seats 10, 12 when open¬ ing the valve. FIG. 5 FIG. 5 shows yet another expanding valve assembly 200 which is constructed in accordance with further features of the present invention. A valve body 220 includes an upstream fluid flow pas- sageway 222 and a downstream fluid flow passageway 224, and* the valve body 220 defines a central cavity denominated gen-, erally by reference numeral 226. The central cavity 226 is open to the fluid flow passageways 222 and 224, and also The recess 415 is of greater depth than the length of the key 414 so that the principal part of the stem 232 can move upwardly a short distance. The nut 326 is retained in position by an annular plate 400 which extends around its outer side; the annular plate 400 is bolted to the bonnet 228 by bolts 402 extended through holes 404. The annular plate 400 fits over the flange 324 formed on the lower end of the nut 326 and retains the nut 326 as shown. A pair of oppositely acting torsion springs 406 and 408 are disposed in the bore 334 in the nut 326 and form a part of a lift-and-turn mechanism 410 which is employed in the valve 200. The top torsion spring 406 has an end of a leg portion 406A extended into a receiving recess in the nut 326, and is then bent through 90° and curved through one or more convolutions which encircle the upper stem segment 412 of the stem 232. The top torsion spring 406 is then again bent through 90° and ends in a leg portion 406B. A lug 407 which is carried on the upper stem segment 412 of the stem 232 projects into the path of rotation of the leg portion 406B of the spring 406 when the spring 406 is rotated by the handle 390. The second or bottom torsion spring 408 has a leg 408A extended into a recess formed in the bottom or base of the bore 334 in the nut 326. The leg 408A is located about 180° around the circumference of the bore 334 from the recess into which the leg 406A of the top torsion spring 406 is extended. The bottom torsion spring 408 -is curved through one or more convolutions which encircle the upper stem seg- ment 412 of the stem 232, and ends in a leg portion 408B after being bent through an angle of 90°. The lug 407 also projects into the path of movement of the leg portion 408B when the bottom torsion spring 408 is rotated relative to the upper stem segment 412 of the stem 232. The valve assembly 200 in FIG. 5 is shown in its closed position. To open the valve assembly 200, the handle 390 is rotated counterclockwise (looking from the top), and the nut 326 to which it is keyed also undergoes rotation. This

Claims: What is claimed is: 1. A turning mechanism for a rotary valve having a valve body with a fluid flow passageway therethrough, and a closure assembly rotatably disposed in the valve body to selectively open and to close the fluid flow passageway, the turning mechanism comprising: a stem connected to the closure assembly; turning means supported by the valve body and rotatable about the stem for selectively rotating the stem; and coupling means interconnecting the turning means and the stem for coupling the turning means and the stem so that free uncoupled rotation of the turning means about the stem occurs during a limited free- travel interval of the turning means thereabout and so that coupled rotational movement of the turning means and stem occurs following such limited free-travel interval. 2. The turning mechanism of claim 1 further comprising: connecting means interconnecting the turning means and the stem for imparting selected axial movement to the stem in response to rotational movement of the turning means during the limited free-travel inter- val of the turning means. 3. The turning mechanism of claim 2 wherein the turn¬ ing means comprises a hub rotatably supported by the valve body and wherein the coupling means comprises: a lug member supported by the stem; a first bias means supported by the hub for contacting the lug member and imparting rotational movement of the hub to the stem in a selected rotational direction thereof; a second bias means supported by the hub for contacting the lug member and imparting rotational movement of the hub to the stem in the opposite rotational direction thereof, the first bias means and second bias means disposed to selectively provide no biasing contact with the lug member during the limited free-travel interval of the hub. 4. The turning mechanism of claim 3 wherein the first bias means comprises a first spring. 5. The turning mechanism of claim 4 wherein the second bias means comprises a second spring. 6. The turning mechanism of claim 5 wherein the first spring is a first torsion spring having a first end, a sec- ond end and a middle portion, the first end connected to the hub, the middle portion convoluted around the stem, and the second end forming a first bias contact disposed to selec¬ tively contact the lug member during rotational movement of the hub. 7. The turning mechanism of claim 6 wherein the second spring is a second torsion spring having a first end, a sec¬ ond end and a middle portion, the first end connected to the hub, the middle portion convoluted around the stem, and the second end forming a second bias contact disposed to selec¬ tively contact the lug member during rotational movement of the hub. 8. The turning mechanism of claim 7 wherein the first bias contact and the second bias contact are spatially dis¬ posed on opposite rotational sides of the lug member. 9. The turning mechanism of claim 8 further comprising: stop means for preventing the rotational movement of the stem beyond a selected arc of rotational travel. 10. An expanding valve comprising: a valve body having a fluid flow passageway defining a fluid flow path through the valve body, the valve body defining a body cavity in the fluid flow path; a valve seating surface disposed in the valve body at one location on the fluid flow passageway; closure means for selectively closing and opening the fluid flow passageway to fluid flow, the closure means comprising: a closure member disposed in the body cavity and having a first face and a second face, the closure member having a pair of spaced apart, substantially parallel wedging-camming surfaces disposed on the first face facing toward the valve seating surface; and a floating segment movably mounted on the first face of the closure member and having: a sealing face facing the valve seating sur- face in the valve body; and a closure member-contacting face on the oppo¬ site side thereof and contacting the first face of the closure member, the closure member-contacting face defining a pair of spaced apart, substantially parallel wedging-camming surfaces, the wedging-camming surfaces being spaced from each other and coacting with, mating with and extending substantially parallel to the wedging-camming surfaces disposed on the first face of the closure member; travel means for reciprocally moving the closure member movement of the operator handle other than the limited interval. 13. The expanding valve of claim 12 wherein the lift- and-turn means comprises spring means resiliently intercon¬ necting the operator handle and the valve stem. 14. The expanding valve of claim 13 wherein the spring means comprises: a first torsion spring having a first end connected to the operator handle, and a second end and a middle portion convoluted around the valve stem; a second torsion spring having a first end connected to the operator handle, and a second end and a middle portion convoluted around the valve stem in the opposite direction from the direction that the first tortion spring is convoluted around the valve stem; a valve stem thread carried on a part of the valve o stem; threaded means connected to the operator handle, having a thread engaging the valve stem thread on the valve stem, for reciprocatingly moving the valve stem along the axis thereof when the operator -. handle is moved; and stop means positioned to be engaged at different times by the second ends of the first and second torsion springs as the operator handle is moved for causing the valve stem to periodically rotate in one direction concurrently with movement of the operator handle, and then for causing the valve stem to rotate in the opposite direction concurrently with the movement of the operator nan- handle. 15. An expanding valve comprising: a valve body having a fluid flow passageway extending through the valve body and defining a path of fluid flow through the valve body, the valve body defin- ing a centrally located cavity in the fluid flow passageway; a pair of spaced, opposed, valve seating surfaces with¬ in the valve body and facing each other across the centrally located cavity, the valve seating sur- faces including: a first valve seating surface; and a second valve seating surface; a valve stem extending transversely to the fluid flow path; valve operator means mounted on the valve stem for selectively moving the valve stem; a gate connected to the valve stem for undergoing move¬ ment when the valve stem is moved by movement of the valve operator means, the gate having a major portion located in the centrally located cavity between the first and second valve seating surfaces, the gate being reciprocably movable in a direction transverse to the fluid flow path, the gate having a first face and a second face, and having two spaced-apart, substantially parallel, wedging-camming surfaces located on the first face, the gate having two spaced-apart, substantially parallel, wedging-camming surfaces located on the second face of the gate; a first floating segment movably mounted on the first face of the gate and having: a sealing face on one side of the first floating segment facing toward the first valve seating surface; and a gate-contacting face on the opposite side of the first floating segment from the sealing face, the first floating segment defining two spaced-apart, substantially parallel, wedging- camming surfaces on the gate-contacting face of the first floating segment and coacting with, and moving against, the corresponding two spaced-apart, substantially parallel, wedging-camming surfaces carried on the first face of the gate so that when the gate is moved relative to the first floating segment in one direction, the wedging-camming surfaces on the gate force the first floating segment toward the first valve seating surface, forc¬ ing the first floating segment sealingly against the first valve seating surface by movement of the first floating segment away from the gate; a second floating segment movably mounted on the second face of the gate and having: a sealing face on one side of the second floating segment facing toward the second valve seating surface; and a gate-contacting face on the opposite side of the second floating segment from the last- mentioned sealing face, the second floating segment defining two spaced-apart, substan¬ tially parallel, wedging-camming surfaces on the gate-contacting face thereof and coacting with, and moving against, the corresponding two spaced-apart, substantially parallel, wedging-camming surfaces carried on the second face of the gate so that when the gate is moved relative to the second floating segment in one direction, the second floating segment is forced towards the second valve seating surface, and the sealing face of the second floating segment seals against the second valve seating surface by movement of the sec¬ ond floating segment away from the gate; means positioned in the valve body for arresting movement of the floating segments while the gate continues to move so that the floating segments will be caused to expand outwardly away from the gate due to the interaction of the wedging-camming surfaces carried on the gate with the wedging-camming surfaces carried on the floating segments and wherein the valve operator means comprises: an operator handle; and a lift-and-turn means connected between the operator handle and the valve stem for permitting movement of the valve stem and the gate by the valve stem only when the operator handle is moved, the lift-and- turn means only reciprocating the stem 5 and gate in a direction transverse to the direction of fluid flow during a limited interval of movement of the operator handle, and the lift-and-turn means caus¬ ing the stem and gate to rotate with o movement of the operator handle at a time of movement of the operator handle other than the limited interval. 16. The expanding valve of claim 15 wherein each of the 5 valve seating surfaces is a part of the surface of a solid of revolution, and wherein the sealing face on each of the segments is correspondingly shaped in a configuration com¬ plementary to the valve seating surface toward which the respective segment faces. 0 17. The expanding valve of claim 16 wherein the lift- and-turn means comprises spring means resiliently intercon¬ necting the operator handle and the valve stem. 18. The expanding valve of claim 17 wherein the spring means comprises: a first torsion spring having a first end connected to the handle, and a second end and a middle portion convoluted around the valve stem; a second torsion spring having a first end connected to the handle, and a second end and a middle portion convoluted around the valve stem in the opposite direction from the direction that the first torsion spring is convoluted around the stem; a valve stem thread carried on a part of the valve stem; threaded means connected to the handle, having a thread engaging the valve stem thread on the valve stem, for causing the valve stem to reciprocate along its axis when the handle is moved; and a stud on the stem positioned to be engaged at different times by the second ends of the first and second torsion springs as the handle is moved to cause the stem to periodically rotate in one direction con¬ currently with movement of the handle, and then to rotate in the opposite direction concurrently with movement of the handle.

Inventors: NEVREKAR VENKATESH R, NEVREKAR, VENKATESH, R.
Applicants: NEVREKAR VENKATESH R, NEVREKAR, VENKATESH, R.
Application year: 1993
Main classification: F16K3
IPC codes: F16K3