IL40078A - A fast valve operator - Google Patents

Description

A FAST VALVE OPERATOR Ί This invention relates to valve operators and particularly to valve operators which are very fast-acting. In many instances it is desirable to have a valve which is quick-opening or quick-closing. This is especially true where fast-moving streams of abrasive particles are being handled, since in such an environment the valve is exposed to greatest wear during its movement from a fully closed to a fully open position. Thus, for example, the valve operator of the present invention might find usefulness in a process for processing anisotropic solid substances such as that disclosed in U. S. Patent 3 , 257, 080, issued June 21, 1 66 to P. H. Snyder. Other uses are as fast safety shut-off on fuel lines, etc., and for fast opening of fire-control valves.

While there is extensive prior art in the field of valve operators, our own conclusion is that most such operators depend on spring operation or on some complex mechanical inter-relationship of parts which would render them unreliable for certain operations, such as that required in the process of U.. S. Patent 3 ,257, 080 where long wear and accuracy of timing are fundamental requirements .

Among the valve operators which have come to our attention it is believed that U. S. Patent No. 3 , 095, 901 (Larson) issued Jul 2 , 1 63 provides a fair example of fluid pressure operated rapid opening valve structures as proposed in the prior art. It will be rioted that this patent discloses a pressure actuated piston adapted to be held in a cocked or pressurized position by an independently actuatable control device. The piston, however, also serves as the valve. in fields other than valve operators, we have found as most typical U. S. Patent No. 2, 535, 588 (Mead) issued December 26, 1950. This disclosure shows a fluid. driven impact mechanism which combines a pressurized hammer operatin plunger with a pressurized > actuating rod which serves to operate the hammer automatically when the operating plunger reaches the set cocked or fully-pressurized condition. There is provision for effecting manual release of the plunger but only at a pressure lower than the set pressurized condition.

As will be explained in more detail, the problems of causing a pressure actuated piston to operate a rotary valve operator have been very formidable, and it is clear that the solution of these problems represents an important advance in the art.

Accordin to the invention there is provided a fluid pressure actuated fast action valve operator comprising a pressure actuated piston adapted to be held in a cocked or pressurized position by an independently actuatable control device, characterized by means operatively interconnecting said piston with a rotary operating member, said control device being operative when said piston is in fully pressurized condition.

Intone embodiment the invention includes a chain and sprocket connection between the power piston of the operator and a rotatable shaft of the valve so that longitudinal movement of the piston results in rotation of the shaft; said chain encompassing a substantial portion of said sprocket and providing an amplified contact surface with the sprocket to assure proper transmittion of power from the power piston to the rotatable shaft.

Such a valve operator is faster operating than any other presently commercially available, and is so rapid that it may complete one-half of a complete cycle, so as to open or close a valve in approximately 10 milliseconds. la - > In order that the disclosure will be more fully understood and readily carried into effect, the following detailed description is given with reference to the accompanying drawings in which: Brief Description of the Drawings In, the accompanying drawings, in which like numerals indicate like parts : FIGURE 1 is an isometric view of a valve operator constructed in accordance with the present invention connected to a valve to be operated] FIGURE 2 is a side view, partly in section and partly in elevation, of the valve operator of FIGURE lj . FIGURE 3 is : a end elevational view taken along line 3-3 of FIGURE 2 and having portions broken away to more clearly show the various parts; FIGURE 4 is an enlarged sectional view of the dashpot in the main pneumatic cylinder of FIGURE 2; FIGURE 5 is a plan view of the alternate form of latch mechanism for use in selectively restraining the main valve shaft against rotation, with the parts shown in gripping or latching' configuration; FIGURE 6 is a plan view of the latch of FIGURE 5 but with parts shown in nongripping configuration.

. FIGURE 7 is a somewhat diagrammatic illustration of the actuator means of the valve operator of FIGURE 1 illustrating an alternate means for restraining and releasing the actuator means j and FIGURES 8 and 9 are fragmentary side elevational views, of the valve operator of FIGURE 1 showing an alternate form of the operator means, with the parts shown, respectively, in latching and nonlatching configuration.

Description of the Preferred Embodiment Referring first to FIGURES 1 and 3, there is -shown a valve body 10 which is connected in a flow line (not shown) and supported on a valve support 12. The valve may be of any suitable type but. the preferred form is a full-ported plug or ball valve, operable by rotation of its shaft 1 through an arc of 90° to open or close the valve. ·· ■ i The fast-acting valve operator comprising this invention for actuating the valve 10 is indicated generally at 16. Said operator is mounted in a support frame.18 including front and back mounting plates 18a and l8b and upper, and lower plates l8c and l8d, respectively. As shown in FIGURES 1 arid 3» the operator means includes a shaft 20 of gas under pressure and includes a pressure regulator 82. Through this arrangement, gas under pressure can be supplied selectively to either end of cylinder body 62 while air is exhausted from the other end. Fluid conduit 7 also preferably includes a flow control valve 83 having an orifice and adjustable needle valve. As explained more fully hereinafter, flow control valve 83 may be used to control the speed of the return, or closing, stroke of the valve operator., · · ' - ΐ Ϋ''Λ{·· " Slidably disposed in cylinder body 62 is a piston · 84 having a stem 86, the rear end of which extends through "rear plate 4 of the cylinder 61 and is connected to the chain coupling 50; so that as the piston moves forward ' .. .in cylinder body, 62 (to the left as viewed in FIGURE 1), chain 'coupling 50 and the lower end of chain 40 will move forward, rotating sprocket 38 and shaft 20 in a clockwise direction to open the valve 10. Conversely, movement of the piston to the right (as viewed in FIGURE 1) will rotate the ,shaft 20 in a counterclockwise direction to close valve " 10. A compression coil spring 87 may be provided to assist -the ;pneumatic pressurizing fluid in the forward, or opening, stroke of piston 84. Also, as is apparent, the spring 87 mayi if made sufficiently strong, be wholly substituted for the pressurizing fluid. A sleeve 85 is disposed about ste 86 between the pi3ton 84 and the rear wall 64. of the ^ cylinder.. As explained more fully hereinafter,., sleeve 85 act3 as a stop on piston 84 during the closing stroke of As may be noted from FIGURE 2, the lower end of chain ¾0, chain coupler 50 'and piston stem 86 are all •approximately in a straight line, which line is tangent to the sprocket 38. This arrangement prevents racking of the" shaft 20.and also provides for maximum straight- line transmission of forces between the power piston 8iJ 'and the sprocket 38. ·.'.'·· ·:'·'.·'* ·..· " .A. aashpqt, Indicated generally at 88 and shown in enlarged detail In FIGURE is provided in the forward end plate 63 of cylinder 61 to smoothly: terminate the forward travel of piston 8¾. As shown in FIGURE h9 the end plate 63 includes a vertical bore 90 in communication with gas conduit 72 and a horizontal bore 92 in communication with bore 90 and the forward end of the cylinder chamber. Additional horizontal and vertical bores ^ and 96» respectively, of reduced diameter also communicate with vertical bore 90 and the forward end of the cylinder chamber. A screw 0 in end plate 63 is adjustable to further restrict flow through passages 9'4 and 96..

As the piston 84 nears the completion of its . forward stroke, the forward end of piston stem 86 enters the horizontal, bore 92, cutting off the principal means of egress for air remaining in the forward end of the cylinder chamber; which air then must bleed through reduced diameter passages 9k and 96. This provides an air cushion effect at the end of the forward stroke 30 that, the piston stroke is terminated without shock. A positive stop •·':·*.·.. ..;··.'···.'· Means are provided for releasably restraining the valve operator means, including shaft 20, sprocket . 38 .and chain 40, against movement responsive to the .. actuator means of cylinder 6.1. and piston 84. In the preferred form of valve operator, restraining means com- ■ _ prise a projection or cam 100 secured to or formed on chain .. sprocket 38 and a pivoted trigger 102 adapted to releasably - engage the cam 100. Hard metal inserts 101 and 103. are ." preferably provided on the cam and trigger, respectively, to provide the actual contact surfaces. The inserts may be mounted as by dovetail extensions on the inserts which engage dovetail slots on the can and trigger. As shown in . FIGURES 2 and , the trigger 102 is pivotally mounted on' . a stub shaft 10 carried by the forward plate 18a of frame 18, •. and is biased toward a position engaging cam 100 by coil expansion spring 106. The coil spring 106 has one end attached to the trigger 102 and the other end to a support stem 108 extending from plate 18a. While it l3 preferred that, the restraining means be associated with the sprocket ...38 of the operator means, it is apparent that restrainin means with other parts of the operator means such as the ' chain 40 or shaft 20 or with a part of the actuator means such as the piston 84, stem 86, or chain coupling 50 would also function satisfactorily. .·'■_·■" • For releasing the restraining means, there is provided a control air cylinder 110 havin gas supply conduit 112 and exhaust conduit 114. Λ piston 116 is terminating in a resilient ball 120. When it is desired to releast trigger 102, gas under pressure is applied through conduit 112 to move the piston 116 and stem 118 to the right, as viewed . in FIGURE 2, until the ball 120 contacts the lower end of trigger 102, pivoting it about shaft 104 in a counterclockwise direction and releasing the cam 100. A coil spring 122 is provided in cylinder 110 to return.the piston to its original position once the supply of pressurizing gas is discontinued.

In operation, with the parts in the position shown in FIGURE 2, the valve is closed. Power piston 84 is disposed approximately midway in cylinder body 62 and trigger 102 is in engagement with cam 100 on the chain sprocket 38 to prevent clockwise rotation of the shaft 20. To cock the valve, four-way valve 6 is adjusted so that gas under pressure from conduit 80 is fed through . conduit 74 and control valve 83 into the right-hand side of cylinder body 62 behind the piston 84. The presence of pressurizing fluid behind the piston 84 will urge the piston forward in the power cylinder (in a direction to open the valve 10) but latch trigger 102 engaging cam 100 ■will restrain such movement. The valve operator, once cocked, may remain in that condition indefinitely. However, when it is desired to open the valve 10, pressurizing fluid is supplied through conduit 112 into the portion of the control, cylinder 110 behind piston 116 to thereby urge the piston ll6 forward, causing ball 120 to strike the trigger 102 and release the cam 100, as described above. When the trigger is released, the piston 84 and stern 86 will move forward within the cylinder 6l very rapidly responsive to the expansion of the compressed gas in the cylinder. By providing a relatively large volume - - position, a pneumatic spring effect is achieved whereby when ^ the piston is released, its forward movement is due principally to the expansion of gas already in the cylinder rather than to the admission of additional pressurizing gas. This provides for an extremely fast movement of the piston and concomitantly, rapid movement of the chain 40 about sprocket 38 to rotate sprocket 38 and shaft 20 in a clockwise direction.

Since, as explained above, the chain 40 engages sprocket 38 over approximately l80e , a large force transmitting area is made available, and additionally the torques on shaft 20 are somewhat balanced; thus reducing the tendency to displace, bend or twist the shaft 20. Also, as noted above, the. straight-line transmission of forces from the power piston 84 to the sprocket 38 along a line tangential to the circumference of sprocket 38 provides for maximum mechanical advantage .

At the completion of its stroke, the forward motion of piston 84 is cushioned by the dashpot 88 and finally terminated by the forward end of stem 86 seating fully in the horizontal bore 92 as explained above. The distance of travel of piston 84 in the cylinder 61 is such that one complete stroke of the piston will rotate the shaft 20 through a 90° arc, so as to move the valve 10 from a fully closed to a fully open position. To adjust the length of the actuating piston stroke, the position of the cylinder 6l may be adjusted horizontally by means of its mounting on plate l8b . The nuts 68 on mountin bolts 66 are loosened so that the bolts may slide horizontally in slots 67. The horizontal bolts 69 are then adjusted in their brackets 70 to horizontally position the -\ . -10- cy n er . nce e cy n er s a us e or p op s o e, of piston 84, bolts 68 are retightened so that the cylinder will remain stationary during operation.

To close the valve 10, the position of four-way valve 76 is. reversed so that pressurizing air from conduit 80 is supplied to. the left-hand side of cylinder body 62 through conduit 72 while air is exhausted from the right-hand side of the cylinder through conduits 7 and 78. This causes the piston 84 to move back, or to the right, as viewed in FIGURE 2, rotating shaft 20 in a counterclockwise direction and closing valve 10. The adjustment of the needle valve within speed control valve 83 controls the rate of return of the piston since it controls the rate at which gas can be exhausted through conduit 74.

Since, as discussed above, the movement of piston 84 to open the valve 10 is due to the expansion of gas already within the power cylinder, the control valve 83 does not affect the speed with which the valve opens, only the speed at which it closes.

A sto on the closing movement is provided by sleeve 85 on piston stem 86 which will engage the end plate 64 of cylinder 62 to terminate movement of the. piston. The sleeve 85 is dimensioned to allow for a slight over-displacement to assure that the trigger 102 will engage the cam 100. Then, as pressurizing gas is again admitted to the right-hand, side of cylinder body 62 to cock the valve operator, the piston will again move to the position shown in FIGURE 2.

An alternate form of restraining means for restraining the valve operator means including shaft 20 and sprocket 38 against rotation in a direction to open the valve is shown in FIGURES 5 and 6. Referring to FIGURE 5, there Is shown the shaft 20 with sprocket 38 thereon, journalled In ball bearing 22 mounted on the front wall 18a of the valve opera tor support frame. However, in this alternative form, the shaft 20, instead of terminating at the ball bearing 22, extends through the bearing 22 and wall l8a and has disposed on its outer end a tapered drum or hub 124., Mounted, on the outside of frame wall l8a, as by welds 126, is a rectangular housing 128 supporting in its central wall a nonrotating splined collar 130.

Slidably disposed in collar 130 is a splined shaft 132 having secured to its inner end a mounting plate 13 . A coil retainer assembly 136 is mounted on plate 134 by means of its two legs 138 and l40, respectively, which. pass through bores in the mounting plate 134 and are threaded at their lower ends to receive nuts 142. Confined between retainer assembly I36 and mounting plate 134 is a square-cut coil spring 144 which is coiled about the periphery of tapered hub 124 of shaft 20.

The outer end . of coil spring 144 is secured to mounting' plate 13 by bolt 146, while the upper end is free to move within retainer assembly 136. The tension in coil spring 144 may •be adjusted by adjusting the position of nuts 142 so as to compress or extend the effective length of spring 144 .

Means are provided for normally urging, the coil 144 into engagement with hub 124. These preferably comprise a second coil sprin 148 disposed about splined shaft 132 and confined between the inner surface of splined collar 130 and the outer surface of mounting plate 134. Spring 148 normally urges the mounting plate, spring-retainer assembly 136 and coll spring 134 inwardly so that the inner periphery of coil spring 144 will engage the outer surface of hub 124 as shown at A in FIGURE 5. hub 124 are provided by: a solenoid 150 which, when actuated, will overcome the force of coil spring 148 and move the coil 144, coil retainer assembly, coil mounting plate and splined shaft 132 outwardly so that the coil spring 144 clears hub 124 , as shown at B in FIGURE 6.

The manner in which this alternate restraining means operates is as follows: with the parts positioned as shown in FIGURE 5, the shaft 20 and sprocket 138 are restrained against rotation in a direction to open the valve. The direction of opening rotation is indicated by the bold arrow 152. However, any tendency toward rotation in this direction will merely cause the spring l44 ,. which is engagin hub 124, to wrap more tightly about the hub 124. Since the spring and its retainer assembly are unable to rotate, this effectively prevents rotation of the shaft and sprocket in the direction of arrow 152, However, the shaft and sprocket are free to rotate in the opposite direction since this will tend to unwind the spring 144 and loosen its grip on the hub 124. Therefore, when engaged, the restraining means prevents rotation in a direction to open the valve but permits rotation in a direction to close the valve .

When the valve operator has been "cocked" as hereinafter explained, and it is desired to release the shaft 20 and sprocket 138 so that the valve may open, solenoid 150 is actuated to move the parts into the position shown in FIGURE 6 so that spring 144 will clear hub 124 and permit its free rotation in a direction to open the valve.

In FIGURE 7 is shown a still further alternate form of means for releasably restraining the valve operator. This alternative means utilizes pneumatic pressure for releasably restraining the operator means as opposed to the mechanical trigger and cam latch of FIGURE 2, or the hub and spring is suitably connected to the operator means for operating the J~ valve between closed and open positions. The cylinder' has a modified forward end plate l60, oversized exhaust port I6l and exhaust line 162. Exhaust line 162 has therein a special highspeed solenoid valve 164 with the exhaust or downstream side of valve 164 leading through exhaust line 162 to atmosphere.

Pressurizin fluid is supplied to the cylinder.6l through gas supply conduit 80 which is connected to a suitable source, (not shown) of gas under pressure and includes pressure regulator 82. Supply conduit 80 is- branched at tee 166 to form dual gas supply conduits 168 and 170 with conduit 168 passing through solenoid valve 172 and into forward cylinder and plate l6o through port 174. Supply conduit 170 leads through solenoid valve 176 and into rear cylinder end plate 64 through port 178. Gas supply line 170 also includes, in the portion between solenoid valve 176 and port 178, a tee l80 from which branches exhaust conduit 182 which leads through speed-regulating valve 184 and solenoid valve l86 to suitable exhaust to atmosphere..

Suitable control means (not shown) are provided for selectively operating the solenoid valves 164, 172, 176 and l86.

Operation of the valve operator utilizing the pneumatic restraining means is as follows: Beginning with all solenoid valves closed, valves 172 and 186 are opened simultaneously. This admits pressurizing gas through line l68 and port 17 into the forward end of cylinder 6l (to the left of piston 84 as viewed in FIGURE 7). This will move the piston to the right as viewed in FIGURE 7, with air in the cylinder to the right of piston 84 being forced out through port I78, exhaust conduit 182, speed-control valve 184, and solenoid valve l86 .

Justed to control the rate at which air may be evacuated, " thereb controlling piston speed and avoiding shock to the mechanism. As piston 8 and piston stem 86 move to the right, sprocket 33 and shafts 20 are rotated in a counterclockwise . direction to close the valve 10 as discussed above. The travel of piston 84 is stopped when sleeve 85 around piston stem 86 engages rear cylinder end plate 64. When piston travel stops, solenoid valve l86 is closed and valve 176 is opened to admit pressurizing gas through conduit 170, valve 176 and port 1?8 into the bore of cylinder 62 behind piston 84 (to the right of piston 84 as viewed in FIGURE 7). At this point, both valves 172 and 176 are open, the other solenoid valves are closed, and pressurizing gas at equal pressure is present on both sides of piston 84. However, the area on which the pressurizing fluid acts on the forward, or left-hand side, of piston 84 is equal to the full face area of the piston including, piston stem 86, while the area on which the pressurizing fluid acts on the back side of piston 84 is equal to the piston face are reduced by the area of piston stem 86. This difference in area results in a net force to the right as viewed in FIGURE 7 which keeps the piston in its fully retracted position.

The valve operator is now cocked and may remain in that position indefinitely. When it is desired to rapidly open the valve 10, solenoid valve 172 is closed shutting off the supply of pressurizing fluid to the forward end of cylinder 6l and solenoid valve 164 is opened, permitting the rapid venting of the pressurizing gas on the forward side of piston 84 through exhaust line l62 to atmosphere. The compressed gas confined on the rear side of piston 8 then expands to rapidly move the . piston forward in cylinder 6l to open valve 10 as explained above.

In addition to the two mechanical and one pneumatic restraining mechanisms illustrated, other forms are of course possible, as, for example, a magnetic clutch assembly between the shaft 20 and some stationary portion of the valve operator support frame.

FIGURES 8 and 9 illustrate an alternate form of operator means which utilizes two aligned sprockets and an endless chain. Referring to FIGURE 8, there is shown the main shaft 20 which rotates valve 10 between open and closed positions. As described in connection with the FIGURE 2 embodiment , shaft 20 is suitably journalled in the frame 18 of the valve operator and has thereon a chain sprocket 38. An idler sprocket 246 is also provided on idler shaft 248 also journalled in valve operator frame 18. -Journalled about sprockets 38 and 246 is an endless chain 240 composed of individual links 242 connected by pins 244. A "U" shaped traveler car 190 is connected to piston stem 86. The open side of the "U" faces up so that endless chain 240 may nest inside the car 190. The end of the car distant from pisto stem 86 is attached to endless chain 24o by means of pins 192 which pass through the traveler car and chain. The traveler car is supported from below by linear bearing surface 194, attached to the main valve operator frame l8 by supports 196. Keying means (not shown) may be provided between traveler car 190 and linear bearing 194 to keep the two properly aligned during horizontal movements of the traveler car.

As in the FIGURE 2 embodiment above, a cam 100 is provided for engagement by trigger 102 to releasably restrain . drive sprocket 38 and shaft 20 from rotation in a direction to open valve 10. While the cam 100 is shown mounted on drive sprocket 38, it may of course be mounted directly on drive .

A slight modification of the trigger 102 is also shown in FIGURE 8. A roller 98 is mounted on roller bearings 200 near the end of the horizontal portion of trigger 102 in place of the hard metal inserts shown in FIGURE 2. The fric-tionless roller 198 engages the cam 100 to prevent operation of the valve when the valve operator is in a cocked position (as shown in FIGURE 8)and rolls into a releasing position when the trigger is released by actuation of control cylinder 110 (as shown in FIGURE 9). When the ball 120 provided on the end of piston stem ll8 of cylinder 110 engages the trigger 102 as shown in FIGURE 9, a downward loading is generated on the ball 120 and stem 118. A linear bearing 202 may be provided under ball 120 to carry this loading and prevent eventual damage to the piston stem II8. A positive stop 204 limits rotational movement of the trigger 102 to prevent overstretching of the return spring 106.

The valve operator functions in the same manner utilizing the alternate operator means of FIGURES 8 and 9 as previously described in connection with the FIGURE 2 embodiment. The movements of piston stem 86 responsive to pressurizing fluid in cylinder 6l are .transmitted through traveler car 190 to endless chain 240 to thereby close or open valve 10 by rotating the drive sprocket 38 and drive shaft 20. With the parts in the positibn shown in FIGURE 8, roller 198 of trigger 102 is in engagement with cam 100 preventing the drive sprocket 38 and shaft 20 from rotating in a clockwise direction to open valve 10. Pressurizing gas may then be admitted to cylinder 6l behind piston 84 to urge the piston forward and place piston stem 86 and traveler car 190 in tension. When it is desired to operate the valve, pressurizing fluid is supplied to control cylinder 110 behind piston 116 to urge the piston 116 forward, causing ball 120 to strike trigger 102 and release the cam 100, whereupon the piston 84 and stem 86 in cylinder 81 may move forward responsive to the expansion of compressed gas behind the cylinder. This causes piston stem 86 and traveler car 190 to move forward (to the left as viewed in FIGURE 8) very rapidly, thereby rotating chain 240 about sprockets 38 and 246, at the same time causing drive shaft 20 to rotate in a clockwise direction approximately 90° to open valve 10. With the valve in full open position, the parts are positioned as shown in FIGURE 9. .

The double sprocket and endless chain operator means of FIGURE 8 has certain advantages over that of the FIGURE 2 embodiment in that the chain coupling 50 with its cantilevered arm 5 of FIGURE 2 is eliminated and the two equal-size sprockets provide for smoother operation with less whipping of the piston stem 86.. By using the traveler car 190 with linear bearing 19 , all forces between piston stem 86 and endless chain 240 are kept linear with the piston stem travel and shocks induced by operation of the valve operator are distributed and partially dissipated by transmitting them through the linear bearing 19 and supports I96 to the operator frame l8.

- While the valve operator has been described in terms of quick*-opening a valve, it is apparent that it could also be used for quick-closing a valve, or, by employing two restraining or latch mechanisms, for both quick-opening and quick-closing of a valve.

Claims (22)

'40078/2 I Cl aims :

1. A fluid pressure actuated fast action valve operator comprising a pressure actuated piston adapted to be held in a cocked or pressurized position by an independently actuatable control device, and means operatively interconnecting said piston with, a rotary operating member, said control device being dperatabl e'-' vrhen said piston is in fully pressurized con-ditlon.

2. A fluid pressure actuated fast action valve operator adapted to control both the opening and the closing of a valve, comprising a rotary valve operating member, a pressure actuated piston, and interconnecting means through which said piston rotates said member, a control device being independently operable when said valve is in a cocked or fully pressurized condition to release said piston for movement of said rotary operating member.

3. A fast action valve operator according to claim 1 or 2, wherein said piston is adapted to effect both the opening and the closing of the valve.

4. A fast action valve operator according to claim 1 or 2, wherein said interconnecting means comprises a force transmitting device arranged for exerting a continuous, uniform torque on said valve operating member during movement of the piston.

5. A fast action valve operator according to any one of the preceding claims, wherein said piston is slidable in a cylinde and a valve system is operative for selectively introducing pneumatic pressurizing fluid into said cylinder on either side Of said piston, said valve system being adapted for.rapidly venting the pressurizing fluid on the side of the piston which permits rapid movement in a direction to open said main valve. , 40078/2 J*

6. Λ fast action valve operator according to any one of the preceding claims, wherein said operator member comprises a sprocket for rotating a shaft which operates a valve shaft, and said interconnecting member comprises a chain engaging said sprocket and connectable to said piston.

7. A fast action valve operator according to claim 6, wherein the chain engages said sprocket over approximately 180° of its circumference.

8. A fast action valve operator according to claim 6 or 7, wherein one end of said chain is connected to said piston so as to lie in a straight line relative to the direction of motion thereof, said line being approximately tangential to the circumference of the sprocket.

9. A fast action valve operator according to any one of claims 6 to 9, wherein said chain extends around an idler sprocket.

10. A fast action valve operator according to claim 9, wherein said chain is, an endless chain disposed about a drive sprocket and an idler sprocket.

11. A fast action valve operator according to claim 10, wherein said endless chain is connected to said piston by a traveler car supported from a stationary frame.

12. A fast action valve operator according to any one of the precedin claims, including a spring adapted to urge said piston toward valve opening position. 40078/2

13. A fast action valve operator according to any one of the preceding claims, wherein said control device comprises a detent, and mechanism is provided for suddenly releasing said detent to permit the piston to move said operating member in a direction to open the valve.

14. A fast action valve operator according to claim 13, wherein said mechanism for suddenly releasing the detent comprises a piston slidable in the bore of a pneumatic cylinder and having a piston stem thereon, a release device being provided on said piston stem for engagement with said restraining device to move said device from a first position restraining 'said operating member from opening the main valve to a second position permitting rsaid operating member to rotate in a direction to open said valve. .

15. A fast action valve operator according to claim 14, wherein said restraining device comprises a pivoted latch, and said operating member is connected to a projection adapted to be engaged by said latch to prevent rotation in a direction which would open the main valve.

16. A fast action .valve operator according to claim 15, including antifriction means positioned between said latch and the projection.

17. A fast action valve operator according to claim 16, wherein said antifriction means comprises a roller carried by said pivoted latch. , 40078/2

18. A fast action valve operator according to any one of claims 1 to 12 , wherein said control device comprises a hub rotatable with said operating member and a coil spring disposed about said hub means being provided for normally urging said coil spring into engagement with the hub to restrain rotation of said operating member i a direction to open said main valve while permitting rotation in a direction to close said main valve.

19. A fast action valve operator according to any one of claims 1 to 12 , including a valve system for applying a differential pressure across said piston to hold the operated valve in closed position, said control device being operative to release suddenly the pressure on one side of said piston and permit rapid movement toward the valve-open position.

20. A fast action valve operator according to claim 19, including means for isolating the higher pressure side of said piston from the pressure source prior to operation of said control device.

21. A fast action valve operator according to claim 19 or 20, including means for exhausting fluid from the low pressure side of said pisto to permit return to the valve-closed position.

22. A fast action valve operator substantially as herein described with reference to and as illustrated in the accompanying drawings. All. MULFORD Attorney for Applicants