US2716394A - Pilot controlled diaphragm valve with follow-up - Google Patents

Description

Aug. 30, 1955 v w. A. RAY 2,716,394

PILOT CONTROLLED DIAPHRAGM VALVE WITH FOLLOW-UP Filed Sept. 28, 1953 2 Sheets-Sheet 1 F ".4 r 1 7 ".1 36 3/ f 8/ 76 a q 37 5 5a 79 2 (95 I 59 60 6a 62 62 66. 76- 67 m 66 a2- 75 v m/f/vro/e,

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A T TOPNE W. A RAY PILOT CONTROLLED DIAPHRAGM VALVE WITH FOLLOW- Filed Sept. 28, 1953 2 Sheets-Sheet 2 INVENTOR, MLL/AM 4. PAY

HTTOENE'K United States Patent PILOT CONTROLLED DIAPHRAGM VALVE WITH FOLLOW-UP William A. Ray, North Hollywood, Calif., assignon to General Controls C0., Glendale, Calif., a corporation of-California Application September 28, 1953, Serial No. 382,623

2 Claims. (Cl. 121-41) This invention relates to fluid-pressure motors of the pilot-valve controlled type adapted for operating devices such as fluid control valves.

An object of this invention is to provide improved pilot-valve-actuating and follow-up means for controlling the operation of the motor so as to position the valve or other operated device in accordance with the magnitude of a condition, such as temperature or pressure, resulting from the;operation of the device.

Another object of the invention is to provide supplemental means for controlling the operation of the motor so as to effecton-off operation of the device.

A further object is to provide an arrangement whereby the on-oft operation of the device is effected through the medium .of the same pilot valve employed for the positioning operation.

For full understanding of the invention, and further appreciation of its objects and advantages, reference is to be had to the following detailed description and accompanying drawing, andto the appended claims.

In the drawing:

Figure 1 is a vertical sectional view (taken along the line 1-1 of Fig. 2) of a diaphragm-valve structure embodying the invention;

Figure 2 is a horizontal section taken .along the line 2..2.of Fig. 1;

Figure 3 is a fragmentary vertical section taken along the line 3.3 of Fig. 2; I

Figure 4 is a fragmentary sectional view, to enlarged scale, of the pilot valve and actuating means therefor shown, Partly in elevation, in Fig. 1;

Figures 5, 6 and 7 are fragmentary sections showing the essential elements of Fig. 4 in various positions assumed in operation; and

Figure 8 is a diagram showing the valve structure of Figs. 1-3 .as applied to the control of a heating system employing a gas-heated boiler.

In the drawing, the numeral 11 indicates a valve casing having an inlet 12 and an outlet 13 separated by an angled partition 14 which is provided with an opening through its top wall for receiving a port member 15. The open top of the casing is covered by a flexible diaphragm 16 which is clamped at its margin to the casing by the flange of a housing 17 mounted on top of the casing. The diaphragm carries on its underside a closure disk 18 which, together with a vaned member 19 below the disk and a stiffening plate 20 on top of the diaphragm, are held in place by a screw 21 and nut 22. The closure disk 18 cooperates with an annular seat 23 at the top of port member 15, and the guide vanes 24 of member 19 fit freely in the port. Connected by a fitting 25 to a downward extension 26 of screw 21 is another closure disk 27 which cooperates with an annular seat 28 at the bottom of the port member. Between the port member and a plate 29 clamped to closure disk 27 is a compression spring 30 which urges the closure assembly (comprising disks 18 and 27) and diaphragm 16 downwardly.

Mounted on top of housing 17 is a member or casting "ice 31 having in its bottom a recess 32 whose mouth coincides with an opening through the top wall of the housing. Within recess 32 is a structure 33 which includes a pilot valve 34 of the three-position type whose details are better seen in the enlarged fragmentary view of Fig. 4. Structure 33 is secured at its lower end to a pair'of bosses 35 projecting from the front and back walls of recess 32, and has a cylindrical upper portion which fits sealingly in an opening 36 in the top of the recess. At its upper end the opening 36 is in communication with the atmosphere by way of passages 37 with which an adjustable flow restriction or needle valve 38 cooperates. The structure 33 has in its lower end a horizontal passage 39 which (as is diagrammatically indicated at 40 in Fig. l) is in communication with the inlet 12 of the valve casing by way of a vertical passage 41 and pipe 42 (.both indicated in Fig.2) and an opening 43 in the back wall of the casing. Branching upwardly from passage 39 is an opening 44, the passage 39 being otherwise closed atits outlet end.

In Fig. 3 the numeral 45 indicates a conventional electromagnetic operator of the solenoid type which (as can be seen in Fig. 2) is mounted on a lateral extension of member 31 in front of the cutting plane of Fig. l and hence ,does not appear in that figure. The solenoid operator comprises a plunger 46 having a stem 47 whose lower end is grooved to fit freely in a slot 48 (see Fig. 2) in one end of an arm 49 which is pivoted on a bracket 50 projecting integrally from a lower part of structure 33. The plunger is biased downwardly by the force of a relatively strong spring 51 compressed between the base of the electromagnet and a washer 52 on the plunger stem. As shown in the figure the electromagnet is unenergized, the position of the plunger when attracted being indicated at 53.

Referring now more particularly to Fig. 4, the structure 33 has a vertical bore, aligned with and joining opening 44, wherein a tube 54 is reciprocable; a seal 55 of the O-ring type being provided around the upper part of the tube. Encircling tube 54 is a groove '56 for receiving the bifurcated left end of the solenoid-operated .arm 49 shown in Fig. 3 (and fragmentarily in Fig. 1). Since the solenoid is energized, arm 49 bears against the top shoulder formed by groove 56 and, under the force of the solenoid bias spring 51, tube 54 is raised to its highest position wherein a spring 57, urging the tube downwardly, is fully compressed. The ends of spring 57 bear against a snap ring 58 in the tube bore and another snap ring 59 at the top of the tube. At its lower end the tube 54 is of reduced internal diameter to provide a seat for a closure 60 which is urged toward seated position by the force of a light spring 61 compressed between it and the snap ring 59. Depending from closure 60 is a stem 62 which carries on its lower end another closure 63 which is cooperable with a seat formed at the top of opening 44.

When the pilot valve constituted by tube 54 and closures 60, 63 is in its extreme elevated position as shown in Figs. 1 and 4, recess 32 and the space or pressure chamber 64 above diaphragm 16 are in communication with opening 44 (by way of a transverse slot 65 through structure 33) and hence with the inlet 12 of the valve casing as previously described, so that the fluid pressures acting upwardly and downwardly on the diaphragm are generally the same and the closure disk 18 therefore seated under the force of spring 30.

For actuating the pilot valve there is a lever 66 which extends through slot 65 and is pivoted at its left end, as indicated at 67, on the bifurcated end of a channeled arm .68 which in turn is pivoted on a pair of bosses '69 (Fig. 2) on the back and front of structure 33. The arched and channeled portion 66 of lever 66 is freely 3 apertured around stem 62. Threaded in the right end of arm 68 is an inverted screw 70 having in its head a socket for a ball 71 formed on the top of a rod 72 which depends from the screw within the hollow of a tubular upward extension 73 of the diaphragm screw 21. A spring 74 compressed between arm 68 and the head of screw 70 serves to maintain the same in adjusted position.

Lever 66 is urged to rock counterclockwise by the force of a relatively strong spring 75 compressed between it and a lateral extension of structure 33. But since the right extremity of the lever is in lapping engagement with the underside of arm 68 (when the parts are in the positions shown in Figs. 1, 4, 5 and 6) and spring 75 is at the left of the pivot 69 of the arm, the force of spring 75 tends to rock lever 66 and arm 68, as a unit, clockwise so that rod 72 (depending from the right end of the arm) is continuously in engagement with the diaphragmscrew 21.

Within a tubular upward extension 76 of member 31 is a pressure motor comprising a metallic bellows 77 which is sealingly connected at its bottom to extension 76 and at its top to a disk 78 which forms the motor head. Around the bellows is a housing 79 which, with the bellows and its head, defines a pressure chamber for operating fiuid such as steam which may be introduced through a tube and fitting 80. Secured to head 78 is a fitting 81 to which a pair of interthreaded rods 82 and 83 is connected. The lower rod 83 projects through a bushing 84 threaded in an opening through the bottom wall of extension 76, a conventional sealing member 85 being provided around this rod. Aligned with rod 83, and maintained in engagement therewith by the force of a spring 86, is another rod 87 which extends through an opening in the structure 33 and is operatively engageable with the pilot-valve actuating lever 66. The bellows head 78 is urged upwardly by the force of a spring 88 compressed between it and an adjusting nut assembly 89 threaded on a tubular extension of bushing 84, the nut being accessible through openings (not shown) in the front and back of extension 76.

Figure 8 illustrates a typical application of the valve structure shown in the other figures. In Fig. 8 the numeral 90 indicates a main gas burner which is connected by a pipe 91 to the outlet 13 of the valve casing, a pilot burner 92 for igniting the main burner being shown connected to the inlet 12 of the casing by a tube 93. Above the burners, in a furnace indicated by a wall 94, is a steam boiler 95 to the upper region of which the tube 80 (Fig. 1) is connected. A vent tube 37' leads to the furnace from the vent passages 37 shown in Fig. 1. A conventional thermostat 96, which may be responsive to the temperature of a remote space heated by fluid from the boiler, is shown electrically connected by wires 97 to the solenoid operator 45 in series with a source of alternating current indicated by the symbol.

When, upon demand for heat by thermostat 96, the solenoid operator is energized its arm 49 is rocked counterclockwise, permitting tube 54 to move downwardly under the force of spring 57 into engagement with the arched portion 66 of lever 66, closure 60 being raised from its seat (against the light force of spring 61) after closure 63 seats. The parts are shown in Fig. 5 in the positions described.

Because of the altered flow-controlling positions of closures 60, 63 the gas compressed in the chambers above diaphragm 16 passes upwardly through tube 54 around closure 60 and vents to atmosphere by way of opening 36 and passages 37 at a rate determined by the setting of needle valve 38, so that the pressure of the gas below the diaphragm is effective to raise it and the main closure assembly against the force of spring 30. In the upward movement of the diaphragm the arm 68 is rocked (through connection 7072) counterclockwise about its pivot 69. Lever 66 remains in engagement with arm 68 under the force of spring 75, which is superior to that of p of the diaphragm.

4 spring 57 above tube 54, so that the tube is raised by the lever until it reaches a position wherein closure 60 is seated. Venting of gas from chambers 32, 64, and resultant rise of the diaphragm, then ceases; the parts being in the positions of Fig. 6.

With arm 68 in the substantially horizontal position of Fig. 6 the diaphragm is in a position such that the closure disks 18 and 27 are equally spaced from their respective seats 23 and 28, so that there is maximum flow of gas through the valve casing and a high-fire condition is established at the main burner; the tip of screw 70 then being in the plane indicated by the legend Hi Fire in Fig. 1. By adjustment of screw 70 the balanced position of pilot valve 34, wherein both of the closures 60 and 63 are seated, can be accurately set to correspond to the high-fire position of the main closure assembly.

Rise of steam pressure in the boiler produced by the high-fire at the burner effects gradual downward movement of the bellows head 78 and'rod 87, so that the tip of this rod finally engages lever 66 and rocks it aboutits pivot 67, permitting tube 54 to fall under the force of spring 57 so that closure 60 is unseated. The resultant escape of gas reduces the fluid pressure acting downwardly on diaphragm 16 so that the same rises under the constant fluid pressure below it, rocking arm 68 counterclockwise. In this movement of the arm the pivot 67 of lever 66 is lowered so that, under the force of spring '75, lever 66 rocks counterclockwise about the tip of rod 87 as a fulcrum, moving tube 54 upwardly to efiect reseating of closure 60 so that upward movement of the diaphragm is arrested. The right end of lever 66 is now spaced by a short distance from the underside of arm 68, generally as shown in Fig. 7 but to a smaller degree.

It the boiler pressure continues to rise the action described in the preceding paragraph is repeated, the pilot valve being returned to its balanced position due to the follow-up efiect produced by arm 68.

If the boiler pressure falls, the resultant rise of rod 87 and lever 66 eflects corresponding rise of tube 54 and unseating of the lower closure 63.

to fall so that arm 68 is rocked clockwise and the leverpivot 67 raised. Raising of pivot 67 effects clockwise rocking of lever 66 about the tip of rod 87 so that tube 54 falls and closure 63 is seated to reestablish the balanced position of the pilot valve and arrest of movement It has been found that best results are obtained by arranging the pivot 69 of arm 68 on the axis of rod 87. With these parts in the relative positions shown there is no tendency for lever 66 to slide on the tip of rod 87 in operation, as would be the case if the pivot 69 were displaced from the axis of rod 87.

In each successive rise of the diaphragm (in response to increase of steam pressure) the lower main-closure disk 27 is moved closer. to its seat 28' so that flow to the main burner is throttled. Upward movement of the diaphragm and main closure assembly is limited by engagement of the tipof screw 70 (on arm 68) with another screw 99 which is adjustable in a bushing 100 threaded in an opening through the top wall of chamber 32 and is normally covered by a cap 101. Screw 99 is adjusted (to a position indicated by the legend Lo Fire) so that when the main closure assembly is in its highest position there is a space between disk 27 and seat 28 for flow of gas sufiicient only to produce a low-fire condition at the main burner; the pilot valve and associated actuating and follow-up means then being in the positions shown in Fig. 7.

If, despite the low-fire, the boiler pressure were to increase, closure 60 would be unseated but no farther rise of the diaphragm (and follow-up action) could occur. With fall of boiler pressure and rise of rod 87 the closure 63 is unseated. as described above, so that the resultant increase of pressure above the diaphragm efifects The resultant increase of pressure above the diaphragm causes the same downward movement of closure disk 27 and increased flow of gas to the main burner.

Downward movement of the diaphragm in response to reduction of boiler pressure can occur only until the main closure assembly reaches its high-fire position, in which position the right end of lever 66 is in engagement with the underside of arm 68 (as shown in Fig. 6) so that no farther rise of the lever can occur despite possible rise of rod 87.

When the requirement for heat in the space controlled by the thermostat is satisfied and the solenoid operator 45 is consequently deenergized, arm 49 is rocked clockwise under the force of spring 51 so that tube 54 is raised to its extreme position (as shown in Figs. 1 and 4) wherein closure 63 is unseated and, since tube 54 is now out of range of actuation by lever 66 and can no longer follow its movements, the diaphragm falls to its lowermost position wherein the top closure disk 18 is seated and flow to the main burner fully obstructed.

It will be observed that if the boiler pressure were already high when the solenoid operator is energized, the main closure assembly would then rise directly to a throttling or low-fire position to eflFect balancing of the pilot valve, but in rising to the throttling position the main closure assembly would pass through its high-fire position and thus ensure ignition of the main burner.

It is within the scope of this invention to employ a pressure motor of the type wherein there is constant bleed of pressure fluid to the chamber above the diaphragm, and there is a vent for that chamber, of relatively large flow capacity, controlled by a three-position pilot valve. The intermediate or balanced position of that pilot valve is that in which the rate of flow through the vent is exactly equal to that through the bleed, its other two positions being those in which flow through the vent is, respectively, less and greater than through the bleed.

The specific embodiment of my invention herein shown and described is obviously susceptible of further modification without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In combination: a pressure motor comprising a wall movable between opposite positions; a pilot valve, of the three-position type, mounted on said motor for controlling pressure in the motor and movable in opposite directions from an intermediate balanced position to elfect movement of said wall in corresponding opposite directions, the pilot valve when in said balanced position effecting stoppage of the wall between its opposite positions; an arm pivoted intermediate its ends on the motor and connected at one end to the wall so that movement of the wall eflfects rocking of said arm; a lever for actuating said pilot valve, said lever being in lapping relation to a medial portion of said arm and pivoted on the other end of the arm so that rocking of the arm effects operation of the lever; means, including means responsive to a controlling condition, for operating said lever gradually upon variation of the degree of said condition to effect corresponding actuation of said pilot valve and resultant movement of said wall and rocking of said arm, said lever-operating means comprising a stem movable along an axis substantially intersecting said arm-pivot and having a tip operatively engageable with the lever so as to force the same in a direction away from lapping engagement with the arm when said condition varies in a given sense; and a spring, mounted on said motor, urging the lever in an opposite direction into engagement with the arm and thereby urging the arm in a direction toward said stem tip; said arm forming a follow-up connection between the wall and the lever, said connection being so arranged that the pilot valve is returned to its balanced position by movement of the wall resulting from said actuation of the pilot valve, the arrangement being such that the lever rocks on said stem-tip as a fulcrum in said return of the pilot valve to balanced position.

2. The combination defined in claim 1, and including supplemental power-operated means capable of actuating said pilot valve, independently of said lever, directly to an extreme position wherein movement of said wall to a given one of its opposite positions is effected, and wherein the pilot valve is out of range of actuation by said lever.

References Cited in the file of this patent 4 UNITED STATES PATENTS 1,075,733 Simon Oct. 14, 1913 1,141,114 Henderson June 1, 1915 1,563,988 Howse Dec. 1, 1925 2,398,158 Ray Apr. 9, 1946

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