US2597032A

US2597032A - Pressure operated follow-up system

Info

Publication number: US2597032A
Authority: US
Publication date: 1952-05-20
Anticipated expiration: 1969-05-20

Description

May 20, w, R

PRESSURE OPERATED FOLLOW-UP SYSTEM 2 Sl-iEETS-SHEET 1 Filed Aug. 25, 1947 INVENTOR) MLL/AM A1. 19A Y ATTORNEY y 1952 w. A. RAY 2,597,032

PRESSURE OPERATED FOLLOW-UP SYSTEM Filed Aug. 23, 1947 2 SHEETS--SHEET 2 |NVENTOR MLL/AM 4. 9/4) ATTORN EY Patented May 20, 1952 UNITED STATES TNT FFICE- PRESSURE OPERATED FOLLOW-UP SYSTEM Application August 23, 19487, Serial No. 770,265

7' Claims.

This invention relates to control systems and more particularly to systems for controlling burners of the fluid-fuel consuming type. The invention, in one of its aspects, relates more par-: ticularly to a fluid-pressure-operated control system which includes a pilot-valve-controlled pressure operator having follow-up means for pcsitioning the operator at a point or points intermediate its limits of movement. The present invention is, in some respects, an improvement upon the inventions disclosed in my Patents No. 2,317,640 and No. 2,331,502 issued, respectively, April 27, 1943 and October 12, 1943.

In heating installations which include a furnace having a fluid-fuel consuming burner, it has been observed that upon initiation of operation of the furnace severe reverberations frequently occur, especially in large installations, which reverberations may cause damage to the furnace and so affect the setting of associated control apparatus that readjustment is necessary. I have found that this trouble is mainly due to the fact that, if the flue or stack of the furnace is cold when the fire is started, there may be insufiicient or no draft, or even negative draft.

It is therefore an object of this invention to avoid such trouble, and I accomplish this object by providing a system which includes a fuelsupply' valve having means normally so restricting its opening that full flow of fuel to the burner is prevented, and means responsive to the existence of proper draft in the flue or stack, after a low-fire condition has been-established, for so conditioning the valve that it then can open to full capacity.

Another object of the invention is to provide a fluid-pressure operated control system which, while particularly adapted for accomplishment of the preceding object, is capable of performing various other controlling functions.

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, and to the appended claims.

In the drawing:

Figure 1 is a schematic view of a gas-burner control system embodying the invention;

Figure 2 is an enlarged view, mainly in section, of the valve structure shown in Fig. 1;

Figure 3 is an enlarged sectional view of the governor unit of the valve structure of Fig. 2;

Figure 3a is a detail section taken along the line 3a-3a of Figure 3;

Figure 4 is a fragmentary sectional view of a simplified form of the governor unit shown in Figs. 3 and 3a; and

Figure 5 is a sectional view showing essential parts of the governor-unit pilot-valve in positions assumed in operation.

Referring first briefly to Fig. 1 of the drawing, the numeral I I indicates a boiler furnace having a gas burner l2 whose fuel supply is controlled by a valve structure generally indicated at l3 and shown in detail in the other figures of the drawing. The other apparatus in Fig. 1 will be described hereinafter with reference to the operation of the system.

In Fig. 2, the numeral l4 indicates a main valve casing having an inlet l5 and an outlet l6 separated by a partition [1. Threaded in an opening through the horizontal portion of the partition is an annular seat member [8 with which a main closure l9 cooperates; the closure being provided with guide vanes 20 fitting the bore of the seat member. For. operating the closure is manually, under abnormal circumstances, there is a screw 2| engageable with the closure'and threaded in an opening in the bottom of the casing normally covered by a cap 22.

Mounted above the top of the valve casing M, by means of a hollow spacing-member 23, is a diaphragm motor comprising opposed dished plates 24 and 25 which are joined together at their flanges with the marginal portion of a flexible diaphragm 26 therebetween to form an upper and a lower pressure-chamber 21 and '28, respectively. The lower dished plate 25 is centrally apertured so that the chamber 28 is in communication with the interior of the spacing member 23. On opposite sides of the movablewall or diaphragm 28' is a pair of stifieningplates 29 to which a rod 30 is secured; the rod being connected at its lower end to the closure l9 and guided in a central opening through the bottom wall- 3| of the spacing member. In the wall 3| is another opening 32 which affords continuous communication between the valve-casing inlet [5 and the lower diaphragm-chamber 28.

Resting on top of the diaphragm plates 29, and guided in a sleeve 33 mounted in an opening through the unper dished plate 24, is a rod 34 which is pivotally connected at its outer end to a damper arm 35 pivoted at its left-hand end on the diaphragm motor. Leakage around the rod 34 is prevented by a bellows 36 encompassing the inner end of the rod. Since the rod 34 is not attached to the diaphragm plates, seating of the main closure [9 would not be impeded in the event that the damper arm 35 were accidentially held in raised position.

For controlling the operation of the diaphragm motor there is, mounted on the top of the same, a three-way pilot valve generally indicated at 31. This pilot valve comprises a casing having a central chamber 39 whose top and bottom walls are ported to provide valve seats with which a closure 49 alternately cooperates; the closure being connected by its stem to an electric solenoid 4|. When the solenoid is energized and the closure 49 resting by gravity on the lower seat, as shown, the upper chamber 21 of the diaphragm motor is in communication with the inlet I5 of the valve casing by way of a passage 42 (interconnecting the diaphragm chamber 21 and the pilot-valve chamber 39) the open upper pilotvalve port, and a pipe 43 which connects the space 44 above the upper pilot-valve port to the interior of the spacing member 23 and thereby to the main inlet I5.

Assuming that the valve inlet I5 is connected to a source of gaseous fuel, the pressure of the fuel is applied equally to both sides of the movable-wall or diaphragm 26 when the pilot valve 31 is in the condition shown and described; the diaphragm therefore being in its depressed position under the force of gravity acting on its associated parts, and the main closure l9 seated.

When the solenoid 4| is energized, the pilotvalve closure 49 is raised to close the upper port (so that communication between the diaphragm chamber 21 and the supply of pressure fluid is obstructed) and to open the lower port so that the space 45 below it then communicates with the diaphragm chamber 21. This space 45 is connected by a pipe 46 to the valve structure 41 of a governor unit 48, both hereinafter to be described. The valve structure 41 has a vent pipe 49 with which, under certain conditions of the valve structure, the pipe 46 is in communication, so that under those conditions the fluid compressed in the diaphragm chamber 21 can vent -to atmosphere when the pilot-valve closure 49 is raised, whereupon the pressure in chamber 28 The governor unit 48 is ounted on the spacing member 23 and, as can be seen in Fig. 3, comprises an elongated casing 69 bored at both ends and having an intermediate partition 6|.

Extending from the left-hand end of the casing 69 is the valve structure 41 which comprises a r hollow member 62 sealingly secured in the casing bore and having at its top a threaded opening 49' 'for the vent pipe 49 shown in Fig. 2. Threaded in the inner or right-hand end of the member 62 is a brushing 63 wherein a tubular member 64 is slidable. This member has on its left-hand end a conical head or closure 65 which cooperates with a valve seat 66 formed by the inner end of a fitting .61 threaded in the outer end of the member 62; to which fitting the pipe 46, shown in Fig. 2, is connected. Leakage of fluid around the member 64 is prevented by a flexible bellows 6B sealed to the head 65 and the bushing 63. The tubular member 64 is urged in a left-hand direction by a relatively light spring 69 compressed between the bushing 63 and a washer secured to the head or closure 65. Within the member 94 is a rod 19 which carries a spherical closure 1| cooperable with the adjacent left-hand end of the member, this closure being urged to seated position by a spring 12 (whose force is considerably greater than that of spring 69) compressed between the right-hand end of bushing 63 and a collar 13 adjustably secured to the rod 19.

Threaded in an opening in the governor-unit partition 6|, and extending to the right thereof, is an elongated member 14 whose right-hand portion is bored concentrically to freely receive the stem 15 of a pressure motor generally indicated at 19. This motor comprises a cup-shaped housing 11 secured to the casing 69 and containing an expansible-contractible metallic bellows 18 which is sealingly secured at its opposite ends to the housing 11 and to a plate or head 19 to which the motor stem 15 is connected. In the side Wall of housing 11 is a fitting 89 whereby the space or chamber between the housing and the bellows can be subjected to the pressure of a controlling fluid, which fluid may be the steam generated in the boiler II shown in Fig. 1, as indicated by the pipe 8| extending between the fitting 39 and the upper region of the boiler. Opposing the fluid pressure in the motor is a spring 82 compressed between the bellows head and a nut 83 threaded on the member 14; a ball-bearing thrust washer 84 being provided to facilitate adjustment of the nut.

The left-hand portion of member 14 is bored concentrically to receive a rod 85; the member having a recess in its left-hand face for packing 86, held in place by a snap-ring and washer. whereby leakage around the rod is prevented. Cut horizontally through the member 14 is an elongated slot 81 (better seen in Fig. 4) for a cross-bar 89 through the medium of which the motor-stem 15 can drive the rod 85; a stop-nut 89, adjustably threaded on the member 14, limiting left-hand movement of the cross-bar and thereby the movement in that direction of the stem 15 and rod 85.

As shown in Fig. 3, the left-hand extremity of the stem 15 is spaced from the cross-bar 88; the cross-bar being held in engagement with the stop-nut 89 by a lever 99 having an annular intermediate portion (see Fig. 3a) freely encircling the member 14 and engaging the cross-bar. The lower end of lever 99 extends through an opening in the bottom of casing 69 and. is there fulcrumed on the rounded point of a screw 9|, against which it is held by a spring-urged pin 92. The lever 99 is biased in counterclockwise direction by the force of a relatively stiiT spring 93 backed by a nut 94 threaded on member 14.

For operating the lever 99 there is mounted on the top of the casing 69 an electric solenoid 95, the plunger 96 of which is connected by a link 91 to an arm 98 pivoted on the casing and having a finger 99 engageable with a screw I99 in the upper portion of lever 99. A leaf spring I9I, below the plunger and held in place by a helical spring I92, serves as means for cushioning the fall of the plunger to the position shown (after it has been raised by energization of the solenoid) Interposed between the pointed extremities of the rods 19 and 85 is a cam I93 formed by a pair of opposed conical pieces secured to a plate I94. The plate I94 is pivoted on an arm I which in turn is pivoted on another plate I96, so that the rods 19 and 85 can move longitudinally, carrying the cam I93 with them. Thus, with the parts in the positions shown in Fig. 3, if the solenoid 95 is energized and the lever 99 thereby rocked clockwise out of engagement with the cross-bar 88, the rods 19 and 85 can move in a right-hand ass-7,032.

direction; undertheforce oi: spring 'l'z, to a position wherein the-cross-bar 88' has-been moved by the red 8-5 to-the right-hand endofsl'ot 8! (indicatedin Fig.- 4a).

Theplata Hiliis secured" toa shaft l ft-l which extends into-the interior of thespacing member 23 (Fig 2) and'is: there-secured toan arm: I 08 whichisconnectedby a link- I08 to a; plate I I secured; to the lower-diaphragm-plate- 28. By this connection, and the-arm; Hi shown-in Fig. 3; movement of the diaphragm ZG eii'ects rocking ofthecam F03, so--that theeffective-combined length of-"rods I0 and His-varied. In the outer surf-ace-of-the shaft I0! is a: groove- II I (Fig. 3) which affords fluid communication between the interior"ofthe-spacing-member 23 (and; hence, the-inlet I 5) and the compartment [t2 adjacent the valve-structure- 41; this compartment being otherwise sealed.

The operati'on oi the apparatus shown in Figs. 2 and 3- w-il-lnow be described in connection with the burner system of Fig. I. Itwill be observed that in Fig. lfuel is being supplied to theburner I1 (as evidenced bythe flames: I I3) and that the damper H4 is in partly-open position due to the elevated condition of the diaphragm 28 and the damper arm connected thereto. In Figs. 2 and 3 the parts are shown in their normal positions, corresponding to a cold condition of the furnace.

The solenoid 41 is connected by wires 5, in series with acontroldevice l I6, to terminals II! which, it'isto be-assumed, are those of an electricsource, preferably of low-voltage; The con.- trol device l lomay be such asamanual switch, a time-clock,- or' a safety or limit-control responsive toa: condition resulting from the: operation of=the burner *system and acting toopen ,the circuit-ofsolenoid M in the: event said condition becomesabnormal. As: was previously" described,

deenergization of the solenoid 4| effects seating of the main closure: I9.

Theother solenoid 95 is connected by wires II8 to theel'ectric source in series: with the control device H6. and another control device II9 which are open until proper draft has been established.

When, to initiate operation of the system, the solenoid. 4I is energized, the pilotevalve closure 40 is raisedso that, since (as-seen inFig. 3) the closure 65 of the-,valvestructured?! is spaced. by

'apshort-distancefrom its seatBB and the pipe 48 thereforein, communication with the: ventrpipe 49, pressure in the diaphragm; chamber 21 is relieved and the diaphragm and; closure H}, rise;

permitting fuel to pass to the burner I2 where it-is lighted bya pilot burner or'ot-her conventional igniting means (not-shown);

However, assuming that. the. furnace stack is cold, or-that there is insufiicient: draft-therethroughrand thecontacts of: the controlv device II 9 aretherefore-opemso thatthez-othersolenoid 9 5 is unenergized, upon rise of the closure I19. to a. position. wherein gas is: supplied to the burner in. an amount sufficient to produce .a low-fire the furnace, theresultanttrocking of the cam to sin aclockwisa direction; (asindicatedhrr he arrow and-legend" openiirr-Eia 3): eif c s uch movement of the rod 10 as to bring the closure; 65 into engagement with, itsseat. 6.8 (the closu following the. movement of; he. rod, unde the force 01 spring 69;) whereupon the venting of the d aphra m chamber- 21 is; interrupted. so; ha upward movement, of; the diap ra miand: ur I9, is arrested. The, low-fire;. position, of, the closure I9 is set by adjustmentv of the stop-nut 89 which (under the. conditions indicated, in Fig;. 3 determines the. pos t on. Of ro sbar and rod, and thereby -the" nit alv D SiBi ILQ-f 2 and, closure 05'.

When. due to thelow-fire, there. isprop r-draft inthe stack: I20, the contact f the control ,dee vice: I19 closesothat the: solenoid; 9,5 :is also nerizedr The resultant c ockw se o kingthe lever 9,0Qutof en ag ment with,m nnes ar effects movementrof-the, rodsflil. and; 85, under; the .force. of spring 12;. to a position wherein, the cross-bar isat the right-hand end of -it s slot 81. Since the closure; 65 is now widely spaced from its seat, thediaphragm chamber 2] is completely vented and the diaphragm and closure I9 rise to their full extent. By this rise of the diaphragm the cam I03 is rocked to a horizontal position whereinvthe efiective combinedlength of the rods 10 and 8,5 is the greatest (the effective combined lengthof, the; rods being the least when the cam is in the position. shown in Fig. 3). Such lengthening of-the rods is, however, now ineffective to causeseating of the closure the; approximate relative positions of the parts under the conditionsv just described being shown in .E ge 5- When, due to. the: high-fire condition now established in the furnacasteam is generated. in the boiler, its: pressure acting on, the bellowshead I9 gradually forces the, stem I5 inwardly so that itengages thecross-bar 88 and then moves the same, together with the, rods 85 and I0 and cam I03, in a left-hand direction. After the closure I55 engages its seat 66 (the closure following the movement of the rod 10 under the force of spring 69), continued movement of, the rod [0 unseats the ball closure 'II so that pressure-fluid can pass fromthe chamber I I2 (which, as previously described is incommunlcation with the inlet. I5) through the tubular member 64, and thence through fitting 61, pipe, 46, and the now-energized pilot. valve 31,, to the diaphragm chamber 21; the diaphragm, moving downwardly by gravity due to theequalizationof the pressure above and below it.v However, due to the follow-up connection, (comprising cam I03) between the diaphragm and the valve structure.4.l, the downward movement of the diaphragm (and closure I8) is quickly checked due to the reseating of the ball closure II resulting from theroching f the cam and decreasev of the effective combined length of 'therods 10 and85.

If the steam pressure rises despite reduction of supply of fuelto the burner, the operation, is repeated and the diaphragm and closure I9 arrested in still lower positions; thesupply of fuel being progressively throttled down until (if the steam pressure continues to rise) farther movement of the motor stem I5 is prevented, by engagement of the cross-bar 88 with the stop-nut 89; the position of closure I9 then being such that the burner is on low-fire.

With decrease ofsteam pressure, the resultant right-handmovement of stem 15, effectsunseatingrof the closure 65 and progressive rise of the 7 diaphragm as its chamber 21 is vented and then reclosed due to the follow-up operation of the closure 65.

The structure shown in Fig. 4 is identical with that of Fig. 3 except for the omission of the pressure motor 16 and its associated parts; the empty end of casing 60 being covered by a plate I22.

With the arrangement shown in Fig. 4, the burner can be operated on high-fire or low-fire (while the solenoid 4|, controlling pilot valve 31, is energized) as, for example, by controlling the energization of solenoid 95 by means of a thermostat responsive to the temperature of a space heated by the furnace; the solenoid 95 when energized effecting, through lever 90, movement of the controlling parts to their high-fire positions as shown in Fig. 5; these parts being returned, under the superior force of spring 93, to their lowfire positions (generally as shown in Figs. 3 and 4) upon deenergization of solenoid 95.

The specific embodiments of my invention herein shown and described are obviously susceptible of 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: v

1. In a fluid-pressure operated control system: means defining a pressure chamber and including a wall movable between limiting positions in response to change of pressure in the chamber; a source of pressure fluid; first valve means for controlling passage of said pressure fluid with respect to said chamber to effect movement of said wall in opposite directions; second valve means also controlling said passage of pressure fluid; means forming a follow-up connection between said second valve means and said wall whereby movement of the wall effects movement of the second valve means; means normally so conditioning said second valve means that, through said follow-up connection, the second valve means is effective to arrest the wall in a predetermined position intermediate said limiting positions; and means for rendering said conditioning means ineffective so that the wall can then move throughout its full range under the control of said first valve means.

2. In a fluid-pressure operated control system: means defining a pressure chamber and including a wall movable between limiting positions in response to change of pressure in the chamber; a source of pressure fluid; first valve means for controlling passage of said pressure fluid with respect to said chamber to effect movement of said wall in opposite directions; second valve means also controlling said passage of pressure fluid; means forming a follow-up connection between said second valve means and said wall whereby movement of the wall efiects movement of the second valve means; said follow-up connection normally being such that movement of the wall to a predetermined position intermediate said limiting positions effects such operation of the second valve means that the resultant pressure in said chamber arrests the wall in said intermediate position; and means for so altering said follow-up connection that the same is ineffective to operate the second valve means, and the wall can then move throughout its full range under the control of said first valve means.

3. In a fluid-pressure operated control system: means defining a pressure chamber and including a wall movable between limiting positions in response to change of pressure in the chamber; a

source of pressure fluid; first valve means for controlling passage of said pressure fluid with respect to said chamber to effect movement of said wall in opposite directions; second valve means also controlling said passage of pressure fluid and comprising means forming a valve seat and a closure cooperable with said seat; means forming a follow-up connection between said closure and said wall whereby movement of the wall effects movement of the closure; means normally positioning said closure in operative relation to said follow-up connection so that movement of the wall to a predetermined position intermediate said limiting positions effects such movement of the closure relative to its seat that a pressure condition is established in said chamber whereby the wall is arrested in said intermediate position; and means for so altering the position of the closure relative to the follow-up connection that the wall can then move throughout its full range, under the control of said first valve means, without effecting operative movement of the closure relative to its seat.

4. In a fluid-pressure operated control system: means defining a presure chamber and including a wall movable between limiting positions in response to change of pressure in the chamber; a source of pressure fluid; three-way valve means having a pair of passages whereby in one controlling position of the valve means said pressure fluid is supplied to said chamber through one of said passages to move the wall in one direction, and in the alternate controlling position of the valve means said chamber is vented through the other of said passages to eifect movement of the wall in an opopsite direction; additional valve means for controlling flow through a given one of said passages; means forming a follow-up connection between said wall and said additional valve means; means normally so conditioning said follow-up connection that, when the wall is in a predetermined position intermediate said limiting positions, flow through said given one of said passages is obstructed by said additional valve means; and means for rendering said conditioning means ineffective so that the wall can then move throughout its full range without eifecting obstruction of flow through'said given one of the passages.

5. In a fluid-pressure operated control system: means defining a pressure chamber and including a wall movable between limiting positions in response to change of pressure in the chamber; a source of pressure fluid; three-way valve means having a pair of passages whereby in one controlling po'sition of the valve means said pressure fluid is supplied to said chamber through one of said passages to move the wall in one direction, and in the alternate controlling position of the valve means said chamber is vented through the other of said passages to effect movement of the wall in an opposite direction; additional valve means for controlling flow through a given one of said passages and comprising means forming a valve seat and a closure cooperable with said seat; means forming a follow-up connection between said closure and said wall whereby movement of the wall effects movement of the closure; means normally positioning said closure in operative relation to said follow-up connection so that movement of the wall, to a predetermined position intermediate said limiting positions, efiects seating of said closure and thereby obstruction of flow through said given one of the passages; and means for so altering the position of the closure relative to the follow-up connection that the wall can then move throughout its full range without effecting seating of the closure.

6. In a fluid-pressure operated control system: means defining a pressure chamber and including a wall movable between limiting positions in response to change of presure in the chamber; a source of pressure fluid; three-way valve means having a pair of passages whereby in one controlling position of the valve means said pressure fluid is supplied to said chamber through one of said passages to move the wall in one direction, and in the alternate controlling position of the valve means said chamber is vented through the other of said passages to efiect movement of the wall in an opposite direction; additional valve means for controlling flow through a given one of said passages and comprising means forming a valve seat and a closure cooperable with said seat; means forming a follow-up connection between said closure and said wall, and including a cam whereby movement of the wall efiects movement of the closure toward and away from its seat; said connection also including means whereby said closure and said cam can move, as a unit, independently of said wall; means normally maintaining said unit adjacent said seat so that movement of the wall to a predetermined position intermediate said limiting positions effects, through said cam, seating of said closure and thereby obstruction of flow through said given one of the passages; and means for moving said closure-and-cam unit to a position away from said valve seat so that the wall can then move throughout its full range without effecting seating of the closure.

'7. In a fluid-pressure operated control system: means defining a pressure chamber and including a wall movable between limiting positions in response to change of pressure in the chamber; a source of pressure fluid; three-way valve means having a pair of passages whereby in one controlling position of the valve means said pressure 10 fluid is supplied to said chamber through one of said passages to move the wall in one direction, and in the alternate controlling position of the valve means said chamber is vented through the other of said passages to effect movement of the wall in an opposite direction; additional valve means for controlling flow through a given one of said passages and comprising means forming a valve seat and a closure cooperable with said seat; means forming a follow-up connection between said closure and said wall, and including a cam whereby movement of the wall efiects movement of the closure toward and away from its seat; said connection also including means whereby said closure and said cam can move, as a unit, independently of said wall; a spring biasing saidunit to a position remote from said seat; stop means for maintaining said unit, against the force of said spring, in a position adjacent said seat so that movement of the wall to a predetermined position intermediate said limiting positions effects, through said cam, seating of said closure and thereby obstruction of flow through said given one of the passages; and means for removing said stop means so that said closure-and-cam unit then moves to its biased position away from said seat, and the wall can move throughout its full range without effecting seating of the closure.

WILLIAM A. RAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,985,799 Scheifele Dec. 25, 1934 2,317,640 Ray Apr. 27, 1943 2,331,502 Ray Oct. 12, 1943 2,346,214 Flowers Apr. 11, 1944 2,368,017 Grad Jan. 23, 1945 2,396,205 Russell Mar. 5, 1946 2,416,766 Miller et al Mar. 4, 1947