US2627867A

US2627867A - Safety pilot control

Info

Publication number: US2627867A
Authority: US
Publication date: 1953-02-10
Anticipated expiration: 1970-02-10

Description

Feb. 10, 1953 H. F. scHoENr-ELD ErAL SAFETY PILOT CONTROL Filed Sept. 22. 1948 3 Sheets-Sheet l Feb. 10, 1953 H. F. scHoENFr-:LD Erm. 2,627,867

SAFETY PILOT CONTROL Filed Sept. 22. 1948 3 Sheets-Sheet 2 IN VEN TORS.

1F05/mana J Jm/Z/z/S/er Henry A c/memfeld A TTPNEKS.

Feb. 10, 1953 H. F. scHoENFl-:LD ErAL 2,627,857

SAFETY PILOT CONTROL Filed Sept. 22. 1948 3 Sheets-Sheet 3 Ill lll

/ IN VEN TORS BY @MKM TTUAPA/EYS.

Patented Feb. 10, 1953 naar UNITED STATES PATIENT '()l'lffIC'Ili SAFETY SPiLoT CONTROL 10 Ciaims.

his invention relatesto improved controls for gas burners, particularly controls embodying simple, reliable heat-responsive units of the type hereinafter described.

In the operation of gas burners, there is an element of danger arising outof the possibility that, following niterruption of the iiow of gas in the system or failure'of the pilot burner to continue to function for some other reason, gas may be admitted to and discharged unburne'd by the main burner. In' some types ci burners, provision is made for automatically cutting oi the supply of gas to the main burner but no provision is made for cutting oli the passage of gas to the pilot burner, thus permitting leakage oi the unburned gas from thepilot` burner. In an eort to remedy these deci'en'cies, controls have been proposed in the past that would cut off the supply of gas to both the main and pilot burners; however, such controls have proven to be complicated, unreliable, or both.

The present invention makes possible, and has for its principal lobject to provide, aY simple, reliable control for glas burners that operates to cut on" the supply of gas to both main and pilot burners in the event that somev abnormal condition inhibits operation of the 'main'burnen A further Vobject is to proviclea control that may without difficulty be installed, actuated, and adjusted to different conditions of operation. other object is to provide a control in which operation of the actuating mechanism is easily initiated from the exterior of the device. Still another object isl to provide' a Asimple, reliable heat-responsive unit for controls of these' and other kinds that may be installed, adjusted and, if necessary, replaced, all with a minimuml of effort.

The invention is illustrated in the accompany ing drawing, in which:

Figure 1A is a sectional plan, with parts ielevation, of a control constituting a'preierred embodiment of the invention;

'Figure 2 is a'verticalv section, with parts in elevation, along line 2-2 of Egurel;

Figure 3 is a verticalsection, with parts in elevation, along line 3 3 of Figure l;

Figure 4 is a transverse vertical section, `with parts in elevation, along line 4-4 of Figure l;

Figure 5 is a detail, on an enlarged scale, of the sealing assembly appearing in elevation in 1Figure 4;

Figure 6 is a diagrammatic perspective show ing the actuating mechanism oi Figures l, 3 and g 4 in me erst com) position;

Cil

2 Figure 'l isa similar view showing the same actuating mechanism in the second (pilot) position;

Figure 8 is a similar View showing the same actuating mechanism in the third (on) position; Figure 9 is a side'view of the outer cam lin the position illustrated in perspective in Figure 8;

Figure `10 illustrates the control of Figures 1 to 4 as employed with a gas burner used for heating water;

Figures v11,y 12 and V13' show, in'sectional plan, a :modified control within the purview of the invention and illustrate the actuatingmechanism thereof in the"off, pilot and on positions, respectively;

Figure 14 isa transversegvertical section on line Ill-I4 oi Figure V11; and

Figure 15 is' a side veW of the open link forming part of the actuating mechanism of the modified control of Figures' 11 to 14, inclusive.

The control illustratedin: Figures 1 to 9,'inelusive, is characterized, among other things, by a body or block havingjtwo` separate passageways therethrou'gh. In each. of vsaid. passageways is located a spring-pressed check valvebiased toward closed position. A rsinglejajctuajtorj serves both check valves, unseating Vthem seriatim `When the control is putinto operation. In normal operation, the actuator isV held byl a thermallyoperated detent' in a position in Vwhich both valves are unseated. Upon the development oi a condition which inhibits' continued operation of the main burner, the actuator functions to permit the check valves to seat, the seating being seriatim but in reverse order as compared with the Vorder in which the valves are unseated. Referringnow to Figures 3- and 4, body l, which preferably takes the form of a block machined from bar stock `or a casting, is provided with a wide threaded inlet 2-admitting gas from the suppl-y system. On the opposite side of body l is a narrotvthreaded outlet 3 through which the gas so admitted passes to the main burner. Between inlet 2 and outlet 3 is a smooth connecting bore d, whichV is narrower thanin-let 2 and. of substantially the same diameter as outa let 3. At the base of inlet2 is an annular shcul der 5 which servesas a valve. seat for main Vval-ve 6. The latterconsists, inv `addition to thevalve body, of an 0-ring packing 1-,- Ia, hollow stud 8, which, if desired.may be solid, spring centering means 9, and a coil spring Ill whichabutsfagainst and is vplaced. under compression by the inner en d ofva coupling member Il whichv serves/as a cap or retainer for the valve assembly.

As shown in Figures 1, 2 and 4, body I is further provided with a second threaded inlet I5, a smooth connecting bore I6 of smaller diameter, the latter constituting an extension of inlet I5, and a communicating cross bore I1 drilled from the exterior of body I at right angles to inlet i and connecting bore I6. The outer end of cross bore I1 is closed by a suitable plug. Between inlet I5 and connecting bore I6 is an annular shoulder I 8 which serves as a valve seat for pilot valve I 9. The latter is generally similar to main valve 6 in that it is provided with an 0ring packing 20, is biased toward seating position by a coil spring 2 I, and is retained in place by a coupling member 22 which is similar to, but smaller than, coupling member li. Mounted for movement with but on the opposite side of pilot valve i9 is a plunger 23 which extends through a suitable opening in the wall 24 separating connecting bore I6 from connecting bore 4. As indicated in Figures 1 and 4, plunger 23 projects well into connecting bore 4. Surrounding plunger 23 is the sealing assembly 25, shown in detail in Figure 5, which comprises an 0-ring packing 25, an overlying washer` 21 and a coil spring 28 which forces the O-ring packing 26 into sea-ling contact with plunger 23 and wall 24.

The purpose of inlet I5, connecting bore I6 and cross bore I1, is to provide a passageway admitting gas to pilot burner tube 33. i

Figures 2 and 4 illustrate the manner in which an orifice of the conventional type may be inserted in body I between cross bore I1 and pilot burner tube 33. A threaded bore 36 extending from the exterior of body I to a point in proximity to cross bore I1 provides access to a second threaded bore 3I of smaller diameter. The latter communicates with a smooth connecting bore 32 which extends through body I in prolongation of threaded bores 30 and 3I. Pilot burner tube 33 having openings 34 is brazed or screwed in place in connecting bore 32 at a point spaced from orice 35. Between orifice and the inner end of pilot burner tube 33 is an air opening 31 which permits air to mix with the gas passing through orice 35 into pilot burner tube 33. Access to orifice 3I may be had by removing oriiice cap 3B, which serves to seal bore 30 against the escape of gas when the control is in operation.

The actuating mechanism or actuator for main valve 6 and pilot valve I9 is located in body I in the relationship shown in Figures l and 3.

A transverse bore communicating with bore 4 in the first of the two above-described passageways extends from one side to the other of body i. At opposite ends of bore 40 two bushings 4I are mounted, as by brazing, in gas-tight relation to the ends of bore 40. Within bushings 4I is located a. shaft 42 which is so mounted as to permit it to have a considerable degree of rotary movement and which projects beyond the sides of body I. Rigidly affixed to sha-ft 42 at a point midway of bore 43 is an inner cam 43, shown also in Figure 4. On opposite sides of inner cam 43 and abutting bushings 4I are sealing assemblies 44 generally similar to sealing assembly 25. On the same side of body I as pilot burner tube 33 is an outer or locking cam 45 which is rigidly aixed to the projecting end of shaft 42. On the opposite end of shaft 42 is an actuating knob or dial 45 having indicia thereon which serve to disclose the position of the actuator at any given time. Within knob 46 is a return spring 41 of the torsion type, the ends of which are fixed to knob 46 and body I.

As shown in Figures l and 3, a post or rod 50 parallels pilot burner tube 33, being mounted in body I in such manner as to preclude the possibility of movement other than the hereinafter described movement of its free end. Preferably, post 50 is solid and fabricated from type 430 stainless steel having a co-e'icient of expansion of 0000065; however, it may be of hollow construction and, if desired, of some other material having a higher or lower co-efiicient of expansion. Adjacent post 50 is a generally L-shaped primary element 5I which has its outer end 52 at the end of the long leg thereof shaped to conform to and welded onto post 50 at the outer end thereof. Primary element 5I has a relatively high degree of expansibility, being preferably of type 43'/ stainless steel with a co-efcient of expansion of .0000095; however, any other suitable material with a co-efflcient of expansion of the same order of magnitude may be used instead; e. g., type 421 stainless steel.

The short leg 53 of L-shaped primary element 5I extends at right angles to the long leg thereof in a position to overlie outer cam 45. It is provided with a longitudinally extending slot (not shown) through which extend two screws 59 which serve to attach adjusting strip 51 to short leg 53. Adjusting strip 51 is coextensive as to width with short leg 53 of primary element 5I and is mounted for adjustment lengthwise of short leg 53 by suitable manipulation of the screws 59. At one end of adjusting strip 57 is a tang 53, struck up from strip 51, which serves as a cam stop for outer cam 45 in a manner hereinafter to be described.

Welded to primary element 5I at the unsupported inner end thereof, but at a point short of the point at which short leg 53 extends therefrom, is a secondary element 54 which, like post 50, preferably is, but need not necessarily be, of type 430 `stainless steel with a co-efilcient of expansion of 0000065. Therefore, as compared with primary element 5I, secondary element 54 is characterized by limited expansibility. At the end of secondary element 54 opposite the unsupported inner end thereof is an L-shaped bracket 55 one shank of which is brazed, welded or otherwise aiixed to secondary element 55 and another shank of which, extending at right angles, is received and welded in place in a slot 56 milled in post 50 at a point intermediate the supported and unsupported ends of primary element 5I.

Post 50, primary element 5I and secondary element 54 are so related, by being mounted in the manner above described, as to permit of considerable transverse movement but little lengthwise movement of either element. As the fla-me from pilot burner tube 33 strikes the near side of the free end of post 50, the supported end of primary element 5I, and such parts (if any) of secondary element 54 as are exposed to it, primary element 5I tends to lengthen as a result of its relatively high coecient of expansion. However, because of the relatively low coefficient cf expansion of secondary element 54, which places a limit on eiective lengthwise expansion of primary element 5I, the latter tends to bow toward post 50, an action which has the net eiect of imparting a generally clockwise or upward movement to the short leg 53 of primary element 5I and the unsupported end of secondary element 54 as seen in Figure l.

This transverse movement of the parts is somewhat accentuated by the limited expansion occurring in post 50 as a result of localized heating near the free end thereof on the side next gesmeerto pilot burner tube'33`. The side'of thefree end of post 50 near the pilot burner tube reaches a higher temperature than the opposite side; thus, the side nearthe-pilot'burner tube expands 'more than the opposite side. As a result, the freefend of post 5d tends to bend away from pilot burner tube 33 in a generally clockwise or downward direction as seen in Figure l, thus imparting to the supported outer end of 'primary element 5I a tur/ning force which has the effect of accentuating the generally clockwise or upward movement of short leg 53. Such movement of short leg 53 produces corresponding movement in strip 51 vand tang or cam stop 58.

By modifying the materials and proportions of the several parts, different operating-characteristics, particularly different operating ltimes, Vcan be developed in the heatresponsive unit. For example, the limited expansion of the free end of 'post 5c can be enhanced by using a type of stainless steel 'or some other Vsuitable 'material having a co-eicient of expansion "higher than the characterizing type zl'3'0 stainless steel. Simik larly, by varying the dierence in length between primary element 5I and secondary element 5d, it is possible to increase or decrease the sensitivity of the heat-responsive unit-andtherefore of the control as a whole. With due regard to these and similar factors, the present invention thus makes it possible to provide a 'control which, unlike 'the controls of the prior art, is capable or" reliable operation even at very high ambient temperatures.

Referring now to Figure 9, outer cam 45, which receives tang, takes the form of a shallow disklike member that may be cast as shown cr machined from an originally circular blank. Of its four quadrants, only two adjacent quadrants, .A and B, remain largely or entirely intact. Of a third quadrant C, nothing remains except a quarter-circle 5i) near the center. The fourth quadrant D contains a guiding slot 52 terminating in an inwardly extending notch or recess A63 located at the inner endof slot'62 but formed in quadrant A rather than in quadrant D. The inner wall of guiding'slot 62 vis dened by a quarter Circlet! which adjoins and is of thesame radius Aas the duarter circle-69 remain-ing at the center of quadrant C.

On the far side of guiding lslott? is`an arcuate member 65, located largely in quadrant D, oi which the inner edge 64 forms `the vouterwall of guiding slot 62. The radially extendingend face B1 of arcuate member 55 cooperates with tang 58 in a manner to be described, as -does also the radially extending face-66 located `at thepoint Where quadrant B and'quadrant C adjoin. Together with the recess 63 at the inner end of guiding slot 62, the semi-circular portion'il 'is .adapted to serve as part of a' detent mechani'sm'which includes tang 58.

As shown Yin diagrammatic vfashion in VFigures 6?, 7 and 8, the actuator 'for main valve .sand pilot valve I9 consists essentially of .shaft A2, .inner cam d3, outer cam i5 'and knob 4%. As indicated in Figure 6, `in the first (oi") position, valves 6 and I9 are seated on their respective'valve seats 5 and I3. In this positicn,.the lobeofinner cam d3 extendsdownward out of contact with Istud. 8 on main valve 6 and out of contact with plunger 23 on pilot valve IS. Tang 58 on adjusting strip 51 vis in contact with radiallyv extending face 56 formedfby outer cam dat thepoint wherey quadrants B andC adjoin. This zris therelationship of parts,mcr e particularly fthe yrelationship of the actuator to main valve '6 and pilot valve le, when the control unit .is 'iirst installed :in the mai-n burner.

When itis desired Yto place the control `in operation, kknob .45 is `.rotated counterclockwise through an arc 'of .'90,`which brings thelobe of inner cam 43 .into contact withplunger .23 of pilot valve I9 and thus forces the latter away from its seat on annular @shoulder I8. At the Vsame time, outer ca'm 45, being rigidly .aiixed .to :shaft d2, is rotated throughfan'arcsofie", which serves to bring `rad'ialiend `face 61 on arcuate'member 65 into contact with tang 58. This .is `the `second (.pilot.) position, and .is .illustrated in Figurev 7. With the 'parts in thisrelationto each other, Agas escaping through openings 3.4V in .pilot burner tube 33 `canine ignited. VIn @this position, spring .di tends to return .the'parts :to their zoriginalA Dosition, so that continuing :eiort must be .exercised through :knob '46 .to ykeep :pilot valve I9 unseatcd.

As the free end of `post "50-and the supported endofgprimaryfelem'ent 51 .heat up under .the inuence of the pilot -flame, short leg 53 ofprin mary element 5I moves .laterallyas already described, carrying with it--adjusting strip 5l and tang 5B. With knob :d5 heldin the second (pilot) position, short Aleg .53, adjusting `strip 51 and tang 58 move inward across radial end face 61 of arcuate member ,55 ,intoregistry with guiding'slct'62. `This action, v4whichnormally requires fromnfteen to thirty `Iseconds :for its :completion, permits the actuator vto vbe .rotated through va further arc of iby'continued counterclockwise movement .of :knob 4t. At this point the actuating mechanism-,arrives :at-the relationship indicated inFigure x8, .illustrating the third on) position.

In this position, the lobe on inner .cam d3 is in contact with -bothgplunger ,123 von pilot valve I9 and stud d on main valve 5,; so .that both pilot valve te and main valve 6 .zare now unseated. rThe iiow cf gas .past `main lvalve''which results permits the flame emanatingfromi openings St in pilot burner tube 3.3 to :ignite the gasescaping from the mainxburner. Ain the'meanwhil'e, continued lateral movement of short leg 53 of 'primary element 15|, adjusting strip :57 ,and tang 55 brings the latter 'into recess 163and, by detent action, prevents return spring Hiram restoring the parts to 'their original position.

Upon the development-of an abnormal condition which inhibits continued .operation yofthe main burner, vby which ,is .imeantthatfboththe flame at thefmain burner and that emanating from openings 34 in .pilotiburner .tube '33. have been inadvertently extinguished, jprimary element 5I tends to 'contract'. reversing the lateral travel of short .leg y53, adjusting strip 5l, and tang 53. Movement of tang 58 toward post 15d in consequence ofv this contraction .of primary element 5I results in -disengagement of tang and outer cam at the :innerend vofsguiding slot t2. Thisipermits progressive :returnof the vactuator, including.innerxcamit to :its original position, v'with' consequent :seating of main vvalve 6 and pilot valve Iil in that -f'crden Tang 5&3 rides on surfacesv i; I and 'Eil 'cfr lthe .inner semi-circular portion of vouter `cain'ltaunitil `'it Yiinally abuts radial face Se, at :which :point the parts again :in their originalfposition.

The control illustrated .in Figures luto 9, -inclusive, maybe installed-in' the system as vindicated ,in Figure/10. Sc installed,l abracket-lt holds body I inloperating position. Conduit'ii .suppliersV gasv :for @pilot burner `tube' `T33 to body I Conduit "I2 supplies gas for main burner I4 to body I. Conduit 'I3 supplies gas from body I to main burner i4. The control as so incorporated in the system is in addition to the control provided by the usual thermostat acting in response to changes in temperature in the water or other medium being heated by main burner '54.

A modiiied control is illustrated in Figures 1l to 15, inclusive. Such control, like that illustrated in Figures 1 to 9, inclusive, is characterized, among other things, by two separate passageways through a body or block, a springpressed check valve, biased toward closed position, in each of said passageways, and actuating mechanism, operable manually from the exterior of the control, for unseating the valves seriatim. Cooperating with the actuating mechanism and serving to hold both valves in unseated position is a heat-responsive unit similar to that illustrated in Figures l to 4 but lacking the angularly extending portion comprising short leg 53 of primary element 5I. In other respects, the modified heat-responsive unit comprising post |50, primary element |5| and secondary element |54 is much the same as the heat-responsive unit illustrated in Figures 6 to 8, inclusive.

As indicated in Figures 11 to 13, inclusive, the modified control comprises a body |||I machined or otherwise formed from bar stock or a casting. It is provided with a wide threaded inlet |62 receiving gas from conduit 'I2 (Figure l0), a narrow threaded outlet |03 permitting gas so received to travel thence to the main burner, and a smooth connecting bore IM. Inlet |62 and outlet |l3 extend at right angles to each other, being coupled together by connecting bore |86. At the junction of connecting bore IUI! and inlet |62 is an annular shoulder |05 serving as a valve seat for main valve |06. The latter consists, in addition to the valve body, of O-ring packing It?, hollow stud |08, spring centering means |09, and coil spring im, all of which are retained in place by action of coupling member III on spring H0.

At the opposite side of body IGI is an opening in which is received a bushing ||2 brazed in gas-tight relation in body IBI. Through such bushing extends a pin ||3, one end of which is received in stud |08 on main valve |06 and the other end of which projects beyond the body ||l I. Located between stud |08 and bushing ||2 is a sealing assembly H4 generally similar to the sealing assembly shown in Figure 5.

A second passageway through body IGI is formed by threaded inlet I l5, which receives gas from conduit 7| for the pilot burner flame; by a smooth connecting bore I6, relatively narrow as compared with inlet H5; by a cross bore drilled from the exterior of body ||l| and plugged at its outer end; by a threaded bore I I8 paralleling connecting bore IIE, and by a smooth outlet bore ||9 in which is mounted pilot burner tube 33, the latter being brazed or screwed in place. Located approximately at the center of body IEI is criiice |25, the same being inserted and removed through threaded bore ||8. The latter is sealed against escape of gas by oriiice cap IZI. Extending transversely through body I|l| at a point in proximity to the discharge side of orii'lce |23 is air inlet |22, shown in Figure 14.

Located at the junction of inlet ||5 and connecting bore ||6 is an annular shoulder |23 serving as a valve seat for pilot valve |24. The

latter is generally similar to main valve |66, being characterized by an O-ring packing |25,- a coil spring |25 biasing the pilot valve to closed position, and means taking the form of coupling member |27 for placing spring |26 under compression. On the opposite side of body IGI is a bushing 28 brazed in position in gas-tight relation in body li. Through bushing |28 extends a pin |29, the inner end of which, surrounded by a sealing assembly |36 generally similar to the sealing assembly shown in Figure 5, abuts against valve |25.

With the parts in the position indicated in Figure 1l; that is to say, with the parts in the cold position, the control is installed much as contemplated by Figure 10. When it is in order to initiate operation of the burner, force is applied manually to depress button |3|, which results in immediate unseating of pilot valve |24. This action permits gas to enter inlet H5, connecting bore HS, cross bore |I'I, threaded bore IIB, outlet bore H9, and pilot burner tube 33. The iioW o1n gas thus established permits lighting of the pilot ame. Localized heating of post |53 and the supported end of expansible element IE! results in growth of primary element |5| with consequent transverse movement of squared-oil end |33. At this point, the parts are in the position indicated in Figure 12, the main valve being closed and the pilot valve |24 being open.

If, however, an abnormal condition develops to inhibit operation of the burner, including the pilot flame, primary element |5| contracts, with resulting reversal of the original movement. The resulting inward travel of squared-off end |33 of primary element and secondary element |54 disengages link |32, permitting main valve |26 and pilot valve |24 to seat. Such seating takes place substantially simultaneously. Thus the parts return to the cold position indicated in Figure 1l, precluding all now of gas until such time as manual actuation is again employed to restore the system to operation.

Advantages of the invention as expressed in each of the two above-described embodiments include the possibility of installation of the control in almost any position, a feature which follows from the use of spring-pressed check valves rather than valves which depend upon the action of gravity. The controls illustrated in Figures 1 to 9 and Figures 11 to 14 are easy to manufacture, simple to assemble, and reliable in operation. They lend themselves to many uses other than the indicated use in connection with the heating of water; in fact, certain parte thereof such as the elements of the heat responsive unit, i. e., post 59 or |53, primary element 5| or ISI, and secondary element 54 or |54, as the case may be, lend themselves to installation in controls of other types. A high degree of reliability, coupled with flexibility, characterizes both the heat-responsive units and the controls themselves.

Numerous changes may be made without departing from the inventive concept and it is therefore desired that the invention should be accorded the scope contemplated in the appended claims, which are intended to define whatever features of patentable novelty reside in the invention.

We claim:

1. A control for a gas burner comprising a valve body provided with a valve alternately permitting and preventing now through the valve body; a post rigidly mounted on the valve body; a relatively expansible element of elongated form one end of which is supported from the post and the other end of which is unsupported, such unsupported end being located in proximity to but spaced from the valve body; a relatively ineXpansible element attached to the expansible element at a plurality of widely separated points one of which is near the unsupported end of the expansible element; and, mechanically connected to the valve, a manually movable latching member located in the space between the valve body and the expansible element, the unsupported end or the expansible element having a coacting portion serving as a detent for said manually movable latching member.

2. A gas burner control as in claim'l in which the manually movable latching member takes the form of a flat-surfaced link.

3. A gas burner control as in claim 2 in which the link is adjustable toward and from the detent.

4. A control for a gas burner comprising a valve body provided with a valve alternately permitting and preventing flow through the valve body; a post rigidly mounted on the valve body; a relatively expansible element of elongated form one end of which is supported from the post and the other end of which is unsupported, such unsupported end being located in proximity to but 'spaced from the valve body; a relatively inexpansible element attached to the expansible element at a plurality `of widely separated points one of which is near the unsupported end of the expansible element; and, mechanically connected to the valve, la manually movable cam member located in the space between the valve body and the expansible element, the unsupported end of the expansible element having a coacting portion serving as a detent for said manually movable cam member.

5. A gas burner control as in claim 4 in which the unsupported end of the expansble element includes a part that acts as a cam stop.

6. A gas burner control as in claim 5 in which the cam includes a slot receiving that part of the expansible element that acts as the cam stop.

7. A -control for a gas burner comprising a valve body provided with a plurality of functionally independent valves, each of said valves alternately permitting and preventing flow through the valve body; a post rigidly mounted on the valve body; a relatively expansible element of elongated form one end of which is supported from the post and the other end of which is unsupported, such unsupported end being located in proximity to but spaced from the valve body; a relatively inexpansible element attached to the expansible element at -a plurality of widely separated points one of which is near the unsupported end of the expansible element; and, mechanically connected to each of the valves in the valve body, `a manually movable latching member located in the space between the valve body and the expansible element, the unsupported end of the expansible element having a coacting portion serving as a detent for said manually movable latching member.

8. A gas burner control as in claim 7 characterized by the presence of mechanical means for seating the valves substantially simultaneously.

9. A gas burner control as in claim 7 characterized by the presence of mechanical means for seating the valves seriatim.

10. A gas burner control as in claim 7 characterized by the presence of mechanical means for unseating the valves seriatim.

HENRY F. SCHOENFELD. RAYMOND J. SMITHISLER.

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

UNITED STATES PATENTS Number Name Date 1,326,247 Zengel Dec. 30, 1919 2,027,458 Tepas Jan. 14, 1936 2,064,909 Hahn Dec. 22, 1936 2,179,633 Jenkins Nov. 14, 1939 2,240,950 Hahn May 6, 1941 2,308,272 English Jan. 12, 1943 2,363,525 Higley et a1 Nov. 28, 1944 2,381,926 Ray Aug. 14, 1945 2,385,155 Newell Sept. 18, 1945 2,420,078 Higley May 6, 1947 2,426,786 Newell Sept. 2, 1947 2,427,935 Vandenberg Sept. 23, 1947 2,487,968 Higley Nov. 15, 1949