US2548300A - Controlling pilot burner - Google Patents

Description

April 10, 1951 c. M. GARNER CONTROLLING PILOT BURNER 2 Sheets-Sheet 1 Filed Oct. 22, 1946 56 T a 5 6M wf a a mm. H a b 4 a W/ 7 .|4 1 Kajiblh ll ni a @E 6 MM 3 m April 10, 1951 c. M. GARNER CONTROLLING PILOT BURNER 2 Sheets-Sheet 2 Filed 001;. 22, 1946 Z k ZMT #6 M "W N 4 L m; w

Patented Apr. 10, 1951 CONTROLLING PILOT BURNER Claude M. Garner, Clayton, Mo., assignor, by mesne assignments, to Missouri Automatic Control Corporation, a corporation of Missouri Application October 22, 1946, Serial N0. 704,881

9 Claims. 1

The present invention relates to a controlling pilot burner for controlling the flow of fluid to a main burner and in which a control means such as a switch or the like is actuated in response to the presence or absence of flame at the pilot burner.

It is an object of the present invention to provide a simple, rugged and dependable controlling pilot of this kind which is very quickly responsive to the presence or absence of flame.

A further object of the present invention is to provide a device of this character in which two elements of substantially the same co-eflicient of thermal expansion are associated with the pilot burner such wise that, when the burner has a flame, one of the elements will be heated to a greater degree than the other one, or will be heated more rapidly and maintained at a somewhat higher temperature than the other one so long as the flame persists, whereby a switch, or the like, may be actuated by the resulting difierential in the expansion of the elements, and in which the other element will be heated almost as much as the one, so that a maximum positional differential is obtained.

A further object is to provide a device of this character having a particularly efficient temperature responsive device comprising a pair of elongated expansible elements which are rigidly connected at spaced points and which are weakened coextensively for a relatively short distance between their connected points so that when one of the elements is heated to a higher'temperature than the other, substantially all of the warping due to the differential in the elongation between the connected points will occur in the short coextending weakened portions, thereby to achieve greater actuating motion per degree of temperature differential in the two elements.

It is a further object of the present invention to provide, in a mechanism of this kind, a particularly accurate and dependable control.

Other objects and advantages will appear from the following description and the accompanying drawings, in which:

Fig. l is a front elevation of acontrolling pilot burner constructed in accordance with the present invention;

Fig. 2 is a side elevation of the pilot burner taken from the right of Fig. 1;

Fig. 3 is a rear elevation of the device taken from the right of Fig. 2;

Fig. 4 is an enlarged plan view;

Fig. 5 is an enlarged vertical section through the center taken from front to rear;

Fig. 6 is a fragmentary view showing the upper portion of the thermally-responsive elements in an exaggerated operational position;

Fig. 7 is a cross sectional view of the temperature responsive device taken on line 1-1 of 'Fig. 2.

Fig. 8 is a wiring diagram of a typical installation.

The control includes, as primary elements, a.

pilot burner, generally indicated at Ill, an, igniter therefor, generally indicated at H, a temperature-responsive device, generally indicated at 12, and an actuated device, here shown as a be provided with suitable mounting means such as the notch 20 and hook 2011 on the flange l8 by which the pilot burner may be attached to a main burner.

The pilot burner H1 is mounted between the two flanges I1 and IS. The pilot burner includes a base portion 22 that preferably is flat-sided,-

so that it may be supported against the inner surfaces of the flanges I 1 and I8 and secured thereto by screws 23.

nozzle 26 is a relatively large port or jet 28 at which the main pilot flame is produced. Extending halfway around the nozzle from jet 28 is a flame propagation slot 29 which serves to ignite a series of jets 30 arranged down the side of the burner opposite to port 28. On the same side as burner 28 and slightly below is a relatively small igniter jet 3|.

An igniter is disposed adjacent the igniter jet 3! at a point sufiiciently close to the jet to insure ignition, but sufliciently below the jetto avoid direct impinging of the flame on the.

igniter. The igniter element consists of a coil 32 of platinum wire, or the like, which is suspended between two forwardly projecting arms This base portion 22 has a longitudinal passage 24 therethrough and is 33 and as which are formed as parts of conductor members 35 and 35. The conductor members he along opposite sides of the pilot burner 26. The members 35 and 36 are provided with downwardly and rearwardly projecting arms 31 and 38.

The conductor members 35 and 36 are attached to opposite sides 'of the burner head 26 by 4 screws 39, 39a, 40 and 40a. Suitable insulating strips 4| and 42 are disposed between the mem bers and the burner head. Also 4 insulating washers 43, 43a, 44 and 440, are arranged outside of the conductor members and between them and the screws. The .conductor members are thereby effectively insulated from the pilot burner.

The two rearwardly and downwardly projecting arms 31 and 38 receive screws 45-and 46, by means of which terminal clips and 48, respectively, are attached. These terminal clips are adapted to connect a pair of leads 4i} and 50 to the conductor-members'35 and 3% respectively, and thereby tothe opposite ends of the platinum wire igniter coil 32. g

The temperature-responsive device l2'is of the rate-ofbhange type having twoelements i and 52 constructed of material having substantially the .same co-eflicient of expansion which lie alongside-each other in spaced relationship and which are secured together at the extremities of theirefie'ctive-length. Front 01 hot element .55 is disposed .withrelation to burner head 26 so that flames fed by theseriesof .jets .30 will directly impinge-upon it. It .is-.provided with'forwardly extending fianges 53 which co-extend with the series of burner jets wand which shield the flames issuing from these jets at their outer ends from stray drafts, thus insuring uniformrateof heat'absorption by element 5!. Flanges 53 are tapered,..diminishing in .width' toward the top. This provision promotes generally better flame characteristics.

:Element 5| is further provided at its lower end-withxa forwardly formedflip 55 which serves as a flame baffle "tOiDYOtGCt the switch structure [3. The rear or cold element 52 is arranged as indicated'so as to be'shielded from direct-flame by the element 5|.

'At its upper 'end'element 5| is'provided with rearwardly extending flanges 54, see Fig. 4, which are overlaid by similar forwardly extending flanges 55 on'the rear or cold element 52. Flanges 54' and '55 are securelyconnected as by spotweldingat :56 thereby securely fastening elements 5| and 52 at their upper ends. Element 52 is also provided with forwardly extending flanges 60 having extensions 51 which overlay flanges 53 on element 5| near its lower end. These flange extensions 57 of element'52 are also-securely connected to the flanges 53 of element 5| in a suitable manner as by spot-welding'at 58. Elements 5| and 52 are thus spaced laterally as indicated and securely fastened at the extremities of their effective length. The effective lengths of elements 5| and 52 in which elongation is effective to'warp the elements is therefore the length between the connected points 5% and 53. Element 52, although its length as a temperature responsive elements ends at the connection 53, has an integral downward extension 52d provided with relatively wide flanges indicated at 522) and which interfits with the deep channel-formgupport member l5 and is fastened to'the web portion 16 thereof by a bolt 68. The temperature 4 responsive device is thereby supported at its lower end.

There is a motion transmission member 55 arranged parallel with and between elements 5| and 52 which has its upper end securely attached to the upper end of element 52 as by spot-welding and which extends downwardly to a free end which is: arranged-to actuate-.zthe switch l3. The lower end of member 65 carries a threaded adjustable contacting member 66, which is provided with a non-conducting tip 61.

-Elementsi5l .;and 52 are stiffened throughout their lengthsbetween their connected points by flan es ;53.an'd 6'0 and by formed stifiening ribs 6I.and';6,2 respeCtively, see Fig. 7, with the exception of a short length on each element near their upper-sends as indicated at 63 and 54. These short eunstiflened portions which extend between the lower ends of flanges 54..and 55 and the upper ends of flanges 53 and 50 may be further weakened by cutting away portions of the web of both members as indicated. at 64a in Fig. 3. With this'substantial reduction in section modulus at these portions it will be seen that warping due to any expansion'diflerential of the two elements will be substantially limited to theseweakened portions andthat the point of tangency of the warp-curve'with the'unwarped stifiened portions will be at the upper ends'of flanges53 and 50. See Fig-'6' in which this warping is exaggerated to more clearly illustrate.

There are particular advantage in this arrangement. First; greater deflection or curvatureof the elements per degree :of temperature" diflerentialresults with this design and :consequently a greater-actuating movement per degree or temperature differential is achieved. Thisis true because the diiierentialin total elongation of;any elements between their connected points resulting. from a temperature differential is efiective to warp only the comparatively short weakened portions, which results in agreaterangular deflectionper degree of temperature differential than would occurif'the elementswere or uniform section throughout the distance between their connectedpoints. This will be readily understood when. considering that for any given differential in the elongation of two members connected as in this caseythe'shorter the length of the elements the greater will be their curva-' ture. Also, the total elongation or differential of elongation isproportional' to .the effective length of the elements when differentially heated, so that when the-total differential of elongation obtained bythe longer total effective length of the elements is constrained by stiffening to act on only a relatively short section of the effective length of the elements, then a greater curvature in the short sections will occur than if the elementswere 'of uniform section throughout their effective length and the curvaturetherefore uniform throughout their effective length. Further, in the compact arrangement-which is employed in the present invention for the multiplication and transmission of this angular deflection, it is apparent that for a given angular deflection at the upper end of element 65, the shorter thearc the less the upper end of member 65 will'move to the right with respect to the-actuated switch blade 13 and as aresult therewill be a greater net movement toward the left at the lower end of member 65. Secondly; a much more rigid and durable instrument may be constructed in following these principles.

Switch I3 is of the single-pole, double-throw type. having contacts 89, HI and 1| supported on resilient Switch blades I2, 13 and 14 respectively. The switch blades are stacked on bolt 68 with suitable insulating separators in a conventional manner as indicated. The bolt 68 therefore rigidly secures the switch structure and the temperature responsive device to the support member l5. Switch blade 13 is so formed as to normally hold contacts 18 and H in a closed position. Stop strips 15 and 18 are provided for switch blades 12 and 14 respectively. blade 14 and stop strip 16 are perforated at 1! to provide access to the switch blade 13 for the actuation thereof by contacting member 68 on the lower end of motion transmission member 85. The lower ends of the switch blades 12, 13 and 14 and the various leads attached thereto are encased in heat-resisting, waterproof, hardsetting cement '18 for the purpose of rigidly fixing the leads and protecting the connections against moisture and corrosive atmosphere. The web portion I6 of support member |5 has a lower integral extension |6a formed at a right angle thereto. The extension |6a is perforated and receives a bushing ||ib which receives an armored conduit I03 in which leads to be described hereinafter are contained.

In the wiring diagram, Fig. 8, a typical adaptation of the present invention is illustrated. In this arrangement a normally closed main burner fuel supply control valve is indicated at 19 having an operating coil 80 which, when energized, opens the main valve. A controlling and energizing circuit for the coil 88 is provided and includes a main-transformer secondary winding 8|, 8. lead 82, the valve operating coil 88, a lead 83, a space or room thermostatic switch 84, a lead 85, a heat production limit switch 86, a lead 81, the controlling pilot switch blade 12, the contacts 69 and Hi, the switch blade 13 and a lead 88 back to the other side of transformer secondary 8|.

A circuit for the energization and control of the controlling pilot igniter 32 is provided and includes an igniter-transformer primary winding 89, a lead 98, the switch blade 14, the switch blade 13, the lead 88, the main-transformer secondary winding 8|, a lead 9|, a push-button switch 92, a lead 93 back to the other side of the ignitertransformer primary winding 89 and a circuit in parallel with lead 99, including the ignitertransformer secondary winding 94, a lead 95, the lead 50, the igniter coil 32, the lead 49, and the common lead 99 back to the other side of the igniter-transformer secondary winding 94.

A pilot flame indicator light 96 is also provided, having a circuit therefor connected through the primary winding 89 of the igniter-transformer and which includes the lead 93 connected to one side of the primary winding 89, a lead.9'|, a resistor 98, the light 98 and a lead 99 back to the other side of the primary winding 89. Alternating current is supplied to the primary winding of the main-transformer I by commercial lines |8| and I02.

In operation When the controlling pilot is not burning, the pilot switch I3 and the actuating arm 85 will assume thepositions indicated in Fig. that is, the contacts 10 and II will be closed due to the rightward urging of formed switch blade '13 and the no-flame position of the lower end of motiontransmission member 85 which permits the closing of these contacts. Fuel is supplied to the Switch 6" burner head 28 through the fuel line 25 and passage 24 from which it issues at the jets 28, 30 and 3| and slot 29. The control of fuel flow through the fuel line 25 may be by any suitable means such as a hand operated valve not shown.

To light the pilot burner, the fuel valve controlling line 25 is opened and the push buttonenergization of ignition coil 32, ignition will takefirst, thereafter ignition will place at jet 3| progress to the main pilot flame jet 28 immediately above, thence around the burner head via the slot 29 and finally down the series of ports 30.

The flames burning at ports 39 impinge directly on the hot element 5| over substantially the full length thereof causing rapid absorption of heat 4 and elongation of this element. Due to their being securely connected at both ends the elongation of element 5| will cause warping of both elements 5| and '52. This warping will be substantially confined to the short portions 63 and 9 near the upper ends of the elements for the reasons hereinbefore explained. This will cause the inclination to the right of the upper flanged ends of the elements and consequently the upper end of motion-transmission member 65, causing its lower end and contacting member 66 to move.

to the left. Switch blade 73 will be moved there-.

by toward the left opening contacts 18 and 1| and closing contacts 39 and 70.

The opening of contacts 18 and II will break the igniter energizing circuit and also the circuit for signal light 96. The closing of contacts 69 and 18 will establish the following closed circuit,

for energization of the operating coil of the main burner fuel supply velvet-switch blade 13, lead 98, main-transformer secondary 8|, lead 82, valve operating coil 88, lead 83, room thermostatic switch 84, lead 85, heat production limit switch 86, and lead 81 back to contact 99. The energization of the valve operating coil 80 will cause the opening of the main burner fuel valve, admitting fuel to the main burner, which is ignited by the main pilot flame issuing from port 28.

In event of flame failure at the pilot burner for any reason, element 5| will lose temperature rapidly, causing both elements to move toward their unwarped no-fiame position shown in Fig. 5, and the lower endof member 55 and contacting member 66 will move toward the right, permitting the formed spring blade 13 to open the contacts 89 and 19, breaking the energizing circuit of the operating coil 89, thus cutting off fuel to the main-burner. As element 5| cools further, contacts l0 and H will be closed, thus readying the pilot ignition-circuit for operation by the pushbutton 92.

It may be well to point out that th time required in this device to actuate the switch mechanism in either direction, due to ignition or flame failure, is in the order of 12 seconds.

The foregoing description is intended to be illustrative and not limiting and the exclusive useessence of Tall modifications within the scope of the -.-appended claimstis contemplated.

.Irclaim:

:1. .Ina device of the class vdescribed, :a support member, .adevice to be actuated mountedon said support member, .an elongated temperature responsive devicesupported at one end bysaid support member and extending therefrom to a free end, said temperature responsive device comprisingza :pair of elongated elements lying alongside each other and being rigidly connected at their inner :and outer ends and being freely movable with relation to each other between their connected points toexpand and contract difierential- 1y, both of said elements being stifiened throughout their length with the exception of a short portionon each .of said elements .lying between their connected points and closely adjacent their outerends which portionsare substantially weakened against transverse bending said weakened portion-s being coextensive, whereby when one of saidelements is heated to expand more than the other, substantially all deflection will occur .in both elements in the :short weakened portions near their outer ends and whereby less transverse displacement-of the outer end of said'device'for argiven deflection thereof willoccur, and an actuating arm having one end attached/to the outer end of said elements and extending therewith toward saidsupport member for engaging saiddeviceto be actuated.

2. In a device of the class described, a rigid support member, an elongated temperatur responsivexdevice supported at one end on said support member and extending therefrom to a free end, said temperature responsive device comprising apair of elongated elements having substantially the same coeificients of expansion arranged substantially parallel and being spaced from each other exceptattheir ends at which they are rigidly connected to each other, both of said elements being:stifienedthroughout their lengths between their connected points except for a short portion on each element lying between their connected pointsand closely adjacent their outer free ends which portions are substantially weakened against transverse bending, said weakened portions being coextensive'whereby when one of said elements is heated to .a higher temperature than the other, substantially-all warping will occur in said weakened portions near one end and whereby less transverse displacement of the outer end of said'device for a given deflection thereof will occur, and an actuating arm having one end connected'to the outeriidefiectingend of said device and extending toward said support member toa free end.

.3. In a heat responsive device, a pair of elongated'elements arranged alongside of each other and rigidly connectednear their ends and being spaced from each other throughout the distance betweensaid connected points thereby to reduce heat .transfer'from one of said elements to the other, both of said elements being stifiened throughout their lengths with the exception of one relatively short portion of each of said elementslying between said connected points which portions .have a substantially reduced section modulus, said short portions being coextensive and near one :end of saidelements whereby substantially all warping due to the total difierential in expansion of the elementsbetween their connected points will be caused to occur in said short coextending weakened portions near one end of said elements whenone ofrsaid elementsisheated more than the other between their connected points, means for rigidly supporting saidelements at their opposite end, an actuating'arm attached to theiree warping end of said elements and ex tending substantially parallel therewith toward their supported end, and means for heating one of said elements to a higher temperature thanthe other between said connected points.

4. In a heat responsive device, a pair of elongated elements arranged alongside of each other and rigidly connected at first and second spaced points and being spacedfrom each other throughout the distance between said connected points thereby to reduce heat transfer from one ofsaid elements to .the otheigboth of said elements being stiffened throughout their lengths between said connected points except for one relatively short portion of each of said elements lying between said connected points which portions are substantially weakened against bending, said short portion being coextensive and near said first connected point whereby substantially all warping due to the total differential in expansion of the elements between their connected points will be caused to occur in said short coextending weakened portions near said first connected point when one of said elements is heated more than the other between their connected points, means for rigidly supporting said elements includingan additionally stifiened portion of one of said elements extending beyond said second connected point, an actuating arm attached'to said elements at said first connected pointand extending toward said support, and means for heating one of said elements'to a higher temperature than the other between said connected points.

5. In a heat responsive device, a pair of elongated elements having substantially the same coefficient of expansion and arranged alongside of each other, said elements being rigidly-connected near their ends and being spaced from each other throughout the distance between said connected points, both of said elements being stiffened throughout their lengths between said connected points except for one short portion of each of said elements lying between said connected points which short portions have a substantially reduced section modulus, said short portions being coextensive and near one end of said elements whereby substantially all warping of the elements due to the total differential in expansion of the elements between their connected points will be caused to occur in said short coextending weakened portions near one end when one of said ,elements is heated more than the other between their connected points, means for rigidly supporting said elements at their opposite end, and an actuating member attached to the warping end of said elements.

6. In a heat responsive device, a pair of elon gated elements arranged alongside of each other and rigidly connected at first and second spaced points and being spaced from each other throughout the distance between said connected points thereby to reduce heat transfer from one of said elements to the other, stiffening means for both of said elementsthroughout their lengths between said connected points except for one portion of each of said elements lying between said connected points which portions are substantially weakened against bending, said weakened portions being coextensive and adjacent said first connected point whereby substantially all warping will be caused to occur in said weakened portions adjacent :said first connected point when one of said elements is heated more than the other between their connected points, means for rigidly supporting said elements at their second connected point, and a motion multiplying arm attached at one end to said elements at their first connected point and extending substantially parallel with said elements toward said support.

7. In a temperature responsive device, a pair tion, said reduced portions being coextensive and near one connected end whereby substantially all warping will occur in said coextensive reduced portions near one end of said elements when one of said elements is heated more than the other between said connected points, means for supporting said elements at their otherend, a switching device carried by said support means adjacent the supported end of said elements, and an actuating arm having one end attached to said elements at their free warping end and engaging said switching device at its other end for the actuation thereof.

8. In a controlling pilot burner an elongated burner head having a longitudinally arranged series of burner ports, a heat responsive device comprising a pair of elongated elements lying parallel with each other and rigidly connected near their ends and being spaced from each other throughout the distance between their connected points, said device being arranged parallel with said burner head with one of said elements facing said burner ports and the other of said elements being shielded therefrom, said elements being stiffened throughout the distance between their connected points with the exception of one short portion of each element lying between said connected points which portions are substantially weakened against bending, said weakened portions being coextensive and near one end of said elements whereby when one of said elements is heated more than the other by flame at the burner substantially all warping will be caused to occur in said coextensive weakened portions near one end, means at the other end of said heat responsive device for rigidly supporting one end of said burner and said device adjacent each other in fixed relationship, switching mechanism carried by said support means, and an actuating arm 10 having one end attached to the free warping end of said device and extending substantially parallel therewith to said switching mechanism thereby to actuate it.

9. In a temperature responsive device, a pair of elongated elements lying substantially parallel with each other and rigidly connected near their ends and being spaced from each other throughout the distance between their connected points, said elements being stifiened throughout their lengths between said connected points except for one short portion of each of said elements lyin between said connected points which portions have a substantially reduced section modulus, said weakened portions being coextensive and near one end of said elements, whereby when one of said elements is heated more than the other substantially all warping will be caused to occur in said coextensive weakened portions near one end of said elements, means for rigidly supporting said elements at their other end, a switching device carried by said support means and adjacent the supported end of said elements, said switching device including a switch blade fixed at one end and having a free end movable to control a circuit and a switch actuating arm having one end connected to the warping end of said elements and having a free end engaging said switch blade at a point intermediate of its ends for the actuation thereof.

CLAUDE M. GARNER.

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