US2454229A - Thermoelectric generator with - Google Patents

Description

H. T. SPARROW 'THERIOELECTRIC GENERATOR WITH PILOT BURNER Nov. l6, 1948.

' Filed July 51 2 Sheets-Sheet 1 HOT JUNCTION otherwise be possible.

Patented Nev. 16, 1948 UNITED STATE THERMOELECTRIC GENERATOR WIT PILOT BURNER Hubert T. Sparrow, Minneapolis, Minn., asslgnor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn, a corporation of Delaware Application July 31, 1942, Serial 10. 453,113

20 Claims.

The present invention is concerned with a thermoelectric generator and more particularly with one adapted to be employed as a pilot burner in a burner control system;

An object of the present invention is to provide a combined pilot burner and thermoelectric generator which provides for the efficient lighting of a main burner and at the same time generates a relatively large electromotive force so that the electromotive force generated can be used for energizing a control system.

A further object of the present'invention is to provide a combination of a combined pilot burner and thermoelectric generator unit and a main burner in which the main burner is adapted to heat the hot junctions of the thermoelectric generator unit to a greater extent than the cold junctions so as to increase the electromotive force generated by the thermoelectric generator unit.

-A further object of the present invention is to provide a thermoelectric generator unit comprising a, plurality of thermocouples so arranged as to provide for the maximum temperature difierential between the hot and cold junctions and at the same time to provide a relatively compact un't. I

A still further object of the present invention is to provide such a thermoelectric generator unit in which the individual thermocouples are arranged in the form of U-shaped elements with the legs of the U-shaped elements disposed on opposite sides of the burner unit.

A still further objector the present invention is to provide such a generator unit in which the cold junctions are disposed in the path both the secondary and the primary air so that a large temperature difi'erential is maintained between the hot and cold junctions.

A still further object of the invention is to provide such a thermoelectric generating unit in which provision is made for protecting the elements adjacent the hot junction against corrosion so as to permit the use of metal of more desirable thermoelectric characteristics than would A further object 0! the present invention is to provide in connection with the burner and generating unit a new and nove1 burner unlt'which involves a minimum number of parts and which can be made in an extremely simple manner.

Other objects of the invention will be apparent from a consideration of the accompanying speciiication, claims and drawing, of which Figure 1 is a front elevational view oi my improved thermoelectric generating and burner unit,

Figure 2 is a side elevational view of my generating and burner unit, 7

Figure 3 is a vertical sectional view taken along the line 33 of Figure 2,

Figure 4 is a transverse sectional view taken along the line 4-4 of Figure 1,

Figure 5 is a side elevationalview of a portion of one of these thermocouple units.

Figure 6 is a view, partly schematic, of a gas burner control system employing my improved generator and pilot unit,

Figure '7 is a front elevational view, with portions broken away, of an alternative-form of my thermoelectric generator unit,

Figure 8 is a transverse sectional view of the burner unit of Figure 7, the section being taken along the line B-8 of Figure 7, and

Figure 9 is a sectional view of the burner unit of Figure 7, the section being taken along the line 99 of Figures '7 and 8.

Referring to Figures 1 to 4, the thermopile and burner of the present invention generally comprises a burner unit In (Figures 3 and 4) which i is supported in a Ll-shaped bracket ll, around which extends a member I! which acts as a support and cover member tor a plurality of U-shaped thermocouples connected together to constitute a thermopile.

Referring specifically to the burner Hi, this ignated by the reference numerals It and I5 (Figure 4-). Each of the members is provided with a plurality of tongues l6 (Figure 3), these tongues being bent around the edge of the adjoining memberso as to retain the two members in assembled relation. Each member is stamped so that its lowermost portion [9 is in the form of half a frusto-conical tube. Connecting with this grooved portion I9 and diverging upwardly is a, grooved portion 20, also in the form of half or a frusto-conica'l tube. The upper end of the grooved portion 20 joins with a further recessed portion II which diverges outwardly in an even greater angle terminating in a rectangular recess. The two portions I9 and 20 collectively define two frusto-conical passages joined by a narrow throat so as to provide a Venturi effect. The two portions 2| collectively define a diverging passage serving to lead the gas leaving the passage 20 to the outlet of the burner. At the extreme upper end, the two members I4 and I5 are spaced apart to form an elongated narrow slit 23 (best indicated a Figure 4).

Gas issuing through this slit, upon being ignited, results-in the flame for heating the various thermocouple units. 'The proper spacing between members l4 and i3 is maintained by a pair of stamped projections, one extending inwardly from each the members l4 and It. The .two projections 24 are cl 9. predetermined depth andserve to accurately space the members i4 and I3.

In the center of each of the, recessed portions 2| is a deeply grooved portion 23 which terminates at its upper end in an opening 21. The openings 21 constitute burner openings for igniting flames, which flames are of substantially greater size than the flames issuing through the v I 4 plementaiy to a similar semi-circular recess in the adjoining edge of tongue 44. These recesses in each case define a circular opening 34 through which a screw II is adapted to extend. As best indicated in Figure 3, screws 63 are threadedly engaged with the. U-shaped bracket ii. The

. screws 33 iunction to maintain the cover memslit 23, as'best indicated in Figured. Projecting being 01' identical shape in the case of each memher and being held closely together by reason of the clamping action of tongues i3 so as to constitute two spaced legs in efiect. Similarly, adjacent the upper outer end, members i4 and [5 are each provided with a pair oi-ears 3i and 32. These pairs of ears likewise are identical in the case of both members so that ears 3i of the two members act as one ear while ears 32 act as a second car. The legs 23 and 33 and the ears 3i and 33. are designed to cooperate with the U-shape supporting bracket II. This U- shaped supporting bracket is provided with slots in its base portion into which legs 23 and 33 extend and is provided with slots in its two side legs into which ears 3| and 32 extend.- The burner unit l3 is'thus held rigidly with respect to the U-shaped bracket ii.

A burner reducing nipple 35 having a connecting portion 36 and a threaded tip portion 31 is secured in the base'portion of U-shaped bracket The tip portion 31 is threadedly secured in an opening centrally 01' this base portion, with the tip portion projected into the mouth of the conical passage l3. The tip portion 31 and the conical portionsl9 and 23 of the burner l3 provideior the intake of primary air and the mixture of gas and air in a conventional manner.

The cover assembly I! is formed of two cover members 33 and 43. These twomembers are' identical and adapted to interflt with one another. Each of the cover members 33 and 43 is formed of sheet metal and is bent adjacent its edges to provide two end portions. In the case of each cover member, one end portion comprises a tongue 4i, ears 43 and 44 which are turned inwardly, and cars 45 and 46 which lie in the plane of the end portion. In the case 01 each cover member, the other end portion comprises two ears 43 and 53 which together define a recess adapted to receive the tongue 4|. This same end portion, in each case, is provided with two in-turned tongues 5| and 52, and with two further tongues. 53 and 54 which extend in the 'plane of the end portion. It will be noted in Figure 2 that when the end portion 01' one member is placed against the complementary end, portion of the other, the tongue 4! fits between the ears cover members.

hers 33 and 43 in assembled relation with the U-shaped member ll. Furthermore, the two cover'members 33 and 43 serve to increase the rigidity of the assembly comprising U-shaped bracket and burner l3 by counteracting any tendency of the legs or the U-shaped bracket II to spread apart and thus release the upper end of the burner.

The cover assembly 12 comprising the two cover members 33 and 43 functions not only to enclose the mechanism thus far described but also to sup-' port the series of U-shaped thermocouples which together define the thermopile o! the present invention. These thermocouples and the manner in which they are supported by cover members 33 and 43 will now be described.

The thermopile comprises a plurality of elements 63 and 6i of metals of difierent thermoelectric characteristics. Thus the element- 3| maybe of Copel and the element'Bi of Chromel. Copel is an alloy comprising 55 per cent copper and 45 per-.cent nickel. The Chromel which is desirably used is an alloy consisting of per cent nickel and 20 per cent chromium. The elements 63 and El are Joined at their upper ends, as indicated by the numeral 62 in Fig. 5 to form hot junctions. Each element 63 is connected to the adjoining element ii at its lower end, as indicated by the reference numeral 64. The junction constitutes the cold junction. A sleeve 66 surrounds each pair of elements 63 and BI adjacent their junction 62. This sleeve 33 is of stainless steel and is designed to resist heat and to protect the thermoelectric elements 63 and GI from the corrosive action of the flame.

By using such a sleeve of non-corrosive material to protect the thermoelectric elements, it is possible to 'employ' thermocouple elements having better thermoelectric characteristics than would otherwise be possible.

The thermoelectric elements are held in position between the cover members 33 and 43 and clamping bars 13, 1!, 12 and 13. The clamping bars 13, 1I,- 12 and 13 are formed of sheet metal stamped to provide ribs for re-enforcing purposes. The rib of clamping bar 13 is indicated by the reference character 15 and is best shown in Figure 4. In view of the fact that the ribs in connection with the other clamping bars are similar,

no reference characters have been applied thereto.

Cover members 33 and 43 are similarly stamped with rib portions 16, which rib portions serve to reenforce the cover members 33 and 43 and to retain ceramic spacing members 14. The clamping bars 13 to 13 are held in position bythe inturned tongues 43, 44, 5| and 53. These tongues serve to firmly hold the cover members I4 and I5 and the clamping bars 13 to 13 in assembled relationshipwith the thermoelectric members 63 and il firmly secured therebetween. The ceramic spacing members 14 are provided with a plurality of grooves into which the thermoelectric members 63 and BI fit. The members 14 thus serve to hold the members 33 and SI properly spaced apart.

Sheets 83 and 3| ofinsulating material are located between the thermoelectric elements and the I have conveniently employed sheets of mica for this purpose. Strips 33,11, 13,

and 19 of similar-insulating material-are disposed between clamping bars 10, 1|, 12 and 13. respect: ively, and the thermoelectric elements 50 and GI. It will be noted that the thermoelectric elements are surrounded on both sides by insulating mate rial and are thoroughly insulated from each other.

As best shown in Figure 6, the central portion of sleeve 68 surrounding the hot junction 52 is heated by a central runner flame 09 issuing from the opening 23 of burner I0 and extending the full width of the burner. Issuing from opening 11 are igniting flames 90 and 9|, which flames are em ployed to ignite the main burners I00 and i0 I, respectively.

It will be noted that the thermoelectric elements 60 and BI form a series of U-shaped thermocouples, the legs of which straddle the burner This results in a very compact structure and utilizes to the utmost the cooling eifect of the incoming gas and air as will be pointed out more fully later. Furthermore, the bends of the thermocouples form a cage enclosing the runner flame 89 and protecting it against extinguishment.

The manner in which the improved thermoelectric generator unit is employed in a burner system is illustrated schematically in Figure 6. As shown in this figure, the generating unit is employed to energize the electromagnetic pilot valve of a diaphragm valve. This diaphragm valve 95 may be of any conventional type in which a sensitive electromagnetic pilot valve controls the pressure ap-.

. The type of valve which I have found particularly desirable to employ in connection with such a generator and in such a system as shown in Figure 6 is the valve shown in my copending application Serial No. 437,541, filed April 3, 1942, and issued as Patent No. 2,393,427 on January 22, 1946.

The valve assembly 95 is provided with two electrical terminals 96 and 91 which are connected to the ends of the winding of the electromagnetic pilot valve. vided with a bleed opening 94 which is connected with a pipe 93 leading to a bleed burner 98. When a source of power is connected across terminals 95 and 91 the electromagnetic valve is moved to such a position that the gas from the pressure chamber formed by the diaphragm is bled 01! to The valve assembly is'further prothe bleed burner 98 and the dlaphragmmoves the main valve to open position. When power is removedfrom terminals 96 and 91, the pilot valve moves to a diiferent position in which the escape of gas from the controlling chamber through pipe 93 and bleed burner 90 is prevented with the result that pressure builds up within the diaphragm chamber and causes the main valve to move to closed position.

The valve assembly 95 controls the flow at gas to a plurality of main burners I00 and IN, being connected thereto by pipe I03. The pilot burner and generator unit is rigidly mounted with respect to burners I00 and IN so that the flames 90 and 0| issuing from openings 21 just extend over the inner ends of the burner in a position to ignite gas tions, the cold junctions are located in a relatively cool portion of the burner. As is well known, the temperature within a burner chamber drops sharply below the main burner due to the inrush to insure closure of valve assembly 95 when the themopile is not heated as a result of the pilot burner being extinguished but is also operative to supply current for the operation of the valve. Current is supplied to the valve assembly 95 under the control of a thermostat I01. This thermostat is of conventional form comprising a bimetallic element I08 to which is connected 9. contact arm I09 movable into and out of engagement with a fixed contact H0, As indicated by the legend adjacent the thermostat, the bimetallic element I08 is effective to move contact arm I09 towards the right into engagement with contact H0 when the temperature drops. While the thermostat is illustratively assumed to be responsive to the temperature of a space, it is to be understood that the thermostat can be responsive to any other desired controlling temperature condition. As far as the present invention is concerned, the thermostat I01 may be replaced by any controlling switch.

The pilot burner assembly is supplied with gas through a' pipe H5 connected to the inlet chamber of valve 95. Normally, the pilot burner is constantly burning. Figure 4 clearly shows the side walls of the burner I0 spaced from the cover I2 and also the top and bottom-of the cover to be open. This construction provides a passage for the flow of air through the device. The gas passing through nipple 31 and the Venturi throat formed by passages I9 and 20 draws with it primary air which is mixed with the gas in a conventional manner. It is to be noted that because the lower ends of the thermocouple elements extend below the casing II, this air passes over the cold junctions serving to cause cooling thereof.

The mixture of gas and air issues from openings 21 and from slit 23 to form flames 89, 90, and 9I. This discharge sets up an aspirating action which draws secondary air through the space between the burner and the cover and thus over the exposed thermocouple elements 60 and BI. vTherefore not only are the cold junctions B4 cooled by the primary air entering the Venturi throat I9 but they are also cooled by the secondary air which is drawn up through the burner casing to support combustion. Also, the incoming gas contributes to the cooling eflect. Thus, under normal circumstances, the thermoelectric unit generates a substantial electromotive force. The

amount of this electromotive force is materially increased by reason of the fact that the air and gas which serve to support combustion and increase the temperature of the 'hot junctions also serve to cool the cold junctions and hence increase the temperature diflerential between the hot and cold junctions.

Whenever the thermostat I01 calls for heat. that is, when the temperature to which the bimetallic element I08 drops sufliciently to cause closure of switch blade I09 against contact H0, an energizing circuit is established between terminals 99 and 91 as follows: from the thermoelectric 7 generating unit through conductor II1, bimetallic element I00, switch blade I03, contact Ill, conductor Ill, terminal 36, the electromagnetic unit of the pilot valve, terminal 01, and conductor 'IIO back to the generator unit. If the pilot burner is properly ignited, the generator unit serves to supply power to the electromagnetic unit to cause the pilot valve to move to such a position .that the gas in the pressure chamber bleeds 01! through pipe 93 and burner 03 permitting the diaphragm to move the main valve toopen position. Gas issuing from bleed burner 08 is ignited by the igniting iiames 90 and l Similarly, the gas supplied through pipe I03 to main burners I00 and IOI as a result of the opening of the main valve is likewise ignited by the igniting flames 00 and SI. The operation of main burners I00 and IN tends to increase the temperature differential between the hot junctions 52 and the cold junctions 64, as previously explained. This increase in difierential by reason of the operation of the mainbu'rner is not suflicient, however, to prevent the pilot valve from moving to valve closing position if the pilot burner is extinguished. It is desirable in normal applications that the main burner be extinguished if the pilot burner is at any time extinguished. Hence, if the pilot burner should be extinguished the electromotive force generated by the thermopile unit will drop to a lower value than that caused by the temperature differential produced by both the pilot burner and the main burner. This lower value is such that the electromagnetic pilot valve will not remain in the position in which the main valve is open but will move to its other position, interrupting the escape of gas through bleed pipe 93 and causing pressure to be applied to the main diaphragm chamber to cause closure of the main valve, and hence to interrupt the flow of gas to the main burners I00 and IN.

Under normal circumstances, however, the pilot burner remains ignited so the gas continues to flow to main burners I00 and IM until such time as the thermostat I01 is satisfied. When this happens, switch blade I 09 is moved out of Species of Figures 7, s and 9 In Figures 7, 8 and 9, I have provided asomewhat modified form of pilot burner and generator unit. In this modification, the burner and the means for supporting the thermocouples are combined in a single cast member I25. This casting comprises a base portion I21 of substan I tially square cross-section having a tubular stem portion I28 projecting upwardly therefrom and communicating with a horizontal tubular portion I29 provided with a plurality of burner openings I30. The'stem portion I and horizontal portion I29 form a T-shaped'burner unit. Secured tothe rectangular base portion I21 are a pair of spaced walls I33 and I34.

Referring first to the base portion I21 of square cross-section, this is provided with a cylindrical recess I36 which is threaded at its lower end to I30 and at its lower end with a threaded nipple.

I40 designed to be connected to a conduit for supplying gas to the burner. Two opposed openings I42 (only one 01! which is shown) extend through the walls or the cylindrical recess I36.

and serve for the introduction of primary air. The upper end of the cylindrical recess I38 connects through a conical passage I with a passage I45 in the stem portion I23. These passages serve as a mixing chamber for'gas and air. The stem portion I20, as best noted from a comparison of the dotted line shown in Figure 7 and the full-line showing in Figure 8, is of square cross-section. This passage I45 in turn communicates with a horizontal passage I46 extending through the horizontal tubular portion I29. The passage I46 in turn serves to supply gas to the plurality-of burner openings I30 spaced at uniform intervals along the tubular member I20.

The walls I33 and I34 are integrally secured to the base portion I21 and are integrally connected to the horizontal tubular portion I29 by connecting ribs I50 and iii. I34 are channeled to accommodate the various thermocouple members, as will be presently explained. As best seen in Figure 9, the walls are spaced from the burner to allow a freefiow of secondary air.

Located on top of the casting I25 is "a cagemember I56 of ceramic material. This cage member is provided with end walls I51 having openings I58 therethrough and side walls I60 and IBI. The cage member I56 serves to support the hot junctions of the thermocouples in proper spaced a relation with respect to the burner jet 30.

A plurality of thermocouple elements I10 andments I10 and "I are connected together to form a hotjunction I12. As with'the previously described species, a tube I13 of flame resistant material such as stainless steel is located around the elements I10 and III adjacent the hot junction I12. This stainless steel tube I13 serves to protect the thermoelectric element In from the corrosive, action of the flame.

The lower ends of the thermocouple elements I10 and [H are reduced in diameter to form relatively thin terminal portions I15 and I16. These thin terminal portions are connected together at their lower ends, as indicated by the reference numeral I11. The junctions I11 constitute the cold junctions of the thermoplle. By

reducing the material adjacent the cold junctions, it is possible for the cold junctionsv to be maintained at a lower temperature by the primary and secondary air and tocool ofi relatively quickly when the flame is extinguished.

The thermopile consisting of elements I10 and III is located over the casting I25 and the cage I56 of ceramic material with the horizontal uppermost portions of the elements I10 and I1I' The walls I33 and ing material are disposed on opposite sides oi the. legs of the thermocouple elements I and Ill and serve to insulate these elements from the main casting I25 and from the plates I" and I81. The casting liland the plates I" and I81 together with the'cage memberlll serve to securely hold the thermocouple members in assembled relationship.

. In order thoroughly to insure that .the flame issuing from jets ill! will not contact the thermocouple elements, a coating of ceramic material IIII is "applied to the thermocouple elements on each side 01 the sleeve I13, this coating joining with thesidewalls I" and lil of the cage I" of ceramic material and serving to completely enclose the portions of the thermocouple elements I10 and [H entering the stainless steel tubes I13.

It is believed that the operation oi the burner unit of Figures 7, 8, and 9 will be obvious from the preceding description. The gas entering through the jet I39 draws with it air through the primary air openings III. A mixture of the gas and air passes up through passages I and I and out through the burner openings IIII resulting in a series of flames for the full width of the burner unit. These flames are protected from extinguishment by the cage I56. The flames extend through the stainless steel tubes I13, heating these tubes and thus heating the hot junction I12. Unlike the arrangement 01' Figures 1 to 6, the same flames act to heat the hot junction and to ignite the main burner. As with the previous species, but to a slightly lesser extent, the incoming primary and secondary air cools the cold junctions I11. Because of the thermocouples being reduced adjacent the cold junctions, the thermal mass of the cold junctions is less and it is easier for the air to maintain them at a low temperature. 7

Due to the combined action of the ceramic cage I56 and the ceramic coating I80, the elements I10 and HI are thoroughly protected from the corrosive action of the flame.

In both of the modifications, the combined burner and thermoelectric generating unit is relatively compact and by reason of the relatively great resistance to transfer of heat between the hot and cold junctions, is capable of generating an electromotive force of substantial magnitude.

In general, while I have shown certain speciiic embodiments of my invention, it is to be understood that this is for purposes of illustration and that my invention is to be limited only by the scope of the appended claims.

I claim as my invention:

1. A combination electric generator and pilot burner device .comprising, a plurality of thermocouples electrically connected in series, a .pilot burner member having an elongated and relatively narrow slot at one end thereof for producing a thermocouple heating flame and having larger orifice means therein as igniter producin means, said burner having an opening/at the opposite end thereof for the admission of gas and primary air thereinto, sleeve members forprotecting the hot junction of the thermocouples, insulated casing means for insulating and supporting the thermocouples with one leg of each thermocouple on opposite sides of the said burner and with the hot junctions spaced from the pilot burner in a row extending parallel with said narrow pilot burner slot to be thus subjected to substantially the highest temperature produced by proper operation of U-shaped wire thermocouple members con-,

nected in series to form a thermopile, a metallic flame-protecting sleeve for the hot junction of each of said thermocouple members, the said not junction covering sleeve oi the said thermocouple members being bent to retain the sleeve members in their proper position and to form the curved portion of the U-shaped thermocouple members, insulated casing means for mounting the leg portions of the U-shaped series connected thermocouple members parallel with each other and with the hot and cold junction ends thereof extending beyond the said casing, gas burner means having a mixing chamber for mixing gas with primaryair, means for insulating the burner from the thermocouple members and for mounting the burner means within the said thermocouple casing means, supporting means including a bracket member for supporting the said casing together with the gas supply line for the burner and the connecting leads for the thermopile, the said supporting means surround bracket and said gas burner being disposed to induce a flow of secondary air to bathe said cold junctions and then flow along exposed portions of said thermocouples intermediate said burner and said casing and to induct a flow of primary air to bathe said coldjunctlons and then pass into the mixing chamber of said burner, and the said hot junctions and protecting sleeves extending beyond the casing and burner to a position in which they are subjected to substantially the highest temperature produced by the burner flame.

3. The combination comprising, a thermopile formed of a series of thermocouple units, each 01 said thermocouples comprising a U-shaped unit with the two leg portions" of dissimilar thermoelectric propertles and having the leg portions joined to form a hot junction, a sleeve member for protecting the said hot junction, the said leg portions and sleeve member being shaped to form the angular portion of said U-shaped unit, means including a cover member for insulating and sup porting the leg portions of the thermocouple units in a. row and for maintaining the respective legs and hot junctions in alignment with each other, the end portions of .each of the legs of said units being joined to the adjacent unit to thus connect the cold junctions of the units in series for com pleting the thermopile, a burner member located in the said casing and having a nozzle spaced from the said hot'junctions for the uniform heating of each oi said but junctions, the said burner forming a Venturi orifice at one end thereof, and a fuel supply line cooperating with said Venturi orifice and the orifice serving to provide for the flow of fuel and primary air to the said burner, means for securing said burner and cover members together in spaced relation so as to provide for a circulation of burner secondar air between the burner and cover, and the said cold junctions being extended from the said cover and burner to a position in the path of the flow of the primary and secondary'bumer air for maintaining a sub- I the pilot flame, and the said sleeve members supporting the cold junction stantially the full width of said burner, means near the upper ends oi said members to retain the central portions of the-upper ends in proper spaced relation, and a casin telescoped over said members in closely spaced, relation thereto whereby a secondary air passage is formed.

5. In combination, a burner comprising a pair members 01' sheet material, each of said members having tongues bent around the edge of the other member to retain them together, said members being flared inwardly and then outwardly at their lower ends, said members being superposed on each other whereby they collectively define a Venturi throat, and said members being so formed at their upper ends to form a narrow slit extending substantially the full width of said burner, means for maintaining said slit uniform throughout its entire length, a bracket to which said burner is attached,.and a sleeve of sheet material secured to said bracket and encasing said members, the side walls. of said sleeve and said members being spaced apart.

6. In combination, a burner block having a, central burner'portion and a pair of walls on opposite sides of the burner portion and spaced therefrom, a hollow member of ceramic material disposed on said walls, and a U-shaped thermocouple straddling said burner block and said ceramic member, the hot junction of said thermocouple being located in the bend of the U- shaped thermocouple and'the cold junction being near said means, and said bend resting on said hollow member with the hot junction in the path of the flame from said burner portion,

.7. In combination, a' burner block having a central T-shaped burner portion and a pair of walls on opposite sides of the burner portion and spaced therefrom, a hollow member of ceramic material disposed on said; walls, and a plurality ofv connected U-shaped' thermocouples straddling said burner block and said ceramic member, the hot junctions of said thermocouples being located in the bends thereof, and said bends resting on said hollow member with the hot junctions in the path or the flames from said burner portion.

8. In combination, a burner block having a central burner portion and a pair of walls on opposite sides of the, burner portion and spaced therefrom, a hollow member of ceramic material disposed on said walls, a plurality of connected U-shaped thermocouples straddling said burner block and said ceramic member, the hot junctions of said thermocouples being located in the bends thereof, and said bends resting on said hollow member with the hot junctions in the path of the flames from said burner portion, sleeves of non-corrosive material surrounding said hot junctions, and a covering of ceramic material molded around the ends of said sleeves. 9. In combination, a burner comprising a pair of members of sheet material each having a dis-.

charge aperture therein, means for securing said members together adjacent their edge with the central portions thereof spaced from each other,

said members being flared inwardly and then,

outwardly at their lower ends, said members being superposed on each other whereby they collectively define a Venturi throat, each of said members having a deep vertical groove communieating at one end with said throat and at the other end with said discharge aperture, the concave portions of said grooves facing each other so that said grooves collectively define a passage therebetween, the upper portions of said members being flared outwardly as to width and inwardly toward each other, and each of said members having an inwardly extending projection in said upper portion adapted to engage the other member to retain the central portions of the upper edges of said members in such spaced relation as to define a relatively long narrow slit extending substantially the full width of the upper portions or said members.

10. In combination, a combination pilot burner and thermopile unit, said pilot burner bein of the type burning a mixture of gas and primary air and having outlet means providing a runner flame for heating the hot junctions of said thermopile and for igniting a burner, said thermopile having leg portions sufliciently long to provide a substantial diflerence in temperature between thehot and cold junctions upon proper operation of the thermopile heating runner flame'oi the pilot burner, a cover comprising an open ended sheath encasing said pilot burner, the sidewalls of said sheath being spaced from the sidewalls of said pilot burner and providing means for directing a flow of secondar air therebetween when said pilot burner is in operation, means for supporting the thermopile in a position adjacent to and extending beyond the body portions of said pilot burner, said supporting means maintaining the legs associated with each hot junction in a position astride opposite sides of the pilot burner and also maintaining the hot junctions ina position spaced above the pilot burner to be responsive to substantially the highest temperature resulting from the proper operation of the thermopile heating flame of the pilot burner, the said extended leg portions having the cord junctions spaced from the burner, and means for directing a flow of primary and secondary burner air over said cold junctions to maintain -a substantial difierence in temperature between the cold and hot junctions of the ther mopile upon proper operation of the thermopile heating flame of the pilot burner.

ll. In combination,-a pilot burner and thermopile unit comprising a, relatively flat pilot burner unit with outlet means for producing a horizontal runner flame and a plurality of vertically extending thermocouple units spaced from said pilot burner with the hot junctions disposed in a horizontal straight line above said outlet means, said thermocouple units being relatively long as compared with the body portion of said pilot burner, an open ended cover telescoped over said thermocouple units and providing a shield for a portion thereof, said cover being spaced from the 13 current of air flowing therethrough burner.

12. In combination, a pilot burner and thermopile unit comprising a relatively flat burner with air and fuel inlet at one end and outlet means for producing a runner flame at the other end thereof, a plurality of vertically extending therto said P lot mocouple units spaced from said pilot bumerand having the hot junctions thereof disposed in a horizontal straight line above said flame opening, a shield telescoped over the intermediate portion of said thermocouples and providing a conduit for the passage of air between said burner and said shield, means for maintaining said shield and said burner in their spaced positions, and the cold junctions and intermediate portions of said thermocouples being disposed within said conduit to be afleoted by the passage of air therethrough.

13. In combination, a pilot burner and a thermopile unit comprising, a relatively thin burner with outlet means for producing a horizontal runner flame and a plurality of U-shaped thermocouples, said pilot burner and said U-shaDed thermocouples being disposed in spaced relation with the hot Junctions in alignment above said flame opening and the cold junctions and intermediate portions of each of said thermocouples on opposed sides of said relatively thin burner,

a cover positioned over the intermediate portions and a sleeve member for protecting the said hot junction, the said joined portion and sleeve being shaped to form the bend of said U-shaped unit, means including a cover member for insulating and supporting the units in spaced relation with the hot junctions in a single aligned row and the leg portions in two aligned rows, the ends of the legs of said units being joined to the end leg portions of adjacent.units to thus electrically connect the cold junctions for forming a thermopile, said burner being operably positioned within said assembled U-shaped thermocouple units, and

'means for maintaining said burner spaced from said insulating and supporting means.

15. The combination comprising, a U-shaped thermocouple unit, the two leg portions of said U- shaped unit having dissimilar thermoelectric properties and being joined to form a hot junction, a sleeve like member for protecting the said hot junction, the said leg portions adjacent the said hot junction of said unit and said sleeve member being shaped to form the bend of said U-shaped unit, a fuel supply line, a burner having a burner nozzle at one end thereof and a Venturi orifice at the other end thereof, said fuel line being disposed to direct fuel into said Venturi orifice andthereby induce a flow of primary air through said orifice and into said burner, and means for insulating and supporting the burner between the leg portions of said thermocouple unit with the hot junction spaced from the burner to receive the maximum heat from the flame produced by the 14 burner, the said supporting means maintaining the cold junctions of theunit spaced from the said burner and extending to a position in which they are subjected to the flow of primary air into said burner.

16. In combination a fuel burner having at one end thereof orifice means to produce an elongated flame and at the other end an inlet for the admission of fuel and air thereinto, and a thermopile comprising a plurality of hot junctions connected in alternate series with a plurality of cold junctions, said thermopile being positioned with said hot junctions spaced in a single row above said burner and in heat conducting relation with the burner flame and the said cold junctions being located in spaced parallel rows on opposite sides of said burner and adjacent said inlet, said hot junctions being positioned to span said elongated flame, supporting meansv for maintaining said thermopile and said burner in said spaced association, a cover member encasing a portion of said associated burner and thermopile and forming a secondary air passage therebetween and cooperating with said supporting means to provide an air passageway to said inlet and to said secondary air passage, and said cold junctions being positioned in said passageway.

17. In combination a fuel burner having an inlet and an orifice for the escape of fuel therefrom, and a thermopile comprising a plurality of hot junctions connected in alternate series with a plurality of cold junctions, said thermopile being positioned with said hot junctions aligned above and spaced from said orifice and in heat conducting relation with the flame of said burner and said cold junctions being divided, aligned and spaced from opposite lower sides of said burner,

means for maintaining said hot and cold junctions in their respective alignments and spaced from said burner, said maintaining means being spaced from said burner and cooperating therewith to provide passage means for the induction.

passage having an air inlet, a fuel supply means' spaced from and arranged to discharge fue1 into said passage for inducing the flow of air into said passage, a wall surrounding said burner and spaced therefrom, said wall in conjunction with said burner providing a second passage having an air inlet for the flow of air induced therethrough when the device is in operation, the air inlets of the first mentioned passage and said second passage being adjacent each other, a thermopile unithaving hot junction portions of inverted U-shape and positioned 'to provide aprotective cage over the flame issuing from the discharge portion of said burner and to be heated thereby, and cold junctions disposed in front of the air inlets to said passages.

19. In combination, a pilot burner having an air and fuel inlet at one end and an orifice at the other end thereof, a plurality of thermocouples each having two legs of thermoelectrically dissimilar material joined at one end to each other to form a hot junction and joined at their lower ends to other of said thermocouples to form cold junctions, and 'means for mounting said thermocouples-in spaced relationship with respect 15 to said burner with said hot Junctions above said orifice and with said legs extending downwardly on opposite sides of said burner, said means comprising a casing surrounding the burner and the intermediate portions of said thermocouples and with the lower end thereof terminating close to but spaced from said cold junctions and said air and Lie! inlet to provide a secondary air inlet and passage between said pilot burner and said means ior mounting said thermocouples.

20. An electric generator comprising a burner having an orifice at one end thereof and a primary air opening at the other end thereof, a thermocouple mounted thereon with its hot Junction substantially in alignment with said orifice and its legs extending substantially parallel to and in spaced relationship with the side of the burnerand with its cold Junction-in front of said anopening, a wall extending generally parallel with said burner with a portion oi! a leg of said thermocouple therebetween, said wall thus providing a secondary air passage between said wall and the side of the burner with one end of said wall terminating close to but spaced from said primary.

, air opening and said cold Junction so that air flowing into said primary air opening and said secondary air passage will pass over or adjacent to said cold junction.

HUBERT T. SPARROW.

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

Number Number UNITED STATES PATENTS Name Date Gulcher May 29, 1888 Muirhead Nov. 29, 1910 Bell May 25, 1915 Klelberg May 5, 1925 Fuller et al July 10, 1928 Anderson et a1. Feb. 19, 1929 Palmer Jan. 19, 1937 Wunch et al Feb. 13, 1940 Wetzel Apr. 30, 1940 Milnes Sept. 17, 1940 Ray Apr. 1, 1941 Mantz ..i Dec. 30, 1941 Ray July 14, 1942 Kliever Aug. 4, 1942 Ames Oct. 6, 1942 I Higley -1. Feb. 2, 1943 Alfery June 22, 1943 Ray Feb. 8, 1944 Mantz Mar. 27, 1945 Ray May 1, 1945 FOREIGN PATENTS Country Date Great Britain 1906 Austria June 25, 1910 Great Britain Jan. 31, 1924 Great Britain June 12, 1924

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