US2072552A - Ignition device - Google Patents

Description

March 2, 1937. GAUGER 2,072,552

IGNITION DEVICE Filed May 2, 1932 3 Sheets-Sheet 1 o 0 0 0 0 0 OUOUUUDUOUUUODUU 0 D March 2, 1937. A, GAUGER 2,072,552

IGNITION DEVICE Filed May 2, 1952 3 Sheets-Sheet 2 r i r 1 i y 4 0 52 5 41 52am F. A. GAUGER IGNITION DEVICE March 2, 1937.

Filed May 2, 1932 5 Sheets-Sheet 3 Patented Mar. 2, 1937 UNITED STATES PATENT OFFICE IGNITION DEVICE United States Application May 2, 1932, Serial No. 608,713

4 Claims.

This invention relates to ignition devices and has particularreference to an automatic oven lighter for gas stoves.

Gas ranges are now constructed with low ovens 5 in which the oven burner is disposed at an appreciable distance below the cooking top and hence considerably below the constantly burning pilot light which is to serve as the igniter for the oven burner in addition to the cooking top burners. 10 It has, therefore, been quite a problem to get a practical form of flash-back tube to insure quick and positive automatic lighting despite the remoteness of the ignition device with respect to the burner and the fact that the ignition device 15 is so far above the burner. I have found that the successful functioning of a long range flashback tube depends primarily on having the right proportion of gas to air, not allowing too much secondary air to mix with the gas admitted to 20 the tube by the auxiliary pilot, and it is the principal object of this invention to provide a flashback tube properly constructed to secure such a mixture, that is, a tube in which a balance is maintained between the secondary air and the 25 gas ilowing through the tube, whereby to secure good ignition and the proper rate of flame propagation from the main pilot back to the awnliary pilot.

Another important object of this invention is so to construct the tube so as to avoid collection of moisture therein between the main pilot and the auxiliary pilot when the latter is ignited. The presence of the moisture, which is due to condensation, interferes with a flash-back if it is 35 attempted to relight the oven burner shortly after the same has been in use and before the tube has had an opportunity to dry out. Ac-

cording to my invention, two solutions to this problem are ofiered, one being to provide a single walled tube so constructed that the same is heated sumciently throughout its length so that there are no low temperature areas at some distance from the flame of the auxiliary pilot where ooh- I densation can occur, and the other being to pro-- 45 vide a double walled tube in which the inner and hotter walled passage will serve for flame propagation and the outer passage as a conduit open to the atmosphere for any vapors resulting from 50 moisture in the tube.

Other objects and advantages of my invention will be brought out in the course of the following detailed description in which reference is made to the accompanying drawings, wherein- 55 Figure 1 is a view partly in front elevation and partly in vertical section through a gas range showing one embodiment of my invention, namely, the single walled tube;

Fig. 2 is a perspective view of the tube showing -its relation to the main pilot, the auxiliary pilot,

the oven burner, etc.

Fig. 3 is an enlargement of the lower portion of Fig. 2 showing the auxiliary pilot in vertical section and substantially full size;

Fig. i is a horizontal sectional detail through the upper front portion of Fig. 2;

Fig. 5 is a view partly in front elevation and partly in vertical section of the ilash tube;

Fig. 6 is a cross-section on the line 6-45 of Fig. 5;

Fig. 'lis aview similar to Fig. 5 but showing another embodiment of my invention, namely, the double walled tube;

Fig. t is a cross-section on the line 8-8 of lifig. 'i', and

Figs. 9, l0, and 11 are views similar to Fig. 8 but showing modified or alternative constructions.

Similar reference numerals are applied to corresponding parts throughout the views.

Referring to Figs. 1 to 3, the stove illustrated is of a low oven type, called a table-top range, having the usual cooking top it next to the oven section iii. The cooking top and the top of the oven section, it will be observed, are substantially at the same level, about table height. This accounts for the-low elevation of the oven burner appearing at M with respect to the pilot light casing it of the automatic lighter it disposed in the center of the cooking top between the burners i l. The lighter i6 is of a Well known type having flash-back tubes i8 radiating therefrom to conduct gas issuing from a port on any one of the cooking top burners to the lighter for ignition by the flame of the pilot burner id in the casing i5. The burner It, for the sake of convenience, will hereinafter be referred to as the main pilot, although any type or kind of igniting device may be used in place of this main pilot. The manifold it has cocks 2i thereon to supply gas to the various 5 cooking top burners, and the main pilot I!) has a tube 22 connected with the manifold for supply of gas therefrom.

An oven cock 23 also communicates with the manifold to deliver gas to the oven burner, usually through an oven regulator 24 connected between the oven cock and the pipe 25 communicating with the mixer 26 of the oven burner. The casting 21, asappears in Fig. 4, has a pipe 28 communicating with the oven cock to supply gas to the chamber 29 therein communicating with the inlet of the oven regulator 24, the outlet of which communicates with the other chamber 30 in the casting. The pipe extends from the chamber to the oven burner, thus making it' clear that the flow of gas to the oven burner is under control of the oven regulator. A tube 3| communicates with the chamber 29 in the casting 21 to supply gas to another pilot burner 32 for igniting the oven burner, thereby insuring a constant delivery of gas at uniform pressure to the burner 32 independent of any restriction by the oven regulator, so long as the oven cock 23 is open. The burner 32, for the sake of convenience and'in order to f distinguish from the main pilot l9, will hereinafter be referred to as the auxiliary pilot. It is also sometimes referred to as an intermediate burner for the reason that it is arranged to be automatically ignited similarly as one of the cooking top burners I1, and is in turn arranged to light the oven burner. In other words, the oven burner is not ignited by direct flash-back thereto through a tube like one of the cooking top burners but relies for its ignition upon the auxiliary pilot between the lighter l6 and the oven burner. The present invention, as stated before, has particular reference to the flash-back tube 33 disposed between the main pilot l9 and the auxiliary pilot 32 and arranged to ignite the latter from the former by flame propagation or flash-back through the tube.

The oven burner M has an extension 34 reaching through an opening in the side wall of the oven into proximity with the auxiliary pilot 32, whereby to have the gas issuing from the ports 35 in the bottom of the extension ignited by the flame from the laterally and upwardly extending port 36 of the auxiliary pilot. The flame is propagated from port to port along the extension 34 to ignite the gas issuing from the ports 31 in the bottom of the oven burner. Any suitable or preferred form of support may be provided for the auxiliary pilot 32 to insure its proper relation to the extension 34 of the oven burner; I have shown a T-connection 38 where the pipe 25 extends downwardly and then laterally for communication with the mixer 26 of the oven burner, and a pipe 39 is threaded into the T 38 at one end and at its other end into a blind hole 40 in the fitting 4| provided on the lower end of the auxiliary pilot 32, where the tube 3| has connection therewith. A mixer 42 is provided on the burner 32 extending upwardly from the fitting 4|, and a gas jet 43, threaded in the fitting, delivers gas under pressure through the mixer to the burner and causes primary air to be entrained therewith through holes 44 in the lower end of the mixer, whereby to produce a Bunsen flame. The air is regulated by adjustment of the sleeve valve 45 on the mixer. A combustible mixture of gas and air is therefore discharged upwardly through a central vertical port 46 in the top of the auxiliary pilot, in addition to the combustible mixture issuing from the port 36, previously men I tioned. The gas discharged from the port 46 is conducted through the tube 33 upwardly and then laterally to the main pilot |9 for ignition, whereupon, as we shall see later, a flash-back occurs through the tube to ignite the auxiliary pilot at its ports 36 and 46. A single port is shown at 46 because of the fact that the tube 33 used in connection therewith is of small diameter; if a larger tube is used, a cluster of ports should be provided instead of the single port. The tube 33 is supported at its lower end in a recess 41 in a collar 46 preferably formed integral therewith, as indicated by the web portions 49, the collar being at a predetermined elevation above the auxiliary pilot so as not to allow any more secondary air to mix with the gas entering the lower or inlet end of the tube 33 than is necessary to support combustion. While I have shown a fixed spacing between the lower end of the tube and the auxiliary pilot, it should be understood that the lower or inlet end of the tube might be made adjustable toward and away from the auxiliary pilot, if desired. In passing, it will be seen that a safety pilot valve 50 is provided in the pipe 25 for shutting off the gas to the oven burner in the event the auxiliary pilot is extinguished and fails to relight, due, for example, to a temporary lapse in the delivery of gas to the manifold 20. Any suitable or preferred form of safety pilot valve could be provided; the one shown has a bimetallic thermostatic element 5| to which heat is conducted by the member 52 disposed adjacent the flame of the auxiliary pilot. The valve is shown closed due to the parts 5| and 52 being cold. However,-

when the auxiliary pilot is ignited, the parts 5| and 52 are heated and the valve is snapped open, thus allowing gas to flow to the oven burner. In other words, there is no danger of gas being discharged from the oven burner without having a pilot light to ignite the same, and the oven cannot become filled with gas prior to ignition of the auxiliary pilot.

Referring now to Fig. 5 for a discussion of the novel features embodied in the flash-back tube 33, it will be seen that cuts are made in the wall of the tube on diametrically opposite sides at points 53 uniformly spaced lengthwise of the tube, the cuts on one side being approximately midway between cuts on the opposite side and all of approximately the same depth, and that a portion of the wall below each cut is pressed in or indented parallel with the opposite wall of the tube, whereby to provide air injector openings 55, and also make the passage 56 through the tube of sinuous or zigzag form. The purpose of thus forming the tube is to secure balanced aeration, namely to supply the necessary secondary air in such ratio to the gas by entrainment as it travels up to the main pilot l9, to secure good ignition at the main pilot, and then the correct rate of flame propagation back to the auxiliary pilot 32 in relation to the rate of charging, so that the auxiliary pilot will not only be sure of ignition, but the ignition will not be delayed. In other words, the secondary air taken in through the injector openings 55 insures a proper balance between the gas delivered from the auxiliary pilot 32 and the air mixed therewith in the tube, to secure immediate ignition and prompt flash-back from the main pilot to the auxiliary pilot. I have found that it takes very little time for lighting the auxiliary pilot after the gas has been turned on, the flash-back being practically instantaneous. Another reason for thus forming the tube is the fact that I have found that the walls of a plain tube tend to collect moisture thereon at some distance from the flame of the auxiliary pilot due to the same being at lower temperature. That is, the first flash-back is secured instantaneously but after the auxiliary pilot has been burning for some time, long enough to get the tube heated, condensation forms therein between the auxiliary pilot and the main pilot, and if the oven burner is shut off for a short time and it is desired to again light the oven burner, before the flash tube 33 has had an opportunity to dry out,

iii

the flash-back to the auxiliary pilot is rendered uncertain due to vapors in the tube caused by the condensation, the vapors rendering the mixture of gas and air in the tube non-combustible and preventing enough secondary air from entering the tube to support combustion for a flashback. By making the passage through the tube of sinuous or zigzag form, the products of combustion from the burner are caused to impinge the entire inside surface of the tube from end to end to heat the same sufiiciently to prevent condensation. As, a matter of fact, the particular formation of the tube results in not only a sinuous or, zigzag passage but a restricted passage as well, so that there is more definite assurance of the hot products of combustion transferring heat to the walls of the tube. There being no condensation in the tube, there is no difficulty in relighting. It is also thought that the baffling effect secured by the indented portions slows up somewhat the gasflow upwardly in the vertical portion of the tube in the charging thereof so that the flame will propagate downwardly and ignite the auxiliary pilot. It is also believed the bafliing effect minimizes the difiiculties in so far as a stack effect in the vertical portion of the tube is concerned. It is, of course, impossible to state with absolute certainty that the theory of operation as above described is correct but my observation of the results secured with variously formed tubes leads me to believe that the theory stated is correct. At any rate, the construction illustrated and described is thoroughly practical and gives the results described.

In Fig. 7, I have shown a double walled flashback tube 33 in which the vertical span 51 has a partition 58 therein extending preferably the full length thereof, the horizontal span 59, however, being left clear. The partition 58, as appears in Fig. 8, is of square or rectangular form and has a press lit in the tube thus providing a? central restricted passage 60 and surrounding passages 6|. A series of equally spaced openings 62 are provided along one side of the vertical span ill of the tube 33 and along the bottom of the horizontal span 59 for the purpose of admitting secondary air into the tube. Another series of holes 63 is provided in equally spaced relation lengthwise of the partition 58 on the same side as the hole 62 whereby to admit secondary air from the passage (ii to the passage Ell to maintain a properly balanced proportion of gas and air in the passage 60 for good flash-back from the main pilot to the auxiliary pilot. The initial lighting of the auxiliary pilot, with a flash tube of this construction, is quick and positive, the flame being propagated readily through the inner passage 50 by reason of the correct proportioning of gas and air in said passage due to the atmospheric openings 62 and 63. So far as any difficulty with moisture collecting in the tube is concerned, the construction illustrated is free from those difficulties because of the fact that the inner passage being so restricted is sure to have the walls thereof heated enough to avoid condensation thereon. If there should happen to be any moisture in the passage Bl, it is not apt to interfere with the formation of a good mixture in the passage 60, due to the fact that the openings 62 are so large as to insure a good supply of secondary air to the passage 6| under any ordinary circumstances and there is, therefore, every assurance of the proper amount of secondary air getting into the passage 60 because of the smaller holes 63. Any moisture in the passage 6l is cleared out when the flash-back occurs, due to the sudden pressure created in the passage 60. Furthermore, the construction is such that the inner walls forming the passage 60 are insulated more or less because of the space between those walls and the outside wall of the tube, thus making outside temperatures of little or no effect in so far as causing collection of moisture is concerned. Here again it should be understood that while the theory of operation,

as above stated, appears to be correct judging.

from nny observations of the performance of tubes of different constructions, it should be clear that it is impossible to state with any real certainty that the theory outlined correctly outlines the operation secured.

Substantially the same operation is secured irrespective of the way in which the passages 6U and BI are provided. Thus, Fig. 9 shows a partition- 58 between the passages 6|) and 6|; Fig. 10 shows a tubular partition 58* with radial ribs 64 whereby to separate a passage 60 from another passage Gi and Fig. 11 shows a substantially elliptical tube partition 58 separating passage 6|] from passage iii. In each case it will be noted that holes 62 and B3 are provided for admitting secondary air to the outer and inner passages, respectively.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn so as to cover all legitimate modifications and adaptations.

I claim:

1. In combination, a high igniter, a low burner to be ignited thereby, a flash-back tube disposed with its lower end over the burner and its upper end adjacent the igniter, said tube having portions of the opposite side walls thereof indented to provide inwardly projecting portions in staggered relation on opposite sides of the tube whereby to deflect products of combustion flowing upwardly through the tube .from the burner into a zigzag course for good heat transferring contact with the walls of the tube, the upper ends of the indented portions being formed so as to provide secondary air inlet openings between the indented portions and the adjacent walls of the tube, said tube being arranged to be charged with a mixture of fuel and air.

2. In combination, a first burner at higher elevation, a second burner at lower elevation to be ignited thereby, and a flash-back tube disposed with its lower end over the second burner and its upper end adjacent the first burner, said tube having air injectors thereon at points spaced lengthwise thereof for injection of secondaryair into said tube with gas or products of combustion flowing upwardly through the tube, said injectors forming restrictions in the tube whereby to afford a restricted passage through the tube for conducting products of combustion from the second burner, said tube being arranged to be charged with a combustible gas.

3. In combination, a high elevation igniter, a low elevation burner to be ignited thereby, a flash-back tube disposed with its lower end over the burner and its upper end adjacent the igniter, and air injectors provided on said tube at points spaced lengthwise thereof adapted to inject air into the tube upon flow upwardly therethrough, said injectors being constructed whereby to cause flow in a zigzag course upwardly through the tube, said tube being arranged to be charged with a combustible gas.

4. In combination, a high elevation igniter, a. low elevation burner to be ignited thereby, and a flash-back tube disposed with its lower end over the burner and its upper end adjacent the igniter, said tube having portions 01' the walls thereof bent inwardly to form air injectors for entrainment of air into the tube when flow occurs upwardly therethrough, the said injectors being so formed and related to direct upward flow through the tube in a zigzag course, said tube being arranged to be charged with a combustibie gas.

FRANK A. GAUGER.

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