US2235468A - Oil burner igniting mechanism - Google Patents

Description

March 18, 1941.

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, Filed June 21, 1938 P'Ig'-1 5 Sheets-Sheet 1 March 18, 1941. v D L 2,235,468

OIL BURNER IGNITING MECHANISM Filed June 21, 1938 5 Sheets-Sheet 2 Mauwq He ne ()6. Fdad'a'e,

R. M. VIDALIE OIL BURNER IGNITING' MECHANISM March 18, 1941.

5 Sheets-Sheet 3 Filed, June 21, 1938 Mmfi ih 51 JZene M. yakiala'a,

A A v E ow March 18, 1941. R. M. VIDALIE 61L BURNER IGNITING MECHANISM Filed June 21, 1938 5 Shets-Sheet 4 a m i m w m o2 MW a, W x i m A NE q /M lAx M 5 g 3. T g h March 18, 1941. Q R D L E 2,235,468

OIL BURNER IGNITING MECHANISM Filed June 21, 1938 v 5 Sheets-Sheet S Ammonia,

i atented Mar. 18, 1941 UNITED STATES- OIL BURNER IGNITFNG MECHANISM Rene M. Vidalie, Port Washington, N. Y., assignor to Preferred Utilities Company, Inc., New York, N. Y., a corporation of Delaware Application June 21, 1938, Serial No. 215,007

21 Claims.

This invention relates to ignition mechanism for oil burners and has particular reference to rotary type burners wherein oil is discharged from a fuel tube fixedly positioned within a rotating oil cup and centrifuged into a swirling current of air to form a combustible mixture. It is applicable to the air turbine driven type rotary burner as well as 'to the horizontal and vertical motor driven types of rotary burner.

For domestic purposes the so-called gun type burner has hitherto been used very extensively. The ignition associated with this type of burner, wherein oil is supplied to a nozzle at high pressure and atomized as it is discharged therefrom, air being supplied around the spray through a blast tube from a blower, is obtained from a high tension spark.

The rotary type of burner possesses many inherent advantages suiting it to use for domestic purposes by reason of its low cost of manufacture, efliciency of combustion, and the fact that its fire may be varied within a large range without change of parts simply by simultaneous positioning of the air and oil valves. This produces a 25 flexibility unobtainable with the gun type burner and permits what may be regarded as modulating flame control, a very important feature when considering the ultimate burner control whereby the fire is controlled directly and instantly by the 30 load as distinguished from the very severe and ineflicient on and off operation.

A further advantage in the rotary burner resides in the fact that it can be 'emciently operated at a relatively low rate of combustion, being capable of sustaining a fire on approximately one quart of oil per hour as compared with from three quarts to one gallon of oil per hour necessary for the gun type.

High tension spark ignition has not proved suitable foroil burners of the rotary type and an object of this invention is to provide efllcient automatic electric ignition for a rotary burner, automatically operable to provide reliable and safe ignition imder all circumstances.

struct and arrange the ignition mechanism in association with the rotary type burner that no heavy carbon deposit forms in the oil cup after the repeated firing and dousing of the burner that is essential for satisfactory domestic use. Service cost, upkeep, and incidental annoyances to the domestic user are thereby eliminated and the rotary type of burner with its attendant eillciency and flexibilityis available in a field wherein it has been hitherto relatively unknown.

Another object of the invention is to so con-- A distinct advantage in my improved ignition mechanism resides in the fact that it functions without creating radio interference, which is sometimes very troublesome with high tension spark ignition and becomes especially so with the appearance of extra-sensitive sets for short wave lengths and television.

An important feature of the invention resides in the particular method whereby the above specifled advantages, together with others hereinafter to be brought out, are obtained. Elimination of dangerous explosions as well as promptness and reliability in performing the ignition function are obtained by first heating the oil rendered available through the discharge opening in the fuel tube to a temperature above the flash point of the oil, thereby vaporizing the same, and subsequently igniting the vapor so formed through the same heating element which created the vaporization. For this purpose it is of course necessary to locate the heat source, here shown in the form of an electrical resistance element, near the discharge opening in the fuel feed tube and so asso-- clate it with the surrounding mechanism that the heat radiated thereby may be used for the g5 purpose of initially vaporizing the oil.

To this end I have provided an electric circuit including a resistance coil positioned within the oil cup on the discharge side of the fuel feed tube opening. The heat from the resistance coil is absorbed by the walls of the oil cup to thereby vaporize the oil fed thereinto through the fuel tube discharge opening. The vaporsso formed within the oil cup are ignited by direct contact with the resistance element, and air is supplied in the usual manner to maintain combustion.

Performance of this method is considerably facilitated under certain circumstances when the oil cup itself is shielded or insulated from the blast of air customarily surrounding the same. For this purpose I have provided an insulating sleeve surrounding the oil cup and protecting the same from the air blast. In this manner the time required to bring the oil cup up to a temperature above the flash point of the oil is considerably reduced and ignition obtained more quickly, particularly where the oil is turned on after previously starting both the ignition and air blast.

Among other objects of the invention are to so arrange the discharge opening in the fuel feed 5 tube as to preclude the possibility of oil seeping or drooling along the fuel tube, in either direction, when the oil supply is shut off. This aids materially in preventing the formation of carbon or soot on the walls of the oil cup. ll

Various other objects and meritoriom features of the invention will become apparmt from the following description taken in conjunction with the drawings. wherein like numerals refer to lih parts throughout the severalflgurea, and whu'ein:

Figure 1 isasidedevatirlnjmkenawayandin section, of the front end of a tylical installation:

Fig.2 isaftarysectionthrough theoil feed head at therearoftheburner;

Fig.3isasectionalview'similartorig. lillustrating a modified form of structure; I

Fig.4is asecfionthrmlghtheollfeedhead the modified formillustratedin Fig. 3;

Figfiisanmlargedpartiallysectionalview of my improved resistance coil assembly;

Figfiisasomewhatvlewofthe improved. ignition asociated with a rotary burner of the vertical type; I

Fig. 'l'isasectionillustratlngasomewhatmodifled form of coil igniter; 4

Fig. 8 is asectlonalviewWimproved ignition associated with an air turbine driven rotary burner, and

Fig.9 isatlcillustrationofaoonventional program relay circuit for relative timing of the motor, ignition element, and oil feed operations.

Referring now to Figs- 1 and 2 of the drawings, the numeral ll representstheoutereasing ofa rotary oil burner of the horizontal type in which the motor I! is provided with a hollow armature shaft It through which the MI feed tube II extends. The fuel feed tube is fixedly positioned by the oil feed head I! and is preferably welded thereto as at 22. Theheadisboltedas at II to the rear of the motor casing.

Hubmember uisboltedtotheflontendof motor shaft l4 and is provided with a flange I towhich lssecured,asbymeans ofrlvets 28 or otherwise, fan member II. A easing cover 32 is secured to the open face of the casing II, which cover includes a diaphragmportion 34 which functionsas abafllein directingtheforcedairarolmd the oil cup and through the burner mouth.

In the preferred form illustratedin Figs. 1 and 2 the oil cup is so formed as to provide an annular dead air space surrounding it, thereby insulating the inside wall of the cup from the secondary air blast passing around it when the motor is in operation- The cup eomprims an inner tapered member 36, which is preferably of high grade bronze having a low specific heat, provided with annular flanges 38 and ll at each end. A cylindrical tube 2, which is preferably stainless steel having a low heat conductivity, is press-fitted over the flanges 3i and ii and bolted to hub member 24 as indicated at r It is immaterial howtapered insert or cup iiis flxed in the surrounding tube 2, the important feature being the formation of a dead air space the cup 36 and completely sealed fromingress of moisture andair. The annularflanges 3| andllmaybe received in a press fit by outer tube II, or possibly welded thereto, to perform this flmction in the arrangement illustrated.

. tip it, more fully illustrated in Fig. 5.

head by an annular insulating member 54. Electrode rod ll extends through the fuel feed tube and is supported at its forward end by means hereafter described. One end of resistance coil I is connected to the forward end of rod 48 and its other end is connected, directly or indirectly, to the fuel feed tube. The fuel feed tube provides a return circuit from the resistance coil, which circuit is grounded through the motor casing by the contact indicated at it.

Howofoil through passage 60 inthe oil feed head may be controlled by a valve operating member 62. It lstobe noted that the central electrode rod 48 projects beyond the end of the fuel feed tube and extends substantially to the discharge end of the oil cup. The annular passage within the fuel tube surrounding the electrode rod, through which the oil supply flows, is closed just beyond the discharge opening $4 and the forward end of said rod is supported by means of fuel tube Central electrode 48 is preferably of nickel wir and should be a fairly good conductor, substantially impervious to corromon from fuel oil fumes containing small wants of sulphur, and. heat resisting to a substantial extent. The aforesaid fuel tube tip 66 may comprise a metallic or conducting tube 8 having an annular lip portion ll pres-fitted into a corresponding annular lip I2 formed at the extremity of fuel feed tube It. For integrating and rigidifying purposes bead ll ex tending around the wall of the tube and abutting liplimaybeweldedorbrazedto thesaidlipas indicated at 13. An opening I5 is provided on the upper side of tube it for discharge of the fuel into the oil cup and annular beads 18 and II adjoin this opening on each side thereof. Beads ll, I8, and ll function to prevent oil dripping or drooling back along the tube toward the motor shaft or into the oil cup and, by placing opening It on the upper side, accumulation of oil in the cup during the shut-oil period is substantially The forward end of tube 68 is provided with an annular flange 8 I which performs the same function in preventing seepage as beads 14, etc., and which includes a socket member 82 adapted to receive therein one extremity of resistance coil 55, which is preferably welded therein as indicated at CI. The other end of the resistance coil is inserted in a socket 85 provided in the end of central electrode ll and is likewise preferably welded therein as indicated at it. A centrally apertured disc ll of ceramic material which is insulating and heat resisting is inserted into the end of tube 68 and around electrode rod 48 on the forward side of discharge opening 18. This disc is cemented in as indicated at it with material which is also insulating and heat resisting, thereby securely sealing the end of the tube beyond the discharge opening thereof, supporting electrode rod II with in the fuel feed tube, and insulating the one from the other.

A somewhat modified form of structure is illustrated in Figs. 3 and 4 wherein a second tube 92 surrounds fuel feed tube It and is insulated therefrom by suitable means, such as a mica tube 94. In this modification the fuel feed tube itself constitutes the lead electrode and surrounding tube S2 is the electrode providing for the return circuit which is grounded through the burner casing by contact with the oil feed head as indicated at it. Contact member 98 surrounds the fuel feed tube to provide a lead-in from some suitable source of electricity, said contact memher being insulated from component parts I and I02, of the oil feed head by annular insulating members I64 and I06. The entire assembly may be securedtogether by means of bolts I08 which are insulated from contact member 98 by means of insulating sleeves, not shown.

The forward end of tube 82 is broken away on its under side as indicated at I I0 somewhat short of its extremity to permit free flow of oil through discharge opening 2 in the end of the fuel feed tube. In this particular modification the discharge opening is directed downwardly. Tube 92 terminates at substantially the end of fuel feed tube I6 and rod H4 is press-fitted and welded in the open end of the fuel tube to seal the said tube on the discharge side of opening II2. One end of resistance coil 56 issecured to the end of rod H4 and the other is inserted in a socket II6 formed in any suitable manner'at the forward extremity of electrode tube 92.

Thus the circuit to the resistance coil is provided through the fuel tube itself and retumed through electrode tube 92-, being grounded through the contact of the latter with the oil feed head at the rear of the burner, this circuit being substantially the same as the circuit in the preferred form hitherto described.

Oil cup H8 is press-fitted over a lip I20 of fan hub I22, which latter is secured to the hollow armature shaft I4 of the motor in any suitable fashion. An annular flange I24 abuts against the end of this lip to limit the telescoping movement of the oil cup thereover, as does shoulder I25 of the hub.

A somewhat modified form of insulating sleeve is herein illustrated, the sleeve I26 being welded v as indicated at I28 to the flared annular extremity of diaphragm member 34, which constitutes an integral part of easing cover 32. The sleeve is spaced from the wall of oil cup I I 8 to thereby provide an air spaceimmediately surrounding the same, but the air space is not closed as in the preferred form of structure. Nevertheless, this insulating sleeve shields the oil cup from the air blast from the fan, thereby facilitating heating of the oil cup wall.

In Fig. 6 I have illustrated in somewhat diagrammatic form the application of the hitherto described ignition mechanism to a rotary oil burner of the. vertical type. As clearly indicated therein, a central electrode I30 extends through fuel tube I32, which fuel tube functions as the grounded electrode. Rod I30-is insulated as indicated at I84 from the oil feed head I86 supplied through tube I38. The electrode rod I30 projects through and beyond the closed end of the fuel tube and one end of resistance coil I40 is connected to the end thereof and its other end is connected to fuel tube m m a manner hitherto described. This installation as illustrated does not include an insulating sleeve surrounding the oil cup I42,

' the walls of which are preferably more tapered than the oil cup used in the horizontal type burner so that proper centrifuging of the oil is ob-' tained. The insulating sleeve is not essential to successful performance of my improved method of igniting a rotary oil burner, although it is distinctly advantageous and desirable where, as aforesaid, the ignition and air blast are started simultaneously.

Fig. 7- illustrates a modified form of resistance coil which has proven distinctly advantageous in .that it positively prevents the coil from sagging and provides a better insulation between the inside electrode and outside coil where it enters the fuel tube tip 66 and where the difference in potentIal is the highest. One end of resistance coil I44 is inserted in a socket provided in the end of coil portion of the resistance element is wound.

The other end of the coil is secured in a socket I52 provided in the fuel tube tip hitherto described. It is to be noted that core I50 extends into the end of the fuel tube tip but terminates short of the oil discharge opening. A seal I54 of oil-proof and heat-proof cement abuts the end of core I50 and seals the annular discharge portion of the fuel tube on the discharge side of the opening therein.

The composite oil cup is so constructed and arranged in this modification as to provide an annular dead air space surrounding the inner wall of the cup, as hitherto described. The tapered inner member I56 and straight tubular insulating sleeve I58 are secured by means of a series of single rivets I60 to an annular shoulder I62 projecting from the fan hub I64. The thickness of this annular shoulder and the taper of member I56 are such that sleeve I58 and member I56 are held in abutting relation at the extremity of the composite cup, thereby creating a dead air 'insulating space about the inner wall thereof. The abutting ends of member I 56 and insulating sleeve I58 may be positively sealed, if

desired, in any suitable manner.

within casing I68. A rotor I is fixedly secured to shaft I66 and is rotated by an air blast forced through passage I12 and issuing through nozzle I14 surrounding the rotating oil cup after it has passed the rotor. The composite insulated oil cup I16 is the same as that illustrated in Fig. 7 and described above. Electrode rod I18 extends coaxially through fuel tube I80 in a manner hitherto described, oil flow being controlled from fuel feed head I82. The fuel tube tip I84 and the resistance coil I86 herein illustrated are like those illustrated in Fig. 7 and hitherto described.

The current is preferably supplied by a constant output transformer that gives the same output regardless of primary, voltage variations. The secondary current may be about two volts and between fifty and seventy-five amperes, which presents no insulation difilculties throughout the ignition circuit because of the low voltage. program relay of the conventional type may be arranged for controlling the circuit to the motor, the resistance coil and oil feed in timed relation to one another. The entire fuel feed assembly, including the ignition mechanism, may be removed by unbolting the oil feed head and withdrawing the tube assembly through the hollow motor shaft, r

The numeral I92 represents a standard thermostat control, hereafter referred to as the. thermostat, which includes a main boiler switch and a thermostat switch, not shown. This unit isc'ustomarily placed in the smoke pipe of the furnace where it is most susceptible to effective changes in temperature. The unit is one of several standard manufactured products designed for this particular use.

When predetermined temperature conditions are present the thermostat unit operates to simultaneously close a circuit from main line I88 through I98 and thence out of the unit through leads I94 and 2. A thermostat switch operating transformer in the thermostat unit is grounded to ground wire I88 through lead 228.

Lead I84 feeds a program motor through branch I98, the curernt passing out through lead 284 to lead 2I2 which extends back to ground wire I88. The program motor, which is one of many possible standard products available for closing a circuit in timed relation, includes a rotor 288 carrying a cam 282 which is operable on continued rotation of the said rotor to actuate switch arm I96 to thereby make contact with lead 286 extending to oil feed control actuating means 288 and to the motor 2I8, preferably positioned in a housing indicated by the numeral 222. The circuit through these two units is carried through lead 2I2 back to ground wire I88.

Lead 2I4 extending from the thermostat unit I92 energizes the primary coil of a transformer 2"; and is grounded through 2I2 to ground wire I88. The secondary of the transformer feeds ignitionresistance coil 56 through lead '2 I8 which is coupled with the electrode rod 48, the return being through the tube I8 which is grounded as indicated at 58 in Figs. 2 and 9, at which point the other end of the secondary coil of the transformer 2 I 6 is likewise grounded. The oil feed tube I6 may be grounded elsewhere if desired, as in dicated diagrammatically.

From the foregoing it will be apparent that, when leads 2 and I94 are energized simultaneously through thermostat unit I92, the resistance coil 56 is immediately included in circuit and begins to heat the wall of oil cup 36. Simultaneously the rotor 288 of the program motor fed by lead I94 begins to turn. The speed of the rotor is so timed that cam 282 functions to close the circuit through I98 and 288 after approximately sixty seconds, at which time the circuit through oil feed control 288 and the motor 218 is completed. In this way the wall of the rotary oil cup may be heated above the flash temperature of the oil prior to depositing oil thereon and prior to forcing air through the duct surrounding the same. This is an effective means for excluding from contact with the wall of cup 35 any substantial amount of air tending to cool the same during the period of preheating by means of resistance coil 56.

There are two satisfactory cycles for obtaining ignition by my improved method and mechanism. Each has its attendant advantages. The circuit through the igniting resistance coil may first be started, and after a preheating period the circuit to the motor creating the air supply is closed and the oil supply line opened. This particular cycle of operation requires a shorter period of pre-ignition than that described later. When the ignition circuit is closed the resistance coil is heated to about 2008 F. and the radiant heat therefrom is absorbed by the walls of the atomizing cup. When the oil is turned on vapors are formed in the cup because the temperature of the walls is above the flash point of the oil, and these vapors are ignited by direct contact with the resistance coil positioned within the cup. Air for maintaining combustion after igniting the vapor is available simultaneously, the circuit to the motor having been closed when the oil line was opened. With this particular cycle of operation the insulating sleeve surrounding the oil cup is not so particularly desirable because the air blast is not turned on until the walls of the oil cup have been brought up to a temperature above the flash point of the oil. There has therefore been no cooling blast around the oil cup during the preheating stage. It is for this reason that this particular cycle of operation provides the most rapid ignition. Eliminating the air blast during the period when the cup is heating is perhaps a more effective means than a. sleeve for excluding from contact with the wall of the cup any substantial amount of air tending to cool the same.

The other cycle involves starting the ignition by closing the circuit through the resistance coil and simultaneously starting the air blast by closing the motor circuit. The Oh line is then opened after the oil cup has been heated to a temperature above the flash point of the oil. This cycle is particularly advantageous because, although it requires a longer pre-ignition period, the inside of the cup is maintained free and clear of undesirable soot and carbon which might otherwise become deposited on the walls. When the motor and ignition are started together prior to supplying oil to the cup, rotation of the cup purges it of any oil accumulated during the shutoflf period and no carbon forms on the walls. A longer pre-ignitionperiod is required, however, because the air blast from the fan begins with rotation of the oil cup and its cooling effect lengthens the time required to heat the wall of the oil cup to a temperature above the flash point of the oil. The difference in time is not great where the insulating sleeve shields the cup from the air blast. After the cup has reached the desired temperature, which may require an approximate maximum of sixty seconds elapsed time, the oil valve is opened and ignition takes place in the same manner as hitherto described. Thus the delay in providing the oil feed permits the oil cup to purge itself and provides time for heating the wall thereof to the desired temperature by means of the radiant heat from the resistance coil positioned within the cup.

It will of course be understood that the ignition circuit is opened automatically by the program relay after ignition has been completed.

It is to be noted that where the discharge opening of the fuel tube is at the top, the fuel tube is always full when the oil is shut off, there is no dripping or drooling while the burner is idle, and fuel is available at the cup as soon as the oil valve opens. The beads surrounding the tip of the fuel feed tube, tube 88 illustrated in Fig. 5, prevent all from running along the tube toward the heating lement or toward the hollow motor shaft. 7

In all of the forms illustrated the same method of ignition occurs. The wall of the oil cup is preheated by radiant heat from resistance coil to a temperature such thatoil introduced into the cup will flash and the vapors formed ignite on contact with the resistance coil, air being provided by the blast issuing through the mouth of a rotary cup which comprises the steps of preheating the wall of said cup to a temperature above the fiash,point of the oil by radiation from a heat source so positioned with reference to the rotary cup surrounded by a forced air duct which comprises the steps of preheating the wall of said cup, while excluding any substantial amount of air tending to cool the same from contact therewith, to a temperature above the flash point of the oil by radiation from a heat source so positioned with reference to thewall thereof as to preclude contact between the heat source and the wall, and thereafter depositing oil upon the wall of the cup without contacting said ofl with the heat source to thereby successively vaporize the oil by contact with the preheated wall and subsequently ignite the vapor so formed by contact with said heat source.

3. Ignition mechanism for a rotary oil burner comprising a rotatable oil cup, heating means arranged to heat solely by radiation the inside of the wall of said cup to vaporize oil when deposited thereon, said heating means including an element capable of radiating suilicient heat to raise the inside of the cup wall to a temperature above the flash point of the oil and so positioned as to contact the vapor so formed to ignite the same, and means for depositing oil inside 1 said cup on the wall thereof.

4. Ignition mechanism for a rotary oil burner comprising a rotatable oil cup, an air passage surrounding the same, means for passing air therethrough, means for excluding from contact with the wall of said cup any substantial amount of air tending to cool the same, means for depositing oil inside said cup on the wall thereof, and a heating element so positioned relative to said cup as to heat the inside of the wall'thereof to thereby vaporize the oil deposited thereon and contact the vapor so formed to ignite the same.

5. Ignition mechanism for a rotary oil burner comprising a rotatable oil cup insulated exteriorly against heat losses, means for depositing oil inside said cup on the wall thereof, and a heating element so positioned relative to said cup as to heat the inside of the wall thereof to thereby vaporize the oil deposited thereon and contact the vapor so formed to ignite the same.

6. Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube opening into said cup and comprising a heating element positioned within the cup on the discharge side of said fuel tube opening, and a heat insulating sleeve surrounding said cup.

'I. Ignition mechanism for a rotary oil burner including'a rotary oil cup, a fuel tube opening into said cup, and a forced air duct surrounding the cup, and comprising a heating element positioned within the cup on the discharge side of said fuel tube opening, and means surrounding said cup to shield the same from the air in said duct. a i 'l"? 8. Ignition mechanism for a rotary oil burner including a rotatable oil cup comprising a fuel feed tube opening into said cup and constituting one electrode of an electric circuit, a second electrode spaced therefrom projecting into the oil cup, a resistance coil positioned within the oil cup on the discharge side of the opening in said fuel feed tube connecting the two electrodes, and a heat insulating sleeve. surrounding said oil cup. 9. Ignition mechanism for a rotary oil burner including a rotatable oil cup comprising a fuel feed tube opening into said cup and constituting A one electrode of an electric circuit, a second electrode spaced therefrom projecting into the oil cup, a resistance coil positioned within the oil cup on the discharge side of the opening in said fuel feed tube connecting the two electrodes, and an, insulating I sleeve surrounding said oil cup in spaced relation thereto, said sleeve being so constructed and arranged with reference to said cup as to form an annular dead air space surrounding the same.

10. Ignition mechanism for a rotary oil burner including a rotatable oil cup comprising a fuel tube opening into said cup and constituting one electrode of an electric circuit, a tube electrically insulated from and surrounding said fuel tube extending into said oil cup and constituting a second electrode, a resistance c'oil positioned within said oil cup on the discharge side of the opening in said fuel tube connecting said tubes, and a heat insulating sleeve surrounding said oil cup.

11-. Ignition mechanism for a rotary oil burner including a rotatable oil cup comprising a fuel tube opening into said cup and constituting one electrode of an electric circuit, a tube electrically insulated from and surrounding said fuel tube extending into said oil cup and constituting a second electrode, a resistance coil positioned within said oil cup on the discharge side of the opening in said fuel tube connecting said tubes, and an insulating sleeve surrounding said oil cup-in spaced relation thereto, said sleeve being so constructed and arranged with reference to said cup as to form an annular dead air space surrounding the same.

12. Ignition mechanismfor a rotary oil burner including a rotatable oil cup comprising a fuel tube opening into said cup and constituting one electrode of an electric circuit, an electrode rod extending through said fuel tube into said cup, a resistance coil positioned within the oil cup on the discharge side of the opening in said fuel tube connecting the two electrodes, and a heat insulating sleeve surrounding said oil cup. H

13. Ignition mechanism for a rotary oil burner including a rotatable oil cup comprising a fuel tube opening into said cup and constituting one electrode of an electric circuit, an electrode rod extending through said fuel tube into said cup, a resistance coil positioned within the oil cup on the discharge side of the opening in said fuel tube connectingthe two electrodes, and an insulating sleeve surrounding said oil cup in spaced relation thereto, said sleeve being so constructed and arranged with reference to said cup as to form an annular dead air space'surrounding the same. Y

14.7 Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube opening into :said cum-and comprising a heating ele.. ment disposed within the cup in spaced relation to the wall thereof, and a heat insulating sleeve surrounding said cup.

' 15. Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube opening into saidcup, and comprising an electric heating element disposed within the cup in spaced relation to the wall thereof, and a heat insulating sleeve surrounding said cup.

16. Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube pening into said cup, said mechanism comprising a heating element positioned within said cup spaced from the wall thereof and on the discharge side of said fuel tube opening, and a heat in sulating sleeve surrounding said cup.

17. Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube opening into said cup, and comprising a heating element positoned within the cup on the discharge side of said fuel tube opening, and a heat insulating sleeve surrounding said cup, said sleeve being spaced from the wall of said cup.

18. Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube opening into said cup, and comprising a heating element positioned within the cup on the discharge side of said fuel tube opening, and a heat insulating sleeve surrounding said cup, said sleeve being fixedly positioned in relation to said rotatable cup and spaced therefrom. I

19. Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube the cup on the discharge side of said fuel tube opening, and a heat insulating sleeve fixedly positioned in surrounding relation to said cup.

20. Ignition mechanism for a rotary'oil burner including a rotatable oil cup and a fuel tube opening into said cup, and comprising a heating element positioned within the cup on the discharge side of said fuel tube opening, an insulating sleeve fixedly positioned with reference to said cup and surrounding the same, said sleeve being so constructed and arranged with reference to said cup as to form .an air space about the cup.

2L Ignition mechanism for a rotary oil burner including a rotatable oil cup and a fuel tube opening into said cup, and comprising a resistance coil positioned within the cup on the discharge side of the opening in said fuel tube, and an insulating sleeve surrounding said oil cup in spaced relation thereto, said sleeve being so constructed and arranged with reference to said cup as to form an annular dead air space surrounding the same.

RENE M. VIDALIE.

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