US2990877A - Vehicle heater burner - Google Patents

Description

July 4, 1961 v. N. TRAMONTINI VEHICLE HEATER BURNER 5 Sheets-Sheet 1 Filed Jan. 27, 1958 July 4, 1961 v. N. TRAMONTINI 2,990,877

VEHICLE HEATER BURNER Filed Jan. 27., 1958 5 Sheets-Sheet 2 July 4, 1961 v. N. TRAMONTINI VEHICLE HEATER BURNER 5 Sheets-Sheet 5 Filed Jan. 27, 1958 July 4, 1961 v. N. TRAMONTIN! 2,990,877

VEHICLE HEATER BURNER Filed Jan. 27, 1958 5 Sheets-Sheet 4 L'i {A I i J i e 0 g 919 i BY adj 499W July 4, 1961 Filed Jan. 27, 1958 V. N. TRAMONTlNl VEHICLE HEATER BURNER 5 Sheets-Sheet 5 aym United States Patent 2,990,877 VEHICLE HEATER BURNER Vernon N. Tramontini, Indianapolis, Ind., assignor to Stewart-Warner Corporation, Chicago, 111., a corporation of Virginia Filed Jan. 27, 1958, Ser. No. 712,058 6 Claims. (Cl. 158-28) This is a continuation-in-part of application Serial No. 532,887, filed September 7, 1955, for Vehicle Heater Burner, now abandoned.

The present invention relates generally to sealed combustion heaters primarily intended for use in automotive vehicles. More particularly the invention relates to an improved burner to be used in such heaters.

One of the objects of this invention is to provide an improved heater burner of the spark-ignited spray type which has high efficiency and which will operate for long periods without attention.

Another object is to provide a novel heater burner of the above type which is readily removable, along with most of its accessories from the remaining portion of the heater system for servicing.

Another object of my-invention is to provide a novel heaterburner which is extremely stable in operation and which is not sensitive to the length of the exhaust line used with" the heaternor to pulsations in the combustion air supply to the burner.

Another object is to provide a burner having the above characteristics, which can be manufactured at low cost.

Another object is to provide a heater burner of the type set out above which can be started and stopped instantly, thereby lending itself well for operation in a rapid cycling heating system.

' Another object is to provide an improved heater burner which is capable of starting and operating dependably in automotive vehicle service when supplied with gasoline under a pressure no greater than the fuel pressure tolerat- .ed by a standard internal combustion engine carburetor, i.e-., a fuel pressure of the order of three to four pounds per square inch.

Another object is to provide an improved heater burner, as recited in the previous object, in which the capability of operating satisfactorily on gasoline supplied at a low pressure is achieved without complicating or significantly increasing the cost of the burner structure.

In vorder that all of the structural features for attaining the object of this invention may be readily understood, reference is herein made to the drawings wherein:

FIG. 1 is substantially a longitudinal, vertical, medial sectional view of a heater embodying a burner which incorporates features of the present invention. In this view the sparking electrodes and the fuel intake passages have been rotated slightly. so as to place them in the plane of the section, inthe interests of a better understanding of the invention; p "FIG. 2 is a transverse sectional view which may be considered as taken substantially along the line 2-2 of FIG. '1, showing the major portion of the heater structure 'in elevation from the burner end. A portion of the structure has been-broken away to reveal details of construction. In this view the sparking electrode and the fuel inlet passage are shown in their true location; 7 FIG. 3 is a transverse sectional view taken in the direction of the arrowssubstantially along the line ,3-'3 of FIG. I

of liquid fuel within the burner. for this necessity are that any accumulation of fuel within FIG. 4 is a longitudinal vertical sectional view ofthe burner drawn to larger scale. It may be considered as an enlargement of a portion of FIG. 1;

FIG. 5 is a view of a second burner embodiment with a broken-away section showing the details of the modifications necessary to alter the burner of FIGS. 1 through 4 for low pressure operation;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5;

FIG. 7is a perspective view of a third burner embodiment incorporated in a booster heater. with a broken-away section showing the modifications necessary to alter the burner of FIGS. 5 and 6 for low pressure booster operation; and

FIG. 8 is an elevation view of the burner shown in FIG. 7 with a broken-away section showing the details of the burner modifications required for booster heater operation.

The heater shown in FIGS. 1 through 4, briefly consists of a spray type burner which supplies hot products of combustion directly to the inside of a sheet metal heat exchanger, from which the heat is exchanged to a ventilating air stream, while the cooled products of combustion pass from the heat exchanger by way of an exhaust fitting. Combustion air is supplied to the heater burner from any convenient means. A-motor driven blower is suitable for this purpose. Fuel is supplied from a pump, not'shown, to the nozzle, by way of a magnetic on-ofi valve so that fuel is sprayed from the nozzle only when the magnetic valve is energized. The burner is spark-ignited by means of a suitable step-up transformer or spark coil, not shown.

A combustion air blower, a ventilating air blower, a source of high tension electricity, a fuel pump, and a control circuit, are not shown since they form no part of the present invention and they of course may take many optional and Well known forms. The present invention is primarily concerned with the structure of the burner itself and its association with the heat exchanger.

One method of regulating the heat output of a heater of the present type calls for automatically turning the fuel on and 01f as heat is required, while causing the ventilating air to flow continuously so as to keep the temperature of the ventilating air leaving the heater approximately constant. Control of this type is obtained by using an on-ofl cycling thermostatic switch in the hot air duct downstream of the heater so that whenever the temperature of the hot ventilating air rises above some manually preset level the fuel valve previously referred to is deenergized and closed. This shuts off the burner and very quickly the continuously flowing ventilating air reduces the temperature of the heat exchanger, and hence the temperature of the ventilating air. to the point where the thermostatic switch in the hot air duct recloses, thereby reopening the fuel valve and instantly restarting the heater. This cycling continues endlessly whenever the heater is in operation and serves to maintain the temperature of the ventilating air at a desirable level through the operation of a comparatively simple control system.

Regulation of the type discussed above places considerable demands upon the burner, however, since the burner should, with this type operation, start and stop substantially instantaneously, so as to prevent any accumulation The principal reasons the heater is likely to produce an objectionable gasoline smell in the vicinity of the vehicle, and furthermore, the principal source of carbon formation within a burner of this general type is the periodic presence of unburned gasoline. Thus the service life of the burner between inspections and cleaning periods is greatly extended if the burner can be kept free of unburned fuel.

In combustion heaters it is also necessary that the metal of the heat exchanger not be overstressed by expansion and contraction, and this is a difficult problem to solve in a rapid cycling system of the type described above where the metal of the heat exchanger is rapidly heated and rapidly cooled in a cyclic fashion.

Referring now particularly to FIG. 1, I have indicated a generally cylindrical sheet metal case at through which the ventilating air flows. For this purpose it may be considered that the right hand, as illustrated in FIG. 1, is connected to a source of ventilating air such as a ventilating air blower, for instance while the opposite end of the case is connected to duct work leading to the space to be heated.

In order to facilitate assembly and servicing of the heater, a generally rectangular section, -as indicated by the line 12, is cut out of the duct 10 at the top, the opening thus formed which extends to about the center line of the duct being closed by a removable curved cover 14 secured to the duct 10 as by screws 16 threaded into nuts 18 which are anchored to the duct 10. Sheet metal screws may be used if desired.

A heater of this type commonly is provided with an overheat safety thermostatic switch which is for the purpose of turning oif the burner, that is, shutting off the fuel, in the event that the metal of the heat exchanger becomes too hot. In the interest of completeness, I have shown such a safety switch at 20 mounted in a recess 22 in the cover 14. This is an appropriate location for this switch, since it is thus placed close to the heat exchanger where it is subjected to radiation heating, and furthermore it is readily available for adjustment of checking simply by removing the cover 14.

The heat exchanger is preferably formed of stainless steel or similar metal and is comprised principally of three nested, generally cylindrical sheet metal tubes. The outermost of these tubes is indicated at 24. It encloses the intermediate tubular member 26 which in turn surrounds the innermost tube 28. The three tubes are well spaced from each other. At the bottom of the heater the outermost tube 24 is flattened somewhat longitudinally so as to provide a longitudinally extending larger space as will appear, for the collection of exhaust which is conveyed to a tubular outlet fitting 30. This fitting or spud is flanged at its inner end as at 32 and is seam-welded to the metal of the outermost heat exchanger tube 24. The exhaust fitting extends downwardy through an opening in the air case 10 so as to be available for the attachment of an exhaust line which may lead to any suitable location.

The ends of the intermediate tube 26 are stretch-formed to a larger diameter as indicated at 34 and 36 so that the external diameter at the stretched portions fits the internal diameter of the external tube 24, In accomplishing this some inward or outward shaping of the ends of the tube 24 may be advisable as an aid to convenient fabrication. As shown, the right end at 36 is slightlylargerthan the left end at 34 so that in assemblingthe elements the tube 26 may freely be slid endwise into the left end of the tube 24 for almost its entire length, some pressure being applied to bring about a final seating between the interfitting tube ends.

The left-hand end of the innermost tube 28 is closed by an outwardly flanged closure member 40 which is pressed into place with its flange 42'tightly fitted into the end of the opening in the innermost tube 28. To facilitate fabrication, this end of the tube 28 may also be shaped inwardly or outwardly slightly, this s'hapiri'g being not so much for the purpose of altering the'dirn'eii'sion as for the purpose of arriving atiapredeterrn iii'eddimehs'ion. It 'is easier 'to rem -s'liet metaltubes, such "as 28,

26 and 24, approximately to desired size and then stretch or shrink the ends sutficiently to exceed the elastic limit of the metal and thereby to arrive at a definite dimension than it is to attempt to make the tubes with the desired press fit, without this supplemental shaping.

A tubular burner adapter fitting 44 is shown at the right-hand end of the tube 28 with approximately half its length projecting into the space within the tube 28. It, like the other elements, is formed of sheet metal and is flared at its outer end as at 46 while its inner end is shaped inwardly to a smaller dimension to form a short cylindrical flange 48 at its end. v

At the top, the innermost shell has a longitudinally extending portion punched out to form a slot which does not approach either of the tube ends very closely. The metal in the vicinity of this slot is also drawn outwardly and thus forms a peripheral outstanding rib 29 surrounding a generally rectangular opening with well rounded ends. The metal of the intermediate shell is similarly punched and drawn inwardly at the top so as to form a similar slot and peripheral rib 31 which is of such a size and shape as to telescope tightly over the rib 29. During assembly these two ribs are telescoped and seam-welded together, so as to be joined entirely around their periphery, thereby providing an airtight passage 33 between Shells 28 and 26.

It should be noted further that the inner shell 28 together with the burner mechanism carried thereby (as will appear) is supported entirely separately from the intermediate shell 26 excepting for the connection at the joint between the ribs 29 and 31. This gives a very 'resilient support to the interior of the heat exchanger with respect to the outer portion thereof, and this prevents differential expansion and contraction of the order encountered in a device of this character from producing local wracking stresses on the metal which in more conventional structures frequently results in a breakdown of the joints between the elements.

The combustion chamber of the burner is illustrated at 50 and consists of a generally cylindrical sheet metal cup with the base thereof secured to the center of a circular plate 52 as by riveting, as shown at 54. In order to space the base of the cup slightly from the plate 52, the rivets pass through stamped bosses 55 formed either in the plate or the base or both. The cup 50 has its outer end flared outwardly to provide a cylindrical flange 56 which forms a loose sliding fit with the flange '48 of the adapter. The cup 50 is provided with several combustion air entry holes 58 in its side wall and the base thereof has an inwardly flanged opening '60 surrounding a fuel spray nozzle 62. The end of this nozzle projects through a hole at the center of the plate 52, and this plate 52 also is lanced and deformed to provide several louvers '64 which permit combustion air to pass from a chamber 66 to the right of the plate 52 into the annular chamber 68 which is formed within the adapter 44 with a's'wirling motion. A small amount of air also flows without spin from the space 66 through five small holes 69 placed substantially evenly around the central hole in the plate 52. The air thus admitted insures pressurization of the space between the base of the cup 50 and the plate 52 even under high air flow rate conditions where the rotary effect produced by the louvers 64 might otherwise produce a low pressure at the nozzle opening60. Air from the annular chamber 68 then passes inwardly through the previously mentioned holes 58 with a rotary component and some of this air and that flowing throughthe holes 69 passes through the opening 60 around the end of the nozzle 62 and through other openings to be mentioned presently. In order to provide desirable turbulence within the burner, a narrow strip of metal '67 extends across near the mouth of'the combustion chamber. Itis secured sirriply by snapping its ends, which "are slightly narrower than the main portion thereof, i'rito 'tv'vo "of "the holes 58 which are opposite each other.

A cup 70, which can be readily formedas a die casting for instance, since it remains cool, is provided with a peripheral'flange 71 at its open end. This cup is se: cured with its open face against the back of the previ-, ously mentioned plate 52 by means of screws 72,; and the flanges 71 and 46, together with a resilient sealing gasket 74 are all secured together by a screw tightened split peripheral clamping band, 76. As shown, the insulator for one of the electrodes of the spark-igniter is indicated at 78. 'It extends through an opening at the base of the cup 70 and aligned openings in the plate 52 and combustion chamber 50, and is secured in place and sealed by a screw-held clamp fitting 80 and copper gaskets 81. It isso positioned that its electrode 82 extends into the combustion chamber in close proximity to a grounded electrode 84 welded to the base of the combustion chamber cup 50 in an appropriate location.

"The nozzle62, which is conventional, is secured in the end of a hollow stem 85 formed at the center of the cup 70, and this stern also contains the elements of the magnetically actuated poppet type fuel valve 88. The coil for actuating the valve is indicated at 86 and is secured against the base of the cup 70. Fuel is brought to the valve by way of an inlet fitting 90, and a cored passageway 92 which intersects a passage 94 drilled in the die casting so as to intersect the valve chamberin the stem 85.

[In addition to the combustion air louvers 64 which; serve as air inlets to the space 68 around the combustion chambe'r'50, there are also two similar louvers 73 formed in the base of the combustion chamber 50. These are about 120 degrees apart and are equally spaced with respect to the opening in the base of the combustionchamber through which the electrode insulator 78 passes. The clearance at this point (between the insulator and com bustion chamber base) actsas a third air inlet opening. These three air inlets, together with that provided by the central opening 60 around the nozzle, supply suflicient air for starting and are a great aid in preventing the formation of carbon deposits upon the nozzle face and sparking electrodes. e The central opening in the plate 52 fits tightly against the tapered end of the nozzle and insures proper centering and spacing of the elements. During this assembly operation there is no objection if the center of the plate 52 is sprung inwardly slightly, and therefore the parts involved canbe made to ordinarily observed manufacturing tolerances.

The close proximity of the poppet fuel valve 88 to the nozzle insures that there will be almost no residual fuel trapped between thevalve and nozzle when the valve is closed. This is extremely helpful in preventing dribbling of fuel from the nozzle after the burner has been shut off. I for combustion is brought into the space 66 within the cup 70 through one of a pair of horizontal hollow horns 96 or 98. These horns are formed as a portion of the die casting 70. Two are provided, one on each side, so that the tube from the combustion air blower can be connected on whichever side is the more convenient for a particular installation. The opposite opening is partially closed by a pressed-in flanged disc 100 which has a small hole 102, in the present example about one-quarter inch in diameter, therethrough. This hole helps in preventing noisy or uneven operation of the burner and has proved to be very effective for this purpose even under conditions where the combustion air supplied to the burner pulsates considerably. This feature is important because the most customarily used source of combustion air is a blower of the centrifugal type which produces a pulsating air stream caused bythe passage of the blades of the rotor in near proximity to the blower outlet opening.

, It should be noted that each of the air horns is fitted into a rubber tubular member 104 or 106 which extends outwardlyand provides a flat vertical face 108 or 110 which engages the inside surface of the sheet metal around openings formed betweenthe case 10 and the cover 14 to permit ,thepass ageof the Imembers 104 and 106. This arrangement acts as a seal for the opening s in the air case 10 and also provides resilient support for the burner, combustion chamber, and heat exchanger withrespect to the air case. One of these tubular members 104 is molded at the end of the combustion air inlet hose and serves as the means for conducting air to the chamber within the cup 70. The other tubular member 106 terminates just outside the wall of the case 10 and acts as an atmospheric pressure outlet for any air flowing through the hole 102. Additional means for supporting and locating the heat exchanger outer shell 24 within the casing 10 may take the form of sheet metal spacing clips secured to the inside surface of the case 10 as at 114 for instance. With the above structure it will be seen that the heat exchanger and the burner are secured together as a single unit which is mounted within the air casing 10 and supported therefrom in a manner which provides for free movement within a limited range. Therefore, no strain is put upon the metal of the heat exchanger or burner due to expansion and contraction which occurs differentially as between the heat exchanger and the air case 10.

It will be apparent that by removing the cover 14, the spark plub wire and fuel line connection, and by removing or sufficiently loosening the clamping band 76 the burner casting 70, the combustion chamber 50, the sparking electrode 78, the nozzle 62, the fuel valve and actuator therefor 8886, may all be removed from the heater in one piece simply by slipping the combustion chamber '50 to the right out of its adapter tube 44. Thus all of the elements of the theater which might require attention, including the over-heat switch 20, which is attached to the cover 14, are readily accessible. The heat exchanger and air case 10 and its mounting brackets and connections to the ventilating air duct work may be allowed to remain in place undisturbed.

Note also that the only sealed joint between the burner mechanism and the heat exchanger is at the clamping band 76 which remains cold. It is well removed from the hot portions of the heat exchanger and burner, and also cold ventilating air flows over the joint while cold combustion air flowing through the space 66 and air chamber between the combustion ohamber 50 and adapter 44 has a cooling effect. This permits the use of a simple, molded, rubber seal-ing gasket at 74 and insures that the burner mechanism will be well sealed and will be readily removable even after extended use, since there will be no warping or roughening of the matching surfaces such as is usually caused by repeated heating and cooling and by combustion gases. The joint between the flanges 48 and 56 can be quite loose and, therefore, gives no diflicul'ty, it being appreciated that looseness will merely result in a small and unimportant amount of additional combustion air flowing into the heat exchanger around the combustion chamber.

\As shown, all of the elements of the heat exchanger and the burner adapter tube, which is directly attached thereto, are joined and sealed by seam resistance welding and, therefore, the structure may be fabricated at low cost.

In order to remove any unburned fuel that may possibly leak from the nozzle 62 into the combustion chamber 50, an L-shaped draine tube 112 extends from a low point in the adapter fitting 44 to the exhaust spud 30. This tube may be sealed to the sheet metal at both ends by silver soldering, since the temperatures encountered atthese joints are never very high.

In this heater, assuming a supply of ventilating air, combustion air, fuel under pressure, and tension electricity, all appropriately connected as previously mentioned, opening the fuel valve causes fuel to be sprayed from the nozzle, mixed with combustion air and ignited by the spark between the igniter electrodes. Hot products of combustion thus formed pass from the combustion;

chamber into the inner shell 28 and thence through the passage 33 into the space between the intermediate shell 26 andthe outer shell 24. The hot gases then how circumferentially in both directions and longitudinally to the exhaust fitting 30. Hot products of combustion, therefore, heat all of the heat exchanger surfaces. Ventilating air removes the heat by flowing longitudinally between the air case and the outerrshell 24 and between the intermediate shell 26 and the inner shell 28.

The heater previously described is adapted to use gasoline supplied to the burner nozzle at relatively high pressures of the order of 25 to 30 pounds per square inch. In a passenger car installation, the usual carburetor fuel pressure is generally inadequate for fuel supplied to a combustion heater. As a result an auxiliary pump is required to raise the pressure of the fuel supplied to the heater above that required for fuel supplied to the carburetor. This additional pump contributes to the cost of the heater installation and in many instances rules out the use of a heater which would otherwise be admirably suited to serve the heating requirements of an automobile.

The desirability of eliminating the auxiliary fuel pump has stimulated eiforts to operate a vehicle heater on gasoline delivered to the burner nozzle directly from the standard fuel pump at carburetor pressures. However, the inherent operating characteristics of a burner nozzle used in a combustion heater is such that a coarse spray results from relatively low fuel pressures.

This coarse spray does not ignite with certainty and does not burn eiiiciently and dependably. The reduced number and larger size of the fluid droplets in the coarse spray tends to delay vaporization of the fuel in critical burner zones where a proper mixture of fuel and air is essential to positive ignition and dependable fuel combustion under adverse conditions characteristic of vehicle service. These conditions include not only extreme weather conditions, but also highly significant changm in the rate at which combustion air is forced through the critical burner zones by the electric blower supplied for this purpose.

FIGS. and 6 disclose certain modified burner components substituted for related components in the burner shown in FIGS. 1 through 4 so that this latter burner may be adapted for operation at the usual carburetor fuel pressures which may be of the order of three to four pounds per square inch gauge. Burner cup 50a and circular plate 52a are intended for substitution of components 50 and 52 in the burner shown in FIGS. 1 through 4.

The principal structural changes featured in the low pressure burner components 50a and 52a are as follows. Three louvers 125 are included in the side wall of burner cup 50a. These louvers are formed closely adjacent the fuel injection and ignition zone at equally spaced peripheral distances. A gasket or ring 126 is sandwiched between the base of cup 50a and plate 52a so that a reduced amount of air flows between chambers 68a and 127.

It should be noted that the base of cup 50a omits the louvers 73 formed in the base of cup 50, shown in FIG. 3. Plate 52a is also preferably formed with only three circularly spaced holes 69a as compared to the five holes 69 formed in plate 52 and shown in FIG. 4. The inclusion of gasket 126 and the reduction in the number of spaced holes is desirable to prevent tearing apart of the low pressure fuel spray emanating from the nozzle 62a. Spark plug 781: fits loosely in the holes formed in the base of cup 50a and plate 520:, and nozzle 62a fits tightly in the hole formed in plate 52a. Combustion air enters the combustion chamber formed within cup 50a through louvers 125, holes 6911 and the annular opening around spark plug 78a.

The modified construction of FIGS. 5 and 6 insures a uniform air supply within the combustion chamber formed b su 0 i hst nd n he fact hat h ai output ths'q mb stie a r blower new fl ctu s e a fla r- 1y broad pressure range.

Louvers are employed in lieu of the louvers 73 of the embodiment shown in FIGS. 1 through 4 so that the combustionair required at the nozzle or the base end of the burner cup will not disturb or otherwise tear apart the uniform core of fuel spray. The vortex of air intro duced by louvers 125 tends to concentrate this, core of fuel spray Without undue disturbance.

With a low pressure burner it is necessary to limit the amount of primary air to a certain maximum value to obtain a low temperature ignition. If the primary air quantity becomes excessive, the mixture will be lean and will not ignite with the relatively low energy spark available. It is for this reason that in the modified construction of FIGS. 5 and 6 the base of the burner cup and plate 52a are so formed that material quantities of air flow only through louvers 64a, holes 69a and the annular opening around spark plug 78a.

FIGS. 7 and 8 disclose an alternative embodiment of the low pressure burner structure of FIGS. 5 and 6 which is particularly adapted for use in a low pressure vehicle heater of the booster type. A booster heater is one which is inserted between the vehicle engine coolant line and a conventional hot water heater so that the booster heater may supply hot water to the hot water heater shortly after engine start up.

In a preferred construction for a booster heater, the heating requirements are of such a nature that the outer wrap of the heat exchanger has a smaller diameter than that usually found in hot air heaters. Accordingly, in a preferred construction, adapter devices can be dispensed with and the burner can be telescopically inserted within an extension section of the heat exchanger. For example, in FIGS. 7 and 8 the outer wrap of booster heater 151 is extended so that burner 152 is telescopically coupled to the outer wrap. The only principal change required to adapt the components of FIGS. 5 and 6 to the requirements of the booster heater of FIGS. 7 and 8 is the inclusion of an annular flange 153 on the heat exchanger end of burner cup 5% and the addition of a ring-like rim 154 on the periphery of end ring 153. This rim 154 makes a loose sliding fit with the interior surface of the outer wrap 150. Additionally, it should be noted that the burner cup 70b does not include any type of horn incorporating an air hole 102 (FIG. 2), as combustion noise which may result from this omission may be tolerated in a booster heater. In all other particulars burner cup 50b corresponds exactly to cup 50a shown in FIGS. 5 and 6. Likewise, plate 52b corresponds exactly with plate 52a of FIGS. 5 and 6.

It should be noted that with respect to all three of the burner embodiments disclosed herein, the burner structure, including casing 70, 70a or 7%, together with associated burner cups 50, 50a or 50b can be integrally removed from the heat exchanger which incorporates the enveloping burner shell or adapter fitting 44, 44:; or 4411. This operation may be easily effected by releasing the appropriate clamping band and withdrawing the central burner structure from within the associated components. The mode of cooperation between burner and the heat exchanger greatly facilitates the repair of the burner in the event of faulty operation inasmuch as ready access can be had to the internal burner components.

The above described embodiments are merely illustrative of the principles of this invention. It should be understood that modifications can be incorporated therein without departing from the scope of the invention.

I claim:

1. In a burner for supplying hot products of combustion to the heat exchanger of a sealed combustion heater for an automotive vehicle, means forming a tubular adaptor fitting, a sheet metal cup forming a combustion chamber having its rim shaped to form a loose fit with said adaptor fitting, said fitting and said cup being shaped to provide appreciable space therebetween excepting at said nm, ,a circular combustion air baifie plate secured to the base of saidlcup in spaced relation thereto, means forming a larger cup having its mouth removably secured to the end ,ofsaid fittingoppo'site said rim, means securing Saidplate acrossthe mouth of said-larger cup, said plate halving a central openingtherethrough, said larger cup having an axial hollow stem extending from the base thereof, a spray nozzle secured in the end of said stem, said nozzle having-a tapered forward face seated in'the central opening in said plate when said plate, said larger cup and said adaptor fitting are secured together, said combustion chamber forming cup having air inlet openings formed through the side wall thereof, the base of said combustion chamber forming cup being formed to provide additional air inlet openings to the combustion chamber, the last said openings including a circular opening in alignment with the central opening of said plate and defining an annular space around said nozzle, said plate being formed to provide a plurality of openings communicating the interior of the larger cup with the space between the adaptor fitting and the combustion chamber, means for supplying air for combustion to said larger cup, a spark plug having an insulating sleeve, said sleeve extending through aligned openings in said larger cup, said plate, and said combustion chamber forming cup, said spark plug terminating at one end in an exposed sparking electrode positioned within said combustion chamber.

2. A two-part burner structure comprising as a first part, a generally tubular fitting adapted to be permanently attached to a heat exchanger for a vehicle combustion heater and comprising as a second part, a removable assembly comprising a cup forming an air supply casing, a plate fixed across the mouth of said cup, a second cup having a smaller diameter than said casing and having a base attached to and supported by said plate, said second cup having air inlet openings formed in the wall thereof, a nozzle disposed within said air supply casing and having a forward end seated in an opening in said plate so as to supply fuel to the chamber of said smaller cup through a central opening located in the base of this cup, and a plurality of circularly disposed louvers formed in the portions of the plate outwardly offset from the base of said smaller cup, said smaller cup being insertable into said tubular fitting with said plate acting as a stop against said tubular fitting and the forward end of said second cup frictionally engaging said tubular fitting to form an annular chamber around said smaller cup having an air fiow inlet from said air supply casing through said louvers and an outlet into said chamber of said smaller cup through said opening in the Wall.

3. A two-part burner structure comprising as a first part, a generally tubular fitting adapted to be permanently attached to a heat exchanger for a vehicle combustion heater and comprising as a second part, a removable assembly comprising a generally tubular air supply casing, a plate fixed across a transverse opening in said casing, a second generally tubular casing having a smaller diameter than said first casing and attached to and supported by said plate, said second casing having air inlet openings formed in the wall thereof, a nozzle disposed within said air supply casing and having a forward end seated in an opening in said plate so as to supply fuel to the chamber formed by said smaller tubular casing, and a plurality of shielded openings formed in the portions of the plate outwardly oifset from the smaller tubular casing, said second smaller tubular casing being insertable within said genera-11y tubular fitting with said plate acting as a stop against said tubular fitting and the forward end of said second generally tubular casing frictionally engaging said generally tubular fitting to form an annular chamber around said'second generally tubular casing having an air flow inlet from said air supply casing through said shielded 10 openings and an outlet into thechamber of said second generally tubular casing through said opening-in the wall.

4. A two-part burner structure comprising as a first part, a generally tubular fitting adapted to be permanently attached to a heat exchanger for a vehicle combustion heater, and comprising, as a second 'part, a removable assembly comprising a cupforming anair supply casing, a plate fixed across the mouth of said cup, a second and smaller diameter cup having its base attached to and supported by said plate, said second cup having air inlet openings formed in the wall thereof, a nozzle disposed within said air supply casing and having a forward end tightly seated in a central opening in said plate so as to supplyfuel to the chamber of said smaller cup through a central opening located in the base of this cup, a spark plug having an insulating sleeve extending through aligned openings in both of said cups and said plate and supporting an ignition electrode with in said second cup, and a plurality of circularly disposed louvers formed in the portions of the plate laterally offset from the base of said smaller cup, said smaller cup being insertable into said tubular fitting with said plate acting as a stop against said tubular fitting and the forward end of said second smaller cup frictionally engaging said fitting to form an annular chamber around said smaller cup having an air flow inlet from said air supply casing through said louvers and an outlet into said chamber of said smaller cup through said openings in the wall.

5. A two-part burner structure comprising as a first part, a generally tubular fitting adapted to be permanently attached to a heat exchanger for a vehicle combustion heater, and comprising as a second part, a removable assembly comprising a generally tubular air supply casing, a plate fixed across a transverse opening in said casing, a second tubular casing having a smaller diameter than said first casing and attached to and supported by said plate, said second casing having air inlet openings formed in the wall thereof, a nozzle disposed within said air supply casing and having a forward end tightly seated in a central opening in said plate so as to supply fuel to the chamber formed by said smaller tubular casing, and a plurality of louvers formed in the portions of the plate outwardly offset from the smaller tubular casing so as to project away from said air supply casing and serving as air openings through said plate, said second tubular casing being insertable into said tubular fitting with said plate acting as a stop against said tubular fitting and the forward end of said second tubular casing frictionally engaging said fitting to form an annular chamber around said smaller tubular casing having a restricted air flow inlet from said air supply casing through said louvers and an outlet into the chamber of said smaller tubular casing only through said openings in the wall.

6. A two-part burner structure comprising as a first part, a generally tubular fitting adapted to be permanently attached to a heat exchanger for a vehicle combustion heater, and comprising, as a second part, a removable assembly comprising a generally tubular air supply casing, a plate fixed across a transverse opening in said casing, a second and smaller diameter tubular casing attached to and supported by said plate and formed with a plurality of circularly disposed louvers adjacent said plate and a plurality of holes farther removed from said plate, a nozzle disposed within said air supply casing and having a forward end tightly seated in a central opening in said plate so as to supply fuel to the chamber formed by said smaller tubular casing, and a plurality of circularly disposed louvers formed in the portions of the plate outwardly offset from the smaller tubular casing so as to project away from said air supply casing and serving as the only material combustion air openings through said plate, said smaller diameter tubular casing being insertable into said -tubular fitting with said plate acting as a stop against said tubular fitting and the forward end of said smaller diameter tubular easing ffricti'ona'lly engaging said fitting to form a confined annular chamber around said smaller tubular easing having an 'air flow inlet from said air supply casing through said ,plate louvers and an outlet into the chamber of said smaller tubular casing through the holes and louvers formed in the walls thereof.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain Feb. 6,

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