US2642858A - Fuel burning air heating device - Google Patents

Description

June 23, 1953 E. H. PLEssl-:T :TAL 2,642,858

FUEL BURNING AIR HEATING DEVICE Filed sept. so, 194e 3 sheets-sheet 1 l *1K/.lm

l `l a EAP/V57 M Q 555.47%

June 23, 1953 E H PLEssET ETA; 2,642,858

FUEL BURNING AIR HEATING DEVICE Filed Sept. 30, 1948. 5 Sheets-Sheet, 2

June 23, 1953 E. H. PLEssET ETAL 2,642,858

FUEL BURNING AIR HEATING DEVICE Filed sept. so, 194e s sheets-sheet s IN V EN TORS Patented `lune 23, 1953 FUEL BURNING AIR HEATING DEVICE Ernst H. Plesset, Sherman Oaks, William R.y Elswick, Santa Monica, andPaul. A. Palmer, Los Angeles, Calif.; said Elswick. and said Palme assignors. to said Plesset Application septemtepao, 194s, swarm. 52,032

comme.' (01. 12e-us).-

This invention-relates to heating.l devices and more particularly to a heating device of the-internal combustion type in which a combustible fuel is burned. Althoughy the illustrated embodiment of.V the present'invention has been shown and described as one intended to burn hydrocarbon fuel in. liquid phase, the invention. is not to be limited thereto, for; fuels ingaseous or vaporous phase could be used.

HeatingV devices of. the internal combustion. type have been previously' proposed. and. used as heaters for motor vehicles, airplanes, andv the interiors of: buildings of: various sizes. Such devices asv have been heretofore proposed have generally consisted of a spray elementv for injecting liquid fuel such. as gasoline, diesel` oiland other hydro-carbons in droplets into a'combustion chamber; Various igniting devices have been proposedv to ignite the injected fuel with. varying success.

Considerable dfculty has been experienced in. igniting the fuel particularly' at low temperatures and at: high. altitudes.4 Thisr diillcultyxhas plagued the industry for many years andr although. various solutions have been advanced heretofore, no one solution has 'completely solved the problem of starting the: heater and maintaining combustion of the fuel atlowtemperatures and at thev alti.- tudes at which presentl day' airplanes operate. Although internal combustion heatersV foruse inl aircraft' present problemsy not. presented by heaters designed for use in motor vehicles such as passenger cars, trucks and busses, nevertheless the latter type heaters, particularly inv cold weather,.-

haver not generally been entirely' successful. Failure of' ignition of the. fuel-air mixture-is the. most frequent cause of dissatisfaction.

The present invention provides an internal combustion. heater in which the fuel-air mixture is easy to ignite even at temperatuers Well belowy 0 F; and at' low pressures corresponding to high.

altitudes. As is well known, the ignition of liquid. fuels becomes increasingly diflicult as the 'temperatures` offthel liquid fuel and combustionv air. and ambient pressures are decreased. At'v leastv a part ofthe difficulty arises from the strong dependence ofr vapor pressure of such liquid fuels upon temperature. At relatively low temperatures, spontaneous vaporization may occur at such. a low rate that the resulting air-fuel mixture is so lean .that combustion of the mixture may be extremely difficult or even impossible. For instance, it has been found-that ignition of the fuel in an aircraft heater may be easily lbrought about when the temperature of the fuel Vand combustion air is relatively highv but that the flameis often extinguished by the cold fuel droplets and cold inletlairas the aircraft ascends into altitudes` of: colder temperatures and lower pressures where; little, or no.. spontaneous vaporization. of the fuel takes place..

Furthermore.. at high altitudes because of the. low* atmosphericfpressures, the combustion air suppliedto a combustion chamber ofheaters, of the type herein disclosed, from the ambient atmosphere is: less dense than at. sea level and,

` as is well-.knowncombustionzoff even a static system is more difficult: to.A maintain where the density of thefuel-air' mixture is. relatively low". The geometries of the: heater of the present invention and. they action of the injector-burner therein used produces a.- morev stable combustion system which is. not asf adversely affected by'lowvv atmospheric pressures asv previously proposed combustion systems. ofpriorheaters.

It will; also be seen that. the lower densityl of theffuel-air-mixturenecessarily callsflor a greater volume flow of combustion. air to maintain a given thermal output and the required increased velocity of the combustion. air often extinguished the flame inf prior heaters. In the heater of the present invention the velocity of. the combustion air entering the combustion chamber has little, if anyadversek effect on; the combustion flame so that' the ydi'tiiculties had. with prior heaters is not experienced with the heater" of this invention.

The present. invention provides means for insuring ahi-gh rate of vaporization and lean fuelair mixtures are: thus eliminated To bring about A this feature of. the vpresent-invention, liquid fuel is heated. tov rapidly producer fuel vapor', which vapor is further heated as* it admixes with a portion of the combustionairwhichis also warmed. The resulting` fuel vapor-air mixturev is easily ignitedr and asthe fuel, the vapors thereof',` and of the present. invention, liquid .fuel is collected in a well contiguous' to a fuel injector andza heat,- ing element mounted! the Well vaporizes the liquid. fuer collected therein, andv further heatsthe fuel; vapor formed to increase admi-Xing of the fuel vapor with combustion air as Well as to` heat the mixture formed.' Ignitionof' the heated fuelv vapor-air mixture cany nowfbe easily brought about by any means desired:l although. in one embodiment ofthe heater herein shown. the mixture.

is ignited by the portion of the heating element disposed above the surface of the liquid fuel held by the well.

The ignition of the mixture creates a pilot flame, which impinging against the fuel injector, rapidly increases the temperature thereof, which results in better vaporization of the incoming fuel. The fuel injector is comprised of a hollow vessel at least one wall of which is permeable by the liquid fuel. The liquid fuel passing through the permeable wall is caused to vaporize and this when mixed With combustion air forms a combustible mixture which is easily ignited by the pilot flame previously created as above described. A main combustion flame is thus established at the fuel injector, which as will now be seen lalso serves as a burner. The flame established at the injector-burner further heats the same and liquid fuel supplied to the interior of the hollow vessel forming the injector-burner is consequently heated and vaporization of this fuel is had actually within the injector-burner. Thus the injector-burner itself furnishes fuel to the cornbustion chamber in the physical state most conducive to efficient burning. With the main cornbustion fiame now established at the injectorburner, which serves also as a flame holden'the heating and ignting element can be deenergized.

In another embodiment of the invention,y the fuel vapor-air mixture, although warmed by the heating element mounted in the well, is ignited by a separate igniting element mounted adjacent to the well. In this form of the invention, a hoodlike shield or guard is mounted over the well and serves to trap and guide the mixture to the igniting element. The ignition of the mixture, as in the earlier mentioned embodiment of the present invention, heats the injector-burner and produces vaporization of the liquid fuel not only at the surface of the latter but within the same as well.

Ignition of the fuel vapor-air mixture produced at the injector-burner is quickly brought about and the main combustion name thus created at the burner, which also serves `as a flame holder, further heats the fuel supplied thereto to produce even more rapid vaporization of the fuel.

The ignition means may be formed as a part of the injector-burner by embedding in at least one wall member and preferably the porous or foraminous member a resistance element which, when energized, Will heat the wall member to a temperature suicient to vaporize and ignite the resultant fuel vapor-air mixture formed contiguous to the surface of the burner. If desired, a separate igniting element may'be mounted adjacent the injector-burner for igniting the ccmbustible mixture formed by the commingled fuel vapor and air surrounding the burner.

The injector-burner, in all embodiments illustrated, serves further as a flame keep-alive for preferably the same is formed of a material having a low heat capacity and thermal conductivity. Thus, if for any reason the main combustion flame is extinguished at the injector-v burner, re-ignition is immediately brought about as the fuel vapors passing through the permeable wall of the injector-burner are admixed with combustion air at the exterior surface of the injector-burner which is at a temperature sufficiently high to ignite the mixture created at the surface.

Other features and advantages of the present invention will be apparent from the following detailed description of the illustrated embodiments of the present invention, particularly when taken ooi 4 in connection with the accompanying drawing, in which:

Figure 1 is a perspective view of one embodiment of the heater of the present invention partly in phantom;

Figure 2 is a sectional view of the heater shown by Figure 1; f

Figure 3 is a section taken along 3-3 of Figure 2;

Figure 4 is a perspective view of the heating and igniting element of the heater of Figure 1;

Figure 5 is a top plan view of the heating and igniting device shown in Figure 4;

Figure 6 is a longitudinal, sectional view of the heating and igniting device;

Figure 7 is a sectional view of a modied form of the injector-burner of the heater of the present invention;

Figure 8 is a view similar to Figure 2 but showing a modified embodiment of the heater of the present invention;

Figure 9 is a section taken along line 9-9 of Figure 8; Y

Figure 10 is a fragmentary sectional view of the heater of the embodiment shown in Figures 8 and 9; and

Figure 11 is a view similar to Figure 7 but showing a still further modified form of the injectorburner.

The heater of the present invention in one embodiment herein illustrated, referring now to the drawing and more particularly to Figures 1 through 6, comprises an outer shell or casing I0 formed at one end with an inlet II for air to be heated. This air may be supplied by a compressor or air pump forming a part of the heater or may be air from Ia ram duct particularly if the heater is used on an airplane. The outer shell is formed at the end opposite to said inlet with an opening or register IIa for discharging into the space to be heated air which has been passed over the exterior surface of the combustion chamber I2. To increase the heat transfer from the wall of the chamber I2 the exterior surface of the same is provided with a plurality of longim tudinally extending ns I3 which may be cast or molded integrally with the chamber wall. 1f desired, however, the fins I3 could be separately formed and then subsequently secured to the exterior surface of the chamber wall by some conventional process such as welding or brazing.

The combustion chamber I2 itself may be formed by any conventional forming or fabricating process or processes, but should be of a material which will withstand the high temperatures bolted or otherwise secured to the edge face of the open end of the chamber.

The transverse wall I4 and closure dome I5 form a plenum chamber I6 into which combustion air is forced from a source of air under pressure. This source may comprise a ram, although in the form of the invention herein shown, air under pressure is furnished to the plenum chamber by a small compressor or air pump I1 carried by the outer shell Ill; by a suitable. bracket I8. A duct I9 leads |air from the discharge end.

of the compressorv through the domel closure.' I5

and into the plenum chamber. IIt should now be. seen that combustion after burning of the fuel has commenced, is warmed by theair flowing around duct. I9, this air having been heated in passing over the, combustion chamber I2. Inaddition, the wallY I ofthe plenum charnber istraversed by the heated air just prior to itsA exit through the register IIav thus further heating the inlet combustion air` inv chamber I6'.

The, transverse wall, I4 is formedwith a relatively large opening 2lV located adjacent; the. up per marginal` portion, thereof. The wall is. provided with a vane, 22V which is so positioned that;

air passing through the openingN 2l. is directed by the vane-downwardly anduve-r a fuelA injecting device 23.

The. fuel injecting device comprises; a. small vessel. or receptacle, the, wallsv of which are at least' poriferous in part, which. may take vari.- ous forms depending uponthe flame*` pattern de..- sired. This vessel may be formed` of numerousY materials so long as the specific fuel tobe burned will permeate at least a portionof the wall members or readily pass through the same. The ma.-` terial may be porous, that is, one with such interstices or forarnina that permeation by the fuel is possible, or the material forming the Walls of the vessel may bev impervious and rendered porous or foraminous by small openings or channels formed through the Walls of the vessel.

The material used to form4 the vessel or receptacle 23 could be a porous metal formed by the techniquesv of powder metallurgy or one of a number of porous ceramics. Where a porous material, either metal or ceramic, is used the interstices of the material should be of such size that the liquid will, by capillar flow or because of pressure on the liquid, pass through the walls of the. vessel.

It. should be noted here that the entire ves-y sel need not be formed of a porous materiall so long as a portion of av wall is permeable by the fuel. Thus, for example, the` vessel might be formed in part of. a material impervious tothe fuel and in part by a porous material which would permit passage of thev fuel. The wall portion permeable by the fuel could consist of a reticulated plate or-screen of a suitable metal or other material permanently mounted across an opening in oneror more wall members of the vessel.

The fuel injecting vessel 23 may be mounted within the, combustion chamber I2 by any means desired although, in the. form of thev invention illustrated, the vessel is held inplace by a. small duct or conduit 24 forming a fuel line connecting the vessel to a source of fuel (not shown). It will be seen, referring to Figure 2, that the lineforming duct passes through aligned openings` formed in the outer shell I0 and a boss 25 carried by the wall of4 the combustion chamber and is held against longitudinal or axial movement by split, tapered plugs 26, threaded into tappedy ignited by a novel fuel heating, vaporizing, and.

face of thev wallsr thereof and.- consequently the exterior-surface of vthe same. These .means may take the form of, internal vanes 21 oppositelyprojecting fromY thev adjacent inner Wall` surfaces of the vessel. distribute the fuel over the interior'surfaces of the Wall'sof` the vessel and thus. insure the desired distribution of the fuel over the exterior surfaces of the vessel..

As is well known, the ignition ofy liquid fuels becomes increasingly difficult as the temperatures of the liquid fuel and combustion air are decreased. Part ofthe diiculty arises from the strong dependence of vapor pressure of such liquid; fuel upon the temperature. peratures spontaneous vaporizationmayoccur at such a low. rate that the resulting air fuel mix-,-

In the embodiment of the invention now being described, referring again to they drawing, fuell passed. through. the walls of the Vessel 23 is igniting elementr 28, bestr illustrated in Figure 6 of the drawing. This element comprises a heatc ing element 29 of asuitable resistance wire coiled about a sleeve 3l of Aan insulation material, suchl as asbestos, circumscribing a hollow metallic plug 32 formed with an enlarged head 33 at the lower end thereof. The upper surface of the head 33 may be formed with anv annulargroove or lslot in Which the lower edge of the sleeve'3I may be suitably anchored. One end of. the wire forming. the heating element 23 is permanently grounded to the head of the plug at 34. TheV other end passes. through the bore of the plug and-is intended to be'connected to a source of current, not shown.. The portion. of the` wire disposedv within.

thebore of the plug is spaced from the Wall thereof by suitable insulating element 35.

The plug 32 carrying the resistance or heating element 29 is threadedly mounted in a tappedy opening centrallykformed in a cylindrical boss 36 integral with. the wall of the combustion chamber I2.. 'To facilitate mounting. of the plug within the boss, the headed end of the plug is formed With an annular'flange 3T the'pe'ripheral surface of which may be knurled as indicated at 38.

The depth of the head 33V is such relative to the length of the boss 33 that the inner portion f of `the head projects beyond the inner surface of f the wall of the combustion chamber and is 1 threadedly received by. a tapped opening. formed openings formed at opposite endsof: the.` boss 25.

Iff desired,jor found necessary, the conduit 2.4 may be provided with a protective sheathV or othery means for protectingI the same fromV the temperature to be expected.

Fuel, under a pressure varying in proportion to the porosity of thematerial forming the Walls of the Vessel 23, is delivered into the vessel,the

interior vof Which may be provided with means in the bottom wall of a well 39. forming a part of a dish-like member 4I. The member II is partially held to the wall of the combustion chamber by the threaded engagement between the head of the plug and the tapped. opening in the bottom wall of the well 39 and partially by locating. bolts 42 insertable through openings formedr in the boss 36 and adapted to be threaded intotapped openings in the well 39, respectively. The bolts l2 beside holding the member 4I to the wall of the combustion chamber also locate the member, to align the opening in the lower wall of the well with the'opening in the boss 36. Thus` in assembling the member within thecombustion The varies 21, as will be apparent,

Ati low tem-A chamber the bolts 42 are passed through the openings in the boss 36 after which the projecting ends areA threaded into the opening in the wall of the well 39. The latter openings are so located relative to the large threaded opening in the lower wall of the well 39 that reception of the bolts 42 in their respective opening will properly align the large opening of the well with the opening formed in the boss 35. The plug can now be threaded into the bore formed by the aligned openings to complete the mounting of the member 4|.

To permit easy access to the plug the outer shell is provided with an opening slightly larger in diameter than the flange of the plug. This opening is formed so as to align with the opening in the boss 36 receiving the plug and is normally closed by a closure element 43 carrying a grommet 44 of some suitable insulating material for passing the resistance wire or lead of the heating element 29.

For reasons which will be hereinafter apparent, a gasket 45 may be mounted between the lower wall of the well 39 and the wall of the combustion chamber, as well as between the fiange 3l and th under surface of the boss 36.l

The member 4| in addition to the well 39, includes a relatively large but shallow pan 46 positioned so as tc catch fuel dropping from the in# jection device formed by the vessel 23. The lower wall of this pan is formed or provided with troughs or elongate depressions 4l of .varying lengths radially extending outwardly from the well 39. These troughs slope inwardly from their outer ends to the well so that fuel falling onto the pan gravitates into the well.

In operation, fuel is delivered to the injection device or vessel 23 under a pressure sufficient to cause the fuel to pass through the porous wall member or members of the vessel. In this initial stage of operation liquid fuel drops onto the pan 46 and flows through the troughs 41 to the well 39, The heating and igniting element 29, having previously been energized, heats the fuel held by the well thereby causing the same to vaporize. Fuel vapor rising from the surface of the fuel held by the well passes upwardly along the portion of the heating and igniting element above the surface of the fuel. This fuel vapor admixes with air as it travels upwardly along the element and is heated thereby to form an inflammable mixture which is easily ignited by the upper portion of the glowing wire of the element.

It will thus be seen that the element 29 actually performs three functions; first, the lowermost portion, that is, the portion immersed in the liquid fuel held by the well vaporizes this fuel; second, the intermediate portion of the element heats the fuel vapors rising from the surface of the fuel; and third, the upper portion ignites the heated fuel vapor-air mixture as it rises and fiows upwardly along the element. It is thus obvious that three separate elements could be used if desired. It has been found however that the single element under most conditions of use will properly function to bring about the results enumerated above.

It can be mentioned here that the element 29 could be formed of a plurality of short lengths of resistance wires of different operating characteristics suitably joined end-to-end to form a single path of resistance which would operate at different degrees of heat. Thus, for example, the upper portion of the element could be formed of a resistance wire which, when energized, would 8 attain a higher temperature than the remainder of the element.

To insure that the fuel vapors pass upwardly around the element, and are further heated thereby, a guard 48 in the form of an apertured or perforated sleeve may be mounted to the pan. The majority of the apertures provided in the guard are to admit air into the same although the primary purpose of theY apertures provided at the lower edge of the guard is to insure that fuel caught by the pan 46 and flowing along the troughs 41 can pass through the guard into the well 39. This guard, as best shown in Figure 6, forms a flue or chimney which draws the heated fuel vapors upwardly around the element 29 and also prevents combustion air delivered into the combustion chamber through the opening 2| from carrying the vapors away from the element.

It should be noted that combustion air in addition to that delivered through the opening 2| may be necessary. In such event an additional opening can be provided in the wall I4 of such as the opening shown at 49. It is to be understood that further openings can be provided if found rnecessary because of the fuel-air ratio used or flame pattern desired in the combustion chamber proper.

The ignition in the region of the ignitor 28 and combustion of the fuel-air mixture over the well 39 serves as a pilot flame to initiate combustion of fuel on the surface of the fuel injecting device 23. Once combustion at the injector-burner 23 has been established, there is little likelihood of the flame being extinguished. This is due in part to the fact that fuel vaporization and air-fuel vapor intermixing takes place within the burner formed by the vessel 23 or at the exterior surface of the same or both locations. In short, the burner itself furnishes fuel to the combustion chamber in the physical state most conducive to efficient burning, that is, as a vapor. Thus, there is no necessity for pre-carburetion of the fuel nor for altering the physical status of the fuel, such as atomization, prior to delivery of the fuel to the combustion flame Zone.

`The vessel also functions as an efficient flame holder for, referring now to Figure 2, combustion air is directed against the back surface of the vessel adjacent the opening 2| and swirls around the front or downstream surface. The translational velocty of the air moving over the front surface of the vessel is relatively low although the absolute velocity may be high. Such a moving air pattern is favorable to a stable flame and a flame front attaches and holds to the downstream face or surface of the vessel, whence the translational component of the air velocity carries the ame into the main combustion chamber.

The vessel also will function as a name keepalive particularly where a material such as a ceramic having a low heat capacity and thermal conductivity is used to form the vessel. If a metal-is used to form the vessel, a button or even a ring of ceramic can be mounted to the vessel to increase the flame keep-alive action. Such a keep-alive is shown at 5| in Figures 2 and 3.

In this connection it can also be pointed out that flame keep-alives can be mounted to the pan 46 if desired. There is shown at 52 one form of a keep-alive which can be used with the pan. This keep-alive, somewhat T-shaped, is formed of any material desired, which has a low thermal capacitance and can be mounted to the pan by fusion or other mechanical connection. It should be obvious now that the pan 46 itself is initiated a large portion, if not all, Iof the fuel caught by the pan is readily vaporized and burned from the pan. With a high rate of fuel supply, the pan may serve as an auxiliary vaporizing and flame-holding surface, as well asa keep-alive, in a much more effective way than the relatively cold wall of the combustion chamber.

The B. t. u.s supplied bythe heater of the present invention may be variedby independent or simultaneous variation yof the rate of air or fuel flow, either or both yof which may be varied by conventional means which have not been shown. It has been found that the permissible over-all air-fuel vratio may vary over an extremely Wide range. Furthermore, combustion with any airfuel ratio betweenlOzl and 200:1 is `smooth and extremely efficient. f

,It has also been found that the velocity of combustion air supplied to the combustion cham ber can be varied within an extremely wide range yof velocities. The air velocity maybe that for just perceptible motionfor example one (l)A foot per second or it may .be as yhigh as will allow combustion within kthe combustion charnber. As the velocity of the air may be varied obviously the pressure head under which the air is supplied to the combustion chamber may also be varied.

There is shown in Figure 7 4a section of a modil fied form of the combined fuel injector and burner 23. In the form of the burner there shown the vessel 54 is formed in the same manner and of the same materials as was the vessel 23. plane normal to the plane ofthe 'section shown by Figure 2 and as the interiors of the vessels 23 and 54 are identical the showing of Figurer? also can be used to more clearly illustrate the position and function of thevanes 2'1. i f

The `vinjector` and burner formed by the `vessel 54 differs from the previously described vessel 23 in that a downwardly projecting funnel-like element 55 is integrally formed with the lowermost wall section of the vessel 5 4. This funnel-like element 55 is formed with anA opening 56 at its lower end which serves -as a discharge vent for liquid fuel during the initial operation of igniting the fuel. As liquid fuel enters the vessel 54 and flows downwardly therethrough it is collectedby the element 55 and then discharged through the opening 5B directly onto the heating element and into the well 39. f

-in 'Figui-.esiti through `10, yidentical in form and jector-burner 23. Thef-.unnel-'like element'55 of ther injector-'burner 15.4 `projects downwardly :through an opening `formed in a hood-like shield 58 carried `:by the l-pan 4|. This 4shield y58 extends upwardly .overthe well 39 and resistance element 29 and rvat least fat the one side thereof, extends outwardly .and upwardly Aover an igniting element .59 mounted v.tocthe wall of the combustion chamber jl2. Although the igniting-element 59 maytake various forms, in the illustrated embodiment of the heater herein'shown, this element comprises aglow coil yconsisting of a coiled The section of Figure '7 is taken along a Accordingly, the vapor forming and fuel vaporair admixing steps of the .method of igniting the fuel is speeded by the use of the injection burner of .Figure 'I for it is not necessary for the liquid fuel to pass through the walls of the burner and be collected and then channeled by the pan 4l into the well 39. Y n

There is shown in Figures 8 through 10 a modified form of the heater of vthe present inventionr in which many of the elements are the 'same as elements in the embodiment of the invention` earlier described. For thesake of brevity, ele-v length of `resistance wire .6I carried bya suitable support 62 of some insulating material. The one end ofthe wirel. is ygrounded to a. metallic threaded plug 63 to .which is mounted the support =B2,--while 'the opposite end of Lthe wireis fastened to a lead tov permit the wireto be connetted toasource of current. `The element l59 is mounted tothe wall iof the :combustion chamber "I2 'bythread-ing the plug '63 into a tapped opening formed in aboss 54 lformed integrally with the wall-of the combustion chamber. T'o facilitate mounting of the elementf59 lthe plug 63 is formed at vthe one end thereof Awith ay head 66 invention. As the glow coil v59 is an igniting element the temperature of the wire 6I obviously must be such as to -ignite the mixture formed by the heated fuel vapors arising from the coil 29 and commin'gling with ycombustion air under the hood orlshield.

The shield 58 may take various forms so long i as'it protects the glow'coil59 from cooling effects produced by incoming combustion air entering the combustion chamber through the opening 2 l. Although the guard 48 previously described has been ksho-wn in the illustrated embodiment of the form ofthe invention now being described, it

has been found that this guard is not always necessary in this embodiment of the invention and may be removed if desired.

The heater of the. embodiment of Figures `8. through l0 operates substantially Vin the same mI form a combustible mixture `as they commingle l with combustio-nair flowing under the hood or Shield 58. As this vcombustible kmixture flows up# wardly .over the 'igniting Acoil 59 it is ignited and the resulting 'flame heats the injector-burner .54 toirase thetemperature of the same .to a degree vof heat sufficient to vaporize the liquid fuelv supplied to the same. The combustible mixture formed by the fuel vapors flowing'from the injector-burner admixes with the combustion air to produce a primary combustible mixture which, when ignited by the burning fuel-air mixture just described, forms a primary combustion flame at the injector-burner. This primary combustion flame further heats the injector-burner so that, 'as in the earlier described embodiment, the burner itself furnishes fuel to the combustion chamber in the physical state most conducive to efficient burning, that is, as a vapor.

It should be obvious that the injector-burner 54, in this embodiment of the invention now being described, also functions as a flame holder in the same manner as does the injector-burner 23. The injector-burner 54 also can be supplied with a keep-alive similar to the keep-alive l of the injector-burner 23.

There is shown in .Figure 11 a. still further modified form of the injector-burner. In this embodiment, the burner comprises a dish-like member 68 open at the one side thereof. The open side of the member is closed by a transverse wall element comprising a pair of plates 69 and 1| held in a facewise engagement. The adjacent or contacting faces of the plates are each formed with half-round grooves which form, when the plates are mounted across the opening of the member 68, a spirally-shaped course, circular -in cross-section, for receiving a suitable electrical resistance wire 12. This Wire is connected to a source of current (not shown) through a lead 13 carried within a protecting sheath 14 which may be supported by the conduit 24.

The plates 69 and 'H forming the transverse wall closing the open side of the member 68 are porous or foraminous so that liquid fuel supphed to the interior of the injector-burner will flow, either by capillary action or because of pressure on the fuel, through the Wall formed by the plates 69 and l I. This material, of which the plates are formed, preferably has a low heat capacitance, as well as a low thermal conductivity, so that the heat transferred thereto by said resistance wire 12 will cause the wall to attain a relatively high temperature. The heat of the wall will also raise the temperature of the remainder of the burner and the combined action of the relatively hot wall and the heated remainder of the burner will readily vaporize the fuel permeating the wall. The fuel vapors issuing from the wall will readily mix and commingle with combustion air flowing past and around the burner to form a combustible mixture ignitable by either the relatively hot wall of the injector-burner or by a separate ignition element mounted adjacent the injector-burner.

Although, in the illustrated embodiment of the injector-burner shown in Figure 11, only the Wall formed by the plates 69 and 'H is shown as foraminous, it is to be understood that all wall members may be formed of a material which will permit now of the fuel and its vapors.

Although the now preferred embodiments of the present invention have been illustrated and described herein, it is to be understood that the invention is not to be limited thereto, for it is susceptible to changes in form and detail Within the scope of the appended claims.

We claim:

1. In an internal combustion heater, means forming a sealed horizontally disposed combustion chamber having inlet and outlet passageways at opposite ends, blower means connected t0 said inlet passageway for supplying a now ofA air through said combustion chamber, a fuel conduit extending into said chamber near the end having the inlet passageway, a fuel vaporizing burner having a substantially vertical wall disposed transverse of said air flow and supported on said conduit, fuel conducting means arranged to conduct fuel from said conduit to a downstream face of said wall exposed to said combustion chamber, said wall being adapted to permit liquid fuel to drip therefrom, a fuel igniting structure located below and out of contact with said burner wall and embodying a pan positioned to collect raw fuel dripping from said burner when initially delivered thereto by said conduit and when said burner is cold, an electrically energizabie glow coil extending into said pan in position to heat to vaporization the fuel collected therein| and means for shielding said vaporized fuel adjacent to said glow coil from said flow of air while supplying an amount thereto sufficient to form a combustible mixture, said shield directing the flame into heat transfer relationship to the burner wall whereby the fuel is vaporized on the downstream face thereof and burned when mixed with the air flowing through said combustion chamber.

2. In an internal combustion heater, means forming a sealed horizontally disposed combustion chamber having inlet and outlet passageways at opposite ends, blower means connected to said inlet passageway for supplying a flow of air through said combustion chamber, a fuel conduit extending into said chamber near the end having the inlet passageway, a fuel vaporizing burner having a substantially vertical wall disposed transverse of said air flow and supported on said conduit, fuel conducting means arranged to conduct fuel from said conduit to a downstream face of said wall exposed to said combustion chamber, said wall being adapted to permit liquid fuel to drip therefrom, a fuel igniting structure located below and out of contact with said burner and embodying a pan positioned to collect raw fuel dripping from said burner when initially delivered thereto by said conduit and when said burner is cold, an electrically energizable glow coil extending into said pan in position to heat to vaporization the fuel collected therein, means for shielding said vaporized fuel adjacent to said glow coil from said flow of air while supplying an amount thereto sufficient to form a combustible mixture, said shield directing the flame into heat transfer relationship to the burner whereby the fuel is vaporized on the downstream face thereof and burned when mixedv air through said combustion chamber, a fuel con-4 duit extending into said chamber near the end having the inlet passageway, a hollow fuel vaporizing burner having at least onefuel pervious substantially vertical wall disposed transverse of said air flow adapted to permit liquid fuel to drip therefrom and supported on said conduit with the downstream face of said wall in position tosupport a flame, said conduit being arranged to deliver fuel to the interior of said burner, a fuel igniting structure located-below and out of conlas tactil/itil said burner embodying a pan Aposineutri tofcoll'ect raw fuel dripping from saidkburner when initially deiiveredlihereto-by saidfc'onduit air while suppl-ying an amount thereto sumcient to form a combustible mixture, saidY shield directing the vflame into heat transfer relationshipito lthe burner whereby the fuel isvaporizedonv said downstream face and burned when mixed with the air flowing through said combustion chamber, the portion of said glow coil out of contact with said raw fuel being disposed in position to ignite said vaporized mixture.

4. In an internal combustion heater, means forming a sealed horizontally disposed combustion chamber having inlet and outlet passageways at opposite ends, blower means connected to one said passageway for producing a flow of air through said combustion chamber, a fuel conduit extending into said chamber near the end having the inlet passageway, a flat fuel vaporizing'burner supported on said conduit and having a wall disposed in a vertical plane transverse to said flow of air and adapted to permit liquid fuel to drip therefrom, means for directing fuel from said conduit to the downstream face of said Wall so that vaporization and burning will occur on the downstream side of the burner relative to said flow of air, a fuel igniting structure located below said burner and embodying a pan positioned to collect raw fuel dripping from thebottom of said burner which is delivered thereto from said conduit when said burner is cold, an electrically energizable means mounted within the combustion chamber and located in such relation to said pan as to heat to vaporization the fuel collected therein, means mounted within said combustion chamber adjacent .to said energizable means for shielding said vaporized fuel from said flow of air while supplying an amount of air thereto to form a combustible mixture, and a second energizable means located adjacent to said pan for igniting said mixture.

5. In an internal combustion heater, means forming a sealed horizontally disposed combustion chamber having inlet and outlet passageways at opposite ends, blower means connected to one 'said passageway for producing a ow of air through said combustion chamber, a fuel conduit extending into said chamber near the end having the inlet passageway, a flat fuel vaporizing burner supported on said conduit and having a wall disposed in a vertical plane transverse to said flow of air and adapted to permit-liquid fuel to drip therefrom, means for directing fuel from said conduit to the downstream face of said wall so that vaporization and burning will occur on the downstream side of the burner relative to said flow of air, a fuel igniting structure located below said burner and embodying a pan positioned to collect raw fuel dripping from the bottom of said burner which is delivered thereto from said conduit when said burner is cold, .an electrically energizable means mounted within the combustion chamber and located in such relation to said pan as to heat to vaporization the fuel collected therein, and means mounted within said combustion chamber adjacent to said energizable means for shielding said vaporized fuel from Isaid flow of air While supplying an amount of air thereto to form a combustible mixture,

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said shielddirecting the .flame from the ignitin'g' porized, mixed with air and burned so that no Yfurther fuel is delivered to said pan, saidener- A'.'gizable means'beinga glow-coil `which is partially immersed 'by the fluid collected in the pan for jheating said `fluid `to vaporization, the part extending Aabove the fluid being available to 4ignitey the vaporized jxnixture.l f

*6. =In an 'internal combustion heater., means forminga' sealed horizontally disposed combustion chamber having inlet and outlet passageways at opposite ends, blower means connected to one said passageway for producing a flow of` air through said combustion chamber, a fuel conduit extending into said chamber near the end having the inlet passageway, a flat fuel vaporizing burner supported on said conduit and having a wall disposed in a vertical plane transverse to said flow of air and adapted to permit liquid fuel to drip therefrom, means for directing fuel from said conduit to the downstream face of said wall so that vaporization and burning will occur on the downstream side of the burner relative to said flow of air, a fuel igniting structure located below said burner and embodying a pan positioned to collect raw fuel dripping from the bottom of said burner which is delivered thereto from said conduit when said burner isfcold, an electrically energizable means mounted within the combustion chamber and located Ain such relation to said panas to heat to vaporization the fuel collected therein, means mounted within said combustion chamber adjacent to said energizable means for shielding said vaporized fuel from said flow of air while supplying an amount of air thereto to form a combustible mixture, said shield directing the flame from the igniting structure into heat transfer relationship to the burner whereby the fuel delivered thereto is vaporized, mixed with air and burned so that no further fuel is delivered to said pan, said energizable means being a glow coil which is partially immersed by the fluid collected in the pan for heating said fluid to vaporization, the part extending above the fluid being available to ignite the vaporized mixture, said pan sloping toward a well therein through which the glow coil extends which heats the initial flow of oil as it collects thereabout, said glow coil being removable from said pan exteriorly of the combustion chambenvanes extending from said combustion chamber longitudinally thereof, and an outer casing surrounding said chamber and engagingl the outer ends of said vanes for forming longitudinal air passages extending from one to the other end of the combustion chamber.

ERNST H. PLESSET.

WILLIAM R. ELSWICK.

PAUL A. PALMER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date f 428,334 Field May 20, 1890 722,163 Stoermer 1 Mar. 3, 1903 986,067 Klein Mar. 7, 1911 1,032,811 Brookblank July 16, 1912 1,174,113 Beatty Mar. 7, 1916 1,307,797 Squires et al 1 June24, 1919 1,329,052 Lukaszewski Jan. 27, 1920 `1,646,503 Steward Oct. 25, 1927 (Other references on following page) Number UNITED STATES PATENTS Name Date Hansen Oct. 9, 1928 Goldsborough June 28, 1932 Harrington May 1, 1934 Roe Dec. 24, 1935 Brace Oct. 3, 1939 Farrell Feb. 1, 1942 Holthouse June 16, 1942 10 Hourvtz Apr. 17, 1945 Hess Oct. 9, 1945 Number Number 16 Name Date' Lowell Feb. 11, 1947 Trimble et al July 20, 1948 Smoot Aug. 17, 1948 McMichael Mar. 22, 1949 Parrish June 28, 1949 McCollum Dec. 27, 1949 Tramontn Jan. 17, 1950 FOREIGN PATENTS Country Date France Jan. 7, 1931

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