US2374203A - Heater - Google Patents

Description

April 24, 1945.

H. AE.. 'HQLTHOUSE HEATER Filed Aug. 50, 1941l 3 Sheets-Sheet 1 Amin 24, 1945. H. B. HoLTHUSE x 2,374,203

HEATER Filed Aug. 50, 1941 5 Sheets-Sheet 2 y: y I i," Milf/ pri 24, 1945. H B HHQLTHOUSE 2,374,203

HEATER Filed Aug. 30, 1941 3 Sheets-Sheet 3 i a? g.

Patented Apra 24, i945 HEAT orricsi Harry B. Holthouse, Chicago, Ill., assigner to Galvin Manufacturing Corporation, Chicago. Ill., a corporation o Illinois l2 Claims.

This invention relates generally to heating sys tems and in particular to a heating system of internal combustion type operated in conjunction with an internal combustion engine.

t is an object of this invention to provide an improved heating system.

Another object of this invention is to provide an air heater of internal combustion type assembled as a portable unit with an internal combustion engine and utilizing such engine as the sole source of power supply.

n further object oi this invention is to provide a heater of internal combustion type operated on liquid fuel and in conjunction with an internal combustion engine, in which the fuel is substantially completely vaporized for burning in the heater by utilization of the engine waste heat.

Yet another object of this invention is to pro vide a heater of internal combustion type operated on liquid fuel, in which the fuel is introduced with air into a conditioning portion having heat projected thereon to heat the same to a fuel vaporizing temperature to provide for a thorough mixing of the air and fuel therein.

A still further object 'of this invention is to provide a portable air heating system comprised vof a heater of internal combustion type operatively assembled with an internal combustion engine as a source of power, which is compact and simple in design, rugged in construction, light in weight, and capable of producing heat quickly and emoiently.

A particular feature of this invention is found in the provision of a heater of internal combustion type using liquid fuel andsadapted for operation by an internal combustion engine, in which the heat in the engine exhaust gases is used to vaporize the liquid fuel to condition it for mixing together with the air for combustion.

Another feature o1" this invention is found in the provision of a heater of internal combustion type operated by an internal combustion engine,

in which the burner' fuel is initially vaporizedby the heat of the engine exhaust gases for mixing together with air, with the air and fuel mixture then being mingled with the exhaust gases for burning together.

Further objects, features, and advantages of this invention will become apparent from the following description when taken in connection with the accompanying drawings in which:

Fig. 1 is a view in perspective of a complete assembly of one form of this invention with parts thereof removed and other parts shown in section for the purpose of clarity;

Fig. 2 is a fragmentary transverse sectional view of the heater combustion chamber as seen along the line 2 2 in Fig. l;

Fig. 3 is a fragmentary sectional view showing the assembly of the heater fuel conditioning unit with the exhaust conduit of the internal combustion engine;

Fig. e is a sectional view taken along the line l--e in Fie. 3;

Fig. 5 is a sectional plan view as seen along line 5--5 in Fig. 3; l

Fig. 6 is a fragmentary sectional view showing the tail pipe assembly at the outlet of the heater combustion chamber. l

Fig. 'l is a fragmentary sectional view of a modied form of the invention;

Fie. 3 is a sectional view along line i--S in Fig. 9 is a fragmentary sectional view' of yet I another modication oi the invention;-

Fig. lo is a sectional view taken along the line `lenient-ias; ein

Fig. 11 is a sectional view as seen on line l l-l l in Fig. 9.

En practicing this invention there is provided as a portable unit, an air heater of internal combastion type and an internal combustion engine which produces all oi the power for operating the heater. liquid fuel for burning in the heater is introduced with air into a fuel conditioning unit or mixing device, the heat from the engine exhaust gases being utilized to heat the condition= ing unit and vapori the fuel for mixing together with the air. This vaporous mixture is admitted into a combustion chamber where it is mingled with the exhaust gases for burning therewith. The air to be heated is circulated in a heat-transf fer relation about the combustion chamber, the entire unit being capablel of mounting on skids or a carriage so as to be easily transportable from place to place to deliver heated air whenever it is desired.

Referring to the drawings; there is shown in Fig, 1 one form of the invention which inciudes an internal combustion engine having an engine block iii, an air-cooled cylinder il cooled by a fan l2, an intake manifold I3, an exhaust conduit It, and a crank shaftv I6. The nengine operates an air heater or burner and is assembled therewith as a complete operating unit which may be mounted on a carriage or the like (not shown) so as to be easily moved about to furnish heated air wherever it is necessary, as for example to heat airplane engines to facilitate their starting, or to heat tents, barracks, cabins, or the like.

The heater includes a housing comprising a longitudinally extending cylindrical portion I1 and an integrally formed L-shaped radially extending portion I8 at one end I9 thereof, the end .assembly with the housing cover plate 2|, the air chamber 23 ybeing formed within the member 21.

A partition member 28 of substantially' crossshape (Figs. 1 and 2) is positioned within and axially of the chamber 22 and is of a construction to divide the chamber into four axially extending but connected passages 29a-29d.` The member 21 is formed in the bottom portion 21a thereof with openings in communication with the passages 29a and 29d to provide an inlet 3| and an outlet 32 for the connected passages and hence for the combustion chamber. The wall of the combustion chamber 22 is integrally constructed with alternately arranged peripheral portions 33 and radially extending iins 34 (Fig. 2). The fins 34 are bent double with their inner ends 36 opening into the combustion passages 29m-29d. The partition member 28 is positioned within the open inner ends 36 of certain of the fins 34 and is retained in a fixed relative position Within the combustion chamber 22 as by welding. The housing portion I1 fitsabout the outer ends 31 -of the iins 34 to form an annular passage 38 about the combustion chamberv 22, the end 39 of the housing portion I1 extending outwardly of the combustion chamber 22 and being of funnel shape to provide a discharge or outlet opening 4| for the passage 38..

As is evident from Fig, l, the iins 34 are coextensive in length with the combustion chamber 22, with the air passage 38 being extended to the housing cover plate 2| by the cup-shaped member 21. The air passage 38 is in communication with the fan compartment 24 through a passage 46, the fan 41 located in the compartment 24 being mounted on the end 48 of the engine crank shaft I6 which extends through and is rotatably supported by a bearing 49 in the housing cover plate 2|. The bearing 49 is of a construction to seal the opening in the end 'plate 2| for the crank shaft |6. An air inlet for the fan 41 is formed in the housing portion I8. 'IIhe air to be heated is thus drawn by. the fan 41 through the inlet 5|, passed through the passage V38 in heat exfrom the combustion chamber 22 and the air passage 38 and is in communication with the fan compartment only through the passage 52.

As shown in Figs. 1 and 3 a portion 53 of enlarged section of the engine exhaust conduit I4 is located within the air chamber 23 in a position axially of the combustion chamber 22 and concentrically of the combustion chamber inlet 3|. The conduit portion 53 is of greater diameter than the inlet 3| so that the end 54 thereof is radially spaced about the combustion chamber inlet-,3| and in sealed engagement with the base portion 21a of the member 21. Supported by the conduit portion 53 is a fuel conditioning unit designated generally as 56, for preparing fuel for burning in the combustion chamber 22 with the exhaust gases from the engine.

Referring to Figs. 3, 4 and 5 the fuel conditioning unit 56 is seen to include a substantially tubalar housing 51 having a closed end 58 and an open end 59. The housing 51 is positioned within and axially of the exhaust conduit portion 53 and is radially spaced therefrom so as to be c0mpletely exposed to the exhaust gases passing therethrough. The open end 59 of the housing 51 is positioned within the combustion chamber inlet. 3| and seals such opening against any passage therethrough of exhaust gases from the exhaust conduit portion 53. An air and fuel mixing chamber 6| is located at the closed end 58 of the housing 51 and is separated from an equalizing chamber 62 therein by a partition plate 63 which extends transversely completely across the housing 51, the chambers 6| and 62 being in communication through perforations 64 formed in the upper portion of the plate 63. The housing 51 and partition plate 63 are composed of a heat conducting material such as copper or the like and are connected together in thermal relation. The equalizing chamber 62 is in turn separated from the lpassage 29a of the combustion chamber 22 by a heat insulating plate 66 which ,extends completely across the open end 59 of the housing 51 and is spaced inwardly thereof, the equalizing chamber 62 and the passage 28a being in communication through openings 61 positioned peripherally about the plate 66. Ad-

change relation with the ins 34 and discharged from the heater through the outlet 4|. A

The air chamber 23 within the member 21 is connected with the fan compartment 24 by a passage 52 which is separated from the air circulating passage 46 by a baille 50 integrally formed with the member 21 and extending to the periph- The baille 50 divides the air the fan 41 operates to supply both `the air for combustion and the air to be heated. Itis understood, of course, that lthef chamber 23 is sealed mission of the exhaust gases from the engine and specifically from the conduit portion 53 into the combustion chamber 22 is accomplished by means including a heating element or conduit portion 68 composed of copper or like material and extending .axially through the housing 51 and outwardly therefrom at both ends, the element 68 being supported in the closed housing end 5I, and partition plates 63 and 66. The end 69 of the heating element 68 which projects from the closed end 58 of the housing 51 is open to the exhaust conduit portion 53 so as to receive exhaust gases therefrom, these gases being discharged into the combustion chamber from the element end 10. The inlet end 69 is located to one-side of a, partition plate 1| extending longitudinally of the conduit portion 53 and about the projecting end 69 of the heating element 68 and housing 51. The end 12 of the partition mem-A ber 1| is in sealed engagement with the end 13 of the conduit portion 53, while itsother end 14 is spaced from the base portion 21a of the member 21 to form a vconnecting passage 16 between the compartments 11 and 18 of the conduit 53 on opposite sides of the partition member. The exhaust gases, as indicated by the arrows in Fig. 3, thus flow from the exhaustconduit I4 into the compartment 11 through passage 16 yinto against the stantially equal to the temperature of the exhaust gases in the conduit portion 53.

The air and fuel which is to be burned in the combustion chamber 22 with the engine exhaust gases is introduced into the mixing chamber 6| through an air and fuel receiver or nozzle 19 inserted through the wall o f the conduit portion 53 and mounted on the housing 51 so that the end 3l thereof is located in the air chamber 23. Fuel is delivered to the receiver 19 by a pump 82 illustrated as being of reciprocating type and operated from the engine crank shaft I6 through cam means B3. Connection of the pump with the engine fuel tank (not shown) but generally located in the base of the engine block lli is made through pipe 84, the fuel from the pump being delivered through pipe 86 to the nozzle 1S (Fig. 1).

As is shown in Fig. 3 the nozzle 19 includes a Venturi portion' 81 having peripherallyextending air ports or openings 83 near one end thereof which are in communication with the air chamber 23. The air entering the ports 88 and the fuel from the fuel line St are introduced together in the' Venturi portion 81 for discharge theren from into the -rnixing chamber 6l of the condition unit 56. Since the air in the chamber 23 is maintained under pressure by the fan il it is evident that an initial velocity is imparted to the air entering the Venturi portion B1 through the ports 33, so that the body of fuel entering the Venturi :portion 81 is partially broken up by the air prior to its passage into the mixing chamber tl.

In the operation of the invention the air and fuel from the venturi 31 are directed against an inclined Wall 89 of the mixing chamber 6l, integral with the housing 51 at the end 58 thereof and against that portion of the heating element 'S3 within the mixing chamber, for deflection partition plate S3. As previously mentioned the housing 51, heating unit E8 and of the housing 51 at the outlet end 59. This uniform distribution of the fuel mixture is further aided by a copper screen or the like 9| placed within the equalizing chamber 62 and across the openings 61 in the heat insulating plate 66. The mixture passing through the perforations 61 into the passage 29a of the combustionk chamber is thus of substantially uniform quality on entering the combustion chamber 22. This mixture is intermingled with the exhaust gases discharged from the outlet 10 of the heating or conduit element B8 for burning therewith in the combusltion chamber 22, ignition being initiated by a spark plug 32 arranged in the passage 29aat the combustion chamber inlet 3l, the plug 92' being electrically connected by a cable 93 to a coil (not shown) mounted on the engine and energized by the magneto (not shown) associated therewith. Additional air for supporting combustion in the combustion chamber 22 is admitted into the pas-v sage 29a through openings 9@ formed in the base portion 21a concentrically about the combustion chamber inlet 3| and connecting the passage 29a. with the air chamber 23.' Combustion proceeds through the passages 29e-29d, with the products of combustion being exhausted from the combustion chamber 22 through the outlet 32, the

y ilow of the gases through the passages in the combustion chamber being indicated by the varrows in Fig. 1.

As shown in Figs. l and 6 the outlet 32 is provided with a tail pipe 9d which projects outwardly therefrom into the air chamber 23. A second tail pipe 95 of larger diameter than the tail pipe 9d is inserted through the heater housing cover plate 2l into the air chamber 23, concentric with the tail pipe 94 butspaced therefrom.` The adjacent ends of the tail pipes 94 and 95 are thus both open to the air chamber 23. However, since the air chamber 23 is retained under pressure by the fan 41, air therefrom flows outwardly y through the tail pipe 95 to provide an ejector action on the exhaust gases owing in the tail i i pipe 34. This ejector action serves to reduce the back pressures in the combustion passages 29m-29d and facilitates the passage of the gases therethrough, the gases being discharged Y fromthe heater through the tail pipe $6.

plate E3 are heated by the engine exhaust gases v in the exhaust conduit portion 53, this heat being such that these parts are heated to a temperature which is capable of vaporizing the fuel coming in Vcontact therewith. The heating of Athese parts is facilitated by a perforated plug in the end 'it of the conduit 58, the plug acting to impede the ow of the exhaust gases and thus prolong their contact with the conditioningunit 5t. The fuel thus vaporized in the mixing chamber mixes together with the air introduced into the mixing chamber through -the venturi 81 and through the tubes T connecting the mixing chamber Si and airchamber '23, 'this vaporous mixture 'passing through the apertures 66' in the plate 63 into the equalizing chamber 62. The fue] is re- On starting of the heater, or at times during itsl operation it may happen that all of the fuel entering the mixing chamber 6| is not completely vaporized therein. In such instances the unvapcrized or raw fuel collects in a cavity or fuel carrying portion 91 at the bottom of the mixing chamber formed between the unperforated portion of the plate 63 and the inclined wall 89. By virtue of the heat in the walls of the cavity S1 any fuel collected therein is heated and vaporized for mixing togetherl with the air passing through the mixing chamber, this mix* ture entering the equalizing chamber in a vaporous form. In the event any raw fuel should form or nd its way into the combustion chamber 22, it collects in the cavities 9B (Fig. 2) in the fins 3Q through'the openings 36 therein, the heat in the lns vaporizing this fuel for later burning.v All of the fuel supplied to the heater is thus sub stantially completely vaporized so that burning thereof proceeds eiciently and uniformly at all times of heater operation. Since the` fan 41 supplies both the air for combustion and circulates the air to be heated, air is circulated through the passage 38 simultaneously with the starting of heater operation, it being understood that operation of the heater starts concurrently with the starting of the engine.

The modified forms of the invention shownin Figs. 7 and 9 are similar in all respects to the embodiment of Fig. 1 except for the relational assembly of the conditioning unit 56, the exhaust conduit portion 53 and the combustion chamber 22. Similar numerals of reference shall be used,

therefore, to designate similar parts throughout the various views.

In Fig. '7 the exhaust conduit portion 53 is eliminated and the conditioning unit 56 is located within the air chambery 23 with the open end 59 thereof positioned through the combustion chamber inlet 3| in communication with the passage 29a. The heating element 68 at the end 60 thereof is connected directly with the engine exhaust conduit I4 so that the exhaust gases are passed in a heat transfer relation therewith and discharged directly into the combustion chamber from its outlet end 'l0'. To facilitate the heating of the unit 68' radially extending fins |0| (Fig. 8) are provided therein over the portion thereof extending across the mixing chamber 6| and equalizing chamber 62. A transfer of heat from the exhaust gases in the element 68 to that portion,

` end 58 is Within the air chamber 23' air is intro-- duced from the air chamber directly into the mixing chamber 6| through ports |03 formed in the housing about the nozzle 19. This air and the air introduced into the mixing chamber with the fuel from the nozzle 19 is thoroughly mixed with the fuel in the mixing chamber due to its vaporization in the manner above fully described in connection with Fig. 1.

In the modification of Fig. 9, the exhaust conduit portion of 53a has its end 54a positioned within the combustion chamber inlet 3| so that the exhaust gases from the engine are discharged therefrom directly into the combustion chamber. The housing 51a of the conditioning unit 56a is located within the conduit portion 53a in spaced relation therewith. This form of the invention eliminates the 4heating element 68 of Fig. l so that the transfer of heat to the conditioning unit 56a from the exhaust gases in the conduit portion 53a is accomplished entirely by the passage of such gases about the housing 51a. The transfer of heat from these exhaust gases is aided by fins |05 (Fig. 10) annularly spaced about the housing 51a and extending longitudinally thereof, and fins |05a extending in an up and down direction, as viewed in Fig. 9, formed at the closed end 58a of the housing 51a.- The ow of exhaust gases through the conduit portion 53a is impededby the provision of an annular apertured flange |06 at the end 54a thereof, the flange being in sealed engagement with the outlet 59a of the conditioning unit 56a so that the apertures |01 in the flange |06 are positioned between the housing 51a and the wall of the conduit 53a. The outlet 59a of the conditioning unit 56a is provided with an annular projecting nose or extension 59h of heavier construction than the walls of the housing 51a and of a scalloped or fin contour on the inner periphery thereof. The nose 59h acts to collect and transfer heat from the mixture burning at the outlet 50a back to the housing 51a to aid thev heating function of the exhaust gases in the conduit 53a. The air and fuel introduced into the mixing chamber 6| is additionally mixed with air entering the chamber 6| from the air chamber 23 through the tubes T, the fuel being vaporized for mixing together with this air by its contact with the housing end wall 89a' and deection against the partition plate 63. The vaporous mixture leaving the conditioning unit at the outlet thereof is interminged with the exhaust gases from the paertures |0'Iand together are burned in the combustion chamber 22.

From a consideration of the drawings and above description it is seen that the invention provides for a unit air heater of portable type which is operated in conjunction with an internal combustion engine, and whichutilizes the power from such engine as the sole source of power supply. The exhaust heat from the engine is used in the operation of the heater to prepare a vaporous air and fuel mixture which is intermingled with the exhaust gases for burning therewith in the heater combustion chamber. The substantially complete vaporization ofthe fuel for the heater assures a complete burning thereof with a maximum production of heat and a practical elimination of noxious odors and visible exhaust. 'I'he engine and heater are assembled together in a compact unit which may be readily moved about to provide heated air wherever it is needed. The unit is thus readily applicable for use in an airport to heat airplane engines for starting purposes, in cabins, small workshops, and the like. The entire unit is simple in design and of a rugged construction tov withstand any rough handling thereof during its movement from place to place, without impairing its efficient operation.

Although the invention has been described with specific reference to several preferred forms thereo'f it is to be understoodthat changes therein can be made which are within the full intended scope of the invention as defined by the appended claims.

I claim:

1. A heating system including a burner and an internal combustion engine having an exhaust conduit, a combustion chamber means for said burner having an inlet at one end, an air chamberl means at said one end separated from said combustion chamber means, said exhaust conduit having ay portion thereof positioned in said air Achamber means, a passage means about said combustion chamber means for air tobe heated, air

moving means in uid connection with said air chamber means and passage means to supply ail thereto, air and fuel mixing means at said combustion chamber means inlet arranged in heat transfer relation with the exhaust gases in said conduit portion, means admitting air from said air chamber means into said air and fuel mixing means, and means for supplying fuel to said mixing means, with said fuel being heated -in said mixing means and vaporized for mixing together with the air therein, said vaporous mixture being passed through said combustionchamber inlet for burning therein.

2. A heater of internal combustion type utilizing an internal 'combustion engine as a. source of power supply, a combustion chamber means for said heater having an inlet, a fuel conditioning unit arranged 'with the outlet thereof in fluid communication with the inlet of said combustion said conditioning unit, with chamber means, means supplying air and fuel to said conditioning unit, an exhaust conduit for said engine having an end portion thereof positioned Within said conditioning unit and arranged to discharge the engine exhaust gases into said inlet, with the fuel in said unit being vaporized for mixing together with said supply air'by 'the heat from the exhaust gases in said conduit portion, said air supply means-- acting to move said vaporous mixture into said combustion chamber means for burning therein with the gases from said conduit portion.

3. A heater of internal combustion type adapted to be operated in conjunction with an internal combustion engine having an exhaust conduit, a

combustion chamber means for said heaterhav- 1 said air and fuel and to vaporize the fuel for mixing together with said air, with said air supvaporous mixture into said combustion chamber means for burning therein wtih said exhaust gases.

4. In a burner operated in conjunction with an internal combustion engine.' a combustion chamber means for said burner having an inlet, fuel conditioning means having' an outlet in communication with the inlet of said combustion chamber means, an exhaust conduit for said engine having a portion thereof positioned about said conditioning means, and a second portion extending through said conditioning means, with said second portion being arranged to discharge the exhaust gases from said engine through said inlet, means connecting together said two conduit portions, with said conditioning means being heated by the exhaust gases passing through said two conduit portions, and means introducing air and fuel into said conditioning means, with the fuel in said conditioning means being vaporized by the heat therein and mixed together with said air, With Said vaporous mixture and exhaust gases being intermingled at said inlet for burning together in said combustion chamber means.

5. In a burner of internal combustion type utilizing an internal combustion engine as the sole source of power supply, a ,combustion chamber means for said burner having an inlet, an exhaust conduit for said engine having one portion thereof adjacent said inlet but separated therefrom, a fuel conditioning unit in said one portion of the exhaust conduit having an outlet in communication with the inlet of said combustion chamber means, means extending longitudinally through said fuel conditioning unit uid connecting said exhaust conduit portion with said inlet, and means supplying air and fuel to the heat from the gases in said longitudinally extending means and vone conduit portion heating said conditioning unit to vaporize the fuel therein -for mixing together with said air, said air supply means acting to move said vapor-ous mixture into said combustion chamber means for burning therein with said exhaust gases. i

6. In a burner operated in conjunction with an ply means providing for the movement of said internal combustion engine, a combustion chamber'means for said burner having an inlet, a fuel conditioning unit having an outlet inv communicationwith the inlet of said combustion chamber means, an exhaust conduit for the exhaust gases from said engine having an end portion thereof positioned longitudinally through said fuel conditioning unit with the discharge opening thereof arranged at said outlet, means supplying .air and fuel to said conditioning unit, with the heat from the engine exhaust gases in said exhaust conduit portion heating the air and'fuel in said unit and vaporizing said fuel for mixing together with said air, said vaporous mixture being burned in said combustion chamber means with said exhaust gases.

'l'. In a ysystem having an engine with heated exhaust gases issuing therefrom and passage means therefor and having a heater with a fuel combustion chamber; the means for conditioning fuel for burning in the combustion chamber which comprises fuel and air mixing and mixture conveying means opening into the combustion chamber. and conduit means enclosing at least a portion of said mixing and mixture conveying means and opening into said combustion chamber, with said conduit means being connected with said passage means and receiving heated exhaust gases therefrom and discharging said heated exhaust gases into the combustion chamber.

8. In a system having an engine with heated exhaust gases issuing therefrdm and passage means therefor and having a heater with a fuel combustion chamber; the means for conditioning fuel for burning in the combustion chamber which comprises fuel and air mixingand mixture conveying means opening into the combustion chamber, first conduit means enclosing at least a portion of said mixingv and mixture conveying means and uid connected with said passage means to receive heated exhaust gases therefrom, and second conduit means extending Within said portion of said mixing and mixture conveying means open at one end to receive heated exhaust gases from said first conduit means and open at the other end to discharge said heated exhaust gases into the combustion chamber.

9. In an internalcombustion heating system which includes an engine provided with an exhaust and a heater provided with means defining a combustion chamber, a fuel conditioning unit comprising a pair of tubular members disposed one within the other to provide two spaces which are separated by the Walls of the inner member, perforated partition walls'dividing one of said spaces into an air and fuel mixing chamber and an equalizing chamber through which a mixture of fuel and air may be deliveredto said combustion chamber for supplying fuel and air to said mixing chamgases from said engine exhaust through the other of said spaces for the purpose of vaporizing the fuel supplied to said mixing chamber and trans mitted through said equalizing chamber to saidi combustion chamber.

10.` In an internal combustion heating system Whichincludes an engine provided with anexfhaust and a heater provided with means defining l fuel conditioning unit a combustion chamber, a comprising a plurality of tubular members disiposed one within the' other vto provide three coni-.f centrically arranged spaces, perforated partitionl v walls dividing the middle-one of said spaces into an air and fuel mixing chamber and a pressure;

from said mixing chamber, means equalizing chamber through which a mixture of fuel and air may be delivered to said combustion chamber from said mixing lchamber, means deiining an air pressure chamber which surrounds at least a part of said unit and communicates with said mixing chamber, air moving means for supplying air under pressure to said air pressure chamber, means for supplying fuel to said mixing chamber for mixing with the air therein and for transmission with the air through said equalizing chamber to said combustion chamber, and means for transmitting heated exhaust gases from said engine exhaust to said combustion chamber over a path which includes the outer one of said spaces and the inner one of said spaces, thereby to vaporize-the fuel supplied to said mixing chamber and transmitted with the air through said equalizing chamber to said. combustion chamber.

11. In an internal combustion heating system which includes an engine provided with an exhaustand a heater provided with means defining a combustion chamber having an inlet at one end, means defining an air chamber at said one end of said combustion chamber, air moving means for delivering air to said air chamber, air and fuel mixing means at least` partially disposed in said air chamber and provided at said combustion chamber inlet to discharge a mixture of fuel and air into said combustion chamber, means for delivering fuel to said mixing means, said air and fuel mixing means having at least one aaraaoe air admission opening through which air from said air chamber may be received therewithin for mixing with the fuel, and means communieating with said engine exhaust and disposed withinsaid air chamber for utilizing the heat -from the engine exhaust gases to heat the fuel during its mixture with the air in said mixing means and prior to admission of the mixture into said combustion chamber..

l2. In an internal combustion heating system which includes an engine provided with an exhaust and a heater provided with means defining a combustion chamber having an inlet at one end, meansdefining an air chamber at said one end of said combustion. chamber, air moving means for delivering air to said air chamber, air and fuel mixing means at least partially disposed in said air chamber and provided at said combustion chamber inlet, said lmixing means having an air and fuel mixing space therein which communicates with said air chamber to receive air therefroml and 'also Vcommunicates with said combustin chamber, means for delivering fuel to said mixing chamber, and conduit means communicating with said engine exhaust and having a portion disposed within said mixing space for utilizing the heat from the engine exhaust gases to heat the fuel during its mixture with the air in said mixing means and prior to admission of the mixture into said combustion chamber.

HARRY B. HOLTHOUSE.

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