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I Nov. 26, 1946. H. J. DE N. MCCQLLUM _ 2,41 1,581 FUEL SUPPLY SYSTEM ' Filed my 17, 1944 4 Sheets-Sheet 1 Nbv. 26, 1946; H_ J_ DE N, MccQLLUM " 2,411,581 FUEL SUPPLY SYSTEM > Filed May 17, ‘1944 _ A Sheets-Sheet 2 NOY- 26, 1946- I H. J. DE N. MccoLLuM ’ _ 2,411,581 FUEL SUPPLY SYSTEM , (‘e1 ‘ “I | L Q Q glldl *w -<:. ~ 1 ‘ \ ------ -4NI’ _ . JO 20 /_'_ . Li; 3 "I. I ‘II / I _ .I Nov. .26, 1946. "H. ‘J. DE N. McCOLLUM 2,41 1,581 FUEL SUPPLY SYSTEM Filed May 17, 1944 4 Sheets-Sheet 4 Patented Nov. 26, 1946 2,411,581 ' ’ UNITED. STATES PATENT OFFICE’ ‘ FUEL SUPPLY SYSTEM Henry J. De N. McCollum, Chicago, Ill.: Thelma McCollum, executrlx of said Henry J. De N. McCollum, deceased, asslgnor to Stewart- Warner Corporation, Chicago, III._, a corpora I tion of Virginia Application May 17, 1944, Serial No. 535,902 8 Claims.‘ (Cl. 126-116) My invention relates to fuel supply systems and self-contained heater adapted to be secured to -. more particularly to fuel supply systems for in ‘ temal combustion heaters of the kind used on aircraft. _ the skin of an aircraft or to a panel which is mounted in a- window opening or other opening in an aircraft wall. This heater comprises a sheet metal housingv I ll secured to a wall 12 of an aircraft cabin, or to a panel which may be in Internal combustion heaters used on aircraft are subject to variation in operation resulting from changes in altitude of the aircraft and re serted ina window openingor other opening in suiting changes in the fuel mixture supplied by such a wall, The wall I2 is provided with open the ordinary carburetor under these varying con ings through which the ventilating air ram i4 and ditions of altitude. Numerous and various expe 10 exhaust pipe l6 project. A ring it surrounds the dients have been adoptedrin order to provide a opening for the ventilating‘ air, and screws 20 fuel feeding system for such heaters to overcome extend through this ring, wall I! and housing Ill, this objection to the ordinary carburetor. These and engage nuts 22 attached to the inner wall of various expedients are frequently complicated, expensive, cumbersome, heavy, require frequent ,adjustment or repair, or are otherwise objec tionable. . this housing. A second ring 24 surrounds the opening for the exhaust pipe, and screws 26 ex tend through this ring, wall l2 and housing It, and engage nuts 28 attached to the inner wall of An object of my‘ invention is to provide a new this housing; An asbestos or other suitable gasket and improved fuel supply system which is simple, may be interposed between' the wall i2 and I inexpensive, compact, lightweight and capable of 20 ‘30 housing iii. providing a uniform mixture of fuel and air under varying conditions of altitude and speed. Another object of my invention is to provide a fuel supply system having new and improved A heat exchanger, indicated generally by ref erence character 32, is located in the housing It! and is mounted on partitions 34 and, 36, which form supports for this heat exchanger and also means to prevent ?ooding. ' .25 serve to direct air ?ow therethrough. A cylindri Another object of my invention is to provide cal combustion chamber 38 is- attached to one a fuel supply system which automatically com; end of the heat exchanger 32 by way of a ?aring pensates for variations in altitude and which may (throat 40 and supplies the tubes 42 of the heat‘ readily be applied to existing aircraft heaters. exchanger with hot products of combustion. Another object of my invention is to provide 80 After these products of combustion have passed a new and improved altitude compensating fuel lengthwise of the tubes 42 and have given up supply system whichcan readily be built into air substantially all of their heat, to these tubes and craft heaters without appreciably increasing their to inlet header 44, the cooled products of com size, weight or cost. or in any wise detracting .- bustion enter an exhaust manifold 48 and pass ‘from their normal operation. 86 therefrom into exhaust pipe it. g In addition to Other objects and advantages will become ap the inlet header 44, the heat exchanger alsoin parent as the description proceeds. cludes an outlet header 48, the tubes 42 being In the drawings: ' ‘ mounted inboth of these headers. Fig. 1 is a longitudinal vertical section through When the aircraft is in motion, the ram M sup an aircraft heater to which my inventionhas 40 plies ventilating air to a space 50 surrounding the been applied. ‘This ?gure is taken on the line combustion chamber 38. This ventilating air i-l of Fig. 2:‘ Fig. 2 is a transverse vertical section taken on ?owsv horizontally through ' the space 50 and ‘ around the combustion chamber 88 and absorbs Fig. 3 is a horizontal section taken on the line heat from the walls of this combustion chamber. This ventilating air then ?ows into an elongated chamber 52 at one side of the heat exchanger the line 2-2 of Fig. 1; 3-; of Fig. 1; Fig. 4 is a partial vertical longitudinal section of a modi?ed form of my invention; and 32, and thence horizontally through the heat ex I Fig. 5 is a top plan view of the modified‘ heater changer to a corresponding chamber 54 on" the installation of Fig. 4 showing in cross section the 60 opposite side thereof. The ventilating air ab wall or other support to which the heater is at sorbs heat from the heat exchanger as it passes tached. > ‘ Theparticular embodiment of my invention which I have illustrated in the drawings of this thereover,‘ and this heated ventilating air ‘?ows from chamber 54 into a space 56 surrounding the exhaust manifold 46. The ventilating air passes application is shown as being applied to-a unitary, 65 fromthe space“ into the aircraft cabin or other 2,411,581 ‘ 3 space to be heated by way of an outlet, 60 provided in an end wall of the housing Ill. The heat exchanger 32 is illustrated as having thick header plates’ 44 and 48 and tubes 62 having thick walls and as being of the type described more fully and claimed in my copending appli cation Serial No. 516,648, filed January 1, 1944. The self-contained, unitary heater which I .have described is like that disclosed and claimed in my copending application Serial'No. 516,649, filed January 1, 1944. Combustion air is admitted through a second ram 62 formed by the curved inlet end of a com bustion air pipe 66. The ram 62 is located in the , As ‘the aircraft changes altitude, the pressure of the combustion air delivered to the vVenturi tube will change and the mass of air ?owing through this tube in a given time will likewise . change. The fuel vapor delivered to the jet ‘I6 is subject to the same pressure variations caused by altitude changes as the combustion air with whichthis vapor is to be admixed. The density of both gases varies with variations in this pres sure, and the proportions of fuel and air in the combustible mixture formed in the Venturi tube .10 remain the same for all changes in altitude. The internal combustion heater, therefore, oper ates ef?ciently and evenly at all altitudes. In this connection, it will be noted from Fig. 1 that the top of the coil I06 is at substantially same opening in the aircraft skin I2. The com the same elevation as the top of the liquid in bustion air pipe 64 extends transversely of one the ?oat bowl 90, so that the liquid head in _ end of the combustion chamber 38, whereby com this ?oat bowl is not relied upon to supply fuel bustion air ?owing through this pipe is preheated, to the Venturi tube ‘I0. That portion of the tube 20 before being mixed with fuel, to form a com I04 between the coil I06 and Venturi tube ‘I0 is bustible mixture. The other end 66 of the com inclined upwardly to a slight extent so that the bustion air pipe 64 communicates with an elbow rate of vapor delivery by the jet ‘I4 is solely a “which delivers the preheated combustion air function of the vacuum created at the throat tothe inlet end of a Venturi tube 10 formed in of the Venturi tube by combustion air ?owing a casting ‘I2 attached to one wallof the combus therethrough. tion chamber 38. A fuel jet ‘I4 delivers fuel Air ?ow into the rams I4 and 62 is produced vapor to the throat of the Venturi tube 10 where by forward motion ‘of the' aircraft relative to this fuel vapor is mixed with combustion air to the air through which it is traveling. The greater form a combustible mixture. The outlet end of the speed the greater the quantity of air deliv 30 the Venturi tube ‘I0 is connected to an induction ered by these rams and the greater the pressure tube 16 having a curved outlet end ‘I8 located at which this air is delivered. The pressure at in the combustion chamber. This combustible the air inlet of the Venturi tube ‘I0, therefore, mixture is ignited by an electrical igniter 80 varies not alone with variations in altitude but having a hot wire 82 located in a pocket 84 pro vided by the casting ‘I2 and communicating with 35 also with variations in air speed of the aircraft to which the heater. is attached. All variations the combustion chamber 38 by way of passages in pressure at the air inlet of the Venturi tube 86 and 88. ‘ are transmitted to the ?oat bowl 00 by pipe I00, A novel aspect of my invention resides in the so that the pressure ',on the fuel thereinchanges fact that vaporized fuel, instead of liquid fuel, is with the variations 5in pressure at the Venturi supplied to the jet ‘I4. This vaporized fuel is 40 tube inlet, regardless of whether these pressure subject to the same variations in pressure caused variations are caused by changes in altitude or by altitude changes as is the combustion air changes in air speed, or both. My novel‘ fuel which creates the suction in the Venturi tube to supply system is, therefore, compensated for draw vaporized fuel thereunto. .I shall now de changes in both air speed and altitude ,and 45 scribe the mechanism by which the foregoing delivers a combustible mixture whose richness is novel feature of my invention is accomplished. not changed by variations in either speed or alti The jet ‘I4 is supplied with fuel from a ?oat bowl 90 having the usual ?oat 92 controlling a tude. The essential difference between the modi?caé needle valve 04 regulating admission of- fuel to of Figs. 4 and 5 and the embodiment of Figs. the ?oat bowl through an inlet 96. A pipe 98 50 tion and 3 resides in the fact that in Figs. 1, 2 and ' 1, 2 connects the inlet 96 with any suitable source of 3 the fuel line I04 has a coil I06 exposed to the fuel. A pipe I00 connects the top of the ?oat ventilating air which vaporizes the fuel, whereas bowl with the elbow 68, through whichv the com in the modi?cation of Figs. 4 and 5 the fuel line bustion air ?ows in passing from the' rain 62 to 65 has a portion‘ extending into the combustion I ram I4, and both of these project through the the Venturi tube 10. This pipe I00, therefore, chamber and the fuel is vaporized by heat ob» insures maintenance in the ?oat bowl of the same tained from this chamber. Referring to Figs. 4 ' pressure to which the combustion air is subjected and 5, it will be seen that in this form of my just prior to its entry into the Venturi tube 10. invention the ?oat bowl 00 is located at the for The ?oat bowl 90 has a fuel outlet ?tting I02 ward/or combustion chamber end of the heater. through which .the liquid fuel leaves this ?oat 60 The‘ fuel line N41; has a reversely bent portion bowl. This outlet ?tting is preferably provided I06'o which extends through the combustion ,with a restriction I03. A tube of copper‘ or other. chamber 30 and into the ?aring throat 40. This suitable material I04 connects the outlet ?tting portion I00a is exposed to the hotv products of I02 with the jet ‘I4. This tube I04 extends into combustion and absorbs sumcient heat therefrom 65 the ventilating air space 50 and has a coiled por to'vaporize the fuel contained in this portion of tion I06 located therein. The ?ow of heated ven- ' the fuel line I04a so that the jet ‘I4 receives only tilating air over ‘that portion of the tube ‘I04 which is within the space 58 vaporizes theliquid ~ vaporized fuel instead of the usual liquid fuel. The pipe I00awhich connects the top of the ?oat fuel in this‘ portion of the tube so that-the fuel with the elbow 08 is shorter than the cor ?owing from the coiled portion I06 of the tube 70 bowl responding pipe I00 of the vprevious embodiment _ Thevjet .14 is made by "104 iisein vaporized form. but performs the, same function of maintaining screwing a small plug I08 into the outlet end of a pressure in the ?oat, bowl corresponding at the tube I04 and by providing this plug with-Ya all times to the pressure at .the air inlet of small ori?ce through which the vapor passes intov the throat of the Venturi tube'10'. _ . the Venturi tube ‘I0. Since the operation of that - 2,411,581 ' form of my invention shown in Figs. 4 and 5 is the same as the operation of the previous em bodlmentpit is unnecessary further to describe the operation of the modi?cation of Figs. 4 and 5. In each of the two embodiments of my inven tion the heating coil which vaporizes the fuel be ture to said combustion chamber, means’ includ ing‘ a ram for supplying combustion air to said Venturi tube, a ?oat bowl for liquid fuel, a fuel jet in said Venturi tube, a pipe connecting said ?oat bowl with said jet, said pipe .having a part exposed to ventilating ‘air leaving said heat ex changer whereby fuel in said pipe is vaporized fore this fuel reaches the jet 14 receives heat as a result of heater operation. When the heater is before it reaches said jet, and a second pipe con ?rst started, no heat is available to vaporize the‘ necting the inlet end of said Venturi tube with fuel and liquid fuel is supplied to the jet 14. This 10 the top. of said ?oat bowl. jet is made of appropriate size to deliver the de 2. An aircraft heater comprising walls forming sired amount of vaporized fuel when the heater a combustion chamber, a heat exchanger receivis operating normally'and unless special means ‘ ing hot products of combustion fromsaid com were provided a great excess of liquid fuel would bustion chamber, means including a ram for cir ?ow through this jet when‘ the heater is ?rst culating ventilating air over said heat exchanger, started and would ?ood the heater. I have pro a Venturi tube for supplying a combustible mix vided special means to prevent such ?ooding ture to said combustion chamber, means includ when the heater is ?rst started and this anti \ ing a ram for supplying combustion air to said ?ooding means constitutes an important feature Venturi tube, a ?oat bowl for liquid fuel, a fuel of my invention. 20 jet in said ‘Venturi tube, a pipe connecting said I have previously ‘pointed out that the outlet float bowl with said jet, said pipe having a part ?tting it? for the float bowl is provided with a extending into said combustion chamber whereby ’ restriction ass. This restriction is smaller than , the jet ‘it and when the heater is ?rst started the restriction H33 ratherthan the jet ‘it determines the quantity of fuel supplied to the heater. Since it is desirable to supply a rich mixture for start ing, the restriction I03 is so designed that it will furnish a quantity of fuel slightly in excess of that required when the heater is in normal operation. As soonv as the heater attains normal operating temperature, the fuel in coil I06 or IBM is vapor ized and thereafter the jet 14 determines the quantity of fuel supplied to the combustion chamber. ' , 4 In a heater designed to have a heat output of 10,000 B. t. u. per hour, the Venturi tube 10 would fuel in said pipe is vaporized before it reaches said jet, and a second pipe connecting the inlet end of said Venturi tube with the top of said ?oat bowl. 3; An aircraft heater comprising walls forming a combustion chamber, a‘heat exchanger receiv ing hot products of combustion from said combus tion chamber, means including a ram for cir culating ventilating air over said heat exchanger, ' a Venturi tube for supplying a combustible mix ture to said combustion chamber, means includ ing ‘a ram for supplying combustion air to said Venturi tube, a ?oat bowl for liquid fuel, a fuel jet in said Venturi tube, a pipe connecting said ?oat‘ bowl with saidiet, said pipe having a part be given a throat diameter of about %" and the > - exposed to heat from said heater whereby fuel in tube I04 would have an outside diameter of 1A". said pipe is vaporized before it reaches said jet, The jet 14 would have a diameter of about .055" 40 and a second pipe connecting the inlet end of and the restriction I03 would have a diameter of said Venturi tube with the top of said ?oat bowl. about .015"~. In such a heater the pipe I00 or 4. An aircraft heater comprising walls form - 100a would be considerably smaller-‘than that ining a combustion chamber, a heat exchanger dicated in the drawings and would probably be receiving hot products of combustion from said formed of copper tubing having an outside diam combustion chamber, means including a ram for eter of 1A" or 1%". ’ circulating ventilating" air over said heat ex It will be apparent from the foregoing descrip-_ , changer, means for supplying a combustible mix tion taken in connection with the accompanying ture to said combustion chamber, means includ-_ drawings that applicant’s novel fuel supply sys ing a ram for supplying combustion air to said tem incorporates no more operating parts than r second-named means, a ?oat bowl for liquid fuel, does the ' conventional carburetor. There is said second-named means including a fuelout nothing about this new and improved fuel supply let, a pipe connecting said ?oat bowl with said system which should cause any additional service outlet, said pipe having a part exposed to heat problems or which would add appreciably to the from said heater whereby fuel in said pipe is cost or weight of the heater. Likewise, there is vaporized before it reaches said outlet, and a‘ no increase in bulk over a conventional fuel sup ‘second pipe connecting the ‘inlet end of said ply system of the carburetor type, and no addi second-named means with the top of said ?oat tional manufacturing or assembling problems are presented by my invention. In other words,‘ my 5. An aircraft heater comprising walls forming invention provides a simple, eflicient and inex 00 a combustion chamber, a heat exchanger re pensive solution for the problem of altitude and ceiving [hot products of combustion from said speed compensation in aircraft heaters; combustion chamber, means including a ram for While I have illustrated and described only two circulating ventilating air over said heat ex embodiments of my invention, it is to be under changer, a Venturi tube for supplying a com stood that my invention may assume numerous bustible mixture to said combustion chamber, other forms and includes all ‘modi?cations, varia means including a ram for supplying combustion tions and equivalents coming within the ap air to said Venturi tube, a ?oat bowl for liquid pended claims. ' . fuel, a fuel jet in said Venturi tube, said jet being I claim: ' located slightly above the liquid level in said bowl, 1. An aircraft heater comprising walls forming 70 a pipe-connecting said ?oat bowl with said jet, a combustion chamber, a heat exchanger receiv said pipevhaving a part exposed to heat from ing hot products of combustion from said com said heater whereby fuel in said pipe is vaporized bustion chamber, means including a ram for cir-= before‘ it reaches said jetpand a second pipe culating ventilating air over said heat exchanger, connecting the inlet end of said Venturi tube 0 Venturi‘ tube for supplying a combustible mix- _ 76 with the top of said ?oat bowl. 2,411,581 7 6. An aircraft heater comprising walls forming a combustion chamber, a heat exchanger receiv ing hot products of combustion from said com bustion chamber, means including a ram for cir culating ventilating air over said heat exchanger, 8. Venturi tube for supplying a combustible mix ture to said combustion chamber, means includ necting said ?oat bowl with said jet, said pipe having a part exposed to heat from saidlheater whereby fuel in said pipe is vaporized before it reaches said jet, 9. second pipe connecting the inlet end of said Venturi tube with the top of said ?oat bowl, and means forming a restriction in said ?rst pipe limiting ?ow of liquid fuel to said jet when the heater is started. 8. An aircraft heater comprising walls forming Venturi tube, a float bowl for liquid fuel, a fuel ' jet in said Venturi tube, a pipe connecting said 10 a combustion chamber, a heat exchanger receiv ing hot products of combustion from saidcom ?oat bowl with said jet, said pipe having a part bustion chamber, means including a ram for cir exposed to heat from said heater whereby fuel culating ventilating air over said heat exchanger, in said pipe is vaporized before it reaches'said 9. Venturi tube for supplying a combustible mix ‘jet, a second pipe connecting the inlet end of said Venturi tube with the top of said ?oat bowl, 15 ture to said. combustion chamber, means includ ing a ram for supplying combustion air to said, and means preventing excess ?ow of liquid fuel Venturi tube, a ?oat bowl for liquid fuel, a fuel through said jet when the heater is started. jet‘ in said Venturi tube, a. pipe connecting said '7. An aircraft heater comprising walls forming ?oat bowl with said jet, said pipe having a part a combustion chamber, a' heat exchanger re ceiving hot products of combustion from said 20 exposed to heat from said heater whereby fuel in said pipe is vaporized before it reaches said combustion chamber, means including a ram for jet, a second pipe connecting the inlet end of v_ circulating ventilating air‘ over said heat ex said Venturi tube with the top of said ?oat bowl, changer, a Venturi tube for supplying ‘a com and means forming a restriction between said bustible mixture to said combustion chamber, means including a ram for supplying combustion 25 jet and float bowl, said restriction being smaller than said jet. air to said Venturi tube, a ?oat bowl for liquid ‘ HENRY J. DE N. McCOLLUM. fuel, afuel jet in said Venturi tube, a pipe con . ing a ram for supplying combustion air to said .