US2484385A - Fluid fuel burning internalcombustion air heater - Google Patents

Description

Oct. 1l, 1949. H. J. DE N. MccoLLUM 2,484,385

l FLUID FUEL BURNING INTERNAL-COMBUSTION AIR HEATER Filed Oct. E, 1945 Patented ocr. 11, 1949 FLUID FUEL BURNING INTERNAL- COMBUSTION AIR HEATER Henry J. De N. McCollum, deceased, late of Chicago, Ill., by Thelma McCollum, executrix, Chicago, Ill., assigner to Stewart-Warner Corporation, Chicago, Ill., a corporation of Virginia Application October 3, 1945, Serial No. 619,981

12 Claims. 1

This invention relates generally to heaters, and more particularly to heaters burning liquid hydrocarbon fuels employed to heat vehicles such as automobiles, trucks, tanks, boats, and airplanes, as well as for general heating purposes.

One object of the invention is to provide an improved heater for automobiles and the like, which operates independently of the automobile engine.

Another object of the invention is to provide an improved heater for use in automobiles and other vehicles, which has means to preheat the air supplied for combustion, thereby increasing the combustion` rate and making it possible to generate heat at a high rate in a heater of relatively small overall dimensions.

It is also an object of the invention to provide an improved heater for automotive vehicles, which will start readily at very low temperatures, and in which fuel oils, kerosene or gasoline, may be used as the fuel, and which will operate reliably under varying adverse conditions of temperature.

A further object of the invention is to provide an improved heater oi the type indicated which is constructed mainly of sheet metal and thus may be very economically manufactured in a form which is light in weight, and small in size, and in which the possibility of the escape of products of combustion from the heater directly into the space to be heated can be eifectively eliminated.

Other objects and advantages of the invention will appear from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is an axial vertical sectional view of an improved heater embodying this invention;

Fig. 2 is a transverse detail section taken substantially as indicated at line 2-2 on Flg. 1.

The heater shown in the drawings is of the same general type as the heaters disclosed in a copending application, Serial No. 584,359, filed March 23, 1945, for an invention by the same Henry J. De N. McCollum, but involves certain differences in construction and arrangement. It includes an outer casing I of approximately cylindrical form having a ilaring portion l2 near the top to which there is connected a return bend portion I4 which supports a sleeve I6 surrounding a fan I8 and its driving motor 28. The fan I8 serves to draw Ventilating air into the heater in heat exchange relation with the products of combustion so that this air, when discharged to the space to be heated, will act as the vehicle for delivering heat thereto. The sleeve or cylinder I6 which denes the intake passage for the air supports a plurality of vanes 22 which are disposed in substantially vertical planes so as to direct the air downwardly from the fan I8 and removethe circular component of motion therefrom.

Within the casing I0 there is a coaxially arranged combustion chamber or space 24 which is formed between an inner shell 26 and an outer shell 28. The outer shell 28`is spaced inwardly from the casing wall I0 and is supported therefrom by brackets 38 and 3| which may be welded to said shell 28 and which are attached to the casing wall I 0 by screws 32. 'I'he inner wall 26 of the combustion chamber is formed with an outwardly extending ilange 34 at its upper end and a terminal ange 36 which is welded to the upper margin of the shell 28, thus closing the combustion chamber at its upper end and supporting vthe inner shell 26 through this connection to the outer shell 28.

The fan motor 20 is carried upon a plate 38 which rests upon and is secured to a iianged ring 40 welded to the inner surface of the shell 26. The housing of the motor 20, together with the plate 38 and ring 40, form a substantially air tight partition extending across the shell 26. The air for supporting combustion enters the heater through an air induction tube or ram 42 attached to an air inlet fitting 44 which extends outside the casing l0. Inside the casing this fitting connects with an air tube 46 which passes through the Walls 28 and 26 of the combustion chamber and is connected laterally into a vertically extending tube 48 which is axially positioned within the shell 26. The upper end of the tube 48 has a flange 50 which is welded to the underside of a transversely extending partition plate 52, said plate having a peripheral flange 54 welded to the inner surface of the shell 26. The plate 52 is spaced below the partition plate 38 to accommodate the rotor or impeller wheel 56 of a blower which is carried on the downwardly extending shaft 2l of the motor 20 to be driven thereby. The wheel 56 comprises a disc or web secured to a hub 58 and said disc carries a plurality of irnpeller blades 60 which are spaced outwardly from of the wheel 56. central opening 62 which registers with the interior of the tube 48 and admits air from the tube 46 to the central portion of the rotor or wheel 56. The centrifugal action of the rotor 56 discharges the air outwardly and downwardly through ports 64 formed in the peripheral portion of the partition plate 52 and provided with vanes 66 trending downwardly in contact with the converging walls of the lshell 28. These vanes or baiiies may be struck out of the plate 52 and extend preferably in substantially vertical planes for directing the air downwardly into a cup portion 21 of the shell 28 at the lower end thereof.

At the lower end of this cup portion 21 the shell 26 is formed with a bottom wall 29 and the tube 48 includes an in-turned flange 49 welded to said bottom wall 29 so that the tube serves as a brace or strut between said end wall 29 and the partition plate 52, reinforcing the structure and tending to prevent vibration thereof.

Adjacent the converging lower portions e the shell 26, the outer wall 28 of the combustion chamber also converges downwardly and terminates in an annular flange or collar 68 which provides a relatively constricted annular passage 10 around the cup portion 21 of the inner shell 26. The combustion chamber includes a downwardly flaring member 12 having an annular flange or collar 14 which is welded to the collar 68 and having a bottom -wall I8 set into its lower end and secured by welding the flange 18 of said bottom wall to the terminal flange 80 of the dared member 12. Within this conical chamber the lower end of the cup 21 is suspended and air outlet openings 82 at the lower end of said cup 21 are provided with vanes or louvres 84 extending obliquely so that the air discharged through the openings 82 will be given a whirling motion with some centrifugal effect tending to throw it outwardly toward the sloping wall 12 and retarding its escape from this space. An electrical igniter assembly is threaded into a ring 88 which is welded in the center of the bottom wall 29 of the shell 26 so that the high resistance coil 88 and its enclosing tubular shell 90 depend therefrom into a well 92 formed at the axis of the bottom wall 16. Liquid fuel supplied to this well 92 is vaporized by the heat radiated by the shell 90 or by contact therewith, and the vapor is ignited as it forms a combustible mixture with the air entering the well and the adjacent space through the ports 82. To insure -prompt ignition of the vapor, the shell 90 may have -ports 94 permitting the vapor to come into direct contact with the coil 88.

The liquid fuel is supplied through a tube 98 connected to a suitable source of fuel, such as a tank (not shown) and attached by a coupling 98 to a threaded stem on the air intake fitting 44. A bushing |02 secured ln the bore of the stem |00 provides a restricted passage for limiting the flow of fuel as deired. The fitting 44 is cast with a bridge |04 extending across it, this bridge having a bore through which the fitting may be threaded to receive the bushing |02, and the bushing itself may be inserted. Thereafter, a portion of this bore is closed by a plug |08 threaded adjacent its head |08 and dimensioneda to leave a space I0 into which fuel is fed through the restricted opening in the bushing |02 and from which a tube 2 extends laterally through the air pipe 46. An elbow ||4 connects the tube 2 with a vertically extending tube ||8 which passes through the bottom wall 29 of the shell 26 and discharges into the well 92 as clearly shown in Fig. 1. The feed wire ||8 for the igniter coil 88 also is conveniently arranged to extend through the air induction tube 46 and the tube 48.

Thus the fuel vaporized from the well 92 is mixed with air discharged from the ports 82 and is ignited in the conical chamber 12, whereupon the hot gases are forced upwardly through the '4 constricted passage into the combustion chamber or space between the shell 26 and the shell 28, and the products of combustion escape eventually through an exhaustoutlet extending laterally from the upper end of the chamber andV through the outer casing I0. Meanwhile, the Ventilating air drawn into the heater by the fan I8 ows downwardly between the vanes 22 toward the partition plate38. Then it reverses direction and flows upwardly between the sleeve I6 and the inner shell 26 of the combustion chamber absorbing some heat from this shell. The air is again reversed in direction s it strikes the return bend portion |4 of the casing and flows downwardly between the casing wall I0 and the outer shell 28 of the combustion chamber. Here its temperature is further increased by contact with the hot wall 28 of the combustion chamber and with the flaring wall 12 Within which combustion commences. The air thus heated eventually is discharged downwardly through an outlet |22 which may lead directly to the space to be heated or may be connected with any suitable conduit or conduits for distributing the heated air as desired.

It will be noted that the air induction tube 46, which furnishes air for combustion, extends transversely across the space through which the heated air flows between the wall I0 and the shell 28, and also extends transversely through the combustion chamber itself. The incoming air thus -picks up a considerable quantity of heat as it passes through the tube 46; then again as it is discharged centrifugally by the blower wheel 56 against the inner Wall 26 of the combustion chamber and is swept downwardly along the converging surfaces thereof. It is additionally preheated before it is discharged through the ports 82 for admixture with the vaporized fuel. In this condition the air ,facilitates vaporization of the fuel and the turbulence produced by the whirling discharge of air from the ports 82 tends to secure thorough intermixture of the air and fuel and to promote rapid combustion thereof so that a. high temperature is quickly attained in the lower part of the combustion chamber and is maintained as the products of combustion are forced upwardly by their own expansion. At the same time the products of combustion are effectively separated from the Ventilating air flowing around the combustion chamber, all joints in the wall of the combustion chamber being welded to provide air-tight connections. IAlmost the entire struc'- ture is composed of relatively thin sheet metal which may be of a composition of steel adapted to withstand high temperatures but which is light in weight and relatively simple to form into the desired shapes composing the heater parts already described. The heater therefore is eilicient in operation and can be manufactured at relatively low cost.

The outwardly daring wall 12 which forms the conical lower portion of the combustion chamber not only serves to retard the escape of the products of combustion upwardly at the constriction 10 of the combustion chamber, but this position of the wall 12 extending more or less transversely of the upward ow insures a scrubbing or scouring contact of the gases which is conducive to effective transmission of heat through the wall 12. This scouring action is increased by the whirling motion of the gases which results from the provision of the vanes 84 at the air supply ports 82. On the outer side of the wall 12 the Ventilating air, flowing downwardly, meets the obliquely presented surface of this wall and the result is a scouring action of the air over this surface causing the efficient transfer of heat from the wall 12 to the Ventilating air.

Some changes may be made in the construction and arrangement of the parts of this apparatus without departing from the spirit and purpose of the invention, and it is intended to cover by the claims any modified forms of structure or any use of mechanical equivalents which may be reasonably included within their scope.

Having thus described the invention, what is claimed as new and desired to be secured by Lettrs Patent is:

l. In a heater, the combination of a pair of generally `concentric shells having their upper rims sealed together and providing a combustion chamber between them, said shells having substantially cylindrical upper portions with downwardly tapering lower portions, the tapering portion of the inner shell terminating in a central cup with ports opening laterally toward the outer shell, said outer shell having a conical portion surrounding said cup and tapering upwardly to form a constricted zone around the cup and above its said ports, said conical portion having a bottom wall with a central Well, a fuel feed pipe extending into said well, an igniter of the hot wire type supported by the bottom of said cup and extending into said well, means supplying combustion air to said inner shell for discharge through said ports to form a combustible mixture with the fuel vaporized in said well, and an exhaust passage leading from the upper portion of said combustion chamber.

2. In a heater as defined in claim 1, vanes disposed adjacent the ports of said cup, each extending outwardly from one side of its port in oblique relation to the plane of the port, said vanes causing a whirling motion of the air discharged from said ports.

3. In a heater as defined in claim 1, a pair of partition walls extending across the inner shell in vertically spaced relation, said means for supoutlet means for air delivered by the blower to be fed through the ports of said cup portion.

4. In a heater as dened in claim l, a pair of partition walls extending across the inner shell in vertically spaced relation, said means for supplying combustion air including a blower wheel disposed between said walls, the lower wall having a central inlet port for air and outlet ports leading from its peripheral portion into said inner shell, and a tube connected to said lower wall around said inlet port extending to the bottom wall of the cup and secured thereto, together with an air supply conduit extending through the walls of the combustion chamber and connected laterally into said tube.

5. In a heater as defined in claim 1, a jacket surrounding the outer shell to serve as a passage for air to be heated, and means for causing said air to flow downwardly in said jacket and against the outwardly aring conical portion of said outer shell of the combustion chamber.

6. In a heater as defined in claim l, a jacket for Ventilating air including a cylinder coaxially disposed within the ,upper portion of said inner shell. a cylinder coaxially disposed around said outer shell and a reversely bent wall connecting the upper ends of said cylinders together with a rotary fan and a motor therefor mounted within said first mentioned cylinder, and a transverse partition wall in the inner shell below the end of said cylinder whereby the air fed downwardly by the fan is reversed by said wall for upward travel along the inner wall of the combustion chamber and is then reversed by the reversely bent wall for downward travel along the outer wall of the combustion chamber.

7. In a heater, the combination of a pair of generally concentric shells having their upper rims sealed together and providing a combustion chamber between them, said shells having substantially cylindrical upper portions with downwardly tapering lower portions, the tapering portion of the inner shell terminating in a central cup with ports opening laterally toward the outer shell, said outer shell including a portion surrounding said cup at the level of said ports and extending below said cup with a bottom wall formed to receive liquid fuel, means supplying liquid fuel to said bottom wall an igniter disposed adjacent said bottom wall, means supplying air through said ports to form a combustible mixture, said outer shell forming a constricted annular space around the cup portion and above its said ports, and an exhaust passage leading from the upper part of said outer shell.

8. In a heater, the combination of a pair of generally concentric shells having their upper rims sealed together and providing a combustion chamber between them, said shells having substantially cylindrical upper portions with downwardly tapering lower portions, the tapering portion of the inner shell terminating in a central cup with ports opening laterally toward the outer shell, the downwardly tapering portion of the outer shell forming a constricted annular space around the cup of the inner shell and above its said ports, said outer shell including an outwardly extending wall adjoining said constricted space and forming an annular chamber of larger diameter around the ports of the inner shell with a bottom wall which includes a central well, means supplying liquid fuel to said well, a hot wire igniter disposed in said well, means supplying air through said ports to form a combustible mixture with fuel vaporized in said well, and an exhaust port in the upper part of said combustion chamber.

9. In a heater as defined in claim 8, a jacket -for Ventilating air surrounding said outer shell,

and meansy to feed said air downwardly in said jacket and against said outwardly extending wall 0f the outer shell, said jacket extending past said wall with clearance for the discharge of air heated by contact with the wall of the combustion chamber.

10. In a heater, the combination of a pair of coaxially disposed shells providing a combustion chamber between them and having their upper rims sealed together to close the upper end of said chamber, a casing surrounding said shells and spaced therefrom to provide a Ventilating air passageway, said casing having a portion which extends over the closed upper end of the combustion chamber in spaced relation thereto and an extension depending therefrom in spaced relation to the inner face of the inner shell. means for supplying liquid fuel to said combustion chamber at a controlled rate, means for supplying air for combustion to said combustion chamber including ports and vanes at the lower end of the inner shell arranged to impart turbulence to the combustion air for assisting in vaporizing liquid fuel, igniter means located in the space between said shells, and means including a partition extending across the inner of said shells causing a flow of Ventilating air upwardly between said inner surface of the inner shell and said extension of the casing and thence over the upper end of the combustion chamber and downwardly through said Ventilating air passageway within the casing.

11. In a heater as dened in claim 10, a rotary fan and a motor therefor supported within said depending extension of the casing and axially thereof, and baffle means spaced below the lower end of said extension whereby air drawn downwardly by said fan is deflected upwardly into the space between said extension and the inner surface of the inner shell.

12. In a heater as dened in claim 10, a transverse partition spaced below the lower end of said extension of the casing and tted into the inner shell, a motor supported on said partition with its shaft axially disposed in said shell, a fan on the upper endeof said shaft within said depending extension of the casing for forcing air downwardly within said extension and causing said air to be deected upwardly by said partition into the space between the extension and the inner shell, said motor shaft extending downwardly through the partition, a blower rotor secured to said shaft below said partition, said blower rotor being disposed to promote flow through said combustion air supplying means when said motor is operating.

THELMA McCOLLUM, Executriz of the Last Will and Testament of Henry J. De N. McCollum, Deceased.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS

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