US2308888A - Heater - Google Patents

Description

Jan. 19, 1943. J DE McCOLLUM 2,308,888

HEATER Filed Aug. 9, 1959 5 Sheets-Sheet l Jan. 19, 1943. H. J. DE N. McCOLLUM 2,308,888

HEATER Filed Aug. 9, 1939 5 Sheets-Sheet 2 1943. H. J. DE N. MCCOLLUM 2,308,888

HEATER Filed Aug. 9, 1939 5 ShejlZs-Sheet 3 fzadezzi'm.

Hem 26/1/1776 (allzzm- J 1943- H. J. DE N. MCCOLLUM 2,308,888

HEATER Filed Aug. 9, 1959 5 Sheets-Sheet 4 Jan- 19, 1943. H. J. DE N. MCCOLLUM ,30 ,88

HEATER Filed Aug 9, 1939 5 Sheets-Sheet 5 jgja w fiewim- 2% Patented Jan. 19, 1943 UNITED STATES PATENT OFFICE HEATER Henry J. De N. McOollum, Chicago, Ill.

Application August 9, 1939, Serial No. 289,108

9 Claims.

My invention relates generally to heaters, and more particularly to relatively small space heating units adapted for use in busses, trucks, and the like, and for the heating of small enclosures such as automobile service stations, etc.

It ls among the objects of my invention to provide an improved space heater which is in the form of a self contained unit and may be operated independently of the engine of the vehicle and requires merely the supp y of a liquid fuel, such as gasoline, and electric current.

A further object is to provide an improved liquid fuel burning heater in which a combustible mixture is supplied under pressure to a combustion chamber and in which the products of combustion are drawn from the heater by means of a suction blower.

A further object is to provide an improved unit type heater which is substantially noiseless in operation.

A further object is to provide an improved liquid fuel burning heater in which improved means are provided for obtaining a substantially complete atomization of the liquid fuel,

A further object is to provide an improved heater in which a single motor is utilized to supply combustible mixture under pressure to the combustion chamber, and to exhaust the products of combustion from the heater.

A further object is to provide an improved heater in which the richness of the mixture supplied to the combustion chamber is controlled by means responsive to the temperature of the exhaust from the heater.

A further object is to provide an improved heater having safety devices to stop the operation of the heater when the temperature thereof rises above a predetermined maximum value.

A further object is to provide an improved unitary heater which is relatively simple in construction and operation, which will be effective to deliver a large quantity of heat for its size, which may readily be controlled as to the rate of heat delivered, and which may be economically manufactured.

Other objects will appear from the following description, reference being had to the accompanying drawings, in which Fig. 1 is a side elevational view of the heater;

Fig. 2 is a top plan view thereof;

Fig. 3 is a vertical cross sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is a horizontal sectional view taken on the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary sectional view showing a portion of the blower and the thermostatically operated valve for admitting additional air when the exhaust from the heater attains a predetermined temperature;

Fig. 6 is a transverse sectional view taken on the line 66 of Fig. 3;

Fig. 7 is a transverse sectional view taken on the line 'll of Fig. 4;

Fig. 8 is an elevational view of a modified form of means for delivering liquid fuel to the heater;

Fig. 9 is a fragmentary sectional view taken on the line 99 of Fig. 8; and

Fig. 10 is a diagrammatic view of the heater including a modified form of fuel supply system and the electrical wiring diagram therefor.

In general, the heater of my invention comprises an automatically operated pump for the liquid fuel, either mechanically or electrically driven, which supplies fuel to an auxiliary reservoir in which the level of the fuel is maintained by a float operated valve and from which the fuel is drawn to a carbureting device by suction. The fuel mixed with atmospheric air in the carbureting device is supplied to a blower which assures substantially complete atomization of the liquid fuel, and discharges it under pressure into a combustion chamber. Within the combustion chamber is an electrically heated igniter which ignites the mixture and permits the addition of auxiliary air to .the burning mixture as to in sure complete combustion. The hot gases of combustion flow through a plurality of conduits forming a radiator or heat exchange device and into an exhaust manifold which leads to the inlet of a suction or aspirating blower. An electric motor driven fan circulates air from the enclosure to be heated over the heat exchange device or radiator. The fuel injection blower and the aspirating blower are driven by a common motor, the speed of which may be manually controlled. The heater is provided with electrical control circuits whereby the supply of current to the electrically heated igniter is cut off after the heater has commenced operation, and for cutting off the supply of current to the motor which drives the blowers whenever the radiator attains a temperature unsafe for continued operation. It is believed that with the foregoing general description of the invention, the more detailed description which follows will be more readily understood.

Referring to Figs. 1, 2, 3, and 4, an automatic fuel pump 20 is mounted on the heater support 22 in any suitable manner, the fuel pump illustrated in the enumerated figures being electrically operated, being supplied with current through the conductor 24, the return path being through a suitable ground connection (not shown). The fuel pump 26 is supplied with gasoline through a conduit 26 and has an outlet conduit 26 which leads to an auxiliary reservoir 36 which may be of any suitable construction incorporating a float operated valve to maintain the fuel level therein uniform, or may be of a type having an overflow conduit 32 through which the surplus of the fuel supplied by the pump 26 may be returned to the main reservoir from which the pump 26 derives its supply of fuel. A conduit 64 leads from the auxiliary reservoir 96 to a carbureting device 36 (best shown in Fig. 4). The end of the conduit 34 leading into the auxiliary reservoir 36 may be of the construction disclosed in my copending application Serial No. 61,213, filed January 28, 1936, Patent No. 2,191,173, or in my copending application Serial No. 177,075, filed November 29, 1937. The latter application also discloses a suitable form of float controlled auxiliary reservoir.

Suction is induced in the outlet end of the carbureting device 36 by a blower 36 which comprises a housing 46 closed by a cover plate 42, the cover plate providing a bearing 44 for the hub 46 of an impeller or rotor, the blades of which are in the form of radial tubes 46 pressed into (and preferably welded) the hub 46. The hub 46 is nonrotatably secured to the rotating armature shaft 56 of an electric motor 52 which is suitably mounted on the heater support 22. The carbureting device 36, it will be noted from Fig. 4,

has passageways for admitting atmospheric air,

and a Venturi shaped passageway 54 for increasing the suction effective upon a nozzle 56 which is the effective termination of the conduit 34.

The mixture of the fuel and air supplied by the carbureting device 66 is radially ejected through the tubes 46 due to the centrifugal action. A substantial pressure is built up within the housing 46, the mixture being thus forced under pressure through an outlet tube 56 which is secured to the housing 46. The outlet tube 56 projects into a combustion chamber casting 66 which is suitably secured to a plate 62 mounted on the support 22. Within the outlet tube 56 is a heating tube 64, the inner end of which projects into a combustion chamber 66 formed in the casting 66 and closely adjacent a batile plate 66 which, as shown in Fig. 6, has a plurality of notches 16 for the passage of the fuel mixture, and is likewise spaced from the wall of the combustion chamber by lugs I2 so as to provide a substantially complete annular passageway for the flow of the combustible mixture into the combustion chamber 66.

The combustion chamber casting 66 is enclosed in a housing I4 which is secured to the plate 62 by a nut 16 threaded over the end of the combustion chamber casting 66, and has an inlet port I6 registering with a corresponding opening formed in the plate 62 to admit atmospheric air thereto from the engine compartment of the vehicle, assuming that the heater is utilized for heating the passenger compartment of an automobile, bus or truck, and that the support 22 constitutes the dash of such vehicle. It will be understood, however, that the heater may be utilized for heating any enclosed space, and the support 22 may constitute a partition or wall of a room, or may be part of a housing and standar for the heater.

The housing I4 serves not only as a protection for the igniter hereinafter to be described. but

also serves as an insulator against the transmission of flame noise from the heater to the space being heated. The housing I4 may also constitute the support for a ring 66 which surrounds the end of the combustion chamber and forms a support for the manifold 62. The end of the manifold 62 is welded or otherwise suitably secured to the ring 66, and is spaced from the tubular projection 64 of the combustion chamber casting 66 to provide an annular passageway 66 through which air from within the housing I6 may flow freely into the manifold 62, as indicated by the arrow in Fig. 3.

It will be understood that ordinarily the mixture supplied to the combustion chamber will be relatively rich, so that complete combustion may not take place within the combustion chamber 66,

and as a result the flame will extend into the manifold 62, combustion being supported by the auxiliary air admitted through the annular passageway 66. The flame and products of combustion within the manifold 62 are drawn through a plurality of radiating tubes 66 which connect the manifold 62 with an outlet manifold 96, the flow being as indicated by the arrows in Fig. 4. The outlet manifold 66 is connected by suitable conduit 92 with the inlet of a suction blower 94, the impeller of which is connected to the shaft 56 of the motor 52 and which is effective 'to create a partial vacuum in the conduit 92 and eject the products of combustion under pressure through a discharge conduit 96. The discharge conduit 96 may lead to any suitable outlet such as the flue of a chimney, if the heater is installed in a building, or, in case the heater is installed upon an automobile, the conduit 96 may exhaust directly to the outer atmosphere, or may be connected to the exhaust pipe of the vehicle.

The radiator formed by the manifolds 62 and 96, and the tubes 66 interconnecting these manifolds, is enclosed in a suitable housing comprising side walls 96, I66, I62, and I64, and having a bottom deflecting wall I66, the wall I66 serving to deflect air to the right (Fig. 3), through an outlet I66. A top I65, having a circular flanged fan receiving opening I61, completes the casing. Air is forced downwardly past the radiator by a fan II6 driven by an electric motor II2, the motor being mounted upon a suitable bracket support I I4, which is welded or otherwise suitably secured to the manifolds 62, 96. A deflector plate III is mounted within the casing to prevent the fan from blowing cold air over thermostatically operated switch mechanisms hereinafter to be described.

As best shown in Figs. 4 and 10, a thermostatically operated switch mechanism H6 is secured to the end of the manifold 62 so as to be in heat conducting relationship therewith. The switch mechanism I I6 comprises a switch arm I I6 which is connected by a conductor I26 to a source of current I22, upon the closure of a control switch I24. The switch arm II6 carries a contact I26 which is normally in engagement with rigid contact I 26, the latter being connected by a wire I36 with one terminal of igniter coil I32. The igniter coil, as illustrated in Figs. 3 and 10, may be made of a suitable resistance wire such as nichrome wire, and has one end grounded and the other end connected to an insulated terminal I34 to which the wire I36 is connected. The contacts I26 and I 26 are normally in engagement so that upon closure of the switch I24, current will immediately flow to the igniter coil I32. After the manifold 62 becomes heated to a temperature approaching its normal operating temperature, the thermostatic bi-metal arm I38 flexes to the left (Fig. 4) causing its contact I38 to engage a contact I48 carried by the contact arm II8. Upon engagement of these contacts I38 and I40, current may flow from the battery through the conductor I20 to the motor II2, causing circulation of air from the space to be heated downwardly past the radiator.

A safety switch mechanism I42 is secured to the outlet manifold 80 in heat conducting relationship therewith, the switch mechanism being generally similar to the switch mechanism II8 previously described, except that its bi-metal thermostatic arm I44 is preferably set so as to flex sunlciently to bring its contact I45 into engagement with the contact I48 carried by the center contact arm I50, at a temperature considerably higher than that at which the thermostatic bimetal arm I36 operates. The switch mechanism I42 has a pair of contacts I52 which are normally closed and connect the switch arm I50 with a conductor I54.

The conductor I54 is connected to a contact arm I55 forming part of a rheostat including an adjustable resistance I58.

The rheostat is adapted to control the current flow to the motor 52, as well as to the electrically operated fuel pump 20. By adjustment of the position of the contact arm I55, the speed of the motor may be controlled, thereby controlling the rate of heat production of the heater unit, since the speed of this motor not only affects the rate at which the combustible mixture is supplied to the combustion chamber, but also determines the rate at which the gases of combustion will exhaust from the heater. It will be noted that the thermostatic bi-metal arm I44 of the switch mechanism I42 is electrically isolated, and the contacts I45, I48 thus do not complete any circuit. The thermostatic arm I44 functions only to open the contacts I52 whenever the manifold 90 approaches a dangerously high temperature, the switch thus constituting a safety cut-out for deenergizing the motor 52 if due to some unforeseen abnormal condition the radiator should become very hot.

After the heater has been in operation for some time, the housing of the blower 94 will, of course, become heated to some extent and transmit heat to a bi-metal thermostatic strip I62, one end of which is secured to the housing of the blower and the other end of which forms a valve closing the end of a conduit I64. The conduit I54 is connected to a passageway I66 formed in the cover plate 42 of the blower housing 40, and communicates with the interior of said housing through an inlet port I68, as best shown in Fig. 4. In order to assure rapid ignition of the combustible mixture supplied to the combustion chamber 55, when operation of the heater is initiated, it is desirable that the mixture be very rich. However, after normal combustion has started, the mixture may be made considerably leaner without disturbing normal combustion and, in fact, increasing the efliciency of combustion. Thus when the housing of the blower 94 becomes slightly heated after the normal combustion is initiated for a short time, the bi-metallic thermostatically operated valve I62 will open to admit additional air to the blower housing 40. This additional air is, of course, mixed with the mixture received from the carbureting device 36 and fed to the combustion chamber.

In Figs. 1, 2, 3, and 4, the fuel supply system for the heater is illustrated as including an electrically operated gasoline pump which maintains liquid fuel at the required level in an auxiliary reservoir 30. ,In Fig. 10 the fuel pump 28 is illustrated as being connected directly to the carbureting device 38, in which case the fuel pump will either be of a construction in which the rate at which it discharges fuel is determined by the voltage of the current supply as governed by the rheostat I55, I58, or the fuel pump will incorporate a reservoir in which the fuel is maintained at substantially atmospheric pressure and at a substantially constant level.

In Figs. 8 and 9 I have shown a modified form of the fuel supply system which comprises a casing I14, the upper end of which is closed by a flexible diaphragm I16, the central portion of which is secured to a connecting rod I18. The rod I18 is connected to an eccentric strap I surrounding an' eccentric I82 secured to the shaft 50 of the motor 52. The upward and downward oscillatory movement of the central portion of the diaphragm I15 causes the fuel to flow into the casing I14 from the pipe I84 which is connected to a standard fuel tank, and to discharge the fuel through a conduit I85. It will be understood that the casing I14 of the fuel pump will be provided with the necessary passageways and check valves to cause this result. Any suitable form of mechanically operated pump may be utilized, the construction illustrated in Figs. 8 and 9 being more or less diagrammatic and representative of a variety of fuel pumps which are well known. The significant feature of the arrangement shown in Figs. 8 and 9, when used in the system shown in Fig. 10, is that the fuel pump is operated at a speed determined by the speed of operation of the motor 52 and that the displacement of the fuel pump may therefore be correlated withe the fuel requirements of the heater when the motor 52 is operating at difierent speeds.

When the heater is placed in operation, the switch I 24 is closed, thus connecting the conductor I20 to the hot side of the battery I22. Since the contacts I52 are closed at this time (it being assumed that the heater is at atmospheric temperature) current will be supplied through the conductor I54 to the rheostat I55, I58, which, as shown in Fig. 1, may be adjusted by means of a control knob I59. Depending upon the adjustment of the rheostat I56, I58, the motor will operate at a predetermined speed and create a partial vacuum in, the Venturi shaped passageway 54 of the carbureting device 36, thus drawing liquid fuel directly from the fuel pump 20 (as shown in Fig. 10) or from the auxiliary reservoir 30 (as shown in Figs. 1, 2 and 4) into the blower housing. Particularly due to the construction of the blower, the partially atomized fuel supplied by the carbureting device 35 will be further broken up and more completely atomized in the course of the passage of the mixture through the blower. The mixture flowing under pressure developed by the blower will pass through the preheating tube 64 and be projected against the bailie plate 68, where the mixing and atomization will be rendered still more complete, the mixture then flowing into the combustion chamber 86 through the various apertures and slots formed in the baffle plate 68. Some of the fuel thus supplied will flow into the space beneath the igniter coil I32. The igniter coil will be supplied with heating current as soon as the switch I24 is closed, since as was assumed, the thermostatic switch mechanism I I5 is at atmospheric temperature and its contacts I26 and I28 in engagement to complete the circuitfrom'the battery through the conductor I30 to the igniter coil I32. The igniter coil is preferably made of sufllciently fine wire that it will heat to incandescence within a very short time under the applied voltage, so that shortly after the combustible mixture commences flowing into the combustion chamber, the igniter will be sufliciently hot to ignite the mixture and cause the propagation of a flame. This flame will project into the manifold 82 and be drawn, together with the products of combustion, through the tubes 82 into the manifold 98 under the influence of the suction generated by the suction blower 94.

After the heater has been in operation for a short period, the bi-metal thermostatic contact arm I36 will swing to the left-(Fig. 4) and close contacts I38, I48, thus completing the circuit to energize the motor H2. The motor 2 drives the fan IIO circulating air from the space to be heated downwardly around the tubes 88 and manifolds 82, 90, ejecting the air in a generally horizontal direction from the outlet I 88. As

the manifold 82 becomes hotter, the thermostatic bi-metal contact arm I36 will flex still further to the left and open contacts I26, I28, thus cutting off the supply of current to the igniter coil I32.

After the heater has been in operation for some time, the housing of the suction blower 94 will become heated and as a result the bi-metal thermostatic valve I62 will commence opening, admitting additional air to the blower 38, and making the mixture more lean so as to assure complete combustion. Of course, throughout the operation of the heater, air will flow through the annular passageway 86, so that there will normally be a slight excess of air over that required for complete combustion. This excess of air is desirable to insure that no unburnt fuel or carbon monoxide is drawn through the heater and ejected from the exhaust pipe 96.

If for any reason the radiator should become excessively hot, the bi-metal thermostatic contact arm I 44 of the switch mechanism I42 will flex to the left (Fig. 4) and separate the switch contacts I52, thus breaking the circuit which supplies the motor 52 as well as the electric fuel pump 20. heater will, of course, cease operation until the radiator has cooled to a safe operating temperature, whereupon the contacts I52 will again complete the circuit to the motor 52 and fuel pump 20. The completion of this circuit will, of course. result in the heater starting operation as previously described. There is however, the possibility that due to the fact that the bimetal thermostatic contact arm I is constructed to open its associated contacts at a higher temperature than is required to cause the bi-metal contact arm I36 to operate its contacts, the contacts I26, I28 may separate when the heater has cooled to a temperature sufficient to permit the closure of the switch contacts I52. Under these latter circumstances the apparatus may operate for some short period without igniting the combustible mixture supplied to the combustion chamber, but this will not have any seriously disadvantageous effect because after a short time the thermostatic bi-metal contact arm I36 will be cooled by the mixture to a temperature which will result in its closure of the switch formed by the contacts I26, I28.

It has been found that a flame burning in a When this circuit is opened, the v combustion chamber and flowing into a space such as that provided by the manifold 82 has a tendency to produce a roaring noise. The noise is considerably reduced by the admission of additional air to the manifold 82 through the inlet passageway 86 and the conduction of noise from the manifold 82 to the outside atmosphere is hindered by virtue of the fact that the housing H encloses the combustion chamber and the only direct path for the travel of sound through air to the atmosphere is through the relatively small port I8 formed in the housing I4.

While I have shown and described particular embodiments of my invention, it will be apparent to those skilled in the art that numerous variations and modifications thereof may be made without departing from the underlying principles of the invention. I, therefore, desire by the following claims to include within the scope of my invention all such similar constructions and modifications by which substantially the results of my invention may be obtained utilizing substantially the same or equivalent means.

I claim:

1. In a unit heater, the combination of a combustion chamber, means to ignite a mixture of fuel and air supplied to said chamber, a fuel pump, a carbureting device connected to said fuel pump to receive fuel therefrom and admix air with said fuel, a blower for drawing the mixture of fuel and air from said carbureting device and forcing it into said combustion chamber, a radiator receiving the products of combustion from said combustion chamber, means for causing air to pass over the outer surface of said radiator, and suction means for withdrawing the products of combustion from said radiator and maintaining said radiator and" combustion chamber under a partial vacuum.

2. In a unit heater, the combination of a combustion chamber, a blower for supplying a mixture of fuel and air under pressure to said combustion chamber, a radiator connected to receive the products of combustion from said combustion chamber, means for causing air to be heated to pass over the outer surface of said radiator a suction blower to withdraw the products of combustion from said radiator, and a common motor for rotating said blowers, said suction blower having a sufficiently greater capacity than said first-named blower to maintain the interior of said radiator at subatmospheric pressure.

3. In a unit heater, the combination of a combustion chamber, means to supply a combustible mixture to said chamber, a manifold for receiving products of combustion from said chamber, said manifold having an inlet end spaced from the end of said combustion chamber to provide an annular opening for the admission of atmospheric air to said manifold for admixture with the products of combustion, a casing surrounding said combustion chamber and sealed around the inlet end of said manifold, said casing having a restricted opening to the atmosphere formed therein, heat exchange means connected to said manifold, and suction means for withdrawing the products of combustion from said heat exchange means.

4. In a unit heater, the combination of a blower having an inlet and outlet, and having an auxiliary air inlet, means for supplying a combustible mixture t the inlet of said blower, a combustion chamber connected to the t t of said blower, means to ignite the combustible mixture 1n said combustion chamber. heat radiating means for receiving the products of combustion from said combustion chamber, a suction blower for drawing the products of combustion through said heat radiating means, and a thermostatically operated valve responsive to the temperature of the products of combustion withdrawn by said blower to admit air to said auxiliary inlet.

5. In a unit heater, the combination of a blow er, means to supply a combustible mixture of liquid fuel and air to said blower, a combustion chamber connected to receive the combustible mixture from said blower, means to ignite the combustible mixture in said combustion chamher, a housing, forming a substantially closed chamber, around said combustion chamber and spaced therefrom, a tubular element receiving the products of combustion from said combustion chamber, said tubular element being spaced from the end of said combustion chamber to provide an auxiliary air admission passageway, said passageway communicating between the space within said housing and said tubular element, thereby reducing the noise created by the operation of said heater and means for creating a partial vacuum in said tubular element.

6. In a unit heater, the combination of a combustion chamber, electrical means for igniting a combustible mixture in said chamber, means for supplying a combustible mixture of fuel and air to said chamber, said means including an electrically operated fuel pump, a blower for forcing the combustible mixture to said chamber, a radiator connected to receive the products of combustion from said combustion chamber, means for causing air to be heated to pass over the outer surface of said radiator, an exhaust manifold, a suction blower connected to exhaust the gases of combustion from said exhaust manifold, a single electric motor for operating both of said blowers, and a manually operable rheostat common to said electric motor and said electric fuel pump for controlling the supply of electrical energy thereto, whereby a combustible mixture is supplied to said combustion chamber, and the interior of said radiator is maintained at subatmospheric pressure, at all normal speeds of motor operation.

'7. In a unit heater, the combination of a combustion chamber, means to ignite a mixture of fuel and air supplied to said chamber, a fuel pump, a carbureting device connected to said fuel pump to receive fuel therefrom and admix air with said fuel, a blower for drawing the mixture of fuel and air from said carbureting device and forcing it into said combustion chamber means defining a substantially enclosed chamber having an air inlet, a duct for supplying a limited amount of air from said last-named chamber to the products of combustion from said combustion chamber, a variable speed motor driving said fuel pump and said blower, means for causing air to be heated to pass over the outer surface of said radiator a radiator receiving the products of combustion from said combustion chamber, and means for withdrawing the products of combustion from said radiator.

8. In a unit heater, the combination of a combustion chamber, means for supplying a combustible mixture of fuel and air to said combustion chamber, a radiator receiving the gases of combustion from said combustion chamber, means for removing said gases of combustion from said radiator, and means defining a substantially closed sound trap chamber, said radiator having an inlet end spaced from the end of said combustion chamber to provide an annular opening affording communication between said sound trap chamber and said gases of combustion.

9. In an internal combustion heater, the combination of a combustion chamber, means for supplying a combustible mixture of fuel and air to said combustion chamber, a heat exchange for receiving the gases of combustion therefrom, suction producing means for removing the products of combustion from said heat exchanger, means defining a sound trap chamber, and an inlet for admitting air to said sound trap chamber, said heat exchanger having an inlet end spaced from the end of said combustion chamber to provide an annular opening for permitting air to flow from said sound trap chamber to the gases of combustion leaving said combustion chamber.

HENRY J. DE N. MoCOLLUM.

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