US2398106A - Heater - Google Patents

Description

April 9, 1946. H. J. DE N. MccoLLuM 2,398,106

HEATER Filed June 5, 1945 2 Sheets-Sheet l Patented Apr. 9, 1946 HEATER Henry J. De N. McCollum, Chicago, Ill.; Thelmav McCollum executrix of said Henry J. De N.

McCollum, deceased Application June 5, 1943, serial No. 489,765

(ci. 12s- 116) 10 Claims.

My invention relates to heaters and more particularly to heaters of the internal combustion type commonly used to heat cabins or other enclosed spaces in aircraft, or for other similar purposes.

InA internal combustion heaters of the kind to which my invention pertains, it is common to use electrical ignition means for igniting a mixture of fuel and air supplied to the heater. Such electrical ignition means is ordinarily energized from a battery or other outside source of electrical energy. In certain installations it is undesirable to connect the heater with such an outside source of electrical energy and an object of my invention is to provide an internal combustion heater having an electrical ignition system which does not require an outside source of electrical energy. l

Another object of my invention is to provide an internal combustion heater wherein the same force which is utilized to force Ventilating air through the heater is also utilized to operate an Other objects and advantages-will become apparent as the description proceeds.

In the drawings:

Fig. 1 is a longitudinal, vertical section through a heater embodying a preferred form of my invention;

Fig. 2 is a transverse, sectional View taken on the line 2-2 of Fig. l; I

Fig. 3 is a transverse, sectional view taken on the line 3-3 of Fig. 1; 1

Fig. 4 is a partial, longitudinal section showing a modiiied form of my invention in which I utilize a variable pitch fan for driving a generator;

Fig. 5 is a side view partly in section showing a form of my invention using a variable pitch fan;

Fig. 6 is a longitudinal section through the variable pitch fan control mechanism of the embodiments of Figs. 4 and 5; and l Fig. '7 is a partial, transverse section taken on the line 1-1 of Fig. 6.

'Ihe heater shown in Figs. 1 to 3 of the drawings comprises a cylindrical casing I0 having a cated in the casing I0 and discharges hot products of combustionjnto the longitudinal passages I6 of a cylindrical heat exchanger indicated generally by reference numeral I8. The righthand end of the heat exchanger I8 is closed by a plate 20 having a central opening 22 in communication with an exhaust pipe 24 through which the cooled products of combustion are discharged to atmosphere.

'I'he heat exchanger I8 has a corrugated shell 26 of stainless steel, or other suitable material, and i'lns 28 have their bases located in folds in this shell 26, as best shown in Fig. 2. Those portions of the ns 218 which project radially outward of the Vshell 26 are slotted as indicated at 30 in Fig. l and project into the Ventilating air passage 32 formed between the shell 26 and casing I0 to transmitheat from the hot products of combustion to this Ventilating air.

A muiller 34 is located in the heat exchanger I8 and comprises a sheet metal cylinder 36 closed at its ends by sheet metal plates 38 and 40. A disc 42 or heat insulating material is attached to the plate 38 to protect this end of the muiller from the intense heat of the combustion chamber and the hot gases issuing therefrom. Partitions 44 divide the muiller into compartments which are lled with sound absorbing material, such as glass wool or stainless steel wool, and a row of openings 46 forms acoustic couplings between each compartment and the gas passages I6.

Part of the air which has passed over the ns 28 is diverted into the pipe 50 leading to a Venturi tube 52. A jet 54 discharges fuel, such as gasoline, into the throat of this Venturi tube, this jet being connected to any suitable source ofv fuel supply by a pipe 56. The mixture of fuel and air formed in the Venturi tube 52 is delivered to an induction pipe 58, having a discharge end located in the combustion chamber I4 and so positioned as to deliver the combustible mixture in a direction tangential to the circular wall of this combustion chamber. A housing 62 attached to the combustion chamber provides a pocket 64 for a spark plug 66 which serves to ignite the fuel and air mixture delivered to the combustion chamber. This pocket connects with the interior of the combustion chamber by way of an inlet opening 68 and an outlet opening 10. A ring l2 serves to direct liquid fuel delivered to the combustion chamber into the pocket 64.

Current for the spark plug 66 is provided by a high tension alternator 16 supported in a sheet metal frame 16, mounted in the forward end of the casing I4. A single wire connects the means. A high tension magneto with a suitable circuit breaker could be used in lieu of the alternator, if desired.

When the heater is operating, the air entering the inlet or lefthand end ofthe casing rotates propeller 22 and drives alternator 12 to create a spark across the gap between the terminals of the spark .plug 22 and these sparks ignite and maintain combustion of the mixture of fuel and air delivered to the combustion chamber by the induction tube 52. The hot products of combustion flow from the open or rlghthand end ,of this combustion chamber into the gas passages i2 and give up their heat to the shell 28 and fins 422 of the heat exchanger i2. The cooled products of combustion pass through the opening 22 in plate 20 and now through exhaust pipe 24 to atmosphere.

The air supplied to the heater by the ram or blower absorbs some heat from the walls of the combustion chamber I4 and additional heat from the heat exchanger as this air flows lengthwise of the passage 22. Most of this heated air is utilized as Ventilating air to heat the airplane cabin or other space to be heated and passes from the tapered outlet end 24 of the casing i0 either directly into the space to be heated or into a duct system leading to selected outlet located in the same or different spaces. to be heated.

A small portion of the heated air is diverted into Venturi tube 22 where it mixes with fuel supplied by jet 52 to form a combustible mixture. This combustible mixture flows through induction tube 52 to the combustion chamber where it is ignited by the spark plug 22. The tangential arrangement of the outlet end 62 of the induction tube tends to create a ring of flame in the combustion chamber and this ring of flame cooperates with the spark plug 22 in maintaining combustion. However, since the spark plug continues to operate as long as the heater is in operation, this spark plug alone is sufficient to maintain continuous combustion.

From the foregoing it will be apparent that I have provided a simple, inexpensive, light weight, compact and efficient heater which is entirely independent of any outside source of electrical energy to operate its electrical ignition means. Such a heater may, therefore, belocated in places 4where no outside source of electrical energy is readily available or where it would be disadvanable to have this propeller and alternator operate continuously while the heater is in use. In

certain installations, however, the slight resistance offered by the propeller to air flow through the casing might be objectionable or it might be desirable to discontinue alternator operation to prevent magnetic or other electrical interference or for other reasons it might be desirable to render the alternator inoperative as soon as the heater has attained normal operating conditions. In the modified structures of Figs. 4 to '1, inclusive, I have shown means for automatically discontinuing alternator operation as soon as the heater attains normal operating temperature.

In Fig. 4, the alternator 12' is driven by a propeller 22' having adjustable blades |00 which may be shifted from the operating position shown in this figure to positions in planes passing through the axis of the propeller and alternator so that only the edges of the blades are directly exposed to the flow of Ventilating air through the casing.

tageous to provide wiring-to connect the heater Y with such an external source of current.

I wish particularly to point out that the alternator or other current generator is so located that it is protected against the heat of the combustion chamber and the gas passages leading therefrom, Furthermore the propeller for operating this alternator is located in 'a contracted portion of the casing where the rate of air flow is relatively great and where the density of the air is a maximum because this air has not yet been exposed to the heat of the combustion chamber and heat exchanger.

In the embodiment of Figs. 1 to 3, inclusive, the propeller and alternator continue to operate as long as Ventilating air is supplied to the inlet end of the heater casing. The propeller 22 offers little resistance to the flow of air through the casing and for most purposes it is not objection'- In this form of my invention, the combustion chamber is provided with one or more re-igniters |02 to insure maintenance of combustion in the heater after the alternator 12 has ceased to operate.

In the particular embodiment shown, the propeller blades |02 are pivoted in the propeller hub and are automatically shifted between operative and inoperative position in response to variations in heater temperature. When the heater is cold, the propeller blades assume the operative position shown, but after the heater has been started and reaches operating temperature, these blades are automatically shifted to inoperative position wherein they cease to drive the alternator and oder substantially no resistance to air flow through the heater casing. Since automatically controlled fans of this general type are in commercial use for other purposes, a relatively brief description of the operating mechanism for such a propeller will sufllce.

As best shown in Figs. 6 and 7, each blade |02 may comprise a flat tapered strip of sheet metal orother suitable material supported in a shaft |02 rotatably mounted in bearings provided by the propeller hub |22. Each shaft |04 carries a gear |22 meshing with the ring-like teeth formed on the reduced extension iin of a piston ||2. The piston ||2 is slldably mounted in fluid-tight relationship in a cylindrical extension ||4 of the propeller hub |26. The piston ||2 is urged to the right by a spring i|2 resting on a spring seat ||2 adiustably mounted in the cover plate |22 of the propeller hub |22. The spring seat ||2 has a wrench receiving portion |22 to facilitate adjustment of this spring seat to vary the tension of the spring ||2.

The propeller hub is mounted on the alternator shaft luto which it is attached by a set screw |22 or in any other suitable manner. This shaft has a reduced end |22 which extends through the piston ||2 and'its extension ||2 and is slldably receivedin the-borev |22 of the spring seat ||2. Ihe piston ||2 ispreferably provided with a pin |22 to llmitmovement of this piston under the force of spring vIll. This pin |22 serves to determinev the full operative position of the propeller blades |22.

VThe piston H2 is moved to the left by the expansion of fluid in a bulb |22, illustrated in Fig. 4 as being attached'tothe end wall of the combustion chamber I2. A pipe |24 connects this bulb with a passage |22 formed in a sleeve |22 which constitutes an extension of the housing of the alternator 10'. The passage |36 communicates with the annular groove |40 in the alternator shaft |24 and this groove in turn communicates with a longitudinal passage |40 by way of drill hole |42. Theother end of `the passage |40 communicates with the interior of the cylinder I4 through a cross bore |44 in the shaft |24.

When the heater is not operating, the uid in the bulb |32 is cool and contracted so that the spring ||6 holds the piston ||2 and blades |00 in the operative position shown in the drawings. If it is desired to operateA the heater, Ventilating air is directed into the heater supply pipe |46 from a ram or any other suitable source of air supply and rotates the propeller 82', thereby driving the alternator 16'.

This alternator supplies current to the spark plug 66 and ignites combustible mixture delivered to the combustion chamber |4 through the induction pipe 58. After the heater has been in operation a sufficiently long time to attain normal operating temperature, the fluid in the bulb |32 heats up and expands and moves piston ||2 to the left, thereby shifting the propeller blades so that they lie in planes passing through the axis of the shaft |24. 'I'his renders the propeller inoperative and also causes it to offer a minimum resistance to air flow through the heater. Thereafter combustion is maintained by the re-igniter |02. In

case ignition should fail in the heater for antr reason, the resulting cooling of the bulb |32 will permit spring ||6 to return the propeller blades to operative position, thereby driving the generator and re-starting the heater operation.

The modification shown in Fig. is the same as that of Fig. 4, except for the position of the temperature responsive control bulb |32. In Fig. 4, this bulb is illustrated as being attached to a wall of the combustion chamber and responsive to the temperature of that chamber, whereas in Fig. 5 the bulb |32 is placed in the duct |50 which conducts the heated Ventilating air to the space or spaces to be heated. A pipe |34 connects this bulb with the blade controlling mechanism so that the position of the propeller blades is dependent upon the temperature of the Ventilating air in the duct |50. After the heater has been in operation a short time, the Ventilating air will be heated sufficiently to cause the propeller blades to assume their inoperative position and the a1- ternator 16 will remain idle as long as the heater continues to operate in a normal manner.

Except for the automatic mechanism for shifting the propeller blades, the modifications of Figs. 4 and 5 may be identical with that of Figs. 1 to 3. The particular control mechanism for rendering the propeller blades operative or inoperative is to be considered as illustrative only, as any other suitable type of temperature responsive propeller may be substituted for the one shown in the drawings. Some of the fans of this general type use stationary bimetallic blades which change their curvature with variations in temperature. Similarly constructed propellers could, be used in lieu of the type shown, but where propellers with bimetallic blades are used it would ordinarily be preferable to place a propeller and alternator in the outlet duct |50which would have the disadvantage of subjecting the alternator to higher temperatures and for most purposes the arrange ments shown in Figs. 4 and 5 would be preferable.

It is to be understood that my invention is not limited to the particular details shown and described herein, but may assume numerous other forms. The combustion ch'amber, heat exchanger and muiiler shown herein are claimed in my co-pending applications. Serial Nos. 477,080, iiled February 25, 1943; 476,266, filed February 18, 1943; and 478,259, led March 6, 1943; and othertypes of combustion chambers, heat exchangers and muillers may be used in lieu of the particular ones shown herein.

I claim:

1. An internal combustion type of heater, comprising a combustion chamber, means for supplying a combustible mixture thereto, a heat exchanger receiving hot products of combustion from said combustion chamber, a casing surrounding said combustion chamber and heat exchanger, said casing having a tapered inlet adapted to be connected to a ram or blower, a propeller mounted in said tapered inlet, a high tension alternator driven by said propeller, and a spark plug supplied with current by said alternator and serving to ignite combustible mixture in said combustion chamber.

2. A heater of the class described, comprising a combustion chamber, means for delivering a combutible mixture thereto, a spark plug for igniting said mixture, a heat exchanger receiving hot products of combustion from said combustion chamber, a cylindrical casing enclosing said combustion chamber and heat exchanger, said casing having an inlet adapted to be connected to a source of air under pressure, electrical generating means located in said casing and connected to said spark plug, and a propeller in said casing for drivingsaid generating means, said propeller being rotated by air ilow through' said casing.

3. A heater of the class described, comprising a combustion ch'amber, a heat exchanger receiving hot products of combustion from said combustion chamber, means for delivering a combustible mixture to said combustion chamber, a casing enclosing said combustion chamber and heat exchanger and having an inlet end for Ventilating air, an electrical igniter for said combustion chamber, and electrical generating means connected to said igniter, said electrical generating means being located in said casing ahead of said combustion chamber and heat exchanger, and a propeller for said generating means driven by air ilowing through said casing.

4. A heater of the class described, comprising a combustion chamber, a heat exchanger connected thereto, a casing enclosing said combustion chamber and heat exchanger and having an inlet end adapted to be connected to a source of air under pressure, an electrical igniter for saidA combustion chamber, an electrical generator for said igniter, and a motor located in said casing for driving said generator, said motor being operated by air flow through said casing.

5. A heater of the class described, comprising a combustion chamber, a heat exchanger connected thereto, a casing enclosing said combustion chamber and heat exchangerand having an inlet end adapted to be connected to a source of air, an electrical igniter for said combustion chamber, a generator for supplying current to said igniter, an air driven motor located in said casing for driving said generator, and means for rendering said motor inoperative when said heater is operating normally.

6. A heater of the class described, comprising a combustion chamber, means for supplying combustible mixture to said chamber, an electrical ignited for said mixture, a generator for supplying current to said igniter, a propeller for driving said generator. and means responsive to temperature variations of said combustion chamber for stopping the operation o! said propeller and generator when the heater attains normal operating temperature.

'7. A heater of the class described, comprising a combustion chamber, means for supplying combustible mixture thereto, an electrical igniter for said combustion chamber, a generator for supplying current to said igniter, a propeller responsive to the temperature of said h'eater, said propeller being connected to said generator for driving the same only when current is needed to ignite said mixture, and temperature response means responsive to the temperature of said combustion chamber for controlling the operation oi' said propeller.

8. A heater of the class described, comprising a. combustion chamber, a heat exchanger receiving hot gases from said combustion chamber, means ior circulating air over said heat exchanger, an igniter for said combustion chamber. a re-igniter for said combustion chamber, a generator for supplying current to said igniter, an air operated means for driving said generator, said air operated means including automatic control mechanism for rendering said means inoperative when said heater attains normal operating temperatures.

9. A heater of the class described comprising a casing, a combustion chamber located in said casing, said casing having an inlet adapted to be connected to means for directing air therethrough, a propeller driven by airfilowing through said casing, ignition means for said combustion chamber operated by said propeller, and means for rendering said propeller inoperative when said combustion chamber reaches a predetermined temperature.

10. A heater of the class described, comprising a casing, a heat exchanger located in said casing, said casing having an inlet adapted to be connectedA to a source of air supply. a combustion chamber for supplying hot gases to said heat excxhanger, ignition means for said combustion chamber, a propeller operated by air ow through said casing for operating said ignition means, and means for rendering said propeller inoperative when the air leaving said heat exchanger attai a predetermined temperature.

HENRY J. DE N. MecoLLUM.

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