US2388969A - Airplane heating system - Google Patents

Description

Filed Feb. 14, 1941 H g/ n50 5. 114442-051 0 ATTORNEY end of the heater structure.

Patented not. 13, 1945;

UNITED wes PATENT OFFICE AIRPLANE ammo SYSTEM Frederic o. Hess, Germantowmand Richard E. n.

Wakefield, Aidan, Pa., assignors to Sales Corporation of America, a corporation of Pennsybvanla Application February 14, 1941, Serial No. 378,916

Claims. (on. 158-28) This invention relates to heaters adapted to be operated on liquid fuel, such as gasoline, for example, and it is an object to provide an improvement for operating such heaters whereby .the

larity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however/its advantages and specific objects attained with its, use, reference should be had to the following descriptive matter and accompanying drawing in which the single figure more or less diagrammatically illustrates a heater embodying the invention.

A fluid heater A embodying the invention comprises structure providing an annular heating space E having distributed heatinggas outlets B at its upper end and having its lower end closed by a burner wall 0 formed with burner orifices C leading to the heating space B from a burner inlet chamber D which extends across the lower The burner C is advantageously of the type disclosed and claimed in the Hess Patent No. 2,228,114, granted January '7,

- 1941, in that the burner wall is formed by radially extending lamina or plates of ceramic material with grooves in their sides, which form the orifices C. 1

Air is 'drawn into the inlet chamber D. by a fan or blower F centrally disposed with respect to that chamber, and a supply conduit E which may lead from the atmosphere external to the airplane in which the heater A is mounted, opening to the chamber D at its center. is driven by an electric motor G located within the space b surrounded by the structure forming heating space B. The motor G is cooled and some of the heat generated in the heating space E isgiven up to air moved through the space b by a fan 9 driven by the motor G.

In the preferred construction shown, the blower F also serves as a means for mechanically atomizing a liquid fuel, such as gasoline, for example, and mixing it with the air drawn into the chamber D to form a. combustible mixture which passes through the burner orifices C into and is burned in the heating space B. The liq- Pipe H of a pump I, said having its dis: charge end axially disposed relative to the blower F and extending into the space about which the inner ends of the blower F bladesor vanes F turn. The pump I comprises an impeller rotated by an electric motor 1A., The discharge end of the pipe H is closed except for one or more fine orifices H, each discharging a jet of liquid fuel radially into the space through which the blades'F' move. The formation of a combustible mixture of air andliquid fuel in the manner and by the means described is the joint invention of John W. Townsend and Frederic O. Hess, one of the joint applicants herein, and described and claimed in Patent No. 2,314,089, granted March 16, 1943.

The heating chamber outlets B extend radi-' ally inward from the upper portion of the heat of an exhaust fan K. The impeller of the fan K is rotated by an electric motor KA, and the products of-combustion drawn from the heating space B are discharged by the fan K through a discharge pipe K into the external atmosphere. A butterfly valve or damper K in the exhaust K is connected to a regulator K shown as a bellows deviceadapted to expand and contract and to thereby throttle the passage K more or less as the pressure of the atmosphere is increased and decreased by airplane altitude changes, so that combustion air and liquid fuel may be supplied to the heater at suitable rates by operating the blower F, fan K and pump I at proper and readily maintained speeds.

.The blower F uid-fuel thus atomized is supplied by the outlet medium in liquid form through a pipe L from the outlet of a circulating pump M. The liquid heated in the tubular coil L passes from the latter in liquid form through an outlet pipe L connected to the heat inlets 0' of radiator elements 0. The elements 0 have their individual outlets 0 connected to a return conduit 0 through which liquid discharged from the radiators is returned to the inlet of the pump M. The return conduit 0 includes a heat exchanger section 0 adapted to absorb heat from the spent heating gases passing to the atmosphere through the pipe K The return conduit 0 includes a section 0 which is adapted to absorb heat from and thereby cool the cylinder wall of an internal combustion engine P.

The engine P, which forms the prime mover element of the heating'system, directly drives a dynamoelectric machine Q. In normal operation, themachine Q acts as a generatorand has its terminals connected to service conductors l and 2 by a switch S. The latter, however, may be adjusted to connect the terminals of the generator Q to the terminals of a small storage battery R to energize the machine Q for operation as a starting motor for the engine 1?. The engine P is arranged to drive the pump M employed to circulate the heating medium The current generated by the dynamoelectric machine Q energizes the motors IA, G and KA, when the switch SA connects the service conductors l and 2 to the branch-service conductors 3 and 4, The conductors l and 2 when energized supply energizing current to fan motors TA operating fans T employed to move air over the heat dissipating surfaces of the radiators O. The speed of each fan motor TA may be regulated by adjustment of a corresponding regulating rheostat T. The switch SA may be opened to interrupt the operation of the heater during period in which the fan motors TA may continue in operation.

The liquid fuel, which may be gasoline, for example, is supplied under pressure from a suitable tank or other source, through one branch U from a supply pipe U, to the inlet of the heater pump 1, and through a second branch U from the supply pipe to the carburetor V of the internal combustion engine P. The engine P is provided with a magneto W which supplies energizing current through a conductor 5 to the ignition means P of the engine P, and supplies current through a conductor 6 to ignition contacts 1 extending into the heating space B and employed to maintain combustion in said space as long as a combustible mixture is being passed into the space through the orifices C. a

To avoid fire risk or other trouble due to the accumulation of deatomized' or condensed liquid fuel, such as gasoline, for example, in the heater A when starting the apparatus into operation when cold, we provide porous bodies of ceramic material in various portions of the apparatus to absorb and hold the deatomized or condensed gasolin until the apparatus warms up sufficiently to volatilize such gasoline. Thus, porous discs J of ceramic material are placed beneath the burner wall C, and a tubular porous body JA of ceramic material is arranged coaxially with the blower F and beneath the latter. The tubular body JA of porous ceramic in 'the combustion air supply conduit E is beneath the region at which the fuel line H terminates at the vicinity of the fan F. In this way, any liquid fuel discharged from the orifice H and passing downwardly within the conduit E, as when the heater A is shut down, for example, is collected within the conduit E to retard backward flow of such fuel beyond a predetermined point in the air supply conduit. When operation of the heater is subsequently started, following a shut down period, air passing through the conduit E picks u fuel collected by the porous body JA.

As will be apparent, wide variations in atmospheric pressure due to substantial changes in airplane altitude, do not prevent the desired operati'on of the heating system, since the use of the power actuated pump 1, blower F, exhaust fan K and regulator K responsive to atmospheric pressure make it possible to move an adequate weight of gasoline and combustion air into the combustion chamber B at all times when the heater is in operation. While in accordance with the provisions of thestatutes, we have illustrated and described the best form ofour invention now known to us, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit and scope ot-our invention, as set forth in the following claims.

Having now described our invention what-we claim as new and desire to secure by Letters Patout is:

1. A- heater including structure providing a combustion space and an inlet space and a dividing wall therebetween having a numberof openings therein, means including a blower having a rotatable fan therein and a liquid fuel line terminating in the vicinity of the fan for discharging a combustible mixture of atomized fuel and air into the inlet space which is subdivided into a plurality of streams at the openings for combustion in the combustion space, and a body of porous material in the inlet space in the path of fiow of the combustible mixture and another body of porous material about a portion of the fuel line in the vicinity of the fan, said bodies beingprovided to absorb liquid fuel when the heater is relatively cool, as at starting, for exmeans including a liquid fuel line having a discharge orifice terminating in the passage for dis charging fuel into the air stream to produce the combustible mixture of air and fuel, said conduit means including a portion extending vertically downward from the region of the fuel discharge orifice, and a body of porous material in said conduit means for absorbing any liquid fuel which may fiow downwardly through the vertically extending portion thereof and from which fuel is picked up by air supplied to the heating space through the passage by said blower.

3. A heater including structure (providing a heating space adapted to be heated by combustion of a mixture of air and fuel, means providing a passage for supplying air to the space including conduit means and a blower therein, means including a liquid fuel'line having a discharge orifice terminating in said passage for discharging fuel into the air stream to produce a combustible mixture of air and fuel,.said conduit means including a portion extending vertically downward from the region of the discharge orifice of the fuel line, and means embodied in said conduit means for collecting any liquid fuel which may fiow downwardly through the vertically extending portion thereof to retard backward flow of such a fuel beyond a. predetermined point in the air supply passage.

4. A heater including structure providing a heating'space adapted to be heated by combustion of a mixture of air and fuel, an air supply conduit, means for supplying air to the space through said conduit comprising a blower havin a rotatable fan therein, said conduit including a portion beneath said blower having a vertically extending part connected at its upper end to the inlet of the blower, means including a liquid fuel line having a discharge orifice at the vicinity of the fan for discharging fuel into the air stream to produce the-combustible mixture of air and fuel, and a body of porous material in the air supply conduit beneath the discharge orifice of the fuel line to absorb any liquid fuel which may pass downwardly through the vertically extending part and from which fuel is picked up by air supplied to the space through said conduit by said blower.

5. A heater including structure providing a heating space adapted to be heated by combustion of a mixture of air and fuel, an air supply conduit, means for supplying air to the space through said conduit comprising a blower having a rotatable fan therein, said air supply conduit including a portion beneath said blower and having a vertically extending part connected at its upper end to the inlet of the blower, means ineluding a. liquid fuel line having a discharge orifice at the vicinity of the fan for discharging fuel into the air stream to produce the combustible mixture of air and fuel, and means embodied in the air supply conduit beneath the discharge orifice of the fuel line for collecting any liquid fuel which may pass downwardly through the vertically extending part to retard backward flow of such fuel beyond a predetermined point in the I air supply conduit.

FREDERIC o. HESS. RICHARD E. B. WAKEFIELD.

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