US2403188A

US2403188A - Heating apparatus

Info

Publication number: US2403188A
Application number: US447345A
Authority: US
Inventors: Mccollum Thelma
Original assignee: Individual
Current assignee: Individual
Priority date: 1942-06-17
Filing date: 1942-06-17
Publication date: 1946-07-02
Anticipated expiration: 1963-07-02

Description

July 2, 1946-` H. J. N. MccovLLUM l I 2,403,188

HEATING APPARATUS Filed June 17, .1942, 5 Sheets-Sheet 1 Q v v9 I. 3 91 N QQ Q u@ g N) lJuly 2 1946- H. l.L DE N. MccoLLUM A 2,403,188

HEATING APPARATUS Filed June 17, 1942 :s sheets-sheet 2 July 2, 194s. H. 4; DE N. MCCLLUM y A2,403,138

HEATING APPBATUSl Filed June 1'7, 1942 3 Sheets-Sheet 3 Patented July 2, 1946 HEATmG APPARATUS Henry' .L DeN. McCollum,"y chicago, nl.; Thelma McCollum, executrix of said Henry, J. DeN.

McCollum, deceased Application June 17, 1942, Serial No. 447,345'

. 2 Claims.

1 n; My invention relates generally to internal 'combustion type'heaters, that is, heaters in which combustion takes place in a. sealed combustion chamber, and more particularly to heaters of this type for use on aircraft and other vehicles in which maximum heat production is desired from a heater oi minimum size and weight.

It is an object of my invention to provide an improved heater of the internal combustion type incorporating means to secure uniform and nonexplosive combustion of a combustible mixture of fuel (such as gasoline) and air.

A further object is to provide an improved internal combustion type heater `which is constructed to prevent explosive combustion in the event that the flame in the heater should become accidentally extinguished.

A further object is to provide an improved internal combustion type heater having means to prevent hash-back of the flame into the conduit through which the combustible mixture is supplied to the heater.v

A further object is to provide an improved interna1 combustion type heater which is quiet in operation.

A further object is to lprovide an improved internal combustion type heater which'can be economically constructed, which will be highly efflcient, which will operate satisfactorily under varying conditions, and which will have a long useful life. f l y l Other objects will appear from the following description, reference being had to the accompanying drawings, in which:

Fig. 1 is a fragmentary sectional view ofthe heater, the sections being taken along a `central longitudinal plane;

Fig. 2 is a, fragmentary sectional view taken yon the line 2-2 of Fig. 1;

Fig. 3 is an end elevational view taken on the line 3-3 of Fig. 1, a portion of thecasing being broken away to show the igniter;

Fig. 4 is an end elevational view taken on the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary sectional view to a larger scale than Fig. 1, showing particularly the shield for the igniter;

Fig. 6 is a, fragmentary sectional View taken on the line 6-6 of Fig. 5;

Fig. 7 is a fragmentary transverse sectional view taken on the line 1-1 of Fig. 1; and,

Fig. 8 is a wiring diagram of the electrical components of the heater.

Heaters of the type to which my invention appe'rtains are supplied with a combustible mixture to control the rate of flow of the combustiblemixture to the heater.

Within the outlet portion of the fitting I0 is a flame arrester I8, which, as best shown in Fig. 2, comprises a plurality of small diameter tubes 20, which may be made of copper or other good conducting metal. 'I'he overall cross-sectional areas. of the bores through the tubes 20, plus the cross-sectional area of the spaces between thesetubes, is suiiiclently large so that the iiame arrester does not oiier an undesirably high resistance tovlow of the combustible mixture through the llame arrester. The tubes, however, are of such small diameter that they may act in a well known manner to prevent the propagation `of a flame through the flame arrester.

The valve fitting I0 is suitably secured to the inlet boss 22 of a combustion chamber casting 24 by studs 26, a portion of the wall of a main casing 28 being clamped between the fitting I0 and the boss 22. It'will be noted that the llame arrester tubes 20 are located in a cylindrical tube 30, which extends into the bore of the boss 22 and has a reduced diameter end portion 32,

which projects into a combustion chamber 34 formed within the casting 24. The portion 32 is provided with a plurality of ports 36 formed by louvers 38 struck inwardly from the portion 32 to cause the combustible mixture to i'low in a circular path as it leaves the ports 36. A ring 40 is located within the tube 30 to form a smooth velocity of ow increasing throat, while a cusp'- shaped plug 42 is secured within the end of the projecting portion 32. By virtue of the provision of the ring 40 and p1ug'42, as well as the louvers 33,` the mixture enters the combustion chamber with a smooth uniform vertical iiow.

As best shown in Figs. 5 'and 6, thecombustion chamber casting 24 is provided with a sidewardly extending boss 46, which is threaded to receive an igniter plug 48, within .which is locateda coiled wire 50 of Nichrome orsimilar high resistance metal.. the inner end of this coil being welded tothe inner end ofthe plug-48 and the ture in the combustion chamberfrom too rapidly 5 cooling the igniter coil 50 when the latter is energized, the casting 24 isformed to provide a baffle 54. This, baii'e is generally convex in shape to provide openings at its top and bottom for the circulation of the combustible mixture past the' l0h end of the igniter coil 50. By thus restricting the` circulation of the combustible mixturepastthegigniter wire coil, the latter may be heated more ra'pidly to a temperature at which? it Vw'ill "ign'ntep 5 the mixture, and, since thefrnxtureY vflows* `past '15'5 the igniter at a lower velocity, it is more susceptible to ignition. The ignition l'of the-mixture is thus greatly facilitated by theV provision of the.-

baille 54. This is an important factor in securving reliable ignition of Ythe mixture at extremely low'A temperatures and when'the mixtureis'supplied at lless than atmospheric pressures, aswhen the heater is; used upon aircraft flying atlhigh altitudes. f

In order to make it unnecessary-to reenergize the igniter 50 whenever the flame in the'combustion chamber is vaccidentally extinigulshed V due to a temporary; interruption in the supply ofV combustible mixture, or a temporary change inthe proportion of fuel to air in the mixture which may render the mixture vcomparatively incombu'stible; there is providedA areigniter 56;. which is secured to a plug 58 andi extends horizontally into the combustion chamber. This regniter is preferably in' the form of 'a spirally coiled sheet or Inconel or similar heat. and corrosion` resistant metal. '5

i The combustion chamber casting 24 is secured to a clamping ring 59 by a plurality of'stucls 60,

the ring v59 having a. plurality of Yradially extendf ing Yarms 62, to which the outer casing 28 is fixed by"screws 54. A heat exchanger shell166, preferably made of copper or other good heat conductor, Vhasits flanged end 63 clamped be:- twe'en the ring' 58 and the casting 24, a suitable gasket lbeing provided to seal this joint. The other end of theshell. 0E is brazed'or otherwise suitably secured Vto an outlet fitting l2.A

` Within the shellVV 68 is a hollow filter land muffierV structure comprising aV cylindricaltube" i4 having aV plurality of radial ribs 16;' 'Y The outer end surfaces'cf the ribsl are'of the same diam'- eter as the inside diameterV of the shell Slgso that there is a press-fit contact between the' ends of the ribs andthe shell 66, resulting in good heat conductionjbetween these parts; `The cylindricalft'ube 14 has a pluralityof spacedsmall diameter ports, i8 formed' thereirr.at'fthe :bases of thegrooves between the rlbsI-'lftov provide Vre.-

strictedcommunication I with the. interior' of: the f tube 14. The tube I4 isfllled? with7 a Asuitable sound and vibrationdamping material', such as stainless steel wool or glassxwool $30'. The.' 'conr- Y bustion chamber endjof the-'cylinder 14 is' closed byY a plug V82, while the discharge rend. orthis f cylinder vis closed by a hollow generallyfconical endl cap 84, which issuitably flanged toipermit the adjacent. end ofthe cylinder. 14' to; besecurled thereto byaspinning.operation.:AV f'. fY

`A bolt 88 isjriveted-inzthe end* cap 84 Yanizljprn- Y jects through `a suitable boss/8.8 Vformed'ontlfie outletftting '|2; ajnut fbeing threaded? on; this bolt 'to make it possiblev to dra'w the .en-d* cap? 84 and. parts,V assembled fftherewithinto. properly spaced: relationship giwitrrres-pecttogthe outlet 'fitshaped portion projecting into the bore 86. The outerend of the nozzle 98 is suitably threaded for' connection to a discharge cond-uit.

The combu'stionichamber casting 24 is providedfwjthaplurality of heat radiating lns |00, whilefthe shell Bfls provided with a plurality of 4genera-llyradial fins |02, which may be brazed or, ldepending upon the metals used, welded to the shell. Ihese ns |02 preferably extend into close proximity with the inner surface of the outercasing-'28L The outer casing 28- is secured to'the heat yexchange' assembly notl only byf the nozz-le'ttingd, VA suitablyanged bracket |04 is securedtortheoutletgi'itting '|12 and to the outer casing 28 (see Fig. 4) The outer casing 28v has'a flange |06 at its vinlet end for/ attachment toV a blower or aconduitl through which airtofbe heated is conveyed, and has asimilar flange |01 at itsV outlet end Vfor connection with aconduit for conveying theA heated airv tothe space tobe heated.: The casing 28 also has a projecting portion |08 (Fig. 3) -suitablyto protect the igniter plug 48 and theelectrica-l connectionsthereto and also isprovided witha protuberance ||0 tojhouse anc electrical connection fitting.

The temperature; responsive overheat switch |24 (Fig. 8) is mountedfin av tuba 2^-(Flg.i 3)., which isV located betweenffins |02 near the V,corn- Vbust-ion chamber. f A temperatureresponsive: lg'- rlter switch |22 (Fig. 85) may be located-in a tube I4Y (Figg'l) inear the outlet end of the 4heat` grounded. Uponclosing `a'niaster control switch` |20, current ls. supplied through a thermostatically operated igniter switch |22 (in tube ||4) toi'gnit'e'rf 50, the other terminal of whichl is connected toground;v Thermostatic switchesv |24 and |25 are connected'v inY series with a solenoid operated valve'l2'8 by which the '.supplyiof fuel mixture to the heater isjcontrolled. The switches |24 and |25 are contained intubesv IfIZand'fiII-B,

respectively.v l

It will be apparentfthatxupon. closure tof".` the switch |'20-...the-igniterll=will bey energized', and,

Vassurningfthat the heateriis cold,.the switches; |24

and las will `iiecioseu :anuthe solenoid 'vais/e428 thus" energized. Thus, -thev supplyiof fuel mixture is fed to the heater and ignitedfby' the l'iotz're-l-V Y sistancev wire igniter 50. lAsv soon as,c the heater has'attained substantially its normal. 'operating' temperature, the thermostatic. switch: L22.-V will open' to cut 'off -thefcurrentisupply to tha-igniter.

If for any reason the heaterj shouldbecomeex- `cessively hot,.ras1by failure'ofgthe, supply; ofivntilating airji forced: thrdughlthej casingijfthe high temperature as td :cause :ittdop'err` thehincuit; t o.. the.- .solenoid valve .i |28, :whereupon: the

terrupted, and dangerous overheating of the apparatus prevented. v

In normal operation, the air flow through the flame arrester I8 is suiliciently rapid and these tubes are of sufficiently small diameter that the flame from the combustion chamber cannot flash back through these tubes and the spaces between them to the inlet iitting l0. The mixture sup'- plied through the flame arrester I8 is maintained at high velocity due to the constriction formed by the member 40, and the mixture is given a rotary component of flow by the louvre vanes adjacent the ports 36. This rotary iiow results in complete mixing of the fuel and air, so that it will be substantially uniform as it meets the burning mixture in the combustion chamber. pronounced turbulence does not, however, interfere with initial ignition of the mixture by the igniter 50 because of the protecting baflle54, which shields the igniter from this rapid ilow.

Due to the fact that the combustion chamber is L-shaped, the degree of turbulence is increased so that complete combustion takes place and there is no possibility of a stream of fuel mixture passing through the combustion chamber Without burning. This is an important factor when the heater is used on aircraft ilying at high altitudes. Under these circumstances, the air of the mixture is so rareied that all conditions must be favorable in order that combustion may be maintained within the combustion chamber. 'I'he difficulty of thisV problem may be appreciated by the fact that a candle will not burn when This in atmosphere at a pressure corresponding to that mixture, is inhibited by the provision of the muff ing or sound vibration filtering chamber 2|), which communicates with these passageways through the small holes '18.V This muiller construction is of importance in assuring steady and uniform combustion under varying conditions of operation.

The combustible mixture leaving the passageways between the ribs 16 flows through the restricted passageway 94 at a relatively high velocv ity. It is of importance to Vreduce the volume of this passageway 12 to a minimum in order to prevent, immediately after starting operation of the heater, an accumulation of gas mixture which might be ignited by the heated products of combustion and cause an explosion. Such explosive l 6 ,f Y combustion in this passageway might cause extinguishment of the iiame in the combustion chamber due to the interruption of the supplyY `to a space of lower pressure than that of the fuel mixture supply. The Venturi-shaped passageway in the outlet fitting 98 has the advantageous property of appreciably compensating for changes in relative pressure of the fuel mixturesupply and exhaust and functions in a manner more fully disclosed 'in my prior Patent No.

aierglvsa f While I have shown and described a particular embodiment of my invention, it will be ap parent to those skilled in the art that numerous modifications and variations may be made without departing from the underlying principles `of. the invention. I therefore desire, by the following claims,v to include within the scope of the invention all such modifications and variations by whichsubstantially the results thereof may be obtained by the use of substantially the same or equivalent means.

I claim:

1. In a heater of the internal combustion type, a combustion chamber casting having an elbowshaped combustion chamber formed therein, an igniter receiving opening extending into said combustion chamber, an igniter element secured to said casting and communicating with said combustion chamber'through said opening, a connection to one end of said combustion chamber for supplying a combustible mixture theretoa heat exchanger, a connection securing said heat exchanger to the other end of said combustion chamber casting-and a reigniter elementextending into said combustion chamber in a direction toward said heat exchanger and removable therefrom without disturbing the other connectionsv to said combustion chamber casting.

2. In a heaterA of the internal combustion type having means for supplying a fuel mixture and means for withdrawing the products of combustion therefrom, the combination of a casting A having an L-shaped combustion chamber formed therein and said casting forming a smaller space Y communicating with the combustion chamber, an electrical igniter secured to said casting and having its igniting element located in said space, and Y a baille forming part of said combustion chamber casting and located in front of said space to prevent direct iow of combustible mixture from said combustion chamber to the igniter element.

HENRY J. DEN. McCOLLUM.