US2458042A - Fuel feeding system for liquid fuel burners having means for disposing of fuel vapors - Google Patents

Description

Jan. 4, 1949. w s, JR 2,458,042

FUEL FEEDING SYSTEM FOR LIQUID FUEL BURNERS HAVING MEANS FOR DISPOSING OF FUEL VAPORS Filed March 20, 1944 2 Sheets-Sheet l Jan. 4, 1949. L. A. WILLIAMS, JR 2,458,042

FUEL FEEDING SYSTEM FOR LIQUIDFUEL BURNERS HAVING MEANS FOR DISPOSING OF FUEL VAPORS Filed March 20, 1944 2 Sheets-Sheet 2 Patented Jan. 4, 1949 FEEDING SYSTEM FOR LIQUID FUEL UBURNER'S .IIAVING MEANS FOR DISPOS- ING OF FUEL VAPORS Lynn A. Williams, Jr., Northfield, 111., assignor to "Stewart-"Warner Corporation, Chicago, 111., a corporation of Virginia Application March 20, 1944, Serial No. 527,229

3 Claims. 1

Myinvention-relatestofuel'feeding systems for heaters, and more particularly to fuel feeding, systemsfor heaters of the internal combustion type usedin airplanes wherein it is of great importance operation ofthe heater.

ation of the heater. i

in, operation, and easy to install.

parentwas the description proceeds.

'In the drawings:

showing the heater in longitudinal section;

fuel under pressure.

fuel toitheburner through a pipe I.

The burner Bis referably especially designed to provide means for preventing vaporized fuel 5 bustion chamber is automatically controlled conwhich may be a present from intefering with the jointly by the pressure drop across the heater, and the absolute pressure is claimed in Patent No.

.An object ofmy jinventionis to provide a new 2,374,569, issued April 24, 1945 to Vernon N. Traand improved fuel feeding system for internal montini. Such a burner includes a generally combustionheaters wherein .mechanism is proelbow-shaped induction pipe casting In having a vided to prevent any vaporization of the fuel flange l2 andatubular extension [6 which is conwhich may occur, from interfering with the opernected at one end to the combustion air supply pipe E. A tubular sheet metal casing I 8 is secured Another object ofmy invention. is to provide to the flange l2 and to the extension IS. The upa'newandfimproved fuelfee'ding systemfor heatper portion of the casing 18, together with a ers having means iorjtaking careof vaporized fuel, tapering sheet metal section 20, forms a combusand which is 'inexpensive to manufacture, reliable tion chamber22. The upper end of the section is welded or otherwise suitably secured to the end Other objects .and advantages will become apwall 24 of the heat exchanger 0..

20 The heat exchanger C may be of any suitable construction adapted to receivethe products of .Fig. 1.is a view of the. heater installation .emcombustion from the combustion chamber 22, and bodying .a preferred form of .my invention and to transfer heat to ventilating air which flows past the combustion chamber and associated parts Fig. 2 isa sectional .viewof the pressure car- 25' and through or around the heat exchanger itburetorand is takenon the line 2- 2 of Fig. 1. self. In the particular embodiment selected for .In Fig. 1. of the "drawings .1 have illustrated my illustration the heat exchanger C is of the spiral invention asjbeing incorporated in a heater intype and has an outlet 26 which may be constallation comprising in general a heater indinected with any suitable exhaust pipe through cated generally by reference character A and 30 which the cooled products of combustion are dishaving aburner B and heat exchanger C. Vencharged to atmosphere. tilating air is supplied to the heater through an An igniter supporting tube 28 rojects through inlet .pipeD connected. to a ram, blower or other the section 20 and is suitably welded thereto. suitable source, of air. The heatedventilated air This tube houses an igniter shell 32. discharged .irom the heat exchanger C flows igniter shell 32 is the usual hot wire igniter 34, the through an outlet .duct D. to the aircraft cabin or inner end of which is secured to the shell 32 and other space orspacesto beheated. Air for comthe outer end of which is suitably connected to bustion purposes is suppliedto the burner B by a wire 36 which is insulated from the shell 32 and way of a combustion air supply pipe E which may supplies energizing current to the igniter. also be connected witharam, blower or other suit- 40 able thermostatic control means are preferably able source of airwhich maybe the same as or inprovided to cause energization of the igniter durdependent of. the source .for .the ventilating air ing starting and in the event that the flame in the burner becomes extinguished.

Ahfuelfeed controldeviceF. is interposed be- The fuel feed regulator F which controls the tween theburner B and thefuel supply pipe G flow of fuel to the burner is best shown in Fig. 2. which isaconnected to any suitable source of liquid This mechanism is illustrated as comprising a The pressure on the fuel body casting I I0 and upper and lower castings I [2 may .behcreated by a pump, gravity head, or in and I M are secured to the body I Hi by cap screws any other suitable manner. A solenoid shut-off HE. A plate H8 is located between the upper valve .11 .is preferably incorporated in the fuel casting or cover H2 andthe body ill! and serves supply line G to the .fuel feel device F to comapurpose whichIshall hereinafter describe. Suitpletely cut off the supply of fuel when the burner able gaskets are interposed between the various is not operating. The fuel feed device F delivers parts to render theassembly air and fuel tight.

The feed regulator has an air inlet chamber to maintain the gravimetric rate of air flow to the combustion chamber of the heater substantially constant. A burner suitable for this purpose in which the rate of flow of air into the com- Within the Suit- IZU connected by a pipe I22 jto a pitot tube I 3 located in the ventilating air inlet pipe D and having an inlet I26 directed upstream of the air flowing in this pipe whereby air is forced through the inlet I26 and pipe I22 into chamber I20. A second chamber I28 communicates with the chamber I20 by way of a valve comprising a sleeve I30 having a slot I32 formed in the wall thereof and a valve member I34 which shifts to variably uncover the slot I32 and thereby variably control communication between the chambers I20 and The valve member I34 is controlled by an aneroid bellows I36 located in the chamber I28. This bellows is attached to the lower casting II4 by a screw I38 which may be adjusted to support the valve member I34 in any desired position. A look nut I40 secures the screw I38 in adjusted position and a pin, not shown, prevents rotation of the bellows with the adjusting screw I38. A cap I42 encloses and protects the outer end of the adjusting screw I38.

A portion of the air entering the chamber I28 by way of the valve slot I32 is bled through a restricted outlet I44 and a pipe M6 to the outlet or downstream end of the heater. The slide valve which controls communication between the chambers I20 and I28 serves to maintain a constant pressure in the chamber I28. This constant pressure is communicated through a bore I48 to a chamber I50 surrounding a bellows I52. The interior of this bellows communicates through a slot I54 with the air inlet chamber I20 so that the pressure in the interior of the bellows I52 corresponds at all times with the pressure in the inlet chamber I20 and reflects the gravimetric flow of air in the ventilating air supply pipe D. The bellows I52 controls the position of a fuel metering means which I shall now describe.

Referring particularly to Fig. 2 it will be seen that the fuel from the fuel tank or other source of supply enters the fuel feed device through a bore I56 leading to a valve chamber I58. The upper end of this chamber I50 is closed by a tubular plug I60 threaded into the casting H4 and having a discharge port I62 variably controlled by a valve I64. The valve I04 has a tapered upper end cooperating with a flaring or tapered portion of the plug I50 leading to the port I62. The valve I64 has a valve stem I66 which is threaded at its upper end into a socket member I68 attached to the base of the bellows I52. The lower end of the valve I64 is provided with a slot I'I0 receiving the tongue I12 of a valve adjusting member I14. The adjusting member. I14 has a kerf I10 into which a screw driver or similar tool may be inserted to rotate the adjusting member I14, valve I64 and valve stem I60 and screw the latter into or'out f the member I68 attached to the base. of the bellows I52. A nut IIII clamps the adjusting member I74 in adjusted position and the cap I 80 encloses and protects the lower end of the adjusting member I14 and its nut I18.

Fuel flowing past the fiow control valve I04 and through port I62 enters a float chamber I82 containing a float I84 pivotally mounted at I36 to an upstanding boss I88 formed integral with the casting H4. The valve stem I08 extends completely across the float chamber I82 and passes through an opening I90 in a partition I92. In order to prevent fuel from flowing through the opening I90 into the chamber I50, a bellows I94 connects the flange I96 of member I68 with a ring I98 held in sealing engagement with partition I92 by screws 200.

.fioat chamber I82 and bores 2I2 and 2I4 which together constitute a vapor escape passage communicating with pipe I leading to the burner. The accumulation of any appreciable quantity of vapor in the float chamber will cause the float to drop sufficiently to open valve 2I0 whereupon the vapor can escape to the pipe I by way of bores 2I2 and 2M The orifice 200 provides a sufiicient pressure differential thereacross to insure free discharge of vapor as soon as valve 2) opens Liquid fuel or vapor can pass from the float chamber I82 through opening I'to the interior of bellows I94. The pressure in this bellows therefore corresponds at all times to the pressure in the float chamber 32., This float chamber pressure acting over the area of bellows I94 tends to resist expansion of bellows I52 under the force' created by air flow inthe ventilating air supply pipe D, andthis resistance is taken into account in designing the relative sizes of the bellows I94 andI52. .1

In the operation of the apparatus, combustion air under pressure is supplied through pipe E to the inlet extension I6 of the burner] casting I0 and flows in the direction of the arrows. At

the same time, fuel under pressure is supplied by the fuel feed device F to the burner through the pipe I. In the particular arrangement shown the quantity of fuel supplied varies with the pressure drop across the ventilating air side of the heater. 1

The combustible mixture produced in the burner will be ignited bythe electrical igniter 34 and substantially complete combustion will take place within the combustion chamber 22 and the inlet end portion of the heat exchanger 0.

In the particular embodiment shown, the fuel supply is caused to vary with the pressure. drop of the ventilating air across the heater so .that the rate of fuel supply varies with the heat cut put requirements corresponding to variations in the rate at which ventilating air is fed through the heater. By connecting the air inlet and air outlet ports-of thefuel feed device to different parts of the heater, the fuel supply can be caused to vary with any other characteristic of the heater, and it is to beunderstood that my inven-; tion is not'limited to an installationidenti'cal with that herein disclosed. p v

Under certain conditions some vapor is given off by the fuel and if means is not provided for automatically taking care of this vapor, the

presence of the vapor will interfere with the proper operation of the heater. A most common cause of such interference is the accumulation of slugs of vapor between slugs of liquidfuel and the irregular operation of the burner resulting from'alternate deliveries of slugs of vapor and liquid me; Where the slugs of, vapor become sufficiently large. the combustion in the heater may be put out when a particula'rlylarge vapor slug is delivered thereto.

With my invention the vapor accumulates in the float chamber; andwhena predetermined amount has accumulated,'this vapor is'supplied to the burner in diluted form mixed with liquid fuel, so that at no time does the burner receive only vapor. The proportion of vapor is at no time large enough appreciably to affect burner operation. In other words, my invention automatically relieves the accumulated vapor in such manner that efficient burner operation is maintained and vapor accumulation is prevented from building up to a point where it can interrupt the supply of liquid fuel to the burner.

The heat exchanger shown and described is claimed in the application of William C. Parrish, Serial No. 490,162, filed June 9, 1943, now Patent No. 2,432,929, issued December 16, 1947. Certain features of the fuel feed control device are claimed in my earlier application, Serial No. 476,429, filed February 19, 1943, now Patent No. 2,427,758, issued September 23, 1947, and in the patent of William A. Marshall, Jr., No. 2,381,358, issued August 7, 1945, therein referred to.

While I have illustrated and described only a single embodiment of my invention, it is to be understood that my invention may assume numerous other forms and includes all modifications, variations and equivalents coming within the appended claims.

I claim:

1. In combination with a burner, a fuel feedin system comprising means providing a fuel chamber, means for supplying liquid fuel under pressure to said chamber, said fuel being of a nature to give off vapor, a conduit which conducts said liquid fuel from said chamber to the burner, means forming a vapor passage and a passage for liquid fuel connecting said conduit with the upper and lower portions respectively of said fuel chamber whereby vapor from said chamber is mixed with the liquid fuel conducted to the burner, and a float controlled valve responsive to fuel level in said chamber regulating communication between said chamber and the vapor passage.

2. In combination with a burner, a fuel feeding system comprising means providing a fuel chamber, means for supplying liquid fuel under pressure to said chamber, said fuel being of a nature to give off vapor, a conduit which conducts said liquid fuel from said chamber to the burner, means forming a vapor passage and a passage for liquid fuel connecting said conduit with the upper and lower portions respectively of said fuel chamber whereby vapor from said chamber is mixed with the liquid fuel conducted to the burner, and a float controlled valve responsive to fuel level in said chamber and regulating communication between said chamber and the vapor passage, together with means forming a flow restriction in the other passage.

3. A fuel feeding system for an aircraft heater burning a liquid fuel, said system comprising means providing a fuel chamber, means for supplying liquid fuel under pressure to said chamber, said fuel giving off vapor under certain conditions, automatic vapor relief valve means for said chamber, a conduit adapted to feed liquid fuel from said chamber to said heater, and conduit means adapted to feed said vapor from said relief means back into the liquid fuel in said conduit for preventing interruption to the flow of liquid fuel to the heater by such vapor.

LYNN A. WILLIAMS, JR.

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

UNITED STATES PATENTS Number Name Date 1,736,033 Barlow Nov. 19, 1929 1,919,413 Buck July 25, 1933 2,046,813 Dunham et al July 7, 1936 2,232,351 Udale Feb. 18, 1941 2,241,655 Carlson May 13, 1941 2,314,089 Hess et al Mar. 16, 1943 2,315,881 Thomas Apr. 6, 1943

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