US2448142A - Vaporizing type burner with - Google Patents

Description

Aug. 31, 1948; R. E. FELL ETAL 2,448,142

VAPORIZING TYPE BURNER WITH RESISTANCE IGNITER Filed Aug. 12, 1943 3' v o 0 K9 3' so 3| 29 Y Ky 22 I I v I I 9 0 Patented Aug. 31, 1948 UNITED STATES PATENT OFFICE VAPORIZING TYPE BURNER WITH RESISTANCE IGNITEB Raymond E. Fell and John W. Miller, Lansing, Micln, assignors to Motor Wheel Corporation, Lansing, Mich., a corporation of Michigan Application August 12, 1943, Serial No. 498,320

3 Claims. (c1. 158-91) 1 This invention relates to fuel ignition devices for burners of the type including a container having a bottom wall into which liquid fuel flows during combustion.

In burners of the type mentioned fuel is admitted to the burner in liquid form. The liquidv spreads out in a pool over the bottom of the burner or the bottom of a pan therein, where it is vaporized and burned; In order to light a cold burner the fuel must first be vaporized by heat and mixed with air before it will ignite. Ordinarily the fuel in such burners is ignited by droppingapieceof burning oily waste or the like intofthe burner Or by inserting a lighted taper therein. That is inconvenient, so provision is made for maintaining a .small pilot fire in the burner during the entire heating season rega'rd-* less -of whether heat is required or not. That eliminates the necessity iorfrequent relighting of the burner but it is wasteful of fuel.

In order toovercome those disadvantages ignition units, usually electrically operated, for permanent installation in the burner, have been deand particularly to Figures 1 to 3 thereof, it will be seen that an ignition unit 10 is mounted in a' burner I I of the vaporizing pot type. The burner may be of the type disclosed in Valjean Patent- No. 2,186,156 granted January 9, 1940. The burner has a bottom wall l2 and a side wall I3 in which a plurality of air inlet openings it are visedbut heretofore they have not been satlsfactory. Their'life is short because they soon become heavily coated with soot which short circuits the heating coils and causes them to burn out. 'Furthermore, they do not always operate j satisfactorily in igniting the burners withwhich they are associated.

Accordingly, the principal object of the present invention is to provides. novel electrical ignition unit that is positive in action and long lived.

Another object is to provide an ignition unit in which the heating coil or coils are protected against deposit of carbon.

Another object is to provide an ignition unit which heats the bottom of the burner so as to more eillciently vaporize the fuel.

A'still further object is to provide an ignition unit in whichcombustion occurs only momentarily during the ignition period.

These objects will more fully appear in the following speclflcation when read in connection with the accompanying drawings, wherein-- Figure 1 is a fragmentary cross-sectional view of a pot type burner showin one form of the invention applied thereto;

Figure 2 is a cross-sectional view taken on substantially the line 2-2 of Figure 3;

Figure 3 is a fragmentary cross-sectional view of the burner taken on substantiallythe line 33 of Figure 1;

The ignition unit employs at least one heating element located within a housing; the heating formed. Aninlet 15 for fuel is provided in the side wall adjacent the bottom.

The fuel ignition unit Ill comprises generally a pair of heating coils l6 and I1 vand a housing therefor. The housing comprises a side wall ll of sheet metal, a top I 9, an annular ring 20 and a shell 2! for the heating coil I. The side wall I8 is generally tubular and is open at its lower end. Adjacent the lower end are a number of holes 22 for the admission of air. A portion of the lower edge is cut away at 23 to admit liquid fuel, vapors and air to the housing. Adjacent the upper end of the housing is a hole 24 for the escape of air and vapors from the housing.

The top I! is formed of some refractory insulating material such as asbestos fiber preferably moulded into .place and completely closing the upper end of the tubular side wall.

The heating coils l6 and H are connected together in series relation and the leads therefrom are connected to a pair of terminal bolts 25 and 26. The terminal bolts pass through the side wall l8 and are insulated therefrom by insulating bushings 27. The leads from the heating coils are embedded in the top wall is by being moulded therein, and the coils are supported in the'proper position within the housing by the leads.

Coil I6 is located adjacent the bottom of the housing and centrally thereof. Coil I1 is positioned adjacent the outlet opening 24. Coil I6 is of relatively great heating capacity, while coil I! may be of smaller capacity. The temperature generated by the coil ll should be above the ignition point of the fuel vapors.

The enclosure of coil I8 is completed by the shell 2! which is in the form ofa truncated cylin- Referring now more in detailto the drawings,

24 and is flanged onto the upper end of the shell 2 I. The outer rim of the ring engages the side wall ll of the housing. Directly below the opening 24 andthe coil i1 is an opening it in the ring.

The opening 28 permits the passage of gases over the coil i1 and out through opening 24.

Attached at one extremity to the side wall ll of the housing adjacent the opening 24 is a bimetal element 29. At the free extremity of the bimetal element is a disk or washer 30 of refractory material. Under certain conditions which will be more fully pointed out hereinafter, the element 29 bends toward the housing so that washer II covers the opening 24 and closes it.

The ignition unit is attached to the side wall of the burner by the terminal bolts and I! which pass through a block of insulating material II and an outer cap 32. The members II and I! are clamped to the burner side wall by drawing up nuts 33 on the terminal bolts.

In operating the ignition element, current is turned on in the coils l8 and i1 and fuel is admitted through inlet II. 'The bottom of the burner is heated by contact with shell 2| which in turn is heated by cell it to a temperature suillcient to vaporize some fuel. The air within the housing is also heated andrises by convection causing a circulation upward through the housing, and out through openings 28 and 24. This effect is that of a chimney. Air is drawn in through openings 22 and 23 and mixed with fuel vapors; Eventually 4 in the burner is limited sting normally combustion occurs high enough in the burner so that air cannot pass downward and admission of fuel and air and a relatively small outlet opening wholly remote from said bottom the air and fuel vapors will form a combustible, in v I fact somewhat explosive, mixture which on contact with the coil i1 is ignited. The flame flashes back toward the surface of the oil and spreads outside of the housing. Several flashbacks or miniature explosions may occur before the fuel ignites outside of the housing. The fuel then continues to burn and the burner operates in the normal manner.

After fuel in the burner is ignited, insufllcient air will enter the housing to support combustion because the air cannot get down to the bottom of the burner. Thus, combustion occurs within the housing only during the ignition period. and

that but momentarily. Soot will not deposit on the unit, at least in any quantity.

To completely prevent soot inside, the bimetal element 29 and disk close the opening 24 and stop the chimney effect through the housing as soon as the burner warms up and begins to oper-- ate normally.

From the foregoing it will be seen that the ignition unit has a heating element located within a housing and that the housing is formed to provide a chimney effect when the heating coil is hot, which sets up convection currents of fuel vapors and air, therebymixing the same and forming a combustible mixture. After the fuel appended claims.

into the housing in any quantity and thereby cause combustion to occur in the housing. That eliminates formation oi carbon deposits in the housing and on the heating coil.

The scope of the invention is indicated in the We claim: I

1. In combustion apparatus including a vaporiaing pot type burner having a bottom wall, a fuel ignition unit for the burner comprising an electrical heating element, a housing partially enclosing said heating element. said housing being formed to provide an air and fuel inlet adjacent the lower end and an outlet adjacent the upper end, said heating element having a portion in heat exchange relation with the bottom wall of the burner and another portion in close proximity to theoutlet from the housing, and heat responsive ineans attached to said housing adjacent said outet and movable under the influence of variations in temperature to open and close said outlet.

1. 2. Fuel ignition means including a fuel recepin close proximity to the bottom wall and coop-- crating with said bottom wall to form a housing, said housing having a relatively large inlet open- .ing closely adjacent to said bottom wall for the wall, electrical heating and ignition means in the housing having a portion thereof adjacent the bottom wall and located in heat exchange rela-' tion therewith, and a shell cooperating with said casing to form a complete enclosure for the por-= 'tion of said heating and ignition. means adjacent the bottom wall of the receptacle.

with the bottom assurances orran wall of the receptacle.

- The following references are of record in the illeof this patent:

UNITED STATES- PATENTS Number Name Date 31,427,059 Bridgford et al. -1... Aug. 22, 1922 1,522,750 Schulenberg Jan. 13, 1925 1,646,509 Steward Oct. 25, 1927 1,724,132 Hart Aug. 13, 1929 1,994,720 Little Mar. 19, 1935 2,008,320 Caron July 16; 1935 2,025,074 is Roe Dec. 24, 1935 2,259,845 Valjean Oct.21, 1941' 2,286,854 Holthouse June 16, 1942 2,309,319 Johnston Jan. 28, 1943 andtheburnerisoper

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