US1926394A - Fluid fuel burner ignition device - Google Patents

Description

Sept. 12, 1933. l. E.'MCABE FLUID FUEL vBURNER IGNITION DEVICE 3 Sheets-She et 1 Filed April 2. 1950 INVENTOR BY IRA. ELI/l CABE'. W M

ATTORN EY Sept. 12, 1933. I. E. McCABE FLUID FUEL BURNER IGNITION DEVICE Filed April 2, 1930 3 Sheets-Sheet 2 INVENTOR IRA. E. /1 CASE? ATTORNEY Sept; 12, 1933.

l. E. MCCABE 1,926,394

FLUID FUEL BURNER IGNITION DEVICE Filed April 2, 1930 5 Sheets-Sheet 3 Illl ATTORNEY Patented Sept. 12, 1933 UNITED STATES,

PATENT OFFICE 9 Claims.

This invention relates to improvements in ignition devices for electrically operated fluid fuel burners and more particularly to devices of this character known as the hot wire type.

It is customary to provide electrically operated fluid fuel burners, particularly for domestic heating purposes, with an electrical ignition device usually so controlled that it will operate for a predetermined time when it is desired to initiate the operation of the burner mechanism. The fluid fuel is delivered to'the combustion chamber of the furnace or heater either in the form of a combustible gas or in a spray of atomized liquid fuel mixed with sufficient air to form a combustible mixture and this combustible mixture is ignited by a jump spark or hot wire ignition device caused to operate when the combustible mixture is passed thereover.

Heretofore it has been customary in, the hot wireignition to provide a circular coil of fine resistance wire which becomes heated to incandescence by the passage of an electrical current therethrough and discharge the combustible mixture therethrough. The combustible mix.- ture passing over the incandescent coils ignites and after ignition continues to burn. In this type of ignition device the resistance wire remains permanently in close proximity to the flame of the burning fuel and is subjected to the excessive heat of the flame as long as the burner is operating.

It is an object of this invention to provide an electrically operated ignition of the hot wire type of substantial construction which will present a concentrated mass of metal heated to incandescence at the initial operation of the burner mechanism in the path of the combustible mix-, ture for a sufficient time to cause ignition and.

thereafter automatically withdraw the ignition device from the excessive heat of combustion and the deteriorating efiects thereof. 1

With these and other objects in view, referenc is made to the accompanying sheets of drawings which illustrate preferred forms of this invention, with the understanding that minor detail changes may be made therein without departing from the scope thereof.

Figure 1 is a view partly in side elevation and partly in section illustrating an embodiment of this invention to a commercial fluid fuel burner mechanism of the forced draft type.

Figure 2 is a view in end elevation of Figure 1.

Figures 3 and 4 are enlarged detail views in top plan and side elevation, respectively, of the ignition device shown applied in Figures 1 and 2.

Figures 5 and 6 are views similar to Figures 3 and 4 of a modified form of ignition device of the same type.

Figure 7 is a view partly in side elevation and partly in section of a rotary type of fluid fuel burner installed in the combustion chamber of a domestic furnace illustrating this improved 'ignition device as applied to this type of burner mechanism.

In the embodiment of this invention as illustrated in Figures 1 to 4 inclusive, the fluid fuel is delivered through a pipe 1 concentrically mounted within the draft pipe 2 of a forced draft burner mechanism, in which the fuel is delivered in a spray from the discharge nozzle 3 to mix with the air forced through the draft pipe 2 to which it is customary to imparta whirling motion by passing through an air spiral 4 customarily mounted upon the nozzle 3 or fuel pipe 1.

The resistance element of the ignition device is preferably formed from a flat strip 5 of nickelchromium alloy which readily becomes heated upon the passage of an electric current therethrough and which is centrally divided by a slot 6 extending to a point adjacent the forward free end and the bifurcated ends each mounted upon the ends of strips of bi-metallic metal 7 which in turn are clamped or otherwise secured to the terminals 8 of the ignition circuit, which terminals are shown mounted upon a block 9 of insulatingmaterial carried upon the fuel pipe 1.

It is customary to employ an ignition circuit so controlled as to be energized for a predetermined time whenever the burner mechanism operated, such as disclosed in this applicant's prior co-pending application Serial No. 331,542, filed January 10, 1929, and, inasmuch as this invention may be used in connection with any ignition circuit, it is not thought necessary to further describe the ignition circuit.

The bifurcated strip 5 of the resistance element is preferably tapered toward its free end, as shown in Figure 5, to increase the resistance offered to the passage of the current through this part and thereby bring the tapered end to incandescence while the wider portions secured to the bi-metallic strips '7, offering less resistance, do not become heated so rapidly. It is preferable to coil the reduced free end of the strip 5, as shownin Figures 1 and 4, whereby a mass 10 of incandescent metal is presented in the path of the combustible mixture when the ignition device is operated.

The strip 5 and bi-metallic strips 7 are so supported upon the block 9 that when the ignition device is inoperative the coiled end 10 will normally be out of the path of the combustible mixture issuing from the burner nozzle and out of the direct path of the flame from the nozzle when the burner is operating, as shown in full lines in Figure 1.

Commercial electrically operated fluid fuel burner mechanisms are customarily provided with controls which when the circuit to the control is closed, closes the ignition circuit and operates the motor to discharge the combustible gas or mixture from the burner nozzle, such as disclosed in the said prior copending application of this applicant. The bi-metallic strips 7 are of such formation that when the ignition circuit is closed, the current passing through these strips 7 and bifurcated strip of nickel-chromium alloy, the heat generated thereby willcause the strips 7 to deform and bend toward the fuel pipe 1 causing the coiled end 10 approaching incandescence to move toward the spray issuing from the burner nozzle and as it becomes incandescent will be brought and held in the path of the combustible spray, as shown in dotted lines, Figure 1, a sufficient time to ignite the combustible mixture.

It is customary for the control to open the ignition circuit'after a predetermined time found to be sufficient for the ignition device under normal conditions to ignite the fuel. In the form shown in Figures 1 and 2, as soon as the ignition circuit is broken the current ceases to pass through the bi-metallic strip 7 and ignites strip 5 and these strips will begin to cool and in this type of burner the atmospheric air forced through the draft pipe in passing over the strip 7 will hasten the cooling thereof so that after a short period of normal functioning of the burner the igniter strip will assume its normal cold position with the coiled end 10 out of the flame, as shown in full lines in Figure 1.

Figures 5 and 6 illustrate an igniter or ignition element formed of a strip of bi-metallic metal in which the nickel-chromium alloy is one element with a metal of a different coefficient of expansion as the other and in which the strip 11 of nickel-chromium extends the entire length and is slotted as'sh'own, with the other metal 12 extending from the bifurcated ends clamped to the terminals to a sufficient distance to allow the ignition current when passing therethrough to bend the free end of the igniter into operative position.

To the successful operating life of a hot wire igniter for a rotary fluid fuel burner, it is just as desirable to remove the igniter from the excessive heat of the burning fuel as in the forced draft type. Figure 7 illustrates an embodiment of this invention to a commercial rotary type of burner in which a casing 13 is centrally mounted in the bottom of the combustion chamber 14 of a domestic furnace or heater, the interior of the bottom and sidewalls of which are customarily lined with refractory material 15. In this type burner mechanism the operation of the motor delivers the fluid fuel to a rapidly rotating member which atomizes the fluid by centrifugal action causing the combustible mixture to flow outward along or above the surface of the refractory bottom 15 of the combustion chamber.

To apply this improved igniter an aperture 16 is provided through the bottom of the combustion cha ber adjacent the wall lining, as shown. A bloc 17 of insulating material is secured upon the under side of. the bottom of the combustion chamber at one side of the aperture 16 to which is clamped the ignition circuit terminals 8 and strips 7 of bi-metallic metal. The igniter is formed preferably of a strip 5 of nickel-chromium alloy of the shape shown in Figures 3 or 5, as desired, and is preferably secured to the ends of the bi-metallic strip '7 so as to normally extend at right angles thereto. The bi-metallic strips 7 are so formed that normally, when the ignition circuit is open, they will support the igniter wholly within the aperture 16, as shown in dotted lines, Figure '7, and where the ignition circuit is closed the current passing through the bi-metallic strip 7 and igniter 5, the heat generated by the resistance of these parts will cause the bimetallic strip to deform causing the free ends of the strips 7 to move upwardly so that the right angularly extending igniter strip 5 will be brought to the position shown in full lines in Figure '7 with the incandescent end extending above the top of the bottom lining 15 of the combustion chamber and in the path of the combustible mixture delivered from the burner-mechanism.

As in the first form, the passage of the current of the ignition circuit through the igniter automatically brings the incandescent igniter into the path of the combustible mixture and after a predetermined time automatically withdraws it when the ignition circuit is broken. A hot wire igniter mounted in the manner described, upon the closing of the ignition circuit is automatically brought into the path of the combustible mixture and after the normal ignition thereof is then automatically withdrawn from the excessive heat generated by the burning fuel. The results of this automatic movement are obvious. The excessive heat from burning oil, gas or other fluid fuels upon metal is always deteriorating, particularly if the fuel contains sulphur, which is usually the case, and metal is brought into direct contact therewith.

What I claim is:

1. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a'member of electric resistance material adapted to become incandescent upon the passage of the current of the-ignition circuit therethrough, and means actuated by the closing of the ignition circuit to bring the incandescent ignition member into the path of the fuel, including a bi-metallic member interposed in the ignition circuit adjacent the igniter'adapted to be deformed upon passage of the current therethrough to move the igniter into operative position.

2. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a member of electric resistance material adapted to become incandescent upon the passage of the current of the ignition circuit therethrough, and means controlled by the ignition circuit for moving the ignition member into and out of the path of the fuel from the burner mechanism, including a bi-metallic member interposed in the ignition circuit adjacent the igniter adapted to be deformed upon passage of the current therethrough to move the igniter into operative position.

3. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a member of electric resistance material adapted to become incandescent upon the passage of the current of the ignition circuit therethrough, and means controlled by the ignition circuit for moving the ignition member into and out of the path of the fuel from the burner mechanism, including a strip of bi-metallic metal interposed in the ignition circuit adapted to be deformed upon passage of the current therethrough to move the igniter into operative position.

4. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a member of electric resistance material adapted to become incandescent upon the passage of the current of the ignition circuit therethrough, and means controlled by the ignition circuit for moving the ignition member into and out of the path of the fuel from the burner mechanism, including a strip of bi-metallic metal interposed in the ignition circuit, adjacent the resistance member adapted upon the passage of the current therethrough to move the igniter into operative position.

5. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a member of electric resistance material adapted to become incandescent upon the passage of the current of the ignition circuit therethrough, and means controlled by the ignition circuit for moving the ignition member into and out of the path of the fuel from the burner mechanism, including a strip of bi-metallic metal interposed in the ignition circuit adjacent the resistance member and forming a part of the resistance member adapted upon the passage of the current therethrough to move the igniter into operative position.

6. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a member of electric resistance material adapted to become incandescent upon the passage of the current of the ignition circuit therethrough, including a bifurcated strip of electrical resistance material with the free end of each leg connected in the ignition circuit and the opposite end coiled upon itself to prevent a mass of incandescent metal when the current uf the ignition circuit passes therethrough, and

means controlled by the ignition circuit for moving the ignition member into and. out of the path of the fuel from the burner mechanism including a strip of lei-metallic metal interposed in the ignition circuit adjacent the resistance member adapted upon the passage of the current therethrough to deform and move the igniter into operative position.

7. A fluid fuel burner ignition device for electrically operated and controlled burner mechanisms including an ignition circuit and a control for energizing such circuit to initiate combustion, a member of electric resistance material adapted to become incandescent upon the passage of the current of the ignition circuit therethrough, including a bifurcated strip of electrical resistance material with the free end of each leg connected in the ignition circuit and the opposite end coiled upon itself to present a mass of incandescent metal when the current of the ignition circuit passes therethrough, and means controlled by the ignition circuit for moving the ignition member into and out of the path of the fuel from the burner mechanism, including securing to each leg of the resistance from its connection in the ignition circuit a strip of metal of a different coefficient of expansion.

8. An electrically operated ignition device for fluid fuel burners including a member of electric resistance material adapted to become incandescent upon the passage of the required current therethrough and a bimetallic member of proper electric resistance material arranged therewith whereby upon passage of the required current therethrough the bimetallic member moves said incandescent member into the proper location for igniting said burner and upon discontinuing of said current it moves away from said location into one wherein it will be out of the path of said burner flame.

9. An electrically operated ignition device fo fluid fuel burners including a bimetallic member of electric resistance material a portion of which is adapted to become incandescent upon passage of the required current for the purpose of igniting the fuel and other portions of which become sufficiently heated upon passage of the same current to move the incandescent portion into the proper location to ignite the fuel and upon discontinuation of said current returns same to its original position outside the path of the flame.

HA E. McCABE.

CERTIFICATE OF CORRECTION.

latent No. l, 926, 394.

September 12 1933.

IRA E. McCABE,

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 52, claim 6, for "prevent" read present; and that 'the said Letters Patent should be read with this correction therein that the same may conform th the record of the case in the Patent Ofiice.

Signed and sealed this 9th day of January, A. D. 19341.

(Seal) i M. Hopkins Acting Commission of Patents.

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