US2229717A - Igniter for oil burners - Google Patents

Description

Jan. 28, 1941. K. P. BRACE ET A1. 2,229,717

IGNITER FOR OIL BURNERS Filed March 14, 1938 Patented Jan. 28, 1941 IGNITER FOR OIL BURNERS Kemper P. Brace and Franklin H. Wells, South Bend, Ind., assignors to International Engineering Corporation, AChicago, Ill., a corporation of Illinois Application March 14, 1938, Serial No. 195,770

7 Claims.

This invention relates to oil burners and similar devices, and more particularly to ignition means therefor.

An object of the invention is to provide a hotwire ignition device which will vaporize and ignite the fuel with a minimum input of electrical energy. Another object is to so locate the igniter that after ignition is effected the igniter itself will be entirely outside the zone of burning of lo the fuel and consequently will not be subjected to extremely high temperatures, and so that the electrical connections thereto will not be subject to high temperatures, and preferably also so that the igniter is shielded from the direct fiow of air for combustion. Another and very important object is to provide a very effective form of hot-wire igniter using a relatively small current and which quickly reaches a high temperature when the ignition current is passed therethrough.

The igniter, in the form illustratedin the drawing, comprises a resistance wire wound to form a relatively long small-diameter inner coil encircled by a relatively short large-diameter outer coil, and is arranged in the rear end of an air passage approximately at the center of a porous refractory member to which the fuel is fed, and through which the fuel seeps transversely of a series of such air passages.

'I'hus initial ignition takes place after the oil has traveled far enough to give time for the igniter to heat up and yet far enough from the bottom of the porous member so that no fuel is lost by dripping from its lower surface before combustion starts. Moreover ignition takes place Well behind the zone in which combustion takes place after the burner gets started. Preferably a shield is placed just behind the igniter, to insure turbulence of the fuel-air mixture dur- 0 ing ignition, and to shield the igniter from the direct iiow of air thereafter.

The above and other objects and features of the invention will be apparent from the following description of the illustrative embodiment shown in the accompanying drawing, in which:

Figure 1 is a central vertical section longitudinally through the burner as it appears when mounted in a furnace; and

Figure 2 is a side elevation, .on a larger scale,

of theigniter proper.

Tests of hot-wire igniters, for oil burners and the like, have shown that with a given length and size of wire and with a given current input the manner in which the wire is coiled or other- Q# Wise arranged has a very great effect on its temone of the upper passages I4.

perature, and consequently on its effectiveness in igniting the oil. In a single coil the most effective arrangement is in a coil of substantial diameter whose length is approximately equal to its diameter. 5

We provide such a coil I0, of suitable resistance wire; we nd, however, that we can greatly increase its effectiveness by arranging it to encircle a relatively long small-diameter inner coil I2. Preferably the two coils are integral, being 10 wound from the same resistance wire with the outer coil arranged centrally of the inner coil, as shown in Figure 2. Since the inner coil is radiating to a hot outer coil, and receives heat from the outer coil, it as well as the outer coil l5 becomes very hot and is very effective.

The igniter is arranged at the rear end of one of a plurality of air passages I4 through and paralleling the axis of a porous refractory member I6, the igniter being approximately at the 20 center of its rear face. The illustrated porous member I6 is formed with a convex front face and a substantially plane rear face, with the passages I4 paralleling its axis.

Fue1 is supplied to the upper part .of member 25 I6 by means such as a spout I8 having a removable cleanout plug 20 and discharging into The spout I8 receives oil fuel through a conduit 22, fed by gravity or by a suitable pump, under the control of 30 a fuel valve (not shown) controlled by the usual room thermostat (not shown). The fuel seeps downwardly through the porous structure of member I6, transversely of the passages I4.

The member I6 is secured, by means such as 35 a holding ring 24, in the front end of a generallycylindrical open-ended carrier 26. The carrier 26 is flanged outwardly at its rear end and secured (by suitable fastenings) to the rear end of acasing 28 formed to be seated in the fuel 40 door or other opening in the side wall of a furnace, a suitable refractory panel 30 closing the remainder of the opening. The front end of the casing is shown conical, so that in a general way it parallels the front face of the member I6. 45 The whole burner is mounted to discharge into the furnace at a slight angle downwardly.

Excess fuel, in the case of ignition failure for example, may drain back through a conduit 32 to-operate a suitable iioat-type safety shut-olf 50 switch (not shown).

If desired, the conduit 32 may also be utilized as a housing for an ignition wire 34 connected to a binding screw 36 passing through an insulating bushing 38 to a heavy wire support 40, 55

The support 4l) and a similar support 42 grounded on the carrier 213 are welded or otherwise secured to the ends of the resistance Wire making up the coils ill-l2, and support the igniter as Well as supply current thereto When the room thermostat calls for heat.

A shield 44, preferably of mica or other transparent refractory material, may be mounted on the ends of the resistance Wire, a short distance behind the rear face of the member i6.

The flow of air through the burner, under the influence of the suction from the chimney of the furnace, is controlled by a glass or other transparent heini-spherical closure 4G having a central stem 48 adjustably threaded into a nut 50 secured to a diametrically-arranged vertical bar 52 Welded at its ends to the flanged rear end of carrier 26.

It will be seen that, when the igniter is first energized, the flow of air through the burner is slow as compared to the ilo-W after the burner is in operation. When the fuel `seeps down far enough to reach the passage containing the igniter, the heat therefrom vaporiaes and then ignites a small part of the fuel. rlhe air ilow through the burner almost immediately reaches such a velocity that the zone of combustion is just in front of the member It and in the front ends of the passages le, leaving the igniter lill2 and its connections it-i2 entirely behind that zone. rilhe shield riti, if used, insures turbulence of the fuel-air mixture about the coils Il'l-lt during ignition, and also protects the igniter from the direct flow of air after ignition When the flow becomes more rapid.

Since the closure it and the shield i4 are transparent, the operation of the igniter and of the burner can conveniently be observed at any time.-

Except for our improvements in the construction and arrangement of the igniter, the illustrated burner is covered by applications Nos. 145,706 and 195,769, filed respectively June 1, 1937, and March 14, 1938, by Kemper P. Brace, and is not claimed herein.

While one illustrative embodiment has been described in detail, it is not our intention to limit the scope of the invention to that particular embodiment, or otherwise than by the terms of the appended claims.

We claim:

1. A11 oil burner comprising an open-ended casing adapted to be mounted in an opening in the side Wall of a furnace, a porous refractory member supported at the front end of the casing and which is formed with air passages therethrough generally paralleling the axis of the casing, means at the rear end of the casing for varying the air flow through the casing, a hot- Wire igniter supported in the rear end of one of said air passages approximately in the central plane of said member and which includes a rei sistance Wire formed to provide a small diameter inner resistance coil encircled by a large diameter outer resistance coil, and means for supplying liquid fuel to said member to seep therethrough transversely of said passages.

2. An oil `burner comprising an open-ended casing adapted to be mounted in an opening in the side Wall of a furnace, a porous refractory member supported at the front end of the casing and Which is formed with -air passages therethrough generally paralleling the axis of the casing, means at the rear end of the casing for varying the air flow through the casing, a hot-Wire igniter supported in the rear end of one of said air passages which includes a resistance Wire formed to provide a small diameter inner resistance coil encircled by a large diameter outer resistance coil, a shield mounted behind said igniter and spaced from the rear side of said member, and means for supplying liquid fuel to said member to seep therethrough transversely of said passages.

3. An oil burner comprising an open-ended casing adapted to be mounted in an opening in the side wall of a furnace, a porous refractory member supported at the front end of the casing and Which is formed With air passages therethrough generally paralleling the axis of the casing, means at the rear end of the casing for varying the air flow through the casing, a hot-Wire igniter supported in the rear end of one of said air passages, a shield mounted behind said igniter and spaced from the rear side of said member, and means for supplying liquid fuel to said member to seep therethrough transversely of said passages.

4. An oil burner comprising a porous refractory member having a convex front face and a generally plane rear face and formed with air passages therethrough, means to supply liquid fuel to said member to seep through the structure thereof transversely of said air pasages, a hot wire igniter in the rear end of one of the air passages and which consists of a resistance Wire formed to provide a relatively small diameter inner coil encircled by a relatively large diameter outer coil, and a shield spaced a short distance behind the igniter opposite the central portion of the rear face of said member.

5. An oil burner comprising a porous refractory member having a convex front face and a generally plane rear face and formed with air passages therethrough, means to supply liquid fuel to said member to seep through the structure thereof transversely of said air passages, a hot Wire igniter in the rear end of one of the air passages, and a shield spaced a short distance behind the igniter opposite the central portion of the rear face of said member.

6. An oil burner comprising a porous refractory member formed with air passages therethrough, means to supply liquid fuel to said member to seep through the structure thereof transversely of said air passages, a hot Wire igniter in the rear end of one of the air passages and which consists of a resistance Wire formed to provide a relatively small diameter inner coil encircled by a relatively large diameter outer coil.

7. An oil burner comprising a porous refractory member formed with air passages therethrough, means to supply liquid fuel to said member to seep through the structure thereof transversely of said air passages, a hot Wire igniter in the rear end of one of the air passages and which consists of a resistance Wire formed to provide a relatively small diameter inner coil encircled by a relatively large diameter outer coil, and a shield spaced a short distance behind the igniter opposite the central portion of the rear face of said member.

KEMPER P. BRACE. FRANKLIN H. WELLS.

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