US3470864A - Combustion chamber - Google Patents

Description

06L 7, T E EMMERT COMBUSTION CHAMBER Filed March 22, 1968 United States Patent ()1 lice 3,470,864 Patented Oct. 7, 1969 3,470,864 COMBUSTION CHAMBER Thomas E. Emmert, Lebanon, Ind., assignor to Stewart- Warner Corporation, Chicago, 11]., a corporation of Virginia Filed Mar. 22, 1968, Ser. No. 715,300

. Int. Cl. F24h 3/02; F23] 9/04; F24c 3/00 U.S. Cl. 126-110 2 Claims ABSTRACT OF THE DISCLOSURE The following specification describes a compact type oil furnace using a cylindrical combustion chamber in which an axially directed primary flame and combustion air are distributed radially and circumferentially through a series of circumferentially and axially spaced holes in the cylindrical combustion chamber wall.

I DESCRIPTION OF THE INVENTION Field of the invention The present inventionrelates in general to combustion chambers for oil furnaces and the like and more particularly to a combustion chamber for avoiding local hot spots and flame noises in a compact type of oil furnace.

Background of the invention In compact type oil furnaces the primary combustion air is usually provided along an axis perpendicular to its subsequent general flow through the exchanger and since the walls diverting the flow are quite close to the primary flame localized high heat exchanger surface temperatures result and flame noises are also created. Localized high heating causes'temperatures at adjacent heat exchanger surfaces in the range'of 900 F. and above. At these temperatures ordinary mild or cold rolled sheet steel loses a considerable portion of its strength and fails easily. It has therefore been necessary to fabricate heat exchanger surfaces exposed to direct flame from either stainless steel or other high heat resistant materials, which add substantially to the cost. i

SUMMARY OF INVENTION The present invention solves the above problems provide a combustion chamber for reducing overheating of adjacent metal surfaces.

It is another object of the present invention to provide an improved combustion chamber for a compact type oil furnace.

It is still a further object of the present invention to provide improved apparatus for mounting a cylindrical combustion chamber in the heat exchanger of a compact type oil furnace.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view illustrating a typical compact type oil burner in which the combustion chamber of the present invention is used; and

FIG. 2 is an isometric view illustrating the combustion chamber, together with the mounting brackets therefor and the end portion of the flame tube.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawings a furnace assembly is indicated therein by the reference character 10. The furnace assembly 10 comprises a sheet metal housing 12 having an opening 14 at one end through which ventilating air to be heated is drawn by a blower 16.

The ventilating air is drawn through a filter 18 adjacent opening 14 and follows a path indicated by arrows 20 between longitudinally extending side walls 22 of housing 12. The walls 22 have a heat insulating lining 24 and located intermediate walls 22 is a heat exchanger 26 defined in part by side walls 28 parallel to walls 26 and spaced inwardly from walls 24 to define a passageway 29 for the ventilating air.

The ventilating air after it is warmed by heated combustion air passing through the heat exchanger 26 exits through an opening 30 at the end of housing 12 opposite opening 14 for passage through appropriate conduits or otherwise into the space to be heated. It will be noted that the ventilating air follows a generally longitudinal path from one end of the furnace assembly 10 to the other end and since this path is relatively short to conserve space, it is necessary to mount a burner assembly 32 at the side of the furnace assembly 10.

The burner assembly 32 comprises a conventional blower 34 for providing combustion air to a blast or flame tube 36. A fuel pump 38 in the burner assembly introduces fuel through a nozzle in the flame tube 36 wherein it is ignited by a pair of electrodes under control of a high voltage transformer. The various conduits and connections for supplying fuel and electricity are omitted for the sake of simplicity since the apparatus for creating the flame is of conventional construction.

The blast tube 36 is inserted through a flanged ring 40 which extends from around an aperture in one of the side walls 22 of the furnace to an aperture in a bulkhead plate 42 located at the end of the heat exchanger closest to the blower 16 or source of ventilating air. The bulkhead plate 42 is secured to one of the side walls 28 of the exchanger opposite the burner assembly 32. The flanged ring 40 provides a passageway for the flame tube to be inserted in the heat exchanger 26 while avoiding communication between the ventilating air and combustion air. A boss 44 on the bulkhead plate 42 projects from the plate 42 through the passageway 29 and the adjacent wall 22. The boss 44 has an axial opening to provide a port for viewing the flame in the exchanger. A cover, not shown, is usually provided over the aperture in boss 44 and its position may be conventionally controlled for admitting some secondary combustion air, if necessary.

The end of blast tube 36 is axially aligned with the axis of a generally cylindrical combustion chamber 46 formed of an appropriate ceramic material and a cone 47 on the end of blast tube nests in an opening 48 of about 3.5" diameter formed in an end wall 50 of the chamber. The opposite end of the chamber is closed by an end wall and the chamber has an overall length of about 13" with the cylindrical wall 52 of the chamber having an inside diameter of about 9".

A plurality of circumferentially and axially spaced apertures or passageways 54 are provided in the cylindrical wall 52 so that the axially directed flame from the blast tube 36 exits from the combustion chamber in radially directed flow paths as indicated by the arrows 56. The passageways 54 are chosen and sized to provide the most even distribution of heat in the desired directions. A pair of legs 58 approximately 3" to 4" long and having flat ends are formed at opposite ends of the combustion chamber 46 and these engage against a target plate 60 forming an end wall of the heat exchanger 26 closest to the blower 16. The legs 58 prevent the chamber 46 from rotating and properly space the chamber from the target plate.

The ends of the combustion chamber 46 are supported by arcuate spring clips 62 having outwardly bent ends. The clips are formed with a radius of curvature conforming to the radius of the chamber with the clips extending over 180 so that they securely grasp the chamber. Each clip has three spaced tabs 64 welded to the inner surface thereof with one end of each tab extending beyond the adjacent clip and bent outwardly to facilitate insertion of the chamber end in the clip. The other end of each tab is welded to one of the heat exchanger side walls 28 and the bulkhead plate 42, respectively, to space the clips and the combustion chamber properly from the walls of the heat exchanger. Radially directed end tabs 65 on the clips 62 prevent axial movement of the combustion chamber 46.

Radial air flow from the combustion chamber 46 is divided by the numerous apertures 54 and proceeds both against the target plate or wall 60 and downstream through the heat exchanger due to the concentration of the large number of holes facing the target Wall and facing downstream.

It will be noted that a rather broad band of closed wall surface is provided for the chamber 46 covering about 30 on each side of an axially extending vertical plane as viewed in the drawings to properly control air flow and this vertical plane is perpendicular to a horizontal axial plane having the passageways 54 distributed on both sides thereof. Flow from the target plate also proceeds downstream through the heat exchanger past conventional baflle walls 66 for ensuring proper heat exchange between the combustion air and the ventilating air. The ventilating and combustion air paths thus proceed generally in the same direction and the combustion air exits through the conduit 68 for passage through an appropriate stack.

The apertures 54 are approximately 1" in diameter and serve to distribute the heat from the flame originating at tube 36 to the target plate 58, but do so in a manner avoiding local hot spots. Local temperatures at the target plate are therefore kept in the range of 800 P. which is in the temperature range that ordinary sheet steel maintains its strength and thereby the need to use a stainless steel target plate is avoided. Likewise, any baffle downstream of the combustion chamber is not exposed to a direct high heat of a large flame, which in previous furnaces, might require the use of a high temperature expensive metal if close to the flame, but instead the bafile can now be fabricated of ordinary sheet steel.

The foregoing constitutes a description of an improved combustion chamber whose inventive concepts are believed set forth in the accompanying claims.

What is claimed is:

1. A combustion chamber for use with afiame tube conveying combustion air in an axial direction, the improvement comprising a combustion chamber having a cylindrical wall for axial alignment with said flame tube and end walls for closing said combustion chamber with one of said end walls having an opening therein for communicating combustion air from said flame tube to said chamber, a plurality of axially and circumferentially spaced passageways in said cylindrical wall for distributing the heat delivered by said combustion air over a plurality of paths to avoid excessive heat in any one path, a pair of arcuate clips encircling end portions of said chamber over 180", and tabs on said clips for supporting said clips and chamber. 1

2. In a compact type oil furnace of the type wherein ventilating air flows along a path extending past a heat exchanger having a target plate at one end adjacent the source of ventilating air and combustion air is introduced into said heat exchanger through a flame tube having a source of fuel and electrodes for iginiting said fuel to produce a flame and arranged to direct combustion air into said heat exchanger axially of said tube and perpendicular to said path, the improvement comprising a cylindrically walled combustion chamber having closed ends with an opening in one of said closed ends for communication with the end of said flame tube to receive combustion air directed along the axis of said chamber, a plurality of passageways in each quadrant of the cylindrical wall of said chamber equally spaced in an arc of no more than on each side of an axial plane extending through the axis of said chamber and perpendicular to said target plate with said passageways equally spaced along the entire axial length of said cylindrical wall and having a diameter less than 1 /2" for directing said combustion air toward said target plate and towards other portions of said heat exchanger along radial paths distributing the heat produced by said flame to avoid temperatures greater than 800 Fahrenheit at adjacent heat exchanger surfaces, and spacing means including integrally formed legs on said chamber for spacing the cylindrical wall of said chamber from said target plate by a distance between 3" and 4".

References Cited UNITED STATES PATENTS 10/1965 Scheppers 126-144 5/1968 Martz 43l-17l X EDWARD G. FAVORS, Primary Examiner

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