US3477798A - Gas burner - Google Patents

Description

Nov. 11, 1969 l E ERICKSON 3,477,798

GAS BURNER Filed OCL. 30, 1967 58 Il l i m l M`\36 I 35 o 34 37 33 ZNVENTOR.

CLIFFORD E. ERICKSON www H15 ATTORNEY United States Patent O 3,477,798 Y GAS BURNER Clilford E. Erickson, Chicago, Ill., assignor to General Electric Company, a corporation of New York Filed Oct. 30, 1967, Ser. No. 679,048

, Int. Cl. F23q 13/02 U.S. Cl. 431-263 7 Claims ABSTRACT F THE DISCLOSURE Background of the disclosure This invention relates to gas burners and, more particularly, to an improved arrangement for igniting the gas and air mixture, which improves the performance and life of the igniter and llame sensor. Prior art burners of the type which are used to heat a stream of air flowing past the burner normally are used with an igniter and, in most cases, with a flame sensor positioned in the path of the main lame. This subjects these elements to intense heat, often in an oxidizing area of the llame. Operation of such burner arrangements causes the igniter and sensor to become oxidized and materially shortens their useful life.

A object of this invention is to provide an improved gas burner.

Another object is to provide such an improved burner whereby a portion of the gas and air mixture is diverted from the main stream to form an auxiliary llame.

A further object is to provide an improved gas burner assembly in which an igniter and flame sensor may be positioned in the reduction portion of the path of an auxiliary llame.

Summary of the invention In accordance with one aspect of this invention there is provided gas burner assembly including a mixing chamber, a venturi tube downstream of the mixing chamber and a flame spreader downstream of the venturi tube. The llame spreader is provided with a lateral opening and a projection extending out of the spreader just upstream of the opening to create a reduced pressure area outside the opening to cause part of the gas and air mixture owing through the burner to flow through the opening. An igniter is positioned to ignite the mixture by igniting the portion flowing through the opening. Also a llame sensor may be positioned to sense burning of the portion flowing through the opening.

Brief description of the drawing FIGURE l is a fragmentary side elevational view of a mechanism such as a gas clothes dryer utilizing a new and improved burner assembly in accordance with one cmbodiment of this invention.

FIGURE 2 is a fragmentary plan View of the mechanism of FIGURE 1.

FIGURE 3 is an exploded perspective view of the burner of FIGURE 1.

Description of the preferred embodiments Referring to the drawing, especially FIGURES l and 2, there is shown a gas burner assembly 10 for heating ICC a stream of air flowing past the burner. As shown, the burner 1s mounted in some mechanism such as a gas heated clothes dryer having a cabinet with a front wall 11 and a base 12. A combustion chamber 13 is mounted in the cabinet and the burner assembly 10 is positioned at the inlet to the combustion chamber so that, as air is drawn into the cabinet through some suitable opening such as that shown at 11a, it will flow past the lburner assembly 10 and through the combustion chamber 13. Thus the llame provided by the burner assembly 10 will heat this lagir as it flows past the burner into the combusti-on cham- Referring particularly to FIGURES 1 and 3, it will be seen that a burner housing 14 is formed from a pair of elements 15 and 16, each of which comprises substantially half of the burner housing. The elements 15 and 16 each has a semi-cylindrical section, 17 and 18 respectively, and a long, tapered groove of semi-circular cross-section, 19 and 20 respectively, extending axially from one end of the corresponding semi-cylindrical section. The semi-cylindrical section 17 has spaced end walls 21 and 22 and the semi-cylindrical section 18 has spaced end walls 23 and 24. The end walls 22 and 24 each has a semi-circula1 opening, such as that shown at 25, and each of the end walls 21 and 23 has a semi-circular opening such as that shown at 26. The semi-circular openings in walls 21 and 23 communicate with the small radius end of the associated tapered grooves 19 and 20. The other or large radius ends of the tapered grooves communicate with an expanded section, 27 and 28 respectively, each of which terminates in a reduced area, semi-rectangular opening such as that illustrated at 29.

Element 15 also is provided with domed portion or extension 30 which -projects axially from the expanded section 27 and extends transversely or laterally away from the direction of ilow of the main portion of the gas and primary air mixture. Each of the elements 15 and 16 is provided with a planar flange, 31 and] 32 respectively. Flange 31 extends outward from the semi-cylindrical `section 17, the tapered groove 19, the expanded section 27 and the domed extension 30; while flange 32 extends outwardly from the semi-cylindrical section 18, the tapered groove 20 and the expanded section 28.

, The burner housing is assembled by placing the elements 15 and 16 together so that the flanges 31 and 32 are in abutting relationship and then securing the flanges together by suitable means such as spot Welding or crimping the edge of one flange aroundthe other. Thereafter, if desired, the assembly may be porcelain enameled. By assembling the elements in this manner the semicylindrical sections 17 and 18 are aligned to form a mixing chamber 33; the tapered grooves 19 and 20 are aligned to form a tube 34 which is commonly called a venturi tube in the art; and the expanded sections 27 and 28 are aligned to form a laminar ilow region 35. The semi-,circular openings in end walls 22 .and 24 cooperate to form an inlet opening 36 for gas to enter the mixing chamber; the semi-circular openings in walls 21 and 23 cooperate to form an outlet 37 from the mixing chamber to the venturi tube; and the semi-rectangular openings, such as illustrated at 29, mate to form a reduced area rectangular exit port 38 from the venturi tube.

The domed extension 30 and its associated flange portions serve as a llame spreader to cause the llame emanating from the burner to be spread and flattened. To accomplish this purpose the llame spreader cooperates with the rectangular exit port. Since the exit port is generally rectangular, having its axis across the burner much longer than its other axis, the stream of' gas and air flowing from the exit port will be in a generally rectangular configuration. The llame spreader will further lla-tten and spread this to produce a large, flat, and generally rec tangular flame. Also the reduced area of the exit port, as compared to the laminar region flow will cause the velocity of the gas and air mixture to be such that, when ignited, the flame thus produced Will begin at about the mid point of the flame spreader along the longitudinal axis of the burner.

As an important aspect of this invention the domed extension is provided with a lateral opening 39 at about its mid point, and a projection 40 extending outwardly of the burner just up stream of the lateral opening. It will be understood that lateral opening means one generally tangential to the path of flow the gas and air mixture as contrasted to one generally perpendicular theret0.

Referring now in particular to FIGURE 3, it will be seen that semi-cylindrical section 17 is provided with a relatively narrow, circumferentially disposed opening 41 and section 18 is provided with a similar, but relatively wide, circumferentially disposed opening 42 which terminates at one end in a slot 43, which is wider than the opening 42. A ring like shutter 44, including a relatively narrow portion 45 and a relatively wide portion 46 may be inserted in the burner, after assembly, by passing the relatively wide portion 46 through the slot 43 and then securing it in a desired angular position within the mixing chamber 33 by some suitable means such as a thumb screw 46, which passes through the opening 41 and is engaged in a threaded opening 47 provided in the shutter. With this arrangement the shutter may be adjusted within the mixing chamber to control the amount of primary air provided for mixing with gas entering inlet 36. This captured shutter arrangement is described in more detail and claimed in applicants copending application Ser. No. 679,049, led concurrently herewith, and assigned to Genneral Electric Company, assignee of the present invention.

The flanges 31 and 32 are provided with openings 50, 51, 52 and 53 disposed so that 50 and 52 are aligned and 51 and 53 are aligned when the burner is assembled. They provide a means for mounting the burner on a suitable support such as bracket 54 in the associated machine. They also provide a suitable means for mounting burner accessory means such as an igniter 55 and llame sensor 56. In the particular assembly illustrated the igniter and sensor are mounted on a bracket 57 which, in turn, is attached to the burner housing. As an important aspect of this invention the igniter and the liame sensor are mounted so that the contacts 58 of the igniter and the feeler 59 of the ilame sensor are positioned adjacent the lateral opening 39, on the opposite side the domed extension 30 from the exit port 38.

The burner assembly is mounted in the machine with the inlet 36 in registry with the spud or orifice holder 60 of a suitable, conventional gas control valve 61, which may be connected to a conventionalsource of gas. The other end of the burner is received in the combustion chamber 13. For operation, gas is supplied to the burner conventional means. For instance, in a gas clothes dryer,

this air flow normally would be caused by the same fan which blows heated air through the clothes drying drum.

Part of the air, called the primary air, enters the burner through opening 42 and is mixed with the gas. The gas and air mixture then flows from the mixing chamber 33, through the venturi tube 34 and into the laminar ow region 35. As the mixture flows through the laminar flow region its stream tends to spread and then is compressed and given a generally rectangular cross-section as it flows from the exit port 38. The ame spreader, formed by domed extension 30 and the associated portion of flange 31, further spreads the stream of gas Aand air mixture so that, when ignited, a large, ilat and generally rectangular flame is produced.

At the same time, the other, much greater, portion of the air, called secondary air, is drawn through the combustion chamber around the burner. The lateral opening 39 and projection 40 functions as an important part of this invention. As secondary air flows up and over the projection 40 and then past the lateral opening 39 it creates a low pressure area adjacent the lateral opening. This causes a portion of the gas and air mixture flowing from the exit port 38 to be diverted for flow through the lateral opening. This diverted portion of the mixture impinges on the contacts 58 of the igniter 55 and the feeler 59 of the llame sensor 56. When the igniter is actuated it causes the diverted portion to be ignited to give an auxiliary flame. This auxiliary ame then causes ignition of the main portion of the mixture to provide a ame to heat the secondary air. The auxiliary liame continues to burn and impinge upon the contacts S8 and feeler 59. Thus the sensor, in the usual manner, may provide protection by causing the valve 61 to turn otf if the ame fails.

The spacing of the exit port 38 and lateral opening 39 forms another important aspect of this invention. The usual gas llame normally has a irst or reducing region in which it uses essentially all the available oxygen and then an oxidizing region in which it tends to cause oxidation of objects it contacts, there being excess oxygen available in the latter region beyond the oxygen required for the flame. The exit port 38 is sized to impart such velocity to the mixture that burning begins in the region in axial alignment with the lateral opening. Thus the igniter contacts and sensor feeler are in the reducing region of the auxiliary dame. This reduces corrosion of these elements. Also, since they are subjected only to the auxiliary flame, in the large volume stream of the secondary air, these elements operate at a substantially lower temperature.

As will be evident from the foregoing description, certain aspects of the invention are not limited to the particular details of construction of the example illustrated, and it is contemplated that other variations, modifications or applications will occur to those skilled in the art. It is, therefore, intended to cover such variations, modifications and applications as do not depart from the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A gas burner assembly for heating a stream of air owing past said burner assembly, including:

(a) a mixing chamber to receive gas and primary air to be mixed with the gas; (b) a venturi tube downstream of said mixing chamber; v

(c) a flame spreader downstream of said venturi tube for expanding the flame resulting from ignition of the gasand primary air mixture;

(d) said flame spreader being formed with a domed portion extending transversely away from the direction of iiow of the main vportion of the gas and primary air mixture;

(e) said flame spreader having a lateral opening in said domed portion, and a projection extending out of said spreader into the stream of air to be heated just upstream of said opening, whereby a reduced pressure area is created outside said opening to cause a portion of said gas` and primary air mixture to flow through said opening;

(t) and burner accessory means positioned outside said opening in the path of said portion of said gas and primary air mixture.

2. The invention as set forth in claim 1, where said burner accessory means includes an igniter for igniting the gas and primary air mixture by igniting said portion thereof flowing through said opening.

3. The invention as set forth in claim 1 wherein said flame spreader is preceded by a reduced area nozzle for accelerating said mixture to insure main flame ignition substantially in axial alignment with said opening.

4. The invention as set forth in claim 1 wherein said burner accessory means includes a flame sensor positioned to sense burning of said portion of said mixture flowing through said opening.

5. A gas burner assembly for heating a stream of air flowing past said burner assembly, including:

(a) a mixing chamber to receive gas and primary air to be mixed with the gas;

(b) a venturi tube downstream of said mixing charnber;

(c) an expanded area laminar How region formed downstream of said venturi tube, said laminar flow region terminating, at its downstream end, in a reduced area nozzle, said nozzle being formed with an elongated, generally rectangular configuration` to cause the stream of the gas and primary air mixture to have a predetermined shape and velocity;

(d) a ame spreader downstream of said nozzle formed to expand the flame resulting from ignition of the gas and primary air mixture;

(e) said ame spreader defining a lateral opening therein, and a projection extending out of said spreader into the stream of air to be heated just upstream of said opening, whereby a reduced pressure area is created outside said opening to cause a portion of said gas and primary air mixture to flow through said opening;

(f) and an igniter positioned outside said opening for igniting the gas and primary air mixture by igniting said portion thereof owing through said opening.

6. The invention as set forth in claim 5 wherein said flame spreader is formed with a dorned portion extending transversely away from the direction of tlow of the main portion of the gas and primary,l air mixture, said lateral opening being formed in said domed extension.

7. The invention as set forth in clairn 5 further including a arne sensor positioned to sense burning of said portion of said mixture flowing through said opening.

References Cited UNITED STATES PATENTS 2,544,930 3/1951 Malek 431-43 2,667,920 2/1954 Smith 43 1-78 2,965,166 12/1960 Alger 431--349 FREDERICK L. MATTESON, JR., Primary Examiner H. B. RAMEY, Assistant Examiner

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