Gas Burner

Abstract

A gas burner including a mounting plate and a burner cap is provided with a baffle for distributing the flow of gas from an inlet in the plate to burner ports in the cap for preventing uneven flame distribution and flame extinction. The baffle includes a central opening surrounded by an inclined wall in which are formed a group of uniformly spaced trapezoidal slots.

Description

This invention relates to gas burner devices such as are used in home cooking ranges and recreational vehicle ranges. More particularly, this invention relates to gas distribution apparatus or baffles which can be used to distribute gas uniformly into a gas burner chamber for uniform distribution to the gas burner ports.

Home gas ranges and recreational vehicle (RV) gas ranges have one or more gas burners capable of providing a flame for heating a cooking utensil. The gas burner generally comprises an enclosed chamber having a gas inlet and a gas outlet. The outlet generally comprises one or more apertures called burner ports. A mixture of a combustible gas and primary air enters the burner chamber from an inlet tube generally called a mixing tube and the mixture of gases is ignited to provide flame at the burner ports. The air around the burner ports, called secondary air, supplements the primary air to provide enough oxygen for combustion at the burner ports.

To evenly heat a cooking utensil, it is necessary to provide gas uniformly to each burner port. At moderate gas flow rates uniform gas distribution is not a significant problem. However, at low and high rates, the gas flow characteristics through a burner cause two substantial problems: (1) flame extinction, and (2) non-uniform gas distribution to burner ports. These problems are aggravated in a burner having an off-center gas inlet. The burner of the present invention contains a baffle or gas distributing means which can be easily inserted into a gas burner during manufacture for distributing gas uniformly to the burner ports to overcome the difficulties of flame extinction and non-uniform gas flow.

The baffle of the present invention is most useful in a burner which has an off-center gas inlet. Burners having a center hole for supplying secondary air are sometimes adapted to receive a top burner thermostat and thus have off-center gas inlets. As a result of the off-center inlet, the burner ports closest to the gas inlet may receive more gas than those farther away from the gas inlet. The resulting flame distribution is not uniform.

One attempt to solve this gas distribution problem has been to provide additional gas burner structure such as a post or protrusion for directing the gas in the desired direction. This approach is inappropriate in some types of burner due to added expense in manufacture of the burner and because of lack of uniform distribution over a wide range of flow rates. Another approach has been to use a baffle having only a central aperture in an attempt to direct the gas centrally upward as would result from a central gas inlet. Such a baffle does provide uniform gas distribution, but presents excessive restriction to flow at low flow rates.

Another proposal has been a baffle which provides different sized holes positioned at different locations around the baffle. Smaller slots are provided at areas of higher gas pressure in an attempt to pass an equal amount of gas through the baffle at each slot. These baffles, however, are prohibitively expensive to manufacture and must be specially designed for each particular burner. In addition, this type of baffle must be installed in a specific orientation in the burner, and this adds to the expense of manufacture.

A primary object of the present invention is to provide a gas burner having a uniform gas flow through the burner ports for the entire operating range of gas burner flow rates.

Further objects of the present invention are to provide a gas burner having the following characteristics: uniform distribution of gas to the burner ports even when the gas burner inlet is off-center; upward flame angle rather than a horizontal or downward angled flame; and a gas burner baffle having ports capable of distributing gas uniformly at all flow rates. other objects are to provide an improved baffle for gas burners which can be manufactured economically of inexpensive material and can be easily and economically mounted in a gas burner.

In brief, the above and other objects and advantages of the present invention are achieved through the provision of a gas burner including a mounting plate, a burner cap, and a baffle of novel configuration. The mounting plate includes a gas inlet, which may be located in an off-center position. The burner cap includes a group of burner ports, and a burner chamber, defined between the plate and cap, communicates with the inlet and the ports.

In accordance with the invention the baffle includes a central opening surrounding a group of additional openings. The baffle is symmetrical about its center and is formed from thin sheet material so that the expense of making the baffle and of positioning it in the burner is minimized. An inclined wall extends from adjacent the outer edge of the baffle and surrounds the central opening. The additional openings are in the form of trapezoidal slots in the inclined wall.

The invention together with the above and other objects and advantages may be best understood from consideration of the following detailed description of an illustrative embodiment of the invention shown in the accompanying drawings, wherein:

FIG. 1 is a side elevational view of a gas burner constructed in accordance with the present invention, illustrating the burner in conjunction with a mixer tube and mounting bracket;

FIG. 2 is an enlarged cross sectional view of the gas burner;

FIG. 3 is an enlarged plan view of the baffle of the gas burner; and

FIG. 4 is a cross sectional view, on a reduced scale, of the baffle taken along line 4--4 of FIG. 3.

Referring now to the drawings, and initially to FIGS. 1 and 2, there is illustrated a gas burner, generally designated by the reference numeral 10 and embodying the features of the present invention. The burner is supplied with fuel by a gas mixing tube 12 and is mounted in a range (not shown) by a support bracket or clamp 14. In general, burner 10 includes a burner cap 16 mounted on a mounting plate 18 to provide an enclosed burner chamber 20. The cap 16 has a plurality of gas burner ports 22 which serve as a gas outlet for gas to be ignited. In accordance with an important feature of the present invention, a baffle 24 is supported within the chamber 20 between a gas inlet opening 26 in the plate 18 and the gas outlet ports 22 in order to prevent uneven flame distribution and flame extinction at ports 22. The ports 22 are uniformly arranged about the burner chamber 20.

Referring more particularly to FIG. 1, gas entering mixing tube 12 from a suitable source (not shown) passes through a venturi portion 28 of the mixing tube and primary air enters a primary air inlet 30 and mixes with the gas. The combustible mixture of gas and primary air enters the chamber 20 through the mounting plate inlet 26. The mixture then passes through the baffle 24 and is expelled through the gas discharge ports 22. Secondary air is entrained in the mixture at this region, and after ignition a cooking flame exists in the vicinity of ports 22.

With reference more particularly to the structure of the burner 10 as best illustrated in FIG. 2, the mounting plate 18 comprises a one-piece stamped structure having a central circular cylindrical wall 32 and an eccentric collar 34 defining the gas inlet 26 and serving to interconnect the plate 18 and the mixing tube 12. An outer circular rim 36 of the plate 18 facilitates joining of the plate with the burner cap 16.

Cap 16 includes an outer wall 38 terminating at its lower edge in a flange portion 40 crimped to the rim 36 of plate 18 an inner wall 42 of the cap 16 includes a circular cylindrical portion 44 interfitting with wall 32 of plate 18 to define a central vertical passageway 46 through burner 10. As will be understood by those skilled in the art, the passge 46 may provide a passage for secondary air to reach the top of the burner, and may also accommodate a top burner thermostat if desired. A pair of ledges 48 and 50 define a flame retention region 52 surrounding ports 22 at the outer and upper rim portion of the burner.

In the use of known gas burners problems have been encountered in obtaining flame retention and uniformity at various gas flow rates. This problem has been particularly acute with burners having an eccentric inlet. At high rates of gas flow, the differential in pressure existing around the burner port area results in uneven flame due to different angles of gas emission from ports at different locations. To overcome this problem, baffles or flow restrictors have been used. However, with known devices the restriction to flow is too great and flame extinction occurs at low rates of flow.

In accordance with the present invention, the baffle 24 is provided to overcome these problems. At high flow rates the baffle 24 provides even flame distribution around the full extent of the ports 22. At low rates of flow the baffle 24 offers only small resistance to flow and the problem of undesirable flame extinction is minimized.

Proceeding now to a description of the baffle 24, the baffle 24 is preferably formed as by stamping from a thin sheet of material so that the expense of making the baffle is minimized. In addition, the baffle is symmetrical about its center, and since no keying or positioning of the baffle in the burner 10 is necessary, the expense of fabricating the burner is reduced. In general, the baffle 24 has a central aperture 54 surrounded by a plurality of additional openings 56 placed symmetrically around the central opening 54. As best shown in FIG. 3, the central opening 54 has an area substantially larger than the area of any one slot 56. The gas inlet 26 is not aligned with central opening 54.

More specifically, the baffle 24 includes a circular outer rim portion 58 permitting the baffle to be clamped in position between the burner cap 16 and the plate 18 when the burner is assembled. An inclined wall 60 extends inwardly and upwardly from the rim 58, and the inner edge of wall 60 defines the central opening 54 which is preferably circular. Each outer opening 56 is located in the inclined wall 60 and varies in width from a maximum width adjacent the opening 54 to a minimum width adjacent the rim 58. Preferably the openings 56 are trapezoidal and include parallel top and bottom edges.

In the use of the baffle 24, all of the gas flowing into the burner 10 passes through the openings 54 and 56 of the baffle before reaching the outlet ports 22. At relatively high flow rates, a substantial portion of the gas tends to be directed by the inclined wall 60 toward and through the central opening 54 resulting in uniform distribution of gas to the ports 22. If only the opening 54 were provided, performance at high flow rates would be satisfactory, but at low flow rates excessive restriction would be present. The additional openings 56 reduce the restriction at low flow rates, but at high rates do not permit a substantial portion of the gas to bypass the central opening 54. It is believed that this results from the slope of the wall 60, preferably between 15.degree. and 65.degree. from horizontal, and from the varying width of the outer openings 56.

At low flow rates, the influence of the inlined wall 60 upon the direction of flow through the baffle 24 is reduced, and a substantial portion of the flow passes through the outer openings 56. The total area of the openings 54 and 56 is large enough so that the restriction to flow is small and the pressure drop across the baffle 24 is also small. Thus, ample gas reaches the ports 22 reliably to support combustion, and flame extinction is avoided.

Although the present invention has been described with reference to details of the illustrated embodiment, such details are not intended to limit the scope of the invention as defined in the following claims.

Claims

What is claimed and desired to be secured by Letters Patent of the United States is:

1. In a gas burner, a burner chamber including uniformly arranged outlet means about the chamber, and a gas inlet, the improvement comprising baffle means mounted within said burner chamber and positioned between said gas inlet and said burner ports, said baffle means being inclined upwardly and inwardly toward a central opening for the passage of gas therethrough and having a plurality of uniformly spaced baffle slots of uniform configuration surrounding said central opening and extending toward said opening, said gas inlet being non-aligned with said central opening and said central opening having an area substantially larger than the area of any one baffle slot.

2. The combination of claim 1 wherein the baffle means comprises a formed sheet of thin material.

3. The combination of claim 2, further comprising a rim extending radially from the base of the inclined annular wall for seating the baffle in position within the burner chamber.

4. The combination of claim 3 wherein the baffle slots increase in width toward the center of the baffle.

5. The combination of claim 4 wherein the baffle slots are trapezoidally shaped.

6. The combination of claim 5 wherein the parallel sides of the trapezoidally shaped slots are substantially parallel to said rim and wherein the parallel side closer to said rim is shorter than the parallel side closer to said central opening.

7. A gas burner comprising in combination

a mounting plate having a gas inlet therein and having a generally circular outer plate edge;

a cap having a generally circular outer cap edge attached to said plate edge and having uniformly arranged outlet means therein;

said plate and cap being constructed and arranged to enclose a burner chamber therebetween communicating with said inlet and said burner ports;

a baffle supported between said cap and plate for distributing the flow of gas from said gas inlet through said chamber to said burner ports;

said baffle being upwardly and inwardly inclined and symmetrical about its center and including a central opening for the passage of gas therethrough and a plurality of of uniform configuration surrounding said central opening and extending toward said opening, said central opening having an area substantially greater than the area of any one additional opening, and said gas inlet being non-aligned with said central opening.

8. The gas burner of claim 7, said inlet being off-center of said mounting plate.

9. The gas burner of claim 7, said baffle including a generally circular outer edge sandwiched between said plate edge and said cap edge.

10. The gas burner of claim 7, said central opening being defined by the inner edge of said inclined portion.

11. The gas burner of claim 10, each slot being of varying width and having its widest portion closest to the center of said baffle.