Stoves and furnaces – Stoves – Cooking
Reexamination Certificate
2000-01-07
2001-06-12
Yeung, James C. (Department: 3743)
Stoves and furnaces
Stoves
Cooking
C126S04100R, C126S0390BA, C431S264000, C431S354000
Reexamination Certificate
active
06244263
ABSTRACT:
DESCRIPTION
Technical Field
The present invention relates to gas burners and barbecue grills equipped with work-top or mounting-top gas burners.
BACKGROUND OF THE INVENTION
Outdoor cooking apparatus, such as gas barbecue grills, can require design criteria different than cooking apparatus designed for indoor use. For example, during periods of non-use, barbecue grills are exposed to weather, blowing dust, debris and insects. These elements can seriously affect the performance of gas-fueled burners. Furthermore, during use, wind and precipitation can seriously affect flame performance in gas-fueled burners, as the flow of air/fuel mixture may not be sufficiently robust enough to avoid partial or total extinguishment of the flame.
Conventional gas burners for outdoor applications are designed such that the primary combustion air intake occurs upstream of the gaseous fuel inlet, where the gas orifice is located. In general, the opening or openings through which primary air enters the combustion chamber allows insects, mostly spiders, to crawl into the gas mixing chambers. This can lead to either partially or completely closing the gas orifice and obstructing flow in the gas mixing chamber. The combination of dust, debris and insects which clog up the gas orifice or gas mixing chamber make it necessary for the user to periodically clean these areas. However, when a conventional gas burner is mounted to a work or mounting surface of a barbecue grill, the combustion air intake is accessible only from underneath the mounting-top surface. This makes it extremely inconvenient for the user to clean these areas.
To avoid this, “spider guards” have conventionally been placed over the primary air intake openings. These spider guards have had some degree of success, but do not completely prevent spiders and other insects from entering through the fuel and air mixture exit ports in the burner head. Furthermore, the addition of “spider guards” provides an additional surface for debris to accumulate. Ultimately, cleaning of the gas orifice and gas mixing chamber is still required.
In addition, the cleaning procedure for this type of burner system to remove insects, spider webs and accumulated dust and dirt is relatively involved. The user is either forced to access the burner from below the mounting surface or, with some designs, one may be required to detach the entire burner from its mounting on the mounting-top for cleaning.
Another limitation of conventional burners is that the amount of combustion air provided to the burner must be adjusted when switching the type of gaseous fuel used; for example, propane versus natural gas. Also, during certain windy conditions, an adjustment to the combustion air intake is sometimes desired or necessary in order to achieve maximum performance of the burner. These adjustments are normally accomplished by adjusting the size of the opening or openings for the intake of combustion air. However, since these openings are mounted beneath the mounting surface on conventional burners, this adds to the inconvenience of having to make the adjustment.
While there are some burners which provide access to external parts of the burners by removing upper components thereof, most of these burners are not likely to provide sufficient structural stability when mounted to a barbecue with wheels. Such grills are occasionally moved over rough surfaces, such as lawns or spaced-deck boards. The lift-off components of these conventional burners in such instances may become partially or totally dislodged, resulting in an unacceptable condition.
Another problem unique to outdoor gas grills with conventional side burners is the potential for strong winds which blow the primary flame back into the air/fuel mixing chamber. This could cause melting of interior burner parts should they be manufactured out of aluminum.
SUMMARY OF THE INVENTION
The present invention remedies the above-mentioned deficiencies in the art and provides additional structural and functional benefits in outdoor cooking apparatus, such as a barbecue grill with an auxiliary or work-top gas burner (hereinafter referred to as “gas burner” or “burner”) mounted to a mounting or work surface on the barbecue grill.
One embodiment of the invention provides a barbecue grill having a grill housing and a work-top gas burner mounted adjacent the housing on a mounting surface. According to one aspect of the invention, the gas burner is designed and mounted such that its primary combustion air intake is located above the mounting surface, which surface is preferably a work-top of the barbecue grill.
According to another aspect of the invention, the burner includes a fuel inlet, air and fuel mixture exit ports, and a venturi having opposed relatively open ends. The venturi provides a passage between the fuel inlet and the air and fuel mixture exit ports. A base chamber surrounds one of the open ends of the venturi. The chamber has an inner wall which reduces from a wider portion to a narrower portion. The fuel inlet provides access for fuel into the chamber. A combustion air inlet is disposed about a periphery of the chamber, at or near the wider portion of the chamber, and is located such that incoming air at least initially flows into the base chamber in a direction from the wider portion of the chamber toward a narrower portion of the chamber.
In a preferred embodiment of the present invention, first and second peripheral flanges are provided. The first peripheral flange extends circumferentially outwardly from and below the air and fuel mixture exit ports, but above the combustion air inlet. The second peripheral flange extends outwardly from the wider portion of the base chamber below the combustion air inlet. The second flange has an outside diameter which is greater than the diameter of a mounting hole in the work surface of the grill, thereby allowing the burner to be easily mounted to the top of the work surface.
The first and second peripheral flanges are cooperatively located and spaced from each other such that air for combustion flows between the two flanges and into the combustion air inlet. Among other things, the first flange assists in preventing liquid spills from entering the air/fuel mixing chamber. Preferably, the second flange has a thickness dimension which spaces the combustion air inlet to a distance above the mounting surface. This prevents liquids on the mounting surface from flowing into the combustion air inlet. According to another aspect of the present invention, an igniter may be mounted on the second flange and extend through an opening in the first flange, such as to be exposed to the air and fuel mixture exit ports.
Preferably the wider portion of the base chamber is disposed upwardly relative to the narrower portion of the chamber. It is also preferable, according to the embodiments currently tested, that the base chamber be substantially frustoconical in shape; although it is also contemplated that the inner wall of the chamber could be either convex away from a center of the chamber or concave toward a center of the chamber to define other narrowing chambers.
The fuel inlet is preferably joined to the inner wall of the burner base by an arcuate annular wall portion to reduce turbulence and is located at a narrower portion of the chamber.
According to another aspect of the invention, a burner head consisting of a cap, a burner head base plate and a head chamber within the burner head is positioned on the burner base. A means for securing the burner head to the burner base is provided, such that the burner head may be simply lifted off of the burner base for inspection and cleaning of the burner base and the base chamber. With this design, it is not necessary to access the burner from below the mounting surface.
The burner is designed such that individual parts of the burner will not get dislodged and move out of position when, for example, the grill is being moved on an uneven surface, as required by ANSI Z21.58 (1995), or Canadian CGA 1.6 M95 Standard 2.7.1 (“hereafter ANSI shake test”).
Harneit Horst Uwe
Schlosser Erich J.
Shoeb Mohammed
Wallenstein & Wagner Ltd.
Yeung James C.
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