Patent Application
20090269712
The present invention relates generally to gas burners and, in particular, to an apparatus for reducing noise that occurs in some appliances when a burner is ignited.
It has been found that some burners, such as premixed burners, i.e., burners in which the air needed for combustion is pre-mixed with the fuel prior to reaching the burner ports, will produce a “ignition pulse” when the burner is lit. The ignition pulse can produce a low frequency rumbling noise especially in appliances with combustion chambers that are sealed or combustion chambers in which ports or openings for admitting secondary air are made relatively small. Many appliances today such as gas fired water heaters are required to be flammable vapor ignition resistant (FVIR) systems. To meet a FVIR requirement for the appliance, individual air openings must be very small in order to prevent flame from passing through them. In order to relieve the ignition pulse, a large number of these openings must be used.
The present invention provides a new and improved apparatus and method for relieving an ignition pulse created at burner ignition while providing a flammable vapor ignition resistant (FVIR) appliance such as a gas fired water heater, room heater, etc.
In accordance with a preferred and illustrated embodiment, a gas-fired appliance is disclosed that includes a burner located in a combustion chamber. A port for allowing the passage of air into and out of, the combustion chamber is provided that is sufficiently sized to relieve an ignition pulse that may be created when the burner is ignited. In accordance with this embodiment, the air opening is overlaid with an element made from a material that contains a plurality of small openings. The material is formed into a cup-shaped configuration so that the total area of the material, including both open and non-open areas of the material, is substantially greater than the area of the air opening.
In a more preferred embodiment, the burner is a pre-mix type burner and the port defines an opening admitting secondary air.
According to a feature of the invention, the material is a wire mesh material and, in a more preferred embodiment, the overlying element is made from two layers of wire mesh material.
In a more preferred embodiment, the element is formed into a tapered cup-shaped element.
The invention contemplates not only an overlying element made from a wire mesh material, but also contemplates the use of a perforated sheet material and/or a perforated ceramic material.
Additional features and a further understanding of the invention will be obtained by reading the following detailed description made in connection with the accompanying drawings.
The illustrated burner is a pre-mixed type burner in which primary combustion air and gas, i.e., natural gas or propane, are pre-mixed prior to entering the main burner housing 12a. In particular, the fuel and primary air enter the burner assembly through a venturi tube opening indicated generally by the reference character 16. For proper operation of the illustrated burner, the combustion chamber 114 in which it is located must have an opening for admitting secondary air.
In general, the burner requires an ignition device to light the burner when heating is desired. This ignition device may be a pilot light or an electronically controlled igniter.
In the illustrated embodiment, the tank construction includes a mounting plate 20 (sometimes referred to as a door) which serves as a means for at least partially mounting the burner 12 within the combustion chamber 14. The plate 20 also serves as a cover for closing off an opening in the tank wall which provides access to the combustion chamber 14 and through which the burner is inserted into the combustion chamber.
In accordance with the illustrated embodiment, the mounting plate 20 also defines a secondary air opening 24 through which secondary air is admitted into the combustion chamber 14. The opening 24 also serves as a combustion relief port for relieving the ignition pulse that is generated when the burner is ignited.
As seen in
In accordance with the invention, the element 30 has a total surface area (including both the non-open and open areas of the material) that is greater than the area of the opening 24. The effective “opening” of the element 30 is determined by the number of openings per unit area multiplied by the size or area of each opening multiplied by the total surface area of the element. It should be noted here, that the total effective open area provided by the element 30 does not have to be equal to or greater than the area of the secondary opening. The total effective opening provided by the element 30 must be sufficient to relieve the ignition pulse generated when the burner is lit.
In accordance with the invention, and as seen best in
Two layers of cup-shaped wire mesh material can be nested together to enhance flammable vapor ignition resistance for the appliance.
Wire mesh materials including, but not limited to, temperature and corrosion resistant metals are contemplated by the present invention. Perforated material such as cast/formed ceramic or formed/drawn perforated sheet metal is also contemplated.
It should be noted here, that the present invention should not be limited to a gas-fired water heater or the construction shown in
It should be noted, that the present invention has been disclosed in connection with a pre-mixed burner and a secondary air opening. Principles of this invention, however, are applicable to other types of burners including non pre-mixed burners. For some appliances, using non pre-mixed burners, an “air opening” is required in order to admit combustion air which may be primary combustion air rather than secondary combustion air.
Although the invention has been described with a certain degree of particularity, it should be understood that those skilled in the art can make various changes to it without departing from the spirit and scope of the invention as hereinafter claimed.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/125,444, filed Apr. 25, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61125444 | Apr 2008 | US |
