Gas burner

Details Gas burner Gas burner

1999-02-09

2002-04-16

Clarke, Sara (Department: 3743)

Combustion

With simulation feature

C431S354000, C239S432000

Reexamination Certificate

active

06371753

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to gas burners, and in particular to a gas burner especially adapted to form part of an artificial fireplace and which produces a yellow flame.
BACKGROUND ART
Artificial fireplaces have become very popular with homeowners. These types of fireplaces normally require little if any maintenance and do not produce solid combustion byproducts or waste such as ash.
In order to be aesthetically pleasing to the homeowner, it is desirable that the artificial fireplace simulate an actual wood burning flame as closely as possible. Flames produced by the burning of hydrocarbons such as natural gas, propane, butane, etc., under generally ideal conditions produce a blue flame. A yellow flame is normally produced when inefficient or incomplete combustion of the fuel occurs.
It is desirable to provide a burner for use in an artificial fireplace that produces a yellow flame that simulates an actual log burning fireplace while providing stable and efficient combustion.
DISCLOSURE OF INVENTION
A new and improved gas fireplace burner intended for use with non-combustible log members which produces a yellow flame and no sooting or substantially reduced sooting.
According to the preferred embodiment, the gas fireplace burner, which is intended to burn gaseous fuels, such as natural gas, butane, propane, etc. includes an elongate, generally tubular body having an inlet end and a closed distal end. A tubular segment extends between the ends. In the preferred and illustrated embodiment, the burner body is made from sheet metal, preferably tubular sheet metal, which can be readily formed and shaped. The inlet end of the body is formed to define a gas orifice holder which mounts a gas orifice element. The inlet end is further formed to define at least one combustion air opening which operates to admit combustion air into an interior region of the body.
A bluff body is located downstream from the gas orifice element and is positioned such that gas emitted by the orifice impinges on the bluff body. The bluff body forces the gas to move to either side of the body it and, in so doing, is encouraged to mix with the incoming combustion air.
A series of flame ports are defined by the tubular segment in order to create a desired, predetermined flame pattern. The flame pattern may be dictated in part by the arrangement of the non-combustible log members.
According to a more preferred embodiment, the inlet end of the burner body is formed with a second combustion air opening. The first and second openings are preferably arranged such that the orifice holder is located intermediate the openings.
According to a feature of the invention, the cross-section of the combustion air openings are sized during the forming operation to accommodate the type of gas to be used and/or the gas flow rate sustainable by the gas orifice.
With the disclosed invention, a relatively inexpensive burner for use in artificial fireplaces is provided. The burner can accommodate a wide variety of orifice sizes and gas types. The inlet end, as indicated above, defines the combustion air openings, the size of which are determined during the forming operation. As a consequence, a single burner design can be used with a wide variety of gases and orifice sizes merely by changing the cross-section of the formed inlet end.
The flame ports are formed in the tubular segment of the burner body and, in the preferred embodiment, are arranged in a linear pattern. At least some of the flame ports are slot-like in configuration and have an effective size that is determined by the orientation of a bent tab element that partially defines each of the ports. The ports are preferably formed by a “lancing” operation which utilizes a punch element that pierces the surface of the tubular segment to form the tab that bends downwardly into the burner plenum. The tab is bent downwardly to define an opening in the burner body through which the gas/air mixture is emitted. In the preferred method, the extent to which the punch is driven into the burner body determines the extent to which the port tabs are bent and, hence, the effective size of the port opening. According to the invention, certain areas of the burner may be formed with smaller sized ports in order to produce a smaller flame at that location. For example, flame ports that are located below a “crossing log”, i.e., a log that is positioned across and supported atop front and rear non-combustible logs forming part of the fireplace assembly, may be of smaller size.
In the illustrated embodiment, the flame ports are arranged in two or more spaced apart rows of adjacent slot-like openings. In the exemplary embodiment, one row of flame ports extends along a substantial length of the tubular segment. Two other row segments of flame ports are preferably arranged in a parallel relationship with the first row of ports, but are longitudinally spaced with respect to each other. In the preferred embodiment, the first row of ports is segmented and includes a central portion that is formed with smaller flame ports. This disclosed arrangement which includes a first row with a central portion having reduced flame port size coupled with two additional, spaced apart row segments of ports leaves a central region of the burner where the flame is smaller or less intense. This reduced flame in the central region allows a transverse log member to be placed across the front and rear log members used in the fireplace assembly. By providing a lower flame height below the transverse log member, Booting is eliminated, or at the very least, substantially reduced. It should be noted here that the present invention contemplates the provision of reduced size ports at other positions in the tubular body to accommodate the positioning of transverse log members. For example, if two transverse log members are used, rows of ports could be provided with reduced port sizes at opposite ends and/or the elimination of flame ports at end segments of flame port rows. In short, the present invention contemplates using either reduced flame port sizes and/or the elimination of flame ports in certain regions of the burner to provide lower flame height below log members.
The burner is especially adapted to be used in an artificial fireplace which utilizes front and rear spaced apart non-combustible log members supported on a log support, such as a grate. The lower flame present in the central portion of the burner allows a transverse log member to be placed across the front and rear log members. By providing a reduced or smaller flame in the central region of the burner body, sooting on the transverse log member is eliminated or substantially reduced.
According to an alternate embodiment of the invention, the bluff body is formed by a pair of confronting depressions formed near the inlet end of the burner body. The confronting dimples or depressions form a pair of venturi channels that communicate with the combustion air openings and control or effect air entrainment. The dimple defines structure that is in a confronting relationship with the orifice element, so that gas emitted by the element must move to either side of the dimple and through the venturi channels. In so doing, the fuel gas is mixed with the incoming combustion air in proper proportion.
It has been found that the disclosed burner provides a very effective yellow flame producing burner that is especially adapted to be used in artificial fireplaces. Unlike prior art burners of this type, relatively large combustion air openings are provided so that clogging of the air inlet by lint, etc. is inhibited. It has been found that with the disclosed construction, the port nearest the orifice can be at a distance that is less than 2½ times the diameter of the tube, which results in a short mixing chamber, i.e., a relatively short segment of the burner body devoted to receiving and mixing the combustion air with the gas.
Additional features of the invention will become apparent and a fuller understanding obtained by reading the following

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