Abstract:
A gas burner for producing an annular array of flames includes a circular gas distribution channel distributing gas from an inlet to a circular array of burning ports. The burner includes a gas injector delivering gas to the gas distribution channel tangentially. This reduces the overall footprint of the burner to facilitate its incorporation in small appliances.

Description:
[0001]    This application is related to co-owned U.S. Ser. No. 10/___,___ (Docket #MAC-007) filed on even date herewith and entitled “Patio Heater”. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to burners with a tangential gas. More particularly, although not exclusively, the invention relates to a circular or toroidal burner for use in a heating appliance, such as, but not limited to patio heaters.  
           [0004]    2. State of the Art  
           [0005]    Patio heaters, often used at outdoor restaurants, include a post at the top of which there is situated a gas-burning radiator. These radiate heat primarily downwardly toward restaurant patrons seated at the restaurant&#39;s tables alongside which the heaters are situated. This localised radiation source can be uncomfortable for the restaurant&#39;s patrons, particularly over a period of time.  
           [0006]    Known circular gas burners as used in water heaters and cook-tops for example have a radially extending gas inlet. This not only increases the “footprint” of the burner itself, but also hinder the flow of gas into the annular space beneath the burning ports. Also, where the inlet extends radially from the burner, the gas line attached thereto effectively further increases the required space as the gas line must be bent or curved back (or otherwise contorted to thereby wasted space) for connection to a gas-flow control device that might be mounted on the exterior of the appliance. Furthermore, the gas must turn sharply after having been injected into the annular space via the inlet.  
           [0007]    The burner should preferably be space-efficient in its construction, and have a small footprint so as to enable reduction in the size of the appliance in which it is incorporated. The arrangement of the gas inlet should be such that a gas supply line can be connected thereto in a space-efficient manner.  
           [0008]    A burner should also provide efficient gas distribution to its burning ports.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide a space-efficient gas burner for use in a heating appliance.  
           [0010]    It is another object of the present invention to provide a gas burner giving efficient gas distribution to its burning ports.  
           [0011]    It is a further object of the present invention to provide a circular gas burner having a tangential gas inlet to reduce the “footprint” of the burner and reduce space requirements within the appliance for any gas supply line.  
           [0012]    It is an additional object of the invention to provide a low-mounted gas burner which can provide even heat radiation to heat the inside of a tubular heat exchanger; e.g., a post of a patio heater.  
           [0013]    There is disclosed herein a gas burner having a substantially circular gas distribution channel distributing gas from an inlet that includes a gas injector delivering gas to the gas distribution channel tangentially.  
           [0014]    Preferably, the gas distribution channel distributes the gas to a substantially circular array of burning ports.  
           [0015]    Preferably the inlet includes a mixing tube through which gas from the injector passes tangentially to the distribution channel.  
           [0016]    Preferably a venturi is situated in the mixing tube so as to accelerate gas injected by the injector into the distribution channel.  
           [0017]    The burning ports can be circular apertures.  
           [0018]    Alternatively, the burning ports can be radially extending slots.  
           [0019]    Preferably the distribution channel is annular so as to allow secondary combustion air to pass through a centre thereof.  
           [0020]    There is further disclosed herein a heating appliance having the above-disclosed gas burner mounted therein so as to  
           [0021]    Preferably, the appliance further includes a gas supply line extending substantially co-linearly with and from the gas inlet directly to a gas-flow control valve. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:  
         [0023]    [0023]FIG. 1 is a schematic plan view of a gas burner,  
         [0024]    [0024]FIG. 2 is a schematic cross-sectional elevation of a gas distribution channel,  
         [0025]    [0025]FIG. 3 is a schematic side elevation of the gas burner of FIG. 1,  
         [0026]    [0026]FIG. 4 is another schematic side elevation of the gas burner of FIG. 1,  
         [0027]    [0027]FIG. 5 is a schematic plan view of an alternative gas burner,  
         [0028]    [0028]FIG. 6 is a schematic side elevation of the burner of FIG. 5,  
         [0029]    [0029]FIG. 7 is another schematic side elevation of the gas burner of FIG. 5, and  
         [0030]    [0030]FIG. 8 is a schematic cross-sectional elevational view of a patio heater having the gas burner of either FIG. 1 of FIG. 5 therein. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    In FIGS.  1  to  4  of the accompanying drawings there is schematically depicted a circular or toroidal burner  10 . The burner  10  might typically be formed as a steel pressing, but might alternatively be cast or otherwise fabricated. The burner  10  includes a circular gas distribution channel  21 . Channel  21  is of annular or toroidal form.  
         [0032]    The burner  10  includes a mixing tube  14  via which gas enters venturi or constriction  13  via which gas is accelerated after having been injected by an injector  12 .  
         [0033]    Gas is delivered to the injector  12  via an inlet  11 . A gas-delivery line extending say from a control valve would be attached to the inlet  11 . The gas delivery line might extend straight from the inlet  11  to the control valve as a continuous straight tangent. As one could imagine, this would significantly reduce the footprint of the appliance within which the burner is incorporated, as compared to the situation where the mixing tube extends radially from an edge of the burner  10 .  
         [0034]    The burner  10  includes a plurality of burning ports  15  facing upwardly in use. Optionally, the burner ports may also be located on the sides of the distribution channel. These are distributed the whole way around the burner to provide a circular array of flames. As shown in FIG. 1, the mixing tube  14  extends substantially tangentially from the circular array of burning ports  15 . However, it could be said that the mixing tube  14  is offset slightly radially from a true tangential position. In an alternative construction, the mixing tube  40  could be formed as just beneath the other end portion of the distribution channel. This remote or other end portion would be blocked. In such a construction, the mixing tube  14  would extend linearly from the inlet end of the mixing channel beneath the overlapping end portion.  
         [0035]    As shown in FIG. 2, the distribution channel might be of hexagonal cross-section. However, the cross-section might be circular, square, rectangular or any other conveniently manufactured shape.  
         [0036]    FIGS.  5  to  7  depict an alternative burner  20 , also of circular/toroidal form and including features similar to those described with reference to FIGS.  1  to  4 . In this embodiment however, the burning ports  15  are in the form of radially extending slots. However, there are many styles of burner porting possible. For example, there might be one or more continuous circular slots extending circumferentially.  
         [0037]    In both of the embodiments of FIGS.  1  to  4  and FIGS.  5  to  7 , primary air  16  is drawn the into the venturi  17  via suction forces induced as a result of gas injection by the injector  12 . Also, in each embodiment, secondary combustion through the large hole H shown in the plan view of FIGS. 1 and 5) and the area radially outside of the burner.  
         [0038]    [0038]FIG. 8 depicts a typical installation of a burner  10  or  20 . This diagram shows a patio heater having a heat exchanger  17  within which there is situated an exhaust gas scrub enhancer  19 . The heat exchanger is in the form of a circular cross-sectioned, vertically oriented pipe. It might be desired to direct a ring of flame against the inner surface of the heat exchanger, without wasting flame up through the centre of the heat exchanger. The patio heater of FIG. 8 also includes a heat reflector  30  as described in more detail in U.S. Ser. No. 10/___,___ (Docket #MAC-007) previously incorporated by reference herein.  
         [0039]    The gas burner&#39;s described above are particularly suited to such an application, because a patio heater should not take up too much floor space, particularly in a small outdoor restaurant. The compact heat exchanger of small footprint (with reduced space requirements for the gas-delivery pipe) resulting from the tangential arrangement of the gas inlet and venturi is eminently suitable to such an application.  
         [0040]    It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, instead of being circular, the burner might be oval shaped.  
         [0041]    Also, in a gas cook-top arrangement for example, the burner might be complemented by a centrally-mounted burner enabling a broad spread of flame-control and this might be particularly suited to cooking with a wok.