Abstract:
A radiant panel burner is provided having a primary heat emitter and a secondary heat emitter. The radiant panel includes a plenum chamber that houses a baffle connected to a mixer that supplies combustible gas. In a preferred embodiment, the primary heat emitter is a perforated ceramic grid positioned over the plenum chamber and having a plurality of ports through which the combustible gas can travel. The secondary heat emitter is a non-planar radiant panel positioned over the primary heat emitter that generates convective and radiant heat. The non-planar shape of the secondary heat emitter provides more uniform heating and reduces accumulation of cooking by-products. The radiant panel protects the primary heat emitter from contaminants and provides enclosure for the combustion area for more rapid and efficient heating. Together, the primary and secondary heat emitters are configured to provide fast, clean, efficient, and uniform heating within a grilling apparatus.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to burner devices used in food grilling, particularly infrared burners. 
       BACKGROUND OF THE INVENTION 
       [0002]    The trend in barbecuing is to use high intensity infrared heat for searing of meats. However, conventional infrared sear burners used in grilling and barbecuing have several disadvantages. Though infrared burners provided very intense heat, they cover only a limited area and are susceptible to contamination from grease and other food products, flare-ups, and non-uniform heating. The heat is often non-uniformly distributed. There is a need for a more robust and efficient burner to provide uniform, high intensity heat over a broader area of the cooking surface. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention provides an improved high intensity under-fired infrared sear burner for grilling meats and other suitable foods. A radiant panel burner is provided having a primary heat emitter and a secondary heat emitter. The radiant panel includes a plenum chamber that houses a baffle connected to a mixer that supplies combustible gas. In a preferred embodiment, the primary heat emitter is a perforated ceramic grid positioned over the plenum chamber and having a plurality of ports through which the combustible gas can travel. The secondary heat emitter is a non-planar radiant panel positioned over the primary heat emitter that generates convective and radiant heat. The non-planar shape of the secondary heat emitter provides more uniform heating and reduces accumulation of cooking by-products. The radiant panel protects the primary heat emitter from contaminants, provides enclosure for the combustion area for more rapid and efficient heating, and returns radiant heat back to the primary heat emitter for faster heat-up and efficiency. Together, the primary and secondary heat emitters are configured to provide fast, clean, efficient, and uniform heating as compared to conventional infrared sear burner designs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  illustrates a perspective top view of the radiant panel burner of the present invention. 
           [0005]      FIG. 2  illustrates a cross-sectional side view through the center of the radiant panel burner. 
           [0006]      FIG. 3  illustrates a cross-sectional front view through the center of the radiant panel burner. 
           [0007]      FIG. 4  illustrates a cross-sectional front view through the center of two side-by-side radiant panel burners. 
           [0008]      FIG. 5  illustrates a perspective top view of a plurality of radiant panel burners within a grilling structure. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. In other instances, well-known elements, processes or techniques have been briefly mentioned and not elaborated on in order not to obscure the present invention in unnecessary detail and description. Moreover, specific details and the like may have been omitted inasmuch as such details are not deemed necessary to obtain a complete understanding of the invention, and are considered to be within the understanding of persons having ordinary skill in the relevant art. 
         [0010]      FIG. 1  illustrates a perspective top view of a radiant panel burner. The radiant panel burner  110  comprises a mixer  115 , a plenum chamber  130  (i.e., chamber  130 ), a perforated ceramic grid  135  with ports  136 , and a radiant panel  140 . While in a preferred embodiment the grid  135  is made of a perforated ceramic material such as ceramic foam, hard ceramic (cordierite), or ceramic fiber plaque, it could also be made from a perforated metal foam, metal wire mesh or other comparable perforated material that can support surface combustion with a high level of radiant heat. The mixer  115  is a tubular intake element that connects to, and terminates on the interior of, the plenum chamber  130  (see  FIG. 2 ), and is capable of delivering a gas &amp; air mixture into the chamber  130 . In a preferred embodiment, the plenum chamber  130  is a rectangular container that stores said gas/air mixture. Above the chamber  130  sits a perforated ceramic grid  135 , which is the primary emitter of heat in the system. Ports  136  are evenly distributed throughout the grid  135 , and permit the aforementioned gas/air mixture to flow from the plenum chamber  130  and be ignited on the grid&#39;s surface. Lying between  1  to  1 . 5  inches above the ceramic grid  135 , the radiant panel  140  is an angled plate that serves as a secondary emitter of heat. Thus, there is an air gap between the radiant panel  140  (secondary heat emitter) and the ceramic grid  135  (primary heat emitter) in which the ignition and combustion of the gas occurs. 
         [0011]    The radiant panel  140  is preferably composed of a durable metal such as steel or ceramic that can withstand high temperatures without distortion or corrosion. Its length portions are open below the panel, while its width portions possess supporting extensions  141  that extend perpendicularly outward from the sides of the panel  140 , making contact with two of four perimeter extensions  139 . Said supporting extensions  139  extend perpendicularly outward from the vertical sides of the plenum chamber  130  and support the weight of the radiant panel  140 . In a heating capacity, the radiant panel  140  evenly distributes combustive gases, acts as a radiant emitter to provide high quality radiant heat to the cooking surface, distributes convective heat, and returns a portion of heat energy back to the ceramic emitter for fast heat-up and efficiency. Additionally, the radiant panel  140  protects the ports  136  of the grid  135  from cooking matter that inevitably falls from a cooking surface above (e.g. grill surface). The resulting burner system provides a very controlled, high temperature, high efficiency heat propagation that is also very durable under intense cooking conditions. 
         [0012]    Burner operation begins with natural or propane gas passing through a mixer, where it is combined with 100% of the air required for combustion. An internal baffle (see baffle  231  of  FIG. 2 ) inside the plenum chamber  130  distributes the gas/air mixture evenly under the perforated ceramic grid  135 . The gas/air mixture passes through the ports  136  in the ceramic grid  135  and is ignited on the surface. This surface combustion heats the surface of the ceramic to temperatures between 1,600 and 1,800 degrees Fahrenheit. The infrared or radiant heat created by the high temperature of the ceramic is projected to the radiant panel  140 . A portion of the radiant heat is reflected back to the surface of the grid  135 , adding additional heat to the ceramics. The radiant panel can heat up to temperatures between 900 and 1,200 degrees Fahrenheit using conventional gases (e.g. propane), radiating a significant amount of heat to the cooking surface. The radiant panel  140  also functions to distribute convective heat from the combustive gases to the cooking surface. The air beneath the radiant panel  140  is heated and forced upward around the radiant panel  140  to provide convective heating (as described further in connection with  FIG. 3 ). In addition to the radiating and distributing of heat, the radiant panel  140  also protects the perforated ceramic grid  135  from grease, liquids and solid debris from the grilling surface above. When used in a barbecue or gas grille, multiple burners can further provide a uniform heat distribution pattern at the cooking surface. Additional advantages include reduced flare-ups, ease of maintenance, rapid heat-up, and wind resistance. 
         [0013]      FIG. 2  illustrates a cross-sectional side view through the center of the radiant panel burner. The depicted cross-section is made through dashed line “A” of  FIG. 1 , which passes through length of the radiant panel burner  210 . The radiant panel burner  210  comprises a mixer  215 , a plenum chamber  230  with interior baffle  231 , a perforated ceramic grid  235  with ports  236 , and a radiant panel  240 . The mixer  215  further comprises a bracket  216  with an orifice adapter  217 . The bracket  216  holds the orifice adapter  217  off from the venture and is where the air is mixed with the combustible gas. The orifice adapter  217  permits attachment to a gas source (i.e., natural or propane gas) such as by being threaded into a valve or gas manifold. A controlled quantity of said gas is channeled through to an orifice  218  found on the interior terminal end of the orifice adapter  217 . The orifice  218  permits an appropriate quantity of gas to enter through to the mixer  215  via the bracket  216 , thus mixing with all of the air necessary for combustion. As shown in  FIG. 2 , the mixer  215  initially enters into the plenum chamber  230 , then extends further to penetrate the interior of baffle  231 . Here, the flow of the gas/air mixture is controlled and distributed evenly under the perforated ceramic grid  235 . Ports  236  permit the flow of said mixture through the grid  235  and onto its surface, where combustion can occur. From here, radiant heat is not only output to the radiant panel  240  and grilling surface above, but simultaneously conserved and exchanged with the ceramic grid  235  below. Additional convective heat is extended to the grilling surface via the radiant panel  240 . The substantial level of control over gas/air flow throughout the radiant panel burner  210  allows for much more conservative gas usage. Moreover, the multi-step intake, mixture, and dissemination process ensures highly efficient energy output. 
         [0014]      FIG. 3  illustrates a cross-sectional front view through the center of the radiant panel burner and a method for controlled heat emission and transfer. The depicted cross-section is made through dashed line “B” of  FIG. 1 , which passes through the width of the radiant panel burner  310 . The radiant panel burner  310  comprises a mixer  315 , a plenum chamber  330  with interior baffle  331 , a perforated ceramic grid  335  with ports  336 , and a radiant panel  340 . The gas/air mixture fed into the plenum chamber  330  and interior baffle  331  via the mixer  315  is evenly distributed and fed through ports  336 , reaching the surface of the ceramic grid  335  where ignition occurs. Wavy line  300  indicates said ignition, or surface combustion. From this combustion, substantial levels of radiant heat are propagated upward toward the bottom surface of the radiant panel  340 , causing high levels of radiant heat to be propagated above and beyond the top exterior surface of the panel  340 . Upward motion arrows  301  indicate this rising radiant heat. 
         [0015]    Meanwhile, a portion of the radiant heat propagated within the space between ceramic grid  335  and panel  340  is returned to the grid  335 , for additional heating of the ceramic element. Downward motion arrows  302  indicate this quantity of returned radiant heat, which is directed at and absorbed by the ceramic grid  335 . As such, this radiant heat energy  302  is not wasted, but rather, transferred to the ceramic grid  335 , which in turn becomes further heated. This provides conservation of heat  302  provides added efficiency not found in conventional burners. Accompanying these quantities of radiant heat is a portion of convective heat pushed through the open length portions of the radiant panel  340  and upward to a grilling surface. Curved motion arrows  303  indicate convectively propagated heat flowing upward and outward out from beneath the radiant panel  340 . As shown, radiant panel  340  is not flat or planar, but rather, slightly angled and slopes downward from its center toward its terminal lengthwise edges. Its top surface is thus slightly raised along a line parallel to the length axis of the burner  310 . The angled sections of the radiant panel  340  terminate in downward projections  350 . Thus, this cross-sectional view across the width of the secondary heat emitter shows a symmetric surface that slopes downward from the centerline (which coincides with the “ 340 ” label) of the radiant panel to its perimeter edge and then terminates in a vertical or nearly vertical downward projection. These downward projections help protect the combustion/ignition area (air gap) from the wind and contaminants, and isolates this area to promote faster and more efficient heating. 
         [0016]    The slight angle in the shape of the radiant panel  340 , which may ideally be in the range of 3-6 degrees, provides many advantages. First, the shape helps the panel maintain its shape at high temperatures. Further, the angled shape has the effect of spreading out the radiant heat over a broader area, thus promoting a uniform temperature distribution. The angled shape also prevents oils, fats, and other cooking by-products from accumulating on the radiant panel  340 . Thus, the non-flat, convex shape of the radiant panel  340  provides numerous performance advantages. Alternatively, the slope of the radiant panel may be curved (i.e. curved convex surface) rather than linear (i.e. linear convex surface). Thus, as used herein, the term “convex” refers to a slight protrusion or bulge in the upward direction (towards the grilling surface above and away from the plenum chamber) irrespective of whether the bulge is in the form of a linear or curved surface. 
         [0017]    Unlike conventional infrared burners, the flame is effectively enclosed, which provides numerous advantages as well. First, the radiant panel enhances the performance of the infrared burner by reflecting part of the radiant energy back to the surface of the primary emitter (i.e. perforated ceramic grid  335 ). This allows the burner to heat more rapidly and increases the temperature of the primary emitter for more efficiency. By distributing the combustion gases out the side of the burner, heat is better distributed across the surface of the cooking surface or grille. Moreover, because the radiant panel  340  covers the primary emitter (i.e. perforated ceramic grid  335 ), it protects the primary emitter from fat, grease and other cooking by-products that may fall through the grille and would otherwise fall onto the primary emitter below and cause blockage of the ports in the perforated ceramic grid which would decrease efficiency. The radiant panel  340  also protects the burner from wind and drafts that would prevent the burner from working efficiently. Finally the radiant panel  340  provides a smooth cleanable surface that is not affected by harsh chemicals such as oven cleaners. 
         [0018]      FIG. 4  illustrates a cross-sectional front view through the center of two side-by-side radiant panel burners beneath a grilling surface  475 . The depicted cross-section is made through dashed line “B” of  FIG. 1 , which passes through the width of the radiant panel burner  410 . The radiant panel burners  410  comprise a mixer  415 , a plenum chamber  430  with interior baffle  431 , a perforated ceramic grid  435  with ports  436 , and a radiant panel  440 . The angled or curved sections of the radiant panel  340  terminate in downward projections  450 . The gas/air mixture fed into the plenum chamber  430  and interior baffle  431  via the mixer  415  is evenly distributed and fed through ports  436 , reaching the surface of the ceramic grid  435  where ignition occurs. Wavy line  400  indicates said ignition, or surface combustion. From said combustion, substantial levels of radiant heat are propagated upward toward the bottom interior surface of the radiant panel  440 , causing high levels of radiant heat to be propagated above and beyond the top exterior surface of the panel  440 . Upward motion arrows  401  indicate this rising radiant heat. Meanwhile, a portion of the radiant heat propagated within the space between ceramic grid  435  and panel  440  is returned to the grid  435 , for additional heating of the ceramic element. Downward motion arrows  402  indicate this quantity of returned radiant heat. Accompanying these quantities of radiant heat is a portion of convective heat pushed through the open length portions of the radiant panel  440  and upward to a grilling surface. Curved motion arrows  403  indicate this quantity of convectively propagated heat. As described above, each radiant panel  440  is slightly angled (in a linear or curved fashion) and slopes downward from its center toward its terminal lengthwise edges to provide more efficient heat transmission. 
         [0019]      FIG. 5  illustrates a perspective top view of a plurality of radiant panel burners placed in a grilling structure. By way of example, a grilling structure  570  with grilling surface  575  utilizes standard methods of high intensity sear-burning, and is especially suited for grilling meats with infrared heat. The grilling structure  570  provides an enclosure for multiple radiant panel burners  510  (of which four are shown), to be placed two to four inches below the grilling surface  575 .  FIG. 5  shows said radiant panels  510  placed symmetrically into four quadrants of the grilling structure  570 , for ideal, even heating results. During operation, high levels of evenly distributed radiant and convective heat rise from the radiant panels  540  of the burners  510  to reach the underside of food items  590  placed on the grilling surface  575 . The present invention thus provides a highly propagative yet even transmission of heat for grilling food items, producing highly controlled, high-intensity sear-burning. 
         [0020]    While there have been described herein what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein. It is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, substitutions arc contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.