Patent Publication Number: US-8535052-B2

Title: Cap for a gas burner

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a cap for a gas burner. More particularly, the present invention relates to a cap for a gas burner, and a spill resistant gas burner assembly incorporating such a cap. 
     Gas burner assemblies have been widely used in cooking appliances such as free standing cooking ranges, cooktop units. Such gas burner assemblies often include a gas burner unit and a cap disposed on the gas burner unit. As is known in the art, included in the gas burner unit is an ignition system, such as, for example, a piezoelectric starter, that provides a spark for igniting gas flowing out of the gas discharge ports of the gas burner unit. Also as is known in the art, the cap can be made an integral part of the gas burner unit. Alternatively, it can be a removable part sitting on the gas burner unit. In the latter configuration, preferably the cap and the gas burner unit together define a plurality of gas discharge ports along a lateral wall of the gas burner unit (the cap defines the top of each gas discharge port). These are known in the art, and therefore will not be discussed in detail herein. 
     One common problem with gas burner assemblies is that liquids in a cooking vessel or utensil can be heated to such a degree that they may boil over from the top of the cooking vessel and fall onto the cap. Such boiled-over liquid, referred to as “spillover” or “spill” herein, can extinguish the flames of the gas burner unit and even foul the ignition system. In an attempt to prevent a relatively small amount of spillover from flowing into and extinguishing the flames, the cap often has a recessed portion on its top surface to confine the spillover therein. Alternatively and/or additionally, the cap often has a diameter that is slightly greater than that of the gas burner unit so that the cap can steer or direct the spillover away from the gas discharge ports of the gas burner unit. 
     While these caps may operate with some degrees of success, they have various disadvantages. For example, when a relatively large amount of spillover falls onto a known cap discussed above, flames are often extinguished. Moreover, despite efforts with known caps, spillover continues to foul the ignition system because of surface tension between the spillover and the cap as well as dynamics of the spillover. 
     A very large cap can be used to better shield the gas burner unit from spilled liquids. However, this large cap negatively impacts the combustion of the gas flowing out of the gas discharge ports because the flame has to travel almost horizontally a significant distance under the cap, thereby creating excessive flame impingement. It also reduces the heating efficiency of the gas burner assembly because a significant amount of the flame is below the cap and the heat is transferred to the cap rather than the cookware.  FIG. 1  illustrates a side view of an exemplary gas burner assembly  100  wherein a large cap  110  is positioned on a gas burner unit  130 . As illustrated in  FIG. 1 , flame  120  extends a significant distance under the cap  110  before being directed upward to heat a cooking utensil (not shown). This substantially reduces the heating efficiency of the gas burner assembly  100 . Also shown is an igniter  140  that provides a spark for igniting the gas flowing out of the gas burner unit  130 . As illustrated in  FIG. 2 , the cap  110  may be spaced high above the gas burner unit  130  by spacers  210 . In this configuration, the combustion of the gas flowing out of the gas discharge ports may be improved. However, the cooking utensil is positioned further away from the flame  120 ′. As a result, the heating efficiency of the gas burner assembly  200  is again reduced. 
     Hence, there is a need in the industry for a cap which can safely steer or direct spillover away from the ignition system and the flame without substantially reducing the heating efficiency of the gas burner assembly. 
     BRIEF DESCRIPTION OF THE INVENTION 
     As described herein, the preferred embodiments of the present invention meet this and other needs and overcome one or more of the above or other disadvantages known in the art. 
     One aspect of the present invention relates to a cap for a gas burner. The cap includes a center portion including a top surface having a periphery; at least one extension extending outward from the center portion, the at least one extension defining a drain channel extending outward and downward from the top surface; and a ledge extending along the periphery. 
     Another aspect of the present invention relates to a spill resistant gas burner assembly. The assembly includes a gas burner, and a cap disposed above the gas burner. The cap includes a center portion including a top surface having a periphery; a plurality of extensions distributed along the periphery and extending outward therefrom, the extensions defining respective drain channels each extending outward and downward from the top surface; and a ledge extending along the periphery and between adjacent ones of the extensions. 
     These and other aspects and advantages of the preferred embodiments of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. 
     The preferred embodiments shown in the accompanying drawings, and described in the accompanying detailed description, are to be used as illustrative embodiments and should not be construed as the only manner of practicing the invention. Also, the same reference numerals, possibly supplemented with reference characters where appropriate, have been used to identify similar elements. 
     Furthermore, it is to be understood that the figures and descriptions of the preferred embodiments of present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity other elements found in conventional systems of the type described herein. Those of ordinary skill of the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIGS. 1 and 2  illustrate possible gas burner assembly configurations; 
         FIGS. 3A-3D  illustrate a cap in accordance with an exemplary embodiment of the present invention; in  FIG. 3C , part of a corresponding gas burner unit is also shown; 
         FIGS. 4A-4D  illustrate an exemplary gas burner assembly incorporating the cap shown in  FIGS. 3A-3D ; 
         FIG. 5  is another perspective view of the gas burner assembly; 
         FIG. 6  is a cross-section view of an extension of the cap shown in  FIGS. 3A-3D ; and 
         FIG. 7  is another perspective view of the gas burner assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION 
       FIGS. 3A-3D  illustrate a bottom view, a perspective view, a first side view, and a second side view, respectively, of a cap  300  in accordance with an exemplary embodiment of the present invention. 
     As shown in  FIG. 3B , the cap  300  includes a substantially circular main or center portion  301  which has a top surface  302  with a periphery  303 . Preferably three extensions or overhangs  340  extend outward and downward from the center portion  301 . The extensions  340  are preferably substantially uniformly distributed along the periphery  303 . 
     Each extension  340  defines therein a drain channel  360  which controls or directs the spilled liquids away from the top surface  302  of the center portion  301 . More specifically, as illustrated in  FIGS. 3B ,  3 C,  5  and  6 , each drain channel  360  extends outward and downward from the top surface  302 , with its upper end  361  being terminated at the top surface  302  and its lower end  362  being radially spaced apart from a gas burner unit  430 . As clearly shown in  FIGS. 5 and 6 , each drain channel  360  has a main sloped surface  363 , which preferably has a curved or substantially convex cross section. The center line of the main sloped surface  363  forms an acute angle A of at least 10 degrees with the top surface  302 . The angle A is selected so that the gravitation forces on the spilled liquids are greater than the surface tension forces. Hence, the spilled liquids are likely directed away from the top surface  302  through the drain channel  360 . In addition, each drain channel  360  preferably has a second sloped surface  364  extending further outward and downward from the lower end of the main sloped surface  363 . Preferably the second sloped surface  364  also has a curved or substantially convex cross-section. The angle B formed by the center line of the second sloped surface  364  and the top surface  302  is preferably greater than the angle A. The lower end of the drain channel  360  terminates at the lower end of the respective extension  340 . 
     As shown in  FIGS. 3A ,  3 C and  3 D, the cap  300  also includes a substantially circular base portion  350  which extends downward from, and is preferably co-axial with, the center portion  310 . Each extension  340  extends a predetermined distance from the base portion  350 . In one exemplary embodiment, the main section  351  of the base portion  350  has a diameter which is slightly greater than that of the gas burner unit  430 . The cap  300  can removably sit on the gas burner unit  430  with the lower, tapered end section  352  of the base portion  350  being received in the gas burner unit  430  in a manner known in the art. This configuration ensures that after installation, the radially inner most part of the underside of each extension  340  is spaced apart from the upper edge of the lateral wall of the gas burner unit  430  by the height of the main section  351 . Moreover, preferably the outer or lower end of each extension  340  is radially spaced apart from the lateral wall of the gas burner unit  430  by a distance C of at least 0.3125 ( 5/16) inches (see  FIG. 3C ). 
     Extending upward from the center portion  301  along the periphery  303  are ledges  370  that enclose or surround the top surface  302  except for the areas where the extensions  340  engage or merge with the top surface  302 . The ledges  370  act as reflectors to prevent spilled liquids flowing onto the cap  300  from flowing out of the top surface  302  through other areas of the top surface  302 . That is, by retaining spilled liquids within the space defined by the ledges  370  and the top surface  302 , the spilled liquids will likely be directed away from the top surface  302  in a controlled manner only through the drain channels  360 . 
     Although the exemplary embodiment of the invention is shown with three drain channels  340 , it would be recognized by those skilled in the art that the embodiment discussed herein is not limited to the illustrated number of drain channels, but rather may include any number of drain channels  340 . In fact, the cap  300  can have just one drain channel  340 . Such altering of the number of drain channels has been contemplated and considered to be within the scope of the invention claimed. 
       FIGS. 4A-4D  illustrate a top view, a perspective view, a first side view, and a second side view, respectively, of a gas burner assembly  400  in accordance with an exemplary embodiment of the present invention. The gas burner assembly  400  incorporates the cap  300  shown in  FIGS. 3A-3D . In this illustrated embodiment, the cap  300  is centered over the gas burner unit  430  and with respect to a substantially annularly shaped cover  410  for a substantially annularly shaped second gas burner unit  435  which surrounds the gas burner unit  430 . The second gas burner unit  435  and its cover  410  are optional. 
     As shown in  FIG. 5 , during operation, flames  120 ″ extend outward and upward from main gas discharge ports  431  formed on a lateral wall or periphery  432  of the gas burner unit  430 . As discussed earlier, the ledges  370  extend only between the adjacent ones of the extensions  340 . Thus, the lateral wall or periphery  432  of the gas burner unit  430  has portions that angledly correspond to, or vertically align with, the ledges  370 . Preferably, the main gas discharge ports  431  are substantially uniformly distributed only along those portions. In other words, no main gas discharge ports  431  are formed on part of the lateral wall or periphery  432  that is vertically aligned with and here covered by the extensions  340 . This configuration substantially avoids any undesired interference of the extensions  340  with the flames  120 ″. However, as shown in  FIG. 7 , preferably carry-over ports  433  are formed on the part of the lateral wall or periphery  432  that is covered by the extensions  340  such that flames from the main gas discharge ports  431  on one side of an extension  340  are easily carried over to the main gas discharge ports  431  on the other side of the same extension  340  during the ignition process. The carry-over ports  433  are smaller than the main gas discharge ports  431 . Moreover, preferably the carry-over ports  433  are substantially uniformly distributed only on the part of the lateral wall or periphery  432  covered by the extensions  340 . Other than the main gas discharge ports  431  and the carry-over ports  433 , the configuration of the gas burner unit  430  is similar to that known in the art, and therefore will not be discussed in detail here. 
     The configuration of the second gas burner unit  435  and the cover  410  is known in the art (see, for example, US Patent Application Publication No. 2007/0154858, the entire content of which is incorporated herein by reference), and the inner structure of the second gas burner unit  435  therefore will not be discussed here. As clearly shown in  FIGS. 4B-4D  and  5 , the second gas burner unit  435  has a plurality of gas discharge ports  436  which are substantially evenly or uniformly distributed on a later wall  440  of the second gas burner unit  435 . The cover  410  preferably removably sits on the second gas burner unit  435 , and has an inner periphery  437 , an outer periphery  438 , and a curved top surface  439  extending inward and downward from the outer periphery  438  toward the inner periphery  437 . The inner periphery  437  is disposed radially between the main gas discharge ports  431  of the first gas burner unit  430  and the gas discharge ports  436  of the second gas burner unit  435 . As shown in  FIG. 5 , each extension  340  extends beyond the inner periphery  437 , with its lower end thereof being disposed spaced apart from the top surface  439  of the cover  410  and between the inner periphery  437  and the outer periphery  438 . Of course, if the second gas burner unit  435  is large enough, the lower end of each extension  340  can be disposed between the first gas burner unit  430  and the inner periphery  437  of the cover  410 . 
     Each of the cap  300 , the gas burner units  430 ,  435 , and the cover  410  can be formed or made of a suitable material such as a metal. 
     Thus, while there has been shown, described and pointed out fundamental novel features of the invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.