Abstract:
A roller grill assembly includes a roller grill housing and a plurality of rollers disposed in an array and rotatably supported by the housing, each roller having an external heating surface, a first opening at a first end thereof and a second opening at a second end thereof. The roller grill assembly also desirably includes heating elements provided in the rollers for heating the external heating surfaces, and a first insulating end cap secured in the first opening of each roller and a second insulating end cap secured in the second opening of each roller for minimizing heat loss through the ends of the rollers.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention is generally related to cooking units and is more specifically related to roller grill assemblies.  
           [0002]    Roller grill assemblies typically use an array of heatable tubes that are rotatably mounted within a grill housing. In operation, food items are placed upon the roller tubes and the roller tubes are rotated as heat is transferred to the food items.  
           [0003]    There have been many improvements in roller grill assembly technology. Some of these improvements are directed to providing uniform heat temperature levels across the width of the roller tubes. For example, FIG. 1 of U.S. Pat. No. 6,393,971 to Hunot et al. shows a roller grill assembly  20  including a main housing  24 , rotatable roller tubes  26  including two heating members  28 , and roller tube drive assembly  32 . Referring to FIG. 8 thereof, the assembly includes cover plates  217  that serve to reflect heat emanating from the tube ends  194  for uniform heat levels near the ends of the tubes  194 . As shown in FIG. 13 of the &#39;971 patent, the spacing between each of the heating elements  222  is more compact at the outer sections  224 ,  226  thereof, than in the central part  228 . The more compact spacing between the windings in sections  224  and  226  provide for greater wattage and more intense heating at the ends of the roller tubes  26 , than for the interior regions of the roller tube positioned around the less compact portion of the coils  228 .  
           [0004]    U.S. Pat. No. 6,486,448 to Niskanen et al. discloses a method for heating a roll. Instead of heating the roll using a circulating liquid, Niskanen teaches introducing heat at a position very close to the outer surface of the roll mantle for reducing thermal stress, whereby the temperature profile of the roll can be kept substantially more uniform than in rollers heated by a circulating liquid. As a result, large temperature gradients across the roll are eliminated.  
           [0005]    U.S. Pat. No. 6,349,634 to Delpierre III et al. discloses a grill with improved rotary heating elements. Referring to FIG. 1 thereof, the grill  10  includes a plurality of rollers  12  which are rotatably supported by side walls  14 . Each roller has a generally cylindrical exterior surface and at least one internal heating element  16  thermally coupled to the exterior surface of the roller. Referring to FIG. 2 of the &#39;634 patent, wires  30  are fixed to the roller  20  in a helical grid pattern along the length of the cylindrical roller. The wires  30  may be anchored by binding them to rings  24  that extend around the roller at each end of the grid. Referring to FIG. 3, a grid is provided by longitudinal wire segments  32  and circumferential wire segments  34 . The wire grid is preferably in direct contact with the roller for transmitting heat to the roller.  
           [0006]    In spite of the above advances, there remains a need for a roller grill assembly having uniformly heatable rollers, whereby the temperature at the exterior heating surface of the rollers is substantially uniform across the width of the rollers.  
         SUMMARY OF THE INVENTION  
         [0007]    In certain preferred embodiments of the present invention, a roller grill assembly includes a plurality of rollers disposed in an array, each roller having an external heating surface, a first opening at a first end of the roller and a second opening at a second end of the roller. The roller grill assembly also preferably includes a heating element provided in each roller for heating the external surface, a first insulating end cap in communication with the first opening of each roller and a second insulating end cap in communication with the second opening of each roller, whereby the insulating end caps minimize heat loss through the openings at the ends of the rollers by preventing heat from escaping through the ends.  
           [0008]    In some preferred embodiments, the first insulating end caps cover the first openings of the rollers and the second insulating end caps cover the second openings of the rollers. In other preferred embodiments, the first insulating end caps are secured over the first openings of the rollers and the second insulating end caps are secured over the second openings of the rollers. In highly preferred embodiments, the first insulating end caps are integrally connected with the first openings of the rollers and the second insulating end caps are integrally connected with the second openings of the rollers, such as by welding.  
           [0009]    In other preferred embodiments, at least one of the insulating end caps preferably has a central opening and the heating element passes through the central opening. In more preferred embodiments, each of the insulating end caps has a central opening, whereby the heating elements pass through the central openings. In operation, the heating element transfers heat to the exterior surface of the roller tube which, in turn, transfer heat to the food items in contact with the exterior surface of the roller tube.  
           [0010]    The assembly may also include a sprocket connected with each of the first insulating end caps, and a drive element engagable with the sprocket for rotating the first insulating end caps and the rollers. The sprocket and the insulating end cap may be one piece or may be integrally connected with one another. The drive element and the sprocket are desirably arranged for rotating the rollers in the same rotational direction. In highly preferred embodiments, the drive element is a drive chain.  
           [0011]    Each roller preferably has the shape of a substantially cylindrical tube. The rollers are desirably made of a heat conductive material such as metal. Preferred rollers are made of stainless steel and cold rolled steel. Preferred finishes applied over the exterior surfaces of the rollers include chrome plated finishes and non-stick finishes.  
           [0012]    The roller grill assembly also desirably includes supports in contact with the first and second ends of the rollers for rotatably supporting the rollers. The assembly desirably includes a roller grill housing, whereby the supports are secured to the housing for rotatably supporting the rollers.  
           [0013]    The roller grill assembly may also include a sneeze guard secured over the roller grill housing. The sneeze guard is preferably at least partially transparent and made of a polymeric material and includes at least one opening for accessing food product being heated on the rollers. The sneeze guard may also include an elongated slot formed in a top surface of the sneeze guard that is adapted to receive a bottom edge of signage, such as an advertisement or menu board.  
           [0014]    In other preferred embodiments of the present invention, a roller grill assembly includes a roller grill housing and at least one roller rotatably mounted in the housing. The at least one roller has an external heating surface, a first opening at a first end of the roller, a second opening at a second end of the roller, and a heating element provided in the roller for heating the external surface of the roller. The roller grill assembly also desirably includes a first insulating end cap in communication with the first opening of the roller and a second insulating end cap in communication with the second opening of the roller, whereby the insulating end caps minimize heat loss through the openings at the ends of the roller. A sprocket may be connected with the first insulating end cap, and a drive element is desirably engagable with the sprocket for rotating the first insulating end cap and the roller. In other preferred embodiments, the sprocket may be provided at either end of the roller.  
           [0015]    In still other preferred embodiments of the present invention, a roller grill assembly includes a roller grill housing, and a plurality of rollers disposed in an array and rotatably supported by the housing, each roller having an external heating surface, a first opening at a first end of each roller and a second opening at a second end of each roller. The roller grill assembly also desirably includes heating elements provided in the rollers for heating the external heating surfaces, a first insulating end cap secured in the first opening of each roller and a second insulating end cap secured in the second opening of each roller, whereby the insulating end caps minimize heat loss through the ends of the rollers. The assembly may also include drive sprockets having teeth connected with each of the first insulating end caps, and a drive element engagable with the drive sprockets for rotating the first insulating end caps and the rollers. The drive sprockets and the insulating end caps may be integrally connected with one another.  
           [0016]    These and other preferred embodiments of the present invention will be described in more detail below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 shows a perspective view of a roller grill assembly including a plurality of heatable rollers, in accordance with certain preferred embodiments of the present invention.  
         [0018]    [0018]FIG. 2 shows an end view of one of the heatable rollers of FIG. 1.  
         [0019]    [0019]FIG. 3 shows an insulating end cap for covering the end of the roller of FIG. 2, in accordance with certain preferred embodiments of the present invention.  
         [0020]    [0020]FIG. 4 shows the insulating end cap of FIG. 3 covering the end of the heatable roller of FIG. 2.  
         [0021]    [0021]FIG. 5 shows a front elevation view of a heatable roller for the roller grill assembly of FIG. 1 including an insulating end caps secured over open ends thereof, a support element and a heating element.  
         [0022]    [0022]FIG. 6 shows an insulating end cap for an open end of a heatable roller, in accordance with other preferred embodiments of the present invention.  
         [0023]    [0023]FIG. 7 shows an open end of a heatable roller.  
         [0024]    [0024]FIG. 8 shows the insulating end cap of FIG. 6 secured over the open end of the roller of FIG. 7.  
         [0025]    [0025]FIG. 9 shows a front elevation view of the heatable roller of FIG. 8 including the insulating end cap.  
         [0026]    [0026]FIG. 10 shows a series of heatable roller tubes including insulating end caps having sprockets engaged with a driving element, in accordance with certain preferred embodiments of the present invention.  
         [0027]    [0027]FIG. 11 shows a front elevation view of a roller tube including a first insulating end cap at a first end and a second insulating end cap including a sprocket at a second end, in accordance with further preferred embodiments of the present invention.  
         [0028]    [0028]FIG. 12 shows a detailed view of the first end of the roller tube of FIG. 11.  
         [0029]    [0029]FIG. 13 shows a perspective view of the second end of the roller tube of FIG. 11 including a cut-away view of the second insulating end cap with sprockets.  
         [0030]    [0030]FIG. 14 shows a cut-away view of the second end of the roller tube of FIG. 13.  
         [0031]    [0031]FIG. 15 shows a front view of the second insulating end cap shown in FIG. 11. 
     
    
     DETAILED DESCRIPTION  
       [0032]    [0032]FIG. 1 shows a roller grill assembly  20  including a housing  22  having a front control panel  24 , a left support  26  and an opposing right support  28 . The roller grill assembly  20  includes an array of heatable rollers  30  rotatably mounted in the left and right supports  26 ,  28 . The heatable rollers  30  are rotatable and are preferably rotatable in the same direction. In operation, the heatable rollers  30  transmit heat to food items placed atop the rollers.  
         [0033]    Referring to FIGS. 2 and 5, each heatable roller  30  preferably has a first end  32 , a second end  34  and an intermediate region  36  between the first and second ends  32 ,  34 . Each end of the heatable roller tube  30  desirably has an opening at the ends  32 ,  34  thereof.  
         [0034]    Referring to FIG. 2, the roller tube  30  has a first opening  38  at the first end  32  thereof. The roller tube includes an interior surface  40  and an exterior surface  42  opposite the interior surface  40 .  
         [0035]    Referring to FIG. 3, an insulating end cap  44  insertable into the opening at the first end of the roller tube  30  includes an outer perimeter  46  and a central opening  48 .  
         [0036]    Referring to FIG. 4, in certain preferred embodiments, the insulating end cap  44  covers the opening at the first end  32  of roller tube  30 . As will be described in more detail below, the insulating end cap  44  preferably minimizes the amount of heat that may escape through the ends of roller tube  30  so as to provide for more uniform heating of the roller tube  30  across the width of the roller tube.  
         [0037]    Referring to FIG. 5, a first insulating end cap  44  covers the opening at the first end  32  of roller tube  30  and a second insulating end cap  50  covers the opening at the second end  34  of the roller tube  30 . Roller tube  30  is in engagement with a supporting element  52  that passes through the central opening  48  of first insulating end cap  44 , as well as the central opening (not shown) of second insulating end cap  50 . The roller tube  30  also has a heating element which passes through the central openings of the first and second insulating end caps  44 ,  50 . The heating element  54  may be wound around the interior surface  40  (FIG. 2) of the roller tube  30  in a helical pattern for transmitting heat to the exterior surface  33  of the roller tube  30 . In other preferred embodiments, the heating element  54  may pass directly through the center of the roller tube and emanate heat outwardly therefrom.  
         [0038]    Although the present invention is not limited by any particular theory of operation, it is believed that the insulating end caps minimize the amount of heat that may escape or leak through the open ends of the roller tubes. As a result, the heat will tend to remain within the roller tube and more uniformly heat the exterior surface of the roller tube  30 . As noted above in the discussion of prior art roller grill assemblies, roller tubes having open ends allow heat to escape, so that the outer ends of the roller tubes have lower temperatures than the inner ends. As a result, any food product positioned over the outer ends of the roller tubes will not be heated to the same temperature as the food product positioned over the inner regions of the roller tubes.  
         [0039]    [0039]FIGS. 6-9 show a roller tube for a roller grill assembly in accordance with other preferred embodiments of the present invention. Referring to FIG. 6, insulating end cap  144  has a central opening  148  and sprockets  156  on an outer perimeter thereof. The insulating end cap  144  is preferably made stainless steel or cold rolled steel, drawn cold rolled steel or drawn stainless steel.  
         [0040]    Referring to FIGS. 7 and 8, roller tube  130  has an opening  138  at the first end  132  thereof. The insulating end cap  144  is secured over the first opening  138  for at least partially covering the opening at the first end  132  of roller tube  130 . Referring to FIGS.  8  and  9 , the sprockets  156  of the insulating end cap  144  are engagable with a drive element  158 , such as a drive train, for rotating the insulating end cap  148 . Rotation of the insulating end cap  148 , in turn, rotates the roller tube  130 .  
         [0041]    Referring to FIG. 10, the drive element  158  is in engagement with the respective sprockets  156  of a series of insulating end caps  144 A,  144 B,  144 C for rotating the insulating end caps, which, in turn, rotate the respective roller tubes  130 A,  130 B and  130 C. The engagement of the sprockets with the drive element  158  insures that all of the roller tubes  130 A- 130 C rotate in the same direction for rotating food product positioned thereon.  
         [0042]    [0042]FIG. 11 shows a roller tube  230  in accordance with another preferred embodiment of the present invention including first end  232 , second end  234  and intermediate region  236 . A first insulating end cap  244  covers an opening at first end  232  of roller  230 . In addition, a second insulating end cap  250  with sprockets  256  covers an opening at the second end  234  of roller  230 .  
         [0043]    [0043]FIG. 12 shows a detailed view of the first end of the roller tube  230  having an opening  238  at the first end  232  thereof, first insulating end cap  244  having a sealing flange  246  and a central opening  248  secured within the first opening  238 . The sealing flange  246  is preferably welded to the interior surface  240  of roller tube  230 .  
         [0044]    [0044]FIG. 13 shows roller tube  230  having second insulating end cap  250  secured to the opening at the second end  234  thereof. Referring to FIG. 14, second insulating end cap  250  includes central opening  251  and sprockets  256 . The second insulating end cap  250  is secured within an opening at the second end  234  of roller tube  230 .  
         [0045]    [0045]FIG. 15 shows a front view of the second insulating end cap  250  having central opening  251  and sprockets  256 . As shown in FIG. 14, the second insulating end cap  250  is assembled with the second end  234  of roller tube  230 . The second insulating end cap preferably includes a sealing flange  247  that is welded to the interior surface  240  of roller tube  230 . In certain preferred embodiments, the number of teeth on the sprocket is approximately 15-20 evenly spaced around the perimeter of the second insulating end cap  250 . As noted above, the teeth of the sprocket are engagable with a drive element such as a drive chain for rotating the sprocket in second insulating end cap  250 , which, in turn, rotates the roller tube  230 .  
         [0046]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.