Abstract:
A unitary shell for a heating appliance is formed having first and second side panels and first and second end panels. The first end panel has first and second sub panels, each sub panel having a vertical edge and the vertical edges of the first and second sub panels being spaced apart to form an opening between the vertical edges. The first end panel allows the insertion of components through the opening during assembly of the heating appliance. An assembly for a heating appliance may also be formed including the unitary shell and a first heating element attached on the inside of the first side panel. A second heating element is attached on the inside of the second side panel. Each heating element includes at least one terminal adapted to receive a power signal and operates responsive to power being applied to the terminal to generate heat. Furthermore, a method of manufacturing an assembly for a toaster includes providing a shell having first and second side panels and first and second end panels. The first end panel has an opening. A first outer heating element is inserted through the opening and attached to the first side panel. A second outer heating element is inserted through the opening and attached to the second side panel. A center heating element is inserted through the opening and attached to the second end panel.

Description:
TECHNICAL FIELD 
     The present invention relates generally to heating appliances such as toasters or toaster ovens, and more specifically to a shell structure for a heating appliance that includes an open end panel through which components may be inserted during assembly of the heating appliance. 
     BACKGROUND OF THE INVENTION 
     A conventional heating appliance, such as a toaster or toaster oven, generally includes a shell formed from three separate panels. a bottom panel and two end panels. During manufacture of the toaster, these panels, along with a plurality of electrical and mechanical components, are assembled to construct the toaster. FIG. 1 is an isometric view of a conventional toaster  200  with its external case (not shown) removed to illustrate a shell  202 . The toaster  200  is described merely as an example of a conventional toaster, and other similar prior art configurations will be understood by those skilled in the art. The shell  202  is formed from a bottom panel  204 , a rear end panel  206  and a front end panel  208 . Each end panel  206 ,  208  is attached to the bottom panel  204  through tabs (not shown) that are inserted in respective slots  210 ,  212  in the bottom panel, as shown for the end panel  208 . A first outer heating element  214  and second outer heating element  216  are mounted between the end panels  206 ,  208 , each heating element generating heat to toast food items during operation of the toaster. The heating elements  214 ,  216  include respective first terminals  217 ,  219  extending through corresponding apertures in the front end panel  208  and also typically includes a second terminal (not shown) extending through a corresponding aperture (not shown) in the rear end panel  206 . Each of the electrical terminals is adapted to receive a respective power signal that is applied to circuitry (not shown) on the heating element  214 ,  216  to generate heat for toasting food items. To provide added mechanical support for the heating elements  214 ,  216 , a stringer (not shown) is typically attached between the end panels  206 ,  208  along the top edge of each heating element. A center heating element  218  is positioned between the outer heating elements  214 ,  216 , and generates heat to toast respective food items between the element  218  and the outer heating elements  214 ,  216 . The center heating element  218  also typically includes a terminal  221  extending through an aperture in the front end panel  208  and a terminal (not shown) extending through an aperture (not shown) in the rear end panel  206 . None of the electrical terminals  217 ,  219 ,  221  contact the front panel  208 . 
     The toaster  200  further includes an outer bread guard  220  positioned inside the end panel  214 , and an identical outer bread guard  222  positioned inside the side panel  216 . Two inner bread guards  224  and  226  are positioned on both sides of the center heating element  218 . Each of the bread guards  220 - 226  includes a horizontal member  228  and vertical members  230 , as shown for the bread guard  220 . A first bread cavity  232  is defined between the bread guards  220  and  224 , and a second bread cavity  234  is defined between the bread guards  222  and  226 . The bread guards  216 - 222  function to protect bread placed between the bread guards from the heating elements  214 - 218  during operation of the toaster  200 . 
     A first bread tray (not shown) is contained within the first bread cavity  232  and functions to support a piece of bread as it is lowered into and raised from the bread cavity. A second bread tray (not shown) is similarly positioned within the second bread cavity  234  to support another piece of bread in that bread cavity. Each of the bread trays includes a lever  234  extending through slots  224  and  226 , respectively, in the front end panel  208 . The levers  234  are pushed down to lower the respective pieces of bread on the bread trays into the bread cavities  232 ,  234 . As the bread trays are pushed down, the outer bread guards  220 ,  222  move toward the center of the corresponding bread cavity  232 ,  234 , as shown for the bread guard  222 . In this way, the bread guards  220 - 226  position the bread towards the centers of the bread cavities  232  and  234  so that the bread placed on the bread trays is positioned for optimum toasting. The toaster  200  further includes an electronic circuit  236  mounted on the bottom panel  204 . Although not shown in FIG. 1, the circuit  236  is typically coupled to the terminals  217 - 221  and other components of the toaster  200  to control its operation. 
     During manufacture of the toaster  200 , the heating elements  214 ,  216 , and  218 , bread guards  220 - 226 , and a plurality of other electrical and mechanical components must be assembled. It is desirable to automate as much of the manufacturing process as possible in order to reduce the cost and increase the reliability of the toaster  200 . With the conventional shell  202 , however, automating the assembly process is difficult due, in part, to the order in which components must be assembled. For example, as previously described the heating elements  214 - 218  include respective terminals  217 - 221  that extend through apertures in the end panels  206 ,  208 . As a result, to position the heating elements  214 - 218  between the panels  206 ,  208 , one end panel is typically mounted to the bottom panel  204  and then the terminals inserted in the corresponding apertures in that end panel. The terminals at the opposite ends of the elements  214 - 218  are thereafter inserted in the corresponding apertures in the other end panel  206 ,  208  and this panel is attached to the bottom panel  204 . As will be understood by those skilled in the art, this process is difficult to automate. 
     In addition to difficulties presented in automating manufacture, the conventional shell  202  is not very sturdy once assembled. This is due primarily to the end panels  206 ,  208  being fastened to the bottom panel  204  through tabs located at one end. While the end panels  206 ,  208  could be fastened more securely to the bottom panel  204  to make the shell  202  more sturdy, such as by welding the end panels to the bottom panel, this would increase the cost of manufacturing the toaster  200 . Another difficulty presented by the conventional shell  202  is the positioning of the heating elements  214 ,  216  near the ends of the end panels  206 ,  208 . When the heating elements  214 ,  216  become hot during operation, a significant amount of heat may be radiated outward away from the cavities  232 ,  234 . This outward radiated heat may heat an external case (not shown) enclosing the shell  202  to an unacceptably high temperature. It is desirable for the external case to have “cool touch” sides, meaning that the sides of the case remain cool even during operation. A panel (not shown) may be placed between the heating elements  214 ,  216  and the external case, but this requires additional labor and parts, which increase the cost of the toaster  200 . 
     There is a need for a shell structure for a heating appliance that is relatively sturdy, enables automated assembly of the toaster, and enables cool-touch sides to be easily constructed. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a shell for a heating appliance includes first and second side panels and front and rear end panels. The front end panel has first and second sub panels and each sub panel has a vertical edge. The vertical edges of the first and second sub panels are spaced apart to form an opening between the vertical edges that allows the insertion of components through the opening during assembly of the heating appliance. Each sub panel includes an aperture extending to the corresponding vertical edge. The aperture is adapted to receive a portion of one of the components that extends beyond an outer surface of the sub panel. Each side panel may include a mounting panel formed at a bottom edge of the side panel, the mounting panel being adapted to receive a portion of one of the components. 
     According to another aspect of the present invention, a first side heating element is attached on the inside of the first side panel and includes a terminal extending through the aperture in the first sub panel. A second side heating element is attached on the inside of the second side panel and includes a terminal extending through the aperture in the second sub panel. A center heating element is attached to the second end panel between the first and second side heat elements. The center heating element includes a terminal extending through an aperture in the second end panel. Each of the first and second side heating elements and the center heating element operates responsive to a power signal being applied on the corresponding terminal to generate heat. 
     According to a further aspect of the present invention, a method of manufacturing a toaster includes providing a shell having first and second side panels and first and second end panels. The first end panel has an opening. A first outer heating element is inserted through the opening and attached to the first side panel. A second outer heating element is inserted through the opening and attached to the second side panel. A center heating element is inserted through the opening and attached to the second end panel. Outer bread guards may also be inserted through the opening, each outer bread guard being attached adjacent a corresponding outer heating element. 
     According to a further aspect of the present invention, a unitary shell structure for a heating appliance includes first/and second side panels, a rear end panel, and first and second front end panels. All of the panels are integrally formed from a single piece of material, such as, for example, metal. Each of the first and second front end panels has a vertical edge, the vertical edges of the first and second front end panels being spaced apart to form an opening between the vertical edges that allows the insertion of components through the opening during assembly of the heating appliance. Each of the first and second front end panels includes an aperture extending to the corresponding vertical edge, the aperture being adapted to receive a portion of one of the components that extends beyond an outer surface of the front end panel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 is an isometric view of a conventional toaster including a conventional toaster shell. 
     FIG. 2 is an isometric view of a toaster shell according to one embodiment of the present invention. 
     FIG. 3 is an isometric view of a toaster including the toaster shell of FIG. 2 according to one embodiment of the present invention. 
     FIG. 4 is an isometric view of the toaster shell of FIG. 2 showing installation of an outer heating element according to one embodiment of the present invention. 
     FIG. 5 is an isometric view of the toaster shell of FIG. 2 showing upper and lower mounting tabs for installation of a center heating element according to one embodiment of the present invention. 
     FIG. 6 is an isometric view of the toaster shell of FIG. 5 showing installation of the center heating element according to one embodiment of the present invention. 
     FIG. 7 is an exploded isometric view of the upper rear tab of FIG.  5 . 
     FIG. 8 is an exploded isometric view of the lower rear tab of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 2 is an isometric view of a toaster shell  300  according to one embodiment of the present invention. In the embodiment of FIG. 2, the shell  300  is a unitary shell including two side panels  302 ,  304 , a rear panel  306 , and a front panel  308 . The side panels  302 ,  304  each include a pair of upper side tabs  309  with spacers  311  being formed on both sides of each side tab. The tabs  309  function to secure a heating element (not shown) to the corresponding side panel  302 ,  304 , as will be described in more detail below. In FIG. 2, the upper side tabs  309  of the side panel  302  are shown before being bent down to secure the corresponding heating element in place, while the tabs  309  of the side panel  304  are shown after having been bent down to secure the corresponding heating element. Each of the side panels  302  and  304  further includes a horizontal panel  310  formed along its bottom edge. Each horizontal panel  310  includes a plurality of slots  312 , each slot adapted to receive a tab from a corresponding heating element (not shown). In addition to receiving tabs from the corresponding heating element, each horizontal panel  310  also increases the strength of the corresponding side panel  302 ,  304 . 
     In the shell  300 , the front panel  308  includes a left sub panel  316  and right sub panel  318 . An opening  320  is formed between vertical edges of the sub panels  316 ,  318  to allow heating elements and other components to be inserted inside the shell  300  during construction of the toaster, as will be explained in more detail below. Each of the sub panels  316 ,  318  includes a respective aperture  319 ,  321  that extends to the vertical edge of the sub panel. The apertures  319 ,  321  receive a terminal of a heating element being secured to the adjoining side panel  302 ,  304 . A hook  324 ,  325  formed adjoining the apertures  319 ,  321  receives a portion of a bread guard (not shown) during construction of the toaster, as will be described in more detail below. The rear panel  306  of the shell  300  includes an upper rear tab  326  and lower rear tab  328  (not shown in FIG. 2) to which a center heating element (not shown) is attached during construction of the toaster, as will also be described in more detail below. 
     FIG. 3 is an isometric view of one embodiment of a toaster  400  with its external housing (not shown) removed to better illustrate the shell  300  along with a plurality of components mounted in the shell. In the toaster  400 , many of the components perform the same function as corresponding components previously described with reference to the conventional toaster  200  of FIG. 1, and thus, for the sake of brevity, the function of these components will not be described in more detail. The toaster  400  includes first and second outer heating elements  402 ,  404  positioned inside the side panels  302  and  304 , respectively. To secure the heating element  402 ,  404  to the corresponding side panel  302 ,  304 , respectively, tabs along the bottom edge of the heating element are inserted in the slots  312  of the horizontal panel  310  and the upper side tabs  309  are thereafter bent down to secure the heating element in place, as will be described in more detail below. The outer heating elements  402 ,  404  include respective first electrical terminals  406 ,  408  extending through the apertures  319 ,  321  in the front sub panels  316 ,  318 , and respective second electrical terminals  410 ,  411  extending above a top edge of the rear panel  306 . 
     The toaster  400  includes an outer bread guard  418  positioned inside the outer heating element  402 , and a similar outer bread guard  420  positioned inside the outer heating element  404 . The outer bread guard  418  includes a bottom member  422  having a front end that extends through the hook  324  and a rear end that extends through a hole  427  in the rear panel  306  to thereby position the outer bread guard  418  in place. The outer bread guard  420  includes a bottom member  423  that is positioned in the same way. A bottom bracket  426  is attached to the bottom of the front sub panels  316 ,  318  to secure each of the members  422 ,  423  in the corresponding hook  324 ,  325  as shown, and thereby secure the bread guards  418 ,  420  in place. 
     A center heating element  412  is positioned between the heating elements  402  and  404 , and includes a pair of terminals  414  that extend through an aperture in the rear panel  306 . The rear end of the center heating element  412  is attached to the rear panel  306  through the upper rear tab  326  and lower rear tab  328 , as will be described in more detail below. Two inner bread guards  434  and  436  are positioned on respective sides of the center heating element  412 . Each of the inner bread guards  434  and  436  is attached at its rear end through a corresponding tab on the rear panel  306 , and is attached at its front end through a corresponding tab on a carriage support bracket  438  positioned between the front sub panels  316  and  318 . The carriage support bracket  438  has a hole  439  adapted to receive a vertical rod (not shown). A bread carriage (not shown) slides along the vertical rod to raise and lower bread supports in the toaster  400 , as will be understood by those skilled in the art. Although not shown in FIG. 3, the front end of the center heating element  412  is supported through respective tabs formed on the insides of the bottom bracket  426  and carriage support bracket  438 . 
     In the toaster  400 , a first bread cavity  440  is defined between the bread guards  418  and  434 , and a second bread cavity  442  is defined between the bread guards  420  and  436 . A first bread tray (not shown) is contained within the first bread cavity  440  and functions to support a piece of bread as it is lowered into and raised from the bread cavity  440 . A second bread tray (not shown) is similarly positioned within the second bread cavity  442  to support another piece of bread in the bread cavity  442 . Each of the bread carriages includes a lever  444  extending through slots  446  and  448 , respectively, formed between the carriage support bracket  438  and the sub panels  316  and  318 , respectively. The toaster  400  further includes an electronic circuit  428  mounted on the horizontal portion of the bottom bracket  426 . Although not shown in FIG. 3, the electronic circuit  428  is coupled to the terminals  406 - 411  and  414  of the heating elements  402 ,  404 , and  412 , and operates to control the toaster  400  during operation. The specific operation of the electronic circuit  428  and overall operation of the toaster  400  will be well understood by those skilled in the art, and thus for the sake of brevity will not be described in more detail. An example of circuitry that may be utilized to form the electronic circuit  428  is described in U.S. patent application No. 09/307,074 to Lile, filed on May 7, 1999, which is incorporated herein by reference. 
     FIGS. 4-6 illustrate various isometric views of the shell  300  and will be used in describing the process of attaching the heating elements  402 ,  404 , and  412  to the shell  300 . FIG. 4 illustrates the insertion and attachment of the outer heating element  402  to the side panel  302 . Before the outer heating element  402  is attached to the side panel  302 , the upper side tabs  309  are in a substantially vertical position as indicated by the dotted lines in FIG.  4 . To attach the outer heating element  402  to the side panel  302 , the heating element  402  is first inserted along a path indicated by the dotted arrow  500  through the opening  320  and towards the rear panel  306 . When being inserted through the opening  320  along the path  500 , the heating element  402  is vertically positioned so that the terminal  410  is above the top edge of the rear panel  306  and the terminal  406  is just below the top edge of the aperture  319 . Once the heating element  402  has been moved towards the rear panel  306  so that its front edge is inside the front sub panel  316 , the heating element  402  is moved perpendicular to the surface of the side panel  302  as indicated by the arrows  502 . The heating element  402  is moved toward the side panel  302  until the plurality of tabs along the bottom edge of the heating element are in position over corresponding slots  312  in the horizontal panel  310 . When the tabs of the heating element  402  are over the corresponding slots  312 , the heating element  402  is thereafter lowered to insert each of the tabs in a corresponding slot  312  as indicated by the arrows  502 . After the heating element  402  has been lowered, the upper side tabs  309  are thereafter bent as indicated by the arrows to thereby secure the heating element  402  in place. As seen in FIG. 4, the tabs  309  secure the top of the element  402  against the spacers  311 , and in this way the element  402  is secured substantially parallel to the panel  302  at a distance D from the panel. 
     The insertion and attachment of the outer heating element  404  to the side panel  304  is analogous to that previously described for the heating element  402 , and thus for the sake of brevity will not be described in further detail. After the heating elements  402  and  404  are attached to the side panels  302  and  304 , respectively, the outer bread guards  418  and  420  may similarly be inserted through the opening  420  and placed in position adjacent to the corresponding heating element  402 ,  404 . It should be noted, however, that before attaching the bottom bracket  426  (FIG. 3) to the sub panels  316  and  318 , the front ends of the bottom members  422 ,  423  of the outer bread guards  418 ,  420  are merely placed inside the corresponding hooks  324 ,  325 , and not until the bottom bracket  426  is attached to the sub panels  316  and  318  are the front ends of the outer bread guards  418 ,  420  secured in place. 
     FIG. 5 is an isometric view of the shell  300  illustrating in more detail the upper rear tab  326  and lower rear tab  328  for attaching the rear end of the center heating element  412 . Two rear tabs  326 ,  328  are shown in FIG. 5, but the precise number of rear tabs may be varied. FIG. 6 illustrates the process of attaching the center heating element  412  to the rear tabs  326 ,  328 . To attach the center heating element  412 , the center heating element is first moved towards the rear panel  306  as indicated by the arrow  500 . The center heating element  412  is moved towards the rear panel  306  until respective slots  502  and  504  in the element are in line with the tabs  326  and  328 , respectively. The center heating element  412  is thereafter moved towards the side panel  302  as indicated by the dotted arrow  500  to thereby insert the tabs  326  and  328  through the slots  502  and  504 , respectively. The portions of the tabs  326  and  328  extending through the heating element  430  are thereafter deformed, such as by twisting, to secure the heating element  412  to the rear panel  306 . The electric terminals  414  extend through the aperture in the rear panel  306  once the heating element is attached to the rear panel. Once the center heating element  430  has been attached to the tabs  326  and  328 , the bottom bracket  426  (FIG. 3) is attached to the sub panels  316  and  318  as shown in FIG.  3 . The carriage support bracket  438  is thereafter attached to the sub panels  316  and  318 , and the inner bread guards  434  and  436  attached to the carriage support bracket  438  and rear panel  306  as previously described with reference to FIG.  3 . The bread trays (not shown) may be inserted through the horizontal portions of the slots  446 ,  448  (see FIG. 3) after the bracket  438  is attached. As will be understood by those skilled in the art, the point during manufacture at which the bread trays are inserted may be varied. 
     FIG. 7 is an exploded isometric view of the upper rear tab  326  according to one embodiment of the present invention. The upper rear tab  326  includes a projection  700  that extends through the center heating element  412  (not shown) when that heating element is in place against a receiving side  702  of the tab  326 . A guide projection  704  also extends through a corresponding hole in the center heating element  412  when the heating element is in place against the receiving edge  702 , and functions to ensure that the heating element  412  is in the proper vertical position. The projection  700  is deformed once the center heating element  430  is in place against the receiving edge  702  to thereby secure the center heating element to the tab  326 . FIG. 8 similarly is an exploded isometric view of the lower rear tab  328  according to one embodiment of the present invention. The tab  328  includes a projection  800  that extends through the corresponding slot in the heating element  412  (not shown) when the heating element is in place against a receiving edge  802  of the tab  328 . As previously described for the tab  326 , the projection  800  is thereafter deformed to secure the heating element  412  to the tab  328 . 
     The shell  300  enables the insertion of the heating elements  402 ,  404 , and  412  to be automated, reducing the cost and improving the reliability of the toaster  400 . The insertion of these components through automation is possible due to the opening  320  that allows the components to be moved inside the shell  300  and then into position. As previously described, each of the heating elements  402 ,  404 , and  412  includes terminals that must extend through the sides of the shell to provide electrical coupling between components outside the shell and the heating elements. The same is true of the outer bread guards  418  and  420 , which may be inserted through the opening  320  and into place using automation. Furthermore, it should be noted that in the toaster  400 , a space D (see FIG. 4) exists between the side panels  302 ,  304  and the heating elements  402 ,  404 , respectively. These spaces, along with side panels  302  and  304 , provide insulation for heat generated by the heating elements  402 ,  404  and thereby provide cool touch sides for the toaster  400  without further manufacturing operations. More specifically, even where a metal or plastic case is placed over the shell  300 , the combination of the space between each of the side panels  302 ,  304  and the corresponding heating element  402 ,  404  provides sufficient insulation that the sides of the case remain cool even during option of the toaster  400 . 
     It is to be understood that although various embodiments of the present invention have been set forth in the foregoing description, the above disclosure is illustrative only, and changes may be made in detail while remaining within the broad principles of the invention. For example, the number of side tabs  309  one each side panel  302 ,  304  of the shell  300  may be varied, as may the particular shape and size of the apertures  319 ,  321  as well as the shape and size of the opening  320 . Accordingly, the invention is to be limited only by the appended claims.