Abstract:
A continuous infrared oven and an infrared element therefor wherein the source and return terminals of the element are located on the same lateral side of the oven conveyor and are both accessible through the same oven side wall.

Description:
FIELD OF THE INVENTION 
   The present invention relates to improved infrared ovens and to improved infrared heating elements therefor. 
   BACKGROUND OF THE INVENTION 
   One example of an infrared oven heretofore used in the art is a continuous infrared oven available from Unitherm Food Systems, Inc. for removing purge material and free moisture from the surfaces of bag-cooked turkey breasts or hams prior to applying liquid smoke products or other browning liquids thereto. Another example of an infrared oven known in the art is a continuous infrared oven available from Unitherm Food Systems, Inc. for pasteurizing the surfaces of precooked food products prior to packaging. 
   The continuous infrared ovens used in these applications typically comprise: an elongate insulated housing having inverted-U-shaped inlet and outlet openings; a conveyor (typically a stainless steel wire belt) having an upper carrying run extending longitudinally through the housing; and a series of inverted-U-shaped electrical infrared elements extending laterally over the conveyor carrying run. 
   The inverted-U-shaped infrared elements used in these systems have consisted of: a source terminal located on one lateral side of the conveyor; a return terminal located on the other lateral side of the conveyor; and an inverted-U-shaped element segment extending laterally over the conveyor from the source terminal to the return terminal. The inverted-U-shaped elements thus desirably surround and directly irradiate the upper surface and both side surfaces of the products and can be conveniently sized to allow even large products such as whole turkeys and hams to be conveyed through the oven without difficulty. 
   The Unitherm continuous infrared ovens used for surface pasteurization have also included a series of lower infrared elements extending laterally beneath the wire conveyor for directly irradiating the bottom surfaces of the products. These lower infrared elements have consisted of: a source terminal located on one lateral side of the conveyor; a return terminal located on the other lateral side of the conveyor; and a straight or slightly arched element segment extending beneath the belt from the source terminal to the return terminal. 
   The Unitherm continuous infrared ovens used heretofore for surface pasteurization have been of two basic types, single lane infrared ovens and dual lane infrared ovens. The dual lane ovens have been substantially identical to the single lane ovens except that the dual lane ovens have included a pair of conveyors. The dual conveyors extend side-by-side through the oven housing such that the lateral inner side of one conveyor is adjacent to the lateral inner side of the other conveyor. The upper and lower infrared heating elements used in the dual lane ovens have also been identical to those used in the single lane ovens so that each lane includes its own individual series of upper inverted-U-shaped elements above the belt and its own series of lower elements beneath the belt. Each of the upper and lower elements has a first terminal located on the outer lateral side of the belt and a second terminal located on the inner lateral side of the belt. 
   A need presently exists for an improved dual lane infrared oven and for improved infrared elements which can be used therein. It has been necessary heretofore that the inner end of each of the upper and lower elements used in each lane be installed, and that the necessary leads and connections therefore be directed to and provided within, the central interior portion of the oven. Such interior connections are not readily accessible and (a) significantly increase the complexity of the dual lane oven versus a single lane oven, (b) can require the use of materials capable of withstanding higher temperatures within the central part of the oven, (c) typically require that both processing lanes be shut down when a problem in one lane occurs, and (d) can make the oven more difficult to operate, repair, and maintain. 
   Previous attempts to address these shortcomings have not been successful. It has been suggested, for example, that, rather than each dual lane having its own individual series of upper infrared elements, a single series of wide upper infrared elements be used such that each element extends laterally over both conveyors. The wider elements would thus extend laterally across the entire oven such that the element source terminals would be located on the outer lateral side of one of the belts and the element return terminals would be located on the outer lateral side of the other belt. Unfortunately, the use of such elements results in (a) the inner sides of the products on each belt being shadowed by the products traveling down the other belt and/or (b) the upper infrared elements being much closer to the outer side of the product than to the innerside. Thus, the use of elements of this type would result in uneven, nonuniform irradiation and in inadequate heat transfer to the inner side of the product. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved infrared element and an improved dual lane continuous oven which satisfy the needs and alleviate the problems discussed above. The invention allows the element connections within the interior of the oven between the dual lanes to be eliminated and allows all of the elements in each lane to be installed and connected through an outer wall of the oven. Moreover, the present invention allows each individual conveyor lane to retain its own individual series of upper infrared elements arching from the outer lateral side to the inner lateral side of the conveyor. The direct irradiation of the products on each conveyor is therefore very consistent and uniform and cannot be blocked or shadowed by products traveling down the other conveyor. In addition, the present invention can improve the construction and operation of even a single lane oven by allowing all of the element connections to be made and accessed through one side of the housing. 
   In one aspect, the present invention provides an improved infrared element positionable over a conveyor wherein the element includes a source terminal and a return terminal and is configured to extend upwardly from a first lateral side of the conveyor and downwardly toward a second lateral side of the conveyor. The improvement to this infrared element comprises the source and return terminals being positioned adjacent to each other in a manner such that, when the infrared element is positioned over the conveyor, the source and return terminals will both be located on the first lateral side of the conveyor. The improvement further comprises the infrared element including an outgoing segment comprising: a source end having the source terminal thereon; an upwardly extending portion following the source end; and a downwardly extending portion following the upwardly extending portion. The improvement also comprises the infrared element including a return segment comprising: a return end having the return terminal thereon; a downwardly extending portion preceding the return end; and an upwardly extending portion preceding the downwardly extending portion of the return segment. 
   In another aspect, the present invention provides an improved infrared oven having a conveyor therein and a plurality of infrared elements over the conveyor wherein each of the infrared elements includes a source terminal and a return terminal and is shaped such that one portion extends upwardly from a first lateral side of the conveyor and another portion extends downwardly toward a second lateral side of the conveyor. The improvement comprises both the source terminal and the return terminal of each of the infrared elements being located on the first lateral side of the conveyor. The improvement preferably also comprises each of the infrared elements having (a) an outgoing segment extending from the source terminal and having a first portion extending upwardly away from the first lateral side of the conveyor and a second portion extending downwardly toward the second lateral side of the conveyor and (b) a return segment extending to the return terminal and having a first portion extending upwardly away from the second lateral side and a second portion extending downwardly toward the first lateral side of the conveyor. 
   In yet another aspect, the present invention provides an improved dual lane infrared oven including a first conveyor and a second conveyor, each of the conveyors having an outer lateral side and an inner lateral side and the conveyors extending side by side such that the inner side of the second conveyor is adjacent to the inner side of the first conveyor. The dual lane oven further includes a plurality of first conveyor infrared elements over the first conveyor and a plurality of second conveyor infrared elements over the second conveyor, each of the first and second conveyor infrared elements having a source terminal and a return terminal. Each of the first conveyor infrared elements is shaped such that one portion extends upwardly from the outer lateral side of the first conveyor and another portion extends downwardly toward the inner lateral side of the first conveyor. Similarly, each of the second conveyor infrared elements is shaped such that one portion extends upwardly from the outer lateral side of the second conveyor and another portion extends downwardly toward the inner lateral side of the second conveyor. The improvement to the dual lane infrared oven provided by the present invention comprises: (a) both the source terminal and the return terminal of each of the first conveyor infrared elements being located on the outer lateral side of the first conveyor and (b) both the source terminal and the return terminal of each of the second conveyor infrared elements being located on the outer lateral side of the second conveyor. 
   For each of the conveyors and upper infrared elements corresponding thereto in the improved dual lane infrared oven, the inventive improvement also preferably comprises each of the infrared elements having (a) an outgoing segment extending from the source terminal and having a first portion extending upwardly away from the outer lateral side of the conveyor and a second portion extending downwardly toward the inner lateral side of the conveyor and (b) a return segment extending to the return terminal having a first portion extending upwardly away from the inner lateral side of the conveyor and a second portion extending downwardly toward the outer lateral side of the conveyor. 
   Further aspects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following detailed description of the preferred embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an embodiment  2  of the dual lane infrared oven provided by the present invention. 
       FIG. 2  is an elevational end view of inventive dual lane oven  2 . 
       FIG. 3  is a plan view of inventive dual lane oven  2 . 
       FIG. 4  is an elevational side view of an embodiment  100  of the upper infrared element provided by the present invention. 
       FIG. 5  is an elevational proximal end view of inventive infrared element  100 . 
       FIG. 6  is an elevational distal end view of inventive infrared element  100 . 
       FIG. 7  is a plan view of inventive infrared element  100 . 
       FIG. 8  is a plan view of an embodiment  200  of the lower infrared element provided by the present invention. 
       FIG. 9  is an elevational side view of inventive lower infrared element  200 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   An embodiment  2  of an improved dual lane infrared oven provided by the present invention is shown in  FIGS. 1-3 . The inventive dual lane oven  2  comprises: an elongate insulated housing  4  supported on a frame  6 ; a first conveyor  8  having a horizontal upper carrying run  10  which extends longitudinally through housing  4 ; a second conveyor  12  having a horizontal upper carrying run  14  which extends longitudinally through housing  4 ; a wide, inverted-U-shaped, inlet end opening in housing  4  for delivering products  18  to both of conveyors  8  and  12 ; a wide, inverted-U-shaped, outlet end opening  20  in housing  4  through which products  18  from both of conveyors  8  and  12  are delivered; a series  22  of lateral inventive upper infrared elements  100  positioned over the carrying run  10  of conveyor  8 ; a series  24  of lateral inventive upper infrared elements  100  positioned above the upper carrying run  14  of conveyor  12 ; a series  26  of lateral inventive lower infrared elements  200  positioned below the first conveyor carrying run  10 ; a series  28  of lateral inventive lower infrared elements positioned below the second conveyor carrying run  14 ; and overhead ducts  30  provided in housing  4  above the inlet and outlet openings  16  and  20  for venting hot air from the oven so that it does not otherwise escape into and heat the area surrounding oven  2 . 
   Conveyors  8  and  12  can each be generally any type of oven conveyor used in the art. However, for most applications, conveyors  8  and  12  will each preferably be a stainless steel wire belt or other type of open belt which will allow the infrared energy from lower infrared elements  200  to directly irradiate the lower surfaces of the products  18 . As will be understood, inventive oven  2  preferably includes a belt washer  32  of a type known in the art positioned beneath housing  4  for cleaning the return runs of conveyors  8  and  12 , preferably using a high pressure water spray or other media effective for discharging cinders and other particles from the belts. 
   The carrying run  10  of first conveyor  8  extends longitudinally through housing  4  and has an outer lateral side  32  and an inner lateral side  34 . Similarly, the upper carrying run  14  of second conveyor  12  extends longitudinally through housing  4  and has an outer lateral side  36  and an inner lateral side  38 . As illustrated in  FIG. 2 , first conveyor carrying run  10  and the second conveyor carrying run  14  preferably run side-by-side through housing  4  such that the respective inner lateral sides  34  and  38  thereof are adjacent to each other. In this relationship, the outer lateral side  32  of first conveyor carrying run  10  is positioned adjacent to side wall  40  of oven housing  4  and the outer lateral side  36  of second conveyor carrying run  14  is positioned adjacent to the opposite side wall  42  of the oven housing. 
   The embodiment  100  of the inventive upper infrared element used in oven  2  is shown in  FIGS. 4-7 . The inventive upper infrared element  100  can be an electrical or gas infrared element and will preferably be electrical. The inventive upper element  100  comprises: a source terminal  102  and a return terminal  104  which are preferably adjacent to each other and are co-directional or otherwise directed so that, when installed in oven  2  over either of the conveyor carrying runs  10  or  14 , both the source terminal  102  and the return terminal  104  will be located on the outer lateral side  32  or  36  of the carrying run  10  or  14  and will both be accessible through the same side wall  40  or  42  of the oven housing. 
   The inventive upper infrared element  100  further comprises: a distal turn-around portion  106  which will be positioned on the inner lateral side  34  or  38  of the conveyor carrying run; an outgoing element segment  108  having the source terminal  102  on an initial end portion  103  thereof and extending laterally over the conveyor carrying run  10  or  14  to the distal turn-around portion  106 ; and a return element segment  110  having the return terminal  104  on a terminal end portion  105  thereof and extending laterally over conveyor carrying run  10  or  14  from the distal turn-around portion  106 . In order to allow the products  18  to pass beneath the upper infrared elements  100  and to provide direct and uniform irradiation of the top and side surfaces of the products, the outgoing segment  108  of element  100  is preferably shaped to include an initial portion  112  which will extend upwardly away from the lateral outer side  32  or  36  of the conveyor carrying run  10  or  14  followed by a second portion  114  which will extend downwardly toward the inner lateral side  34  or  38  of the conveyor. Similarly, the return segment  110  will preferably include a first portion  116  which will extend upwardly away from the inner lateral side  34  or  38  of the conveyor followed by a second portion  118  which will extend downwardly toward the outer lateral side  32  or  36 . 
   The distal turn-around portion  106  of inventive upper element  100  can be a substantially straight, horizontal segment as shown in  FIGS. 5-7  or it can be a segment which is continuously curved or has any other shape effective for transitioning from the distal end of outgoing segment  108  to the initial end of return segment  110 . A substantially straight turn-around segment  106  of the type shown in  FIGS. 5-7  allows the outgoing segment  108  and the return segment  110  to extend over the conveyor carrying run in a consistent, parallel spaced relationship all the way to the inner lateral side of the conveyor and is therefore preferred for use in the present invention. 
   To provide consistent and uniform heating and irradiation, the inventive upper infrared element  100  is preferably symmetrical or otherwise configured such that the return segment  110  is substantially a mirror image of outgoing segment  108 . Outgoing segment  108  and return segment  110  will also preferably be spaced apart from and parallel to each other and will each preferably be perpendicular to the carrying run  10  or  14  of the conveyor. 
   The shape of the outgoing and return segments  108  and  110  can be rectangular, continuously arched, or any other shape effective for irradiating the tops and sides of products  18  while allowing the products to travel through the oven. In order to most effectively surround the products  18  laterally and provide uniform spacing for the direct irradiation of the top and both sides of the product, the outgoing and return segments  108  and  110  will most preferably have an inverted-U-shape. In addition, the upper portion of the inverted-U-shape will preferably be a smooth (preferably semicircular) arch as illustrated in FIG.  2 . 
   Embodiment  200  of the lower infrared element provided by the present invention is shown in  FIGS. 8 and 9 . As with the inventive upper infrared element  100 , the inventive lower infrared element  200  preferably includes a source terminal  202  and a return terminal  204  which are adjacent to each other and are co-directional or otherwise directed such that, when installed in inventive oven  2  beneath the conveyor carrying run  10  or  14 , the source terminal  202  and the return terminal  204  will each be located on the outer lateral side  32  or  38  of the conveyor and will be accessible through the same side wall  40  or  42  of housing  4 . To provide consistent uniform heating and irradiation across the bottom of the belt, the inventive lower infrared element  200  preferably comprises a straight outgoing segment  206  and a straight return segment  208  which will extend laterally beneath the conveyor carrying run in a spaced, parallel relationship. 
   Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those skilled in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the appended claims.