Abstract:
A cooking device and method for removal of contaminants from an air stream that circulates in the cooking device. The cooking device includes a fan that operates to circulate the air stream in a path that includes a cooking chamber and a heating chamber of the cooking device. A catalytic material is disposed on one or more surfaces of a structure that is disposed in close proximity to the fan, such as about the periphery of the fan. The structure may include honeycomb, laminar or finned arrangements.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. provisional application 60/470,818, filed on May 15, 2003, the entire contents of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to cooking devices and, more particularly, to a cooking device with abatement of contaminates, such as grease, smoke and odor.  
       BACKGROUND OF THE INVENTION  
       [0003]     Cooking devices have employed catalytic converters for removal of contaminants from a circulating hot air stream in a cooking device. The contaminants include grease, smoke and other undesired particles that can cause an odor. The catalytic converter flamelessly oxidizes oxidizable components of the contaminants in the circulating hot air stream. Due to the size of known catalytic converters, the ductwork of the cooking device had to be enlarged to accommodate the catalytic converters. This has resulted in larger footprints of the cooking devices.  
         [0004]     Thus, there is a need for a cooking device that has a catalytic converter and that has a relatively small footprint.  
       SUMMARY OF THE INVENTION  
       [0005]     The cooking device of the present invention fulfills the aforementioned need with a catalytic material that is disposed in close proximity to a fan that circulates the air stream in a fluid communication path that includes a cooking chamber and a heating chamber. By locating the catalytic material in close proximity to the fan, instead of in the ductwork, the ductwork can be smaller, thereby allowing a smaller footprint for the cooking device.  
         [0006]     In one embodiment of the cooking device of the present invention, the catalytic material is disposed about the periphery of the fan. In other embodiments, the fluid path extends between the cooking chamber and the heating chamber via a side, a top, a bottom or a back of the cooking chamber.  
         [0007]     In other embodiments of the cooking device of the present invention, the catalytic structure is comprised of a honeycomb arrangement, a laminar arrangement a fin arrangement or an arrangement of a plurality of air passages disposed in a plurality of layers.  
         [0008]     In another embodiment of the cooking device of the present invention, the catalytic structure comprises  
         [0009]     In another embodiment of the cooking device of the present invention, the heater element is elongated and includes a plurality of fins that extend outwardly. The catalytic material is disposed on the heater element. Preferably, the heater element is shaped to extend about the periphery of the fan.  
         [0010]     In another embodiment of the cooking device of the present invention, the catalytic structure comprises a plurality of layers that are separated by air gaps. Each of the layers includes a heater element with the catalytic material being disposed on at least one side of the heating element so as to face one of the air gaps. The circulating air stream flows through the air gaps and is cleansed of contaminants by the catalytic material.  
         [0011]     In another embodiment of the cooking device of the present invention, the catalytic material is also disposed on an opposed side of the heating elements of the layers. In some embodiments, each of the layers further includes a metallic plate disposed between the at least one side of the heater element and the catalytic material. In further embodiments, the catalytic material is also disposed on an opposed side of the heater elements.  
         [0012]     In another embodiment of the cooking device of the present invention, the catalytic material is disposed on at least one blade of the fan.  
         [0013]     In another embodiment of the cooking device of the present invention, the catalytic material is disposed on a fan cover so as to contact the air stream being taken in be the fan.  
         [0014]     The method of the present invention operates a fan to circulate the air stream in a cooking device. A catalytic material is disposed in close proximity to the fan to remove the contaminants from the air stream.  
         [0015]     In another embodiment of the method of the present invention, the catalytic material is disposed on a structure that is positioned substantially in a radial flow of the air stream emitted by the fan.  
         [0016]     In another embodiment of the method of the present invention, the catalytic structure is located about a periphery of the fan.  
         [0017]     In another embodiment of the method of the present invention, the catalytic structure comprises a plurality of layers that are arranged in a laminar arrangement with air gaps between the layers, the air gaps being substantially aligned with the radial flow. The catalytic material is disposed on at least one surface of the layers.  
         [0018]     In another embodiment of the method of the present invention, the catalytic structure comprises a honeycomb arrangement that includes surfaces that define a plurality of air passages that are substantially aligned with the radial flow. The catalytic material is disposed on the surfaces.  
         [0019]     In another embodiment of the method of the present invention, the air stream is heated.  
         [0020]     In another embodiment of the method of the present invention, the air stream circulates in a path that extends through a cooking chamber and a heating chamber of the cooking device. The fan and the catalytic material are disposed in the heating chamber.  
         [0021]     In another embodiment of the method of the present invention, the catalytic material is disposed on at least one blade of the fan.  
         [0022]     In another embodiment of the method of the present invention, the catalytic material is disposed on a fan cover so as to contact the air stream being taken in by the fan.  
         [0023]     In the various embodiments of the cooking device and method of the present invention, heated air makes multiple passes across and through the catalytic structure, thereby cleaning the air of smoke and odors during the cooking process. The multiple pass system has several advantages vis-à-vis a traditional single pass system. The multiple pass system can operate at lower temperatures, thereby providing better baking performance without serious disruption from higher operating temperatures as well as increasing the efficiency. The multiple pass system also allows the catalyst surface area to have a small enough footprint to be disposed in the heating chambers of convection ovens, instead of in a remote area of the oven ductwork.  
         [0024]     The continuous cleaning of the heated air during the cooking process reduces or eliminates the puff of smoke when the cooking device door is opened to remove a cooked food product. This allows the cooking device to be used in locations, such as convenience stores, that do not have an exhaust system for exhausting smoke and other contaminants to the outside. This further allows the cooking device, when installed in exhaust free locations, to cook items, such as meatloaf, that produce smoke and other contaminants. In several of the embodiments the combination heater/catalyst is disposed in the exhaust air of the fan. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference characters denote like elements of structure and:  
         [0026]      FIG. 1  is a perspective view of the cooking device of the present invention;  
         [0027]      FIG. 2  is a perspective view of the cooking device of  FIG. 1  with the heating chamber exploded from the cooking chamber;  
         [0028]      FIG. 3  is a perspective view from another angle of the exploded heating chamber of  FIG. 2 ;  
         [0029]      FIG. 4  is a cross-sectional view of an alternate embodiment of the heater/catalyst structure of the cooking device of  FIG. 1 ;  
         [0030]      FIG. 5  is a perspective view of an alternate embodiment of the fan assembly for the heater chamber of  FIG. 1 ;  
         [0031]      FIGS. 6-8  are cross-sectional views of alternate embodiments of the heater/catalytic structure of  FIG. 5 ;  
         [0032]      FIG. 9  is a perspective view of the oven of  FIG. 1  with top and side covers in phantom showing the fan assembly of  FIG. 5  installed;  
         [0033]      FIG. 10  is a perspective view of an alternate embodiment of the heater/and catalyst structure for the cooking device embodiments of the present invention;  
         [0034]      FIG. 11  is a perspective view of another cooking device embodiment of the present invention;  
         [0035]      FIG. 12  is a top view of  FIG. 11 ;  
         [0036]      FIG. 13  is a perspective view of the fan cover of  FIG. 11 ; and  
         [0037]      FIG. 14  is a perspective view of a blade of the fan of  FIG. 3  or  FIG. 11 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0038]     The cooking device of the present invention includes a circulating air stream that is generated by a fan. Cooking devices of this type, for example, include convection ovens, combination microwave/convection ovens, conveyor ovens and the like. In some cooking devices of the present invention, the ductwork can be arranged to provide columns of impingement air. Also, moisture may be imparted into the air stream. By way of example, the cooking device of the present invention will be described herein in the context of a convection oven.  
         [0039]     Referring to  FIG. 1 , an oven  20  of the present invention includes a housing  22  that has a top panel  24 , a bottom panel  26 , a side panel  28 , a side panel  30 , a back panel  32  and a front panel  34 . A door  36  is mounted to front panel  34  so as to pivot about a fulcrum (not shown) near bottom panel  26  so as to operate as a drop down door. A control section  38  is mounted in front panel  34  above door  36 .  
         [0040]     Referring to  FIG. 2 , a cooking chamber  40  and a heating chamber  42  are shown disassembled from housing  22 . When assembled, cooking chamber  40  and heating chamber  42  are mounted to housing  22  by fasteners and/or supports (not shown). Cooking chamber  40  includes a top  44 , a bottom  46 , a back  48 , a side  50  and a side  52 . Shelf supports  54  and  56  are mounted on sides  50  and  52 , respectively, for holding shelves or racks (not shown) upon which food may be disposed for cooking. Side  50  includes an air intake port  58  located about in the center thereof. Air exhaust ports  60  and  62  are disposed above and offset laterally from intake port  58  and air exhaust ports  64  and  66  are disposed below and offset laterally from intake port  58 .  
         [0041]     Heating chamber  42  is preferably shaped to mate with side  50  of cooking chamber  40 , when assembled thereto by fasteners (not shown). In the embodiment shown in  FIG. 2 , both side  50  and heating chamber  42  have a rectangular shape, but may have other desired shapes. Heating chamber  42  includes a fan assembly  68  mounted thereto.  
         [0042]     Referring to  FIG. 3 , fan assembly  68  includes a fan  70 . A heater/catalyst structure  72  is disposed about the periphery or circumference of fan  70 . Fan  70  draws air from within cooking chamber  40  via air intake port  58  into heating chamber  42 . The air is heated and cleansed of odor and smoke by heater/catalyst structure  72  and then returned to cooking chamber  40  via air exhaust ports  60 ,  62 ,  64  and  66 . That is, fan  70  provides a stream of heated air that circulates through cooking chamber  40  and heating chamber  42  via air intake port  58  and air exhaust ports  60 ,  62 ,  64  and  66 .  
         [0043]     Although oven  20  is shown as a convection oven, it will be apparent to those skilled in the art that oven  20  may alternatively be a structure convection and microwave oven with the microwave energy being supplied to cooking chamber  40  from top  44 , bottom  46 , back  48 , and/or side  52 . It will also be apparent to those skilled in the art that heating chamber, air intake port  58  and air exhaust ports alternatively may be disposed to provide the circulating air to cooking chamber  40  via side  52 , top  44 , bottom  46  or back  48 .  
         [0044]     Fan  70  may suitably be a blower wheel that takes in air along its axis and expels air via its circumferential periphery. For example, fan  70  may be a forward incline, backward incline or radial fan. The expelled air travels through heater/catalyst structure  72 , which removes smoke and other contaminants from and heats the air stream upstream of air exhaust ports  60 ,  62 ,  64  and  66 .  
         [0045]     Heater/catalyst structure  72  may have any suitable shape, such as rectangular (as shown in  FIGS. 2 and 3 ), polygonal, square, circular, oval and the like. In the embodiment shown in  FIGS. 2 and 3 , heater/catalyst structure  72  has a honeycomb structure that contains a large plurality of air passages therethrough.  
         [0046]     Referring to  FIG. 4 , one embodiment of heater/catalyst structure  72  comprises a honeycomb structure  74  that contains a catalyst coating with a heater element  76  disposed within honeycomb structure  74 . Honeycomb structure  74  is formed of a metal or ceramic monolith coated with a catalytic material, which, for example, may be palladium, platinum, a combination thereof, or an alloy thereof.  
         [0047]     Honeycomb structure  72  comprises a relatively large plurality of air passages  78 , each coated with a catalytic material. Air passages  78  are arranged in a plurality of layered rows  80 ,  82 ,  84 ,  86  and  88 . To form honeycomb structure  72 , adjacent rows are offset from one another and alternate rows are aligned with one another. For example, air passages  78  of adjacent rows  80  and  82  are offset from one another and air passages of alternate rows  80  and  84  are aligned with one another. Air passages  78  preferably have a hexagonal shape, but other shapes may be used, such as square, rectangular, polygonal, circular, oval, triangular, and the like. It will be apparent to those skilled in the art that layered structures other than honeycomb are possible to provide a large number of catalytic coated air passages  78 . In all these embodiments, the large number of catalytic coated air passages provide a large catalytic coated surface area to the air stream, which enhances the removal of odor, smoke and contaminants from the air stream.  
         [0048]     Heater element  76  extends along and is adjacent to row  84 . Heater element  76  may be any suitable electrical heater element for heating the air stream and honeycomb structure  74 .  
         [0049]     Referring to  FIG. 5 , another embodiment of heater/catalyst structure  72  includes a laminar structure  90  that has air gaps  92  between adjacent layers and that is shaped to surround the periphery of fan  70 . The layers include heating elements, and/or catalytic elements. As fan  70  rotates, air is taken in from cooking chamber  40  via air intake port  58  and expelled radially through air gaps  92 . The air stream is heated by the heater elements and decontaminated by the catalytic elements. Individual electrical contacts  96 ,  98  and  100  connect the heater elements in circuit with a source of electric energy (not shown). Fan  70  is shown in  FIG. 5 , by way of example, as a radial fan.  
         [0050]     Referring to  FIG. 6 , one embodiment of heater/catalyst structure  72  of  FIG. 5  may be formed of laminar structure  90  that includes a plurality of layers  102 ,  104 ,  106 ,  108 ,  110  and  112  with air gaps  92  disposed between adjacent layers. Each layer is substantially identical so only layer  112  will be described in detail. Layer  112  includes an electrical heater element  101  disposed in a box  103 . Heater element  101  has a pair of electrical contacts  107  that extend externally of box  103 . Catalytic layers  105  are disposed on opposite sides of box  103 . Heater element  101  may be any suitable electrical heating element, such as a coil, strip element and the like. Box  103  may be constructed of metallic sheet material, such as stainless steel, aluminum and the like. Each catalytic layer  105  may be formed of a sheet of catalytic material, which, for example, may be palladium, platinum, a combination thereof, or an alloy thereof.  
         [0051]     Referring to  FIG. 7 , another embodiment of heater/catalyst structure  72  may be formed of a laminar structure  114  of layers  116 ,  118 ,  120 ,  122 ,  124  and  126  that are separated by air gaps  92 . Each layer is substantially identical so only layer  126  will be described in detail. Layer  126  includes a metal plate  130 , a heater element layer  132  disposed on one surface of metal plate  130  and a catalytic element layer  134  disposed on the opposed surface of metal plate  130 . Metal plate  130  may be any good electrical conductivity material, such as stainless steel. Heating element layer  132  may be any suitable electrical resistive heating element material. Catalytic element layer  134  may be any suitable catalytic material, which, for example, may be palladium, platinum, a combination thereof, or an alloy thereof.  
         [0052]     Referring to  FIG. 8 , another embodiment of heater/catalyst structure  72  may be formed of a laminar structure  136  of layers  138 ,  140 ,  142  and  144  that are separated by air gaps  92 . Each layer is substantially identical so only layer  144  will be described in detail. Layer  144  includes a metal plate  146 , a heater element layer  148  disposed on one surface of metal plate  146  and a catalytic element layer  152  disposed on the opposed surface of metal plate  146 . An additional catalytic element layer  150  is disposed on top of heater element layer  148 . Metal plate  146  may be any good electrical conductivity material, such as stainless steel. Heating element layer  148  may be any suitable electrical resistive heating element material. Catalytic element layers  150  and  152  may be any suitable catalytic material, which, for example, may be palladium, platinum, a combination thereof, or an alloy thereof.  
         [0053]     Referring to  FIGS. 5-8 , laminar structures  90 ,  114  and  136  are held together by fasteners  94  that, for example, extend through layers  102 ,  104 ,  106 ,  108 ,  110  and  112  of laminar structure  90  ( FIG. 6 ). Fasteners  94  may be any suitable fasteners and may, for example, be bolts with spacers that separate the laminar sheets so as to provide air gaps  92 .  
         [0054]     Referring to  FIG. 9 , cooking chamber  40  is shown with a portion of back  48  cut away. Thus, heating chamber  42  is located between back  48  of cooking chamber  40  and back panel  32  of oven  20 . Fan assembly  68  is shown installed in heating chamber  42 . Fan assembly  48  includes combination heater/catalyst  72  with the laminar structure of  FIG. 5  that surrounds the periphery of fan  70 . Fan  72  is aligned with an air intake port (not shown) disposed in about the center of back  48  of cooking chamber  40 . The laminar structure may be any of the laminar structures shown in  FIGS. 6-8 .  
         [0055]     Referring to  FIG. 10 , another embodiment of heater/catalyst structure  72  comprises an electrical heater element  160 . Heater element  160  has a plurality of fins  162  extending radially therefrom and disposed along its length at spaced apart locations. Heater element  162  is shaped for disposition around the periphery or circumference of fan  70 . For example, heater element  160  is shown as substantially circular, but may have other shapes as mentioned above for heater/catalyst structure  72 . Heater element  160  and fins  162  are covered with a coating of catalytic material. Electrical contacts  164  are electrically connected to each end of heater element  160 .  
         [0056]     Referring to  FIGS. 11 and 12 , another embodiment of the oven of the present invention comprises an oven  168  that is shown with housing and door removed. Oven  168  includes a cooking chamber  170  and a heating chamber  172 . Cooking chamber  170  includes a top  174 , a bottom  176 , a side  178  and a side  180 . A front of cooking chamber  170  would be closed by a door (not shown) similar to door  36  of oven  20 . A fan cover  182  separates cooking chamber  170  and heating chamber  172 . An air intake port  184  is located in about the center of fan cover  182 . Fan cover  182  is mounted so as to form a peripheral air gap  186  along one or more sides thereof. In the embodiment shown in  FIGS. 15-17 , air gap  186  extends around the entire periphery of fan cover  182  and serves as an air exhaust port. Thus, air gap  186  is located between the periphery of fan cover  182  and top  174 , bottom  176 , side  178  and side  180 . A back  188  is spaced from fan cover  182  and fits flush with top  174 , bottom  176 , side  178  and side  180 . Thus, heating chamber  172  is defined by fan cover  182 , back  188 , top  174 , bottom  176 , side  178  and side  180 .  
         [0057]     A heater/catalyst structure  72  is mounted to fan cover  182  so that fan  70  is aligned axially with air intake port  184 . As shown in  FIG. 12 , heater/catalyst structure  72  is shown as heater element  160  of  FIG. 10 , but could be any of the embodiments of heater/catalyst structure  72 .  
         [0058]     In operation, fan  70  rotates to provide an air stream that is taken in via air intake port  184 , expelled radially from fan  70  through heater catalyst structure  72  and returned to cooking chamber  170  via air gap  186 . Heater/catalyst structure  72  heats and cleans the circulating air. The path of the circulating air stream is shown by the arrows in  FIGS. 11 and 12 .  
         [0059]     Referring to  FIG. 13 , fan cover  182  includes a sheet or panel  190  upon which is disposed a layer of catalytic material  192 . Fan cover  182  includes a port  194 . The catalytic material may also be disposed along the interior of port  194  so as to be in contact with the air stream as it is being taken in by fan  70 . Panel  190  may be a metal, such as stainless steel.  
         [0060]     Referring to  FIG. 14 , a blade  196  of fan  70  includes a layer of catalytic material  198 . I will be appreciated that the other blades (not shown) of fan  70  may also include a layer of catalytic material  198 . Catalytic material  198  is in contact with the air stream as it is being taken in by fan  70 . Blade  196  may be a metal, such as stainless steel.  
         [0061]     The present invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as defined in the appended claims.