Patent Publication Number: US-2006005548-A1

Title: Countertop thermoelectric assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      Not Applicable  
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
      Not Applicable  
     REFERENCE TO MICROFICHE APPENDIX  
      Not Applicable  
     FIELD OF THE INVENTION  
      The present invention generally relates to a device for cooling and/or heating a food preparation surface such as a kitchen countertop and, more particularly, to an assembly having a thermoelectric or “Peltier effect” unit for cooling and/or heating a food preparation surface such as a kitchen countertop.  
     BACKGROUND OF THE INVENTION  
      It is sometimes desirable to have a cool working or preparation surface when preparing certain foodstuffs such as, for example, confectioneries like fudge. Such food preparation surfaces are often made from natural stone such as, for example, granite. The natural stone has thermal properties such that it tends to remain relatively cool in most kitchen environments, particularly when the stone has a relatively large thickness. Granite also has other properties such as hardness, scratch resistance, ease of cleaning which make it a desirable material for food preparation surfaces. In commercial kitchens, granite food preparation surfaces and other thermally conductive food preparation surfaces such as, for example, stainless steel are sometimes provided with refrigeration systems to insure a desirable temperature of the preparation surface. An additional benefit of using a granite or other cold preparation surface is that it somewhat cools the ambient temperature of an otherwise warm kitchen environment.  
      Granite, stainless steel, and the like are also popular materials for countertops in residential kitchens because of their natural beauty as well as the above-identified properties suitable for food preparation surfaces. However, because of the relatively thin material thickness of residential countertops, the food preparation surface is typically not as naturally cool as desired for preparing some foodstuffs such as, for example, confectionaries like fudge. Additionally, the refrigeration systems used in commercial kitchens are cost and space prohibitive for most residential kitchens.  
      It is also sometimes desirable to have a warm working or preparation surface when preparing certain foodstuffs such as, for example, baked goods like bread. In commercial kitchens, food preparation surfaces are sometimes provided with heater systems to insure a desirable temperature at the preparation surface. Residential cooking stoves or ranges sometimes have smooth top cooking surfaces but these cooking surfaces provide temperatures which are too high to operate as a food preparation surface for some operations where cooking is not desired such as, for example, a warm surface for rising bread. Additionally, the heater systems used in commercial kitchens are cost and space prohibitive for most residential kitchens.  
      Therefore, most “home chefs” must make do with less than ideal conditions and commercial chefs must purchase multiple systems which are relatively expensive and space consuming. Accordingly, there is a need in the art for an improved device for cooling and/or heating food preparation surfaces such as a countertop or the like.  
     SUMMARY OF THE INVENTION  
      The present invention provides a countertop thermoelectric assembly which overcomes at least some of the above-noted problems of the related art. According to the present invention, a thermoelectric assembly comprises, in combination, a panel forming a preparation surface at an upper side thereof, at least one thermoelectric unit located below the panel and in thermal communication with the panel, a heat sink in thermal communication with the thermoelectric unit, and a controller in electrical communication with the thermoelectric unit to selectively operate the thermoelectric unit to change a temperature of the preparation surface.  
      According to another aspect of the present invention, a countertop thermoelectric assembly comprises, in combination, a portion of a countertop forming a food preparation surface at an upper side thereof and at least one thermoelectric unit located below the countertop and in thermal communication with the countertop. The thermoelectric unit is a Peltier effect device. A thermal transfer plate is located between the countertop and the thermoelectric device. A heat sink is in thermal communication with the thermoelectric unit. A controller is in electrical communication with the thermoelectric unit to selectively operate the thermoelectric unit to change a temperature of the food preparation surface formed by the countertop. A first temperature sensor is in electrical communication with the controller and located to provide signals representative of a temperature of the countertop. A second temperature sensor is in electrical communication with the controller and located to provide signals representative of a temperature of the heat sink.  
      According to yet another aspect of the present invention, a countertop thermoelectric assembly comprises, in combination, a portion of a countertop forming a food preparation surface at an upper side thereof and at least one thermoelectric unit located below the countertop and in thermal communication with the countertop. The thermoelectric unit is a Peltier effect device. A thermal transfer plate is located between the countertop and the thermoelectric device. A heat sink is in thermal communication with the thermoelectric unit. A controller is in electrical communication with the thermoelectric unit to operate the thermoelectric unit to selectively cool and warm the food preparation surface formed by the countertop. A first temperature sensor is in electrical communication with the controller and located to provide signals representative of a temperature of the countertop. A second temperature sensor is in electrical communication with the controller and located to provide signals representative of a temperature of the heat sink. A condensation shield is located below the heat sink and a moisture sensor in electrical communication with the controller and located to provide signals representative of moisture at the condensation shield.  
      From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of thermal control units for food preparation surfaces. Particularly significant in this regard is the potential the invention affords for providing a high quality, reliable, low cost assembly. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and further features of the present invention will be apparent with reference to the following description and drawing, wherein:  
       FIG. 1  is a top plan view of a countertop thermoelectric assembly according to the present invention;  
       FIG. 2  is a front elevational view of the countertop thermoelectric assembly of  FIG. 1 ;  
       FIG. 3  is a side elevational view of the thermoelectric assembly of  FIGS. 1 and 2 ;  
       FIG. 4  is a diagrammatic view of the thermoelectric assembly of FIGS.  1  to  3 ;  
       FIG. 5  is a diagrammatic view of an alternative thermoelectric assembly according to the present invention; and  
       FIG. 6  is a diagrammatic view of the thermoelectric assembly of  FIG. 5  showing inlet and outlet vents.  
      It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of a countertop thermoelectric assembly as disclosed herein, including, for example, specific components, shapes and dimensions will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the countertop thermoelectric assembly illustrated in the drawings. In general, up or upward refers to an upward direction within the plane of the paper in  FIGS. 2 and 3  and down or downward refers to a downward direction within the plane of the paper in  FIGS. 2 and 3 . Also in general, fore or forward refers to a direction toward the front of the countertop and/or kitchen cabinet, that is, a rightward direction within the plane of the paper in  FIG. 3  and aft or rearward refers to a direction toward the rear of the countertop and/or kitchen cabinet, that is, a leftward direction within the plane of the paper in  FIG. 3 .  
    
    
     DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS  
      It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the improved countertop thermoelectric assemblies disclosed herein. The following detailed discussion of various alternative and preferred embodiments will illustrate the general principles of the invention with reference to countertop thermoelectric assemblies for use in cooling and/or heating residential or home food preparation surfaces such as kitchen countertops. Other embodiments suitable for other applications such as, for example, commercial food preparation surfaces or the like will be apparent to those skilled in the art given the benefit of this disclosure.  
      Referring now to the drawings, FIGS.  1  to  4  show a countertop thermoelectric assembly  10  installed on a residential kitchen countertop according to the present invention. The thermoelectric assembly  10  includes a panel such as a countertop  12  forming a food preparation surface  14 , at least one thermoelectric device or unit  16  located below the countertop  12  and in thermal communication with the countertop  12 , a thermal transfer plate or cold sink  18  located between the countertop  12  and the thermoelectric unit  16 , a thermal transfer body or heat sink  20  in thermal communication with the thermoelectric unit  16 , and a controller or control unit  22  in electrical communication with the thermoelectric unit  16  to selectively operate the thermoelectric unit  16  to cool and/or warm the preparation surface  14 .  
      The illustrated thermoelectric assembly  10  is installed on a standard kitchen cabinet  24  supporting the countertop or panel  12 . The panel  12  covers the open top of the cabinet  24  and has a planar top surface which forms the food preparation surface  14  and a planar bottom surface  26  facing the interior space of the cabinet  24 . The panel  12  preferably comprises a solid surface counter material such as, for example, natural stone like granite or marble, stainless steel, poured concrete or man-made solid surface counter materials but any other suitable material can alternatively be utilized. The illustrated countertop  12  includes an insert panel  28  held in an opening in the panel  12  by a support bracket  30 . The illustrated support bracket  30  is generally Z-shaped in cross-section but another other suitable bracket or support means can alternatively be utilized. The illustrated insert panel  28  has a planar top surface  2  which forms the food preparation surface and a planar bottom surface facing the interior space of the cabinet  24 . The insert panel  28  is positioned so that the upper surfaces of the panel  12  and the insert panel  28  form the substantially continuous food preparation surface  14 . The insert panel  28  preferably comprises solid surface counter material such as, for example, a natural stone material like granite or marble, or man-made solid surface counter materials but any other material suitable for cooling and/or warming by the thermoelectric unit  16  can alternatively be utilized. It noted that the insert panel  28  can alternatively be eliminated so that the thermoelectric unit  16  directly cools and/or warms the panel  12  without the opening or the insert panel  28 . It is further noted that the insert panel  28  is preferably eliminated when the panel  12  comprises a suitable material for cooling and/or warming by the thermoelectric unit  16  such as, for example, a natural stone material (best shown in  FIG. 4 ) but the insert panel  28  is preferably utilized when the panel  12  comprises a material not suitable for cooling and/or warming by the thermoelectric unit  16  such as, for example, a laminate material (best shown in FIGS.  1  to  3 ).  
      The illustrated cabinet  24  has a drawer  32  located near the top of the cabinet  24  which opens in a forward. Mounted in this manner, the open top of the drawer  32  faces the bottom surface  26  of the countertop  12  when the drawer  32  is closed. Below the drawer  32  is a hinged door  34  which selectively provides access to a storage space  36  located below the drawer  32 . It is noted that the cabinet  24  can alternatively have any suitable, size, shape, and form such as, for example, the drawer  32  and/or hinged door  34  could be altered and/or eliminated.  
      As best shown in  FIG. 4 , the illustrated thermoelectric unit  16  is located below the panel  12  and in thermal communication with the panel  12  so that operation of the thermoelectric unit  16  cools and/or heats the panel  12  so that the food preparation surface  14  is at a desired temperature. The thermoelectric unit  16  is preferably a Peltier effect device, that is a device sometimes referred to as a “semiconductor refrigerator” that works according to the Peltier effect and either cools or warms an object depending on the direction of current flow therethrough. Such a thermoelectric device  16  typically includes an array of semiconductor couples electrically connected in series and thermally connected in parallel. The semiconductor couples are typically sandwiched between metalized ceramic substrates. When DC electric current is applied in series to the thermoelectric device  16 , it acts as a heat pump with heat being absorbed on the cold side, thereby cooling it, while heat is dissipated at the other side. Reversing the current causes the direction of heat flow to be reversed. Attaching a heat sink  20  and a cold sink  18  to the respective hot and cold sides enhances the efficiency of the thermoelectric device  16 .  
      It is noted that more than one thermal electric unit  16  can be stacked together to produce a sharper thermal gradient and decrease the cooling or warming time for the area of the food preparation surface  14  to be cooled or warmed. It is also noted that more than one thermal electric unit  16  or more than one stack of thermoelectric units  16  can be utilized to increase the overall area of the food preparation surface  14  to be cooled or warmed or, if adequately spaced, to provide more than one distinctly different area of the food preparation surface  14  to be independently cooled or warmed. The thermoelectric assembly  10  of FIGS.  1  to  3 , utilizes four of the thermoelectric units  16  to create a relatively large area of the food preparation surface  14  which is cooled and warmed.  
      As best shown in  FIG. 4 , the thermal transfer plate  18  is a substantially planar member located between the thermoelectric unit  16  and the bottom surface  26  of the panel  12 . The thermal transfer plate  18  preferably is sized substantially equal to area of the food preparation surface  14  which is desired to be cooled and/or warmed. The thermal transfer plate  18  provides a larger footprint than the thermoelectric unit  16  to aid in the transfer of heat over a larger area. The thermal transfer plate  18  preferably comprises a material having a relatively high coefficient of thermal conductivity such as, for example, copper, aluminum, and/or the like. The thermal transfer plate  18  is preferably provided with a suitable thermal transfer medium  38  such as, for example, thermal transfer grease or tape at its interfaces with the panel  12  and the thermoelectric unit  16  to improve heat transfer therebetween.  
      The heat sink  20  is located below the thermoelectric unit  16  and in thermal communication therewith. The heat sink  20  can be unitary with the thermoelectric unit  16  or suitably connected thereto. The heat sink  20  is preferably provided with a suitable thermal transfer medium  40  such as, for example, thermal transfer grease or tape at its interface with the thermoelectric unit  16  to improve heat transfer therebetween. The heat sink  20  is sized and shaped to provide a suitable surface area for the transfer of heat. The heat sink  20  is preferably provided with fins  42  to increase its exterior surface area. The heat sink  20  preferably comprises a material having a relatively high coefficient of thermal conductivity such as, for example, copper, aluminum, and/or the like.  
      A layer of thermally insulating material  44  is preferably provided at the lower side of the thermal transfer plate  18  to ensure that the thermal gradient does not “self cancel.” The layer  44  preferably cover substantially all of the lower surface of the thermal transfer plate  18  which is not covered by the thermoelectric unit or units  16 . The layer  44  can comprise any suitable thermally insulating material.  
      The controller or control unit  22  is adapted to control operation of the thermoelectric assembly  10  so that the thermoelectric unit  16  selectively cools and/or warms the panel  12 . The control unit  22  is in electrical communication with the thermoelectric unit  16  and a suitable power supply  46 . The electric communication can be provided by hard wiring, wireless technology, or a combination. The wireless technology utilized can be, for example, X-10, Bluetooth, or other communication protocols. The illustrated control unit  22  is located above the countertop  12  but can alternatively be located at any other desired location. The control unit  22  preferably includes user input means for initiating cooling and/or warming of the panel  12  by the thermoelectric unit  16 , selecting one of multiple temperature settings such as, for example high and low settings (the control unit  22  can alternatively permit the input of a desired temperature), selecting a duration of time for operation of the thermoelectric unit  16  until operation of the unit automatically shuts off such as, for example, duration of between thirty minutes and two hours (the control unit  22  can alternatively operate the thermoelectric unit  16  for a predetermined non-user adjusted period of time),and selecting between more than one temperature controlled zone when applicable. It is noted that the thermoelectric assembly  10  operates within a temperature range which warms the panel  12  to aid in food preparation but does not heat the panel  12  to a temperature which cooks food.  
      The illustrated thermoelectric assembly  10  also includes first and second temperature sensors  48 ,  50  which are in electrical communication with the control unit  22 . The first temperature sensor  48  is located at the bottom surface  26  of the countertop  12  to provide a signal representative of the temperature at the countertop  12 . The control unit  22  can use this signal to stop operation of the thermoelectric unit  16  or activate a fan (as described in more detail hereinafter) when the countertop temperature reaches a predetermined cutoff temperature or when a predetermined temperature gradient is present across the thermoelectric unit  16 . The second temperature sensor  50  is located at the heat sink  20  to provide a signal representative of the temperature of the heat sink  20 . The control unit  22  preferably uses this signal to stop operation of the thermoelectric unit  16  or activate a fan (as described in more detail hereinafter) when the heat sink  20  temperature reaches a predetermined cutoff temperature or when a predetermined temperature gradient is present across the thermoelectric unit  16 . The temperature sensors  48 ,  50  can be any suitable type of device which provides a signal representative the temperature of a desired location.  
      The illustrated thermoelectric assembly  10  of FIGS.  1  to  3 , includes a condensation guard  52  in the form of a tray or container for catching and holding condensation which drips from the heat sink  20 . The illustrated condensation guard  52  sits in the drawer  32  of the cabinet  24  below the heat sink  20  when the drawer  32  is closed. It is noted that the condensation guard  52  can take other shapes, sizes and locations.  
      As best shown in  FIG. 4 , the various components of the thermoelectric assembly  10  are preferably sized and shaped so that the thermoelectric assembly  10  has a height small enough that the thermoelectric assembly  10  is located entirely above the top of the drawer  32 . The components of the thermoelectric assembly  10  preferably extend below bottom surface  26  of the panel  12  no more than about 1.5 to about 2 inches. Sized in this manner, the drawer  32  can be opening and closed in a normal manner without damage to the thermoelectric assembly  10  and/or drawer  32  or alteration to the cabinet  24  or the drawer  32 . If the thermoelectric assembly  10  extends below the top of the drawer  32 , the drawer  32  is preferably provided with a notch or openings  54 , so that the drawer  32  can be opened and closed without contacting the thermoelectric assembly  10 .  
      It is noted that solid surface countertops do not allow any direct means of attachment thereto. Therefore, when a solid surface countertop is present, a mounting bracket assembly is used to secure the thermoelectric assembly  10  to the cabinet  24  and support the thermoelectric assembly  10  in the desired position in contact with the bottom surface  26  of the panel  12 . It is believed that a mounting bracket similar to a cabinet drawer runner can be affixed horizontally in the cabinet  24  with a spring member and/or adjusting member which provides upward pressure to keep the assembly pressed against the bottom surface  26  of the panel  12 . When an insert panel  28  is used in conjunction with a non-solid surface countertop, a mounting bracket can secure the thermoelectric assembly  10  as described above, directly to the countertop  12 , or to the support bracket  30  of the insert pane  28 .  
       FIGS. 5 and 6  show a countertop thermoelectric assembly  60  according to a second embodiment of the invention which is substantially the same as the thermoelectric assembly  10  of FIGS.  1  to  4  and common reference numbers are utilized throughout. The thermoelectric assembly  60  additionally includes at least one electric fan  62  which is located to direct air over the heat sink  20  to aid in the dissipation of heat therefrom. Additional fans  62  can be provided for this and/or other purposes such as for example, ventilation, backup in case of failure of the first fan  62 , to dry the condensation guard  52 . The illustrated embodiment positions a single fan  62  for directing air over both the heat sink  20  and the condensation guard  52 .  
      The illustrated thermoelectric assembly  60  also is provided with a housing or enclosure  64  which encloses the thermoelectric unit  16  and the heat sink  20 . The enclosure  64  is provided with an air inlet  66  and an air outlet  68 . The illustrated air inlet  66  and air outlet  68  are connected to inlet and outlet vents  70 ,  72  in the front of the cabinet  24  by inlet and outlet ducts or conduits  74 ,  76 . The ducts  74 ,  76  are preferably flexible tubes but can alternatively can any suitable form. Fresh air from the room enters the first vent  70  and travels through the first duct  74  to the air inlet  66 , through the air inlet  66  into the enclosure  64 , through the enclosure  64  over the heat sink  20  and condensation guard  52 , out of the enclosure  64  through the air outlet  68 , through the second duct  76  to the second vent  72  and back into the room. Circulation continues as long as the fan  62  operates. It is noted that alternatively, the inlet vent  70  and inlet duct  74  can be eliminated so that are is drawn from the interior space  36  of the cabinet  24  when there is adequate air mass available within the cabinet. The fan  62  can operate whenever the thermoelectric unit  16  is operating and/or can be activated when certain predetermined conditions are present. The illustrated condensation guard  52  is in the form of a tray at the bottom of the enclosure  64 . The illustrated condensation guard  52  forms the lower portion of the enclosure  64  and provides protection against condensation dripping into the drawer  32  from the heat sink  20 .  
      The illustrated thermoelectric assembly  60  also is provided with a water or moisture sensor  78  in electrical communication with the with the control unit  22 . The moisture sensor  78  is located to provide a signal representative of the moisture at the condensation guard  52  and/or within the enclosure  64 . The control unit  22  preferably uses this signal to continue operation of the fan  62  or activate the fan  62  until all water in the condensation guard  52  and/or enclosure  64  is evaporated. The moisture sensor  78  can be any suitable type of device which provides a signal representing the presence of moisture or water at a desired location.  
      From the above description, it should be appreciated that the present invention provides a countertop thermoelectric assembly  10  and method for warming and cooling a countertop which is relatively simple and inexpensive to produce and operate.  
      From the foregoing disclosure and detailed description of certain preferred embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the present invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the present invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to which they are fairly, legally, and equitably entitled.