Patent Application
20070068174
The present invention relates to a cooler for adjusting the temperature of the contents thereof, and more particularly, to a cooler including a thermoelectric cooling apparatus including a heatsink and/or a coldsink formed from a substantially planar sheet material.
For the sake of convenience and not by way of limitation in any manner, the use of the term “cooler” in this disclosure will refer to any apparatus that is capable of defining a volume to chill or freeze foodstuffs. The volume is preferably insulated from heat exchange with the exterior environment. Further, the term “cooler” is intended to include other common apparatuses, such as a container, thermos, ice box, bottle, box, can, storage tank, or any other suitable receptacle.
A refrigerator is one common apparatus useful for adjusting the temperature of the contents thereof. However, in certain situations the refrigerator has several disadvantages. A primary disadvantage is that the refrigerator requires a complex system to chill or freeze foodstuffs including a compressor, heat-exchanging pipes, an expansion valve, and a refrigerant. A secondary disadvantage is that the refrigerator requires a motor, and thus can be noisy to operate. A third disadvantage is that the refrigerator is costly to produce and operate.
Another common apparatus for adjusting the temperature of the contents thereof uses a thermoelectric module, commonly known as a Peltier device. Thermoelectric modules are small solid-state devices that function as a heat pump to either cool or heat a target volume. The modules may be configured with any desired dimensions and are particularly useful in smaller dimensions where complex systems cannot be configured to operate efficiently or are space limited. Generally, in one configuration, for example only and not for limitation, a thermoelectric module includes two electric conductors, two ceramic plates and an array of small bismuth telluride cubes disposed between the ceramic plates. Heat transfer across the plates occurs when a direct current is applied to the two conductors. Further, to increase the rate of heat transfer at least one heat exchanger is commonly added to the thermoelectric module.
However, the conventional Peltier device including a heat exchanger has several disadvantages. As is well know in the art, a higher heat transfer rate may be achieved by increasing the effective heat transfer area of the heatsink exposed to the surrounding medium. The larger surface area aids in both conduction and convention cooling of the target volume, as desired.
A common example of a heatsink is a fin-type heatsink that includes a base plate, in thermal contact with one side of the Peltier device. Further, a series of fins, or protrusions, extend perpendicularly away from the base and extend into the volume. Obviously, a pair of such heatsinks is preferred and in this disclosure one side which draws heat, or cools the volume, will be referred to as the “coldsink” and the other side which rejects heat, or heats the volume, will be referred to as the “heatsink.”
However, conventional heatsink/coldsink design is limited due to the required thickness of the fins, so that the fins will support their own weight and will collapse or come into contact with adjacent fins. Accordingly, conventional fin-type heat exchangers have relatively thick fins, i.e. greater than 0.080 inches. This limitation is the result of the manufacturing processes necessary to produce the heat exchanger. The fins are commonly either extruded or milled, which are both time intensive and costly. Further, the tooling necessary for both processes requires a thicker fin and spacing therebetween. Consequently, the potential surface area of the heat exchanger and spacing of the fins per square inch of base is physically limited.
Therefore, there is a need in the art for a cooler including a thermoelectric cooling apparatus having a more efficient (i.e. more fins, thinner fins, closer spacing, and more surface area per given square inch of base) and cost effective heatsink, that is easy to manufacture.
Certain embodiments are shown in the drawings. However, it is understood that the present disclosure is not limited to the arrangements and instrumentality shown in the attached drawings, wherein:
For the purposes of promoting and understanding the principles disclosed herein, reference will now be made to the preferred embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope is thereby intended. Such alterations and further modifications in the illustrated device and such further applications are the principles disclosed as illustrated therein as being contemplated as would normally occur to one skilled in the art to which this disclosure relates.
In accordance with one principle aspect of the present disclosure, a thermoelectric cooling apparatus comprises a thermoelectric module including a heatsink contiguous with one side of the thermoelectric module and a coldsink contiguous with another side of the thermoelectric module. At least one of the heatsink and the coldsink is configured from a generally continuous planar element and includes a series of lands and opposing grooves, which are each defined about a fold line normal to a longitudinal axis of the continuous planar element. Further, a substantially planar intermediate portion is disposed between each adjacent land and groove. Each groove is contiguous with the thermoelectric module so that heat is transferred by the Peltier effect when direct current is applied to the thermoelectric module.
In accordance with another principal aspect of the present disclosure, the cooler comprises walls that enclose a volume. A thermoelectric module is connected to one of the walls such that a heatsink, contiguous with one side of the thermoelectric module, is disposed external to the volume and a coldsink, contiguous with another side of the thermoelectric module, is disposed within the volume of the cooler. At least one of the heatsink and the coldsink is configured from a generally continuous planar element and includes a series of lands and opposing grooves, which are each defined about a fold line normal to a longitudinal axis of the continuous planar element. Further, a substantially planar intermediate portion is disposed between each adjacent land and groove. Each groove is contiguous with the thermoelectric module so that heat is transferred by the Peltier effect when direct current is applied to the thermoelectric module.
In another aspect of the present disclosure, at least one aperture is formed in at least one of the lands and/or grooves adjacent the respective fold line. In another aspect of the present disclosure, at least one offset element is formed in the intermediate portion of the heat exchanger extending along the longitudinal axis.
In another aspect of the present disclosure, a flange couples at least one of the heatsink and coldsink to the thermoelectric module. In another aspect of the present disclosure, the flange includes a plurality of channels that are complementary to the grooves on the heatsink and/or coldsink.
In another aspect of the present disclosure, a plurality of offset elements are formed in each intermediate portion of the heat exchanger so that adjacent offset elements each project to an opposite side of the intermediate portion.
A lid 28 is configured as the removable top portion of the cooler 86 and includes a hinged door 30 that permits access to the otherwise enclosed volume 82 of the cooler 86. The lid 28 further includes a bridge portion 83 having a front 102 disposed above the door 30, opposing ends 104, 106 and a top 108. The bridge portion 83 and the mounting wall 81 cooperatively define a volume that functions as an upper air channel when the cooler 86 is operative. Vents 32 are formed in each of the opposing ends 104, 106 and extend onto the top 108 so that the fan 84, when operative, draws air into the upper air channel and over heatsinks 24 of the thermoelectric apparatus 20 that are disposed in the air channel. A spacer 90 is disposed in the upper air channel to facilitate efficient routing of the air. A vent 33 is formed in the top 108 of the bridge portion 83 to exhaust air drawn into the upper air channel by the fan 84. Further operation of the cooler 86 will be disclosed in more detail below.
Equipment (not shown) is disposed in the upper air channel and includes the necessary electrical and electronic components for the operation of the thermoelectric apparatus 20, which will be recognized by one of skill in the art and is discussed in greater detail in reference to
The thermoelectric apparatus 20, in this embodiment, is connected to the mounting wall 81 such that the coldsinks 26 are disposed within the volume 82 in order to facilitate adjustment of the temperature thereof. A deflector plate 54, connected to the walls 80 and the mounting wall 81, cooperatively define a lower air channel. The coldsinks 26 and the fan 84 are disposed in the lower air channel. The deflector plate 54, in this embodiment, is configured as a plastic element that is connected to the mounting wall 81 and rear wall 80 and is spaced, at each end, from opposing side walls so that the fan 84 may exhaust air drawn into the lower air channel through a bottom air vent 34. A drip hole 42 is configured as an aperture formed in the bottom wall of the cooler 86 that defines a passage from inside the volume 82 to the outside of the volume 82. A wick 40 is disposed outside of the volume 82 such that condensate, i.e., water, passing through the drip hole 42 must flow over the wick 40 in a convoluted path to a catch pan 52.
A rack element 36 is disposed adjacent each of the vertical walls 80 and the bottom wall to support the contents thereof and space the contents from the walls to avoid contact with any condensate. A thermometer 38 may be provided to display a temperature within the volume.
In one embodiment, a thermometer 38 may be provided that is operatively coupled to appropriate equipment, as will be recognized by one of skill in the art, so that the thermoelectric apparatus 20 may be electronically controlled to adjust the temperature within the volume 82.
In the preferred embodiment, a heatsink 24 is connected to one side of the thermoelectric module 22 and a coldsink 26 is connected to another, opposite side of the thermoelectric module 22. At least one of the heatsink 24 and the coldsink 26 is formed from a continuous generally planar element 44. In the embodiment shown in
In one embodiment, the thermoelectric module 22 is operatively thermally coupled to a spacer 68 which is configured with a specified thickness to facilitate orienting the coldsink 26 within the volume 82 and the heatsink 24 exterior to the volume 82, substantially as thick as the walls 80, not shown.
In another embodiment, the thermoelectric apparatus 20 includes a flange 76 operatively associated with each heatsink 24 and coldsink 26 formed from the generally planar element 44. Each flange 76, 78 has a series of channels 78 that are collectively formed with complementary surfaces to facilitate meshing with the grooves 48. Such heatsink 24 and/or coldsink 26 is connected to the respective flange 76 to facilitate increased heat transfer by way of greatly increased surface area. The heatsink 24 and/or coldsink 26 may be connected in any suitable manner sufficient to provide the transfer of heat. In one embodiment, threaded fasteners 58 are useful for coupling all the elements of the thermoelectric apparatus 20 together. In another embodiment, a thermal adhesive 56 may be disposed between the heatsink 24 and/or coldsink 26 and the respective flange 76 to facilitate the coupling. Any suitable thermal adhesive may be used to perform the intended functionality. Further, screw holes 60 and the screws 58 can be used to assemble the thermoelectric apparatus 20. Screw holes 60 are formed in the heatsink 24, the coldsink 26, the flange 76, and the housing element 68.
In another embodiment, either the heatsink 24 and/or the coldsink 26 include a plurality of offset elements 66. The plurality of offset elements 66 are formed in the intermediate portion 62 wherein adjacent offset elements each project to an opposite side of the intermediate portion 62. Each offset element 66 is formed so that the elongated height of the offset element 66 is generally normal to the fold line 50. The offset element 66 is preferably formed with a press or stamp punch apparatus (not shown). Further, the offset elements 66 are formed in the generally planar element 44 before the forming of the lands 46 and grooves 48.
Further, the offset elements 66 facilitate an improved heat transfer rate in the heatsink/coldsink by way of creating a turbulent airflow in the heatsink/coldsink. The structural configuration of the offset portions 66 strengthens the intermediate portion 62, keeps adjacent intermediate portions 62 spaced apart and provides turbulence to air flowing there between, thus facilitating an increased rate of heat transfer.
While the particular preferred embodiment has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made. For example, changing the profile of the offset element 66, or modifying the number and/or location of the offset elements 66.
In another embodiment, the planar element 44 includes a plurality of offset elements 66. Each offset element extends from approximately the fold line 50 to the substantially planar intermediate portion 62. However, it is possible to have other variations, such as the offset element 66 only being located on the substantially planar intermediate portion 62. Further, the offset elements 66 overlap, thus forcing the air to follow a convoluted path. This convoluted path creates turbulent airflow in the heatsink 24.
In another embodiment, the heatsink 24, and more specifically the grooves 48, will couple to the thermal adhesive 56. Further, the flange 76 has complementary surfaces, the flange channels 78, to facilitate meshing with the grooves 48 and the thermal adhesive 56. The flange 76 also thermally couples to the thermoelectric module 22, and the housing element 68.
Further, electrical power is supplied to a motor 91 outside of the volume, that includes a shaft 92 having a first end 93 outside the volume 82 and a second end 94 extending into the volume 82. A fan blade is connected to each of the first end 93 and the second end 94.
During operation of the cooler 86, ice may form on the coldsink and then may melt and drip from the cold sink, if the lid is opened for a certain period of time, because the warmer outside air flows into the volume 82. Apertures 64 formed in the coldsinks 26 allow the melted ice to drip out of the coldsink 26. Thus, the grooves 48 of the heatsink 24 have apertures 64, which allows the water to flow out of the cold sink 26.
The deflector plate 54, as discussed in
Further, once the correct voltage and current is set, DC power 98 is provided to the fan motor 91. On a separate DC power line 98, two thermoelectric apparatuses 20 electrically connect in series. More specifically, DC power 98 is electrically provided to the thermoelectric modules 22.
Further, once the correct voltage and current is set, DC power 98 is provided to the fan motor 91. In this embodiment, four thermoelectric apparatuses 20 electrically connected as two pairs of parallel devices to the DC power 98. More specifically, DC power 98 is electrically provided to the thermoelectric modules 22.
In another embodiment, the thermometer (38, in
As briefly mentioned above, a fan draws air in through the vent 32 and then across the heatsinks 24. The fan blade 95 on the second end 94 draws air in through bottom air vent 34, which is formed in the deflector plate 54, and then across the coldsinks 26.
As discussed in detail above, a plurality of offset elements 66 are formed in the intermediate portion 62 wherein adjacent offset elements each project to an opposite side of the intermediate portion 62. The offset elements 66 increase the rigidity of the heatsink 24 and facilitate the use of a thin generally planar element 44. Accordingly, more grooves 48 and lands 46 may be formed as a heat exchanger. Thereby increasing the surface area and the heat transfer rate.
In the illustrated embodiment, utilizing four 40 mm.×40 mm. Thermoelectric modules 22 each producing 25 watts of cooling (or 80 Btu per hour) and a door having a 1.8 R factor, a cooler storage volume 80 of 2.5 ft3 maintains a 35 to 40 degree delta (difference between ambient temperature and mean storage compartment temperature) depending on humidity.
In the illustrated embodiment, the door 30 is constructed of multiple, slightly spaced plies of plastic sheets to achieve a desired degree of insulation, it being understood that each spacing produces an R factor of approximately 0.6.
While the particular preferred embodiments have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the teaching of the disclosure. For example, additional Peltier devices may be used in any desired wiring configuration, different materials of construction, controllers and other suitable modification or changes. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as limitation. The actual scope of the disclosure is intended to be defined in the following claims when viewed in their proper perspective based on the related art.
