Patent Application
20250093080
The present invention relates to tempering modules and tempering chambers with Peltier elements.
A Peltier element is an electronic component that, when an electric current passes through it, develops different temperatures at the contact surfaces of two conductors (the so-called Peltier effect). Thus, when an electric current passes through the element, the Peltier element behaves like a heat pump, with one side of the element heating up at the expense of the other side, which cools down. The side that heats up is called the hot side and the side that cools down is called the cold side. When the polarity of the electric current is reversed, the sides are swapped and the side that was originally heated cools and the side that was originally cooled heats. For the purposes of this description, these sides are referred to as a first side and a second side, and depending on the polarity of the electric current, this means the hot side and the cold side, or the cold side and the hot side.
For efficient heat transfer, heatsinks are mounted on the cold and hot sides of the Peltier elements. The simplest design of a heat pump based on Peltier elements is one where one Peltier element is clamped by screws between a heated heatsink and a cooled heatsink by a force defined by the Peltier element manufacturer. For the purposes of this description, these heatsinks are referred to as a first heatsink and a second heatsink, and depending on the polarity of the electric current, this means the heated heatsink and cooled heatsink, or the cooled heatsink and heated heatsink. For the purposes of this description, a heat pump based on a Peltier element means a tempering module.
Sometimes a spacer made of a thermally conductive material is inserted between the Peltier element and the cooled heatsink or heated heatsink. The spacer increases the distance between the cooled heatsink and the heated heatsink and allows the gap to be filled with a larger layer of thermal insulation, thereby reducing unwanted heat exchange between the cooled and heated heatsink. In order to maximize the heat transfer between the Peltier element, the heated heatsink, the spacer and the cooled heatsink, a thermally conductive paste is applied to their contact surfaces. To increase the efficiency of heat transfer, both heatsinks are flushed with a liquid medium, usually air.
For a proper function and long life of the Peltier element, all surfaces in contact with the Peltier element must be manufactured to the required flatness tolerance specified by the Peltier element manufacturer.
The problem arises when the tempering module contains more than one Peltier element, and at the same time contains only one heated heatsink and only one cooled heatsink. As the electric current passes through the Peltier elements, the heated heatsink starts to lengthen, and the cooled heatsink shortens due to thermal expansion. As a result, the tempering module starts to bend, and this changes the flatness of some of the contact surfaces that are in contact with the Peltier elements. This can result in failure of the Peltier elements over time.
The US patent application US2005126184 A1 discloses a tempering module comprising two arrays of N and P thermoelectric semiconductor elements, wherein each element has a first (cold) side and a second (hot) side. Said at least two arrays of elements are oriented with their first (cold) side so as to be in thermal contact with a common shared cold heatsink, and each array of elements is oriented with its second (hot) side so as to be in thermal contact with an individual array of hot heatsinks, further connected to electrical terminals. The N and P thermoelectric semiconductor elements form an array of elements electrically connected by conductive connector tabs of the cold heatsink and conductive tab-like base ends of the hot heatsinks. Owing to this electric connection, the whole array of elements is interpreted as one Peltier element. Disadvantageously, the cold heatsink and the individual array of hot heatsinks cannot be swapped because the individual array of hot heatsinks is electrically connected to the array of elements and moisture and frost would accumulate on such a hypothetical individual array of cold heatsinks, thus increasing the risk of short-circuiting the whole module.
The European patent EP 2891176 B1 discloses a tempering module comprising at least two thermoelectric modules, wherein each thermoelectric module has a first (hot) side and a second (cold) side. Said at least two thermoelectric modules are oriented with their first (hot) side so as to be in thermal contact with a common shared hot heatsink. Moreover, at least two, but not each thermoelectric module is oriented with its second side so as to be in thermal contact with an individual cold heatsink.
The U.S. Pat. No. 6,463,743 B1 discloses a tempering module comprising at least two thermoelectric cooler devices, wherein each thermoelectric cooler device has a first (hot) side and a second (cold) side. Said at least two thermoelectric cooler devices are oriented with their first (hot) side so as to be in thermal contact with a common shared hot heatsink.
The U.S. Pat. No. 5,315,830 A1 discloses a similar modular thermoelectric assembly including a thermoelectric device with a hot sink and a cold sink.
Consequently and with respect to known prior art, there is a need in the prior art to provide a tempering module with Peltier elements with longer lifetime and lower failure rate.
The object of the invention is to provide a tempering module with Peltier elements that maintains the flatness of the contact surfaces resulting from thermal expansion, thereby extending its lifetime and reducing failure rate.
The object is achieved in a first aspect of the present invention by a tempering module comprising at least two Peltier elements, wherein each Peltier element has a first side and a second side, and wherein said at least two Peltier elements are oriented with their first side so as to be in thermal contact with a common shared first heatsink suitable to be heated (i. e. a common shared hot heatsink).
The underlying idea of the tempering module according to the present invention is that each Peltier element is oriented with its second side so as to be in thermal contact with an individual second heatsink suitable to be cooled (i. e. an individual cold heatsink).
According to the present invention, the first side is the hot side, the second side is the cold side, the first heatsink is the heated heatsink, and the second heatsink is the cooled heatsink, and these terms are used interchangeably below, although one skilled in the art understands that when the polarity of the electric current is reversed, opposite definitions apply.
Thus, the tempering module according to the present invention comprises just as many cooled heatsinks as it comprises Peltier elements. Owing to this structure, the passage of electric current due to heating of the heated heatsink results only in its linear extension, whereby the desired flatness of the surfaces in contact with the Peltier elements is not affected. Even in the case of reversal of the polarity of the electric current, when the originally heated heatsink starts to cool and the originally cooled heatsinks start to heat, there is no bending of the tempering module, but only its linear shortening.
This structure also allows easy removal of the cooled heatsinks. This makes it possible, e.g. in the event of a tempering module failure, to replace only the tempering module without the cooled heatsinks, to which the original cooled heatsinks from the failed tempering module are fitted, saving production costs.
A further advantage of this invention is that other cooled heatsinks with different cooling fin direction can be mounted on the tempering module with unmounted cooled heatsinks, as it is the most advantageous for the air flow and positioning of the tempering module.
A spacer may be arranged between the second side of each Peltier element and each corresponding individual second heatsink to allow thermal contact between the Peltier element and the second heatsink in order to increase the distance between the cooled heatsink and the heated heatsink and to create a gap to be filled with a larger layer of thermal insulation, thereby reducing unwanted thermal exchange between the cooled and heated heatsink.
The first heatsink and the second heatsink can be attached to the spacer. The first heatsink may be secured to the spacer by means of first screws, preferably provided with a resilient member (e.g. a disc spring), a steel washer and a thermal insulating member (e.g. a thermal insulating pad) to limit heat transfer between the first heatsink and the spacer. The second heatsink may be attached to the spacer by second bolts, preferably provided with a resilient element (e.g. a resilient washer).
The first and second sides of each Peltier element, as well as both sides of the first and each second heatsinks in thermal contact with the corresponding Peltier element, may be coated with a layer of thermally conductive paste for as efficient heat transfer as possible.
The first and/or second heatsink may be formed as a finned air heatsink. The fins of the first heatsink may be oriented parallel to the fins of the second heatsink or perpendicular to the fins of the second heatsink.
Thermal insulation can be placed between the heated heatsink and the cooled heatsinks.
The object is achieved in the second aspect of the present invention by a tempering chamber comprising a wall with a mounted tempering module as described above. On the outer side of said wall, the first heatsink is arranged on which a first fan is arranged for pushing air into the first heatsink in a substantially perpendicular direction to the plane of the first side of the Peltier element. At least two second heatsinks are arranged on the inner side of said wall. A second fan is further arranged on the inner side of said wall for pushing air into the second heatsinks in a direction substantially parallel to the plane of the second side of the Peltier element, preferably drawing air through an opening in a cover plate.
In this arrangement, the cooled heatsinks are flushed with air from the side of the cooled heatsink through the gaps between the fins. In this way, one second fan arranged in this way can provide air flushing to one or more cooled heatsinks which are arranged on one or more tempering modules. A further advantage of the second fan positioned in this way is its height space saving compared to a second fan positioned from above on the cooled heatsink.
At least one flow rectifier may be arranged on the inside of said wall to increase the efficiency of flushing of the cooled heatsinks.
The cooled heatsinks and the second fan can be located in the space between the tempering chamber and a cover plate.
A first example embodiment is a tempering module according to
A second example embodiment is a tempering chamber 13 according to
The above-described tempering module can be used for cooling and/or heating various instrument chambers, e.g. laboratory incubators or storage and test cabinets.
| Number | Date | Country | Kind |
|---|---|---|---|
| 23198672 | Sep 2023 | EP | regional |
