Thermoelectric temperature control unit

The application relates to thermoelectric temperature control units, for example for controlling the temperature of an energy storage device in a motor vehicle. An exemplary embodiment comprises a Peltier element, having a first and a second surface, wherein the second surface is substantially adjacent or opposite to the first. The first surface is connected in a thermally conductive manner to a first and/or second flow duct, through which a fluid can flow. The second surface is connected in a thermally conductive manner to a heat-producing element, wherein the first flow duct is in fluid communication at one of the ends thereof with a first header, and the second flow duct is in fluid communication at one of the ends thereof with a second header, and the first flow duct and the second flow duct are in fluid communication at the respective second ends thereof with a common reversing header.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is based upon and claims the benefit of priority from prior German Patent Application No. DE 10 2012 211 259.6, filed Jun. 29, 2012, the entire contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

A thermoelectric temperature control unit, in particular for controlling the temperature of an energy storage device in a motor vehicle, having at least one first Peltier element, which has a first surface and a second surface substantially adjacent or opposite to the first surface, wherein the first surface is connected in a thermally conductive manner to at least one first flow duct and/or one second flow duct, is advantageous.

PRIOR ART

Motor vehicles with electric additional drives or fully electric drives generally require electric energy storage devices. In order to keep these electric energy storage devices within an optimum temperature window at all times in respect of the performance thereof, these energy storage devices must be periodically cooled or heated, depending on ambient conditions.

In this context, there are demanding requirements on the homogeneity of the temperature distribution within the energy storage device in order, on the one hand, to ensure uniform power consumption and power output and, in addition, to avoid uneven aging processes due to different temperature stresses.

The cooling and heating capacity required for this purpose is generally significantly lower than the cooling and heating capacity required for controlling the temperature of a passenger compartment.

In currently known applications, the energy storage devices are either cooled by means of conditioned compartment air, by means of a coolant, the temperature of which is controlled by means of a “chiller” or a coolant circuit of the air conditioning system, or directly by means of a refrigerant.

Nowadays, the heating mode is generally provided by means of an internal electric short circuit or by means of external resistance heating elements.

Since, as already mentioned above, the required cooling capacity is generally significantly lower than in conventional systems used to control the temperature of the interior, downsizing of the components used is desirable.

In the literature, there are likewise also initial studies on the use of Peltier elements for controlling the temperature of energy storage devices. In this regard, however, there are no known solutions suitable for series production at present that provide sufficient cooling and heating capacity with an appropriate installation space requirement.

The disadvantage with the prior art is, in particular, the fact that Peltier elements generally entail a high power consumption in relation to the cooling capacity supplied, especially when the temperature differences between the hot and the cold side of the Peltier elements are relatively large.

This is to be avoided especially in the context of electric vehicle applications, which are sensitive in terms of range.

DESCRIPTION OF THE INVENTION, PROBLEM, SOLUTION AND ADVANTAGES

It is therefore the object of the present invention to provide a thermoelectric temperature control unit which allows uniform temperature distribution and uniform heat output over the surface.

The object of the present invention is achieved by a thermal temperature control unit having the features according to claim1. Advantageous developments of the present invention are described in the dependent claims.

One illustrative embodiment of the invention relates to a thermoelectric temperature control unit, in particular for controlling the temperature of an energy storage device in a motor vehicle, having at least one first Peltier element, which has a first surface and a second surface substantially adjacent or opposite to the first surface, wherein the first surface is connected in a thermally conductive manner to at least one first flow duct and/or one second flow duct, through which a first fluid can flow, and the second surface is connected in a thermally conductive manner to at least one first heat-producing element, wherein the first flow duct is in fluid communication at one of the ends thereof with a first header, and the second flow duct is in fluid communication at one of the ends thereof with a second header, and the first flow duct and the second flow duct are in fluid communication at the respective second ends thereof with a common reversing header.

In this way, the Peltier element can carry heat from one of the surfaces thereof to the other if a sufficient voltage is applied to the Peltier element. Sufficient heat transport can thus be achieved without the need to use mechanically moving parts. It is advantageous that the Peltier element is in very good thermally conductive contact both with the heat-producing element, from which it is generally supposed to remove heat, and with the flow ducts, to which the Peltier element is supposed to transfer the heat.

In an advantageous embodiment, the heat-producing element is one of the battery elements which together form the energy storage device.

It is furthermore advantageous if the first flow duct and the second flow duct run essentially parallel to one another.

It is also expedient if the first fluid in the first flow duct can flow as a countercurrent with respect to the first fluid in the second flow duct.

The countercurrent allows a particularly advantageous profile of the temperature level across the flow ducts. The fact that the fluid flows in one direction and flows back in the other direction results in different temperature levels in the first and the second flow ducts owing to the duration of contact with the heat-producing element.

Averaging the temperature level of the first and second flow ducts gives a temperature level with significantly less scatter than with an arrangement of flow ducts through all of which the flow is in the same direction.

It is furthermore to be preferred if the first surface of the Peltier elements is in thermal contact via a first plate with the first flow duct and/or the second flow duct.

Using a plate between the individual Peltier elements and the flow ducts enables better thermal connection of the Peltier elements to the flow ducts. This is advantageous particularly if the Peltier elements are wider than the individual flow ducts. The Peltier elements would otherwise project beyond the flow ducts, and a heat buildup could form in the gap between the flow ducts, with a disadvantageous effect on the efficiency of the thermoelectric temperature control unit.

The parallel alignment of the flow ducts, in particular in a common plane, makes it a particularly simple matter to connect the flow ducts to a plate in order to be able to achieve a level connecting surface for the Peltier elements that is independent of the structure of the flow ducts.

In an advantageous embodiment, the plate used can be composed of plastic or metal or ceramic. In a further advantageous embodiment, the plate used should have good thermal conduction properties.

In addition, it is expedient if the first plate has slots arranged between the first flow duct and the second flow duct.

By means of the slots, thermal bridges between the first and the second flow ducts can be avoided. However, care should be taken to ensure that the mechanical stability of the overall temperature control unit is not negatively affected by the slots in the plate. In all cases, the disadvantage which arises from any thermal bridges that are present is of secondary importance to any negative effect on mechanical stability.

It is also expedient if the common reversing header has fluid-conducting structures which carry the first fluid from the first flow duct into the second flow duct.

By means of fluid-conducting structures of this kind, it is possible to improve distribution into the first and second flow ducts.

It is furthermore advantageous if the second surface of the Peltier element is connected to a third surface of a second plate, and the fourth surface of the second plate is connected to the at least first heat-producing element.

By connecting the Peltier elements to a plate, it is possible to connect the heat-producing elements, which in one embodiment according to the invention are battery elements, to the Peltier elements in a particularly advantageous manner. Care should be taken to use a plate which has only a very low thermal resistance.

Moreover, it is expedient if the first header is thermally insulated from the second header.

This avoids a situation where an additional thermal bridge is formed between the first flow ducts and the second flow ducts.

It is also advantageous if the first header and the second header are implemented in a single component part.

Implementation in a single component part allows a particularly space-saving embodiment of the thermoelectric temperature control unit.

It is furthermore desirable if the thermoelectric temperature control unit has a plurality of first flow ducts and a plurality of second flow ducts, wherein the number of second flow ducts is preferably equal to or greater than the number of first flow ducts.

This has an advantage for the heat absorption of the two flow ducts. Owing to the tendency for a higher temperature in the second flow ducts, there is a lower driving temperature difference with respect to the Peltier elements than with the first flow ducts. This can advantageously be balanced out by having a larger number of second flow ducts than of first flow ducts.

It is also expedient if individual flow ducts or groups of flow ducts of the first flow ducts and of the second flow ducts are arranged alternately to one another.

This alternate arrangement of the flow ducts results in an advantageous distribution pattern, especially as regards temperature distribution over the first and second flow ducts.

It is furthermore advantageous if the thermoelectric temperature control unit has a plurality of Peltier elements and a plurality of heat-producing elements.

A plurality of Peltier elements allows greater heat transfer, and, as a result, the overall system has considerable advantages for commercial use.

PREFERRED EMBODIMENT OF THE INVENTION

FIG. 1shows a schematic view of a thermoelectric temperature control unit1. InFIG. 1, the thermoelectric temperature control unit1is shown in section and, since the intention is to illustrate only the principle of the thermoelectric temperature control unit1, it is not shown fully.

Arranged above the thermoelectric temperature control unit1is a plurality of battery elements5, the temperature of which the thermoelectric temperature control unit1serves to control. The thermoelectric temperature control unit1consists essentially of a plurality of Peltier elements2, which are capable of transferring heat from one of the outer surfaces thereof to the opposite outer surface through the application of a voltage. The battery elements5can thereby be either cooled or heated.

The focus of the invention is on the cooling of the battery elements5. In order to be able to dissipate the heat absorbed by the battery elements5from the thermoelectric temperature control unit1, the Peltier elements2must be in thermally conductive contact with a coolant flow, as indicated inFIG. 1by reference sign6.

For this purpose, a first surface37of the Peltier elements2is connected in a thermally conductive manner to a heat exchanger3. In this arrangement, the heat exchanger3forms an interface with the cooling circuit6and can, for example, be formed by tubes, through which there is a flow of coolant. In the illustrative embodiment shown inFIG. 1, the first surfaces37are connected to the heat exchanger3by a plate4, which is arranged as an intermediate element between the flow ducts11,12of the heat exchanger3and the Peltier elements2.

As an alternative, the thermally conductive connection can also be established directly with the heat exchanger3by applying the Peltier elements2to the flow ducts11,12of the heat exchanger without an intermediate element. The second surface38of the Peltier elements2, that opposite the first surface37, is in thermal contact with one or more heat-producing elements. InFIG. 1, the heat-producing element is formed by a plurality of battery elements5. The heat radiated by the battery elements5is transferred by the Peltier elements2to the contact points between the Peltier elements2and the cooling circuit6and is released from there to the coolant flowing in the cooling circuit6.

The quantity of heat which is released to the coolant in the cooling circuit6is then cooled by a heat exchanger7, through which a flow of external air8flows, and is released to the environment. The construction of the coolant circuit6and of those components contained therein which are outside the thermoelectric temperature control unit1is not the subject matter of the invention and is therefore not described further in detail.

The Peltier elements2are either connected directly to the battery elements5or, as shown inFIG. 1, via an intermediate medium, such as a plate30.

In this context, care should be taken to ensure that there is always a good thermally conductive connection between the Peltier elements2and the heat source or the heat sink formed by the coolant in the coolant circuit6.

FIG. 2shows a schematic view of the flow principle of the flow ducts11,12. A first fluid flows through the flow ducts11,12as well as in the coolant circuit6. The direction of flow within the first flow ducts is opposed to the direction of flow in the second flow ducts12.

In order to achieve this, the fluid, after flowing through the first flow ducts11, is deflected in a reversing header13arranged at the end of the first flow ducts11and the second flow ducts12, ensuring that the fluid then flows back through the second flow ducts12in the opposite direction of flow.

For this purpose, the first flow ducts11are supplied jointly with the fluid by a header box. There is likewise a second header box, which collects the fluid again after it has flowed through the second flow ducts and carries it out of the thermoelectric temperature control unit1. The two header boxes are not shown inFIG. 2. Further details thereof are given in the following figures.

Fluid guiding devices can be provided within the reversing header13. However, this is not essential since the primary direction of flow is fundamentally already determined by the inflow through the first flow ducts11and the outflow of the fluid through the second flow ducts12.

The use of additional fluid guiding devices can be appropriate if uneven distribution of the fluid over the flow ducts11,12occurs.

FIG. 3likewise shows a schematic view of the flow principle of the thermoelectric temperature control unit1. As inFIG. 2, only the first and second flow ducts11, and the reversing header13are shown. For the sake of clarity, the Peltier elements2and the battery elements5or additional plate elements4,30have been omitted from the illustration. This is also the case inFIGS. 2, 4 and 7.

In addition,FIG. 3now shows an inlet branch16, which is in fluid communication with an inlet header14, and an outlet branch17, which is in fluid communication with an outlet header15.

For its part, the inlet header14is in direct fluid communication with the first flow ducts11. The outlet header15is likewise in direct fluid communication with the second flow ducts12.

In the embodiment shown inFIG. 3, the outlet header15is in one plane with the reversing header13, the first flow ducts11and the second flow ducts12. The inlet header14, for its part, is offset downward out of this plane and thus lies below the outlet header15.

In this way, it is possible to achieve thermal insulation between the inlet header14and the outlet header15. This is advantageous, in particular, because thermal bridges between the fluid before it flows through the thermoelectric temperature control unit1and after flowing through the latter can thereby be avoided.

In order to ensure connection of the first flow ducts11to the inlet header14, the first flow ducts11have a kinked shape in the region of the inlet header14, said shape leading out of the plane of the other component parts and to the inlet header14.

In alternative embodiments, it is likewise conceivable to take additional thermal insulation measures between the inlet header box and the outlet header box. It is likewise conceivable to configure the arrangement of the flow ducts and of the header boxes in a single plane, but this is not essential.

It is particularly advantageous if the arrangement of the first flow ducts11and of the second flow ducts12is always in an alternating sequence. In this way, a particularly homogeneous temperature pattern can be produced across the thermoelectric temperature control unit1.

This results from the fact that the fluid in the first flow ducts11has a lower temperature level than the fluid in the second flow ducts12in the case of the cooling of the battery elements5.

In alternative embodiments, it is also conceivable, as a departure from the illustration shown in the figures, in each case to arrange a plurality of first flow ducts11as a group and a group of second flow ducts12alternately to one another. The number of adjacent first flow ducts11and second flow ducts12should be chosen according to the planned use.

FIG. 4shows a further perspective view of a thermoelectric temperature control unit1. In the version shown inFIG. 4, the inlet header22and the outlet header23are embodied in just one component part. For this purpose, the inlet box27, which consists of an element bent in a U shape, has an insert24in its interior.

This insert24is embodied in such a way that it closes off the open region of the inlet box27which runs around three side faces, giving rise to a closed component part.

This insert24is furthermore embodied in a comb-like manner and allows a division into the first flow ducts11and the second flow ducts12within the inlet box27. An aperture28, to which the inlet header box12can be directly connected, is arranged on the upper side of the inlet box27.

A plurality of outlet openings25is likewise arranged on the upper side of the inlet box27. In the fully assembled state, said openings are covered by the outlet header box23and are additionally sealed off by the latter from the environment.

The insert24limits the length of the second flow ducts12within the inlet box27to such an extent that, after flowing through the second flow ducts12, the fluid can flow only as far as the outlet openings25in the inlet box27. The insert24thus forces the fluid that has flowed through the second flow ducts12through the outlet openings25, into the outlet header box23, and, via the outlet branch21, out of the thermoelectric temperature control unit.

In addition, the insert24forms flow ducts within the inlet box27, allowing the fluid to flow directly through the inlet box27into the first flow ducts11via the inlet branch20and the inlet header box22.

The reversing header13illustrated inFIG. 4corresponds essentially to the reversing header13already illustrated in the previous figures.

FIG. 5shows an exploded view of the inlet box27, which was shown only schematically inFIG. 4. Here, it is possible to see, in particular, the insert24, which controls the distribution of the fluid into the first flow ducts11and the second flow ducts12.

InFIG. 5, the inlet box27is formed by a component part bent in a U shape. The fluid flows through the inlet branch20and through the insert24which seals off the inlet box27from the outside. Via the inlet header22, which is here provided as an embossed feature in the inlet box27, the fluid can flow into the aperture18of the insert24and, from there, it can flow into the four longer apertures19via the insert24. This is made possible by the inlet header22, which is arranged in the inlet box27in such a way that the fluid can flow over the insert24in the region of the longer apertures19, which are in fluid communication with the first flow ducts11.

It is not possible for the fluid to flow into the three shorter apertures29, which are in direct fluid communication with the second flow ducts12, since the path to these three apertures for the fluid is limited or blocked by the arrangement of the inlet header22.

After flowing through the first flow ducts11, being deflected in the reversing header13and flowing back through the second flow ducts12, none of which is illustrated inFIG. 5, the fluid reaches the three shorter apertures29of the insert24. From there, the fluid flows via the apertures25and the top-mounted perforated plate26into the header box23, which is mounted from the outside on the inlet box27, and, from said header box23, flows via the outlet branch21out of the thermoelectric temperature control unit1.

The embodiment, shown here inFIG. 5, of such an inlet box27is merely one illustrative embodiment and, in practice, can be achieved by many other arrangements of the inlet and outlet header boxes relative to one another. Apart from embodiment of the inlet and outlet header boxes in a single component part, the arrangement of individual inlet boxes and outlet boxes on the thermoelectric temperature control unit is, of course, furthermore also conceivable.

FIG. 6shows one possible embodiment of the connection of the Peltier elements2in the direction of the battery elements5. Apart from the connection, as already indicated in the preceding figures, using a plate30, which is then, in turn, connected to the battery elements5, it may also be necessary to introduce additional reinforcing measures in order, for example, to prevent deformation of the thermoelectric temperature control unit1due to thermal stresses.

The structure illustrated inFIG. 6is suitable for this purpose. In a layered structure, there is first a plate30, which is subsequently connected directly to the battery elements5on its upper side. Arranged below this is a frame31, which has apertures corresponding to the size and arrangement of the Peltier elements2. Arranged below this frame31is a lower plate32, which likewise has apertures34, through which the Peltier elements2can be inserted. This layered structure is shown in the left-hand part ofFIG. 6. An assembled module comprising the component parts on the left is shown in the right-hand part ofFIG. 6.

Here, the Peltier elements2are inserted through the lower plate32, and the frame31is placed on the lower plate32. Plate30forms the upper end.

It should be emphasized, in particular, that the second surface38of the Peltier elements2is in direct thermally conductive contact with the upper plate30. One or more heat-producing elements can then be connected to plate30. It should furthermore be mentioned that an air gap36must always be maintained between the lower plate32and the connection of the Peltier elements2to the flow ducts11,12, which are represented by the block35. This air gap36serves to provide thermal insulation of the hot side of the Peltier elements2from the cold side thereof. The thermal connection of the Peltier elements2to the cooling circuit is accomplished by means of the first surface37thereof.

This structure for increasing the rigidity of the thermoelectric temperature control unit is also to be regarded as illustrative and can likewise be formed by other means, such as a component part cast in one piece, which can include the upper plate30, a frame31and/or the lower plate32.

FIG. 7likewise once again shows a schematic illustration of the flow through the thermoelectric temperature control unit1. In addition to the structure already shown inFIGS. 2 and 3, the battery elements40are now indicated here. These are arranged transversely across the first flow ducts11and the second flow ducts12.

In the first of the battery elements40, a first qualitative temperature variation is indicated by the curve42, said variation arising from the different temperatures of the first flow ducts11and of the second flow ducts12in the lower region of the battery elements40, that facing the flow ducts11,12.

It can be seen that the quality temperature variation42is highly dependent on whether a first flow duct11or a second flow duct12runs under the battery element40. This is attributable to the different temperatures of the fluid in the flow ducts11,12.

With increasing distance within the battery element40from the flow ducts11,12, this qualitative temperature variation flattens out to a greater and greater extent, however, with the result that the qualitative temperature variation41shown is established in the upper region of the battery element40, showing a largely homogeneous temperature distribution across the width of the battery elements40.

This is advantageous, in particular because the critical or maximum temperatures occur in the upper regions of the battery elements5, i.e. those further away from the flow ducts11,12, in the case of battery cooling.