Method for bonding a heat-active unit to a heat-conducting plate

Abstract

Method for bonding a heat-active unit (1), in particular a battery cell, to a heat-conducting plate (3), characterized in that a carrier material (2) is fastened to the heat-conducting plate (3) by means of a pre-bond, adhesive (6) is introduced into the carrier material (2), and the heat-active unit (1) and the heat-conducting plate (3) are brought together, wherein the carrier material (2) is located between the heat-conducting plate (3) and the heat-active unit (1).

Description

[0001] The invention relates to a method for bonding a heat-active unit to a heat-conducting plate according to the preamble of claim 1. The invention also relates to an associated bond, an arrangement with such a bond and a motor vehicle.

[0002] For use in high-voltage cells, battery cells are assembled into modules and installed in the battery housing. Due to the heat generated during operation, the battery cells must be cooled. For this purpose, the battery cells are thermally coupled to a cooler. The battery cell bases are bonded with a heat-conducting plate. A paste-like material is used to compensate for tolerances.

[0003] For bonding, an adhesive is applied to the heat-conducting plate. The adhesive is applied in beads, i.e., individual strands, to the heat-conducting plate. The heat-conducting plate is then pressed onto the battery cells combined to form a module.

[0004] The disadvantage is that the application is inaccurate, especially at the beginning and end of the beads, meaning that too much or too little adhesive can be applied. Applying too much adhesive can drip off and lead to contamination during production. Applying too little adhesive can impair the thermal coupling between the battery cells and the heat-conducting plate or reduce the stability of the bond.

[0005] Additives in the adhesive that improve the thermal conduction of the adhesive attack the dispensing heads used to apply the beads.

[0006] To prevent the adhesive from dripping, the adhesive has a relatively high viscosity. This requires high pressing forces and impairs the adhesive's distribution.

[0007] DE 10 2009 052 508 A1 discloses a method for bonding a heat-active unit to a heat-conducting element. Adhesive is introduced into a carrier material, and the heat-active unit and the heat-conducting element are brought together, with the carrier material located between the heat-conducting element and the heat-active unit.

[0008] Nonwoven materials containing biodegradable copolymers are known from DE 696 36 485 T2.

[0009] From DE 10 2014 203 765 A1 a method for producing an assembly comprising an energy storage module and a cooling element is known.

[0010] The object of the invention is to reduce, if not completely avoid, the aforementioned disadvantages.

[0011] The solution to this problem is found in particular in the independent claims. The dependent claims specify advantageous further developments. Further details can be found in the description.

[0012] A method for bonding a thermally active unit, in particular a battery cell, to a heat-conducting plate is proposed. Although a plurality of thermally active units are typically bonded to the heat-conducting plate, the invention is also suitable for bonding a single thermally active unit.

[0013] A heat-active unit is defined as any component to which heat is to be added or removed, thus requiring good heat conduction to a heat-conducting plate. Typically, these are components that need to be cooled, i.e., heat-dissipating units. The main application is the battery cells described above.

[0014] The method is characterized in that a carrier material is attached to the heat conducting plate with a pre-adhesive bond, adhesive is introduced into the carrier material and the heat-active unit and the heat conducting plate are brought together, whereby the carrier material is located between the heat conducting plate and the heat-active unit.

[0015] The adhesive can be applied to the substrate in a variety of ways. The advantage is that the substrate can absorb the adhesive and ensure even distribution. This ensures that there is enough adhesive to achieve a good bond, while simultaneously preventing excess adhesive from dripping off. Because the substrate binds the adhesive, a relatively liquid adhesive can also be used. This, in turn, simplifies the application of the adhesive.

[0016] The adhesive, heat-activated unit, and heat-conducting plate can be pressed together. However, a high degree of force is generally not required.

[0017] In one embodiment, the heat-conducting element is a heat-conducting plate or is part of a cooler. It is very common, as in the prior art described above, to use heat-conducting plates. These are connected to a cooler, i.e., thermally coupled to it, so that heat can be dissipated. However, it is also possible for the heat-conducting element to be part of the cooler. For example, the cooler can be formed by a plate through which coolant flows. If the heat-active units are then glued to the heat-conducting element, the side of the cooler facing the heat-active units forms a heat-conducting element.

[0018] Even if the heat-conducting element is designed as a separate component, it doesn't necessarily have to be a heat-conducting plate. Another material with good heat conduction, such as ceramic, can also be considered.

[0019] In one embodiment, the adhesive is applied by immersing the carrier material in a bath containing adhesive. This allows for a simple, very even application of the adhesive. The carrier material absorbs a defined amount of adhesive, which depends on the adhesive and the carrier material. Thus, a suitable selection of adhesive and carrier material ensures that, on the one hand, a good bond is achieved and, on the other hand, no excess adhesive drips off. In addition to the disadvantages of dripping described above, it is also important to remember that excess adhesive leads to unnecessary material consumption, which should be avoided for both ecological and economic reasons.

[0020] In one embodiment, the carrier material is continuously guided through the adhesive bath. For example, the carrier material can be unrolled from a roll and pulled through the adhesive bath. The carrier material can then be cut to size. It is usually advisable for the carrier material to be the same size as the heat-conducting plate, but this is not mandatory. It is also possible for the heat-conducting plate not to be fully covered with carrier material, although this is usually advisable. The carrier material can also be tailored to the size of the heat-active unit.

[0021] It is also possible to first glue the carrier material onto the heat conducting sheet, for example with a small amount of adhesive, and then to immerse the sheet with the glued carrier material into the adhesive bath.

[0022] In one embodiment, the adhesive is introduced into the carrier material by spraying it with adhesive. This, of course, assumes that the adhesive does not have an excessive viscosity. As explained, this is easily possible when using a carrier material. Spraying can be achieved by moving the carrier material past a suitable spray device at a suitable speed.

[0023] An array of spray heads can serve as the spraying device. Maintaining a suitable and defined adhesive pressure will spray a defined rate of adhesive. Together with the selection of a suitable speed at which the carrier material is moved past the spraying device, the desired amount of carrier material can be applied. Of course, the spraying device can also be moved.

[0024] Spray heads are just one example; other spraying devices are also conceivable.

[0025] In one embodiment, high thermal conductivity is taken into account when selecting the adhesive. Of course, this is not about the thermal conductivity of the adhesive itself, but rather the thermal conductivity of the bond. First of all, the thermal conductivity of the cured adhesive must be considered if a curing adhesive is used, as is usually the case.

[0026] Furthermore, the thermal coupling of the adhesive to the heat-active element and the heat-conducting plate must also be considered. For example, if an adhesive with inherently high thermal conductivity were used that was not fully bonded to the heat-active unit, the overall heat conduction from the heat-active unit to the heat-conducting plate could be poorer than with an adhesive with inherently lower thermal conductivity but better coupling to the heat-active unit. Of course, with most adhesives, the bond to the parts to be bonded is already good enough to achieve a strong bond.

[0027] Of course, an adhesive with high thermal conductivity can also be achieved by adding additives to a known adhesive that improve thermal conductivity. However, the above considerations must still be observed in this case.

[0028] In one embodiment, the carrier material is made of nonwoven fabric, particularly a volume nonwoven, such as that currently marketed by Sandler, among others. This is made of 100% polyester and has a 1 cm thickness and a basis weight of approximately 120 g / m². 2 . Currently, this fleece is used for the interior of bedspreads, play mats, sleeping bags, anoraks, and the like.

[0029] Another particularly suitable nonwoven is a separation fleece. This is a water-permeable geotextile made of mechanically bonded nonwoven fabric. It can be made of 100% polypropylene. It has been widely used in horticulture, landscaping, and riding arena construction for separation, stabilization, and protection. This air- and water-permeable separation fleece has proven itself as a separation layer for ground grids, ground honeycombs, gravel honeycombs, gravel grids, paddock slabs, and paddock grids. It has a known basis weight of 110 g / m².

[0030] Nonwoven fabric is easy to process and is well-suited for absorbing adhesives, as well as other liquids. Nonwoven fabric is often inexpensive and lightweight. Weight plays a particularly important role in automotive applications, such as bonding battery cells to a heat-conducting element, as any additional weight leads to increased energy consumption during vehicle operation.

[0031] Also claimed is an adhesive bond between a heat-active unit, in particular a battery cell, and a heat-conducting plate. The bond is characterized by a carrier material, into which adhesive is incorporated, arranged between the heat-active unit and the heat-conducting plate.

[0032] To avoid repetition, reference is made to the above explanations of the corresponding procedure.

[0033] In one embodiment, the bond is produced using a method described above.

[0034] An arrangement of a heat-activated unit with the described bonding is also to be protected. Likewise, a motor vehicle with such a bonding or an arrangement of heat-activated units is to be protected.

[0035] Further details, features, and advantages of the invention will become apparent from the following description and the accompanying figures. They show: Fig. 1a several battery cells which are to be glued to a heat-conducting element formed by a heat-conducting plate using a carrier material into which adhesive is incorporated, Fig. 1b an alternative to Fig. 1a, where the heat-conducting element is part of a cooler. Fig. 2 a structure for pulling carrier material through an adhesive bath and thus introducing adhesive, Fig. 3a and Fig. 3b a structure for introducing adhesive from an adhesive bath into carrier material that is attached to a heat conducting plate.

[0036] In Fig. 1a, several battery cells 1 can be seen. The battery cells 1 are heat-active units, as they emit heat during charging and operation. They are therefore heat-emitting units. In the Fig. 1a below is a fleece 2 serving as a carrier material. In the fleece 2 is Fig. 1a, an adhesive 6 is applied. A heat-conducting plate 3 is connected to the fleece 2. A cooling system 4 is located on the side of the heat-conducting plate 3 facing away from the fleece 2.

[0037] When the battery cells 1 are pressed against the heat-conducting plate 3, a bond is created due to the adhesive 6 incorporated into the fleece 2. This ensures good heat conduction from the battery cells 1 via the fleece 2, into which the adhesive 6 is incorporated, to the heat-conducting plate 3.

[0038] From the heat-conducting plate 3, the heat is dissipated by the cooling system 4. The cooling system can be a coiled tube attached to the heat-conducting plate 3. Since the heat conduction in the heat-conducting plate 3 is functionally good, it is sufficient for the coiled tube to have only a manageable contact area with the heat-conducting plate 3.

[0039] Fig. 1b differs from Fig. 1a in that there is no heat-conducting plate. Rather, the heat-conducting element is a flat part of the cooler 4.

[0040] Before the Fig. 1a and Fig. 1b, it is necessary to apply the adhesive 6 into the fleece 2. For this purpose, a Fig. 2 is provided. The adhesive container 5 has an adhesive tray filled with the adhesive 6, forming an adhesive bath 7.

[0041] The fleece 2 is guided through the adhesive bath 7 filled with adhesive 6. When viewing Fig. 2 this is done from left to right.

[0042] The fleece 2 is then cut to the size of the heat conducting plate 3. This should Fig. 2 is indicated by the heat-conducting plate 3 being shown. Cutting takes place at the cutting line 8 so that the fleece 2 reaches the length of the heat-conducting plate 3. The width of the fleece 2 is correctly selected in advance. The fleece 2 can be unrolled from a roll. In this way, series production can be achieved easily.

[0043] Fig. 3a and Fig. 3b show an alternative to Fig. 2. It can be seen in Fig. 3a again shows the adhesive container 5, which contains the adhesive tray filled with the adhesive 6, forming an adhesive bath 7. Above, the heat-conducting plate 3, to which the fleece 2 is attached, can be seen. The fleece 2 is attached to the heat-conducting plate 3 with a pre-bond (not shown). This pre-bond can be very simple, as its sole purpose is to lightly adhere the fleece 2.

[0044] As in Fig. 3b, the fleece 2, which is attached to the heat conducting plate 3 by means of pre-gluing, is immersed in the adhesive bath 7, so that the adhesive 6 is introduced into the fleece 2. As in Fig. 3b, this is preferably done in such a way that only the fleece 2 and the side of the heat conducting plate 3 on which the fleece 2 is located come into contact with the adhesive 6. This prevents contamination. Fig. 3a and Fig. The method shown in Figure 3b is also suitable for the Fig. 1b shows a variant without heat conducting plate 3, although it must be a cooler 4 that is correspondingly easy to handle.

[0045] The fleece 2, into which the adhesive 6 is applied as in Fig. 2 or Fig. 3 can then be used for the purposes set out in Fig. 1a or Fig. The bonding shown in 1b can be used.

[0046] This allows a compact and weight-saving energy storage device to be installed in a motor vehicle. List of reference symbols 1 heat-active unit 2 Carrier material, fleece 3 heat conducting plate 4 Cooling 5 glue containers 6 glue 7 Glue bath 8 Cutting line

Claims

[1] Method for bonding a heat-active unit (1), in particular a battery cell, to a heat-conducting plate (3), characterized by that a carrier material (2) is attached to the heat conducting plate (3) with a pre-adhesive bond, adhesive (6) is introduced into the carrier material (2) and the heat-active unit (1) and the heat conducting plate (3) are brought together, wherein the carrier material (2) is located between the heat conducting plate (3) and the heat-active unit (1). [2] Method according to claim 1, characterized by that the heat conducting plate (3) is a heat conducting element or the heat conducting element is part of a cooler (4). [3] Method according to claim 1 or 2, characterized by that the introduction of adhesive (6) is carried out by immersing the carrier material (2) in an adhesive bath (7) containing adhesive (6). [4] Method according to one of claims 1 or 2, characterized by that the carrier material (2) is continuously guided through an adhesive bath (7). [5] Method according to one of claims 1 or 2, characterized by that the adhesive (6) is introduced into the carrier material (2) by spraying the carrier material (2) with the adhesive (6). [6] Method according to one of the preceding claims, characterized by that when selecting the adhesive (6) attention is paid to high thermal conductivity. [7] Method according to one of the preceding claims, characterized by that the carrier material (2) is selected from nonwoven fabric (2), wherein in particular a nonwoven fabric (2) suitable as a volume nonwoven fabric or as a separating nonwoven fabric is selected. [8] Bonding between a heat-active unit (1), in particular a battery cell, and a heat-conducting plate (3), characterized by that a carrier material (2), into which adhesive (6) is introduced, is arranged between the heat-active unit (1) and the heat-conducting plate (3). [9] Bonding according to the preceding claim, characterized bythat the bond is produced by a method according to one of claims 1 to 7. [10] Arrangement of heat-active units (1) and a heat-conducting plate (3) with an adhesive bond according to one of claims 8 or 9. [11] Motor vehicle with an adhesive bond according to one of claims 8 or 9 or an arrangement of heat-active units (1) according to claim 10.

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