Device for connecting individual battery cells

Abstract

The invention relates to a device (1) for electrically connecting individual battery cells (2) of a battery module (3), wherein each of the individual battery cells (2) has two battery poles (9, 10), the device having cell connectors (8) which are each designed to electrically contact two battery poles (9, 10) of different individual battery cells (2). The invention is characterised in that an electrically insulating frame (4) is provided, in which the cell connectors (8) are each rotatably accommodated about an axis of rotation (A).

Description

[0001] Device for connecting individual battery cells

[0002] The invention relates to a device for connecting individual battery cells of a battery module with cell connectors according to the type defined in more detail in the preamble of claim 1.

[0003] The construction of battery modules from a multitude of individual battery cells, in particular prismatic individual battery cells, which are stacked to form the battery module, is known from the prior art. Each of the individual battery cells has two battery terminals, which must be connected via cell connectors according to the desired electrical wiring.

[0004] Purely as an example, reference can be made to DE 102015 204 111 A1 in this context. The structure described there is comparatively complex and requires, on the one hand, precisely fitting battery terminals in a hollow cylindrical design and, on the other hand, the appropriate cell connectors to insert them into the individual battery terminals. This results in considerable manufacturing effort, requiring strict adherence to very tight manufacturing tolerances.

[0005] For this reason, it is often common practice to use cell connectors, which are connected to the battery terminals of the individual battery cells using joining methods such as welding or soldering, or even mechanical joining methods such as crimping. While this reduces the effort required to meet the manufacturing tolerances of the individual components to a certain extent, the assembly required to connect the individual battery cells remains very complex.

[0006] Furthermore, when using correspondingly robust cell connectors, which are made, for example, from metallic components with a material thickness of 0.5 mm or more, the options for tolerance compensation are very limited. This, in turn, requires a relatively small manufacturing tolerance for the external dimensions of the individual battery cells, so that, for example, they are always in the same position relative to a base support, if possible, and the battery poles are all in the same plane. However, it is precisely here, with the housings of prismatic or round individual battery cells, especially with housings of so-called pouch cells, which are shrink-wrapped in a foil bag, that such tolerances in the manufacturing and positioning of the individual battery cells are very difficult and can therefore only be maintained at great expense in terms of time and / or money.

[0007] DE 102014 118 773 A1 describes busbar modules with cell connectors, referred to there as busbars, capable of compensating for such manufacturing tolerances between two battery cells. Overall, this results in considerable effort, as a large number of such busbar modules must be laboriously assembled.

[0008] The object of the present invention is therefore to provide an improved device for connecting individual battery cells of a battery module with cell connectors for contacting two battery poles of different individual battery cells, which enables simple and efficient production of the battery module even when the requirements for the manufacturing and positioning tolerances of the components are moderate.

[0009] According to the invention, this object is achieved by a device having the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and further developments of the device emerge from the dependent claims.

[0010] The device according to the invention for connecting individual battery cells of a battery module uses an electrically insulating, i.e. electrically non-conductive frame in which the cell connectors for at least some, preferably a majority or all of the battery terminals of the battery module to be contacted are arranged. The cell connectors themselves are rotatably accommodated in this electrically non-conductive frame. This allows several of the cell connectors to be positioned extremely easily and efficiently, together with the frame. Unlike the use of individual cell connectors that are not connected to one another, which must each be positioned individually using a handling device, for example, the combination of several of the cell connectors in the frame creates a structure in which only the frame needs to be positioned accordingly, in order to bring a large number of cell connectors into position extremely easily and efficiently.

[0011] Because the cell connectors in the device according to the invention are rotatably mounted in the frame, the design also allows for good tolerance compensation, since, for example, height tolerances in the surfaces of the individual battery poles can be very well compensated for by the rotational mobility of the cell connectors. Since the size of the battery poles in the area where the cell connectors come into contact with them is typically sufficiently large anyway, tolerance compensation in one direction, for example, in the height direction of the battery poles, can be easily implemented by the rotational mobility, while tolerance compensation in the directions transverse to this is easily possible anyway due to the dimensions of the battery poles.

[0012] The attached cell connectors can then be joined to the battery terminals easily and efficiently, preferably using laser welding processes.

[0013] According to an exceptionally advantageous development of the device according to the invention, the rotation axes are arranged approximately parallel to a plane in which the battery terminals of the individual battery cells terminate according to their predetermined arrangement. The predetermined arrangement in this sense means that the theoretical position of the surfaces of the battery terminals would be in this plane if the individual battery cells had no manufacturing or positioning tolerances. In practice, these do exhibit manufacturing or positioning tolerances in this vertical direction.An arrangement of the rotation axis in a plane perpendicular to this height direction now allows these particularly critical tolerances to be compensated for simply and efficiently by allowing the corresponding cell connectors to move around their rotation axes in the direction of the respective battery poles, in order to allow a sufficiently reliable support surface and stable connection, for example by means of a weld seam, between the cell connectors and the battery poles, largely independent of the exact position of the surface of the battery pole with respect to the plane of its theoretical position.

[0014] According to a further very advantageous embodiment, it can be provided that the axis of rotation of prismatic individual battery cells stacked in the battery module runs at an angle of 30 to 100°, preferably at an angle of approximately 90°, to the stacking direction of the individual battery cells. Such an arrangement with an angular position of 90°, and additionally preferably with a position in the plane described above, now allows, for example, a series connection of the individual battery cells in the battery module if they are stacked with alternating battery poles.If they were stacked with the battery poles aligned in the same direction, then, depending on the distance between the battery poles of one of the individual battery cells, the angle would have to be selected in the order of magnitude of, for example, 60°, in order to connect the battery poles arranged at the bottom and top ends perpendicular to the stacking direction at an angle to the stacking direction. For the special case where the distance between adjacent battery poles in the stacking direction and perpendicular to the stacking direction were the same, this angle would be 45°.

[0015] A further very advantageous embodiment of the device according to the invention further provides that the rotation axis accommodates the cell connectors in the region of their center of gravity. Such an arrangement of the rotation axis, which can consist, for example, of a pin attached to the frame protruding through a hole in the cell connector, or a pin attached to the cell connector and mounted in corresponding holes or grooves in the frame, then accommodates the cell connector in such a way that it is level when not yet placed on the battery module and thus touches both battery poles after placement if the battery poles are perfectly aligned. If tolerance compensation is required, the correspondingly protruding battery pole will push the end of the respective cell connector that comes into contact with it upwards, so that the other end adapts accordingly and contacts the adjacent battery pole.If the rotation axis is positioned near the center of gravity of the cell connectors, this occurs largely automatically when the device is placed on a battery module prepared for contacting, so no intervention is necessary. This makes assembly very efficient.

[0016] According to another very advantageous embodiment, it can further be provided that the cell connectors each have a curved shape, so that their ends, during intended use, protrude in the direction of the battery poles beyond the area of ​​their rotation axis. Such a curved or slightly curved shape in side view, which in principle could also be realized in the shape of a V, a U, or the like, allows, particularly together with the arrangement of the rotation axis in the area of ​​the center of gravity, an ideal adaptation to the position of the individual battery poles, in particular to their height, largely independent of the height tolerances of the individual battery cells.

[0017] Another very advantageous embodiment of the device according to the invention provides that the frame has two longitudinal sections, between which the axes of rotation are formed. The individual axes of rotation can thus be formed, for example, via connecting pins between the longitudinal sections, on which the cell connectors are designed to be rotatable. This then allows, for example, in the example of stacked prismatic individual battery cells, the battery poles on one side to be contacted with each other transversely to the stacking direction of the battery module.

[0018] Alternatively, according to an advantageous embodiment of the device according to the invention, the frame can also be provided with four longitudinal sections, which form two sub-frames, between each of which two longitudinal sections the axes of rotation are formed, wherein the sub-frames are connected via intermediate webs. This allows two sub-frames to be joined together to form an overall frame, which can then be used to contact all of the individual battery cells of the battery module.

[0019] To stabilize the frames or sub-frames, a very advantageous embodiment can provide for the longitudinal sections to be connected via connecting webs halfway between adjacent axes of rotation. This stabilizes the structure accordingly, as the longitudinal sections are connected to one another not only via the axes of rotation, but also via additional connecting webs. They can then be ladder-shaped, with every second rung forming either a connecting web or, offset therefrom, every second rung forming an axis of rotation. If two sub-frames are involved, these can in turn be connected via intermediate webs. This has the crucial advantage that such a frame consisting of two sub-frames is very stable in itself and that a single such frame with its two sub-frames needs to be placed on the battery module in order to make appropriate contact with the cell connectors.This significantly reduces the effort required compared to attaching many individual cell connectors that are not yet pre-assembled to one another. This enables a much shorter production time combined with more reliable and reproducible manufacturing, thus saving costs over the production time on the one hand, and costs through reduced scrap and / or rework on the other. According to another highly advantageous embodiment of the device according to the invention, the distance between the rotation axes for prismatic individual battery cells is twice the thickness of the individual battery cells in the stacking direction.The material thickness of the individual cell connectors can in particular be greater than or equal to 0.5 mm, so that due to the possibility of tolerance compensation via the rotatable bearing of the individual cell connectors, a relatively stable design of the cell connectors can be used, which accordingly enables good contact with low electrical resistance within the cell connector.

[0020] Alternatively, the frame described above can also consist of a type of flexible film into which the individual cell connectors are incorporated, for example, laminated. In this case, the above-described plug-in connection consisting of a hole and pin from the cell connector to the frame could be omitted, since possible rotational movements of the cell connectors around their axis of rotation can be achieved by slight deformation of the frame. The further described functionalities regarding the support of the cell connectors and their precise positioning by the frame are also fulfilled with such an embodiment.

[0021] As mentioned above, the cell connectors can be welded to the battery terminals for electrical contact, particularly using a laser welding process. This, along with other conceivable options for joining the cell connectors to the battery terminals, is a very simple and reliable method. Furthermore, it minimizes heat input into the individual battery cells due to the relatively small melted areas during laser welding, while still allowing for good adhesion.

[0022] Further advantageous embodiments of the device according to the invention also emerge from the exemplary embodiments which are presented in more detail below with reference to the figures.

[0023] Showing:

[0024] Fig. 1 is a schematic plan view of an embodiment of a device according to the invention; Fig. 2 is a side view of a device according to the invention arranged on individual battery cells of a cell module;

[0025] Fig. 3 is a view similar to that in Fig. 2 after connecting the cell connectors to the battery terminals;

[0026] Fig. 4 is a schematic representation of a device analogous to the representation in Fig. 1 on an exemplary battery module; and

[0027] Fig. 5 shows an alternative embodiment of the device before being placed on a battery module.

[0028] Figure 1 shows a device 1 for connecting individual battery cells 2, which are also shown in the following figures, to form a battery module 3, a partial section of which can be seen in Figures 4 and 5. The device 1 comprises a frame 4, which is constructed from two longitudinal sections 5. Connections 6, which form axes of rotation, and connecting webs 7 extend alternately between these longitudinal sections 5, ultimately resulting in a ladder-shaped structure of the frame 6. Cell connectors 8, which are rotatable about the axes of rotation A, shown with a dash-dotted line, are arranged on the connections 6 forming the axes of rotation. In the exemplary embodiment or section of this device 1 shown here, the device 1 comprises four such cell connectors 8.As an alternative to the example in Figure 1, the rotation axes A could also be designed in the form of two pins on the longitudinal sections 5 of the frame 4, which protrude into openings of the cell connectors 8. The principle could also be reversed, so that pins on the cell connectors 8 protrude into openings of the longitudinal sections 5 to form the rotation axes A. Likewise, a rotational movement of the cell connectors can be enabled via a deformable frame.

[0029] Figure 2 shows a side view of a section of this structure. One of the longitudinal rails 5 of the frame 4 can be seen, with a connecting web 7 and two connections 6 forming the axis of rotation A. Cell connectors 8, which are made of a comparatively thick material with a thickness t and can in particular have a material thickness of 0.5 mm or more, are rotatably mounted on these axes of rotation A. Each of the cell connectors 8 is designed to be rotatable in the region of its center of gravity on the axis of rotation A and is curved in order to protrude beyond the material in the region of its center of gravity at its ends in the direction pointing downwards in Figure 2. Four individual battery cells 2 of a battery module 3 are shown below this device 1.In the area of ​​each of the individual battery cells 2, one of their battery poles 9, 10 can be seen, with the battery poles 9 representing, for example, the positive battery pole and the battery poles 10 representing, for example, the negative battery pole. The aim of the desired electrical contact according to the illustration in Figure 2 is therefore a series connection in which the battery pole 9 of the individual battery cell 2 on the far left is to be connected to the battery pole 10 of the adjacent individual battery cell, and so on. The individual battery cells 2 can, as can be seen in more detail in Figures 4 and 5, be designed as prismatic individual battery cells that are stacked in a stacking direction S.The axes of rotation A now run perpendicular to this stacking direction S and lie in a plane which is parallel to the plane of the surfaces of the battery poles 9, 10, whereby in practice these can and will have a tolerance-related height offset H, which is shown here purely as an example on the two individual battery cells 2 shown on the right.

[0030] In the stacking direction S, each battery cell has a distance az from its neighboring individual battery cell, which also takes into account the possible installation of tensioning mats or adhesives between the individual cells. The distance av between the individual rotation axes A of the device 1 is twice the distance az of the individual battery cells 2 and is constant for battery modules composed of the same individual battery cells 2.

[0031] The device 1 is now lowered, as indicated by the arrow in Figure 2, onto the individual battery cells 2 or their battery poles 9, 10, which are arranged with a height offset H due to the tolerances. This lowered state is shown in Figure 3. The individual cell connectors 8 have rotated about their rotation axes A according to the rotational movement arrows shown here, in order to touch the surface of the battery poles 9, 10 of the adjacent individual battery cells 2 accordingly, despite the height offset H, which is also shown in Figure 3 using the two individual battery cells 2 shown on the right. The rotational arrangement of the individual cell connectors 8 thus made it possible to reliably and easily compensate for the tolerance-related height offset H.

[0032] As indicated by the black triangles, the actual contacting is then carried out by joining, in particular by a laser weld seam, as is already known from the prior art of the applicant for cell connectors of this type, and in particular for cell connectors shaped in this way.

[0033] In addition, the possibility of combining the cell connectors 8 in the frame 4 also offers further advantages. For example, the frame 4 shown in Figure 1, for example, can be placed simply and efficiently on the bottom row of battery poles 9, 10 transverse to the stacking direction S, as shown in Figure 4, a view from above of the battery module 3 indicated here by dashed lines, in order to contact them in the manner already described. Instead of having to position the cell connectors 8 individually, it is therefore only necessary to position the device 1 on the bottom row of battery poles 9, 10 transverse to the stacking direction S and once on the top row, offset by one battery pole accordingly. In Figure 4 and Figure 5, only some of the parts of the device 1 are again provided with reference numerals.

[0034] In order to further reduce the manufacturing effort and the susceptibility to errors, the device 1 can also combine several sub-frames into one frame 4. In the illustration in Figure 5, the battery module 3 can again be seen on the left in a dashed line, while on the right such a frame 4 of the device 1 consisting of two sub-frames 4.1 and 4.2 is shown accordingly. Each of the sub-frames 4.1, 4.2 can be designed analogously to the frame 4 already shown. Each of the sub-frames 4.1, 4.2 therefore has the connections 6 forming the axes of rotation between its longitudinal rails 5 and connecting webs 7 arranged therebetween. The two sub-frames 4.1, 4.2 are then connected to one another via intermediate webs 11, in the example in Figure 5 via three intermediate webs 11. The length of the intermediate webs 11, which extends between two of the longitudinal sections 5 of one sub-frame 4.1 and the other sub-frame 4.2, is dimensioned such that it is oriented towards the distance between the battery poles 9, 10 of each of the individual battery cells 2, so that the cell connectors 8 of one sub-frame 4.1 come to lie above the upper battery poles 9, 10 here transverse to the stacking direction S, and the cell connectors 8 of the other sub-frame 4.2 accordingly come to lie above the lower battery poles 10, 9. In order to realize the series connection mentioned as an example with a mirrored arrangement of adjacent individual battery cells 2, one sub-frame 4.1 is arranged offset from the other sub-frame 4.2 by a distance az of the individual battery cells 2 in the stacking direction S.

[0035] The frame 4 or the sub-frames 4.1 can be designed such that they consist of one of the longitudinal sections 5, to which the connections 6 and the connecting webs 7 are then applied accordingly or are already formed integrally with this longitudinal section. The connections 6 and the connecting webs 7 are preferably designed identically, so that only one of the cell connectors 8 needs to be applied to every second one, which preferably has a hole in the area of ​​its center of gravity in the side view. After the cell connectors 8 have been attached, the frame 4 can then be closed accordingly with the second longitudinal section 5, for example by the connections 6 and connecting webs 7 being pushed into corresponding openings with a form fit, being latched, glued, welded or the like to the longitudinal section 5.The intermediate webs 11 can also be designed in a comparable manner, in particular they can be designed as continuous elements, as can be seen in the illustration on the right in Figure 5, which form the connecting web 7 in one of the sub-frames 4.1 and then accordingly the connection 6 in the other sub-frame 4.2 to form the axis of rotation A, as can be seen, for example, in the middle intermediate web 11 shown on the right in Figure 5.

Claims

Patent claims Device (1) for electrically connecting individual battery cells (2) of a battery module (3), each of the individual battery cells (2) having two battery poles (9, 10), with cell connectors (8) for electrically contacting two battery poles (9, 10) of different individual battery cells (2), characterized in that an electrically insulating frame (4) is provided, in which the cell connectors (8) are each rotatably received about a rotation axis (A). Device (1) according to claim 1, characterized in that the rotation axes (A) lie parallel to a plane in which the longitudinal directions of the surfaces of the battery poles (9, 10) of the individual battery cells (2) lie according to their predetermined arrangement.Connection (1) according to claim 1 or 2, characterized in that the axes of rotation (A) of prismatic individual battery cells (2) stacked in the battery module (3) run at an angle of 30° to 100°, preferably at an angle of approximately 90°, to the stacking direction (S). Device according to claim 1, 2 or 3, characterized in that the axes of rotation (A) are arranged in the region of the center of gravity of the cell connectors (8) in their side view along the axis of rotation (A). Device (1) according to one of claims 1 to 4, characterized in that the cell connectors (8) in their side view along the axis of rotation (A) have a. have a curved shape, so that the ends of the cell connectors (8) protrude in the direction of the battery poles (9, 10) relative to the area of ​​the rotation axis (A) when used as intended. Device (1) according to one of claims 1 to 5, characterized in that the frame (4) has two longitudinal sections (5), between which the rotation axes (A) are formed. Device (1) according to one of claims 1 to 5, characterized in that the frame (4) has four longitudinal sections (5), which form two sub-frames (4.1, 4.2), wherein the axes of rotation (A) are formed between the two respective longitudinal sections (5) of the sub-frames (4.1, 4.2), and wherein the sub-frames (4.1, 4.2) are connected via intermediate webs (11). Device (1) according to claim 6 or 7, characterized in that the longitudinal sections (5) are connected via connecting webs halfway between adjacent axes of rotation (6). Device (1) according to one of claims 1 to 7, characterized in that the distance between the axes of rotation in the case of prismatic individual battery cells corresponds to twice the cell spacing (az) of the individual battery cells (2) in the stacking direction (S). Device (1) according to one of claims 1 to 9, characterized in that the cell connectors (8) have a material thickness (t) of at least 0.5 mm.

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