DEVICE FOR CONNECTING SEVERAL BATTERY CELLS ARRANGED PARALLEL TO EACH OTHER WITH RESPECT TO A JOINTING AXIS

Description

Technical area

[0001] The invention relates to a device for connecting in parallel several battery cells arranged parallel to one another with respect to a joining axis, with a contact plate having individual openings. State of the art

[0002] Devices for connecting battery cells in parallel are known from the prior art (EP3096372A1). In these devices, individual battery cells arranged parallel with respect to a joining axis are gripped by contact springs under prestress on the casing side. To connect the individual battery cells in parallel, the contact springs are firmly bonded to a contact plate. Although this detachable, force-fit connection between the battery cells and the contact springs offers the advantage of simple assembly and the replaceability of defective battery cells, it nevertheless has the disadvantage that the clamping forces required for secure electrical and mechanical contact between the battery cells complicate the assembly process, as joining the battery cells into the contact springs can lead to damage to the battery casing and / or the oxidation-inhibiting coating of the contact springs.This results in design limitations regarding the possible battery cell diameters and thus the usable power density, particularly when the battery cells and thus the contact springs are exposed to mechanical stresses such as vibrations. With the typical sharp-edged design of the contact blades, this leads to gradual damage to the battery cell casing and / or the oxidation-inhibiting coating of the contact springs. Furthermore, the varying contact surfaces between the contact blades and the battery cell casing result in variable contact resistance, resulting in unfavorable electrical operating conditions. For this reason, bonded connections between the contact springs and the battery cells are typically preferred.

[0003] In order to achieve a bonded connection even at hard-to-reach contact points, it has already been proposed (US6120564, EP2007833442) to provide welding points on the contact springs, which enable a bonded connection when a sufficiently high current is applied. However, the obvious disadvantage of this is that, in addition to the assembly limitations and the inability to replace defective battery cells, the currents and temperatures occurring during welding can lead to damage to the battery cells. A device for connecting several battery cells in parallel, arranged parallel to each other with respect to a joining axis, is known from CN101719540 A. Description of the invention

[0004] The invention is therefore based on the object of designing a device of the type described above in such a way that a reliable and yet detachable parallel connection of individual battery cells under periodic mechanical loads is made possible, regardless of their diameter and their relative position to the contact plate, whereby a simple assembly process can be maintained and a more structurally flexible serial connection of the battery cells can be made possible.

[0005] The invention achieves this objective in that each aperture is configured to enclose the battery cells on the casing side and has at least one contact tongue projecting into the aperture with a contact body in the shape of a cut ovoid projecting from the contact tongue on the aperture side. In contrast to a contact spring known from the prior art, which would have an undetermined contact area with the battery cell enclosed by the aperture depending on the relative position, the inventive provision of a contact body in the shape of a cut ovoid, preferably in the shape of a hemisphere, predetermines the contact area between the contact spring and the casing, resulting in a defined contact resistance between the contact body or contact spring and the battery cell. This contact resistance is largely constant even in the event of mechanical deformation of the device due to vibrations.Furthermore, the convex surface of the contact bodies prevents surface damage, especially since the contact bodies separate the sharp-edged contact prongs from the respective surface coating of the battery cells. The embodiment of the invention offers the further advantage that the contact plate can be arranged at any position along the joining and longitudinal axes of the battery cells, thus opening up greater design options with regard to the serial connection of the individual battery cells. In a production-efficient embodiment, the contact prongs can be sections of the contact plate bent in the direction of the joining axis of the battery cells. This means that, for better electrical conductivity of the device, the contact plate and contact prongs are formed from a single piece of metal.

[0006] To improve electrical contact while simultaneously simplifying manufacturing conditions, it is further proposed to press the contact body out of the contact tongues. This allows the contact bodies to be manufactured in a single work step, whereby the rounded surface can be achieved without separate post-processing to avoid surface damage. To reduce the foreign layer resistance, the contact bodies can be provided with an oxidation-inhibiting coating. In a particularly advantageous embodiment of the invention, such a coating can be produced by providing the contact tongues with a coating thickness that is sufficient for a person skilled in the art before the contact bodies are pressed, so that after forming, the contact body surfaces protruding into the openings have a continuous oxidation-inhibiting coating.Nickel or gold can be used as coatings to protect against oxidation and reduce the resistance of the foreign layer.

[0007] Since power-to-weight ratios and energy densities play a particularly important role in vehicle construction, it is proposed that the circular openings in the contact sheet be arranged according to a closest circular packing, forming gussets between every three openings. Those skilled in the art will understand that a closest circular packing of openings within the meaning of the invention requires the retention of a connecting web between the individual battery cells or openings, the width of which must be adapted to the material properties and the required mechanical stability. According to the proposed design, the gussets created between every three openings result in a reinforced contact sheet section that can be used to introduce clamping forces into the contact sheet and, due to its structural strength, is particularly suitable for positioning the contact tongues.This also allows the mechanical preload and position of the contact tongues to be adjusted depending on the battery type used, since the contact point between the contact tongue and the conductor plate can be selected more freely.

[0008] To clamp the battery cells to the contact plate in a force-fitting and symmetrical manner, at least two, preferably at least three, circumferentially equidistant contact tongues can be provided per aperture. This increases the stabilizing clamping force on the battery, the symmetrical force connection reduces the mechanical stress between the battery modules and the contact plate, and enables a force-fitting mounting even in the event of damage to individual contact tongues. A further resulting effect is a more durable electrical connection between the battery cell casing and the contact plate, since a continuous electrical connection can be created here, particularly in the event of mechanical damage to a contact tongue.

[0009] To achieve a particularly favorable force introduction of the clamping forces into the contact plate, it is proposed that each contact tongue of an opening surrounded by six openings defines a gusset, which is also defined by a contact tongue of two surrounding openings. This arrangement stiffens the device in the direction of the joining axis of the battery modules, i.e., essentially orthogonal to the plane of the parallel plate. In addition to improved electrical conduction properties, the increased number of contact tongues per opening also increases the mechanical stability of the arrangement as a synergistic effect, especially since the forces of the contact tongues introduced into the contact plate section of a gusset cancel each other out vectorially.It will be understood by those skilled in the art that this pattern cannot be continued arbitrarily in a contact sheet, so that the openings in edge regions that are not surrounded by six openings no longer have to meet the above characteristics. A particularly material-saving and production-efficient embodiment of the device according to the invention results if exactly three contact tongues are provided per opening, whereby three contact tongues are adjacent to every second gusset, while the first gussets remain free. Such a sequential pattern can also be created in a particularly simple manner by parallel displacement of a generating opening with three contact springs in the contact sheet plane. Depending on requirements and application, the contact sheet can be designed to be more or less elastic or rigid with respect to bending and torsional stresses due to the number of contact tongues per opening.

[0010] To further improve the stability of the device according to the invention, it is proposed that the edge region of the contact plate is formed at least five times wider than the narrowest point between two openings. Brief description of the invention

[0011] The drawing shows an example of the subject matter of the invention. Fig. 1 is a perspective view of the device according to the invention, Fig. 2 is a plan view of the device according to the invention on a larger scale and Fig. 3 is a section along the line III-III of Fig. 2 on an even larger scale with suggested battery cells inserted. Ways to implement the invention

[0012] A device according to the invention comprises a contact plate 1. Battery cells 2 can be mounted in openings 3 in the contact plate 1 and connected in a force-fitting and parallel electrically conductive manner via contact tongues 4, which have contact bodies 5.

[0013] The contact bodies 5 are designed such that under periodic mechanical loading and changes in the relative position between contact sheet 1 and battery cell 2, the contact surface between contact body 5 and battery cell 2 remains largely constant, which is achieved according to the invention by designing the contact bodies 5 as cut ovoids, preferably as hemispheres.

[0014] The openings 3 of the contact sheet 1 are arranged according to a closest circular packing. Together with the inventive arrangement of the contact tongues 4, this results in gussets 6, 7 located between each three openings 3. In the case of three contact tongues 4 per opening 3, which are arranged circumferentially equidistant and at an angle of 120° to one another, this results in gussets 6 to which no contact tongues 4 are connected, and gussets 7 to which contact tongues 4 of the surrounding openings 3 are connected, forming a mechanical stiffener. In the device shown, gussets 6 without contact tongues 4 alternate with gussets 7 with contact tongues 4.

[0015] For stability reasons, the edge region 8 of the contact plate 1 can be formed at least five times as wide as the narrowest point 9 between two openings 3.

Claims

1. A device for connecting in parallel multiple battery cells (2) arranged in parallel to one another with respect to a joining axis with a contact plate (1) having individual passages (3), characterized in that each passage (3) is designed for the jacket-side enclosure of the battery cells (2) and comprises at least one contact tongue (4), which has on the passage side a contact body (5) protruding from the contact tongue (4) into the passage (3) in the form of a cut ovoid.

2. The device according to claim 1, characterized in that the contact bodies (5) are pressed out of the contact tongues (4).

3. The device according to claim 1 or 2, characterized in that the circular passages (3) of the contact plate (1) are arranged according to a densest circle packing with formation of spandrels (6, 7) lying between each three passages (3).

4. The device according to any one of claims 1 to 3, characterized in that the passages (3) each have at least three contact tongues (4) arranged circumferentially equidistant to one another.

5. The device according to claim 4, characterized in that each contact tongue (4) of one passage (3) surrounded by six passages (3) delimits a spandrel (7) which is also delimited by one contact tongue (4) of each of two surrounding passages (3).

6. The device according to any one of claims 1 to 5, characterized in that the edge region (8) of the contact plate (1) is formed at least five times wider than the narrowest point (9) between two passages (3).