Connecting device for battery cells of a traction battery, and traction battery

Abstract

The invention relates to a connecting device (16) for battery cells (12, 14) of a traction battery (10), which connecting device is designed to compensate for tolerances between two battery cells (12, 14) of the traction battery (10) in at least two spatial directions, comprising a bus bar (26), the first end (22) of which is designed to be electrically connected to a first battery cell (12), and the second end (24) of which is designed to be electrically connected to a second battery cell (14), as a result of which the bus bar (26) electrically interconnects the two battery cells (12, 14), and comprising a fastening device (34) via which the connecting device (16) can be fastened in various relative positions to a housing component or a structural component (18) of the traction battery (10) for the purpose of tolerance compensation (30).

Description

[0001] Connection device for battery cells of a traction battery and traction battery

[0002] The invention relates to a connecting device for battery cells of a traction battery and a traction battery for a motor vehicle.

[0003] EP 2 715 837 B1 discloses a cover for an electrochemical device comprising a plurality of electrochemical cells. This cover comprises a carrier element on which at least one cell connector is arranged for electrically connecting a first cell terminal of a first electrochemical cell and a second cell terminal of a second electrochemical cell. Each cell connector comprises two contact regions for electrically contacting one cell terminal each and a compensation region connecting the two contact regions to one another, which compensation region is designed to be elastically and / or plastically deformable in order to enable relative movement of the two contact regions of the cell connector to one another during operation of the electrochemical device and / or to compensate for tolerances during assembly of the electrochemical device.For this purpose, the compensation area can have one or more compensation waves running transversely to a connection direction.

[0004] DE 10 2014 003 911 A1 discloses a battery for a motor vehicle with at least one battery cell comprising at least one terminal, as well as an electrical connecting element for electrically connecting the at least one terminal of the battery cell, and a busbar for electrically connecting the at least one terminal of the battery cell to a terminal of another battery cell. The electrical connecting element can thus be used similarly to a conductive adhesive, with which the busbar can be attached to the terminals of the battery cells. The electrically conductive and simultaneously elastically deformable connecting element can serve as a tolerance compensation element.

[0005] Furthermore, WO 2009 / 080148 A2 discloses a cell connector for connecting two terminals of battery cells, which is designed in the form of a sheet metal. The cell connector has two openings, with a compensating element arranged between the cell connector and the terminal in the area of ​​each opening. The arrangement of the compensating element in the opening of the cell connector enables tolerance compensation regarding the position of the terminal.

[0006] The object of the invention is to create a solution which enables tolerance compensation between two electrically connected battery cells and protects the battery cells from damage resulting from mechanical stress.

[0007] This problem is solved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0008] The invention relates to a connecting device for battery cells of a traction battery, wherein the connecting device is configured to compensate for tolerances between two battery cells of the traction battery in at least two spatial directions. The traction battery is configured to provide electrical energy for an electric drive train of an electrically operable motor vehicle. Thus, the electrically operable motor vehicle can be electrically driven by means of electrical energy from the traction battery, in particular from the battery cells of the traction battery. The traction battery comprises a plurality of battery cells that are electrically connected to one another. At least two of the battery cells of the traction battery can be electrically connected to one another by means of the connecting device.The connecting device can be configured to electrically connect battery cells of the same battery module or battery cells of different battery modules of the traction battery. Tolerances between the battery cells to be connected can be compensated for using the connecting device. Designs that feature tolerance compensation allow for the compensation of errors or deviations within specified tolerances. This means that errors or deviations between the battery cells to be connected can be compensated for using the connecting device.

[0009] The connecting device comprises a busbar, which is designed to be electrically connected at its first end to a first battery cell and at its second end to a second battery cell, whereby the busbar electrically connects the two battery cells to one another. In particular, the busbar is designed to enable tolerance compensation along its longitudinal direction between the first battery cell and the second battery cell. In the installed position of the connecting device in the motor vehicle, the busbar can, in particular, enable tolerance compensation between the battery cells in the transverse direction and in the longitudinal direction of the vehicle.

[0010] The connecting device further comprises a fastening device, via which the connecting device can be fastened in different relative positions to a housing component or a structural component of the traction battery for tolerance compensation. The housing component can be, for example, a base, a side wall, or a cover of a housing of the electric traction battery. The structural component of the traction battery can be, for example, a reinforcing rib of the traction battery. The reinforcing rib can, for example, be used to stiffen the housing of the traction battery.Because the connecting device can be fastened in different relative positions to the housing component or the structural component of the traction battery, the connecting device can be moved relative to the housing component or the structural component of the traction battery while compensating for tolerances between the battery cells, and can thus be fastened to the housing component or the structural component without mechanical stress. By attaching the connecting device to the housing component or the structural component of the traction battery via the fastening device, the mass of the connecting device is absorbed by the housing component or the structural component of the traction battery. Furthermore, vibrations during operation or while the motor vehicle is traveling can be absorbed by the housing component or the structural component.This allows the battery cells to be protected from significant stresses, particularly at the respective interfaces of the battery cells where the battery cells are mechanically connected to the connecting device, in particular the busbar. The connecting device thus enables the battery cells to be connected with the tolerance compensation and, at the same time, provides particularly good protection for the battery cells against damage.

[0011] In a further possible embodiment of the invention, it is provided that the busbar is designed to be rotatably connected to the first battery cell via its first end. This means that the busbar is placed with its first end in a connecting direction onto the first interface of the first battery cell and is rotatable about this connecting direction relative to the first battery cell. This enables tolerance compensation between the first battery cell and the second battery cell in directions perpendicular to the connecting direction. In other words, the connecting device is designed to permit rotation between the first battery cell and the busbar. This enables tolerance compensation in the rotation plane of the busbar that is perpendicular to the connecting direction.

[0012] It is further provided that the busbar has an elongated hole at its second end, via which the busbar can be connected to the second battery cell so as to be displaceable relative to the second battery cell in order to compensate for tolerances between the battery cells. The elongated hole runs in particular with its longitudinal direction in the longitudinal direction of the busbar. This enables tolerance compensation in the longitudinal direction of the busbar. The tolerance compensation can thus take place by means of the elongated hole along a straight line from the first interface of the first battery cell to the second interface of the second battery cell. It is thus possible for the busbar to have a constant length, wherein the tolerance compensation along the longitudinal direction of the busbar takes place via the elongated hole provided at the second end of the busbar.This makes the busbar particularly easy to manufacture and ensures particularly high stability.

[0013] In a further possible embodiment of the invention, the connecting device comprises a housing that completely encloses the busbar. This housing serves as contact protection and is particularly designed to electrically insulate the busbar. In particular, the housing covers the busbar at least substantially completely to the outside, thereby particularly reliably preventing electrical contact between the busbar and components other than the battery cells connected to the busbar. This makes it possible to particularly minimize the risk of injury to persons and the risk of short circuits between the connecting device and components of the traction battery.

[0014] In this context, a further development of the invention can provide for the housing to comprise at least two housing elements which are displaceable relative to one another along the longitudinal direction of the busbar, each enclose the busbar over a length range along the longitudinal direction of the busbar, and overlap one another in an overlapping region, whereby the busbar is circumferentially enclosed by both housing elements in the overlapping region. Due to the overlapping of the housing elements in the overlapping region, the busbar is reliably and completely circumferentially enclosed by at least one of the housing elements along its entire length in every displacement position of the housing elements relative to one another. The busbar is covered outwards by the respective housing elements perpendicular to its longitudinal direction.In every sliding position of the housing elements, the adjacent housing elements overlap each other, whereby the busbar is reliably electrically insulated from the outside at all times by means of the housing elements.

[0015] In this context, a further possible embodiment of the invention provides that one of the housing elements has the fastening device. Due to the relative displaceability of the housing elements to one another along the longitudinal direction of the busbar, the fastening device can thus be displaced along the longitudinal direction of the busbar relative to the busbar. Due to the displaceability of the fastening device along the longitudinal direction of the busbar relative to the busbar, the fastening device can be arranged in overlap with the housing component or the structural component to which the fastening device is to be fastened - with different rotational positions of the busbar about its first end.This allows the fastening device to be connected to the housing component or the structural component of the traction battery with very little mechanical stress introduced into the connecting device. The relative displaceability of the fastening device along the longitudinal direction of the busbar relative to the busbar ensures that the fastening device can be securely connected to the housing component or the structural component of the traction battery, despite the tolerance compensation along the longitudinal direction of the busbar.

[0016] In a further possible embodiment of the invention, at least three housing elements are provided, wherein the housing element having the fastening device is displaceable along the longitudinal direction of the busbar both relative to a first housing element associated with the first end of the busbar and relative to a second housing element associated with the second end of the busbar. As a result, the fastening device is displaceable along the longitudinal direction of the busbar relative to the first end and relative to the second end of the busbar.As a result, the arrangement of the fastening device in the different relative positions to the housing component or the structural component of the traction battery is made possible and at the same time it is ensured that in each of the relative positions of the fastening device relative to the housing component or the structural component, the busbar is completely surrounded by the housing and is thus reliably electrically insulated.

[0017] In a further possible embodiment of the invention, it is provided that the fastening device has an elongated hole. This elongated hole extends with its length in particular perpendicular to the longitudinal direction of the busbar. The length of the elongated hole is oriented obliquely or perpendicularly to the longitudinal direction of the busbar. Because the fastening device is displaceable along the longitudinal direction of the busbar relative to the busbar and additionally has the elongated hole whose longitudinal direction runs obliquely or perpendicularly to the longitudinal direction of the busbar, the connecting device can be securely fastened in different relative positions to the housing component or the structural component via the fastening device, wherein at the same time, tolerance compensation is possible at least in the two spatial directions by means of the connecting device.A fastening point of the fastening device on the housing component or on the structural component is thus movable two-dimensionally relative to the busbar, in particular in the plane of rotation of the busbar, in order to enable tolerance compensation.

[0018] In a further possible embodiment of the invention, it is provided that the busbar has a shaft whose vertical direction is perpendicular to the longitudinal direction of the busbar, thereby enabling tolerance compensation in the third spatial direction. This means that the shaft rises perpendicular to the plane of rotation and thus rises out of the plane of rotation in which the busbar can be rotated about the first end relative to the first battery cell. In other words, the busbar has at least three bends in one longitudinal section, whereby the busbar has a wave-shaped elevation. Due to the shaft of the busbar, the busbar has a spring in the vertical direction perpendicular to the plane of rotation in the longitudinal section comprising the shaft, whereby tolerance compensation between the first battery cell and the second battery cell can take place in this third spatial direction.In the longitudinal section having the shaft, the busbar is elastically deformable due to the bends of the shaft, whereby height differences between the interfaces of the battery cells, at which the battery cells can each be connected to the busbar, can be compensated in the vertical direction.

[0019] The invention further relates to a traction battery for a motor vehicle, comprising a first battery cell, a second battery cell, and a structural component or a housing component. Furthermore, the traction battery comprises a connecting device, which is electrically connected at one end to the first battery cell and at the other end to the second battery cell. The connecting device is displaceably held on the structural component or the housing component via a fastening device. Furthermore, the connecting device is configured to compensate for tolerances between two battery cells of the traction battery in at least two spatial directions. In particular, the connecting device compensates for tolerances between the first battery cell and the second battery cell at least in the two spatial directions, in particular in three spatial directions.The connecting device is, in particular, the connecting device described in connection with the connecting device according to the invention. Due to the fastening of the connecting device to the structural component or the housing component, the connecting device is supported on the housing component or the structural component, whereby mechanical loads on the respective interfaces of the battery cells at which the battery cells are connected to the connecting device can be kept particularly low.Due to the movable fastening of the connecting device to the structural component or the housing component, the tolerances between the first battery cell and the second battery cell can be compensated particularly well or particularly large tolerances between the first battery cell and the second battery cell can be compensated and at the same time a secure support of the connecting device on the structural component or the housing component can be ensured.

[0020] In a possible development of the invention, it is provided that the first battery cell is part of a first battery module and the second battery cell is part of a second battery module. The connecting device is thus a module connector, via which the battery cells of the various battery modules of the traction battery are connected to one another both mechanically and electrically. By means of the connecting device, the first battery cell of the first battery module and the second battery cell of the second battery module can be connected to one another particularly securely and with a particularly low risk of damage to the battery cells.

[0021] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] The drawing shows:

[0023] Fig. 1 is a schematic plan view of a section of a traction battery for a motor vehicle with a first battery cell, a second battery cell, a structural component and a connecting device; and

[0024] Fig. 2 is a schematic perspective view of the connecting device.

[0025] In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0026] Fig. 1 shows a detail of a traction battery 10 for a motor vehicle in a plan view. The traction battery 10 is designed to provide electrical energy for an electric drive train of the motor vehicle. The motor vehicle can thus be driven using electrical energy from the traction battery 10. The traction battery 10 comprises a plurality of battery cells, of which a first battery cell 12 and a second battery cell 14 are shown in Fig. 1. The first battery cell 12 is part of a first battery module of the traction battery 10, and the second battery cell 14 is part of a second battery module of the traction battery 10. The traction battery 10 further comprises a connecting device 16, via which the first battery cell 12 is connected to the second battery cell 14. In the present case, the connecting device 16 is a module connector. The connecting device 16 is shown in Fig.2 shown separately in a perspective view.

[0027] Fig. 1 also shows a structural component 18 of the traction battery 10. The structural component 18 in the present case is a stiffening rib of the traction battery 10. The connecting device 16 is designed to electrically connect respective interfaces 20 of the battery cells 12, 14, which are aligned in the vehicle vertical direction z in the installed position. The connecting device 16 is connected with its first end 22 to the first battery cell 12 via a first interface 20 and with its second end 24 to the second battery cell 14 via a second interface 20. For the electrical connection of the first battery cell 12 to the second battery cell 14, the connecting device 16 has a busbar 26. The busbar 26 is electrically contacted with the first battery cell 12 in the region of the first end 22 and electrically contacted with the second battery cell 14 in the region of the second end 24.The connecting device 16 is held at its first end 22 on the first battery cell 12 so that it can rotate about the vehicle's vertical direction z. At the second end 24 of the connecting device 16, opposite the first end 22, the busbar 26 has an elongated hole 28, via which the busbar 26 is connected to the second battery cell 14. Via the elongated hole 28, the length of which runs parallel to the longitudinal direction of the busbar 26, a tolerance compensation 30 between the first battery cell 12 and the second battery cell 14 along the longitudinal direction of the busbar 26 is possible. Due to the rotatable mounting of the busbar 26 at the first interface 20 of the first battery cell 12, the busbar 26 can be pivoted in a plane spanned by the vehicle's longitudinal direction x and the vehicle's transverse direction y for the tolerance compensation 30.The tolerance compensation 30 between the first battery cell 12 and the second battery cell 14 in the vehicle longitudinal direction x and in the vehicle transverse direction y in the installation position of the traction battery 10 can thus be carried out particularly well via the busbar 26.

[0028] To enable tolerance compensation in the vehicle's vertical direction z, the connecting device 16 has a shaft 32 in one longitudinal region, the vertical direction of which is perpendicular to the longitudinal direction of the busbar 26. This shaft 32 allows tolerances in the vehicle's vertical direction z between the battery cells 12, 14 to be compensated by means of the busbar 26 without the busbar 26 being lifted with its respective ends from the interfaces 20 of the battery cells 12, 14.

[0029] The connecting device 16 further comprises a fastening device 34, via which the connecting device 16 is fastened to the structural component 18 of the traction battery 10. This fastening device 34 is held on one of several housing elements 36 of the connecting device 16. In the present case, the connecting device 16 comprises three housing elements 36, a first of which is assigned to the first end 22, the second of which is assigned to the second end 24, and the third of which has the fastening device 34. The housing elements 36 are displaceable relative to one another along the longitudinal direction of the busbar 26. The busbar 26 is completely electrically insulated from the outside by the housing elements 36 in any sliding position of the housing elements 36 relative to one another. This means that the busbar 26 is completely enclosed by the housing elements 36. The housing elements 36 are designed to be electrically insulating.

[0030] In order to enable the relative displacement of the housing elements 36 along the longitudinal direction of the busbar 26 and at the same time to ensure that the busbar 26 is completely enclosed to the outside by the housing elements 36 in every relative position of the housing elements 36 to one another, respective overlapping regions 38 are provided, in which adjacent housing elements 36 overlap one another in a longitudinal section of the busbar 26. This means that the busbar 26 is enclosed on the outer circumference by both adjacent housing elements 36 in the respective overlapping regions 38. In the respective overlapping regions 38, one of the housing elements 36 thus encloses the adjacent housing element 36 on the outer circumference. The overlapping regions 38 serve to provide contact protection to ensure that the busbar 26 is completely electrically insulated from the outside at all times.

[0031] Because the third housing element 36 can be moved both relative to the first end 22 and relative to the second end 24 of the busbar 26, it can be ensured with the tolerance compensation 30 along the longitudinal direction of the busbar 26 that the connecting device 16 can be fastened to the structural component 18 via the fastening device 34. For this purpose, it can additionally be provided that the fastening device 34 has an elongated hole 40 whose length runs perpendicular to the longitudinal direction of the busbar 26 and perpendicular to the vertical direction of the shaft 32. In the present case, the length of the elongated hole 40 runs in the vehicle transverse direction y. The connecting device 16 can be screwed to the structural component 18 via the elongated hole 40.

[0032] The connecting device 16 is configured to dissipate vibrations that occur due to a free length of the busbar 26 and that could lead to damage to the connecting device 16 or the battery cells 12, 14 connected to the connecting device 16 via the interfaces 20, via the structural connection to the structural component 18. This firmly integrated structural connection can compensate for large tolerances in a compact installation space.

[0033] In the connecting device 16, the contact protection, which is a plastic housing for the busbar 26 that is clipped onto a shell construction, is divided into three assemblies, in this case the three housing elements 36. The middle housing element 36 has the fastening device 34, which is the structural connection and thus a holder for a screw connection. This middle housing element 36 is mounted on the busbar 26 so that it can be moved longitudinally. This allows tolerances in the longitudinal direction of the busbar 26 to be compensated for on the holder. The fastening device 34 has an elongated hole 40 which is aligned with its length obliquely or perpendicular to the busbar 26 and is incorporated in the holder. This allows tolerances transverse to the longitudinal direction of the busbar 26 to be compensated for.

[0034] In the traction battery 10, which is designed as a high-voltage storage unit, two battery modules are electrically connected to one another by the connecting device 16, which is designed as a module connector. The module connector is attached to the structural component 18 or to a housing of the high-voltage storage unit using the integrated holder. In this design, tolerances between the interfaces 20 of the battery cells 12, 14 assigned to the different battery modules, and thus length tolerance compensation along the longitudinal direction of the busbar 26 and in the plane at the screw-on point of the holder on the structural component 18 of the high-voltage storage unit, must be compensated.The tolerance compensation along the longitudinal direction of the busbar 26 and in this case in the vehicle longitudinal direction x is carried out via the position of the holder between the two interfaces 20 and the tolerance compensation perpendicular to the longitudinal direction of the busbar 26 and thus in this case in the vehicle transverse direction y is carried out via the distance of the busbar 26 to a drill hole in the structural component 18, via which the connecting device 16 is fastened to the structural component 18 of the traction battery 10 by means of the elongated hole 40.

[0035] Overall, the invention shows how the busbar 26 can be designed as a cell or module connector with touch protection and structural connection with integrated tolerance compensation in at least two spatial directions. Reference numerals 10 Traction battery

[0036] 12 first battery cell

[0037] 14 second battery cell

[0038] 16 Connecting device

[0039] 18 Structural component 20 Interface

[0040] 22 first end

[0041] 24 second end

[0042] 26 Busbar

[0043] 28 Slotted hole 30 Tolerance compensation

[0044] 32 Wave

[0045] 34 Fastening device

[0046] 36 Housing element

[0047] 38 Overlap area 40 Slot

Claims

Patent claims 1. A connecting device (16) for battery cells (12, 14) of a traction battery (10), which is designed to compensate for tolerances between two battery cells (12, 14) of the traction battery (10) in at least two spatial directions, with a busbar (26) which is designed to be electrically connected with its first end (22) to a first battery cell (12) and with its second end (24) to a second battery cell (14), whereby the busbar (26) electrically connects the two battery cells (12, 14) to one another, and with a fastening device (34) by means of which the connecting device (16) can be fastened in different relative positions to a housing component or a structural component (18) of the traction battery (10) for the tolerance compensation (30).

2. Connecting device (16) according to claim 1, characterized in that the busbar (26) is designed to be rotatably connected to the first battery cell (12) via its first end (22) and has an elongated hole (24) at its second end (24), via which the busbar (26) can be connected to the second battery cell (14) in a displaceable manner relative to the second battery cell (14) in order to compensate for tolerances (30) between the battery cells (12, 14).

3. Connecting device (16) according to claim 1 or 2, characterized in that a housing is provided which completely encloses the busbar (26).

4. Connecting device (16) according to claim 3, characterized in that the housing comprises at least two housing elements (36) which are relatively are displaceable relative to one another along the longitudinal direction of the busbar (26), each enclose the busbar (26) over a length region and overlap one another in an overlap region (38), whereby the busbar (26) is circumferentially enclosed by both housing elements (36) in the overlap region (38).

5. Connecting device (16) according to claim 4, characterized in that one of the housing elements (36) has the fastening device (34).

6. Connecting device (16) according to claim 5, characterized in that at least three housing elements (36) are provided, wherein the housing element (36) having the fastening device (34) is displaceable along the longitudinal direction of the busbar (26) both relative to a first housing element (36) assigned to the first end (22) of the busbar (26) and relative to a second housing element (36) assigned to the second end (24) of the busbar (26).

7. Connecting device (16) according to one of the preceding claims, characterized in that the fastening device (34) has an elongated hole (40).

8. Connecting device (16) according to one of the preceding claims, characterized in that the busbar (26) has a shaft (32) which is perpendicular to the longitudinal direction of the busbar (26) with its vertical direction, whereby a tolerance compensation (30) in the third spatial direction is made possible.

9. Traction battery (10) for a motor vehicle, comprising a first battery cell (12), a second battery cell (14), a structural component (18) or a housing component and a connecting device (16) which is electrically connected at one end to the first battery cell (12) and at the other end to the second battery cell (14). which is displaceably held on the structural component (18) or the housing component via a fastening device (34) and which is configured to compensate for tolerances between two battery cells (12, 14) of the traction battery (10) in at least two spatial directions. Traction battery according to claim 9, characterized in that the first battery cell (12) is part of a first battery module and the second battery cell (14) is part of a second battery module.

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