Connecting device for battery cells of power battery and power battery

Abstract

The invention relates to a connecting device (16) for battery cells (12, 14) of a power battery (10), which connecting device is provided for compensating for errors between two battery cells (12, 14) of the power battery (10) in at least two spatial directions, comprising: a busbar (26), which is provided for electrically connecting with a first end (22) thereof to a first battery cell (12), a busbar (26) which is electrically connected with the first battery cell (12) by means of its first end (24) and with the second battery cell (14) by means of its second end (24), thus electrically connecting the two battery cells (12, 14) to each other; and a fastening means (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 power battery (10) for error compensation (30).

Description

Technical Field

[0001] The invention relates to a connecting device for a battery cell of a power battery and a power battery for a motor vehicle. Background Art

[0002] EP2715837B1 discloses a cover for an electrochemical device, which comprises a plurality of electrochemical cells. The cover comprises a carrier element, on which at least one cell connector is arranged for electrically conductively connecting a first cell terminal of a first electrochemical cell to a second cell terminal of a second electrochemical cell. Each cell connector comprises two contact areas for electrically contacting one cell terminal each and a compensation area for connecting the two contact sections to each other, the compensation area being elastically and / or plastically deformable so as to allow relative movement of the two contact sections of the cell connector to each other during operation of the electrochemical device and / or for error compensation in assembly of the electrochemical device. For this purpose, the compensation area may have one or more compensation waves extending transversely to the connection direction.

[0003] DE102014003911A1 discloses a battery for a motor vehicle, comprising: at least one battery cell having at least one electrode; and an electrical connection element for electrically connecting the at least one electrode of the battery cell; and a busbar for electrically connecting the at least one electrode of the battery cell to an electrode of another battery cell. Therefore, the electrical connection element can be used similarly to a conductive adhesive, by which the busbar can be fixed to the electrode of the battery cell. The conductive and elastically deformable connection element can be used for error compensation.

[0004] In addition, WO 2009 / 080148 A2 discloses a battery cell connector for connecting electrodes of two battery cells of a battery, which is formed in the form of a metal plate. The battery cell connector has two openings, and a compensation element is arranged in the region of each opening between the battery cell connector and the electrode. Since the compensation element is arranged in the opening of the battery cell connector, compensation of errors related to the electrode position is allowed. Summary of the invention

[0005] The object of the present invention is to provide a solution which allows tolerance compensation between two battery cells which are electrically connected to one another and which allows the battery cells to be protected from damage due to mechanical loads.

[0006] The object is achieved by the subject matter of the independent claims. Other possible solutions of the invention are disclosed in the dependent claims, the description and the drawings. The features, advantages and possible solutions set out within the scope of the description for one of the subject matters of the independent claims may be regarded at least similarly as the features, advantages and possible solutions of the corresponding subject matter of the other independent claims, and may be regarded at least similarly as the features, advantages and possible solutions of each possible combination of the subject matter of the independent claims (perhaps in combination with one or more dependent claims).

[0007] The present invention relates to a connecting device for a battery cell of a power battery, which is arranged to compensate for errors between two battery cells of the power battery in at least two spatial directions. The power battery is arranged to provide electrical energy for an electric drive train of an electrically drivable motor vehicle. Therefore, the electrically drivable motor vehicle can be electrically driven by means of electrical energy from the power battery, in particular from the battery cells of the power battery. The power battery includes a plurality of battery cells, which are electrically connected to each other. At least two of the battery cells of the power battery can be electrically connected to each other by means of a connecting device. The connecting device can be arranged to electrically connect the battery cells of the same battery module of the power battery to each other, or to electrically connect the battery cells of different battery modules of the power battery to each other. The errors between the battery cells to be connected can be compensated by means of the connecting device. The structure with error compensation capability allows compensation of errors or compensation of deviations within a specified error. This means that errors or deviations between the battery cells to be connected to each other can be compensated by means of the connecting device.

[0008] The connecting device comprises a busbar which is provided for electrically connecting the first battery cell with its first end and for electrically connecting the second battery cell with its second end, so that the busbar electrically connects the two battery cells to one another. In particular, the busbar is provided for allowing tolerance compensation between the first battery cell and the second battery cell along their longitudinal extension. In this case, the busbar can allow tolerance compensation between the battery cells in the vehicle transverse direction and in the vehicle longitudinal direction in particular at the installation position of the connecting device in the motor vehicle.

[0009] The connecting device also includes a fixing mechanism, by which the connecting device can be fixed to the housing member or structural member of the power battery at different relative positions for error compensation. The housing member can be, for example, the bottom or side wall or cover of the housing of the electric power battery. The structural member of the power battery can be, for example, a reinforcing rib of the power battery. With the help of the reinforcing rib, for example, the housing of the power battery can be reinforced. Since the connecting device can be fixed to the housing member or structural member of the power battery at different relative positions, the connecting device can be moved relative to the housing member or structural member of the power battery when compensating for the error between the battery cells, and can therefore be fixed to the housing member or structural member without mechanical stress. Since the connecting device is connected to the housing member or structural member of the power battery via the fixing mechanism, the mass of the connecting device is received by the housing member or structural member of the power battery. In addition, during the operation of the motor vehicle or during the driving of the motor vehicle, vibrations can be absorbed via the housing member or structural member. Therefore, the battery cell can be protected from large loads, especially from loads on the corresponding interfaces of the battery cell, where the battery cell is mechanically connected to the connecting device, especially the busbar. The connecting device therefore allows, on the one hand, a connection of the battery cells with tolerance compensation and, on the other hand, particularly good protection of the battery cells from damage.

[0010] In another possible solution of the present invention, it is provided that the busbar is arranged to be rotatably connected to the first battery cell via the first end of the busbar. This means that the busbar rests with its first end on the first interface of the first battery cell in the connection direction and is rotatable relative to the first battery cell around the connection direction. Therefore, error compensation between the first battery cell and the second battery cell in directions extending perpendicularly to the connection direction is possible. In other words, the connecting device is arranged to allow rotation between the first battery cell and the busbar. Therefore, error compensation is achieved in the rotation plane of the busbar perpendicular to the connection direction.

[0011] It is further provided that the busbar has an elongated hole at its second end, through which the busbar can be connected to the second battery cell in a manner that it can be moved relative to the second battery cell, in order to compensate for errors between the battery cells. The elongated hole extends, in particular, with its longitudinal direction in the longitudinal extension direction of the busbar. Error compensation in the longitudinal extension direction of the busbar is therefore possible. Error compensation can therefore be achieved 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 therefore possible that the busbar has a constant length, wherein error compensation is achieved along the longitudinal extension direction of the busbar by means of the elongated hole provided at the second end of the busbar. Therefore, the busbar can be manufactured particularly simply and has a particularly high stability.

[0012] In another possible solution of the present invention, it is provided that the connection device comprises a housing which completely surrounds the busbar. The housing serves as a contact protection and is in particular provided for electrically isolating the busbar. In particular, the housing covers the busbar at least substantially completely outwardly, so that electrical contact between the busbar and other components other than the battery cells connected to the busbar can be particularly reliably prohibited. As a result, the risk of injury to personnel and the risk of short circuits between the connection device and components of the power battery can be kept particularly low.

[0013] In this context, in an extension of the invention, it can be provided that the housing comprises at least two housing elements, which are movable relative to one another along the longitudinal extension direction of the busbar, respectively surround the busbar along the longitudinal extension direction of the busbar over a length region, and overlap each other in an overlapping region, so that the busbar is surrounded circumferentially by the two housing elements in the overlapping region. Due to the overlap of the housing elements in the overlapping region, the busbar is reliably and completely surrounded circumferentially by at least one of the housing elements in each displacement position of the housing elements relative to one another along the entire length of the busbar. The busbar is covered outwardly by the corresponding housing element in a direction perpendicular to its longitudinal extension direction. In each displacement position of the housing elements, the housing elements adjacent to each other overlap each other, so that the busbar is reliably electrically isolated outwardly at any time by means of the housing elements.

[0014] In this context, in a further possible embodiment of the invention it is provided that one of the housing elements has a fastening device.

[0015] Due to the relative movability of the housing elements relative to each other along the longitudinal extension direction of the busbar, the fixing mechanism can be moved relative to the busbar along the longitudinal extension direction of the busbar. Due to the movability of the fixing mechanism relative to the busbar along the longitudinal extension direction of the busbar, the fixing mechanism can be arranged overlapping with the housing component or structural component to which the fixing mechanism is to be fixed in different rotational positions of the busbar around its first end. Therefore, the fixing mechanism can be connected to the housing component or structural component of the power battery while introducing particularly little mechanical stress into the connecting device. Due to the relative movability of the fixing mechanism relative to the busbar along the longitudinal extension direction of the busbar, it can be ensured that the fixing mechanism can be reliably connected to the housing component or structural component of the power battery despite the error compensation along the longitudinal extension direction of the busbar.

[0016] In another possible solution of the present invention, it is provided that at least three housing elements are provided, wherein the housing element having the fixing mechanism can be moved along the longitudinal extension direction of the busbar not only relative to a first housing element assigned to the first end of the busbar but also relative to a second housing element assigned to the second end of the busbar. Therefore, the fixing mechanism can be moved along the longitudinal extension direction of the busbar relative to the first end of the busbar and relative to the second end of the busbar. Therefore, it is allowed to set the fixing mechanism at different relative positions relative to the housing component or structural component of the power battery, and at the same time ensure that, at each relative position of the fixing mechanism relative to the housing component or structural component, the busbar is completely surrounded by the housing and is therefore reliably electrically isolated.

[0017] In another possible solution of the present invention, it is provided that the fixing mechanism has a long hole. The long hole extends with its length, in particular perpendicularly to the longitudinal extension direction of the busbar. The length of the long hole is oriented obliquely or perpendicularly to the longitudinal extension direction of the busbar. Since the fixing mechanism is movable relative to the busbar along the longitudinal extension direction of the busbar and additionally has the following long hole: the longitudinal extension direction of the long hole extends obliquely or perpendicularly to the longitudinal extension direction of the busbar, the connecting device can be reliably fixed to the housing component or the structural component in different relative positions by means of the fixing mechanism, and error compensation in at least two spatial directions is possible by means of the connecting device. Therefore, a fixing point of the fixing mechanism on the housing component or on the structural component is movable to allow error compensation relative to the busbar in two dimensions, in particular error compensation in the rotation plane of the busbar.

[0018] In another possible solution of the present invention, it is provided that the busbar has a wave, which is perpendicular to the longitudinal extension direction of the busbar with its height direction, thereby allowing error compensation in a third spatial direction. This means that the wave rises perpendicularly to the rotation plane and therefore rises from the rotation plane, in which the busbar can rotate about the first end relative to the first battery cell. In other words, the busbar has at least three bends in the length section, so that the busbar has a corrugated bulge. Due to the wave of the busbar, the busbar has elasticity in the height direction perpendicular to the rotation plane in the length section with the wave, so that error compensation between the first battery cell and the second battery cell can be achieved in this third spatial direction. In the length section with the wave, the busbar can be elastically deformed due to the bends of the wave, so that the height difference between the interfaces of the battery cells can be compensated in the height direction, and each battery cell can be connected to the busbar at the interface respectively.

[0019] The present invention also relates to a power battery for a motor vehicle, the power battery comprising a first battery cell, a second battery cell and a structural member or a housing member. In addition, the power battery comprises a connecting device, which is electrically connected to the first battery cell at one end and to the second battery cell at the other end. The connecting device is movably held on the structural member or the housing member by a fixing mechanism. In addition, the connecting device is provided to compensate for errors in at least two spatial directions between the two battery cells of the power battery. In particular, the connecting device compensates for errors between the first battery cell and the second battery cell at least in two spatial directions, in particular in three spatial directions. The connecting device is in particular the connecting device already described in relation to the connecting device of the present invention. Since the connecting device is fixed to the structural member or the housing member, and the connecting device is supported on the housing member or the structural member, the mechanical load of the corresponding interfaces of each battery cell can be kept particularly small, and each battery cell is connected to the connecting device at these interfaces. Since the connecting device is movably fixed to the structural component or the housing component, errors between the first battery cell and the second battery cell can be compensated particularly well, or particularly large errors between the first battery cell and the second battery cell can be compensated, and at the same time, reliable support of the connecting device on the structural component or the housing component can be guaranteed.

[0020] In a possible embodiment 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 therefore a module connector, via which the battery cells of different battery modules of the power battery are connected to one another not only mechanically but also electrically. With the aid 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 reliably and in a manner with a particularly low risk of damage to the individual battery cells.

[0021] Other features of the invention can be derived from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations shown below in the description of the drawings and / or in the drawings alone can be used not only in the combination described respectively, but also in other combinations or can be used alone without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The attached pictures are as follows:

[0023] Figure 1 A schematic top view showing a portion of a power battery for a motor vehicle, the power battery comprising a first battery cell, a second battery cell, a structural member, and a connecting device; and

[0024] Figure 2 A schematic perspective view showing a connection arrangement.

[0025] In the figures, identical elements or elements having the same function are provided with the same reference symbols. DETAILED DESCRIPTION

[0026] exist Figure 1 1 shows a power battery 10 for a motor vehicle in a top view. The power battery 10 is provided to provide electrical energy for an electric drive train of the motor vehicle. Thus, the motor vehicle can be driven by means of electrical energy from the power battery 10. The power battery 10 includes a plurality of battery cells. Figure 1 1 and 14 are shown in the figure. The first battery cell 12 is a component of a first battery module of the power battery 10, and the second battery cell 14 is a component of a second battery module of the power battery 10. The power battery 10 also includes a connecting device 16, through which the first battery cell 12 is connected to the second battery cell 14. The connecting device 16 is currently a module connector. The connecting device 16 is Figure 2 are described separately in perspective views.

[0027] exist Figure 11 and 2. In addition, a structural component 18 of the power battery 10 is shown. The structural component 18 is a reinforcement rib of the power battery 10 in the present case. The connecting device 16 is provided for electrically connecting the interfaces 20 of the battery cells 12 and 14, which are oriented in the vehicle height direction z at the installation position, to each other. The connecting device 16 is connected to the first battery cell 12 via the first interface 20 with its first end 22, and is connected to the second battery cell 14 via the second interface 20 with its second end 24. In order to electrically connect 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 is electrically contacted with the second battery cell 14 in the region of the second end 24. The connecting device 16 is rotatably held on the first battery cell 12 at its first end 22 about the vehicle height direction z. At the second end 24 of the connecting device 16, which is opposite to the first end 22, the busbar 26 has an elongated hole 28, through which the busbar 26 is connected to the second battery cell 14. By means of the elongated hole 28, the length of which extends parallel to the longitudinal extension direction of the busbar 26, tolerance compensation 30 between the first battery cell 12 and the second battery cell 14 along the longitudinal extension direction of the busbar 26 is possible. Since the busbar 26 is rotatably held on the first interface 20 of the first battery cell 12, the busbar 26 can be pivoted in a plane formed by the vehicle longitudinal direction x and the vehicle transverse direction y for the tolerance compensation 30. Thus, in the installed position of the power battery 10, 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 can be achieved particularly well by means of the busbar 26.

[0028] In order to allow tolerance compensation in the vehicle height direction z, the connecting device 16 has a wave 32 in the length region, which wave is perpendicular with its height direction to the longitudinal extension direction of the busbar 26. Due to the wave 32, tolerances between the battery cells 12, 14 in the vehicle height direction z can be compensated by means of the busbar 26 without the busbar 26 being lifted with its respective ends from the connection 20 of the battery cells 12, 14.

[0029] The connecting device 16 also includes a fixing mechanism 34, by which the connecting device 16 is fixed to the structural component 18 of the power battery 10. The fixing mechanism 34 is retained on one of the multiple housing elements 36 of the connecting device 16. At present, the connecting device 16 includes three housing elements 36, among which the first housing element is assigned to the first end 22, the second housing element is assigned to the second end 24, and the third housing element has a fixing mechanism 34. The housing elements 36 can be moved relative to each other along the longitudinal extension direction of the busbar 26. The busbar 26 is completely electrically isolated from the outside by the housing elements 36 at any displacement position of the housing elements 36 relative to each other. This means that the busbar 26 is completely surrounded by the housing elements 36. The housing elements 36 are constructed to have an electrical isolation effect.

[0030] In order to allow the relative movement of the housing elements 36 along the longitudinal extension direction of the busbar 26 and at the same time ensure that the busbar 26 is completely surrounded by the housing elements 36 toward the outside at any relative position of the housing elements 36, corresponding overlapping areas 38 are provided, in which adjacent housing elements 36 overlap each other in a length section of the busbar 26. This means that the busbar 26 is surrounded on the outer circumferential side by two mutually adjacent housing elements 36 in the corresponding overlapping area 38. Therefore, in the corresponding overlapping area 38, one of the housing elements 36 surrounds the adjacent housing element 36 on the outer circumferential side. The overlapping areas 36 are used to provide a contact protection device in order to ensure that the busbar 26 is completely electrically isolated toward the outside at any time.

[0031] Since 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 during the tolerance compensation 30 along the longitudinal extension direction of the busbar 26 that the connecting device 16 can be fixed to the structural component 18 by the fixing means 34. For this purpose, it can be additionally provided that the fixing means 34 has an elongated hole 40, the length of which extends perpendicularly to the longitudinal extension direction of the busbar 26 and perpendicularly to the height extension direction of the wave 32. In the present case, the length of the elongated hole 40 extends 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 provided for dissipating vibrations via the structural connection to the structural component 18, which vibrations may occur due to the free length of the busbar 26 and may lead to damage to the connecting device 16 or to the battery cells 12, 14 connected to the connecting device 16 via the interface 20. Such a firmly integrated structural connection can compensate for large tolerances in a compact installation space.

[0033] In the connection device 16, it is provided that the contact protector is divided into three structural components, in the present case into three housing elements 36, which are plastic housings clamped in a shell-like structure for the busbar 26. The middle housing element 36 has a fixing mechanism 34, which is a structural connection and therefore a bracket for the screw connection. The middle housing element 36 is mounted on the busbar 26 in a longitudinally movable manner. Therefore, errors in the longitudinal direction of the busbar 26 can be compensated on the bracket. An elongated hole 40 is provided on the fixing mechanism 34, which is oriented obliquely or perpendicularly to the busbar 26 with its length and is introduced into the bracket. Therefore, errors transverse to the longitudinal extension direction of the busbar 26 can be compensated.

[0034] In a power battery 10 designed as a high-voltage storage device, two battery modules are electrically connected to each other via a connecting device 16 designed as a module connector. The module connector is fixed to a structural component 18 or a housing of the high-voltage storage device by means of an integrated bracket. In this design, tolerances between the interfaces 20 of the battery cells 12, 14 assigned to different battery modules can be compensated, and thus length tolerances can be compensated along the longitudinal extension direction of the busbar 26 and in the plane at the screw connection points of the bracket on the structural component 18 of the high-voltage storage device. The tolerance compensation along the longitudinal extension direction of the busbar 26 and in the current vehicle longitudinal direction x is achieved by the position of the bracket between the two interfaces 20, and the tolerance compensation perpendicular to the longitudinal extension direction of the busbar 26 and therefore in the current vehicle transverse direction y is achieved by the spacing between the busbar 26 and the borehole of the structural component 18, through which the connecting device 16 is fixed to the structural component 18 of the power battery 10 by means of the slotted hole 40.

[0035] Overall, the invention shows how a busbar 26 can be implemented as a cell connector or module connector with a contact protection device and a structural connection and with integrated tolerance compensation in at least two spatial directions.

[0036] Reference numerals list

[0037] 10 Power Battery

[0038] 12 First battery cell

[0039] 14 Second battery cell

[0040] 16 Connecting device

[0041] 18 Structural members

[0042] 20 Interface

[0043] 22 First end

[0044] 24 Second end

[0045] 26 Bus

[0046] 28 Long hole

[0047] 30 Error compensation

[0048] 32 waves

[0049] 34 Fixing mechanism

[0050] 36 Shell element

[0051] 38 Overlapping Area

[0052] 40 Long hole

Claims

1. A connecting device (16) for battery cells (12, 14) of a power battery (10), the connecting device being configured to compensate for errors between two battery cells (12, 14) of the power battery (10) in at least two spatial directions, the connecting device comprising: a busbar (26) which is provided for electrically connecting the first battery cell (12) with its first end (22) and for electrically connecting the second battery cell (14) with its second end (24), so that the busbar (26) electrically connects the two battery cells (12, 14) to one another; and A fixing mechanism (34) by which the connecting device (16) can be fixed to a housing component or a structural component (18) of the power battery (10) in different relative positions for tolerance compensation (30).

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

3. The connecting device (16) according to claim 1 or 2, characterized in that: A housing is provided which completely surrounds the busbar (26).

4. The connection device (16) according to claim 3, characterized in that The housing comprises at least two housing elements (36) which are movable relative to one another along the longitudinal extension direction of the busbar (26), respectively surround the busbar (26) over a length region, and overlap one another in an overlapping region (38), so that the busbar (26) is surrounded circumferentially by the two housing elements (36) in the overlapping region (38).

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

6. The connection device (16) according to claim 5, characterized in that At least three housing elements (36) are provided, wherein the housing element (36) having the fixing means (34) is movable along the longitudinal extension direction of the busbar (26) both relative to a first housing element (36) assigned to a first end (22) of the busbar (26) and relative to a second housing element (36) assigned to a second end (24) of the busbar (26).

7. A connecting device (16) according to any one of the preceding claims, characterized in that The fixing means (34) has an elongated hole (40).

8. The connecting device (16) according to any one of the preceding claims, characterized in that The busbar (26) has waves (32) whose height direction is perpendicular to the longitudinal extension direction of the busbar (26), thus allowing error compensation (30) in a third spatial direction.

9. A power battery (10) for a motor vehicle, the power battery comprising: - a first battery cell (12); - a second battery cell (14); - a structural member (18) or a housing member; as well as - a connecting device (16) which is electrically connected to a first battery cell (12) at one end and to a second battery cell (14) at the other end, the connecting device being movably held on a structural component (18) or a housing component by a fixing mechanism (34), and being provided for compensating for errors between two battery cells (12, 14) of a power battery (10) in at least two spatial directions.

10. The power battery according to claim 9, characterized in that: The first battery cell (12) is a component of a first battery module, and the second battery cell (14) is a component of a second battery module.

Images