BATTERY FOR A MOTOR VEHICLE AS WELL AS MOTOR VEHICLE AND MANUFACTURING METHOD THEREFORE

Abstract

A battery for an at least partially electrically drivable motor vehicle. The battery includes a battery pack with a plurality of battery cells, a frame enclosing the battery pack, which frame at least partially covers each of the battery cells on a shell surface of the respective battery cells, and a battery housing with an insertion opening for receiving the battery pack. The battery further includes a pretensioning device having a pretensioning unit which is designed to apply a pretensioning force onto the battery pack on a first side of the frame.

Claims

1. A battery for an at least partially electrically drivable motor vehicle, comprising: a battery pack with a plurality of battery cells, wherein each of the battery cells has two surface areas which are connected to one another via a shell surface of the respective battery cell; a battery housing with an insertion opening for receiving the battery pack; a frame which encloses the battery pack and is designed as a hollow profile with a closed cross-section, wherein the frame at least partially covers each of the battery cells on the shell surface of the respective battery cell; and a pretensioning device having a pretensioning unit which is designed to apply a pretensioning force onto the battery pack on a first side of the frame.

2. The battery according to claim 1, wherein the pretensioning device has a further pretensioning unit which is designed to apply a further pretensioning force onto the battery pack on a second side of the frame, which is opposite the first side, so that the pretensioning force of the pretensioning unit and the further pretensioning force of the further pretensioning unit act in opposition to each other.

3. The battery according to claim 1, wherein the pretensioning device has a plate element which rests with a plate top over the entire surface on the first side of the frame and is arranged with a plate bottom on at least one pretensioned spring element, wherein the at least one spring element has a defined spring constant and/or a defined spring characteristic which specifies the pretensioning force.

4. The battery according to claim 3, wherein the pretensioning device is connected to a further plate element via the at least one spring element and/or is arranged directly on the battery housing, and/or the at least one spring element contains a helical spring and/or a flat spring with a wavy cross-section.

5. The battery according to claim 1, wherein the frame has two further sides, each perpendicular to the first side, which are each arranged between the battery pack and a wall of the battery housing that delimits the insertion opening.

6. The battery according to claim 1, wherein the battery pack has a separating element which is positioned between two battery cells adjacent to one another and is designed to thermally insulate the two adjacent battery cells from one another or is positioned between a terminal one of the battery cells and the frame and is designed to thermally insulate the terminal one of the battery cells and the frame from one another.

7. The battery according to claim 6, wherein the separating element is present as a separate component or is integrated into the frame.

8. The battery according to claim 1, wherein the shell surface of each battery cell has a rectangular cross-section with two longitudinal sides and two end faces, which are shorter than the longitudinal sides by comparison, wherein two adjacent battery cells are arranged with their longitudinal sides adjacent one another.

9. A vehicle with a battery according to claim 1, wherein the battery is designed to supply electricity to a drive motor of the motor vehicle.

10. A method for producing a battery, wherein the battery has a battery pack with a plurality of battery cells, wherein each of the battery cells has two surface areas connected via a shell surface, wherein the battery further comprises a battery housing with an insertion opening for receiving the battery pack and a pretensioning device with a pretensioning unit, the method comprising the following steps: enclosing the battery pack with a frame which is designed as a hollow profile with a closed cross-section, such that each of the battery cells is at least partially covered by the frame on the shell surface of the respective battery cell; setting an assembly state of the pretensioning device, wherein the pretensioning unit is pretensioned and fixed in such a way that an outwardly directed pretensioning force is prevented before it is arranged inside the battery housing; arranging the enclosed battery pack and the fixed pretensioning device in the insertion opening of the battery housing, wherein the fixed pretensioning unit adjoins a first side of the frame; and setting an operating state of the pretensioning device arranged in the battery housing, wherein fixation of the pretensioning unit is released so that the pretensioning force is applied to the battery pack on the first side of the frame.

11. The battery according to claim 2, wherein the pretensioning device has a plate element which rests with a plate top over the entire surface on the first side of the frame and is arranged with a plate bottom on at least one pretensioned spring element, wherein the at least one spring element has a defined spring constant and/or a defined spring characteristic which specifies the pretensioning force.

12. The battery according to claim 2, wherein the frame has two further sides, each perpendicular to the first side, which are each arranged between the battery pack and a wall of the battery housing that delimits the insertion opening.

13. The battery according to claim 3, wherein the frame has two further sides, each perpendicular to the first side, which are each arranged between the battery pack and a wall of the battery housing that delimits the insertion opening.

14. The battery according to claim 4, wherein the frame has two further sides, each perpendicular to the first side, which are each arranged between the battery pack and a wall of the battery housing that delimits the insertion opening.

15. The battery according to claim 2, wherein the battery pack has a separating element which is positioned between two battery cells adjacent to one another and is designed to thermally insulate the two adjacent battery cells from one another or is positioned between a terminal one of the battery cells and the frame and is designed to thermally insulate the terminal one of the battery cells and the frame from one another.

16. The battery according to claim 3, wherein the battery pack has a separating element which is positioned between two battery cells adjacent to one another and is designed to thermally insulate the two adjacent battery cells from one another or is positioned between a terminal one of the battery cells and the frame and is designed to thermally insulate the terminal one of the battery cells and the frame from one another.

17. The battery according to claim 4, wherein the battery pack has a separating element which is positioned between two battery cells adjacent to one another and is designed to thermally insulate the two adjacent battery cells from one another or is positioned between a terminal one of the battery cells and the frame and is designed to thermally insulate the terminal one of the battery cells and the frame from one another.

18. The battery according to claim 5, wherein the battery pack has a separating element which is positioned between two battery cells adjacent to one another and is designed to thermally insulate the two adjacent battery cells from one another or is positioned between a terminal one of the battery cells and the frame and is designed to thermally insulate the terminal one of the battery cells and the frame from one another.

19. The battery according to claim 2, wherein the shell surface of each battery cell has a rectangular cross-section with two longitudinal sides and two end faces, which are shorter than the longitudinal sides by comparison, wherein two adjacent battery cells are arranged with their longitudinal sides adjacent one another.

20. The battery according to claim 3, wherein the shell surface of each battery cell has a rectangular cross-section with two longitudinal sides and two end faces, which are shorter than the longitudinal sides by comparison, wherein two adjacent battery cells are arranged with their longitudinal sides adjacent one another.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] Exemplary embodiments of the invention are described hereinafter. The following is shown:

[0035] FIG. 1 a schematic illustration of an exemplary embodiment of a motor vehicle according to the improved design; and

[0036] FIG. 2 a schematic sectional illustration of an exemplary embodiment of a battery according to the improved design.

DETAILED DESCRIPTION

[0037] The exemplary embodiments explained hereinafter are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention to be considered independently of one another, each of which also refining the invention independently of one another. Therefore, the disclosure is also intended to include combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.

[0038] The same reference numerals designate elements that have the same function in the figures. For the sake of clarity, elements that are functionally identical and shown multiple times, in particular in FIG. 2, are provided incompletely but at least once with a corresponding reference numeral.

[0039] FIG. 1 shows an example of a motor vehicle 10 designed as a passenger car with a drive motor 12 and a battery 14. The battery 14 can be designed as a so-called high-voltage battery to supply the drive motor 12 with electricity. Thus, the motor vehicle 10 can be at least partially electrically drivable and the drive motor 12 can be designed as an electric drive or a hybrid drive.

[0040] FIG. 2 shows, by way of example, sections of the battery 14 in a sectional illustration in layout format with reference to the components shown and described in connection with FIG. 1. The battery 14 comprises four battery packs 16, a battery housing 18, a respective frame 32 enclosing each battery pack 16, and a pretensioning device 36.

[0041] The battery housing 18 has two insertion openings 20 for receiving the battery pack 16, the two insertion openings 20 being arranged one above the other in the y-direction. In this case, the battery packs 16 are each positioned in pairs next to one another in the x-direction, i.e. left and right, in the respective insertion opening 20. The battery packs 16 are each relatively displaceable in the x-direction and relatively immovable in the y-direction within the insertion openings 20. Each battery pack 16 comprises six battery cells 22 arranged next to one another, each battery cell 22 having two surface areas 24 which are connected to one another via a shell surface 26 of the respective battery cell 22. Overall, the battery 14 can have between 150 and 200 battery cells 22, for example. In FIG. 2, only one of the two surface areas 24, i.e. a top surface with an electrical connection, is visibly shown, while the second of the two surface areas 24, i.e. a bottom surface, is covered. In particular, each battery cell 22 can be designed as a prismatic cell, so that the two surface areas 24 are rectangular and thus the shell surface 26 of each battery cell 22 has a rectangular cross-section with two longitudinal sides 28 in the y-direction and two end faces 30 in the x-direction which are shorter as compared to the longitudinal sides 28. In this case, two adjacent battery cells 22 are arranged within the battery pack 16 with their longitudinal sides 28 adjacent one another.

[0042] Each battery pack 16 is enclosed by the frame 32, which is designed as a hollow profile with a closed cross-section, the frame 32 at least partially covering each of the battery cells 22 on the shell surface 26. In particular, each battery cell 22 is covered by the frame 32 on the end faces 30 of the shell surface 26. In addition, at the end of the battery cells 22 of each battery pack 16, one of the longitudinal sides 28, which delimits the battery pack 16 to the outside, can be covered by the frame 32. In this case, the two surface areas 24 of each of the battery cells 22 are not covered by the frame 32. The frame 32 has a first side 34a, a second side 34b opposite thereto, each in the y-direction, and two further sides 34c, 34d. The two further sides 34c, 34d are each formed perpendicular to the first side 34c and the second side 34b, i.e. in the x-direction. Thus, the longitudinal sides 28 of each battery cell 22 are parallel to the first side 34a and the second side 34b, and the end faces 30 are parallel to the two further sides 34a, 34d.

[0043] The battery 14 also has the pretensioning device 36. The pretensioning device 36 comprises a pretensioning unit 38a and a further pretensioning unit 38b. The two battery packs 16 located at the end of the insertion openings 20, i.e. the two battery packs 16 shown on the right in the x-direction and above one another in the y-direction in FIG. 2, each arranged with the first side 34a of the frame 32 on pretensioning unit 38a and with the second sides 34b of the frame 32 arranged on the further pretensioning unit 38b, and each with the further sides 34c, 34c of the frame 32 on a wall 40 delimiting the insertion opening 20. In this case, pretensioning unit 38a is designed to apply a pretensioning force F1 to the first side 34a of the frame 32 arranged thereon, which is shown schematically as an arrow extending in the direction opposite the x-direction. Similarly, the further pretensioning unit 38b is designed to apply a further pretensioning force F2 to the second side 34b of the frame 32 arranged thereon, which is shown schematically as an arrow extending in the x-direction, so that pretensioning force

[0044] F1 of pretensioning unit 38a and further pretensioning force F2 of further pretensioning unit 38b act in opposition to one another, as is shown by way of example for the battery pack 16 shown at the upper right in FIG. 2.

[0045] The pretensioning device 36 has a plate element 42a, which rests with a plate top over the entire surface on the first side 34a of the frame 32 and is arranged with a plate bottom on a pretensioned spring element 44. The at least one spring element 44 has a defined spring constant and, as an alternative or in addition, a defined spring characteristic which specifies pretensioning force F1 and further pretensioning force F2. As shown on the respective pretensioning unit 38b, the pretensioning device 36 in this case is connected to a further plate element 42b via the spring element 44, which is formed as three helical springs 46a. As an alternative or in addition, the pretensioning device 36 can be arranged directly on the battery housing 18, as shown for the respective pretensioning unit 38a. In this case, the battery pack 16 shown at the top right in FIG. 2 is fastened to the battery housing 18 via a flat spring 46b with a wavy cross-section (corrugated sheet), and the plate element 42a of the battery pack 16 shown at the bottom right is fastened to the battery housing via three further helical springs 46a.

[0046] Furthermore, the battery 14 comprises several separating elements 48 for thermal insulation. A respective separating element 48 can be positioned between two adjacent battery cells 22 in order to thermally insulate the two adjacent battery cells 22 from one another. Alternatively or additionally, separating elements 48 can each be arranged between a terminal one of the battery cells 22 and the frame 32 in order to thermally insulate the terminal one of the battery cells 22 and the frame 32 from one another. The separating elements 48 can each be present as a separate component 50 or can be integrated into the frame 32.

[0047] In a first step S1 of a method for producing the battery 14, the battery pack 16 is enclosed by means of the frame 32, so that the frame 32 at least partially covers each of the battery cells 22 on the shell surface 26 of the respective battery cell 22. In a second step S2 of the method, an assembly state of the pretensioning device 36 is set, the pretensioning unit 38a being pretensioned and fixed in such a way that an outwardly directed pretensioning force F1 is prevented before the pretensioning unit 38a is arranged inside the battery housing 18. The second step S2 of the method can be carried out before, after, or at the same time as the first step S1 of the method. In a third step S3 of the method, the enclosed battery pack 16 and the fixed pretensioning device 36 are arranged in the insertion opening 20 of the battery housing 18, the fixed pretensioning unit 38a adjoining a first side 34a of the frame 32. Alternatively or additionally, the further fixed pretensioning unit 38b can be arranged on the second side 34b of the frame 32, as shown in connection with the two battery packs 16 shown on the right in FIG. 2. In a fourth step S4 of the method, an operating state of the pretensioning device 36 arranged in the battery housing 18 is set. A fixation of the pretensioning unit 38a is released, in this case, so that the pretensioning force F1 is applied to the battery pack 16 on the first side 34a of the frame 32. If the further pretensioning unit 38a is also present, the further pretensioning force F2 on the second side 34b of the frame 32 can act in opposition to pretensioning force F1 of the pretensioning unit 38a by releasing the fixation thereof.

[0048] The improved design is based on the knowledge that the battery 14 for the motor vehicle 10, which is designed as a high-voltage battery, can currently have at least one cell module with a cell pack (battery pack 16). It is necessary that the design of at least one cell module has both a required pretension to withstand or compensate for a swelling force of the cell pack as well as thermal propagation protection, the latter being designed to prevent or delay thermal propagation of the cell pack. This can result in great effort in the manufacturing of the at least one cell module and a high weight of the battery 14 due to increased material requirements (e.g. module housing). Furthermore, due to the increased material requirement and increased manufacturing effort, the battery 14 can be cost-intensive and the design of the at least one cell module can be very complex with regard to swelling behavior over the service life of the battery 14.

[0049] The improved design is thus based on the idea that the cell pack can be inserted directly into a housing frame of the battery housing 18 in a simple support frame (frame 32). A required pretension (pretensioning force F1 and further pretensioning force F1) can be applied pretensioned over two respective plate elements 42a, 42b via the spring element 44. The required pretension can thus be set via the spring characteristic and swelling (“bulging”) of the battery cells 22 can be compensated for via the pretensioned spring element 44. This results in the advantage that the cell stack is easier to design and manufacture compared to the aforementioned at least one rigid cell module. The pretensioning force F1 and further pretensioning force F1 can also be set particularly flexibly and precisely over the service life of the battery 14. Furthermore, by omitting many module components (e.g. module housings), such a battery 14 can be manufactured particularly inexpensively, be light, and have small installation space requirements.

[0050] If rapid aging of the battery cells 22 is advantageous, the pretensioning device can also only comprise the pretensioning unit 38a, whereby an asymmetry in terms of stiffness that promotes aging can be provided, i.e. the battery housing 18 is stiffer than the plate element 40a with the spring element 44. In particular, there are two pretensioning units 38a, 38b in order to pretension the battery pack 16 and the battery cells 22 contained therein from both sides 34a, 34b with equally large pretensioning forces F1, F2.

[0051] Overall, the examples show how the battery 14 can be provided with the cell packs (battery packs 16) integrated into the battery frame, the cell packs being pretensioned via spring plates (plate elements 42a, 42b with at least one spring element 44).