DE102022130313A1 - Battery module with a pressure element for adjusting a cell stack tension and motor vehicle with a battery module - Google Patents

Abstract

The invention relates to a battery module (1; 10; 100) for motor vehicles, with a plurality of battery cells (2; 102) stacked along a stacking direction (x), and a pressure element (6; 16; 106) having an electric motor (210) and support elements (7; 17; 107) driven by the electric motor and extendable and retractable along the stacking direction (x), for setting a tensioning force acting on the battery cells (2; 102) in the stacking direction (x). In addition, a possible expansion path for the cell stack can also be set in this way. The invention also relates to a motor vehicle with such a battery module (1; 10; 100).

Description

The invention relates to a battery module with a pressure element for adjusting a cell stack tension. Furthermore, the invention relates to a motor vehicle with such a battery module.

Today's electrified motor vehicles have drive batteries for storing electrical energy, which have a large number of battery cells. These are often grouped into so-called modules, with each module having a stack of lithium-ion batteries stacked on top of each other and clamped together. If this structure, i.e. such a stack, is used for solid-state batteries, then the difficulty arises that the change in volume due to aging of the solid-state battery cells and during the individual charging cycles is much greater than with lithium-ion batteries. However, a significant change in the length of the stack is difficult due to installation space and fastening aspects in the vehicle.

From the EN 10 2021 102 550 A1 A battery module is known whose cell stack can be clamped by means of an adjustable cylinder device.

It is an object of the present invention to provide an alternative battery module with a pressure element for adjusting a cell stack tension. This object is achieved by a battery module according to claim 1 and a motor vehicle according to claim 10. Advantageous developments of the invention are the subject of the dependent claims.

According to one embodiment of the invention, a battery module for motor vehicles is provided, with a plurality of battery cells stacked together along a stacking direction, and a pressure element having an electric motor and support elements driven by the latter, which can be extended and retracted along the stacking direction, for setting a clamping force acting on the battery cells in the stacking direction. The electromotive adjustment enables both precise control of the clamping force and a possible expansion path for the cell stack to be set (which expansion path is made available to the cell stack during a charging cycle, for example). This is achieved with a compact installation space.

According to a further embodiment of the invention, the support elements can be extended and retracted by means of a spindle drive. The spindle drive enables precise power transmission from a single electric motor to a large number of support elements.

According to a further embodiment of the invention, the support elements are extendable and retractable telescopic cylinders. As a result, the support elements are particularly compact when retracted and require little installation space.

According to a further embodiment of the invention, the battery module is further equipped with a spindle that is coupled to the electric motor and can be driven by it, and a plurality of assembly gears that are in engagement with the spindle, wherein the assembly gears are connected in a rotationally fixed manner to a first thread and the support elements are connected to a second thread, so that a rotation of the assembly gears is translated into a translational movement of the support elements. This has the advantage of a precise power transmission from a single electric motor to a plurality of support elements.

According to a further embodiment of the invention, the support elements are divided into a first and a second group, wherein the support elements of the first group can be extended and retracted from one side of the pressure element and the support elements of the second group can be extended and retracted from an opposite side.

According to a further embodiment of the invention, the battery module is further equipped with a module frame which frames the plurality of battery cells and the support elements.

According to a further embodiment of the invention, the pressure element is arranged within the module frame.

According to a further embodiment of the invention, the pressure element forms a section of the module frame. This makes it possible to save on a separate pressure plate.

According to a further embodiment of the invention, the battery cells are solid-state battery cells. In the context of this invention, a solid-state battery cell is understood to mean a battery cell that at least partially uses a solid electrolyte for the lithium ion conduction between the anode and cathode (e.g. Al oxide, polymer or sulfide or combinations) or uses a lithium metal anode with liquid electrolyte. Combinations of Li anode and liquid/solid electrolyte are possible. This means that one speaks of a solid-state battery when part of a solid electrolyte or a Li anode is used.

Furthermore, the present invention provides a motor vehicle with such a battery module.

• 1 zeigt schematisch eine dreidimensionale Ansicht eines Batteriemoduls gemäß einem ersten Ausführungsbeispiel der Erfindung;
• 2 zeigt schematisch eine dreidimensionale Ansicht eines Batteriemoduls gemäß einem zweiten Ausführungsbeispiel der Erfindung;
• 3 zeigt schematisch eine dreidimensionale Ansicht eines Batteriemoduls gemäß einem dritten Ausführungsbeispiel der Erfindung;
• 4 zeigt im Detail ein Ausführungsbeispiel für einen Spindelantrieb zum Ein- und Ausfahren der Abstützelemente in einer dreidimensionalen Ansicht;
• 5 zeigt den Spindelantrieb aus 4 in einer Seitenansicht, und
• 6 zeigt den Spindelantrieb aus 4 in einer Draufsicht.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which:

• 1 shows schematically a three-dimensional view of a battery module according to a first embodiment of the invention;
• 2 shows schematically a three-dimensional view of a battery module according to a second embodiment of the invention;
• 3 shows schematically a three-dimensional view of a battery module according to a third embodiment of the invention;
• 4 shows in detail an embodiment of a spindle drive for extending and retracting the support elements in a three-dimensional view;
• 5 shows the spindle drive from 4 in a side view, and
• 6 shows the spindle drive from 4 in a top view.

1 shows a schematic three-dimensional view of a battery module 1 according to a first embodiment of the invention. The battery module 1 has a plurality of battery cells 2 stacked together in a stacking direction x, which thus form a cell stack. The battery cells 2 are stacked together in such a way that the sides with the largest surface area face or touch the adjacent battery cells 2. The battery cells 2 are rechargeable storage cells on an electrochemical basis, in particular solid-state battery cells. These could be cuboid-shaped, but in particular they have the shape of so-called pouch cells. In a pouch cell, an active material and an electrode are enclosed between layers of a flexible outer film and the edges of the outer film layers are connected to one another, for example welded. The battery cells 2 of the battery module 1 are electrically connected to one another in parallel and/or in series, for example by means of a cell contact plate (not shown).

An outer pressure plate 3 is arranged at each of the longitudinal ends of the battery module 1, relative to the stacking direction x. The outer pressure plates 3 are connected to one another via two tie rods 4, which run on both sides of the stacked battery cells 2 in the stacking direction x. The outer pressure plates 3 and the tie rods 4 are connected to one another in such a way that the outer pressure plates 3 essentially maintain a temporally constant distance in the stacking direction x. The connection can be made, for example, by means of a positive connection, e.g. hanging, screwing, or a material connection, e.g. welding.

The outer pressure plates 3 and the tie rods 4 together form a module frame within which the battery cells 2 are arranged. In addition, an inner pressure plate 5 is arranged within the module frame. In the exemplary embodiment shown, the inner pressure plate 5 is arranged at an end of the cell stack opposite one of the outer pressure plates 3, i.e. all of the battery cells 2 of the battery module 1 stacked on top of one another are arranged between the inner pressure plate 5 and one of the outer pressure plates 3. A pressure element 6 is arranged between the other outer pressure plate 3 and the inner pressure plate 5.

The pressure element 6 has several support elements 7 that can be extended and retracted in the stacking direction x by means of an electric motor. In particular, a single electric motor drives all support elements 7 per pressure element 6, in that the support elements 7 are coupled to the electric motor by means of a gear. In the exemplary embodiment shown, the support elements 7 are extendable and retractable cylinders. The support elements 7 can extend from a base body 8 from one side along the stacking direction x and additionally from an opposite side in an opposite direction. It is also possible for the support elements 7 to extend from only one of the two sides mentioned. By retracting the support elements 7, the support elements 7 are retracted on both opposite sides, so that a dimension of the pressure element 6 in the stacking direction x is reduced. By extending the support elements 7, the support elements 7 are extended on both opposite sides, so that a dimension of the pressure element 6 in the stacking direction x is increased. As the dimension in the stacking direction x of the pressure element 6 increases, the distance in the stacking direction x between the outer pressure plate 3 resting on the pressure element 6 and the inner pressure plate 5 is increased, so that the cell stack is braced in the stacking direction x with greater force, i.e. the force with which the individual battery cells 2 stacked next to one another are pressed together is increased. As the dimension in the stacking direction x of the pressure element 6 decreases, the distance in the stacking direction x between the outer pressure plate 3 resting on the pressure element 6 and the inner pressure plate 5 is reduced, so that the cell stack is braced in the stacking direction x with less force, i.e. the force with which the individual battery cells 2 stacked next to one another are pressed together is reduced.

In this way, the tension of the cell stack can be set and changed by electrically controlling the electric motor of the pressure element 6. This can be done, for example, depending on the aging of the battery cells 2 and/or the charge level of the battery cells 2. The aim can also be to keep the tension force in the stacking direction x constant regardless of the charge level and aging.

The inner pressure plate 5 can be a separate component from the pressure element 6, as in 1 shown, or it can be connected to the outwardly facing ends of the support elements 7, so that the inner pressure plate 5 moves with the retraction and extension of the support elements 7 (see 3 ).

An embodiment has been described above in which the pressure element 6 is arranged at one end of the battery module 1. However, it is also possible for battery cells 2 to be arranged on both sides of the pressure element 6 within the module frame, so that, for example, the pressure element 6 is arranged more centrally in the battery module 1.

2 shows a schematic three-dimensional view of a battery module 10 according to a second embodiment of the invention. To avoid repetition, only the differences from the first embodiment are described below and otherwise reference is made to the description of the first embodiment.

In the first embodiment, the module frame is formed by the two outer pressure plates 3 and the tie rods 4, with the pressure element being located within this module frame. In contrast, according to the second embodiment, a pressure element 16 forms a section of a module frame. As a result, the battery module 10 has only a single outer pressure plate 3, which is arranged at the end of the battery module 10 opposite the pressure element 16.

Thus, the module frame of the second embodiment is formed from the pressure element 16, the outer pressure plate 3 and the two tie rods 4. These elements are connected to one another as described in connection with the first embodiment.

The pressure element 16 also has a plurality of support elements 17 which can be extended and retracted in the stacking direction x by means of an electric motor. The support elements 17 are arranged only on one side of the pressure element 16, namely the side facing the battery cells 2.

The extendable and retractable support elements 17 are 2 about cylinders that can be extended and retracted telescopically. In particular, a single electric motor drives all support elements 17 per pressure element 16, in that the support elements 17 are coupled to the electric motor by means of a gear.

However, cylinders as described in connection with the first embodiment can also be used as support elements 17. Likewise, the telescopic cylinders described here can also be used as support elements 7.

3 shows a schematic three-dimensional view of a battery module 100 according to a third embodiment of the invention. To avoid repetition, only the differences from the first embodiment are described below and otherwise reference is made to the description of the first embodiment. The battery module 100 has a multiplicity of battery cells 102 stacked on one another in a stacking direction x, which are arranged in the form of two cell stacks 109, between which a pressure element 106 is arranged. The battery cells 102 are pouch cells. The pressure element 106 essentially corresponds to the pressure element 6, from which a plurality of support elements 107 are arranged so as to be extendable and retractable, which essentially correspond to the support elements 7.

In 3 The pressure element 106 is shown in the form of two separate components arranged next to each other, but it is self-explanatory that a continuous one-piece pressure element can also be provided.

In contrast to the first embodiment, inner pressure plates 105 are provided which are firmly connected to the outer ends of the support elements 107. The cell stacks 109 are thus each clamped between one of the outer pressure plates 3 and the inner pressure plates 105.

In 3 One half of the pressure element 106 is shown with the pressure elements 107 fully extended and the other half is shown with the pressure elements 107 fully retracted. However, this is only for illustrative purposes. In operation, the pressure elements 107 are all extended to the same extent.

The 4 to 6 show in detail an embodiment of a spindle drive or a spindle drive 200 for extending and retracting the support elements 107, which can of course also be used for the support elements 7 and 17.

A substantially cylindrical electric motor 210 can be operated in both clockwise and anti-clockwise rotation. At one longitudinal end, the electric motor 210 is provided with a gear 211 which is mounted in a rotationally fixed manner on a drive shaft 212 of the electric motor 210. The gear 211 driven by the electric motor 210 drives a gear 213 with which it is in engagement. The gear 213 can rotate about an axis of rotation which is parallel to the drive shaft 212. The gear 213 is in turn connected in a rotationally fixed manner to a cylindrical spindle 214 whose longitudinal axis is parallel to the drive shaft 212.

The spindle 214 is provided with an external spindle thread. On both sides of the package comprising the electric motor 210 and the spindle 214, a plurality of support element assemblies 215, 216 are arranged, each of which has a support element 107 and transmits the drive force coming from the electric motor 210 to these support elements 107. Each of the support element assemblies 215, 216 has an assembly gear 217 which is in engagement with the spindle 214. A rotation of the drive axis 212 of the electric motor 210 is transmitted to the spindle 214 via the gears 211 and 213. The rotation of the spindle 214 is transmitted into a rotation of the assembly gears 217. The assembly gears 217 are connected in a rotationally fixed manner to bushings 218, each of which is provided with a first thread, in particular an internal thread. A support element 107 is accommodated in each of the bushings 218, which is provided with a second thread, in particular an external thread, which engages with the first thread of the bushings 218. The assembly gears 217 and the bushings 218 are rotatably mounted by means of rolling bearings 219, in particular rotatably mounted relative to the pressure elements 6, 16 and 106. It is of course also possible for the first thread to be an external thread and the second thread to be an internal thread.

Thus, a rotation of the spindle 214 leads to a rotation of the gears 217, which in turn rotate the bushings 218. The rotation of the bushings 218 leads to a retraction and extension of the support elements 107 via the engaged internal and external threads, depending on whether the electric motor 210 is operated in a clockwise or anti-clockwise direction.

The support element assemblies 215 each have a 4 upwardly projecting support element 107, whereas the support element assemblies 216 have a 4 have a support element 107 projecting downwards.

The inner pressure plates 105 can be fastened to the support elements 107 by means of screws 220 which can be screwed into the outer ends of the support elements 107.

While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description is to be considered as exemplary and not restrictive, and it is not intended to limit the invention to the embodiment disclosed. The mere fact that certain features are recited in various dependent claims is not to suggest that a combination of these features could not also be used to advantage.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 102021102550 A1 [0003]

Claims (10)

Battery module (1; 10; 100) for motor vehicles, with a plurality of battery cells (2; 102) stacked together along a stacking direction (x), and a pressure element (6; 16; 106) having an electric motor (210) and support elements (7; 17; 107) driven by the electric motor and extendable and retractable along the stacking direction (x), for setting a tensioning force acting on the battery cells (2; 102) in the stacking direction (x). Battery module (1; 10; 100) according to Claim 1 , wherein the support elements (7; 17; 107) can be extended and retracted by means of a spindle drive (200). Battery module (10) according to one of the preceding claims, wherein the support elements (17) are extendable and retractable telescopic cylinders. Battery module (1; 10; 100) according to one of the preceding claims, with a spindle (214) which is coupled to the electric motor (210) and can be driven by it, and a plurality of assembly gears (217) which are in engagement with the spindle (214), wherein the assembly gears (217) are connected in a rotationally fixed manner to a first thread and the support elements (217) are connected to a second thread, so that a rotation of the assembly gears (217) is translated into a translational movement of the support elements (7; 17; 107). Battery module (1; 100) according to one of the preceding claims, wherein the support elements (7; 107) are divided into a first and a second group, wherein the support elements (7; 107) of the first group can be extended and retracted from one side of the pressure element (6; 106) and the support elements (7; 107) of the second group can be extended and retracted from an opposite side. Battery module (1; 10; 100) according to one of the preceding claims, with a module frame which frames the plurality of battery cells and the support elements (7; 17; 107). Battery module (1; 100) according to Claim 6 , wherein the pressure element (6; 106) is arranged within the module frame. Battery module (10) according to Claim 6 or 7 , wherein the pressure element (16) forms a portion of the module frame. Battery module (1; 10; 100) according to one of the preceding claims, wherein the battery cells (2; 102) are solid-state battery cells. Motor vehicle with a battery module (1; 10; 100) according to one of the Claims 1 until 9 .

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