Electrical energy storage with clamping unit

Abstract

The invention relates to an electrical energy storage device (4), in particular for a vehicle, having a plurality of electrically connected individual cells (6) arranged to form a cell stack (2) and having a pressure device (10) for exerting targeted pressure on the cell stack (2), wherein the pressure device (10) comprises two pressure plates (16), each of which lies flat against one end of the cell stack (2), a tensioning band (14, 14') which clamps the two pressure plates (16) and the cell stack (2) together in a circumferential manner, and a tensioning unit (12, 12') which is coupled to the tensioning band (14, 14') in order to tension or relax the latter.

Description

[0001] The invention relates to an electrical energy storage device for a vehicle having a housing in which a plurality of electrically connected individual cells arranged to form a cell stack and a pressure device for targeted pressure exertion on the cell stack are arranged.

[0002] Electrical energy storage devices typically expand when they are being charged or are in a state of full charge. They take up a smaller volume when they are being discharged or are in a state of full discharge. Due to such expansion tolerances, electrical energy storage devices are subjected to external mechanical pressure.

[0003] A solid-state battery unit is known from US 2023 / 0318052 A1. The solid-state battery unit comprises a battery module in which a plurality of solid-state battery cells are laminated, a pressure unit configured to apply pressure to the battery module, and a control unit configured to control the pressure unit. The control unit controls the pressure force of the pressure unit depending on the temperature of the battery module and the charge level of the battery module.

[0004] Alternative pressure units, for example, are designed as hydraulic systems. These have the disadvantage that, due to possible leaks, air or fluid can penetrate the interior of the energy storage device, which can lead to contamination or, in the case of moisture, corrosion or even electrical short circuits.

[0005] The invention is based on the object of providing an electrical energy storage device for a vehicle which is of simple construction and easily adjustable with regard to expansion tolerances.

[0006] Advantageous embodiments of the invention are the subject of the subclaims.

[0007] The object is achieved according to the invention with an electrical energy storage device having the features of patent claim 1.

[0008] The electrical energy storage device according to the invention comprises a plurality of electrically connected individual cells arranged to form a cell stack and a pressure device for targeted pressure exertion on the cell stack, wherein the pressure device comprises two pressure plates, each of which lies flat against a free end of the cell stack, a tensioning band that clamps the two pressure plates and the cell stack together circumferentially, and a tensioning unit that is coupled to the tensioning band in order to tension or relax it.

[0009] The advantages achieved by the invention are, in particular, that the pressure on the individual cells (also called battery cells) can be easily and robustly adjusted using the pressure device comprising a clamping unit with a coupled clamping band. Furthermore, such a design as a clamping unit with a clamping band saves space and weight and is optimized with regard to pressure adjustment.

[0010] For example, the tensioning unit can comprise a winding mechanism, in particular a tensioning roller (also called a roller or shaft for short). The tensioning unit can, in particular, have a passage through which the circumferential tensioning strap is or can be guided. Alternatively, both free strap ends of the tensioning strap can be or can be fastened to the tensioning unit.

[0011] In one possible embodiment, the tensioning pulley is rotatably mounted, wherein a rotational movement of the tensioning pulley in a first direction of rotation tensions the tensioning band and a rotational movement of the tensioning pulley in a second direction of rotation opposite to the first direction of rotation relaxes the tensioning band. In particular, the rotation of the tensioning pulley occurs as a function of a current state of charge (also called State of Charge or SoC for short) of the electrical energy storage device, in particular of the individual cells and / or as a function of a pressure acting on the cell stack or the individual cells, wherein the at least one tensioning band is at least partially "rolled in" or "rolled up" and thus tensioned or "shortened" or alternatively "rolled out" or "unrolled" and thus relaxed and "lengthened". In particular when the tensioning band is shortened, corresponding pressure is exerted on the individual cells or on the cell stack of the individual cells.

[0012] Multiple tensioning straps can be provided. If multiple tensioning straps are provided, these can be arranged parallel, one above the other, or side by side, and can be arranged completely encircling the individual cells or the cell stack. The tensioning strap(s) can be made of a flexible material. For example, the respective tensioning strap can be made of metal, in particular a spring sheet, or of another suitable flexible material, in particular a high-strength woven textile material or a high-strength, fiber-woven plastic material, or another suitable material combination.

[0013] The respective clamping band can be extremely thin, especially in the millimeter range. This allows the clamping unit to require little installation space and be particularly lightweight.

[0014] The respective tensioning strap can also be made of different materials in certain areas. For example, a first strap section, which is rolled up or unrolled and / or deflected, can be made of a high-strength yet highly flexible textile material. A second strap section, which runs along the electrical energy storage device, particularly laterally to the individual cells or the cell stack of individual cells and the pressure plates (also called end plates), can be made of steel or another solid material, for example.

[0015] The respective tensioning strap (also called a pull strap) can be designed to vary its dimensions, particularly its width and / or thickness, and / or the number of tensioning straps. In particular, the specified number of tensioning straps can be used to adjust and ensure the strength required to exert the appropriate pressure.

[0016] The tensioning unit comprises, in particular, a winding mechanism, which is formed, for example, from a roller, in particular a shaft (also referred to as a tension roller or tension shaft). For example, the two free ends of the respective tensioning band can be attached to the roller. Alternatively, the tensioning band can be guided through this roller as an endless band. This roller / shaft can be connected to a controllable drive unit. For example, the roller / shaft can be connected to a worm gear, which in turn is connected to a corresponding worm, which is driven, for example, by an electric motor.Such a worm drive with a worm gear allows for correspondingly high transmission ratios, which means that high torques can be applied to the roller / shaft and thus to the tensioning band(s) at relatively low drive power levels. This results in a correspondingly high compressive force on the individual cells or the cell stack when the tensioning band(s) are tightened via the practical "shortening." Ideally, the electric motor operates at the same voltage level as the on-board electrical system of a higher-level overall electrical system.

[0017] In summary, the pressure device can be arranged in a housing of the electrical energy storage device with a relatively optimized installation space. The pressure device can efficiently exert pressure on the cell stack, whereby the pressure, in particular the contact force, can be easily adjusted via the adjustable drive unit and the clamping unit coupled to it. Due to its simple design, the pressure device is robust.

[0018] Embodiments of the invention are explained in more detail below with reference to drawings.

[0019] Showing: Fig. 1 schematically shows a comparison between a cell stack of an electrical energy storage device arranged in a housing with fully charged individual cells and a cell stack arranged in a housing with half-charged individual cells, Fig. 2 schematically shows in section an electrical energy storage device with a pressure device comprising a clamping unit and at least one clamping band, Fig. 3 schematically shows an enlarged section of the Fig. 2 in a corner area of ​​the electrical energy storage unit, Fig. 4 schematically shows an alternative embodiment for the corner area of ​​the electrical energy storage device, Fig. 5 shows a schematic sectional view of an electrical energy storage device with an alternative pressure device comprising an alternative clamping unit and at least one clamping band, Fig. 6 schematically shows an enlarged sectional view of the clamping unit according to Fig. 5, Fig. 7 shows a schematic representation of the coupling of the clamping unit with a drive unit designed as a worm drive, and Fig. 8 shows a schematic sectional view of an electrical energy storage device with an alternative pressure device according to Fig. 2 and an alternative guidance of at least one tensioning strap in corner areas of the energy storage device.

[0020] Corresponding parts are provided with the same reference numerals in all figures.

[0021] Fig. 1 schematically shows a comparison between a cell stack 2 of an electrical energy storage device 4 arranged in a housing 1 with largely fully charged individual cells 6 (for example 100% SoC) and, for example, half-charged individual cells 6 (for example 50% SoC) and a resulting change in size 8, in particular a change in length due to an expansion of the individual cells 6 in the fully charged state.

[0022] The electrical energy storage device 4 is, in particular, a traction battery of an electric vehicle, a hybrid vehicle, or a fuel cell-powered vehicle, wherein the individual cells 6 can be, for example, solid electrolyte cells. Such individual cells 6 expand during electrical charging and decrease in volume when discharged. It is important that, regardless of the respective state of charge (SOC) of the individual cells 6, a certain pressure is exerted on the individual cells 6, in particular on their flat sides.

[0023] In the Fig. In the comparison shown in Figure 1 of the two cell stacks 2 arranged in the housing 1, the individual cells 6 shown on the left have a state of charge (SOC) of 100 percent, while the individual cells 6 of the same electrical energy storage device 4 shown on the right have a state of charge (SOC) of 0 percent. The resulting change in size 8 is also shown. If the individual cells 6 are charged, the spatial volume increases or is larger than that of less or uncharged individual cells 6.

[0024] Fig. Figure 2 shows a schematic sectional view of the electrical energy storage device 4 with a pressure device 10 according to the invention for exerting targeted pressure on the cell stack 2. The pressure device 10 is designed to be efficient, space- and weight-optimized. The pressure device 10 can be used to adjust a contact force with respect to the individual cells 6 of the cell stack 2.

[0025] The printing device 10 comprises at least one clamping unit 12 and at least one clamping band 14. The printing device 10 further comprises at least two printing plates 16, each of which rests flatly against a front stack end 2.1, 2.2 of the cell stack 2.

[0026] The clamping band 14 is arranged circumferentially around the two pressure plates 16 and the cell stack 2 and is configured to clamp the pressure plates 16 and the cell stack 2 together. For this purpose, the clamping unit 12 is coupled to the circumferential clamping band 14 in order to tension or release it.

[0027] By means of the pressure device 10 comprising the clamping unit 12 with coupled clamping band 14, pressure on the individual cells 6 (also called battery cells) or the cell stack 2 with the individual cells 6 can be easily and robustly adjusted.

[0028] For example, the tensioning unit 12 can comprise a winding mechanism 18, in particular a tensioning roller 20 (also referred to as a roller or shaft for short). Free band ends 14.1, 14.2 of the circumferential tensioning band 14 are attached to the tensioning unit 12, in particular attached laterally.

[0029] For example, the tensioning roller 20 is rotatably mounted, wherein a rotational movement of the tensioning roller 20 in a first direction of rotation 100 tensions the tensioning band 14 and a rotational movement of the tensioning roller 20 in a second direction of rotation 102 opposite to the first direction of rotation 100 relaxes the tensioning band 14.

[0030] In particular, the rotation of the tensioning roller 20 occurs depending on a current state of charge SOC of the electrical energy storage device 4, in particular of the individual cells 6, and / or a pressure acting on the cell stack 2, wherein the at least one tensioning band 14 is "rolled in" or "rolled up" at least in some areas and thus tensioned or "shortened," or alternatively "rolled out" or "unrolled" and thus relaxed and "lengthened." In particular, when the tensioning band 14 is shortened, corresponding pressure is exerted on the individual cells 6 or on the cell stack 2 of the individual cells 6.

[0031] Alternatively, multiple tensioning straps 14 can be provided. If multiple tensioning straps 14 are provided, these can be arranged parallel, one above the other, or side by side, and can be arranged to completely surround the individual cells 6 or the cell stack 2. The tensioning strap 14 or straps 14 can be formed from a flexible material. For example, the respective tensioning strap 14 can be formed from metal, in particular a spring sheet, or from another suitable flexible material, in particular a high-strength woven textile material or a high-strength plastic material woven from fibers, or another suitable material combination.

[0032] The respective clamping band 14 can be extremely thin, particularly in the millimeter range. This allows the printing device 10 to require little space and be particularly lightweight.

[0033] The respective tensioning strap 14 can also be formed from different materials in certain areas. For example, a first strap section 14.3, which is rolled up or unrolled and / or deflected, can be formed from a high-strength yet very flexible textile material. A second strap section 14.4, which extends in certain areas, particularly laterally, around, for example, the electrical energy storage device 4, in particular the individual cells 6 or the cell stack 2 composed of individual cells 6 and the pressure plates 16 (also called end plates), can be formed, for example, from steel or another solid material.

[0034] The respective tensioning band 14 (also called a tension band) can be designed to be variable in terms of dimensions, in particular width and / or thickness, and / or the number of tensioning bands 14. In particular, the strength of the pressure device 10 can be adjusted via the predetermined number of tensioning bands 14, thus ensuring how many tensioning bands 14 are required to exert the corresponding pressure.

[0035] The tensioning unit 12 comprises, in particular, the tensioning roller 20 (also referred to as roller, shaft or tensioning shaft) as a winding mechanism 18. For example, the two free band ends 14.1, 14.2 of the respective tensioning band 14 can be fastened to the tensioning roller 20. Alternatively, the tensioning band 14 can be guided through this tensioning roller 20 as an endless band (shown in Fig. 5 and Fig. 6).

[0036] In summary, Fig. 2 a basic structure of the described pressure device 10. By rotating the tension roller 20, which is rotatably mounted in the housing 1, the tension band 14 is shortened, which leads to the two pressure plates 16 exerting pressure on the individual cells 6 or the cell stack 2 of the individual cells 6 indirectly via an optional support plate 22 and / or an optional support roller 24 or directly.

[0037] The rotational movement, in particular a resulting angular adjustment in some areas, of the tension roller 20 takes place here as a function of the state of charge (SOC) of the electrical energy storage device 4, in particular of the cell stack 2, and / or the pressure exerted and detectable thereon, so that the optimal pressure on the individual cells 6 is or can be set and exerted depending on the state of charge (SOC) and / or the pressure force applied. In order to be able to optimally adjust the ideal pressure or the ideal contact force, a sensor 26, in particular a pressure sensor, a force sensor, a strain gauge strip or the like, can be provided, which is arranged and fastened, for example, at a suitable position on the pressure device 10.

[0038] The sensor 26 generates a corresponding sensor signal, by means of which the tensioning unit 12 can then be adjusted or regulated in order to tension or relax the tensioning band 14 accordingly.

[0039] Fig. 3 shows schematically an enlarged section of the Fig. 2 in a corner area 28 of the electrical energy storage device 4.

[0040] The electrical energy storage 4 according to Fig. 3 differs from the electrical energy storage 4 according to Fig. 2 only in the corner area 28, in which the tensioning band 14 is guided or applied along the pressure plate 16 during tensioning or untensioning. The corner area 28 is characterized by a corresponding bevel 16.1 of the pressure plate 16. The bevel 16.1 ensures that the tensioning band 14 is deflected in the corner area 28 with as little friction and wear as possible.

[0041] Instead of a bevel 16.1, the corner region 28 can also be formed by a radius, arc, or a combination of bevels and different radii. Additionally, in this corner region 28, the pressure plate 16 can have a sliding surface, in particular sliding or running surfaces made of suitable sliding materials, so that the clamping band 14 can be guided with as little friction and wear as possible during tensioning or untensioning. This leads to less force required and to an increased service life and durability of the clamping unit 12 (also called the clamping mechanism).

[0042] The bevel 16.1 is in Fig. 3 is shown by way of example only at one of the four corner regions 28 of the electrical energy storage device 4. In principle, however, this would be implemented or applied to all corner regions 28 and / or sliding regions of the electrical energy storage device 4 in which the tensioning band 14 touches other components or housing regions or is guided along them. As special materials in the respective component regions along which the tensioning band 14 is guided, these component regions can be formed from a corresponding sliding material. For example, these component regions can be formed from brass or bronze or the like. Plastics, such as polyamide, or coatings, such as Teflon, can also be provided in these component regions, in particular housing regions and / or plate regions. As a result, the electrical energy storage device 4 has good sliding properties in some regions on the outside.

[0043] Fig. 4 schematically shows an alternative embodiment for the corner region 28 of the electrical energy storage device 4.

[0044] The electrical energy storage 4 according to Fig. 4 differs from the electrical energy storage 4 according to Fig. 2 or Fig. 3 only in the corner region 28, in which the tensioning band 14 is guided or applied indirectly along the pressure plate 16 via a deflection element 30, in particular a round element, during tensioning or untensioning. The deflection element 30 ensures that the tensioning band 14 is deflected in the corner region 28 with as little friction and wear as possible.

[0045] The deflection element 30 can, for example, be a fixed cylindrical pin or bolt made of a sliding material, in particular of a metal, for example of steel, brass, bronze or the like, or of a plastic or even graphite.

[0046] The material used for the deflection element 30 depends in particular on the material of the tensioning band 14. Therefore, the appropriate material combination for the tensioning band 14 and the deflection element 30 must be selected so that the tensioning band 14 is guided with particularly low wear and friction. Alternatively, the deflection element 30 can also be designed as a small, easily disassembled roller bearing, which runs with particularly low wear and virtually frictionless operation.

[0047] The deflection elements 30 can be provided and arranged, in particular fastened, at all deflection points on the outer circumference of the electrical energy storage device 4.

[0048] Fig. 5 shows a schematic sectional view of the electrical energy storage device 4 with an alternative pressure device 10', which comprises an alternative clamping unit 12' and the at least one alternative clamping band 14'. Fig. 6 shows schematically an enlarged sectional view of the clamping unit 12' according to Fig. 5.

[0049] The clamping unit 12 can in particular have a passage 12.1 through which the circumferential clamping band 14' is or is guided.

[0050] In other words: The tensioning band 14' is not attached to the tensioning unit 12, in particular the tensioning roller 20, but is guided through it. This can be done via the passage 12.1 in the tensioning roller 20 (= shaft or roller), which is designed as an opening or groove. The advantage here is that so-called endless bands can be used as an alternative tensioning band 14', which are particularly robust and can therefore contribute to longevity. If a material combination is used for the tensioning bands 14', it is advisable to use a flexible textile band in the area of ​​the tensioning band 14', which is then wound onto the tensioning roller 20 during tensioning, due to its flexibility. In addition, it can be provided to guide the tensioning band 14' in the slot-shaped passage 12.1 through the pressure plate 16 if this can be considered advantageous for certain reasons.

[0051] Fig. Figure 7 shows a schematic illustration of the coupling of the clamping unit 12, 12' to a drive unit 32 configured as a worm drive. The clamping unit 12, 12', in particular its tensioning roller 20 or tensioning shaft, can be connected to a controllable drive unit 32. For example, the tensioning roller 20 can be connected to a worm gear 32.1, which in turn is connected to a corresponding worm 32.2, which is driven, for example, by an electric motor 32.3.Such a worm drive with a worm gear allows correspondingly high transmission ratios to be achieved, which means that, at relatively low drive power levels, high torques can be applied to the tension pulley 20 and thus to the tensioning band 14, 14' or the tensioning bands 14, 14', resulting in a correspondingly high compressive force on the individual cells 6 or the cell stack 2 when the tensioning band 14, 14' or the tensioning bands 14, 14' are tightened via the practical "shortening." The electric motor 32.3 is ideally at the same voltage level as the on-board electrical system voltage of a higher-level overall on-board electrical system.

[0052] Fig. 7 shows an enlarged view of the drive unit 32 and its coupling with the tensioning unit 12, 12', in particular the tensioning roller 20, which is driven by the corresponding structure of worm wheel 32.1 and worm 32.2 by means of the electric motor 32.3.

[0053] The drive unit 32 and the clamping unit 12, 12' can be mounted on the pressure plate 16 and / or on the housing 1 (shown in Fig. 2) of the electrical energy storage device 4.

[0054] Fig. Figure 8 shows a schematic sectional view of the electrical energy storage device 4 with the pressure device 10 according to Fig. 2 and an alternative guidance of at least one tensioning strap 14 in the corner regions 28 of the energy storage device 4.

[0055] The circumferential tensioning belt 14 is or will be deflected by deflection elements 30, in particular rollers, bolts, pins, shafts, round elements, or the like. The geometric arrangement, size / diameter, and number of these deflection elements 30 can be used to tailor the force distribution and force introduction, depending on the stiffness and strength of the pressure plates 16, to the requirements of the respective cell type of the cell stack 2.

[0056] Instead of one support roller 24, two support rollers 24 can be provided on the outside of one of the pressure plates 16 for deflecting and guiding the tensioning belt 14. On the outside of the opposite pressure plate 16, the support plate 22 can be arranged between the pressure plate 16 and the tensioning unit 12. List of reference symbols 1 housing 2 cell stacks 2.1, 2.2 End of stack 4 electrical energy storage 6 single cells 8 Resizing 10, 10' printing device 12, 12' clamping unit 12.1 Implementation 14, 14' tension strap 14.1, 14.2 free end of tape 14.3 first band area 14.4 second band area 16 printing plate 16.1 Bevel 18 Winding mechanism 20 tension pulley 22 support plate 24 support roller 26 Sensor 28 Corner area 30 deflection element 32 drive unit 32.1 Worm gear 32.2 Snail 32.3 Electric motor 34 Bracket 100 first direction of rotation 102 second direction of rotation SOC state of charge QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2023 / 0318052 A1

[0003]

Claims

[1] Electrical energy storage device (4), in particular for a vehicle, with a plurality of electrically connected individual cells (6) arranged to form a cell stack (2) and with a pressure device (10) for the targeted application of pressure to the cell stack (2), characterized by that the pressure device (10) comprises two pressure plates (16), each of which lies flat against one end of the cell stack (2), a tensioning band (14, 14') which clamps the two pressure plates (16) and the cell stack (2) together in a circumferential manner, and a tensioning unit (12, 12') which is coupled to the tensioning band (14, 14') in order to tension or relax it. [2] Electrical energy storage device (4) according to claim 1, characterized by that the tensioning unit (12, 12') comprises a winding mechanism (18) which is designed in particular as a tensioning roller (20). [3] Electrical energy storage device (4) according to claim 2, characterized bythat the clamping unit (12, 12') has a passage (12.1) through which the circumferential clamping band (14') is guided or can be guided. [4] Electrical energy storage device (4) according to claim 2 or 3, characterized by in that the tensioning roller (20) is rotatably mounted, wherein a rotational movement of the tensioning roller (20) in a first direction of rotation (100) tensions the tensioning band (14, 14') and a rotational movement of the tensioning roller (20) in a second direction of rotation (102) opposite to the first direction of rotation (100) relaxes the tensioning band (14, 14'). [5] Electrical energy storage device (4) according to one of claims 2 to 4, characterized by that a rotational movement of the tensioning roller (20) can be controlled as a function of detected pressure signals from at least one sensor (26) and a contact pressure of the pressure plate (16) on the cell stack (2) determined therefrom. [6] Electrical energy storage device (4) according to one of the preceding claims, characterized bythat the tensioning band (14, 14') is made of a flexible textile material.

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