Electrical energy storage device with pressure device

Abstract

The invention relates to an electrical energy storage device (4), in particular for a vehicle, comprising a plurality of electrically interconnected individual cells (6) arranged in a cell stack (2) and a pressure device (10) for applying targeted pressure to the cell stack (2), wherein the pressure device (10) comprises at least one pressure plate (14) which rests flat against one end of the cell stack (2) and a length-adjustable pressure plunger (12) which rests against or engages the pressure plate (14) on a plate surface (18) facing away from the cell stack.

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 charge. 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 a pressure force of the pressure unit depending on a temperature of the battery module and a charge level of the battery module.

[0004] Alternative pressure units are designed, for example, as hydraulic and / or pneumatic 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] The object is achieved according to the invention by an electrical energy storage device having the features of patent claim 1.

[0007] Advantageous embodiments of the invention are the subject of the subclaims.

[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 exerting targeted pressure on the cell stack, wherein the pressure device comprises at least one pressure plate which lies flat against one end, in particular the front end, of the cell stack, and a length-adjustable pressure stamp which lies against or engages the pressure plate on a plate surface facing away from the cell stack.

[0009] For example, the length-adjustable pressure stamp can be designed as a telescopic shaft with a number of nested and length-adjustable sleeves, in particular threaded sleeves. In this case, the optimal pressure can be exerted on the cell stack with the individual cells (also called battery cells), in particular depending on the corresponding state of charge (SoC), via the sleeves, in particular threaded sleeves, which are arranged one inside the other. These can, for example, be constructed such that a first threaded sleeve is mounted in or on the cell stack and / or on the battery housing in such a way that this first threaded sleeve is rotatable but not displaceable in the longitudinal direction. This first threaded sleeve has, for example, an external thread on its outer surface. A second threaded sleeve (with a correspondingly larger diameter) is then arranged on the external thread of the first threaded sleeve.The second threaded sleeve has an internal thread that corresponds to the external thread of the first threaded sleeve. If the first threaded sleeve, which is not movable in its longitudinal direction, is then rotatably driven, for example by a drive unit, in particular an electric drive motor, the second threaded sleeve, which is in particular firmly connected to the pressure plate that compresses the cell stack of individual cells or exerts pressure on it, is moved accordingly in the longitudinal direction by the coupled threads of both threaded sleeves. This movement then exerts corresponding pressure on the cell stack of individual cells. This allows the expansion of the individual cells to be compensated accordingly.Instead of two threaded sleeves, three or more threaded sleeves can also be provided, with a first outermost threaded sleeve always being rotatable and not longitudinally movable and the other threaded sleeves being rotatable and longitudinally movable, with a second outermost threaded sleeve being firmly connected to the pressure plate.

[0010] The energy storage device can also comprise multiple cell stacks, wherein the pressure device can have a number of pressure plungers corresponding to the number of cell stacks for even distribution of the compressive force acting on the cell stack. Alternatively, multiple pressure devices can be provided for a single cell stack for a correspondingly even pressure distribution and / or individual pressure adjustment. Preferably, if there are multiple pressure plungers, these are coupled to one another for movement, for example, via a transmission, in particular a gear transmission.

[0011] In order to keep the so-called “dead space” for the arrangement of the expansion compensation or tolerance compensation of the pressure device (also called contact pressure device) as small as possible, it is of course advantageous in principle to choose the number of threaded sleeves as large as possible so that they require as little “dead space” as possible in the “retracted” state.

[0012] For example, a "dead space" of 100 mm can be provided. This means that the first threaded sleeve can occupy a dead space of 100 mm. When retracted, the second threaded sleeve can be completely "slid" or "screwed" onto the first threaded sleeve. The second sleeve can also be 100 mm long. Theoretically, this results in a linear expansion of 100 mm with a dead space of 100 mm.

[0013] However, if this is achieved with three threaded sleeves, a theoretical linear expansion of 200 mm with a dead space of 100 mm is possible. These ratios become increasingly optimal the more threaded sleeves are used, which can essentially be slid over one another. However, this naturally has practical limitations, such as the fact that the threaded sleeves cannot be made arbitrarily thin, as they must also have sufficient mechanical strength to exert the necessary pressure on the pressure plate to compress the cell stack. Furthermore, more threaded sleeves also mean increased manufacturing effort. This, unfortunately, is associated with higher costs. In practice, an appropriate optimum must be selected here.

[0014] A particular advantage of this arrangement is that the ratio between "dead space" and expansion length can be greatly optimized, making the arrangement as a whole very space-saving. This not only saves space but also has corresponding weight advantages. Another key benefit is that the mechanical components make the design relatively simple and very robust, thus ensuring a long service life. A further advantage is that the pressure and / or length of the expansion compensation can be adjusted very precisely, which is beneficial for the operation and longevity of the individual cells. Due to the simple and robust design, the overall susceptibility to failure is particularly low. This allows the pressure device for compensating for linear expansion to be located within the battery casing, where it is protected.

[0015] Embodiments of the invention are explained in more detail below with reference to drawings.

[0016] 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 a schematic representation of an electrical energy storage device with a pressure device comprising a length-adjustable pressure stamp in the extended state, Fig. 3 a schematic representation of an electrical energy storage device with the pressure stamp in the partially extended or partially retracted state, Fig. 4 a schematic representation of an electrical energy storage device with the pressure piston in the fully retracted state, Fig. 5 a sectional view of a length-adjustable pressure stamp, Fig. 6 a plan view of a drive unit for the printing device, Fig. 7 a sectional view of a length-adjustable pressure stamp with a drive unit coupled via a gear.

[0017] Corresponding parts are provided with the same reference numerals in all figures.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] Fig. 2 shows a schematic representation of the electrical energy storage device 4 (shown in Fig. 1) with a printing device 10, comprising a length-adjustable printing stamp 12 in an extended state 100.

[0022] The pressure device 10 is designed to exert targeted pressure on the cell stack 2 (shown in Fig. 1). The printing device 10 comprises at least one printing plate 14, which rests flat against one end of the cell stack 2, and the length-adjustable printing stamp 12, which rests or engages the printing plate 14 on a plate surface 18 facing away from the cell stack.

[0023] The length-adjustable pressure stamp 12 is designed, for example, as a telescopic shaft 20. The telescopic shaft 20 comprises, for example, at least two sleeves 20.n that are telescopically nested and adjustable in length relative to one another. In the example, three sleeves 20.1 to 20.3 are shown, of which a first sleeve 20.1 is stationary (not longitudinally movable or longitudinally adjustable) and rotatable, and a second sleeve 20.2 and a third sleeve 20.3 are longitudinally movable or longitudinally adjustable and rotatable.

[0024] In particular, the sleeves 20.n are designed as threaded sleeves. The sleeves 20.n can additionally be provided with guide rails 22 and / or guide grooves 24 (shown in Fig. 5) be guided so as to be longitudinally movable relative to each other.

[0025] Fig. 2 to 4 show the basic structure of the pressure device 10, designed as a length-adjustable pressure stamp 12, in three different phases of the state of charge SOC of the energy storage device 4 (also called battery) with the corresponding different dimensions. Fig. 2 shows the extended state 100 resulting from a lowest state of charge SOC.

[0026] Fig. 3 shows a schematic representation of the electrical energy storage device 4 with the pressure stamp 12 in a partially extended or partially retracted state 102.

[0027] The energy storage device 4 has a charge level of 100% compared to the state of charge SOC according to Fig. 2 has a higher state of charge SOC, ie the individual cells 6 have expanded corresponding to the state of charge SOC.

[0028] The energy storage device 4 can have a sensor 26, for example a pressure sensor, a strain gauge, a strain sensor, or the like. The sensor 26 measures, for example, the pressure and transmits this measured value to a control unit or a computer unit (not shown), which, based on the measured value, determines an optimal extension length of the length-adjustable pressure piston 12, which is designed, for example, as a threaded sleeve arrangement, and generates a control signal for a drive unit 28 (shown in Fig. 5) is generated.

[0029] Fig. 4 shows a schematic representation of the electrical energy storage device 4 with the pressure piston 12 in the fully retracted state 104.

[0030] The energy storage device 4 is almost fully charged and the pressure piston 12 is almost completely retracted.

[0031] Due to its design, the previously described printing device 10 has a so-called dead space 9, which is created in the housing 1, in particular the battery housing, and which should be kept as small as possible. In order to keep this dead space 9 as small as possible, it is advantageous to select the number of sleeves 20.n as large as possible, so that in the retracted state 104 (shown in Fig. 4) require the smallest possible dead space 9.

[0032] Fig. Figure 5 shows a sectional view of the length-adjustable pressure stamp 12 with drive unit 28. The drive unit 28 is coupled on the output side to the pressure stamp 12 for its longitudinal adjustment. A gear 30 can be arranged between the drive unit 28 and the pressure stamp 12 (shown in Fig. 6 and Fig. 7).

[0033] In particular, the first sleeve 20.1 is designed as a threaded sleeve and coupled to the drive unit 28.

[0034] The drive unit 28 is, for example, a worm drive. The drive unit 28 comprises a worm gear 28.1, which is connected to the first sleeve 20.1. The worm gear 28.1 is coupled on the drive side to a worm 28.2, which in turn can be driven by an electric drive motor 28.3 and moved accordingly.

[0035] Due to a high gear ratio in the drive unit 28, which is designed as a worm drive optionally with a gear 30, high contact forces on the pressure plate 14 for pressing the pressure plate 14 onto the cell stack 2 (shown in Fig. 1 to 4). This allows a smaller and correspondingly more cost-effective electric drive motor 28.3 to be selected.

[0036] The sleeves 20.1 to 20.3 are designed, for example, as threaded sleeves. The sleeves 20.1 to 20.3 have, for example, corresponding threads 32, in particular internal threads 32.1 and / or external threads 32.2. High transmission ratios can also be achieved by using small thread pitches of the threads 32 of the sleeves 20.1 to 20.3.

[0037] Furthermore, a locking mechanism 34 may be provided, which is designed, for example, as a latch mechanism 36. The latch mechanism 36 comprises, on the one hand, a latch receptacle 36.1, for example, a latch groove or a latch opening or the like, and, on the other hand, a latch 36.2, which, in a locked state, engages in the latch receptacle 36.1 in a locking manner.

[0038] The respective latch 36.2 is mounted, in particular, on a front side of the respective sleeves 20.1 to 20.2, in particular in a movable manner, for example pivotable. The respective latch 36.2 can be spring-loaded.

[0039] The sleeves 20.2 to 20.3 have corresponding latch receptacles 36.1. The respective latch 36.2, in combination with the latch receptacle 36.1 when engaged with each other, serves to prevent the respective sleeves 20.2 to 20.3 from being completely unscrewed, but allows longitudinal adjustment relative to each other when they are disengaged.

[0040] In other words, the respective pawl 36.2 engages with the pawl receptacle 36.1, preventing the sleeves 20.2 and 20.3 from being rotated further apart. The pawl 36.2 and the pawl receptacle 36.1 are designed such that the pawl 36.2 locks in the direction of rotation in which the sleeves 20.2 and 20.3 can be rotated apart, and in the opposite direction of rotation, the pawl 36.2 does not lock the sleeves 20.2 and 20.3, allowing them to be adjusted longitudinally.

[0041] The second sleeve 20.2, especially all "middle" threaded sleeves of the telescopic shaft 20 with more than three threaded sleeves, has an internal thread 32.1 that matches the external thread 32.2 of the first sleeve 20.1. Furthermore, the second sleeve 20.2 has an external thread 32.2 that matches the internal thread 32.1 of the third sleeve 20.3.

[0042] A latch 36.2 is attached to the respective end face of the first sleeve 20.1 and the second sleeve 20.2, which then engages in the latch receptacle 36.1 of the adjacent second sleeve 20.2 or the third sleeve 20.3.

[0043] Furthermore, the third sleeve 20.3, which engages the pressure plate 14, can have the guide groove 24, in particular a longitudinal groove. Alternatively or additionally, instead of the guide groove 24, a guide rail 22, in particular a longitudinal rail, can be formed on the third sleeve 20.3.

[0044] The guide groove 24 and the guide rail 22 can be configured to correspond to one another. For example, the guide rail 22, which is connected to the housing 1 or formed on its inside, can engage in this guide groove 24, or vice versa. This prevents the rotational movement of the third sleeve 20.3, or the corresponding torque is supported here, and the third sleeve 20.3 is guided in its longitudinal direction.

[0045] Fig. 6 shows a plan view of a drive unit 28 for the printing device 10.

[0046] Depending on the size of the energy storage device 4, several pressure devices 10 can be provided in order to achieve, in particular, an even distribution of the contact pressure or the required contact force on the cell stack 2.

[0047] The plurality of pressure devices 10, in particular designed as pressure stamps 12, are preferably arranged in parallel. The respective pressure stamp 12 is adjustable in length and, as previously described, is designed as a telescopic shaft 20. Fig. 6 shows the longitudinally movable and non-rotatable third sleeve 20.3 of the respective telescopic shaft 20, which is mounted in the housing 1 via the guide rail 22 in guide grooves 24. A pair of guide rails 22 and guide grooves 24 can be provided for each third sleeve 20.3, which are opposite one another.

[0048] Fig. 6 shows the arrangement viewed from the front side of the pressure plate 14, in the configuration when several telescopic shafts 20, designed as threaded sleeves inserted into one another in a telescopic manner, are arranged quasi-parallel.

[0049] The guide grooves 24, designed as longitudinal grooves, are formed on the outside in the walls of the sleeves 20.n (shown in Fig. 2). The guide rails 22 are firmly connected to the housing 1. The guide grooves 24 and the guide rails 22 enable the respective sleeves 20.n to be guided parallel, thus exerting uniform pressure on the pressure plate 14.

[0050] In order for the three length-adjustable pressure stamps 12 shown as examples, designed as telescopic shafts 20, to move synchronously, they are mechanically connected to one another and coupled in movement, for example via the gear 30 designed as a gear arrangement, for example.

[0051] For example, the electric drive motor 28.3 can only drive the worm 28.2 and the worm wheel 28.1 (each shown in Fig. 5) of the middle pressure ram 12. The two outer pressure rams 12 are mechanically connected via meshing gears 30.1. In particular, the rotatable first sleeves 20.1 (shown in Fig. 5) are each vertically coupled to one of the gears 30.1, which in turn are horizontally coupled in motion via the intermeshing gears 30.1. For example, the gear 30.1 of the middle pressure ram 12 is driven by the drive motor 28.3 via the worm gear 28.1 and the worm 28.2. This movement of the driven middle gear 30.1 of the middle pressure ram 12 is transmitted to the two outer pressure rams 12 via the intermeshing gears 30.1 of the gear unit 30, so that the sleeves 20.n of all three length-adjustable pressure rams 12 are actuated synchronously.

[0052] Alternatively, all three pressure rams 12 can be driven and adjusted separately and individually. This requires a correspondingly higher level of effort, as three drive motors 28.3 are required and the corresponding synchronization must be controlled. However, controlling each pressure ram 12 individually offers the advantage that the contact pressure can be controlled differently across the width of the energy storage device 4, allowing the contact pressure to be adjusted more precisely overall.

[0053] Fig. 7 shows a sectional view of a length-adjustable pressure stamp 12 (shown in Fig. 2) with drive unit 28 coupled via the gear 30 (shown in Fig. 5). The transmission 30 is a gear transmission and includes the gear 30.1.

[0054] Fig. 7 shows a corresponding structure of the pressure stamp 12 with drive unit 28 analogous to Fig. 5 but with the difference that between the drive unit 28 and the first sleeve 20.1 the gear 30.1 (also called gear element) is integrated, which has further gears 30.1 (also called intermediate gears, shown in Fig. 6) ensures the synchronization of the movement of other adjacent pressure stamps 12. The additional gears 30.1 designed as intermediate gears ensure that the direction of rotation of the three pressure stamps 12, designed as telescopic shafts 20 (also called threaded sleeve arrangements, shown in Fig. 2), have the same direction of rotation and thus identical parts can be used, so that the effort is reduced accordingly. List of reference symbols 1 housing 2 cell stacks 4 electrical energy storage 6 single cells 8 Resizing 9 Dead space 10 Printing device 12 printing stamps 14 printing plate 18 Plate surface 20 telescopic shaft 20.1 first sleeve 20.2 second sleeve 20.3 third sleeve 20.n sleeve 22 Guide rail 24 guide groove 26 Sensor 28 Drive unit 28.1 Worm gear 28.2 Snail 28.3 Drive motor 30 gearboxes 30.1 Gear 32 threads 32.1 Internal thread 32.2 external thread 34 locking mechanism 36 latch mechanism 36.1 Jack socket 36.2 Jack 100 extended state 102 partially extended or partially retracted state 104 retracted state 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 printing device (10) comprises at least one printing plate (14) which lies flat against one end of the cell stack (2), and a length-adjustable printing stamp (12) which lies or engages the printing plate (14) on a plate surface (18) facing away from the cell stack. [2] Electrical energy storage device (4) according to claim 1, characterized by that the length-adjustable pressure stamp (12) is designed as a telescopic shaft (20). [3] Electrical energy storage device (4) according to claim 2, characterized by that the telescopic shaft (20) comprises at least two sleeves (20.n) which are telescopically nested and adjustable in length relative to one another. [4] Electrical energy storage device (4) according to claim 3, characterized by that the sleeves (20.n) are designed as threaded sleeves. [5] Electrical energy storage device (4) according to claim 3 or 4, characterized by that the sleeves (20.n) are additionally guided longitudinally via guide rails (22) and / or guide grooves (24). [6] Electrical energy storage device (4) according to one of the preceding claims, characterized by that a drive unit (28) is provided which is coupled on the output side to the pressure stamp (12) for its longitudinal adjustment. [7] Electrical energy storage device (4) according to claim 6, characterized by that a transmission (30), in particular a gear transmission, is arranged between the drive unit (28) and the pressure stamp (12). [8] Electrical energy storage device (4) according to one of the preceding claims, characterized by that the locking mechanism (34) is designed as a latch mechanism (36). [9] Electrical energy storage device (4) according to claim 8, characterized by that the latch mechanism (36) comprises, on the one hand, a latch receptacle (36.1) and, on the other hand, a latch (36.2) which, in a locked state, engages in the latch receptacle (36.1) in a locking manner. [10] Electrical energy storage device (4) according to one of the preceding claims, characterized by that a plurality of cell stacks (2) are provided, wherein the printing device (10) has a number of printing stamps (12) corresponding to the number of cell stacks (2), or that a plurality of printing devices (10) are provided for a single cell stack (2).

Images