Measuring arrangement and method for detecting a mechanical stress on a housing component of a housing of a battery unit

Abstract

The invention relates to a measuring arrangement (38) for detecting a mechanical stress on at least one housing component (14a; 16) of a housing (14a; 16) of a battery unit (10) comprising at least one battery cell (14). The measuring arrangement (38) comprises an evaluation unit (34, 36) and a permanently uninterrupted conductor loop (40) which is electrically connected to the evaluation unit (34, 36) and which can be or is fastened at two different locations (32; 32a, 32b; 30; 30a; 44) of the battery unit (10) in such a way that a distance between the two locations (32; 32a, 32b; 30; 30a; 44) can be changed by an expansion (Δs, Δs', Δs'') of the at least one battery cell (14), wherein the evaluation unit (34, 36) is designed to detect a change (ΔR, ΔR', ΔR'') in an electrical resistance of the conductor loop (40) and, depending on the change (ΔR, ΔR', ΔR'') to record the mechanical stress.

Description

[0001] The invention relates to a measuring arrangement for detecting mechanical stress on at least one housing component of a housing of a battery unit comprising at least one battery cell. Furthermore, the invention also relates to a method for detecting mechanical stress.

[0002] In the case of batteries, particularly automotive batteries, for example high-voltage batteries, information about the "electrical" service life or the aging state of the battery cells can be obtained for the battery cells by diagnosing the charge capacity and voltages of the battery cells, for example. Over the course of such a battery's service life, however, not only the battery cells are subject to certain aging effects, but housing components of such a battery also experience a certain degree of mechanical stress. Theoretically, it is therefore possible for housing components or a housing as a whole, for example a module housing, to exhibit mechanical damage before the chemical aging of the battery cells has progressed to the point where a diagnostic system indicates that the electrical condition of a battery module or cell module requires replacement.There is therefore a risk that a battery module would have to be replaced or repaired due to such mechanical damage, but this is not detected or not detected in a timely manner. It would therefore be desirable to be able to detect, monitor, and / or quantify mechanical stress on the housing components of a battery or battery module.

[0003] WO 2021 / 074456 A1 describes a cooling device for a battery with round cells, wherein the cooling device comprises a cooling line positioned in a serpentine configuration between the round cells. This line can be inflatable and flexible, so that expansion of the line is caused by the fluid pressure of the coolant conveyed in the line. A flexible circuit board with sensors, in particular temperature sensors and strain sensors, can be arranged on the line. The strain sensors can be used to monitor the coolant pressure.

[0004] DE 10 2018 200 919 A1 describes a detection device for detecting a mechanical deformation of a high-voltage storage device of a motor vehicle. The detection device comprises a flat sensor element that is electrically conductive and is arranged on a first component and positioned opposite an electrically conductive region of a second component. Furthermore, the detection device comprises an evaluation device that can detect, by evaluating an electrical measurement variable, when the sensor element comes into electrically conductive contact with the second component, for example, due to a deformation of the high-voltage storage device.

[0005] EP 3 249 737 A1 describes a battery with a component for detecting information about physical stress. The component can comprise an acceleration sensor, a vibration sensor, a strain sensor, an impact sensor, a pressure sensor, an inclination sensor, a position sensor, and a speed sensor. The strain sensor can be embodied as a strain gauge.

[0006] The object of the present invention is to provide a measuring arrangement and a method which allow the mechanical stress on a housing component of a battery unit to be recorded and / or quantified in the simplest and most efficient manner possible.

[0007] This object is achieved by a measuring arrangement and a method having the features according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0008] A measuring arrangement according to the invention for detecting a mechanical stress on at least one housing component of a housing of a battery unit comprising at least one battery cell has an evaluation unit and a permanently uninterrupted conductor loop which is electrically connected to the evaluation unit and which can be or is fastened at two different locations on the battery unit in such a way that a distance between the two locations can be changed by an expansion of the at least one battery cell, wherein the evaluation unit is designed to detect a change in an electrical resistance of the conductor loop and to detect the mechanical stress as a function of the change.

[0009] The invention is based on the finding that the so-called swelling of battery cells, in particular the age-related swelling of battery cells, according to which battery cells expand over the course of their service life, is largely responsible for the mechanical stress on housing components, such as the cell housing or cell cup of the battery cells themselves or the module housing. Mechanical vibration stresses, for example, are significantly less significant than these swelling-related stresses, especially in small modules, for example, with fewer than 15 battery cells. Furthermore, the invention is based on the finding that the resistance of an electrical conductor, such as the conductor loop of the measuring arrangement, changes upon stretching.This advantageously makes it possible to arrange the conductor loop at at least two different points on the battery unit in such a way that it expands at least in some areas when the at least one battery cell expands and the distance between the two points changes, in particular increases, accordingly. This at least partial expansion of the conductor loop in turn leads to a change in its electrical resistance, which can be detected by the evaluation unit. Accordingly, such a change in resistance, i.e. the change in electrical resistance, can be used to detect mechanical stress on the housing component of the battery unit housing and, in particular, to quantify it by the size of the change in electrical resistance, e.g. relative to a defined resistance reference value.Overall, it is therefore advantageously possible to record, quantify and also monitor such stress on a housing component over time in a particularly simple and efficient manner, namely by measuring the electrical resistance of the conductor loop.

[0010] A conductor loop is understood to be an electrical conductor, i.e. an electrically conductive element and / or component, which can be designed in one or more parts, and which is guided in the form of a loop and connected to the evaluation unit. The electrical conductor, i.e. the conductor loop, has two ends, namely conductor ends, which are coupled or connected to the evaluation unit. The evaluation unit can, for example, be designed to apply a measuring voltage or a measuring current to the conductor loop. For example, a measuring voltage can be applied between the two conductor ends. The applied measuring voltage leads to a measuring current through the conductor loop. This current can be used to determine the resistance of the conductor loop. A change in the current with the same applied voltage indicates a change in resistance.The two different locations of the battery unit (to which the conductor loop is attached) can, for example, both be located on the at least one battery cell or both be arranged at a location on the battery unit different from the at least one battery cell or only one of the two locations can be located on the at least one battery cell.

[0011] The expansion of the battery cell and / or a cell group with several battery cells and / or the battery unit in a certain direction can also be referred to as elongation.

[0012] The term "permanently uninterrupted" refers to the fact that the conductor loop is permanently uninterrupted during normal operation and use in the measuring setup. This means that its two conductor ends are permanently connected to each other via a closed, electrically conductive connection. Therefore, no interruption or damage to the conductor loop should be used to detect mechanical stress, nor, conversely, should an electrical contact between two areas be used to close the conductor loop to detect a specific mechanical stress.

[0013] For example, a first mechanical stress state and a second mechanical stress state can be defined, wherein the mechanical stress of the at least one housing component is increased according to the second mechanical stress state compared to the first mechanical stress state. The second mechanical stress state can be assigned a different electrical resistance or resistance range of the conductor loop than the first mechanical stress state. Accordingly, depending on the currently detected electrical resistance of the conductor loop, it can be determined whether the first or the second mechanical stress state exists. During each measurement of the electrical resistance to determine the mechanical stress, the conductor loop is therefore in an uninterrupted, continuous state in which the two ends of the conductor loop are electrically conductively connected to one another.

[0014] In particular, the evaluation unit can be designed to detect a change in the electrical resistance of the conductor loop caused by a change in the distance between the two points. Depending on the detected change, the evaluation unit can then detect the mechanical stress. Other parameters, such as a change in temperature, can also contribute to a change in the electrical resistance of the conductor loop. Such other influencing factors can be easily eliminated, for example, by temporally averaging multiple measured resistance values.

[0015] Therefore, it represents a further very advantageous embodiment of the invention if the evaluation unit is designed to repeatedly record the stress as a function of the change in resistance, i.e. the change in electrical resistance, over a certain period of time, and to output a signal as a function of the recorded stresses. The repeated recording of the resistance or the change in resistance has several advantages: Firstly, this allows temporal monitoring of the electrical resistance and thus of the elongation of the battery unit and correspondingly the mechanical stress on at least one housing component. Secondly, this also allows the above-mentioned averaging to be implemented in a simple manner in order to eliminate other influences, such as temperature.

[0016] Alternatively or additionally, one or more such influencing parameters, such as temperature, can be recorded and taken into account when evaluating the electrical resistance. This can be easily achieved, for example, using a corresponding characteristic curve map, which assigns a measured resistance at a specific temperature to a specific elongation and / or stress value.

[0017] Within a specific period of time, a measurement can be carried out multiple times to record a change in resistance or to record the current electrical resistance of the conductor loop. The electrical resistance measured during such a measurement can be compared with a defined resistance reference value to determine the change in resistance. The repeatedly recorded resistance values can, for example, each be compared with this resistance limit value; when this value is exceeded, a signal is output, and this corresponds, for example, to a mechanical limit load. In this way, it can be detected if at least one housing component is already subjected to severe mechanical stress or is subjected to excessive mechanical stress and replacement and / or maintenance of the housing component is necessary.Depending on the signal output, an entry can be made in an error log and / or information can be sent to the vehicle driver and / or a workshop, and / or similar devices. The repeatedly recorded resistance values are also compared with this resistance limit, and deviations from the resistance limit are stored or documented over time. This allows the mechanical stress to be monitored and documented over time.

[0018] According to a further advantageous embodiment of the invention, the measuring arrangement comprises the battery unit, in particular wherein the housing represents a cell housing or at least one battery cell and / or a module housing of the battery unit designed as a battery module, wherein the at least one battery cell is accommodated in the module housing. By means of the measuring arrangement, in particular, both a mechanical stress on the cell housing of such a battery cell and on a module housing of the battery module that comprises the battery cell can be detected. The battery cell can be a lithium-ion cell, for example. In particular, the battery cell can be a prismatic battery cell. Prismatic battery cells in particular are subject to very strong swelling-related expansion as they age.Several prismatic battery cells can be arranged next to one another in a stacking direction to form a cell stack. The battery module can, for example, comprise such a cell stack with several battery cells. The measuring arrangement according to the invention or its embodiments can, above all, easily and efficiently detect elongation of the battery module in the stacking direction. The conductor loop can be attached or attachable to any two locations on such a battery module. These two locations can be very close to one another or very far apart. This allows mechanical stresses to be detected both over short distances and over longer distances of the battery module. This allows particularly flexible and comprehensive monitoring of the mechanical stress state of such a battery module.

[0019] According to a further advantageous embodiment of the invention, the battery unit comprises at least a first and a second battery cell, wherein a first location of the two locations is fixed relative to the first battery cell and a second location of the two locations is fixed relative to the second battery cell, in particular wherein the battery unit comprises a cell stack with a plurality of battery cells arranged next to one another in a stacking direction, wherein the first and the second location are provided by the battery unit in such a way that they move away from one another in the event of an expansion of the cell stack in the stacking direction. In principle, the first and the second location can also be provided by the battery unit in such a way that they move away from one another in the event of an expansion of the cell stack in the stacking direction, even if the first location and the second location are not each fixed to one of the two battery cells.However, the conductor loop can be attached to the battery module particularly easily if it is directly or indirectly fixed to at least two battery cells of the battery unit. This provides a particularly simple attachment option for the conductor loop, and on the other hand, an expansion of the cell stack in the stacking direction can be detected particularly easily, since an expansion of the two battery cells in the stacking direction also leads to the two points at which the conductor loop is attached moving away from each other. The two points can be provided by the two battery cells themselves. For example, they can be provided by a part of the cell housing of each of the two battery cells.However, the two locations can also be provided by other elements that are different from the two battery cells, but are mechanically coupled to them, for example, so that an expansion of the respective battery cell also leads to a corresponding change in the position of the element, through which the respective location at which the conductor loop is fixed.

[0020] The evaluation unit itself can be provided, for example, by a cell module controller. Such a cell module controller can also be part of the battery module. For example, such a cell module controller can be arranged at one end of the cell stack, for example, arranged on an end plate of such a battery module, which is part of a clamping frame surrounding the cell stack and delimits the cell stack in or against the stacking direction.

[0021] According to a further very advantageous embodiment of the invention, the first and second battery cells are adjacent to one another in a specific direction. In other words, the two points at which the conductor loop is or can be attached are provided by two battery cells that are adjacent to one another in the stacking direction. The conductor loop then does not have to extend over all of the battery cells in the stacking direction, but can be made very short in the stacking direction, so that the conductor loop covers, for example, only the first and second battery cells, or a cell group comprising the first and second battery cells with a few but not all of the cells of the battery unit. This makes it possible to detect mechanical stress over a very short distance. This procedure is particularly suitable, for example, for detecting the mechanical stress on the cell housings themselves.The measuring arrangement can also comprise several such conductor loops. Each of these conductor loops can be assigned to at least two battery cells in the cell stack. These can be paired differently. This allows local mechanical stresses between any two cell pairs to be measured particularly precisely. This also makes it possible to detect, for example, if one of the battery cells in the cell stack expands excessively. Several conductor loops can also be provided, covering the cell stack to varying degrees in the stacking direction. This allows stresses to be measured on different length scales.

[0022] According to a further advantageous embodiment of the invention, the battery unit comprises at least one or more third battery cells, which is or are arranged between the first and the second battery cell. In other words, in this example, the conductor loop is coupled to two battery cells that are not directly adjacent to one another, but are further apart from one another and between which there is at least one further battery cell, which is also referred to herein as a third battery cell. In this example, the first and second battery cells can be two edge cells that delimit the cell stack on both sides in and against the stacking direction. This allows the elongation of the battery module over its entire length in the stacking direction to be detected and monitored over the course of its service life.It is therefore also possible to detect the elongation of the battery module over longer distances using a corresponding resistance measurement and, accordingly, to measure and monitor the mechanical stress over larger length scales. This embodiment can be provided in addition to or as an alternative to the embodiments described above. For example, the elongation can be detected via the resistance measurement of the conductor loop both across multiple battery cells and, additionally or alternatively, only across two adjacent battery cells. The expansion of the battery module can thus advantageously be detected both globally across the entire battery module and / or locally across only one or two or a few cells.

[0023] According to a further advantageous embodiment of the invention, the measuring arrangement comprises a flexible printed circuit board arrangement with a flexible printed circuit board and at least one sensor arranged thereon for detecting a measured variable relating to the at least one battery cell, wherein a flexible printed circuit board arrangement is arranged and fixed or can be arranged and fixed on the battery unit at least at two different locations, wherein the conductor loop is arranged at least partially on the flexible printed circuit board. Such a flexible printed circuit board can advantageously be used to fulfill further functions, in particular to act as a carrier for, for example, one or more sensors, for example temperature sensors and / or current sensors and / or voltage sensors or the like.For example, in addition to the conductor loop, the circuit board assembly can also include one or more additional conductor tracks arranged on the flexible circuit board, for example, to connect such an additional sensor to the evaluation unit. By integrating the conductor loop into such a circuit board assembly, which can also be referred to as an FPC (flexible printed circuit) or flex-print cable, existing components can advantageously be used to support or integrate the conductor loop and also to fix it in at least two places. This means that no additional structural effort is required due to the provision of the conductor loop.Furthermore, the evaluation unit of the battery module, which is used to record the measured values of such at least one further sensor as part of the circuit board assembly, can also be used simultaneously to record the electrical resistance of the conductor loop, in particular a change in resistance. Because the circuit board assembly also comprises a flexible circuit board, it is also possible to allow a certain amount of expansion of such a flexible circuit board in the stacking direction as the battery cells expand, which is why such a flexible circuit board can also be used as a carrier for the conductor loop without limiting the functional principle of the measuring assembly.

[0024] The flexible circuit board can be made of an electrically insulating carrier material. The electrically conductive components of such a circuit board arrangement, for example, electrical and electronic components and / or conductor tracks, can be fully or at least partially embedded in such a flexible circuit board. For this purpose, these components can be laminated, for example, between two electrically insulating films of the flexible circuit board or something similar. The same applies accordingly to the conductor loop. At the end of the flexible circuit board, the two ends of the conductor loop can be led out of this circuit board and plugged into or connected to the evaluation unit.

[0025] According to a further advantageous embodiment of the invention, the conductor loop is formed by a continuous electrical conductor, in particular a continuous wire and / or a continuous conductor track, in particular a one-piece wire and / or a one-piece conductor track, which, when fastened at the two locations, is electrically insulated from the at least one battery cell, in particular which is electrically insulated from all battery cells comprised by the battery unit. This embodiment of the conductor loop is particularly simple and efficient. The electrical insulation from the battery cells can, for example, be provided in a simple manner by the aforementioned flexible printed circuit board. The conductor loop can thus be provided as a simple wire or simple conductor track that is embedded in the electrically insulating material of the flexible printed circuit board or arranged thereon.

[0026] According to a further advantageous embodiment of the invention, at least part of the conductor loop is electrically conductively connected to a cell pole of the at least one battery cell, in particular wherein a battery unit comprises a plurality of battery cells, wherein at least two of the battery cells are electrically contacted with one another via an electrically conductive cell connector and wherein the cell connector is part of the conductor loop. The conductor loop can therefore additionally or alternatively be provided by already existing electrically conductive components of the battery module, for example partially by a cell connector that electrically connects two battery cells, in particular their cell poles, to one another. Thus, already existing electrically conductive components can be used to provide the electrical conductor loop.This is very advantageous, especially since a cell connector is already firmly connected to two battery cells of such a battery module and fixed relative to them. An elongation of the battery module, in particular an expansion of one or both of these battery cells, thus directly affects a change in the length of such a cell connector. It is therefore very advantageous to use such a cell connector as part of the conductor loop in order to detect the elongation via the change in resistance of the conductor loop.

[0027] According to a further advantageous embodiment of the invention, the measuring arrangement can comprise a first voltage tap and a second voltage tap, wherein the first and the second voltage tap are formed as part of the conductor loop. The two voltage taps can, for example, be electrically connected or contacted to the above-mentioned cell connector or also to different cell connectors. At least one of these two voltage taps can, for example, be designed or used in combination with the second or a further third voltage tap to tap a cell voltage of the at least one battery cell. The electrically conductive contact of such a voltage tap to the evaluation unit, which is used to tap the cell voltage, can thus simultaneously be used as part of the conductor loop.This advantageously eliminates the need for separate cabling or routing, or it can be reduced to a minimum. The measuring setup can thus be designed even more efficiently. Furthermore, in this case, the evaluation unit does not necessarily have to be designed to apply a test voltage or current, or a measurement voltage or current, to the conductor loop, since this can also be provided, for example, by the battery cell itself. For this purpose, the conductor loop can also be designed with very high resistance or include a very high resistance resistor, so as not to place any energy load on the cells during the measurement.

[0028] This procedure for determining the change in resistance is also suitable for two locations that are very close to each other as well as for two locations that are very far apart, for example, provided by two edge battery cells.

[0029] Furthermore, the invention also relates to a battery with a measuring arrangement according to the invention or one of its embodiments.

[0030] The battery according to the invention can be designed, for example, as a high-voltage battery. The battery can also comprise one or more battery units, e.g., battery modules. Each of the battery units can be designed as described for the at least one battery unit.

[0031] Furthermore, the invention also relates to a motor vehicle with a measuring arrangement according to the invention or one of its embodiments. Furthermore, the invention also relates to a motor vehicle with a battery according to the invention or one of its embodiments.

[0032] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle.

[0033] Furthermore, the invention relates to a method for detecting a mechanical stress on at least one housing component of a housing of a battery unit comprising at least one battery cell.

[0034] In this case, a permanently uninterrupted conductor loop which is electrically connected to an evaluation unit is fastened at two different locations on the battery unit in such a way that an expansion of the at least one battery cell changes a distance between the two locations, wherein the evaluation unit detects a change in an electrical resistance of the conductor loop, in particular a change in the electrical resistance of the conductor loop caused by a change in the distance, and detects the mechanical stress as a function of the change.

[0035] The advantages described for the measuring arrangement and its configurations apply equally to the method according to the invention.

[0036] The invention also includes further developments of the method according to the invention that have features already described in connection with the further developments of the measuring arrangement according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0037] The evaluation unit can have a data processing device or a processor device that is configured to carry out an embodiment of the method according to the invention. The processor device can for this purpose have at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). In particular, a CPU (Central Processing Unit), a GPU (Graphical Processing Unit) or an NPU (Neural Processing Unit) can be used as the microprocessor. Furthermore, the processor device can have program code that is configured to carry out the embodiment of the method according to the invention when executed by the processor device. The program code can be stored in a data memory of the processor device. The processor device can, for example,based on at least one circuit board and / or on at least one SoC (System on Chip).

[0038] The invention also encompasses combinations of the features of the described embodiments. The invention therefore also encompasses implementations that each comprise a combination of the features of several of the described embodiments, unless the embodiments are described as mutually exclusive.

[0039] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 a schematic and perspective representation of a battery module according to an embodiment of the invention; Fig. 2 a schematic representation of a measuring arrangement according to the embodiment of the invention; Fig. 3 a schematic representation of a measuring arrangement according to a further embodiment of the invention; and Fig. 4 a schematic representation of a measuring arrangement according to a further embodiment of the invention.

[0040] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass 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 already described.

[0041] In the figures, identical reference symbols denote functionally identical elements. The coordinate systems depicted in the figures are preferably Cartesian coordinate systems.

[0042] Fig. 1 shows a schematic and perspective illustration of a battery unit 10 in the form of a battery module 10 according to an exemplary embodiment of the invention. The battery module 10 comprises a cell stack 12 with a plurality of battery cells 14 arranged next to one another in a stacking direction x, of which, for reasons of clarity, only some are provided with a reference symbol. The cell stack 12 is arranged in a module housing 16 of the battery module 10. In addition, each battery cell 14 has its own cell housing 14a. In the present example, the battery cells 14 are designed as prismatic battery cells 14. Furthermore, each cell 14 comprises two cell poles 18, of which, for reasons of clarity, only some are provided with a reference symbol. In the present example, a carrier unit 20, which can also be referred to as an LV (low-voltage) cable carrier 20, is arranged on an upper side of the cell stack 12.This carrier unit 20 can comprise a carrier plate 22 on which one or more components can be mounted or arranged. In the present example, a flex-print cable 26 is arranged on this carrier plate 22 as an example of a flexible printed circuit board arrangement 24. This comprises, for example, an electrically insulating, flexible printed circuit board substrate 28 with conductor tracks embedded therein. These can be electrically connected to sensors which, depending on the type of sensor, can optionally also partially protrude from the printed circuit board substrate 28, such as voltage taps 30 (see ). Fig. 2) in order to connect them electrically to the cell poles 18, in particular indirectly via cell connectors 32 (compare Fig. 2) to connect and make electrical contact.

[0043] In addition, the battery module 10 includes an evaluation unit 34 in the form of a cell module controller 36, which can also be referred to as a cell management controller 36, and which, in the present example, is arranged on the front side of the module housing 16 of the battery module 10. The flex-print cable 26 is connected to the evaluation unit 34.

[0044] Due to chemical aging processes, cell growth of the battery cells 14 occurs over time, resulting in an expansion of the cells 14 primarily in the x-direction shown. This expansion is also denoted by Δs here and is also called elongation. The arrow denoted by Δs is intended to illustrate the direction of expansion of this elongation Δs and not necessarily its extent. Due to aging-related swelling of the battery cells 14, a respective cell 14 and thus the module 10 in the case of the prismatic cell 14 will expand in a transverse arrangement, i.e., primarily in the longitudinal direction x. This elongation Δs represents the elementary mechanical stress on the cell cup, i.e., the cell housing 14a, and the module housing 16.This elongation Δs, for example of the cell module 10, can now advantageously be measured using a diagnostic function and, for example, an integral statement can be made about the mechanical condition of the cell module 10.

[0045] For this purpose, a measuring arrangement 38 is provided. Such a measuring arrangement 38 is shown as an example in Fig. 2 illustrated. In Fig. 2, in particular, a carrier unit 20 for a battery module 10 is illustrated, for example as already shown in Fig. 1. However, the carrier unit 20 can be considered as part of the measuring arrangement 38. Also, the Fig. 1 mentioned evaluation unit 34 may be part of this measuring arrangement 38, although for reasons of clarity this is shown in Fig. 2 is not shown, as are the other components of the Fig. 1. The measuring arrangement 38 is now advantageously designed to measure the above-described elongation Δs of the cell module 10. One possibility for implementing this is, for example, by integrating a measuring technology into the above-mentioned flexprint cable 26, which is a component of the LV cable carrier 20. As described, this carrier unit 20 can be arranged, for example, on the top side of the module 10 or the cell stack 12, as in the present example, or on any other side of such a cell stack 12, for example, also to the side of the cell stack 12 with respect to the y-direction, in order to be able to arrange a cooling device on the battery module 10, for example, at the top and bottom with respect to the z-direction. Such a flexprint cable 26 can rest on the cells 14 and, for example, via a plastic component, e.g.the aforementioned carrier plate 22, and / or via the cell connectors 32 with the cells 14 in the load flow. A change in resistance can be measured on such a flex-print cable 26, analogous to a strain gauge in a Wheatstone bridge circuit with a thin wire. In this example, the measuring arrangement 38 comprises an electrical conductor loop 40, which can be provided by such a wire or thin conductor. In other words, the conductor loop 40 in the present example is provided by a wire 42 or an electrical conductor track 42, which can, for example, be integrated into the electrically insulating substrate 28 of the flex-print cable 26 and which is accordingly electrically insulated from the cells 14. The conductor loop 40 has two conductor ends 40a, 40b, which are connected to the evaluation unit 34.For measurement purposes, the evaluation unit 34 can apply a measuring voltage to the conductor ends 40a, 40b and use this voltage to measure the electrical resistance of the conductor loop 40. If the length of the cell stack 12 changes, the conductor loop 40 also expands accordingly, leading to a change in its electrical resistance, in particular to an increase. Repeated measurement of the electrical resistance of the line 40 makes it possible to detect a change in the length of the module 10 in a simple and efficient manner, i.e., to measure it and, from this, to determine the mechanical stress on at least one housing component, for example, a cell housing 14a and / or module housing 16.The change in resistance that can be detected using this conductor loop 40 and the evaluation unit 34 thus offers the possibility, if a correlation to elongation was established in the test, of performing a measurement with the existing components without significant structural changes to the current modules. In other words, the integration of this functionality for measuring the change in resistance of such a conductor loop 40 via the evaluation unit 34 does not require any major structural changes to the battery module 10 and, moreover, requires little or no additional installation space, since the conductor loop 40 can be easily integrated into the flex-print cable 26 and the cell module controller 36 can be used to evaluate or measure the change in resistance.

[0046] Parts of the carrier unit 20 can be fixed to the cell stack 12 in a variety of ways. Firstly, sensors of the flex-print cable 26, such as voltage taps 30 in the present example, can be fixed to the corresponding cell connectors 32. This also fixes corresponding points on the flex-print cable 26 to corresponding points or locations on the cell stack 12. Furthermore, the flex-print cable 26 can additionally or alternatively be mechanically connected to the carrier plate 22 via pins 44. These pins 44 can transmit axial loads to the FPC (Flexible Printed Circuit) 24, i.e., to the flexible printed circuit board 24. The carrier plate 22 is in turn attached to the cells 12, in particular via the cell connectors 32 or other attachment points. An expansion of the cells in the x-direction also has a corresponding effect on the carrier plate 22, the flex-print cable 26, and the integrated conductor loop 40.

[0047] Compared to the use of a strain gauge, the use of the conductor loop 40 enables a significantly simpler structure, easier integration into the module 10, significantly more flexible application possibilities, since the conductor loop can be very easily modified in terms of its length and course and can be designed and arranged according to requirements and, above all, existing components can be used much more easily, even electrically conductive components such as cell connectors, voltage taps, conductor tracks, as part of the conductor loop.

[0048] The connection pins of the cell management module, such as the evaluation unit 34 in the present example, are not yet fully occupied, and the flex-print cables 26 offer a simple way to incorporate a loop 40 for measurement. This eliminates the need to add new sensors, either for tests during the development process or during operation of an installed vehicle battery. The resistance of the loop 40 can be tapped at the cell management controller 36, e.g., with a prepared CMC (Cell Management Controller) 36. The measuring arrangement 38 can be implemented as a simple electronic component that can utilize existing components of a module 10 as components.Compared to a conventional displacement sensor, optical or inductive, this is a cost-effective, lightweight and space-saving variant with which measurements can be taken and no redesign of the cell modules 10 is required in order to have a mechanical fatigue of the cell modules 10 displayed integrally.

[0049] At the conductor ends 40a, 40b, especially at the signal bundling point 46, the signal bundling and forwarding to the CMC 36 takes place. Fig. With the example of the measuring arrangement 38 shown in Figure 2, an integral deformation of the cell module 10 can be measured. This means that the individual length changes of the cells 14 in the x-direction can be detected in their entirety using a single conductor loop 40, which in this case extends over a large part of the cell stack 12, in particular almost the entire cell stack 12 in the x-direction. The length change Δs and the resulting resistance change ΔR are illustrated here by an arrow.

[0050] Alternatively, the conductor loop 40 can extend over only a few cells 14 in the x-direction or even over only a single cell 14 in the x-direction, for example, to detect a linear expansion Δs of only these few cells 14 or of the individual cell 14 via the corresponding resistance change ΔR. These described variants can also be combined with one another as desired.

[0051] Additionally or alternatively, existing electrical lines of the flexprint cables 26, for example the electrical lines from the voltage taps 30 to the evaluation unit 34, can also be used to measure a corresponding change in length Δs, for example between any cell connector 32 and its signal bundling point 46, where it is coupled to the CMC 36, via the change in their electrical resistance.

[0052] As described, the conductor loop 40 can be integrated into an FPC 26. An existing FPC 26 can be used for this purpose, or a thin additional FPC 26 can be additionally or alternatively inserted into the module 10, for example, to allow the conductor loop 40 to run at a desired position. With such a loop 40, it is therefore possible to measure the change in electrical resistance ΔR at the signal bundling point 46 or by measuring the resistance between the conductor ends 40a, 40b.

[0053] Fig. 3 shows a schematic representation of a measuring arrangement 38 according to a further exemplary embodiment of the invention. The measuring arrangement 38 can be designed as described above, except for the differences described below: In this variant, the local deformation of two adjacent cells 14 is measured. The gap growth of the gap between the two adjacent cells 14 and / or the growth of the two adjacent cells 14 as such can therefore be recorded. The measuring principle is the same as that previously described in connection with the conductor loop 40 embodied as a wire 42. In the present example, the conductor loop 40 is not embodied entirely as a one-piece wire 42, but also comprises other module components, namely a cell connector 32a, which is contacted with the FPC 26 via a first voltage tap 30a and a second voltage tap 30b.The first voltage tap 30a can, for example, represent an already existing voltage tap 30a of the module 10. The second voltage tap 30b can represent an additionally provided voltage tap 30b. The first voltage tap 30a is connected to the first line end 40a via a first electrical line 42a, and the second voltage tap 30b is connected to the second end 40b via a second line 42b. The second voltage tap 30b does not function to tap a voltage at a cell 14, since the cell poles of the neighboring cells connected via the cell connector 32a are at the same potential anyway. Nevertheless, this second voltage tap 30b can be designed like a conventional voltage tap 30a and connected to the flex-print cable 26. Thus, a conductor loop 40 can advantageously be provided using partially already existing electrical and / or electronic components.

[0054] In this example, the two voltage taps 30a, 30b are connected to the terminals 18 of two cells 14 that are directly adjacent to each other in the x-direction. This makes it possible to detect the length change Δs via a corresponding resistance change ΔR that occurs between these two cells 14, i.e., due to cell growth in the x-direction and / or the gap growth of the gap between the cells 14.

[0055] Fig. Figure 4 shows a schematic representation of a measuring arrangement 38 according to a further embodiment of the invention. This can be implemented in particular as shown in Fig. 3, except for the differences described below. In this example, too, as already mentioned, Fig. 3, the conductor loop 40 is provided at least partially by components of the module 10 that are already provided. In particular, voltage taps 30a, 30b as part of the conductor loop 40 are now further apart from each other than in the Fig. 3 and not directly adjacent cells 14. The measurement of the integral deformation ΔR'' of the cell module 10 is carried out in this example via the cell voltage taps 30a, 30b of distant cells 14, for example via the voltage taps 30a, 30b between two cells 14 of the cell stack 12 that are maximally separated in the x-direction. The structure and procedure can be as follows: Fig. 3, except for the difference that the electrical resistance is tapped or used between the cells 14 that are further or most distant.

[0056] Overall, the examples demonstrate how the invention can provide a measurement of swelling-induced strains of a module housing and / or the cells using existing FPC technology. 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] WO 2021 / 074456 A1

[0003] DE 10 2018 200 919 A1

[0004] EP 3 249 737 A1

[0005]

Claims

[1] Measuring arrangement (38) for detecting a mechanical stress on at least one housing component (14a; 16) of a housing (14a; 16) of a battery unit (10) comprising at least one battery cell (14), characterized by , that - the measuring arrangement (38) comprises an evaluation unit (34, 36) and a permanently uninterrupted conductor loop (40) which is electrically connected to the evaluation unit (34, 36) and which can be or is fastened at two different locations (32; 32a, 32b; 30; 30a; 44) of the battery unit (10) in such a way that a distance between the two locations (32; 32a, 32b; 30; 30a; 44) can be changed by an expansion (Δs, Δs', Δs'') of the at least one battery cell (14), and - wherein the evaluation unit (34, 36) is designed to detect a change (ΔR, ΔR', ΔR'') in an electrical resistance of the conductor loop (40) and to detect the mechanical stress as a function of the change (ΔR, ΔR', ΔR''). [2] Measuring arrangement (38) according to claim 1, characterized by that the evaluation unit is designed to repeatedly record the stress as a function of the resistance change (ΔR, ΔR', ΔR'') over a certain period of time and to output a signal as a function of the recorded stresses. [3] Measuring arrangement (38) according to one of the preceding claims, characterized by that the measuring arrangement (38) comprises the battery unit (10), in particular wherein the housing (14a; 16) represents a cell housing (14a) of the at least one battery cell (14) and / or a module housing (16) of the battery unit (10) designed as a battery module, wherein the at least one battery cell (14) is accommodated in the module housing (16). [4] Measuring arrangement (38) according to one of the preceding claims, characterized byin that the battery unit (10) comprises at least a first and a second battery cell (14), wherein a first location of the two locations (32; 32a, 32b; 30; 30a; 44) is fixed relative to the first battery cell (14) and a second location of the two locations is fixed relative to the second battery cell (14), in particular wherein the battery unit (10) comprises a cell stack (12) with a plurality of battery cells (14) arranged next to one another in a stacking direction (x), wherein the first and the second location (32; 32a, 32b; 30; 30a; 44) are provided by the battery unit (10) in such a way that they move away from one another in the event of an expansion (Δs, Δs', Δs'') of the cell stack (12) in the stacking direction (x). [5] Measuring arrangement (38) according to one of the preceding claims, characterized by that the first and second battery cells (14) are adjacent to each other in a specific direction (x). [6] Measuring arrangement (38) according to one of the preceding claims, characterized by that the battery unit (10) comprises at least one or more third battery cells (14) which are arranged between the first and the second battery cell (14). [7] Measuring arrangement (38) according to one of the preceding claims, characterized by in that the measuring arrangement (38) comprises a flexible printed circuit board arrangement (24) with a flexible printed circuit board and at least one sensor (30) arranged thereon for detecting a measured variable relating to the at least one battery cell (14), wherein the flexible printed circuit board arrangement (24) is arranged and fixed or can be arranged and fixed on the battery unit (10) at least at the two different locations (32; 32a, 32b; 30; 30a; 44), wherein the conductor loop (40) is arranged at least partially on the flexible printed circuit board. [8] Measuring arrangement (38) according to one of the preceding claims, characterized bythat the conductor loop (40) is formed by an uninterrupted electrical conductor, in particular a wire (42) and / or a conductor track (42), which, in a state fastened at the two points (32; 32a, 32b; 30; 30a; 44), is electrically insulated from the at least one battery cell (14), in particular is electrically insulated from all battery cells (14) comprised by the battery unit (10). [9] Measuring arrangement (38) according to one of the preceding claims, characterized by that at least a part of the conductor loop (40) is electrically conductively connected to a cell pole (18) of the at least one battery cell (14), in particular wherein the battery unit (10) comprises a plurality of battery cells (14), wherein at least two of the battery cells (14) are electrically contacted with one another via an electrically conductive cell connector (32; 32a), wherein the cell connector (32; 32a) is part of the conductor loop (40). [10] Method for detecting a mechanical stress on at least one housing component (14a; 16) of a housing (14a; 16) of a battery unit (10) comprising at least one battery cell (14), characterized by , that - a permanently uninterrupted conductor loop (40) electrically connected to an evaluation unit (34, 36) is fastened at two different locations (32; 32a, 32b; 30; 30a; 44) of the battery unit (10) in such a way that an expansion (Δs, Δs', Δs'') of the at least one battery cell (14) changes a distance between the two locations (32; 32a, 32b; 30; 30a; 44), and - the evaluation unit (34, 36) detects a change (ΔR, ΔR', ΔR'') in an electrical resistance of the conductor loop (40) and detects the mechanical stress as a function of the change (ΔR, ΔR', ΔR'').

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