LU507952B1

LU507952B1 - Battery assembly for electric vehicle

Info

Publication number: LU507952B1
Application number: LU507952A
Authority: LU
Inventors: Mario Cola Patrick Di; Arthur Cretin; Laurent Lamesch; Michael Olk; Peter Larsen; Thomas Stifter
Original assignee: Iee Sa
Priority date: 2024-08-07
Filing date: 2024-08-07
Publication date: 2026-02-09

Abstract

The invention relates to a battery assembly (10) for an electric vehicle (1), comprising a housing wall (11) delimiting a battery space (23) for a battery unit (25). In order to improve the operational safety of a battery unit of an electric vehicle in view of possible impact damage, the invention provides that the battery assembly also comprises a detection arrangement (12) comprising at least one impact sensor (13) and being adapted for detecting an impact-induced deformation of the housing wall (11).

Description

BATTERY ASSEMBLY FOR ELECTRIC VEHICLE

Technical Field

[0001] The present invention generally relates to a battery assembly for an electric vehicle, and more particularly to an EV battery assembly with integrity detection.

Background Art

[0002] Electric vehicles usually comprise a battery pack as the main energy storage device. The battery pack comprises a plurality of batteries or battery cells, which may be connected by a frame or shell. Apart from connecting the batteries mechanically, the shell also provides limited protection against damage. The battery pack and the shell or frame may collectively also be referred to as a battery unit. In order to facilitate the connection of the battery unit to the vehicle body, and to improve the mechanical protection, the battery unit is commonly placed inside a battery housing. The battery housing may provide protection against dirt, moisture, and impact by small objects.

[0003] However, since a usual installation location of the battery unit is at the bottom of the vehicle body, mechanical damage may occur, even without an impact being noticed by the driver. The impact may e.g. be caused by stones or other objects that are flung up against the bottom of the housing. Another possibility is the vehicle driving on an uneven terrain, e.g. over a curb during a parking maneuver.

Not only may the impact be unnoticed by the driver, but it may not even lead to a visible deformation. This is because the housing may only be deformed elastically and assume its undeformed shape after the impact. Still, apart from possibly reducing the lifetime of the housing, such an impact may potentially lead to a damage or predamage of the battery pack. This may not only impair the operability of the battery pack. Depending on the battery type, a damaged battery cell may also pose a serious risk to other vehicle components.

Technical Problem

[0004] It is therefore desirable to improve the operational safety of a battery unit of an electric vehicle in view of possible impact damage.

[0005] This problem is solved by a battery assembly according to claim 1.

General Description of the Invention

[0006] The invention relates to a battery assembly for an electric vehicle. The vehicle is preferably a road vehicle like a passenger car or a truck, but it could also be e.g. an electric motorcycle or an electric bicycle. The term “assembly” is not to be construed in any limiting way. Various components of the assembly, which are mentioned hereinafter, can be mechanically connected. However, some components may only be indirectly connected when the assembly is installed in the vehicle and may be coupled, e.g., electrically connected, to enable signal transmission. As will become apparent below, the assembly is related to a battery unit of the electric vehicle but does not necessarily comprise the battery unit.

[0007] The battery assembly comprises a housing wall delimiting a battery space for a battery unit. The term “battery unit” refers to a unit that may at least in some embodiments be also referred to as a battery pack. Such a battery unit comprises at least one battery, preferably a plurality of batteries or battery cells. The batteries may be connected by a frame or shell that mechanically connects them and may also provide some protection. As mentioned above, the battery unit itself is not necessarily part of the battery assembly, though. The housing wall represents at least a portion of a battery housing. In some embodiments, the battery wall may be identical to the battery housing. The housing wall delimits the battery space for the battery unit. The battery space represents a space in which the battery unit can be received. However, the battery space can be larger than the battery unit itself, i.e., the battery unit may not entirely fill the battery space when it is disposed therein.

The housing wall delimits the battery space on at least one side. Accordingly, the battery space is disposed on one side of the housing wall, which may be referred to as the inner side, while another side of the housing wall facing away from the battery space may be referred to as the outer side. Preferably, the housing wall is at least liquid tight, thereby preventing moisture as well as dirt from entering the battery space. The overall shape of the battery housing may be box-like, although other shapes are possible. Specifically, the battery housing may be adapted for mounting on a lower side of the vehicle body. In this case, it may comprise a front wall, a rear wall, lateral walls, and a bottom wall. Optionally, it may also comprise a top wall or lid. The housing wall may represent one or several of these walls. Its general shape may at least partially be planar, although it may e.g. comprise structures like beads to improve its structural stability.

[0008] Furthermore, the battery assembly comprises a detection arrangement comprising at least one impact sensor and being adapted for detecting an impact- induced deformation of the housing wall. The detection arrangement may comprise one or several components. It at least comprises one impact sensor. The term “impact sensor” describes the general function of the sensor and the detection arrangement and is not to be construed in any limiting way. The detection arrangement is adapted for detecting an impact-induced deformation of the housing wall. “Impact-induced” means that the deformation is caused by an impact, more specifically by an impact of an object on the outer side of the housing wall. The impact deformed the housing wall elastically and/or plastically. It is preferred that the detection arrangement is adapted to detect an elastic deformation. This is particularly important since the housing wall, after being elastically deformed, will return into its undeformed state so that visual inspection of the housing wall may not give any hint to the impact that has occurred. While some minor deformations may be considered as unimportant or negligible, it is desirable that the detection arrangement can detect any deformation above a certain threshold. The at least one impact sensor can be used to detect the deformation. In this context, an impact sensor is considered as “adapted for detecting the deformation” even if it needs to be connected to an additional component to achieve the detection process.

[0009] Since the inventive battery assembly allows for a detection of an impact on the housing wall, such an impact, which may potentially lead to a damage of the battery unit, does not go unnoticed. Due to the detection of the impact, it is possible to check the housing wall and especially the battery unit for possible damage. The check may be performed during a routine inspection, or an extraordinary inspection may be performed in response to the detected deformation. In some embodiments, the detection arrangement may only detect the deformation as such, while in other embodiments, it may also detect the magnitude or severity of the deformation. In the latter case, the magnitude of the deformation can be used as a criterion whether an extraordinary inspection is necessary. It will be noted that the information about an impact and possibly about the magnitude of the resulting deformation can also be used to trigger an emergency state (shutdown) at a specific "emergency state"

threshold. This "emergency state" threshold may equal to the "extraordinary inspection” threshold or differ from the "extraordinary inspection” threshold.

[0010] According to one embodiment, the housing wall comprises a bottom portion which in assembled state is disposed underneath the battery space, and the detection arrangement is adapted for detecting an impact-induced deformation of the bottom portion. The bottom portion may also be referred to as the above- mentioned bottom wall. This includes the possibility that the housing wall also comprises a front wall, area wall and/or lateral walls. “In assembled state” refers to a state in which the battery assembly is mounted to the electric vehicle. “Underneath” refers to the reference system defined by the longitudinal axis (X- axis), the lateral axis (Y-axis) and the vertical axis (Z-axis) of the electric vehicle.

The bottom portion is disposed underneath or below the battery space with respect to the vertical axis of the electric vehicle. For several reasons, the bottom portion in particular needs to be monitored for impact. The one hand, it is usually the largest portion of the battery housing. Furthermore, it is the lowest part of the battery housing and is therefore most likely to be hit by a foreign object. It should be noted that in this embodiment, the detection arrangement may also be adapted to detect a deformation of at least one sidewall portion, which may be a front, rear and/or lateral portion.

[0011] It is preferred that at least one impact sensor is at least indirectly mounted to the housing wall. Thus, it is either directly or indirectly, via at least one intermediate component, connected to the housing wall. On the one hand, this mechanical connection facilitates the detection of the deformation. On the other hand, integration of the impact sensor and the housing wall into one assembly can facilitate an assembly or disassembly process. Specifically, the position of the impact sensor with respect to the housing wall, which may be critical for a reliable detection, remains unchanged if the housing wall is connected to or disconnected from the vehicle body. If the detection arrangement is adapted for detecting a deformation of the above-mentioned bottom portion, at least one impact sensor may at least indirectly be connected to the bottom portion. The same applies to a detection on a sidewall portion.

[0012] It is conceivable that an impact sensor could be disposed on an outer side of the housing wall or could be integrated into the housing wall, e.g., between two layers thereof. One embodiment provides that at least one impact sensor is disposed on an inner side of the housing wall facing the battery space. On the one hand, the impact sensor is thus protected from dirt, moisture, and mechanical damage by the housing wall. On the other hand, it is relatively easy to install as compared to an integration into the housing wall. Moreover, it may be beneficial that the impact sensor is disposed on the same side of the housing wall as the battery unit. At least with some types of sensors, this makes it easier to detect a deformation that could potentially damage the battery unit.

[0013] The detection arrangement could comprise only a single impact sensor.

However, it is hardly possible to detect a deformation in various parts of the housing wall with only one impact sensor. Therefore, the detection arrangement preferably comprises a plurality of impact sensors. Advantageously, these are arranged in a two-dimensional distribution. Thus, they can effectively cover a two-dimensional area like a surface of the housing wall. The distribution may be an irregular or a regular one. In the latter case, the impact sensors could be arranged along lines that are parallel to the X-axis and/or the Y-axis. The total number of sensors and their relative distance may be chosen, e.g. based on simulation studies, depending on various factors. For instance, a larger area generally requires a larger number of sensors in order to guarantee a reliable detection. Also, a higher sensitivity of the individual sensor may allow for a greater distance between neighboring sensors. In this context it should be noted that due to mechanical deformation of the battery unit the sensor may be located outside an area of interest, i.e. outside the actual area of impact, and deduce damage from consequential bending of the unit (due to an impact).

[0014] As mentioned above, the battery assembly may also comprise the battery unit. According to one such embodiment, a deformation space is interposed between the battery unit and at least one impact sensor in an undeformed state of the housing wall. When the housing wall is in its undeformed state, the respective impact sensor is not in contact with the battery unit but separated therefrom by the deformation space. This embodiment allows for a certain amount of deformation before a mechanical interaction between the battery unit and the impact sensor can occur. Therefore, in case of a minor deformation, no force or pressure will act on the battery unit. Also, if the detection depends on a mechanical interaction with the impact sensor, the minor deformation will not be detected. Preferably, the housing wall is also at least partially separated from the battery unit by the deformation space.

[0015] The detection arrangement preferably comprises a control unit operatively connected to at least one impact sensor and being adapted to detect the impact- induced deformation based on a signal from the at least one impact sensor. The control unit is operatively coupled to at least one impact sensor, preferably to all impact sensors. “Operatively coupled” or “coupled” here and in the following refers to a coupling that enables an electric connection and a transfer of an electric signal.

This may refer to an electrically conductive connection, as well as a capacitive coupling and/or an inductive coupling, i.e., a coupling through electromagnetic fields. There may be a dedicated connection for each individual impact sensor. On the other hand, a group of impact sensors or even all impact sensors can be connected to the control unit by a single connection. Preferably, the at least one impact sensor and the control unit are physically separate from each other. It is possible, though, that at least one of the impact sensors may be physically integrated into the control unit. The control unit may receive a signal from an impact sensor and/or control an impact sensor. Also, it may internally perform logical operations and/or calculations. At least some functions of the control unit may be software-implemented. It will be appreciated that, as the electric signals from the impact sensor may be dynamic in nature, an algorithm may be used to assess if the time-domain evolution of the signals represent a critical case or not. The control unit can be adapted to record data documenting the deformation in a memory unit, e.g., an error memory. Alternatively or additionally, it can be adapted to output a warning signal to the driver of the vehicle.

[0016] One embodiment provides that the control unit is adapted to detect the impact-induced deformation based on an electric property of at least one impact sensor that is changeable by the impact-induced deformation. In this embodiment, the control unit may apply a detection signal to the respective impact sensor. The detection signal is an electric signal, which could also be a constant current and/or voltage. Then, the control unit may receive a response signal from the sensor that depends on the electric property. By way of example, if the detection signal corresponds to a defined voltage applied to the impact sensor, the response signal could be a current through or into the impact sensor. If the detection signal is an alternating voltage or alternating current signal, this may also be true for the response signal, wherein amplitude or a phase shift of the response signal may depend on the electric property of the impact sensor. It will be noted that a time dependent electrical signal may be configured to have an appropriate duty cycle to enhance the life time in case of resistance or force-sensitive resistor based sensor.

[0017] As already stated, the at least one impact sensor may be a simple switch with a purely resistive switch behaviour. It is however preferred that at least one impact sensor is force-sensitive, and the detection arrangement is adapted to detect the impact-induced deformation based on a force exerted on the impact sensor between the housing wall and the battery unit in a deformed state of the housing wall. A force-sensitive impact sensor can also be referred to as a “force sensor’.

Specifically, an electric property of the impact sensor may depend on a force exerted on the sensor. In this context, it is not distinguished between a sensor that responds to a certain amount of force and a sensor that response to a certain amount of pressure. This embodiment may be specifically combined with the above-mentioned embodiment in which the impact sensor is disposed on the inner side of the housing wall. It may also be combined with the embodiment in which the battery unit is separated from the impact sensor by the deformation space. In any case, when the housing wall is deformed to a sufficient extent, a force acts on the impact sensor that is located between the housing wall and the battery unit. Strictly speaking, this is a force pair comprising one force exerted by the housing wall and an opposite force exerted by the battery unit. At the same time, the sensor exerts a force on the battery unit, which could potentially lead to damage. The force only occurs due to the impact-induced deformation and therefore can be used as an indicator for this deformation. It is possible that the impact sensor responds to a deformation even before it is compressed between the housing wall and the battery unit. For instance, the deformation of the housing wall may lead to a deformation of the sensor that could change the response signal.

[0018] Various types of force-sensitive impact sensors could be used. For instance, the capacitance of the impact sensor could depend on the force exerted on the sensor. According to a preferred embodiment, at least one force-sensitive impact sensor has a resistance that depends on a force exerted on the impact sensor. This type of sensor can also be referred to as a force-sensitive resistor (FSR).

Specifically, the resistance may decrease as the force increases. The resistance may change continuously and/or stepwise as a function of the force. In some embodiments, the resistance may allow to at least approximately determine the magnitude of the force. In this embodiment, the control unit may apply a voltage of a certain magnitude as a detection signal, while the current through the at least one impact sensor can be used as a response signal. It will be understood that as the resistance decreases, the current increases. All sensors could be connected individually to the control unit, which would allow for determining the location of the deformation. On the other hand, groups of sensors or sensors could be connected in parallel. Although this would not allow for determining the location of the deformation, it greatly reduces the complexity and the costs for the connection and the associated electronics.

[0019] A particularly advantageous type of sensor is a foil-based sensor. According to such an embodiment, at least one force-sensitive impact sensor comprises a primary foil and a secondary foil, both foils being electrically insulating and forming a sandwich structure with a conductive switching structure interposed between the foils. The term “primary foil” and “secondary foil” are not to be construed in a limiting way. However, the primary foil may be the foil that is directly or indirectly connected to the housing wall, while the secondary foil faces the battery space. The foils are electrically insulating and may e.g. consist of a polymer like PET (polyethylene terephthalate), PEN (polyethylene naphthalate) or PI (polyimide). Between the two foils is a switching structure, which may comprise a first portion connected to the primary foil and a second portion connected to the secondary foil. The switching structure may be implemented in various ways. For instance, it can be constituted by conductive ink (e.g., silver ink) printed onto the foils and/or by etched, deposited or milled metal electrodes (e.g., aluminum or copper electrodes). The switching structure may be disposed in a sensitive region of the sensor, in which the foils are spaced apart as long as no force is acting on the sensor. In order to ensure a spacing between the foils in this sensitive region, at least one spacer element may be interposed between the foils. This spacer element should also be made of insulating material. The spacer element(s) can be disposed around the sensitive region. A foil-based sensor can be very thin, possibly even less than a millimeter in thickness, and is highly flexible. Therefore, it can be easily integrated in almost any location and requires only negligible space. It can be mounted to the inner side of housing wall by glueing. Also, a foil-based sensor can be designed to cover a smaller or larger area. Then, depending on the size and sensitivity of the impact sensor, a smaller or larger area can be monitored for a deformation. As stated above, an impact may be reliably detected even if the sensor is located outside an area of interest, ie. outside the actual area of impact. Due to mechanical deformation of the battery unit the sensor may deduce damage from consequential bending of the unit (due to an impact) even if the impact occurs only in the vicinity of the sensor and not on the sensor itself.

[0020] In case of a plurality of impact sensors, every sensor could be produced separately and have its own dedicated pair of foils. According to another embodiment, a plurality of spaced-apart impact sensors are connected by a base foil which constitutes the primary foil of these impact sensors. The base foil also covers an area between the impact sensors. The impact sensors can be referred to collectively as a sensor group or sensor unit. The size of the base foil and the distribution of the impact sensors thereon have to be designed in advance for the specific application. On the other hand, combining the sensors in a common sensor group facilitates the assembly process of the battery assembly. One could also say that the sensors represent active areas or sensitive areas on the base foil.

[0021] Preferably, the base foil is connected to the housing wall. More specifically, it may be connected to the inner side of the housing wall, e.g. by glueing. Since the base foil covers a relatively large area, the respective connection is extremely secure. Also, due to the flexibility of the base foil, it can be adapted to the shape of the housing wall, even if the surface of the housing wall is not (fully) planar. Finally, it will be appreciated, that the base foil may be provided with openings to allow passage of mounting elements such as screws, rivets, clips or the like.

[0022] Apart from connecting the individual sensors with each other, and possibly connecting them to the housing wall, the base foil may have additional functions. In one embodiment, connection lines, which are electrically connected to the impact sensors, are disposed on the base foil. The connection lines are of course electrically conducting structures. These may be printed onto the base foil with conductive ink. If needed, the connection lines may be covered with a protection foil,

which could be made of the same material as the secondary foil. The connection lines are adapted to be at least indirectly connected to the control unit. For instance, connector, which are electrically connected to the connection lines, may be disposed on the base foil, e.g., at an edge thereof. These connectors can be detachably connected to corresponding connectors of a cable that is connected to the control unit. It will be understood that this is just one option.

[0023] In order to improve the effectiveness of the detection arrangement, at least one compressive element can be interposed between an impact sensor and the battery unit. The compressive element can preferably be connected to the impact sensor. Alternatively, it may also be regarded as part of the sensor. The compressive element may be made of an elastomer, like EPDM (ethylene propylene diene monomer) or a foam material such as PE or PU. Due to its compressibility, its shape can to some extent adapt to a force acting on it. It may therefore serve as a buffer that prevents excessive local pressure. On the other hand, a compressive element, if small enough, may also help to focus a force onto a certain area or region. Specifically, the compressive element may be disposed over the sensitive region. As the impact sensor approaches the battery unit due to the deformation of the housing wall, the compressive element will get into contact with the battery unit.

This will then lead to a localized pressure on the sensitive region of the impact sensor, facilitating its activation. By adjusting the size and the physical properties of the compressive element, the sensitivity of the impact sensor can be adjusted according to various requirements. It will further be noted that, an impact may be reliably detected even if the sensor is located outside an area of interest, i.e. outside the actual area of impact. Due to mechanical deformation of the battery unit the sensor may deduce damage from consequential bending of the unit (due to an impact) and/or the compressive element even if the impact occurs only in the vicinity of the sensor and not on the sensor itself.

Brief Description of the Drawings

[0024] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawing, in which:

Fig. 1 is a schematic side view of an electric vehicle with a first embodiment of an inventive battery assembly;

Fig. 2 is a sectional view according to the line II-Il in fig.1, with a housing wall in an undeformed state;

Fig. 3 is a detail view of fig.2;

Fig. 4 is a sectional side view corresponding to fig.3, with the housing wall in a deformed state;

Fig. 5 is a top view of a part of the battery assembly from fig 1; and

Fig. 6 is a top view of a part of a second embodiment of a battery assembly.

Description of Preferred Embodiments

[0025] Fig.1 is a schematic view of an electric vehicle 1 with a first embodiment of an inventive battery assembly 10. Figs. 2 to 5 show the battery assembly 10 in detail.

For sake of reference, a longitudinal axis X, a lateral axis Y and a vertical axis Z of the electric vehicle 1 are shown in the figures. It should be appreciated that all figures are schematic and are not to scale. The battery assembly 10 comprises a housing wall 11 that is connected to an underside of a vehicle body 2. The housing wall 11 defines a battery space 23 in which a battery unit 25 is received. The overall shape of the housing wall 11 is box-like with a bottom portion 11.1, a front portion 11.2, arear portion 11.3, two lateral portions 11.4. and a lid portion 11.5. The battery unit 25, which may comprise a plurality of battery cells (not shown), is connected to the lid portion 11.5 and is spaced from the remaining portions 11.1 - 11.4 by a deformation space 27. A plurality of impact sensors 13 are connected to an inner side 11.6 of the bottom portion 11.1. The impact sensors 13 belong to a detection arrangement 12 and are connected to a control unit 30 that is disposed within the vehicle body 2. It will be noted that further impact sensors 13 may be arranged on an inner side of the front portion 11.2 and/or of the rear portion 11.3 and/or of the lateral portions 11.4. (not shown).

[0026] As can be seen in the detail view of fig. 3, the impact sensors 13 are foil- based sensors that comprise a primary foil 15 and a secondary foil 16 made of electrically isolating material, e.g., PET, PEN or PI. The foils 15, 16 are spaced apart by interposed space elements 17, which are likewise electrically isolating. The spacer elements 17 do not extend into a central part of the impact sensor 13, which can be referred to as a sensitive region 13.1. Within this sensitive region 13.1,

conducting elements of a switching structure 18 are disposed. These can be made of conducting ink printed onto the foils 15, 16, or can be etched, deposited or milled metal structures. À compressible element 19 is disposed on top of the secondary foil 16, over the sensitive region 13.1. This compressive element 19 can be made of an elastomer like EPDM. For sake of simplicity, the compressive elements 19 are not shown in the top view of fig.5.

[0027] The switching structure 18 is connected to connection lines 20, which can be seen in fig.5 but are not shown in fig.3. The connection lines 20, which may be made of the same material as the switching structure 18, are disposed on a base foil 14, which constitutes the primary foil 15 for all impact sensors 13. The base foil 14, which is partially removed in fig.5, is glued to the inner side 11.6 of the housing wall. The connection lines 20 connect the switching structures 18 of all impact sensors 13 in parallel to a pair of connectors 21. In assembled state, these connectors 21 are electrically connected to the control unit 30. The control unit 30 can apply a detection signal to the impact sensors 13. This detection signal may, e.g., be a direct voltage signal. The control unit 30 can then detect a response signal from the impact sensors 13, e.g., the collective current through the impact sensors 13. When no force F is acting on the impact sensor 13, the switching structure 18 does not establish an electrical connection, wherefore the current is negligible, corresponding to a very high resistance. When a force F acts on the impact sensor 13, the foils 15, 16 are moved together in the sensitive region 13.1 so that the switching structure 18 can establish an electric connection. The resistance of the impact sensor 13 drops significantly and the current increases. This can be registered by the control unit 13. It will be noted that printed fixed resistances can be used as diagnostics elements for each sensor element. Such printed fixed resistances can e.g. be connected in parallel with the sensing resistors to allow a diagnostic current to flow even if no force acts on the impact sensor.

[0028] Figs.2 and 3 show the housing wall 11 in an undeformed state. Fig.4, on the other hand, shows the housing wall 11 in a deformed state, which may be due to an impact by a foreign object (not shown). This could e.g., be a curb that is hit by the housing wall 11 during a parking maneuver of the electric vehicle 11. Due to the deformation of housing wall 11, specifically the bottom portion 11.1 thereof, at least one of the impact sensors 13 is moved through the deformation space 27 into contact with the battery unit 25. If the impact-induced deformation is great enough, as shown in fig.4, a force F is exerted on the impact sensor 13 between the bottom portion 11.1 and the battery unit 25. The compressible element 19 is the first element to make contact with the battery unit 25 and is designed to focus the pressure on the sensitive region 13.1. The diameter and the thickness of the compressible element 19 thereby will determine the sensor sensitivity. The resistance of the impact sensor 13 drops as described above. The control unit 30 takes this as a sign of a relevant impact-induced deformation, which could potentially damage the battery unit 25. The control unit 30 can store data representing the deformation in an internal or external memory device. Alternatively or additionally, it can output a warning signal to the driver of the electric vehicle 1. Either way, the battery unit 25 can later be inspected for relevant damage, even if there is no visible, permanent deformation of the housing wall 11.

[0029] Fig.5 shows a total number of nine impact sensors 13 arranged in a two- dimensional distribution. In this case, the sensors 13 are arranged in a rectangular pattern of three times three. The number of sensors 13 and their size with respect to the total surface area of the bottom portion 11.1 can be varied according to different requirements. Fig.6 shows an alternative embodiment in which the impact sensors 13 are arranged in seven lines of alternatingly two or three impact sensors 13, corresponding to a total of eighteen sensors 13. As compared to fig.5, the impact sensors 13 are smaller and they are more densely distributed. This may allow for a more reliable detection. Both embodiments show all impact sensors 13 connected in parallel, wherefore the control unit 30 cannot determine the location of the deformation, at least not with a direct voltage signal. In a different embodiment, each impact sensor 13 could be connected individually to the control unit 30, so that a location and/or distribution of a deformation can be determined. This may facilitate the inspection of the battery unit 25.

Legend of Reference Numbers: 1 electric vehicle 2 vehicle body battery assembly 11 housing wall 11.1 bottom portion 11.2 front portion 11.3 rear portion 11.4 lateral portion 11.5 lid portion 11.6 inner side 12 detection arrangement 13 impact sensor 13.1 sensitive region 14 base foil primary foil 16 secondary foil 17 spacer element 18 switching structure 19 compressible element connection line 21 connector 23 battery space battery unit 27 deformation space control unit

F force

X longitudinal axis

Y lateral axis

Z vertical axis

Claims

1. A battery assembly (10) for an electric vehicle (1), comprising a housing wall (11) delimiting a battery space (23) for a battery unit (25), and a detection arrangement (12) comprising at least one impact sensor (13) and being adapted for detecting an impact-induced deformation of the housing wall (11).

2. A battery assembly according to claim 1, wherein the housing wall (11) comprises a bottom portion (11.1) which in assembled state is disposed underneath the battery space (23), and the detection arrangement (12) is adapted for detecting an impact-induced deformation of the bottom portion

(11.1).

3. A battery assembly according to any of the preceding claims, wherein at least one impact sensor (13) is at least indirectly mounted to the housing wall (11).

4. A battery assembly according to any of the preceding claims, wherein at least one impact sensor (13) is disposed on an inner side (11.6) of the housing wall (11) facing the battery space (23).

5. A battery assembly according to any of the preceding claims, wherein the detection arrangement (12) comprises a plurality of impact sensors (12) arranged in a two-dimensional distribution.

6. A battery assembly according to any of the preceding claims, further comprising the battery unit (25), wherein a deformation space (27) is interposed between the battery unit (25) and at least one impact sensor (13) in an undeformed state of the housing wall.

7. A battery assembly according to any of the preceding claims, wherein the detection arrangement (12) comprises a control unit (30) operatively connected to at least one impact sensor (13) and being adapted to detect the impact- induced deformation based on a signal from the at least one impact sensor (13).

8. A battery assembly according to any of the preceding claims, wherein the control unit (30) is adapted to detect the impact-induced deformation based on an electric property of at least one impact sensor (13) that is changeable by the impact-induced deformation.

9. A battery assembly according to any of the preceding claims, wherein at least LU507952 one impact sensor (13) is force-sensitive, and the detection arrangement (12) is adapted to detect the impact-induced deformation based on a force (F) exerted on the impact sensor (13) between the housing wall (11) and the battery unit (25) in a deformed state of the housing wall (11).

10. A battery assembly according to any of the preceding claims, wherein at least one force-sensitive impact sensor (13) has a resistance that depends on a force (F) exerted on the impact sensor (13).

11. A battery assembly according to any of the preceding claims, wherein at least one force-sensitive impact sensor (13) comprises a primary foil (15) and a secondary foil (16), both foils (15, 16) being electrically insulating and forming a sandwich structure with a conductive switching structure (18) interposed between the foils (16).

12. A battery assembly according to any of the preceding claims, wherein a plurality of spaced-apart impact sensors (13) are connected by a base foil (14) which constitutes the primary foil (15) of these impact sensors (13).

13. A battery assembly according to any of the preceding claims, wherein the base foil (15) is connected to the housing wall (11).

14. A battery assembly according to any of the preceding claims, wherein connection lines (20), which are electrically connected to the impact sensors (13), are disposed on the base foil (14).

15. A battery assembly according to any of the preceding claims, wherein at least one compressive element (19) is interposed between an impact sensor (13) and the battery unit (25).