DE102021109135A1 - Single-layer deformation detection device for an energy store - Google Patents

Abstract

The invention relates to a deformation detection device and a method for an energy storage assembly that is integrated into a vehicle support structure of a motor vehicle and has an energy storage device and a housing structure, having a strain gauge element that is formed on an outer housing structure element, and an evaluation unit that is set up to detect a change in an electrical to capture operating parameters.

Description

The invention relates to a deformation detection device for an energy storage assembly integrated into a vehicle support structure of a motor vehicle, and to a vehicle information system with such a deformation detection device. Furthermore, the invention relates to a method for detecting a deformation of an energy storage assembly.

For structure-integrated high-voltage storage, a typical design of an energy storage assembly in a motor vehicle, the space available in the vertical direction of the vehicle is severely limited. In order to arrange a sufficient number of energy storage cells in this limited installation space, it is necessary to make the best possible use of the installation space, particularly in the vertical direction of the vehicle. At the same time, however, sufficient robustness of the high-voltage battery must be ensured against mechanical stress from the outside, in particular against stresses that are not introduced via functional chains that are determined for the entire vehicle. This conflict of objectives is normally resolved via a chain of mechanical damage in which, in the event of mechanical overload of the entire vehicle, peripheral and/or sacrificial components fail in a targeted manner in order to protect load-bearing structural components through the energy reduction achieved.

From the DE 10 2018 200 919 A1 a detection device for detecting a mechanical deformation of a high-voltage battery of a motor vehicle is also known, comprising: a sensor element that detects an electrical measured variable, the sensor element being essentially flat and being attached at least partially to a first component of the high-voltage battery; and an evaluation device for analyzing the electrical measured variable between the sensor element and a second component of the high-voltage battery and for outputting a corresponding warning message based on the electrical measured variable, with at least one area of the surface of the second component being electrically conductive.

Against this background, it is an object of the invention to improve deformation detection for an energy storage assembly.

This object is achieved by a deformation detection device having the features of claim 1, a vehicle information system having the features of claim 9 and a method for detecting a deformation of an energy storage assembly having the features of claim 10. The dependent claims relate to advantageous developments of the invention.

1. (a) eine Sensiereinrichtung mit wenigstens einem flächigen Dehnungsmesselement, das mit einem äußeren Gehäusestrukturelement der Energiespeicherbaugruppe, insbesondere bezüglich seiner gesamten flächigen Erstreckung, fest verbunden und dazu ausgebildet ist, bei einer Deformation entlang und/oder orthogonal zu seiner Erstreckungsfläche seinen elektrischen Widerstand, insbesondere messbar, zu ändern. Unter einem flächigen Dehnungsmesselement ist insbesondere ein Dehnungsmesselement zu verstehen, das sich hinsichtlich zweier Raumachsen sehr viel weiter erstreckt als hinsichtlich der dritten Raumachse, und beispielsweise als Blech, Folie oder anderes dünnes Bauteil ausgebildet ist.
2. (b) eine Auswerteeinheit, die dazu eingerichtet ist, eine Veränderung des elektrischen Widerstands des Dehnungsmesselements zu erfassen. Das Erfassen kann insbesondere mittelbar erfolgen, indem eine am Dehnungsmesselement anliegende Spannung erfasst und ausgewertet wird.

According to one aspect, a deformation detection device for an energy storage assembly integrated in a vehicle support structure of a motor vehicle with an energy storage and a housing structure is disclosed. The deformation detection device has at least:

1. (a) a sensing device with at least one flat strain gauge element, which is firmly connected to an outer housing structure element of the energy storage assembly, in particular with respect to its entire flat extent, and is designed to have its electrical resistance, in particular measurable, in the event of a deformation along and/or orthogonally to its extension surface , to change. A flat strain gauge element is to be understood in particular as a strain gauge element that extends much further with respect to two spatial axes than with respect to the third spatial axis, and is designed, for example, as a sheet metal, foil or other thin component.
2. (b) an evaluation unit that is set up to detect a change in the electrical resistance of the strain gauge element. The detection can in particular take place indirectly by detecting and evaluating a voltage applied to the strain gauge element.

It is thus possible to record any relevant deformation of the energy store, specifically its lower housing structure. In contrast to the known solutions, not only a serious defect can be detected, but also slight deformations, which enables a finely structured reaction logic to different degrees of damage to the lower housing structure and possibly also to the energy store itself.

In the present case, the energy storage assembly is in particular an electric traction battery with a plurality of battery modules and/or cells, which are accommodated with a battery management system in a load-bearing housing.

The term "energy storage device integrated into a vehicle support structure" is to be understood in particular as an energy storage device whose housing, in addition to the functions of protecting the energy storage cells and battery management from environmental influences and the environment from the stored electrical and/or thermal energy, is also designed and set up to To carry loads from a weight and / or a driving dynamics and / or a crash contact of the vehicle and / or absorb and / or brace against other carrier components.

In the present case, an outer housing structure element is to be understood in particular as a component part of a lower housing structure of the energy store. In particular, the outer housing structural element is designed in the form of a shell and/or trough and/or in the manner of a sliding panel. According to one embodiment, the strain gauge element is applied to the outer structural element of the housing in the form of a printed conductor track that is glued on, in particular on a thin metal sheet or foil.

According to one embodiment, a damping material, such as a suitable hardened foam, is provided between the energy store of the energy store assembly on the one hand and the outer housing structure element on which the sensing device is arranged on the other hand, for absorbing loads in the event of deformation. For example, the damping material occupies a large part or all of the space between the energy store and the outer housing structural element. Due to the load-bearing capacity of the damping material, a distance between the energy store and the outer housing structure element can be reduced in the vertical direction of the vehicle.

The energy store itself is in particular a high-voltage store in the vehicle, for example in the sense of a traction battery. The energy storage device has, in particular, several electrochemical battery cells connected in series and/or parallel to one another and/or can be constructed from several battery modules connected in series and/or parallel to one another, each having a plurality of battery cells.

According to a further aspect of the invention, a vehicle information system is disclosed which in particular has a deformation detection device according to an embodiment of the invention and an output means which is set up and designed to output information to at least one vehicle user. The output means is also set up to output a warning message, in particular one that can be reliably perceived, to a vehicle occupant, in particular a driver and/or another occupant, and/or a vehicle environment when a change threshold of an electrical voltage of the sensing device detected by the evaluation device is exceeded.

As a result, the consequences of damage to the energy storage assembly can be minimized, especially with regard to personal injury, but possibly also with regard to property damage, in particular by advising the warning message to visit the workshop immediately or to park the vehicle in an empty open space as quickly as possible or to leave the damaged vehicle immediately.

In particular, the warning message is output by means of the output means after a corresponding activation by means of the evaluation unit. In particular, exceeding the change threshold represents a presumed exceeding of a mechanical load limit of the energy storage assembly, which is why the limit value is set at the selected level.

• - einen Bildschirm für eine optische Ausgabe einer Warnmeldung und/oder eine Warnlampe für eine optische Ausgabe eines Warnsignals, und/oder
• - einen Lautsprecher für eine akustische Ausgabe eines Warnsignals und/oder einer Warnmeldung, und/oder
• - eine, insbesondere in ein Lenkrad des Fahrzeugs integrierte, haptische Warnvorrichtung für eine haptische Ausgabe eines Warnsignals.

In particular, the output means is set up to output the warning message in a way that ensures that the message is perceived by the intended recipient(s), for example by the output means having:

• - a screen for a visual output of a warning message and/or a warning lamp for a visual output of a warning signal, and/or
• - a loudspeaker for an acoustic output of a warning signal and/or a warning message, and/or
• - A haptic warning device, integrated in particular in a steering wheel of the vehicle, for a haptic output of a warning signal.

According to another aspect of the invention, a motor vehicle is disclosed having an energy storage assembly that is part of a vehicle support structure of the motor vehicle. The motor vehicle has in particular a vehicle information system according to one embodiment of the invention.

1. (i) Erfassen wenigsten einer an einer Sensiereinrichtung anliegenden elektrischen Spannung zum Überwachen eines elektrischen Widerstands der Sensiereinrichtung.
2. (ii) Vergleichen einer sensierten Änderung der elektrischen Spannung mit einer Änderungsschwelle, die repräsentativ für eine potentiell schädliche Deformation der Energiespeicherbaugruppe ist.
3. (iii) Ausgeben einer Warnung an einen Fahrzeuginsassen und/oder die Fahrzeugumgebung, falls die Änderungsschwelle überschritten ist.

According to a further aspect of the invention, a method for detecting a deformation of an energy storage assembly is disclosed, the method being designed in particular to be carried out using a deformation detection device according to an embodiment of the invention. The method has at least the following method steps:

1. (i) detecting at least one electrical voltage applied to a sensing device to monitor an electrical resistance of the sensing device.
2. (ii) comparing a sensed change in electrical voltage to a change threshold representative of a potentially damaging deformation of the energy storage assembly.
3. (iii) Issuing a warning to a vehicle occupant and/or the vehicle environment if the change threshold is exceeded.

The method makes use of the fact that the electrical resistance of the strain gauge element changes with each deformation of that area of the outer housing structure element to which the strain gauge element is connected flat and firmly, and this can be measured in a manner that can be predetermined in advance for the evaluation unit. The change in resistance can be detected via a change in the electrical voltage between two contact points of the strain gauge element.

The pre-determination of the voltage changes to be expected takes place, for example, when data is entered into a characteristic map for different operating states and/or different deformations of the energy storage assembly in vehicle development by means of tests.

According to one embodiment, the evaluation unit is set up to apply a known electrical voltage to the strain gauge element when the motor vehicle is in the intended operating state and/or to apply a, in particular unforeseen, change in the applied voltage, in particular in the event of any deformation, especially if a mechanical load limit of the strain gauge is exceeded lower housing structure of the vehicle structure-integrated component to detect.

As a result, even the smallest deformations and/or displacements of the strain gauge element can be detected. In particular, with a deformation of the outer housing structure element in a measuring area, the shape of the strain gauge element and thus its electrical resistance also change. The change in voltage can be measured by the evaluation unit using a voltage sensor.

In particular, the evaluation unit is set up to detect and/or evaluate manifestations of an electrical voltage that is applied to the strain gauge element, and in particular the change therein.

According to one embodiment, the evaluation unit is set up to detect a deformation when a change threshold for the change in the electrical resistance of a strain gauge element and/or the applied voltage as a measured variable that is representative of the change in resistance is exceeded. As a result, stress changes (which tend to be smaller) due to dynamic loads from regular driving operations can be differentiated from damage events (which tend to be larger stress changes).

According to one embodiment, the evaluation unit is set up to detect a permanent deformation if a changed measured value, in particular for the voltage, in particular constant, occurs after a detected change.

This enables a distinction to be made between elastic and plastic deformations of the strain gauge element. In the case of an elastic deformation of the strain gauge element, it can also be assumed, according to one embodiment, that the outer housing structural element is at most elastically deformed.

According to one embodiment, the evaluation unit has a damage determination logic that is set up to assign different damage classes to different degrees of severity and/or different localization and/or different lengths of time, in particular in the electrical resistance of the strain gauge element (due to the different and distinguishable voltage changes).

In particular, it is provided that different change threshold values for the voltage are stored in the evaluation unit and/or a higher damage class is assigned, the higher a change threshold is exceeded.

This enables a more accurate failure prognosis and thus safe operation of the energy store for the vehicle user and/or the environment while at the same time requiring little installation space in the vertical direction of the vehicle.

According to one embodiment, a predetermined breaking point, in particular mechanical, for its electrical conductivity is arranged on the strain gauge element, which is designed in such a way that it triggers at a predetermined stress limit of an environmental protection of the energy store, in particular mechanically fails with loss of the electrical contacting effect.

According to one embodiment, the sensing device, in particular its strain gauge element(s), is arranged on a surface of an inside of the outer housing structure element. As a result, a deformation of the outer housing structural element can be detected immediately and directly.

In particular, the sensing device, in particular its strain gauge element(s), is firmly connected with a flat contact side to a surface of the outer housing structural element, in particular glued or welded thereto. According to different embodiments, a strain gauge element and/or its conductor track(s) can instead be attached to the housing structure be printed and/or etched and/or lithographed and/or sputtered and/or vapor-deposited, with the respective advantages that these joining methods bring with them, as is known in the art.

This ensures reliable transmission of any deformation of the outer housing structure element to the sensing device (and thus the detectable deformation of the strain gauge element).

According to one embodiment, the sensing device has at least one flat strain gauge sensor, i.e. Strain gauges, as a strain gauge element.

According to one embodiment, the strain gauge element has at least one conductor track, which is applied, in particular printed, in particular to a non-conductive carrier film or to an electrically insulated carrier sheet, in particular sheet steel. This ensures a thin structure, particularly in the vertical direction of the vehicle.

According to one embodiment, the sensing device has two or more, in particular separately from one another, strain gauge elements connected to the evaluation unit, the arrangement area of which on the outer housing structural element is, in particular in relation to an extension in a horizontal vehicle plane, in terms of an extension along a vehicle longitudinal direction and/or along a vehicle lateral direction differs from each other.

In this way, a spatially more detailed statement can be made about a damage class to be assigned. The damage class to be assigned can then also be based on local differences in the resilience of the energy storage device. It can thus be taken into account that the same load application at a first point of an energy store may cause less damage than at another point.

According to one embodiment, the evaluation unit is a control device arranged in the energy storage assembly. In particular, the evaluation unit can be designed as a logical and/or physical part of a battery management system. This ensures that the deformation detection device requires minimal installation space and/or integration.

• 1 zeigt in einer schematischen Schnittansicht eine Energiespeicherbaugruppe mit einer beispielhaften Ausführung einer Deformationsdetektionsvorrichtung mit einem Dehnungsmesselement.
• 2 zeigt in einer schematischen Schnittansicht eine Energiespeicherbaugruppe mit einer beispielhaften Ausführung einer Deformationsdetektionsvorrichtung mit mehreren Dehnungsmesselementen.
• 3 zeigt ein Ablaufdiagramm mit Schritten eines Verfahrens zur Detektion einer Deformation der Energiespeicherbaugruppe aus 1.

Further advantages and application possibilities of the invention result from the following description in connection with the figures.

• 1 shows a schematic sectional view of an energy storage assembly with an exemplary embodiment of a deformation detection device with a strain gauge element.
• 2 shows a schematic sectional view of an energy storage assembly with an exemplary embodiment of a deformation detection device with multiple strain gauges.
• 3 FIG. 12 shows a flowchart with steps of a method for detecting a deformation of the energy storage assembly 1 .

In 1 a section of a motor vehicle 1 is shown, which is designed with an electric traction machine (not shown), for example battery-electric (BEV) or plug-in hybrid (PHEV). As a traction battery for the electric drive motor, the motor vehicle 1 has an energy storage assembly 2, which is part of a vehicle support structure 4 of the motor vehicle, here the vehicle underbody. The energy storage assembly 2 has an energy storage 12 with a plurality of battery cells 14, round cells here, and a housing structure 16 with a housing trough 18 and a housing cover 20, which is formed by a vehicle floor component of the vehicle support structure 4. The housing trough 18 and the vehicle floor component of the vehicle support structure 4 are sealed against one another in a fluid-tight manner, so that the energy store is decoupled from the environment in this respect.

In addition, the motor vehicle 1 has a vehicle information system 6 . The vehicle information system 6 has a deformation detection device 8 for the energy storage assembly 2 and an output means 10 for the deformation detection device 8 .

The deformation detection device 8 has a sensing device 21 with a flat strain gauge element 22 and an electrical connection 23 . The strain gauge element 22 is formed on the surface of an inside of a housing structural element, here a base plate of the housing trough 18, and is glued to the base plate by means of a thin adhesive layer 25.

The flat strain gauge element 22 is formed with a very thin metal sheet, on which a conductor track is applied as a DMS sensor distributed over the flat extension in such a way that deformations on any parts of the entire extension area of the strain gauge element 22 can be detected. The representation with a two-layer arrangement of the voltage tap by means of the electrical connection is only for illustration. The trace can be in a single be arranged on a plane and is the present also.

A damping material 30 is arranged between the strain gauge element 22 and a cell contacting system 24, in this case a suitable, hardened foam for absorbing loads in the event of deformation. Both the strain gauge element 22 and the adhesive layer 25 are much thinner in relation to the thickness of the layer made of the damping material 30 than they are illustrated here.

The deformation detection device 8 also has an evaluation unit 26 which is set up to detect a change in an electrical voltage V present at the strain measuring element 22 .

Such a change can result in particular from a deformation D of strain gauge element 22, which in turn is caused by a force F from outside the vehicle, typically when the vehicle floor is placed on a pointed or angular obstacle.

This enables relevant deformations D of the energy storage assembly 2, especially the housing trough 18, to be detected. In contrast to the known solutions, not only a serious defect can be detected, but also slight deformations that may not immediately lead to a safety-critical failure of the energy storage assembly 2 , but lead to a later failure with a certain probability, so that a detection is desirable in order to be able to avert later damage if necessary by checking the integrity of the energy storage assembly 2, for example a visual inspection in the workshop.

The use shown here of a DMS-based sensor 22 as a strain gauge element can help to save installation space in a vehicle vertical direction z.

In the present case, when motor vehicle 1 is in a specified operating state, an electrical voltage of a predetermined and therefore known level is applied to strain gauge element 22 . With a deformation of the strain gauge element 22, which occurs essentially proportionally and/or uniformly to a deformation of the base plate of the housing trough 18 due to the firm adhesion 25, the conductor track of the strain gauge element 22 is stretched plastically and/or elastically - both with a deformation in a direction of the extension surface of the strain gauge element 22 as well as during a deformation out of this surface, ie at right angles to it.

The internal electrical resistance in the conductor track of the strain gauge element 22 changes with the strain. This change in resistance can be detected by means of a voltage sensor 34 and measured by the evaluation unit 26 . As a result, even the smallest deformations D of the strain gauge element 22 can be detected.

In the present case, a deformation is detected when a first voltage limit value is exceeded, which stands for a specific strength of the change in resistance at the strain gauge element 22 and thus for a specific strength and/or type of deformation D. As a result, stress changes caused by dynamic loads from regular driving - in which no deformation is then detected - can be differentiated from damage events.

The evaluation unit 26 can be programmed in such a way that it sets a deformation flag only if a new voltage that differs from the old voltage occurs after a detected voltage change. This enables a distinction to be made between elastic and plastic deformations of the strain gauge element.

In the present case, the evaluation unit 26 has a damage determination logic 36, by means of which changes in the detected voltage V of different magnitudes are assigned to deformations of different magnitudes and thus to different damage classes. In this way, different reactions of the vehicle information system 6 can be triggered in different cases of damage.

The output means 10 is set up to output a warning message to a vehicle occupant and/or a vehicle environment, for example by means of a combined audio and screen warning message M. The screen -Warning message contains instructions for action, which can differ depending on the location or the severity of the deformation D detected.

In 2 an energy storage assembly 102 is shown, which differs from the energy storage assembly 2 of 1 differs in that a plurality of strain gauge elements 122, 123 are designed in order to enable a locally finer detection of the deformation D*, which results from the action of the force F*.

For this purpose, deformation detection device 108 has a sensing device 121 with a plurality of strain gauge elements 122, 123, which are electrically separate from one another and whose arrangement area differs from one another with regard to an extension along a vehicle longitudinal direction x and/or along a vehicle transverse direction y.

By using voltage sensors 134, 135 to monitor and evaluate the electrical voltages V1 of the strain gauge element 122 and V2 of the strain gauge element 123 separately, a spatially more detailed statement can be made about a damage class to be assigned, in this case also the statement that the deformation D* in the arrangement area of the strain gauge element 123 occurs.

3 shows method steps of an exemplary method for detecting a deformation of the energy storage assembly 2 1 .

In step S10, an electrical voltage V applied to strain gauge element 22 is monitored.

In step S20, a sensed change in electrical voltage V is compared with a limit value V_G, which is representative of a potentially harmful deformation D.

If the limit value V_G is exceeded, a warning message M is output to a vehicle occupant and/or the vehicle environment in step S30.

If the limit value V_G is not exceeded, the electrical voltage V continues to be monitored in the sense of step S10, and step S20 is carried out again—possibly with a predetermined time offset.

Reference List

1

motor vehicle

2, 102

energy storage assembly

4

vehicle support structure

6

vehicle information system

8, 108

deformation detection device

10

output means

12

energy storage

14

battery cell

16

housing structure

18

housing tray

20

housing cover

21, 121

sensing device

22, 122, 123

strain gauge element

24

cell contacting system

25, 125

adhesive layer

26

evaluation unit

30

cushioning material

34, 134, 135

voltage sensor

36

damage determination logic

D, D*

deformation

f, f*

application of force

M

warning message

V

electrical voltage

V_G

Electrical voltage limit

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• DE 102018200919 A1 [0003]

Claims (10)

Deformation detection device (8, 108) for an energy storage assembly (2, 102) of a motor vehicle (1), having: - A sensing device (21, 121) with at least one flat strain gauge element (22; 122, 123), which is firmly connected to an outer housing structural element (18) of the energy storage assembly and is designed to measure its electrical resistance in the event of a deformation (D, D*). to change, - An evaluation unit (26) which is set up to detect a change in the electrical resistance of the strain gauge element. Deformation detection device according to claim 1 , wherein the evaluation unit is set up to - apply a predetermined electrical voltage to the sensing device when the motor vehicle is in a specified operating state, and/or - detect a change in the applied voltage (V; V1, V2). Deformation detection device according to one of the preceding claims, wherein the evaluation unit is set up to detect a deformation (D, D*) when a change threshold (V_G) for the change in the electrical resistance of the strain gauge element is exceeded. Deformation detection device according to one of the preceding claims, wherein the evaluation unit is set up to detect a permanent deformation if a changed measured value, in particular constant, occurs subsequent to a detected change. Deformation detection device according to one of the preceding claims, wherein the evaluation unit has damage determination logic (36) which is set up to assign different damage classes to different changes. A deformation detection device according to any one of the preceding claims, wherein the sensing means is disposed on a surface of an inside of the outer case structural member. Deformation detection device according to one of the preceding claims, wherein the sensing device is firmly connected with a flat contact side to a surface of the outer housing structural element. Deformation detection device according to one of the preceding claims, wherein the sensing device (32, 132) has two or more strain measuring elements (122, 123) connected separately from one another to the evaluation unit, the arrangement area of which on the outer housing structural element differs in terms of an extension along a vehicle longitudinal direction (x) and/or or differs from each other along a vehicle transverse direction (y). Vehicle information system (6), having a deformation detection device (8, 108) according to one of the preceding claims and an output means (10) which is set up to, when a change threshold (V_G) is exceeded in an electrical voltage (V; V1, V2) the sensor device (21, 121) to output a warning message (M) to a vehicle occupant and/or a vehicle environment. Method for detecting a deformation (D, D*) of an energy storage assembly (2, 102), having the method steps: - (S10) detecting at least one electrical voltage (V; V1, V2) present at a sensing device (21, 121), - (S20) comparing a sensed change in the electrical voltage with a change threshold (V_G), which is representative of a potentially harmful deformation (D, D*) of the energy storage assembly, - (S30) Outputting a warning (M) to a vehicle occupant and/or the vehicle environment if the change threshold is exceeded.

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