Underbody element for a traction battery of a motor vehicle, motor vehicle with an underbody element and method for detecting an intrusion of a traction battery of a motor vehicle

Abstract

Underbody element (2) for a traction battery (3) of a motor vehicle (1), comprising at least one sensor device (6), characterized in that the sensor device (6) has at least one electrically conductive sensor wire (8) which is integrated into a planar textile material (7), wherein the sensor device (6) is designed to measure a voltage applied to the sensor wire (8) and to detect a deformation of the sensor wire (8) as a function of a measured change in voltage.

Description

The invention relates to an underbody element for a traction battery of a motor vehicle, which comprises at least one sensor device, to a motor vehicle having such an underbody element, and to a method for detecting an intrusion of a traction battery of a motor vehicle.Nowadays, many motor vehicles are designed partly or fully electrically, for example as a hybrid vehicle or as a purely electrically operated motor vehicle. A drive battery or traction battery required for this purpose, which usually comprises a plurality of battery cells, is usually arranged in a floor region of the motor vehicle. This has the disadvantage that impacts from below directly strike the traction battery, which can lead to damage to the traction battery. In order to limit or to avoid damage due to intrusion from below, it is known to use an underbody element for the traction battery, which may be designed, for example, as underrun protection in order to protect the traction battery from a direct application of force. In this case, the underbody element may be a cladding on the underbody of the traction battery and / or of the motor vehicle, which cladding shields the traction battery from environmental influences and / or mechanical influences.However, an underbody element also does not keep all impacts away from the traction battery and, in the event of strong impacts from below, for example when the motor vehicle is placed on during a pylon crossing, the underbody element may be pressed into the traction battery and damage may thereby be produced to the traction battery. That is, intrusion of the traction battery may occur. In order that this type of damage can be ascertained and consequent damage to the motor vehicle and / or risks for a driver of the motor vehicle can be minimized, detection of these events is necessary in order to draw conclusions as to whether battery cells of the traction battery have experienced an intrusion. That is, a sensing concept is required in order to be able to determine a physical intrusion or a deformation of the traction battery.EP 1 168 463 A1 discloses a fiber composite material with a piezoelectric sensor or actuator integrated therein. In this case, the electrical leads for the actuator or sensor are designed in the form of electrically insulated, thin wires which are led out of the fiber composite material perpendicularly to the laminate layers, wherein the fibers are not severed by the lead-out of the leads, but rather are pushed apart.From DE 10 2017 206 663 A1, a battery pack comprising a plurality of battery cells arranged in a battery housing is known, wherein the battery housing has at least one electrically insulating protective plate, at least one deformation sensor comprising an electrically conductive coating which is applied to the protective plate, and at least one evaluation circuit for detecting a change in resistance of the at least one deformation sensor. In this case, a plurality of deformation sensors are provided, and the deformation sensors are arranged in separate segments of the protective plate.DE 10 2010 013 017 A1 discloses devices for securing batteries or battery arrangements in which one or more individual cells are arranged in a housing. For this purpose, one or more sensor elements are mounted in and / or on the housing, which emit a signal or interrupt a signal circuit when the housing is deformed or penetrated, which could also mechanically damage the individual cells and / or the batteries or battery arrangements formed therefrom, which signal circuit then leads by means of a monitoring device to a disconnection of the medium supply to the interior of the housing and / or the individual cells and or the batteries or battery arrangements or to an interruption of the power circuit of the battery system and possibly other units.DE 10 2011 013 182 A1 discloses a safety traction battery for electric vehicles, by means of which an effect of high dangerous voltage potentials on persons in the event of a crash is prevented.The invention is based on the object of detecting damage to a traction battery which originate from below the motor vehicle.This object is achieved by the independent patent claims. Advantageous refinements of the invention are disclosed in the dependent patent claims, the following description and the figures.The invention provides an underbody element for a traction battery of a motor vehicle, comprising at least one sensor device. The term underbody element is understood here to mean a floor covering, in particular an underride guard, which, in an intended installation position in the motor vehicle, is arranged in the direction of an underside of the motor vehicle and / or of the traction battery and which provides at least one protective effect against external influences. According to the invention, the underbody element has at least one sensor device, wherein the sensor device has at least one electrically conductive sensor wire which is integrated into a planar textile material, wherein the sensor device is designed to measure a voltage applied to the sensor wire and to determine a deformation of the sensor wire as a function of a measured change in the voltage.In other words, at least one electrically conductive sensor wire is integrated into a planar textile material. For example, the wire material can be applied to a planar textile semi-finished product. The textile material can serve as a carrier structure which can facilitate attachment of the sensor wire to the underbody element. Thus, for example, the textile material can be attached flat to the underbody element, such that the sensor wire is distributed uniformly on the underbody element and covers a large part of the underbody element. The textile material can be designed, for example, as a fiber composite material, whereby an increase in strength can be achieved. During operation, a current at a predefined voltage can flow through the sensor wire, which can be formed from a metal, for example, wherein a deformation of the sensor wire leads to a change in the voltage and, therefore, in the case of a detected change, the deformation of the underbody element and consequently an intrusion onto a traction battery of the motor vehicle can be detected. The invention has the advantage that a deformation, in particular a deformation of the underbody element, can be determined in a simple manner, wherein damage to the traction battery can be inferred by the deformation of the underbody element.The invention also encompasses embodiments which result in additional advantages.One embodiment provides that the sensor wire is integrated in meandering fashion in the flat textile material. In other words, the sensor wire can extend in a loop-like manner over a predetermined width of the textile material. This results in the advantage that the sensor wire covers a large area of the textile material while saving material of the sensor wire and thus an improved sensing of deformations can be provided.It is preferably provided that the sensor wire is formed from a carbon fiber or a metal-coated plastic filament. In other words, the sensor wire can be designed as carbon fiber or carbon fiber, which is incorporated into the planar textile material. The advantage of carbon is a very good electrical conductivity and at the same time an improved possibility of incorporating the sensor wire into the textile material. In addition, a structure of the underbody member can be reinforced by the carbon fiber. In particular, carbon can be processed as a fiber composite material. Alternatively, the sensor wire can be formed as a plastic filament coated with a metal. The advantage of a plastic filament is that it can be incorporated into the textile material particularly easily, which facilitates production and saves costs. The conductivity of the sensor wire is provided by the coating with metal. In a further alternative, the sensor wire can be formed from a metal, in particular copper, which can be incorporated into the textile material in a cost-effective manner.A further embodiment provides that the sensor wire is designed to change an electrical resistance during deformation. That is, the change in the voltage and thus the deformation of the sensor wire are detected by the sensor wire changing its electrical resistance. If the underbody element deforms, the length and / or diameter of the sensor wire change, resulting in a measurable change in resistance. The sensor wire can therefore preferably be provided from suitable materials, in particular carbon, which changes a length and thickness of the sensor wire upon deformation. Alternatively, the sensor wire can also break in the event of too great a deformation, wherein the change in the stress can be detected here if no more current flows through the sensor wire.A further embodiment provides that the sensor device is designed to generate a warning signal if the measured change in the voltage is above a predefined voltage threshold value. In other words, the sensor device can determine how great the change in voltage is. If the change is above a predetermined voltage threshold, a warning signal may be generated. The warning signal can preferably be used to warn a driver of the motor vehicle. For example, the warning signal may serve as a control signal for a warning light, which may indicate to the driver of the motor vehicle damage to the traction battery. The sensor device can also have an electronics or evaluation unit which measures and evaluates the voltage, wherein, depending on the measured change in the voltage, it is also possible to provide a plurality of voltage threshold values which can indicate different severity levels of intrusions on the traction battery of the motor vehicle. In particular, the change in the stress may be dependent on the deformation of the sensor wire, whereby the warning signal may be provided depending on the change in the stress. This embodiment has the advantage that damage to the traction battery and / or deformation of the sensor wire is only detected as such from a certain threshold, and lighter impacts, which do not lead to damage, can be avoided as false detection.One embodiment provides that the planar textile material with the sensor wire is arranged on a surface of the underbody element in the direction of the motor vehicle when the underbody element is installed as intended. In particular, the planar textile material can be bonded to the surface of the underbody element. For adhering the textile material to the surface of the underbody element, the textile material or semi-finished textile product can be injected beforehand with resin and thus applied to the surface as a thin plate. This results in a preferred form of attachment of the sensor device to the underbody element.A further embodiment provides that the underbody element has a foam insert as a flexurally rigid intermediate layer between at least two covering layers, wherein the planar textile material with the sensor wire is arranged between the foam insert and one of the two covering layers. In other words, another construction of the underbody element can provide for the textile material to be arranged between one of two covering layers and an intermediate layer which is designed as a foam insert. The textile material or textile semi-finished product can thus be integrated directly into the production process of the underbody element. The cover layers can preferably be formed from a glass fibre fabric, whereby an additional protective effect can be provided. By this embodiment, a further preferred form of attachment of the sensor device into the underbody element can be provided.In a further embodiment, it is provided that the underbody element has a foam insert as a flexurally rigid intermediate layer between at least two covering layers, wherein the planar textile material is integrated with the sensor wire in the foam insert. In other words, the underbody element can be configured in a similar manner to the aforementioned embodiment, that is to say with two outer layers which enclose a foam insert therebetween, wherein the textile material can be foamed into the foam insert by means of the sensor wire. For example, during a production process, the textile material can be foamed in such a way that it is integrated into the flexurally rigid intermediate layer. By this embodiment, a further preferred form of attachment of the sensor device into the underbody element can be provided.In the aforementioned embodiment, it is preferably provided that a respective end of the sensor wire is connected to a plug unit integrated into the foam insert, wherein the plug unit can be coupled to an evaluation unit of the sensor device via an exposed opening through at least one of the cover layers and the intermediate layer by means of a plug. In other words, if the textile material is integrated with the sensor wire in the foam insert, a plug unit can additionally be provided in the foam insert, which plug unit can also be foamed together with the textile material, for example, in a production process. The sensor wire in the textile material can preferably be connected to this plug unit, for example directly or via a metal lamina, which in particular provides an improved manufacturing tolerance. The plug unit can then be subsequently released after a production process by a predetermined positioning, for example by drilling, in order to gain access to the plug unit. Subsequently, a plug can be used to couple the plug unit and thus the sensor wire to an evaluation unit of the sensor device. As a result, a cost-effective, simple and reproducible contacting of the respective ends of the sensor wire can be provided in order to pick up signals of the voltage and consequently detect a deformation of the underbody element.A further aspect of the invention relates to a motor vehicle having an underbody element according to one of the preceding embodiments. 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. The motor vehicle may preferably be designed as an electrically operated motor vehicle having at least one traction battery.In one embodiment of the motor vehicle, it is provided that the motor vehicle has a traction battery and the underbody element comprises a plurality of chambers for arranging battery cells of the traction battery, wherein the textile material with the sensor wire is arranged in a planar manner in the regions of the chambers on or in the underbody element. In other words, the underbody element may have recesses in which battery cells of the traction battery may be arranged. The textile material can be arranged with the sensor wire into these chambers, which preferably represent planar regions in the underbody element. This results in sensor surfaces at the level of the battery cells, wherein each of the chambers can thus have its own sensor wire, whereby it can be determined in an improved manner which chamber has been deformed during a deformation. This embodiment provides the advantage that deformation and thus damage to one of the battery cells can be localized in an improved manner.According to the invention, a method for detecting intrusion of a traction battery of a motor vehicle is also provided, having an underbody element according to one of the preceding embodiments. The method provides that a voltage applied to the sensor wire is measured by a sensor device of the underbody element, which has at least one electrically conductive sensor wire that is integrated into a planar textile material, and a deformation of the sensor wire and thus an intrusion of the traction battery is determined as a function of a measured change in the voltage. This results in the same advantages and possible variations as in the underbody element and / or as in the motor vehicle with the underbody element.The invention also includes the control device for the motor vehicle. The control device can have a data processing device or a processor device which is configured to carry out an embodiment of the method according to the invention. For this purpose, the processor device can 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). Furthermore, the processor device can have program code which 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 invention also includes developments of the method according to the invention, which have features as have already been described in connection with the developments of the underbody element according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.The invention also includes the combinations of the features of the described embodiments. The invention therefore also comprises implementations which each have a combination of the features of a plurality of the described embodiments, provided that the embodiments have not been described as mutually exclusive.Exemplary embodiments of the invention are described below. The following shows: FIG. 1 shows a schematically illustrated motor vehicle having an underbody element according to an exemplary embodiment; FIG. 2 shows a schematically illustrated underbody element having a sensor device according to an exemplary embodiment; FIG. 3 shows a schematically illustrated application location of a textile material with a sensor wire, according to a first exemplary embodiment; FIG. 4 shows a schematically illustrated application location of a textile material with a sensor wire, according to a second exemplary embodiment; FIG. 5 shows a schematically illustrated application location of a textile material with a sensor wire, according to a third exemplary embodiment; FIG. 6 shows a schematically illustrated underbody element with an integrated sensor wire and an integrated plug unit.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 are to be considered independently of one another and that also develop the invention independently of one another. Therefore, the disclosure is intended to include combinations of the features of the embodiments other than those illustrated. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.In the figures, identical reference numerals designate functionally identical elements.FIG. 1 shows a schematic motor vehicle 1 having an underbody element 2 according to an exemplary embodiment. The motor vehicle 1 can be, for example, a passenger car that is operated electrically. For the energy supply, the motor vehicle 1 can comprise a traction battery 3 or traction battery, wherein the traction battery 3 can have a plurality of battery cells 4.In order to protect the traction battery 3 and the respective battery cells 4 from impacts from below the motor vehicle 1, the underbody element 2, which can be designed as underrun protection, can be arranged below the attachment location of the traction battery 3. The underbody element 2 can preferably be designed to protect the traction battery 3 from mechanical influences. Nevertheless, it may occur that, due to a strong impact from below the motor vehicle 1, for example when a pylon crossing is placed on top, intrusion of the traction battery 3 occurs. In order to ascertain this and to warn a driver of the motor vehicle 1 of damage to the traction battery 3, it may therefore be provided to provide a sensing concept for the traction battery 3.FIG. 2 schematically illustrates the underbody element 2 of the motor vehicle 1 in a plan view from the direction of the traction battery 3, wherein the traction battery 3 is not illustrated in this figure. The underbody element 2 can have a plurality of chambers 5, which are designed as planar regions, it being possible for the battery cells 4 of the traction battery 3 to be arranged in the chambers 5. In order to be able to detect impacts on the traction battery 3 and the respective battery cells 4, a sensor device 6 can be provided, which is arranged in a planar manner in each of the chambers 5, for example. In this figure, only a section of the sensor device 6 is shown, wherein the sensor device 6 can preferably be arranged on an entire surface of the chambers 5. The sensor device 6 can be designed to ascertain a deformation of the underbody element 2 and thus an intrusion onto the traction battery 3. The arrangement of the sensor device 6 in the respective chamber has the advantage that a detection of a deformation of the respective chamber 5 is made possible and thus a localization at which battery cell 4 damage has occurred.The sensor device 6 can have a planar textile material 7, into which a sensor wire 8 is integrated. The textile material 7, which can also be referred to as a planar textile semi-finished product, can facilitate an attachment of the sensor wire 8 in the underbody element 2, in particular in the chambers 5. The sensor wire 8 can be formed, for example, from a carbon fiber, which can be incorporated into the textile material 7 particularly easily and has suitable breakage and expansion properties. Furthermore, the sensor wire 8 is preferably incorporated in meandering fashion into the textile material 7, so that a good compromise can be provided between saving material and covering a surface for detection.For detecting a deformation, it can be provided that a current, in particular with a predefined voltage, is measured by the sensor device 6 through the sensor wire 8, wherein a deformation of the sensor wire 8 can be determined as a function of a change in the voltage. For this purpose, the sensor wire 8 can be designed to change an electrical resistance upon deformation, for example by changing a length and / or a diameter of the sensor wire upon deformation, which leads to a measurable change in resistance. If the sensor wire 8 is bent too strongly and beyond a defined deflection, it can be provided, for example, that a measured change in the stress lies above a predefined stress threshold value and a driver of the motor vehicle 1 can then receive a warning signal which is generated by the sensor device 6 in the event of the tension threshold value rising. A deformation of the underbody element 2 and consequently an intrusion onto the traction battery 3 or one of the battery cells 4 can thus be established in a simple manner.FIGS. 3 to 5 show preferred application sites for the sensor wire integrated in the textile material. In FIG. 3, a first exemplary embodiment is shown, in which the textile material with the sensor wire is arranged on a surface of the underbody element 2, wherein the surface is arranged in the direction of the motor vehicle. This means that on the inner side of the underbody element 2 in the direction of the traction battery 3, the semi-finished textile product (textile material 7) with the sensor wire 8 can be applied, for example adhesively bonded, subsequently to the inner side of the finished underbody element 2. For this purpose, the textile material 7 can be injected with resin, for example, in an upstream production step, in order to produce a thin plate therefrom, which can be adhered to the surface of the underbody element 2. The underbody element 2 itself can be formed with a plurality of layers, in particular with two covering layers 9 and a foam insert 10 as a flexurally rigid intermediate layer between the two covering layers 9.FIG. 4 shows a second exemplary application location for the textile material 7 with the sensor wire 8 in the underbody element 2. In this exemplary embodiment, the textile material 7 with the sensor wire 8 can be integrated directly into the underbody element 2, for example, by the textile material 7 being inserted between the foam insert 10 and one of the covering layers 9, for example, in a wet process. The textile material 7 can preferably be inserted between the foam insert 10 and the upper cover layer 9. The cover layer 9 can be present, for example, as a glass layer or glass fiber core / glass fiber fabric and provide stability of the underbody element 2.FIG. 5 shows a third exemplary application location for the textile material 7 with the sensor wire 8. In this exemplary embodiment, the textile material 7 can be directly foamed into a prefabricated foam insert 10 of the underbody element 2. That is, the planar textile material 7 is located in the foam insert 10, which is surrounded by the two cover layers 9.FIG. 6 shows an underbody element 2 with a plug integration for the third exemplary application location, in which the textile material 7 is integrated with the sensor wire 8 into the foam insert 10. In order to contact the sensor wire 8 and to pick up a signal, in particular in order to measure the voltage applied to the sensor wire 8, a plug unit 11 can also be foamed into the foam insert 10 in addition to the textile material 7 during a production process. Preferably, the sensor wire 8 can be connected to the plug unit 11, either directly or via a metal lamina 12, wherein a manufacturing process can be facilitated by the metal lamina 12, in particular due to an easier connection of the metal lamina 12 to the sensor wire 8.In order to reach the plug unit 11 from the outside, an opening through at least one of the cover layers 9 and the foam insert 10 as far as the plug unit 11 can be exposed in the production process, via which opening the plug unit 11 can be coupled by means of a plug 13 to an evaluation unit 14 of the sensor device 6. In other words, access to the plug unit 11 can be subsequently enabled by an exact positioning of the plug unit 11, for example by subsequently drilling a hole through the cover layer 9. A further plug unit, which is not shown here, can connect another end of the sensor wire 8 to a further plug which leads to the evaluation unit 14. Thus, a cost-effective, simple and reproducible contacting of the wire ends can be provided in order to be able to pick off signals.Overall, the examples show how a sensing concept for a traction battery 3 can be provided by the invention via a resistance sensing in the underbody element 2 in that a detection of a deformation of the underbody element 2 allows conclusions to be drawn about an intrusion of battery cells 4.

Claims

Underbody element (2) for a traction battery (3) of a motor vehicle (1), comprising at least one sensor device (6), characterized in that the sensor device (6) has at least one electrically conductive sensor wire (8) which is integrated into a planar textile material (7), wherein the sensor device (6) is designed to measure a voltage applied to the sensor wire (8) and to determine a deformation of the sensor wire (8) as a function of a measured change in the voltage.Underbody element (2) according to Claim 1, wherein the sensor wire (8) is integrated in a meandering manner in the planar textile material (7).Underbody element (2) according to one of the preceding claims, wherein the sensor wire (8) is formed from a carbon fibre or a metal-coated plastic filament.Underbody element (2) according to one of the preceding claims, wherein the sensor wire (8) is designed to change an electrical resistance in the event of deformation.Underbody element (2) according to one of the preceding claims, wherein the sensor device (6) is designed to generate a warning signal if the measured change in the voltage is above a predefined voltage threshold value.Underbody element (2) according to one of the preceding claims, wherein the planar textile material (7) with the sensor wire (8) is arranged on a surface of the underbody element (2) in the direction of the motor vehicle (1) when the underbody element (2) is installed as intended.Underbody element (2) according to one of Claims 1 to 5, wherein the underbody element (2) has a foam insert (10) as a flexurally rigid intermediate layer between at least two covering layers (9), wherein the planar textile material (7) is arranged with the sensor wire (8) between the foam insert (10) and one of the two covering layers (9).Underbody element (2) according to one of Claims 1 to 5, wherein the underbody element (2) has a foam insert (10) as a flexurally rigid intermediate layer between at least two covering layers (9), wherein the planar textile material (7) is integrated with the sensor wire (8) in the foam insert (10).Underbody element (2) according to Claim 8, wherein a respective end of the sensor wire (8) is connected to a plug unit (11) integrated into the foam insert (10), wherein the plug unit (11) can be coupled via a released opening through at least one of the covering layers (9) and the intermediate layer (10) by means of a plug (13) to an evaluation unit (14) of the sensor device (6).Motor vehicle (1) having an underbody element (2) according to one of the preceding claims.Motor vehicle (1) according to Claim 10, wherein the motor vehicle (1) has a traction battery (3) and the underbody element (2) comprises a plurality of chambers (5) for arranging battery cells (4) of the traction battery (3), wherein the textile material (7) with the sensor wire (8) is arranged in a planar manner in the regions of the chambers (5) on or in the underbody element (2).Method for detecting an intrusion of a traction battery (3) of a motor vehicle (1), having an underbody element (2) according to one of Claims 1 to 9, wherein a voltage applied to the sensor wire (8) is measured by a sensor device (6) of the underbody element (2), which has at least one electrically conductive sensor wire (8) integrated into a planar textile material (7), and a deformation of the sensor wire (8) and thus an intrusion of the traction battery (3) is detected as a function of a measured change in the voltage.

Images