Detection device for distinguishing between mechanical contact and accumulation of conductive fluid in high-voltage accumulators

Abstract

The invention relates to a detection device (24) for detecting mechanical deformations of a high-voltage energy accumulator (20) of a motor vehicle (10), comprising: a sensor element (30) for detecting electrical measured values, the sensor element (30) being of approximately flat design and being applied at least partially to a first component of the high-voltage energy accumulator (20); and an evaluation device (40) for analyzing the electrical measured values between the sensor element (30) and a second component of the high-voltage energy accumulator (20) and outputting a corresponding warning message based on the electrical measured values, at least one region of the surface of the second component being electrically conductive.

Description

Technical Field

[0001] The invention relates to a detection device for distinguishing between mechanical contact and accumulation of conductive fluid in a high-voltage energy accumulator, a high-voltage energy accumulator having such a detection device, and a motor vehicle having a corresponding high-voltage energy accumulator. Background Art

[0002] Current electric or hybrid vehicles are unable to detect damage or deformation of the high-voltage energy storage device or its housing that does not lead to an immediate safety-critical state or even failure of the system including the high-voltage energy storage device. One possible cause of such deformation is, for example, interference by foreign objects when the high-voltage energy storage device is installed in the vehicle floor.

[0003] According to the prior art, the risk of safety-critical damage to the high-pressure accumulator is addressed by designing the high-pressure accumulator and its housing to be mechanically robust and installing it in a suitable location, i.e., with sufficient floor clearance. Minor damage to the high-pressure accumulator or its housing (which could later cause damage) can only be detected through visual inspection. No systematic inspection is performed, and no visual inspection is even required.

[0004] The robustness of mechanical design currently required to manage risks in the event of damage results in excessively large mechanical dimensions for normal driving operation. The specific design implementation and its testing—for example, through deliberate crash tests with hard objects—cannot guarantee that safety-critical components will not be damaged during "normal" driving. This translates to high development costs and, due to the excessive dimensions, prevents the full utilization of potential reductions in vehicle weight and manufacturing costs. Furthermore, installing the high-voltage accumulator in vulnerable areas of the vehicle leads to significant restrictions on vehicle styling, functionality—especially range—and design. Furthermore, it is impossible to detect the degree to which any deformation of the high-voltage accumulator is critical for vehicle safety. Summary of the Invention

[0005] The present invention is based on the object of providing a cost-effective detection device for detecting deformations of a high-pressure accumulator housing in a motor vehicle. This detection device is capable of detecting deformations of the high-pressure accumulator housing with the greatest possible differentiation, thereby making the best possible use of the available space in the design and arrangement of the high-pressure accumulator. The contact detection device should not increase the installation space and weight of the high-pressure accumulator, or at least not significantly.

[0006] This object is achieved by a detection device according to the invention for detecting a deformation of a motor vehicle energy storage housing, a high-voltage energy storage device according to the invention, and an electric or hybrid vehicle according to the invention.

[0007] According to the present invention, a detection device for detecting mechanical deformation of a high-voltage energy accumulator of a motor vehicle includes a sensor element for detecting an electrical measured value, the sensor element being of substantially flat design and at least partially attached to a first component of the high-voltage energy accumulator; and an evaluation device for analyzing the electrical measured value between the sensor element and a second component of the high-voltage energy accumulator and for outputting a corresponding warning message based on the electrical measured value, at least one region of the surface of the second component being electrically conductive. The detection device includes an electrically insulating layer disposed between the component of the high-voltage energy accumulator and the sensor element, and / or the evaluation device distinguishes between a mechanical contact and an accumulation of conductive fluid in the high-voltage energy accumulator using the electrical measured value and its temporal curve.

[0008] For this purpose, the evaluation device is designed in such a way that it issues a warning message if the measured electrical resistance rises from an initial value corresponding to the undeformed state of the housing to a certain value.

[0009] The warning message is a warning corresponding to deformation of the housing caused by mechanical contact of the sensor element with a component of the high-voltage accumulator to be inspected.

[0010] The warning message can be, for example, acoustically via a loudspeaker and / or visually on a monitor and / or as a corresponding data entry in a diagnostic device or control unit of the high-voltage energy storage device or the motor vehicle. The dielectric elastomer sensor can be arranged in an electrically insulating layer or form such a layer.

[0011] The present invention therefore has the advantage that even when the housing of a high-voltage accumulator in a motor vehicle is deformed, possible damage to a component can be detected. Based on this detection, appropriate measures or functions can be implemented to warn the vehicle user, thereby increasing the safety level of the vehicle. The manufacturing costs incurred for implementing the sensor element and evaluation device according to the present invention and the additional expenses caused by the increased weight can be offset by the possible reduction in the mechanical design of the high-voltage accumulator and its housing according to the present invention. Furthermore, the increased diagnostic reliability allows for the use of additional installation space in the vehicle for installing at least part of the high-voltage accumulator there. This offers advantages in vehicle design and can also be used to increase the vehicle's range. Because the sensor element has an electrically conductive layer and is applied to a component of the high-voltage accumulator, the detection device is very cost-effective to implement, and its design or the application of the sensor element is very simple. This also reduces manufacturing costs.

[0012] According to an advantageous embodiment of the present invention, the sensor element comprises a metal foil or a conductive coating. Both metal foils and conductive coatings are cost-effective options for implementing the detection device. Furthermore, metal foils can be applied very easily to components of the high-voltage energy storage device, and conductive coatings also offer advantages such as stability and ease of production.

[0013] According to an advantageous development of the invention, the first component and / or the second component is designed as a housing of the high-voltage energy accumulator, a battery module of the high-voltage energy accumulator, a cooler of the high-voltage energy accumulator, an electronic component of the high-voltage energy accumulator, a contact protection device of the high-voltage energy accumulator, or a vibration protection device of the high-voltage energy accumulator.

[0014] This allows targeted monitoring of safety-critical components, such as battery modules, housings, or electrical or electronic components provided therefor, for example, to determine whether they are damaged. This has the advantage that deformation of various components of the high-voltage energy storage device can be detected in a targeted manner when an object strikes it.

[0015] According to an advantageous embodiment of the invention, the sensor element can be mounted on the inside of the housing, for example on the housing bottom. This has the advantage that any deformation of the housing when an object strikes from below is detected by mechanical contact between the housing and the internal components of the high-pressure accumulator.

[0016] According to an advantageous embodiment of the invention, the second component has at least one electrically conductive sensor surface.

[0017] According to an advantageous embodiment of the invention, the touch protection device of the high-voltage energy store and / or the vibration protection device of the high-voltage energy store has at least one chamber which serves as a holder for the electrically conductive sensor surface.

[0018] According to an advantageous embodiment of the invention, the detection device comprises an electrically insulating layer which is arranged between a component of the high-voltage energy store and the sensor element.

[0019] According to an advantageous embodiment of the invention, the sensor element is provided with at least one measuring contact for acquiring and outputting an electrical measured value detected by the sensor element.

[0020] According to an advantageous embodiment of the invention, the evaluation device comprises a voltage measuring device, a resistance measuring device or a capacitance measuring device for measuring an electrical measured value present between the sensor element and a second measuring contact on the second component.

[0021] According to an advantageous embodiment of the invention, the evaluation device detects the time curve of the electrical measured value.

[0022] According to an advantageous embodiment of the invention, the evaluation device can differentiate between a mechanical contact and an accumulation of conductive fluid in the high-voltage energy store by means of the electrical measured values and their time curve.

[0023] According to an advantageous embodiment of the invention, the evaluation device determines that a mechanical contact has occurred if the duration of exceeding or falling below a predefined threshold value is less than 500 ms, in particular less than 100 ms.

[0024] According to an advantageous embodiment of the invention, the evaluation device determines that an accumulation of conductive fluid has occurred in the high-voltage accumulator if the duration of exceeding or falling below a predefined threshold value exceeds 500 ms, in particular exceeds 1000 ms.

[0025] In addition to evaluating the aforementioned measured values, the duration of contact between the housing of the high-voltage accumulator and a component can also be considered. For example, a contact time of 10 to 50 ms can be considered moderate deformation and therefore moderate damage, while longer contact times (50 to 100 ms) can be considered severe damage.

[0026] The sensor element's evaluation device should be designed to detect the duration for which the electrical measured value exceeds a threshold value. This allows a distinction to be made between the two damage modes of mechanical deformation and detection of conductive fluid accumulation. Due to the elastic deformation component of mechanical deformation, the electrical measured value exceeds the threshold value only for a short duration in mild or moderate events. This duration is less than 500 ms, typically less than 100 ms. Therefore, a first warning message of medium urgency can be sent to the driver, for example, advising immediate visit to a workshop.

[0027] In the event of a large accumulation of conductive liquid, this duration is in the range of more than 500 ms, typically more than 1 second. The risk of internal battery short circuits due to severe deformation or the risk of hydrogen formation and the subsequent ignition or explosion of hydrogen-oxygen explosive gas due to the accumulation of conductive liquid creates a high safety risk. This time difference allows the driver to receive a second, highly urgent warning message, such as a request to stop the vehicle immediately and leave.

[0028] According to the present invention, the insulating layer protrudes beyond the electrically conductive sensor surface and thus ensures that air and creepage distances to the base component on which the sensor is mounted are maintained. By extending or shortening this protrusion, the resistance between the sensor surface and the base component can be adjusted so that no errors occur in the dry state, while a measurable current flows in the wet state. This also makes it possible to detect water accumulation in high-voltage accumulators.

[0029] Furthermore, the frequency with which electrical measurements exceed a threshold over a certain period of time can be used as a criterion for distinguishing between mechanical deformation and conductive liquid accumulation (which can be triggered multiple times during liquid sloshing). When multiple sensor elements are used, the location of the threshold exceedance can be determined. If the threshold is exceeded consecutively at different sensor elements, conductive liquid sloshing can also be inferred.

[0030] A particularly simple and reliable realization possibility for the evaluation device used according to the invention is provided if the evaluation device comprises a resistance measuring device for measuring the resistance present between the first measuring contact and the second measuring contact.

[0031] Furthermore, the above object is achieved by a high-pressure energy accumulator for a motor vehicle, comprising a detection device according to the above description. Furthermore, the above object is achieved by a motor vehicle equipped with such a high-pressure energy accumulator. Accordingly, the same or similar advantages as those described above result, and to avoid repeated reference to the above description relating to the detection device according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Some advantageous embodiments of the present invention are exemplarily described below with reference to the accompanying drawings. The accompanying drawings are as follows:

[0033] Figure 1 A schematic diagram showing a detection device according to the present invention, which is arranged by way of example on a high-pressure energy storage device installed in a motor vehicle;

[0034] Figure 2 A schematic diagram shows a first embodiment of a high-pressure accumulator according to the invention, in which a sensor element is installed;

[0035] Figure 3 A schematic diagram shows a second specific embodiment of a high-voltage energy store according to the invention having a battery module and a sensor element. DETAILED DESCRIPTION

[0036] Figure 1A motor vehicle 10 according to the present invention is shown, in which a high-voltage energy storage device 20 is installed, which is provided with a detection device 24 according to the present invention. The high-voltage energy storage device 20 is located in a housing 22 with a battery module 23. In addition to the detection device 24, a sensor element 30 with measuring contacts 31 and an evaluation device 40 are located in the housing 22. In this example, the sensor element 30, which is designed as a membrane made of a dielectric elastomer sensor, is located on the bottom of the housing 22, but it could also be located on the battery module 23. The second measuring contact 32 could be located on an electrically conductive part of the high-voltage energy storage device 20, such as the inner wall of the battery module 23 or the housing 22. An electrical signal can be detected as an electrical measured value (voltage or resistance) of the sensor element 30 via the first and second measuring contacts 31, 32, and supplied to the evaluation device 40. The voltage measuring device of the evaluation device 40 measures the voltage between the two measuring contacts 31 and 32. The evaluation device 40 is designed so that it can analyze the corresponding output measured values and thereby detect mechanical contact between the housing and another component of the high-voltage energy storage device. Examples of specific embodiments of the evaluation device 40 and the sensor element 30 will be described later. Furthermore, the evaluation device 40 is designed so that if it detects a corresponding mechanical contact, it can output a warning signal or a warning message. This warning message can be conveyed to the driver of the motor vehicle 10, for example, optically via a corresponding display 54 and / or acoustically via a suitable loudspeaker 56. Furthermore, the warning message can be fed to a controller 58 for the high-pressure energy accumulator 20 or the entire motor vehicle 10, where it can be stored and used for further analysis or, for example, for repair instructions at a workshop or service center.

[0037] Figure 2 The first embodiment of the high-voltage energy storage device 20 shows a situation in which a foreign object 9 presses the bottom of the housing 22 upwards until the housing 22 presses onto the battery module 23 located above it or even deforms the battery module. In this second embodiment, the sensor element 30 is only arranged on the bottom of the housing 22. The housing of the battery module can be made of metal. In this case, the surface of the battery module 23 is electrically conductive. Therefore, Figure 2 In the situation shown, sensor element 30 and therefore the electrical signal emitted thereby are more strongly influenced by the mechanical contact.

[0038] If the material of the high-voltage energy storage component itself is not electrically conductive, a conductive layer can be applied to at least one region of the component surface and second measuring contact 32 must be arranged on this region so that first measuring contact 31 and second measuring contact 32 can be electrically connected to one another when sensor element 30 contacts this conductive region.

[0039] When it happens Figure 2During the deformation shown, the two measuring contacts 31 and 32 are electrically connected, and a measuring current flows between them. Consequently, the voltage measured by the voltage measuring device between the two measuring contacts 31 and 32 changes. Based on this fact, the evaluation device 40 infers that a mechanical deformation has occurred and issues a corresponding warning message to the driver of the motor vehicle 10. Such a warning message could, for example, include a request to immediately visit a workshop or even shut down the engine, as damage that could affect the function of the high-voltage energy accumulator may have occurred.

[0040] The voltage and / or resistance value is continuously detected between the two measuring contacts 31 and 32. It goes without saying that the corresponding measurement can also be performed, for example, periodically, ie discontinuously.

[0041] As described above, the evaluation device 40 is also installed in the housing 22 of the high-pressure accumulator 20 as part of the detection device 24. Of course, the evaluation device 40 can also be arranged outside the housing 22. It is also conceivable that the sensor element 30 can also be fixed on the outside of the housing 22.

[0042] In addition to evaluating the aforementioned measured values, the duration of contact between the high-voltage accumulator housing and the component can also be considered. For example, a contact time of 10 to 50 ms can be considered moderate deformation and therefore moderate damage, while a longer contact time (50 to 100 ms) can be considered severe damage.

[0043] The sensor element's evaluation device should be designed to detect the duration for which the electrical measured value exceeds a threshold value. This allows a distinction to be made between two damage modes: "detection of mechanical deformation" and "detection of conductive fluid accumulation." Due to the proportion of elastic deformation in mechanical deformation, the electrical measured value exceeds the threshold value only for a short duration in mild or moderate events. This duration is less than 500 ms, typically less than 100 ms. Therefore, a first warning message with a medium level of urgency can be sent to the driver, for example, advising immediate visit to a workshop.

[0044] In the event of a large accumulation of conductive liquid, this duration is in the range of more than 500 ms, typically more than 1 second. The risk of internal battery short circuits due to severe deformation or the risk of hydrogen formation and the subsequent ignition or explosion of hydrogen-oxygen explosive gas due to the accumulation of conductive liquid creates a highly safety-critical situation. This time difference allows for a second, highly urgent warning message to be issued to the driver, such as a request to stop the vehicle immediately and leave.

[0045] Figure 3A second embodiment of a high-voltage energy storage device 20 is shown, in which an evaluation device 40 and a plurality of battery modules 36 are arranged. A sensor element 30 comprising a metal foil or a conductive coating is a sensor surface applied to the battery module. The sensor element 30 can also be applied to another component of the high-voltage energy storage device 20, such as the inner side of the housing 22.

[0046] The sensor element 30 can wrap around the battery module and / or flatly cover the entire housing bottom of the high-voltage energy storage device 20. Alternatively, the sensor element 30 or corresponding sensor elements 30 can be locally arranged, for example, on critical component areas, such as the inside of the housing 22, or depending on critical impact areas. If the sensor element is applied only to critical subcomponents within the high-voltage energy storage device 20 (such as the battery module) (and therefore not to the bottom of the housing 22), only severe deformations can be detected through corresponding contact.

[0047] If a component surface, such as a battery module surface, is itself electrically conductive and electrically grounded, an electrically insulating layer (such as a non-conductive film or coating) must first be applied to the battery module in order to separate the conductive layer from the ground.

[0048] A low-cost application method, for example, is prefabricated aluminum foil with an insulating adhesive layer. If the adhesive layer's insulating effect is insufficient, a self-adhesive film such as Kapton or PET can be applied first, followed by the aluminum tape. Another alternative is to coat with an electrically insulating layer, such as KTL, and then apply a conductive lacquer.

[0049] To implement a galvanically isolated measurement circuit, it may be necessary to combine multiple sensor elements or sensor surfaces at different potentials. The sensor membrane (sensor element 30) can also be applied to the battery module. Alternatively, the sensor membrane 30 can be applied to other surfaces within the high-voltage accumulator 20, such as the inside of the housing bottom surface and / or to protected subcomponents, such as a cooler.

[0050] Alternatively, the first component and / or the second component can include a battery module or an electronic component of the high-voltage energy accumulator or a touch protection device of the high-voltage energy accumulator or a vibration protection device of the high-voltage energy accumulator, wherein the touch protection device of the high-voltage energy accumulator and / or the vibration protection device of the high-voltage energy accumulator has at least one cavity, which serves as a holder for the electrically conductive sensor surface.

[0051] The second component has a conductive surface, at least a portion of its surface or has a conductive sensor surface.

[0052] The aforementioned sensor surface and its installation can save manufacturing costs and reduce the weight or installation space of the high-voltage accumulator 20. At the same time, the robustness of the detection device 24 with respect to loads exceeding the design limit can be increased.

[0053] If one or more sensor surfaces are used to cover multiple critical areas, it is advantageous to conduct the measurement signal sequentially through all sensors and tap off at an output separate from the input in order to control the electrical connection of the sensors (interlocking principle). For example, the sensor surfaces can be connected in series, with a resistor connected to a voltage source at the input and a sensor line for measuring the voltage at the output. This ensures that all sensor surfaces are connected, and that all sensor surfaces can be identified by evaluating a single sensor line.

[0054] Furthermore, water accumulation in the high-pressure accumulator 20 (due to housing damage or a radiator rupture) can be detected by the detection device 24 .

[0055] According to the present invention, the insulating layer 34 protrudes from the conductive sensor surface 30 ( Figure 3 ) and thus ensures that air and creepage distances to the base component (such as battery module 36) on which the sensor is mounted are maintained. By extending or shortening this protrusion, the resistance between sensor surface 30 and the base component can be adjusted so that no current flows in the dry state, while a measurable current flows in the wet state. This utilizes the conductive properties of the coolant (500 μS-4000 μS). To ensure robustness against ambient humidity, the measuring distance is adjusted so that, for example, a coolant leak of >100 ml can be detected.

[0056] A similar mechanism can be achieved by microstructuring the membrane surface. This allows water to be detected on a larger surface and thus earlier or more reliably.

[0057] Furthermore, the sensor system can also be designed as an independent subsystem within a corresponding component of the high-pressure energy store, for example as a multi-layer housing bottom.

[0058] It should be noted that the features of the invention described with reference to individual embodiments or variants, such as the type and design of individual sensor elements or evaluation devices and their spatial arrangement, may also be present in other embodiments, unless otherwise indicated or prohibited for technical reasons. Furthermore, not all features of the features described in combination of various embodiments are necessarily implemented in one embodiment in question.

Claims

1. A detection device (24) for distinguishing between mechanical contact of a high-voltage energy accumulator (20) of a motor vehicle (10) and accumulation of a conductive liquid in the high-voltage energy accumulator (20), the detection device comprising: a sensor element (30) for detecting an electrical measured value, the sensor element (30) being of approximately flat design and being applied at least partially to a first component of the high-voltage energy accumulator (20), wherein the sensor element (30) is provided with at least one first measuring contact (31) for acquiring and outputting the electrical measured value detected by the sensor element (30); and An evaluation device (40) for analyzing an electrical measurement value between a first measuring contact (31) on the sensor element (30) and a second measuring contact (32) on a second component of the high-voltage energy accumulator (20) and for outputting a corresponding warning message based on the electrical measurement value, at least one area of the surface of the second component being electrically conductive, wherein the evaluation device (40) comprises a voltage measuring device and / or a resistance measuring device for measuring a voltage and / or a resistance between the first measuring contact (31) on the sensor element (30) and the second measuring contact (32) on the second component as the electrical measurement value, The detection device (24) comprises an electrically insulating layer (34) which is arranged between a first component of the high-voltage energy accumulator (20) and a sensor element (30), wherein the electrically insulating layer is applied to the first component of the high-voltage energy accumulator as a non-conductive film or a non-conductive coating and projects beyond the surface of the sensor element, wherein the electrical resistance between the first component of the high-voltage energy accumulator and the surface of the sensor element can be adjusted by extending or shortening the projection of the electrically insulating layer, so that in a dry state no current flows, while in a wet state a measurable current flows and thus an accumulation of conductive liquid in the high-voltage energy accumulator can be detected, and The evaluation device (40) distinguishes between mechanical contact and accumulation of conductive liquid in the high-voltage energy storage device (20) by means of electrical measurement values and a time curve of the electrical measurement values, wherein the evaluation device distinguishes between mechanical contact and accumulation of conductive liquid in the high-voltage energy storage device based on the duration of time during which the electrical measurement values exceed a threshold value and / or the frequency of the electrical measurement values exceeding a threshold value within a certain time period.

2. The detection device (24) according to claim 1, wherein The sensor element (30) comprises a metal foil.

3. The detection device (24) according to claim 1 or 2, wherein: The first component and / or the second component is configured as a housing (22) of a high-voltage energy accumulator (20), a battery module (36) of a high-voltage energy accumulator (20), a cooler of a high-voltage energy accumulator (20), an electronic component, a contact protection device of a high-voltage energy accumulator (20), or a vibration protection device of a high-voltage energy accumulator (20).

4. The detection device (24) according to claim 3, wherein: The sensor element (30) is mounted on the inner side of the housing (22).

5. The detection device (24) according to claim 3, wherein: The second member has at least one electrically conductive sensor surface.

6. The detection device (24) according to claim 5, wherein: The contact protection device of the high-voltage energy store (20) and / or the vibration protection device of the high-voltage energy store (20) has at least one chamber which serves as a holder for the electrically conductive sensor surface.

7. The detection device (24) according to claim 1 or 2, wherein: The evaluation device (40) detects the time curve of the electrical measured value.

8. The detection device (24) according to claim 1 or 2, wherein: If the duration of exceeding or falling below a predefined threshold value is less than 500 ms, the evaluation device (40) determines that a mechanical contact has occurred.

9. The detection device (24) according to claim 8, wherein If the duration of exceeding or falling below a predefined threshold value is less than 100 ms, the evaluation device (40) determines that a mechanical contact has occurred.

10. The detection device (24) according to claim 1 or 2, wherein: If the duration of exceeding or falling below a predefined threshold value exceeds 500 ms, the evaluation device (40) determines that an accumulation of electrically conductive liquid has occurred in the high-voltage accumulator (20).

11. The detection device (24) according to claim 10, wherein: If the duration of exceeding or falling below a predefined threshold value exceeds 1000 ms, the evaluation device (40) determines that an accumulation of electrically conductive liquid has occurred in the high-voltage accumulator (20).

12. The detection device (24) according to claim 1 or 2, wherein: The sensor element (30) has a conductive coating.

13. A high-voltage energy accumulator (20) for a motor vehicle (10), comprising a detection device (24) according to any one of claims 1 to 12.

14. Electric vehicle or hybrid vehicle comprising a high-voltage energy storage device (20) according to claim 13.

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