Circuit arrangement for a steering wheel of a vehicle, method for operating a circuit arrangement, and steering wheel having a circuit arrangement

Abstract

The present invention relates to a circuit device (10) for a steering wheel (12) of a vehicle, a method (55) for operating the circuit device for the steering wheel (12) of a vehicle, and a steering wheel (12) for a vehicle having the circuit device (10). The steering wheel (12) has at least one conductive layer (16) and a frame structure (20). An intermediate layer capacitor (30) is formed between the conductive layer (16) and the frame structure (20), and an ambient capacitor (32) is formed between the frame structure (20) and a vehicle frame component (34). The intermediate layer capacitor (30) and the ambient capacitor (32) constitute a capacitive voltage divider for the conductive layer (16). The circuit device (10) also has a voltage source (24) that can be selectively coupled to the frame structure (20) via a frame lead (26). The frame lead (26) has a resistor (38). The circuit device (10) is designed to detect at least a first voltage value (V1) on the voltage source side of the resistance (38) of the skeleton lead (26) and a second voltage value (V2) on the skeleton side of the resistance (38) of the skeleton lead (26). The control device (22) of the circuit device (10) is designed to detect a faulty skeleton lead (26) based on the ambient capacitance (32) with at least the first and second voltage values ​​(V1, V2).

Description

Technical Field

[0001] The present invention relates to an electrical device for a vehicle steering wheel, a method for operating the electrical device for a vehicle steering wheel, and a steering wheel for a vehicle having the electrical device. Background Technology

[0002] In modern vehicle control systems, such as those performing autonomous or partially autonomous driving functions, it is important to monitor whether the vehicle user wishes to make manual control inputs, for example, by implementing a hand recognition function related to the steering wheel (so-called hands-on / off-hand detection (HOD), also known as a hand occupancy system). To ensure this detection mechanism, the steering wheel typically has multiple conductive layers, allowing hand recognition to be achieved through capacitance measurements, as the placement of the hand causes a change in the relative capacitance ratio.

[0003] Steering wheels with HOD functionality to date have incorporated multiple conductive layers, see, for example, WO2023 / 169827A1, arranged within the steering wheel body. However, this results in a complex steering wheel structure and relatively high manufacturing costs. It is worth considering that, to achieve the desired shape, the steering wheel also has a skeleton structure, which typically comprises metal and is therefore conductive, serving as a component during HOD functionality. Furthermore, the detection mechanism is also complex to reliably identify changes in capacitance ratio.

[0004] Furthermore, the steering wheel is continuously subjected to vibration and movement. For this reason, in addition to the HOD (Hardware Overhead) function, a reliable detection mechanism for potential damage to the basic switching circuitry must also be considered. For example, it is possible that the leads leading to the conductive layer or other conductive layers (such as the frame structure installed inside the steering wheel) are faulty. A reliable identification mechanism must be established for such faulty conditions.

[0005] Here, the identification of faulty leads becomes difficult due to changes in capacitance ratio caused by vibration, motion, and additionally by component deviations. Summary of the Invention

[0006] The objective of this invention is to eliminate or at least reduce the drawbacks of the prior art. In particular, it aims to provide a feasible method for cost-effectively manufacturing steering wheels, while simultaneously achieving reliable HOD (Hardware Overhead) functionality and fault identification.

[0007] This task is addressed by the subject matter of the independent claims. Advantageous design solutions are given in the dependent claims and the following description, each of which, on its own or in combination thereof, constitutes aspects of the invention. Some aspects relate to apparatus while others relate to method. However, these features and advantages can be transferred in corresponding manner.

[0008] According to one aspect, a circuit device for a vehicle steering wheel is provided. The steering wheel has at least one conductive layer and a frame structure. An intermediate layer capacitor is formed between the conductive layer and the frame structure, and an ambient capacitor is formed between the frame structure and a vehicle body frame component.

[0009] The intermediate layer capacitor and the ambient capacitor constitute a capacitive voltage divider for the conductive layer.

[0010] The circuit device also has a voltage source that can be selectively coupled to the skeleton structure via skeleton leads.

[0011] The skeleton leads have resistance.

[0012] The circuit device is designed to detect at least a first voltage value on the voltage source side of the resistor in the bobbin lead and a second voltage value on the bobbin side of the resistor in the bobbin lead.

[0013] The control device of the circuit is designed to detect faulty skeleton leads based on ambient capacitance using a first voltage value and a second voltage value.

[0014] This capacitive voltage divider provides an effective identification mechanism, taking into account the resistance of the bobbin leads, to detect faulty bobbin leads. It is important to consider that the voltage division will change due to the capacitive voltage divider. In particular, the intermediate layer capacitors are configured differently in cases of faulty and functional bobbin connections, allowing the determination of whether a bobbin connection is normal or faulty based on the measured voltage division. Advantageously, it is only necessary to detect voltage values ​​on the input and output sides, i.e., the voltage source side and the bobbin side of the resistor, and compare them with corresponding expected values. As a result, a simple, compact, yet efficient and reliable mechanism is provided to identify faulty (e.g., broken) bobbin leads.

[0015] Preferably, the frame structure forms a steering wheel frame. The frame structure is preferably made of a metallic material. For example, the frame structure may be made of aluminum alloy and / or magnesium alloy.

[0016] In some embodiments, the frame structure includes, for example, a steering wheel rim connected to the hub of the steering wheel via spokes. The steering wheel rim, spokes, and hub can together form the steering wheel frame.

[0017] Optionally, the conductive layer constitutes at least one conductive conductor segment. The conductive conductor segment can be constructed as a single wire, a wire mesh, or the like. Particularly preferably, the conductive conductor segment is integrated into the grip area of ​​the steering wheel assembly. For example, the conductive conductor segment has metallic wires.

[0018] Preferably, the conductive layer and the skeleton layer are arranged centrally and / or layered with each other in cross-section.

[0019] The intermediate layer capacitor is constructed as an intermediate layer capacitor between the conductive layer and the skeleton structure. The intermediate layer capacitance is typically (approximately) constant. For example, variations may exist between different steering wheels due to component deviations, but this is usually negligible. The intermediate layer capacitance can be based on: for example, a non-conductive material, such as in the form of foam, being disposed between the conductive layer and the skeleton structure, which is used to shape the steering wheel.

[0020] In contrast, environmental capacitance is formed between the skeleton structure and (ideally: infinitely far) vehicle frame components.

[0021] With this arrangement, the skeleton structure affects not only the intermediate layer capacitance but also the ambient capacitance. Therefore, the intermediate layer capacitance and the ambient capacitance constitute a capacitive voltage divider for the conductive layer. In this regard, the ambient capacitance can also be viewed as the capacitance formed between the conductive layer and the vehicle frame component in an alternative observation method. The detection mechanism based on the faulty skeleton lead is unaffected because, in the latter alternative observation method, the conductive layer affects both capacitances, namely the intermediate layer capacitance and the ambient capacitance. Therefore, a voltage divider is also formed with respect to the conductive layer in the aforementioned alternative observation method.

[0022] Here, the resistance of the skeleton lead is understood as a dedicated, separate resistor arranged within the skeleton lead. The resistance of the skeleton lead, in this sense, does not refer to the inherent conductor resistance of the skeleton lead itself. Rather, the resistance of the skeleton lead can be viewed as a separate, predetermined component specifically arranged within the skeleton lead to provide the described fault identification mechanism.

[0023] In some embodiments, the resistance of the skeleton leads can be between 100 Ohm ± 10% and 1 MOhm ± 10%, preferably between 200 Ohm ± 10% and 500 kOhm ± 10%, more preferably between 300 Ohm ± 10% and 100 kOhm ± 10%, more preferably between 500 Ohm ± 10% and 10 kOhm ± 10%, more preferably between 700 Ohm ± 10% and 5 kOhm ± 10%, more preferably between 800 Ohm ± 10% and 2 kOhm ± 10%, and more preferably, especially, between 1 kOhm ± 10%.

[0024] The control device may have corresponding components for detecting voltage values, such as at least one data processing device. These components may be at least partially digital or analog. Additionally, the control device is at least indirectly coupled to the resistance of the bobbin leads, particularly not only on the voltage source side but also on the bobbin side. This means that the control device can detect the voltage values ​​of the bobbin lead resistance on both the voltage source side and the bobbin side independently of each other.

[0025] According to one aspect, a method for operating an electrical device for a steering wheel of a vehicle is also provided. The steering wheel has at least one conductive layer and a frame structure. An intermediate layer capacitor is formed between the conductive layer and the frame structure, and an ambient capacitor is formed between the frame structure and a vehicle body frame component.

[0026] The intermediate layer capacitor and the ambient capacitor constitute a capacitive voltage divider for the conductive layer.

[0027] The circuit device also has a voltage source that can be selectively coupled to the skeleton structure via skeleton leads.

[0028] The skeleton leads have resistance.

[0029] The method includes at least the following steps:

[0030] - The first voltage value on the voltage source side for detecting the resistance of the skeleton leads.

[0031] - The second voltage value on the skeleton side is used to detect the resistance of the skeleton leads.

[0032] - Based on the ambient capacitance, at least based on the first voltage value and the second voltage value, the control device detects the faulty skeleton lead.

[0033] The advantages achieved by the circuit devices described above can also be achieved in a corresponding manner by the methods introduced here.

[0034] By selectively coupling the skeleton structure to a voltage source, different stages of power supply via the voltage source can be defined. This opens up the possibility of detecting a specific voltage value based on the coupling with the voltage source. Consequently, the detection of faulty skeleton leads is simplified.

[0035] Optionally, the ambient capacitance is variable. This can be caused by differences in component characteristics. However, it can also be caused by the motion and vibration experienced by the steering wheel. Additionally, external influences can also cause the ambient capacitance to be variable. In particular, due to the variability of the ambient capacitance, a robust identification mechanism for faulty skeleton leads is needed.

[0036] In some implementations, the skeleton leads can be selectively coupled to the vehicle ground. For example, a switching device can be provided and arranged such that an alternating conductance value is formed between the skeleton structure and the switching device. Through selective coupling, the skeleton leads can be connected to a defined potential at least in stages. If the skeleton leads are coupled to the vehicle ground, the ambient capacitance is zero in this case due to direct electrical coupling. This enables the skeleton leads to be forced into specific operating states and thus simplifies fault identification. Other operating states can be ignored. The alternating conductance value provides the feasibility of additional fault identification mechanisms. If the conductance remains constant despite the operation of the switching device, a fault condition exists.

[0037] Optionally, the circuit arrangement is additionally designed to detect a third voltage value for the at least one conductive layer. This can be considered, in particular, as an additional method step in the previously described method. For example, a control device or a component coupled to a control device can be used for this purpose. The control device is designed to additionally detect faulty skeleton leads based on variable ambient capacitance, taking into account the third voltage value. In particular, the ambient capacitance can be at least temporarily variable in this case. The third voltage value simplifies the determination of faulty skeleton leads.

[0038] In some implementations, a skeleton lead is detected as faulty if a second voltage value exceeds a first voltage threshold and a third voltage value does not exceed the second voltage threshold. The second voltage threshold is related to the first voltage threshold when considering a capacitive voltage divider. Here, a capacitive voltage divider consisting of an intermediate layer capacitor and an ambient capacitor can be used to determine a desired value that the second and third voltage values ​​must have, thereby determining the skeleton lead as fault-free. On the other hand, based on the capacitive voltage divider, a corresponding voltage threshold can be determined, which can be used to detect faulty skeleton leads. In other words, the voltage thresholds are in a specific relationship determined by the capacitive voltage divider.

[0039] Preferably, the corresponding tolerance range is considered when determining the voltage threshold.

[0040] For example, the detection of faulty skeleton leads can also be based on whether a corresponding condition regarding a voltage threshold is met / not met for multiple detection cycles within a predefined time interval. This avoids situations where a single measurement based on vibration might lead to the skeleton lead being directly detected as faulty.

[0041] Optionally, the control device is designed to place the skeleton lead in a first defined state at least in a first stage, in which the skeleton lead is decoupled from the voltage source and coupled to the vehicle ground.

[0042] Preferably, at the start of the method for operating the circuit device, all voltage lines, i.e., skeleton leads, are coupled to ground not only on the voltage source side of the resistor but also on the skeleton side of the resistor (and therefore also the skeleton structure) and the conductive layer. This ensures that at the start of the method, all capacitors of the circuit device are discharged and have a defined potential. This capacitor discharge process can also be part of a first stage.

[0043] Then, the control device is also designed to place the skeleton lead in a second defined state during the second stage, in which the skeleton lead is decoupled from the vehicle ground and coupled to the voltage source. This describes the start time point used for this method.

[0044] All subsequent voltage value measurements can then preferably be performed within a predetermined time interval t1. Here, the time interval t1 can be significantly smaller than the product of the resistance of the skeleton leads and the capacitance of the intermediate layer capacitor. Therefore, it can be ensured, based on the corresponding time interval, that the conditions for a steady state have not yet been reached.

[0045] Therefore, the circuit is designed to detect the second voltage value within a predetermined time interval after the start of the second phase. Selective coupling to the voltage source or vehicle ground is typically ensured by a switching device. A control device controls the switching state of the switching device. The switching process induces fluctuations in voltage amplitude within the circuit. By taking into account the predetermined time interval after the start of a specific phase (in this second phase), fluctuations caused by the switching process can be avoided from affecting the detection mechanism for faulty skeleton leads.

[0046] Additionally, the predetermined time interval enables configurations that take into account the definition of the circuit device. Since the value of the intermediate layer capacitor can be known in advance, the time interval can be selected, for example, such that the charge stored in the intermediate layer capacitor has not been fully built up (or depleted). In terms of the final effect, the time interval can be used to detect faulty skeleton leads based on measurements corresponding to the defined operating state of the circuit device, particularly regarding the second voltage value. It should be considered that the existing voltage division changes due to the capacitive voltage divider. This is fully utilized within the range of the stage through selective coupling.

[0047] In particular, the intermediate layer capacitors are configured differently in cases of faulty and functional core connections, allowing the core connection to be judged as normal or faulty based on the measured voltage distribution. This improves the reliability of the identification mechanism used to detect faulty core leads.

[0048] In some embodiments, the skeleton structure is electrically coupled to the vehicle frame components via a grounding wire. The ambient capacitance is zero in this case, and the capacitive voltage divider is eliminated. The control device of the circuit arrangement is designed in this case to detect faulty skeleton leads based solely on first and second voltage values. Therefore, the detection mechanism for faulty skeleton leads becomes particularly compact. This means that faulty skeleton leads can be determined, especially independently of the voltage values ​​detected with respect to the conductive layer. Additionally, this embodiment enables the implementation of different topologies, which may be desirable for a given application.

[0049] Alternatively, in the embodiment where a separate grounding wire is provided for the skeleton structure, the switching device can also be arranged such that an alternating conductivity value is formed between the skeleton structure (via the skeleton leads) and the vehicle frame components. This achieves and ensures an additional fault identification mechanism, namely, that the integrity of the skeleton leads can be determined by the alternating conductivity value, despite the separate grounding wire.

[0050] Preferably, according to the embodiment outlined last, the skeleton lead is detected as faulty when the second voltage value exceeds a minimum threshold. The compactness of the detection mechanism for detecting faulty skeleton leads is shown here. Only a comparison between the second voltage value and the minimum threshold is needed.

[0051] Preferably, the circuit device has a single conductive layer. This makes the circuit device, and therefore the steering wheel's structure, particularly compact in terms of circuitry. As a result, manufacturing costs are low.

[0052] Optionally, the at least one conductive layer is configured as a resistance heating device and / or a hand recognition device (HOD) for the steering wheel. This means that the conductive layer can also fulfill additional functions, based on which, for example, the authenticity of autonomous or at least partially autonomous driving functions can be achieved, thereby improving the comfort for vehicle users.

[0053] Preferably, the HOD function is ensured based on the intermediate layer capacitor. In capacitive hand recognition devices, the definition of the potential on the steering wheel frame, i.e., the frame structure, is meaningful for reliable hand recognition. The circuit arrangement described herein allows for reliable checking of the frame leads, thereby ensuring the HOD function. For example, if a frame connection fault is detected, the hand recognition device (HOD function) can be classified as faulty or inactive. This can be taken into account in downstream driving control systems.

[0054] To perform resistance heating, it can be specified that an electric current is applied to a conductive layer, and the current is converted into heat energy through the conductive layer.

[0055] According to another aspect, a steering wheel for a vehicle is also proposed, which has the circuitry as described above or has a circuitry that can operate according to the method described above.

[0056] According to an additional aspect, a vehicle having the steering wheel previously described is also provided. Attached Figure Description

[0057] The invention, along with other advantageous embodiments and further improvements, is described and illustrated below with reference to examples shown in the accompanying drawings. Features derived from the description and drawings can be used individually or in any combination thereof according to the invention. In the drawings:

[0058] Figure 1 A schematic diagram of a circuit arrangement for a vehicle steering wheel and a steering wheel according to an embodiment of the present invention is shown.

[0059] Figure 2 A schematic diagram of a circuit arrangement for a vehicle steering wheel and a steering wheel according to another embodiment of the present invention is shown.

[0060] Figure 3 A schematic diagram illustrating a method for operating a circuit device for a vehicle steering wheel according to an embodiment of the present invention. Detailed Implementation

[0061] All features disclosed below with reference to the embodiments and / or accompanying drawings can be combined individually or in any sub-combination with features of various aspects of this disclosure (including features of preferred embodiments), provided that the resulting combination of features is meaningful to those skilled in the art.

[0062] Figure 1 A schematic diagram of a circuit device 10 for a vehicle steering wheel 12 according to an embodiment of the present invention is shown. The steering wheel 12 is shown as a radial cross-section of the steering wheel rim.

[0063] The structure of the steering wheel 12 is basically determined by the circuit device 10, at least in terms of the conductive parts.

[0064] The steering wheel according to this embodiment includes leather as an outer upper layer 14. A conductive layer 16 is disposed below the upper layer 14, the conductive layer having at least a portion of a conductive material. For example, the conductive layer 16 can be constructed using an electrical conductor in the form of a two-dimensional conductive grid.

[0065] According to this embodiment, a non-conductive layer 18 is disposed adjacent to and below the conductive layer 16, and this non-conductive layer comprises foam. The non-conductive layer 18 surrounds the skeleton structure 20, which also has a conductive material and functions as a dielectric between the conductive layer 16 and the skeleton structure 20.

[0066] The circuit device 10 also includes a control device 22, which is coupled not only to the conductive layer 16 but also to the skeleton structure 20.

[0067] According to this embodiment, the control device 22 includes a voltage source 24, which may also be external to the control device 22 according to other examples.

[0068] The control device 22 is coupled to the skeleton structure 20 such that the skeleton lead 26 can be used to couple the skeleton structure 20 to the voltage source 24. For this purpose, the skeleton lead 26 is connected to an interface 28, which is electrically coupled to the skeleton structure 20.

[0069] A capacitor is formed by the conductive layer 16 and the skeleton structure 20 through the non-conductive layer 18 (which is the dielectric between the conductive layer 16 and the skeleton structure 20), which is shown in the present case as the intermediate layer capacitor 30 (intermediate layer capacitor).

[0070] Since the frame structure 20 is typically subjected to stress, at least temporarily, an ambient capacitance 32 is formed between the frame structure 20 and the vehicle frame component 34 (ideally infinitely distant). This ambient capacitance 32 is typically variable over time, as the steering wheel 12 experiences vibrations and movements, and also because the electrostatic relationship with respect to the vehicle frame component 34 can change. Consequently, in an alternative consideration, a time-variable resistance 36 can be assumed to form between the frame structure 20 and the vehicle frame component 34. In this case, resistance 36 is referred to as a second resistance R2.

[0071] The skeleton lead 26 has a dedicated, separately arranged first resistor 38, R1, which is arranged between the voltage source 24 and the intermediate layer capacitor 30.

[0072] Control device 22 is designed to detect a first voltage value 40 (also denoted as V1) on the voltage source side of the first resistor 38. Additionally, control device 22 is also designed to detect a second voltage value 42 (also denoted as V2) on the frame side of the first resistor 38. For this purpose, control device 22 may, for example, have a corresponding measurement interface that can be selectively coupled to the voltage source side of the first resistor 38, R1 and the frame component.

[0073] In order to selectively couple the skeleton structure 20 and thus the skeleton lead 26 to the voltage source 24, the first switching device 46 is arranged between the voltage source 24 and the voltage source side of the first resistor 38, R1.

[0074] Additionally, a second switching device 47 is arranged between the terminal 44 of the control device 22 and the voltage source side of the first resistor 38, R1.

[0075] This means that the first switching device 46 and the second switching device 47 are coupled to each other at node 48 on the voltage source side of the first resistor 38, R1. At node 48, the first voltage value 40, V1 on the voltage source side can then be detected, for example, by selectively coupling with the measurement interface of the control device 22.

[0076] The control device 22 is designed to adjust the switching states of the switching devices 46 and 47.

[0077] Additionally, the control device 22 according to this embodiment includes an analog-to-digital converter (ADC) 50, which is coupled to the conductive layer 16 on one side and to the skeleton side of the first resistors 38, R1 on the other side. For example, the ADC 50 can be coupled to a dedicated node 49, which is arranged between the first resistors 38 and the intermediate layer capacitor 30 on the skeleton side of the first resistors 38, R1. At node 49, a second voltage value 42, V2 can be detected using the ADC 50. Additionally, the ADC 50 is also designed to detect a third voltage value V3 with respect to the conductive layer 16.

[0078] The detected voltage values ​​V1, V2, and V3 are transmitted to the data processing unit of the control device 22, which can determine whether there is a fault in the skeleton lead 26 based on the detected measurement values. Here, a capacitive voltage divider for the conductive layer 16 can be constructed using the intermediate layer capacitor 30 and the ambient capacitor 32.

[0079] The voltage values ​​V1, V2, and V3 can be detected under the defined operating conditions of the circuit device 10.

[0080] In the first stage, the first switching device 46 can be opened and the second switching device 47 can be closed. This means that the skeleton lead 26 is not coupled to the voltage source 24, but only to the terminal 44 of the control device. In the first stage, the skeleton lead 26 can be additionally coupled to the vehicle frame component 34 via the grounding wire 51 by means of the control device 22 and, for example, the terminal 44, which is electrically grounded in this respect. As a result, the intermediate layer capacitor 30 is discharged because the stored charge flows out through the terminal 44 toward the vehicle ground in the form of the vehicle frame component 34. Thus, the intermediate layer capacitor is placed at a defined potential, i.e., grounded.

[0081] In the second stage, the first switching device 46 can be closed and the second switching device 47 can be opened. This means that the skeleton lead 26 is coupled only to the voltage source 24, but not to the terminal 44 of the control device 22, and therefore (effectively) not to the vehicle frame component 34. In the second stage, the intermediate layer capacitor 30 can be charged at least partially using the charge provided by the voltage source 24. The charging behavior of the intermediate layer capacitor 30 depends directly on whether the skeleton lead 26 is faulty or intact. This can be fully utilized in the current situation to assess whether the skeleton lead 26 is faulty.

[0082] Since the skeleton lead 26 and therefore the intermediate layer capacitor 30 are coupled to the voltage source 24 during the second stage, the second voltage values ​​42, V2 and the third voltage values ​​50, V3 can be detected, in particular, during the second stage. Time intervals can be considered here, so that the measured values ​​of voltage values ​​42, 50, V2, V3 are detected at a defined time point after the start of the second stage or within a defined time interval. Thus, a defined operating state that the circuit device 10 should have at said time point is defined, unless the skeleton lead 26 is not faulty. This enables a precise comparison of the measured values ​​of voltage values ​​42, 50, V2, V3 with corresponding expected values, which can be considered, for example, when evaluated using voltage thresholds S1, S2.

[0083] Figure 3 A schematic diagram of a method 55 for operating a circuit device 10 for a steering wheel 12 of a vehicle according to an embodiment of the present invention is shown. Optional steps are shown in dashed lines.

[0084] Method 55 begins with an optional step 56, in which all relevant voltage lines, particularly 40, V1, 42, V2 and 50, V3, are coupled to ground. This, in particular, allows the intermediate layer capacitor 30 to discharge and ensures the initial conditions defined for method 55.

[0085] The method then includes an optional step 57 in which a first voltage value 40 V1 is measured on the device using a switching device 46 at a predetermined time interval, for example, the node 48 of which is first coupled to the voltage source 24.

[0086] Method 55 can then be constructed such that the additional steps 58, 60, 64, in which different voltage values ​​are detected, are performed within a predetermined time interval t1 from the coupling with voltage source 24. Here, the time interval t1 is determined such that it is much smaller than the product of the resistance values ​​of the first resistor 38, R1 of the skeleton lead 26 and the capacitance value of the intermediate layer capacitor 30. Figure 3 This is indicated by curved brackets. This prevents a steady-state value from being reached when the voltage value is detected.

[0087] Method 55 then includes step 58, in which the first resistance 38 of the skeleton lead 26, the first voltage value 40 on the voltage source side of R1, and V1 are detected.

[0088] Additionally, method 55 includes step 60, in which a second voltage value 42, V2 is detected on the skeleton side of the first resistor 38, R1 of the skeleton lead 26.

[0089] According to the circuit device 10 in Figure 1 In the embodiment shown, method 55 also includes a generally optional step 64 in which a third voltage value 50, V3 for at least one conductive layer 16 is detected.

[0090] Steps 60 and 64 of method 55 are performed, in particular, at a predetermined time interval after the start of the second phase, i.e., when the skeleton lead 26 is coupled only to the voltage source 24, not to the terminal 44, using the switching devices 46 and 47.

[0091] Finally, method 55 also includes step 62, in which the faulty skeleton lead 26 is detected by control device 22 based on ambient capacitance 32 at least based on first voltage value 40, V1 and second voltage value 42, V2.

[0092] As already described, the coupling between the skeleton structure 20 and the vehicle frame component 34 can be described by means of a second resistor 36, R2 that varies with time. Based on the relative resistance values ​​of the first resistor 38, R1 arranged inside the skeleton lead 26 and the second resistor 36, R2 that vary with time, the operating states can be schematically shown in the forms A), B), and C) regarding the measured values ​​of voltage values ​​V1, V2, V3.

[0093] According to operating state A), the first resistors 38 and R1 can (very often) be smaller than the second resistors 36 and R2. In this case, the capacitive voltage divider constructed with respect to the conductive layer 16 by the intermediate layer capacitor 30 and the ambient capacitor 32 causes the voltages existing on the skeleton lead 26 and the conductive layer 16 (corresponding to the second voltage values ​​42 and V2 and the third voltage values ​​50 and V3) to be in a defined relationship with each other at least within a predetermined time interval, during which the measured values ​​are detected. Here, this relationship is caused by the capacitive voltage divider. In this case, the second voltage values ​​42 and V2 are a factor larger than the third voltage values ​​50 and V3 of the conductive layer 16 on the skeleton side of the first resistors 38 and R1. Correspondingly, corresponding voltage thresholds can be set, such as a first voltage threshold S1 for the second voltage values ​​42 and V2 and a second voltage threshold S2 for the third voltage values ​​50 and V3, by means of which this situation can be determined. If the associated voltage thresholds S1 and S2 are exceeded by the corresponding voltage values ​​42, 50, V2, and V3 respectively, the existence of operating state A can be detected by the control device 22.

[0094] In operating state B), the first resistance 38, R1 is (significantly) greater than the second resistance 36, R2. This is, for example, when the skeleton lead 26 is electrically coupled to the vehicle frame component 34 during the second phase. In this case, the intermediate layer capacitor 30 is discharged and the charge stored therein flows out toward the vehicle frame component 34, which serves as the vehicle ground. Since the skeleton lead 26 is still coupled to the voltage source 24 during the second phase, the first voltage value 40, V1 is not zero. However, in contrast, the second voltage value 42, V2 and the third voltage value 50, V3 are zero in this case. Therefore, the existence of operating state B) can be determined, for example, by determining that the second voltage value 42, V2 does not exceed the first voltage threshold S1 and the third voltage value 50, V3 does not exceed the second voltage threshold S2.

[0095] In operating state C), the skeleton lead 26 is faulty, for example, broken. In this case, the capacitive voltage divider with respect to the conductive layer 16 is inactive. This means that the third voltage value 50, V3 is zero in this case. Therefore, if it is determined that the third voltage value 50, V3 does not exceed its associated second voltage threshold S2 and at the same time the second voltage value 42, V2 exceeds its associated first voltage threshold S1, the control device 22 can detect the presence of a faulty skeleton lead 26. Relatedly, taking into account the capacitive voltage divider composed of the intermediate layer capacitor 30 and the ambient capacitor 32, the second voltage threshold S2 is selected according to the first voltage threshold S1.

[0096] Therefore, all relevant operating states can be distinguished from each other in terms of the coupling between the skeleton structure and the vehicle frame component 34 or the integrity of the skeleton leads 26. As a result, it is also possible to determine when functionality additionally implemented by the conductive layer 16, such as resistance heating or HOD functionality, is considered satisfactory. In other words, it is possible to determine when measurement signals based on HOD functionality can be trusted. This has an impact on the execution of autonomous or partially autonomous driving functions.

[0097] Figure 2 A schematic diagram of a circuit arrangement 10 for a vehicle steering wheel 12 and a steering wheel 12 according to another embodiment of the present invention is shown. Only the differences are discussed here.

[0098] Unlike the previously shown implementation, the skeleton structure 20 is now permanently coupled to ground via a dedicated grounding wire 52 and a separate grounding terminal 54. As a result, the ambient capacitance 32 is zero in this case. This means that no capacitive voltage divider is constructed with respect to the conductive layer 16. This simplifies the identification of faulty skeleton leads 26. According to this implementation, operating state A) is not possible.

[0099] However, the conductivity between the skeleton structure 20 and ground is variable via the skeleton lead 26 using the switching device 47. This ensures that the effects of grounding can be taken into account when monitoring the skeleton lead 26. The first voltage values ​​40, V1 and / or the second voltage values ​​42, V2 can therefore be detected when the switching device 47 is open. The corresponding nodes on which the first and second voltage values ​​40, V1, 42, V2 are detected can therefore be coupled only to the skeleton structure 20.

[0100] As a result, according to the operating state C) of this embodiment, a faulty skeleton lead can be detected solely based on the first voltage values ​​40, V1 and the second voltage values ​​42, V2. For this purpose, only the second voltage values ​​42, V2 are compared with the associated first voltage threshold S1. If the second voltage values ​​42, V2 exceed the first voltage threshold S1, then an operating state C) corresponding to a faulty skeleton lead 26 exists. Otherwise, the skeleton lead 26 can be presumed to be intact.

[0101] The specific embodiments disclosed herein, and in particular the corresponding modules, use switching circuits (e.g., one or more switching circuits) to execute the standards, protocols, methods, or techniques disclosed herein, enabling two or more components to be properly coupled, generate information, process information, analyze information, generate signals, encode / decode signals, convert signals, transmit and / or receive signals, control other devices, etc. Any type of circuit can be used.

[0102] In one embodiment, the circuit (switching circuit) particularly includes one or more computing devices, such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system-on-a-chip (SoC), and any combination thereof, and may include discrete digital or analog circuit elements or electronic devices or combinations thereof. In one embodiment, the circuit includes hardware circuit execution schemes (e.g., execution schemes in analog switching circuits, execution schemes in digital switching circuits, and combinations thereof).

[0103] In one embodiment, the switching circuit includes a combination of a switching circuit and a computer program product having software or firmware instructions stored on one or more computer-readable storage media that cooperate to cause a device to perform any or more of the protocols, methods, or techniques described herein. In one embodiment, the circuit technology includes a switching circuit, such as a microprocessor or a portion thereof, which requires software, firmware, etc., to operate. In one embodiment, the switching circuit includes one or more processors or portions thereof, and associated software, firmware, hardware, etc.

[0104] Quantities and figures may be referenced in this application. Unless explicitly stated otherwise, such quantities and figures should not be construed as limiting, but rather as examples of feasible quantities or figures relevant to this application. In this context, the term "multiple" may also be used to refer to quantities or figures. In this context, the term "multiple" means any number greater than one, such as two, three, four, five, etc. The terms "approximately," "approximately," "close to," etc., mean plus or minus 5% of a given value.

[0105] While this disclosure has been shown and described with respect to one or more implementation schemes, those skilled in the art will identify equivalent changes and modifications upon reading and understanding this specification and the accompanying drawings. Although specific features of this disclosure have been disclosed with respect to only one of several embodiments, such features may be combined with one or more other features of other embodiments as may be desired and advantageous for a given or particular application.

Claims

1. An electrical device (10) for a vehicle steering wheel (12), wherein, The steering wheel (12) has at least one conductive layer (16) and a skeleton structure (20). An intermediate layer capacitor (30) is formed between the conductive layer (16) and the skeleton structure (20), and an environmental capacitor (32) is formed between the skeleton structure (20) and the vehicle frame component (34). The intermediate layer capacitor (30) and the ambient capacitor (32) constitute a capacitive voltage divider for the conductive layer (16). The circuit device (10) also has a voltage source (24) that can be selectively coupled to the skeleton structure (20) via skeleton leads (26). The skeleton lead (26) has a resistor (38). The circuit device (10) is designed to detect at least a first voltage value (V1) on the voltage source side of the resistance (38) of the skeleton lead (26) and a second voltage value (V2) on the skeleton side of the resistance (38) of the skeleton lead (26), and The control device (22) of the circuit device (10) is designed to detect faulty skeleton leads (26) based on the ambient capacitance (32) with at least the first voltage value and the second voltage value (V1, V2).

2. The circuit device (10) according to claim 1, characterized in that, The ambient capacitance (32) is variable.

3. The circuit device (10) according to claim 1 or 2, characterized in that, The skeleton lead (26) can be selectively coupled to the vehicle ground, thereby forming an alternating conductivity value between the skeleton structure (20) and the vehicle ground by means of a switching device (47).

4. The circuit device (10) according to claim 3, characterized in that, The circuit device (10) is additionally designed to detect at least a third voltage value (V3) for the at least one conductive layer (16), and the control device (22) is designed to detect a faulty skeleton lead (26) based on a variable ambient capacitance (32) in addition to taking into account the third voltage value (V3).

5. The circuit device (10) according to claim 4, characterized in that, When the second voltage value (V2) exceeds the first voltage threshold (S1) and the third voltage value (V3) does not exceed the second voltage threshold (S2), a fault is detected in the skeleton lead (26), wherein, taking into account the capacitive voltage divider, the second voltage threshold (S2) depends on the first voltage threshold (S1).

6. The circuit device (10) according to any one of claims 3 to 5, characterized in that, The control device (22) is designed to place the skeleton lead (26) in a first defined state at least in a first stage, in which the skeleton lead (26) is decoupled from the voltage source (24) and coupled to the vehicle ground, and in a second defined state in a second stage, in which the skeleton lead (26) is decoupled from the vehicle ground and coupled to the voltage source (24), and the circuit device (10) is designed to detect the second voltage value (V2) within a predetermined time interval after the start of the second stage.

7. The circuit device (10) according to claim 1, characterized in that, The skeleton structure (20) is electrically coupled to the vehicle frame component (34) via a grounding wire (52), wherein the ambient capacitance (32) is zero in this case, and the control device (22) of the circuit device (10) is designed in this case to detect faulty skeleton leads (26) only by means of the first voltage value and the second voltage value (V1, V2).

8. The circuit device (10) according to claim 7, characterized in that, The switching device (47) is arranged such that an alternating conductivity value is formed between the skeleton structure (20) and the vehicle frame component (34).

9. The circuit device (10) according to claim 7 or 8, characterized in that, When the second voltage value (V2) exceeds the minimum threshold, the skeleton lead (26) is detected as faulty.

10. The circuit device (10) according to any one of the preceding claims, characterized in that, The circuit device (10) has a single conductive layer (16).

11. The circuit device (10) according to any one of the preceding claims, characterized in that, The at least one conductive layer (16) is configured as a resistance heating device and / or configured for hand recognition of the steering wheel (12).

12. A method (55) for operating a circuit device (10) for a vehicle steering wheel (12), wherein, The steering wheel (12) has at least one conductive layer (16) and a frame structure (20), an intermediate layer capacitor (30) is formed between the conductive layer (16) and the frame structure (20), and an environmental capacitor (32) is formed between the frame structure (20) and the vehicle frame component (34). The intermediate layer capacitor (30) and the ambient capacitor (32) constitute a capacitive voltage divider for the conductive layer (16). The circuit device (10) also has a voltage source (24) that can be selectively coupled to the skeleton structure (20) via skeleton leads (26). The skeleton lead (26) has a resistor (38), and The method (55) includes at least the following steps: - Detect the first voltage value (V1) on the voltage source side of the resistance (38) of the skeleton lead (26). - Detect the second voltage value (V2) on the skeleton side of the resistance (38) of the skeleton lead (26). - Based on the ambient capacitance (32), at least based on the first voltage value (V1) and the second voltage value (V2), the control device (22) detects the faulty skeleton lead (26).

13. The method (55) according to claim 12, characterized in that, The skeleton structure (20) is electrically coupled to the vehicle frame component (34) via a grounding wire (52), wherein the ambient capacitance (32) is zero in this case, and the control device (22) of the circuit device (10) detects the faulty skeleton lead (26) only by means of the first and second voltage values ​​(V1, V2).

14. The method (55) according to claim 12, characterized in that, The method (55) further includes: - Detect a third voltage value (V3) for the at least one conductive layer (16). The control device (22) additionally detects faulty skeleton leads (26) while taking into account the third voltage value (V3), and the ambient capacitance (32) is variable in this case.

15. A steering wheel (12) for a vehicle, the steering wheel having a circuit device (10) according to any one of claims 1 to 11 or having a circuit device (10) capable of operating according to the method (55) according to any one of claims 12 to 14.

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