Steering wheel actuator device for a steer-by-wire steering system of a motor vehicle and operating procedures

Abstract

A steering wheel actuator device (110, 210) for a steer-by-wire steering system (105) of a motor vehicle (100) is presented.It comprises at least one steering wheel angle sensing device (211) for sensing a steering wheel angle of a steering wheel (140), an actuator motor device (212) for generating an actuator motor torque that counteracts a driver torque applied to the steering wheel (140), and a control device (219), wherein the steering wheel actuator device (210) is connectable to an electrical energy source (250) which supplies the steering wheel actuator device (210) with electrical energy at least in a normal operating condition, and wherein the steering wheel actuator device (210) also comprises an electrical energy storage device (216) that can be charged up to a limit value and is configured to supply at least the at least one steering wheel angle sensing device (211) with stored electrical energy when, in an irregular operating condition, the steering wheel actuator device (210) is not supplied with electrical energy by the electrical energy source (250).Preferably, the electrical energy storage device (216) can be charged with electrical energy generated by the actuator device (212) when the applied driver torque overcomes the actuator torque.

Description

[0001] The present invention relates to a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle, a steer-by-wire steering system, a motor vehicle and a suitable method for operating the steering wheel actuator device.

[0002] A motor vehicle is usually steered by the driver changing the orientation of the steerable wheels in contact with the road. To do this, the driver operates a steering wheel, whose change in steering or rotation angle is converted into a change in the angle of the steered wheels relative to the road. For this purpose, there can be a mechanical connection between the steering wheel operated by the driver and the steered wheels of the motor vehicle, e.g., via a steering column and handlebar. A steer-by-wire steering system, on the other hand, detects the steering command or the corresponding steering angle information using one or more sensors, in particular at least one steering wheel angle sensor, and transmits this exclusively via an electrical connection, possibly with the aid of one or more control devices, to an electromechanical actuator, which executes the steering command and changes the orientation of the steered wheels accordingly.For this purpose, a steer-by-wire steering system comprises a feedback actuator device, i.e., a steering wheel actuator device connected to the vehicle's steering wheel, and a road wheel actuator device, i.e., an axle actuator device, electrically connected to this, which controls the angles of the steered wheels relative to the road. The steering wheel actuator device serves to detect the steering wheel angle set by the driver and, with the aid of a servomotor, to generate a servomotor torque appropriate to the current driving situation, i.e., a feedback torque for the driver that counteracts the driver torque applied to the steering wheel by the driver. The axle actuator device moves the steered wheels to the requested position with the aid of another servomotor.

[0003] Since a vehicle's steering system is a safety-relevant vehicle system, it is necessary to ensure the safe, uninterrupted availability of the control function of a steer-by-wire steering system. A failure of the electrical communication between the steering wheel actuator device and the axle actuator device, or a failure of the steering wheel angle detection, would result in a loss of controllability of the vehicle. Unavailability of the control of the servomotor of the steering wheel actuator device can result in no longer generating driver torque, so that the driver may turn the steering wheel with virtually no effort and thus, in particular, make unintentionally large steering angle changes. These can then lead to unintentionally large steering angles of the steered wheels of the motor vehicle unless damping is implemented for safety reasons through a suitable design of the steering wheel actuator device upon detection of such a fault condition.

[0004] Therefore, steer-by-wire steering systems may provide redundant components, for example the use of multiple sensors for angle detection, multiple steering wheel actuator devices, multiple axle actuator devices or, in particular, the use of multiple external sources of electrical energy to which the steering wheel actuator device and / or the axle actuator device are connected.

[0005] DE 100 53 335 A1 describes a steer-by-wire steering system for motor vehicles in which all essential components are provided in multiple locations. The system's power supply also requires connection to multiple batteries.

[0006] US 2002 / 0005315 A1 describes a steering system that supports steer-by-wire operation and provides additional damping of the steering wheel movements if the steering wheel actuator fails.

[0007] WO 2019 / 179859 A1 describes a steer-by-wire steering system in which the steering wheel actuator device and the axle actuator device are jointly connected to two redundant power sources.

[0008] WO 2019 / 243300 A1 presents a steer-by-wire steering system in which the axle actuator is connected to two redundant power sources, the feedback actuator is also connected to one of the power sources and the system additionally has another steering angle sensor connected to the other power source.

[0009] DE 20 2014 100 980 U1 describes a drive system in which a DC motor is switched to a short-circuit state in response to a sudden power failure in order to generate a resistive torque, the short-circuit transistors used being supplied with power by an auxiliary power supply.

[0010] Since the electrical energy supply is usually provided by the vehicle battery, providing redundancy is associated with high costs and, in addition, the independence of the energy sources from one another, which is sensible from a safety perspective, cannot always be guaranteed.

[0011] The present invention is based on the object of providing a cost-effective alternative possibility of ensuring the availability of the steering of a motor vehicle with a steer-by-wire steering system even in the event of a disruption or partial loss of the regular electrical power supply.

[0012] This object is achieved according to the invention with a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle according to claim 1, a steer-by-wire steering system for a motor vehicle according to claim 11, a motor vehicle according to claim 12 and a method for operating a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle according to claim 13.

[0013] Advantageous further developments of the invention are specified in the subclaims.

[0014] According to a first aspect of the invention, a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle comprises at least one steering wheel angle detection device for detecting a steering wheel angle, a servomotor device for generating a servomotor torque that counteracts a driver torque applied to the steering wheel, and a control device. The steering wheel actuator device is connectable to an electrical energy source that supplies the steering wheel actuator device with electrical energy, at least during regular operation.It is provided that the steering wheel actuator device also has an electrical energy storage device that can be charged up to a limit value and is designed to supply at least the at least one steering wheel angle detection device with stored electrical energy if, in an irregular operating case, the steering wheel actuator device is not supplied with electrical energy by the electrical energy source.

[0015] A steering wheel angle is the angle by which the steering wheel is turned by the driver around its axis of rotation. A steering wheel angle detection device comprises a steering wheel angle sensor and any necessary control circuits. A servomotor device comprises a servomotor, for example a DC motor, which is preferably brushless due to its lower mechanical friction, and one or more switch assemblies for switching the individual phases of the servomotor. The switch assemblies consist of controllable semiconductor switching elements, for example field-effect transistors and / or thyristors. The control device, which can be a programmable device, e.g., a processor or microcontroller, is configured to send control signals to the switch assemblies to control the current operating state of the servomotor.In addition, depending on the embodiment of the steering wheel angle detection device, it can be provided that the control device receives steering wheel angle signals from the steering wheel angle detection device, processes them and also transmits these or associated steering commands to the axle actuator device.

[0016] An electrical energy source is a current or voltage source, such as the vehicle battery, and is intended, under normal conditions—that is, during trouble-free, regular operation—to supply at least the steering wheel actuator device with electrical energy. An irregular operating condition occurs when the electrical energy source is disconnected, switched off, or malfunctioning, so that it cannot supply the steering wheel actuator device with electrical energy as normally intended.

[0017] For this irregular operating scenario, the steering wheel actuator device is equipped with its own internal energy storage device, which comprises, for example, a storage capacitor, which at least enables at least one steering wheel angle detection device to be supplied with stored electrical energy, even if the (main) electrical energy source is unavailable. This at least ensures that the steering wheel angle continues to be detected, without which the motor vehicle would otherwise no longer be steerable. If only the detection of the steering wheel angle is ensured, the steering wheel angle detection device is designed to transmit the steering wheel angle or the associated steering command directly to the axle actuator device.The electrical energy storage device can be charged up to a limit value, which, when reached, ensures that sufficient energy is available for at least temporary continued operation of the steering wheel angle detection device. The limit value can be the maximum value, i.e., the maximum amount of electrical energy that can be stored.

[0018] In this way, at least a sudden failure of the steering in the event of loss of the energy source actually provided in normal operation can be prevented, whereby the size of the electrical energy storage device can be selected to be small and thus cost-effective if the energy is only to be sufficient to ensure, for example, only a safe stop.

[0019] In one embodiment, the steering wheel actuator device is configured such that, in the irregular operating case, the electrical energy storage device also supplies at least the control device with stored electrical energy. In this embodiment, it can be provided that the steering wheel angle detection device is supplied with energy by the control device. The electrical energy storage device is dimensioned such that it can also supply the control device with electrical energy, thus at least ensuring the continuation of the steering angle detection.

[0020] In a further embodiment of the steering wheel actuator device, the actuator motor device is configured to generate electrical energy when, in a generator operating state, the applied driver torque overcomes the actuator motor torque, i.e., acts in the opposite direction and exceeds the magnitude. In this way, electrical energy can be generated in the steering wheel actuator device independently of the availability of the external electrical energy source. The generator operating state is one of several possible operating states of the actuator motor device and can be assumed in both regular and irregular operating cases of the steering wheel actuator device.During normal operation of the steering wheel actuator device, in which the external electrical energy source is also available, the actuator device can also be operated in the electric motor operating state, in which the applied driver torque does not overcome the actuator motor torque, so that electrical energy is consumed. Since the internal electrical energy storage device is intended to be a cost-effective safety solution, it is not intended to be dimensioned in such a way that it can permanently enable regular operation of the steering wheel actuator device even when the external electrical energy source is unavailable. During irregular operation of the steering wheel actuator device, an operating state of the actuator device can also be available in which the possible steering wheel movement is damped.

[0021] In an exemplary embodiment, the steering wheel actuator device is configured to at least partially store electrical energy generated in the generator operating state in the electrical energy storage device if its charge level is below the limit value. In other words, in this way, the electrical energy storage device can be charged by steering movements, i.e., rotations of the steering wheel by the driver, even during irregular operating conditions. Even if the steering system is de-energized and no longer operational, it can be restarted and made operational by turning the steering wheel. The charge level of the electrical energy storage device is a parameter that represents either an absolute value or a relative value, e.g., a percentage of the total storage capacity defined by the limit value.It is intended that overcharging of the energy storage device is prevented, for example by a protective circuit belonging to the energy storage device.

[0022] In a further embodiment, the steering wheel actuator device is configured to store electrical energy from the electrical energy source at least partially in the electrical energy storage device during normal operation if its charge level is below the limit value. In addition or alternatively to charging the electrical energy storage device by rotational movements of the steering wheel, it is provided that the internal electrical energy storage device of the steering wheel actuator device is charged by the external electrical energy source when this is available during normal operation.

[0023] In one embodiment of the steering wheel actuator device, the electrical energy storage device comprises a storage capacitor. Alternatively, it can also be a rechargeable battery, e.g., a lithium-ion battery.

[0024] In one embodiment of the steering wheel actuator device, the actuator motor device is configured to switch to a phase-short-circuit operating state, at least during irregular operation, when the charge level of the electrical energy storage device reaches the limit value. This can be the case, for example, when the electrical energy storage device is at its maximum charge. In the phase-short-circuit operating state, the phases of the actuator motor are short-circuited by switch assemblies consisting of semiconductor switching elements, so that the actuator motor acts as an electromagnetic brake when the driver moves the steering wheel. In this way, the steering wheel movement is dampened. Generated energy can be dissipated as heat.For this purpose, the semiconductor switching elements of the switch assemblies of the actuator motor device can be configured in such a way that they switch them into the phase short-circuit operating state based on control signals received from the control device or if all control signals are lost.

[0025] Since electrical energy is consumed in the phase-short-circuit operating state, at least for generating the control signals and operating the steering wheel angle detection device, the charge level of the electrical energy storage device slowly changes and drops below the limit value. It may be possible to switch back to the generator operating state and recharge the electrical energy storage device until the limit value is reached again. This prevents overcharging of the energy storage device and simultaneously prevents discharging of the energy storage device, so that the steering function remains available.In a preferred embodiment, in which the control device is kept ready for operation, it is configured, after switching back from the phase-short-circuit operating state, to adapt the actuator torque generated in the generator operating state to the damping torque last generated in the phase-short-circuit operating state. This offers the advantage of reducing the driver's perceptibility of the change in operating states.

[0026] In a further embodiment, the semiconductor switching elements of the servomotor device can also be designed to switch directly to the phase-short-circuit operating state upon loss of the electrical power supply. This is particularly advantageous in an alternative embodiment of the steering wheel actuator device, in which the servomotor device is configured to switch to a phase-short-circuit operating state in the event of irregular operation and to generate electrical energy when the applied driver torque overcomes a damping torque generated in the phase-short-circuit operating state. In other words, in this embodiment, upon loss of the external electrical power supply, the system switches directly to the phase-short-circuit operating state, with provision being made here to generate electrical energy even in this state and to use it to charge the electrical energy storage device.In this way, it is possible to avoid having to continually change the operating state of the servomotor device in order to extend the operational capability of the steering system.

[0027] In one embodiment, the steering wheel actuator device further comprises a disconnecting device for interrupting an electrical connection to the electrical energy source, at least in the event of irregular operation. This prevents the electrical energy storage device from being discharged via the electrical energy source in the event of a short circuit of the electrical energy source to ground. Such a disconnecting device can comprise, for example, a diode circuit.

[0028] In one embodiment of the steering wheel actuator device, a storage capacity of the electrical energy storage device is determined depending on an average duration of inactivity phases of the steering wheel. Since the charge state of the electrical energy storage device depends on the rotational movement of the steering wheel, at least during irregular operation, a situation can arise in principle that too few steering movements charge the energy storage device less quickly than it is discharged by maintaining the steering functionality. In the described embodiment, the storage capacity is therefore determined taking into account an average duration of an inactivity phase, i.e., a period without steering movements, such that the probability that the electrical energy storage device is discharged during an inactivity phase is reduced to a low value defined as acceptable.

[0029] According to a second aspect of the invention, a steer-by-wire steering system for a motor vehicle comprises a steering wheel actuator device according to the first aspect of the invention and an axle actuator device electrically connected to the steering wheel actuator device. According to a third aspect of the invention, a motor vehicle comprises a steer-by-wire steering system according to the second aspect of the invention.

[0030] Furthermore, according to a fourth aspect of the invention, a method for operating a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle, wherein the steering wheel actuator device has at least one steering wheel angle detection device for detecting a steering wheel angle of a steering wheel, a servomotor device for generating a servomotor torque counteracting a driver torque applied to the steering wheel, a control device, and an electrical energy storage device that can be charged up to a limit value, comprises the following steps: Supplying the steering wheel actuator device with electrical energy, at least in a regular operating case, by an electrical energy source connected to the steering wheel actuator device; and Supplying at least the at least one steering wheel angle detection device of the steering wheel actuator device with stored electrical energy by the electrical energy storage device of the steering wheel actuator device in an irregular operating case in which the steering wheel actuator device is not supplied with electrical energy by the electrical energy source.

[0031] In one embodiment, the method comprises a step of supplying the control device of the steering wheel actuator device with stored electrical energy by the electrical energy storage device of the steering wheel actuator device in the irregular operating case in which the steering wheel actuator device is not supplied with electrical energy by the electrical energy source.

[0032] In one embodiment, the method further comprises a step of generating electrical energy by the actuator device when, in a generator operating state, the applied driver torque overcomes the actuator torque. In an exemplary embodiment, it is then also provided to store at least some of the electrical energy generated in the generator operating state in the electrical energy storage device when its state of charge is below the limit value. Alternatively or additionally, a further embodiment of the method provides for storing at least some of the electrical energy from the electrical energy source in the electrical energy storage device during regular operation when its state of charge is below the limit value.

[0033] In yet another embodiment, the method further comprises switching the actuator device to a phase-short-circuit operating state in the irregular operating case when the charge level of the electrical energy storage device reaches the limit value. In an alternative embodiment, the actuator device can also directly switch to a phase-short-circuit operating state in the irregular operating case and generate electrical energy if the applied driver torque overcomes a damping torque generated in the phase-short-circuit operating state.

[0034] In addition, in a further embodiment, it is provided that the method also includes interrupting an electrical connection to the electrical energy source in the event of irregular operation.

[0035] Thus, the advantages and special features of the steering wheel actuator device according to the invention, including its embodiments, are also implemented in the context of a steer-by-wire steering system, a motor vehicle and a method for operating a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle.

[0036] Further advantages of the present invention will become apparent from the detailed description and the figures. The invention will also be explained in more detail below in connection with the following description of exemplary embodiments with reference to the accompanying figures. They show: Fig. 1 is a schematic diagram of an example of a motor vehicle having a steer-by-wire steering system with a steering wheel actuator device according to an embodiment of the invention; Fig. 2 is a schematic representation of a first example of a steering wheel actuator device for a steer-by-wire steering system according to another embodiment of the invention; Fig. 3 is a schematic diagram of a second example of a steering wheel actuator device for a steer-by-wire steering system according to yet another embodiment of the invention; Fig. 4 is a schematic diagram of a third example of a steering wheel actuator device for a steer-by-wire steering system according to yet another embodiment of the invention; Fig. 5 a schematic representation of operating states of the servo motor device in a regular operating case of the steering wheel actuator device; Fig. 6 a schematic representation of operating states of the servomotor device in an irregular operating case of the steering wheel actuator device; and Fig. 7 is a schematic representation of an example of a method for operating a steering wheel actuator device for a steer-by-wire steering system according to another embodiment of the invention.

[0037] In the figures, the same or similar reference symbols designate the same or similar elements unless otherwise stated.

[0038] It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. It is understood that the features of the various exemplary embodiments described above and below may be combined with one another unless specifically stated otherwise. Therefore, the description is not to be construed in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0039] In Fig. 1 shows a schematic representation of an example of a motor vehicle 100 with a steer-by-wire steering system 105 having a steering wheel actuator device 110 according to an embodiment of the invention. The steering wheel actuator device 110 is connected to an axle actuator device 120 via an electrical connection 130. The electrical connection 130 enables the exchange of electrical signals and can, for example, be a direct conductive cable connection. However, an electrical connection also exists, for example, if both the steering wheel actuator device 110 and the axle actuator device 120 are connected via suitable interfaces to an on-board network of the motor vehicle 100 (e.g., CAN bus), via which the electrical signals, in particular steering commands or associated steering angle information, are transmitted.The steering wheel actuator device 110 is arranged on the steering wheel 140 of the motor vehicle in order to, on the one hand, detect the current steering wheel angle and, on the other hand, apply a servomotor torque that counteracts the driver torque applied to the steering wheel 140. The steering wheel actuator device 110 is also connected to an electrical energy source 150, which supplies it with electrical energy, at least during normal operation. In the embodiment shown, the axle actuator device 120 is also connected to the electrical energy source 150.

[0040] The axle actuator device 120 is connected to an axle 165 or the steerable, steered wheels 170, 171 of the motor vehicle 100 such that the steering angle of the wheels 170, 171 can be changed via a suitable mechanism (not shown). To operate the axle actuator device 120, it is connected to a further electrical energy source 160. In the embodiment shown, the steering wheel actuator device 110 is also connected to the further electrical energy source 150. The motor vehicle 100 also has at least one further axle 175 with two wheels 180, 181.

[0041] In Fig. 2 shows a schematic representation of a first example of a steering wheel actuator device 210 for a steer-by-wire steering system according to a further embodiment of the invention. The steering wheel actuator device 210 has a steering wheel angle detection device 211 for detecting a steering wheel angle of a steering wheel 140, as well as a servomotor device 212 for generating a servomotor torque that counteracts a driver torque applied to the steering wheel 140, and a control device 219. The steering wheel actuator device 210 is shown in Fig. 2 is connected to an electrical energy source 250. This supplies the steering wheel actuator device 210 with electrical energy during regular operation. In addition, the steering wheel actuator device 210 has an electrical energy storage device 216 that can be charged up to a limit value and is designed to supply at least the steering wheel angle detection device 211 with stored electrical energy when an irregular operating situation occurs in which the steering wheel actuator device 210 is no longer supplied with electrical energy by the electrical energy source 250. The electrical energy storage device 216 comprises Fig. 2, in particular a storage capacitor 217 and a resistor 218. In the embodiment shown, the steering wheel angle detection device is not integrated into the control device 219, but is designed to transmit steering angle information generated based on the detected steering wheel angle itself via the electrical connection 230 (e.g., interface to the CAN bus) to the axle actuator device of the steer-by-wire steering system. Therefore, in the event of irregular operation, depending on the embodiment, it may be possible to dispense with using the energy stored in the electrical energy storage device 216 to activate the control device 219, which may be, for example, an electronic control unit or another processor.

[0042] The actuator device 212 comprises an electric motor, for example a brushless DC motor, as the actuator 213, as well as a first switch assembly 214 and a second switch assembly 215 for switching the individual phases of the actuator 213. The switch assemblies 214, 215 consist of controllable semiconductor switching elements, for example, self-conducting or self-blocking field-effect transistors when uncontrolled. The control device 219 is configured to send control signals to the switch assemblies to control the operating state of the actuator device 212.Thus, in the embodiment shown, it can be provided that in the irregular operating case in which there is no supply from the electrical energy source 250, only the steering wheel angle detection device 211 is supplied by the electrical energy storage device 216, but the control device 219 remains switched off and the switch assemblies 214, 215 are not activated.In this case, the non-controlled conductive and blocking semiconductor switching elements are connected in such a way that the servo motor device 212 changes into a generator operating state in which a damping torque is generated even without control signals from the control device 219, wherein in this case it is provided that in this state electrical energy is also generated when an applied driver torque overcomes a damping torque generated in the generator operating state, so that in this state too the electrical energy storage device 216 can be charged on the basis of rotational movements of the steering wheel.

[0043] In Fig. 3 shows a schematic representation of a second example of a steering wheel actuator device 310 for a steer-by-wire steering system according to yet another embodiment of the invention. As shown in Fig. In the embodiment shown in Figure 2, the steering wheel actuator device 310 also has a steering wheel angle detection device 311 for detecting a steering wheel angle of a steering wheel 140, as well as a servomotor device 312 for generating a servomotor torque counteracting a driver torque applied to the steering wheel 140, and a control device 319. The steering wheel actuator device 310 is shown in Fig. 3 is connected to the electrical energy source 350. This supplies the steering wheel actuator device 310 with electrical energy during regular operation.

[0044] In addition, the steering wheel actuator device 310 has an electrical energy storage device 316 that can be charged up to a limit value. The electrical energy storage device 316 comprises Fig. 3, a storage capacitor 317 and a resistor 318.

[0045] The Fig. The electrical energy storage device 316 shown in Figure 3 is designed to supply the steering wheel angle detection device 311, but also the control device 319, with stored electrical energy. Since, in this embodiment, the control device 319 remains switched on even in an irregular situation, i.e., when the supply from the external electrical energy source 350, i.e., not belonging to the steering wheel actuator device but connected to it, is interrupted, the steering wheel angle detection device 311 can be simplified and is integrated into the control device 319, wherein the communication of the generated steering angle information to the axle actuator device of the steer-by-wire steering system is also carried out by the control device 319 via the electrical connection 330 (e.g., interface to the CAN bus).

[0046] The Fig. The servomotor device 312 shown in Figure 3 corresponds largely to the one shown in Fig. 2 and comprises an electric motor, for example a brushless DC motor, as the actuator 313, as well as a first switch assembly 314 and a second switch assembly 315 for switching the individual phases of the actuator 313. The switch assemblies 314, 315 consist of controllable semiconductor switching elements.

[0047] The control device 319 is configured to send control signals to the switch assemblies in order to control the operating state of the actuator motor device 312. Thus, in the embodiment shown, it can be provided that in regular, but in particular also in irregular, operating cases, the control device 319 controls the switch assemblies 314, 315 such that the actuator motor device 312 is operated in a generator operating state, i.e. that electrical energy is generated when the driver torque applied to the steering wheel by the driver overcomes the actuator motor torque, said electrical energy being at least partially stored in the electrical energy storage device 316 when its charge state is below the limit value, which corresponds, for example, to the maximum storage capacity.If the charge level of the electrical energy storage device 316 reaches the limit value during irregular operation, the actuator device 312 is configured to switch to a phase short-circuit operating state, in which rotational movements of the steering wheel are dampened. Since electrical energy is consumed in the phase short-circuit operating state, the charge level of the electrical energy storage device slowly changes back below the limit value. It may be provided to then switch back to the generator operating state and recharge the electrical energy storage device 316 until the limit value is reached again.

[0048] In Fig. 4 shows a schematic representation of a third example of a steering wheel actuator device 410 for a steer-by-wire steering system according to yet another embodiment of the invention. The embodiment shown corresponds almost entirely to that shown in Fig. 3, which is why a detailed explanation of the corresponding elements can be found in the preceding description of Fig. 3. In addition, the steering wheel actuator device 410 has a disconnecting device 420 for interrupting an electrical connection to the electrical energy source 450 in the event of irregular operation. This prevents the electrical energy storage device 416 from being discharged via the electrical energy source 450 in the event of a short circuit of the electrical energy source 450 to ground. The disconnecting device 420 is in Fig. 4 only as an example with the Fig. 3 shown embodiment of a steering wheel actuator device 310, 410. For example, the one shown in Fig. The embodiment of a steering wheel actuator device shown in Figure 2 can be correspondingly extended by a separating device for interrupting an electrical connection to the electrical energy source in the event of irregular operation.

[0049] In Fig. Figure 5 shows a schematic representation of possible operating states 500 of the servomotor device during normal operation of the steering wheel actuator device. Normal operation occurs when the steering wheel actuator device is supplied with electrical energy as intended by an external electrical energy source, i.e., one that is not part of the steering wheel actuator device but is connected to it, e.g., a vehicle battery.

[0050] In an active torque operating state 501, the actuator is actively caused by the control device to generate an actuator torque T Mto generate a torque equal to or greater than the torque T applied by the driver to the steering wheel D In this operating state, electrical energy is consumed in the actuator device. This is the case, for example, when the steering wheel actuator device simulates to the driver that one of the steered wheels of the vehicle is locked due to contact with a curb and cannot be further aligned as desired.

[0051] In a generator operating state 502, the actuator torque T M from the driver torque T applied by the driver Dovercome, i.e., exceeded. In other words, the driver turns the steering wheel in the desired direction, counter to the torque generated by the servomotor based on appropriate control of the switch assemblies of the servomotor device by the control device, which is intended to simulate the current driving or road conditions. In this state, the servomotor device generates electrical energy according to the principle of a generator, which is either consumed directly or stored in the electrical energy storage device of the steering wheel actuator device.

[0052] In a phase short-circuit operating state 503, the phases of the actuator motor are short-circuited by the semiconductor switching elements of the switch assemblies of the actuator motor device, so that the actuator motor acts as an electromagnetic brake when the driver moves the steering wheel. In this way, the steering wheel movement is dampened. It may be provided to actively activate this fault state by appropriately switching the switch assemblies, even when the electrical energy source is available. In this state, the driver torque T overcomes D the damping torque generated by the phase short circuit, ie a passive actuator torque T M* .

[0053] In Fig. 6 shows a schematic representation of operating states 600 of the servo motor device in an irregular operating case of the steering wheel actuator device.

[0054] An irregular operating condition occurs when the steering wheel actuator device is not supplied with electrical energy from an external electrical energy source as intended, but rather the external electrical energy source has failed, is switched off, or is malfunctioning. In this case, the internal electrical energy storage device should supply the steering wheel actuator device or at least a part thereof, in particular at least one steering wheel angle detection device and, if applicable, the control device, with electrical energy.

[0055] In irregular operating conditions, the active torque operating state of the actuator device is not available.

[0056] The generator operating state 602 corresponds to the generator operating state 502 in the regular operating case of the steering wheel actuator device, whereby in the irregular operating state this offers a possibility to charge the internal electrical energy storage device even if the external electrical energy source is not available.

[0057] The phase short-circuit operating state 603 corresponds to the phase short-circuit operating state 503 in regular operation. Depending on the embodiment, it may be provided to switch to the phase short-circuit operating state 603 only when the internal electrical energy storage device is fully charged to its limit, i.e., when charging cannot continue in the generator operating state 602. Alternatively, it may be provided to switch to the phase short-circuit operating state 603 beforehand, provided that the actuator device is designed to generate electrical energy even in the phase short-circuit operating state 603.

[0058] In Fig. 7 shows a schematic representation of an example of a method 700 for operating a steering wheel actuator device for a steer-by-wire steering system according to a further embodiment of the invention. The method 700 begins in a start state 701 when the steering wheel actuator device is activated. This occurs in particular when starting the motor vehicle, to whose steer-by-wire steering system the steering wheel actuator device belongs. The steering wheel actuator device has at least one steering wheel angle detection device for detecting a steering wheel angle of the steering wheel, a servo motor device for generating a driver torque T applied to the steering wheel D counteracting actuator torque T M , a control device and an electrical energy storage device that can be charged up to a limit value G.

[0059] First, a check 702 is carried out to determine whether an external electrical energy source is supplying the steering wheel actuator device with electrical energy, the checking being continued permanently during the method sequence.

[0060] If the check 702 shows that the steering wheel actuator device is not supplied with electrical energy by an external electrical energy source (in Fig. 7 with "-"), the irregular operating case is present. In the embodiment shown, an electrical connection to the electrical energy source is then first interrupted 703 by a disconnecting device for safety reasons. In the following steps, the at least one steering wheel angle detection device and the control device of the steering wheel actuator device are supplied 704 with stored electrical energy by the electrical energy storage device of the steering wheel actuator device in the irregular operating case in which the steering wheel actuator device is not supplied with electrical energy by the electrical energy source.

[0061] In a further step, a check 706 is carried out to determine whether the state of charge of the electrical energy storage device is below the limit value G. If this is the case (in Fig. 7 marked with "+"), the actuator device changes into a generator operating state and electrical energy is generated 707 by the actuator device when the driver torque T applied by the driver to the steering wheel D the actuator torque T M overcomes, ie exceeds, followed by storing 708 the electrical energy generated in the generator operating state at least partially in the electrical energy storage device if its state of charge is below the limit value G. The method then continues with supplying 704 to the steering wheel angle detection device.

[0062] If the check 706 as to whether the state of charge of the electrical energy storage device is below the limit value G shows that this is not the case (in Fig. 7 marked with "-"), the servo motor device switches 709 to a phase short-circuit operating state in the event of irregular operation. Here, too, the method then continues with the supply 704 of the steering wheel angle detection device.

[0063] If the check 702 as to whether an external electrical energy source supplies the steering wheel actuator device with electrical energy reveals that this is the case (in Fig. 7 marked with “+”), the regular operating case of the steering wheel actuator device is present.

[0064] In this case, the steering wheel actuator device is supplied 710 with at least electrical energy by an electrical energy source connected to the steering wheel actuator device.

[0065] If a check 711 determines whether a driver torque T applied by the driver to the steering wheel D greater than a servo motor torque T generated by the servo motor device Mis that this is the case (in Fig. 7 marked with “+”), a check 712 is then carried out to determine whether the state of charge of the electrical energy storage device is below the limit value G. If this is the case (in Fig. 7 marked with "+"), the actuator device changes to a generator operating state, in which a generation 713 of electrical energy by the actuator device, followed by a storage 714 of the electrical energy generated in the generator operating state at least partially in the electrical energy storage device. Furthermore, in regular operation, a storage 715 of electrical energy from the electrical energy source can take place at least partially in the electrical energy storage device if its state of charge is below the limit value G. The method then continues with the supply 710 of the steering wheel actuator device with electrical energy by the electrical energy source connected to the steering wheel actuator device.

[0066] If the check 712 as to whether the state of charge of the electrical energy storage device is below the limit value G shows that this is not the case (in Fig. 7 marked with "-"), the method also continues with supplying 710 the steering wheel actuator device with electrical energy by the electrical energy source connected to the steering wheel actuator device.

[0067] If the test 711 shows whether a driver torque T applied by the driver to the steering wheel D greater than a servo motor torque T generated by the servo motor device M is that this is not the case (in Fig. 7 marked with "-"), the actuator device switches 716 to an active torque operating state, and the method also continues with the supply 710 of the steering wheel actuator device with electrical energy via the electrical energy source connected to the steering wheel actuator device. The method ends, for example, when the steering wheel actuator device is switched off, in particular when the motor vehicle is deactivated.

[0068] In other embodiments of the method, the sequence differs. For example, in one embodiment, the generation of electrical energy can also be provided in the phase-short-circuit operating state, i.e., the actuator device switches to a phase-short-circuit operating state in the event of irregular operation and electrical energy is generated when the applied driver torque overcomes a damping torque generated in the phase-short-circuit operating state. List of reference symbols 100 motor vehicles 105 Steer-by-wire steering system 110 Steering wheel actuator device 120 Axle actuator device 130 electrical connection 140 steering wheel 150 electrical energy source 160 additional electrical energy sources 165 Axis 170 steered wheel 171 steered wheel 175 additional axle 180 unsteered wheel 181 unsteered wheel 210 Steering wheel actuator device 211 Steering wheel angle detection device 212 Actuator device 213 Actuator 214 first switch assembly 215 second switch assembly 216 electrical energy storage device 217 Storage capacitor 218 Resistance 219 Control device 230 electrical connection 250 electrical energy source 310 Steering wheel actuator device 311 Steering wheel angle detection device 312 Actuator device 313 Actuator 314 first switch assembly 315 second switch assembly 316 electrical energy storage device 317 storage capacitor 318 resistance 319 Control device 330 electrical connection 350 electrical energy source 410 Steering wheel actuator device 411 Steering wheel angle detection device 412 Actuator device 413 Actuator 414 first switch assembly 415 second switch assembly 416 electrical energy storage device 417 storage capacitor 418 Resistance 419 Control device 420 separator 430 electrical connection 450 electrical energy source 500 operating states of the actuator device in regular operation of the steering wheel actuator device 501 Active torque operating state 502 Generator operating status 503 Phase short-circuit operating state 600 Operating states of the actuator device in the irregular operation case of the steering wheel actuator device 602 Generator operating status 603 Phase short-circuit operating state 700 Method for operating a steering wheel actuator device 701 Start state 702 Check 703 Interrupt 704 Supply 705 Supply 706 Check 707 Create 708 Save 709 Change 710 Supply 711 Check 712 Check 713 Create 714 Save 715 Save 716 Change QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 100 53 335 A1

[0005] US 2002 / 0005315 A1

[0006] WO 2019 / 179859 A1

[0007] WO 2019 / 243300 A1

[0008] DE 20 2014 100 980 U1

[0009]

Claims

[1] Steering wheel actuator device (110, 210, 310, 410) for a steer-by-wire steering system (105) of a motor vehicle (100), comprising at least one steering wheel angle detection device (211, 311, 411) for detecting a steering wheel angle of a steering wheel (140); a servomotor device (212, 312, 412) for generating a servomotor torque counteracting a driver torque applied to the steering wheel (140); and a control device (219, 319, 419), wherein the steering wheel actuator device (210, 310, 410) is connectable to an electrical energy source (250, 350, 450) which supplies the steering wheel actuator device (210, 310, 410) with electrical energy at least in a regular operating case, characterized byin that the steering wheel actuator device (210, 310, 410) further comprises an electrical energy storage device (216, 316, 416) which can be charged up to a limit value and which is designed to supply at least the at least one steering wheel angle detection device (211, 311, 411) with stored electrical energy if, in an irregular operating case, the steering wheel actuator device (210, 310, 410) is not supplied with electrical energy by the electrical energy source (250, 350, 450). [2] Steering wheel actuator device according to claim 1, wherein the steering wheel actuator device (210, 310, 410) is configured such that the electrical energy storage device (216, 316, 416) also supplies at least the control device (219, 319, 419) with stored electrical energy in the irregular operating case. [3] Steering wheel actuator device according to claim 1 or claim 2, wherein the actuator motor device (212, 312, 412) is arranged to generate electrical energy when, in a generator operating state, the applied driver torque overcomes the actuator motor torque. [4] Steering wheel actuator device according to claim 3, wherein the steering wheel actuator device (210, 310, 410) is configured to store electrical energy generated in the generator operating state at least partially in the electrical energy storage device (216, 316, 416) when its state of charge is below the limit value. [5] Steering wheel actuator device according to one of the preceding claims, wherein the steering wheel actuator device (210, 310, 410) is configured to store electrical energy from the electrical energy source (250, 350, 450) at least partially in the electrical energy storage device (216, 316, 416) during regular operation if its state of charge is below the limit value. [6] Steering wheel actuator device according to one of the preceding claims, wherein the electrical energy storage device (216, 316, 416) comprises a storage capacitor, a battery or an accumulator (217, 317, 417). [7] Steering wheel actuator device according to one of the preceding claims, wherein the servo motor device (212, 312, 412) is configured to change into a phase short-circuit operating state at least in the case of irregular operation when the state of charge of the electrical energy storage device (316, 416) reaches the limit value. [8] Steering wheel actuator device according to one of claims 1 to 6, wherein the servo motor device (212, 312, 412) is configured to change to a generator operating state in the event of irregular operation and to generate electrical energy when the applied driver torque overcomes a damping torque generated in the generator operating state. [9] Steering wheel actuator device according to one of the preceding claims, wherein the steering wheel actuator device (210, 310, 410) further comprises a disconnecting device (420) for interrupting an electrical connection to the electrical energy source (250, 350, 450) at least in the case of irregular operation. [10] Steering wheel actuator device according to one of the preceding claims, wherein a storage capacity of the electrical energy storage device (216, 316, 416) is determined as a function of an average duration of inactivity phases of the steering wheel (140). [11] Steer-by-wire steering system (105) for a motor vehicle (100), comprising a steering wheel actuator device (110) according to one of claims 1 to 10; and an axle actuator device (120) electrically connected to the steering wheel actuator device (110). [12] Motor vehicle (100) with a steer-by-wire steering system (105) according to claim 11. [13] Method (700) for operating a steering wheel actuator device for a steer-by-wire steering system of a motor vehicle, wherein the steering wheel actuator device (210, 310, 410) has at least one steering wheel angle detection device (211, 311, 411) for detecting a steering wheel angle of a steering wheel (140), a servomotor device (212, 312, 412) for generating a servomotor torque counteracting a driver torque applied to the steering wheel (140), a control device (219, 319, 419) and an electrical energy storage device (216, 316, 416) that can be charged up to a limit value, wherein the method (700) comprises: Supplying (710) the steering wheel actuator device with electrical energy at least in a regular operating case by an electrical energy source connected to the steering wheel actuator device; and Supplying (704) at least the at least one steering wheel angle detection device of the steering wheel actuator device with stored electrical energy by the electrical energy storage device of the steering wheel actuator device in an irregular operating case in which the steering wheel actuator device is not supplied with electrical energy by the electrical energy source. [14] The method according to claim 13, further comprising supplying (705) also the control device of the steering wheel actuator device with stored electrical energy by the electrical energy storage device of the steering wheel actuator device in the irregular operating case in which the steering wheel actuator device is not supplied with electrical energy by the electrical energy source. [15] A method according to claim 13 or claim 14, further comprising generating (707) electrical energy by the actuator means when, in a generator operating condition, the applied driver torque overcomes the actuator torque. [16] The method of claim 15, further comprising storing (708) the electrical energy generated in the generator operating state at least partially in the electrical energy storage device when its state of charge is below the limit value. [17] Method according to one of claims 13 to 15, further comprising storing (715), in regular operation, electrical energy from the electrical energy source at least partially in the electrical energy storage device when its state of charge is below the limit value. [18] Method according to one of claims 13 to 17, further comprising changing (709) the servo motor device in the irregular operating case into a phase short-circuit operating state when the state of charge of the electrical energy storage device reaches the limit value. [19] Method according to one of claims 13 to 17, further comprising changing the servo motor device into a generator operating state in the irregular operating case and generating electrical energy when the applied driver torque overcomes a damping torque generated in the generator operating state. [20] Method according to one of claims 13 to 19, further comprising interrupting (703) an electrical connection to the electrical energy source in the event of irregular operation.

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