STEER-BY-WIRE STEERING SYSTEM AND METHOD FOR THEFT PROTECTION OF A MOTOR VEHICLE WITH A STEER-BY-WIRE STEERING SYSTEM

Description

[0001] The invention relates to a steer-by-wire steering system and a method for theft protection of a motor vehicle with a steer-by-wire steering system.

[0002] From DE 10 2017 218 830 A1 a method for decelerating a servo motor of a steering device is known, in particular for protection in a maintenance operating situation and / or for theft protection, wherein the steering device comprises at least one control unit which is provided to set at least one assistance torque of the servo motor in a normal operating mode, wherein a movement of the servo motor caused by an external force is monitored by evaluating a movement characteristic correlated with the movement of the servo motor and, depending on this, a deceleration process is triggered in which the servo motor is decelerated by means of the control unit.In the operating state for performing the deceleration process, the control unit is placed in a special deceleration operating mode, in which at least one operating function of the control unit activated in the normal operating mode is deactivated and / or is inaccessible to the control unit. The steering device can also be designed as a steer-by-wire steering system.

[0003] From DE 10 2004 004 537 A1 a method for steering assistance of a motor vehicle is known, wherein during normal operation steering instructions are implemented in a corresponding steering angle of steered wheels of the motor vehicle, wherein the steering angle is actively influenced independently of the steering instructions if operation of the motor vehicle by an unauthorized operator has been detected.

[0004] From DE 10 2010 028 101 A1 a method for blocking a steering system is known which is equipped with a synchronous motor for steering assistance, wherein at least two phases of the synchronous motor are short-circuited.

[0005] A steer-by-wire steering system of this type is known from US 2020 / 269907 A1. DE 10 2013 109 527 A1 discloses a method for operating a steering system in a vehicle with an electric motor for generating a torque that assists the steering movement. This torque is adjusted as a function of a sensor-determined steering operation. To achieve a steering wheel lock, a torque opposing the steering operation is generated.

[0006] The invention is based on the technical problem of creating a steer-by-wire steering system in which theft protection is improved and of providing a suitable method.

[0007] The solution to the technical problem is provided by a steer-by-wire steering system having the features of claim 1 and a method having the features of claim 6. Further advantageous embodiments of the invention emerge from the subclaims.

[0008] The steer-by-wire steering system comprises a steering column module and a steering gear. The steering column module has at least one rotation angle sensor for detecting a steering wheel rotation angle on a steering handle, an actuator for generating a counter-torque on the steering handle, and at least one control unit. The actuator is preferably designed as an electric motor. The steering gear has at least one control unit, an actuator system for generating a rack force on a rack, and at least one sensor system for detecting or determining a rack position. The control units are connected via data communication, for example, via a bus system such as a CAN bus system.

[0009] The steering gear control unit is designed to wake up periodically and / or situationally when the motor vehicle is parked and to detect or determine a current rack position, which is then compared with a previous rack position (when the motor vehicle is parked or during the last wake-up cycle). If the rack position changes, the control unit controls the steering gear actuator so that it maintains the current rack position or another predetermined rack position with maximum rack force. Modern steering gears, for example, can apply up to 9,500 N of rack force. Here, too, the rack position is fixed or locked, making steering no longer possible. Regarding reaction times, a change in the rack position is detected, for example, 5 ms after wake-up, and locking takes place after a total of 20 ms.Thus, effective theft protection can be achieved with only minor software changes.

[0010] In one embodiment, the control unit of the steering column module is configured to wake up periodically and / or situationally (i.e., event-driven) when the motor vehicle is parked and to detect a current steering wheel angle and compare it with a previous steering wheel angle. This previous steering wheel angle is, for example, the steering wheel angle that existed when the motor vehicle was parked or was measured during the last wake-up process. If the steering wheel angle changes (previous to current), the control unit controls the actuator of the steering column module such that it maintains the current steering wheel angle or another predetermined steering wheel angle with maximum torque. If an attempt is then made to set a different steering wheel angle on the steering handle, the actuator counteracts this. The current steering wheel angle or the predetermined steering wheel angle is thus fixed or locked.The actuator can, for example, counteract a manual torque on the steering handle with up to 35 Nm, making the vehicle almost impossible to steer. The process is relatively fast. For example, a change in the steering wheel angle is detected approximately 5 ms after wake-up, with locking occurring after a total of 20 ms.

[0011] In a further embodiment, the control unit of the steering column module is configured to transmit a control command to the control unit of the steering gear to lock a rack position, and / or the control unit of the steering gear is configured to transmit a control command to the control unit of the steering column module to lock a steering wheel rotation angle. This further improves theft protection, since both actuators lock their assigned angles.

[0012] In a further embodiment, the control units are designed to communicate with each other in an encrypted manner in order to prevent or make it more difficult to manipulate the software.

[0013] In a further embodiment, the supply voltage connections of the steering column module actuator and / or the steering gear actuator are designed such that they are short-circuited without the supply voltage connector plugged in. Therefore, if an attempt is made to bypass the locking mechanism by pulling the supply voltage connector, the short circuit ensures that the actuators are extremely stiff, since each movement generates short-circuit currents whose resulting electromagnetic forces counteract the movement.

[0014] With regard to the procedural details, reference is made in full to the preceding statements.

[0015] The invention is explained in more detail below using a preferred embodiment. The sole figure shows a schematic block diagram of a steer-by-wire steering system.

[0016] The Fig. 1The steer-by-wire steering system 1 shown has a steering handle 2, a steering column module 3, and a steering gear 4 connected to a rack 5. The steering handle 2 is designed, for example, as a steering wheel and is connected to a steering column 6 in the steering column module 3. The steering column module 3 further has at least one rotation angle sensor 7, an actuator 8, and a control unit 9. The rotation angle sensor 7 and the actuator 8 are arranged on the steering column 6, with the rotation angle sensor 7 detecting a steering wheel rotation angle on the steering handle 2 and transmitting it to the control unit 9. The actuator 8 generates a counter-torque on the steering column 6, which is perceptible as a counter-torque on the steering handle 2. The actuator 8 is preferably designed as an electric motor and is also referred to as a force feedback actuator. The actuator 8 has a supply voltage connection 10 into which a supply voltage plug 11 can be inserted in order to supply the actuator 8 with a voltage U1.

[0017] The steering gear 4 has a control unit 12, an actuator 13, and a sensor system 14 for detecting or determining a rack position. The actuator 13 has two half-motors 15, 16, each of which is assigned its own power electronics 17, 18. The half-motors 15, 16 and their power electronics 17, 18 each have an independent voltage supply U1 and U2, respectively. Supply voltage connections 19, 20 are provided, into which supply voltage plugs 21, 22 can be inserted. Fig. 1are shown in the unplugged state. The two half-motors 15, 16 operate on a common rotor 23, which is connected to the rack 5 via a gear 24. Sensor system 14, designed as a rotor position sensor, is assigned to the rotor 23. Based on the signals from the rotor position sensor and the known gear ratio of the gear 24, control unit 12 can then determine the rack position. The control units 9, 12 are connected to each other via a bus system 25, with communication being encrypted.

[0018] Control unit 9 and / or control unit 12 are configured to wake up periodically and / or depending on the situation when the motor vehicle is parked. This will now be explained using control unit 9 as an example. Control unit 9 wakes up and receives the current steering wheel angle from angle sensor 7. Control unit 9 compares this current steering wheel angle with a previous steering wheel angle (e.g., the steering wheel angle when the motor vehicle was parked or the angle from the last wake-up cycle). If there is a change, control unit 9 assumes a theft attempt and controls actuator 8 so that it maintains the current steering wheel angle or another predetermined steering wheel angle. If an attempt is then made to turn the steering handle, actuator 8 counteracts this to maintain the position. Actuator 8 can, for example, apply a maximum of 35 Nm, which is almost impossible to oversteer.At the same time, control unit 9 sends a control command to control unit 12, instructing actuator 13 to lock the current rack position, i.e., to hold it in position with maximum rack force against external forces. If control unit 12 was previously asleep, it is awakened by the control command from control unit 9.

[0019] The procedure is similar if the control unit 12 is woken up periodically and / or situationally.

[0020] As a further protective measure, the supply voltage connections 10, 19, 20 of the actuators 8, 13 are designed in such a way that they are short-circuited without the supply voltage plug 11, 21, 22 being plugged in. List of reference symbols

[0021] 1Steer-by-wire steering system 2Steering handle 3Steering column module 4Steering gear 5Rail 6Steering column 7Angle sensor 8Actuator 9Control unit 10Supply voltage connection 11Supply voltage connector 12Control unit 13Actuator 14Sensors 15, 16Half motor 17, 18Power electronics 19, 20Supply voltage connection 21, 22Supply voltage connector 23Rotor 24Gearbox 25Bus system

Claims

1. Steer-by-wire steering system (1), comprising a steering column module (3) and a steering mechanism (4), the steering column module (3) having at least one rotational angle sensor (7) for detecting a steering wheel rotational angle on a steering handle (2), an actuator (8) for generating a counter torque on the steering handle (2) and at least one control unit (9), and the steering mechanism (4) having at least one control unit (12), an actuator (13) for generating a rack force on a rack (5) and at least one sensor system (14) for detecting or determining a rack position, the control units (9, 12) being connected for data transmission, characterized in that the control unit (12) of the steering mechanism (4) is designed such that it wakes up periodically and / or situationally in the parked state and detects or determines a current rack position, wherein, in the case of a change in the rack position, the control unit (12) controls the actuator (13) of the steering mechanism (4) such that the actuator maintains the current rack position or a different predetermined rack position with maximum rack force.

2. Steer-by-wire steering system according to claim 1, characterized in that the control unit (9) of the steering column module (3) is designed such that it wakes up periodically and / or situationally in the parked state and detects a current steering wheel rotational angle, wherein, in the case of a change in the steering wheel rotational angle, the control unit (9) controls the actuator (8) of the steering column module (3) such that the actuator maintains the current steering wheel rotational angle or a different predetermined steering wheel rotational angle with maximum torque.

3. Steer-by-wire steering system according to claim 1 or claim 2, characterized in that the control unit (9) of the steering column module (3) is designed such that it transmits a control command to the control unit (12) of the steering mechanism (4) in order to lock a rack position and / or the control unit (12) of the steering mechanism (4) is designed such that it transmits a control command to the control unit (9) of the steering column module (3) in order to lock a steering wheel rotational angle.

4. Steer-by-wire steering system according to claim 3, characterized in that the control units (9, 12) are designed such that they communicate with one another in an encrypted manner.

5. Steer-by-wire steering system according to any of the preceding claims, characterized in that supply voltage connections (10, 19, 20) of the actuator (8) of the steering column module (3) and / or of the actuator (13) of the steering mechanism (4) are designed such that they are short-circuited without a plugged-in supply voltage plug (11, 21, 22).

6. Method for theft protection for a motor vehicle comprising a steer-by-wire steering system (1), the steer-by-wire steering system (1) comprising a steering column module (3) and a steering mechanism (4), the steering column module (3) having at least one rotational angle sensor (7) for detecting a steering wheel rotational angle on a steering handle (2), an actuator (8) for generating a counter torque on the steering handle (2) and at least one control unit (9), and the steering mechanism (4) having at least one control unit (12), an actuator system (13) for generating a rack force on a rack and at least one sensor system (14) for detecting or determining a rack position, the control units (9, 12) being connected for data transmission, characterized in that the control unit (12) of the steering mechanism (4) wakes up periodically and / or situationally when the motor vehicle is in the parked state and detects or determines a current rack position by means of the sensor system (14) and compares the current rack position with a previous rack position, wherein, in the case of a change in the rack position, the control unit (12) controls the actuator (13) of the steering mechanism (4) such that the actuator maintains the current rack position or a different predetermined rack position with maximum rack force.

7. Method according to claim 6, characterized in that the control unit (9) of the steering column module (3) wakes up periodically and / or situationally when the motor vehicle is in the parked state and detects a current steering wheel rotational angle of the rotational angle sensor (7) and compares the current rotational angle with a previous steering wheel rotational angle, wherein, in the case of a change in the steering wheel rotational angle, the control unit (9) controls the actuator (8) of the steering column module (3) such that the actuator maintains the current steering wheel notional angle or a different predetermined steering wheel rotational angle with maximum torque.

8. Method according to claim 6 or claim 7, characterized in that the control unit (9) of the steering column module (3) transmits a control command to the control unit (12) of the steering mechanism (4) in order to lock a rack position and / or the control unit (12) of the steering mechanism (4) transmits a control command to the control unit (9) of the steering column module (3) in order to lock a steering wheel rotational angle.

9. Method according to claim 8, characterized in that the control units (9, 12) communicate with one another in an encrypted manner.

10. Method according to any of claims 6 to 9, characterized in that by removing a supply voltage plug (11, 21, 22) from a supply voltage connection (10, 19, 20) of the actuator (8) of the steering column module (3) and / or the actuator (13) of the steering mechanism (4), the supply voltage connections (01, 19, 20) are automatically short-circuited.