STEERING COLUMN WITH ELECTRIC MOTOR AND SENSOR DEVICE

Description

[0001] The invention relates to a steering column for a motor vehicle, which comprises a support unit, an actuating unit adjustably mounted on the support unit and an adjusting device with an electric motor, wherein the adjusting device is designed to adjust the actuating unit relative to the support unit.

[0002] Such steering columns are known in the prior art. These can be configured to adjust the actuating unit longitudinally and / or vertically relative to the support unit by means of the adjustment device, in particular to enable an operating position of a steering handle arranged on the steering column that is adapted to the driver. Furthermore, with regard to autonomous driving of a motor vehicle, it is known to move the actuating unit relative to the support unit from an operating position, in which a driver can steer the motor vehicle manually, to a stowed position, in which the motor vehicle is steered automatically without any steering intervention by the driver, and vice versa.In order to be able to precisely determine the position of the steering column's actuator unit, particularly with regard to optimal control of vehicle restraint systems, DE 10 2019 108 466 A1 discloses a steering column with a position detection device. The disadvantages of this device are its comparatively complex design and the high number of components.

[0003] Furthermore, US 2004 / 144192 A1 discloses a longitudinally and vertically adjustable steering column for a motor vehicle. The steering column is adjusted by means of electric motors, with the position of the steering wheel being determined via the rotations of the motor shaft. A sensor arrangement is disclosed for this purpose, in which a disk-shaped magnetic pulse generator, which rotates together with the motor shaft, interacts with a magnetic sensor to detect the position.

[0004] Furthermore, DE 198 61 266 B3 discloses a method for controlling and regulating motor-driven adjustment devices in motor vehicles. According to this method, a drive shaft can be equipped with a multipole magnet, whereby the speed of the drive shaft can be determined by Hall sensors associated with the magnetic disk.

[0005] Against this background, it is an object of the present invention to provide an improved steering column which advantageously detects the operation of the electric motor of the adjustment unit and thereby enables, among other things, a simple and cost-effective position determination, in particular with high accuracy.

[0006] To achieve this object, a steering column according to claim 1 is proposed. Further advantageous embodiments of the invention are described in the dependent claims and the description and illustrated in the figures.

[0007] The proposed solution provides a steering column for a motor vehicle, comprising a support unit, an actuating unit adjustably mounted on the support unit, and an adjusting device with one or more than one electric motor, wherein the adjusting device is designed to adjust the actuating unit relative to the support unit. The electric motor of the adjusting device has a motor shaft and a sensor device. The sensor device comprises a first sensor element and a second sensor element, each designed and arranged to detect a magnetic field that changes when the motor shaft rotates, wherein the first sensor element and the second sensor element are aligned differently with respect to the electric motor. A rotation of the motor shaft can advantageously be determined from the change in the detected magnetic field.This allows the first sensor element and the second sensor element to provide information for controlling the electric motor. Furthermore, the position of the actuating unit relative to the support unit can advantageously be determined indirectly by evaluating the first signal provided by the first sensor element and the second signal provided by the second sensor element. This is because the outermost positions that the actuating unit can assume are each a clearly defined number of revolutions of the motor shaft apart. Due to the different orientation of the first sensor element and the second sensor element, the magnetic field can advantageously be determined in a first direction and a second direction, thereby advantageously increasing the measurement accuracy. Furthermore, the direction of rotation can advantageously be reliably determined.

[0008] Advantageously, the first sensor element and the second sensor element are arranged in a common plane. The common plane is, in particular, a common geometric plane. In particular, it is provided that the first sensor element and the second sensor element are arranged on a common circuit board. This advantageously simplifies the design.

[0009] In particular, the motor shaft of the electric motor extends along a motor shaft axis, with the plane in which the first sensor element and the second sensor element are advantageously arranged being perpendicular to the motor shaft axis. This enables a particularly advantageous alignment of the sensor elements for detecting the magnetic field or the magnetic flux density.

[0010] According to a particularly advantageous embodiment of the invention, the first sensor element and the second sensor element are offset from one another by an angle within an angular range between 80° and 100°. It is particularly advantageous if the first sensor element and the second sensor element are offset from one another by an angle of 90°, in particular offset with respect to the motor shaft axis. Such an alignment is advantageous with regard to measurement accuracy. Furthermore, the alignment is advantageous with regard to determining the direction of rotation of the motor shaft.

[0011] In a further advantageous embodiment of the invention, the first sensor element is further configured to provide a first signal relating to a detected magnetic flux density. Furthermore, the second sensor element is advantageously configured to provide a second signal relating to a detected magnetic flux density. In particular, it is provided that the first sensor element and the second sensor element are integrated into a circuit that already enables processing of the provided signals, so that the first signal and the second signal can be forwarded in a processed form.

[0012] A further advantageous embodiment has a magnetic ring arranged on the motor shaft in a rotationally fixed manner, wherein the magnetic ring preferably has two poles or four poles. In particular, an alternating arrangement of the poles of the magnetic ring in the circumferential direction is provided. The poles are in particular uniformly formed. However, an asymmetrical design of the magnetic ring can also be provided, so that a complete rotation (360°) can be easily detected. The number of poles is preferably even. Even if two or four poles are advantageous, particularly for a simple structure, a magnetic ring with six or eight poles or even more poles can also be provided.

[0013] According to an advantageous development, the first sensor element and the second sensor element are aligned with respect to the associated electric motor such that the first signal from the first sensor element and the second signal from the second sensor element are offset by 90° from each other when the magnetic ring has two poles, are offset by 45° from each other when the magnetic ring has four poles, are offset by 30° from each other when the magnetic ring has six poles, and are offset by 22.5° from each other when the magnetic ring has eight poles. In this way, the measurement accuracy can be further improved.

[0014] It is further advantageously provided that the sensor device is a 2D Hall sensor, wherein the first sensor element is a first Hall element of the 2D Hall sensor and the second sensor element is a second Hall element of the 2D Hall sensor. This allows the design to be implemented in a particularly simple and cost-effective manner, in particular since only one component is used. The 2D Hall sensor can in particular also be implemented as a 3D Hall sensor, in which only two of the three Hall elements, whose doped semiconductor layers are arranged offset by 90° with respect to the motor shaft axis, are used. In particular, it is provided that the 2D Hall sensor is part of an integrated circuit, wherein the circuit advantageously already enables processing of the signals detected by the Hall elements.Advantageously, a rotating magnetic field can be detected radially and tangentially simultaneously by a single component, namely the 2D Hall sensor, due to the different orientation of the Hall elements. The space required for this component is advantageously equivalent to that of a single component and can be arranged particularly well on the circuit board in the motor. The D in 2D or 3D stands for dimensional, so 2D is synonymous with two-dimensionality and 3D is synonymous with three-dimensionality.

[0015] According to a further particularly advantageous embodiment of the invention, the steering column comprises an evaluation unit, wherein the evaluation unit is designed to evaluate signals provided by the first sensor element and the second sensor element. In particular, it is provided that the evaluation unit is designed to determine a revolution of the motor shaft from the signals provided by the first sensor element and the second sensor element. Furthermore, the evaluation unit is advantageously designed to determine a direction of rotation of the motor shaft from the signals provided by the first sensor element and the second sensor element, in particular by means of a quadrature signal. Advantageously, this makes it possible to monitor the control of the electric motor. Furthermore, the evaluation unit is advantageously designed to record the number of revolutions of the motor shaft.Furthermore, the evaluation unit is advantageously designed to determine the direction of rotation of the motor shaft using a quadrature signal. Alternatively, a sensor device is provided that is designed to directly output a direction signal. Advantageously, the combination of the first and second sensor elements is processed internally in the sensor device to directly output a direction signal. In particular, the sensor device can be a 2D Hall sensor that is designed to directly output a speed signal and a direction signal.

[0016] A further advantageous embodiment provides a signal converter configured to convert the provided signals, in particular the signals provided by the first sensor element and / or the signals provided by the second sensor element, into discrete signals, in particular binary-coded signals with low levels and high levels, prior to evaluation. This advantageously simplifies further processing of the signals.

[0017] According to a further advantageous embodiment, an interface is provided which is designed to transmit the signals from the first sensor element and the second sensor element to the evaluation unit. In particular, a 3-wire interface or a 4-wire interface is provided as the interface. With a 3-wire interface, the following pin assignment is provided in particular: 1: supply and signal in X direction, 2: signal in Y direction, 3: ground. With a 4-wire interface, the following pin assignment is provided in particular: 1: supply, 2: signal in X direction, 3: signal in Y direction, 4: ground. For the transmission of the signals, it is also provided in particular that the steering column has a bus interface, in particular using SPI (SPI: Serial Peripheral Interface), SENT (SENT: Single Edge Nibble Transmission), SPC (SPC: Short PWM Code Frames) or I2C (I2C: Inter-Integrated Circuit).In particular, a common power supply is also planned.

[0018] A further advantageous embodiment provides for the sensor device and the electric motor to be arranged in a common housing. This advantageously allows for a particularly compact design and protects the motor and sensor device.

[0019] According to another particularly advantageous embodiment of the invention, the steering column comprises a position-determining device. The position-determining device is advantageously designed to determine a position of the actuating unit relative to the support unit using the first sensor element and the second sensor element. For this purpose, the evaluation unit is advantageously assigned to the position-determining device. In particular, it is provided that the evaluation unit is included in the position-determining device.

[0020] In particular, it is provided that the electric motor is designed as a first electric motor for longitudinal adjustment of the actuating unit, and the adjusting device comprises a second electric motor for vertical adjustment of the actuating unit, wherein the sensor device is assigned to the first electric motor as a first sensor device, and a second sensor device is assigned to the second electric motor. In particular, it is provided that the first sensor device and the second sensor device have the same structure. Advantageously, the position-determining device determines the position of the actuating device relative to the support unit from a number of detected revolutions of the motor shaft and a detected direction of rotation of the motor shaft.Advantageously, this allows a high level of measurement accuracy to be achieved in a compact design, which is particularly necessary for the exact position determination of a steering handle arranged on the steering column and the precise control of vehicle restraint systems such as airbags.

[0021] Further advantageous details, features, and design details of the invention are explained in more detail in connection with the exemplary embodiments shown in the figures (Fig.: Figure). Fig. 1 shows a perspective view of an embodiment of a steering column designed according to the invention; Fig. 2 shows a further perspective view of the embodiment according to Fig. 1; Fig. 3 in a simplified schematic representation, an embodiment of a sensor unit of a steering column designed according to the invention, which is arranged to detect a changing magnetic field of a magnetic ring arranged on a motor shaft; Fig. 4 in a plan view, an embodiment of a sensor unit for a steering column designed according to the invention; and Fig. 5 in a diagrammatic representation, an exemplary profile of a sensor unit according to Fig. 3 provided first signal and second signal.

[0022] In the various figures, identical parts are generally provided with the same reference symbols and are therefore sometimes explained only in connection with one of the figures.

[0023] The Fig. 1 and Fig. 2The exemplary embodiment of a steering column 1 shown comprises a support unit 2, with which the steering column 1 can be arranged on the body of a motor vehicle. Furthermore, the steering column comprises an actuating unit 5 with an outer casing tube 3 and an inner casing tube 6, wherein the actuating unit 5 is mounted on the support unit 2 in a manner that is longitudinally and vertically adjustable. A steering shaft 7 is also mounted in the actuating unit 5 for rotation about its longitudinal axis 8.

[0024] In this exemplary embodiment, the inner casing tube 6 of the actuating unit 5 is displaceable within the outer casing tube 3 along the longitudinal axis 8 of the steering shaft 7. At the rear end of the inner casing tube 6, the inner casing tube 6 also has a retaining element 16 on which a steering handle, in particular a steering wheel, can be arranged.

[0025] Using a steering handle, a driver can convert a steering request into a rotary movement of the steering shaft 7, which is then transmitted via the Fig. 1 and Fig. 2at the front end of the steering column 1 shown universal joint and other steering shaft parts in a Fig. 1 and Fig. 2 a steering gear (not shown) is introduced. In particular, however, a steer-by-wire steering system can also be provided in which there is no mechanical coupling between the steering handle and the steerable wheels of the motor vehicle, and in which detected steering movements are transmitted as control signals to a steering actuator acting on a steering gear.

[0026] For the longitudinal and vertical adjustment of the steering column 1 relative to the support unit 2, the steering column 1 further comprises an adjustment device 12, which, in a conventional manner, comprises a first electric motor 9 and a second electric motor 10, each with a threaded rod drive, also referred to as a spindle drive, for the longitudinal and vertical adjustment. The threaded rod drive can, in particular, have a worm shaft arranged on the output of the respective electric motor 9, 10, wherein the worm shaft engages a worm gear. The worm gear is either rotationally fixed to the threaded rod (rotary spindle drive or also referred to as a rotary spindle drive) or rotationally fixed to a spindle nut (also referred to as a plunger spindle drive). Thus, by controlling the first electric motor 9, a longitudinal adjustment of the actuating unit 5 is achieved. By controlling the second electric motor 10, a height adjustment of the actuating unit 5 is achieved.In particular, it is provided that the first electric motor 9 and the second electric motor 10 have a common power supply or voltage supply.

[0027] For controlling the first electric motor 9 and the second electric motor 10, the steering column 1 in this embodiment comprises a control unit 13, which is Fig. 1 and Fig. 2 is only shown schematically. The control unit 13 can be connected to the first electric motor 9 and the second electric motor 10 for communication purposes, in particular via a communications bus, in particular a CAN bus (CAN: Controller Area Network). The control unit 13 can, in particular, be a correspondingly programmed microcontroller circuit. However, the control unit 13 can also be part of a central ECU (ECU: Electronic Control Unit) of a motor vehicle, in particular a comfort control unit.

[0028] The control unit 13 comprises a position determining device 11 with a Fig. 1 and Fig. 2not explicitly shown evaluation unit. The position determination device 11 is designed to determine a position of the actuating unit 5 relative to the support unit 2. For this purpose, the electric motors 9, 10 of the adjusting device 12 each comprise a Fig. 1 and Fig. 2 Sensor device 20 (not shown) with a first sensor element 21 and a second sensor element 22. The first sensor element 21 and the second sensor element 22 are each designed and arranged to detect a magnetic field which changes when the motor shaft of the respective electric motor 9, 10 rotates, wherein the first sensor element 21 and the second sensor element 22 are aligned differently with respect to the electric motor 9, 10 to which they are assigned.

[0029] An embodiment of the sensor device 20 and a position determination by means of the position determination device 11 using the signals 31, 32 provided by the sensor device 20 is described below with reference to Fig. 3 to Fig. 5 explained.

[0030] Fig. 3 shows a highly simplified front view of the first electric motor 9, which is only shown schematically. The design can be identical for the second electric motor 10. The first electric motor 9 comprises a motor shaft 14 and a magnetic ring 15 arranged on the motor shaft 14 in a rotationally fixed manner. In this exemplary embodiment, the magnetic ring 15 has two poles, namely a magnetic south pole as the first pole 17 and a magnetic north pole as the second pole 18.

[0031] Furthermore, the electric motor 9 comprises a printed circuit board 19 and a sensor device 20 arranged on the printed circuit board 19 of the electric motor 9, which Fig. 4is shown in more detail. In particular, it is provided that the electric motor 9 and the printed circuit board 19 with the sensor device 20 are arranged in a common housing, wherein the housing protects against external influences, for example moisture. The sensor device 20 in this exemplary embodiment is a 2D Hall sensor integrated into an IC (IC: Integrated Circuit) 24 with a plurality of contact pins 25 and has a first Hall element as a first sensor element 21 and a second Hall element as a second sensor element 22. The sensor device 20 is arranged in a stationary manner and does not rotate when the motor shaft 14 rotates. Because the printed circuit board 19 already present for the electric motor 9 is equipped with the 2D Hall sensor, almost no additional installation space is required.

[0032] The sensor elements 21, 22 of the sensor device 20 are arranged in relation to the electric motor 9 in such a way that they detect the magnetic field 40 produced by the magnetic ring 15, which Fig. 3symbolically represented by arrows, namely the magnetic flux density at the respective arrangement position. If the motor shaft 14 rotates about the motor shaft axis M and thus the magnetic ring 15 arranged thereon, the magnetic field 40 detected by the sensor elements 21, 22 or the detected magnetic flux density also changes. The first sensor element 21 and the second sensor element 22 are aligned differently with respect to the electric motor 9, namely such that a first signal 31 generated by the first sensor element 21 with respect to the detected magnetic flux density and a second signal 32 generated by the second sensor element 22 with respect to the detected magnetic flux density are shifted by 90° to one another.Due to various inaccuracies, for example with regard to the alignment of the sensor elements 21, 22 and / or a non-ideal concentricity of the motor shaft 14, certain deviations from 90° may occur in the displacement of the signals 31, 32, in particular deviations of up to 10%.

[0033] The first sensor element 21 and the second sensor element 22 are arranged in a common plane formed by the IC 24 or the circuit board 19, which extends orthogonally to a motor shaft axis M of the motor shaft 14. The doped semiconductor layer of the respective sensor element 21, 22 is aligned perpendicular to the image plane, wherein the first sensor element 21 and the second sensor element 22 are aligned offset by approximately 90° to each other, as in Fig. 4 shown.

[0034] This results in the magnetic flux density of the rotating magnetic ring 15 detected by the first sensor element 21 and the second sensor element 22 being represented as a sinusoidal signal. In this exemplary embodiment, these sinusoidal signal waveforms are converted into discrete signals 31, 32 by a signal converter included in the IC 24, which is not explicitly shown in the figures. The thus converted first signal 31 and the thus converted second signal 32 merely alternate between low level 33 and high level 34, as exemplified in Fig. 5 shown.

[0035] The converted first signal 31 of the first sensor element 21 and the converted second signal 32 of the second sensor element 22 are fed to the evaluation unit of the position-determining device 11. The evaluation unit determines one revolution of the motor shaft 14 from the first signal 31 and the second signal 32, which corresponds to one period of the respective signal 31, 32. In addition, the evaluation unit determines the direction of rotation 26 of the motor shaft 14, taking the signal offset into account. The position-determining device 11 comprises a counter that counts the revolutions of the motor shaft 14 in the respective direction of rotation and preferably a memory for storing the counter and reading it out again at a later time. The number of revolutions of the motor shaft 24 required when adjusting the actuating unit 5 from one stop to the other stop is fixed.From this, the position determination device 11 then determines the longitudinal position of the actuating unit 5 in relation to the support unit 2 based on the signals 31, 32 recorded and evaluated for the electric motor 9 for the longitudinal adjustment - and correspondingly for the height adjustment for the electric motor 10.

[0036] From the frequency of the signals 31, 32, the evaluation unit advantageously also determines the rotational speed of the motor shaft 14.

[0037] In this respect, the signals provided by the sensor device 20 and evaluated by the evaluation unit can in particular also be provided to the control unit 13 for controlling the first electric motor 9 or the second electric motor 10.

[0038] The exemplary embodiments shown in the figures and explained in connection with them serve to explain the invention and are not limiting thereof. List of reference symbols

[0039] 1Steering column 2Support unit 3Outer steering column 4Pivot axis 5Actuator 6Inner steering column 7Steering shaft 8Longitudinal axis 9First electric motor 10Second electric motor 11Positioning device 12Adjusting device 13Control unit 14Motor shaft 15Magnet ring 16Retaining element 17First pole 18Second pole 19Printed circuit board 20Sensor device 21First sensor element 22Second sensor element 24Integrated circuit 25Contact pin 26Direction of rotation of the motor shaft (14) 31First signal 32Second signal 33Low level 34High level 40Magnetic field MMotor shaft axis

Claims

1. Steering column (1) for a motor vehicle, comprising a support unit (2), an adjusting unit (5) adjustably mounted on the support unit (2), an adjusting device (12) with an electric motor (9, 10), which is designed to adjust the adjusting unit (5) relative to the support unit (2), characterized in that the electric motor (9, 10) has a motor shaft (14) and a sensor device (20), wherein the sensor device comprises a first sensor element (21) and a second sensor element (22), wherein the first sensor element (21) and the second sensor element (22) are each designed and arranged to detect a magnetic field (40) which changes when the motor shaft (14) rotates, wherein the first sensor element (21) and the second sensor element (22) are aligned differently in relation to the electric motor (9, 10).

2. Steering column (1) according to claim 1, characterized in that the first sensor element (21) and the second sensor element (22) are arranged in a common plane.

3. Steering column (1) according to claim 2, characterized in that the motor shaft (14) extends along a motor shaft axis (M), the plane being perpendicular to the motor shaft axis (M).

4. Steering column (1) according to one of the preceding claims, characterized in that the first sensor element (21) and the second sensor element (22) are aligned offset by 90° relative to one another.

5. Steering column (1) according to one of the preceding claims, characterized in that the first sensor element (21) is further designed to provide a first signal (31) relating to a detected magnetic flux density, and the second sensor element (22) is further designed to provide a second signal (32) relating to a detected magnetic flux density.

6. Steering column (1) according to one of the preceding claims, characterized in that a magnetic ring (15) is arranged non-rotatably on the motor shaft (14), the magnetic ring (15) having two poles (17, 18) or four poles.

7. Steering column (1) according to claim 5 and claim 6, characterized in that the first sensor element (21) and the second sensor element (22) are aligned with respect to the electric motor (9, 10) in such a way that the first signal (31) and the second signal (32) are displaced by 90° with respect to each other when the magnetic ring (15) has two poles (17, 18), and are displaced by 45° with respect to each other when the magnetic ring (15) has four poles.

8. Steering column (1) according to one of the preceding claims, characterized in that the sensor device (20) is a 2D Hall sensor, wherein the first sensor element (21) is a first Hall element of the 2D Hall sensor and the second sensor element (22) is a second Hall element of the 2D Hall sensor.

9. Steering column (1) according to one of the preceding claims, characterized by an evaluation unit which is designed to determine a rotation of the motor shaft (14) and a direction of rotation (26) of the motor shaft (14) from the signals (31, 32) provided by the first sensor element (21) and the second sensor element (22).

10. Steering column (1) according to claim 9, characterized in that the evaluation unit is further designed to determine the direction of rotation of the motor shaft (14) by means of a quadrature signal.

11. Steering column (1) according to claim 9 or claim 10, characterized by a signal converter which is designed to convert the signals provided into binary-coded signals with low level (33) and high level (34) before evaluation.

12. Steering column (1) according to one of claims 9 to 11, characterized by a 3-wire interface or a 4-wire interface, which is designed to transmit the signals (31, 32) of the first sensor element (21) and the second sensor element (22) to the evaluation unit.

13. Steering column according to one of the preceding claims, characterized in that the sensor device and the electric motor are arranged in a common housing.

14. Steering column (1) according to one of the preceding claims, characterized by a position determining device (11) which is designed to determine a position of the adjusting unit (5) relative to the support unit (2) using the first sensor element (21) and the second sensor element (22).

15. Steering column (1) according to one of the preceding claims, characterized in that the electric motor (9) is designed as a first electric motor for a longitudinal adjustment of the adjusting unit (5), and the adjusting device (12) comprises a second electric motor (10) for a height adjustment of the adjusting unit (5), the sensor device (20) being assigned to the first electric motor (9) as a first sensor device, and a second sensor device being assigned to the second electric motor (10).