Steering angle sensor with improved hybrid position detection, associated arrangement and use

Abstract

Steering angle sensor (1), comprising: a encoder wheel (3) which is driven by a steering shaft (2) and rotatably mounted about an axis of rotation (D), on which at least one magnetic encoder element (8a) and at least one inductive encoder element (9a) are each fixed for synchronous rotation with the encoder wheel (3); a magnetic sensor (8b) at rest with respect to the encoder wheel (3), which is configured to generate a first position signal by interaction with the magnetic encoder element (8a), which contains a first position information of the encoder wheel (3) and an inductive sensor device (9b) at rest relative to the encoder wheel (3), which is configured to generate a second position signal by interaction with the inductive encoder element (9a); an evaluation unit (12) electrically connected to the magnetic sensor (8b) and the inductive sensor device (9b), which is trained to determine and output a corrected position signal from the first position signal and the second position signal; characterized in that the inductive sensor device (9b) is arranged between the magnetic sensor (8b) and the encoder wheel (3), that the inductive sensor device (9b) and the magnetic sensor (8b) are arranged on a common circuit board (7), one (7a) of which of two main surfaces (7a, 7b) faces the encoder wheel (3), and that the magnetic sensor (8b) is arranged on the remaining main surface (7b) facing away from the encoder wheel (3) and that the magnetic encoder element (8a) is permanent magnet and a magnetization direction (M) of the magnetic encoder element (8a) intersects a plane (E) orthogonal to the axis of rotation (D) at an angle α, where: 0° < α < 10° and the encoder wheel (3) has at least one hollow cylindrical extension (3a) for bearing support on the circuit board (7), in the cavity of which the magnetic encoder element (8a) and the inductive encoder element (9a) are accommodated.

Description

[0001] The invention relates to a steering angle sensor with improved hybrid position detection, an associated arrangement, and its use. Steering angle sensors of this type are used to determine the steering angle of steered wheels of a motor vehicle. These sensors typically incorporate a permanent magnet as a magnetic position sensor, which is driven synchronously by the steering shaft and whose position is detected by a Hall sensor. Ideally, the magnetic field direction and the Hall sensor are aligned such that the noise margin of the Hall sensor's detection signal is uniform across the adjustment range of the sensor wheel. This uniformity is adversely affected by tolerance deviations in the magnetic field direction of the magnetic position sensor from a predetermined orientation or by tolerances in the relative arrangement of the magnetic position sensor with respect to the magnetic sensor, for example, the Hall sensor.For example, play in the bearing of the encoder wheel can lead to such adverse effects. To reduce the risk of false detection, which is a significant problem, especially in autonomous driving, this magnetically based detection is regularly supplemented by another independent position detection method that ideally does not mutually influence the detection result. For example, inductive detection using an inductive position encoder and an inductive sensor device is provided, so that in addition to the magnetically detected result, another inductively detected result is provided to generate a verified detection result, which is referred to as hybrid position detection. It has been shown that the relative arrangement of the components is nevertheless crucial for the reliability of the hybrid detection.

[0002] A steering angle sensor according to the preamble of claim 1 is known from the publication by Brajon, Bruno: Bevelopment of a hybrid magneticinductive angular sensor with 360° range and stray field immunity, 2020, (URL: https: / / webthesis.biblio.polito.it / secure / 16017 / 1 / tesi.pdf accessed on 28.01.2025). Steering angle sensors of this type are also known from DE 10 2009 031 176 A1.

[0003] Against this background, there was a need for a steering angle sensor that reliably ensures position detection while simultaneously saving installation space. This problem is solved by an operating device according to claim 1. An equally advantageous use is the subject of the dependent use claim. Advantageous embodiments are the subject of the respective dependent claims. It should be noted that the features listed individually in the claims can be combined with one another in any technologically meaningful way and demonstrate further embodiments of the invention. The description, particularly in conjunction with the figures, further characterizes and specifies the invention.

[0004] The invention relates to a steering angle sensor comprising a sensor wheel rotatably mounted about a pivot axis and driven by a steering shaft. At least one magnetic sensor element and at least one inductive sensor element are fixed to the sensor wheel for synchronous rotation.

[0005] According to the invention, a magnetic sensor that is stationary with respect to the encoder wheel is provided, which is configured to generate a first position signal produced by interaction with the magnetic encoder element, which includes a first position information of the encoder wheel.

[0006] According to the invention, an inductive sensor device is further provided which is stationary relative to the encoder wheel and which is designed to generate a second position signal by interacting with the inductive encoder element.

[0007] According to the invention, an evaluation unit is provided which is electrically connected to the magnetic sensor and the inductive sensor device and which is designed to determine and output a corrected position signal from the first position signal and the second position signal.

[0008] According to the invention, the inductive sensor device is arranged between the magnetic sensor and the encoder wheel. It has been found that this arrangement results in a more uniform profile of the signal-to-noise ratio of the first position signal as plotted against the position, i.e., the position-dependent useful distance between the first position signal and the signal-to-noise ratio remains as constant as possible. For example, the profile of the first position signal plotted against the position of the encoder wheel corresponds to a Lissajous figure, which, with a strictly predetermined orientation of the magnetization direction and magnetic sensor, corresponds to a circle. However, the aforementioned tolerance deviations cause the circular Lissajous figure to deform into an ellipse. It has been found that this ellipse effect is amplified with closer proximity between the magnetic encoder element and the magnetic sensor.Therefore, in order to save installation space at the same time, a nested arrangement is proposed according to the invention in which the inductive sensor device is arranged between the encoder wheel and the magnetic sensor.

[0009] According to the invention, the inductive sensor device and the magnetic sensor are arranged on a common printed circuit board, one of whose two main surfaces faces the encoder wheel. The magnetic sensor is arranged on the remaining main surface facing away from the encoder wheel. For example, the inductive sensor device is integrated into the printed circuit board and / or arranged on the main surface of the printed circuit board facing the encoder wheel. Preferably, the inductive sensor device is integrated into the uppermost layer of a multilayer printed circuit board facing the encoder wheel and an adjacent further layer of the printed circuit board.

[0010] Preferably, the inductive encoder element and the inductive sensor device are arranged between the magnetic encoder element and the magnetic sensor.

[0011] According to the invention, the magnetic encoder element is permanent magnetic and a magnetization direction of the magnetic encoder element intersects a plane orthogonal to the axis of rotation at an angle α, where: 0° < α < 10°.

[0012] According to a preferred embodiment, the sensor device has one or more transmitter coils and one or more receiver coils.

[0013] Preferably, the inductive sensor device has a transmitter coil extending around the multiple receiving coils, wherein the multiple receiving coils are arranged with rotational symmetry. Preferably, the inductive sensor device comprises three receiving coils, each with 120° rotational symmetry and arranged rotated 30° relative to each other.

[0014] Preferably, a turn of a receiving coil is formed by several interconnected, essentially uniformly shaped partial turns arranged around a central point. Each of the partial turns extends along an individual principal direction, such that the principal directions each form an angle β ≠ 0° with each other.

[0015] Preferably, a winding of a receiving coil is formed by three interconnected partial windings, the main directions of which each form an angle β = 120° with each other and thus exhibit 120° rotational symmetry.

[0016] For example, each of the partial coils has the shape of a truncated parabola, a truncated hyperbola, a truncated ellipse, or something similar. In other words, the entire coil formed by the partial coils looks like a flower, with the individual petals being formed by the partial coils.

[0017] Preferably, the at least one transmitting coil has a diameter of more than 10 mm, preferably more than 14 mm.

[0018] Preferably, the encoder wheel is the output wheel of a spur gear drive powered by the steering shaft. For example, the spur gear drive further comprises a drive wheel arranged coaxially with the steering shaft.

[0019] Preferably, at least one engagement between two gear wheels, for example the encoder wheel and the drive wheel of the spur gear, is elastically preloaded to eliminate backlash. For example, the encoder wheel is mounted in a bearing block that is movable relative to the steering shaft and elastically preloaded in the direction of the steering shaft. The encoder wheel's mounting also includes, for example, guide ribs that guide the encoder wheel axially.

[0020] In a preferred embodiment, the axis of rotation of the encoder wheel is fixed relative to the magnetic sensor and the inductive sensor device. For example, in this embodiment, the drive wheel is movable and elastically biased against the encoder wheel.

[0021] Preferably, the magnetic sensor is a Hall sensor which has a maximum dimension lying in a plane orthogonal to the axis of rotation that is smaller than a maximum radius of the encoder wheel.

[0022] Preferably, the magnetic encoder element has a diameter of more than 5 mm, preferably more than 8 mm, and most preferably more than 10 mm.

[0023] Preferably, the magnetic encoder element is integrated into the encoder wheel by overmolding it with a thermoplastic material forming the encoder wheel.

[0024] Preferably, the inductive encoder element is made of a diamagnetic or a weakly paramagnetic material. Aluminum, for example, is considered a weakly paramagnetic material; more generally, a material with a magnetic susceptibility at room temperature of 0.62 × 10⁻⁶ × 10⁻⁶ is defined as a material with a magnetic susceptibility at room temperature of 0.62 × 10⁻⁶ × 10⁻ -9 m 3 / kg or less.

[0025] Preferably, the inductive encoder element has a rotationally symmetrical design. For example, the encoder element comprises three uniformly shaped conductive sections made of a conductive material, which are arranged offset by 120° in the circumferential direction of the encoder wheel. The conductive sections each extend over 60° of the circumferential direction and are separated by non-conductive sections. The conductive sections are preferably arranged closest to the circumferential edge of the encoder wheel, while a central area of ​​the encoder wheel is non-conductive or at least has a non-conductive coating.

[0026] According to the invention, the encoder wheel has at least one hollow cylindrical extension for bearing support, in the cavity of which at least the magnetic encoder element is received, preferably the magnetic encoder element and the inductive encoder element are arranged.

[0027] The invention further relates to an arrangement consisting of a steering shaft and a steering angle sensor in one of the embodiments described above.

[0028] The invention further relates to the use of the steering angle sensor in one of the previously described embodiments in a motor vehicle.

[0029] Other advantageous objectives, benefits and implementations of this invention will become clearer from the detailed description of a specific embodiment in conjunction with the accompanying drawing, in which: Fig. 1 shows a perspective view of an embodiment of a steering angle sensor 1 according to the invention; Fig. 2 is a detailed sectional view of the steering angle sensor 1 from figure; Fig. 3a another detailed view of the steering angle sensor 1 from Fig. 1. To explain the alignment tolerance of the magnetization direction M of the magnetic position sensor 8a; Fig. 3b a position-dependent detection result of the magnetic sensor, in particular Hall sensor, 8b of which in Fig. 1 with and without alignment deviation in the design of the steering angle sensor 1 according to the invention or in the design not according to the invention.

[0030] The invention relates to a steering angle sensor 1 comprising two encoder wheels 3, driven by a steering shaft 2 and rotatably mounted about a pivot axis D. Each encoder wheel 3 is an output wheel of a spur gear transmission 3, 4 driven by the steering shaft 2. The spur gear transmission 3, 4 further comprises a drive wheel 4 arranged coaxially with the steering shaft 2 and rotating synchronously with the steering shaft 2, being non-rotatably connected to it.

[0031] In the illustrated embodiment, the engagement between the encoder wheel 3 and the drive wheel 4 of the spur gear 3, 4 is elastically preloaded to eliminate backlash. The encoder wheel 3 is mounted in a bearing block 5, which is movably mounted relative to the steering shaft 2 and elastically preloaded in the direction of the steering shaft 2. The bearing block 5 is supported by an elastic support element 6 on a housing 10 of the steering angle sensor 1. The mounting of the encoder wheel 3 also includes guide ribs 5a, which guide the encoder wheel 3 axially. A bearing journal 11 serves to rotate the encoder wheel 3. In the illustrated embodiment, the bearing journal 11 is part of the bearing block 5, which is movably and elastically preloaded relative to the drive wheel 4.In an embodiment not shown, the axis of rotation D of the encoder wheel 3 is stationary and the drive wheel 4 is radially movable relative to the steering shaft 2 and elastically preloaded in engagement with the encoder wheel 3.

[0032] As in Fig. As can be seen in Figure 2, a magnetic, in particular permanent magnet, encoder element 8a and an inductive encoder element 9a are each fixed to the encoder wheel 3 for synchronous rotation with the encoder wheel 3. The encoder wheel 3 has a hollow cylindrical extension 3a for support mounting on the circuit board 7, in the cavity of which the magnetic encoder element 8a and the inductive encoder element 9a are arranged.

[0033] Furthermore, a magnetic sensor 8b, stationary with respect to the encoder wheel 3, is provided. This sensor is configured to generate a first position signal through interaction with the magnetic encoder element 8a, which contains initial position information for the encoder wheel 3. The magnetic sensor 8b is a Hall sensor, which in particular has a maximum dimension lying in a plane orthogonal to the axis of rotation D that is smaller than the maximum radius of the encoder wheel 3. In contrast, the magnetic encoder element 8a has a diameter of more than 5 mm, preferably more than 8 mm, and most preferably more than 10 mm. As shown, the magnetic encoder element 8a is integrated into the encoder wheel 3 by overmolding it with a thermoplastic material forming the encoder wheel 3.

[0034] Furthermore, an inductive sensor device 9b, stationary relative to the encoder wheel 3, is provided, which is configured to generate a second position signal through interaction with the inductive encoder element 9a. The inductive sensor device 9b and the magnetic sensor 8b are arranged on a common circuit board 7, one of two main surfaces 7a, 7b of which faces the encoder wheel 3. The magnetic sensor 8b is arranged on the remaining main surface 7b, which faces away from the encoder wheel 3. More precisely, the inductive sensor device 9b is integrated into the circuit board 7. The circuit board 7 is connected to the Fig. The housing 10 shown in Figure 1 is defined. The inductive sensor device 9b has one or more transmitting coils and one or more receiving coils. For example, the sensor device 9b has a transmitting coil extending around the multiple receiving coils, the multiple receiving coils being arranged with rotational symmetry. For example, the sensor device comprises three receiving coils, each having 120° rotational symmetry and arranged rotated 30° relative to each other. Preferably, the at least one transmitting coil has a diameter of more than 10 mm, more preferably more than 14 mm. The inductive sensor element 9a, on the other hand, is made of a diamagnetic material or a weakly paramagnetic material. Aluminum is considered a weakly paramagnetic material, for example; more generally, a material with a magnetic susceptibility at room temperature of 0.62 10 -9 m 3 / kg or less.

[0035] In particular, the inductive encoder element 9a has a rotationally symmetrical design. For example, the inductive encoder element 9a comprises three uniformly shaped conductive sections made of a conductive material, which are arranged offset by 120° in the circumferential direction of the encoder wheel 3. The conductive sections each extend over 60° of the circumferential direction and are each separated by non-conductive sections. The conductive sections are preferably arranged closest to the circumferential edge of the encoder wheel 3, while a central area of ​​the encoder wheel 3 is non-conductive or at least has a non-conductive coating.

[0036] Furthermore, an evaluation unit 12 is provided on the circuit board 7, which is electrically connected to the magnetic sensor 8b and the inductive sensor device 9b and is designed to determine and output a corrected position signal from the first position signal and second position signal, for example by weighted averaging or other mathematical operations from the first and second position information.

[0037] The inductive sensor device 9b is arranged between the magnetic sensor 8b and the encoder wheel 3. More precisely, the inductive encoder element 9a and the inductive sensor device 9b are arranged between the magnetic encoder element 8a and the magnetic sensor 8b.

[0038] It has been shown that by choosing this arrangement, the signal-to-noise ratio of the first position signal plotted against the position becomes more uniform, i.e., the position-dependent useful distance between the first position signal and the noise signal remains as constant as possible.

[0039] As from Fig. 3a, a magnetization direction M of the magnetic encoder element 8a intersects a plane orthogonal to the axis of rotation D at an angle α that is not equal to 0°, preferably in the range 0 to 10°, due to tolerance deviations, which affects the position-dependent interference margin of the first position signal.

[0040] How Fig.Figure 3b shows that the curve of the first position signal plotted against the position of the encoder wheel 3 corresponds to a Lissajous figure, which, with a strictly predetermined, namely radial, orientation of the magnetization direction M and magnetic sensor, corresponds to a circle I1. However, the aforementioned tolerance deviations cause the circular Lissajous figure to deform into an ellipse I2 or I3. It has been shown that this elliptical deformation effect is amplified with closer proximity between the magnetic encoder element 8a and the magnetic sensor 8b, i.e., with a design not conforming to the invention.In order to save installation space at the same time, a nested arrangement is proposed according to the invention in which the inductive sensor device 9b is arranged between encoder wheel 3 and magnetic sensor 8b, preferably the inductive encoder element 9a and the inductive sensor device 9b are arranged between the magnetic encoder element 8a and the magnetic sensor 8b.

Claims

[1] Steering angle sensor (1) comprising: a encoder wheel (3) which is driven by a steering shaft (2) and rotatably mounted about an axis of rotation (D), on which at least one magnetic encoder element (8a) and at least one inductive encoder element (9a) are each fixed for synchronous rotation with the encoder wheel (3); a magnetic sensor (8b) at rest with respect to the encoder wheel (3), which is configured to generate a first position signal by interaction with the magnetic encoder element (8a), which contains a first position information of the encoder wheel (3) and an inductive sensor device (9b) at rest relative to the encoder wheel (3), which is configured to generate a second position signal by interaction with the inductive encoder element (9a); an evaluation unit (12) electrically connected to the magnetic sensor (8b) and the inductive sensor device (9b), which is trained to determine and output a corrected position signal from the first position signal and the second position signal; characterized by , that the inductive sensor device (9b) is arranged between the magnetic sensor (8b) and the encoder wheel (3), that the inductive sensor device (9b) and the magnetic sensor (8b) are arranged on a common circuit board (7), one (7a) of which of two main surfaces (7a, 7b) faces the encoder wheel (3), and that the magnetic sensor (8b) is arranged on the remaining main surface (7b) facing away from the encoder wheel (3) and that the magnetic encoder element (8a) is permanent magnet and a magnetization direction (M) of the magnetic encoder element (8a) intersects a plane (E) orthogonal to the axis of rotation (D) at an angle α, where: 0° < α < 10° and the encoder wheel (3) has at least one hollow cylindrical extension (3a) for bearing support on the circuit board (7), in the cavity of which the magnetic encoder element (8a) and the inductive encoder element (9a) are accommodated. [2] Steering angle sensor (1) according to the preceding claim, wherein the inductive encoder element (9a) and the inductive sensor device (9b) are arranged between the magnetic encoder element (8a) and the magnetic sensor (8b). [3] Steering angle sensor (1) according to one of the preceding claims, wherein the inductive sensor device (9b) has one or more transmitter coils and one or more receiver coils. [4] Steering angle sensor (1) according to the preceding claim, wherein the inductive sensor device (9b) has a transmitter coil formed around the multiple receiving coils and the multiple receiving coils are each formed and / or arranged having rotational symmetry. [5] Steering angle sensor (1) according to one of the two preceding claims, wherein the at least one transmitting coil of the inductive sensor device (9b) has a diameter of more than 10 mm, preferably more than 14 mm. [6] Steering angle sensor (1) according to one of the preceding claims, wherein the sensor wheel (3) is the output wheel of a spur gear drive (3, 4) driven by the steering shaft (2). [7] Steering angle sensor (1) according to the preceding claim, wherein at least one engagement of two gear wheels of the spur gear transmission (3, 4) is elastically preloaded to eliminate backlash. [8] Steering angle sensor (1) according to one of the preceding claims, wherein the magnetic sensor (8b) is a Hall sensor having a maximum dimension lying in a plane (E) orthogonal to the axis of rotation (D) which is smaller than a maximum radius of the encoder wheel (3). [9] Steering angle sensor (1) according to one of the preceding claims, wherein the magnetic sensor element (8a) has a diameter of more than 5 mm, preferably more than 8 mm, most preferably more than 10 mm. [10] Steering angle sensor (1) according to one of the preceding claims, wherein the magnetic encoder element (8a) is integrated into the encoder wheel (3) by overmolding with a thermoplastic forming the encoder wheel (3). [11] Steering angle sensor (1) according to one of the preceding claims, wherein the inductive sensor element (9a) is made of a diamagnetic material or a weakly paramagnetic material. [12] Steering angle sensor (1) according to one of the preceding claims, wherein the inductive sensor element (9a) has a design having rotational symmetry. [13] Arrangement comprising a steering shaft (2) and a steering angle sensor (1) according to one of the preceding claims. [14] Use of the steering angle sensor (1) according to any one of the preceding claims 1 to 12 in a motor vehicle.

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