POSITION DETECTION FOR A ROTATING ANGLE SENSOR

Description

[0001] The present invention relates to a position detection device for a rotary angle sensor, a rotary angle sensor with such a position detection device and a system with such a rotary angle sensor.

[0002] Rotary angle sensors are used, for example, in motor vehicles. In motor vehicles, electric power steering systems are increasingly used. These systems require steering torque for control. The steering torque is detected in a steering column by a torsion bar as differential angles, and these are calculated from the data. More precisely, rotations at the ends of the torsion bar are determined by rotary angle sensors, and differential angles are derived from these. The differential angles caused by the torsion must be determined independently of the steering wheel position. In modern electric power steering systems, these sensors also serve as a human-machine interface. HMITorque sensors are used in what is called a human-machine interface (HMI). These sensors measure the force the driver applies to the steering wheel, enabling power steering assistance. Even in the future, with the elimination of the steering column and the establishment of steer-by-wire systems, sensors for steering angle and, if applicable, steering torque will still be necessary at the steering drive unit or the handwheel sensor and actuator.

[0003] Furthermore, it is important for driver assistance systems such as ESP (Electronic Stability Program for the vehicle's handling) to know the position (relative angular position) of the steering wheel. For this purpose, the steering angle (angle relative to a reference position) is determined. To ensure that angles greater or less than 360° can also be determined, the reference position is assigned an index.

[0004] For magnetic torque sensors, it is known, for example, to generate a signal for each complete rotation of the steering wheel for indexing purposes using a Hall sensor and an associated magnet, thus determining the number of rotations. This employs a method often referred to as magnetic louvers, in which the magnetic flux density changes during rotation. Such sensors are also called Torque Only Sensors (TOS). These sensors are not capable of detecting a steering angle. Examples of such torque sensors are described in EP 1 269 133 B1 and US 7,644,635 B2.

[0005] Devices of this kind for determining the angle of rotation and / or the torque of a rotating part, as well as methods for their operation, are already known in numerous embodiments from the prior art. In general, sensors are known that measure both the torque at the steering wheel and the steering angle.

[0006] From DE 10 2004 019 379 A1, a method for determining a difference angle is known in which two rotation angles are determined and a difference angle is calculated from them. When calculating the difference angle, different transmission ratios between the rotations of two components are taken into account. A large number of rotations remains unconsidered.

[0007] From EP 2 383 558 A1, an inductive angle sensor for determining torque and relative angular position with respect to a reference position is known, comprising means for detecting angles and differential angles as well as means for indexing when passing through the reference position with a permanent magnet and a Hall sensor. To create a cost-effective and compact torque sensor with angle determination and indexing, a flux guide plate is assigned to the Hall sensor, which directs the flux of the permanent magnet to the Hall sensor in the reference position.

[0008] From WO2019 / 185338 A1, a device for determining the angle of rotation and / or the torque of a rotating part is known. The device comprises at least one angle sensing means for detecting the angular position of the rotating part relative to a reference position and at least one indexing means for indexing at a predetermined rotation, preferably a 360° rotation, of the rotating part relative to the reference position. The angle sensing means has a rotor non-rotatably connected to the rotating part, with a base body for attachment to the rotating part and several vanes extending radially outwards from the base body. At least one of the vanes of the rotor has a marking detectable by the indexing means.

[0009] Using such indexing systems, it is possible to forgo an absolute determination of the steering angle across the measuring range of typically 1440°. Instead, the indexing system adds a type of contactless switch that generates a switching signal (index signal) when the vehicle is driving straight ahead. Previous versions of the index switch are magnetic, requiring an additional magnet and an additional integrated circuit. They are not very robust with regard to interference from external fields.

[0010] A non-contact position sensor is known from DE 10 2008 057 416 A1. The position sensor comprises a position transducer with sensor conductor structures and a position encoder with encoder structures. The encoder structures are arranged along a motion path and exhibit varying conductivity.

[0011] From US 2010 033 064 A1 is a "Rotation detector and direct-current motor"The document discloses a power supply that superimposes a DC voltage with an AC voltage and applies this to a motor. When the motor is rotated, a current flows that contains an AC component. The motor contains a capacitor connected in parallel to a phase coil. Due to the capacitor, the impedance of the motor circuit between the brushes changes depending on the motor's rotation. A signal processing unit extracts an AC component from the motor current whose amplitude corresponds to the angular momentum. A rotation angle detection unit detects the motor's angle of rotation based on the angular momentum.

[0012] From "Simulation and Robustness Analyses for a Novel Capacitive / Magnetic Full-Turn Absolute Angular Position Sensor", Brandstatter et al., IEEE Transactions on Instrumentation and Measurement, IEEE, USA, Vol. 54, No. 1, February 1, 2005, pages 436-441, is a simulation and measurements for the design of a "capacitive / magnetic sensor with full circle range" known.

[0013] From DE 10 2018 204 901 a sensor device for detecting position information of a rotor of an electric motor is known.

[0014] In light of this, there is a need for improved technology for indexing and / or determining rotation angles. For this purpose, a position detection device for a rotation angle sensor according to claim 1 or 2, a rotation angle sensor according to claim 12 with such a position detection device, and a system according to claim 14 with such a rotation angle sensor are specified. Specific embodiments of the position detection device are described in dependent claims 3 to 11.

[0015] A specific embodiment of the rotary angle sensor is described in dependent claim 13. According to a first aspect of the invention, a position detection device for a rotary angle sensor is provided. The position detection device comprises at least one stator, at least one rotor, and at least one evaluation unit. The at least one rotor has a base body and at least one rotor blade extending radially outward from the base body. A first dielectric with a first relative permittivity (hereinafter referred to as the first permittivity) is present between at least one of the at least one rotor blades and the at least one stator.A second dielectric with a second relative permittivity (hereinafter referred to as the second permittivity) is present between at least one second rotor blade or at least one free space adjacent to the at least one first rotor blade in the circumferential direction of the rotor and the at least one stator. In other words, the second dielectric is present between the at least one second rotor blade and the at least one stator, or between the at least one free space adjacent to the at least one first rotor blade in the circumferential direction of the rotor and the at least one stator. The first permittivity and the second permittivity are different from each other. The evaluation unit is configured to detect when the at least one first rotor blade reaches, has reached, or exceeds a predetermined rotational position, for example, starting from a reference position.

[0016] The at least one stator can be arranged in a fixed position relative to a rotating element. The at least one rotor can be connected to the rotating element in a rotationally fixed manner.

[0017] The evaluation unit can be configured to detect, based on a capacitive coupling between the at least one rotor and the at least one stator, when the at least one first rotor blade, starting from a reference position, reaches, has reached, or exceeds a predetermined rotational position. According to one embodiment, the evaluation unit is configured not to determine the exact rotational angle of the at least one rotor blade using the capacitive coupling, but rather to detect when the at least one first rotor blade, starting from a reference position, reaches, has reached, or exceeds the predetermined rotational position. The predetermined rotational position can, for example, be a single fixed position relative to the circumference of the stator and / or the rotor. For example, the predetermined rotational position can correspond to the reference position.According to this example, the predetermined rotational position can be reached again after each complete revolution of at least one rotor blade. According to another example, the predetermined rotational position can correspond to a segment of the rotational angle. This segment can be less than 360°.

[0018] It can therefore be said that the position detection device operates capacitively according to the first aspect. The at least one rotor acts as at least one electrode, and the at least one stator acts as a corresponding electrode. The at least one rotor and the at least one stator can be at different potentials. This can lead to the formation of an electric field between the at least one rotor and the at least one stator. The strength of the electric field depends on various parameters. Among other things, the strength of the electric field between the at least one rotor and the at least one stator depends on the material located between them. This material acts as a dielectric.The higher the permittivity of the material acting as a dielectric, the lower the electric field strength of the resulting electric field. Conversely, the lower the permittivity of the material acting as a dielectric, the higher the electric field strength of the resulting electric field.

[0019] The capacitive design of the position detection device is advantageous. Due to the increasing demands of electromobility, the requirements for EMC (electromagnetic compatibility) limits in low-frequency magnetic fields are also rising. Particularly with the high currents of the electric motors in an electric vehicle's traction drive, such very strong magnetic fields are generated. Inductive solutions are susceptible to EMC interference. The capacitive solution proposed here offers improved robustness against magnetic fields as well as a simpler and therefore more cost-effective solution.

[0020] Due to the different permittivities of the first and second dielectrics, the at least one first rotor blade can be distinguished from the at least one second rotor blade and / or the at least one free space. According to one possible embodiment, it is conceivable that, for example, only a single first rotor blade exists. This single first rotor blade can be distinguished from the other rotor blades of the at least one rotor or from the at least one free space. The evaluation unit can, for example, determine when the single first rotor blade, starting from the reference position, reaches, has reached, or exceeds a predetermined rotational position. The predetermined rotational position can be identical for each rotation. According to one example, there can be a single predetermined rotational position for each complete revolution.The evaluation unit can, for example, determine when the single first rotor blade has rotated by a predetermined angle, e.g., a full 360° turn, to the predetermined rotational position. In this way, a full rotation of the single first rotor blade (i.e., a 360° turn) can be determined. According to another example, there can be multiple predetermined rotational positions per full rotation. The evaluation unit can, for example, determine when the single first rotor blade has rotated by a predetermined angle, e.g., a 40° segment, to the predetermined rotational position. In this way, a rotation of the single first rotor blade by a specific 40° segment (e.g., a 40° turn) can be determined.

[0021] The evaluation unit can be configured to generate a switching signal when the first rotor blade reaches, has reached, or exceeds the predetermined rotational position. The evaluation unit can also be configured to generate a switching signal when it detects that the first rotor blade reaches, has reached, or exceeds the predetermined rotational position. This switching signal can be a logical signal that can be transmitted via an electronic digital interface along with other sensor or diagnostic data. Each time a switching signal is generated, a counter can be incremented or decremented, for example, by 1, depending on the direction. This allows for a type of indexing. Such indexing eliminates the need for an absolute determination of the steering angle across the measuring range, typically 1440°, using angle sensors and gear reductions.Rather, indexing adds a type of contactless switch or counter that generates a switching signal (index signal) when, for example, the vehicle is driving straight ahead and / or when a predetermined rotational position is reached. The position detection device can therefore also be considered a type of switch and, for example, referred to as a switch. If an angle sensor on the steering system uniquely detects a steering angle sub-range, the direction-dependent switching signal can be used to count the steering angle sub-ranges. The counter value is then multiplied by the steering angle sub-range and added to obtain a unique derivation of the angle within the steering angle sub-range to achieve a total measuring range. For a selectable configuration, for example, a sub-range is defined by the number of rotor blades (e.g., 9), resulting in a steering angle sub-range to be uniquely measured of 360° / 9 = 40°.

[0022] Previous versions of such an index switch are magnetic, requiring an additional magnet and an additional integrated circuit. The capacitive solution presented here is more robust with regard to interference from external fields.

[0023] For example, the counter can be incremented or decremented by 1 each time the first rotor blade reaches, has reached, or exceeds a predetermined rotation angle segment (i.e., the predetermined rotation position). This allows the reaching or exceeding of specific rotation angle segments, e.g., 40°, to be counted. The rotation angle can then be derived from the counter reading without having to determine the angle itself. If the angle segment is 40°, meaning the counter is incremented or decremented each time a 40° rotation angle segment is reached, then a rotation angle of 4 * 40° = 160° can be derived from a counter reading of 4 in a given direction.

[0024] For example, an index switch can be implemented using the evaluation unit, the evaluation unit can be arranged within such an index switch, or the rotary angle sensor can be implemented as such an index switch. The index switch can be positioned, for instance, when the steering is in a straight-ahead position. It can be assumed that roads typically alternate between right and left turns. Once straight-ahead driving has been identified and validated as the index point, the readings of the motor position sensor for commutation of that motor, or the sweeping of specific angular segments (e.g., 40° segments) of a rotary angle sensor, can be counted.

[0025] With conventional torque sensors using magnetic louvers, as described above, the steering angle is not detected at the magnetic louver. Counting angle segments / partial angles after indexing is therefore not possible. Consequently, an index switch and a counter would seem unnecessary. However, an index switch and a corresponding counter are advantageous in this context because another position sensor is implemented on the power steering motor for controlling and commutation. Due to the steering gear ratio of approximately 20-30, the sensor signal repeats quite frequently, but can be counted after indexing. In this way, an angle sensor value for the steering angle can be (indirectly, so to speak) deduced.

[0026] The at least one rotor can be made of a metal. For example, the base body and / or the at least one rotor blade of the at least one rotor can be made of a metal. According to a first conceivable embodiment, the rotor body and / or the at least one rotor blade of the at least one rotor can be made of metal.

[0027] The first dielectric can be made of a plastic or be designed as a plastic. The first dielectric can, for example, cover at least almost completely or even partially cover the at least one first rotor blade. The first dielectric can, for example, be attached to, arranged on, or connected to the at least one first rotor blade. The second dielectric can be made of a plastic or be designed as a plastic. The second dielectric can, for example, cover at least almost completely or even partially cover the at least one second rotor blade. The second dielectric can, for example, be attached to, arranged on, or connected to the at least one second rotor blade. Alternatively, the second dielectric can be made of air or be designed as air. For example, at least one free space can be formed in this way.Regardless of the precise composition of the second dielectric, its permittivity will differ from that of the first dielectric. For example, the permittivity of the first dielectric can be higher than that of the second. This can be achieved, for instance, by using a plastic with a higher permittivity for the first dielectric than for the second. Alternatively, if air is used as the second dielectric, this can be achieved by using a plastic with a higher permittivity than air for the first dielectric.

[0028] The at least one rotor can each have a rotor carrier. The rotor carrier can be designed to support the rotor's base body. The rotor carrier can be made of a plastic. For example, the rotor carrier can be formed from a plastic, i.e., consist of a plastic. According to a conceivable embodiment, the rotor carrier can be a multi-component plastic part. For example, the rotor carrier can be formed from a multi-component plastic part, i.e., consist of a multi-component plastic part.

[0029] For example, the at least one rotor carrier, whether designed as a multi-component plastic part or comprising a multi-component plastic part, can have several sections or sectors, each containing a different plastic. These sections or sectors can form the first dielectric and / or the second dielectric. Alternatively, the multi-component plastic part can be a two-component plastic part or be designed as a two-component plastic part. The two-component plastic part can have two sections or sectors, each containing a different plastic. These two sections or sectors can form the first dielectric and / or the second dielectric. Accordingly, the first dielectric can be a single plastic or be designed as a single plastic. The first dielectric can, for example, cover at least almost completely the at least one first rotor blade.The first dielectric can, for example, be attached to, arranged on, or connected to the at least one first rotor blade, or it can be part of the at least one first rotor blade or integrated into it. The second dielectric can be made of a plastic or be designed as a plastic. The second dielectric can, for example, cover the at least one second rotor blade at least almost completely. Regardless of the exact design of the second dielectric, its permittivity differs from that of the first dielectric.For example, the permittivity of the first dielectric can be higher than the permittivity of the second dielectric. This can be achieved, for instance, by using a plastic with a higher permittivity for the first dielectric than for the second dielectric. For example, a section or sector forming the first dielectric can be made of, or consist of, a plastic with a higher permittivity than the plastic present in, or consisting of, the section or sector forming the second dielectric.

[0030] The rotor carrier can, for example, have at least one first circular sector-shaped section. This first circular sector-shaped section can have a first radius and form the first dielectric. The rotor carrier can have at least one second circular sector-shaped section. This second circular sector-shaped section can extend coaxially to the first circular sector-shaped section. This second circular sector-shaped section can have a second radius and form the second dielectric. The second radius can be smaller than the first radius. Due to the smaller second radius, circular sector-shaped recesses or cutouts are formed in the radially extended second circular sector-shaped section.

[0031] In other words, the rotor can have a rotor carrier. The rotor carrier can have sectors that form the first dielectric. Additionally or alternatively, the rotor carrier can have sectors or recesses that form the second dielectric. The rotor carrier can be configured such that it has at least one first sector or section and at least one second sector or section. The at least one first sector or section can be circular sector-shaped with a first radius. The at least one second sector or section can also be circular sector-shaped with a second radius. The first radius can be larger than the second radius. The at least one first sector or section can be configured such that it is in alignment with, or covers, or overlaps the at least one first rotor blade.This allows at least one sector or section to be located between the at least one first rotor blade and the stator. In other words, this allows a plastic to be located as the first dielectric between the at least one first rotor blade and the stator. The at least one second sector or section can be configured such that it has at least one recess that is aligned with the at least one second rotor blade. This allows at least one recess to be located between the at least one second rotor blade and the stator. In other words, this allows air to be located as the second dielectric between the at least one second rotor blade and the stator. For example, this can form at least one free space. Alternatively, the at least one second sector or section can be configured such that it is aligned with or covers the at least one second rotor blade.This allows at least one second sector to be located between the at least one second rotor blade and the stator. In other words, this allows a plastic to be used as a second dielectric between the at least one second rotor blade and the stator.

[0032] A third dielectric with a third permittivity can be present between at least one third of the at least one rotor blade and the at least one stator. Further dielectrics can also be provided between the remaining rotor blades and the stator. In principle, as many different dielectrics can be provided as there are rotor blades and / or free spaces. In other words, the number of different dielectrics can range from two up to the number of rotor blades, for example, plus at least one dielectric for any free spaces.

[0033] The rotating element (which can also be referred to as the rotary element) can have a torsion bar or be designed as a torsion bar. The at least one stator and / or the evaluation unit can be arranged on a printed circuit board. The rotating element can extend through the printed circuit board and the at least one rotor.

[0034] According to a second aspect, a rotary angle sensor is provided. The rotary angle sensor includes the position detection device as described herein. The rotary angle sensor further includes a rotary angle determination device. The rotary angle determination device includes at least one stator, at least one rotor, and the evaluation unit. The evaluation unit is configured to determine, starting from the reference position, a rotary angle of the at least one rotor relative to the at least one stator.

[0035] According to the second aspect, the position detection device according to the first aspect can be combined with a rotation angle detection device. For example, a capacitively operating index switch can be combined with an inductively operating rotation angle detection device.

[0036] The evaluation unit can be configured to determine the rotation angle of the at least one rotor based on inductive coupling between the at least one rotor and the at least one stator. The evaluation unit can, for example, determine the rotation angle of the at least one rotor up to a partial or complete revolution as an intermediate result. Furthermore, the evaluation unit can be configured to determine the value of the counter described above. The counter value can indicate the number of partial or complete revolutions of the at least one rotor blade. From the intermediate result (for example, the rotation angle up to 360°) and the counter value, the evaluation unit can determine the total rotation of the rotor. The partial rotation angle can, for example, be an angular segment. According to one example, each exceedance of a respective angular segment, i.e.,Segment crossings are counted. The angle segment can be, for example, 20° or 40°. In this case, the counter is incremented or decremented each time the angle segment is reached or exceeded, depending on the direction of the crossing. Specifically, the angle signal can repeat at specific intervals, for example, 20° or 40°, and in this way, a steering angle of, for example, 1440° can be calculated.

[0037] In one embodiment, the at least one rotor can be configured as two rotors. The evaluation unit can be configured to determine the rotation angle of a first rotor and the rotation angle of a second rotor. The evaluation unit can be configured to determine the total rotation of the first rotor from the determined rotation angle (up to one complete revolution) and the counter value. The evaluation unit can be configured to determine the total rotation of the second rotor from the determined rotation angle (up to one complete revolution) and the counter value. The first rotor can be arranged at one end of the rotating element. The second rotor can be arranged at the other end of the rotating element.The evaluation unit can be configured to derive the torque acting on the rotating element from the angle of rotation or the total rotation of the first rotor and the angle of rotation or the total rotation of the second rotor. For example, the evaluation unit can be configured to determine a difference angle between the angle of rotation or the total rotation of the first rotor and the angle of rotation or the total rotation of the second rotor. From this difference angle, the evaluation unit can derive the torque acting on the rotating element.

[0038] According to a third aspect of the invention, a system is proposed. The system comprises a rotary angle sensor as described herein. The system further comprises a rotating element. The at least one stator of the rotary angle sensor is arranged in a fixed position relative to the rotating element. The at least one rotor is non-rotatably connected to the rotating element. The evaluation unit of the rotary angle sensor is configured to determine a torque acting on the rotating element from the measured rotary angle or the total rotation of the at least one rotor. The rotating element may have a torsion bar or be configured as a torsion bar.

[0039] The evaluation unit can be configured to determine the torque acting on the rotating element from the measured angle of rotation or the total rotation of the at least one rotor. For example, the evaluation unit can be configured to derive the torque acting on the rotating element from the measured angle of rotation or the total rotation of the at least one rotor.

[0040] The described rotary angle sensor and system can be implemented wholly or partially by means of a computer program. A computer program product may include code snippets for executing the procedure. The computer program may be stored on a computer-readable storage medium or within the rotary angle sensor and / or the system, for example, in the evaluation unit. When the code snippets of the computer program are loaded into, or run on, a computer or processor (for example, a microprocessor, microcontroller, digital signal processor (DSP), or digital hard-wired logic in an ASIC), they can cause the computer or processor to execute one or more steps, or all steps, of the technique described herein.

[0041] Although some of the aspects and details described above have been described in relation to the rotary angle sensor, these aspects can also be implemented in a corresponding way in the system with the rotary angle sensor or a computer program supporting the rotary angle sensor.

[0042] The present invention will be further explained with reference to figures. These figures schematically illustrate: Figure 1 is an exploded view of an inductive torque sensor from the prior art; Figure 2 is a schematic representation of a multilayer printed circuit board; Figure 3a is a view of a rotor according to an exemplary embodiment; Figure 3b is a further view of the rotor according to the exemplary embodiment from Figure 3a ; and Figure 3 shows another view of the rotor according to the embodiment shown in Figures 3a and 3b .

[0043] Specific details are set forth below, without limitation, to provide a complete understanding of the present invention. However, it is clear to a person skilled in the art that the present invention can be used in other embodiments which may differ from the details set forth below.

[0044] It is also clear to those skilled in the art that the explanations set forth below can be implemented using hardware circuits, software, or a combination thereof. The software may be related to programmed microprocessors or a general-purpose computer, an ASIC (Application-Specific Integrated Circuit), and / or DSPs (Digital Signal Processors). It is also clear that even if the following details are described in relation to a method, these details may also be implemented in a suitable device unit, a computer processor, or memory connected to a processor, the memory containing one or more programs that carry out the method when executed by the processor.

[0045] Figure 1Figure 1 shows an inductive torque sensor known from the prior art. The inductive torque sensor comprises a printed circuit board 1 and two rotor disks 2 (or, in short, two rotors 2), wherein the rotor disks 2 have different rotor structures 3 with structure sizes of, for example, 20° and 40°. The rotor disks 2 are arranged largely parallel and on a common shaft, which here is formed by a torsion bar. This torsion bar is part of a steering shaft. The rotor disks 2 are distributed at a short distance from both main surfaces of the printed circuit board 1. The printed circuit board 1 and a first of the rotor disks 2a are largely enclosed by a housing 5. A second of the rotor disks 2b is mounted on the outside of the housing 5 with a minimal clearance. The rotor disks 2, the printed circuit board 1, and the housing 5 each have an opening for the torsion bar. The openings are aligned accordingly.

[0046] Each rotor disk 2 is rotationally fixed to the torsion bar by means of a support structure 6, the torsion bar having a torsion element between the rotor disks 2. The one-piece support structure 6 comprises a tube-like section whose inner diameter corresponds to the diameter of an associated section of the torsion bar plus a predetermined small clearance, and to which the corresponding rotor disk 2a, 2b is attached. A disk 12 is attached externally to the support structure 6 of the first rotor disk 2a, which is arranged in the housing 5, and rests tightly against the housing 5. In this way, the torque sensor is stabilized against tilting, thereby minimizing related measurement errors.

[0047] Four stators are formed on the circuit board 1, which, in conjunction with the two rotors 2, form four angle sensors. The stators, together with the necessary excitation structures, are applied and contacted as conductive traces on the two main surfaces of the circuit board 1 in a known manner. The structures of the stators are matched to the structures of the rotor disks 2a and 2b.

[0048] At least one application-specific integrated circuit (ASIC) 7 is arranged on the circuit board 1. Each ASIC 7 has at least two channels. Optionally, at least one evaluation unit is connected downstream of the ASIC 7. The ASIC 7 and, optionally, the at least one evaluation unit constitute the means for evaluation.

[0049] For electrical connection to, for example, a control unit and, if necessary, to the evaluation unit, a socket 13 with corresponding contact pins is attached to the circuit board.

[0050] During operation, the rotors 2 are rotated relative to the stators by means of the torsion bar. This transmits corresponding signals to the channels of circuit 7, which are then calculated as rotation angles starting from a defined zero position. Depending on the torque applied to the steering column via a steering wheel, the torsion bar twists by a specific angle, causing the two rotors 2 to rotate by correspondingly different angles.

[0051] From these different rotation angles, a difference angle is calculated, from which the torque exerted on the steering rod is determined.

[0052] Furthermore, a number of complete rotations of the torsion bar can be determined using a Hall sensor 8, a permanent magnet 10, and a flux guide plate 9: As soon as the torsion bar is rotated axially and the permanent magnet 10 passes through the reference position, the magnetic flux is guided through the flux guide plate 9 to the Hall sensor 8, which then emits a switching signal that is counted. Depending on the direction of rotation of the torsion bar, the number 1 is added or subtracted for each switching signal; from the sum in conjunction with the signal of the rotation angle, an actual steering angle position can be determined.

[0053] Each angle sensing element has a rotor, for example rotor 2, and a stator. In inductive sensors, the stator is constructed in a manner known to those skilled in the art and comprises at least one excitation coil and at least one sensor coil. In the present embodiment, the respective stator is arranged on a single multilayer printed circuit board 8, which is mounted in Fig. 2 This is shown as an example. The multilayer circuit board 8 has a total of six layers, which are shown in the Fig. 2 are designated L1, L2, L3, L4, L5 and L6. The individual layers L1 to L6 are applied to printed circuit board material, which is in the Fig. 2 For the sake of clarity, it is symbolized by means of different textures. The stator of the in the Fig. 1 The partially depicted angle detection device is arranged on layers L1 and L2 of the circuit board 8, and the stator of the in Fig. 1The angle sensing means (not shown) is arranged on layers L5 and L6 of the printed circuit board 8. On layers L3 and L4 of the printed circuit board 8, the indexing means, designed as an inductive sensor, is arranged. Additionally, layers L3 and L4 of the printed circuit board 8 serve as a shield, which at least reduces unwanted interaction between the angle sensing means, also designed as inductive sensors, whose stators are arranged on layers L1 and L2 as well as on layers L5 and L6 of the printed circuit board 8. Fig. 2 Only layers L1 to L6 are shown, but not the stators and the indexing element designed as an inductive sensor.

[0054] Today's torque sensors are fundamentally based on the principles relating to Figure 1 and 2The principles described above, or those with magnetic blinds, are also relevant. A component of a modern power steering system is a so-called torsion bar, which twists when torque is applied. The two ends of the torsion bar are often referred to as the "input shaft" and "output shaft" (or, in this context, the input and output sides). In current technologies, some of which are also referred to as CIPOS structures, these components are integrated into a multilayer printed circuit board (PCB), such as those used in... Figure 2As described, several measuring channels are housed within the structure. Specifically, layers L1 and L2 implement measuring channels that measure the angle of the input shaft, layers L3 and L4 are shielding layers, and layers L5 and L6 contain measuring channels for measuring the angle at the output shaft. The difference between the angles at the input and output shafts represents the twist of the torsion bar and is proportional to the torque that the driver applies to the steering wheel.

[0055] In particular, CIPOS sensors are designed such that an eighteen-bladed CIPOS sensor (IS) with an eighteen-bladed rotor (IS-R) with a uniqueness range of 360° / 18=20° is formed on the "input shaft" side, and a nine-bladed rotor (OS-R) with an absolute measuring range of 40° is formed on the "output shaft" side. The rotors with the nine (or eighteen) blades are made, among other things, of stamped and bent metal parts, plastic parts containing electrically conductive surfaces, or overmolded stamped parts.

[0056] The in relation to Figure 1 and 2The details described describe an inductively operating rotary angle sensor. With such a rotary angle sensor, it is complex to distinguish a specific rotation angle from a rotation angle rotated by a full revolution. Therefore, it was considered to use indexing once a full revolution has been reached.

[0057] For this purpose, it was considered to modify the rotor surfaces by creating cutouts to make them distinguishable. These modified rotor surfaces allow for differentiation between solid and hollow rotor blades. For example, a modified blade can be distinguished from the others, and indexing can occur once the modified blade has completed a full rotation. In other words, the rotor of an angle sensing device, used to detect the angular position of the rotating part relative to a reference position, also serves for indexing after a predetermined rotation, preferably a 360° rotation, of the rotating part relative to the reference position by means of the indexing device.

[0058] The one in relation to Figure 1 and 2The described inductive sensor (CIPOS) primarily utilizes the outer contour of a wing and not the surface itself. For inductive position detection (CIPOS), solid surfaces are inherently problematic because eddy currents can form freely. Therefore, designs with hollow and solid wings exhibit a slight inductive asymmetry that is detrimental to measurement. New implementations are thus desirable.

[0059] Figures 3a to 3c Figures show a rotor of a capacitive position sensing device and / or a rotary angle sensor with such a capacitive position sensing device. The basic structure of the rotary angle sensor can be compared to the basic structure of the inductive sensor from Figure 1 corresponding. However, alternative designs are also possible, for example, torque sensors with magnetic louvers. The following refers to the Figures 3a to 3cA design of the rotor of a capacitive position detection device and / or a rotary angle sensor with such a position detection device is described.

[0060] The capacitive position sensing device has at least one stator (in the Figs. 3a to 3c(not shown), at least one rotor 100 and an evaluation unit. The at least one stator can be arranged in a fixed position relative to a rotating element. That is, when the rotating element rotates, the stator does not rotate with it if it is connected to the rotating element. The at least one rotor 100 can be connected to the rotating element in a rotationally fixed manner. That is, when the rotating element rotates, the rotor 100 rotates with it if it is connected to the rotating element in a rotationally fixed manner. The at least one rotor 100 has a base body 110 and, for example, several rotor blades 120a, 120b extending radially outwards from the base body 110 (as an example of at least one rotor blade). A first dielectric with a first permittivity is present between at least one of the several rotor blades 120a and the at least one stator.Between at least one second rotor blade 120b of the multiple rotor blades and the at least one stator, a second dielectric with a second permittivity is present. The first permittivity and the second permittivity are different from each other. The evaluation unit is designed to detect when the at least one first rotor blade 120 reaches, has reached, or exceeds a predetermined rotational position.

[0061] In the following, a torsion bar is assumed to be the rotating element.

[0062] The Rotor 100 of Figures 3a to 3cFigure 1 shows an example of a rotor carrier 130. The rotor carrier 130 is designed to support the base body 110 and thus the rotor blades 120a, 120b, and is rotationally fixed to the base body 110 and to the rotor blades 120a, 120b. The rotor carrier 130 can be made of metal or be constructed from metal. Additionally or alternatively, the rotor carrier 130 can be made of plastic or be constructed from plastic. In the example from Figures 3a to 3c The rotor carrier 130 is made of a plastic, for example. The base body 110 can be made of or have a metal component. Additionally or alternatively, the base body 110 can be made of or have a plastic component. In the example from Figures 3a to 3cThe base body 110 is made of a metal, for example. The rotor blades 120a, 120b can be made of or have a metal component. Additionally or alternatively, the rotor blades 120a, 120b can be made of or have a plastic component. In the example from Figures 3a to 3c The rotor blades 120a, 120b are made of a metal, for example.

[0063] In the example from Figures 3a to 3c The rotor 100 has nine rotor blades 120a, 120b. A different number of rotor blades is conceivable and possible, for example, eighteen rotor blades for the input shaft (for the inlet side). Of the nine rotor blades, six are configured as the first rotor blades 120a by way of example. Of the nine rotor blades, three are configured as the second rotor blades 120b by way of example.

[0064] The first dielectric can be made of a plastic or be designed as a plastic. The second dielectric can be made of a plastic or be designed as a plastic and / or can be made of air or be designed as air. In the example from Figures 3a to 3c The first dielectric is formed from a plastic as an example, and the second dielectric is formed from air as an example.

[0065] In the example from Figures 3a to 3cThe first dielectric is formed by the rotor carrier 130. More precisely, the rotor carrier 130 is configured such that it has first sectors or sections 130a and second sectors or sections 130b. The first sectors or sections 130a are circular sectors with a first radius. The second sectors or sections 130b are circular sectors with a second radius. The first radius is larger than the second radius. The first sectors or sections 130a are configured such that they are aligned with or cover the first rotor blades 120a. As a result, the sectors 130a are located between the first rotor blades 120a and the stator. In other words, a plastic material is thus positioned as the first dielectric between the first rotor blades 120a and the stator.The second sectors or sections 130b are designed, due to their smaller radius, in such a way that recesses are created which are aligned with the rotor blades 120b. As a result, the recesses lie between the second rotor blades 120b and the stator. In other words, air acts as a second dielectric between the second rotor blades 120b and the stator. In the example from... Figures 3a to 3c The permittivity of the first dielectric is greater than the permittivity of air.

[0066] Even if this is in the Figures 3a to 3c Not shown, the rotor 100 may further have at least one third rotor blade, wherein a third dielectric with a third permittivity is present between the at least one third rotor blade and the at least one stator.

[0067] The evaluation unit can be configured to detect when at least one of the first six rotor blades 120a reaches, has reached, or exceeds a predetermined rotational position. Upon reaching or exceeding the predetermined rotational position, the evaluation unit can increment a counter (e.g., by the value 1). For example, the evaluation unit can generate a switching signal each time at least one of the first six rotor blades 120a reaches, has reached, or exceeds the predetermined rotational position. The switching signal can indicate to increment the switch. The predetermined rotational position can, for example, correspond to a rotational angle segment. The rotational angle segment can, for example, cover an angle of 20° or 40°.

[0068] According to a not in the Figures 3a to 3cIn the alternative shown, for example, only a single first rotor blade 120a may be provided. In this case, the evaluation unit can be configured to detect when the single first rotor blade 120a reaches, has reached, or exceeds the predetermined rotational position, e.g., 360°. When the single first rotor blade 120a reaches, has reached, or exceeds the predetermined rotational angle, the evaluation unit can output a switching signal to activate the counter. This allows predetermined rotational angles, such as partial or complete revolutions, to be counted / indexed. In this way, for example, the rotational angles can be determined with respect to Figure 2 The described indexing means (which can also be referred to as indexing component or indexing device) can be implemented as a capacitive sensor.

[0069] The at least one rotor can be configured as two rotors. One of the two rotors can be located on the input shaft (the input side), and the other can be located on the output shaft (the output side). The evaluation unit can determine the angle of rotation or the total rotation of the two rotors and calculate the difference between these two angles of rotation or total rotations to determine a differential angle. From this differential angle, the evaluation unit can determine the torque acting on the torsion bar.

[0070] The in relation to Figures 3a to 3c The described design serves, so to speak, to implement a capacitive switch. The capacitive switch can be combined with the inductive angle detection method, as described in relation to... Figure 1As described above, the evaluation unit can determine the rotor's angle of rotation (up to a full 360° revolution) using inductive coupling. By also considering the counter value, the total rotation of the rotor, even for values ​​exceeding 360°, can be efficiently determined. This effectively combines a capacitive switch with inductive angle detection. In this way, inductive angle detection can be optimally combined with a capacitive switch at a predetermined rotational position (e.g., 40° or 360°). This means that the switch, with its conductive metal blades, can be used as an inductive position sensor (CIPOS).

[0071] According to an example, the largest area of ​​uniqueness lies on the side of the nine rotor blades and is therefore 360° / 9 = 40°. In this case, the index switch also recognizes straight-ahead travel, even after plausibility checks. Subsequently, the counter starts counting as soon as a predetermined rotational position, for example, an angle segment of 40°, is reached or exceeded (i.e., the number of times the 40° track is crossed is counted). The steering angle is thus steering angle = n * 40° + the measured angle of the rotation angle sensor (e.g., CIPOS) within the 40° segment.

[0072] In other words, according to this example, the counter detects when an angle segment (e.g., 40°) is reached or exceeded. As soon as the angle segment is reached or exceeded, the counter is incremented or decremented depending on the direction of the deviation. This counter operates capacitively. For example, if five angle segments have been reached or exceeded, the counter can be used to determine an approximate rotation angle of 5 * 40° = 200°. The precise steering angle can then be determined using the inductively operating angle-determining device. For example, if the angle-determining device measures an angle of 12°, the resulting steering angle is 5 * 40° + 12° = 212°.

[0073] This means that capacitive modulation for a capacitive sensor or switch operating, for example, in parallel with an inductive sensor, is achieved by designing the rotor in such a way that the dielectric between the rotor and stator of the angle sensor or switch is encoded using several different dielectrics. In this way, individual rotor blades that need to be highlighted can be coated with a plastic with the highest possible dielectric constant (permittivity), while other blades that do not need to be encoded are not coated with plastic, and here only the permittivity of air is effective. The plastic body designed in this way simultaneously serves as the support for the metallic rotor structure.

[0074] Alternatively, a rotor can be made from a two-component (2K) plastic part, where individual sectors of the rotor are made with plastics of different permittivity. Besides 2K plastic parts, plastic parts, such as injection-molded parts, made from 3 to n different plastics are also conceivable.

Claims

1. Position sensing device for a rotational angle sensor, said position sensing device comprising: at least one stator; at least one rotor (100), with said at least one rotor (100) having a base body (110) and at least one rotor blade (120a, 120b) extending radially outwards from the base body (110), whereby a first dielectric with a first permittivity is present between at least one first blade (120a) of the at least one rotor blade (120a, 120b) and the at least one stator, and a second dielectric with a second permittivity is present between at least one second rotor blade (120b) and the at least one stator, whereby the first permittivity and the second permittivity are different from one another; an evaluation unit designed to detect when the at least one first rotor blade (120a) reaches, has reached or exceeds a predetermined rotational position.

2. Position sensing device for a rotational angle sensor, said position sensing device comprising: at least one stator; at least one rotor (100), with said at least one rotor (100) having a base body (110) and at least one rotor blade (120a, 120b) extending radially outwards from the base body (110), whereby a first dielectric with a first permittivity is present between at least one first blade (120a) of the at least one rotor blade (120a, 120b) and the at least one stator, and a second dielectric with a second permittivity is present between at least one free space adjacent to the at least one first rotor blade (120a) in the circumferential direction of the rotor (100) and the at least one stator, whereby the first permittivity and the second permittivity are different from one another; an evaluation unit designed to detect when the at least one first rotor blade (120a) reaches, has reached or exceeds a predetermined rotational position.

3. Position sensing device according to claim 1 or 2 in which the evaluation unit is designed to detect, based on a capacitive coupling between the at least one rotor (100) and the at least one stator, when the at least one first rotor blade (120a) reaches, has reached or exceeds a predetermined rotational position starting from a reference position.

4. Position sensing device according to claim 1, 2 or 3 in which the evaluation unit is designed to generate a switching signal when the at least one first rotor blade (120a) reaches, has reached, or exceeds the predetermined rotational position.

5. Position sensing device according to one of claims 1 to 4 in which the first dielectric comprises a plastic or is designed as a plastic.

6. Position sensing device according to one of claims 1 to 5 in which the second dielectric comprises a plastic or is designed as a plastic, and / or comprises air or is designed as air.

7. Position sensing device according to one of claims 1 to 6 in which the rotor (100) comprises a rotor carrier (130) designed to support the base body (110) of the rotor (100).

8. Position sensing device according to claim 7 in which the rotor carrier (130) comprises a plastic or is designed as a plastic, for example comprises a multi-component plastic part or is made from a multi-component plastic part.

9. Position sensing device according to claim 7 or 8 in which the rotor carrier (130) comprises: at least one first circular segment-shaped section (130a), where the at least one first circular segment-shaped section (130a) has a first radius and forms the first dielectric.

10. Position sensing device according to claim 9 in which the rotor carrier (130) comprises: at least one second circular segment-shaped section (130b), where the at least one second circular segment-shaped section (130b) has a second radius and forms the second dielectric, with the second radius being smaller than the first radius.

11. Position sensing device according to one of claims 1 to 10 in which a third dielectric with a third permittivity is present between at least one third of the at least one rotor blade (120a, 120b) and the at least one stator.

12. A rotational angle sensor comprising: the position sensing device according to one of claims 1 to 11, a rotational angle detection device comprising: the at least one stator; the at least one rotor (100); the evaluation unit, said evaluation unit being designed to determine a rotational angle of the at least one rotor (100) relative to the at least one stator, starting from the reference position.

13. A rotational angle sensor according to claim 12, in which the evaluation unit is designed to determine a rotational angle of the at least one rotor (100) on the basis of an inductive coupling between the at least one rotor (100) and the at least one stator.

14. A system comprising a rotational angle sensor according to claim 12 or 13 and a rotating element in which the at least one stator of the rotational angle sensor is arranged stationary relative to the rotating element and the at least one rotor (100) is connected in a rotationally fixed manner to the rotating element, and the evaluation unit of the rotational angle sensor is designed to determine a torque acting on the rotating element from the determined rotational angle of the at least one rotor (100), with said rotating element being designed as a torsion bar.