POSITION DETECTION FOR A ROTATING ANGLE SENSOR

Description

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

[0002] Angle sensors are used in motor vehicles, for example. For example, electric motor servo systems are increasingly being used for steering assistance. These require steering torque for control. The steering torque is detected in a steering column by a torsion bar in differential angles and calculated from these. More precisely, twists at the ends of the torsion bar are determined using angle sensors, and differential angles are derived from these. The differential angles caused by the torsion can be determined independently of the steering wheel position. In today's electric power steering systems, torque sensors are used as a human-machine interface (HMI). These measure the "force" the driver applies to the steering wheel, allowing steering assistance to be provided.In the future, with the elimination of the steering column and the establishment of so-called steer-by-wire systems, sensors for steering angle and possibly steering torque will be necessary on the steering drive unit or the "Hand Wheel Sensor & Actuator".

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

[0004] For example, magnetic torque sensors are known for indexing, using a Hall sensor and an associated magnet to generate a signal for each complete rotation of the steering wheel, thus determining the number of revolutions. This uses a process often referred to as a magnetic blind, in which a change in the magnetic flux density occurs during rotation. Associated sensors are also referred to as torque-only sensors (TOS). These sensors are not capable of detecting a steering angle.

[0005] Examples of such torque sensors are described in EP 1 269 133 B1 and US 7,644,635 B2.

[0006] Such devices for determining the angle of rotation and / or torque of a rotating part, as well as methods for their operation, are already known in numerous variants from the prior art. Sensors are generally known that measure both the torque at the steering wheel and the steering angle.

[0007] DE 10 2004 019 379 A1 discloses a method for determining a differential angle. Two rotation angles are determined and a differential angle is calculated from these. When calculating the differential angle, different gear ratios between the rotations of two components are taken into account. A large number of revolutions are ignored.

[0008] EP 2 383 558 A1 discloses an inductive angle sensor for determining torque and relative angular position with respect to a reference position, 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 torque sensor with angle determination and indexing that is inexpensive and compact to manufacture, a flux guide plate is assigned to the Hall sensor, which guides the flux of the permanent magnet to the Hall sensor in the reference position.

[0009] WO2019 / 185338 A1 discloses a device for determining a rotation angle and / or a torque of a rotating part. The device comprises at least one angle detection means for detecting an 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 detection means comprises a rotor connected in a rotationally fixed manner to the rotating part, having a base body for attachment to the rotating part and a plurality of vanes extending radially outward from the base body. At least one of the vanes of the rotor has a marking detectable by the indexing means.

[0010] Such indexing makes it possible to dispense with the absolute determination of the steering angle over the measuring range of typically 1440°. Instead, the indexing adds a type of contactless switch that generates a switching signal (index signal / index signal) when 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 the influence of external fields.

[0011] WO 2019 / 185336 A1 discloses a device for determining a rotation angle of a rotor.

[0012] In view of this, there is a need for an 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, a rotation angle sensor according to claim 11 with such a position detection device, and a system according to claim 13 with such a rotation angle sensor are specified. Specific embodiments of the position detection device are set forth in dependent claims 2 to 10. A specific embodiment of the rotation angle sensor is set forth in dependent claim 12.

[0013] According to a first aspect of the invention, a position detection device for a rotation angle sensor is provided. The position detection device has at least one stator, at least one rotor, and at least one evaluation unit. The at least one rotor has a base body and a plurality of rotor blades extending radially outward from the base body. A plurality of first rotor blades of the plurality of rotor blades are designed differently from a plurality of second rotor blades of the plurality of rotor blades. The evaluation unit is designed to detect when the plurality of first rotor blades reach, have reached, or exceed a predetermined rotational position, for example, starting from a reference position.

[0014] For this purpose, the evaluation unit does not need to detect for each of the plurality of first rotor blades when the respective first rotor blade reaches, has reached, or exceeds a predetermined rotational position. For example, by detecting that one of the plurality of first rotor blades reaches, has reached, or exceeds the predetermined rotational position, it can be deduced that all of the plurality of first rotor blades have moved or rotated by the same amount or angle.

[0015] For example, the evaluation unit can be designed to detect when the entirety of the plurality of first rotor blades, for example starting from a reference position, reaches, has reached or exceeds a predetermined rotational position.

[0016] The at least one stator can be arranged stationary relative to a rotating element. Segments can be arranged on the at least one stator, each corresponding to the plurality of first rotor blades and the plurality of second rotor blades. The at least one rotor can be connected to the rotating element in a rotationally fixed manner. The plurality of first rotor blades can each be of identical design. The plurality of second rotor blades can each be of identical design.

[0017] The evaluation unit can be designed to detect, based on a capacitive coupling between the at least one rotor and the at least one stator, when the plurality of first rotor blades, starting from a reference position, reach, have reached, or exceed a predetermined rotational position. According to one embodiment, the evaluation unit is designed not to determine the exact angle of rotation of the at least one rotor blade based on the capacitive coupling, but to detect when the plurality of first rotor blades, starting from a reference position, reach, have reached, or exceed 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, after each complete revolution of the plurality of first rotor blades, e.g.the entirety of the plurality of first rotor blades, the predetermined rotational position can be reached again. According to another example, the predetermined rotational position can correspond to a rotation angle segment. The rotation angle segment can be less than 360°.

[0018] It can therefore be said that the position detection device according to the first aspect operates capacitively. The at least one rotor acts as at least one electrode and the at least one stator acts as an associated 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 capacitance value of a capacitance and thus 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 the at least one rotor and the at least one stator and / or on the distance between the respective electrodes.Furthermore, the capacitance of a capacitor, and thus the strength of the electric field, depends on the capacitively effective overlapping electrode surfaces. Changing the overlap of the electrode surfaces changes the capacitance. The greater the overlap of the electrode surfaces, the greater the capacitance. The smaller the overlap of the electrode surfaces, the lower the capacitance.

[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 for low-frequency magnetic fields are also increasing. Such very large magnetic fields are generated, especially by the high currents of the electric motors in an electric vehicle's traction drive. Magnetic solutions are susceptible to EMC. The capacitive solution proposed here improves robustness against magnetic fields and provides a simpler and therefore more cost-effective solution.

[0020] Due to the different design / configuration of the plurality of first rotor blades and the plurality of second rotor blades, the plurality of first rotor blades can be differentiated from the second rotor blades. The evaluation unit can, for example, determine when the plurality of first rotor blades, starting from the reference position, reach, have reached or exceed 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 per complete rotation. The evaluation unit can, for example, determine when the plurality of first rotor blades have each rotated by a predetermined angle of rotation, e.g. by a full rotation of 360°, up to the predetermined rotational position. In this way, for example, a full rotation of the plurality of first rotor blades (i.e. one rotation of 360°) can be determined in each case.According to another example, there may be several predetermined rotational positions per complete rotation. For example, the evaluation unit can determine when the plurality of first rotor blades have each rotated by a predetermined rotational angle, e.g., by a rotational angle segment of, for example, 40°, up to the predetermined rotational position. In this way, for example, each rotation of the plurality of first rotor blades by a specific rotational angle segment (e.g., a rotation of 40°) can be determined.

[0021] The evaluation unit can be designed to generate a switching signal when the plurality of first rotor blades reach, have reached, or exceed the predetermined rotational position. The evaluation unit can be designed to generate a switching signal when it determines that the plurality of first rotor blades reach, have reached, or exceed the predetermined rotational position. The switching signal can be a logical switching signal that can be transmitted via an electronic digital interface together with further sensor or diagnostic data. Each time a switching signal is generated, a counter can, for example, be increased or decreased by 1 depending on the direction. In this way, a type of indexing can be achieved. With the help of this type of indexing, it is possible to dispense with an absolute determination of the steering angle over the measuring range of 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 / index signal), for example, when driving straight ahead and / or upon reaching a predetermined rotational position. The position detection device can therefore also be viewed as a type of switch and referred to as a switch, for example. If an angle sensor on the steering system clearly detects a partial steering angle range, the direction-dependent switching signal can be used to count the partial steering angle ranges and thus add the counter reading multiplied by the partial steering angle range in order to clearly derive the angle within the partial steering angle range and determine the total measuring range. For a selectable version, for example, a partial range is specified by the number of rotor blades, for example 9, resulting in a partial steering angle range to be clearly measured: 360° / 9 = 40°.

[0022] Previous designs 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 the influence of external fields.

[0023] For example, the counter can be incremented or decremented by 1 each time the plurality of first rotor blades reach, have reached, and / or exceed a predefined rotation angle segment as the predetermined rotational position, based on direction. In this way, the reaching or exceeding of certain rotation angle segments, e.g., 40°, can be counted. The rotation angle can then be derived from the counter reading without having to determine the rotation angle itself. If, for example, the angular sub-range is 40°, ie the counter is incremented or decremented each time a rotation angle segment of 40° is reached, then with a counter reading of 4 and a predefined direction, a rotation angle of 4*40°=160° can be derived.

[0024] According to one example, an index switch can be implemented with the aid of the evaluation unit; the evaluation unit can be arranged in such an index switch, or the angle of rotation sensor can be implemented as such an index switch. The index switch can be installed, for example, when the steering is traveling straight ahead. It can be assumed that right and left turns should normally alternate on roads. Once the straight-ahead position has been identified as the index point and verified, the rollovers of the motor position sensor for commutation of this motor or the sweeping of specific angle segments, for example, 40° segments, of an angle of rotation sensor can be counted.

[0025] In the torque sensors with magnetic blinds known from the prior art, as described above, no steering angle is detected when the magnetic blind is activated. Counting angle segments / angle sections after indexing is not possible in this case. Therefore, an index switch and a counter actually seem unnecessary. However, an index switch and an associated counter are also advantageous in this context, since an additional position sensor is implemented on the motor to control the electric motor of the power steering and to commutate it. Due to the steering gear's gear ratio of approximately 20 to 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 deduced (indirectly, so to speak).

[0026] In order to clearly determine angles of rotation that are greater than a full revolution (360°), it is conceivable according to one possible embodiment that although several first rotor blades exist, only a single first rotor blade is used for indexing. For this purpose, the evaluation unit can be designed to detect when one / only first rotor blade of the several first rotor blades, and thus the entirety of the several first rotor blades, reaches, has reached or exceeds a predetermined angle of rotation, e.g. a rotation angle of 360°. The evaluation unit can, for example, be designed to detect when one / only one of the several first rotor blades reaches, has reached or exceeds an index position.The evaluation unit can be designed to generate a switching signal when it determines that one of the plurality of first rotor blades reaches, has reached or exceeds the predetermined angle of rotation, for example the index position.

[0027] The plurality of first rotor blades may have a different shape than the plurality of second rotor blades. Additionally or alternatively, the plurality of first rotor blades may have a different area or surface than the plurality of second rotor blades.

[0028] According to an exemplary embodiment, the plurality of first rotor blades can be designed as hollow blades and the plurality of second rotor blades can be designed as solid blades. According to an exemplary embodiment, the plurality of first rotor blades can be designed as solid blades and the plurality of second rotor blades can be designed as hollow blades. A hollow blade can be understood to mean a rotor blade which or in whose surface a cavity or an opening is formed. A solid blade can be understood to mean a rotor blade which or whose surface is completely filled. By designing as hollow blades and solid blades, a different area or surface of the plurality of first rotor blades on the one hand and the plurality of second rotor blades on the other hand can be achieved.Accordingly, the strength of the electric field generated by the plurality of first rotor blades may differ from the strength of the electric field generated by the plurality of second rotor blades. The plurality of first rotor blades can thus be distinguished from the plurality of second rotor blades (e.g., due to different capacitive couplings with the stator).

[0029] According to an exemplary embodiment, the plurality of first rotor blades can be longer and / or wider than the plurality of second rotor blades. According to an exemplary embodiment, the plurality of first rotor blades can be shorter and / or narrower than the plurality of second rotor blades. A different shape (and thus a different area or surface) of the plurality of first rotor blades on the one hand and the plurality of second rotor blades on the other hand can be achieved through the longer, wider, shorter and / or narrower configuration.

[0030] The plurality of first rotor blades and the plurality of second rotor blades can be arranged relative to one another in a predetermined sequence. The predetermined sequence can be configured such that the evaluation unit can clearly determine when one or a single one of the plurality of first rotor blades has reached, reached, or exceeded the predetermined angle of rotation, e.g., the index position.

[0031] According to one possible exemplary embodiment, the number of the plurality of rotor blades can be nine, the number of the plurality of first rotor blades can be three, and the number of the plurality of second rotor blades can be six. The predetermined sequence of the plurality of first rotor blades and the plurality of second rotor blades relative to one another can be as follows: second rotor blade, first rotor blade, second rotor blade, second rotor blade, first rotor blade, second rotor blade, second rotor blade, first rotor blade. In this case, the evaluation unit can, for example, be designed to uniquely detect one of the first rotor blades, e.g. rotor blade number 2, rotor blade number 5, or rotor blade number 9, and / or the entirety of the first rotor blades. Any one of the first rotor blades can be used for indexing.Regardless of which of the first rotor blades is used for indexing, it can always be determined when the entirety of the first rotor blades reaches, has reached or exceeds the predetermined angle of rotation. Accordingly, the evaluation unit can be designed, for example, to use rotor blade number 5 for indexing. As soon as rotor blade number 5 and thus the entirety of the first rotor blades reaches, has reached or exceeded the predetermined angle of rotation, e.g. the index position, the evaluation unit can output a switching signal. This switching signal can cause indexing, e.g. an increment of a counter by one. A further rotation of rotor blade number 5 by the predetermined angle of rotation, e.g. up to the index position, for example by a rotation angle of 360°, can in turn cause indexing, e.g. an increment of the counter by one.In this way, rotation angles of several complete revolutions can be recorded, for example, by incrementing a counter. Shifts of the example sequence forward or backward (left or right; clockwise or counterclockwise) are possible, whereby the detected rotor blade does not change accordingly, but the position of the detected rotor blade within the sequence changes accordingly.

[0032] Based on the aforementioned or another sequence, the evaluation unit can be configured to detect when the one / only rotor blade, for example, rotor blade number 5, and thus the entirety of the plurality of first rotor blades, reaches, has reached, or exceeds a predetermined angle of rotation, and to generate a switching signal when the one / only rotor blade of the plurality of first rotor blades, and thus the entirety of the plurality of first rotor blades, reaches, has reached, or exceeds the predetermined angle of rotation. The evaluation unit can perform this detection based on the sequence of the rotor blades, even though the plurality of first rotor blades are identically configured.

[0033] The plurality of first rotor blades and the plurality of second rotor blades can be arranged relative to one another such that the switching signal is generated only once per rotation by the predetermined angle of rotation. In other words, the plurality of first rotor blades and the plurality of second rotor blades can be arranged relative to one another such that the switching signal is generated only when the one / only first rotor blade of the plurality of first rotor blades or the entirety of the plurality of first rotor blades reaches, has reached, or exceeds the index position. This can be derived from different capacitive coupling(s) of the rotor blades to the stator.

[0034] The plurality of first rotor blades and the plurality of second rotor blades can be arranged relative to one another in such a way that the evaluation unit is able to detect that a single first rotor blade of the plurality of first rotor blades or the entirety of the plurality of first rotor blades reaches, has reached, or exceeds an index position. In other words, the plurality of first rotor blades and the plurality of second rotor blades can be arranged relative to one another in such a way that it is detected when the one / only first rotor blade of the plurality of first rotor blades or the entirety of the plurality of first rotor blades reaches, has reached, or exceeds the index position.This can be achieved by detecting only one of the plurality of first rotor blades, not each of the plurality of first rotor blades or all of the plurality of first rotor blades, or the entirety of the plurality of first rotor blades, even though the plurality of first rotor blades are identically formed.

[0035] The plurality of first rotor blades can be connected to a first capacitor. The plurality of second rotor blades can be connected to a second capacitor. From this connection and the signals resulting from the capacitors, the evaluation unit can detect when the entire plurality of first rotor blades reaches, has reached, or exceeds the predetermined angle of rotation.

[0036] The rotating element (which can also be referred to as a rotating element) can comprise 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 circuit board. The rotating element can extend through the circuit board and the at least one rotor.

[0037] According to a second aspect, a rotation angle sensor is provided. The rotation angle sensor has the position detection device as described herein. The rotation angle sensor further has a rotation angle determination device. The rotation angle determination device has the at least one stator, the at least one rotor, and the evaluation unit. The evaluation unit is designed to determine a rotation angle of the at least one rotor relative to the at least one stator, based on the reference position.

[0038] 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.

[0039] The evaluation unit can be designed to determine the angle of rotation of the at least one rotor based on an inductive coupling between the at least one rotor and the at least one stator. The evaluation unit can, for example, determine the angle of rotation of the at least one rotor up to a partial or complete revolution as an intermediate result. Furthermore, the evaluation unit can be designed to determine the value of the counter described above. The value of the counter can indicate the number of partial or complete revolutions of the at least one rotor blade of the rotor. From the intermediate result (for example, the angle of rotation up to 360°) and the value of the counter, the evaluation unit can determine the total rotation of the rotor. The partial angle of rotation can, for example, be an angle segment. According to one example, exceedances of a respective angle segment, ieSegment overshoots are counted. The angle segment can, for example, be an angle segment of 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 overshoot of 20° or 40°. In particular, the angle signal can be repeated every 20° or 40°, for example, and in this way, a steering angle of 1440° can be calculated.

[0040] In one embodiment, the at least one rotor can be designed as two rotors. The evaluation unit can be designed to determine the angle of rotation of a first of the two rotors and the angle of rotation of a second of the two rotors. The evaluation unit can be designed to determine the total rotation of the first of the two rotors from the determined angle of rotation (up to one complete revolution) and the value of the counter. The evaluation unit can be designed to determine the total rotation of the second of the two rotors from the determined angle of rotation (up to one complete revolution) and the value of the counter. The first rotor can be arranged at one end of the rotating element. The second rotor can be arranged at another 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 differential 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. The evaluation unit can derive the torque acting on the rotating element from the differential angle.

[0041] According to a third aspect of the invention, a system is proposed. The system comprises a rotation angle sensor as described herein. The system further comprises a rotating element. The at least one stator of the rotation angle sensor is arranged stationary relative to the rotating element. The at least one rotor is connected to the rotating element in a rotationally fixed manner. The evaluation unit of the rotation angle sensor is designed to determine a torque acting on the rotating element from the determined rotation angle or the total rotation of the at least one rotor. The rotating element can have a torsion bar or be designed as a torsion bar.

[0042] The evaluation unit can be configured to determine a torque acting on the rotating element from the determined 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 determined angle of rotation or the total rotation of the at least one rotor.

[0043] The described angle of rotation sensor and the described system can be implemented in whole or in part using a computer program. Thus, a computer program product with program code sections for carrying out the method can be provided. The computer program can be stored on a computer-readable storage medium or in the angle of rotation sensor and / or the system, for example in the evaluation unit. If the program code sections of the computer program are loaded into a computer, or processor (for example a microprocessor, microcontroller or digital signal processor (DSP), digital hard-wired logic in an ASIC) or run on a computer, or processor, they can cause the computer or processor to perform one or more steps or all steps of the technique described herein.

[0044] Although some of the aspects and details described above have been described with respect to the angle of rotation sensor, these aspects can also be implemented in a corresponding manner in the system with the angle of rotation sensor or a computer program supporting the angle of rotation sensor.

[0045] The present invention will be further explained with reference to the accompanying figures. These figures schematically show: Figure 1 shows an exploded view of an inductive torque sensor from the prior art; Figure 2 shows a schematic representation of a multilayer circuit board; Figure 3a shows a view of a rotor according to an embodiment; Figure 3b shows an autocorrelation function of the rotor coding of the rotor from Figure 3a ; Figure 3c shows a view of a stator according to an embodiment; and Figure 3d shows a view of a rotor according to an embodiment.

[0046] In order to provide a thorough understanding of the present invention, specific details are set forth below, but are not intended to be limiting. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that may vary from the details set forth below.

[0047] It will also be clear to those skilled in the art that the explanations set out below may be implemented using hardware circuits, software means, or a combination thereof. The software means may be associated with programmed microprocessors or a general calculator, computer, ASIC (Application Specific Integrated Circuit), and / or DSPs (Digital Signal Processors). It is also clear that, although the following details are described with reference to a method, these details may also be implemented in a suitable device unit, a computer processor, or a memory connected to a processor, the memory being provided with one or more programs that perform the method when executed by the processor.

[0048] Figure 1shows an inductive torque sensor known from the prior art. The inductive torque sensor comprises a circuit board 1 and two rotor disks 2 (or two rotors 2 for short), wherein the rotor disks 2 have different rotor structures 3 with structure sizes of, for example, 20° and 40° respectively. The rotor disks 2 are largely parallel and arranged on a common shaft, which here is formed by a torsion bar. This is part of a steering shaft. The rotor disks 2 are distributed at a short distance from both main surfaces of the circuit board 1. The circuit board 1 and a first of the rotor disks 2a are largely tightly enclosed by a housing 5. A second of the rotor disks 2b is mounted externally on the housing 5 at a minimal distance. The rotor disks 2, the circuit board 1 and the housing 5 each have an opening for the torsion bar. The openings are accordingly aligned.

[0049] Each rotor disk 2 is rotationally fixed to the torsion bar by means of a support structure 6, which has a torsion element between the rotor disks 2. The one-piece support structure 6 comprises a tubular section, the inner diameter of which corresponds to the diameter of an associated part of the torsion bar plus a predetermined small amount of play, and to which the corresponding rotor disk 2a, 2b is attached. A disk 12 is attached from the outside to the support structure 6 of the first rotor disk 2a, which is arranged in the housing 5 and bears tightly against the housing 5. In this way, the torque sensor is inherently stabilized against tilting, thereby minimizing related measurement errors.

[0050] Four stators are formed on the circuit board 1, which, in conjunction with the two rotors 2, form four angle sensors. The stators, along with the required excitation structures, are applied and contacted in a known manner as conductive tracks on the two main surfaces of the circuit board 1. The stator structures are coordinated with the structures of the rotor disks 2a, 2b.

[0051] Furthermore, at least one application-specific integrated circuit (ASIC) 7 is arranged on the circuit board 1. Each circuit 7 has at least two channels. If necessary, at least one evaluation unit is connected downstream of the circuit 7. The circuit 7 and, if necessary, the at least one evaluation unit form the means for evaluation.

[0052] 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.

[0053] 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, and starting from a fixed zero position, rotation angles are calculated. Depending on the torque applied to the steering rod via a steering wheel, the torsion bar twists by a specific angle, causing the two rotors 2 to rotate by correspondingly different rotation angles. A differential angle is calculated from these different rotation angles, from which the torque applied to the steering rod is determined.

[0054] Furthermore, a number of complete revolutions 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; the sum, in conjunction with the rotation angle signal, allows the actual steering angle position to be determined.

[0055] Each of the angle detection means comprises, in addition to the rotor, for example rotor 2, a stator. The stator is constructed in a manner known to those skilled in the art for inductive sensors 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 multi-layer printed circuit board 8, which is Fig. 2 The multilayer printed circuit board 8 has a total of six layers, which are Fig. 2 are labeled L1, L2, L3, L4, L5 and L6. The individual layers L1 to L6 are applied to printed circuit board material, which is Fig. 2 For better clarity, the stator is symbolized by different textures. Fig. 1 The angle detection means partially shown is arranged on the layers L1 and L2 of the circuit board 8 and the stator of the Fig. 1The angle detection means (not shown) is arranged on layers L5 and L6 of the circuit board 8. On the one hand, the indexing means designed as an inductive sensor is arranged on layers L3 and L4 of the circuit board 8. On the other hand, layers L3 and L4 of the circuit board 8 are additionally designed as a shield, by means of which an undesired interaction between the angle detection means designed as inductive sensors is at least reduced, the stators of which are arranged on layers L1 and L2 as well as on layers L5 and L6 of the circuit board 8. Fig. 2 only the positions L1 to L6 are shown, but not the stators and the indexing device designed as an inductive sensor.

[0056] Today’s torque sensors are fundamentally based on the Figure 1 and 2described principles or on the principles with magnetic blinds also outlined above. A component of a modern power steering system is a so-called torsion bar, which twists when a torque is applied. The two ends of the torsion bar are often referred to as the "input shaft" and "output shaft" (or also as the input side and output side). In today's technologies, which are sometimes also referred to as CIPOS structures, a multilayer printed circuit board (PCB), such as those used in relation to Figure 2As described above, several measurement channels are housed. Specifically, layers L1 and L2 implement measurement channels that measure the angle of the input shaft, layers L3 and L4 are shielding layers, and layers L5 and L6 contain measurement channels for measuring the angle of 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 the driver exerts on the steering wheel.

[0057] Specifically, CIPOS sensors are designed with an eighteen-blade CIPOS sensor (IS) with an eighteen-blade rotor (IS-R) with an unambiguous range of 360° / 18=20° on the input shaft side, and a nine-blade rotor (OS-R) with an absolute measuring range of 40° on the output shaft side. The rotors with the nine (or eighteen) blades are constructed, among other things, from metal stamped and bent parts, from plastic parts containing electrically conductive surfaces, or from overmolded stamped parts.

[0058] The information in relation to Figure 1 and 2The details described describe an inductively operating angle sensor. With such an angle sensor, it is difficult to distinguish a specific angle of rotation from one that has been rotated by a full rotation. Therefore, the idea was to use indexing as soon as a full rotation has been reached.

[0059] For this purpose, the idea was to modify the rotor surfaces by exposing them to make them distinguishable. The rotor surfaces modified by exposing them make it possible to distinguish between solid rotor blades and hollow blades. For example, a modified blade can be distinguished from the other blades, and indexing can occur as soon as the modified blade has moved a full rotation. This means that the rotor of an angle detection device for detecting an angular position of the rotating part relative to a reference position also serves for indexing during a predetermined rotation, preferably a 360° rotation, of the rotating part relative to the reference position using the indexing device.

[0060] The one relating to Figure 1 and 2The inductive sensor (CIPOS) described above primarily uses the outer contour of a blade rather than the surface itself. For inductive position detection (CIPOS), solid surfaces generally tend to be negative, as eddy currents can develop freely. The hollow and solid blade designs therefore present an inductive asymmetry, albeit a slight one, which is detrimental to the measurement. New implementations are therefore desirable.

[0061] The idea so far has been to modify the surface of a single rotor blade by removing it, making it distinguishable from the other rotor blades. The surface modified by removing it makes the solid rotor blade and the hollow blade distinguishable. This means that the idea was to provide a single marked blade. When this single marked blade reaches a full rotation, the indexing switches.

[0062] Figure 3ashows a rotor of a capacitive position detection device and / or a rotation angle sensor with such a capacitive position detection device. The basic structure of the rotation angle sensor can be compared to the basic structure of the inductive sensor from Figure 1 However, alternative designs are also possible, for example torque sensors with a magnetic blind. In the following, with reference to the Figures 3a to 3d a structure of the rotor of a capacitively acting position detection device and / or of a rotation angle sensor with such a position detection device is described.

[0063] The capacitive position detection device has at least one stator (see example stator 200 in Figure 3c), at least one rotor 100 and an evaluation unit. The at least one stator 200 can be arranged stationary relative to a rotating element. This means that when the rotating element rotates, the stator does not rotate 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. This means that when the rotating element rotates, the rotor 100 rotates 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, a plurality of rotor blades 120a, 120b extending radially outward from the base body 110. A plurality of first rotor blades 120a and a plurality of second rotor blades 120b are provided as the plurality of rotor blades 120a, 120b. The plurality of first rotor blades 120a and the plurality of second rotor blades 120b are designed differently from one another.In other words, the plurality of first rotor blades 120a of the plurality of rotor blades 120a, 120b are configured differently from the plurality of second rotor blades 120b of the plurality of rotor blades 120a, 120b. The evaluation unit is configured to detect when the plurality of first rotor blades 120a reach, have reached, or exceed a predetermined angle of rotation.

[0064] The Rotor 100 of the Figure 3acan, for example, have a rotor carrier (not shown). The rotor carrier can be designed to carry the base body 110 and thus the rotor blades 120a, 120b. For example, the rotor carrier and the rotor blades 120a, 120b can be firmly connected to one another. The rotor carrier can comprise a metal or be made of a metal. Additionally or alternatively, the rotor carrier can comprise a plastic or be made of a plastic. However, the rotor carrier can also be omitted. The base body 110 can comprise a metal or be made of a metal. Additionally or alternatively, the base body 110 can comprise a plastic or be made of a plastic. In the example from Figure 3aThe base body 110 is made of a metal, for example. The rotor blades 120a, 120b may comprise a metal or be made of a metal. Additionally or alternatively, the rotor blades 120a, 120b may comprise a plastic or be made of a plastic. In the example from Figure 3a The rotor blades 120a, 120b are made of a metal, for example.

[0065] In principle, a capacitive sensor uses the surface of a rotor blade. This surface is, so to speak, the surface or part of the capacitor surface. The inductive sensor (CIPOS) primarily uses the outer contour of a blade and not the surface itself. A torsion bar is assumed to be the rotating element in the following.

[0066] In the example from Figure 3aThe rotor 100 has nine rotor blades 120a, 120b. A different number of rotor blades 120a, 120b is conceivable and possible, for example, eighteen rotor blades 120a, 120b for the input shaft (for the input side). Of the nine rotor blades 120a, 120b, three are designed as first rotor blades 120a, for example. Of the nine rotor blades 120a, 120b, six are designed as second rotor blades 120b, for example. In the example from Figure 3a The first rotor blades 120a are identical to each other. In the example from Figure 3a The second rotor blades 120b are identical to each other. The first rotor blades 120a differ from the second rotor blades 120b. In the example from Figure 3athe first rotor blades 120a have at least partially or in sections a recess or opening. The recess or opening can completely penetrate the first rotor blade 120a, but can also be arranged only on one side, for example an underside, of the first rotor blades 120a. Due to the recesses or openings in the first rotor blades 120a, the first rotor blades 120a are also referred to as partially hollow or simply as hollow blades 120a. Furthermore, in the example from Figure 3athe second rotor blades 120b are completely filled and can therefore also be referred to as solid blades 120b. Alternatively, the first rotor blades 120a can be designed as solid blades and the second rotor blades 120b as hollow blades. In addition or as an alternative to the previously mentioned design possibilities, it is conceivable that the area of ​​the first rotor blades 120a differs from the area of ​​the second rotor blades 120b. The first rotor blades 120a can, for example, be larger (see the embodiment from Figure 3d ) or wider than the second rotor blades 120b. Alternatively, the first rotor blades 120a may be shorter or narrower than the second rotor blades 120b.

[0067] The different design of the first rotor blades 120a (for example according to Figure 3a or according to Figure 3d) in comparison to the second rotor blades 120b leads to a type of marking of the first rotor blades 120a with respect to the second rotor blades 120b, i.e. the first rotor blades 120a can be distinguished from the second rotor blades 120b. In other words, the first rotor blades 120a can be distinguished from the second rotor blades 120b on the basis of their different design. If the first rotor blades 120a are each identical, they cannot, however, be distinguished from one another on the basis of their design. This would result in indexing taking place, e.g. a counter being incremented, not only when a specific one of the first rotor blades 120a reaches an index position, but also when another of the identical first rotor blades 120a passes the detection location. As a result, the counter would be incremented incorrectly and, more precisely, far too frequently.

[0068] Therefore, the rotor blades 120a, 120b are coded in a manner that enables more precise differentiation. More specifically, coding is performed in such a way that a first rotor blade 120a / a single first rotor blade 120a or the entirety of the first rotor blades 120a or reaching the index position by the one / single first rotor blade 120a or the entirety of the multiple first rotor blades can be clearly detected. For example, a complete rotation of 360° of the one / single first rotor blade 120a of the multiple first rotor blades 120a can be detected, and after each complete rotation, switching can occur, i.e., the index counter can be incremented.

[0069] For this purpose, a special, not arbitrary coding of the rotor blades 120a, 120b of the capacitively scanned position sensor is provided, which is intended to generate a switching signal at a specific position (index position) over a circumference of 360°. This switching signal is also referred to as an index signal. If such index signal switches are designed in such a way that an individual rotor blade has a marking, the implementation of the indexing is easy to understand. If the marking is designed as a hollow blade (see Figure 3a ) or as an extended wing (see Figure 3d ), the capacitive coupling emanating from this marked wing is compared with the capacitive coupling of a solid wing (see Figure 3a ) or shortened rotor blade (see Figure 3d ). The marked rotor blade can be identified / detected from the different capacitive coupling.

[0070] The use of only a single marked wing is not optimal, as only a single wing contributes to the evaluation. Therefore, coding as a pattern or sequence of marked and unmarked wings is proposed here. It is important that the index signal is generated only once per 360° rotation at a predetermined location (index point or index position). For this to work, the coding must be highly irregular, i.e., it must not exhibit any symmetrical structures or geometric repetitions. What is meant by irregular coding will now be explained before a concrete implementation of the coding is described.

[0071] The coding proposed here is based on codes belonging to the class of so-called pseudo-random noise (PRN) sequences. Important technical applications of these codes can be found in communications engineering for signal modulation and satellite-based navigation, such as GPS. Ternary codes are frequently used in mathematical descriptions and for communications applications. In this context, ternary means that the code has three states per position (bit), denoted by +1, -1, and 0.

[0072] For the present application of coding in a position sensor, however, the codes are reduced to binary codes. Each bit of the code can assume the states 0 or 1. For example, 0 is assumed to correspond to an unmarked vane and 1 to a marked vane. This assignment can also be reversed. All codings have a length n, which in the case described here corresponds to the number of vanes of the position sensor. After the length n, the code repeats.

[0073] The properties and effectiveness of the coding used can be examined by mathematically convolving the code with itself. This process is also known as the auto-correlation function (ACF) method. Figuratively speaking, the code is written twice, one under the other, multiplied bit by bit, and then the sum is calculated. The code is then shifted one place to the right. The empty space created on the left is filled with the bit shifted out to the right in a rolling manner. The bit-by-bit multiplication and summation of all bits is carried out again. The code is shifted according to its length n. In other words, imagine an initially random-looking sequence of 0, 1 or -1, +1 as a sequence. Two identical codes are written under each other and the result is calculated by multiplying the two code values ​​in each column and then calculating the sum as a number using the result in the sequence.Now you move the code below one place and repeat the process.

[0074] Good codings exhibit the largest possible value at only one position (without shifting the bits) and the smallest possible value for each shift performed. Another special property that can be used here is demonstrated by the codings of the mathematician Barker and the Baker codes named after him. For these codes, the same result is always obtained for all shifts, and only the unshifted code exhibits a "boost." However, the lengths of Barker codes are limited. Apart from the trivial codes <7, only Barker codes of lengths 7, 11, and 13 are known. In detail, the 7-bit Barker code increases from 2 to 4 at the index point, which corresponds to a doubling of the signal amplitude. The 11-bit Barker code increases from 2 to 5, i.e., an amplification of 2.5. The Barker codes of lengths 7 and 11 are as follows: Barker code of length 7: 1 1 1 0 0 1 0 Barker code of length 11: 1 1 1 0 0 0 1 0 0 1 0

[0075] Barker codes only produce a high value when the two codes are exactly on top of each other. For all shifted codes, the value is comparatively small, but the Barker code has the unique feature that this small value is always the same regardless of the shift. These Barker codes, Barker-7 Bit or Barker-13, therefore produce good results.

[0076] However, the rotor 100 has nine blades and not seven or thirteen, so these codes are not suitable for the problem at hand and therefore only serve for understanding.

[0077] The coding can be used for the steering angle and torque sensors described above (also known as TAS: Torque & Angle Sensor). Regarding the functionality of the TAS sensors, please refer to the above explanations.

[0078] As previously described, one of the rotors of these sensors is currently designed with nine blades. The unique measuring range of 40° resulting from nine blades, and half of this at 20° (for rotors with 18 blades), is typical for the torsion measuring ranges of the torsion bars used in the sensor and their torsional stiffness. Therefore, a 9-bit coding is required for nine blades. Such a coding, with its advantageous properties described in more detail below, is referred to as EX9 and is coded as EX9: 0 1 0 0 1 0 0 0 1

[0079] The EX9 coding shows a very favorable and advantageous behavior regarding the AKF, which is at least very close to that of a Barker code. This results in a typical graphical progression of the AKF as shown in Figure 3bis shown schematically, whereby only the shifts by whole digits were considered. The favorable, advantageous property of this coding is that it has a result of 1 over large areas outside the index point. In the vicinity of the index point, the result is initially 0 and then increases in the correlation peak to a value of 3. The switching edge resulting from 0 to 3 is therefore particularly steep, which can contribute to improved switching accuracy. In other words, the peak at the value of 3, together with the value of 0 directly around the index point, means that the coding enables very good detectability of the one / only first rotor blade of the plurality of first rotor blades 120a at the index position.

[0080] The coding triples the amplitude. Therefore, effective signal amplification can be achieved with the EX9 coding for the capacitive evaluation of an arrangement of marked rotor blades 120a and unmarked rotor blades 120b of a position sensor with a switching function. Compared to a design with only a single marked blade, not just one but multiple blades contribute to the evaluation. This significantly increases the signal amplitude, making the function of such a sensor more robust and precise.

[0081] More details become clear when looking at the Stator 200 from Figure 3c. The code 100101000 is also implemented on the stator 200, which can also be read the other way around (000101001 or 010010001), depending on which side of the rotor 300 is facing the top side of the stator 200. In other words, the stator 200 has various segments that describe or implement the code mentioned. In the Figure 3c On the stator 200, starting at the 9:00 o'clock position, there are three segments 220a corresponding to 1 and six segments 220b corresponding to 0. Likewise, on the rotor 100, there are three first rotor blades 120a (hereinafter partly referred to as hollow blades 120a) corresponding to 1 and six second rotor blades 120b (hereinafter partly referred to as solid blades 120b) corresponding to 0. It is assumed that the Figure 3c a top side of the stator 200, the Figure 3a and 3deach show an underside or a view of the underside of the rotor 300. It is important in this context that the rotor 300 and the stator 200 are coordinated such that there is a position in which the first rotor blades 120a (the entirety of the first rotor blades 120a) completely overlap the segments 220a (the entirety of the segments 220a).

[0082] The nine segments of the receiver, which receive the coding of the rotor 100, are located on the stator 200. The three segments 220a are connected together, for example, to form a first capacitance or a first capacitor. For example, the three segments 220a are connected in parallel to one another, forming a capacitance bank and thus adding together. The six segments 220b are connected together, for example, to form a second capacitance or a second capacitor. For example, the three segments 220b are connected in parallel to one another, forming a capacitance bank and thus adding together. The two capacitance banks thus formed are connected, for example, in series to form a differential capacitor. For example, the respective capacitances or capacitors are formed from the interaction of the respective rotor 100, in particular the rotor blades of the rotor 100, and the stator 200, in particular the segments of the stator 200.

[0083] The code "matches" at the index switching point when the three hollow vanes 120a are positioned exactly above the three detector segments 220a. At this point, the capacitance is three times smaller due to the three hollow vanes 120a, and the capacitance occurring over rotation is the largest at the six solid vanes 220b above the second capacitor bank. When the rotor 100 rotates relative to the stator, the overlap of the rotor vanes 120a, 120b relative to the segments 220a, 220b changes. More precisely, the overlap decreases. Consequently, the capacitance decreases.

[0084] The coding is such that the switching signal still occurs only once at the index point over the 360°. However, since all nine vanes now contribute, rather than just a single one, the signal amplitude is amplified by a factor of 3. This is much easier to evaluate, especially with the weak signals and small capacitances used.

[0085] More specifically, using a rotor 100 coded with the EX9 coding, the evaluation unit can always clearly detect that the one / only first rotor blade of the plurality of first rotor blades 120a or the entirety of the first rotor blades 120a of the plurality of first rotor blades 120a has reached (or has reached) the index position. In this case, the evaluation unit can be configured to detect when the one / only first rotor blade of the plurality of first rotor blades 120a or the entirety of the first rotor blades 120a of the plurality of first rotor blades 120a reaches or exceeds the index position. When the one / only first rotor blade of the plurality of first rotor blades 120a or the entirety of the first rotor blades 120a of the plurality of first rotor blades 120a reaches or exceeds the index position, the evaluation unit can output a switching signal. For example, a counter can be incremented by the switching signal.This allows not only rotation angles up to 360° to be uniquely determined, but also any rotation angle by counting complete revolutions. In this way, for example, the angle of rotation relative to . Figure 2 The indexing means described (which can also be referred to as indexing component or indexing device) can be implemented as a capacitive sensor. For example, on the layers L3 and L4 of the printed circuit board made of Figure 2 the indexing component or indexing device designed as a capacitive sensor can be arranged.

[0086] In general, the evaluation unit can be configured to determine a rotation angle of the rotor or of the first rotor blades 120a. The at least one rotor can be configured as two rotors. A first of the two rotors can be arranged on the input shaft (the input side), and a second of the two rotors can be arranged on the output shaft (the output side). The evaluation unit can determine the rotation angle of both rotors and calculate the difference between the two rotation angles to determine a differential angle. From the differential angle, the evaluation unit can determine a torque acting on the torsion bar.

[0087] In Figure 3d Another example of how the first rotor blades 120a can be configured to be distinguishable from the second rotor blades 120b can be seen. In this example, the first rotor blades 120a are larger than the second rotor blades 120b. Other configurations than those in Figure 3a and 3d are conceivable.

[0088] The rotor from the Figure 3a and 3d exhibits a certain asymmetry. Alternatively, the rotor can also be designed symmetrically. This allows it to be optimally used for inductive solutions. This means that its metallically conductive blades can also be used as an inductive position sensor (CIPOS).

[0089] The evaluation unit can be designed to detect when the three first rotor blades 120a reach, have reached, or exceed 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 the plurality of first rotor blades 120a reach, have reached, or exceed the predetermined rotational position. This can be the case, in particular, once per complete revolution. 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°. As a result, predetermined rotational angles, such as partial or complete revolutions, can be counted / indexed. In this way, for example, the Figure 2The indexing means described (which can also be referred to as indexing component or indexing device) can be implemented as a capacitive sensor.

[0090] The information in relation to Figures 3a to 3d The described configurations serve to create a capacitive switch. The capacitive switch can be combined with the inductive angle detection, as described in relation to Figure 1described. For example, the evaluation unit can determine the angle of rotation of the rotor (up to a complete revolution of 360°) taking into account inductive coupling. By also taking the value of the counter into account, the total rotation of the rotor with values ​​over 360° can be efficiently determined. In a sense, a capacitive switch is combined with an inductive angle of rotation determination. In this way, an inductive angle of rotation determination can be optimally combined with a capacitive switch at a predetermined rotational position (for example, at 40° or 360°). This means that the switch with metallically conductive blades can be used as an inductive position sensor (CIPOS).

[0091] According to one example, the largest uniqueness range lies on the side of the nine rotor blades and is therefore 360° / 9=40°. In this case, the index switch detects straight-ahead travel even under plausibility checks. The counter then counts as soon as a predetermined rotational position, for example, an angle segment of 40°, is reached or exceeded (i.e., the over-laps of the 40° track are counted). The steering angle is thus steering angle = n*40° + measured angle of the rotation angle sensor (e.g., CIPOS) within the 40° segment.

[0092] In other words, according to this example, it is detected when an angular segment (of e.g. 40°) is reached or exceeded. As soon as the angular segment is reached or exceeded, the counter is incremented or decremented depending on the direction of the excess. This counter operates capacitively. If, for example, five angular segments have been reached or exceeded, an approximate angle of rotation of 5*40°=200° can be determined using the counter. The exact steering angle can be determined using the inductively operating angle of rotation determination device. For example, if an angle of 12° is determined using the angle of rotation determination device, the resulting steering angle is 5*40°+12°=212°.

[0093] This means that capacitive modulation for a capacitive sensor or switch operating in parallel with an inductive sensor, for example, is achieved by designing the rotor in such a way that the rotor blades are coded between the rotor and stator of the angle sensor or angle switch. This allows individual rotor blades that require coding to be distinguished from other blades that do not.

[0094] With the described implementation, the sensor's signal amplitude can be increased by arranging a special pattern or sequence (coding) of marked and unmarked vanes. At the same time, the switching point can still be ensured only once over the entire 360° circumference. The improvement compared to a variant with only a single marked vane can be achieved by having not just one but several vanes contribute to the evaluation. This significantly increases the signal amplitude, making the function of such a sensor more robust and precise.

Claims

1. Position detection device for a rotation angle sensor, wherein the position detection device features: at least one stator (200); at least one rotor (100), wherein the at least one rotor (100) features a base body (110) and several rotor blades (120a, 120b) extending radially outwards from the base body (110), wherein several first rotor blades (120a) of the several rotor blades (120a, 120b) are designed so as to differ from several second rotor blades (120b) of the several rotor blades (120a, 120b); and an evaluation unit that is designed to record when the several first rotor blades (120a) reach, have reached or exceed, a predefined rotation angle.

2. Position detection device in accordance with claim 1, wherein the evaluation unit is designed to record when the entirety of the several first rotor blades (120a) reaches, has reached or exceeds a predefined rotation angle.

3. Position detection device in accordance with claim 1 or 2, wherein the several first rotor blades (120a) feature a different shape and / or a different surface than the several second rotor blades (120b).

4. Position detection device in accordance with one of claims 1 through 3, wherein the several first rotor blades (120a) are designed as hollow blades and the several second rotor blades (120b) as full blades; or the several first rotor blades (120a) are designed as full blades and the several second rotor blades (120b) as hollow blades.

5. Position detection device in accordance with one of claims 1 through 4, wherein the several first rotor blades (120a) are designed to be longer than the several second rotor blades (120b); or the several first rotor blades (120a) are designed to be shorter than the several second rotor blades (120b).

6. Position detection device in accordance with one of claims 1 through 5, wherein the several first rotor blades (120a) and the several second rotor blades (120b) are arranged in a predefined sequence relative to each other.

7. Position detection device in accordance with claim 6, wherein the number of the several rotor blades (120a, 120b) is nine, the number of the several first rotor blades (120a) is three and the number of the several second rotor blades (120b) is six and wherein the predefined sequence of the several first rotor blades (120a) and the several second rotor blades (120b) relative to each other is: second rotor blade, first rotor blade, second rotor blade, second rotor blade, first rotor blade, second rotor blade, second rotor blade, second rotor blade, first rotor blade or shifts of this sequence.

8. Position detection device in accordance with one of claims 1 through 7, wherein the evaluation unit is designed to generate a switching signal when the several first rotor blades (120a) reach, have reached or exceed the predefined rotation angle.

9. Position detection device in accordance with claim 8, wherein the several first rotor blades (120a) and the several second rotor blades (120b) are arranged relative to each other in such a way that the evaluation unit can detect that the switching signal is generated only once per complete rotation of the rotor.

10. Position detection device in accordance with one of claims 1 through 9, wherein the several first rotor blades (120a) are interconnected to form a first capacitor and the several second rotor blades (120b) are interconnected to form a second capacitor.

11. Rotation angle sensor featuring: the position detection device in accordance with one of claims 1 through 10; a rotation angle detection device, featuring: the at least one stator (200); the at least one rotor (100); the evaluation unit, wherein the evaluation unit is designed to determine a rotation angle of the at least one rotor (100) relative to the at least one stator (200) starting from a reference position.

12. Rotation angle sensor in accordance with claim 11, wherein the evaluation unit is designed to determine the rotation angle of the at least rotor (100) based on an inductive coupling between the at least one rotor (100) and the at least one stator (200).

13. System featuring a rotation angle sensor in accordance with claim 11 or 12 and a rotating element, wherein the at least one stator (200) of the rotation angle sensor is arranged in a fixed position relative to the rotating element and the at least one rotor (100) is connected in a non-rotating manner to the rotating element and the evaluation unit of the rotation angle sensor is designed to determine from the determined rotation angle of the at least one rotor (100) a torque acting on the rotating element.