Absolute rotation encoder for detecting the rotational motion of a shaft
The absolute rotation encoder uses a Wiegand sensor and permanent magnet rotor unit with non-volatile storage to synchronize devices post-power cutoff, addressing cost and reliability issues in existing encoders, ensuring accurate position detection at low cost.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FRABA
- Filing Date
- 2025-03-18
- Publication Date
- 2026-07-07
AI Technical Summary
Existing absolute rotation encoders require expensive electronic equipment to synchronize the rotation counting device and angular position measuring device after power cutoff, making them costly and unreliable.
An absolute rotation encoder using a Wiegand sensor, magnetic field sensor, and permanent magnet rotor unit that generates alternating magnetic fields at the Wiegand sensor, combined with a non-volatile data storage device, allows for reliable operation without external power and low-cost manufacturing by determining the current absolute position based on stored values and sensor outputs.
Enables reliable detection of rotational motion even after power loss and reduces manufacturing costs by eliminating the need for expensive equipment to detect magnetization states, ensuring accurate position determination.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an absolute rotation encoder for detecting the rotational movement of a shaft, comprising a rotation counting device for determining a rotation count value, an angular position measuring device for determining the current angular position of the shaft, and an evaluation device having a non-volatile data storage device in which the rotation count value is stored. The rotation counting device includes a Weigand sensor, a magnetic field sensor, and a permanent magnet rotor unit designed to be attached to the shaft, and in the attached state, the permanent magnet rotor unit is designed such that an alternating magnetic field is generated at the location of the Weigand sensor during the uniform rotational movement of the shaft. The evaluation device is designed to determine the current absolute position based on the output signals of the Weigand sensor and the magnetic field sensor, the stored rotation count value, and the current angular position determined by the angular position measuring device.
Background Art
[0002] Such an absolute rotation encoder is known from Patent Document 1. In the described absolute rotation encoder, in order to synchronize the rotation counting device and the angular position measuring device, that is, to determine the correct current absolute position, after the external power supply is cut off, the magnetization state of the Weigand wire of the Weigand sensor is detected by energizing a coil surrounding the Weigand wire of the Weigand sensor. However, for this purpose, relatively expensive electronic equipment is required.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] Given this background, the challenge is to realize the type of absolute value rotation encoder mentioned earlier that operates reliably even after the external power supply is cut off and can be manufactured relatively inexpensively. [Means for solving the problem]
[0005] This problem is solved by an absolute rotation encoder for detecting the rotational motion of a shaft, having the features of claim 1, according to the present invention.
[0006] The absolute rotation encoder according to the present invention for detecting the rotational motion of a shaft includes a rotation counting device for determining the current rotation count value. Such a rotation counting device is also called a multi-turn sensor device and is basically known from the prior art. In this case, the rotation count value generally indicates the number of complete rotations performed in a given positive rotation direction since initialization. Typically, the rotation count value is increased by 1 each time the zero angular position is crossed in the positive rotation direction and decreased by 1 each time the zero angular position is crossed in the negative rotation direction opposite to the positive rotation direction. In principle, it is also conceivable that the rotation count value indicates the number of partial rotations performed in the positive rotation direction, for example, the number of half-rotations performed. However, in any case, the number of complete rotations performed can be directly and uniquely derived from the rotation count value.
[0007] An absolute rotation encoder according to the present invention for detecting rotational motion of a shaft is in particular a Wiegand sensor-based rotation counting device similarly known from the prior art, comprising a Wiegand sensor, preferably a single Wiegand sensor, a magnetic field sensor, and a permanent magnet rotor unit, wherein the Wiegand sensor and the magnetic field sensor are designed to be stationary relative to the shaft whose rotational motion is to be detected, and the permanent magnet rotor unit is designed to be mounted to rotate with the shaft whose rotational motion is to be detected, i.e., mounted such that rotational motion of the permanent magnet rotor unit inevitably occurs as a result of the rotational motion of the shaft.
[0008] A Wiegand sensor comprises a Wiegand wire and a sensor coil surrounding the Wiegand wire. Such a Wiegand sensor is also called a pulsed wire sensor and is essentially known from the prior art. The Wiegand wire generally has a hard magnetic sheath and a soft magnetic core, or vice versa. Under the influence of an external magnetic field, the magnetization direction of the Wiegand wire is abruptly reversed, thereby generating a short Wiegand voltage pulse in the sensor coil surrounding the Wiegand wire radially, which can be tapped through the sensor coil ends, i.e., both ends of the sensor coil. This effect is also called the Wiegand effect, or macroscopic Barkhausen effect or large Barkhausen effect, and is generally known.
[0009] In principle, the magnetic field sensor may be any magnetic field sensor known from the prior art, such as a Hall sensor, field plate, TMR sensor, AMR sensor, or GMR sensor.
[0010] The permanent magnet rotor unit is preferably designed to be directly fixed to the shaft, so that the permanent magnet rotor unit and the shaft always rotate at the same speed. However, in principle, the permanent magnet rotor unit may be coupled to the shaft via a transmission so that they rotate together, so that the permanent magnet rotor unit and the shaft rotate at different speeds. The permanent magnet rotor unit is designed, in known ways and embodiments, to generate an alternating magnetic field at the location of the Wiegand sensor when mounted, during uniform rotational motion of the shaft. The permanent magnet rotor unit may include, for example, a permanent magnetic ring magnet arranged around the rotation axis of the rotor unit, the permanent magnetic ring magnet having a series of magnetic north poles and magnetic south poles along its circumference. However, the permanent magnet rotor unit may also include a plurality of separate permanent magnets arranged on a circular path around the rotation axis of the rotor unit, with adjacent permanent magnets having opposite polarities. In any case, the permanent magnet rotor unit includes at least one permanent magnet.
[0011] According to the present invention, the permanent magnet rotor unit is designed such that, in its installed state, the magnetic field generated by the permanent magnet rotor unit at the location of the Wiegand sensor alternates at least four times per revolution during uniform rotational motion of the shaft, and as a result, during uniform rotational motion of the shaft, Wiegand voltage pulses are generated in the Wiegand sensor at at least four different angular positions (hereinafter referred to as trigger angular positions) per revolution. Preferably, the permanent magnet rotor unit is designed such that, in its installed state, the magnetic field generated by the permanent magnet rotor unit at the location of the Wiegand sensor alternates at a constant frequency during uniform rotational motion, and as a result, the four trigger angular positions are approximately equidistant from each other, that is, there is always an approximately equal angular distance between any two consecutive trigger angular positions.
[0012] An absolute rotation encoder according to the present invention for detecting the rotational motion of a shaft further includes an angular position measuring device for determining the current angular position of the shaft. Such an angular position measuring device is also called a single-turn sensor device and is essentially known from the prior art. In this case, the angular position indicates the rotational position of the shaft whose rotational motion is to be detected within a range of one rotation, and therefore can be 0° to 360°. The angular position measuring device includes a rotor unit designed to be mounted to rotate with the shaft whose rotational motion is to be detected, similar to the permanent magnet rotor unit of a rotation counting device, and a stator unit designed to be stationary relative to the shaft whose rotational motion is to be detected. Typically, the stator unit includes a sensor or sensing electronic device that cooperates with a passive, i.e., electrically non-contacting coding element positioned in the rotor unit to determine the angular position, the coding element being designed such that a physical characteristic detected by the sensor or sensing electronic device changes in a defined manner during the rotational motion of the rotor unit such that the current angular position can be derived from the current value of the physical characteristic. The angular position measuring device may be, for example, an optical angular position measuring device, in which the coding element includes a defined sequence of light and dark regions scanned by an optical sensor. However, in principle, the angular position measuring device may be any angular position measuring device known from the prior art, such as a magnetic angular position measuring device, a capacitive angular position measuring device, or an inductive angular position measuring device.
[0013] The absolute rotational encoder according to the present invention for detecting the rotational motion of a shaft further includes an evaluation device having a non-volatile data storage device, preferably a so-called FRAM®. In addition to the non-volatile data storage device, the evaluation device includes processing electronic equipment designed to process the output signals or output values of a rotation counting device and an angular position measuring device. The evaluation device typically includes a microcontroller, a so-called FPGA, or other type of arithmetic unit.
[0014] According to the present invention, a non-volatile data storage device stores at least a rotation count value and a rotation sector value, where the rotation sector value indicates one of a plurality of defined rotation sectors into which a complete rotation is divided by the evaluation logic. In this case, each rotation sector is defined such that it contains exactly one trigger angular position, i.e., each contains exactly one angular position into which a Wiegand voltage pulse is generated in the Wiegand sensor during either a rotational motion in the positive or negative direction. Since Wiegand voltage pulses are generated at different angular positions during rotational motion in the positive and negative directions, according to the present invention, at least eight rotation sectors are identifiable, and therefore, a complete rotation is divided into at least eight rotation sectors by the evaluation logic according to the present invention.
[0015] According to the present invention, the evaluation device is designed to determine the current rotational sector value based on the current output signals of the Wiegand sensor and the magnetic field sensor, as well as the stored rotational sector value, in the presence of an external power supply. Preferably, based on the current output signals of the Wiegand sensor and the magnetic field sensor, a pulse polarity value indicating the polarity of the generated Wiegand voltage pulse and a magnetic pulse value indicating whether or not a magnetic field was detected by the magnetic field sensor at the time of the Wiegand voltage pulse are determined in a manner and manner known from the prior art. In this case, the pulse polarity value and the magnetic pulse value (in binary code form) form the last two bits of the rotational sector value. According to the present invention, since at least eight different rotational sector values must be identifiable, the bit sequence of the rotational sector value must include at least one additional bit. In this case, at least one additional bit preferably indicates a count value that is added by 1, subtracted by 1, or left unchanged, depending on the stored rotational sector value, the current pulse polarity value, and the current magnetic pulse value, based on a predetermined count logic.
[0016] According to the present invention, the evaluation device is further designed to increase, decrease, or leave unchanged the stored rotation count value according to the stored rotation sector value and the current rotation sector value, based on a predetermined rotation count logic, in the presence of an external power supply. In this case, the rotation count logic is designed so that if it can be derived from the stored rotation sector value and the current rotation sector value that the zero angle position has been crossed in the positive rotation direction, the rotation count value is increased by 1; if it can be derived from the stored rotation sector value and the current rotation sector value that the zero angle position has been crossed in the negative rotation direction, the rotation count value is decreased by 1; and if it can be derived from the stored rotation sector value and the current rotation sector value that the zero angle position has not been crossed, the rotation count value is left unchanged.
[0017] According to the present invention, the evaluation device is further designed to determine the current absolute position in a known manner and manner based on the stored rotation count value and the current angular position determined by the angular position measuring device, in the presence of an external power supply, and to store the current rotation sector value in a non-volatile data storage device after processing.
[0018] According to the present invention, the evaluation device is further designed to synchronize the rotation count device and the angular position measuring device after the external power supply is cut off, by adjusting the rotation count value stored in the non-volatile data storage device as needed.
[0019] In particular, according to the present invention, the evaluation device is designed to determine the switch-on rotation sector value based on the current angular position determined by the angular position measuring device after the external power supply is cut off. The switch-on rotation sector value represents the value of the rotation sector, which is divided by the evaluation logic, where the current angular position determined by the angular position measuring device is located.
[0020] According to the present invention, the evaluation device is further designed to increase, decrease, or leave unchanged the determined current absolute position based on a predetermined synchronization logic after the external power supply is cut off, according to the determined switch-on rotational sector value and the rotational sector value stored in the non-volatile data storage device. In this case, the synchronization logic is designed so that, in determining the current absolute position, if it can be derived from the switch-on rotational sector value and the stored rotational sector value that the zero-angle position was crossed in the positive rotational direction while the external power supply was cut off, the rotational count value is increased by 1; if it can be derived from the switch-on rotational sector value and the stored rotational sector value that the zero-angle position was crossed in the negative rotational direction while the external power supply was cut off, the rotational count value is decreased by 1; and if it can be derived from the switch-on rotational sector value and the stored rotational sector value that the zero-angle position was not crossed while the external power supply was cut off, the rotational count value is left unchanged. Alternatively, the synchronization logic may also be designed to either increase, decrease, or keep unchanged the predetermined current absolute position by one full rotation, instead of increasing, decreasing, or keeping unchanged the rotation count value when determining the current absolute position.
[0021] Therefore, the absolute value rotation encoder according to the present invention makes it possible to determine the correct current absolute position without the need to separately detect the magnetization state of the Wiegand wire by energizing the coil surrounding the Wiegand wire of the Wiegand sensor after the external power supply has been cut off. This makes it possible to realize an absolute value rotation encoder for detecting the rotational motion of a shaft that operates reliably even after the external power supply has been cut off and can be manufactured at a relatively low cost.
[0022] In a preferred embodiment, the permanent magnet rotor unit includes a rotor plate and at least four permanent magnets fixed to the rotor plate, whereby the permanent magnet rotor unit can be manufactured at a relatively low cost. Further, a coding element of the angular position measuring device can also be arranged on the rotor plate, so that there is no need to provide an additional support element for the coding element of the angular position measuring device.
[0023] Preferably, the permanent magnet rotor unit is designed such that, in the attached state, during the uniform rotational movement of the shaft, the magnetic field generated at the location of the Weigand sensor alternates exactly 4 times per rotation. This enables the realization of a permanent magnet rotor unit that can be manufactured particularly inexpensively.
[0024] Preferably, the permanent magnet rotor unit is designed to be attached to the outer peripheral surface of the shaft, so that the permanent magnet rotor unit can be attached to both solid shafts and hollow shafts. This enables the realization of an absolute value rotary encoder that can be used particularly widely.
[0025] In a preferred embodiment, the magnetic field sensor is a so-called TMR sensor, which is relatively inexpensive and requires relatively little electrical energy for its operation.
[0026] Preferably, the absolute value rotary encoder is designed such that, in the attached state, the Weigand sensor and / or the magnetic field sensor are arranged adjacent to each other in the axial direction with respect to the permanent magnet rotor unit. This enables the realization of an absolute value rotary encoder that requires only a relatively small radial installation space.
[0027] Preferably, the angular position measuring device is a capacitive angular position measuring device that requires relatively little electrical energy for its operation. The capacitive angular position measuring device includes at least two asymmetrically formed electrodes designed such that the capacitance between the two electrodes changes as the electrodes are rotated relative to each other.
[0028] Embodiments of the present invention will be described below based on the accompanying drawings.
Brief Description of the Drawings
[0029] [Figure 1] A cross-sectional view of an absolute rotation encoder according to the present invention for detecting the rotational movement of a shaft is schematically shown. [Figure 2] An evaluation device and a data interface of the absolute rotation encoder of FIG. 1 are schematically shown. [Figure 3] The rotor unit of the absolute rotation encoder of FIG. 1 is schematically shown, and different angular positions of the rotor unit are indicated by the respective positions of the Weigand sensors arranged on the stator unit. [Figure 4] A bit string of distinguishable states of the rotation sector values processed by the evaluation device of the absolute rotation encoder of FIG. 1 is shown. [Figure 5] The partial rotation count logic stored in the evaluation device of the absolute rotation encoder of FIG. 1 for determining the partial rotation count value of the bit string of the rotation sector values of FIG. 4 is shown in tabular form. [Figure 6] The rotation count logic stored in the evaluation device of the absolute rotation encoder of FIG. 1 for determining the rotation count value in the presence of an external power supply is shown in tabular form. [Figure 7] The synchronization logic stored in the evaluation device of the absolute rotation encoder of FIG. 1 for determining the rotation count value after the external power supply is cut off is shown in tabular form.
Modes for Carrying Out the Invention
[0030] Figure 1 schematically shows an absolute rotation encoder 100 according to the present invention for detecting the rotational motion of a shaft 101 in an installed state, wherein the shaft 101 is formed as a hollow shaft and is driven by a drive motor 102.
[0031] The absolute value rotary encoder 100 includes an annular disc-shaped rotor plate 1 that surrounds the shaft 101 radially and is directly fixed to the outer circumferential surface 101.1 of the shaft 101, and therefore rotates together with the shaft 101.
[0032] The absolute value rotary encoder 100 further includes a stator plate 2, which is fixed to the housing 102.1 of the drive motor 102 via a plurality of fixing means 103 and is therefore positioned stationary relative to the shaft 101.
[0033] The absolute value rotation encoder 100 further includes a magnet-based rotation counting device 3 for determining the current rotation count value U, the rotation counting device 3 comprising a Wiegand sensor 3.1, a magnetic field sensor 3.2 designed as a TMR sensor, a rotor plate 1, and a permanent magnet rotor unit 3.3 formed by four permanent magnets 3.3.1 to 3.3.4 mounted on the rotor plate 1.
[0034] The Wiegand sensor 3.1 and the magnetic field sensor 3.2 are arranged on the stator plate 2 adjacent to the permanent magnet rotor unit 3.3 in the axial direction, and the Wiegand sensor 3.1 and the magnetic field sensor 3.2 are arranged adjacent to each other in the circumferential direction of the shaft 101.
[0035] In this configuration, the Wiegand sensor 3.1 is positioned such that its Wiegand wire 3.1.1 extends radially along the shaft 101.
[0036] The permanent magnets 3.3.1 to 3.3.4 are designed as diametrically magnetized disk magnets and are arranged on the rotor plate 1 such that their magnetization directions extend substantially parallel to the radial direction of the shaft 101, i.e., their magnetic poles N and S are adjacent to each other in the radial direction, while adjacent excitation magnets 1.2a to 1.2d in the circumferential direction of the shaft 101 have opposite magnetization directions.
[0037] Therefore, the permanent magnet rotor unit 3.3 generates a magnetic field at the location of the Wiegand sensor 3.1 during the uniform rotational motion of the shaft 101, and this magnetic field alternates exactly four times per revolution of the shaft 101, i.e., changes its polarity exactly four times.
[0038] The absolute value rotation encoder 100 further includes a capacitive angular position measuring device 4 for determining the current angular position W, the angular position measuring device 4 comprising a rotor electrode configuration 4.1 arranged around the shaft 101 and on the rotor plate 1, a stator electrode configuration 4.2 arranged around the shaft 101 and on the stator plate 2, and measuring electronic equipment 4.3 arranged on the stator plate 2.
[0039] The absolute rotation encoder 100 further includes an evaluation device 5, which comprises a non-volatile data storage device 5.1 designed as FRAM (registered trademark) that stores the current rotation count value U and rotation sector value US-g, and an arithmetic unit 5.2 that stores partial rotation count logic 5.2.1, rotation count logic 5.2.2, synchronization logic 5.2.3, and absolute position determination logic 5.2.4.
[0040] The absolute rotation encoder 100 further includes a data interface 6 through which data from the absolute rotation encoder 100, in particular the determined current absolute position AP, can be read from the outside.
[0041] The stored rotational sector value US-g, the current rotational sector value US-a (as described later), and the switch-on rotational sector value US-e (as described later) are each 3-bit values, where the last bit indicates the pulse polarity value PP, the middle bit indicates the magnetic pulse value MP, and the first bit indicates the partial rotation count value TW.
[0042] The rotation sector values US-g, US-a, and US-e (hereinafter generally referred to simply as US) can each represent eight different states P1-P4 and N1-N4, also shown in Figure 4, each having the bit sequence shown in Figure 4, and each state is assigned a unique angular position range with a width of 360° / 8 = 45°.
[0043] In this case, states P1 to P4 and N1 to N4 are each assigned to a trigger angular position, i.e., the angular position of the permanent magnet rotor unit 3.3 in which a Wiegand voltage pulse is generated within the Wiegand sensor 3.1, as schematically shown in Figure 3. States P1 to P4 correspond to the trigger angular position during rotation in the positive rotation direction Dp, and states N1 to N4 correspond to the trigger angular position during rotation in the negative rotation direction D-n, which is opposite to the positive rotation direction Dp.
[0044] For simplicity, in Figure 3, different trigger angle positions of the permanent magnet rotor unit 3.3 are shown by rotations opposite to the rotation directions Dp and Dn of the Wiegand sensor 3.1 and magnetic field sensor 3.2, respectively, starting from the zero angle position W0. Therefore, rotation of the permanent magnet rotor unit 3.3 in the positive rotation direction Dp is shown by rotation of the Wiegand sensor 3.1 and magnetic field sensor 3.2 in the negative rotation direction Dn, and vice versa.
[0045] The evaluation device 5 is designed to determine, in the presence of an external power supply, in known methods and manner, the current pulse polarity value PP, which indicates the polarity of the last Wiegand voltage pulse generated in the Wiegand sensor 3.1, and the current magnetic pulse value MP, which indicates whether or not a magnetic field was detected by the magnetic field sensor 3.2 at the time of the Wiegand voltage pulse, based on the output signals of the Wiegand sensor 3.1 and the magnetic field sensor 3.2.
[0046] The evaluation device 5 is further designed to determine the current rotational sector value US-a based on the stored rotational sector value US-g, the current magnetic pulse value MP, and the current pulse polarity value PP, in the presence of an external power supply.
[0047] In this process, based on the partial rotation count logic 5.2.1 shown in tabular form in Figure 5, it is determined whether the partial rotation count TW of the stored rotation sector value US-g should be increased by 1 (+1), decreased by 1 (-1), or remain unchanged (0), depending on the stored rotation sector value US-g, the current magnetic pulse value MP, and the current pulse polarity value PP. This determines the current partial rotation count value TW, and therefore the current rotation sector value US-a obtained from the current partial rotation count value TW, the current magnetic pulse value MP, and the current pulse polarity value PP.
[0048] The evaluation device 5 is further designed, in the presence of an external power supply, to increase (+1), decrease (-1), or leave unchanged (0) the rotation count value U stored in the non-volatile data storage device 5.1, based on the rotation count logic 5.2.2 shown in tabular form in Figure 6, according to the stored rotation sector value US-g and the predetermined current rotation sector value US-a.
[0049] The evaluation device 5 is further designed, in the presence of an external power supply, to determine the current absolute position AP in a known manner and manner by absolute position determination logic 5.2.4 based on the stored rotation count value U and the current angular position W determined by the angular position measuring device 4, and the absolute position AP can then be read via the data interface 6.
[0050] The evaluation device 5 is further designed to store the current rotational sector value US-a after processing in a non-volatile data storage device 5.1 in the presence of an external power supply, that is, to replace the stored rotational sector value US-g with the current rotational sector value US-a.
[0051] The evaluation device 5 is further designed to perform synchronization between the rotation counting device 3 and the angular position measuring device 4 after the external voltage supply is cut off.
[0052] The evaluation device 5 is designed to determine the switch-on rotation sector value US-e based on the current angular position W determined by the angular position measuring device 4 after the external voltage supply is cut off, by specifically checking which of the angular position ranges assigned to eight states P1-P4 and N1-N4 the current angular position W is in.
[0053] The evaluation device 5 is further designed so that, after the external voltage supply is cut off, based on the synchronization logic 5.2.3 shown in tabular form in Figure 7, it either increases (+1) the current absolute position AP, which is predetermined by the absolute position determination logic 5.2.4, by a full rotation (+1), decreases (-1) the current absolute position AP, which is predetermined by the absolute position determination logic 5.2.4, by a full rotation (+1), decreases (-1) the current absolute position AP, or remains unchanged (0), or increases (+1) the stored rotation count value U by 1, decreases (-1), or remains unchanged (0) when determining the current absolute position AP. [Explanation of symbols]
[0054] 100 Absolute value rotation encoder 1 Rotor Plate 2 Stator Plate 3. Rotation counting device 3.1 Wiegand Sensor 3.1.1 Weegand Wire 3.2 Magnetic field sensors 3.3 Permanent Magnet Rotor Unit 3.3.1 Permanent Magnets 3.3.2 Permanent Magnets 3.3.3 Permanent Magnets 3.3.4 Permanent Magnets 4 Angular position measuring device 4.1 Rotor electrode configuration 4.2 Stator Electrode Configuration 4.3 Measurement electronics 5. Evaluation device 5.1 Non-volatile data storage devices 5.2 Processing Units 5.2.1 Partial Rotation Counting Logic 5.2.2 Rotation Counting Logic 5.2.3 Synchronization Logic 5.2.4 Absolute Position Determination Logic 6. Data Interface 101 Shaft 101.1 Outer surface 102 Drive motor 102.1 Housing 103 Fixing means AP Absolute Position Dn Negative rotation direction Dp is the positive direction of rotation. MP Magnetic Pulse Value P1~P4 Rotation sector values for the positive direction of rotation N1~N4 Rotation sector values for negative rotation direction PP pulse polarity value TW Partial Rotation Count Value U Rotation count value US-a Current Rotation Sector Value US-g Stored rotational sector value US-e Switch-on Rotation Sector Value W angular position W0 Zero Angle Position
Claims
1. An absolute rotation encoder (100) for detecting the rotational motion of a shaft (101), A rotation counting device (3) for determining the rotation count value (U), Wiegand sensor (3.1) and Magnetic field sensor (3.2) and A permanent magnet rotor unit (3.3) is designed to be mounted to rotate together with the shaft (101), and in the mounted state, the permanent magnet rotor unit (3.3) is designed to generate a magnetic field at the location of the Wiegand sensor (3.1) that alternates at least four times per revolution during the uniform rotational motion of the shaft (101), and A rotational counting device (3) having, An angular position measuring device (4) for determining the current angular position (W) of the shaft (101), An evaluation device (5) having a non-volatile data storage device (5.1) storing the rotation count value (U) and the rotation sector value (US-g), wherein the rotation sector value (US-g) indicates one of a plurality of defined rotation sectors into which a complete rotation is divided by the evaluation logic, In the presence of an external power source, Based on the output signals of the Wiegand sensor (3.1) and the magnetic field sensor (3.2), and the stored rotational sector value (US-g), the current rotational sector value (US-a) is determined. Depending on the stored rotational sector value (US-g) and the current rotational sector value (US-a), the stored rotational count value (U) is increased, decreased, or left unchanged. Based on the stored rotation count value (US-g) and the current angular position (W) determined by the angular position measuring device (4), the current absolute position (AP) is determined. The current rotational sector value (US-a) after processing is stored in the non-volatile data storage device (5.1). Designed to, After the external power supply is shut off, Based on the current angular position (W) determined by the angular position measuring device (4), the switch-on rotation sector value (US-e) is determined, and the switch-on rotation sector value (US-e) represents the value of the rotation sector in which a complete rotation is divided by the evaluation logic, where the current angular position (W) determined by the angular position measuring device (4) exists. Depending on the determined switch-on rotational sector value (US-e) and the stored rotational sector value (US-g), the determined current absolute position (AP) is increased, decreased, or left unchanged. An evaluation device (5) designed for this purpose, An absolute value rotation encoder (100) including [a specific component].
2. The absolute value rotation encoder (100) according to claim 1, wherein the permanent magnet rotor unit (3.3) includes a rotor plate (1) and at least four permanent magnets (3.3.1 to 3.3.4) fixed to the rotor plate (1).
3. The absolute rotation encoder (100) according to claim 1 or 2, wherein the permanent magnet rotor unit (3.3) is designed such that, when mounted by the permanent magnet rotor unit (3.3), the magnetic field generated at the location of the Wiegand sensor (3.1) alternates exactly four times per revolution during uniform rotational motion of the shaft (101).
4. The absolute rotation encoder (100) according to claim 1 or 2, wherein the permanent magnet rotor unit (3.3) is designed to be attached to the outer circumferential surface (101.1) of the shaft (101).
5. The absolute rotation encoder (100) according to claim 1 or 2, wherein the magnetic field sensor (3.2) is a TNR sensor.
6. The absolute rotation encoder (100) according to claim 1 or 2, wherein the Wiegand sensor (3.1) and / or the magnetic field sensor (3.2) are arranged adjacent to the permanent magnet rotor unit (3.3) in the axial direction.
7. The absolute value rotation encoder (100) according to claim 1 or 2, wherein the angular position measuring device (4) is a capacitive angular position measuring device.