JP4858855B2 - Rotation angle detector and rotating machine - Google Patents

Description

  The present invention relates to a rotation angle detection device and a rotating machine that detect a rotation angle of a rotation shaft.

  In Patent Document 1, as shown in FIG. 9, a rotation angle sensor in which a disc-shaped two-pole magnet 400 supported by a rotation shaft 403 and magnetic sensors A and B are arranged near the circumference of the magnet 400. Is disclosed. The magnetic sensors A and B are Hall elements, and are used for detecting the rotation angle by detecting the strength of the magnetic field. When viewed in the circumferential direction, the angle formed by the straight line 412 passing through the center O of the disk and the approximate center of the magnetic sensor A, and the straight line 411 passing through the approximate center of the magnetic sensor B is a mechanical angle of approximately 90 degrees. . It is arranged to be. As the magnetic sensor, an MR element can be used in addition to the Hall element. Here, the mechanical angle refers to an angle of 360 degrees around the circumference of the disk. It is what.

  Patent Document 2 discloses a servo motor including a rotor 515 having a permanent magnet 517 and an encoder 502 for detecting the rotational position of the rotor, as shown in FIG. The permanent magnet has bipolar anisotropy, and the encoder has a magnetic sensor 522 that detects a magnetic field (leakage flux of the permanent magnet) of the rotor. The magnetic sensor is rotated 90 deg. Are arranged at intervals of 180 deg. It is possible to take a differential signal between the magnetic sensors facing each other at the position.

  Patent Document 3 discloses a rotation angle detection device in which each of an end surface and a peripheral surface of a detection magnet is magnetized in multiple poles as shown in FIG. Specifically, as shown in (a), a disc-shaped detection magnet 603 (disc) is provided that is concentrically suspended from the rotating shaft 606. For example, three pairs (six poles) of magnetic poles 603a are arranged in parallel on one surface of the detection magnet 603 at equal intervals in a concentric manner as shown in FIG. For example, 48 pairs (96 poles) of magnetic poles 603b are arranged in parallel on the circumferential surface of the detection magnet 603 at equal intervals, as shown in FIG. A detection substrate 602 is provided on one surface side of the detection magnet 603 so as to be parallel to the detection magnet 603 with an appropriate length interval and to be rotatable with respect to the rotation shaft 606. The detection substrate 602 has a Hall element or MR for detecting the magnetic poles 603b so that the electrical angles formed by the 48 pairs of magnetic poles 603b are different from each other by 1/4 (mechanical angle (360 deg./48)/4). Two magnetic detection elements 602 d and 602 e as elements are provided along the peripheral surface of the detection magnet 603. As will be described later, the detection substrate 602 detects the magnetic pole 603a so that the electrical angles formed by the three pairs of magnetic poles 603a are different in phase by an equal angle (mechanical angle (360 deg./3)/3). Three magnetic detection elements 602a to 602c, which are Hall elements or MR elements, are provided along one surface of the detection magnet 603.

JP 2003-075108 (FIG. 4, paragraph 0028, paragraph 0051) Japanese Unexamined Patent Publication No. 2000-078809 (FIGS. 1 and 2, paragraph 0004) JP 2001-343206 A (FIG. 1, FIG. 2, paragraph 0013)

  Patent Document 1 also describes that a plurality of magnetic sensors are arranged in one place and output values are averaged to obtain an output value with higher accuracy. However, since a dipole magnet is used, it is difficult to detect the rotation angle with high accuracy.

  Since Patent Document 2 uses a bipolar permanent magnet, it is difficult to detect the rotation angle with high accuracy.

  Patent Document 3 uses multi-pole (more than two) permanent magnets (detection magnets), and the peripheral surface and end face of the ring-shaped permanent magnet are magnetized at different pitches. In order to detect each of the magnetic pole 603a and the magnetic pole 603b with different magnetic sensors (magnetic detection elements), the magnetic sensors (magnetic detection elements) 602a to 602e are three-dimensionally arranged at different positions, so that extremely high accuracy is achieved. Alignment is required. However, even if the arrangement of the magnetic sensors is slightly shifted, it is difficult to detect the rotation angle with high accuracy if it is applied to an application that needs to detect the rotation angle.

  Therefore, an object of the present invention is to provide a rotation angle detection device and a rotating machine with high detection accuracy of the rotation angle.

The rotation angle detection device of the present invention includes a magnet rotor having N pole pairs of magnetic poles (where N is an integer equal to or greater than 2) and a magnet rotor according to the magnetic flux applied from the magnet rotor. With four Hall sensors for detecting the rotation angle,
The four Hall sensors have first and second radial Hall sensors arranged with the magnetic sensitive axes directed in the radial direction of the magnet rotor, and the magnetic sensitive axes directed in the circumferential direction of the magnet rotor. The first and second circumferential hall sensors are arranged in the manner described above.

Another rotation angle detection device according to the present invention includes a magnet rotor having N pole pairs of magnetic poles (where N is an integer of 2 or more), and magnet rotation according to the magnetic flux applied from the magnet rotor. And four Hall sensors for detecting the rotation angle of the child,
The four Hall sensors have first and second radial Hall sensors arranged with the magnetic sensitive axes directed in the radial direction of the magnet rotor, and the magnetic sensitive axes directed in the circumferential direction of the magnet rotor. And the first and second circumferential hall sensors arranged
The first radial hall sensor and the second circumferential hall sensor are (2s ₁ −1) × 360 / (4N) deg. In the circumferential direction of the magnet rotor. (Where s ₁ is a natural number including 0),
The second radial hall sensor and the first circumferential hall sensor are (2s ₂ −1) × 360 / (4N) deg. In the circumferential direction of the magnet rotor. (Where s ₂ is a natural number including 0),
Synthesizing outputs of the first radial hall sensor and the second circumferential hall sensor, and synthesizing outputs of the second radial hall sensor and the first circumferential hall sensor; Thus, the rotation angle is detected.

Further, the first and second radial hall sensors are (2s ₃ −1) × 360 / (4N) deg. It is preferable that s ₃ is provided so as to make an angle of (note that s ₃ is a natural number including 0).

  A rotating machine according to the present invention includes the above-described rotation angle detection device.

  Here, outputting the rotation angle signal corresponding to the rotation angle means performing processing including arctangent calculation. Specifically, it is a process of performing an arctangent calculation digitally.

  ADVANTAGE OF THE INVENTION According to this invention, the rotation angle detection apparatus with high detection accuracy of a rotation angle, and a rotary machine can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not necessarily limited by these embodiment.

(Embodiment 1)
1A and 1B are schematic diagrams for explaining the arrangement of magnetic sensors in the rotation angle detection device of the present invention, wherein FIG. 1A is a front view, and FIG. 1B is a sensor output and detection angle with respect to an electrical angle (deg.). And a graph showing the relationship between angle errors. In FIG. 1A, four Hall ICs 41, 42, 43, 44 are arranged along the circumferential direction of the ring-shaped permanent magnet 1a of the magnet rotor (the rotation direction of the ring-shaped permanent magnet 1a). The two Hall ICs 41 and 42 have the magnetic field detection direction directed to the center of the ring-shaped permanent magnet 1a, and the other two Hall ICs 43 and 44 have the magnetic field detection direction directed to the circumferential direction of the ring permanent magnet 1a. The distance between adjacent Hall ICs is 90 deg. It was. The a output obtained by adding the outputs of the Hall ICs 41 and 44 and the b output obtained by adding the outputs of the Hall ICs 42 and 43 are shown in the electric angle-sensor output graph of FIG. The a output is input to the first operational amplifier, the b output is input to the second operational amplifier, the outputs of the first and second operational amplifiers are input to the AD converter, and the output is input to the angle calculator. The detection angle was obtained as output. The detection angle error is an electrical angle of up to 6.4 deg. Got.

(Embodiments 2 and 3)
FIG. 2 is a schematic diagram for explaining the arrangement of magnetic sensors in another rotation angle detection device of the present invention. FIG. 2A corresponds to a configuration in which the Hall sensor 41 in FIG. 1 is arranged with a shift of λ in the counterclockwise circumferential direction. FIG. 2B corresponds to a configuration in which the hall sensors 43 and 44 in FIG. 1 are both shifted by λ in the counterclockwise circumferential direction.

(Surface magnetic flux density distribution and angular error)
3A and 3B are schematic diagrams for explaining the positional relationship between the magnetic field of the magnet rotor and the sensor element in the reference example, where FIG. 3A is a front view, and FIG. 3B is a sensor output with respect to an electrical angle (deg.). It is a graph which shows the relationship between a detection angle and an angle error. In FIG. 3A, with respect to the ring-shaped permanent magnet 1a of the magnet rotor, the direction of magnetization in each magnetic pole is represented by a straight thick arrow, and the magnetic flux 1e generated from the magnetic pole surface is represented by a curved thick arrow. The magnetic sensor unit 2 receives the magnetic flux 1e in the direction of the arrow y. λ corresponds to one wavelength of a sine wave when measuring the surface magnetic flux density distribution (360 deg. in electrical angle), and in the ring-shaped permanent magnet 1a, corresponds to the circumferential length of a pair of magnetic pole surfaces. r corresponds to the distance between the center of the magnetic sensor part 2 and the outer peripheral surface of the ring-shaped permanent magnet 1a (a value close to the size of the gap) when viewed along the radial direction of the ring-shaped permanent magnet 1a. The ring-shaped permanent magnet 1a is moved in the circumferential direction by θ = 90 deg. When the magnetic sensor unit 2 is shifted by a distance, the magnetic sensor unit 2 receives the magnetic flux in the direction of the arrow x. In addition, about the angle etc. in connection with a reference example or this invention, it shows to Fig.3 (a). First, the magnetic sensor unit 2 that is on the dotted line op connecting the rotation center o and the point p of the magnet rotor and that is centered at a distance r from the surface of the magnet rotor 1a is used as a reference. Then, it can be said that the magnetic sensor unit 2r is at a position different from the magnetic sensor unit 2 in the circumferential direction by an electrical angle θ. θ is called the revolution angle. An angle ξ formed by a dotted line connecting the center of the magnetic sensor unit 2r and the rotation center o of the magnet rotor and the magnetosensitive axis of the magnetic sensor unit 2r is referred to as a rotation angle. However, in the embodiment, ξ = 0. φ is a mechanical angle representing the mechanical rotation of the magnet rotor.

(Function)
A magnet rotor having 2N poles in the rotation direction will be described. This magnet rotor may be rephrased as having N pole pairs of magnets, and has N times of axial symmetry. A mechanical angle φ of a certain reference angle is expressed by [Equation 1] by an electrical angle θ.

  Assuming that the magnetic field coming out of this magnet rotor is a magnet rotor that is infinitely long in the axial direction for simplification (ie, it is assumed that the magnetic field is uniformly distributed in the axial direction). The magnetic field in the space generated from the magnet rotor is considered as a vector, and the magnetic field component Hr in the radial direction and the magnetic field component Hθ in the rotational direction are expressed as the following functions as a function of the measurement position (r, φ) expressed in the cylindrical coordinate system: It can be approximated by the function of [Equation 2].

Further, when the fundamental wave component is not zero, that is, when A ₁ is not zero, r becomes large to some extent, and when the third-order or higher harmonic is smaller than the fundamental wave represented by A ₁ [Equation 3 ] Can be simplified.

This means that the direction of the magnetic field changes by θ when the magnet rotor moves by an angle θ with respect to the measurement point. That is, it means that the rotation angle of the magnet rotor can be measured by detecting the direction of the magnetic field regardless of the magnitude of the magnetic field. In the above equation, the amplitude of the cos signal and the sin signal is set to the same A ₁ in the above equation. However, in general, when the axis is a finite length, the cos term and the sin term are applied. The magnitude of the coefficient may be different. When the magnitudes of the coefficients are different, it is necessary to adjust the amplitude according to the conditions.

  When the same Hall sensor is used to obtain cos and sin signals simultaneously as described above, 90 deg. The phase difference is required. Many combinations are possible to obtain this phase difference. In other words, since the Hall sensor has anisotropy in one direction (that is, a magnetosensitive axis), an angle ξ formed by the Hall sensor itself with respect to a line drawn in the normal direction from the center of the rotor is arbitrarily set. Is possible, but the angle ξ is 0 deg. , ± 90 deg, ± 180 deg. It is preferable that it is either. This ξ is called a rotation angle.

  When fixing the position of the hall sensor, the first hall sensor is set to 0 (zero) deg. It is assumed that the second hall sensor is disposed at the position θ in terms of electrical angle at the position. Revolution angle θ = 90 deg. When the second Hall sensor is arranged at the position, it is possible to obtain a signal having a relationship between cos θ and sin θ by setting the rotation angles ξ of the first Hall sensor and the second Hall sensor to the same angle. It becomes. Further, when the first Hall sensor is used as a reference, that is, the revolution angle of the first Hall sensor is 0 deg. And the rotation angle is 0 deg. In this case, the second hall sensor has a revolution angle θ = 45 deg. And the rotation angle ξ = −45 deg. It is possible to obtain a similar signal, and the revolution angle θ = 180 deg. And the rotation angle ξ = 90 deg. It is also possible to obtain a similar signal.

  Further, the revolution angle θ of the two Hall sensors is 0 deg. And the rotation angle ξ = 0 deg. Of the first Hall sensor. And the rotation angle of the second sensor element ξ = 90 deg. It is possible to obtain a similar signal even if two hall sensors are provided at the same location. When these are further expanded, the difference in revolution angle between the first Hall sensor and the second Hall sensor is Δθ, and the rotation angle difference between the first Hall sensor and the second Hall sensor is Δξ. In addition, any combination of [Delta] [theta] and [Delta] [xi] having the relationship of [Equation 4] may be used.

  Further, since the magnet rotor is composed of a multi-pole pair, the second Hall sensor does not stop at the above-mentioned angle in terms of electrical angle but has moved an angle in units of one cycle (electric angle is set to 360 deg. × n). It is possible to obtain a similar signal even if it is installed at a corresponding location, and the integer n may be plus or minus. In other words, any combination of θ and ξ that satisfies the relationship of [Equation 5] may be used (where n is an arbitrary integer). This is the most generalized formula.

(Applicable magnetic sensor)
As a magnetic sensor for realizing the above magnetic sensor, there is a Hall sensor having a Hall element. The Hall element is a sensor element that changes its output voltage value by detecting the “magnitude” of the magnetic field, and is usually used to detect one-dimensionally the magnetic field component applied perpendicular to the surface of the sensor element. (This direction corresponds to the magnetosensitive axis.) The magnetosensitive axis is orthogonal to the flat surface of the Hall sensor (the magnetosensitive portion: corresponding to the widest surface of the molded surface). More specifically, the output of the Hall sensor is proportional to the magnetically sensitive axial direction component of the magnetic field in the magnetically sensitive part of the Hall sensor. In the present invention, the entire sensor system is configured by paying attention to the voltage change when the Hall sensor is placed in the rotating magnetic field. Hall sensor that changes the voltage of cos α (α is the angle formed by the magnetic field with respect to the reference direction) relative to the rotating magnetic field, Hall sensor that changes the voltage of the opposite sign (−cos α), or a combination of elements Is used. By applying a Hall sensor that outputs a voltage proportional to cos α when a DC voltage is applied, the following Vout is output as [Equation 6]. In Equation 6, δ is the rate of change of the output voltage with respect to the applied magnetic field Hin.

  In general, a Hall sensor having a Hall element is placed with its magnetosensitive axis directed toward the magnet rotor, and when a plurality of arrangements are made, it is placed at a predetermined position with an electrical angle (the revolution angle θ described above). ), Without changing the rotation angle ξ. Since the hall sensor must be installed only at spatially different positions, when the hall sensor is used as a magnetic sensor, its location is also limited, but in the present invention, this ξ can be changed. Even if they are arranged at the same mechanical angle, they can have different phase differences.

(Reduction of harmonic components by multiple magnetic sensors)
In the above description of the action, it is assumed that when a magnet rotor is ideally rotated, a magnetic field free of harmonics of sin or cos is generated in time and space. , Harmonic components (harmonic distortion) A ₃ , A ₅ ,... Are not limited to zero. Rather, it is more common to assume that harmonic components are present. If expressed simply, it is expressed as Equation 7.

  That is, the harmonic components that are distortion components are equally contained in the fundamental waves of Hr and Hθ, and the cos component and sin component are mainly used, respectively. In order to reduce this harmonic component, a method of arranging a plurality of magnetic sensors and greatly reducing only the harmonic component was invented.

(Reason why the angle error is reduced by changing the number of magnetic sensors from 2 to 4)
When there are four magnetic sensors, the r-direction (radial direction) component tends to be a trapezoidal waveform and the θ-direction (rotation direction) component tends to be a triangular wave when a magnetic field coming out of the rotor is detected. The harmonics of have an antiphase relationship. The first Hall sensor detects an r-direction component of the magnetic field, and the second Hall sensor detects an electrical angle (revolution angle) of 90 deg. Rotation angle -90 deg. Place with. At that time, the phases of the fundamental waves output from the respective hall sensors can be made to coincide with each other, and in this case, the main harmonics output from the respective hall sensors have an opposite phase relationship. Specifically, the first hall sensor is set to θ = 0 deg. ξ = 0 deg. And the second Hall sensor is θ = 90 deg. ξ = 0 deg. And the third Hall sensor is θ = 180 deg. ξ = 90 deg. And the fourth Hall sensor is θ = 270 deg. ξ = −90 deg. In this case, the outputs from the hall sensors are expressed as Vout ₁ to Vout ₄ .

  By using this relationship, by combining the positional relationship, the fundamental waves from the two Hall sensors are added together, and at the same time, the main third-order harmonic components are added and reduced so as to be in antiphase, and the amplitudes are equal, And 90 deg. Two signals having different phases can be obtained, and as a result, the angle error can be reduced. Here, since the positive and negative signs of each output correspond to the front and back of the surface of the Hall sensor, they can be appropriately arranged so that [Equation 9] is satisfied.

  In Expression 8, although the output amplitude is different due to the coefficient Km which is not generally 1, the same amplitude can always be obtained by combining the outputs of the two Hall sensors in this way. The first and second Hall sensors, the third Hall sensor, and the fourth Hall sensor are respectively the same distance from the center of the magnet rotor and the same angular difference in the circumferential direction with respect to the magnet rotor (= electrically 90 degrees different). If it arrange | positions so that it may become, it will satisfy conditions. The placement of the Hall sensor becomes easy.

The ratio of the third harmonic to the fundamental wave in Equation 8 is A ₃ / A ₁ ,
That in Equation 9 is (Km−1) / (Km + 1) × A ₃ / A ₁ . Therefore, by increasing the number of Hall sensors from two to four, the third harmonic, which is the largest cause of the rotation angle error obtained from the arc tangent calculation, can be reduced to (Km−1) / (Km + 1). it can.

  When examined with the configuration of the first embodiment, Km was about 1.4 to 2. Therefore, by increasing the number of Hall sensors from two to four, the waveform distortion, that is, the angle error can be reduced from 30% to about 10% in the case of two Hall sensors. Further, if the output amplitudes from the four Hall sensors are adjusted, the above Km can be substantially reduced to 1. Therefore, the cause of the angle error due to waveform distortion is from the third-order distortion to the fifth-order distortion, which is a smaller value. Move.

  When the hall sensors are oriented in the same direction with respect to the rotation axis as in the prior art, all the hall sensors detect Hr. Therefore, even if the number of hall sensors is increased from two to four, the above-described effect is obtained. Does not appear. On the other hand, when four Hall sensors are arranged almost symmetrically with respect to the rotation axis, there is a feature that an increase in rotation angle error can be suppressed with respect to eccentricity (variation) of the rotation axis. . In the present invention, the Hall sensor cannot be completely axisymmetrically arranged, and thus cannot be completely suppressed. However, one of the Hall sensors that obtains the in-phase output is installed at a location closest to the other axially symmetric position. (In the case of N = 8), it was confirmed that it can be suppressed to about 1/10 without inferiority.

  When the magnet rotor is, for example, 12 poles, the Hall IC 12b is arranged at a position different from the Hall IC 12a in the circumferential direction by a mechanical angle φ (φ = 15 deg.), And therefore there is a phase difference of the electrical angle θ ( θ = 90 deg.). When one receives the magnetic flux along the circumferential direction of the magnet rotor, the other receives the magnetic flux delayed by θ. By increasing the number of poles in this way, the φ with respect to θ is reduced, and a set of Hall ICs can be accommodated in a narrow area and reduced in size.

(Reduction of rotation angle error due to the number of poles)
When the maximum detection angle error is represented by a mechanical angle, the electrical angle error decreases according to the number of magnetic poles. For this reason, the present invention using a magnet rotor having a large number of magnetic poles can further reduce detection errors. In the case of a 12-pole magnet rotor, the rotational angle error is reduced to one-sixth of the mechanical angle compared to the case of using a 2-pole magnet rotor.
When the number of pole pairs of the magnet rotor is the same as the number of pole pairs of the motor, high-precision motor control is facilitated. Moreover, it can replace with a magnet rotor and a rotation angle can also be calculated | required using the magnet of a motor.
Since there is less magnetic flux leaking outside than a dipole magnet, the magnetic influence on the outside is also small.
The rotation period of the magnetic field received by the Hall sensor is 1 / N times (N is an integer of 2 or more), and the resolution is higher than the mechanical rotation period of the magnet rotor. The above rotation angle detection device may be provided in a rotating machine.

(Reference form 1)
4A and 4B are schematic diagrams for explaining a rotation angle detection device according to a reference embodiment, in which FIG. 4A is a front view, and FIG. 4B is a side view (a lower half is a partial cross-sectional view). The rotation angle detection device shown in FIG. 4 (a) includes a magnet rotor 1, a magnetic sensor unit 2, and a housing 3 to which the magnetic sensor unit is fixed. Hall ICs 12a and 12b (a Hall element and an operational amplifier are integrated). The rotation angle of the ring-shaped permanent magnet 1a is detected by a hall sensor). Hall ICs 12a and 12b are used as magnetic sensors. The Hall IC in FIG. 4 is arranged with the magnetic sensitive axis of the Hall IC parallel to the direction in which the lines of magnetic force are directed (corresponding to the radial direction when viewed from the center of the magnet rotor). As shown in FIG. 4B, the terminals of the Hall IC are fixed to the circuit board 2c. Further, the signals of the Hall ICs 12a and 12b are input to the A / D converter, and both of the obtained outputs are input to the angle calculator to obtain the detected angle value as the final output. The rotation angle is detected by using multiple magnet rotors and bringing the magnetic sensor arrangement close to each other. The same components are used in the embodiment of the present invention except for the number and arrangement of the Hall ICs (that is, the magnetic sensor unit).

  The magnet rotor 1 supports a ring-shaped permanent magnet 1a having an outer peripheral shape connecting a plurality of arcs, a soft magnetic ring 1b integrally formed on the inner peripheral side of the ring-shaped permanent magnet, and the soft magnetic ring The nonmagnetic ring-shaped adapter 1c is provided. The magnetic sensor unit 2 includes a plate-like circuit board 2c having a concave surface facing the magnet rotor 1, a pair of Hall ICs 12a and 12b fixed to the surface of the circuit board 2c, and the Hall IC and circuit. A cable 2d and a connector 2e that electrically connect the circuit board 2c and the control circuit, and a nonmagnetic cover 2f that covers the Hall IC. The housing 3 is provided with a U-shaped angle 3a and a bolt 3c for fixing the circuit board 2c so that the Hall ICs 12a and 12b face the magnet rotor 1 at a predetermined interval.

  In order to use the rotation angle detection device of FIG. 4, the housing 3 in which the magnetic sensor unit 2 is installed is fixed to the machine tool body (using the bolting holes 3b), and the magnet rotor 1 is attached to the rotation shaft of the machine tool. It is fixed so as to be coaxial (using the bolting hole 1d) (the machine tool is not shown in FIG. 4). As shown in FIG. 4A, when the rotating shaft of the machine tool is driven in a state where the magnet rotor 1 and the magnetic sensor unit 2 face each other, the configuration to which the magnetic sensor unit of the first embodiment is applied has high accuracy. It was possible to detect the rotation angle.

Here, the magnet rotor 1 includes a ring-shaped permanent magnet 1a formed by molding NdFeB-based magnetic powder and a binder, a soft magnetic ring 1b formed by molding soft iron powder and a binder, and the soft magnetic ring is attached to a rotating shaft. For this purpose, the adapter 1c made of S45C is used. The Hall ICs 12a and 12b are 15 deg. It is fixed to the circuit board 2c so as to make an angle (mechanical angle: φ). The housing 3 and the U-shaped angle 3a are also made of nonmagnetic SUS316.
Radius of circumscribed circle (illustrated by dotted line) of magnet rotor 1: 40 mm
Distance between circumscribed circle (illustrated by dotted line) of magnet rotor 1 and Hall IC center r: 3.5 mm
Magnet rotor 1 thickness t: 25 mm
Thickness T of housing 3: 2 mm (A 2 mm thick plate is punched out and formed with a diaphragm)
When the distance r was changed, it could be used without any problem even when r = 10 mm. Further, even when the thickness t of the magnet rotor 1 was 5 mm, it could be used without any problem.

(Reference form 2)
5A and 5B are schematic diagrams for explaining the arrangement of magnetic sensors in a rotation angle detection device according to another reference embodiment, in which FIG. 5A is a front view, and FIG. 5B is a sensor output with respect to an electrical angle (deg.). It is a graph which shows the relationship between a detection angle and an angle error. In FIG. 5 (a), four Hall ICs 31, 32, 33, and 34 are provided at an electrical angle of 90 deg. , 180 deg. And 90 deg. It arrange | positions along the circumferential direction (rotation direction of the ring-shaped permanent magnet 1a) by the space | interval of. Each Hall IC faces the magnetic field detection direction toward the center of the ring-shaped permanent magnet 1a, but the magnetic field detection direction of adjacent Hall ICs is reversed. The a output obtained by adding the outputs of the Hall ICs 31 and 32 and the b output obtained by adding the outputs of the Hall ICs 33 and 34 are shown in the electric angle-sensor output graph of FIG. The detection angle error is 22 deg. Got.

  FIG. 6 is a schematic view illustrating the rotating machine of the present invention. FIGS. 6A and 6B are views of the same rotating machine seen from different cross sections. The Hall IC 82b in FIG. 6B is arranged along the circumferential direction (θ direction) of the magnet rotor 71c with the surface of the Hall IC 82a in FIG. 6A (a surface perpendicular to the magnetic sensitive axis of the Hall IC). The direction is changed to the direction (the direction perpendicular to the surface of the Hall IC of (a) (surface perpendicular to the magnetosensitive axis)), and is arranged at a position shifted in the circumferential direction.

  As shown in FIG. 6 (a), this rotating machine is a motor, and in a frame 73c, a permanent magnet rotor 71a having a shaft 71b as a central axis, and a stator coil fixed to the inner peripheral surface of the frame 73c. A stator 73a with 73b is installed. The shaft 71b was rotatably fixed to the frame 73c via a bearing (not shown). Further, the magnet rotor 71c is provided on the shaft 71b, and the Hall IC 82a is installed on the frame 73c via the support portion 72n. The rotating machine also includes a radial Hall IC 82c (not shown) that is the same as the Hall IC 82a and a circumferential Hall IC 82d (not shown) that is the same as the Hall IC 82b.

  The rotating magnetic field of the magnet rotor 71c is detected by the Hall IC 82a, Hall IC 82b, Hall IC 82c and Hall IC 82d, and these four outputs are input to the arithmetic circuit 72m to obtain two outputs to obtain the two outputs. The output was tangented to obtain the rotation angle of the magnet rotor 71c. The axis of magnetic rotation in the magnetization direction is indicated by a chain line in the figure.

  When the configuration of the first embodiment is applied to a motor, the Hall ICs 41 and 42 whose magnetosensitive axis faces the radial direction of the magnet rotor are opposed to the magnet rotor as in the Hall IC 82a of FIG. Deploy. In the configuration of the first embodiment, the Hall ICs 43 and 44 whose magnetosensitive axis faces the circumferential direction of the magnet rotor are 90 ° different from the Hall ICs 41 and 42 as the Hall IC 82b in FIG. 6B. Arrange so that

  FIG. 7 is a schematic diagram illustrating another rotating machine of the present invention, which is an application example in which the configuration of FIG. 6 is modified. FIG. 7A shows a magnet rotor 71d in which the magnetization direction is changed in the axial direction of the shaft in FIG. 6B, the support portion 72n is replaced with the support portion 71o, and the Hall IC 82b is connected to the terminal. Is replaced with a Hall IC 82c whose length is shortened, and the magnetic field of the magnet rotor 71d is detected on the surface of the Hall IC 82c. FIG. 7B differs from FIG. 7A in that the Hall IC 82d and the support portion 72p that support the Hall IC 82d are arranged so that the direction of the magnetosensitive axis is parallel to the shaft. The machine is viewed from different cross sections, and the Hall IC 82c and Hall IC 82d detect the rotating magnetic field of the magnet rotor, process it with one arithmetic circuit, and detect the rotation angle of the magnet rotor. FIGS. 7 (c) and (d) are obtained by replacing the rotor 71a and the magnet rotor 71c with the rotor 71e in the configurations of FIGS. 6 (a) and 6 (b), and the same rotating machine is different in cross section. The rotating magnetic field of the magnet rotor 71e is detected by the Hall IC 82a and the Hall IC 82c, processed by one arithmetic circuit, and the rotation angle of the magnet rotor is detected.

  FIG. 8 is a graph showing the relationship between r / λ and angle error. FIG. 8 shows data obtained by two types of rotation angle detection devices. A is a plot in which the angle error is evaluated with the two outputs of the Hall ICs 41 and 44 of the rotation angle detection device shown in FIG. 4, and B is a graph using all the Hall ICs of the rotation angle detection device shown in FIG. It is the plot which evaluated the angle error. Each corresponds to A: FIG. 4 and B: FIG. From this graph, compared to the configuration in which the magnetosensitive axis of the Hall IC is oriented only in the r direction as shown in FIG. 4, the magnetosensitive axis of the Hall IC is oriented in the r direction and the θ direction as shown in FIG. It can be seen that the angle error is small. Further, it can be seen that the error of B greatly decreases as the distance between the outer peripheral surface of the magnet rotor and the center of the Hall sensor increases as compared to A. The cause of the error in the configuration of FIG. 4, that is, the ratio of the third harmonic to the fundamental wave, which is the distortion of the magnetic field, is attenuated with respect to the distance. In the case of FIG. The harmonics are dominant, and it is considered that the ratio of the fifth harmonic component to the fundamental wave attenuated with respect to the distance.

It is the schematic explaining the arrangement | positioning of the Hall sensor in the rotation angle detection apparatus of this invention. It is the schematic explaining arrangement | positioning of the Hall sensor in the other rotation angle detection apparatus of this invention. It is the schematic explaining the positional relationship of the magnetic field of a magnet rotor, and a Hall sensor. It is the schematic which shows the other rotation angle detection apparatus which concerns on a reference form. It is the schematic explaining the arrangement | positioning of the Hall sensor in the rotation angle detection apparatus of another reference form. It is the schematic explaining the rotary machine of this invention. It is the schematic explaining the other rotary machine of this invention. It is a graph which shows the relationship between r / (lambda) and an angle error. It is the schematic which shows the conventional rotation angle detection apparatus. It is the schematic which shows the conventional rotation angle detection apparatus. It is the schematic which shows the conventional rotation angle detection apparatus.

Explanation of symbols

1: magnet rotor, 1a: ring-shaped permanent magnet, 1b: soft magnetic ring, 1c: adapter,
1d: bolt fixing hole, 1e: magnetic flux,
2: Magnetic sensor part,
2c: circuit board, 2d: cable, 2e: connector, 2f: non-magnetic cover,
2r: magnetic sensor unit,
3: Housing, 3a: U-shaped angle, 3b: Bolt fixing hole, 3c: Bolt,
12a, 12b: Hall IC,
31, 32, 33, 34: Hall IC,
41, 42, 43, 44: Hall IC,
71a: rotor, 71b: shaft, 71c: magnet rotor,
71d: magnet rotor, 71e: rotor,
72m: arithmetic circuit, 72n: support part,
72o: support part, 72p: support part,
73a: Stator, 73b: Coil for stator, 73c: Frame,
82a: Hall IC, 82b: Hall IC, 82c: Hall IC, 82d: Hall IC,

Claims (3)

A magnet rotor having N pole pairs of magnetic poles (where N is an integer of 2 or more) and four for detecting the rotation angle of the magnet rotor in accordance with the magnetic flux applied from the magnet rotor With a hall sensor
The four Hall sensors have first and second radial Hall sensors arranged with the magnetic sensitive axes directed in the radial direction of the magnet rotor, and the magnetic sensitive axes directed in the circumferential direction of the magnet rotor. And the first and second circumferential hall sensors arranged
The first radial hall sensor and the second circumferential hall sensor are (2s ₁ −1) × 360 / (4N) deg. In the circumferential direction of the magnet rotor. (Where s ₁ is a natural number including 0),
The second radial hall sensor and the first circumferential hall sensor are (2s ₂ −1) × 360 / (4N) deg. In the circumferential direction of the magnet rotor. (Where s ₂ is a natural number including 0),
Synthesizing outputs of the first radial hall sensor and the second circumferential hall sensor, and synthesizing outputs of the second radial hall sensor and the first circumferential hall sensor; A rotation angle detecting device characterized by detecting a rotation angle. 2. The first and second radial hall sensors according to claim 1 , wherein (2s ₃ −1) × 360 / (4N) deg. The rotation angle detecting device is provided so as to make an angle (where s ₃ is a natural number including 0). Rotating machine characterized in that it comprises a rotation angle detection device according to claim 1 or 2.

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