JP2020004925A - Magnet evaluation method and magnet evaluation device - Google Patents

Abstract

To provide a magnet evaluation method and a magnet evaluation device with reduced evaluation time.SOLUTION: In a magnet evaluation method according to the present application, on a virtual plane P, the direction of the magnetic flux is detected at a position where the angle θ with respect to the direction of the magnetic field at the intersection P0 is 45°, 135°, 225°, and 315° to calculate an angle error Δθ, and a magnet 12 is evaluated on the basis of the angle error Δθ. In the magnet evaluation method according to the present application, since it is not necessary to detect the direction of the magnetic flux or calculate the angle error for the entire surface or the entire circumference of the magnet 12, the evaluation time can be reduced.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a magnet evaluation method and an evaluation device.

  2. Description of the Related Art In recent years, magnetic rotation angle detectors have been widely used for various applications such as detection of a rotation position of a steering of an automobile. As a magnetic rotation angle detector, for example, a rotation angle detector described in Patent Document 1 is known.

  The rotation angle detector includes a magnet provided on a rotation shaft and a magnetic sensor for detecting a magnetic field generated by the magnet, and detects a rotation angle of the magnet based on a detection output of the magnetic sensor.

JP-A-2006-153765

  In the rotation angle detector described above, it is ideal that the magnetic sensor is arranged on the axis of the magnet, but the magnetic sensor is eccentric with respect to the axis of the magnet due to an error in assembling the magnet and the magnetic sensor. . Such eccentricity of the magnetic sensor contributes to an angular error which is a deviation of the detected rotation angle from the actual rotation angle.

  Therefore, in a rotation angle detector in which the maximum value of the amount of eccentricity is determined, there is a demand for a magnet whose angle error is guaranteed to be equal to or less than an allowable value.

  When such a magnet is obtained, evaluation is performed by measuring the entire main surface of the magnet, or measuring the entire circumference of a circle having an assembly error as a radius around the intersection.

  However, it takes a considerable amount of time to measure the entire surface and the entire circumference of the magnet. In particular, in the case of a rotation angle detector that requires high quality to ensure safety, such as a rotation angle detector used in an automobile, it is desirable to perform a 100% inspection of the magnets. It takes a long time.

  As a result of intensive research, the inventors have newly found a technique that can quickly evaluate whether or not the angle error of a magnet is equal to or less than an allowable value when the eccentricity is equal to or less than a predetermined amount of eccentricity.

  An object of the present invention is to provide a magnet evaluation method and an evaluation device in which the evaluation time is reduced.

  A method for evaluating a magnet according to one embodiment of the present invention includes a rotation angle detector for arranging a magnetic sensor facing a main surface of a magnet having an N pole and an S pole to detect a change in angle between the magnet and the magnetic sensor. Is a method of evaluating the magnets used in the method described above. The method is based on an imaginary circle centered on the intersection of the center axis of the magnet and the imaginary plane on the imaginary plane that is separated from the main surface of the magnet and parallel to the main surface. A probe disposing step of disposing a probe at at least one of positions where angles formed with respect to the direction of the in-plane magnetic field at the intersection on the virtual plane are 45 °, 135 °, 225 °, and 315 °; The detection step of detecting the direction of the magnetic flux of the magnet above, by a probe, and the calculation step of calculating the angle error between the direction of the magnetic flux detected by the probe and the angle at the position of the probe on the virtual plane, Based on the issued angular error, and a evaluation step of evaluating a magnet.

  The inventors have conducted research on the angular error of the magnet, and as a result, in the vicinity of the position where the angle formed with respect to the direction of the in-plane magnetic field at the intersection on the virtual plane is 45 °, 135 °, 225 °, and 315 °, The knowledge that the angle error becomes maximum was obtained. That is, as long as the angle error at the above position is calculated, the entire magnet can be evaluated. In the above magnet evaluation method, it is not necessary to measure the entire surface or the entire circumference of the magnet, so that the evaluation time can be reduced.

  In a method for evaluating a magnet according to another aspect, in the probe disposing step, the probe is set at each of four positions at which angles formed by the in-plane magnetic field on the main surface are 45 °, 135 °, 225 °, and 315 °. After the detection step and the calculation step are performed for each of the four positions, an evaluation step is performed. In this case, by calculating the angle errors at the four positions simultaneously or sequentially, it is possible to suppress an increase in the evaluation time and increase the accuracy and reliability of the evaluation.

  In the method for evaluating a magnet according to another aspect, in the probe disposing step, one of four positions at which angles formed with respect to the direction of the in-plane magnetic field in the virtual plane are 45 °, 135 °, 225 °, and 315 °. After the evaluation step, the probe is moved to another one of the four positions, and the detection step, the calculation step, and the evaluation step are repeated. By performing the evaluation of the magnet at a plurality of positions, the accuracy and reliability of the evaluation can be improved. Also in this case, the evaluation time can be reduced as compared with the case where the entire surface or the entire circumference of the magnet is measured.

  A magnet evaluation device according to one embodiment of the present invention includes a rotation angle detector that has a magnetic sensor facing a main surface of a magnet having an N pole and an S pole and detects a change in angle between the magnet and the magnetic sensor. A jig capable of holding a magnet and an intersection point between the center axis of the magnet and the virtual plane on a virtual plane spaced from the main surface of the magnet and parallel to the main surface. Is located on at least one of the positions where the angle with respect to the direction of the in-plane magnetic field at the intersection on the virtual plane is 45 °, 135 °, 225 °, and 315 °. And, a probe for detecting the direction of the magnetic flux of the magnet on the virtual plane, and calculating the angular error between the direction of the magnetic flux detected by the probe and the angle at the position of the probe on the virtual plane, and calculating the calculated angle error Based, and a control unit which evaluates the magnet.

  The magnet evaluation device can calculate and calculate the angle error at the position where the angle with respect to the direction of the in-plane magnetic field at the intersection on the virtual plane is 45 °, 135 °, 225 °, and 315 °. The entire magnet can be evaluated from the angle error. Therefore, according to the magnet evaluation device, the evaluation time can be reduced as compared with the case where the entire surface or the entire circumference of the magnet is measured.

  According to the present invention, there is provided a magnet evaluation method and an evaluation apparatus in which the evaluation time is reduced.

FIG. 1 is a perspective view of a magnet structure according to one embodiment. FIG. 2 is a sectional view taken along the axis C of FIG. FIG. 3 is a perspective view showing an example of a rotation angle detector using the magnet structure of FIG. FIG. 4 is a diagram showing an evaluation device for evaluating the magnet of the magnet structure of FIG. FIG. 5 is a diagram showing a position on a virtual plane P where the probe is arranged in the evaluation device of FIG. FIG. 6 is a flowchart showing an evaluation method for evaluating a magnet using the evaluation device of FIG. FIG. 7 is a diagram illustrating a result of a simulation performed on an angle error at each position on the virtual plane P. FIG. 8 is a diagram illustrating an evaluation device in a different mode from FIG. FIG. 9 is a diagram illustrating a magnet structure in a mode different from that of FIG. 1.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Note that the same or equivalent elements are denoted by the same reference numerals, and a description thereof will be omitted if the description is duplicated.

  As shown in FIGS. 1 and 2, a magnet structure 10 according to the embodiment includes a magnet 12 and a magnet holder 14.

  The magnet 12 has a cylindrical shape, and has an upper end surface 12a and a lower end surface 12b. The upper end surface 12a and the lower end surface 12b are surfaces perpendicular to the central axis C of the magnet 12. The upper end surface 12a is a facing surface facing a magnetic sensor 26 described later. The length (that is, height) H of the magnet 12 in the central axis direction can be, for example, 1 to 10 mm from the viewpoint of improving the accuracy of the sensor, and is 2 mm in the present embodiment. The diameter D of the magnet 12 can be, for example, 5 to 20 mm, and is 13 mm in the present embodiment. The magnet 12 can be obtained by molding by compression molding, extrusion molding, or the like, or can be obtained by cutting out a large chunk of magnet. The magnet 12 is not limited to a cylindrical shape, and may have a prismatic shape or an elliptical shape.

  The magnet 12 is magnetized in a direction orthogonal to the central axis C, and has an N pole and an S pole on the upper end face 12a as shown in FIG. Hereinafter, for convenience of description, the direction of the center axis C of the magnet 12 is referred to as a Z direction, the magnetization direction of the magnet 12 is referred to as an X direction, and a direction perpendicular to the Z direction and the X direction is referred to as a Y direction.

  The magnet 12 is a permanent magnet. The magnet 12 can be formed using a number of magnetic powders. Examples of magnetic powders are hard magnetic powders such as rare earth magnet powders and ferrite magnet powders. From the viewpoint of miniaturization, the magnetic powder is preferably a rare earth magnet powder. The rare earth magnet powder is an alloy powder containing a rare earth element.

The rare earth elements include at least one element selected from the group consisting of scandium (Sc), yttrium (Y), and lanthanoids belonging to Group 3 of the long-period periodic table. Examples of transition elements are Fe, Co, Cu and Zr, but it is preferable that Fe is essential. Specific examples of the rare earth alloy include an SmCo alloy, an NdFeB alloy, and an SmFeN alloy. Among these, an NdFeB-based alloy represented by Nd ₂ Fe ₁₄ B is preferable. The NdFeB-based alloy contains Nd, Fe, and boron. The rare earth magnet can include other additional elements.

  The average particle size of the magnetic powder can be, for example, 30 to 250 μm. The magnet 12 may include one type of magnetic powder alone, or may include two or more types of magnetic powder.

Each magnetic powder has one or more magnetic crystal grains according to the particle size, and each magnetic crystal grain has an axis of easy magnetization. For example, when the magnetic crystal is Nd ₂ Fe ₁₄ B, the axis of easy magnetization is the c-axis. FIG. 3A is a schematic diagram showing the magnetic crystal grains G in the cross section of the magnet 12 and the respective easy axes of magnetization. In the present embodiment, the direction of the axis of easy magnetization of the magnetic crystal grains G present in the magnet 12 is isotropic, that is, random.

  Such a magnet can be obtained by applying a magnetic field to a magnet after molding without substantially applying a magnetic field when the magnet 12 is molded, and magnetizing the magnet.

  The magnet 12 may be a so-called bonded magnet containing a binder in addition to the magnetic powder. An example of a binder is a resin binder. Examples of the resin binder are a cured product of a thermosetting resin or a thermoplastic resin. Examples of the curable resin are an epoxy resin and a phenol resin. Examples of thermoplastic resins are polyamides such as nylon (eg, PA12, PA6, PA66); polyphenylene sulfide. The magnet 12 may include one type of resin alone, or may include two or more types of resins. When the magnet 12 is a bonded magnet, the volume ratio of the resin in the magnet can be 30 to 90%, and the volume ratio of the magnetic powder can be 10 to 70%.

  The magnet 12 is not limited to the above-described bonded magnet and may be a sintered magnet such as an NdFeB-based sintered magnet or a ferrite sintered magnet as long as the magnet 12 is formed using the magnetic powder. It may be a permanent magnet manufactured by cold working.

  As shown in FIGS. 1 and 2, the magnet holder 14 is a cylindrical case that extends along the direction of the central axis C of the magnet 12. The magnet holder 14 has an inside diameter that is the same as or slightly larger than the diameter of the magnet 12 so that the magnet 12 can be accommodated and fixed inside. The magnet holder 14 can be manufactured by, for example, press working. A non-magnetic material can be adopted as a constituent material of the magnet holder 14. For example, a non-magnetic material such as aluminum, copper, brass, and stainless steel may be employed.

  In the present embodiment, an annular flange portion 14a extending radially outward is provided at the end of the magnet holder 14 on the upper end surface 12a side of the magnet 12. In the present embodiment, the flange portion 14a is provided so as to form the same surface as the upper end surface 12a of the magnet 12. There may be a step of approximately 0.05 to 0.5 mm between the upper end surface 12a of the magnet 12 and the flange portion 14a. The height of the magnet holder 14 is designed to be higher than the height of the magnet 12. Therefore, in the magnet holder 14 on the lower end surface 12b side of the magnet 12, a cylindrical cavity 14b is defined by the inner side surface of the magnet holder 14 and the lower end surface 12b of the magnet 12.

  The magnet 12 and the magnet holder 14 may be fixed with an adhesive. Alternatively, the magnet 12 can be integrally formed in the magnet holder 14 by injection molding. Specifically, the raw material composition including the binder resin and the magnet powder is fluidized by heating or the like, injected into the magnet holder, and solidified by cooling or the like, thereby forming the magnet 12 in the magnet holder 14. it can. By performing the injection step in the absence of a magnetic field, the axis of easy magnetization of the magnetic crystal grains can be oriented isotropically. Although not shown, the contact surface between the magnet 12 and the magnet holder 14 is provided with irregularities, and one of the protrusions fits into the other recess, so that the magnet 12 and the magnet holder 14 are fixed. May be. From the viewpoint that the unevenness of the magnet 12 does not disturb the magnetic field formed by the magnet, the size of the unevenness in the radial direction of the magnet with respect to the outer peripheral surface of the magnet 12 is preferably within ± 0.5 mm.

  The shape of the magnet holder 14 is not limited to a cylindrical case as long as it can hold a magnet, and may be a polygonal cylindrical shape or a bottomed cylindrical case.

  Next, the rotation angle detector 20 using the magnet structure 10 will be described with reference to FIG. The rotation angle detector 20 can be incorporated in, for example, an electric power steering (EPS) of an automobile.

  In the rotation angle detector 20, the magnet structure 10 is attached to an end of the rotation shaft 22. The rotating shaft 22 has a cylindrical end, and is fitted into the cavity 14 b of the magnet structure 10. The magnet 12 of the magnet structure 10 and the rotation shaft 22 are aligned with each other, and the magnet 12 of the magnet structure 10 also rotates around the central axis C in accordance with the rotation of the rotation shaft 22. An electric motor 24 for electric power steering is connected to the rotating shaft 22, and driving of the rotating shaft 22 is controlled by an ECU (Electronic Control Unit) that controls the electric motor 24.

  The rotation angle detector 20 includes a magnetic sensor 26 that can detect the direction of a magnetic field. The magnetic sensor 26 is, for example, an AMR element, a GMR element, and a TMR element. In particular, since the TMR element has high sensitivity, the direction of the magnetic field can be detected with high accuracy.

  The magnetic sensor 26 is disposed so as to face the upper end surface 12 a of the magnet 12 of the magnet structure 10. The magnetic sensor 26 is ideally arranged on the center axis C of the magnet 12. The magnetic sensor 26 is fixed to the lower surface of the fixing jig F that is not interlocked with the rotation of the rotation shaft 22 by, for example, an adhesive. Further, the magnetic sensor 26 may be embedded inside the fixing jig F. In the rotation angle detector 20, the distance Gap between the magnet 12 of the magnet structure 10 and the magnetic sensor 26 can be, for example, 1 to 6 mm. In the case of a magnetic sensor having a TMR element, the magnetic sensor 26 can be arranged at a position where the strength of the magnetic field is 20 to 80 mT.

  In the rotation angle detector 20, a magnetic field as shown by a broken line M in FIG. 3 is generated by the magnet 12 of the magnet structure 10, and when the rotating shaft 22 is rotated around the center axis C of the magnet 12 in the R direction. On the central axis C, the direction of the magnetic field changes around the central axis C according to the rotation angle of the rotation shaft 22. The rotation angle detector 20 detects the rotation angle (change in angle) of the rotation shaft 22 by detecting a change in the direction of the magnetic field with the magnetic sensor 26. In the electric power steering, the current of the electric motor 24 is feedback-controlled according to the rotation angle detected by the rotation angle detector 20, and the amount of power assist is adjusted.

  Next, an evaluation device 30 for evaluating the magnet 12 of the magnet structure 10 described above will be described with reference to FIG.

  The evaluation device 30 includes a jig 32 that holds the magnet structure 10 and a probe 34 that detects the direction of the magnetic field of the magnet 12.

  The jig 32 has a cylindrical end and is fitted into the cavity 14 b of the magnet structure 10. As long as the jig 32 can fix the position of the magnet structure 10, the jig 32 may have a shape in which the magnet structure 10 is gripped from the outer peripheral side or a shape in which the magnet structure 10 is supported from below.

  The probe 34 is disposed on a virtual plane P parallel to the upper end surface 12a of the magnet 12 in the evaluation device 30. The gap Gap between the upper end surface 12a of the magnet 12 and the virtual plane P may be the same as or different from the gap Gap between the magnet 12 and the magnetic sensor 26 described above. On the virtual plane P, there is an intersection P0 with the center axis C of the magnet 12. FIG. 4 shows a reference line M1 extending through the intersection and extending in the direction of the in-plane magnetic field at the intersection P0 as a reference line on the virtual plane P. The reference line M1 is parallel to the direction of magnetization of the magnet 12 (X direction).

  The probe 34 is arranged on the virtual plane P at a position at a specific angle θ with respect to the reference line M1. That is, as shown in FIG. 5, the probe 34 is arranged on the virtual plane P at any one of the positions P1, 45 ° P2, 225 ° P3, 315 ° P4 with respect to the reference line M1. Is done. The distance between the intersection P0 on the virtual plane P and the probe 34 (that is, the radius of the virtual circle Q in FIG. 5) can be determined from the eccentricity of the magnetic sensor 26 described above. In the rotation angle detector 20, the magnetic sensor 26 may deviate from the center axis C of the magnet 12 due to an assembly error or the like, and is designed with a certain amount of eccentricity. Then, the maximum value of the eccentricity (maximum eccentricity) that can actually occur at the time of assembly is determined as the distance between the intersection P0 on the virtual plane P and the probe 34. The maximum amount of eccentricity can vary depending on the accuracy and purpose required for the rotation angle detector 20 including the magnet structure 10. In the present embodiment, the radius of the virtual circle Q, which is the maximum amount of eccentricity, is set to 0.6 mm.

  The probe 34 includes two Hall elements 34x and 34y. One Hall element 34x is oriented to detect the component of the magnetic flux on the virtual plane P in the X direction, and the other Hall element 34y is configured to detect the component of the magnetic flux on the virtual plane P in the Y direction. Oriented.

  The evaluation device 30 further includes a driving unit 36 and a control unit 38.

  The drive unit 36 is an actuator that can move the probe 34 to a predetermined position on the virtual plane P. As the driving unit 36, a linear actuator or the like that can realize a minute displacement of the probe 34 can be employed.

  The control unit 38 is connected to the probe 34 and the driving unit 36. The control unit 38 receives, from the probe 34, an X-direction component and a Y-direction component of the magnetic flux detected by the two Hall elements 34x and 34y. The control unit 38 is controllably connected to the drive unit 36, and can perform position detection and position control of the probe 34 via the drive unit 36. Further, the control unit 38 calculates the direction of the magnetic flux at the position of the probe 34 from the component in the X direction and the component in the Y direction of the magnetic flux received from the probe 34 as an inclination angle θ ′ of the magnetic flux with respect to the reference line M1.

  The inventors simulated the angle error Δθ between the angle θ determined by the position on the virtual plane P and the inclination angle θ ′ of the magnetic flux at the position, and obtained the results shown in FIG.

  FIG. 7 is a graph showing the magnitude of the angle error Δθ at each position on the virtual plane P divided into seven ranges. The horizontal axis of the graph in FIG. 7 indicates a shift amount from the intersection P0 in the X direction, and indicates a shift amount from the intersection P0 in the Y direction. The circle shown in the graph of FIG. 7 is a circle having a radius of 0.6 mm centered on the intersection P0, and corresponds to the virtual circle Q described above.

  As is clear from the graph of FIG. 7, the angle error Δθ is smaller as the deviation from the intersection P0 in the X direction is smaller, and the angle error Δθ is smaller as the deviation from the intersection P0 in the Y direction is smaller. Conversely, it can be seen that the angle error Δθ tends to increase in the four corner regions of the graph where the deviation from the intersection P0 in the X direction and the deviation from the intersection P0 in the Y direction are large. When the virtual circle Q is considered, it can be seen that the angle error Δθ increases in the regions of 45 °, 135 °, 225 °, and 315 °.

  If the inventors obtain the angle error Δθ in the range of 45 °, 135 °, 225 ° and 315 ° where the angle error Δθ is large from the above simulation results, the inventors roughly estimate the state of the angle error Δθ of the entire magnet 12. It was found that the magnet can be evaluated based on the estimation.

  Next, an evaluation method for evaluating the magnet 12 using the above-described evaluation device 30 will be described with reference to the flowchart of FIG.

  When the magnet 12 is evaluated, first, as step S1, the magnet 12 is set on the jig 32 and the probe 34 is arranged at the position P1 on the virtual plane P, and the relative alignment between the magnet 12 and the probe 34 is performed. (Probe placement step).

  Next, in step S2, the probe 34 detects a component in the X direction and a component in the Y direction of the magnetic flux with the probe 34 at the position P1 on the virtual plane P, and the control unit 38 determines the direction of the magnetic flux at the position P1 as a reference. It is calculated as the inclination angle θ ′ of the magnetic flux with respect to the line M1 (detection step).

  Further, as step S3, the control unit 38 calculates an angle error Δθ between the inclination angle θ ′ of the magnetic flux calculated in step S2 and the inclination angle θ of the position P1 (calculation step).

  Then, as step S4, the control unit 38 evaluates the magnet 12 based on the angle error Δθ calculated in step S3 (evaluation step). As an evaluation of the magnet 12, for example, it is evaluated whether or not the angle error Δθ is equal to or less than an allowable value (for example, ± 0.20 °). Can be determined. In other words, when the magnet 12 determined to be non-defective is used for the rotation angle detector 20 in which the amount of eccentricity (assembly error) of the magnetic sensor 26 with respect to the center axis C of the magnet 12 is equal to or less than the above-described maximum eccentricity, It is guaranteed that the angle error Δθ is equal to or less than the allowable value over the entire surface of the image. As an evaluation of the magnet 12, the magnet 12 can be classified according to the magnitude of the angle error Δθ.

  As described above, in the evaluation device 30 and the evaluation method of the magnet 12 according to the present embodiment, the direction of the magnetic flux at the position where the angle θ formed with the reference line M1 on the virtual circle Q of the virtual plane P is 45 ° Is detected to calculate an angle error Δθ, and the magnet 12 is evaluated based on the angle error Δθ. Therefore, it is not necessary to detect the direction of the magnetic flux or calculate the angle error for the entire surface or the entire circumference of the magnet 12, thereby shortening the evaluation time.

  The position at which the angle error Δθ is calculated by detecting the direction of the magnetic flux is not limited to the position P1 on the virtual plane P, but may be any of the positions P2 to P4.

  The positions at which the direction of the magnetic flux is detected to calculate the angle error Δθ may be a plurality of positions among the positions P1 to P4 on the virtual plane P. In this case, after the probe 34 is arranged at any of the positions P1 to P4 on the virtual plane P to calculate the angle error Δθ, the drive unit 36 moves the probe 34 to another position to calculate the angle error Δθ. The evaluation of the magnet 12 is performed based on the angular error Δθ at that position. Specifically, in the flowchart of FIG. 6, steps S1 to S4 are repeated while sequentially changing the position of the probe 34. By performing the evaluation at a plurality of positions in this way, the accuracy and reliability of the evaluation are improved. If the angle error Δθ exceeds the allowable value in the evaluation process at any of the positions P1 to P4, the magnet 12 is determined to be defective at that time, and the process is terminated. Good.

  Further, the angle error Δθ can be calculated by detecting the direction of the magnetic flux at at least one of the positions P1 to P4, and the angle error Δθ can be calculated by detecting the direction of the magnetic flux at the intersection P0. Although the angle error Δθ does not theoretically occur at the intersection P0, the angle error Δθ may be calculated for the purpose of calibration.

  When there are a plurality of positions where the direction of the magnetic flux is detected to calculate the angle error Δθ, the evaluation device can include a plurality of probes. FIG. 8 shows an evaluation device 30A including four probes 34A to 34D. The four probes 34A to 34D are fixedly arranged at positions P1 to P4 on the virtual plane P, respectively. In this case, the driving unit 36 of the evaluation device 30 described above can be omitted.

  In the evaluation device 30A, since the probes 34A to 34D are fixedly arranged in the device, the relative position between the magnet 12 and the probes 34A to 34D in step S1 in the flowchart of FIG. Positioning is completed.

  In addition, in the evaluation device 30A, since the four probes 34A to 34D can simultaneously or sequentially detect the X-direction component and the Y-direction component of the magnetic flux, in step S2 of the flowchart of FIG. The inclination angle θ ′ of the magnetic flux at the positions P1 to P4 can be calculated efficiently.

  Further, in the evaluation device 30A, the evaluation in step S4 of the flowchart in FIG. 6 is performed based on the angle errors Δθ calculated at the four positions P1 to P4, so that the accuracy and reliability of the evaluation are improved.

  The form of the magnet structure is not limited to the form described above, and may be a form like a magnet structure 10A shown in FIG. The magnet structure 10A includes a columnar magnet 12A and a shaft-like magnet holder 14A. The magnet holder 14A is a long member extending along the center axis C of the magnet 12A, and has a substantially cylindrical outer shape. The magnet holder 14A can be made of a non-magnetic material, similarly to the magnet holder 14A described above. One end of the magnet holder 14A is fitted into, for example, a round hole (not shown) provided on the lower end surface of the magnet 12A, thereby coupling the magnet 12A and the magnet holder 14A. At the other end of the magnet holder 14A, a hole into which the rotating shaft 22 is pressed is provided along the center axis C of the magnet 12A, so that the magnet holder 14A and the rotating shaft 22 can be coaxially arranged. ing.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various changes can be made.

  For example, in the above embodiment, the probe constituted by the Hall element is shown, but the probe may be constituted by a TMR element.

10, 10A: magnet structure, 12, 12A: magnet, 12a: upper end surface, 14, 14A: magnet holder, 20: rotation angle detector, 30, 30A: evaluation device, 32: jig, 34, 34A- 34D: probe, 34x, 34y: Hall element, 36: drive unit, 38: control unit, P: virtual plane, P0: intersection.

Claims (4)

An evaluation method of a magnet used for a rotation angle detector for detecting a change in angle between the magnet and the magnetic sensor by disposing a magnetic sensor on a main surface of a magnet having an N pole and an S pole,
On a virtual circle spaced from the main surface of the magnet and on a virtual plane parallel to the main surface, on a virtual circle centered on the intersection of the center axis of the magnet and the virtual plane, A probe disposing step of disposing a probe at at least one of positions where angles formed with respect to the direction of the in-plane magnetic field at the intersection are 45 °, 135 °, 225 °, and 315 °;
A detection step of detecting the direction of the magnetic flux of the magnet on the virtual plane by the probe,
A calculation step of calculating an angle error between the direction of the magnetic flux detected by the probe and the angle at the position of the probe on the virtual plane,
An evaluation step of evaluating the magnet based on the calculated angle error.   In the probe disposing step, the probe is disposed at each of four positions at which the angles with respect to the direction of the in-plane magnetic field on the main surface are 45 °, 135 °, 225 °, and 315 °, The magnet evaluation method according to claim 1, wherein the evaluation step is performed after performing the detection step and the calculation step. In the probe arranging step, the probe is arranged at one of four positions where the angle with respect to the direction of the in-plane magnetic field in the virtual plane is 45 °, 135 °, 225 °, and 315 °,
The method for evaluating a magnet according to claim 1, wherein after the evaluation step, the probe is moved to another one of four positions, and the detection step, the calculation step, and the evaluation step are repeated. . A magnet evaluation device used for a rotation angle detector for disposing a magnetic sensor on a main surface of a magnet having an N pole and an S pole to detect an angle change between the magnet and the magnetic sensor,
A jig capable of holding the magnet,
On a virtual circle spaced from the main surface of the magnet and on a virtual plane parallel to the main surface, on a virtual circle centered on the intersection of the center axis of the magnet and the virtual plane, At an angle of 45 °, 135 °, 225 °, and 315 ° with respect to the direction of the in-plane magnetic field at the intersection, and the direction of the magnetic flux of the magnet on the virtual plane. A probe for detecting
A control unit that calculates an angle error between the direction of the magnetic flux detected by the probe and the angle at the position of the probe on the virtual plane, and evaluates the magnet based on the calculated angle error. An evaluation device for a magnet, comprising:

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