JP5615892B2 - Magnetization method and apparatus - Google Patents

Description

The present invention relates to a magnetized device Ru employed magnetizing method and the deposition magnetizing method polarity to be magnetized body in a predetermined direction of magnetization is multi-pole magnetized so as to change alternately.

  Many automobile wheel bearings (hub bearings) require the wheels required to control ABS (anti-lock braking system: (skid prevention device)) and ESC (electronic stability control (vehicle attitude stabilization device)). A rotation sensor is attached. The wheel rotation sensor includes a magnetic sensor that detects a change in polarity of the N and S poles of the magnet, and a magnetic encoder that is a ring-shaped magnet in which the N and S poles are alternately magnetized at equal intervals in the circumferential direction. It is comprised. The magnetic sensor detects the situation where the polarity of the magnetic encoder changes alternately with the rotation of the wheel, and it is regarded as a wheel rotation signal and used for vehicle control such as ABS and ESC. Magnetizers have been developed for producing magnetic encoders composed of multipole magnetized permanent magnets.

  The present inventor has developed a magnetizing device disclosed in Patent Document 1 as a magnetizing device capable of magnetizing with a large magnetic force while ensuring a highly accurate magnetizing pitch.

Patent No. 4846863

  In recent years, automobiles using a motor as a power source, such as hybrid cars and electric cars, are becoming widespread, and an absolute angle detector that detects an absolute angle is used as a device for controlling the rotation of the motor. An optical detector cannot be used as an on-vehicle absolute angle detector under high vibration and high dust environment. So-called electromagnetic induction type resolver is used, but the resolver is electromagnetic induction type. In order to obtain an output, it is necessary to pass an alternating current through the coil, power consumption is large, the circuit is complicated, and the product cost is high.

  An absolute angle detector using a multi-pole magnetized permanent magnet is a magnetic encoder that detects the magnetic output of the permanent magnet with a magnetic sensor such as a Hall element, and has low power consumption and low cost. For detecting the rotation of a vehicle-mounted motor, the detection accuracy is low and it has not been put into practical use.

  The present inventor has developed a permanent magnet type magnetic encoder that can be used in an absolute angle detector for a vehicle-mounted motor, using the magnetizing method by the magnetizing device of Patent Document 1.

An object of the present invention is to provide a magnetizing Ho及 beauty magnetizing apparatus for manufacturing a magnetic encoder capable of detecting an absolute angle with high accuracy.

In order to achieve the above object, the magnetizing method of the present invention includes a magnetizing head disposed at a position facing the circumferential surface of a cylindrical magnetized body, and the circumferential surface of the magnetized body has a pole number M (M is In a magnetization method in which multipolar magnetization is performed with a natural number of 2 or more, the magnetizing head or the magnetized body is relatively moved along the rotation axis of the magnetized body while supplying an alternating current to the magnetized head. In addition, the magnetized body or the magnetized head is relatively rotated P (P is a natural number of 2 or more) around the rotation axis of the magnetized body, and a total of P × M times of magnetizing operations are performed. The N + 1th magnetization operation is performed on the circumferential surface area adjacent to the circumferential direction of the circumferential surface region magnetized by the N (N is a natural number of 1 or more) magnetization operation among the P × M magnetization operations. performed, N (N is a natural number of 1 or more) towards the rotation axis the height of the magnetized peripheral surface area by th wearing磁動operation of the P × M times the wearing磁動work The N + M-th magnetization operation is performed so as to overlap with a portion exceeding half of the center, and the N + M-th magnetization position is 12 to 20 degrees center angle per 1 mm displacement in the rotational axis direction with respect to the N-th magnetization position. The N + M-th magnetization operation is performed so as to be shifted.

The magnetizing device of the present invention is a magnetizing device that multipolarizes the circumferential surface of a cylindrical magnetized body so that the polarity alternately changes in the circumferential direction. A positioning means is provided that has a core having a tip portion that forms an arc surface that is close to and along the circumferential surface, and that positions and arranges conductive wires that extend from one end side to the other end side of the arc surface on the arc surface. And a magnetizing head disposed so that a direction from one end side to the other end side of the arc surface is perpendicular to the circumferential direction, and the arc surface of the magnetizing head is relatively rotated or rotated in the circumferential direction of the magnetized body. A drive unit that rotates or moves the magnetized body or magnetized head so that the magnetized body or magnetized head moves along the rotation axis direction of the magnetized body, and the magnetized body or magnetized head is rotated or moved by the drive unit. while, a power supply for supplying an alternating current to the conductive wire, electrode peripheral surface of the object to be magnetized body When multipolar magnetization is performed at M (M is a natural number of 2 or more), the drive unit supplies the alternating current to the magnetized head, and the drive unit moves along the rotation axis of the magnetized body. Alternatively, the magnetized body is relatively moved, and the magnetized body or the magnetized head is relatively rotated P times (P is a natural number of 2 or more) about the rotation axis of the magnetized body. Thus, at least P × M magnetization operations are performed, and the circumference of the peripheral surface region magnetized by the N (N is a natural number of 1 or more) magnetization operations among the P × M magnetization operations is performed. The peripheral surface region magnetized by N (N is a natural number of 1 or more) of the P × M magnetization operations, and the N + 1th magnetization operation is performed on the peripheral surface region adjacent to the direction. The N + M-th magnetization operation is performed so as to overlap with a portion exceeding half of the rotational axis height direction of the N-th magnetization position. N + M-th magnetized position is to be shifted center angle 12 to 20 degrees per rotation axis direction height of 1mm displacement, and performs N + M th wearing磁動operation.

  ADVANTAGE OF THE INVENTION According to this invention, the to-be-adhered magnetic body (permanent magnet) which can be utilized for the permanent magnet type magnetic encoder which can detect an absolute angle with high precision can be manufactured.

It is a figure which shows the example of schematic structure of the magnetizing apparatus for performing the magnetizing method in embodiment of this invention. It is a figure which shows the structural example of the core of the magnetization head in this Embodiment. It is a figure which shows the structural example of the magnetizing head by which the conductive wire is arrange | positioned at the core. It is a figure which shows the arrangement pattern of the conductive wire. It is a figure which shows arrangement | positioning with the magnetization head 16 and the to-be-magnetized body 1. FIG. The center angle deviation (skew angle) φ is shown. It is a figure explaining the magnetizing operation | movement in this Embodiment. It is a figure which shows the to-be-adhered magnetic body 1 in which the magnetic pole area | region inclined with respect to the rotating shaft was formed. It is a figure explaining another magnetizing operation | movement in this Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.

  FIG. 1 is a diagram illustrating a schematic configuration example of a magnetizing apparatus for performing a magnetizing method according to an embodiment of the present invention. The present embodiment exemplifies a magnetizing apparatus that magnetizes the peripheral surface of a cylindrical magnetized body so that the polarity changes alternately in the circumferential direction. A magnetizing apparatus according to the present embodiment includes a rotation holding unit 10 that rotatably holds a cylindrical magnetized body 1 to be magnetized, a motor 12 that is driven to rotate by the rotation holding unit, and a rotation angle of the motor 12. An encoder 14 that outputs a pulse signal corresponding to the above, a magnetizing head 16 that magnetizes the magnetized body 1, a vertical drive unit 17 that drives the magnetizing head 16 in the vertical direction, a power supply device 18, and a control means 20. Have

  The magnetized body 1 is a member that becomes a multipolar magnet such as a magnetic encoder by magnetization, and is a cylindrical magnetic body. As the adherend 1, for example, a rare earth sintered magnet capable of obtaining a large magnetic flux density is preferable, but other magnets such as a ferrite bonded magnet can also be applied.

  The rotation holding unit 10 is a main shaft that is concentric with the adherend 1, and the adherend 1 is rotatably fixed to the rotation holder 10. In this embodiment, the magnetizing head 16 is fixed and the magnetized body 1 is rotated with respect to the magnetized head 16. However, the magnetizing head 16 is rotated with respect to the fixed magnetized body 1. In principle, the configuration to be made is also possible.

  As the motor 12, for example, a brushless motor excellent in rotation accuracy is used, and the rotation holding unit 10 is driven to rotate. The encoder 14 outputs a pulse signal corresponding to the rotation angle of the motor 12, and the higher the resolution, the smaller the pitch error. For example, the encoder 14 preferably outputs a pulse signal of 10,000 pulses or more per rotation. .

  The vertical drive unit 17 holds the magnetizing head 16 and moves the magnetizing head 16 up and down in the vertical direction at a predetermined controlled speed. By magnetizing the magnetized body 1 by rotating the magnetized body 1 while moving the magnetized head 16 vertically, the magnetized head 16 magnetizes the peripheral surface of the magnetized body 1 in a spiral shape.

  As will be described in detail later, the magnetizing head 16 has a tip surface that is in contact with or close to the peripheral surface, which is the magnetized surface of the cylindrical magnetized body 1, and the tip surface is the magnetized body 1. Are formed in an arc shape along the peripheral surface, and a predetermined pattern of conductive lines is arranged on the arcuate tip surface shape. It is arranged extending in a predetermined pattern.

  The power supply device 18 is a device that applies a magnetizing current to the electric wire accommodated in the tip surface of the magnetizing head 16, and is an inverter circuit using a switching element such as a thyristor, for example. By controlling the ON / OFF cycle of the switching element, an alternating current having an arbitrary frequency can be obtained.

  The control means 20 includes a control circuit 21 that controls the power supply device 18 and an overall control device 22 that is a higher level thereof. The control circuit 21 is a circuit that controls the cycle of the alternating current of the power supply device 18, and the overall control device 22 acquires the pulse signal from the encoder 14, controls the motor 12 and the control circuit 21, and is driven vertically. The moving speed of the unit 17 is controlled. The overall control device 22 is, for example, a personal computer, and various controls are executed by the CPU executing a predetermined control program.

  Next, the configuration of the magnetizing head 16 will be described in detail with reference to the drawings.

  2 and 3 are diagrams showing a configuration example of the magnetizing head 16 in the present embodiment. The magnetizing head 16 is disposed on a prismatic core 2 formed of a ferromagnetic material such as a cobalt alloy (for example, permendur) and a surface (tip surface) of the core 2 facing the magnetized body 1. And a conductive wire 3. The conductive wire 3 is, for example, a copper wire.

  2A, 2B, and 2C are a bottom view, a front view, and a side view of the core 2, respectively. The bottom surface of the core 2 is a front end surface of the core 2 that faces the magnetized body 1. 3 shows a state in which the conductive wire 3 is arranged on the tip surface of the core 2, FIG. 3 (b) shows a tip surface of the core 2 in which the conductive wire 3 is arranged, and FIG. FIG. 5 is a cross-sectional view taken along the center line VV of the distal end surface of the core 2 shown in FIG.

  The magnetizing head 16 includes, for example, a core 2 formed of a ferromagnetic material such as a cobalt alloy, and conductive wires 3 arranged in a predetermined pattern on a surface (tip surface) of the core 2 facing the magnetized body 1. It is prepared for.

  The distal end portion of the core 2 is formed narrower than the root portion, and the distal end surface is an elongated arc surface 2a that forms an arc along the peripheral surface of the adherend 1 and has six poles. As an example of the configuration for magnetization, the central angle is about 120 degrees as an example. In order to detect the absolute angle with high accuracy by the magnetic encoder, the output waveform of the magnetic encoder needs to be a sin waveform without distortion, but by making the tip surface of the core 2 an arc shape along the peripheral surface, With respect to a predetermined length range in the circumferential direction, the distance to the peripheral surface can be kept at an equal distance, and the constant range can be magnetized with a constant strength, contributing to a waveform output without distortion.

  On the circular arc surface 2a, convex portions 2b and 2c are formed as positioning means for forming an arrangement region in which the conductive wire 3 is arranged. The convex portions 2b and 2c are arranged in series in the circumferential direction with a gap in the center portion of the arc surface 2a, and extend from one end side to the other end side of the arc surface 2a to accommodate the conductive wire 3 Arrangement regions A, B, and C are formed. The three arrangement regions A, B, and C are arranged in parallel at a predetermined interval in the circumferential direction of the adherend 1 when the arcuate face 2a is placed opposite the adherend 1 and the arcuate face 2a It is formed from one end side to the other end side along the rotation axis of the adherend 1.

  A groove-shaped second arrangement region B is formed in a region sandwiched between the end surfaces of the convex portions 2b and 2c facing each other at the central portion of the arcuate surface 2a, and the convex portions 2b and 2c are formed on both sides of the second arrangement region B. A groove-shaped first arrangement area A and third arrangement area C formed by the end face of the arc and the curved end of the arcuate surface 2a are formed. The first, second, and third arrangement regions A, B, and C extend in a direction perpendicular to the peripheral surface, and in FIGS. 2A and 2B, the second arrangement region B, the first The arrangement area A and the third arrangement area C are arranged in parallel in the circumferential direction.

  The root portion of the core 2 is provided with a screw hole or the like for fixing the magnetizing head 16 to a magnetizing head holding device (not shown), and the core 2 is attached to the magnetizing head holding device with a screw. The magnetized head holding device is a known XYZ stage for positioning the magnetized head 16 in the three-axis directions of the X, Y, and Z axes.

  FIG. 4 is a diagram showing an arrangement pattern of the conductive lines 3. The conductive wire 3 extending from the power supply device 18 is projected from the extension line of the second arrangement region B which is the central arrangement region on one end side in the short length direction of the core 2, that is, the direction perpendicular to the circumferential direction. 2b is bent along the side surface on one end side, is arranged in the first arrangement region A and extends from one end side to the other end side of the arcuate surface 2a, and the convex portion 2b on the other end side of the first arrangement region. The second arrangement region B is bent along the side surface on the other end side, is arranged in the second arrangement region B, extends from the other end side to the one end side in the second arrangement region B, and is further arranged in the second arrangement region B. Is bent along the side surface on one end side of the convex portion 2c, is disposed in the third arrangement region C, extends from one end side to the other end side of the arcuate surface, and the other of the third arrangement region C. On the end side, it is bent so as to extend on an extension line of the second second arrangement region B. More specifically, the conductive wire 3 is bent from the extension line of the first arrangement region A on one end side, and in order, the side surface on one end side of the convex portion 2b, the second arrangement region B, and the convex portion 2b. It is arranged along the side surface on the other end side, the first arrangement region A, the side surface on one end side of the convex portion 2c, the third arrangement region C, the side surface on the other end side of the convex portion 2c, and the first on the other end side. It extends on the extended line of the arrangement area A. In this arrangement pattern, the conductive line 3 extends from the other end side to one end side in the first arrangement area A, the second arrangement area B and the third arrangement area C, extends from one end side to the other end side, The direction of the current flowing through the conductive line 3 in the second arrangement region B and the third arrangement region C is opposite to the direction of the current in the conductive line 3 in the first arrangement region A. As described above, since the conductive wire 3 is disposed so as to surround the convex portion 2b and the convex portion 2c, the adjacent peripheral surface regions facing the convex portion 2b and the convex portion 2c are respectively subjected to one magnetization operation. The unit magnetized regions are magnetized simultaneously with different polarities, and are strongly magnetized by the magnetic fields from the four directions generated by the conductive wires 3 surrounding the convex portion. When viewed as an output waveform of the magnetic encoder, a drop in the magnetic flux density in the central region of the unit magnetization region that leads to waveform distortion is eliminated, and a sin waveform output without distortion in the magnetic encoder is obtained.

  The core 2 is formed with a through hole 2d for returning the conductive wire 3 extending to the other end side to the one end side according to the arrangement pattern described above. The through hole 2d is provided along the first arrangement area A at a position directly below the first arrangement area A. The conductive wire 3 coming out from the other end side of the third arrangement region C of the arc surface 2a according to the arrangement pattern shown in FIG. 4 is bent as shown in FIG. 3A, and the other end of the arc surface 2a is bent. The inside of the through hole 2d extends from the side to the one end side, and returns to the power supply device 18 from one end side of the arcuate surface 2a. At this time, the direction of the current flowing through the conductive line portion extending through the first arrangement region A on the circular arc surface 2a and the conductive line portion extending through the through hole 2d is the same. Accordingly, since the magnetic field generated by the current flowing through the through hole 2d also contributes to the magnetization of the magnetized body 1, the through hole 2d is formed as close to the arc surface 2a as possible, and preferably the first groove portion. It may be provided immediately below and the bottom of the first arrangement region A may communicate with the through hole 2d. Of course, the through hole 2d may be formed at a position directly below the first arrangement region A as much as possible without the bottom of the first groove portion communicating with the through hole 2d.

  The convex portions 2b and 2c, the through hole 2d, the screw hole, and the like of the core 2 are formed by machining. Further, in order to fix the conductive wire 3 arranged on the circular arc surface 2a, the conductive wire 3 protruding outward from one end side and the other end side of the circular arc surface 2a of the core 2 is made of, for example, an epoxy resin or the like. You may fix with respect to a side surface.

  Next, the magnetization method will be described.

  The magnetizing head 16 is positioned so that the front end surface 2a faces the magnetized body 1 at a slight distance in order to avoid wear of the arc surface 2a due to friction with the arc surface 2a.

  Then, the overall control device 22 acquires the pulse signal from the encoder 14 and generates an alternating current having a frequency corresponding to the number of poles to be magnetized during one rotation of the magnetized body 1 in synchronization with the pulse signal cycle. As described above, a control signal is sent to the control circuit 21, and the control circuit 21 performs switch control of the switching circuit (inverter circuit) of the power supply device 18 in accordance with the control signal. For example, when 6 poles are magnetized so that the magnetic poles are perpendicular to the rotation direction (without tilting the magnetic poles), the rotation angle per pole is 60 degrees, and the overall control device 22 The number of pulse signals corresponding to the time for which the peripheral surface rotates 60 degrees is counted, and each time the number of pulse signals is counted, a control signal is sent to the control circuit 21 so as to reverse the current direction.

  The alternating current supplied from the power supply device 18 flows through the conductive wire 3 of the magnetizing head 16 and is generated by a magnetic field generated by the current flowing through the conductive wire 3 disposed on the arc surface 2a located very close to the magnetized body 1. The magnetized body 1 is magnetized.

  FIG. 5 is a diagram showing the arrangement of the magnetizing head 16 and the magnetized body 1. In the example of 6-pole magnetization, by passing an alternating current through the conductive wire 3 at the timing of rotating the magnetized body 1 by 60 degrees, as shown in FIGS. 5 (a), (b), and (c), Magnetization is performed sequentially.

  In the magnetization method in the present embodiment, the magnetized body 1 to be magnetized is held by the rotation holding unit 10 and the motor 12 is driven to rotate the magnetized body 1 fixed to the rotation holding unit 10. The magnetizing head 16 is vertically driven at a predetermined speed to magnetize the circumferential surface of the magnetized body 1 in a spiral shape, and a magnetic pole inclined with respect to the rotation axis is formed on the circumferential surface.

  Specifically, when the peripheral surface of the magnetized body is multipolarized with the number of poles M (M is a natural number of 2 or more, for example, 2, 4, 6, 8, and 10), the magnetization is performed. While the head 16 moves in the vertical direction (from bottom to top or from top to bottom), the head 16 rotates at least P times (P is a natural number of 2 or more) and performs at least P × M times of magnetizing operation. By shifting the magnetization position by a predetermined central angle every time, a magnetic pole inclined with respect to the rotation axis of the magnetized body 1 is formed. The number of times of the magnetizing operation is not necessarily limited to P × M times (that is, a multiple of M). For example, when the magnetizing operation is completed in the course of the circulation, the number of times may be P × M + 1. “At least P × M times” includes the number of times of magnetization when the magnetization operation is completed in the middle of the circulation.

  Further, in the magnetization operation in the present embodiment, the height of the rotation axis of the peripheral surface region magnetized by the N (N is a natural number of 1 or more) magnetization operation among the P × M magnetization operations. The N + M-th magnetization operation is performed so as to overlap with a portion exceeding half of the direction, and the N + M-th magnetization position is a central angle 12 per 1 mm displacement in the rotational axis direction height with respect to the N-th magnetization position. The N + M-th magnetization operation is performed so as to be shifted by ˜20 degrees. FIG. 6 shows the deviation (skew angle) φ of the center angle. The magnetizing position is shifted by a skew angle φ per 1 mm of displacement in the rotation axis direction of the magnetizing head 16 (front and back direction in the figure), and magnetization tilted with respect to the rotation axis is performed.

  FIG. 7 is a diagram for explaining the magnetizing operation in the present embodiment. FIG. 7 shows magnetic pole regions (N-pole region and S-pole region) formed on the circumferential surface of the magnetized body 1 developed in a plane. As an example, in quadrupole magnetization, a unit by N + M-th magnetization is shown. The magnetization region overlaps the 2/3 portion of the N-th unit magnetization region in the height direction of the rotation axis (overlap ratio 66.7%), and further, the N + M-th magnetization with respect to the N-th magnetization position. An example in which the magnetic position is deviated by a central angle of 15 degrees per 1 mm displacement in the rotational axis direction height is shown. If the height h of each unit magnetized region formed by one magnetizing operation is 1 mm, the overlap ratio is 66.7%. Therefore, the magnetic pole head 16 is displaced by 1 mm in three rounds. The center angle shifted is 5 degrees (15/3). Accordingly, one round is set to (360 + 5) degrees, and the polarity is changed at intervals of the rotation angle (360 + 5) / 4 degrees.

  Depending on the arrangement pattern of the conductive wires 3 in the magnetizing head 16, it is possible to form both the N-pole region and the S-pole region adjacent to each other by one magnetizing operation. In FIG. The magnetization process will be described.

  First, in the first magnetization, an N-pole region is formed in a predetermined region (for example, the lowermost portion) on the peripheral surface. In the second magnetization in which the current direction is switched, an S pole region is formed adjacent to the first N pole region. This S pole region is formed with a shift in the height direction of the rotation axis from the N pole region by the first magnetization. The displacement amount in the height direction of the rotation axis in one magnetization is (displacement amount of one rotation 0.33 mm / 4). Similarly, in the third magnetization, an N-pole region is formed adjacent to the second S-pole region. This N-pole region is formed with a shift in the height direction of the rotation axis from the N-pole region formed by the second magnetization. Similarly, in the fourth magnetization, an S pole region is formed adjacent to the third N pole region. This S pole region is formed with a shift in the height direction of the rotation axis from the S pole region by the third magnetization.

  The next 5th magnetization is the 2nd round magnetization operation. The N-pole region formed by the fifth magnetization is formed so as to overlap the 2/3 portion of the first N-pole region in the height direction of the rotation axis and is shifted by 5 degrees with respect to the first N-pole region. . The magnetization region by the sixth to eighth magnetizations overlaps the 2/3 portion in the height direction of the rotation axis with respect to the second to fourth magnetization regions in the first round, and the second to fourth magnetizations. Each region is formed with a rotation angle shifted by 5 degrees.

  The 9th to 12th magnetizations are magnetization operations on the 3rd round, and overlap each 2/3 portion in the direction of the rotation axis height of the magnetization area by the magnetization on the 2nd round. They are formed with a rotation angle shifted by 5 degrees with respect to the eighth magnetized region.

  Furthermore, from the 13th time, the magnetization is the magnetization operation of the fourth round. The fourth-round magnetized region is located at a position displaced by 1 mm with respect to the first-round magnetized region and is formed with a center angle shifted by 15 degrees with respect to the first-round magnetized region.

  In this way, by performing the above magnetization operation over the entire circumferential surface while overlapping the unit magnetization regions and shifting the center angle, the magnetic poles inclined with respect to the rotation axis are formed on the circumferential surface of the magnetized body 1. A region is formed. FIG. 8 shows a magnetic pole region (FIG. 8A) formed on the peripheral surface of the adherend 1 and a plan development view thereof (FIG. 8B).

  FIG. 9 is a diagram for explaining another magnetization operation in the present embodiment. When the magnetization operation shown in FIG. 9 is compared with the magnetization operation shown in FIG. 7, the linear relative movement of the magnetized body 1 and the magnetization head 16 in the rotation axis direction in the magnetization operation shown in FIG. On the other hand, the relative movement of both in the magnetization operation shown in FIG. 9 is intermittently performed every round. Each time the magnetizing operation is performed once, the magnetized body 1 and the magnetizing head 16 are relatively moved in the rotation axis direction. Therefore, the height in the rotation axis direction of the unit magnetized region in the same turn is the same. Also in the magnetization operation of FIG. 9, a magnetic pole region inclined with respect to the rotation axis as shown in FIG. 8 can be formed.

  In order to detect the absolute angle with high accuracy by the magnetic encoder, the output waveform of the magnetic encoder needs to be a sin waveform without distortion.

  In the present invention, the inventor relatively moves the magnetized head or the magnetized body along the rotation axis of the magnetized body while supplying an alternating current to the magnetized head, and rotates the magnetized body. In a magnetizing operation in which at least P × M times of magnetizing operation is performed by rotating the magnetized body or the magnetizing head relative to the axis about P times (P is a natural number of 2 or more) or more, P × M N + M-th magnetization so as to overlap with a portion of the peripheral surface region that is magnetized by N-th (N is a natural number of 1 or more) of the first-time magnetization operations, and more than half of the rotational axis height direction. In addition, the N + M-th magnetization operation is performed so that the N + M-th magnetization position is shifted from the N-th magnetization position by a central angle of 12 to 20 degrees per 1 mm displacement in the rotational axis direction with respect to the N-th magnetization position. By doing so, it is possible to detect the absolute angle with high accuracy. It is possible to suppress the distortion rate of the output waveform of the encoder (distortion rate with respect to the ideal sine waveform) to within 2% and within a single pitch accuracy of 2%. The condition that the waveform distortion rate is within 2% and the single pitch accuracy is within 2% is a condition set so as to correspond to the detection accuracy of the absolute angle by an existing practically used resolver.

  Table 1 below corresponds to the overlap ratio of the magnetized bodies magnetized with a deviation of the central angle (skew angle φ in FIG. 6) of 20 degrees per displacement of 1 mm in height in the rotation axis direction in 6-pole magnetization. Showing magnetic properties.

  The magnetic output from the magnetized body (permanent magnet) magnetized by the above-described magnetization method was detected by a Hall element. As described above, the overlap rate is the degree of overlap of each magnetized region in the height direction of the rotation axis. Single pitch accuracy is the error ratio of the pitch of each magnetic pole. The measurement gap is the distance between the adherend and the Hall element that detects the magnetic output. As the measurement gap is smaller, a larger detection output (average magnetic flux density) can be obtained.

  According to Table 1, when the overlap rate is in the range of 0 to 50% or less, both the waveform distortion rate and the single pitch accuracy exceed 2% in any measurement gap. On the other hand, at an overlap rate of 55% exceeding 50%, the waveform distortion rate and single pitch accuracy are both within 2% within the measurement gap of 1.5 mm to 2.25 mm, and the average magnetic flux density is sufficient to exceed 10 mT. Large values were measured. Further, even when the overlap rate was 66.7%, both the waveform distortion rate and the single pitch accuracy were within 2% within the measurement gap range of 1 mm to 2 mm, and the average magnetic flux density was sufficiently large to exceed 10 mT. . Even at a measurement gap of 2.25 mm, the single pitch accuracy was 2.30%, slightly exceeding 2%, but the waveform distortion rate was 0.59%, which was a very good measurement result.

  From the results in Table 1, it is clear that the waveform distortion rate and the single pitch accuracy tend to decrease as the overlap rate increases. By setting the overlap rate to more than 50% at a skew angle of 20 degrees, the characteristics of the magnetic encoder can be obtained. As a result, it was possible to obtain an adherend having a waveform distortion rate of 2% or less and a single pitch accuracy of 2% or less.

  Table 2 shows the magnetic characteristics corresponding to the skew angle of the magnetized body magnetized with the overlapping rate of 66.7% in the 6-pole magnetization. Table 3 shows the magnetic characteristics corresponding to the skew angle of the magnetized body magnetized with the overlapping rate of 66.7% in the quadrupole magnetization.

  In Tables 2 and 3, it was found that the smaller the skew angle, the larger the waveform distortion rate. The skew angle at which the waveform distortion rate was within 2% was in the range of 12 degrees to 20 degrees. As for the single pitch accuracy, the smaller the skew angle, the smaller the single pitch accuracy, and even if the skew angle is less than 12 degrees, the single pitch accuracy is within 2%. Within 2% was not achieved.

  Based on the above results, the absolute angle can be detected with high accuracy by the permanent magnet type magnetic encoder by performing the gradient magnetization exceeding the overlap rate of 50% and the skew angle of 12 to 20 degrees per 1 mm displacement in the rotation axis direction. Is realized.

  In order to detect the absolute angle, it is necessary to obtain two types of outputs, a sin waveform output and a cosine waveform output, but two Hall elements are arranged at predetermined intervals along the rotation axis direction according to the skew angle. By doing so, a sin waveform output and a cos waveform output whose phases are shifted by 90 degrees can be obtained. In a configuration in which the interval between the two Hall elements is determined in advance, the skew angle is determined so that the sin waveform output and the cosine waveform output are shifted by 90 degrees in accordance with the interval, and the skew angle is obtained. By performing the magnetizing operation in this way, it is possible to obtain both waveform outputs with an accurate phase difference of 90 degrees.

  1: magnetized body, 2: core, 2a: tip surface (arc surface), 2b: convex portion, 2c: convex portion, 2d: through hole, 3: conductive wire, 10: rotation holding portion, 12: motor, 14 : Encoder, 16: Magnetizing head, 17: Vertical drive unit, 18: Power supply device, 20: Control means, 21: Control circuit, 22: Overall control device

Claims (3)

In a magnetizing method in which a magnetizing head is arranged at a position facing a circumferential surface of a cylindrical magnetized body, and the circumferential surface of the magnetized body is multipolarized with the number of poles M (M is a natural number of 2 or more). ,
While supplying an alternating current to the magnetized head, the magnetized head or the magnetized body is relatively moved along the rotation axis of the magnetized body, and the rotation axis of the magnetized body is centered. Further, the magnetized body or the magnetized head is relatively rotated P times (P is a natural number of 2 or more), and at least P × M times of magnetizing operation is performed.
The N + 1th magnetization operation is performed on the circumferential surface area adjacent to the circumferential direction of the circumferential surface region magnetized by the N (N is a natural number of 1 or more) magnetization operation among the P × M magnetization operations. Done
N + M so as to overlap with a portion of the peripheral surface region magnetized by the Nth (N is a natural number of 1 or more) magnetization operation of P × M times and exceeding half of the rotational axis height direction. Perform the second magnetizing operation,
The N + M-th magnetization operation is performed such that the N + M-th magnetization position is shifted by a center angle of 12 to 20 degrees per displacement of 1 mm in height in the rotation axis direction with respect to the N-th magnetization position. Magnetic method. In a magnetizing apparatus that magnetizes multiple poles so that the polarity alternately changes in the circumferential direction on the circumferential surface of a cylindrical magnetized body,
A core having a tip part that forms an arcuate surface along the peripheral surface and is in contact with or close to the peripheral surface of the adherend, and the other end side from the arcuate surface to the arcuate surface Positioning means for positioning and arranging the conductive wire extending in the direction, and a magnetizing head arranged so that a direction from one end side to the other end side of the arc surface is perpendicular to the circumferential direction;
The magnetized body or the magnetized head so that the arc surface of the magnetized head rotates or moves relatively in the circumferential direction of the magnetized body and moves along the rotation axis direction of the magnetized body. A drive unit for rotating or moving
A power supply for supplying an alternating current to the conductive wire while rotating or moving the magnetized body or the magnetized head by the driving unit ;
When the peripheral surface of the magnetized body is multipolar magnetized with the number of poles M (M is a natural number of 2 or more), the drive unit supplies the alternating current to the magnetized head, The magnetized head or the magnetized body is relatively moved along the rotation axis, and the magnetized body or the magnetized head is relatively moved P times around the axis of rotation of the magnetized body. (P is a natural number of 2 or more) and at least P × M times of magnetization operation,
The N + 1th magnetization operation is performed on the circumferential surface area adjacent to the circumferential direction of the circumferential surface region magnetized by the N (N is a natural number of 1 or more) magnetization operation among the P × M magnetization operations. Done
N + M so as to overlap with a portion of the peripheral surface region magnetized by the Nth (N is a natural number of 1 or more) magnetization operation of P × M times and exceeding half of the rotational axis height direction. Perform the second magnetizing operation,
The N + M-th magnetization operation is performed such that the N + M-th magnetization position is shifted by a center angle of 12 to 20 degrees per displacement of 1 mm in height in the rotation axis direction with respect to the N-th magnetization position. Magnetic device. In claim 2 ,
The positioning means of the magnetizing head includes a first arrangement area, a second arrangement area, which extends linearly from one end side to the other end side of the arc surface and is arranged in parallel at predetermined intervals in a direction in which the polarity changes. Forming an arrangement area and a third arrangement area on the arc surface;
The conductive wire is bent at a predetermined angle from an extension line of the second arrangement region on one end side of the arc surface and arranged in the first arrangement region, and the arc surface along the first arrangement region Extending from one end side to the other end side, bent in the opposite direction on the other end side of the arc surface, extending from the other end side of the arc surface to the one end side along the second arrangement region, Further bent in the opposite direction on one end side, extends from one end side to the other end side of the arc surface along the third arrangement area, and the second arrangement area on the other end side of the third arrangement area. A magnetizing device, wherein the magnetizing device is arranged to be bent so as to extend on an extension line.

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