JP4504164B2 - Method for manufacturing magnet for rotation angle sensor - Google Patents

Description

  The present invention relates to a method for manufacturing a magnet for a rotation angle sensor.

  Patent Document 1 discloses a rotation angle sensor. In this rotation angle sensor, the magnetic sensor detects the rotation angle of the rotation angle sensor magnet by detecting the magnetic field generated from the rotation angle sensor magnet. The rotation angle sensor magnet is manufactured by subjecting a circular magnetic body to radial magnetization.

  The circular magnetic body has a rotation axis, and a cross section perpendicular to the rotation axis of the circular magnetic body (hereinafter referred to as “flat cross section”) is a uniform circle. The circular magnetic body is divided into two divided parts by a dividing plane. Here, the dividing plane passes through the rotation axis and is orthogonal to the plane cross section. The circular magnetic body is a rotation angle sensor magnet, and after being attached to the rotation angle sensor, rotates around the rotation axis. The side surface of the circular magnetic body constitutes the outer edge of the flat cross section.

  FIG. 10 shows a flat cross section of the circular magnetic body M1. O is a rotation axis, PL is a dividing plane, M11 and M12 are dividing portions, and a and b are intersections of the dividing plane PL and the outer edge of the flat cross section.

  Next, a case where the radial magnetization process is performed on the circular magnetic body M1 will be described as an example. In the radial magnetization process, a magnetic field MF14 that is orthogonal to the rotation axis O, is directed from the side surface of the division portion M11 toward the rotation axis O, and has a uniform magnitude on the side surface of the division portion M11 is applied to the division portion M11. In addition, a magnetic field MF15 that is orthogonal to the rotation axis O, extends from the rotation axis O to the side surface of the divided portion M12, and has a uniform size on the side surface of the divided portion M12 is applied. The direction of the magnetic field MF14 is indicated by an arrow DMF12, and the direction of the magnetic field MF15 is indicated by an arrow DMF13. A magnetic field MF16 is generated from the rotation angle sensor magnet M5 manufactured by subjecting the circular magnetic body M1 to radial magnetization. The magnetic field MF16 is indicated by a magnetic field line LMF6.

  Here, regarding the rotation angle sensor magnet, a point fixed to the outer edge of the flat cross section is d1, a point arbitrarily set to the outer edge of the flat cross section is d2, and the rotation axis and the point d1 are set out of the radius of the flat cross section. The connecting radius is r1, the radius of the plane cross section is r2, the radius connecting the point d2 is r2, and the angle between the radius r1 and the radius r2 is the right rotation around the rotation axis. When a magnetic flux density distribution graph showing the relationship between the angle θ and the magnetic flux density at the point d2 is created with θ (deg) being measured with the direction being the positive direction, the magnetic flux density distribution graph has a rectangular waveform. It is desirable that When the magnetic flux density distribution graph has a rectangular waveform, the magnetic field detected by the magnetic sensor is proportional to the rotation angle of the rotation angle sensor magnet, so the magnetic sensor accurately determines the rotation angle of the rotation angle sensor magnet. This is because it can be detected.

FIG. 11 shows a magnetic flux density distribution graph C4 corresponding to the rotation angle sensor magnet M5. The magnetic flux density distribution graph C4 is drawn on a plane with the horizontal axis representing the angle θ and the vertical axis representing the magnetic flux density B4. When the point d2 coincides with the point a, the angle θ becomes 120, and when the point d2 coincides with the point b, the angle θ becomes 300.
JP-A-8-35809

  However, as indicated by the line of magnetic force LMF6 in FIG. 10, the magnetic flux density B4 increases as the point d2 is closer to the point a or b, so that the magnetic flux density distribution graph C4 has a peak at a portion where the angle θ is 120 or 300. P5-P8. Therefore, the shape of the magnetic flux density distribution graph C4 is different from the waveform of the rectangular wave.

  The present invention has been made to solve such a conventional problem, and its main object is to provide a magnet for a rotation angle sensor that makes the shape of a magnetic flux density distribution graph closer to a rectangular waveform than before. It is to provide a manufacturing method.

  In order to achieve the above object, a method of manufacturing a magnet for a rotation angle sensor according to the present invention includes a rotary magnetic axis, a circular magnetic body having a uniform cross-section orthogonal to the rotary axis, a radial magnetization process and an adjusted magnetization. A circular magnetic body comprising: performing one magnetization process of the processes; and subjecting the circular magnetic body subjected to the one magnetization process to the other of the radial magnetization process and the adjustment magnetization process. Is divided into two divided parts by a dividing plane that passes through the rotation axis and is orthogonal to the cross section, and radial magnetization treatment is performed in one of the two divided parts at one of the divided parts at right angles to the rotation axis and the outer edge of the cross section. A first magnetic field having a uniform size on the side surface is applied from the side surface to the rotation axis, and the other divided portion of the two divided portions is orthogonal to the rotation axis and from the rotation axis to the side surface. Second magnet with uniform size on the side And by multiplying the adjustment magnetization process, the intersection of the dividing plane and the side surfaces intersect, perpendicular to the dividing plane, is from one of the divided portions applying a third magnetic field toward the other split parts.

  According to the method of manufacturing a magnet for a rotation angle sensor according to the present invention, the peak of the magnetic flux density distribution graph can be smoothed by subjecting the circular magnetic body to the radial magnetization process and the adjustment magnetization process. This shape can be made closer to a rectangular waveform than before.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a radial magnetization processing apparatus 1. The radial magnetization processing apparatus 1 includes magnetization coils 11 and 21 and magnetization magnetic bodies 12 and 22. The magnetization coil 11 is wound around the side surface of the magnetization magnetic body 12, and the magnetization coil 21 is wound around the side surface of the magnetization magnetic body 22. The upper end surface 121 of the magnetizing magnetic body 12 is a curved surface that is recessed downward, the radius of curvature thereof coincides with the radius r of the flat cross section, and the lower end surface 221 of the magnetizing magnetic body 22 is recessed upward. It is a curved surface, and its radius of curvature coincides with the radius r of the flat section.

  In the radial magnetization processing apparatus 1, the side surface of the divided portion M <b> 11 is fitted into the upper end surface 121 of the magnetization magnetic body 12, and the side surface of the divided portion M <b> 12 is fitted into the lower end surface 221 of the magnetization magnetic body 22. By passing a current, the magnetic field MF1 is applied to the divided portion M11 and the magnetic field MF2 is applied to the divided portion M12. Thereby, the radial magnetization processing apparatus 1 magnetizes the circular magnetic body M1. The arrow DMF3 indicates the direction of the magnetic field MF1, the arrow DMF4 indicates the direction of the magnetic field MF2, the arrow DMF1 indicates the direction of the magnetic field generated inside the magnetization magnetic body 12, and the arrow DMF2 indicates the magnetization magnetic body. The direction of the magnetic field generated inside 22 is shown. The upper end surface 121 of the magnetizing magnetic body 12 is a curved surface that is recessed downward, and the radius of curvature thereof coincides with the radius r of the plane cross section, so that the magnetic field MF1 is orthogonal to the rotational axis O and is divided into portions M11. Toward the rotation axis O. Further, the magnitude of the magnetic field MF1 is uniform on the side surface of the divided portion M11. The lower end surface 221 of the magnetizing magnetic body 22 is a curved surface that is recessed upward, and the radius of curvature thereof coincides with the radius r of the plane cross section, so that the magnetic field MF2 is orthogonal to the rotational axis O and the rotational axis O To the side of the divided part M12. Further, the magnitude of the magnetic field MF2 is uniform on the side surface of the divided portion M12.

  FIG. 2 shows a magnet M2 manufactured by the radial magnetization processing apparatus 1 magnetizing the circular magnetic body M1. MF5 is a magnetic field generated from the magnet M2, and LMF1 is a line of magnetic force indicating the magnetic field MF5.

  FIG. 3 shows the adjusted magnetization processing apparatus 2. The adjustment magnetization processing device 2 includes a hollow coil 30. When a current flows through the hollow coil 30, a magnetic field MF6 is generated inside the hollow coil 30, and a magnetic field MF7 is generated outside the hollow coil 30. Magnetic field line LMF2 indicates magnetic field MF7, and arrow DMF7 indicates the direction of magnetic field MF6. The magnitude and direction of the magnetic field MF6 are uniform.

  FIG. 4 shows how the adjustment magnetization processing device 2 magnetizes the circular magnetic body M1. LMF3 is a line of magnetic force indicating the magnetic field MF6. The adjustment magnetization processing apparatus 2 installs the circular magnetic body M1 inside the hollow coil 30 so that the division plane PL is orthogonal to the magnetic field MF6, and causes a current to flow through the hollow coil 30 so that the magnetic field MF6 is applied to the circular magnetic body M1. Multiply. Thereby, the adjustment magnetization processing apparatus 2 magnetizes the circular magnetic body M1. The magnetic field MF6 is orthogonal to the division plane PL and travels from the division part M11 to the division part M12.

  FIG. 5 shows a magnet M3 manufactured by magnetizing the circular magnetic body M1 by the adjustment magnetization processing device 2. MF8 is a magnetic field generated from the magnet M3, and LMF3 is a magnetic field line indicating the magnetic field MF8.

  FIG. 6 shows a magnetic flux density distribution graph C1 showing the relationship between the angle θ and the magnetic flux density B1 at the point d2 of the magnet M2, and a magnetic flux density distribution showing the relationship between the angle θ and the magnetic flux density B2 at the point d2 of the magnet M3. It is a graph C2. The angle θ is the size of the angle formed by the radius r1 and the radius r2, and is measured with the right rotation direction around the rotation axis as the positive direction. In the present embodiment, the point d1 coincides with the point b as shown in FIGS.

  As the magnetic field line LMF1 in FIG. 2 indicates, the closer the point d2 is to the point a or b, the larger the magnetic flux density B1, so the magnetic flux density distribution graph C1 peaks at a portion where the angle θ is 0, 180, or 360. P1-P4.

  The magnetic field MF6 is orthogonal to the division plane PL and travels from the division part M11 to the division part M12. Further, the magnitude of the magnetic field MF6 is uniform. For this reason, as the magnetic field line LMF3 in FIG. 5 indicates, the closer the point d2 is to the point a or the point b, the smaller the magnetic flux density B2. The shape of the magnetic flux density distribution graph C2 is a sin wave waveform.

  Next, a method for manufacturing the rotation angle sensor magnet according to the present embodiment will be described. As shown in FIG. 1, the radial magnetization processing apparatus 1 fits the side surface of the divided portion M11 into the upper end surface 121 of the magnetization magnetic body 12, and fits the side surface of the divided portion M12 into the lower end surface 221 of the magnetization magnetic body 22. A current is passed through the magnetizing coils 11 and 21. Thereby, the radial magnetization processing apparatus 1 manufactures the magnet M2.

  Next, as shown in FIG. 4, the adjustment magnetization processing device 2 installs the magnet M <b> 2 inside the hollow coil 30 so that the division plane PL is orthogonal to the magnetic field MF <b> 6, and causes a current to flow through the hollow coil 30. Thereby, the adjustment magnetization processing apparatus 2 manufactures the magnet M4 for rotation angle sensors.

  FIG. 7 shows a rotation angle sensor magnet M4. The manufacturing method of the rotation angle sensor magnet according to the present embodiment is substantially to apply the magnetic fields MF9 and MF10 to the circular magnetic body M1. The direction of the magnetic field MF9 is indicated by an arrow DMF9, and the direction of the magnetic field MF10 is indicated by an arrow DMF10.

  Comparing the magnetic field MF9 and the magnetic field MF1 shown in FIG. 2 at a certain point in the divided portion M11, the magnetic field MF9 has the same size as the magnetic field MF1, and the magnetic field MF9 has a horizontal direction (specifically, a diameter ab (Direction) component is smaller than the absolute value of the horizontal component of the magnetic field MF1, and the absolute value of the vertical component (specifically, the direction perpendicular to the division plane PL) of the magnetic field MF9 is the vertical value of the magnetic field MF1. It is larger than the absolute value of the direction component. When the magnetic field MF10 is compared with the magnetic field MF2 shown in FIG. 2 at a certain point in the divided portion M12, the magnetic field MF10 has the same magnitude as the magnetic field MF2, and the absolute value of the horizontal component of the magnetic field MF10 is the same as that of the magnetic field MF2. The absolute value of the vertical component of the magnetic field MF10 is smaller than the absolute value of the horizontal component, and is larger than the absolute value of the vertical component of the magnetic field MF2. Therefore, when the magnetic flux density at the point d2 of the rotation angle sensor magnet M4 is B3, the point d2 is fixed, and when the magnetic flux density B1 and the magnetic flux density B3 at this point d2 are compared, The absolute value is smaller than the absolute value of the horizontal component of the magnetic flux density B1, and the absolute value of the vertical component of the magnetic flux density B3 is larger than the absolute value of the vertical component of the magnetic flux density B1.

  FIG. 8 is a magnetic flux density distribution graph C3 showing the relationship between the angle θ and the magnetic flux density B3. Since the magnetic flux densities B1 and B3 have the relationship described above, the magnetic flux density distribution graph C3 reduces the absolute value of the magnetic flux density B1 at the peaks P1 to P4 as shown in FIGS. Only the absolute value of the magnetic flux density B1 between the peaks P1 to P4 is increased (see arrows E1 to E3 and broken lines E4 to E7).

  As described above, the magnetic flux density distribution graph C3 is obtained by smoothing the peaks P1 to P4 of the magnetic flux density distribution graph C1, and therefore, the manufacturing method of the magnet for the rotation angle sensor according to the present embodiment is the magnetic flux density distribution graph C3. This shape can be made closer to a rectangular wave waveform than in the prior art.

  Since the magnitude of the magnetic field MF6 is uniform, the peaks P1 to P4 of the magnetic flux density distribution graph C1 can be uniformly smoothed. Therefore, the manufacturing method of the magnet for a rotation angle sensor according to the present embodiment can make the shape of the magnetic flux density distribution graph C3 closer to a rectangular wave waveform than in the prior art.

  Since the method for manufacturing the rotation angle sensor magnet according to the present embodiment generates the magnetic field MF6 by using the hollow coil 30, the magnetic field MF6 can be generated reliably and stably.

  Next, a modification of the present embodiment will be described. FIG. 9 shows how the adjustment magnetization processing device 3 magnetizes the magnet M2. The adjustment magnetization processing apparatus 3 includes a Helmholtz coil composed of magnetization coils 41 and 51. MF12 is a magnetic field generated inside the magnetizing coil 41, MF13 is a magnetic field generated inside the magnetizing coil 51, DMF11 is an arrow indicating the direction of the magnetic field MF12, and DMF12 is the direction of the magnetic field MF13. It is an arrow which shows.

  The adjustment magnetization processing device 3 generates a magnetic field MF 6 between the magnetization coil 41 and the magnetization coil 51 by supplying power to the magnetization coils 41 and 51. Therefore, in the present modification, the magnet M2 is magnetized using the adjustment magnetization processing device 3 instead of the adjustment magnetization processing device 2. Specifically, the adjustment magnetization processing apparatus 3 installs the magnet M2 so that the division plane PL is orthogonal to the magnetic field MF6, and causes a current to flow through the magnetization coils 41 and 51. Thereby, the adjustment magnetization processing apparatus 3 magnetizes the magnet M2.

  Since the magnetic angle MF6 is generated by using the Helmholtz coil in the method for manufacturing the rotation angle sensor magnet according to this modification, the magnetic field MF6 can be generated reliably and stably.

  Needless to say, the present embodiment and modifications may be modified without departing from the spirit of the present invention. For example, in the present embodiment, the circular magnetic body M1 is a cylinder, but may be a column. Further, although the magnetic field MF6 is applied to the entire magnet M2, the magnetic field MF6 may be applied only to the intersection where the side surface of the magnet M2 (the portion corresponding to the side surface of the circular magnetic body M1) and the division plane intersect. Further, the adjustment magnetization processing device 2 or the adjustment magnetization processing device 3 manufactures the magnet M3 by magnetizing the circular magnetic body M1, and the radial magnetization processing device 1 magnetizes the magnet M3, so that the rotation angle sensor magnet M4 is obtained. It may be manufactured.

It is explanatory drawing which shows a radial magnetization processing apparatus. It is explanatory drawing which shows the magnet manufactured by giving a radial magnetization process to a circular magnetic body. It is explanatory drawing which shows an adjustment magnetization processing apparatus. It is explanatory drawing which shows the mode of adjustment magnetization process. It is explanatory drawing which shows the magnet manufactured by performing an adjustment magnetization process to a circular magnetic body. It is explanatory drawing which shows a magnetic flux density distribution graph. It is explanatory drawing which shows the magnet for rotation angle sensors manufactured by giving a radial magnetization process and an adjustment magnetization process to a circular magnetic body. It is explanatory drawing which shows a magnetic flux density distribution graph. It is explanatory drawing which shows the mode of adjustment magnetization process. It is explanatory drawing which shows the conventional magnet for rotation angle sensors. It is explanatory drawing which shows a magnetic flux density distribution graph.

Explanation of symbols

M1 ... Circular magnetic body M11, M12 ... Divided part M4 ... Magnet for rotation angle sensor O ... Rotating shaft PL ... Divided plane 1 ... Radial magnetization processing device 2, 3 ... Adjustment magnetization processing device 11, 21 ... Magnetizing coil 12, 22 ... Magnetic body 121 ... Upper end surface 221 ... Lower end surface

Claims (4)

Applying a magnetization process of one of a radial magnetization process and an adjustment magnetization process to a circular magnetic body having a rotation axis and having a uniform cross section perpendicular to the rotation axis;
Applying the other of the radial magnetization process and the adjustment magnetization process to the circular magnetic body subjected to the one magnetization process,
The circular magnetic body is divided into two divided parts by a dividing plane passing through the rotation axis and orthogonal to the cross section,
In the radial magnetization process, one of the two divided parts is perpendicular to the rotation axis and is directed from the side surface constituting the outer edge of the cross section toward the rotation axis, and the size on the side surface is uniform. The first magnetic field is applied, and the other divided portion of the two divided portions is perpendicular to the rotation axis, is directed from the rotation shaft to the side surface, and has a uniform size on the side surface. Two magnetic fields,
The adjustment magnetization process is to apply a third magnetic field perpendicular to the division plane and from the one division portion toward the other division portion at an intersection where the division plane and the side surface intersect. Manufacturing method of magnet for angle sensor. In the manufacturing method of the magnet for rotation angle sensors according to claim 1,
A method of manufacturing a magnet for a rotation angle sensor, wherein the magnitude of the third magnetic field is uniform. In the manufacturing method of the magnet for rotation angle sensors according to claim 1 or 2,
The third magnetic field is a method for manufacturing a magnet for a rotation angle sensor generated in a hollow portion of a hollow coil. In the manufacturing method of the magnet for rotation angle sensors of any one of Claims 1-3,
The third magnetic field is a method for manufacturing a magnet for a rotation angle sensor generated between two coils constituting a Helmholtz coil.

Images