JP2020129951A - Electric motor and manufacturing method thereof - Google Patents

Abstract

To provide an electric motor having a magnetic encoder with high mounting accuracy, and a manufacturing method of the same.SOLUTION: An electric motor 100 includes: a rotor 10; a stator 20 for rotatably supporting the rotor 10; and a magnetic encoder 70 for detecting a rotation angle of the rotor 20. The magnetic encoder 70 has a magnetic ring 72 made of a rubber magnet vulcanized and adhered to a component of the electric motor 100 as a permanent magnet for detecting a rotation angle.SELECTED DRAWING: Figure 1

Description

The present invention relates to electric motors.

There is known an electric motor having a rotation angle detection means for detecting the rotation angle of a rotor (see, for example, Patent Document 1).

JP, 2005-192345, A

However, if the mounting accuracy of the rotation angle detecting means varies, the detection accuracy of the rotation angle decreases.
Therefore, it is an object of the present invention to provide an electric motor having a magnetic encoder with high mounting accuracy as a rotation angle detecting means, and a manufacturing method thereof.

In order to solve the above problems, an electric motor according to an aspect of the present invention includes a rotor, a stator that rotatably supports the rotor, and a magnetic encoder that detects a rotation angle of the rotor. The magnetic encoder has, as a permanent magnet for detecting a rotation angle, an annular magnetic ring formed of a rubber magnet vulcanized and bonded to a component (excluding the magnetic encoder) constituting the electric motor. And

According to the electric motor of one aspect of the present invention, in the magnetic encoder, the magnetic ring made of a rubber magnet for detecting the rotation angle is vulcanized and adhered to the components (excluding the magnetic encoder) constituting the electric motor. Therefore, the magnetic ring of the magnetic encoder and the electric motor are integrated in advance. Therefore, it is possible to improve the mounting accuracy of the magnetic encoder, as compared with an electric motor in which the magnetic ring after rotational magnetization is incorporated as a component separate from the component of the electric motor.

In the electric motor according to one aspect of the present invention, the component has a fitting surface that is fitted in a radial direction with a bearing that rotatably supports the rotor, and the magnetic ring has a central axis of the fitting surface. It is preferable that the magnet is rotationally magnetized on the basis of.
With such a configuration, the magnetic ring vulcanized and bonded is rotationally magnetized on the basis of the central axis of the fitting surface that is fitted in the bearing in the radial direction. Therefore, it is suitable for a magnetic ring that is rotationally magnetized with high relative accuracy.

In order to solve the above problems, a method of manufacturing an electric motor according to an aspect of the present invention includes a rotor, a stator that rotatably supports the rotor, and a magnet that detects a rotation angle of the rotor. An encoder and a method for manufacturing an electric motor, wherein the rotor is one of the components (excluding the magnetic encoder) that constitutes the electric motor as a permanent magnet used in the magnetic encoder for detecting the rotation angle. Characterized in that an annular magnetic ring made of a rubber magnet is vulcanized and bonded to a component having a fitting surface to be rotatably supported on the bearing in a radial direction. ..

According to the method of manufacturing an electric motor according to one aspect of the present invention, an annular magnetic ring made of a rubber magnet is used as a permanent magnet for detecting a rotation angle, which is used in a magnetic encoder. Of the components (excluding the magnetic encoder) that form (1), the components that have a fitting surface that is fitted in the radial direction with the bearing that rotatably supports the rotor are vulcanized and adhered before being rotationally magnetized, The magnetic ring for detecting the rotation angle and the electric motor are integrated in advance.
Therefore, the mounting accuracy of the magnetic encoder can be improved as compared with a configuration in which the magnetic ring after rotational magnetization is incorporated in the electric motor as a component separate from the component that constitutes the electric motor.

Here, in the electric motor according to one aspect of the present invention, it is preferable that after the vulcanization and adhesion, the magnetic ring is subjected to rotational magnetization necessary for a magnetic encoder with reference to the central axis of the fitting surface.
With such a configuration, after vulcanization and adhesion, the magnetic ring is rotationally magnetized as required with respect to the center axis of the mating surface that is fitted in the bearing in the radial direction. It is suitable for application. Therefore, the electric motor manufactured thereby is suitable for having a magnetic encoder with high mounting accuracy.

As described above, according to the present invention, it is possible to provide an electric motor having a magnetic encoder with high mounting accuracy and a manufacturing method thereof.

It is a typical longitudinal section showing the main composition of the electric motor of a first embodiment. It is a typical longitudinal cross-sectional view explaining the rotation magnetization process to a magnetic ring in the electric motor of 1st embodiment. It is a typical longitudinal cross-sectional view which shows the main structures of the electric motor of the modification of 1st embodiment. It is a typical longitudinal cross-sectional view explaining the rotation magnetization process to a magnetic ring in the electric motor of the modification of 1st embodiment. It is a typical longitudinal section showing the main composition of the electric motor of a second embodiment. It is a typical longitudinal cross-sectional view explaining the rotation magnetization process to a magnetic ring in the electric motor of 2nd embodiment. It is a typical longitudinal section showing the main composition of the motor of the modification of a second embodiment. It is a typical longitudinal cross-sectional view explaining the rotation magnetization process to a magnetic ring in the electric motor of the modification of 2nd embodiment. It is a typical longitudinal cross-sectional view showing a main configuration of an electric motor of a first comparative example. It is a typical longitudinal cross-sectional view explaining the rotation magnetization process to a magnetic ring in the electric motor of a 1st comparative example. It is a typical longitudinal cross-sectional view showing a main configuration of an electric motor of a second comparative example. It is a typical longitudinal cross-sectional view explaining the rotation magnetization process to a magnetic ring in the electric motor of a 2nd comparative example.

Hereinafter, embodiments and modified examples (and comparative examples) of the present invention will be described with reference to the drawings. The drawings are schematic. Therefore, it should be noted that the relationship between the thickness and the plane size, the ratio, and the like are different from the actual ones, and the drawings include portions where the dimensional relationship and the ratio are different from each other.
The following embodiments and modifications (and comparative examples) exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes constituent parts. The material, shape, structure, arrangement, etc. of are not specified in the following embodiments and modifications.

(First embodiment)
The electric motor of the first embodiment is an example of an outer rotor type.
As shown in FIG. 1, the electric motor 100A of the first embodiment includes a rotor 10 and a stator 20. The rotor 10 is located on the outer peripheral side in the radial direction with the rotation axis CL as the center with respect to the stator 20. The inner peripheral stator 20 rotatably supports the outer peripheral rotor 10 via a bearing 30. In addition, in this example, although a cavity centering on the rotation axis CL is provided inside the stator 20, the inside of the stator 20 may not be a cavity.

In the example of the first embodiment, the permanent magnet 40 is provided on the inner peripheral surface of the rotor 10, and the coil 50 is provided on the outer peripheral surface of the stator 20. However, the positional relationship between the permanent magnet 40 and the coil 50 may be reversed. The coil 50 is wound around the core 60 of the stator 20. The core 60 functions as an iron core of the coil 50. The rotor 10 is rotationally driven according to the excitation drive of the coil 50.

The electric motor 100A is provided with a magnetic encoder 70 that detects the rotation angle of the rotor 10. Hereinafter, in the axial direction of the rotating shaft CL, the side on which the magnetic encoder 70 is provided is referred to as one end side of the electric motor 100A, and the opposite side is referred to as the other end side. In the example of the first embodiment, the output shaft portion 10f that functions as the output shaft of the electric motor 100A may be provided on one end side of the rotor 10 but on the other end side.
The magnetic encoder 70 has a sensor unit 71 and an annular magnetic ring 72 centered on the rotation axis CL. The magnetic ring 72 of the first embodiment is a rubber magnet that is rotationally magnetized so that the multiple poles of the magnet are arranged in an annular shape so as to perform the function required as a magnetic encoder.

In the first embodiment, the rotor 10 is provided with the magnetic ring 72, and the stator 20 is provided with the sensor portion 71. However, the positional relationship between the magnetic ring 72 and the sensor unit 71 may be reversed.
The sensor unit 71 uses, for example, a Hall element or the like, and is configured to be able to detect the rotation angle of the rotor 10 based on the degree of change in the relative angle of the magnetic ring 72.
In the first embodiment, as the Hall element or the like of the sensor unit 71, a magnetoresistive effect element that functions as a so-called MR (Magneto Resistive) sensor or the like can be used.

An annular plate-shaped cover 80 that covers the sensor unit 71 and the magnetic ring 72 is provided at one end 20b of the stator 20. The inner peripheral side of the cover 80 is fixed to the stator 20 with screws 81.
The cover 80 covers the opening so that the magnetic encoder 70 is not exposed to the outside of the electric motor 100A. An annular plate-shaped cover 90 is provided on the other end side of the stator 20. The cover 90 has an inner peripheral end in the radial direction fixed to the outer peripheral surface on the other end side of the stator 20.
The sensor unit 71 is provided on the sensor support substrate 73. The sensor support substrate 73 is screwed and fixed to the second base portion 20a of the stator 20 using screws 74. The sensor support substrate 73 does not have to be annular. The sensor support substrate 73 may have a size necessary to support the sensor unit 71 and to provide wiring or the like connected to the sensor unit 71.

In the first embodiment, the sensor support substrate 73 is provided so that the tip end portion on which the sensor unit 71 is mounted extends to a position facing the upper surface of the magnetic ring 72. The sensor unit 71 is supported at a position facing the magnetic ring 72 in a non-contact state.
When the rotor 10 rotates, the magnetic ring 72 fixed to the rotor 10 rotates integrally. The sensor unit 71 can detect a change in magnetism caused by the rotation of the magnetic ring 72, and can acquire information on the rotation angle of the rotor 10 based on the change in magnetism.

Here, the magnetic encoder 70 employs a magnetic ring 72 formed of a ring-shaped rubber magnet as a permanent magnet for detecting the rotation angle of the rotor 10. The magnetic ring 72 is previously vulcanized and adhered to the rotor 10 that is a component (excluding the magnetic encoder) of the electric motor 100A.
Particularly, in the first embodiment, in the electric motor 100A including the magnetic encoder 70, a component (for example, the rotor 10 in the first embodiment) that rotates by being fitted with the bearing 30 that determines the center of the rotation axis CL of the electric motor 100A. The rubber magnet magnetic ring 72 is directly vulcanized and bonded.

In the first embodiment, the magnetic ring mounting portion 10 a is formed on one end side of the rotor 10 on the end side of the fitting surface 10 j with the bearing 30. The surface facing the one end side of the magnetic ring mounting portion 10a is an adhesion surface 10m for vulcanizing and adhering the rubber magnet. In the first embodiment, a ring-shaped rubber magnet is vulcanized and bonded to the bonding surface 10 m, and then the ring-shaped rubber magnet is rotationally magnetized to form the magnetic ring 72.

At the time of rotating and magnetizing, as shown in FIG. 2, before the rotor 10 is incorporated in the electric motor 100A, the fitting surface 10j of the rotor 10 which is fitted in the bearing 30 in the radial direction is used as the reference surface X, and the rotating shaft is rotated. While rotating the rotor 10 around CL, the magnetic ring 72 made of rubber magnet after vulcanization and adhesion is rotationally magnetized. After that, the rotor 10 is incorporated in the electric motor 100. As a result, even after the rotor 10 is incorporated in the electric motor 100A, the center of rotational magnetization of the magnetic ring 72 and the center of the rotation axis CL of the electric motor 100A are prevented or suppressed from deviating from each other. Note that the symbol G in FIG. 2 indicates an image in which rotational magnetization is performed (the same applies to other examples).

Next, operation effects of the electric motor 100A of the first embodiment will be described.
Here, FIGS. 9 and 10 show an electric motor 101 of a first comparative example. 9 and 10, the same components as those in the first embodiment are denoted by the same reference numerals, and the components to be compared are the same as those in the first embodiment except for the matters described by explicitly indicating the reference numerals below. A hundred digit (1xx) is added to the code (xx) in the embodiment for comparison, and detailed description thereof will be appropriately omitted (same in the second comparative example described later).

In the structure of the electric motor 101 of the first comparative example, in the magnetic encoder 170, the magnetic ring 172 is vulcanized and bonded to the core metal part 175 different from the constituent parts of the electric motor 101.
In the first comparative example, the cored bar component 175 is manufactured by pressing or drawing a sheet metal. Therefore, the magnetic encoder 170 is attached to the rotor 110 when it is incorporated into the electric motor 101. It should be noted that FIG. 10 shows an image to be incorporated into the electric motor 101 after the magnetic ring 172 on the cored bar component 175 is rotationally magnetized.

Therefore, in the first comparative example, when the magnetized magnetic ring 171 is attached to the electric motor 101, it is difficult to accurately align the center of the rotation axis CL of the electric motor 101 with the magnetized center of the magnetic ring 171. Is. Therefore, in the first comparative example, even if the magnetic poles could be formed with high accuracy when the magnetic ring 171 was rotationally magnetized, a high position could be detected due to mutual center misalignment when the magnetic ring 171 was attached to the rotor 110. It is difficult to ensure accuracy.

On the other hand, in the electric motor 100A of the first embodiment, the magnetic ring 71 made of rubber magnet is pre-vulcanized and adhered to the rotor 10 that is fitted and rotated with the bearing 30 that rotatably supports the rotating shaft 10 of the electric motor 100A. Then, after that, the magnetic ring 71 after vulcanization and adhesion is subjected to rotational magnetization necessary for the magnetic encoder while rotating around the rotation axis CL with the fitting surface 10j with the bearing 30 as the reference surface X. Manufactured.

As a result, in the electric motor 100A of the first embodiment, even after the magnetic ring 71 is incorporated in the electric motor 100A together with the rotating shaft 10, the center of rotational magnetization and the center of the rotating shaft CL of the electric motor 100A are prevented from being displaced from each other. Can be suppressed. Therefore, the magnetic encoder 70 has high mounting accuracy. Therefore, the magnetic encoder 70 can ensure high position detection accuracy.
Further, in the electric motor 100A of the first embodiment, the bearing 30 and the magnetic ring mounting portion 10a of the rotor 10 are arranged between the coil 50 and the sensor portion 71 in the axial direction. Therefore, the influence of the magnetism of the coil 50 and the permanent magnet 40 on the sensor unit 71 can be further suppressed.

(Modification of the first embodiment (outer rotor type electric motor))
Next, an electric motor 100B according to a modified example of the first embodiment will be described with reference to FIGS. 3 and 4. The same or corresponding configurations as those of the above-described first embodiment will be denoted by the same reference numerals, and detailed description thereof will be appropriately omitted (the same applies to the second embodiment and other modifications hereinafter).
The modified example of the first embodiment is an example in which a thick outer ring retainer 12 is targeted as a component having a fitting surface 12j that is fitted in a radial direction with a bearing 30 that supports the rotating shaft 10 of the electric motor 100B.
As shown in FIG. 3, in the modified example of the first embodiment, the fitting portion between the rotor 10 and the bearing 30 has a split structure, and the rotor body 10B and the outer ring retainer 12 having an annular shape are used to form the rotor 10. Is configured. The annular magnetic ring 72 is different from the first embodiment in that it is mounted on the mounting surface 12m on the upper surface of the outer ring retainer 12.

In the modified example of the first embodiment, first, the annular magnetic ring 72 formed of a rubber magnet is directly vulcanized and adhered to the mounting surface 12m of the outer race retainer 12 in advance. After that, as shown in FIG. 4, the outer ring retainer 12 is rotated about the rotation axis CL with the fitting surface 12j with the bearing 30 as the reference plane X, and the magnetic ring 72 is rotationally magnetized as a magnetic encoder. Give. After that, as shown in FIG. 3, the outer ring retainer 12 and the rotor body 10B are incorporated into the electric motor 100B.

In the modification of the first embodiment, a thick outer ring retainer 12 having a fitting surface 12j that is fitted in the bearing 30 in the radial direction is targeted as a component (excluding a magnetic encoder) that constitutes the electric motor 100B. In advance, the magnetic ring 72 made of rubber magnet is directly vulcanized and adhered to the mounting surface 12m of the outer ring retainer 12 in advance, and the mating surface 12j that is radially fitted to the bearing 30 is used as the reference surface X, and the rotation axis CL is used. The magnetic ring 72 is rotationally magnetized while the outer ring retainer 12 is rotated around.
Therefore, as in the above-described first embodiment, even after the outer ring retainer 12 is incorporated in the electric motor 100B, the center of rotational magnetization of the magnetic ring 72 and the center of the rotary shaft 10 of the electric motor 100B are prevented or suppressed from deviating from each other. it can. Therefore, the magnetic encoder 70 has high mounting accuracy. Therefore, the magnetic encoder 70 can ensure high position detection accuracy.

(Second embodiment)
Next, a second embodiment will be described. The electric motor of the second embodiment is an example of an inner rotor type. In addition, the same reference numerals are given to the same or corresponding configurations as those of the first embodiment, and the description thereof will be appropriately omitted.
As shown in FIG. 5, an electric motor 100C of the second embodiment includes a rotor 10 and a stator 20. The rotor 10 is located on the radially inner side with respect to the stator 20 about the rotation axis CL. The outer peripheral side stator 20 rotatably supports the inner peripheral side rotor 10 via a bearing 30. In addition, in this example, although the cavity centering on the rotation axis CL is provided inside the rotor 10, the inside of the rotor 10 may not be a cavity.

In the example of the second embodiment, the permanent magnet 40 is provided on the outer peripheral surface of the rotor 10, and the coil 50 is provided on the inner peripheral surface of the stator 20. However, the positional relationship between the permanent magnet 40 and the coil 50 may be reversed. The coil 50 is wound around the core 60 of the stator 20. The core 60 functions as an iron core of the coil 50. The rotor 10 is rotationally driven according to the excitation drive of the coil 50.

The electric motor 100C is provided with a magnetic encoder 70 that detects the rotation angle of the rotor 10. Hereinafter, in the axial direction of the rotation shaft CL, the side on which the magnetic encoder 70 is provided is referred to as one end side of the electric motor 100C, and the opposite side is referred to as the other end side. In the example of the second embodiment, the output shaft portion 10f that functions as the output shaft of the electric motor 100C is on one end side of the rotor 10, but may be on the other end side.
The magnetic encoder 70 has a sensor unit 71 and an annular magnetic ring 72 centered on the rotation axis CL. The magnetic ring 72 of the second embodiment is a rubber magnet that is rotationally magnetized so that the multiple poles of the magnet are arranged in an annular shape so as to have a function required as a magnetic encoder.

In the second embodiment, the rotor 10 is provided with the magnetic ring 72, and the stator 20 is provided with the sensor portion 71. The sensor unit 71 is configured to be able to detect the rotation angle of the rotor 10 based on the degree of change in the relative angle of the magnetic ring 72. However, the positional relationship between the magnetic ring 72 and the sensor unit 71 may be reversed.

An annular plate-shaped cover 80 that covers the sensor unit 71 and the magnetic ring 72 is provided at one end 20b of the stator 20. The outer periphery of the cover 80 is fixed by screws 81. The cover 80 covers the opening so that the magnetic encoder 70 is not exposed to the outside of the electric motor 100C.
Further, an annular base portion 20d integrally formed with the side wall portion 20h is integrally formed on the other end side of the stator 20. The base portion 20d is formed so that the inner peripheral end portion in the radial direction covers the opening portion on the other end side of the stator 20 and the rotor 10.
The sensor unit 71 is provided on the sensor support substrate 73. The sensor support substrate 73 is screwed and fixed to the second base portion 20a of the stator 20 using screws 74. The sensor support substrate 73 does not have to be annular. The sensor support substrate 73 may have a size necessary to support the sensor unit 71 and to provide wiring or the like connected to the sensor unit 71.

The second embodiment is directed to the rotor 10 as a component fitted to the bearing 30 that supports the rotor 10 that serves as the rotation shaft of the electric motor 100C.
That is, as shown in FIG. 6, the magnetic ring 72 made of rubber magnet is directly vulcanized and adhered to the adhesion surface 10m of the magnetic ring mounting portion 10a formed on the rotor 10 in advance. After that, the magnetic ring 72 is rotationally magnetized while rotating the rotor 10 about the rotation axis CL with the fitting surface 10j that is fitted in the bearing 30 in the radial direction as the reference surface X. Then, as shown in FIG. 5, the rotor 10 is incorporated into the electric motor 100C.

Here, for example, in the structure of the electric motor 102 of the second comparative example shown in FIGS. 11 and 12, in the magnetic encoder 170, the magnetic ring 172 is vulcanized into a core metal part 175 different from the constituent parts of the electric motor 102. It is glued.
In the second comparative example, the cored bar component 175 is manufactured by pressing or drawing a sheet metal as in the first comparative example. Therefore, the magnetic encoder 170 is attached to the rotor 110 when it is incorporated in the electric motor 102. It should be noted that FIG. 12 shows an image to be incorporated in the electric motor 101 after the magnetic ring 172 on the cored bar component 175 is rotationally magnetized.

Therefore, in the second comparative example, when the magnetized magnetic ring 171 is attached to the electric motor 102, it is difficult to accurately align the center of the rotating shaft CL of the electric motor 102 with the magnetized center of the magnetic ring 171. Is.
Therefore, in the second comparative example, even if the magnetic poles could be accurately formed when the magnetic ring 171 was rotationally magnetized, even if the magnetic ring 171 was attached to the rotor 110, it was possible to detect a high position due to the mutual misalignment. It is difficult to ensure accuracy.

On the other hand, in the second embodiment, the magnetic ring 72 is directly vulcanized and adhered to the thick rotor 10 that fits and rotates with the bearing 30, and the fitting surface 10j that is fitted with the bearing 30 in the radial direction is used as a reference. With the surface X, the magnetic ring 72 is rotationally magnetized while rotating the rotor 10 about the rotation axis CL.
Therefore, according to the second embodiment, similarly to the first embodiment and its modification, even after the rotor 10 is incorporated in the electric motor 100C, the center of rotation and magnetization of the magnetic ring 72 and the rotation of the electric motor 100C. It is possible to prevent or suppress the deviation of the center of the axis CL. Therefore, also in the second embodiment, the magnetic encoder 70 has high mounting accuracy. Therefore, the magnetic encoder 70 can ensure high position detection accuracy.

In addition, as in the structures of the electric motors 101 and 102 of the first to second comparative examples shown in FIGS. 9 to 12, in the magnet ring 171 vulcanized and bonded to another core metal component 175, “core metal + By attaching a "rubber magnet" to the rotor 110 and then rotating and magnetizing it as in the first and second embodiments, it is possible to temporarily obtain the effect of improving accuracy.
However, since the cored bar component 175 is manufactured by pressing or drawing a sheet metal, it is difficult to ensure accuracy such as flatness. Therefore, in the cored bar component 175 in which sufficient accuracy is not ensured, there is a problem that it is difficult to form the magnetic pole with high accuracy when magnetized.
On the other hand, in the first and second embodiments, the rotor 10, the stator 20, etc. are used as components having a fitting surface that is fitted in the radial direction with the bearing 30 that supports the rotating shaft 10 of the electric motors 100A and 100C. Since an annular magnetic ring made of rubber magnet is directly vulcanized and adhered to thick-walled parts, it is easy to control the accuracy of flatness, etc., and it can be said that it is excellent in accurately forming magnetic poles during rotary magnetization. ..

(Modification of Second Embodiment (Inner Rotor Electric Motor))
Next, a modified example of the second embodiment will be described with reference to FIGS. 7 and 8.
The modified example of the second embodiment is an example in which a thick inner ring retainer 22 is targeted as a component having a fitting surface that is fitted in a radial direction with a bearing 30 that supports the rotating shaft 10 of the electric motor 100D.
In the modified example of the second embodiment, as shown in FIG. 7, the fitting portion between the rotor 10 and the bearing 30 has a split structure, and the rotor body 10D and the annular outer ring retainer 22 form the rotor 10. Is configured. The annular magnetic ring 72 is different from the second embodiment in that it is mounted on the mounting surface 22m on the upper surface of the outer ring retainer 22.

In the modification of the second embodiment, as shown in FIG. 8, a magnetic ring 72 made of rubber magnet is directly added in advance to a thick inner ring retainer 22 having a fitting surface 22j that is fitted in the bearing 30 in the radial direction. Sulfur bond. After that, while the inner ring retainer 22 is rotated about the rotation axis CL with the fitting surface 22j that is fitted in the bearing 30 in the radial direction as the reference surface X, the magnetic ring 72 is rotationally magnetized as a magnetic encoder. .. After that, as shown in FIG. 7, the inner ring retainer 22 and the rotor body 10D are incorporated into the electric motor 100D.

Therefore, according to the modified example of the second embodiment, even after the inner ring presser 22 is incorporated in the electric motor 100D, the rotary magnetization of the magnetic ring 72 is performed in the same manner as the first embodiment, the modified example thereof, and the second embodiment. It is possible to prevent or suppress the deviation of the center of the rotation axis from the center of the rotating shaft 10 of the electric motor 100D. Therefore, according to the modified example of the second embodiment, the magnetic encoder 70 has high mounting accuracy. Therefore, the magnetic encoder 70 can ensure high position detection accuracy.
It should be noted that the electric motor and the method for manufacturing the same according to the present invention are not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the spirit of the present invention.

10 rotor 12 outer ring retainer 20 stator 22 inner ring retainer 30 bearing 40 permanent magnet 50 coil 60 core 70 magnetic encoder 71 sensor unit 72 magnetic ring 73 substrate 80 cover 90 cover 100 electric motor CL rotational axis X (for rotational magnetization) Reference plane

Claims (4)

A rotor, a stator that rotatably supports the rotor, and a magnetic encoder that detects a rotation angle of the rotor,
The magnetic encoder has, as a permanent magnet for detecting the rotation angle, an annular magnetic ring formed of a rubber magnet vulcanized and bonded to a component (excluding the magnetic encoder) that constitutes the electric motor. And an electric motor. The component has a fitting surface that is fitted in a radial direction with a bearing that rotatably supports the rotor,
The electric motor according to claim 1, wherein the magnetic ring is rotationally magnetized with reference to a central axis of the fitting surface. A method of manufacturing an electric motor comprising: a rotor, a stator that rotatably supports the rotor, and a magnetic encoder that detects a rotation angle of the rotor,
As a permanent magnet used in the magnetic encoder for detecting the rotation angle, it is fitted in a radial direction with a bearing that rotatably supports the rotor among the components (excluding the magnetic encoder) constituting the electric motor. A method for manufacturing an electric motor, characterized in that an annular magnetic ring formed of a rubber magnet is vulcanized and adhered to a component having a fitting surface before rotationally magnetizing. The method of manufacturing an electric motor according to claim 3, wherein after the vulcanization and adhesion, the magnetic ring is subjected to rotary magnetization necessary for a magnetic encoder with the central axis of the fitting surface as a reference.

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