Magnetic encoder and manufacturing method thereof

Abstract

A magnetic encoder having a plurality of rows of tracks and capable of detecting an absolute angle can be manufactured more accurately and simply. Comprises: an annular core iron (2) having a curved plate section (2B) that is curved and continuous from the edge of a track-forming surface section (2Aa); and two or more adjacent rows of tracks (4) arranged in parallel on the magnetic member (3) provided on the track-forming surface portion (2Aa) such that N poles and S poles are alternately magnetized. The track (4) comprises: a main track (5) for angle calculation with the maximum number of magnetized poles; and sub-tracks (6) for calculating their phase differences. The main track (5) is located on the side of the sub track (6) that is close to the curved plate section (2B).

Description

[0001] The present invention is a divisional application of the invention patent application No. 201880009660.2 filed on January 30, 2018, with the invention name “Magnetic encoder and its manufacturing method”.

[0002] Related Applications

[0003] This application claims the benefit of priority from Japanese Patent Application No. 2017-017322, filed on February 2, 2017, the entirety of which is incorporated herein by reference as if it constitutes a part of this application. Technical Field

[0004] The present invention relates to a magnetic encoder for detecting a rotational speed or a rotational position and a method for manufacturing the same, and more particularly to a magnetic encoder having multiple rows of magnetic tracks suitable for absolute angle detection and a method for manufacturing the same. Background Art

[0005] Patent Document 1 proposes a magnetic encoder device in which, when magnetizing a plurality of rows of magnetic encoder tracks, a magnetic shielding member is used to shield the flow of magnetic flux of the magnetic encoder track rows other than the magnetic object.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: JP Patent No. 5973278 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In the magnetic encoder of Patent Document 1, by setting a difference of one pole pair between corresponding magnetic tracks, it can be used for detecting absolute angles. However, the magnetization accuracy of the track (main track) on one side that constitutes the reference for angle detection is required to be high. For example, when using a magnetic encoder with two rows of tracks magnetized by 32 pole pairs and 31 pole pairs to detect absolute angles, the angle of each pole pair on the 32 pole pair side is 11.25 degrees (360 / 32). In order to determine what phase position is in, a magnetization accuracy of less than 0.35 degrees (11.25 / 32) is required. For example, considering safety, a magnetization accuracy of less than ±0.1 degrees is required. If the number of poles is increased in the form of 64 pole pairs and 63 pole pairs, a higher accuracy is required, for example, a magnetization accuracy of less than ±0.04 degrees is required. Therefore, it is difficult to manufacture a magnetic encoder that meets the required accuracy.

[0011] Therefore, an object of the present invention is to provide a magnetic encoder and a method for manufacturing the magnetic encoder, which can produce a magnetic encoder having a plurality of rows of magnetic tracks and capable of detecting an absolute angle with higher accuracy and in a simple manner.

[0012] Technical solutions to solve problems

[0013] The magnetic encoder of the present invention comprises: an annular core iron having a curved plate portion that is curved and continuous from the edge of a track forming surface; a magnetic track, which is arranged in parallel in two or more rows in which N poles and S poles are alternately magnetized on a magnetic component provided on the track forming surface of the core iron, wherein the two or more rows of magnetic tracks include: a main magnetic track having the largest number of magnetized poles and used for angle calculation; and a secondary magnetic track for calculating their phase difference, the main magnetic track being located on one side of the secondary magnetic track close to the curved plate portion. The magnetic component may be an integrated type used for both the main magnetic track and the secondary magnetic track, or may be a type provided separately for each magnetic track.

[0014] The portion of the track-forming surface of the core tube close to the curved plate portion is a portion with high rigidity and small rotational vibration due to the bending of the core iron. Since the main magnetic track, which is a magnetic track requiring high precision and a large number of magnetic poles, is set in this portion with small rotational vibration, it is expected that the accuracy of the detection angle will be improved and stabilized. In addition, in terms of manufacturing, since only the configuration of the main magnetic track and the auxiliary magnetic track needs to be designed, it is possible to simply manufacture while seeking to improve the accuracy.

[0015] In the magnetic encoder of the present invention, the core iron may include: a cylindrical portion whose outer circumferential surface constitutes the track forming surface portion; the curved plate portion curved from the cylindrical portion to the inner diameter side; and a cylindrical mounting portion that is continuous concentrically from the inner diameter side edge of the curved plate portion to the side opposite to the cylindrical portion. That is, it may also be a so-called radial type. Even in the case of a radial type like this, it is possible to manufacture simply while seeking to improve accuracy. In addition, the curved plate portion is a portion that connects the track forming surface portion and the mounting portion, and is not a portion provided to improve rigidity, so the structure of the core iron is not complicated in order to improve rigidity.

[0016] In the magnetic encoder of the present invention, the core iron may include: a flat plate portion and the curved plate portion, the flat plate portion is in the shape of a flat ring, one surface of which constitutes the track forming surface portion, and the curved plate portion is bent from the inner diameter side edge of the flat plate portion and continues to the side opposite to the track forming surface portion, forming a cylindrical mounting portion. That is, it may also be a so-called axial type. Even in the case of an axial type like this, it can be manufactured simply while seeking to improve accuracy. In addition, since the curved plate portion is a portion of the mounting portion for connecting the shaft, etc., and is not a portion provided to improve rigidity, the structure of the core iron is not complicated in order to improve rigidity.

[0017] In the magnetic encoder of the present invention, the accuracy of the spacing of the magnetic poles of the main track is higher than that of the auxiliary track. The accuracy mentioned here is the difference between the actual spacing and the theoretical spacing. As an example, if a track is magnetized by 32 pole pairs, the angle of each pole pair is theoretically 11.25 degrees. In addition, in fact, when the angle of a certain pole pair is 11.3 degrees, the theoretical spacing is 11.25 degrees and the actual spacing is 11.3 degrees. For magnetic encoders, unmagnetized magnetic encoders are generally manufactured and then magnetized. In this case, each track is magnetized in turn, but when the first magnetized track is magnetized by the later magnetized track, it is estimated that there is an influence of reduced accuracy due to the leakage of its magnetic flux. Therefore, it is difficult to magnetize all adjacent and parallel magnetic encoders with high accuracy.

[0018] Therefore, in the magnetic encoder of the present invention, the track with low accuracy in estimating the magnetic pole spacing is the secondary track. Since the secondary track is a track used for calculating the phase difference relative to the main track, for example, the accuracy of the magnetization spacing is less affected by the above-mentioned magnetization sequence, and the accuracy of the spacing of the main track with a large number of magnetic poles and used for angle calculation is higher than that of the secondary track. Thus, a magnetic encoder that can detect the absolute angle with high accuracy within the limited manufacturing accuracy range can be formed. Preferably, the number of magnetic poles of the above-mentioned main track is one more than the number of magnetic poles of the above-mentioned secondary track. In addition, the magnetic encoder is not limited to a magnetic encoder in which the magnetization sequence of each track is performed in sequence, and is generally applicable to a magnetic encoder in which the accuracy varies between tracks.

[0019] The manufacturing method of the magnetic encoder of the present invention is a method for manufacturing a magnetic encoder of any of the above-mentioned schemes of the present invention, wherein, after manufacturing an unmagnetized magnetic encoder in which the above-mentioned magnetic component is set on the outer periphery of the above-mentioned core iron, each row of tracks is magnetized in turn, and during this magnetization process, while the tracks that are not currently magnetized or the parts that constitute the tracks are shielded by magnetic shielding components, the N pole and the S pole are magnetized alternately one pole at a time.

[0020] By magnetizing one pole at a time alternately and shielding the portion of the magnetic track on the side that is not currently magnetized by the magnetic shielding member, the portion is magnetized, thereby minimizing the influence of magnetic flux leakage and performing magnetization with higher accuracy. As a result, a magnetic encoder can be manufactured with higher accuracy, in which a main magnetic track is formed in a portion of the core iron with high rigidity of the present invention, and an absolute angle can be detected with high accuracy. In addition, the above-mentioned magnetic encoder can be manufactured by a simple improved manufacturing method of such a scheme of the present invention.

[0021] In the manufacturing method of the magnetic encoder of the present invention, the main track may be magnetized after the auxiliary track is magnetized. As described above, during the magnetization of the track, the accuracy is degraded due to magnetic flux leakage, but in terms of the magnetization order, the main track having a large number of magnetized pole pairs that affect the angle accuracy is placed last, thereby suppressing the accuracy degradation of the main track and enabling the detection of the absolute angle with high accuracy.

[0022] Any combination of at least two structures disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims in the claims is also included in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and the accompanying drawings are for simple illustration and description and should not be used to limit the scope of the present invention. The scope of the present invention is determined by the claims. In the accompanying drawings, the same component number in multiple drawings represents the same or corresponding part.

[0024] Figure 1 is a cross-sectional view of a magnetic encoder according to a first embodiment of the present invention;

[0025] Figure 2 (a) is a development diagram showing the parallel arrangement of magnetic poles of the magnetic encoder. Figure 2 (b) Figure 2 (c) are two signals obtained from each track of the magnetic encoder, Figure 2 (d) is a waveform diagram of the phase difference between the two signals;

[0026] Figure 3 A cross-sectional view showing an example of a manufacturing apparatus for manufacturing the magnetic encoder;

[0027] Figure 4 For the edge viewed from above Figure 3 A cross-sectional view of the IV-IV line;

[0028] Figure 5 To show the magnetization process of the magnetic encoder using the manufacturing device (( Figure 5 (a) comes first, Figure 5 (b) a cross-sectional view of the rear portion;

[0029] Figure 6 An explanatory diagram showing the parallel arrangement of magnetic poles in each row of the magnetic encoder;

[0030] Figure 7 A cross-sectional view of a magnetic encoder according to a second embodiment of the present invention;

[0031] Figure 8 A front view showing the parallel arrangement of magnetic poles of the magnetic encoder;

[0032] Fig. 9 This is a diagram for explaining the process of magnetization for magnetic shielding of the magnetic encoder. DETAILED DESCRIPTION

[0033] according to Figure 1 to Figure 6 A first embodiment of the present invention will be described. This embodiment is an example of application to a radial type magnetic encoder. Figure 1 A cross-sectional view showing a magnetic encoder.

[0034] Figure 2 (a) is a diagram showing a magnetization pattern of a track developed in the circumferential direction. Figure 2 (b) Figure 2 (c) represents the detection signal of each magnetized pole pair relative to these magnetic patterns, Figure 2 (d) represents their phase difference.

[0035] In the magnetic encoder 1, a rubber material mixed with magnetic powder is placed in a metal mold together with a core iron 2 composed of a metal ring and hardened and bonded to the outer peripheral surface of the core iron 2, or a component mixed with plastic and magnetic powder on its outer peripheral surface is formed integrally with the core iron 2 to form a circular ring-shaped magnetic component 3, and then, a plurality of rows of magnetic tracks 4 with different numbers of magnetized pole pairs are formed on the outside of the unmagnetized magnetic component 3 (in this embodiment, 2 rows).

[0036] The core iron 2 is a type formed by pressing an iron-based rolled steel plate, and includes: a cylindrical portion 2A whose outer peripheral surface constitutes a magnetic track forming surface portion 2Aa, a bent plate portion 2B, and a cylindrical mounting portion 2C, the bent plate portion 2B being bent from the cylindrical portion 2A to the inner diameter side, and the mounting portion 2C being concentrically continuous from the inner diameter side edge of the bent plate portion 2B to the side opposite to the cylindrical portion 2A. A rotating shaft not shown in the figure is fixed to the mounting portion 2C by means of press fitting or the like.

[0037] The magnetic track 4 on the side close to the curved plate portion 2B is a main magnetic track 5, and is magnetized by, for example, 32 pole pairs on the magnetic member 3, and the magnetic track 4 on the side away from the curved plate portion 2B is a secondary magnetic track 6, and is magnetized by, for example, 31 pole pairs on the magnetic member 3. In the magnetic encoder 1, the absolute angle of the rotating shaft is detected by utilizing the fact that a difference of one pole pair is generated in one revolution.

[0038] For example, in the magnetic encoder 1, the magnetic sensors for absolute angle detection are arranged facing the magnetic sensors 31 and 32 facing the main track 5 and the sub-track 6, and the magnetic encoder 1 rotates around the center O of its ring. In this case, the output from the magnetic sensor 31 on the main track 5 side is Figure 2 The detection signal shown in (b) is output from the magnetic sensor 32 on the secondary track 6 side. Figure 2 The corresponding detection signal is a phase signal of 0 to 360 degrees in one pole pair of N pole and S pole. If the difference of these detection signals is obtained, it looks like Figure 2 As shown in (d) of FIG. 1 , a phase difference signal that changes linearly is obtained along with the rotation of the magnetic encoder 1. In this case, in one rotation from 0 to 360 degrees of the magnetic encoder 1, the phase difference signal shows a waveform of one cycle.

[0039] In the detection of the absolute angle of the magnetic encoder 1, the angle can be detected with high accuracy based on the main track 5, and the position of the main track can be grasped based on the phase difference between the main track 5 and the sub-track 6 to detect the absolute angle. In addition, the magnetic encoder 1, the magnetic sensors 31 and 32, and the computing mechanism (not shown in the figure) such as the electronic circuit that calculates the absolute angle based on the detection signals of the magnetic sensors 31 and 32 constitute an absolute angle detection device.

[0040] As the magnetization method, for example, a method of magnetizing each track 4 (5, 6) in a predetermined order while rotating the magnetic encoder 1 by using an index magnetizing device that alternately magnetizes the N pole and the S pole one pole at a time, and a synchronous magnetization method of magnetizing two tracks 4 (5, 6) at the same time can be used. However, in the synchronous magnetization method, the magnetization yoke structure is complicated, and when magnetizing, there is magnetic interference between the two tracks 4 (5, 6), making it difficult to magnetize with good accuracy. Therefore, in the case of having multiple rows of tracks 4, it is particularly preferable to use an index magnetizing device.

[0041] For example, when the absolute angle is detected by using two rows of tracks 4 (5, 6) magnetized by 32 pole pairs and 31 pole pairs (in this case, the number of poles of the main track 5 is one more than the number of poles of the secondary track 6), the angle of each pole pair on the 32 pole pair side (main track 5) is 11.25 degrees (360 / 32). In order to determine the phase position, a magnetization accuracy of 0.35 degrees (11.25 / 32) or less, which is one-thirtieth of that, is required. For example, a magnetization accuracy of ±0.1 degrees or less is required in consideration of safety. If the number of poles increases in the form of 64 pole pairs and 63 pole pairs, the accuracy is required to be more stringent, for example, an accuracy of ±0.04 degrees or less is required.

[0042] In order to improve the accuracy of the main track 5 that affects the angular accuracy, it is best to suppress the rotational vibration of the magnetic encoder 1 and maintain high rigidity. Therefore, in this embodiment, the core iron 2 in the track forming surface portion 2Aa of the core iron 2 is continuous with the bent curved plate portion 2B, and the track 4 on the side close to the curved plate portion 2B with high rigidity constitutes the main track 5, thereby expecting to improve the angular accuracy.

[0043] In addition, when the main track 5 having a large number of magnetized pole pairs used for angle calculation is initially magnetized, when the secondary track 6 is subsequently magnetized, it is estimated that the accuracy of the main track 5 may be affected by magnetic flux leakage, such as the pole spacing error (spacing accuracy) and cumulative spacing error (cumulative spacing accuracy). In this case, the angle accuracy is reduced.

[0044] Here, both the pitch error and the cumulative pitch error refer to indicators that indicate the accuracy of the magnetized magnetic track. As an example, if a magnetic track is magnetized by 32 magnetic poles, theoretically, the angle of each pole pair is 11.25 degrees. Here, in fact, when the angle of a certain pole pair is 11.3 degrees, the pitch error of the pole pair is +0.05 degrees. In addition, the cumulative pitch error refers to the error expressed by accumulating the pitch errors relative to all pole pairs and taking the maximum value (amplitude).

[0045] Thus, the main track 5 having a large number of magnetized pole pairs that affect the angle accuracy is magnetized last, thereby suppressing the accuracy degradation of the main track 5 and detecting the absolute angle with high accuracy. That is, since the above-mentioned accuracy degradation is suppressed by forming the above-mentioned magnetization sequence, the pitch accuracy and cumulative pitch accuracy of the magnetic poles of the main track 5 are higher than those of the sub-track 6. In this case, when the main track 5 is magnetized, it is also estimated that the accuracy of the sub-track 6 that has been magnetized first will be affected. However, since the sub-track 6 is used to grasp the phase relationship with the main track 5, the accuracy may not be considered much.

[0046] Figure 3 Represents a magnetizing device. Figure 4 Indicates along Figure 3The cross-sectional view of the line IV-IV in FIG. The magnetizing device 7 of the magnetizing encoder includes: a main shaft 9, which rotates a fixture 8 holding the unmagnetized magnetic encoder 1 constituting the magnetization object in such a manner that the center O of the ring coincides with the rotation axis RO; a motor 10 for rotating the main shaft; a magnetizing yoke 11; a positioning mechanism 12, which positions the magnetizing yoke 11 in three-axis directions; a magnetizing power supply 13; and a control mechanism 14. The motor 10 includes a high-precision encoding device 24 as a detection device for detecting the rotation angle. In addition, a magnetic sensor 15 for measuring the magnetization accuracy is provided at the stage where the magnetization of the magnetic encoder 1 held by the fixture 8 is completed, and is fixed to a positioning mechanism 16 that can be positioned in three-axis directions. The positioning mechanism 12 of the motor 10 and the magnetizing yoke 11 constitutes a positioning device 29, which positions the front end 19 of the magnetizing yoke 11 relative to the unmagnetized magnetic encoder 1.

[0047] The control mechanism 14 is composed of a computer or the like, and sequentially magnetizes each of the tracks 4 on the unmagnetized magnetic encoder 1, and magnetizes the main track 5 after the auxiliary track 6 in the order of magnetization, and controls the positioning mechanism 12, the motor 10, and the magnetizing power supply 13 of the positioning device 29 by numerical control or the like in such a manner that the magnetic poles of NS are alternately arranged in parallel.

[0048] The magnetized yoke 11 includes a pair of facing ends (also referred to as "front ends") 19, 20 that face each other magnetically via a magnetic gap, and magnetizes the magnetic track 4 of the magnetic encoder 1 that is not magnetized and is set at a position and posture determined relative to these facing ends 19, 20. Specifically, the magnetized yoke 11 is composed of a U-shaped magnetized yoke body 17 and an excitation coil 18, and a first front end 19 and a second front end 20 that are respectively set at one end and the other end of the magnetized yoke body 17. The excitation coil 18 is wound around the outer periphery of the magnetized yoke body 17. In the magnetized yoke 11, the magnetic flux a (refer to Figure 4 ) penetrates the magnetic encoder 1, and the first front end portion 19 of the magnetizing yoke 11 has a sharp tip and faces the surface of the magnetic encoder 1 (i.e., the magnetic track 4) during magnetization. The second front end portion faces the fixture 8 with a gap, forming a magnetic circuit from the first front end portion 19, through the magnetic encoder 1, the fixture 8 to the second front end portion 20. In addition, the second front end portion 20 may be omitted.

[0049] The magnetic shielding member 21 is provided with an angular hole 22 having a tapered cross section in the longitudinal direction of the axis RO, and the first front end portion 19 is provided at a distance from the corresponding position above and below the hole 22. The magnetic shielding member 21 and the first front end portion 19 facing the magnetic encoder 1 are positioned so as to maintain a certain gap, for example, 0.1 mm, relative to the unmagnetized magnetic track 4.

[0050] The magnetic shielding member 21 is fixed to the end of the support seat 23 fixed at a position close to the second front end of the magnetizing yoke body 17. The magnetic flux inside the magnetic flux generated from the first front end 19 that affects the other magnetic track that is not magnetized is induced to the magnetic shielding member 21, and is moved to the second front end 20 side opposite to the first front end 19 facing the magnetic encoder 1. The magnetic shielding member 21 and the support seat 23 are made of a magnetic body such as low-carbon steel. In the magnetization of the magnetic encoder 1 having a plurality of rows of magnetic tracks, the magnetic shielding member 21 can be made opposite to the magnetic track 4 in a manner that shields the flow of magnetic flux to the magnetic track other than the magnetization target.

[0051] Figure 5 The figure shows the arrangement position of the first front end portion 19 of the magnetizing yoke 11 when two rows of magnetic tracks 4 (5, 6) are magnetized in the magnetic member 3 of the unmagnetized magnetic encoder 1. Figure 6 An example of a magnetization pattern of the magnetic encoder 1 magnetized in two rows is shown.

[0052] Figure 5 (a) shows the configuration of the first front end portion 19 of the magnetizing yoke 11 and the magnetic shielding member 21 when the upper half of the magnetic member 3 of the magnetic encoder 1 is magnetized as the track 4 constituting the secondary track 6. At this time, the surface of the magnetic member 3 forming the other track 4 (main track 5) is covered by the magnetic shielding member 21, and the magnetic flux flowing from the first front end portion 19 is prevented from flowing to the other track 4 (main track 5).

[0053] Figure 5 (b) shows the configuration of the first front end portion 19 of the magnetizing yoke 11 and the magnetic shielding member 21 when the lower half of the magnetic member 3 of the magnetic encoder 1 is magnetized as the track 4 constituting the main track 5. At this time, the surface of the magnetic member 3 forming the track 4 constituting the initially magnetized sub-track 6 is covered by the magnetic shielding member 21, and the magnetic flux flowing from the first front end portion 19 is prevented from flowing to the other track 4 (sub-track 6).

[0054] If in Figure 5 In the step (a) shown in FIG. 1 , a sub-track 6 (track 4) is formed, and finally, in Figure 5 In the step (b) of FIG. 1 , by magnetizing in the order of forming the main track 5 (track 4 ), the magnetic encoder 1 is obtained in which the accuracy degradation of the main track 5 is suppressed, and the absolute angle can be detected with high accuracy.

[0055] According to this embodiment, as described above, since the track 4 close to the bent plate portion 2B where the core iron 2 is bent and has high rigidity and small rotational vibration is the main track 5 requiring high precision and having a large number of magnetized pole pairs, it helps to improve and stabilize the angle accuracy.

[0056] Furthermore, when magnetizing a plurality of rows of magnetic encoders 1, by magnetizing the main track 5 as the track 4 for calculating the angle last, the accuracy degradation of the main track 5 can be suppressed, and the absolute angle can be detected with high accuracy.

[0057] Figure 7 to Figure 9 The second embodiment of the present invention is shown. This embodiment is an example of an axial type magnetic encoder 1. In this embodiment, except for the matters particularly described, other aspects are the same as those of the combination Figure 1 to Figure 6 In this example, the core iron 2 includes a flat plate portion 2D and a cylindrical curved plate portion 2E, the flat plate portion 2D is in the shape of a flat ring, one surface of which constitutes a track forming surface portion 2Da, and the curved plate portion 2E is bent from the inner diameter side edge of the flat plate portion 2D and is continuous with the side opposite to the track forming surface portion 2Da, forming a cylindrical mounting portion.

[0058] A magnetic member 3 is provided on the track forming surface portion 2Da, and tracks 4 are provided in a plurality of rows on the magnetic member 3. In this case, the track 4 on the innermost peripheral side close to the curved plate portion 2E is the main track 5, and the other tracks 4 are the sub-tracks 6. The main track 5 and the sub-track 6 are magnetized in sequence in the unmagnetized magnetic encoder 1, but the sub-track 6 is magnetized first and the main track 5 is magnetized last.

[0059] The device for magnetizing as described above is basically the same as Figure 3 The magnetizing device is the same, but since the direction of the track 4 in the magnetic encoder 1 changes in the axial and radial directions, corresponding to this difference, Fig. 9 In this way, the direction in which the front end portion 19 of the magnetizing yoke 11 and the magnetic shield member 21 face is the center O of the ring of the magnetic encoder 1 ( Figure 7 ), that is, the rotation axis RO( Fig. 9 (a) Fig. 9 (b)) direction. In addition, the direction of relative movement of the magnetizing yoke 11, the magnetic shielding member 21 and the magnetic encoder 1 for switching the magnetized track 4 is as shown in the figure. Fig. 9 (a) Fig. 9 (b) shows the radial direction of the magnetic encoder 1 as shown in each positioning state.

[0060] In the case of this scheme as well, since the magnetic track 4 on the side of the curved plate portion 2E where the core iron 2 is curved and has high rigidity and small rotational vibration is the main magnetic track 5 which requires high accuracy and has a large number of magnetized pole pairs, it helps to improve and stabilize the angle accuracy. In addition, when magnetizing a multi-row magnetic encoder 1, the main magnetic track 5, which is the magnetic track 4 for calculating the angle, is magnetized last, thereby suppressing the accuracy degradation of the main magnetic track 5 and enabling the detection of the absolute angle with high accuracy.

[0061] As described above, the preferred embodiments have been described with reference to the drawings, but various additions, changes, or deletions may be made without departing from the spirit of the present invention. Such modifications are also included in the scope of the present invention.

[0062] Description of the label:

[0063] Reference numeral 1 indicates a magnetic encoder;

[0064] Reference numeral 2 indicates core iron;

[0065] Reference numeral 2A denotes a cylindrical portion;

[0066] Reference numeral 2Aa denotes a track forming surface;

[0067] Reference numeral 2B denotes a bent plate portion;

[0068] Reference numeral 2C denotes a mounting portion;

[0069] Reference numeral 2D denotes a flat plate portion;

[0070] Reference numeral 2Da denotes a track forming surface;

[0071] Reference numeral 2E denotes a bent plate portion;

[0072] Reference numeral 3 denotes a magnetic component;

[0073] Reference numeral 4 denotes a track;

[0074] Reference numeral 5 indicates a main track;

[0075] Reference numeral 6 denotes a secondary track;

[0076] Reference numeral 7 denotes a magnetizing device of a magnetic encoder;

[0077] Reference numeral 8 denotes a clamp;

[0078] Reference numeral 10 denotes a motor;

[0079] Reference numeral 11 denotes a magnetizing yoke;

[0080] Reference numeral 12 denotes a positioning mechanism;

[0081] Reference numeral 13 denotes a magnetizing power supply;

[0082] Reference numeral 14 denotes a control mechanism;

[0083] Reference numeral 19 denotes a front end portion;

[0084] Reference numeral 21 denotes a shielding member;

[0085] Reference numeral 29 denotes a positioning device.

Claims

1. A magnetic encoder, comprising: An annular core iron having a curved plate portion that is curved and continuous from an edge of a magnetic track forming surface portion; A magnetic track, which is arranged in adjacent and parallel rows of more than two rows in which N poles and S poles are alternately magnetized on a magnetic component arranged on the track-forming surface of the core iron, wherein the more than two rows of magnetic tracks include: a main track with the largest number of magnetized poles for angle calculation; and a secondary track for calculating their phase difference, wherein the main track is located on one side of the secondary track close to the curved plate portion.

2. The magnetic encoder according to claim 1, wherein: The core iron includes: a cylindrical portion whose outer circumferential surface constitutes the magnetic track forming surface; the bent plate portion bent from the cylindrical portion to the inner diameter side; and a cylindrical mounting portion that continues concentrically from the inner diameter side edge of the bent plate portion to the side opposite to the cylindrical portion.

3. The magnetic encoder according to claim 1, wherein: The core iron includes: a flat plate portion and the bent plate portion, the flat plate portion is in the shape of a flat ring, one surface of which constitutes the track forming surface portion, and the bent plate portion is bent from the inner diameter side edge of the flat plate portion and continues to the side opposite to the track forming surface portion to form a cylindrical mounting portion.

4. The magnetic encoder according to any one of claims 1 to 3, wherein: The pitch of the magnetic poles of the main track has a higher precision than that of the auxiliary track.

5. The method for manufacturing a magnetic encoder according to any one of claims 1 to 4, wherein: After manufacturing an unmagnetized magnetic encoder in which the above-mentioned magnetic component is set on the outer periphery of the above-mentioned core iron, each row of tracks is magnetized in turn. During this magnetization process, while the tracks that are not currently magnetized or the parts that constitute the tracks are shielded by the magnetic shielding components, the N poles and S poles are magnetized alternately one at a time.

6. The method for manufacturing a magnetic encoder according to claim 5, wherein: After the auxiliary track is magnetized, the main track is magnetized.

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