Rotor manufacturing method

Abstract

To reduce or cancel unbalance of a rotor without affecting the performance of a motor through simplified steps.SOLUTION: A manufacturing method of a rotor including insertion holes arrayed around an axial center in a circumferential direction, magnets and resins disposed in the insertion holes includes: a first step of disposing the magnets and the resins in the insertion holes of a first group among the insertion holes and rotating the rotor at a first rotation speed to identify an unbalance position of the rotor; a second step of disposing the magnets and the resins in the insertion holes of a second group, which is relatively far from the unbalance position, among the insertion holes in which the magnets are not disposed in the first step, and rotating the rotor at a second rotation speed; and a third step of disposing the magnets and the resins in the insertion holes of a third group, which is relatively close to the unbalance position, among the insertion holes, in which the magnets are not disposed in the first step, and rotating the rotor at a third rotation speed lower than the second rotation speed.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing a rotor and to a rotor. [Background technology]

[0002] A rotor used in a motor equipped with a stator and rotor is formed by inserting permanent magnets into a plurality of magnet insertion holes formed in the circumferential direction of a laminated iron core body and sealing them with resin. Patent Document 1 describes a technique for counteracting the unbalanced weight caused by deviations in the circumferential lamination thickness of the laminated iron core body during the manufacturing process of such a rotor. The technique described in Patent Document 1 involves a step of measuring the deviation in the circumferential lamination thickness of the laminated iron core body to estimate the unbalanced weight, and a step of inserting permanent magnets into each magnet insertion hole or filling with resin to counteract the unbalanced weight. Specifically, this involves selectively inserting permanent magnets of different weights into the magnet insertion holes, adjusting the position of the permanent magnets within each magnet insertion hole, or adjusting the amount of resin filled into each magnet insertion hole. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-19381 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in technologies like the one described in Patent Document 1 above, it is necessary to determine the weight, placement, or amount of resin filling of the permanent magnet based on the measured unbalanced weight, which makes the process complicated. Furthermore, changing the weight of the permanent magnet may affect the performance of the motor.

[0005] This disclosure has been made in view of the above-mentioned problems, and the object of this disclosure is to provide a method for manufacturing a rotor and a rotor that can reduce or eliminate rotor unbalance in a simplified process without affecting the performance of the motor. [Means for solving the problem]

[0006] To solve the above problems, in view of the present disclosure, a method for manufacturing a rotor used in a motor comprising a stator and a rotor is provided, wherein the rotor includes insertion holes arranged in the circumferential direction with respect to an axis, and magnets and resin disposed within the insertion holes, and the method includes: a first step of arranging the magnets and resin in a first group of insertion holes and rotating the rotor at a first rotational speed to identify an unbalanced position of the rotor; a second step of arranging the magnets and resin in a second group of insertion holes that are relatively far from the unbalanced position among the insertion holes in which the magnets were not disposed in the first step, and rotating the rotor at a second rotational speed; and a third step of arranging the magnets and resin in a third group of insertion holes that are relatively close to the unbalanced position among the insertion holes in which the magnets were not disposed in the first step, and rotating the rotor at a third rotational speed less than the second rotational speed.

[0007] Furthermore, in order to solve the above problems, according to another aspect of this disclosure, a rotor is provided for use in a motor comprising a stator and a rotor, wherein the rotor includes insertion holes arranged circumferentially around an axis, and magnets and resin disposed within the insertion holes, the magnets and resin being disposed by a first step of arranging the magnets and resin in a first group of insertion holes and rotating the rotor at a first rotational speed to identify an unbalanced position of the rotor; a second step of arranging the magnets and resin in a second group of insertion holes that are relatively far from the unbalanced position among the insertion holes in which the magnets were not disposed in the first step, and rotating the rotor at a second rotational speed; and a third step of arranging the magnets and resin in a third group of insertion holes that are relatively close to the unbalanced position among the insertion holes in which the magnets were not disposed in the first step, and rotating the rotor at a third rotational speed less than the second rotational speed. [Effects of the Invention]

[0008] As described above, according to this disclosure, rotor imbalance can be reduced or eliminated in a simplified process and without affecting the performance of the motor. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a motor according to one embodiment of the present disclosure. [Figure 2] This is a view along the line II-II in Figure 1. [Figure 3] This figure shows the first step of a method for manufacturing a rotor according to one embodiment of the present disclosure. [Figure 4] This figure shows the second step of a method for manufacturing a rotor according to one embodiment of the present disclosure. [Figure 5] This figure shows the third step of a method for manufacturing a rotor according to one embodiment of the present disclosure. [Figure 6] This diagram illustrates the forces acting on the magnet and resin placed in the insertion hole. [Figure 7]It is a flowchart showing the steps of the method for manufacturing a rotor described with reference to FIGS. 3 to 5.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0011] FIG. 1 is a cross-sectional view showing a motor according to an embodiment of the present disclosure, and FIG. 2 is a view taken along the line II-II of FIG. 1. As shown in the drawings, the motor 1 has a stator 2 and a rotor 3. The rotor 3 is a part attached to the shaft 4 and rotates, and the stator 2 is a part fixed around the rotor 3. Since known configurations can be used for the stator 2, the shaft 4, and parts of the rotor 3 other than those described below, detailed description thereof is omitted.

[0012] The rotor 3 includes a main body 31 formed of a laminated iron core, a plurality of insertion holes 32 formed in the main body 31, and magnets 33 and resin 34 disposed in the insertion holes 32. The insertion holes 32 are arranged in the circumferential direction around the axis 3A of the rotor 3 and penetrate the main body 31 in the axial direction. The magnet 33 is, for example, a bar-shaped permanent magnet having a length corresponding to the insertion hole 32. The cross-sectional shape of the insertion hole 32 is not limited, but is, for example, rectangular and larger than the cross-sectional shape of the magnet 33 as shown in the drawings. The cross-sectional shape of the magnet 33 is also not limited, but is, for example, rectangular. The gap between the wall surface of the insertion hole 32 and the magnet 33 is filled with the resin 34. The resin 34 is, for example, a thermosetting resin such as an epoxy resin or a thermoplastic resin. Hereinafter, the step of disposing the magnets 33 and the resin 34 in the plurality of insertion holes 32 will be further described.

[0013] FIG. 3 is a diagram showing a first step of a method for manufacturing a rotor according to an embodiment of the present disclosure. The first step is executed after the rotor 3 is attached to the shaft 4 and becomes rotatable. In the first step, magnets 33 and resin 34 are arranged in the first group of insertion holes 32A among the insertion holes 32, and the rotor 3 is rotated at the first rotational speed n1 to identify the imbalance position P U . The first group of insertion holes 32A is a part of the plurality of insertion holes 32, and is set at equal intervals in the circumferential direction in which the insertion holes 32 are arranged. That is, one or more insertion holes 32 are skipped in the circumferential direction from the insertion holes 32 belonging to the first group of insertion holes 32A, and the next insertion hole 32 belonging to the first group of insertion holes 32A exists. The imbalance position P U is the position of the mass spindle when the rotor 3 has an imbalance, that is, when the mass spindle during rotation does not coincide with the axis 3A. For example, the imbalance position P U is identified by measuring the rotational phase of the rotor 3 and the vibration waveform of the peripheral surface of the rotor 3.

[0014] In addition, in the present embodiment, in the first step, it is only necessary to identify in which direction the imbalance position P U is with respect to the axis 3A of the rotor 3, and the distance d from the axis 3A to the imbalance position P U does not necessarily have to be measured.

[0015] FIG. 4 is a diagram showing a second step of a method for manufacturing a rotor according to an embodiment of the present disclosure. The second step is executed after the first step. In the second step, among the insertion holes 32 where the magnets 33 were not arranged in the first step, magnets 33 and resin 34 are arranged in the second group of insertion holes 32B that are relatively far from the imbalance position P U identified in the first step, and the rotor 3 is rotated at the second rotational speed n2. The second rotational speed n2 in the second step may be, for example, not more than the first rotational speed n1 in the first step as in the example described later, but is not particularly limited.

[0016] Figure 5 shows a third step of a rotor manufacturing method according to one embodiment of the present disclosure. The third step is performed after the second step. In the third step, among the insertion holes 32 in which the magnet 33 was not placed in the first step, the unbalanced position P identified in the first step is... U The magnet 33 and resin 34 are placed in the third group of insertion holes 32C which are relatively close to the rotor, and the rotor 3 is rotated at a third rotational speed n3. The third rotational speed n3 in the third step is less than the second rotational speed n2 in the second step.

[0017] Figure 6 is a diagram illustrating the forces acting on the magnet and resin placed in the insertion hole. When the rotor 3 is rotated at rotational speed n with the magnet 33 placed in the insertion hole 32, a centrifugal force F=mrω acts on the magnet 33 due to its angular velocity ω=2πn. 2 The following force acts upon the magnet 33. Here, m is the mass of the magnet 33, and r is the radius of rotation of the magnet 33, that is, the distance from the axis 3A of the rotor 3 to the center of gravity of the magnet 33 in the illustrated cross-section. The magnet 33 is pressed radially outward from the axis 3A by the centrifugal force F. At this time, the centrifugal force F acts to push the resin 34 filled in the insertion hole 32 out from between the radially outer wall surface 321 of the insertion hole 32 and the magnet 33. Against this centrifugal force F, the viscous force τ that attracts the resins 34 together in the direction along the wall surface 321 resists, so that a layer of resin 34 with a thickness t remains between the wall surface 321 and the magnet 33.

[0018] Here, the viscous force τ does not change if the viscosity of the resin 34 is constant, whereas the centrifugal force F changes according to the rotation speed n, as is clear from the above equation. Therefore, by appropriately setting the rotation speed n, the magnitude of the centrifugal force F can be adjusted, and the thickness t of the resin 34 between the wall surface 321 of the insertion hole 32 and the magnet 33 can be controlled. Specifically, if the rotation speed n is reduced, the centrifugal force F will decrease and the thickness t will increase. The position of the magnet 33 placed in the insertion hole 32 will move further away from the wall surface 321 and closer to the axis 3A as the thickness t increases, so if the rotation speed n is reduced further, the magnet 33 will be placed closer to the axis 3A. The same is true in the reverse case; if the rotation speed n is increased further, the magnet 33 will be placed further away from the axis 3A.

[0019] Therefore, as shown in FIGS. 4 and 5, in the second step where the second rotational speed n2 is relatively high, in the insertion holes 32B of the second group, the resin 34 outside the magnet 33 has a relatively small thickness t2, and the magnet 33 is disposed at a position farther from the axis 3A. On the other hand, in the third step where the third rotational speed n3 is relatively low, in the insertion holes 32C of the third group, the resin 34 outside the magnet 33 has a relatively large thickness t3, and the magnet 33 is disposed at a position closer to the axis 3A. As a result, the mass spindle during rotation of the rotor 3 moves in a direction approaching the axis 3A from the unbalance position P U Thus, in the present embodiment, the unbalance of the rotor 3 that occurred when the magnet 33 and the resin 34 were disposed in the insertion holes 32A of the first group in the first step can be reduced or eliminated in the second and third steps

[0020] FIG. 7 is a flowchart showing the steps of the method for manufacturing a rotor described with reference to FIGS. 3 to 5. First, as a first step (step S10), the magnet 33 and the resin 34 are disposed in the insertion holes 32A of the first group, and the rotor 3 is rotated at the first rotational speed n1. If an unbalance occurs in the rotor 3, the unbalance position P U is specified. In the next second step (step S20), the magnet 33 and the resin 34 are disposed in the insertion holes 32B of the second group determined based on the unbalance position P U and the rotor 3 is rotated at the second rotational speed n2. Further, in the third step (step S30), the magnet 33 and the resin 34 are disposed in the insertion holes 32C of the third group, and the rotor can be rotated at a third rotational speed n3 less than the second rotational speed n2 in the second step. Note that, for example, other steps may be performed between the first step and the second step, and between the second step and the third step, and other steps may be performed before the first step and after the third step. Further, as will be described later, steps after the fourth step in which the rotor 3 is rotated at a rotational speed less than that in the previous step may be performed in the same manner as the third step

[0021] In one embodiment of the present disclosure described above, after a second step of rotating the rotor 3 at a second rotational speed n2, a third step is performed in which the rotor 3 is rotated at a third rotational speed n3 which is less than the second rotational speed n2. In the second step, the unbalanced position P U In the second group of insertion holes 32B, which are relatively farther away, the magnet 33 is positioned further away from the axis 3A, and in the third step, the unbalanced position P U In the third group of insertion holes 32C, which are relatively close to the axis 3A, the magnet 33 is positioned closer to the axis 3A. This causes the mass principal axis of the rotor 3 during rotation to be in an unbalanced position P U By moving it in a direction toward the axis 3A, the imbalance of the rotor 3 that occurred at the time of the first process can be reduced or eliminated.

[0022] In this embodiment, for example, the unbalanced position P as described later U Even if the second rotational speed n2 and the third rotational speed n3 are determined according to the distance d to the rotor, the process is simplified compared to determining the weight and placement of individual magnets, the amount of resin filling, etc., based on the unbalanced weight. The second rotational speed n2 and the third rotational speed n3 can also be set to fixed values, in which case the process is further simplified. In addition, in this embodiment, it is not necessary to change the weight of the magnet 33, so the process of reducing or eliminating rotor unbalance does not affect the performance of the motor.

[0023] The following describes a modified version of the embodiment described above.

[0024] In the second and third steps described above, the mass principal axis of the rotor 3 during rotation is in an unbalanced position P. U The amount of movement when moving towards the axis 3A changes according to the difference between the second rotational speed n2 in the second process and the third rotational speed n3 in the third process. Therefore, in the first process, the unbalanced position P U When identifying the unbalanced position P from the axis 3A, UThe distance d to the point is measured, and at least one of the second rotational speed n2 and the third rotational speed n3 may be determined so that the amount of movement of the mass principal axis in the second and third steps matches or approaches the distance d. More specifically, for example, the second rotational speed n2 may be a fixed value and the third rotational speed n3 may be determined according to the distance d, or the third rotational speed n3 may be a fixed value and the second rotational speed n2 may be determined according to the distance d, or both the second rotational speed n2 and the third rotational speed n3 may be varied according to the distance d so that an appropriate difference in rotational speeds is produced.

[0025] By setting the second rotational speed n2 and the third rotational speed n3 according to the distance d in this way, the unbalance of the rotor 3 can be minimized. However, even if the distance d is not measured and the second rotational speed n2 and the third rotational speed n3 are set to fixed values, a sufficient reduction or elimination of the unbalance can be obtained. For example, in cases where the tolerance for unbalance is small, such as in the drive motor of a vehicle where quietness is particularly important, the second rotational speed n2 and the third rotational speed n3 may be set according to the distance d. Also, in cases where the tolerance for unbalance is relatively large, such as in the motor of a household electrical appliance, the second rotational speed n2 and the third rotational speed n3 may be set to fixed values ​​without measuring the distance d.

[0026] Furthermore, at least one of the first rotational speeds n1 to the third rotational speed n3 in the first to third steps described above may be determined according to at least one of the mass m of the magnet 33 or the viscosity of the resin 34. As described above, the centrifugal force F = mrω acts on the magnet 33 in the insertion hole 32 when the rotor 3 is rotated. 2The rotational angular velocity ω = 2πn, as well as the mass m of the magnet 33, also affects the rotational angular velocity ω = 2πn. Furthermore, the viscous force τ of the resin 34 resisting the centrifugal force F changes depending on the viscosity of the resin 34. Therefore, by determining the first rotational speed n1 to the third rotational speed n3 according to at least one of the mass m of the magnet 33 or the viscosity of the resin 34, the effect of reducing or eliminating the unbalance can be optimized. Note that, for example, if the mass m of the magnet 33 and the viscosity of the resin 34 are approximately constant, or if the tolerance for unbalance is relatively large as described above, a sufficient effect of reducing or eliminating the unbalance can be obtained even if the first rotational speed n1 to the third rotational speed n3 are set to fixed values.

[0027] The relative magnitudes of the first rotation speed n1 and the second rotation speed n2 in the first and second steps described above are not particularly limited, but the second rotation speed n2 may be less than or equal to the first rotation speed n1. For example, if the second step is performed before the resin 34 filled into the first group of insertion holes 32A in the first step hardens, if the second rotation speed n2 is less than or equal to the first rotation speed n1, the centrifugal force F acting on the magnet 33 already placed in the first group of insertion holes 32A in the second step will not be greater than the centrifugal force F acting in the first step. Therefore, the thickness t of the resin 34 between the wall surface 321 and the magnet 33 will not decrease, and the position of the magnet 33 will not change. Such a configuration is effective, for example, in the case of thermosetting resins with a slow hardening speed. By being able to perform the next step without waiting for the resin 34 to harden, the process time can be shortened. The same applies between the second and third steps; the third step can be performed without waiting for the resin 34 filled in the second step to harden. Furthermore, the second step may be performed after the resin 34 filled into the insertion holes 32A of the first group in the first step has hardened, in which case, for example, the second rotation speed n2 may be greater than the first rotation speed n1.

[0028] In the above embodiment, steps 1 through 3 were performed, but in other embodiments, steps 4 and beyond may be performed. In this case, the rotational speed in step 4 is less than the third rotational speed n3 in step 3. The insertion hole 32 in which the magnet 33 is placed in step 4 is selected from the insertion holes 32 in which the magnet 33 was not placed in steps 1 through 3. For example, the insertion hole 32B of the second group in which the magnet 33 is placed in step 2 is at an unbalanced position P U The insertion hole 32C of the third group, where the magnet 33 is positioned in the third step, is furthest from the unbalanced position P. U The insertion hole of the fourth group, which is located in an intermediate position relative to the first group, may be the closest to the unbalanced position in the fourth step. The same applies when performing the fifth step and subsequent steps.

[0029] While preferred embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the present disclosure is not limited to such examples. It is clear to any person with ordinary skill in the art to which the present disclosure pertains that various modifications or alterations may be conceived within the scope of the technical idea set forth in the claims, and these will naturally also be understood to fall within the technical scope of the present disclosure. [Explanation of symbols]

[0030] 1: Motor 2: Status 3: Rotor 3A: Axial center 31: Main unit 32: Insertion hole 32A: Insertion holes for the first group 32B: Insertion holes for the second group 32C: Insertion holes for the third group 33: Magnet 321: Wall surface 4: Shaft

Claims

1. A method for manufacturing a rotor used in a motor comprising a stator and a rotor, The rotor includes insertion holes arranged circumferentially around its axis, and magnets and resin placed within the insertion holes. The first step involves placing the magnet and the resin in the first group of insertion holes, and rotating the rotor at a first rotational speed to identify the unbalanced position of the rotor. A second step is to place the magnet and the resin in a second group of insertion holes that are relatively far from the unbalanced position among the insertion holes in which the magnet is not placed in the first step, and to rotate the rotor at a second rotational speed, In the first step, the magnet and the resin are placed in a third group of insertion holes that are relatively close to the unbalanced position among the insertion holes where the magnet is not placed, and the rotor is rotated at a third rotation speed that is less than the second rotation speed. A method for manufacturing a rotor, including

2. The method for manufacturing a rotor according to claim 1, wherein the insertion holes of the first group are set at equal intervals in the circumferential direction.

3. The method for manufacturing a rotor according to claim 1, wherein the second rotational speed is less than or equal to the first rotational speed.

4. The first step further includes the step of measuring the distance from the axis to the unbalanced position, The method for manufacturing a rotor according to claim 1, wherein at least one of the second rotational speed or the third rotational speed is determined according to the distance.

5. The method for manufacturing a rotor according to claim 1, wherein at least one of the first rotational speed, the second rotational speed, and the third rotational speed is determined according to at least one of the mass of the magnet or the viscosity of the resin.

Images