Rotor production method

Abstract

Provided is a rotor production method capable of suppressing defects such as scratches caused in an annular member when attaching the annular member to an outer periphery of a rotor core. In the rotor production method, a plurality of core pieces are brought into a curved state in advance so that the outer diameter is smaller than the inner diameter of an annular member 5, the plurality of core pieces 9A in the curved state are arranged in the annular member 5, and the plurality of arranged core pieces 9A in the curved state are pressed through openings 5a on both sides of the annular member 5 to form a flat plate shape, thereby forming a rotor core 1 in which the outer periphery is engaged with the annular member 5.

Description

Rotor manufacturing method

[0001] The present invention relates to a method for manufacturing a rotor in which an annular member is attached to a rotor core.

[0002] As an example of a conventional rotor, as disclosed in Patent Document 1, there is a rotor core in which a plurality of plate-shaped core pieces are stacked, and an annular member is attached to the outer periphery of the rotor core.

[0003] The annular member can be attached to the rotor core by a loose fit or an interference fit. However, a loose fit can cause plastic deformation of the rotor due to the presence of a gap, and if the rotor does plastically deform, it can become unbalanced, causing vibration during rotation.

[0004] On the other hand, an interference fit does not have the same problems as a clearance fit, but the rotor core, which is made up of multiple stacked core pieces, is press-fitted into an annular member, which can cause defects such as scratches on the annular member due to sliding between the rotor core and the annular member during press-fitting.

[0005] Patent No. 6220328

[0006] The problem to be solved is that there is a risk of malfunction occurring in the annular member when the annular member is attached to the outer periphery of the rotor core.

[0007] The present invention provides a method for manufacturing a rotor, which comprises pre-curving a plurality of core pieces so that their outer diameters are smaller than the inner diameter of an annular member, arranging the plurality of core pieces in the curved state within the annular member, and pressing the arranged plurality of core pieces in the curved state through openings on both sides of the annular member to form a flat plate, thereby forming a rotor core whose outer periphery engages with the inner periphery of the annular member.

[0008] The present invention can prevent defects such as scratches on the annular member when the annular member is attached to the outer periphery of the rotor core.

[0009] FIG. 1 is a perspective view of a rotor according to a first embodiment of the present invention. FIG. 2 is a plan view of the rotor of FIG. 1. FIG. 3 is a cross-sectional view of the rotor of FIG. 1. FIG. 4 is a cross-sectional view showing a curved state of core pieces used in the rotor of FIG. 2. FIG. 5 is a cross-sectional view showing insertion of the curved core pieces of FIG. 4 into an annular member. FIG. 6 is a cross-sectional view showing pressing by a jig onto the curved core pieces arranged in the annular member of FIG. 5. FIG. 7 is a cross-sectional view showing the curved core pieces of FIG. 5 flattened into a plate shape within the annular member. FIG. 8 is a plan view of a rotor according to a second embodiment of the present invention. FIG. 9 is a cross-sectional view showing pressing by a jig onto the curved core pieces arranged in the annular member of the rotor of FIG. 8. FIG. 10 is a cross-sectional view showing pressing by a jig onto the curved core pieces arranged in the annular member of a rotor according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view showing pressing by a jig onto the curved core pieces arranged in the annular member of a rotor according to a fourth embodiment of the present invention. FIG. 12 is a cross-sectional view of a rotor according to a fifth embodiment of the present invention. Fig. 13 is a cross-sectional view of a state in which a curved core piece is inserted into an annular member. Fig. 14 is a cross-sectional view of a state in which a shaft and a magnet are arranged in the core piece of Fig. 13. Fig. 15 is an enlarged cross-sectional view of the core piece of Fig. 14 before the magnet is accommodated. Fig. 16 is an enlarged cross-sectional view of the core piece of Fig. 14 after the magnet is accommodated. Fig. 17 is a cross-sectional view of a state in which an end core piece is arranged on the other axial side of the core piece of Fig. 14.

[0010] The manufacturing method of the rotor 1 involves engaging the outer peripheries of multiple flat core pieces 9A in an interference fit with the inner periphery of the annular member 5. Before attachment, the multiple core pieces 9A are curved in advance so that their outer diameters are smaller than the inner diameter of the annular member 5. The multiple curved core pieces 9A are placed inside the annular member 5. The curved core pieces 9A are pressed through openings 5a on both sides of the annular member 5 to form flat plates, thereby forming the rotor core 3 whose outer peripheries are engaged with the inner periphery of the annular member 5.

[0011] In one embodiment, the plurality of core pieces 9A may be curved in advance by sandwiching them between jigs 15 and 17 from both sides in the stacking direction. In this case, the plurality of core pieces 9A in the curved state may be inserted into the annular member 5 together with the jigs 15 and 17, and then the jigs 15 and 17 may be retracted from the annular member 5 to be disposed.

[0012] In another embodiment, the plurality of core pieces 9A may be plastically deformed in advance to be curved. In this case, the plurality of curved core pieces 9A may be inserted into the annular member 5 in a stacked state, or may be inserted into the annular member 5 individually and stacked.

[0013] In this embodiment, the multiple core pieces 9A in a curved state arranged within the annular member 5 may include a first group of core pieces 9A and a second group of core pieces 9A having a curvature direction opposite to that of the first group of core pieces 9A.

[0014] In yet another embodiment, the curved core pieces 9A arranged in the annular member 5 may be curved in the same direction. In this case, when pressing the curved core pieces 9A arranged in the annular member 5, the convex portions of the core pieces 9A are pressed by a jig 23 having a convexly curved pressing surface 23a, and the concave portions of the core pieces 9A are pressed by a jig 25 having a concavely curved pressing surface 25a.

[0015] Each of the plurality of curved core pieces 9A may have an outer periphery made of a flat portion 9Ab and a curved portion 9Aa on the radially inner side of the outer periphery.

[0016] The plurality of flat core pieces 9 constituting the rotor core 1 may be indirectly joined to each other via the annular member 5. However, the plurality of flat core pieces 9 may also be directly joined to each other by caulking or adhesive.

[0017] Each core piece 9 may have a hole 9 b that forms a magnet insertion hole of the rotor core 1 .

[0018] In this case, the portions of the plurality of curved core pieces 9A including the bridge portions 13 between the hole portions 9b may be curved.

[0019] [Structure of the rotor] Fig. 1 is a perspective view of a rotor according to a first embodiment of the present invention. Fig. 2 is a plan view of the rotor of Fig. 1. Fig. 3 is a cross-sectional view of the rotor of Fig. 1.

[0020] 1 to 3 constitute a rotating electric machine together with a stator. The rotor 1 includes a rotor core 3 and an annular member 5. The rotor 1 is an IPM (Interior Permanent Magnet) rotor in which magnets (not shown) are housed in magnet housing holes 7 of the rotor core 3.

[0021] The rotor core 3 is configured by stacking a plurality of flat core pieces 9 in the axial direction. Note that the axial direction means the direction along the axial center of the rotor 1, and hereinafter also means the stacking direction of the core pieces 9.

[0022] The multiple core pieces 9 of the rotor core 3 are held in a stacked state by the annular member 5. Therefore, the multiple core pieces 9 are not directly joined to one another by crimping, adhesive, or the like, but are indirectly joined via the annular member 5. In this joining, the outer peripheries of the multiple core pieces 9 of the rotor core 3 are engaged in an interference fit with the inner periphery of the annular member 5. Note that the multiple core pieces 9 can also be integrated by directly joining them to one another by crimping, adhesive, or the like.

[0023] By maintaining the stacked state of the multiple core pieces 9, the space factor of the rotor core 3 is 90% or more, preferably 95% or more, and more preferably 99% or more. In this case, the space factor means the ratio of the volume of the multiple core pieces 9 themselves, excluding the gaps, to the volume of the rotor core 3 including the gaps between adjacent core pieces 9. The gaps between adjacent core pieces 9 are, for example, 1 μm or less.

[0024] Each core piece 9 is formed by punching out an electromagnetic steel sheet or a silicon steel sheet, for example. The thickness of the core piece 9 before being attached to the annular member 5 is 0.5 mm or less, for example, 0.2 mm to 0.35 mm.

[0025] The rotor core 3 has an overall cylindrical shape due to the stacking of these core pieces 9. An axial hole 11 is provided in the center of the rotor core 3, and a plurality of magnet accommodating holes 7 are provided around the axial hole 11. The axial hole 11 and each magnet accommodating hole 7 are configured such that hole portions 9a and 9b provided in each core piece 9 that constitutes the rotor core 3 are respectively connected in the axial direction.

[0026] The shaft hole 11 and the magnet accommodating holes 7 in this embodiment pass through the rotor core 3 in the axial direction and are open at both axial end faces 3 a of the rotor core 3. Note that the magnet accommodating holes 7 may be open only at one end face 3 a of the rotor core 3.

[0027] The multiple magnet accommodating holes 7 are arranged at intervals in the circumferential direction of the rotor core 3. The circumferential direction refers to the direction along the outer periphery of the rotor core 3. Each magnet accommodating hole 7 is rectangular in plan view and is inclined with respect to the circumferential direction and the radial direction so that both circumferential sides are offset in the radial direction. The radial direction refers to the direction along the diameter of the rotor core 3. Note that the shape, number, arrangement, etc. of the magnet accommodating holes 7 can be modified in various ways.

[0028] A magnet (not shown) is housed in each magnet housing hole 7. The magnet may be made of, for example, a sintered ferrite magnet piece, a neodymium magnet piece, or other permanent magnet (including a magnetized piece).

[0029] Around each magnet accommodating hole 7, there is a bridge portion 13 between adjacent magnet accommodating holes 7. If the width of the bridge portion 13 is increased, the leakage magnetic flux of the magnet increases, reducing the efficiency of the rotating electric machine, so it is preferable to make the bridge portion 13 as narrow as possible.

[0030] The bridge portion 13 improves the strength of the rotor 1, thereby enabling a reduction in the thickness of the annular member 5. This reduces the magnetic resistance between the rotor 1 and the stator, which together constitute a rotating electrical machine, thereby improving the output torque.

[0031] The annular member 5 is attached to the outer periphery of the rotor core 3 and functions as a reinforcing member. In this embodiment, the annular member 5 is a cylindrical body that is open on both axial sides. The material of the annular member 5 can be appropriately set, and may be, for example, metal or resin such as fiber-reinforced plastic.

[0032] The annular member 5 has an axial dimension larger than that of the rotor core 3 and protrudes from both axial sides of the rotor core 3. The axial dimensions of the annular member 5 and the rotor core 3 may be the same. The radial thickness of the annular member 5 is, for example, 0.2 mm to 2 mm.

[0033] [Method of manufacturing rotor] Fig. 4 is a cross-sectional view showing a curved state of the core piece used in the rotor of Fig. 2. Fig. 5 is a cross-sectional view showing insertion of the curved core piece of Fig. 4 into an annular member. Fig. 6 is a cross-sectional view showing pressing by a jig against the curved core piece arranged in the annular member of Fig. 5. Fig. 7 is a cross-sectional view showing the curved core piece of Fig. 5 made into a flat plate shape within the annular member.

[0034] The manufacturing method of the rotor 1 is as follows: as shown in Figures 4 to 7, the outer peripheries of multiple flat core pieces 9 are engaged with the inner periphery of the annular member 5 in a tight fit state, and the multiple core pieces 9 are attached to the annular member 5 as a stacked rotor core 3.

[0035] In this manufacturing method, as shown in Fig. 4, first, the plurality of core pieces 9A are curved in advance so that the outer diameter is smaller than the inner diameter of the annular member 5. In this embodiment, the initial shape of the core pieces 9A is flat, but it does not have to be flat. In this embodiment, the plurality of core pieces 9A are sandwiched from both sides in the axial direction by jigs 15 and 17, and are curved by elastic deformation. The curved state of the plurality of core pieces 9A may be maintained by plastic deformation.

[0036] In this embodiment, the flat core piece 9 and the curved core piece 9A are the same core piece, but are distinguished by using different reference numerals.

[0037] The curved core pieces 9A are curved in the same direction, with one axial side (the lower side in FIG. 4) being convex and the other axial side (the upper side in FIG. 4) being concave. Note that the bent shape of the core pieces 9A is not limited to this and may be, for example, a wave shape.

[0038] The jig 15 has a convexly curved holding surface 15a. In this embodiment, the holding surface 15a has a convex spherical shape with a constant curvature. The jig 17 has a concavely curved holding surface 17a. In this embodiment, the holding surface 17a has a concave spherical shape corresponding to the curvature of the holding surface 15a of the jig 15. These jigs 15 and 17 sandwich and hold a plurality of curved core pieces 9A in the axial direction.

[0039] The jigs 15 and 17 of this embodiment only need to be able to curve the core piece 9A into a spherical shape or other curved shape, and the curvatures of the convex and concave holding surfaces 15a and 17a do not need to be constant. Furthermore, the holding surfaces 15a and 17a only need to be shaped to correspond to the cross-sectional shape of the curved core piece 9A.

[0040] The core pieces 9A shown in FIG. 4 can be easily and reliably held in a curved state by the hole portions 9b that form the magnet accommodating holes 7 and the plate thickness of 0.5 mm or less.

[0041] The flat core pieces 9 before being held by the jigs 15 and 17 are stacked according to the number of pieces that make up the rotor core 3, and the stacked flat core pieces 9 are pressed by the jigs 15 and 17 to form pre-curved core pieces 9A. For ease of explanation, in Figures 4 and 5, the number of the multiple core pieces 9A is shown as being less than the number of flat core pieces 9 that make up the rotor core 3 in Figures 6 and 7, etc.

[0042] Due to this curved state, the outer diameters of the plurality of core pieces 9A are smaller than the inner diameter of the annular member 5 (relative to the flat core pieces 9) before attachment.

[0043] 5, the plurality of core pieces 9A in a curved state are arranged in the annular member 5. That is, the plurality of core pieces 9A in a curved state are inserted into the annular member 5 together with the jigs 15 and 17 from the opening 5a on one side (upper side) in the axial direction. However, the plurality of core pieces 9A in a curved state may also be inserted into the annular member 5 from the opening 5a on the other side (lower side) in the axial direction.

[0044] The outer diameter of these curved core pieces 9A is reduced by the amount of curvature, and therefore they can be smoothly inserted into the annular member 5 together with the jigs 15 and 17. In other words, the curved core pieces 9A can be inserted into the annular member 5 in a loose fit. The outer diameters of the jigs 15 and 17 are smaller than the inner diameter of the annular member 5. Therefore, when the core pieces 9A are inserted, defects such as scratches on the inner circumference of the annular member 5 caused by the outer circumference of the core pieces 9A can be suppressed.

[0045] Thereafter, the jigs 15 and 17 are retracted from the annular member 5, leaving the plurality of core pieces 9A arranged within the annular member 5. The arranged curved core pieces 9A elastically return to their original shape, and their outer peripheries engage with the inner periphery of the annular member 5. In this state, the core pieces 9A are temporarily fixed in a curved state within the annular member 5 by their elasticity. The curved core pieces 9A arranged within the annular member 5 are pressed from the openings 5a on both sides of the annular member 5 as shown in FIG. 6 to form the plurality of flat core pieces 9.

[0046] 6, jigs 19 and 21 having flat pressing surfaces 19a and 21a, respectively, are used to press the core pieces 9A in the curved state. These jigs 19 and 21 are inserted into the annular member 5 through openings 5a on both sides of the annular member 5. The curved core pieces 9A are then pressed from both sides by the jigs 19 and 21 to form the core pieces 9 in the form of flat plates, as shown in FIG.

[0047] The outer peripheries of the plurality of flat core pieces 9 are tightly fitted into the inner periphery of the annular member 5 to form the rotor core 3. As a result, the rotor 1 is manufactured in which the annular member 5 is attached to the outer peripheries of the plurality of stacked flat core pieces 9.

[0048] In the manufactured rotor 1, after pressing with the jigs 19 and 21, the difference between the outer diameter of the flat core pieces 9 that make up the rotor core 3 and the inner diameter of the annular member 5 forms an interference, and the annular member 5 is attached by an interference fit to the outer periphery of the rotor core 3. This generates a large frictional force between the flat core pieces 9 and the annular member 5, maintaining the laminated state of the rotor core 3 and maintaining the flat state of the core pieces 9.

[0049] The stacked state here is a state in which the space factor of the rotor core 3 is adjusted to 90% or more, preferably 95% or more, and more preferably 99% or more by pressing with the jigs 19 and 21. At this time, the gap between adjacent core pieces 9 is adjusted to 1 μm or less.

[0050] In this way, by pressing with the jigs 19 and 21, the space factor of the rotor core 3 and the gap between the core pieces 9 can be adjusted, and the adjusted state of the space factor and gap of the rotor core 3 can be maintained by the annular member 5.

[0051] Additionally, compressive stress is applied to the rotor core 3 by the interference fit. This compressive stress counters the tensile stress at the bridge portions 13 that is generated by the centrifugal force acting on the magnets when the rotor 1 rotates. Therefore, the compressive stress due to the interference fit, the strength of the annular member 5 itself, and the strength of the bridge portions 13 improve the centrifugal strength of the rotor 1, enabling the maximum rotation speed of the rotor 1 to be increased.

[0052] Furthermore, if the centrifugal strength is sufficient, the bridge portion 13 of the rotor core 3 can be made even narrower, thereby reducing leakage magnetic flux and improving output.

[0053] As described above, in the manufacturing method of the rotor 1 of this embodiment, the multiple core pieces 9 are curved in advance so that the outer diameter is smaller than the inner diameter of the annular member 5, and the multiple core pieces 9A in this curved state are placed inside the annular member 5. Then, the multiple core pieces 9A in the curved state are pressed into a flat plate shape inside the annular member 5 through the openings 5a on both sides of the annular member 5, thereby manufacturing the rotor 1, which is the rotor core 3 reinforced by the annular member 5.

[0054] Therefore, in this embodiment, it is not necessary to press-fit the plurality of flat core pieces 9 through the openings 5a of the annular member 5, and the plurality of flat core pieces 9 can be smoothly arranged inside the annular member 5. As a result, defects such as scratches on the inner periphery of the annular member 5 can be suppressed.

[0055] In the manufactured rotor 1, the outer peripheries of the plurality of flat core pieces 9 are tightly fitted and engaged with the inner periphery of the annular member 5. This makes it possible to suppress rattle of the rotor core 3 relative to the annular member 5.

[0056] Therefore, it is possible to suppress imbalance of the rotor 1 caused by rattle of the rotor core 3, and to reduce vibration during rotation of the rotor 1. Furthermore, in this embodiment, shrink fitting or cold fitting is not required, which makes it possible to reduce assembly costs.

[0057] The core pieces 9 have holes 9 b that form the magnet insertion holes 7 of the rotor core 3 , and therefore can be easily curved using the jigs 15 and 17 .

[0058] Furthermore, since the thickness of the core piece 9 is 0.5 mm or less before being attached to the annular member 5, the core piece 9 can be bent more easily.

[0059] Furthermore, in the manufacturing method of this embodiment, the space factor of the rotor core 3 or the gap between adjacent flat core pieces 9 in the rotor core 3 can be adjusted by pressing the curved core pieces 9A.

[0060] This improves the centrifugal strength at the same time as attaching the rotor core 3 to the annular member 5, thereby improving the performance of the rotor 1. The space factor of the rotor core 3 is 90% or more, and the gaps between the multiple core pieces 9 are 1 μm or less, so the performance of the rotor 1 can be improved more reliably.

[0061] Fig. 8 is a plan view of a rotor according to a second embodiment of the present invention. Fig. 9 is a cross-sectional view showing a jig pressing a curved core piece disposed in an annular member of the rotor shown in Fig. 8. Note that the basic configuration of the second embodiment is the same as that of the first embodiment, and components corresponding to those of the first embodiment are designated by the same reference numerals, and redundant explanations will be omitted.

[0062] 8 and 9, the plurality of core pieces 9A in a curved state are curved by plastic deformation. In this embodiment, the portion of each core piece 9A in a curved state where plastic deformation is performed is a portion C on the circumference including the bridge portion 13.

[0063] Due to the plastic deformation of portion C, compressive plastic strain remains on the inner side of the bend at the bridge portion 13 in each curved core piece 9A, and tensile plastic strain remains on the outer side of the bend. Then, as shown in Fig. 9, a plurality of core pieces 9A in a curved state that have been plastically deformed are inserted and arranged in a stacked state into the annular member 5. However, a plurality of core pieces 9A in a curved state may also be inserted one by one into the annular member 5 and stacked within the annular member 5. Furthermore, when arranging the core pieces 9A as shown in Fig. 9, it is sufficient that the core pieces 9A are plastically deformed, and it is not necessary to plastically deform the core pieces 9A at portion C as shown in Fig. 8.

[0064] In this embodiment, the multiple core pieces 9A include a first group of core pieces 9A and a second group of core pieces 9A. The first group of core pieces 9A and the second group of core pieces 9A are arranged in the annular member 5 with their curvature directions opposite to each other. Note that, in the second embodiment as well, all of the curved core pieces 9A may be arranged in the annular member 5 with their curvatures facing the same direction. Alternatively, only one of the core pieces 9A in the first group or the second group may be plastically deformed, and the other may be elastically deformed.

[0065] The first group of core pieces 9A and the second group of core pieces 9A are preferably the same in number, but one may be greater than the other. The first group of core pieces 9A and the second group of core pieces 9A are each stacked as a single unit, but each may be divided into multiple units and the units may be arranged alternately. Furthermore, the first group of core pieces 9A and the second group of core pieces 9A may be arranged alternately, depending on the length of the annular member 5, etc.

[0066] In this state, the annular member 5 is pressed by jigs 19 and 21 through the openings 5a on both sides in the same manner as in FIG. 6, to form the rotor 1 having the rotor core 3 inside the annular member 5 as shown in FIG.

[0067] In the rotor 1, the first and second groups of core pieces 9 abut against each other at their interfaces with a force that causes them to return to their curved state due to springback. As a result, the first and second groups of core pieces 9 mutually suppress springback. Therefore, in the rotor core 3, each core piece 9 is reliably held in the annular member 5 in a flat plate shape.

[0068] Furthermore, the bridge portions 13 undergo work hardening when the curved core pieces 9A undergo plastic deformation. This work hardening of the bridge portions 13 counters the tensile stress in the bridge portions 13 that is generated by the centrifugal force acting on the magnets when the rotor 1 rotates. Therefore, the compressive stress due to the interference fit, the strength of the annular member 5 itself, and the work hardening of the bridge portions 13 improve the centrifugal strength of the rotor 1, allowing the maximum rotation speed of the rotor 1 to be increased.

[0069] In addition, in this embodiment, the same effects as those in the first embodiment can be obtained.

[0070] 10 is a cross-sectional view showing a jig pressing a curved core piece disposed in an annular member of a rotor according to Example 3 of the present invention. Note that Example 3 has a basic configuration in common with Example 1, and components corresponding to those in Example 1 are designated by the same reference numerals, and redundant explanations will be omitted.

[0071] 10, similarly to Example 1, the curvature directions of the multiple core pieces 9A in a curved state arranged in the annular member 5 are set to the same direction. Then, the convex portions of the multiple core pieces 9A are pressed by a jig 23 having a convexly curved pressing surface 23a, and the concave portions of the core pieces 9A are pressed by a jig 25 having a concavely curved pressing surface 25a.

[0072] The pressing surface 23a of the jig 23 is curved convexly, such as spherically, with a certain curvature. The pressing surface 25a of the jig 25 is curved concavely, such as spherically, according to the curvature of the pressing surface 23a of the jig 23.

[0073] In this embodiment, the curved core piece 9A is placed in the annular member 5 with the convex portion facing upward. The pressing surface 23a of the jig 23 faces the convex portion of the core piece 9A in the axial direction, and the pressing surface 25a of the jig 25 faces the concave portion in the axial direction.

[0074] In this state, the jigs 23 and 25 are inserted into the annular member 5 through the openings 5a on both sides. In response, the jigs 23 and 25 come into contact with the core pieces 9A located at the axial ends of the convex and concave portions of the opposing core pieces 9A, and then press the curved core pieces 9A from both sides to form a flat plate.

[0075] As a result, the outer peripheries of the plurality of flat core pieces 9 are engaged with the inner periphery of the annular member 5 by tight fit, as shown in FIG.

[0076] In this embodiment, the direction of the concaves and convexes of the jigs 23 and 25 is opposite to the direction of the concaves and convexes of the curved core pieces 9A. Therefore, the curved core pieces 9A can be straightened to be flat in consideration of springback after the jigs 23 and 25 are retracted, and the flat core pieces 9 can be easily and reliably obtained as shown in FIG.

[0077] In addition, the same effects as those of the first embodiment can be obtained.

[0078] 11 is a cross-sectional view showing a jig pressing a curved core piece disposed in an annular member of a rotor according to Example 4 of the present invention. Note that Example 4 has a basic configuration in common with Example 1, and components corresponding to those in Example 1 are designated by the same reference numerals, and redundant explanations will be omitted.

[0079] In this embodiment, as shown in FIG. 11, each core piece 9A in a curved state after plastic deformation has a flat portion 9Ab on the outer periphery and a curved portion 9Aa on the radially inner side relative to this outer periphery.

[0080] The curved portion 9Aa is formed in a spherical shape similar to the curved core piece 9A of Example 1. The flat portion 9Ab is flat and maintains a state along the radial direction of the flat-plate-shaped core piece 9. The flat portion 9Ab is formed in a circumferential shape around the curved portion 9Aa.

[0081] The multiple core pieces 9A in this curved state can be easily and reliably inserted into the annular member 5 by a clearance fit, as shown in Figure 11. In this state, the multiple core pieces 9A are pressed from both sides in the axial direction to flatten the curved portions 9Aa. As a result, the multiple flat core pieces 9 are attached to the annular member 5 by an interference fit, and the rotor 1 having the rotor core 3 inside the annular member 5 is manufactured.

[0082] At this time, in this embodiment, the engagement state with the annular member 5 does not fluctuate in the axial direction due to the clearance fit and the tight fit, so it is possible to more reliably prevent defects such as scratches on the annular member 5. Furthermore, in this embodiment, the surface pressure during pressing can be reduced, and the core pieces 9 can be flattened while preventing damage, etc.

[0083] 11, jigs 27 and 29 having flat pressing surfaces 27a and 29a, respectively, are used to press the core piece 9A. However, convex and concave jigs may also be used, as in Example 3 of FIG. 10.

[0084] In addition, in this embodiment, the same effects as those in the first embodiment can be obtained.

[0085] 12 is a cross-sectional view of a rotor according to a fifth embodiment of the present invention. Since the fifth embodiment has a basic configuration in common with the first embodiment, the components corresponding to those in the first embodiment are designated by the same reference numerals and redundant description will be omitted.

[0086] [Structure of the Rotor] The rotor 1 of this embodiment has magnets 31 and a shaft 33 attached to a rotor core 3. As in the first embodiment, the rotor core 3 is configured by stacking multiple core pieces 9, and is provided with a shaft hole 11 and multiple magnet accommodating holes 7.

[0087] In the rotor core 3 of this embodiment, end core pieces 35 are laminated on both ends in the axial direction. One end core piece 35 is laminated on each end, but multiple end core pieces 35 may be laminated.

[0088] Each end core piece 35 is made of a plate-like non-magnetic material that has an axial hole 11 but does not have a magnet accommodating hole 7. The non-magnetic material can be a metal such as stainless steel or aluminum, or a resin. The end core piece 35 closes both axial ends of the magnet accommodating hole 7.

[0089] In this embodiment, the magnets 31 in each magnet accommodating hole 7 are configured in a rod shape and are fixed in the magnet accommodating hole 7 by elastic pieces 7a (see Figures 14 and 15) described below. The magnets 31 can be fixed in the magnet accommodating holes 7 by any appropriate method.

[0090] The shaft 33 is fastened to both ends of the rotor core 3 via end plates 37. The end plates 37 are plate-shaped bodies made of metal or the like, and abut against the end core pieces 35 of the rotor core 3 in the axial direction. A portion of the end plates 37 in the axial direction is located on the inner periphery of the annular member 5, and the remaining portion protrudes axially outward from the annular member 5. The end plates 37 are provided with insertion holes 37a that communicate with the axial hole 11 of the rotor core 3 in the axial direction.

[0091] The shaft 33 has an axially intermediate portion 33a formed with a relatively large diameter. This intermediate portion 33a is inserted through the rotor core 3 and the end plate 37 via the insertion hole 37a and the axial hole 11. On one axial side (the lower side in FIG. 12 ) of the shaft 33, there is a larger-diameter abutting portion 33c between the intermediate portion 33a and the end portion 33b. The abutting portion 33c abuts against the outer surface of the end plate 37 in the axial direction.

[0092] On the other axial side of the shaft 33 (upper side in FIG. 12 ), the shaft 33 protrudes outward from the end plate 37 from the middle portion 33 a to the end portion 33 b, and a nut 39 is threadedly engaged with the protruding middle portion 33 a. Therefore, the shaft 33 is fastened to the rotor core 3 via the end plate 37 by the nut 39 and the abutment portion 33 c.

[0093] [Method of manufacturing rotor] Fig. 13 is a cross-sectional view of a state in which a curved core piece is inserted into an annular member. Fig. 14 is a cross-sectional view of a state in which a shaft and a magnet are arranged in the core piece of Fig. 13. Fig. 15 is an enlarged cross-sectional view of the core piece of Fig. 14 before the magnet is accommodated, and Fig. 16 is an enlarged cross-sectional view of the same core piece after the magnet has been accommodated. Fig. 17 is a cross-sectional view of a state in which an end core piece is arranged on the other axial side of the core piece of Fig. 14.

[0094] In the manufacturing method of the rotor 1 of this embodiment, as in the first embodiment, a plurality of curved core pieces 9A are arranged in the annular member 5, as shown in Fig. 13. At this time, end core pieces 35A are stacked on one axial side of the plurality of core pieces 9A, and the end core pieces 35A are arranged in a curved state together with the plurality of core pieces 9A in the annular member 5. In this embodiment, the flat end core pieces 35 and the curved end core pieces 35A have the same configuration except for the presence or absence of curvature, but are distinguished by using different reference numerals.

[0095] 14, an end plate 37 is placed adjacent to the end core piece 35A on one axial side (the lower side in FIG. 14) of the core pieces 9A. Then, the shaft 33 is inserted from one axial side through the end plate 37, the end core piece 35A, and the core pieces 9A, and the abutment portion 33c of the shaft 33 is brought into abutment with the end plate 37.

[0096] Magnets 31 are inserted into the magnet accommodating holes 7 of the core pieces 9A. As shown in Figures 15 and 16, the magnets 31 are inserted in the axial direction into the magnet accommodating holes 7 that open on the other axial side (the upper side in Figures 14 to 16).

[0097] Before the magnet 31 is inserted into the magnet accommodating hole 7, an elastic piece 7a protrudes in a cantilever shape. The magnet 31 is inserted into the magnet accommodating hole 7 while deforming this elastic piece 7a, and the elasticity of the elastic piece 7a fixes the magnet 31 in the magnet accommodating hole 7. In this way, the magnet 31 can be fixed to the magnet accommodating holes 7 of the multiple core pieces 9A in a curved state by the elastic piece 7a. Note that the elastic piece 7a in this embodiment is supported on both sides when the magnet 31 is inserted.

[0098] After the magnets 31 are accommodated in the magnet accommodating holes 7, the end core pieces 35A are arranged on the other axial side of the curved core pieces 9A, as shown in Figure 17. The end core pieces 35A may be pre-curved.

[0099] Furthermore, the arrangement of such end core pieces 35A can be performed after the magnet 31 is accommodated in the magnet accommodating hole 7, and the accommodation of the magnet 31 can be performed either before or after the arrangement of the end plate 37 and the shaft 33.

[0100] After the end plate 37 and shaft 33 are positioned on one axial side, the magnet 31 is housed, and the end core piece 35A is positioned on the other axial side, as shown in Figure 12, the end plate 37 is positioned adjacent to the end core piece 35A on the other axial side of the multiple core pieces 9A, and a nut 39 is screwed onto the middle part 33a of the shaft 33 that passes through this end plate 37.

[0101] As a result, the shaft 33 is fastened to the rotor core 3 via the end plate 37. At this time, the nuts 39 are tightened until the core pieces 9A and the end core pieces 35A become flat.

[0102] Therefore, in this embodiment, by utilizing the attachment of the shaft 33, the plurality of flat core pieces 9 and end core pieces 35 can be attached to the inner periphery of the annular member 5 as the rotor core 3.

[0103] In this embodiment, the plurality of core pieces 9A and the end core pieces 35A are pressed into a flat plate shape with the curved end core pieces 35A having no magnet accommodating holes 7 arranged at both ends of the plurality of curved core pieces 9A. This makes it possible to prevent buckling of the bridge portions 13 of the plurality of core pieces 9 that have become flat.

[0104] Furthermore, since the annular member 5 has members (in this embodiment, the core piece 9A, the end core piece 35A, and the end plate 37) that fit into the inner circumference throughout the entire axial direction, the diameter is uniform in the axial direction, making it easier to suppress damage such as cracks.

[0105] Furthermore, in this embodiment, the fastening force of the nut 39 can apply a targeted compressive stress to the bridge portion 13, thereby enabling the rotor 1 to rotate at a high speed.

[0106] In addition, the fifth embodiment can also achieve the same effects as the first embodiment.

[0107] REFERENCE SIGNS LIST 1 rotor 3 rotor core 5 annular member 5a opening 9 flat core piece 9a, 9b hole 9A curved core piece 9Aa curved portion 9Ab flat portion 13 bridge portion 15, 17, 19, 21, 23, 25, 27, 29 jig

Claims

1. A method for manufacturing a rotor, comprising: pre-curving a plurality of core pieces so that their outer diameters are smaller than the inner diameter of an annular member; arranging the plurality of core pieces in the curved state within the annular member; and pressing the curved core pieces through openings on both sides of the annular member to form a flat plate, thereby forming a rotor core whose outer periphery engages with the inner periphery of the annular member.

2. A method for manufacturing a rotor according to claim 1, wherein the plurality of core pieces are first bent by being sandwiched between jigs on both sides in the stacking direction, and the plurality of core pieces in the bent state are inserted into the annular member together with the jigs, and then the jigs are retracted from the annular member and placed in place.

3. A method for manufacturing a rotor according to claim 1, wherein the plurality of core pieces are plastically deformed in advance to be in the curved state, and the plurality of core pieces in the curved state are inserted and arranged in a stacked state into the annular member, or are individually inserted and arranged in a stacked state into the annular member.

4. A method for manufacturing a rotor according to claim 3, wherein the plurality of curved core pieces arranged within the annular member include a first group of core pieces and a second group of core pieces that are curved in the opposite direction to the first group of core pieces.

5. A method for manufacturing a rotor as claimed in claim 3, wherein the curved core pieces arranged within the annular member are curved in the same direction, and when pressing the curved core pieces arranged within the annular member, the convex portions of the core pieces are pressed with a jig having a convexly curved pressing surface, and the concave portions of the core pieces are pressed with a jig having a concavely curved pressing surface.

6. A method for manufacturing a rotor according to claim 3, wherein each of the plurality of curved core pieces has an outer periphery made of a flat portion and a curved portion on the inside in the radial direction relative to the outer periphery.

7. A method for manufacturing a rotor according to any one of claims 1 to 6, wherein the plurality of flat core pieces are indirectly connected to each other via the annular member.

8. A method for manufacturing a rotor according to any one of claims 1 to 6, wherein each of the plurality of core pieces has a hole that forms a magnet insertion hole of the rotor core.

9. A method of manufacturing a rotor according to claim 8, wherein each of the plurality of core pieces in the curved state is curved at a portion including a bridge portion between the hole portions.

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