Method for producing rotor

Abstract

The present invention provides a method for producing a rotor which can suppress the occurrence of a defect such as damage on an inner periphery of an annular member when the annular member is attached to an outer periphery of a rotor core. Provided is a method for producing a rotor 1 in which an annular member 5 is attached to the outer periphery of a rotor core 3 obtained by layering a plurality of plate-like core pieces 9, wherein the rotor core 3, the outer periphery of which is fitted to the annular member 5, is obtained by: disposing, in the annular member 5, the plurality of core pieces 9 in a curved state in which the plurality of core pieces 9 are curved to have a smaller outer diameter; and pressing the plurality of core pieces 9 in the curved state through openings 5a on both sides of the annular member 5 so that the plurality of core pieces 9 each have a flat plate shape.

Description

Rotor manufacturing method

[0001] The present invention relates to a method for manufacturing an IPM (Interior Permanent Magnet) rotor in which magnets are housed in magnet housing holes of 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 outer periphery of 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 gap. If the rotor plastically deforms, imbalance can occur, resulting in vibration during rotation.

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

[0005] For example, if the annular member is made of metal, damage to the inner circumference may cause stress concentration, and if the annular member is made of fiber-reinforced plastic, breakage of the fibers may result in a decrease in strength.

[0006] Patent No. 6220328

[0007] The problem to be solved is that when the annular member is attached to the outer periphery of the rotor core, there is a risk of defects such as scratches occurring on the inner periphery of the annular member.

[0008] The present invention provides a method for manufacturing a rotor in which an annular member is attached to the outer periphery of a rotor core made of stacked plate-shaped core pieces. In this manufacturing method, the stacked core pieces are placed in a curved state so that the outer diameter is reduced, and the curved core pieces are then pressed through openings on both sides of the annular member to flatten each core piece, thereby obtaining the rotor core whose outer periphery is engaged with the annular member.

[0009] The present invention can prevent defects such as scratches from occurring on the inner periphery of the annular member when the annular member is attached to the outer periphery of the rotor core.

[0010] [Correction based on Rule 91 26.09.2024] Figure 1 is a perspective view of a rotor according to a first embodiment of the present invention. Figure 2 is a plan view of the rotor of Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 2. Figures 4(A) to (C) are cross-sectional views showing a manufacturing method for a rotor according to a first embodiment of the present invention.

[0011] The goal of preventing defects such as scratches from occurring on the inner circumference of the annular member when attaching the annular member to the outer circumference of the rotor core is achieved by a rotor manufacturing method in which multiple stacked curved core pieces are made flat within the annular member.

[0012] The manufacturing method for the rotor 1 involves attaching an annular member 5 to the outer periphery of a rotor core 3 made up of a stack of multiple plate-shaped core pieces 9. In this manufacturing method, first, multiple core pieces 9, which are stacked in a curved state so that the outer diameter is reduced, are placed inside the annular member 5. Next, the multiple curved core pieces 9 are pressed through openings 5a on both sides of the annular member 5, making each core piece 9 into a flat plate. This results in a rotor core 3 whose outer periphery is engaged with the annular member 5.

[0013] When stacking the multiple core pieces 9 in a curved state, flat core pieces 9 having an outer diameter larger than the inner diameter of the annular member 5 may be bent while being pushed into the annular member 5 from the opening 5a on one side thereof. In this case, the multiple core pieces 9 in a curved state are stacked inside the annular member 5 by successively pushing the core pieces 9 in this way multiple times.

[0014] The multiple flat core pieces 9 that make up the rotor core 1 may be indirectly joined to each other via annular members 5, or may be directly joined to each other by crimping or adhesive.

[0015] The core pieces 9 may have holes 9 b that form the magnet insertion holes 7 of the rotor core 3 .

[0016] The thickness of the core piece 9 may be 0.5 mm or less.

[0017] The space factor of the rotor core 3 or the gaps between the flat core pieces 9 may be adjusted by pressing the curved core pieces 9. The space factor is preferably 90% or more, and the gaps are preferably 1 μm or less.

[0018] [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 taken along line III-III of Fig. 2.

[0019] 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 interior permanent magnet (IPM) rotor in which magnets (not shown) are housed in magnet housing holes 7 of the rotor core 3.

[0020] The rotor core 3 is configured by stacking a plurality of annular flat core pieces 9 in the axial direction. The axial direction means the direction along the axis of the rotor 1.

[0021] 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 each other by crimping, adhesive, or the like, but are indirectly joined via the annular member 5. By maintaining this stacked state, the space factor of the rotor core 3 is 90% or more, preferably 95% or more, and more preferably 99% or more. The space factor of the rotor core 3 refers to the ratio of the volume of the rotor core 3 excluding the gaps between the multiple core pieces 9 that make up the rotor core 3 to the volume of the rotor core 3. The gaps between the core pieces 9 are, for example, 1 μm or less. Note that the multiple core pieces 9 can also be integrated by directly joining them to each other by crimping, adhesive, or the like.

[0022] 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 is 0.5 mm or less, for example, 0.2 mm to 0.35 mm.

[0023] The rotor core 3 has a cylindrical shape as a whole. An axial hole 11 is provided in the center of the rotor core 3, and magnet accommodating holes 7 are provided around the axial hole 11 of the rotor core 3. The axial hole 11 and the magnet accommodating holes 7 are configured by holes 9a and 9b provided in each core piece 9 that constitutes the rotor core 3, which are connected in the axial direction.

[0024] The shaft hole 11 and the magnet accommodating holes 7 in this embodiment pass through the rotor core 3 in the axial direction and open at both axial end faces 3 a of the rotor core 3. Note that the magnet accommodating holes 7 may also open at only one end face 3 a of the rotor core 3.

[0025] The magnet accommodating holes 7 are provided at multiple locations around 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. The magnet accommodating holes 7 are arranged at an angle with respect to the circumferential and radial directions so that both circumferential sides are shifted inward and outward in the radial direction. The radial direction refers to the direction along the diameter of the rotor core 3. Note that various changes can be made to the shape, number, arrangement, etc. of the magnet accommodating holes 13.

[0026] 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).

[0027] Around the magnet accommodating holes 7, there are bridge portions 13 between adjacent magnet accommodating holes 7 and between the magnet accommodating holes 7 and the outer periphery of the rotor core 3. If the width of the bridge portions 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 them as narrow as possible.

[0028] 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.

[0029] The annular member 5 is attached to the outer periphery of the rotor core 3 and functions as a reinforcing member. As will be described later, the annular member 5 is attached to the outer periphery of the rotor core 3 by an interference fit. In this embodiment, the annular member 5 is a cylindrical body that is open on both axial sides. The annular member 5 is made of metal or resin such as fiber-reinforced plastic.

[0030] 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.

[0031] [Correction based on Rule 91 26.09.2024] [Method of Manufacturing Rotor] FIGS. 4A to 4C are cross-sectional views showing a method of manufacturing the rotor according to the first embodiment.

[0032] [Correction based on Rule 91, 26.09.2024] In the manufacturing method of the rotor 1, first, a plurality of core pieces 9 are placed in a curved state so that the outer diameter becomes smaller, inside the annular member 5. In this embodiment, as shown in Figure 4(A), flat core pieces 9 having an outer diameter larger than the inner diameter of the annular member 5 are pushed one by one through an opening 5a on one side of the annular member 5, while being curved, and then stacked sequentially inside the annular member 5. Note that in Figures 4(A) to 4(C), the holes 9a and 9b of the core pieces 9 are not shown.

[0033] When each core piece 9 is pressed into the annular member 5, the outer periphery of the core piece 9 is brought into contact with the opening edge 5b of the annular member 5, and the core piece 9 is pressed into the annular member 5 at a position inside the outer periphery of the core piece 9 that is in contact with the opening edge 5b. This pressing causes the core piece 9 to buckle and bend. For example, the pressed area becomes convex forward in the pressing direction, and the outer and inner peripheries relative to the pressed area become convex backward in the pressing direction, resulting in an overall wavy curve.

[0034] The core pieces 9 can be easily and reliably bent because the core pieces 9 have hole portions 9b (see FIG. 3) that form the magnet accommodating holes 7 and the plate thickness of the core pieces 9 is 0.5 mm or less. The outer diameter of the curved core pieces 9 is reduced by the amount of curvature, so they can be smoothly inserted into the annular member 5. This prevents defects such as scratches from occurring on the inner periphery of the annular member 5 when the core pieces 9 are pressed into the annular member 5.

[0035] By sequentially pressing the core pieces 9 in this manner, it is possible to stack a plurality of core pieces 9 in a curved state within the annular member 5, as shown in Fig. 4(B) . The stacking here is not limited to the size of the gaps between the plurality of core pieces 9, as long as the plurality of core pieces 9 are arranged in layers.

[0036] It is also possible to stack a plurality of core pieces 9 in a curved state outside the annular member 5 in advance and then insert these into the annular member 5. It is also possible to sequentially insert and stack core pieces 9 that are curved from the beginning into the annular member 5.

[0037] After stacking the curved core pieces 9 inside the annular member 5 in this way, the curved core pieces 9 are pressed through the openings 5a on both sides of the annular member 5 to return each core piece 9 to a flat plate shape as shown in Figure 4(C). This makes it possible to obtain a rotor core 3 whose outer periphery is engaged with the annular member 5. In other words, a rotor 1 in which the annular member 5 is attached to the outer periphery of the rotor core 3 is obtained.

[0038] An appropriate jig can be used to press the core pieces 9 through the openings 5 ​​a of the annular member 5. In this embodiment, pressing members 15 having an outer periphery similar to the inner periphery of the annular member 5 are disposed on both sides of the core pieces 9 in the axial direction, and pressing or the like is performed.

[0039] In this pressed state, 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 fit, 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.

[0040] 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 in this embodiment by pressing with the pressing member 15. At this time, in this embodiment, the gaps between the multiple core pieces 9 constituting the rotor core 3 are adjusted to 1 μm or less by pressing the multiple core pieces 9 together.

[0041] In this way, the space factor and the gap between the core pieces 9 can be adjusted by pressing with the pressing member 15, and this adjusted state can be maintained by the annular member 5.

[0042] Additionally, compressive stress is applied to the rotor core 3 by the interference fit. This compressive stress counters the tensile stress that occurs in the bridge portion 13 due to the centrifugal force when the rotor 1 rotates. Therefore, the compressive stress due to the interference fit and the strength of the annular member 5 itself improve the centrifugal strength of the rotor 1, allowing the maximum rotation speed of the rotor 1 to be increased.

[0043] Furthermore, if the centrifugal strength is sufficient (no need to improve it), the bridge portion 13 of the rotor core 3 can be made even narrower. In this case, the output can be improved by reducing the leakage flux.

[0044] As described above, in the manufacturing method of the rotor 1 of this embodiment, a plurality of core pieces 9 that are stacked in a curved state so that the outer diameter becomes small are placed inside the annular member 5. Then, the curved core pieces 9 are pressed through the openings 5a on both sides of the annular member 5 to form each core piece 9 into a flat plate shape, thereby obtaining the rotor core 3 whose outer periphery is engaged with the annular member 5.

[0045] Therefore, in this embodiment, the plurality of core pieces 9 in a curved state with a reduced outer diameter can be smoothly arranged inside the annular member 5, and defects such as scratches on the inner periphery of the annular member 5 can be suppressed. Furthermore, by forming the plurality of core pieces 9 into a flat plate shape inside the annular member 5, the outer periphery of the rotor core 3 can be engaged with the inner periphery of the annular member 5, and the rotor core 3 can be securely attached to the annular member 5 by an interference fit.

[0046] Therefore, it is possible to reduce vibration by suppressing imbalance of the rotor 1. Furthermore, in this embodiment, shrink fitting or cold fitting is not required, which makes it possible to reduce assembly costs.

[0047] In this embodiment, when stacking the multiple core pieces 9 in a curved state, flat core pieces 9 having an outer diameter larger than the inner diameter of the annular member 5 are pushed into the annular member 5 through the opening 5a on one side thereof to bend the core pieces 9. Then, the core pieces 9 are pushed in multiple times in sequence to stack the curved core pieces 9 inside the annular member 5.

[0048] Therefore, in this embodiment, the plurality of core pieces 9 can be easily and reliably stacked in a curved state inside the annular member 5. Furthermore, since the core pieces 9 are curved in relation to the annular member 5, the outer diameter of the core pieces 9 in the curved state does not become too large compared to the inner periphery of the annular member 5, and defects such as scratches on the inner periphery of the annular member 5 can be suppressed.

[0049] The core pieces 9 have holes 9b that form the magnet insertion holes 7 of the rotor core 3, and therefore can be easily curved.

[0050] Furthermore, since the core piece 9 has a thickness of 0.5 mm or less, it can be bent more easily.

[0051] Furthermore, in this embodiment, the space factor of the rotor core 3 or the gaps between the core pieces 9 can be adjusted by pressing the curved core pieces 9. 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. In this embodiment, the space factor is 90% or more and the gaps between the core pieces 9 are 1 μm or less, so the performance of the rotor 1 can be improved more reliably.

[0052] REFERENCE SIGNS LIST 1 rotor 3 rotor core 3a end face 5 annular member 5a opening 7 magnet insertion hole 9 core piece 9b hole

Claims

1. A method for manufacturing a rotor in which an annular member is attached to the outer periphery of a rotor core made of multiple stacked plate-shaped core pieces, comprising the steps of: arranging the multiple core pieces within the annular member in a curved state so as to reduce the outer diameter; and pressing the multiple core pieces in the curved state through openings on both sides of the annular member to make each core piece flat, thereby obtaining the rotor core whose outer periphery is engaged with the annular member.

2. A method for manufacturing a rotor as claimed in claim 1, wherein the stacking of the multiple core pieces in the curved state comprises pushing a flat core piece having an outer diameter larger than the inner diameter of the annular member through an opening on one side of the annular member while bending the core piece, and stacking the multiple core pieces in the curved state within the annular member by successively pushing the core piece in multiple times.

3. A method for manufacturing a rotor as claimed in claim 1 or 2, wherein the plurality of flat core pieces constituting the rotor core are indirectly connected to each other via the annular member.

4. A method for manufacturing a rotor according to claim 1 or 2, wherein the core pieces have holes which form magnet insertion holes of the rotor core.

5. A method for manufacturing a rotor according to claim 1 or 2, wherein the thickness of the core piece is 0.5 mm or less.

6. A method for manufacturing a rotor according to claim 1 or 2, comprising the steps of: adjusting a space factor of the rotor core by pressing the plurality of core pieces in the curved state.

7. A method for manufacturing a rotor according to claim 6, wherein the space factor is 90% or more.

8. A method for manufacturing a rotor according to claim 1 or 2, comprising adjusting the gaps between the plurality of core pieces constituting the rotor core by pressing the plurality of core pieces in the curved state.

9. A method for manufacturing a rotor according to claim 7, wherein the gap is 1 μm or less.

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