Rotor

Abstract

To protect a magnet from a protrusion provided in a magnet hole while suppressing influence on magnetic characteristics of a rotor.SOLUTION: A rotor of an electric motor includes a rotor core, a magnet, and a sheet. A plurality of side surfaces of the magnet include: a first major side surface having a first magnetic pole and oriented radially outward; a second major side surface having a second magnetic pole and located opposite the first major side surface; a first minor side surface extending between the first major side surface and the second major side surface; and a second minor side surface extending between the first major side surface and the second major side surface and located opposite the first minor side surface. A magnet hole has a first inner surface facing the first major side surface of the magnet, a second inner surface facing the second major side surface of the magnet, and a first positioning portion protruding from the second inner surface and facing the first minor side surface of the magnet. The number of overlapping sheets located between the first minor surface of the magnet and the first positioning portion of the magnet hole is larger than those located between the first main side surface of the magnet and the first inner surface of the magnet hole.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The technology disclosed in this specification relates to a rotor, and more particularly to a rotor of an electric motor.

Background Art

[0002] Patent Document 1 describes a rotor. This rotor includes a rotor core having magnet holes extending in an axial direction parallel to the rotation axis of the rotor, magnets inserted into the magnet holes and having a plurality of side surfaces extending in the axial direction, and a sheet. The sheet covers a first main side surface having a first magnetic pole and facing the outer side in the radial direction, and a second main side surface having a second magnetic pole and located on the opposite side of the first main side surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a rotor as described above, a technique of positioning or fixing a magnet by providing a protrusion on the inner surface of a magnet hole is known. Since such a protrusion comes into local contact with the magnet, there is a risk of generating excessive stress on the magnet. To avoid this, it is conceivable to wind a sheet around the side surface of the magnet multiple times. However, if the side surface of the magnet is covered multiple times by the sheet, there is a problem that the multiple sheets act as a barrier to magnetic flux and the magnetic characteristics of the rotor deteriorate.

[0005] In view of the above, this specification provides a technique capable of protecting a magnet from a protrusion provided in a magnet hole while suppressing an influence on the magnetic characteristics of a rotor.

Means for Solving the Problems

[0006] The technology disclosed in this specification is embodied in a rotor of an electric motor. The rotor includes a rotor core having magnet holes extending in an axial direction parallel to the rotation axis of the rotor, magnets inserted into the magnet holes and having a plurality of side surfaces extending in the axial direction, and a sheet wound around the plurality of side surfaces of the magnets. The plurality of side surfaces of the magnet include a first main side surface having a first magnetic pole and facing outward in the radial direction, a second main side surface having a second magnetic pole and located on the opposite side of the first main side surface, a first sub-side surface extending between the first main side surface and the second main side surface, and a second sub-side surface extending between the first main side surface and the second main side surface and located on the opposite side of the first sub-side surface. The magnet hole has a first inner surface facing the first main side surface of the magnet, a second inner surface facing the second main side surface of the magnet, and a first positioning portion protruding from the second inner surface and facing the first sub-side surface of the magnet. The number of overlapping sheets of the sheet located between the first sub-side surface of the magnet and the first positioning portion of the magnet hole is larger than the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the first inner surface of the magnet hole.

[0007] In the rotor described above, a first positioning portion is provided on the second inner surface of the magnet hole to position the magnet with respect to the magnet hole. The first positioning portion protrudes from the second inner surface of the magnet hole and faces the first sub-side surface of the magnet. Therefore, it is assumed that the first positioning portion of the magnet hole locally contacts the first sub-side surface of the magnet. However, a sheet is wound around a plurality of side surfaces of the magnet including the first sub-side surface, and a plurality of layers of sheets are interposed between the first sub-side surface of the magnet and the first positioning portion of the magnet hole. As a result, the first sub-side surface of the magnet is effectively protected against contact with the first positioning portion. On the other hand, the first main side surface having a magnetic pole and facing the stator is covered with a relatively small number of layers (including one layer) of sheets. Thereby, while suppressing the influence on the magnetic characteristics of the rotor, the magnet can be protected from the positioning portion provided in the magnet hole.

[0008] In the second aspect, in the first aspect, the number of overlapping sheets located between the first secondary surface of the magnet and the first positioning portion of the magnet hole may be two. In this case, the number of overlapping sheets located between the first main surface of the magnet and the first inner surface of the magnet hole may be one. However, these numbers of overlapping sheets may be larger, and can be appropriately designed according to the material, thickness, etc. of the sheet.

[0009] In the third aspect, in the first or the second aspect, the magnet hole may further have a second positioning portion that protrudes from the second inner surface and faces the second secondary surface of the magnet. In this case, the number of overlapping sheets located between the second secondary surface of the magnet and the second positioning portion of the magnet hole may be more than the number of overlapping sheets located between the first main surface of the magnet and the second inner surface of the magnet hole. Thus, there may be a plurality of positioning portions in the magnet hole, and in that case, each positioning portion may be covered with a plurality of layers of sheets.

[0010] In the fourth aspect, in the third aspect, the number of overlapping sheets located between the second secondary surface of the magnet and the second positioning portion of the magnet hole may be two. In this case, the number of overlapping sheets located between the first main surface of the magnet and the first inner surface of the magnet hole may be one. However, these numbers of overlapping sheets may be larger, and can be appropriately designed according to the material, thickness, etc. of the sheet.

[0011] In the fifth aspect, in any of the first to fourth aspects, the number of overlapping sheets located between the second main surface of the magnet and the second inner surface of the magnet hole may be more than the number of overlapping sheets located between the first main surface of the magnet and the first inner surface of the magnet hole. According to such a configuration, the first main surface that faces the outside in the radial direction is covered with fewer sheets than the second main surface that faces the inside in the radial direction, so that the influence on the magnetic characteristics of the rotor can be suppressed.

[0012] In the sixth aspect, in any one of the first to fifth aspects, the sheet may be composed of a single sheet material. In this case, one end at the start of winding of the single sheet material may be located on one of the first secondary surface and the second secondary surface of the magnet. Also, one end at the end of winding of the single sheet material may be located on the other of the first secondary surface and the second secondary surface of the magnet. According to such a configuration, since there are no ends of the sheet on the first main surface and the second main surface having magnetic poles, the influence on the magnetic characteristics of the rotor can be suppressed.

[0013] In the seventh aspect, in any one of the first to sixth aspects, the magnet hole may further have at least one caulking portion that protrudes from the second inner surface and abuts on the second main surface of the magnet via the sheet. In this case, the number of overlapping sheets located between the second main surface of the magnet and the caulking portion of the magnet hole may be larger than the number of overlapping sheets located between the first main surface of the magnet and the first inner surface of the magnet hole.

[0014] In the above aspect, in order to fix the magnet to the magnet hole, a caulking portion is provided on the second inner surface of the magnet hole. The caulking portion protrudes from the second inner surface of the magnet hole, but since a plurality of layers of sheets are interposed between the caulking portion of the magnet hole and the second main surface of the magnet, the second main surface of the magnet is effectively protected against contact with the caulking portion of the magnet hole. On the other hand, the first main surface having magnetic poles and facing the stator is covered with a relatively small number of layers (including one layer) of sheets. Thereby, while suppressing the influence on the magnetic characteristics of the rotor, the magnet can be protected from the caulking portion provided in the magnet hole.

[0015] In the eighth aspect, in the seventh aspect, the number of overlapping sheets located between the second main surface of the magnet and the caulking portion of the magnet hole may be equal to the number of overlapping sheets located between the first secondary surface of the magnet and the first positioning portion of the magnet hole. However, as another embodiment, the number of overlapping sheets located between the second main surface of the magnet and the caulking portion of the magnet hole may be less than or more than the number of overlapping sheets located between the first secondary surface of the magnet and the first positioning portion of the magnet hole.

[0016] In the ninth aspect, in any of the first to eighth aspects, the sheet may be at least partially composed of a foaming material. According to such a configuration, since the space between the magnet and the magnet hole is filled without a gap by the foaming material, the position of the magnet is stabilized. Further, since the foaming material has high flexibility, each side surface of the magnet can be effectively protected against protrusions such as the first positioning portion, the second positioning portion, and / or the caulking portion.

[0017] In the tenth aspect, in any of the first to ninth aspects, the sheet may be at least partially composed of an insulating material. According to such a configuration, the space between the magnet and the magnet hole can be electrically insulated, and losses caused by eddy currents in the rotor can be suppressed.

[0018] In the eleventh aspect, in any of the first to tenth aspects, the sheet may be at least partially composed of an adhesive material. According to such a configuration, the magnet can be fixed to the magnet hole by the adhesive material of the sheet.

[0019] In the twelfth aspect, in any of the first to eleventh aspects, on the outside of the sheet, at least a part of the magnet hole may be filled with a filler. According to such a configuration, the magnet can be fixed to the magnet hole by the filler.

[0020] The technology disclosed in this specification is embodied in the rotor of another electric motor. This rotor includes a rotor core having magnet holes extending in the axial direction parallel to the rotation axis of the rotor, magnets inserted into the magnet holes and having a plurality of side surfaces extending in the axial direction, and a sheet wound around the plurality of side surfaces of the magnets. The plurality of side surfaces of the magnet include a first main side surface having a first magnetic pole and facing radially outward, a second main side surface having a second magnetic pole and located on the opposite side of the first main side surface, a first sub-side surface extending between the first main side surface and the second main side surface, and a second sub-side surface extending between the first main side surface and the second main side surface and located on the opposite side of the first sub-side surface. The magnet hole has a first inner surface facing the first main side surface of the magnet, a second inner surface facing the second main side surface of the magnet, and a caulking portion protruding from the second inner surface and contacting the first sub-side surface of the magnet via the sheet. The number of overlapping sheets of the sheet located between the second main side surface of the magnet and the caulking portion of the magnet hole is greater than the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the first inner surface of the magnet hole.

[0021] In the above-described rotor, in order to fix the magnet to the magnet hole, a caulking portion is provided on the second inner surface of the magnet hole. The caulking portion protrudes from the second inner surface of the magnet hole, but since a plurality of layers of sheets are interposed between the caulking portion of the magnet hole and the second main side surface of the magnet, the second main side surface of the magnet is effectively protected against contact with the caulking portion of the magnet hole. On the other hand, the first main side surface having magnetic poles and facing the stator is covered with a relatively small number of layers (including one layer) of sheets. Thereby, it is possible to protect the magnet from the caulking portion provided in the magnet hole while suppressing the influence on the magnetic characteristics of the rotor.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

BEST MODE FOR CARRYING OUT THE INVENTION

[0023] (Example 1) With reference to the drawings, the rotor 10 of Example 1 will be described. The rotor 10 of this example is employed in an electric motor 100. The electric motor 100 includes a rotor 10, a stator 102, and a housing 104. The housing 104 is a housing member. The housing 104 houses the rotor 10 and the stator 102. Although it is an example, the housing 104 is mainly made of metal. The rotor 10 is rotatably supported with respect to the housing 104 about the rotation axis R. Although not particularly limited, the housing 104 may further house a power transmission mechanism (not shown) such as a speed reduction mechanism or a differential mechanism.

[0024] The stator 102 generally has a cylindrical shape with the rotation axis R as the central axis. The stator 102 is disposed on the outer side in the radial direction of the rotor 10. The stator 102 is fixed to the inner wall of the housing 104. The stator 102 includes a stator core 102a and a stator coil 102b. The stator core 102a is made of a soft magnetic material such as electromagnetic steel, for example. Although it is an example, the stator core 102a in the present embodiment is configured by laminating a plurality of electromagnetic steel sheets. The stator coil 102b is wound around the stator core 102a and is configured to magnetize the stator core 102a. Although it is an example, the electric motor 100 in the present embodiment is a three-phase motor, and the stator coil 102b includes one or more U-phase coils, one or more V-phase coils, and one or more W-phase coils. However, the specific configuration of the stator 102 is not particularly limited.

[0025] As shown in FIGS. 1 and 2, the rotor 10 includes a shaft 12 and a rotor core 14. The shaft 12 is arranged such that its central axis coincides with the rotation axis R. The shaft 12 is made of a metal such as stainless steel, for example. The rotor core 14 is located on the outer side in the radial direction of the shaft 12 and has a cylindrical shape extending parallel to the rotation axis R. The rotor core 14 is made of a soft magnetic material such as electromagnetic steel, for example. Although it is an example, the rotor core 14 in the present embodiment is configured by laminating a plurality of electromagnetic steel sheets. A through hole 14a is provided at the center of the rotor core 14, and the shaft 12 is inserted into the through hole 14a. The rotor core 14 is fixed to the shaft 12, and relative rotation with respect to the shaft 12 is prohibited.

[0026] As shown in FIGS. 1 and 2, the rotor 10 further includes a plurality of magnet holes 16a, 16b and a plurality of magnets 18. The plurality of magnet holes 16a, 16b are located in the outer peripheral portion of the rotor core 14 and are regularly arranged along the circumferential direction. Each of the magnet holes 16a, 16b extends in the axial direction parallel to the rotation axis R of the rotor 10. The cross-sectional shape of each of the magnet holes 16a, 16b is a slot shape extending along the circumferential direction, and the longitudinal axis of the slot shape forms an angle with respect to the circumferential direction. The plurality of magnet holes 16a, 16b include a plurality of pairs of first magnet holes 16a and a plurality of pairs of second magnet holes 16b. Each pair of first magnet holes 16a is symmetrically arranged in the circumferential direction of the rotor core 14. One magnet 18 is inserted into each first magnet hole 16a. Similarly, each pair of second magnet holes 16b is symmetrically arranged in the circumferential direction of the rotor core 14. Each pair of second magnet holes 16b is located radially inside the corresponding pair of first magnet holes 16a. Two magnets 18 are inserted into each second magnet hole 16b. Each magnet 18 has a substantially rectangular parallelepiped shape extending in the axial direction parallel to the rotation axis R of the rotor 10. Although not particularly limited, each magnet 18 is a permanent magnet.

[0027] Next, with reference to FIG. 3, the configuration related to one first magnet hole 16a and the magnet 18 inserted therein will be described. The configuration described below is similarly adopted for the other first magnet holes 16a and the magnets 18 inserted therein, as well as for the second magnet holes 16b and the two magnets 18 inserted therein.

[0028] As shown in FIG. 3, the magnet 18 has a plurality of axially extending side surfaces 20, 22, 24, 26. The plurality of side surfaces 20, 22, 24, 26 include a first main side surface 20, a second main side surface 22, a first sub side surface 24, and a second sub side surface 26. The first main side surface 20 has a first magnetic pole and faces radially outward. Note that the first main side surface 20 facing radially outward means that the normal vector of the first main side surface 20 includes a component facing at least radially outward. That is, each of the plurality of magnets 18 does not necessarily have to be perpendicular to the radial direction, and each may be inclined with respect to the radial direction. The first magnetic pole is either an N pole or an S pole. In the electric motor 100, the first main side surface 20 of the rotor 10 faces the stator 102. The second main side surface 22 has a second magnetic pole and is located on the opposite side of the first main side surface 20. The second magnetic pole is the opposite pole of the first magnetic pole and is the other of the N pole or the S pole. The first sub side surface 24 extends between the first main side surface 20 and the second main side surface 22. The second sub side surface 26 extends between the first main side surface 20 and the second main side surface 22 and is located on the opposite side of the first sub side surface 24. When the rotor 10 is viewed from a direction parallel to the rotation axis R, the first main side surface 20, the first sub side surface 24, the second main side surface 22, and the second sub side surface 26 are arranged in series in that order. The area of each of the first main side surface 20 and the second main side surface 22 is larger than the area of each of the first sub side surface 24 and the second sub side surface 26.

[0029] As shown in FIG. 3, the first magnet hole 16a has a first inner surface 28 and a second inner surface 30. The first inner surface 28 faces the first main side surface 20 of the magnet 18. The second inner surface 30 faces the second main side surface 22 of the magnet 18. The second inner surface 30 is provided with a first positioning portion 32 and a second positioning portion 34. These positioning portions 32, 34 are portions for positioning the magnet 18 with respect to the first magnet hole 16a. The first positioning portion 32 protrudes from the second inner surface 30 and faces the first sub side surface 24 of the magnet 18. The second positioning portion 34 protrudes from the second inner surface 30 and faces the second sub side surface 26 of the magnet 18. Since the second inner surface 30 of the first magnet hole 16a forms an angle with respect to the circumferential direction, the first positioning portion 32 is located radially outside the second positioning portion 34.

[0030] In the above-described rotor 10, positioning portions 32 and 34 are provided on the second inner surface 30 of the first magnet hole 16a in order to position the magnet 18 with respect to the first magnet hole 16a. The positioning portions 32 and 34 protrude from the second inner surface 30 of the first magnet hole 16a and face the secondary side surfaces 24 and 26 of the magnet 18. Therefore, it is assumed that the positioning portions 32 and 34 of the first magnet hole 16a locally contact the secondary side surfaces 24 and 26 of the magnet 18.

[0031] Regarding the above point, as shown in FIG. 3, the rotor 10 further includes a sheet 36. The sheet 36 in this embodiment is composed of a single sheet material. The sheet 36 is wound around a plurality of side surfaces 20, 22, 24, and 26 of the magnet 18. Although it is an example, one end 36a at the start of winding of the sheet 36 is located on the first secondary side surface 24 of the magnet 18, and one end 36b at the end of winding of the sheet 36 is located on the second secondary side surface 26 of the magnet 18. For example, in the manufacturing process of the rotor 10, starting from the state where one end 36a of the sheet 36 is positioned on the first secondary side surface 24 of the magnet 18, the sheet 36 is wound around the magnet 18. At this time, the second main side surface 22, the second secondary side surface 26, and the first main side surface 20 are sequentially covered by the sheet 36. When the sheet 36 is again in the state of being located on the second secondary side surface 26 of the magnet 18, the sheet 36 is cut. As a result, one end 36a at the start of winding of the sheet 36 is located on the first secondary side surface 24 of the magnet 18, and one end 36b at the end of winding of the sheet 36 is located on the second secondary side surface 26 of the magnet 18. In other words, one end 36a at the start of winding of the sheet 36 is the end located on the innermost layer in the sheet 36 wound around the magnet 18, and one end 36b at the end of winding of the sheet 36 is the end located on the outermost layer in the sheet 36 wound around the magnet 18.

[0032] In this embodiment, the number of stacked sheets 36 located between the first secondary side surface 24 of the magnet 18 and the first positioning portion 32 of the first magnet hole 16a is two, and the number of stacked sheets 36 located between the first main side surface 20 of the magnet 18 and the first inner surface 28 of the first magnet hole 16a is one. Also, the number of stacked sheets 36 located between the second secondary side surface 26 of the magnet 18 and the second positioning portion 34 of the first magnet hole 16a is two, and the number of stacked sheets 36 located between the first main side surface 20 of the magnet 18 and the second inner surface 30 of the first magnet hole 16a is one.

[0033] According to such a configuration, the secondary side surfaces 24 and 26 of the magnet 18 are effectively protected against contact with the positioning portions 32 and 34. On the other hand, the first main side surface 20, which has magnetic poles and faces the stator 102, is covered only with a relatively small number of layers (one layer in this embodiment) of the sheet 36. Thereby, while suppressing the influence on the magnetic characteristics of the rotor 10, the magnet 18 can be protected from the positioning portions 32 and 34 provided in the first magnet hole 16a.

[0034] Although not particularly limited, in the rotor 10 described above, as shown in FIG. 3, the number of stacked sheets 36 (two layers in this embodiment) located between the second main side surface 22 of the magnet 18 and the second inner surface 30 of the first magnet hole 16a is larger than the number of stacked sheets 36 (one layer in this embodiment) located between the first main side surface 20 of the magnet 18 and the first inner surfaces 28 of the magnet holes 16a and 16b. According to such a configuration, since the first main side surface 20 directed outward in the radial direction is covered with fewer sheets 36 than the second main side surface 22 directed inward in the radial direction, the influence on the magnetic characteristics of the rotor 10 can be suppressed.

[0035] In this embodiment, the number of stacked sheets 36 located between the secondary side surfaces 24 and 26 of the magnet 18 and the positioning portions 32 and 34 of the first magnet hole 16a is two, and the number of stacked sheets 36 located between the first main side surface 20 of the magnet 18 and the first inner surface 28 of the first magnet hole 16a is one. However, as another embodiment, these numbers of stacked sheets may be larger. In this case, it is sufficient that the number of stacked sheets 36 located between the secondary side surfaces 24 and 26 of the magnet 18 and the positioning portions 32 and 34 of the first magnet hole 16a is larger than the number of stacked sheets 36 located between the first main side surface 20 of the magnet 18 and the first inner surface 28 of the first magnet hole 16a. Note that the number of stacked sheets 36 located between the first secondary side surface 24 of the magnet 18 and the first positioning portion 32 of the first magnet hole 16a may be larger or smaller than the number of stacked sheets 36 located between the second secondary side surface 26 of the magnet 18 and the second positioning portion 34 of the first magnet hole 16a.

[0036] In this embodiment, the first magnet hole 16a is provided with two positioning portions 32 and 34. However, the number of positioning portions 32 and 34 provided in the first magnet hole 16a is not particularly limited. As another embodiment, the first magnet hole 16a may be provided with one positioning portion, and in this case, the positioning portion may be covered with a plurality of layers of the sheet 36. Alternatively, as yet another embodiment, the first magnet hole 16a may be provided with three or more positioning portions, and in this case, each positioning portion may be covered with a plurality of layers of the sheet 36.

[0037] In this embodiment, one end 36a at the start of winding of the sheet 36 is located on the first secondary side surface 24 of the magnet 18, and one end 36b at the end of winding of the sheet 36 is located on the second secondary side surface 26 of the magnet 18. According to such a configuration, since one ends 36a and 36b of the sheet 36 do not exist on the first main side surface 20 and the second main side surface 22 having magnetic poles, the influence on the magnetic characteristics of the rotor 10 can be suppressed. As another embodiment, one end 36a at the start of winding of the sheet 36 may be located on the second secondary side surface 26 of the magnet 18, and one end 36b at the end of winding of the sheet 36 may be located on the first secondary side surface 24 of the magnet 18. Further, the sheet 36 does not necessarily have to be constituted by a single sheet material, and may be constituted by combining a plurality of sheet materials. For example, the sheet 36 may be constituted by a first sheet covering a plurality of side surfaces 20, 22, 24, 26 of the magnet 18 and a second sheet further covering the second main side surface 22 covered by the first sheet.

[0038] Although not particularly limited, the sheet 36 in this embodiment is at least partially constituted by using a foaming material. According to such a configuration, since the gap between the magnet 18 and the first magnet hole 16a is filled without a gap by the foaming material, the position of the magnet 18 is stabilized. Further, since the foaming material has high flexibility, it is possible to effectively protect the side surfaces 20, 22, 24, 26 of the magnet 18 against protrusions such as the positioning portions 32 and 34.

[0039] In addition to or instead of the above, the sheet 36 in this embodiment is at least partially constituted by using an insulating material. According to such a configuration, it is possible to electrically insulate between the magnet 18 and the first magnet hole 16a, and it is possible to suppress the loss caused by the eddy current of the rotor 10.

[0040] In addition to or instead of the above, the sheet 36 in this embodiment is at least partially constituted by using an adhesive material. According to such a configuration, the magnet 18 can be fixed to the first magnet hole 16a by the adhesive material of the sheet 36.

[0041] In this embodiment, each pair of second magnet holes 16b is located radially inward with respect to the corresponding pair of first magnet holes 16a, and magnets 18 are inserted into each of the magnet holes 16a and 16b. Therefore, the plurality of magnets 18 include magnets 18 inserted into the first magnet holes 16a and arranged radially outward, and magnets 18 inserted into the second magnet holes 16b and arranged radially inward. That is, in this embodiment, the plurality of magnets 18 are arranged in two layers in the radial direction. However, the plurality of magnets 18 do not necessarily have to be arranged in two layers in the radial direction. In other embodiments, the plurality of magnets 18 may be arranged in one layer in the radial direction, or may be arranged in three or more layers. Also, in each of those layers, the plurality of magnets 18 may be repeatedly arranged in a V shape.

[0042] In this embodiment, each magnet 18 has a substantially rectangular parallelepiped shape extending in the axial direction parallel to the rotation axis R of the rotor 10. However, each magnet 18 does not necessarily have to have a substantially rectangular parallelepiped shape. For example, as another embodiment, each magnet 18 may have a plate shape in which the first main side surface 20 and the second main side surface 22 are curved. Also, such curved magnets may be arranged in two or more layers in the radial direction.

[0043] (Embodiment 2) Referring to FIG. 4, the rotor 110 of Embodiment 2 will be described. As shown in FIG. 4, in the rotor 110 of Embodiment 2, caulking portions 38 are provided in the first magnet holes 16a as compared with the rotor 10 of Embodiment 1. Since the remaining configuration is the same as that of the rotor 10 of Embodiment 1, redundant description will be omitted here. Note that the configuration related to the first magnet hole 16a described in this embodiment is also adopted for other first magnet holes 16a and second magnet holes 16b.

[0044] As shown in FIG. 4, the caulked portion 38 protrudes from the second inner surface 30 and abuts against the second main side surface 22 of the magnet 18 via the sheet 36. In this case, the number of overlapping sheets 36 (two layers in this embodiment) located between the second main side surface 22 of the magnet 18 and the caulked portion 38 of the first magnet hole 16a is more than the number of overlapping sheets 36 (one layer in this embodiment) located between the first main side surface 20 of the magnet 18 and the first inner surface 28 of the first magnet hole 16a. Note that the number and arrangement of the caulked portions 38 are not particularly limited, and it is sufficient that the caulked portion 38 protrudes from the second inner surface 30 and abuts against the second main side surface 22 of the magnet 18 via the sheet 36. Although not particularly limited, in the rotor 210 of this embodiment, the caulked portion 38 is formed by stamping, and there is a stamping mark 40 near the caulked portion 38 on the end surface in the axial direction of the rotor 210.

[0045] In the rotor 110 of the second embodiment, in order to fix the magnet 18 to the first magnet hole 16a, a caulked portion 38 is provided on the second inner surface 30 of the first magnet hole 16a. The caulked portion 38 protrudes from the second inner surface 30 of the first magnet hole 16a. However, since a plurality of layers of sheets 36 are interposed between the caulked portion 38 of the first magnet hole 16a and the second main side surface 22 of the magnet 18, the second main side surface 22 of the magnet 18 is effectively protected against contact with the caulked portion 38 of the first magnet hole 16a. On the other hand, the first main side surface 20 having magnetic poles and facing the stator 102 is covered with a relatively small number of layers (including one layer) of the sheet 36. Thereby, while suppressing the influence on the magnetic characteristics of the rotor 10, the magnet 18 can be protected from the caulked portion 38 provided in the first magnet hole 16a.

[0046] As described above, the configuration related to the first magnet hole 16a described in the second embodiment is also adopted for the other first magnet holes 16a and the plurality of second magnet holes 16b, respectively. That is, also in those magnet holes 16a and 16b, the caulked portion 38 is provided on the second inner surface 30. And the number of overlapping sheets 36 located between the second main side surface 22 of the magnet 18 and the caulked portions 38 of the magnet holes 16a and 16b is more than the number of overlapping sheets 36 located between the first main side surface 20 of the magnet 18 and the first inner surfaces 28 of the magnet holes 16a and 16b.

[0047] Although not particularly limited, in the rotor 110 of Example 2, the number of overlapping sheets 36 located between the second main side surface 22 of the magnet 18 and the caulking portion 38 of the first magnet hole 16a is equal to the number of overlapping sheets 36 located between the first sub-side surface 24 of the magnet 18 and the positioning portions 32, 34 of the first magnet hole 16a. However, as another embodiment, the number of overlapping sheets 36 located between the second main side surface 22 of the magnet 18 and the caulking portion 38 of the first magnet hole 16a may be less than or more than the number of overlapping sheets 36 located between the first sub-side surface 24 of the magnet 18 and the positioning portions 32, 34 of the first magnet hole 16a.

[0048] (Example 3) Referring to FIG. 5, the rotor 210 of Example 3 will be described. As shown in FIG. 5, the rotor 210 of Example 3 is filled with a filler 42 in the first magnet hole 16a as compared with the rotor 10 of Example 1. Since the remaining configuration is the same as that of the rotor 10 of Example 1, the overlapping description is omitted here. Although not shown in the figure, a similar filler 42 is also filled in other first magnet holes 16a and second magnet holes 16b.

[0049] As shown in FIG. 5, the filler 42 fills the gap between the first magnet hole 16a and the sheet 36 outside the sheet 36. According to such a configuration, the magnet 18 is fixed to the first magnet hole 16a. However, the filler 42 does not necessarily have to completely fill the gap between the first magnet hole 16a and the sheet 36. The filler 42 may be filled in at least a part of the gap. The material constituting the filler 42 is not particularly limited. As an example, the material constituting the filler 42 is preferably an electrically insulating material and also preferably a non-magnetic material magnetically. As an example, the filler 42 in this embodiment is a resin material, particularly a thermosetting resin material.

[0050] In one example, as shown in FIG. 5, the range where the filler 42 of the first magnet hole 16a is filled is mainly provided on both sides of the magnet 18. That is, the gap between the first magnet hole 16a and the magnet 18 is divided into a first region located on the side of the first secondary surface 24 of the first magnet hole 16a and a second region located on the side of the second secondary surface 26 of the first magnet hole 16a. Here, one end 36a at the start of winding of the sheet 36 is located in the first region, and the one end 36a at the start of winding does not directly contact the filler 42. On the other hand, one end 36b at the end of winding of the sheet 36 is located in the second region, and the one end 36b at the end of winding directly contacts the filler 42. Therefore, when filling the filler 42 into the gap between the first magnet hole 16a and the magnet 18 in the manufacture of the rotor 210, it is preferable to fill the filler 42 from the first region where the one end 36a at the start of winding is located. Thereby, it is difficult for the filler 42 to intrude inside the sheet 36, and folding or breakage of the sheet 36 is avoided.

[0051] (Example 4) Referring to FIG. 6, the rotor 310 of Example 4 will be described. As shown in FIG. 6, compared with the rotor 110 of Example 2, the first magnet hole 16a of the rotor 310 of Example 4 is filled with the filler 42. Since the remaining configuration is the same as that of the rotor 110 of Example 2, the overlapping description will be omitted here. Although not shown in the figure, the same filler 42 is also filled in other first magnet holes 16a and second magnet holes 16b. Since the configuration, action, and effect of the filler 42 in this embodiment are the same as those of the filler 42 in Example 3, the overlapping description will be omitted here.

[0052] (Example 5) With reference to FIG. 7, the rotor 410 of Example 5 will be described. As shown in FIG. 7, compared with the rotor 10 of Example 1, the first magnet hole 16a of the rotor 410 of Example 5 is provided with a caulking portion 38 instead of the positioning portions 32 and 34. In other words, the rotor 410 of Example 5 is obtained by removing the positioning portions 32 and 34 from the rotor 110 of Example 2. It should be noted that the positioning portions 32 and 34 are not provided in the other first magnet holes 16a and the second magnet holes 16b either, which is different from the rotor 110 of Example 2 in this regard. Since the remaining configurations are the same as those of the rotor 110 of Example 2, duplicate descriptions are omitted here.

[0053] (Example 6) With reference to FIG. 8, the rotor 510 of Example 6 will be described. As shown in FIG. 8, compared with the rotor 410 of Example 5, the first magnet hole 16a of the rotor 510 of Example 6 is filled with a filler 42. Although not shown, the same filler 42 is also filled in the other first magnet holes 16a and the second magnet holes 16b. Since the configuration, action, and effect of the filler 42 in this example are the same as those of the filler 42 in Examples 3 and 4, duplicate descriptions are omitted here.

[0054] As described above in detail with several specific examples, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility either alone or in combination.

Description of Reference Numerals

[0055] 10: Rotor, 12: Shaft, 14: Rotor Core, 16a, 16b: Magnet Holes, 18: Magnet, 20: First Main Side, 22: Second Main Side, 24: First Sub-Side, 26: Second Sub-Side, 28: First Inner Surface, 30: Second Inner Surface, 32, 34: Positioning Portions, 36: Sheet, 38: Caulking Portion, 40: Indentation, 42: Filler, 100: Electric Motor, 102: Stator, 104: Housing, R: Rotation Axis

Claims

1. A rotor of an electric motor, comprising: a rotor core having magnet holes extending in an axial direction parallel to the rotation axis of the rotor; magnets inserted into the magnet holes and having a plurality of side surfaces extending in the axial direction; a sheet wound around the plurality of side surfaces of the magnets; wherein the plurality of side surfaces of the magnet have a first main side surface having a first magnetic pole and facing radially outward, a second main side surface having a second magnetic pole and located on the opposite side of the first main side surface, a first sub-side surface extending between the first main side surface and the second main side surface, and a second sub-side surface extending between the first main side surface and the second main side surface and located on the opposite side of the first sub-side surface; the magnet hole has a first inner surface facing the first main side surface of the magnet, a second inner surface facing the second main side surface of the magnet, and a first positioning portion protruding from the second inner surface and facing the first sub-side surface of the magnet; the number of overlapping sheets of the sheet located between the first sub-side surface of the magnet and the first positioning portion of the magnet hole is greater than the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the first inner surface of the magnet hole; a rotor.

2. The number of overlapping sheets of the sheet located between the first sub-side surface of the magnet and the first positioning portion of the magnet hole is two, and the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the first inner surface of the magnet hole is one. The rotor according to claim 1.

3. The magnet hole further has a second positioning portion protruding from the second inner surface and facing the second sub-side surface of the magnet, and the number of overlapping sheets of the sheet located between the second sub-side surface of the magnet and the second positioning portion of the magnet hole is greater than the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the second inner surface of the magnet hole. The rotor according to claim 1.

4. The number of overlapping sheets of the sheet located between the second sub-side surface of the magnet and the second positioning portion of the magnet hole is two, and the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the first inner surface of the magnet hole is one. The rotor according to claim 3.

5. The number of overlapping sheets of the sheet positioned between the second main side surface of the magnet and the second inner surface of the magnet hole is greater than the number of overlapping sheets of the sheet positioned between the first main side surface of the magnet and the first inner surface of the magnet hole. The rotor according to claim 3.

6. The sheet is composed of a single sheet material, One end at the start of winding of the single sheet material is located on one of the first sub-side surface and the second sub-side surface of the magnet, One end at the end of winding of the single sheet material is located on the other of the first sub-side surface and the second sub-side surface of the magnet. The rotor according to claim 5.

7. The magnet hole further has at least one caulking portion that protrudes from the second inner surface and abuts on the second main side surface of the magnet via the sheet, The number of overlapping sheets of the sheet positioned between the second main side surface of the magnet and the caulking portion of the magnet hole is greater than the number of overlapping sheets of the sheet positioned between the first main side surface of the magnet and the first inner surface of the magnet hole. The rotor according to claim 1.

8. The number of overlapping sheets of the sheet positioned between the second main side surface of the magnet and the caulking portion of the magnet hole is equal to the number of overlapping sheets of the sheet positioned between the first sub-side surface of the magnet and the first positioning portion of the magnet hole. The rotor according to claim 7.

9. The sheet is at least partially composed of a foaming material. The rotor according to claim 1.

10. The sheet is at least partially composed of an insulating material. The rotor according to claim 1.

11. The sheet is at least partially composed of an adhesive material. The rotor according to claim 1.

12. Outside the sheet, at least a part of the magnet hole is filled with a filler. The rotor according to claim 1.

13. A rotor of an electric motor, A rotor core having a magnet hole extending in an axial direction parallel to the rotation axis of the rotor, A magnet inserted into the magnet hole and having a plurality of side surfaces extending in the axial direction, A sheet wound around the plurality of side surfaces of the magnet, Comprising The plurality of side surfaces of the magnet have a first main side surface having a first magnetic pole and facing radially outward, a second main side surface having a second magnetic pole and located on the opposite side of the first main side surface, a first sub-side surface extending between the first main side surface and the second main side surface, and a second sub-side surface extending between the first main side surface and the second main side surface and located on the opposite side of the first sub-side surface. The magnet hole has a first inner surface facing the first main side surface of the magnet, a second inner surface facing the second main side surface of the magnet, and a caulking portion protruding from the second inner surface and contacting the first sub-side surface of the magnet via the sheet. The number of overlapping sheets of the sheet located between the second main side surface of the magnet and the caulking portion of the magnet hole is greater than the number of overlapping sheets of the sheet located between the first main side surface of the magnet and the first inner surface of the magnet hole. Rotor.

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