JP7733620B2 - Reluctance rotating electric machine - Google Patents

Description

An embodiment of the present invention relates to a reluctance rotating electric machine.

Conventionally, there is a reluctance rotating electric machine that has a rotor core in which multiple annular plates are stacked axially around the central axis of rotation.

Japanese Patent Application Laid-Open No. 2022-103103

In this type of reluctance rotating machine, it would be beneficial, for example, if the generation of leakage magnetic flux could be suppressed.

One example of the problem solved by this invention is to provide a reluctance rotating electric machine with a novel configuration that can suppress leakage magnetic flux.

A reluctance rotating electric machine according to one embodiment of the present invention includes a stator and a rotor. A portion of the rotor is located inside the stator and is rotatable around a central axis of rotation. The rotor has a shaft, a rotor core, and a fixed portion. The shaft extends in the axial direction of the central axis of rotation. The rotor core is annular about the central axis of rotation and includes a plurality of plates stacked in the axial direction. The fixed portion has a first clamping portion and a second clamping portion. The first clamping portion is provided on the shaft and located on one side of the rotor core in the axial direction. The second clamping portion is fixed to the shaft and located on the other side of the rotor core in the axial direction, and is connected to the first clamping portion via the shaft located inside the rotor core. The fixed portion fixes the plurality of plates to each other by clamping the rotor core between the first clamping portion and the second clamping portion. The rotor core has a plurality of flux barrier groups spaced apart circumferentially around the central axis of rotation, and each of the flux barrier groups has a plurality of flux barriers that are convex radially inward of the central axis of rotation and are arranged at intervals in the radial direction, and the second clamping portion is provided for each flux barrier group, and when viewed from the axial direction, is located radially inward of the flux barrier groups and is arranged radially at the tops of the convex shapes of the flux barriers, reinforcing the rotor core.

The present invention provides a reluctance rotating electric machine with a novel configuration that can suppress leakage magnetic flux.

FIG. 1 is a cross-sectional view that schematically shows a reluctance rotating electric machine according to an embodiment. FIG. 2 is a front view schematically showing the stator and rotor of the reluctance rotating electric machine according to the embodiment. FIG. 3 is a cross-sectional view schematically showing a part of the rotor of the reluctance rotating electric machine according to the embodiment. FIG. 4 is a front view schematically showing a rotor of a reluctance rotating electric machine according to an embodiment. FIG. 5 is a cross-sectional view that schematically shows a part of a rotor of a reluctance rotating electric machine of a comparative example. FIG. 6 is a front view schematically showing a rotor of a reluctance rotating electric machine of a comparative example. FIG. 7 is a front view schematically showing a rotor of a reluctance rotating electric machine according to a modified example of the embodiment.

The following describes exemplary embodiments of the present invention. The configurations of the embodiments described below, as well as the actions and effects achieved by those configurations, are merely examples. The present invention can also be realized with configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) achieved by the configurations.

The drawings are schematic, and the dimensional relationships and proportions of each element may differ from reality. The drawings may also contain parts with different dimensional relationships and proportions. Furthermore, ordinal numbers in this specification are used only to distinguish between parts, members, locations, positions, directions, etc., and do not indicate order or priority.

Figure 1 is a cross-sectional view that schematically illustrates a reluctance rotating electric machine 10 according to an embodiment. The reluctance rotating electric machine 10 is, for example, a reluctance motor (electric motor). Note that the reluctance rotating electric machine 10 may also be a generator.

The reluctance rotating electric machine 10 comprises a stator 11, a rotor 12, a housing 13, and two bearings 15.

For convenience, the terms axial direction, radial direction, and circumferential direction are defined herein. The axial direction is the direction along the central axis of rotation Ax. The radial direction is the direction perpendicular to the central axis of rotation Ax. The circumferential direction is the direction of rotation around the central axis of rotation Ax.

The central axis of rotation Ax is the center of rotation of the rotor 12 in the reluctance rotating electric machine 10, and is, for example, an imaginary line passing through the center of the shaft 14 of the rotor 12.

The housing 13 has a frame 41 and two bearing brackets 42. The frame 41 is formed in a generally cylindrical shape surrounding the central axis of rotation Ax. The stator 11 and a portion of the rotor 12 are disposed inside the frame 41.

Two bearing brackets 42 are connected to both ends of the frame 41 in the axial direction. The bearing brackets 42 close the space inside the frame 41. Each bearing bracket 42 supports a corresponding bearing 15. The bearing brackets 42 are also referred to as walls.

The stator 11 has a stator core 21 and a stator winding 22. The stator core 21 is fixed to the frame 41.

Figure 2 is a front view showing a schematic diagram of the stator 11 and rotor 12 of the reluctance rotating electric machine 10 of the embodiment.

As shown in Figures 1 and 2, the stator core 21 is formed in a generally cylindrical shape surrounding the central axis of rotation Ax. The stator core 21 has multiple stator steel plates stacked on top of each other in the axial direction. The stator steel plates are, for example, electromagnetic steel plates, and are made of a magnetic material.

As shown in Figure 2, multiple teeth 21a are provided at circumferential intervals on the inner peripheral surface of the stator core 21. Slots 21b are formed between adjacent teeth 21a in the circumferential direction. The stator windings 22 are wound around the teeth 21a while inserted into the slots 21b. Note that the stator windings 22 are not shown in Figure 2.

As shown in Figures 1 and 2, the rotor 12 has a shaft 14 and a cylindrical body 31. A portion of the rotor 12 is located inside the stator 11 and is rotatable around the central axis of rotation Ax.

As shown in FIG. 1, the shaft 14 is formed in a generally cylindrical shape extending along the central axis of rotation Ax. The shaft 14 passes through the bearing bracket 42 and extends between the interior and exterior of the housing 13. The shaft 14 is supported by bearings 15 so that it can rotate around the central axis of rotation Ax.

The shaft 14 extends axially through the inside of the stator 11 and the cylindrical body 31. The shaft 14 is connected to the cylindrical body 31.

The cylindrical body 31 is disposed inside the stator core 21. The cylindrical body 31 is formed in a generally cylindrical shape surrounding the central axis of rotation Ax. That is, the cylindrical body 31 has a hole 31a that penetrates the cylindrical body 31 in the axial direction. The shaft 14 is inserted into the hole 31a.

The cylindrical body 31 has a rotor core 50 and two pressure plates 52. Note that the pressure plates 52 are not shown in Figure 2. The pressure plates 52 are also called end plates.

The rotor core 50 is formed in a cylindrical shape around the central axis of rotation Ax. The rotor core 50 has a hole 50a that passes through the rotor core 50 in the axial direction.

The rotor core 50 has multiple rotor steel plates 51. The rotor steel plates 51 are electromagnetic steel plates made of a magnetic material. The rotor steel plates 51 are annular around the central axis of rotation Ax. Specifically, the rotor steel plates 51 are disk-shaped. The thickness direction of the rotor steel plates 51 is along the axial direction. The multiple rotor steel plates 51 are stacked in the axial direction. The multiple rotor steel plates 51 are fixed to each other and integrated by fixing portions 60. The shaft 14 is placed inside the multiple rotor steel plates 51. The rotor steel plates 51 are an example of plates. The rotor steel plates 51 are also called blanks.

Figure 3 is a cross-sectional view schematically illustrating a portion of the rotor 12 of the reluctance rotating electric machine 10 of the embodiment. As shown in Figures 1 and 3, the two pressure plates 52 are pressure plate 52A and pressure plate 52B. Pressure plate 52A is located on one axial side (the right side in Figures 1 and 3) of the rotor core 50 and overlaps the rotor steel plate 51 located at the end of one axial side of the multiple rotor steel plates 51. Pressure plate 52B is located on the other axial side (the left side in Figures 1 and 3) of the rotor core 50 and overlaps the rotor steel plate 51 located at the end of the other axial side of the multiple rotor steel plates 51.

The retaining plate 52 is annular around the central axis of rotation Ax. Specifically, the retaining plate 52 is disk-shaped. The shaft 14 is placed inside the retaining plate 52.

The two bearings 15 are located on one axial side and the other axial side of the cylindrical body 31. In other words, the cylindrical body 31 is located between the two bearings 15.

Next, the shaft 14 and cylindrical body 31 will be described in detail. Figure 4 is a front view showing the rotor 12 of the reluctance rotating electric machine 10 of this embodiment.

As shown in Figures 3 and 4, the shaft 14 has a cylindrical outer surface 14a around the central axis of rotation Ax. Also, as shown in Figure 3, the shaft 14 has multiple cylindrical regions 14b to 14e around the central axis of rotation Ax.

Region 14b is a portion of the shaft 14 located inside the cylindrical body 31. Region 14c is located on one axial side of region 14b and is connected to region 14b. The diameter of region 14c is larger than the diameter of region 14b. As a result, region 14c forms surface 12m that protrudes radially outward from region 14b. Surface 12m faces the other axial side, i.e., toward the cylindrical body 31. Surface 12m is annular around the central axis of rotation Ax.

Region 14d is located on the other axial side of region 14b and is connected to region 14b. The diameter of region 14d is smaller than the diameter of region 14b.

Region 14e is located on the other axial side of region 14d and is connected to region 14d. The diameter of region 14e is larger than the diameter of region 14d.

A recess 12n is provided between region 14b and region 14e, with the outer peripheral surface of region 14d as its bottom surface.

As shown in FIG. 4, the rotor core 50 of the cylindrical body 31 is provided with multiple flux barrier groups 53. The number of flux barrier groups 53 matches the number of poles of the rotor core 50 (for example, four).

The multiple flux barrier groups 53 are spaced apart circumferentially. Each flux barrier group 53 has multiple flux barriers 53a. Each flux barrier 53a is a through-hole (hollow portion) that penetrates the rotor core 50 in the axial direction. In other words, the flux barriers 53a are openings provided in the rotor core 50. The flux barriers 53a are formed in a roughly arc shape to follow the flow of magnetic flux that is formed when current is applied to the stator winding 22. This results in the rotor core 50 being formed with areas (directions) where magnetic flux flows easily and areas (directions) where magnetic flux flows poorly. In Figure 2, line L1 indicates an example of the magnetic flux flow. Note that the flux barriers 53a are not limited to the above. The flux barriers 53a may also be cutouts.

In the reluctance rotating electric machine 10, rotational force can be generated by controlling the flow path of magnetic flux using the flux barrier 53a. In other words, the reluctance rotating electric machine 10 can rotate the rotor 12 by utilizing the saliency of the cylindrical body 31, without providing permanent magnets or windings (conductors) on the rotor 12.

As shown in Figure 4, a recess 51b is provided on the inner peripheral portion 51a (inner peripheral surface) of each rotor steel plate 51. The recess 51b penetrates the rotor steel plate 51 in the axial direction and opens toward the radially inward direction of the shaft 14.

As shown in FIG. 3, the fixing portion 60 has a surface 12m of the shaft 14 and a key 61. The surface 12m is an example of a first clamping portion, and the key 61 is an example of a second clamping portion. The key 61 is also referred to as a clamping member.

Surface 12m is located on one axial side of the cylindrical body 31 (rotor steel plate 51). Surface 12m is aligned with one of the pressure plates 52A of the cylindrical body 31 in the axial direction and is in contact with that pressure plate 52A.

As shown in FIG. 4, multiple keys 61 are provided. The number of keys 61 is the same as the number of poles of the rotor core 50, for example, four. The multiple keys 61 are arranged at intervals in the circumferential direction. As shown in FIGS. 3 and 4, the keys 61 are formed, for example, in a rectangular parallelepiped shape. The keys 61 are inserted into the recesses 12n of the shaft 14 and fixed to the shaft 14 by welding or the like. The keys 61 are located on the other axial side of the cylindrical body 31 (rotor core 50). The keys 61 are axially aligned with the other pressure plate 52B of the cylindrical body 31 and are in contact with the pressure plate 52B. When viewed from the axial direction, the keys 61 are located radially inward of the flux barrier group 53. The keys 61 are located radially inward of the portion of the cylindrical body 31 that has relatively low rigidity (strength) due to the provision of the flux barrier group 53, thereby reinforcing the cylindrical body 31. The key 61 is connected to the surface 12m via the shaft 14, i.e., region 14b, located inside the cylindrical body 31.

The fixing portion 60 secures the multiple rotor steel plates 51 and two pressure plates 52 together by axially sandwiching the cylindrical body 31 (rotor core 50) between the surface 12m and the key 61. This integrates the multiple rotor steel plates 51 and the two pressure plates 52. The fixing portion 60 also positions the cylindrical body 31 axially relative to the shaft 14. Here, the shaft 14 is press-fit into the cylindrical body 31 (rotor core 50). In other words, the cylindrical body 31 (rotor core 50) and the shaft 14 are fitted together by an interference fit.

Also, as shown in FIG. 3, the portion 31c between the surface 12m and the key 61 of the cylindrical body 31 (rotor core 50) is solid. That is, the portion 51c between the surface 12m and the key 61 of each rotor steel plate 51, and the portion 52c between the surface 12m and the key 61 of each retainer plate 52 are solid. In other words, the portion 31c between the surface 12m and the key 61 of the cylindrical body 31 does not have a hole penetrating the cylindrical body 31.

Next, a comparative example will be described. Figure 5 is a cross-sectional view that schematically shows a portion of the rotor 112 of the reluctance rotating electric machine 110 of the comparative example. Figure 6 is a front view that schematically shows the rotor 112 of the reluctance rotating electric machine 110 of the comparative example.

As shown in Figures 5 and 6, the reluctance rotating electric machine 110 of the comparative example differs mainly from the cylindrical body 31 and fixed portion 60 of the embodiment in terms of the cylindrical body 131 and fixed portion 160.

The cylindrical body 131 of the comparative example has a fixing through-hole 131a that passes through the cylindrical body 131 (rotor core 150 and presser plate 152) in the axial direction. The fixing portion 160 has a stud bolt 161 partially inserted into the fixing through-hole 131a and two nuts 162 attached to both ends of the stud bolt 161. The fixing portion 160 secures the rotor core 150 to each other by sandwiching the rotor core 150 between the two nuts 162 connected by the stud bolt 161. In other words, the fixing portion 160 is not provided on the shaft 114. The rotor core 150 is provided with a flux barrier group 153, similar to the rotor core 50.

In the comparative reluctance rotating electric machine 110 with the above configuration, the rotor core 150 has a fixing through-hole 131a, which causes leakage magnetic flux in the rotor core 150. In contrast, in the reluctance rotating electric machine 10 of this embodiment, the fixing portion 60 axially sandwiches the cylindrical body 31 (rotor core 50) between the surface 12m and the key 61, thereby fixing the multiple rotor steel plates 51 and the two presser plates 52 to each other, and the portion 31c of the cylindrical body 31 between the surface 12m and the key 61 does not have a hole that penetrates the rotor core 50. Therefore, the reluctance rotating electric machine 10 of this embodiment suppresses leakage magnetic flux in the cylindrical body 31 compared to the comparative reluctance rotating electric machine 110.

As described above, the reluctance rotating electric machine 10 of this embodiment includes a stator 11 and a rotor 12. A portion of the rotor 12 is located inside the stator 11 and is rotatable around the central axis of rotation Ax. The rotor 12 includes a shaft 14, a rotor core 50, and a fixed portion 60. The shaft 14 extends in the axial direction of the central axis of rotation Ax. The rotor core 50 has a plurality of rotor steel plates 51 that are annular around the central axis of rotation Ax and stacked axially. The fixed portion 60 includes a surface 12m (first clamping portion) and a key 61 (second clamping portion). The surface 12m is provided on the shaft 14 and located on one axial side of the rotor core 50. The key 61 is fixed to the shaft 14, located on the other axial side of the rotor core 50, and connected to the surface 12m via the shaft 14, which is located inside the rotor core 50. The fixing portion 60 secures the multiple rotor steel plates 51 to each other by sandwiching the cylindrical body 31 between the surface 12m and the key 61.

With this configuration, the fixing portion 60 secures the multiple rotor steel plates 51 to one another by clamping the rotor core 50 between the surface 12m (first clamping portion) provided on the shaft 14 and the key 61 (second clamping portion) fixed to the shaft 14. This eliminates the need to provide fixing through-holes in the cylindrical body 31 to secure the multiple rotor steel plates 51 to one another. This prevents leakage flux from occurring in the rotor core 50. This, in turn, improves the power factor and other characteristics of the reluctance rotating electric machine 10.

The first clamping portion is a surface 12m formed on the shaft 14 facing the other axial direction, and the second clamping portion is a key 61 fixed to the shaft 14.

This configuration makes it relatively easy to provide the first and second clamping portions.

Here, the greater the number of poles in the rotor core 50, i.e., the greater the number of flux barrier groups 53, the lower the rigidity of the rotor core 50 and the more likely it is to expand in the axial direction. In contrast, in this embodiment, as described above, the same number of keys 61 as the number of poles in the rotor core 50 is provided. Therefore, according to this embodiment, deformation of the cylindrical body 31 can be suppressed compared to a configuration in which the number of keys 61 is fewer than the number of poles in the rotor core 50.

In addition, the inner peripheral portion 51a of each rotor steel plate 51 is provided with a recess 51b that penetrates the rotor steel plate 51 in the axial direction and opens toward the radially inward direction of the shaft 14. The recesses 51b of multiple rotor steel plates 51 are aligned in the axial direction.

With this configuration, when stacking multiple rotor steel plates 51 in the axial direction, the circumferential positions of the multiple rotor steel plates 51 can be easily aligned by inserting an axially extending jig member into each recess 51b. Furthermore, because the recesses 51b are provided on the inner periphery 51a of the rotor steel plates 51, the recesses 51b can be separated from the magnetic flux. This prevents magnetic flux leakage from occurring in the cylindrical body 31.

Next, a modified example of this embodiment will be described. Figure 7 is a front view that schematically shows the rotor 12 of a reluctance rotating electric machine 10 according to this modified example.

In the modified example shown in Figure 7, the rotor core 50 has six magnetic poles and the fixed portion 60 has six keys 61. In other words, the number of keys 61 is the same as the number of poles on the rotor core 50.

In the above embodiment, an example was shown in which the first clamping portion of the fixing portion 60 was formed on the surface 12m of the shaft 14, but this is not limited to this. For example, the first clamping portion may be a member such as a key fixed to the shaft 14, similar to the second clamping portion (key 61).

While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in a variety of other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

10... reluctance rotating electric machine, 11... stator, 12... rotor, 12m... surface (first clamping portion), 14... shaft, 50... rotor core, 51... rotor steel plate (plate), 51a... inner periphery, 51b... recess, 53... flux barrier group, 53a... flux barrier, 60... fixed portion, 61... key (second clamping portion), Ax... rotation central axis.

Claims (4)

A stator;
a rotor, a portion of which is located inside the stator and which is rotatable around a central axis of rotation;
Equipped with
The rotor is
a shaft extending in the axial direction of the rotation center axis;
a rotor core having a plurality of plates that are annular around the central axis of rotation and stacked on top of each other in the axial direction;
a fixing portion including a first clamping portion provided on the shaft and positioned on one side of the rotor core in the axial direction, and a second clamping portion fixed to the shaft and positioned on the other side of the rotor core in the axial direction, and connected to the first clamping portion via the shaft positioned inside the rotor core, wherein the first clamping portion and the second clamping portion clamp the rotor core to fix the plurality of plates to each other;
and
a plurality of flux barrier groups are provided in the rotor core at intervals in the circumferential direction of the central axis of rotation,
each of the flux barrier groups includes a plurality of flux barriers that are convex toward an inner side in a radial direction of the rotation central axis and are arranged at intervals from each other in the radial direction;
the second clamping portions are provided for each of the flux barrier groups, and when viewed from the axial direction, are positioned radially inward of the flux barrier groups, are aligned radially with the tops of the convex shapes of the flux barriers, and reinforce the rotor core.
Reluctance rotating electric machine. the first clamping portion is a surface formed on the shaft and facing the other side in the axial direction,
The second clamping portion is a key fixed to the shaft.
2. A reluctance rotating electric machine according to claim 1. The number of the second clamping portions is the same as the number of poles of the rotor core.
2. A reluctance rotating electric machine according to claim 1. A recess is provided on an inner peripheral portion of each of the plates, the recess penetrating the plate in the axial direction and opening toward the inside in the radial direction of the shaft,
The recesses of the plurality of plates are aligned in the axial direction.
4. A reluctance rotating electric machine according to claim 1.