Rotor and reluctance motor

Abstract

We provide a rotor for a reluctance motor that suppresses torque ripple. [Solution] The rotor is a rotor for a reluctance motor and comprises a rotor core having a rotating shaft, an inner bore through which the rotating shaft is inserted, a plurality of flux barrier portions arranged at equal pitches in the circumferential direction of the rotor around the inner bore, and a yoke portion provided between adjacent flux barrier portions. Each of the plurality of flux barrier portions has a plurality of flux barriers arranged at intervals in the radial direction of the rotor. The rotor core has an outer diameter correction structure in the yoke portion that corrects variations in the outer diameter of the rotor core when the reluctance motor is in operation.

Description

Technical Field

[0006] , , ,

[0001] The present embodiment of the invention relates to a rotor and a reluctance motor.

Background Art

[0002] A reluctance motor is a motor that rotates by a reluctance torque generated by a magnetic resistance difference inside a rotor without using an excitation source such as a permanent magnet in the rotor. The reluctance motor includes a rotor core formed by laminating a plurality of electromagnetic steel plates.

[0003] In the rotor core 131 of the conventional example shown in FIG. 1, a plurality of slit-shaped flux barriers 141 arranged in the circumferential direction are provided around the inner hole 133. Each of these plurality of flux barriers 141 has a curved shape that approaches the outer peripheral surface of the rotor core 131 from the central portion in the longitudinal direction toward both ends when viewed from the axial direction. The plurality of slit-shaped flux barriers 141 arranged in the circumferential direction constitute a flux barrier group 140. The rotor core 131 has a plurality of flux barrier groups 140 arranged at equal pitches in the radial direction.

[0004] Note that the flux barrier 141 may be a gap, or a metal member or a resin member may be inserted into at least a part of the inside.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Figure 2 shows a portion of the rotor core 131 during operation of a conventional reluctance motor. When the reluctance motor is in operation, centrifugal force acts on the rotor core 131 due to rotation. The flux barrier section 134, where the flux barrier 141 is provided, and the yoke section 135, which is provided between the flux barrier sections 134, have different densities. Therefore, even when the same centrifugal force acts, the flux barrier section 134 and the yoke section 135 deform at different rates. Due to the rotation during operation, the flux barrier section 134, which has a large degree of freedom of deformation, bulges outward to increase its outer diameter, while the yoke section 135, which has a low degree of freedom of deformation, deforms less than the flux barrier section 134. As a result, variations occur in the outer diameter of the rotor core 131, as shown by D0 in Figure 2. This variation in the outer diameter of the rotor core 131 during rotation causes an imbalance in the gap length between the rotor and the stator. As a result, the electromagnetic force generated between the rotor and stator becomes non-uniform in the circumferential direction, causing the torque ripple to increase.

[0007] Therefore, the present invention provides a rotor with suppressed torque ripple and a reluctance motor. [Means for solving the problem]

[0008] The rotor of this embodiment is a rotor for a reluctance motor and comprises a rotor core having a rotating shaft, an internal bore through which the rotating shaft is inserted, a plurality of flux barrier portions arranged at equal pitches in the circumferential direction of the rotor around the internal bore, and a yoke portion provided between adjacent plurality of flux barrier portions. Each of the plurality of flux barrier portions has a plurality of flux barriers arranged at intervals in the radial direction of the rotor. The rotor core has an outer diameter correction structure in the yoke portion that corrects variations in the outer diameter of the rotor core when the reluctance motor is in operation.

[0009] The reluctance motor of this embodiment includes a rotor core having a rotating shaft, an inner bore through which the rotating shaft is inserted, a plurality of flux barrier portions arranged at equal pitches in the circumferential direction of the rotor around the inner bore, and a yoke portion provided between adjacent flux barrier portions. Each of the plurality of flux barrier portions has a plurality of flux barriers arranged at intervals in the radial direction of the rotor. The rotor core has an outer diameter correction structure in the yoke portion that corrects variations in the outer diameter of the rotor core when the reluctance motor is in operation. [Brief explanation of the drawing]

[0010] [Figure 1] A diagram showing the stationary state of a conventional rotor core, viewed from the axial direction. [Figure 2] This diagram shows the state of a portion of the rotor core during operation, viewed from the axial direction. [Figure 3] A broken perspective view showing the schematic configuration of the reluctance motor of the first embodiment. [Figure 4] A diagram showing a portion of the rotor core of the first embodiment in an axial view while it is stationary. [Figure 5] A diagram showing a portion of the rotor core of the first embodiment in an axial view during operation. [Figure 6] A diagram showing a portion of the rotor core of the second embodiment in an axial view while it is stationary. [Figure 7] A diagram showing a portion of the rotor core of the second embodiment in an axial view during operation. [Figure 8] A diagram showing a portion of the rotor core of the third embodiment in an axial view while it is stationary. [Figure 9] A diagram showing a portion of the rotor core of the third embodiment in an axial view during operation. [Modes for carrying out the invention]

[0011] Hereinafter, reluctance motors and rotors according to multiple embodiments will be described with reference to the drawings. In addition, elements that are substantially the same in multiple embodiments will be denoted by the same reference numerals, and their descriptions will be omitted.

[0012] (First Embodiment) A first embodiment will be described with reference to Figures 3 to 5. As shown in Figure 3, the reluctance motor 1 is a so-called inner rotor type and comprises a housing 10, a stator 20, and a rotor 30. The housing 10 constitutes the outer shell of the reluctance motor 1. The stator 20 is formed in a substantially cylindrical shape and is fitted and fixed to the inner circumferential surface of the housing 10. The rotor 30 is arranged radially inward of the stator 20 and is rotatably mounted relative to the stator 20.

[0013] The housing 10 includes a frame 11, a first bracket 12, and a second bracket 13. The frame 11 is formed in a substantially cylindrical shape. The first bracket 12 and the second bracket 13 are each formed in a generally circular plate shape and close the openings at both ends of the frame 11.

[0014] The stator 20 has a stator core 21 and windings 22. The stator core 21 is formed by laminating multiple electromagnetic steel sheets. The windings 22 are wound around the stator core 21 to form, for example, a three-phase four-pole coil.

[0015] As shown in Figure 3, the rotor 30 has a rotor core 31 and a rotating shaft 32. The rotor core 31 is formed, for example, by laminating multiple electromagnetic steel sheets. Either the rotor core 31 and / or the stator core 21, or both, may be formed by pressure molding of soft magnetic powder such as silicon steel sheet.

[0016] The rotating shaft 32 extends in the axial direction of the rotor 30. The rotating shaft 32 penetrates the inner hole 33, and the rotor core 31 rotates integrally with the rotating shaft 32 about the rotating shaft 32. The central axis of the rotating shaft 32, that is, the rotation center axis A of the rotor 30, passes through the centers of the stator 20 and the rotor 30. Both ends of the rotating shaft 32 penetrate the respective brackets 12 and 13 and are rotatably fixed. Hereinafter, the direction in which the rotation center axis A extends is referred to as the axial direction, the circumferential direction of the rotor 30 is referred to as the circumferential direction, and the direction orthogonal to the axial direction and the circumferential direction is referred to as the radial direction.

[0017] As partially shown in FIG. 4, the rotor core 31 has a plurality of, in this case four, flux barrier portions 34 and a plurality of, in this case four, yoke portions 35. The flux barrier portions 34 are arranged at equal pitches in the circumferential direction around the inner hole 33, in this case every 90°. Each flux barrier portion 34 has a plurality of flux barriers 41 arranged at intervals in the radial direction. The plurality of flux barriers 41 arranged in each flux barrier portion 34 constitute a flux barrier group 40. The yoke portion 35 is a portion where no flux barrier 41 is formed between adjacent flux barrier portions 34. In other words, the yoke portion 35 is a portion between the flux barrier 41 arranged most radially inward in one flux barrier group 40 and the flux barrier 41 arranged most radially inward in the adjacent flux barrier group 40.

[0018] The rotor core 31 has an outer diameter correction structure. The outer diameter correction structure is a structure that corrects the variation in the outer diameter of the rotor core 31 during the operation of the reluctance motor 1. That is, the outer diameter correction structure has a function of making the outer diameter of the yoke portion 35 during the operation of the reluctance motor 1 approach the outer diameter of the flux barrier portion 34 during the operation of the reluctance motor 1. The outer diameter correction structure is designed such that the variation in the outer shape of the rotor core 31 during the operation of the reluctance motor 1 caused by the flux barrier group 40 is within a predetermined range. For example, during the operation of the reluctance motor 1, the outer diameter difference D generated between the outer diameter of the flux barrier portion 34 and the outer diameter of the yoke portion 35 is within a predetermined range. The predetermined range of the outer diameter difference D can be, for example, within 5% or less, 2.5% or less, or 1% or less of the radius of the rotor core 31.

[0019] As shown in FIGS. 4 and 5, the rotor core 31 of the present embodiment has a protrusion 50 as an outer diameter correction structure. The protrusion 50 is formed by protruding at least a part of the outer peripheral portion of the yoke portion 35 outward in the radial direction. The protruding length L1 from the outer peripheral portion of the yoke portion 35 when the protrusion 50 is not present, that is, the root portion of the protrusion 50, can be set within, for example, a range of 1 / 4 or less of the gap length between the rotor 30 and the stator 20.

[0020] During the operation of the reluctance motor 1, the yoke portion 35 is difficult to bulge outward in the radial direction. However, since the protrusion 50 originally protrudes outward in the radial direction, as shown in FIG. 5, the outer diameter difference D generated between the outer diameter of the flux barrier portion 34 and the outer diameter of the yoke portion 35 during operation can be reduced.

[0021] The shape of the projection 50 can be formed, for example, as an arc shape with a radius smaller than the radius of the rotor core 31. The projection 50 is provided in the central part of the yoke portion 35 in the circumferential direction. That is, the projection 50 is provided at positions that are equally spaced from the flux barrier 41 that is located radially inward among the adjacent flux barrier groups 40 on one side, and from the flux barrier 41 that is located radially inward among the adjacent flux barrier groups 40 on the other side. This makes the outer diameter of the rotor core 31 more uniform during operation and further contributes to improving torque ripple.

[0022] The rotor 30 for the reluctance motor 1 of this embodiment, as described above, comprises a rotating shaft 32 and a rotor core 31. The rotor core 31 has an inner hole 33 through which the rotating shaft 32 is inserted, a plurality of flux barrier portions 34 arranged at equal pitches in the circumferential direction of the rotor 30 around the inner hole 33, and a yoke portion 35 provided between adjacent flux barrier portions 34. The rotor core 31 has a projection 50 on the yoke portion 35 as an outer diameter correction structure to correct variations in the outer diameter of the rotor core 31 when the reluctance motor 1 is in operation.

[0023] According to this, variations in the gap length between the rotor 30 and the stator 20 during the operation of the reluctance motor 1 can be suppressed. Therefore, the electromagnetic force generated between the rotor 30 and the stator 20 during the operation of the reluctance motor 1 can be made more uniform in the circumferential direction, thereby suppressing the occurrence of torque ripple.

[0024] The rotor 30 has an outer diameter correction structure, which includes a projection 50 that, in a stationary state, extends at least a portion of the outer circumference of the yoke portion 35 radially outward from the rotor 30.

[0025] According to this, by increasing the outer diameter of the yoke portion 35 in advance when stationary, the difference in outer diameter between the outer diameter of the bulging flux barrier portion 34 and the outer diameter of the yoke portion 35 can be suppressed during operation. Therefore, variations in the gap length between the rotor 30 and the stator 20 during operation of the reluctance motor 1 can be suppressed, and the occurrence of torque ripple can be suppressed.

[0026] The reluctance motor 1 of this embodiment comprises a rotor 30 having a rotating shaft 32 and a rotor core 31. The rotor core 31 has an inner hole 33 through which the rotating shaft 32 is inserted, a plurality of flux barrier portions 34 arranged at equal pitches in the circumferential direction of the rotor 30 around the inner hole 33, and a yoke portion 35 provided between adjacent flux barrier portions 34. The rotor core 31 has a projection 50 on the yoke portion 35 as an outer diameter correction structure to correct variations in the outer diameter when the reluctance motor 1 is in operation.

[0027] According to this, a reluctance motor 1 is provided that suppresses variations in the gap length between the rotor 30 and the stator 20, thereby suppressing the occurrence of torque ripple.

[0028] (Second Embodiment) A second embodiment will be described with reference to Figures 6 and 7. The rotor 30 of this embodiment has a through-hole 60 as an outer diameter correction structure. The through-hole 60 is formed by penetrating a part of the yoke portion 35 along the axial direction. Because the density of the yoke portion 35 is reduced by the through-hole 60, the yoke portion 35 becomes more susceptible to deformation due to centrifugal force when the rotor core 31 rotates. As shown in Figure 7, the outer diameter difference D during operation of the reluctance motor 1 can be made smaller than the outer diameter difference D0 of the conventional example.

[0029] The through-port 60 may have a flattened shape with a longitudinal direction in the radial direction, or it may be annular. In this embodiment, the through-port 60 has a flattened shape with a longitudinal direction in the radial direction. By making the through-port 60 elongated in the radial direction, it is possible to suppress the disruption and non-uniformity of the magnetic flux flow in the yoke portion 35 due to the presence of the through-port 60.

[0030] The radial length of the through-section 60 can be set to, for example, 70%, within a range of 50% to 75% of the radial length of the yoke section 35. The circumferential length of the through-section 60 can be set to, for example, 20%, within a range of 15% to 25% of the circumferential length of the yoke section 35.

[0031] Furthermore, the through-section 60 is formed such that its width in the circumferential direction (i.e., the shorter side) increases towards the radially inward direction, and decreases towards the radially outward direction. In other words, the edge 61 of the through-section 60 is formed to conform to the curved shape of the adjacent flux barrier 41. As a result, the width of the flesh portion of the yoke section 35, i.e., the distance from the flux barrier 41 to the through-section 60, is kept to a constant degree over approximately the entire length of the through-section 60. This makes the yoke section 35 more susceptible to deformation under centrifugal force.

[0032] According to the embodiment described above, the rotor 30 has a through portion 60 that penetrates the yoke portion 35 along the axial direction of the rotating shaft 32 as an outer diameter correction structure.

[0033] According to this, the through-hole 60 increases the degree of freedom of deformation of the yoke portion 35, so the outer diameter of the yoke portion 35 can be increased when the reluctance motor 1 is in operation. Therefore, variations in the gap length between the rotor 30 and the stator 20 when the reluctance motor 1 is in operation can be suppressed. Consequently, the electromagnetic force generated between the rotor 30 and the stator 20 when the reluctance motor 1 is in operation can be made more uniform in the circumferential direction, thus suppressing the occurrence of torque ripple. In this case, since there is no difference in outer diameter between the flux barrier portion 34 and the yoke portion 35 when the reluctance motor is starting up, i.e., when it is rotating at low speed, torque ripple at startup can be suppressed.

[0034] According to this embodiment, the multiple flux barriers 41 are formed in a curved shape that approaches the outer circumferential surface of the rotor 30 from the center in the longitudinal direction towards both ends. The through-hole 60 is formed in a flattened shape with its longitudinal direction in the radial direction of the rotor 30. The longitudinal edge 61 of the through-hole 60 extends along the longitudinal edge of the flux barrier 41 that is closest to the through-hole 60 among the multiple flux barriers 41.

[0035] This makes the yoke portion 35 more easily deformable. Therefore, torque ripple is further improved.

[0036] (Third embodiment) A third embodiment will be described with reference to Figures 8 and 9. The rotor core 31 of this embodiment has both a projection 50 and a through-hole 60 as an outer diameter correction structure. In this case, even if the projection length L2 of the projection 50 is set shorter than the projection length L1 of the projection 50 of the first embodiment, an outer diameter difference D equivalent to that of the rotor 30 of the first embodiment can be obtained. In this case, at low speed rotation... Since the difference in outer diameter between the yoke portion 35 and the flux barrier portion 34 can be made relatively small, the generation of torque ripple during the startup of the reluctance motor 1 can be suppressed.

[0037] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0038] 1…Reluctance motor, 30…Rotor, 31…Rotor core, 32…Rotating shaft, 33…Inner bore, 34…Flux barrier section, 35…Yoke section, 41…Flux barrier, 50…Protrusion (outer diameter correction structure), 60…Through section (outer diameter correction structure), 61…Edge section

Claims

1. A rotor for a reluctance motor, The axis of rotation and The rotor core comprises an inner bore through which the rotating shaft is inserted, a plurality of flux barrier portions arranged at equal pitches in the circumferential direction of the rotor around the inner bore, and a yoke portion provided between adjacent plurality of flux barrier portions. Each of the plurality of flux barrier sections has a plurality of flux barriers arranged at intervals in the radial direction of the rotor, The rotor core has an outer diameter correction structure in the yoke portion that corrects variations in the outer diameter of the rotor core when the reluctance motor is in operation. Rotor.

2. The outer diameter correction structure has a projection that, in a stationary state, extends at least a portion of the outer circumference of the yoke outward in the radial direction of the rotor. The rotor according to claim 1.

3. The outer diameter correction structure has a through portion that penetrates the yoke portion along the axial direction of the rotation shaft, The rotor according to claim 1 or 2.

4. The plurality of flux barriers are formed in a curved shape that approaches the outer circumferential surface of the rotor from the central part in the longitudinal direction towards both ends. The through portion is formed in a flattened shape having a longitudinal direction in the radial direction of the rotor, The longitudinal edge of the penetration extends along the longitudinal edge of the flux barrier closest to the penetration among the plurality of flux barriers. The rotor according to claim 3.

5. It is a reluctance motor, The axis of rotation and The rotor comprises a rotor core having an inner bore through which the rotating shaft is inserted, a plurality of flux barrier portions arranged at equal pitches in the circumferential direction around the inner bore, and a yoke portion provided between adjacent plurality of flux barrier portions, Each of the plurality of flux barrier sections has a plurality of flux barriers arranged at intervals in the radial direction of the rotor, The rotor core has an outer diameter correction structure in the yoke portion that corrects variations in the outer diameter of the rotor core when the reluctance motor is in operation. Reluctance motor.

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