Rotor and motor

Abstract

The present invention provides a rotor capable of improving torque during startup, and a motor equipped with such a rotor. [Solution] The rotor 10 includes a rotor core 20 having a plurality of through holes that penetrate in the axial direction, a plurality of conductor portions 19 extending along the axial direction and arranged in the circumferential direction, and a pair of end rings connected to the plurality of conductor portions on one and the other axial side of the rotor core, respectively. Each of the plurality of through holes includes a plurality of slots 40 in which the conductor portions are arranged, and a plurality of flux barriers 31, 32, 33 located radially inward from the plurality of slots and constituting a flux barrier group 30 for each q-axis of the rotor. The plurality of slots includes a plurality of first slots 41 located radially outward from the flux barrier group. The cross-sectional area of ​​the plurality of first slots decreases as it approaches the q-axis in the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a rotor and a motor.

Background Art

[0002] The reluctance motor has no copper loss in the rotor and high driving efficiency compared with the induction motor. However, the reluctance motor has disadvantages in that the starting torque is low and an expensive control device is required. In order to compensate for the disadvantages of the reluctance motor, a motor having the characteristics of both the reluctance motor and the induction motor is known. For example, Patent Document 1 discloses a motor in which a cage-type secondary conductor is combined with the outer peripheral portion of the rotor of a reluctance motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a motor, in order to generate reluctance torque, the iron core of the rotor has salient poles, and there are differences in the ease of magnetic flux passage depending on the circumferential position on the rotor surface. Therefore, when the rotating magnetic field generated by the stator is not synchronized with the rotation of the rotor, there is a moment when the salient pole portion generates a negative reluctance torque, and there is a problem that the driving efficiency of the motor particularly at the start is reduced.

[0005] In view of the above circumstances, an object of the present invention is to provide a rotor capable of improving the starting torque and a motor including such a rotor.

Means for Solving the Problems

[0006] One embodiment of the rotor of the present invention is a rotor rotatable about a central axis as the axis of rotation. The rotor has a rotor core which is cylindrical with a central axis coinciding with the central axis and has a plurality of through holes that penetrate in the axial direction, a plurality of conductor portions which extend along the axial direction and are arranged in the circumferential direction, and a pair of end rings which are connected to the plurality of conductor portions on one and the other axial side of the rotor core, respectively. The plurality of through holes each include a plurality of slots in which the conductor portions are arranged, and a plurality of flux barriers which are located radially inward from the plurality of slots and constitute a flux barrier group for each q axis of the rotor. The plurality of flux barriers of the flux barrier group are arranged on the q axis and each extends in a direction transverse to the q axis. The plurality of slots include a plurality of first slots which are located radially outward from the flux barrier group. The cross-sectional area of ​​the plurality of first slots which are located radially outward from one of the flux barrier groups decreases as it approaches the q axis in the circumferential direction.

[0007] One embodiment of the motor of the present invention comprises the rotor described above and a stator surrounding the rotor from the radially outer side. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a rotor that can improve torque during startup, and a motor equipped with such a rotor. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view of a motor according to one embodiment. [Figure 2] Figure 2 is a cross-sectional view of a rotor according to one embodiment along the line II-II in Figure 1. [Figure 3] Figure 3 is a partial cross-sectional view of a rotor according to one embodiment. [Figure 4] Figure 4 is a partial cross-sectional view of a modified rotor. [Modes for carrying out the invention]

[0010] Each figure shows the Z-axis as appropriate. The central axis J shown in each figure is parallel to the Z-axis direction. In the following explanation, the direction parallel to the axial direction of the central axis J, i.e., the vertical direction, will simply be referred to as the "axial direction," the radial direction centered on the central axis J will simply be referred to as the "radial direction," and the circumferential direction centered on the central axis J will simply be referred to as the "circumferential direction."

[0011] Figure 1 is a schematic cross-sectional view of a motor according to one embodiment. The motor 100 in this embodiment is an inner rotor type motor. Furthermore, the motor 100 in this embodiment is a DOL SynRM (Direct-On-Line Synchronous Reluctance Motor).

[0012] The motor 100 comprises a housing 2, a rotor 10, a stator 3, a bearing holder 4, and bearings 5a and 5b. The housing 2 houses the rotor 10, the stator 3, the bearing holder 4, and the bearings 5a and 5b. The bottom of the housing 2 holds bearing 5b. The bearing holder 4 holds bearing 5a. Bearings 5a and 5b are, for example, ball bearings.

[0013] The stator 3 surrounds the rotor 10 from the radially outer side. The stator 3 has a stator core 3a, an insulator 3d, and a plurality of coils 3e. The stator core 3a has a core back 3b and a plurality of teeth 3c. The core back 3b is an annular shape centered on the central axis J. The plurality of teeth 3c extend radially inward from the core back 3b. Although not shown in the figure, the plurality of teeth 3c are arranged at equal intervals along the circumference. The plurality of coils 3e are mounted on the stator core 3a via the insulator 3d. Different phase alternating currents are passed through each of the plurality of coils 3e. As a result, the stator 3 forms a rotating magnetic field that rotates around the central axis J on the radially inward side of the stator 3.

[0014] The rotor 10 is positioned radially inward of the stator 3. The rotor 10 is rotatable about its central axis J. The rotor 10 comprises a shaft 21, a rotor core 20, a plurality of magnets 11, 12, and 13 arranged within the rotor core 20, a plurality of conductive parts 19, and a pair of end rings 18. Note that in Figure 1, the shape and arrangement of the plurality of magnets 11, 12, and 13 are schematic for the sake of simplifying the drawing and do not accurately represent their actual shape and arrangement.

[0015] The shaft 21 extends axially along the central axis J. The shaft 21 is cylindrical in shape, with its central axis coinciding with the central axis J. The shaft 21 is supported by bearings 5a and 5b so as to be rotatable around the central axis J.

[0016] The conductor portion 19 and the end ring 18 are made of a metallic material with excellent conductivity. The conductor portion 19 extends along the axial direction. The conductor portion 19 penetrates the slot 40 in the axial direction. One end of the conductor portion 19 and the other end are connected to the respective end rings 18. The end rings 18 are annular in shape, with their central axis coinciding with the central axis line J. One of the pair of end rings 18 is positioned on one axial side of the rotor core 20. The other end ring is positioned on the other axial side of the rotor core 20. The pair of end rings 18 are connected to multiple conductor portions 19 on one and the other axial side of the rotor core 20, respectively.

[0017] The rotor core 20 is made of a magnetic material. The rotor core 20 extends along the axial direction. The rotor core 20 is cylindrical in shape, with its central axis coinciding with the central axis line J. Although not shown in the illustration, the rotor core 20 is constructed, for example, by laminating multiple electromagnetic steel sheets in the axial direction.

[0018] Figure 2 is a cross-sectional view of the rotor 10 along the line II-II in Figure 1. The rotor core 20 is provided with a plurality of through holes 20h. The plurality of through holes 20h penetrate the rotor core 20 in the axial direction. The plurality of through holes 20h include one central hole 20c, a plurality of slots 40, and a plurality of flux barriers 31, 32, 33.

[0019] When viewed from the axial direction, the central hole 20c has a circular shape centered on the central axis J. A shaft 21 is passed through the central hole 20c. The shaft 21 is fixed within the central hole 20c by, for example, press-fitting or the like. That is, the rotor core 20 is fixed to the outer peripheral surface of the shaft 21.

[0020] FIG. 2 shows a part of the q-axis Lq and the d-axis Ld of the rotor 10. The d-axis Ld is a virtual straight line connecting the position on the outer peripheral surface 20f of the rotor 10 where magnetic flux most easily passes through and the central axis J when viewed from the axial direction. The q-axis Lq is a virtual straight line connecting a point located midway between two adjacent d-axes Ld in the circumferential direction and the central axis J. The midpoint between two adjacent d-axes Ld in the circumferential direction usually coincides with the point where magnetic flux least easily passes through the rotor 10. The rotor 10 has magnetic anisotropy in the q-axis Lq direction and the d-axis Ld direction.

[0021] The rotor 10 of the present embodiment has four d-axes Ld arranged at equal intervals in the circumferential direction and four q-axes Lq arranged at equal intervals in the circumferential direction. The q-axis Lq is arranged between the d-axes Ld in the circumferential direction. The d-axis Ld coincides with the magnetic pole of the rotor 10. That is, the rotor 10 of the present embodiment is four-pole.

[0022] In the present embodiment, the plurality of flux barriers 31, 32, 33 are classified into four groups. Here, each group of the flux barriers 31, 32, 33 is referred to as a flux barrier group 30. The rotor core 20 of the present embodiment is provided with four groups of flux barrier groups 30.

[0023] The flux barrier group 30 is arranged on the q-axis Lq. That is, multiple flux barriers 31, 32, and 33 constitute a flux barrier group 30 for each q-axis Lq. Multiple flux barriers 31, 32, and 33 belonging to the same flux barrier group 30 are arranged on a single q-axis Lq. In addition, a d-axis Ld is arranged between adjacent flux barrier groups 30 in the circumferential direction.

[0024] A single flux barrier group 30 comprises three flux barriers 31, 32, and 33. In the following description, the three flux barriers belonging to a single flux barrier group 30 will be referred to as the first flux barrier 31, the second flux barrier 32, and the third flux barrier (outer end flux barrier) 33. That is, the multiple flux barriers 31, 32, and 33 of the flux barrier group 30 include the first flux barrier 31, the second flux barrier 32, and the third flux barrier 33.

[0025] The first flux barrier 31, the second flux barrier 32, and the third flux barrier 33 are arranged in this order from the radially inner to the radially outer. The first flux barrier 31, the second flux barrier 32, and the third flux barrier 33 are arranged radially along the q axis Lq. The second flux barrier 32 is located radially outside the first flux barrier 31. The multiple third flux barriers 33 are located radially outside the second flux barrier 32. In this embodiment, in each flux barrier group 30, the first flux barrier 31, the second flux barrier 32, and the third flux barrier 33 each have a shape that is symmetrical with respect to the q axis Lq.

[0026] In this embodiment, a case in which three flux barriers 31, 32, and 33 are provided in one flux barrier group 30 has been described. However, the number of flux barriers 31, 32, and 33 included in one flux barrier group 30 is not limited to this embodiment. Furthermore, the shape of each flux barrier 31, 32, and 33 is not limited to this embodiment.

[0027] Figure 3 is a magnified view of a portion of Figure 2. As shown in Figure 3, the multiple flux barriers 31, 32, and 33 of the flux barrier group 30 are aligned on the q-axis Lq and each extends in a direction transverse to the q-axis Lq.

[0028] The first flux barrier 31 is the inner end flux barrier, positioned furthest in the radial direction from the multiple flux barriers 31, 32, and 33 of the flux barrier group 30. The first flux barrier 31 has a larger circumferential dimension than the second flux barrier 32 and the third flux barrier 33. The first flux barrier 31 has a first magnet housing portion 31b that extends linearly in a direction transverse to the q-axis Lq, and first flux barrier ends (ends) 31a that are connected to both sides of the first magnet housing portion 31b in the circumferential direction. The pair of first flux barrier ends 31a each extend radially outward as they move outward in the circumferential direction.

[0029] The second flux barrier 32 is positioned adjacent to the first flux barrier 31 on its radially outer side. The second flux barrier 32 has a larger circumferential dimension than the third flux barrier 33. The second flux barrier 32 has a second magnet housing portion 32b that extends linearly in a direction transverse to the q-axis Lq, and second flux barrier ends 32a that are connected to the second magnet housing portion 32b on both sides in the circumferential direction.

[0030] The third flux barrier 33 is positioned adjacent to the second flux barrier 32 on its radially outer side. The third flux barrier 33 is the outermost flux barrier among the multiple flux barriers 31, 32, and 33 of the flux barrier group 30, positioned on the radially outermost side. The third flux barrier 33 has a third magnet housing portion 33b that extends linearly in a direction transverse to the q-axis Lq, and third flux barrier ends 33a that are connected to the third magnet housing portion 33b on both sides in the circumferential direction.

[0031] In this embodiment, magnets 11, 12, and 13 are arranged inside each of the flux barriers 31, 32, and 33. The rotor 10 does not necessarily have magnets. Also, the magnets may be arranged inside only one or two of the three flux barriers. Examples of magnets 11, 12, and 13 include ferrite magnets, neodymium magnets, or samarium iron cobalt magnets.

[0032] Magnets 11, 12, and 13 are arranged on the q-axis Lq. Each of the magnets 11, 12, and 13 is plate-shaped with its radial direction as its thickness. In the following description, when distinguishing between the multiple magnets 11, 12, and 13, the one placed inside the first flux barrier 31 will be called the first magnet 11, the one placed inside the second flux barrier 32 will be called the second magnet 12, and the one placed inside the third flux barrier 33 will be called the third magnet 13.

[0033] In this embodiment, the first magnet 11, the second magnet 12, and the third magnet 13 are rectangular in shape, with their longitudinal direction perpendicular to the radial direction when viewed from the axial direction. In this embodiment, the circumferential dimension of the first magnet 11 and the circumferential dimension of the second magnet 12 are approximately equal. The circumferential dimension of the third magnet 13 is smaller than the circumferential dimensions of the first magnet 11 and the second magnet 12.

[0034] The first magnet 11 is positioned in the first magnet housing 31b. The radially outward-facing surface of the first magnet 11 faces and preferably contacts the radially inward-facing surface of the first magnet housing 31b.

[0035] The second magnet 12 is positioned in the second magnet housing 32b. The radially outward-facing surface of the second magnet 12 faces the radially inward-facing surface of the second magnet housing 32b, and preferably makes contact with it.

[0036] The third magnet 13 is positioned in the third magnet housing 33b. The radially outward-facing surface of the third magnet 13 faces and preferably contacts the radially inward-facing surface of the third magnet housing 33b. The radially inward-facing surface of the third magnet 13 faces and preferably contacts the radially outward-facing surface of the third magnet housing 33b.

[0037] The multiple slots 40 are located radially outward from the multiple flux barriers 31, 32, and 33. The multiple slots 40 are arranged in an annular shape along the outer circumferential surface 20f of the rotor core 20. Each slot 40 also extends radially. The multiple slots 40 are arranged at equal intervals in the circumferential direction.

[0038] In this context, "the slots 40 are arranged at equal intervals in the circumferential direction" means that the distance between the circumferential centers of adjacent slots 40 is constant in relation to all adjacent slots 40. Therefore, the distance between adjacent slots 40 in the circumferential direction does not necessarily have to be constant in relation to all adjacent slots 40.

[0039] A conductor portion 19 is placed inside each slot 40. The conductor portion 19 is formed, for example, by pouring molten metal into the slot 40 and allowing it to solidify. Therefore, the cross-sectional shape of the conductor portion 19 in a plane perpendicular to the axial direction is approximately equal to the cross-sectional shape of the slot 40 in a plane perpendicular to the axial direction. Alternatively, conductor portions 19 that have been pre-formed to have the same cross-sectional shape as each slot 40 may be inserted into the slots 40.

[0040] In the rotor 10 of this embodiment, the conductor portion 19 and the end ring 18 constitute a squirrel-cage secondary conductor. As a result, an induced electromotive force is generated in the conductor portion 19 by the action of the rotating magnetic field. Furthermore, as the conductor portion 19 crosses the rotating magnetic flux, a Lorentz force is generated in the conductor portion 19, and torque is generated in the rotor 10. That is, from the time the rotor 10 starts moving until it reaches synchronous speed, the conductor portion 19 generates torque in the rotor 10 due to the Lorentz force.

[0041] Furthermore, in this embodiment, multiple flux barriers 31, 32, and 33 are located radially inward from the multiple slots 40. Due to the action of the multiple flux barriers 31, 32, and 33, the magnetic flux is concentrated along the q-axis Lq inside the rotor core 20. As a result, the rotor 10 can obtain sufficient reluctance torque and rotate in synchronization with the synchronous speed.

[0042] In other words, according to this embodiment, the motor 100 is driven as an induction motor when starting up to ensure sufficient torque at startup, and then driven as a highly efficient reluctance motor after the rotational speed of the rotor 10 is synchronized with the rotational magnetic field. In the following description, the driving state in which the rotational speed of the rotor 10 is lower than the rotational speed of the rotating magnetic flux will be simply called the "starting state," and the driving state in which the rotational speed of the rotor 10 is synchronized with the rotational speed of the rotating magnetic field will be called the "steady state."

[0043] In this embodiment, the multiple slots 40 are arranged at equal intervals in the circumferential direction. Therefore, the multiple conductive parts 19 arranged within each slot 40 are also arranged at equal intervals in the circumferential direction. This makes it possible to make the circumferential distribution of the Lorentz force generated on the rotor 10 in the starting state more uniform. As a result, the rotation of the rotor 10 in the starting state can be stabilized, the rotational efficiency of the rotor 10 in the starting state can be increased, and vibrations of the rotor 10 in the starting state can be suppressed.

[0044] In this embodiment, the slots 40 extend radially. Therefore, multiple slots 40 can be arranged at high density in the circumferential direction while ensuring a large cross-sectional area of ​​the slots 40. This also allows for a larger cross-sectional area of ​​the conductor portion 19, thereby reducing the electrical resistance generated in the conductor portion 19. As a result, the current induced in the conductor portion 19 during motor 100 startup increases, and the torque of motor 100 in the starting state can be increased.

[0045] In this specification, the "cross-sectional area" of the slot 40 and the conductor portion 19 refers to the area of ​​the cross-section obtained by virtually cutting the slot 40 and the conductor portion 19 with a plane perpendicular to the axial direction.

[0046] The multiple slots 40 in this embodiment include multiple first slots 41 and multiple second slots 42. That is, the rotor core 20 is provided with multiple first slots 41 and multiple second slots 42.

[0047] Multiple first slots 41 are located radially outward of the flux barrier group 30. In this embodiment, nine first slots 41 are provided radially outward of one flux barrier group 30. Furthermore, as described above, the rotor core 20 is provided with four groups of flux barrier groups 30. Therefore, the rotor core 20 of this embodiment is provided with 36 first slots 41.

[0048] On the other hand, the second slot 42 is located on the d-axis Ld. In this embodiment, the rotor 10 is provided with four d-axis Ld. Therefore, the rotor core 20 is provided with four second slots 42.

[0049] In this embodiment, one of the nine first slots 41 located radially outward of one flux barrier group 30 is positioned on the d-axis Ld. Furthermore, the nine first slots 41 located radially outward of one flux barrier group 30 are arranged symmetrically with respect to the d-axis Ld.

[0050] The multiple first slots 41 each consist of one slot 41a located on the d-axis Ld, and multiple slots 41b, 41c, 41d, and 41e arranged in a direction away from the d-axis Ld in the circumferential direction. These multiple slots 41b, 41c, 41d, and slot 41e are provided in pairs symmetrically with respect to the q-axis Lq as the reference line.

[0051] In this embodiment, the cross-sectional areas of the multiple first slots 41 located radially outward of one flux barrier group 30 decrease as they approach the q-axis Lq in the circumferential direction. More specifically, the cross-sectional area of ​​slot 41d is smaller than that of slot 41e. The cross-sectional area of ​​slot 41c is smaller than that of slot 41d. The cross-sectional area of ​​slot 41b is smaller than that of slot 41c. The cross-sectional area of ​​slot 41a is smaller than that of slot 41b. That is, among the multiple first slots 41, slot 41a located on the q-axis Lq has the smallest cross-sectional area.

[0052] In the starting state, the rotational speed of the rotor 10 has not yet reached the synchronous speed. Therefore, the position of the rotating magnetic flux within the rotor core 20 in the starting state is constantly changing. Here, as the portion with a large magnetic flux density approaches the convex pole portion (d-axis Ld) of the rotor 10, the magnetic flux is more likely to flow into the convex pole portion. This means that a torque is generated in the opposite direction to the rotational direction of the rotating magnetic field. However, in this embodiment, the rotor 10 has a larger cross-sectional area of ​​the first slot 41 near the d-axis Ld compared to the portion near the q-axis Lq. Therefore, when the portion with a high magnetic flux density of the rotating magnetic field approaches the d-axis Ld, a large induced current flows in the conductor portion 19. Since this induced current is in the same direction as the rotational direction of the rotating magnetic field, it can cancel out the reverse torque generated by the convex pole portion. This reduces torque pulsation in the starting state and improves the efficiency of the motor 100 in the starting state.

[0053] According to this embodiment, the cross-sectional area of ​​the multiple first slots 41 increases as it approaches the d-axis Ld. In other words, the cross-sectional area of ​​the multiple first slots 41 decreases as it approaches the q-axis Lq. Therefore, it is possible to suppress torque fluctuations of the rotor 10 in the starting state and stabilize the rotation, while increasing the driving efficiency of the motor 100 in the steady state.

[0054] Here, as shown in Figure 3, we assume two imaginary lines L1 and L2 located between the d-axis Ld and the q-axis Lq. The two imaginary lines L1 and L2 extend radially from the central axis J. Also, the two imaginary lines L1 and L2 divide the space between the d-axis Ld and the q-axis Lq into three equal parts in the circumferential direction. Of the two imaginary lines L1 and L2, the one located on the q-axis Lq side is designated as the first imaginary line L1, and the other one located on the d-axis Ld side is designated as the second imaginary line L2.

[0055] In this embodiment, it is preferable that the cross-sectional area of ​​slot 41c, which is closest to the first virtual line L1 or is located on the first virtual line L1, is between 0.9 and 1.1 times the cross-sectional area of ​​the second slot 42. Furthermore, it is preferable that the cross-sectional area of ​​slot 41d, which is closest to the second virtual line L2 or is located on the second virtual line L2, is between 1.5 and 2.0 times the cross-sectional area of ​​the second slot 42. According to this embodiment, by distributing the cross-sectional areas of the multiple first slots 41 in this way, the above-mentioned effects can be enhanced. That is, according to this embodiment, it becomes possible to flow a larger induced current in the conductor portion 19 in the first slot 41 near the d axis Ld during startup.

[0056] In this embodiment, the rotor core 20 does not overlap with either of the first slots 41. However, the first and second virtual lines L1 and L2 may overlap with either of the first slots 41.

[0057] In this embodiment, the cross-sectional area of ​​the slot 41a located on the q-axis Lq is preferably 0.8 times or more and 1.0 times or less the cross-sectional area of ​​the second slot 42 located on the d-axis Ld. That is, the cross-sectional area of ​​the second slot 42 is smaller than that of the adjacent first slot 41e and is about the same as, or slightly larger than, that of the first slot 41a located on the q-axis Lq. With this configuration, a large induced current is generated in the conductor near the d-axis Ld during the starting state, while suppressing a decrease in the convex polarity of the rotor core 20, thereby increasing the driving efficiency of the motor 100 in the steady state.

[0058] In this embodiment, the distance from the outer peripheral surface 20f of the rotor core 20 to the radial inner end of the slot 40 is called the inner end distance. More specifically, the inner end distance of slot 41a is defined as the first inner end distance Sp1, the inner end distance of slot 41b as the second inner end distance Sp2, the inner end distance of slot 41c as the third inner end distance Sp3, the inner end distance of slot 41d as the fourth inner end distance Sp4, and the inner end distance of slot 41e as the fifth inner end distance Sp5.

[0059] In this embodiment, the inner end distances Sp1, Sp2, Sp3, Sp4, and Sp5 of the multiple first slots 41 located radially outward of one flux barrier group 30 decrease as they approach the q-axis Lq in the circumferential direction. Therefore, the fifth inner end distance Sp5 is smaller than the fourth inner end distance Sp4. The fourth inner end distance Sp4 is smaller than the third inner end distance Sp3. The third inner end distance Sp3 is smaller than the second inner end distance Sp2. The second inner end distance Sp2 is smaller than the first inner end distance Sp1. Therefore, the slot 41a located on the q-axis Lq has the smallest inner end distance among the multiple first slots 41.

[0060] According to this embodiment, it is possible to easily form a magnetic flux around the first slot 41 near the d-axis Ld in the starting state, while also making it easier to secure reluctance torque in the steady state. As a result, it is possible to configure a motor 100 that stabilizes the rotation of the rotor 10 in the starting state while having excellent driving efficiency in the steady state.

[0061] In this embodiment, among the multiple first slots 41 located radially outward of one flux barrier group 30, the first slot 41 located at the circumferential end is called the circumferential end slot 41e. That is, the multiple first slots 41 include the circumferential end slot 41e that is located furthest towards the d-axis Ld in the circumferential direction.

[0062] In this embodiment, the radially inward end portion 41ea of ​​the peripheral end slot 41e extends radially inward beyond the third flux barrier 33. According to the peripheral end slot 41e of this embodiment, it is possible to narrow the width of the slot 41 near the d axis Ld while securing the cross-sectional area of ​​the conductor portion 16 within the slot 41e. This makes it possible to further reduce the reluctance near the d axis Ld, thereby increasing the reluctance torque in the steady state and further improving the efficiency of the motor 100.

[0063] In this embodiment, among the multiple first slots 41, not only the circumferential end slot 41e but also the slot 41d adjacent to the circumferential end slot 41e may have their radially inward end 41da extend radially inward beyond the third flux barrier 33. This can further improve the reluctance torque.

[0064] In this embodiment, the rotor core 20 is provided with a second slot 42 located on the d-axis Ld. Therefore, the rotor 10 also has a conductive portion 19 on the d-axis Ld. This makes it possible to suppress torque pulsation in the starting state while improving reluctance torque in the steady state. However, if the cross-sectional area of ​​the second slot 42 on the d-axis Ld is made too large, the flow of magnetic flux along the d-axis Ld in the steady state will be obstructed. In this embodiment, it is preferable that the cross-sectional area of ​​the second slot 42 is smaller than the cross-sectional area of ​​the peripheral end slot 41e. According to this embodiment, by making the cross-sectional area of ​​the second slot 42 located on the d-axis Ld sufficiently small, it becomes less likely to obstruct the flow of magnetic flux along the d-axis Ld in the steady state, and a motor 100 with excellent driving efficiency in the steady state can be constructed.

[0065] In this embodiment, the minimum distance Td between the second slot 42 and the peripheral end slot 41e is preferably 0.4 to 0.5 times the minimum distance Sd between adjacent flux barrier groups 30 in the circumferential direction. According to this embodiment, by setting the minimum distance Td to 0.4 times or more the minimum distance Sd, magnetic saturation between the second slot 42 and the peripheral end slot 41e can be suppressed by the magnetic flux along the d-axis Ld. As a result, the magnetic flux can be sufficiently concentrated along the d-axis Ld in a steady state, and the driving efficiency of the motor 100 in a steady state can be increased. Furthermore, by setting the minimum distance Td to 0.5 times or less the minimum distance Sd, the conductor portion 19 on the d-axis Ld can be made sufficiently large.

[0066] In this specification, "minimum distance" is defined as the distance between two parts (for example, a slot and a flux barrier) as the length of the shortest line segment among the countless line segments connecting the two parts when viewed from the axial direction.

[0067] The multiple first slots 41 located radially outward of one flux barrier group 30 include two first adjacent slots 41e, two second adjacent slots 41d, and two third adjacent slots 41c. The two first adjacent slots 41e are located at both ends in the circumferential direction of the multiple first slots 41 located radially outward of one flux barrier group 30. That is, the two first adjacent slots 41e are the circumferential end slots described above. The second adjacent slots 41d are located adjacent to the first adjacent slots 41e in the circumferential direction on the q-axis Lq side. Furthermore, the third adjacent slots 41c are located adjacent to the second adjacent slots 41d in the circumferential direction on the q-axis Lq side.

[0068] One of the two first adjacent slots 41e is radially aligned with the first flux barrier end 31a on one circumferential side of the first flux barrier 31. Similarly, the other of the two first adjacent slots 41e is radially aligned with the first flux barrier end 31a on the other circumferential side of the first flux barrier 31. The first inter-hole distance R1 between the radially inner end 41ea of ​​the first adjacent slot 41e and the first flux barrier end 31a is preferably 0.5 mm or more and 3 mm or less. By setting the first inter-hole distance R1 to 3 mm or less, leakage of magnetic flux between the first adjacent slot 41e and the first flux barrier end 31a can be suppressed. This makes it easier to concentrate the magnetic flux on the d axis Ld in a steady state, thereby increasing the driving efficiency of the rotor 10. On the other hand, by setting the first inter-hole distance R1 to 0.5 mm or more, the rotor core 20 can be easily manufactured while ensuring the rigidity of the rotor core 20.

[0069] One of the two second adjacent slots 41d is radially aligned with the second flux barrier end 32a on one circumferential side of the second flux barrier 32. Similarly, the other of the two second adjacent slots 41d is radially aligned with the second flux barrier end 32a on the other circumferential side of the second flux barrier 32. The second inter-hole distance R2 between the radially inner end 41da of the second adjacent slot 41d and the second flux barrier end 32a is preferably 0.5 mm or more and 3 mm or less for the same reasons as the first inter-hole distance R1.

[0070] One of the two third adjacent slots 41c is radially aligned with the third flux barrier end 33a on one circumferential side of the third flux barrier 33. Similarly, the other of the two third adjacent slots 41c is radially aligned with the third flux barrier end 33a on the other circumferential side of the third flux barrier 33. The second inter-hole distance R2 between the radially inner end 41ca of the third adjacent slot 41c and the third flux barrier end 33a is preferably 0.5 mm or more and 3 mm or less for the same reasons as the first inter-hole distance R1.

[0071] According to this embodiment, the first adjacent slot 41e extends radially outward so as to be connected to the first flux barrier 31. Similarly, the second adjacent slot 41d extends radially outward so as to be connected to the second flux barrier 32. According to this embodiment, the magnetic flux flowing between the first flux barrier 31 and the second flux barrier 32 along a direction perpendicular to the q-axis Lq can be smoothly flowed radially between the first adjacent slot 41e and the second adjacent slot 41d. Furthermore, in order to prevent the flow of magnetic flux between the first flux barrier 31 and the second flux barrier 32 from being obstructed between the first adjacent slot 41e and the second adjacent slot 41d, it is preferable to make the dimensions of the gaps between them as close as possible. That is, the minimum distance T1 between the first adjacent slot 41e and the second adjacent slot 41d is preferably 0.9 times or more and 1.1 times or less the minimum distance S1 between the first flux barrier 31 and the second flux barrier 32.

[0072] Furthermore, according to this embodiment, the third adjacent slot 41c extends radially outward so as to be connected to the third flux barrier 33. According to this embodiment, the magnetic flux flowing between the second flux barrier 32 and the third flux barrier 33 along the direction perpendicular to the q-axis Lq can be smoothly flowed radially between the second adjacent slot 41d and the third adjacent slot 41c. In addition, in order to prevent the flow of magnetic flux between the second flux barrier 32 and the third flux barrier 33 from being obstructed between the second adjacent slot 41d and the third adjacent slot 41c, it is preferable to make the dimensions of the gaps between them as close as possible. That is, the minimum distance T2 between the second adjacent slot 41d and the third adjacent slot 41c is preferably 0.9 times or more and 1.1 times or less the minimum distance S2 between the second flux barrier 32 and the third flux barrier 33.

[0073] The multiple first slots 41 located radially outward of one flux barrier group 30 include five outer slots 41a, 41b, and 41c located radially outward of the third flux barrier 33. The five outer slots 41a, 41b, and 41c are located in the circumferential center (i.e., near the q-axis Lq) of the multiple first slots 41 located radially outward of one flux barrier group 30. Furthermore, the two slots 41c located at both ends of the circumferential direction of the multiple outer slots 41a, 41b, and 41c are the aforementioned third adjacent slots 41c.

[0074] In this embodiment, of the multiple outer slots 41a, 41b, and 41c, the slots 41a and 41c other than the pair of slots 41c located at the ends on both sides in the circumferential direction face the third magnet housing 33b in the radial direction. Preferably, the minimum distance Sq1 between slot 41a and the third flux barrier 33, and the minimum distance Sq2 between slot 41b and the third flux barrier 33 are 0.25 times or more the minimum distance S1 between the first flux barrier 31 and the second flux barrier 32, and the minimum distance S2 between the second flux barrier 32 and the third flux barrier 33.

[0075] It is more preferable that the minimum distances Sq1 and Sq2 between slots 41a and 41b and the third flux barrier 33 are 0.25 times or more the minimum distances S1 and S2 between flux barriers 31, 32, and 33 of the flux barrier group 30.

[0076] In this embodiment, the minimum distances Tq1 and Tq2 between adjacent outer slots 41a, 41b, and 41c in the circumferential direction increase as they approach the q-axis Lq. That is, the minimum distance Tq1 between slot 41a and slot 41b is greater than the minimum distance Tq2 between slot 41b and slot 41c. According to this embodiment, in the starting state, the induced current near the d-axis Ld can be made relatively larger, thereby suppressing torque pulsation and making it easier to stabilize the rotation of the rotor 10 in the starting state.

[0077] (Variation 1) A modified rotor 10 that can be used in the motor 100 of the above-described embodiment will be described below. In the description of each modified example below, components that are the same as those in the embodiment or modified example already described will be denoted by the same reference numerals, and their descriptions will be omitted.

[0078] Figure 4 is a partial cross-sectional view showing a portion of the rotor 110 of Modification 1. The rotor 110 of this modification differs from the embodiment described above in that it does not have a second slot.

[0079] In this modified example, all slots 40 are located radially outward from the flux barrier group 30. That is, all slots 40 are first slots. In this embodiment, all slots 140 are positioned at a different location from the d-axis Ld.

[0080] As shown in this modified example, the rotor 110 does not necessarily have a slot (second slot) located on the d-axis Ld. If the rotor 110 does not have a slot located on the d-axis Ld, the slot is less likely to obstruct the magnetic flux along the d-axis Ld. This makes it easier to concentrate the magnetic flux on the d-axis Ld in a steady state, thereby improving the driving efficiency in a steady state.

[0081] In this modified example, it is more preferable that the minimum distance Td2 between two adjacent slots 140 in the circumferential direction with respect to the d-axis Ld is 0.8 times or more and 1.0 times or less the minimum distance Sd between adjacent flux barrier groups 30 in the circumferential direction.

[0082] Although embodiments and variations of the present invention have been described above, the configurations and combinations thereof in the embodiments and variations are merely examples, and additions, omissions, substitutions, and other modifications are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments and variations.

[0083] The applications of the motor to which the present invention is applied are not particularly limited. The motor may be mounted, for example, in a vehicle or in equipment other than a vehicle. Furthermore, the configurations of the flux barrier group in the above-described embodiments and their modifications, such as the shape and number of the first flux barrier, are examples and can be appropriately changed according to the desired performance.

[0084] For example, in this embodiment, magnets are placed inside the flux barrier, but as described above, the inside of the flux barrier may be empty space. In this case, the shape of the flux barrier does not need to have a rectangular magnet housing portion for accommodating the magnets, and a curved shape can be adopted throughout.

[0085] Furthermore, this technology can be configured as follows: (1) A rotor rotatable about a central axis as the axis of rotation, comprising: a rotor core which is cylindrical in shape with a central axis coinciding with the central axis and has a plurality of through holes that penetrate in the axial direction; a plurality of conductor portions which extend along the axial direction and are arranged in the circumferential direction; and a pair of end rings which are connected to the plurality of conductor portions on one and the other axial side of the rotor core, respectively, wherein the plurality of through holes each include a plurality of slots in which the conductor portions are arranged, and a plurality of flux barriers which are located radially inward from the plurality of slots and constitute a flux barrier group for each q axis of the rotor, wherein the plurality of flux barriers of the flux barrier group are arranged on the q axis and each extends in a direction transverse to the q axis, and the plurality of slots include a plurality of first slots which are located radially outward from the flux barrier group, and the cross-sectional area of ​​the plurality of first slots which are located radially outward from one of the flux barrier groups decreases as it approaches the q axis in the circumferential direction. (2) The rotor according to (1), wherein the plurality of slots include a second slot located on the d-axis, and the plurality of first slots include a circumferential end slot located closest to the d-axis in the circumferential direction, and the cross-sectional area of ​​the circumferential end slot is greater than the cross-sectional area of ​​the second slot. (3) The rotor according to (2), wherein the cross-sectional area of ​​the first slots arranged on the q-axis is 0.8 times or more and 1.0 times or less the cross-sectional area of ​​the second slots. (4) The rotor according to (2) or (3), wherein of two imaginary lines extending radially and dividing the space between the d-axis and the q-axis into three equal parts in the circumferential direction, one located on the q-axis side is designated as the first imaginary line, and the other located on the d-axis side is designated as the second imaginary line, the cross-sectional area of ​​the first slot closest to the first imaginary line or on the first imaginary line is 0.9 times or more and 1.1 times or less the cross-sectional area of ​​the second slot, and the cross-sectional area of ​​the first slot closest to the second imaginary line or on the second imaginary line is 1.5 times or more and 2.0 times or less the cross-sectional area of ​​the second slot. (5) The rotor according to any one of (2) to (4), wherein the minimum distance between the second slot and the circumferential end slot is 0.4 times or more and 0.5 times or less the minimum distance between adjacent flux barrier groups in the circumferential direction. (6) The rotor according to (1), wherein all of the slots are located at positions different from the d-axis, and the minimum distance between two adjacent slots in the circumferential direction across the d-axis is 0.8 times or more and 1.0 times or less the minimum distance between adjacent flux barrier groups in the circumferential direction. (7) The rotor according to any one of (1) to (6), wherein the plurality of flux barriers in the flux barrier group includes a first flux barrier and a second flux barrier arranged adjacent to the radially outer side of the first flux barrier, and the plurality of first slots include a first adjacent slot whose radially inner end is radially aligned with one circumferential end of the first flux barrier and a second adjacent slot whose radially inner end is radially aligned with one circumferential end of the second flux barrier and is adjacent to the first slot in the circumferential direction, and the minimum distance between the first adjacent slot and the second adjacent slot is 0.9 times or more and 1.1 times or less the minimum distance between the first flux barrier and the second flux barrier. (8) The rotor according to any one of (1) to (7), wherein the plurality of flux barriers of the flux barrier group include an outer end flux barrier located on the outermost radial side, and the plurality of first slots include a plurality of outer slots located radially outside the outer end flux barrier, and the minimum distance between adjacent outer slots in the circumferential direction increases as it approaches the q-axis. (9) The rotor according to any one of (1) to (8), wherein the plurality of flux barriers of the flux barrier group include an outer end flux barrier located on the radially outermost side, the plurality of first slots include a plurality of outer slots located radially outside the outer end flux barrier, and the minimum distance between the outer end flux barrier and the other slots of the plurality of outer slots, excluding a pair of slots located at both ends in the circumferential direction, is 0.25 times or more the minimum distance between the plurality of flux barriers of the flux barrier group. (10) The rotor according to any one of (1) to (9), wherein the distance from the outer peripheral surface of the rotor core to the radial inner end of the slot is defined as the inner end distance, and the inner end distance of the plurality of first slots located radially outward of one flux barrier group decreases as it approaches the q-axis in the circumferential direction. (11) The rotor according to (10), wherein the plurality of flux barriers of the flux barrier group include an outer end flux barrier located most radially outward, the plurality of first slots include a circumferential end slot located most d-axis-side in the circumferential direction, and the radially inward end of the circumferential end slot extends radially inward beyond the outer end flux barrier. (12) The rotor according to any one of (1) to (11), wherein the plurality of slots are arranged at equal intervals along the circumferential direction. (13) A motor comprising a rotor as described in any one of (1) to (12), and a stator surrounding the rotor from the radially outer side. [Explanation of symbols]

[0086] 3…Stator, 10,110…Rotor, 18…End ring, 19…Conductor section, 20…Rotor core, 20f…Outer surface, 20h…Through hole, 30…Flux barrier group, 31…Flux barrier, 31…First flux barrier, 31a…First flux barrier end (end), 32…Second flux barrier, 33…Third flux barrier (outer end flux barrier), 40,140…Slot, 41…First slot, 41a…Slot (outer slot), 41b…Slot (Outer slot), 41c... Slot (Outer slot, 3rd adjacent slot), 41d... Slot (2nd adjacent slot), 41e... Slot (1st adjacent slot, peripheral slot), 42... 2nd slot, 100... Motor, J... Center axis, L1... 1st virtual line, L2... 2nd virtual line, Ld... d axis, Lq... q axis, S1, S2, Sd, Sq1, Sq2, T1, T2, Td, Td2, Tq1, Tq1q, Tq2... Minimum distance, Sp1, Sp2, Sp3, Sp4, Sp5... Inner end distance

Claims

1. A rotor that can rotate with its central axis as the axis of rotation, A rotor core having a cylindrical shape with its central axis coinciding with the aforementioned central axis, and provided with multiple through holes penetrating in the axial direction, Multiple conductive parts extending along the axial direction and arranged in the circumferential direction, The rotor core has a pair of end rings connected to the plurality of conductors on one axial side and the other side, respectively. The aforementioned plurality of through holes are Each of the aforementioned conductors is arranged in a plurality of slots, It includes a plurality of flux barriers located radially inward from the plurality of slots, which constitute a flux barrier group for each q-axis of the rotor, The plurality of flux barriers in the flux barrier group are aligned on the q-axis and each extends in a direction transverse to the q-axis. The plurality of slots include a plurality of first slots located radially outward of the flux barrier group, The cross-sectional area of ​​the plurality of first slots located radially outward of one flux barrier group decreases as it approaches the q-axis in the circumferential direction. Rotor.

2. The plurality of slots include a second slot located on the d-axis, The plurality of first slots include a circumferential end slot that is positioned closest to the d-axis in the circumferential direction. The cross-sectional area of ​​the peripheral slot is larger than the cross-sectional area of ​​the second slot. The rotor according to claim 1.

3. The cross-sectional area of ​​the first slot, which is located on the q-axis among the plurality of first slots, is 0.8 times or more and 1.0 times or less the cross-sectional area of ​​the second slot. The rotor according to claim 2.

4. Of the two imaginary lines extending radially and dividing the space between the d-axis and the q-axis into three equal parts in the circumferential direction, one located on the q-axis side shall be called the first imaginary line, and the other located on the d-axis side shall be called the second imaginary line. The cross-sectional area of ​​the first slot closest to the first virtual line or located on the first virtual line among the plurality of first slots is 0.9 times or more and 1.1 times or less the cross-sectional area of ​​the second slot. The cross-sectional area of ​​the first slot closest to the second virtual line or located on the second virtual line is 1.5 times or more and 2.0 times or less the cross-sectional area of ​​the second slot. The rotor according to claim 2.

5. The minimum distance between the second slot and the peripheral end slot is 0.4 to 0.5 times the minimum distance between adjacent flux barrier groups in the circumferential direction. The rotor according to claim 2.

6. All of the aforementioned slots are positioned at a location different from the d-axis. The minimum distance between two adjacent slots in the circumferential direction, straddling the d-axis, is 0.8 times or more and 1.0 times or less the minimum distance between adjacent flux barrier groups in the circumferential direction. The rotor according to claim 1.

7. The plurality of flux barriers in the flux barrier group are The first flux barrier and, The first flux barrier is disposed adjacent to the radially outer side of the second flux barrier, The aforementioned plurality of first slots are, The radially inner end is aligned radially with the first adjacent slot that is aligned radially with one circumferential end of the first flux barrier, The radially inner end includes a second adjacent slot that is radially aligned with one circumferential end of the second flux barrier and adjacent to the first slot in the circumferential direction, The minimum distance between the first adjacent slot and the second adjacent slot is 0.9 times or more and 1.1 times or less the minimum distance between the first flux barrier and the second flux barrier. The rotor according to claim 1.

8. The plurality of flux barriers in the flux barrier group include an outer end flux barrier that is positioned radially outward, The plurality of first slots include a plurality of outer slots located radially outward of the outer end flux barrier, The minimum distance between adjacent outer slots in the circumferential direction increases as it approaches the q-axis. The rotor according to claim 1.

9. The plurality of flux barriers in the flux barrier group include an outer end flux barrier that is positioned radially outward, The plurality of first slots include a plurality of outer slots located radially outward of the outer end flux barrier, Of the plurality of outer slots, the minimum distance between the slots other than the pair of slots located at both ends in the circumferential direction and the outer end flux barrier is 0.25 times or more the minimum distance between the plurality of flux barriers in the flux barrier group. The rotor according to claim 1.

10. The distance from the outer circumferential surface of the rotor core to the radial inner end of the slot is defined as the inner end distance. The distance between the inner ends of the plurality of first slots located radially outward of one flux barrier group decreases as it approaches the q-axis in the circumferential direction. The rotor according to claim 1.

11. The plurality of flux barriers in the flux barrier group include an outer end flux barrier that is positioned radially outward, The plurality of first slots include a circumferential end slot located closest to the d-axis in the circumferential direction. The radially inward end of the circumferential slot extends radially inward beyond the outer flux barrier. The rotor according to claim 10.

12. The aforementioned plurality of slots are arranged at equal intervals along the circumferential direction. The rotor according to claim 1.

13. A rotor according to any one of claims 1 to 12, The rotor comprises a stator that surrounds the rotor from the radially outer side, Motor.

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