Rotor, rotary electric machine, vehicular drive device, and production method for rotor

Abstract

The present invention has, from the outside (X1) in the radial direction (X) of a rotor core (2), an outer circumferential region part (22), a center region part (23), and an inner circumferential region part (24). A plurality of magnet insertion holes (4) that accommodate permanent magnets (5) are provided in the outer circumferential region part (22) and the center region part (23). Bridge parts (7) are formed between the magnet insertion holes (4) and the portion of the rotor core (2) that is furthest to the outside (X1) in the radial direction (X). In a cross-section of the rotor core (2) that is orthogonal to the axial direction (Y), the outer circumferential region part (22) is a ring-shaped area that extends from the portion of the rotor core (2) that is furthest to the outside (X1) in the radial direction (X) to include at least the bridge parts (7). The average crystal grain diameter of the outer circumferential region part (22) is smaller than the average crystal grain diameter of at least one of the inner circumferential region part (24) and the center region part (23).

Description

Rotor, rotating electric machine, vehicle drive device, and method for manufacturing rotor

[0001] The present disclosure relates to a rotor, a rotating electric machine, a vehicle drive device, and a method for manufacturing a rotor.

[0002] Development of motors for electric vehicles (EVs) and hybrid electric vehicles (HEVs) is progressing to achieve higher rotational speeds and higher performance in order to further improve driving performance. One method for manufacturing rotors with high strength and excellent magnetic properties is to divide the rotor core into an outer peripheral region and an inner peripheral region, anneal the outer peripheral region at a temperature at which grain growth of the magnetic steel sheet occurs, and anneal the inner peripheral region at a temperature at which grain growth does not occur (see, for example, Patent Document 1). Another method for improving the mechanical strength of the bridge portion of the rotor core is to use an amorphous soft magnetic material, which is an amorphous material, to construct the bridge portion with an amorphous soft magnetic material and the remaining portion with a nanocrystalline soft magnetic material (see, for example, Patent Document 2).

[0003] JP 2020-25466 A JP 2019-221127 A

[0004] In the conventional design of Patent Document 1, the bridge section between the outer circumferential surface of the rotor core and the magnet insertion holes is annealed, causing grain growth of the crystals, which reduces the strength of the bridge section and makes it unable to handle high rotation speeds. Furthermore, because the reduced strength requires the width of the bridge section to be increased, there is a problem that improvements in magnetic properties, particularly operating properties such as torque and output, cannot be expected.

[0005] In addition, in the conventional Patent Document 2, an amorphous soft magnetic material is used, but amorphous soft magnetic materials, which are non-crystalline materials, require a special process of ultra-rapidly cooling the molten material during the manufacturing process. Furthermore, amorphous soft magnetic materials are not only hard and brittle, but also thin foils that are only about 1 / 10 the thickness of electromagnetic steel sheets. Therefore, special press processing is required to punch out the rotor sheet material, and a large amount of rotor sheet material must be stacked, resulting in higher manufacturing costs for the rotor core compared to electromagnetic steel sheets, which are crystalline materials. Furthermore, amorphous soft magnetic materials have a lower saturation magnetic flux density than electromagnetic steel sheets, resulting in the problem that improvements in magnetic properties, particularly torque operating characteristics, cannot be expected.

[0006] The present disclosure discloses technology for solving the above-mentioned problems, and aims to provide a rotor, a rotating electric machine, a vehicle drive device, and a method for manufacturing a rotor that can improve the resistance to centrifugal force and operating characteristics of a rotor in a rotating electric machine using an inexpensive or simple manufacturing method.

[0007] The rotor of the present disclosure is a rotor having a rotor core in which a plurality of rotor plate materials are stacked in the axial direction, wherein the rotor core has an outer circumferential region located radially outside the rotor core, an inner circumferential region located radially inside the rotor core, and a central region located radially between the outer circumferential region and the inner circumferential region, wherein the outer circumferential region and the central region are provided with a plurality of magnet insertion holes or a plurality of slits for accommodating permanent magnets, and a bridge portion is formed between the outermost radial part of the rotor core and the magnet insertion holes or the slits, and the outer circumferential region is an annular range in a cross section perpendicular to the axial direction of the rotor core, from the outermost radial part of the rotor core to include at least the bridge portion, and the average crystal grain size of the outer circumferential region is smaller than the average crystal grain size of at least either the inner circumferential region or the central region. The present disclosure also provides a rotating electric machine comprising a stator having a stator winding and rotatably disposed on the inner circumferential side of the stator via a gap. The present disclosure also provides a vehicle drive device comprising the rotating electric machine described above as a drive motor, and wherein the maximum rotation speed of the rotating electric machine in a normal operating range is set to 15,000 rpm or more. The present disclosure also provides a rotor manufacturing method comprising the above-described steps of: punching an electromagnetic steel sheet, which is a crystalline material, to form the rotor plate material; stacking a plurality of the rotor plate materials in the axial direction; and annealing the electromagnetic steel sheet constituting the rotor plate material at a temperature that causes grain growth of crystals so that the average crystal grain size in the outer circumferential region of the rotor plate material is smaller than at least one of the average crystal grain size in the inner circumferential region and the average crystal grain size in the central region.

[0008] According to the rotor, rotating electric machine, vehicle drive device, and rotor manufacturing method of the present disclosure, the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine can be improved by an inexpensive or simple manufacturing method.

[0009] 12A is a cross-sectional view schematically showing the configuration of a rotating electric machine according to embodiment 1. FIG. 12B is a cross-sectional plan view showing the configuration of a cross section of line AA of the rotor of the rotating electric machine shown in FIG. 1. FIG. 12C is a cross-sectional plan view showing an enlarged portion of the rotor shown in FIG. 2. FIG. 12D is a cross-sectional plan view showing a schematic diagram of the relationship between the grain size of an electromagnetic steel sheet and eddy current loss, hysteresis loss, and total iron loss. FIG. 12E is a cross-sectional plan view showing a first modified example of the rotor according to embodiment 1. FIG. 12F is a cross-sectional plan view showing a second modified example of the rotor according to embodiment 1. FIG. 12G is a cross-sectional plan view showing a third modified example of the rotor according to embodiment 1. FIG. 12H is a cross-sectional plan view showing a fourth modified example of the rotor according to embodiment 1. FIG. 12H is a cross-sectional plan view showing a fifth modified example of the rotor according to embodiment 1. FIG. 12H is a cross-sectional plan view showing a sixth modified example of the rotor according to embodiment 1. FIG. 12H is a configuration diagram showing an application form of the rotating electric machine shown in FIG. 1. FIG. 12A is a schematic diagram showing a method of manufacturing the rotor shown in FIG. 2. FIG. 12B is a plan view showing the configuration of a rotor core of the rotor manufactured according to FIG. 12A. FIG. 12B is a perspective view showing a method of manufacturing a rotor using the rotor core of the rotor shown in FIG. 12B. FIG. 12I is a cross-sectional plan view showing a first specific example of a rotor in a synchronous reluctance motor as the rotating electric machine according to embodiment 1. Fig. 10 is a plan view showing a specific example 2 of the rotor in a synchronous reluctance motor as a rotating electric machine according to embodiment 1. Fig. 11 is a plan sectional view showing another example of the rotor in embodiment 1.

[0010] Embodiment 1. Fig. 1 is a cross-sectional view that schematically shows the configuration of a rotating electric machine according to embodiment 1. Fig. 2 is a cross-sectional plan view that shows the configuration of the rotor of the rotating electric machine shown in Fig. 1 taken along line A-A. Fig. 3 is a cross-sectional plan view that shows an enlarged portion of the rotor shown in Fig. 2. Fig. 4 is a diagram that schematically shows the relationship between the grain size of an electromagnetic steel sheet and eddy current loss, hysteresis loss, and total iron loss. Fig. 5 is a cross-sectional plan view that shows a first modified example of the rotor according to embodiment 1. Fig. 6 is a cross-sectional plan view that shows a second modified example of the rotor according to embodiment 1.

[0011] FIG. 7 is a plan cross-sectional view showing a third modified example of the rotor according to embodiment 1. FIG. 8 is a plan cross-sectional view showing a fourth modified example of the rotor according to embodiment 1. FIG. 9 is a plan cross-sectional view showing a fifth modified example of the rotor according to embodiment 1. FIG. 10 is a plan cross-sectional view showing a sixth modified example of the rotor according to embodiment 1. FIG. 11 is a configuration diagram showing an application form of the rotating electric machine shown in FIG. 1. FIG. 12A is a schematic diagram showing a method for manufacturing the rotor shown in FIG. 2. FIG. 12B is a plan view showing the configuration of a rotor core of the rotor manufactured according to FIG. 12A.

[0012] Fig. 13 is a perspective view showing a method for manufacturing a rotor using the rotor core of the rotor shown in Fig. 12B. Fig. 14 is a plan view showing a first specific example of a rotor in a synchronous reluctance motor as a rotating electric machine according to embodiment 1. Fig. 15 is a plan view showing a second specific example of a rotor in a synchronous reluctance motor as a rotating electric machine according to embodiment 1. Fig. 16 is a plan cross-sectional view showing another example of a rotor in embodiment 1.

[0013] In the following description, each direction in the rotating electric machine 100 is referred to as the axial direction Y of the rotation shaft, the radial direction X, the outer side X1 of the radial direction X, and the inner side X2 of the radial direction X. Therefore, in other parts constituting the rotating electric machine 100, each direction will be described based on these directions. Note that in Figure 3 and subsequent figures, for convenience, the radial direction X is shown only on the d-axis or q-axis. Also, Figures 2, 3, 5 to 10, 14, and 15 show cross sections perpendicular to the axial direction Y of the rotor core 2.

[0014] As shown in Fig. 1, a rotating electric machine 100 includes a stator 102 arranged in an annular shape within a housing (not shown), and a rotor 101 rotatably arranged on the inside X2 of the stator 102 in the radial direction X via an air gap. The stator 102 has an annular core back (not shown), teeth (not shown) extending inward in the radial direction X from the core back, and slots (not shown) surrounded by the core back and the teeth, and a coil (not shown) is housed in the slot. The rotor 101 includes a rotor core 2, a permanent magnet 5, and a fitting part 10. The rotor core 2 is formed by stacking a plurality of rotor plates 3 in the axial direction Y, as shown in Fig. 13 (described later), for example.

[0015] As shown in Fig. 2, the rotor 101 includes a rotor core 2, permanent magnets 5 housed in magnet insertion holes 4 of the rotor core 2, and a fitting part 10 that is inserted into a fitting hole 6 of the rotor core 2 and transmits rotational force. In the first embodiment, the fitting part 10 is illustrated as a substantially cylindrical shaft, but a substantially hollow cylindrical boss (not shown) may also be used. Although not shown, the rotor core 2 and the fitting part 10 may be fitted together via a key structure provided on the outer periphery of the fitting part 10 and the fitting hole 6 of the rotor core 2.

[0016] The rotor core 2 of the rotor 101 is provided with magnet insertion holes 4 corresponding to the desired number of magnetic poles, and in the first embodiment, one pair of magnet insertion holes 4 is provided per pole for a total of eight poles. Each pair of magnet insertion holes 4 is formed in a generally V-shape that protrudes toward the inner side X2 in the radial direction X of the rotor 101. One permanent magnet 5 is housed in one magnet insertion hole 4.

[0017] As shown in Figure 3, a flux barrier 41 for preventing leakage of magnetic flux is configured on the outer side X1 of the magnet insertion hole 4 in the radial direction X. The outermost side X1 of the rotor core 2 in the radial direction X is the outer peripheral surface 21 (hereinafter, this part will be referred to simply as the "outer peripheral surface 21"). A bridge portion 7 having a minute width 9 in the radial direction X is configured between the outer peripheral surface 21 and the magnet insertion hole 4 in the radial direction X.

[0018] The rotor core 2 is formed with an outer circumferential region 22, a central region 23, and an inner circumferential region 24, in that order from the outer side X1 to the inner side X2 in the radial direction X. The outer circumferential region 22 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner side X2 in the radial direction X, including at least the bridge portion 7. The central region 23 is an annular range extending from the outer circumferential region 22 toward the inner side X2 in the radial direction X, including the magnet insertion hole 4. The inner circumferential region 24 is an annular range extending from the central region 23 toward the inner side X2 in the radial direction X, including the fitting hole 6. Although not shown, if the fitting hole 6 of the rotor core 2 has a key structure, the inner circumferential region 24 will include the key structure.

[0019] 3 of the first embodiment, the outer peripheral region 22 is an annular range including a position from the outer peripheral surface 21 to the magnet outer abutment point 8 on the outermost side in the radial direction X1 where the permanent magnet 5 abuts against the magnet insertion hole 4, in other words, including a portion of the side portion 42 of the magnet insertion hole 4 that is closest to the bridge portion 7 on the outermost side in the radial direction X1 (the same position as the magnet outer abutment point 8). The outer peripheral region 22 also includes the bridge inner point B on the innermost side in the radial direction X2 of the bridge portion 7.

[0020] The permanent magnet 5 generally contacts the magnet insertion hole 4 via a coating (not shown) applied to the surface of the permanent magnet 5 or an adhesive (not shown) interposed between the permanent magnet 5 and the magnet insertion hole 4. Therefore, even when contact is made via these, it is considered that the permanent magnet 5 is in contact with the magnet insertion hole 4, and is referred to as the magnet outer contact point 8. This relationship between the permanent magnet, magnet insertion hole, and magnet outer contact point is the same in each of the following examples, and therefore description thereof will be omitted where appropriate.

[0021] The central region 23 is an annular range that includes all areas of the magnet insertion hole 4 that are not included in the outer peripheral region 22. The average crystal grain size of the outer peripheral region 22 is smaller than the average crystal grain size of at least either the central region 23 or the inner peripheral region 24. Note that the "average crystal grain size" referred to in this disclosure is a typical grain size in a metal material that is an aggregate of crystal grains of various sizes. This grain size can be measured by measuring the grain size within 1 mm ２There are two methods for determining the crystal grain size: one is to determine it from the number of crystal grains per test line, and the other is to determine it from the number of crystal grains captured by a linear test line. This also applies to the following cases, so the explanation will be omitted.

[0022] To improve the resistance of the rotor 101 to centrifugal force, it is necessary to increase the strength of the bridge portions 7, which have a fine width 9. Furthermore, the centrifugal force generated by the rotation of the rotor 101 causes the permanent magnets 5 housed in the magnet insertion holes 4 to move outward in the radial direction X1. Therefore, when the rotor 101 rotates at high speeds, an excessive load is applied to the magnet outer abutment points 8 of the rotor core 2 due to the movement or abutment of the permanent magnets 5. If this load is repeatedly applied, there is a concern that the rotor core 2 may suffer fatigue failure, starting from the magnet outer abutment points 8. For this reason, it is necessary to increase the strength of the rotor core 2 in the portions corresponding to the magnet outer abutment points 8.

[0023] In the first embodiment, by making the average crystal grain size of the outer peripheral region 22 including the bridge portions 7 smaller than the average crystal grain size of the inner peripheral region 24 and the central region 23, the strength of the rotor core 2 at the bridge portions 7 and the magnet outer abutment points 8 is increased, thereby improving the resistance of the rotor 101 to centrifugal forces. Furthermore, in order to achieve high rotational speeds and high performance of the rotating electric machine 100, it is necessary to reduce losses occurring in the rotor 101, such as eddy current loss E and hysteresis loss H, in addition to improving torque and output. The relationship between crystal grain size and eddy current loss E and hysteresis loss H will be described in detail below.

[0024] In the above-described first embodiment, an example is shown in which the magnet outer abutment point 8 at the outermost position X1 in the radial direction X where the permanent magnet 5 abuts against the magnet insertion hole 4 is located at the same location as the magnet corner portion at the outermost position X1 in the radial direction X of the permanent magnet 5, but this is not limited to this. For example, as shown in another example in FIG. 16 , if the shape of the magnet insertion hole 40 is different from the shape of the magnet insertion hole 4 in FIG. 3 , the magnet corner portion G at the outermost position X1 in the radial direction X of the permanent magnet 5 may not abut against the magnet insertion hole 40. In other words, the magnet outer abutment point 80 at the outermost position X1 in the radial direction X where the permanent magnet 5 abuts against the magnet insertion hole 40 may be different from the magnet corner portion G at the outermost position X1 in the radial direction X of the permanent magnet 5. Note that this point is the same in the following examples, and therefore description thereof will be omitted as appropriate.

[0025] In the first embodiment, because the bridge portions 7 are strengthened, the width 9 of the bridge portions 7 can be optimized to match the desired magnetic properties, thereby achieving high performance with increased rotation, torque, and output of the rotating electric machine 100. Furthermore, since the hysteresis loss H of the rotor 101 depends on the rotation speed of the rotor 101 and tends to be distributed mainly in the outer peripheral region 22 including the bridge portions 7, optimizing the width 9 of the bridge portions 7 can reduce the region where the hysteresis loss H occurs, thereby reducing the overall loss amount of the rotor 101 and achieving high rotation and high performance of the rotating electric machine 100. Furthermore, by using an electromagnetic steel sheet, which is a crystalline material, higher torque can be achieved than when an amorphous soft magnetic material, which is a non-crystalline material, is used, and since the manufacturing cost of the rotor core 2 is kept low, high rotation and high performance can be achieved by a relatively inexpensive or simple method.

[0026] Furthermore, in the above-described first embodiment, it is possible to set the average crystal grain size of the outer peripheral region 22 to less than 50 μm, which is smaller than that of a normal grain size material having an average crystal grain size of 50 μm or more (note that "normal grain size material" refers to an electromagnetic steel sheet, which is a crystalline material that has been generally used in rotor cores until now). In this case, the outer peripheral region 22 is strengthened, and the rotor 101 can be made even more resistant to centrifugal force. Furthermore, because the bridge portions 7 are strengthened, the torque and output can be improved by optimizing the width 9 of the bridge portions 7, and the overall loss amount of the rotor 101 can be reduced, thereby achieving even higher rotation speeds and higher performance of the rotating electric machine 100.

[0027] Furthermore, in the first embodiment, it is desirable that the central region 23, which includes the magnet insertion holes 4 and the permanent magnets 5 housed in the magnet insertion holes 4, have low loss within the region in order to achieve high rotation speed and high performance of the rotating electric machine 100. As shown in FIG. 4 , the hysteresis loss H of an electrical steel sheet, which is a crystalline material, tends to decrease as the average crystal grain size increases. Therefore, in the first embodiment, it is considered to form the average crystal grain size of the central region 23 to 50 μm or more, which is greater than that of a normal grain size material. By forming it in this manner, the rotor core 2 can be used within a range that can be expected to have a reduction effect on hysteresis loss H, thereby achieving even higher rotation speed and higher performance of the rotating electric machine 100.

[0028] However, as shown in Figure 4, the eddy current loss E tends to increase as the average crystal grain size increases. If the eddy current loss E increases, the rotor 101 is more likely to generate heat during rotation, which requires the addition of rare earth elements to the permanent magnets 5 to improve heat resistance, the addition of a cooling device to the rotor 101 and the rotating electric machine 100, or the improvement of the performance of existing devices, which raises concerns about increased costs. For this reason, in the first embodiment, it is considered to set the average crystal grain size of the central region 23 to less than 200 µm.

[0029] This allows the rotor core 2 to be used within a range where the average crystal grain size is larger than that of a normal grain size material and where a reduction effect can be expected in the total iron loss T, which takes into account both hysteresis loss H and eddy current loss E shown in Figure 4, and thereby enables the rotating electric machine 100 to achieve even higher rotation speeds and higher performance using a relatively inexpensive or simple method.

[0030] Furthermore, the centrifugal force generated by the rotation of the rotor 101 reduces the surface pressure between the rotor 101 and the mating part 10. Therefore, in order to achieve high rotation speeds, it is necessary to provide a larger fit between the rotor 101 and the mating part 10. However, if the fit is made larger, there is a concern that the fit hole 6 of the rotor core 2 that constitutes the rotor 101 may buckle due to stress generated during assembly.

[0031] Therefore, in the present embodiment 1, it is considered to form the average crystal grain size of the inner peripheral region 24 to be less than 50 μm, which is smaller than that of a material with a normal grain size. By forming it in this manner, the strength of the inner peripheral region 24 is increased, and even if a large fitting margin is provided, the rotor core 2 can be assembled without buckling, and a predetermined surface pressure can be secured even at high rotation speeds, thereby realizing even higher rotation speeds of the rotating electric machine 100.

[0032] Furthermore, it is possible to form the relationship between the average crystal grain sizes of the respective regions such that the relationship is: central region > inner region ≥ outer region. This is intended to set the average crystal grain size in the inner region 24 within a range that is not smaller than the average crystal grain size in the outer region 22. Therefore, by reducing the average crystal grain size in the outer region 22 in this way, the inner region 24 can be set in advance to an average crystal grain size of less than 50 μm in accordance with the desired strength and magnetic characteristics of the rotor 101, thereby achieving both high rotational speed and high performance of the rotating electric machine 100.

[0033] In this embodiment 1, one pair of magnet insertion holes 4 per pole is arranged in an approximately V-shape symmetrical with respect to the d-axis, which is the central axis of the magnetic pole, for eight poles, but the number of poles may be other than eight depending on the desired magnetic characteristics.

[0034] Next, a first modification of the first embodiment will be described with reference to Fig. 5 . As shown in Fig. 5 , magnet insertion holes 204, 206 are provided in the rotor core 2 of the rotor 101, and one permanent magnet 205, 207 is housed in each of the magnet insertion holes 204, 206. Flux barriers 2411, 2412 for preventing leakage of magnetic flux are formed on the outer side X1 in the radial direction X of each magnet insertion hole 204, 206. In addition, bridge portions 2071, 2072 having minute widths 2091, 2092 in the radial direction X are formed between the outer circumferential surface 21 of the rotor core 2 and each magnet insertion hole 204, 206 in the radial direction X.

[0035] The rotor core 2 is formed with an outer circumferential region 222, a central region 223, and an inner circumferential region 224, in that order from the outer side X1 to the inner side X2 in the radial direction X. The outer circumferential region 222 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner side X2 in the radial direction X, including at least the bridge portions 2071 and 2072. The central region 223 is an annular range extending from the outer circumferential region 222 toward the inner side X2 in the radial direction X, including the magnet insertion holes 204 and 206. The inner circumferential region 224 is an annular range extending from the central region 223 toward the inner side X2 in the radial direction X, including the fitting hole 6.

[0036] Here, the magnet insertion holes 204, 206 are arranged asymmetrically such that the angles θ1, θ2 formed by the magnet corners G1, G2 at the outermost positions X1 in the radial direction X of each permanent magnet 205, 207, the straight lines S1, S2 connecting the rotation center axis, and the d-axis are different in magnitude.

[0037] More specifically, the outer peripheral region 222 in the first modification of the first embodiment is a region extending from the outer peripheral surface 21 to the magnet outer abutment points 2081, 2082 at the outermost positions X1 in the radial direction X where the permanent magnets 205, 207 abut against the magnet insertion holes 204, 206 (in other words, the positions of the side portions 2421, 2422 of the magnet insertion holes 204, 206 that are closest to the bridge portions 2071, 2072 at the outermost positions X1 in the radial direction X). In this case, the outer peripheral region 222 is an annular region including the magnet outer abutment point 2081 at the innermost position X2 in the radial direction X among the multiple magnet outer abutment points 2081, 2082. In other words, all of the magnet outer abutment points 2081, 2082 are included from the outer peripheral surface 21. The outer peripheral region 222 also includes the bridge inner points B1, B2 at the innermost positions X2 in the radial direction X of the bridge portions 2071, 2072.

[0038] Next, a second modification of the first embodiment will be described with reference to Fig. 6. As shown in Fig. 6, the rotor core 2 of the rotor 101 is provided with magnet insertion holes 304, and each magnet insertion hole 304 houses one permanent magnet 305. A flux barrier 341 for preventing leakage of magnetic flux is formed on the outer side X1 in the radial direction X of the magnet insertion hole 304. In addition, a bridge portion 307 having a minute width 309 in the radial direction X is formed between the outer circumferential surface 21 of the rotor core 2 and the magnet insertion hole 304 in the radial direction X.

[0039] The rotor core 2 is formed with an outer circumferential region 322, a central region 323, and an inner circumferential region 324, in that order from the outer side X1 to the inner side X2 in the radial direction X. The outer circumferential region 322 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner side X2 in the radial direction X, including at least the bridge portion 307. The central region 323 is an annular range extending from the outer circumferential region 322 toward the inner side X2 in the radial direction X, including the magnet insertion hole 304. The inner circumferential region 324 is an annular range extending from the central region 323 toward the inner side X2 in the radial direction X, including the fitting hole 6.

[0040] Here, only one magnet insertion hole 304 is arranged per pole in a direction approximately perpendicular to the d-axis. Therefore, more specifically, the outer peripheral region 322 of Modification 2 of Embodiment 1 includes a bridge inner point B at the innermost point X2 in the radial direction X of the bridge portion 307. This outer peripheral region 322 also includes a magnet outer abutment point 308 at the outermost point X1 in the radial direction X where the permanent magnet 305 abuts against the magnet insertion hole 304 (in other words, the point of the side portion 342 of the magnet insertion hole 304 that is closest to the bridge portion 307 at the outermost point X1 in the radial direction X).

[0041] Next, a third modification of the first embodiment will be described with reference to Fig. 7. As shown in Fig. 7, the rotor core 2 of the rotor 101 is provided with one or more magnet insertion holes 404 in a direction substantially perpendicular to the d-axis, three magnet insertion holes 404 per pole in this example. While the example shows three magnet insertion holes 404 arranged in a substantially V-shape, other magnet insertion holes may be arranged on the outer side X1 in the radial direction X of the magnet insertion holes 404 arranged in a substantially V-shape, depending on the desired magnetic characteristics.

[0042] Each magnet insertion hole 404 houses one permanent magnet 405. A flux barrier 44 for preventing leakage of magnetic flux is formed on the outer side X1 of the magnet insertion hole 404 in the radial direction X. In addition, a bridge portion 407 having a minute width 409 in the radial direction X is formed between the outer peripheral surface 21 of the rotor core 2 and the magnet insertion hole 404 in the radial direction X.

[0043] The rotor core 2 is formed with an outer circumferential region 422, a central region 423, and an inner circumferential region 424, in that order from the outer side X1 to the inner side X2 in the radial direction X. The outer circumferential region 422 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner side X2 in the radial direction X, including at least the bridge portion 407. The central region 423 is an annular range extending from the outer circumferential region 422 toward the inner side X2 in the radial direction X, including the magnet insertion hole 404. The inner circumferential region 424 is an annular range extending from the central region 423 toward the inner side X2 in the radial direction X, including the fitting hole 6.

[0044] More specifically, the outer peripheral region 422 of the third modification of the first embodiment includes, from the outer peripheral surface 21, a bridge inner point B at the innermost point X2 in the radial direction X of the bridge portion 407. The outer peripheral region 422 also includes a magnet outer abutment point 408 at the outermost point X1 in the radial direction X where the permanent magnet 405 abuts against the magnet insertion hole 404 (in other words, a point of the side portion 442 of the magnet insertion hole 404 that is closest to the bridge portion 407 at the outermost point X1 in the radial direction X).

[0045] Next, a fourth modification of the first embodiment will be described with reference to Figure 8. As shown in Figure 8, magnet insertion holes 504 are provided in the rotor core 2 of the rotor 101, and two permanent magnets 505, 506 are housed in each magnet insertion hole 504. Note that a similar configuration is also possible when three or more permanent magnets are housed. A flux barrier 541 is provided on the outer side X1 in the radial direction X of the magnet insertion hole 504 to prevent leakage of magnetic flux. In addition, a bridge portion 507 having a minute width 509 in the radial direction X is provided between the outer circumferential surface 21 of the rotor core 2 and the magnet insertion hole 504 in the radial direction X.

[0046] The rotor core 2 is formed with an outer circumferential region 522, a central region 523, and an inner circumferential region 524, in that order from the outer side X1 to the inner side X2 in the radial direction X. The outer circumferential region 522 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner side X2 in the radial direction X, including at least the bridge portion 507. The central region 523 is an annular range extending from the outer circumferential region 522 toward the inner side X2 in the radial direction X, including the magnet insertion hole 504. The inner circumferential region 524 is an annular range extending from the central region 523 toward the inner side X2 in the radial direction X, including the fitting hole 6.

[0047] More specifically, the outer peripheral region 522 of the fourth modification of the first embodiment is an annular range that includes, from the outer peripheral surface 21, the magnet outer abutment points 508 on the outermost side X1 in the radial direction X where each permanent magnet 505, 506 abuts against the magnet insertion hole 504 (in other words, the point of the side portion 542 of the magnet insertion hole 504 that is closest to the bridge portion 507 on the outermost side X1 in the radial direction X). The outer peripheral region 522 also includes the bridge inner point B on the innermost side X2 in the radial direction X of the bridge portion 507.

[0048] Next, a fifth modification of the first embodiment will be described with reference to Fig. 9. As shown in Fig. 9, magnet insertion holes 6041, 6042, 6043, and 6044 are provided in rotor core 2 of rotor 101, and one permanent magnet 6051, 6052, 6053, and 6054 is housed in each of magnet insertion holes 6041, 6042, 6043, and 6044. Flux barriers 6411, 6412, 6413, and 6414 are provided on the outer side X1 in the radial direction X of magnet insertion holes 6041, 6042, 6043, and 6044 to prevent leakage of magnetic flux. Furthermore, bridge portions 6071, 6072, 6073, and 6074 having a minute width in the radial direction X are formed between the outer peripheral surface 21 of the rotor core 2 and the magnet insertion holes 6041, 6042, 6043, and 6044, respectively.

[0049] The rotor core 2 is formed with an outer circumferential region 622, a central region 623, and an inner circumferential region 624, in that order from the outer circumferential side X1 to the inner circumferential side X2 in the radial direction X. The outer circumferential region 622 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner circumferential side X2 in the radial direction X, including at least bridge portions 6071, 6072, 6073, and 6074. The central region 623 is an annular range extending from the outer circumferential region 622 toward the inner circumferential side X2 in the radial direction X, including magnet insertion holes 6041, 6042, 6043, and 6044. The inner circumferential region 624 is an annular range extending from the central region 623 toward the inner circumferential side X2 in the radial direction X, including the fitting hole 6.

[0050] More specifically, the outer peripheral region 622 of the fifth modification of the first embodiment is an annular range that includes, from the outer peripheral surface 21, magnet outer abutment points 6081, 6083 at the outermost positions X1 in the radial direction X where the permanent magnets 6051, 6053 abut against the magnet insertion holes 6041, 6043 (in other words, of the side portions 6421, 6423 of the magnet insertion holes 6041, 6043, the points that are closest to the bridge portions 6071, 6073 at the outermost positions X1 in the radial direction X). The outer peripheral region 622 also includes bridge inner points B3, B4 at the innermost positions X2 in the radial direction X of the bridge portions 6071, 6072, 6073, 6074.

[0051] In this way, the outer peripheral region 622 of the fifth variant of the first embodiment does not need to include the magnet outer abutment points 6082, 6084 at the outermost positions X1 in the radial direction X of each permanent magnet 6052, 6054, but it is sufficient that it includes at least the magnet outer abutment points 6081, 6083 located at the outermost positions X1 in the radial direction X, which are susceptible to the influence of centrifugal force.

[0052] Next, a sixth modification of the first embodiment will be described with reference to FIG. 10 . As shown in FIG. 10 , magnet insertion holes 704 are provided in the rotor core 2 of the rotor 101, and each magnet insertion hole 704 houses one permanent magnet 705. A flux barrier 74 for preventing leakage of magnetic flux is provided on the outer side X1 of the magnet insertion hole 704 in the radial direction X. Depending on the desired magnetic characteristics, a gap 743 may be provided between the outer peripheral surface 21 of the rotor core 2 and the magnet insertion hole 704 in the radial direction X. In this case, the gap 743 divides the space between the outer peripheral surface 21 of the rotor core 2 and the magnet insertion hole 704 in the radial direction X, forming a plurality of bridge portions 7071, 7072 having minute widths 7091, 7092 in the radial direction X.

[0053] The rotor core 2 is formed with an outer circumferential region 722, a central region 723, and an inner circumferential region 724, in that order from the outer side X1 to the inner side X2 in the radial direction X. The outer circumferential region 722 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner side X2 in the radial direction X, including at least the bridge portions 7071 and 7072. The central region 723 is an annular range extending from the outer circumferential region 722 toward the inner side X2 in the radial direction X, including the magnet insertion hole 704. The inner circumferential region 724 is an annular range extending from the central region 723 toward the inner side X2 in the radial direction X, including the fitting hole 6.

[0054] More specifically, the outer peripheral region 722 of the sixth modification of the first embodiment is an annular range that includes the bridge inner point B at the innermost point X2 in the radial direction X of the bridge portions 7071, 7072. The outer peripheral region 722 also includes, from the outer peripheral surface 21, the magnet outer abutment point 708 at the outermost point X1 in the radial direction X where the permanent magnet 705 abuts against the magnet insertion hole 704 (in other words, the portion of the side portion 742 of the magnet insertion hole 704 that is close to the bridge portion 7072 on the outer side X1 in the radial direction X).

[0055] Regardless of the arrangement and combination of the above-described embodiment 1 and variants 1 to 6 of embodiment 1, the effects of the present disclosure can be achieved by defining the bridge inner point and the magnet outer abutment point, respectively, and specifying the outer peripheral region, the central region, and the inner peripheral region.

[0056] Next, only the main points will be described below regarding application to a vehicle of a rotating electric machine 100 using rotors 101 according to the first embodiment and the first to sixth modifications of the first embodiment. As shown in Fig. 11 , an electric vehicle 150 includes, in an engine compartment, rotating electric machine 100 as a driving motor, a control device 110 for rotating electric machine 100, and a vehicle drive device 130 whose main component is a speed reducer 120. In Fig. 11 , the upper side of electric vehicle 150 is shown as the vehicle rear side CR, and the lower side of electric vehicle 150 is shown as the vehicle front side CF.

[0057] In addition, a battery 140 for supplying power to the vehicle drive device 130 is installed under the floor of the vehicle body. Since the output of the rotating electric machine 100 is the product of the torque and the rotation speed, by using the rotating electric machine 100 of the first embodiment and setting the maximum rotation speed in the normal operating range to 15,000 rpm or more, the torque required by the rotating electric machine 100 can be reduced, and the vehicle drive device 130 equipped with the rotating electric machine 100 can be made smaller and lighter.

[0058] This not only increases the degree of freedom in the placement of vehicle drive device 130, but also saves space in the drive system, expanding the interior space of the vehicle and improving the convenience and comfort of electric vehicle 150. In the application form of the first embodiment, a front-engine, front-drive type vehicle is provided with vehicle drive device 130 in the engine compartment of an EV (electric vehicle). However, a rear-engine, rear-drive type vehicle (not shown) with a vehicle drive device in the lower rear of the vehicle may also be used, or a four-wheel drive (4WD) type vehicle (not shown) with a vehicle drive device in each of the front and rear may also be used. Furthermore, an engine (not shown) may also be used in combination with these to form an HEV (hybrid electric vehicle). The connection and control method of vehicle drive device 130 and the engine may be selected as desired according to the vehicle configuration of electric vehicle 150.

[0059] Next, only the main points will be described below regarding a method for manufacturing rotor 101 of the present embodiment 1 configured as described above. Note that the following example illustrates the case of embodiment 1 in FIGS. 2 and 3 as an example, but it can also be similarly manufactured in the above-described modified examples 1 to 6 of embodiment 1, as well as specific example 1 and specific example 2 of embodiment 1 described below (except for the permanent magnets).

[0060] First, as shown in Figure 12, an electromagnetic steel sheet, which is a crystalline material, is made of a strip- or sheet-shaped substrate 1 with a thickness of 0.2 mm to 0.5 mm. This is then punched out by press working (not shown) into disks with outer circumferential surfaces, fitting holes, and magnet insertion holes to produce a plurality of rotor plate materials 3. If the sheet width of the substrate 1 is large, the rotor plate materials 3 and the stator plate materials (not shown) may be produced from the same substrate 1 by press working.

[0061] Here, a material with an average crystal grain size of less than 50 μm, which is smaller than the average crystal grain size of a normal grain size material, is used as the base material 1. Then, as shown in Fig. 13, a plurality of rotor plate materials 3 are stacked in the axial direction Y, and the rotor plate materials 3 are fastened to each other in the axial direction Y by caulking (not shown) to manufacture the rotor core 2. Note that the fastening method may be welding or adhesive other than caulking.

[0062] The rotor core 2 is divided into an outer circumferential region 22, a central region 23, and an inner circumferential region 24, and each region is annealed to grow grains to a desired average crystal grain size. Here, the outer circumferential region 22 is annealed at a temperature that grows the crystal grains so that the average crystal grain size is smaller than at least either the central region 23 or the inner circumferential region 24 and is less than 50 μm.

[0063] Furthermore, as shown in FIG. 4, the central region 23 is annealed at a temperature that causes grain growth of crystals with an average grain size of 50 μm or more and less than 200 μm, so that a reduction effect can be expected in the total iron loss T, which takes into account both hysteresis loss H and eddy current loss E in the electrical steel sheet.

[0064] Furthermore, the inner peripheral region 24 is annealed at a temperature that causes grain growth so that the average crystal grain size becomes less than 50 μm. In the manufacturing method of the rotor 101 according to the first embodiment, the average crystal grain size in each region has the relationship: central region > inner peripheral region ≥ outer peripheral region.

[0065] After annealing the rotor core 2, permanent magnets 5 are placed in the magnet insertion holes 4 provided in the outer peripheral region 22 and the central region 23, and are fitted with the fitting parts 10 to manufacture the rotor 101. If necessary, a structure or part to prevent the permanent magnets 5 from falling out may be added to the rotor 101.

[0066] In the manufacturing method of the rotor 101 in the first embodiment, as shown in Fig. 13, a plurality of rotor sheet materials 3 are stacked in the axial direction Y and then annealed. This makes it possible to anneal a large number of rotor sheet materials 3 at once, reducing the number of annealing steps required to manufacture the rotor core 2 and achieving the effect of a simple method.

[0067] In addition, in order to obtain the average crystal grain size relationship as described above in each of the outer peripheral region 22, the central region 23, and the inner peripheral region 24, for example, the outer peripheral region 22 and the inner peripheral region 24 may be covered with insulating material during annealing, and grain growth may be actively promoted only in the central region 23, or the material or thickness of the insulating material may be changed between the outer peripheral region 22 and the inner peripheral region 24, and annealing may be performed so that the desired average crystal grain size is obtained in each of the outer peripheral region 22, the central region 23, and the inner peripheral region 24.

[0068] Further, induction annealing may be performed at different temperatures for each of the outer peripheral region 22, the central region 23, and the inner peripheral region 24. Furthermore, in the outer peripheral region 22 and the inner peripheral region 24, in order to remove processing strain during punching of the rotor plate material 3, annealing may be performed at a temperature at which crystal grains do not grow if the average crystal grain size is less than 50 μm.

[0069] Another method for manufacturing the rotor 101 according to the first embodiment will now be described. For example, annealing is performed before the rotor plate materials 3 are stacked in the axial direction Y, that is, after the rotor plate materials 3 are punched as shown in FIG. 12B. Apart from this, the method for manufacturing the rotor 101 is the same as that according to the first embodiment described above. By annealing the rotor plate materials 3 having a thickness of 0.2 mm to 0.5 mm, it is possible to apply an appropriate temperature to each of the outer peripheral region 22, the central region 23, and the inner peripheral region 24.

[0070] Therefore, annealing each rotor plate material 3 individually makes it easier to control the annealing and allows for a more uniform distribution of average crystal grain size than annealing multiple rotor plate materials 3 stacked in the axial direction Y and then achieving a distribution of average crystal grain size in each region. This reduces variations in magnetic properties and strength, allowing the rotor 101 to be made smaller and lighter, thereby enabling the rotating electric machine 100 to achieve high rotational speeds and high performance using a relatively inexpensive or simple manufacturing method. Note that, if the above control is possible, annealing may also be performed for every two or several rotor plate materials 3.

[0071] In the above-described first embodiment and first to sixth variations of the first embodiment, examples have been described in which the present disclosure is applied to an IPM (Intelligent Power Module) rotor and rotating electric machine having magnet insertion holes and permanent magnets housed in the magnet insertion holes, as suitable examples for ensuring resistance to centrifugal force applied to a rotor housing permanent magnets and achieving both high rotation and high performance of a rotating electric machine. However, the scope of application of the present disclosure is not limited to IPM rotors and rotating electric machines. Below, cases other than the IPM type will be described.

[0072] For example, specific example 1 of embodiment 1 will be described with reference to Fig. 14. As shown in Fig. 14, rotor core 2 of rotor 101 is provided with slits 8041, 8042, 8043, and 8044 that function as flux barriers to control the flow of magnetic flux in rotor core 2. The slits have a generally arcuate shape that is convex on the q axis toward the inner side X2 in radial direction X and are arranged in multiple layers in radial direction X. If formed in this manner, the rotor can be used as rotor 101 of a synchronous reluctance rotating electric machine, and the rotating electric machine can be used in a vehicle drive device.

[0073] Furthermore, bridge portions 8071, 8072, 8073, 8074, 8075, 8076, 8077, and 8078 having a minute width in the radial direction X are formed between the outer peripheral surface 21 of the rotor core 2 and each of the slits 8041, 8042, 8043, and 8044 in the radial direction X.

[0074] The rotor core 2 is formed with an outer circumferential region 822, a central region 823, and an inner circumferential region 824, in this order from the outer circumferential side X1 toward the inner circumferential side X2 in the radial direction X. The outer circumferential region 822 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner circumferential side X2 in the radial direction X, and including at least bridge portions 8071, 8072, 8073, 8074, 8075, 8076, 8077, and 8078. The central region 823 is an annular range extending from the outer circumferential region 822 toward the inner circumferential side X2 in the radial direction X, and including slits 8041, 8042, 8043, and 8044. The inner circumferential region 824 is an annular range extending from the central region 823 toward the inner circumferential side X2 in the radial direction X, and including the fitting hole 6.

[0075] More specifically, outer peripheral region 822 in specific example 1 of the first embodiment is an annular range that includes bridge inner points B5, B6, B7, and B8 at the innermost positions X2 in the radial direction X of bridge portions 8071, 8072, 8073, 8074, 8075, 8076, 8077, and 8078 from outer peripheral surface 21. The relationship between the average crystal grain sizes or the crystal materials of each of outer peripheral region 822, central region 823, and inner peripheral region 824 are set in the same manner as in the first embodiment or variations 1 to 6 of the first embodiment.

[0076] A specific example 1 of slits that function as flux barriers in this way is provided with approximately arc-shaped slits 8041 to 8044 that are convex on the q-axis toward the inner side X2 in the radial direction X and are arranged in multiple layers in the radial direction X. Furthermore, in order to improve resistance to the centrifugal force applied to the rotor, an auxiliary bridge portion may be provided that divides the approximately arc-shaped slits arranged in multiple layers in the radial direction X. Furthermore, in order to improve resistance to the centrifugal force applied to the rotor 101, an auxiliary bridge portion may be provided that divides the approximately arc-shaped slits arranged in multiple layers in the radial direction X.

[0077] For example, specific example 2 of embodiment 1 will be described with reference to Fig. 15. As shown in Fig. 15, rotor core 2 of rotor 101 is provided with slits 9041, 9042, 9043, 9044, 9045, 9046, 9047, and 9048 which function as flux barriers for controlling the flow of magnetic flux in rotor core 2. The slits have a generally arc-like shape convex on the q axis toward the inner side X2 in radial direction X and are arranged in multiple layers in radial direction X.

[0078] Furthermore, slits 9041, 9045, slits 9042, 9046, slits 9043, 9047, slits 9044, 9048 are formed by dividing the rotor into two with the q-axis as the boundary. Auxiliary bridge portions 9111, 9112, 9113, 9114 are respectively formed between these slits formed by dividing the rotor into two with the q-axis as the boundary. The number and locations of the auxiliary bridge portions are set appropriately according to the desired strength and magnetic characteristics of rotor core 2. If formed in this manner, the rotor can be used as rotor 101 of a synchronous reluctance rotating electric machine, and a vehicle drive device using this rotating electric machine can be made.

[0079] In addition, bridge portions 9071, 9072, 9073, 9074, 9075, 9076, 9077, and 9078 having a minute width in the radial direction X are formed between the outer peripheral surface 21 of the rotor core 2 and each of the slits 9041, 9042, 9043, 9044, 9045, 9046, 9047, and 9048 in the radial direction X.

[0080] The rotor core 2 is formed with an outer circumferential region 922, a central region 923, and an inner circumferential region 924, in this order from the outer circumferential side X1 toward the inner circumferential side X2 in the radial direction X. The outer circumferential region 922 of the rotor core 2 is an annular range extending from the outer circumferential surface 21 toward the inner circumferential side X2 in the radial direction X, and including at least bridge portions 9071, 9072, 9073, 9074, 9075, 9076, 9077, and 9078. The central region 923 is an annular range extending from the outer circumferential region 922 toward the inner circumferential side X2 in the radial direction X, and including slits 9041, 9042, 9043, 9044, 9045, 9046, 9047, and 9048. The inner circumferential region 924 is an annular range extending from the central region 923 toward the inner circumferential side X2 in the radial direction X, and including the fitting hole 6.

[0081] More specifically, the outer peripheral region 922 of the specific example 2 of the first embodiment is an annular range that includes, from the outer peripheral surface 21, bridge inner points B9, B10, B11, and B12 that are located at the innermost positions X2 in the radial direction X of the bridge portions 9071, 9072, 9073, 9074, 9075, 9076, 9077, and 9078. The relationship between the average crystal grain sizes or the crystal materials of the outer peripheral region 922, the central region 923, and the inner peripheral region 924 are set in the same manner as in the first embodiment or the first to sixth modifications of the first embodiment.

[0082] In addition, the auxiliary bridge portions 9111, 9112, 9113, and 9114 in the central region 923 may have locally smaller crystal grain sizes around them compared to other parts of the central region 923, as long as the relationship between the average crystal grain sizes in each of the outer region 922, the central region 923, and the inner region 924 is within the range in which the relationship described above in embodiment 1 or variants 1 to 6 of embodiment 1 holds.

[0083] By adopting any of the configurations exemplified above, it is possible to improve the resistance of bridge portions or auxiliary bridge portions, etc., to the centrifugal force applied to the rotor 101 to a certain level, thereby achieving the same basic effects as those of the present disclosure. Furthermore, by applying the present disclosure to a rotor of a synchronous reluctance rotating electric machine, in addition to the above-mentioned effects, it is no longer necessary to use rare-earth permanent magnets, which are an expensive and limited resource. This makes it possible to obtain a rotor, rotating electric machine, and vehicle drive unit that excels in terms of structural simplification, cost reduction, and resource conservation.

[0084] According to the rotor of embodiment 1 configured as described above, the rotor includes a rotor core formed by stacking a plurality of rotor plate materials in the axial direction, the rotor core having an outer circumferential region located on the radially outer side of the rotor core, an inner circumferential region located on the radially inner side of the rotor core, and a central region located radially between the outer circumferential region and the inner circumferential region, the outer circumferential region and the central region are provided with a plurality of magnet insertion holes or a plurality of slits for accommodating permanent magnets, and bridge portions are formed between the radially outermost part of the rotor core and the magnet insertion holes or the slits, the outer circumferential region is an annular range from the radially outermost part of the rotor core to include at least the bridge portions in a cross section perpendicular to the axial direction of the rotor core, and the average crystal grain size of the outer circumferential region is smaller than the average crystal grain size of at least either the inner circumferential region or the central region, The bridge portion can be strengthened, and the resistance to centrifugal force and operating characteristics of the rotor in a rotating electrical machine can be improved by an inexpensive or simple manufacturing method.

[0085] Furthermore, according to the rotor of embodiment 1 configured as described above, when the rotor described above is provided with the magnet insertion holes, the outer peripheral region is an annular range in a cross section perpendicular to the axial direction of the rotor core, extending from the radially outermost part of the rotor core to include at least one or both of the radially innermost part of the bridge section or the radially outermost part where the permanent magnet abuts the magnet insertion holes. Therefore, it is possible to increase the strength of at least one or both of the radially innermost part of the bridge section and the radially outermost part of the permanent magnet from the outer peripheral surface, and the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine can be improved by an inexpensive or simple manufacturing method.

[0086] Furthermore, according to the rotor of embodiment 1 configured as described above, the outer peripheral region is an annular range in a cross section perpendicular to the axial direction of the rotor core, extending from the outermost radial part of the rotor core to include the innermost radial part of the bridge portion. This makes it possible to reliably achieve high strength from the outer peripheral surface to the innermost radial part of the bridge portion, and reliably improve the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine using a cheap or simple manufacturing method.

[0087] Furthermore, according to the rotor of embodiment 1 configured as described above, the central region is an annular range from radially inward of the outer peripheral region to the magnet insertion hole or the radially innermost part of the slit, so that the rotor's resistance to centrifugal force and operating characteristics in a rotating electric machine can be improved by an inexpensive or simple manufacturing method.

[0088] Furthermore, according to the rotor of embodiment 1 configured as described above, the average crystal grain size of the outer peripheral region is less than 50 μm, which reliably enables the outer peripheral region to be strengthened, and the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine can be reliably improved by a reliably inexpensive or simple manufacturing method.

[0089] Furthermore, according to the rotor of embodiment 1 configured as described above, the average crystal grain size of the central region is 50 μm or more, so that the reduction in hysteresis loss in the central region can further improve the rotor's resistance to centrifugal force and operating characteristics in a rotating electric machine.

[0090] Furthermore, according to the rotor of embodiment 1 configured as described above, the average crystal grain size in the central region is less than 200 μm, so that the total iron loss in the central region is reduced, thereby further improving the rotor's resistance to centrifugal force and operating characteristics in a rotating electric machine.

[0091] Furthermore, according to the rotor of embodiment 1 configured as described above, the average crystal grain size in the inner region is less than 50 μm, and the relationship in size between the average crystal grain sizes in the outer region, central region and inner region is central region > inner region ≧ outer region, which makes it possible to reliably increase the strength of the inner region, and further improve the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine.

[0092] Furthermore, according to the rotating electric machine of embodiment 1 configured as described above, the stator having the stator winding is rotatably arranged on the inner circumferential side of the stator via an air gap, so that the rotor's resistance to centrifugal force and operating characteristics in the rotating electric machine can be reliably improved.

[0093] Furthermore, according to the vehicle drive device of embodiment 1 configured as described above, the above-described rotating electric machine is provided as a drive motor, and the maximum rotation speed of the rotating electric machine in the normal operating range is set to a value of 15,000 rpm or more, thereby enabling miniaturization, weight reduction, and improved freedom of placement.

[0094] Furthermore, according to the rotor manufacturing method of embodiment 1 configured as described above, the rotor manufacturing method described above includes a punching process of punching an electromagnetic steel plate, which is a crystalline material, to form the rotor plate material; a stacking process of stacking a plurality of the rotor plate materials in the axial direction; and an annealing process of annealing at a temperature that causes grain growth of the crystals of the electromagnetic steel plate that constitutes the rotor plate material, so that the average crystal grain size of the outer peripheral region portion of the rotor plate material is smaller than at least either the average crystal grain size of the inner peripheral region portion or the average crystal grain size of the central region portion.Therefore, the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine can be improved by an inexpensive or simple manufacturing method.

[0095] Furthermore, according to the rotor manufacturing method of embodiment 1 configured as described above, the annealing process is performed so that the average crystal grain size of the outer peripheral region is less than 50 μm, which reliably increases the strength of the outer peripheral region, and reliably improves the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine using a reliably inexpensive or simple manufacturing method.

[0096] Furthermore, according to the rotor of embodiment 1 configured as described above, the annealing process is performed so that the average crystal grain size in the central region is 50 μm or more. Therefore, by reducing the hysteresis loss in the central region, the rotor's resistance to centrifugal force and operating characteristics in a rotating electric machine can be further improved.

[0097] Furthermore, according to the rotor of embodiment 1 configured as described above, the annealing process is performed so that the average crystal grain size of the central region is less than 200 μm. Therefore, by reducing the total iron loss of the central region, the rotor's resistance to centrifugal force and operating characteristics in a rotating electric machine can be further improved.

[0098] Furthermore, according to the rotor of embodiment 1 configured as described above, the annealing process is performed so that the relationship of average crystal grain size among the outer peripheral region, the central region, and the inner peripheral region satisfies the relationship central region > inner peripheral region ≥ outer peripheral region, thereby reliably increasing the strength of the inner peripheral region and further improving the resistance to centrifugal force and operating characteristics of the rotor in a rotating electric machine.

[0099] Furthermore, according to the rotor of the first embodiment configured as described above, the annealing step is performed after the lamination step, thereby improving workability.

[0100] Furthermore, according to the rotor of embodiment 1 configured as described above, the annealing process is performed after the punching process and before the stacking process, so that the relationship in size between the average crystal grain sizes in the outer peripheral region, the central region, and the inner peripheral region can be strictly formed.

[0101] Although exemplary embodiments are described in this disclosure, the various features, aspects, and functions described in the embodiments are not limited to specific embodiments, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, variations in, addition to, or omission of at least one component are included.

[0102] 1 Base material, 100 Rotating electric machine, 101 Rotor, 102 Stator, 110 Control device, 120 Reducer, 130 Vehicle drive device, 140 Battery, 150 Electric vehicle, 2 Rotor core, 3 Rotor plate material, 4, 204, 206, 304, 404, 504, 6041, 6042, 6043, 6044, 704 Magnet insertion hole, 5, 205, 207, 305, 405, 505, 506, 6051, 6052, 6053, 6054, 705 Permanent magnet, 6 Fitting holes, 7, 2071, 2072, 307, 407, 507, 6071, 6072, 6073, 6074, 7071, 7072, 8071, 8072, 8073, 8074, 8075, 8076, 8077, 8078, 9071, 9072, 9073, 9074, 9075, 9076, 9077, 9078 Bridge portion, 8, 2081, 2082, 308, 408, 508, 6081, 6082, 6083, 6084, 708 Magnet outer abutment point, 9, 2091, 2092, 309, 409, 509, 7091, 7092 Width, 10 Fitting parts, 9111, 9112, 9113, 9114 Auxiliary bridge portion, 21 Outer peripheral surface, 22, 222, 322, 422, 522, 622, 722, 822, 922 Outer peripheral region portion, 23, 223, 323, 423, 523, 623, 723, 823, 923 Central region portion, 24, 224, 324, 424, 524, 624, 724, 824, 924 Inner peripheral region portion, 41, 2411, 2412, 341, 44, 541, 6411, 6412, 6413, 6414, 74 Flux barrier, 42, 342, 442, 542, 6421, 6423, 742 Side portion, 743 Gap, 8041, 8042, 8043, 8044, 9041, 9042, 9043, 9044, 9045, 9046, 9047, 9048 Slits, B, B1, B2, B3, B4, B5, B6, B7, B8, B9, B10, B11, B12 Bridge inner points, E Eddy current loss, G, G1, G2 Magnet corners, H Hysteresis loss, T Total iron loss, S1 Linear, S2 Linear, X Radial direction, X1 Outer, X2 Inner, Y Axial direction.

Claims

1. A rotor having a rotor core in which multiple rotor plates are stacked in the axial direction, The rotor core has an outer peripheral region located radially outward, an inner peripheral region located radially inward, and a central region located radially between the outer peripheral region and the inner peripheral region. Multiple magnet insertion holes or multiple slits for housing permanent magnets are provided in the outer peripheral region and the central region. A bridge portion is formed between the outermost radial part of the rotor core and the magnet insertion hole or the slit. The outer peripheral region is an annular area in a cross-section perpendicular to the axial direction of the rotor core, extending from the outermost radial portion of the rotor core to at least the bridge portion. A rotor in which the average grain size of the outer peripheral region is formed to be smaller than at least one of the average grain sizes of the inner peripheral region and the central region.

2. In the rotor according to claim 1, if the magnet insertion hole is provided, The outer peripheral region is an annular area in a cross-section perpendicular to the axial direction of the rotor core, extending from the outermost radial point of the rotor core to at least one or both of the innermost radial point of the bridge portion or the outermost radial point where the permanent magnet abuts the magnet insertion hole. The rotor is an annular region in which the central region extends from radially inward from the outer peripheral region to the innermost radial part of the magnet insertion hole or the slit.

3. The outer peripheral region is an annular area in a cross-section perpendicular to the axial direction of the rotor core, extending from the outermost radial part of the rotor core to the innermost radial part of the bridge portion. The rotor according to claim 1, wherein the central region is an annular range extending from radially inward from the outer peripheral region to the innermost radial part of the magnet insertion hole or the slit.

4. The average grain size of the outer peripheral region is less than 50 μm. The average crystal grain size of the central region is 50 μm or more. The rotor according to any one of claims 1 to 3, wherein the average grain size of the central region is less than 200 μm.

5. The average grain size of the inner circumferential region is less than 50 μm. The relationship between the average grain size of the outer peripheral region, the central region, and the inner peripheral region is as follows: The rotor according to any one of claims 1 to 3, wherein the relationship is such that the central region > the inner circumferential region ≥ the outer circumferential region.

6. The electric motor for driving the rotating electric machine comprises a stator having stator windings and a rotor according to any one of claims 1 to 3, which is rotatably disposed on the inner circumference side of the stator with an air gap between them. A vehicle drive system in which the maximum rotational speed of the rotating electric machine in the normal operating range is set to a value of 15,000 rpm or more.

7. A method for manufacturing a rotor according to any one of claims 1 to 3, A punching process to punch out an electromagnetic steel sheet, which is a crystalline material, to form the plate material for the rotor, A lamination process in which multiple rotor plates are stacked in the axial direction, A method for manufacturing a rotor, comprising: an annealing step of performing annealing at a temperature that causes grain growth of the crystals of the electromagnetic steel sheet constituting the rotor sheet, such that the average crystal grain size of the outer peripheral region of the rotor sheet is smaller than at least one of the average crystal grain size of the inner peripheral region or the average crystal grain size of the central region.

8. The method for manufacturing a rotor according to claim 7, wherein the annealing step is performed such that the average grain size of the outer peripheral region becomes less than 50 μm.

9. The method for manufacturing a rotor according to claim 7, wherein the annealing step is performed such that the average grain size of the central region is 50 μm or more.

10. The method for manufacturing a rotor according to claim 7, wherein the annealing step is performed such that the average grain size of the central region is less than 200 μm.

11. The method for manufacturing a rotor according to claim 7, wherein the annealing step is performed such that the relationship between the average grain size of the outer peripheral region, the central region, and the inner peripheral region is such that the relationship is central region > inner peripheral region ≥ outer peripheral region.

12. The method for manufacturing a rotor according to claim 7, wherein the annealing step is performed after the lamination step.

13. The method for manufacturing a rotor according to claim 7, wherein the annealing step is performed after the punching step and before the lamination step.

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