Rotary electrical machine rotor, rotary electrical machine, in-wheel motor, and vehicle

Abstract

Provided is a rotary electrical machine rotor comprising a magnet, a rotor core into which the magnet is inserted, and a rotor frame which is for fixing the rotor core. The magnet includes main-pole magnets having a magnetization direction that points in the radial direction, and spoke magnets having a magnetization direction that points in the circumferential direction. The rotor core is formed by assembling a plurality of rotor core sheets, and the rotor core sheets are provided with a main-pole magnet slot into which the main-pole magnets are inserted, a spoke magnet slot into which the spoke magnets are inserted, and a back yoke which is formed further on the outer circumferential side than the main-pole magnet slot and the spoke magnet slot. The rotor core sheets each have a plurality of divided core sheets which are adjacent to each other in the circumferential direction and which are disposed at prescribed intervals. The back yoke has a back yoke gap, which is a first gap provided at a position where the spoke magnet slot is formed, and the back yoke gap is formed at least at one location in the rotor core.

Description

Rotor of rotating electric machine, rotating electric machine, in-wheel motor, vehicle

[0001] The present invention relates to a rotor for a rotating electric machine, a rotating electric machine, an in-wheel motor, and a vehicle.

[0002] There is a growing need for smaller, lighter in-wheel motors that consolidate the drivetrain in the wheels of vehicles. This has led to demands for improved torque density in in-wheel motors, as well as lighter, higher torque rotating electrical machines mounted inside the in-wheel motors.

[0003] One known method for reducing the weight of a rotating electric machine is to increase the number of poles of the machine and to thin the stator and rotor in the radial direction. Another known method for increasing the torque of a rotating electric machine is to embed permanent magnets in the rotor core. For example, Patent Document 1 listed below discloses a configuration in which a magnet is composed of a main pole magnet whose principal surfaces face radially of the rotating electric machine and spoke magnets whose principal surfaces face circumferentially of the rotating electric machine, and a back yoke is formed circumferentially connected to the main pole magnet and spoke magnets on the opposite side of the gap.

[0004] International Publication No. 2023 / 286606

[0005] In the magnet arrangement described in Patent Document 1, the back yoke on the opposite gap side from the spoke magnets is a path for magnetic flux that is not necessary for torque generation, and it shorts the south and north poles of the spoke magnets, forming a magnetic circuit through which leakage magnetic flux flows. As a result, when the rotor magnets are magnetized, the magnetizing magnetic flux leaks from this back yoke, which creates the problem of preventing the spoke magnets from being sufficiently magnetized, and this leakage magnetic flux can increase iron loss and result in a decrease in motor efficiency.

[0006] a rotor for a rotating electric machine comprising: a magnet; a rotor core into which the magnet is inserted; and a rotor frame that fixes the rotor core; the magnet includes a main pole magnet whose magnetization direction faces radially and a spoke magnet whose magnetization direction faces circumferentially; the rotor core is formed by assembling a plurality of rotor core sheets; the rotor core sheet comprises main pole magnet slots into which the main pole magnets are inserted, spoke magnet slots into which the spoke magnets are inserted, and a back yoke formed on the outer periphery of the main pole magnet slots and the spoke magnet slots; the rotor core sheet has a plurality of divided core sheets that are adjacent to each other in the circumferential direction and arranged at a predetermined interval; and the back yoke has a back yoke air gap that is a first air gap provided at a position where the spoke magnet slot is formed, and the back yoke air gap is formed in at least one location in the rotor core.

[0007] According to the present invention, it is possible to provide a rotor for a rotating electric machine, a rotating electric machine, an in-wheel motor, and a vehicle that realize improved post-deposition magnetism, reduced iron loss, and improved motor efficiency.

[0008] 1 is a cross-sectional view of a rotating electric machine according to a first embodiment of the present invention; 2 is a cross-sectional view of a rotor for a rotating electric machine according to a first embodiment of the present invention; 3 is a diagram of a divided core sheet according to a first embodiment of the present invention; 4 is a perspective view and a partial enlarged view of a rotor core according to a first embodiment of the present invention; 5 is an explanatory diagram showing the difference in magnetizing magnetic flux between a conventional structure and the present invention; 6 is a partial cross-sectional view of a rotor core showing the difference in leakage magnetic flux during driving between a conventional structure and the present invention; 7 is a partial cross-sectional view of a rotor core showing the flow of magnetizing magnetic flux according to the present invention; 8 is a diagram of two divided core sheets according to a second embodiment of the present invention; 9 is an overall perspective view of a rotor core according to a second embodiment of the present invention; 10 is an overall perspective view and a partial enlarged view of a rotor core according to a third embodiment of the present invention; 11 is a diagram of two divided core sheets according to a fourth embodiment of the present invention; 12 is a cross-sectional view and a partial enlarged view of a rotor and a rotor frame according to a fifth embodiment of the present invention; 13 is a diagram showing the configuration of an in-wheel motor equipped with a rotating electric machine according to a sixth embodiment of the present invention; 14 is a partial cross-sectional view showing the configuration of an in-wheel motor equipped with a rotating electric machine according to the sixth embodiment of the present invention; 15 is a schematic diagram showing the configuration of an electric motorcycle employing an in-wheel motor according to a seventh embodiment of the present invention.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0011] (First embodiment and overall configuration) (Figs. 1 to 3) In describing the configuration of the rotor 10 of the rotating electric machine 1 according to the present invention, the radial direction is a linear direction that perpendicularly intersects with the rotation axis C (Fig. 2) of the rotor 10, and is a radial direction centered on the rotation axis C. The circumferential direction is a circumferential direction centered on the rotation axis C, and is a direction of rotation around the rotation axis C. The axial direction is a linear direction parallel to the rotation axis C. Furthermore, with regard to the inner and outer peripheral sides, the side closer to the rotation axis C is the inner peripheral side, and the side farther from the rotation axis C is the outer peripheral side.

[0012] 1 is a cross section perpendicular to the rotation axis C. The rotating electric machine 1 includes a stator 20 and a rotor 10 rotatably supported by the stator 20 and disposed on the outer periphery of the stator 20. A gap 2, which is a gap having a predetermined distance, is formed between the stator 20 and the rotor 10, so that the stator 20 and the rotor 10 face each other and do not come into contact with each other.

[0013] The rotating electric machine 1 according to the present invention can be applied to either an inner rotor type in which the rotor 10 is rotatably supported on the inner periphery of the stator 20, or an outer rotor type in which the rotor 10 is rotatably supported on the outer periphery of the stator 20.

[0014] The stator 20 has the same rotation axis C as the rotor 10, and includes a stator core 21 formed by laminating a plurality of divided core sheets 30a, and a coil (not shown). The stator 20 has coils of three different phases, for example, U-phase, V-phase, and W-phase, arranged therein in order to generate a rotating magnetic field in the gap 2. Furthermore, the phases of the input current fundamental wave components of the coils of each phase in the stator 20 differ from each other by 120°, thereby generating a rotating magnetic field in the gap 2 and enabling the rotor 10 to rotate.

[0015] A shaft (not shown) or a rotor frame 50 (FIG. 12) having the same center of rotation as the rotor 10 is fixed to the rotor 10. As a result, the rotor 10 is connected to a load via structural members such as the shaft or rotor frame 50, and rotation and torque can be transmitted to the load as the rotor 10 rotates. Note that the rotor frame 50 is preferably made of a non-magnetic material so that magnetic flux does not leak from the rotor 10 to the rotor frame 50.

[0016] The rotor 10 has a rotor core 11 and magnets inserted into magnet slots 13 formed in the rotor core 11. The rotor core 11 is formed by stacking a plurality of divided core sheets 30a in the axial direction. The rotor core 11 may be made of an integrally molded solid member, or may be made of a powder magnetic material such as a dust core that has been compression molded, or may be made of an amorphous metal or a nanocrystalline material.

[0017] 3, the axis passing through the center of each magnetic pole of the rotor 10 is defined as the d-axis, and the axis passing through the boundary of each magnetic pole of the rotor 10 is defined as the q-axis. When the rotor 10 is skewed, the d-axis and the q-axis are defined for each direction of the central axis of each magnetic pole.

[0018] The slots 13 are holes provided in the rotor core 11 for inserting the main pole magnets 14 and spoke magnets 15, which are permanent magnets. The slots 13 have main pole magnet slots 13a into which the main pole magnets 14 on the d-axis are inserted, and spoke magnet slots 13b into which the spoke magnets 15 on the q-axis are inserted. The main pole magnets 14 and spoke magnets 15 are arranged alternately along the circumferential direction. The magnetization direction (magnetization direction) of the main pole magnets 14 is radial. The magnetization direction of the spoke magnets 15 is circumferential.

[0019] The arrangement of the main pole magnet 14 and the spoke magnets 15 is a Halbach arrangement, and in a rotor 10 configured in this manner, for example, magnetic flux entering from the south pole passes through the main pole magnet 14, then passes through the back yoke 12, the spoke magnet 15, the north pole side back yoke 12, and the north pole side main pole magnet 14 in that order (see Figure 7).

[0020] The d-axis core 16 is located in the rotor core 11 closer to the radial gap 2 than the main pole magnet 14. The d-axis core 16 concentrates the magnetic flux of the main pole magnet 14 and the spoke magnets 15, increasing the magnetic flux density in the gap 2. This increases the torque density of the rotating electric machine 1.

[0021] The split core sheet 30a has inter-magnet bridges 17 between the main pole magnet slots 13a and the spoke magnet slots 13b. The inter-magnet bridges 17 are paths through which torque-induced magnetic flux passes through both the main pole magnet 14 and the spoke magnets 15, and are paths through which magnetizing magnetic flux for magnetizing the spoke magnets 15 passes, but they are also paths for leakage magnetic flux that short-circuits the magnetic flux of the magnets inserted in the slots. Furthermore, large stresses are generated in the inter-magnet bridges 17 due to the centrifugal force and electromagnetic force loads acting on the rotor 10. Therefore, it is desirable to make the circumferential width of the inter-magnet bridges 17 as small as possible while ensuring the reliability of the split core sheet 30a, taking into consideration the balance between the magnetic properties related to torque and magnetization and the mechanical strength.

[0022] In Fig. 3, three split core sheets 30a are lined up in the circumferential direction, with the gap-side claw portions 19 side of each split core sheet 30a facing the stator 20 (Fig. 1). Openings 19a are formed between the gap-side claw portions 19. This configuration reduces leakage flux and improves magnetization efficiency.

[0023] The divided core sheet 30a includes a rotor back yoke 12 that forms a path for guiding the magnetic flux of the main pole magnet 14 (FIG. 2) to the adjacent spoke magnets 15 (FIG. 2). The back yoke 12 is provided on the radially opposite side of the rotor core 11 from the side where the gap 2 (FIG. 1) is provided. Circumferentially adjacent divided core sheets 30a have a back yoke air gap 31 between the back yokes 12 on the back yoke 12 side. The back yoke air gap 31 is formed in the spoke magnet slot 13b. The circumferential width of the back yoke air gap 31 may be approximately half the circumferential width of the spoke magnets 15. The back yoke air gap 31 does not need to be air, and may be filled with a non-magnetic material.

[0024] The divided core sheets 30a are stacked in the axial direction to form the rotor core 11 (rotor 10). Each divided core sheet 30a has one pole, i.e., one main pole magnet slot 13a and one d-axis core 16.

[0025] (Fig. 4) The split core 11a is the rotor core 11 for one pole, in which split core sheets 30a (Fig. 3) are laminated. The back yoke air gaps 31 are provided circumferentially, one for each pole, and are provided continuously in the axial direction. Note that it is sufficient that the back yoke air gap 31 is provided in at least one location circumferentially in each spoke magnet slot 13b.

[0026] (FIG. 5) FIG. 5(a) is a partial cross-sectional view of the rotor core 11 showing the magnetizing magnetic flux in a conventional structure, and FIG. 5(b) is a partial cross-sectional view of the rotor core 11 showing the magnetizing magnetic flux in the structure of the present invention.

[0027] In the conventional structure, the main pole magnet 14 and spoke magnets 15 are inserted into the main pole magnet slots 13a and spoke magnet slots 13b in the rotor core 11 formed by an assembly of multiple rotor core sheets 30. The conventional structure, like the configuration of the present invention, has a gap-side claw 19 formed by excluding part of the gap-side bridge instead of a bridge formed on the gap side of the rotor core 11. This structure holds the spoke magnets 15 in place, while the gap between the gap-side claws 19 reduces leakage flux that shorts out the magnetic flux of the permanent magnet.

[0028] The gap side claw portion 19 is able to reduce leakage magnetic flux that short-circuits the magnetic flux of the spoke magnet 15, but since it is also a part where large stress occurs due to the centrifugal force and electromagnetic force load acting on the spoke magnet 15, it is desirable to form it taking into consideration the balance between magnetic properties such as torque and mechanical strength.

[0029] In the conventional structure, the back yoke 12 is formed on the outer periphery of the main pole magnet slot 13a and the spoke magnet slot 13b. In this way, the integrally formed back yoke 12 has low magnetic resistance. Therefore, as shown in Figure 5(a), after inserting the unmagnetized spoke magnets 15 into the spoke magnet slot 13b, when a magnetizer (not shown) is brought close to the rotor 10 from the gap 2 side and a magnetizing current is passed through to generate magnetic flux, part of the magnetic flux can be magnetized by passing through the spoke magnets 15 in the circumferential direction as desired as magnetizing magnetic flux 40, but leakage magnetic flux 41 is also generated.

[0030] The leakage flux 41 passes through the inter-magnet bridges 17 and back yoke 12 that make up the spoke magnet slot 13b, and follows a path that does not penetrate the spoke magnet 15. As a result, the magnetization rate of the spoke magnet 15 may deteriorate, or it may not be possible to magnetize it at all. Furthermore, even if the spoke magnet 15 can be magnetized, a larger magnetizing current is required to compensate for the leaked magnetic flux, which increases the amount of power consumed by the magnetizer, increasing the amount of heat generated by the magnetizer and increasing the cooling time for the magnetizer. This increases the tact time of the rotating electric machine 1, raising concerns about reduced productivity.

[0031] On the other hand, in the configuration of the present invention, the rotor core 11 is formed from multiple divided core sheets 30a that are adjacent to each other in the circumferential direction and arranged at a predetermined interval. A back yoke air gap 31, which is a predetermined gap, is provided in at least one of the multiple spoke magnet slots 13b formed in the circumferential direction of the rotor core 11. The magnetic resistance of the back yoke air gap 31 is the magnetic resistance of air. Therefore, it is greater than the magnetic resistance of the back yoke 12, and the magnetic resistance of the entire axial direction of the rotor core 11 is also higher than in the conventional structure. As a result, when generating the magnetizing magnetic flux 40, leakage magnetic flux 41 as shown in FIG. 5(a) is not generated. Furthermore, even if the back yoke 12 is present in a portion of the circumferential direction of the rotor core 11, magnetic saturation occurs with a small amount of leakage magnetic flux 41, so the leakage magnetic flux 41 is reduced compared to the conventional structure.

[0032] This configuration improves the magnetization rate of the spoke magnets 15 and improves post-magnetization. Furthermore, since the magnetizing current can be reduced compared to conventional structures, the amount of power consumed by the magnetizer can be reduced, thereby reducing the environmental impact due to energy consumption. Furthermore, since the amount of heat generated by the magnetizer can be reduced, the cooling time of the magnetizer can be shortened, and the tact time of the rotating electric machine 1 can be reduced, thereby improving productivity. Specifically, the magnetization rate of the configuration of the present invention is improved by several percent or more compared to conventional structures, and the magnetizing current can be reduced by several percent. Furthermore, since the amount of heat generated by the magnetizer can be reduced by several tens of percent compared to conventional structures, the cooling time can also be shortened by several tens of percent compared to conventional structures. If the cooling time of the magnetizer is the rate-limiting factor in the production process, the present invention improves productivity (the number of rotating electric machines 1 that can be produced per unit time) by several tens of percent compared to conventional structures.

[0033] (FIG. 6) The stator core 21 forming the stator 20 has an annular stator back yoke 22, a plurality of teeth 24 connected to the stator back yoke 22 and provided on the radial side of the gap 2, and coil slots 23 provided between the plurality of teeth 24.

[0034] The stator core 21 may be made of an integrally molded solid member, or may be made of a compressed and molded powder magnetic material such as a dust core, or may be made of an amorphous metal or a nanocrystalline material.

[0035] The coils (not shown) are inserted into the coil slots 23 of the stator 20 and wound around the teeth 24 and the coil slots 23, generating a magnetic field by passing a coil current 43 through them. The coils include an in-slot coil inserted into the coil slots 23, coil ends that span between the coil slots 23 at different positions, and lead wires that input current from an external circuit to connect the coils at different positions.

[0036] In the present invention, it is preferable that the coils be arranged in fractional slot concentrated winding for fractional slots where the number of slots per pole per phase is a fraction. In a stator 20 with fractional slot concentrated winding, the number of slots per pole per phase is a fraction, which is the number of coil slots 23 of the stator 20 divided by the number of coil phases and the number of poles of the rotor 10. In this case, coils of the same phase are inserted into the coil slots 23 of the stator 20 so that they straddle at least two or more consecutive adjacent coil slots 23, thereby forming a rotating magnetic field.

[0037] In the case of a stator 20 with fractional slot concentrated winding, the position (phase) of the stator teeth 24 facing a certain pole of the rotor 10 is different from the position (phase) of the teeth 24 facing the adjacent pole. In other words, the distribution of magnetic flux from a given north pole to an adjacent south pole is different from the distribution of magnetic flux from that south pole to the adjacent north pole. In particular, in fractional slot concentrated winding, when multiple coils of the same phase that continuously straddle adjacent coil slots 23 are considered as one coil group, magnetic flux resulting from the current flowing through these two adjacent coil groups is also generated between these two coil groups. In the conventional structure described above, due to the asymmetry of the magnetic flux distribution between the poles, leakage magnetic flux 42 that straddles multiple poles flows through the rotor back yoke 12. This leakage magnetic flux 42 is different from the magnetic flux that contributes to torque; it generates torque pulsation and increases iron loss in the back yoke 12.

[0038] Furthermore, post-magnetization is difficult with the Halbach magnet arrangement in the conventional structure, and this was addressed by inserting pre-magnetized magnets into the slots. However, because the magnetized magnets are strongly attracted to the core, inserting the magnets into the slots is difficult, and handling is difficult because the magnetized magnets attract and repel each other, and it is also difficult to remove magnetic powder that is produced when the magnets and core are scraped off during the insertion of the magnets into the slots.

[0039] In the present invention, by providing the back yoke air gap 31 in at least one location in each spoke magnet slot 13b, the magnetic resistance of the back yoke air gap 31 is increased, and the effective magnetic resistance in the entire axial direction is increased. Therefore, the leakage magnetic flux 42 that flows through the back yoke 12 across multiple poles can be reduced without reducing the basic performance of the rotating electric machine 1, such as torque and output.

[0040] Furthermore, it is possible to reduce torque pulsation caused by leakage flux 42 and iron loss occurring in the back yoke 12. This improves the quietness of the rotating electric machine 1 and improves the efficiency of the rotating electric machine 1. It also makes it possible to realize a configuration that allows post-magnetization. Specifically, the present invention can reduce iron loss by several percent to 20-something percent compared to the conventional technology, thereby improving efficiency by several tenths of a percent to several percent compared to the conventional technology.

[0041] (Figure 7) In the configuration of the present invention, when the rotating motor 1 is driven, the magnetic flux Φ1 that contributes to the generation of torque flows from the S-pole d-axis core 16S, through the S-pole main pole magnet 14S, back yoke 12S, inter-magnet bridge 17S1, spoke magnet 15, inter-magnet bridge 17N2, back yoke 12N, N-pole main pole magnet 14N, and N-pole d-axis core 16N, in that order.

[0042] (Second embodiment) (FIGS. 8 and 9) The split core sheet 30a may have two or more poles integrated together. In FIG. 8, the split core sheet 30a has a configuration for two poles, including two main pole magnet slots 13a, two d-axis cores 16, and one first spoke magnet slot 15a. The split core sheet 30a may also have three or more poles, for example, three main pole magnet slots 13a, three d-axis cores 16, and two first spoke magnet slots 15a. Split core sheets 30a each having a different number of poles may also be arranged circumferentially. The rotor core 11 may also be configured as a collection of split cores or an integrated core by axially stacking split core sheets 30a each having two or more poles integrated together.

[0043] The spoke magnet slots 13b have a first spoke magnet slot 15a that is formed on the side opposite the gap 2 and is provided at a position where the back yoke 12 that unites two circumferentially adjacent divided core sheets 30a is formed, and a second spoke magnet slot 15b that is provided at a position where the back yoke gap 31 is formed on the side opposite the gap 2. The opening 19a is formed at a position where at least one of the first spoke magnet slot 15a and the second spoke magnet slot 15b is provided, and is located opposite the stator 20 (Figure 6).

[0044] The rotor core 11 may be configured such that multiple divided core sheets 30a are stacked in the axial direction and the axial positions of the second spoke magnet slots 15b are aligned in at least two locations in the circumferential direction. Alternatively, multiple divided core sheets 30a may be stacked in the axial direction and at least one first spoke magnet slot 15a and at least one second spoke magnet slot 15b may be stacked in the axial direction to form an integrated rotor core 11.

[0045] 9, in the rotor core 11, back yoke gaps 31 are provided every other pole in the circumferential direction, with one gap formed for each pole pair consisting of two poles. The back yoke gaps 31 are also formed continuously in the axial direction. Furthermore, gap-side claws 19 are formed on the gap 2 side of the second spoke magnet slots 15b, and openings 19a are formed between adjacent divided core sheets 30a on the gap 2 side.

[0046] With this configuration, even if magnetizing flux is generated after unmagnetized spoke magnets 15 are inserted into spoke magnet slots 15a, 15b, no leakage flux is generated that does not penetrate the spoke magnets 15. Furthermore, because the magnetic resistance of the back yoke air gap 31 is high, leakage flux is reduced compared to conventional structures. This also makes it possible to improve the magnetization rate of the spoke magnets 15, improve post-magnetization, reduce the magnetizing current, reduce the amount of power consumed by the magnetizer, reduce the environmental load due to energy consumption, reduce the heat generated by the magnetizer, shorten the cooling time of the magnetizer, reduce the tact time of the rotating electric machine 1, and improve productivity.

[0047] (Third embodiment) (Fig. 10) Enlarged view B is a diagram showing in detail the configuration in which multiple divided core sheets 30a are stacked in the axial direction with a one-pole offset from each other in the rotor core 11. The multiple divided core sheets 30a are stacked in the axial direction while the circumferential pole positions of each phase are shifted by one pole in the circumferential direction, and are thereby rotated to form an integrated rotor core 11. As a result, the first spoke magnet slots 15a and the second spoke magnet slots 15b (Fig. 8) are arranged alternately in the axial direction.

[0048] In this configuration, for example, when a certain spoke magnet slot is used as a reference, the back yoke 12 is provided in odd-numbered layers from the bottom in the axial direction, and the back yoke air gap 31 is provided in even-numbered layers. Alternatively, the back yoke 12 is provided in even-numbered layers, and the back yoke air gap 31 is provided in odd-numbered layers.

[0049] As a result, when magnetizing magnetic flux is generated, it passes through the inter-magnet bridges 17 and back yoke air gap 31 that make up the spoke magnet slot 13b, so no leakage magnetic flux 41 is generated that does not penetrate the spoke magnet 15. In addition, because the magnetic resistance of the back yoke air gap 31 is high, leakage magnetic flux 41 is reduced compared to the conventional structure.

[0050] The extent to which the magnetic resistance of the back yoke 12 increases depends on the ratio of the back yoke air gap 31 to the back yoke 12, but for example, in the configuration shown in Figure 10, the back yoke 12 that forms the spoke magnet slots becomes magnetically saturated (magnetic resistance is about twice as high) at half the amount of magnetic flux compared to conventional structures. By adopting such a configuration, it is possible to achieve the same effects as described above. Furthermore, because the rotor 10 is an integrated rotor core 11, the number of parts can be reduced compared to when it is divided into split cores 11a (Figures 4 and 9), and productivity can be improved.

[0051] (Fourth embodiment) (Fig. 11) The circumferential width of the back yoke air gap 31 may be equal to or greater than the circumferential width of the spoke magnets 15. In Fig. 8, the convex portions 12a protrude from the back yoke 12 with the back yoke air gap 31 between them, but in the embodiment of Fig. 11, these convex portions 12a are not provided. This makes it possible to further increase the magnetic resistance of the back yoke air gap 31, contributing to a reduction in leakage magnetic flux 41 (Fig. 5) and an improvement in the magnetization rate.

[0052] Fifth Embodiment (FIG. 12) Enlarged view C shows in detail the configuration of the rotor frame 50 and the ring-shaped spring 60. The ring-shaped spring 60 has a ring-shaped spring protrusion 61. The rotor core 11 is fixed by the ring-shaped spring 60, the ring-shaped spring protrusion 61, and the rotor frame 50, which is a non-magnetic material. As a result, the rotor 10 is connected to the load via the ring-shaped spring 60 and the rotor frame 50, and the rotation and torque of the rotor 10 can be efficiently transmitted to the load.

[0053] The ring-shaped spring 60 has predetermined spring characteristics and may be a spring integrally molded into a ring shape or a spring bent into a substantially C-shape. The ring-shaped spring 60 is inserted into the gap between the rotor 10 and the rotor frame 50 and is compressed and deformed by the rotor 10 and the rotor frame 50, generating static friction forces at the contact points between the rotor 10 and the ring-shaped spring 60 and at the contact points between the rotor frame 50 and the ring-shaped spring 60. This integrates the rotor 10 and the rotor frame 50.

[0054] The circumferential position of the ring-shaped spring protrusion 61 is not limited, as long as it is in a position that contacts the back yoke 12 on the d-axis of the rotor 10. By fixing the rotor 10 with the rotor frame 50 and the ring-shaped spring 60, a core-frame gap 62, which is a predetermined gap, can be formed between the rotor core 11 and the rotor frame 50. The configuration is such that the circumferential position of the core-frame gap 62 coincides with the circumferential position of the back yoke gap 31 at least at one point.

[0055] The coolant can be allowed to enter the core-frame gap 62, improving the cooling performance of the rotating electrical machine 1. In particular, the coolant that has entered the core-frame gap 62 can further enter the back yoke gap 31 of the rotor 10, thereby directly cooling the spoke magnets 15, which are prone to heat generation due to the high frequency magnetic flux that tends to flow into them at positions close to the gap 2, and suppressing temperature increases. This also prevents a decrease in torque due to a decrease in residual magnetic flux density caused by magnet heat generation, and the possibility of irreversible demagnetization of the magnets.

[0056] 9, the back yoke 12 and the back yoke gaps 31 are alternately arranged in the axial direction, allowing the back yoke 12 to function as cooling fins. This increases the heat dissipation area, suppresses temperature increases in the spoke magnets 15, which tend to generate heat, and prevents torque reduction due to a decrease in residual magnetic flux density and irreversible demagnetization of the magnets.

[0057] Sixth Embodiment (FIGS. 13 and 14) The in-wheel motor 70 includes a rotor frame 50 and a stator frame (not shown) that secures the stator 20. The in-wheel motor 70 has a high power density configuration due to the rotor 10 being configured with a Halbach magnet arrangement that combines the main pole magnets 14 and spoke magnets 15, as described above. By adopting the configuration of the present invention, the in-wheel motor 70 achieves good post-magnetization of the inserted permanent magnets, shortening the takt time of the rotor 10 manufacturing process and reducing the power required for magnetization. Furthermore, due to its high power density, the in-wheel motor 70 is lighter and uses less material than conventional in-wheel motors with the same power output. Therefore, an in-wheel motor 70 that achieves high power output with less power can be provided at low cost. Furthermore, iron loss generated in the back yoke 12 described above can be reduced, enabling highly efficient driving.

[0058] Seventh Embodiment (FIG. 15) An in-wheel motor 70 having a rotor 10 of a rotating electric machine may be mounted on both the front and rear wheels of an electric motorcycle 80, which is a two-wheeled vehicle, or may be mounted on only the front wheel or only the rear wheel. The in-wheel motor 70 of the present invention can also be applied to, for example, four-wheeled vehicles and compact mobility vehicles. This makes it possible to provide an electric motorcycle 80 that achieves high power density, low-cost production, reduced iron loss, and highly efficient drive, thereby contributing to reduced power consumption, reduced environmental impact, and improved cruising range.

[0059] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0060] (1) In the rotor 10 of a rotating electric machine 1, the rotor 10 comprises a magnet, a rotor core 11 into which the magnet is inserted, and a rotor frame 50 that fixes the rotor core 11, the magnet including a main pole magnet 14 whose magnetization direction faces radially and a spoke magnet 15 whose magnetization direction faces circumferentially, the rotor core 11 being formed by assembling a plurality of rotor core sheets 30, the rotor core sheet 30 comprising a main pole magnet slot 13a into which the main pole magnet 14 is inserted, a spoke magnet slot 13b into which the spoke magnet 15 is inserted, and a back yoke 12 formed on the outer periphery of the main pole magnet slot 13a and the spoke magnet slot 13b, the rotor core sheet 30 has a plurality of divided core sheets 30a that are adjacent to each other in the circumferential direction and arranged at a predetermined interval, the back yoke 12 has a back yoke air gap 31 that is a first air gap provided at the position where the spoke magnet slot 13b is formed, and the back yoke air gap 31 is formed in at least one location in the rotor core 11. By doing so, it is possible to provide the rotor 10 of the rotating electrical machine 1 that achieves improved post-deposition magnetism, low iron loss, and improved motor efficiency.

[0061] (2) The spoke magnet slots 13b include a first spoke magnet slot 15a provided at a position where the back yoke 12 that integrates two circumferentially adjacent divided core sheets 30a is formed, and a second spoke magnet slot 15b provided at a position where the back yoke gap 31 is formed. This allows for the application of a configuration in which two divided core sheets 30a are connected, contributing to improved productivity of the rotor 10 of the rotating electric machine 1.

[0062] (3) The rotor core 11 is formed by stacking a plurality of divided core sheets 30a in the axial direction. This configuration makes it possible to provide a rotor core 11 that achieves improved post-deposition magnetism, reduced iron loss, and improved motor efficiency.

[0063] (4) The rotor core 11 is formed by stacking a plurality of divided core sheets in the axial direction, thereby reducing leakage flux compared to conventional rotors and providing the rotor 10 for the integrated rotating electric machine 1.

[0064] (5) The rotor core 11 has openings 19a facing the stator 20 at positions where at least one of the first spoke magnet slots 15a and the second spoke magnet slots 15b is provided. This reduces leakage flux and improves the magnetization rate.

[0065] (6) The circumferential width of the back yoke gap 31 is equal to or greater than the circumferential width of the spoke magnets 15. This further reduces leakage flux and improves the magnetization rate.

[0066] (7) The rotor core 11 is fixed by the rotor frame 50 and the ring-shaped spring 60, which has a predetermined spring characteristic and is integrally molded in a ring shape or C-shape, and a second gap 62 is provided between the rotor core 11 and the rotor frame 50. In this way, a refrigerant can enter the second gap 62, thereby improving the cooling performance of the rotating electric machine 1.

[0067] (8) At least one circumferential position of the second gap 62 coincides with the circumferential position of the back yoke gap 31. This improves the cooling performance of the spoke magnets 15.

[0068] (9) The rotor frame 50 is made of a non-magnetic material, which allows the rotation and torque of the rotor 10 to be efficiently transmitted to the load.

[0069] (10) The rotating electric machine includes a rotor 10 having the configuration of the present invention and a stator 20 facing the rotor 10 of the rotating electric machine 1 across a predetermined gap 2. In this way, a rotating magnetic field is generated in the rotor 10 of the rotating electric machine 1.

[0070] (11) The stator 20 has coil slots 23 into which coils are inserted, and the coil slots 23 are fractional slots such that the number of slots per pole per phase is a fraction, and coils of the same phase are inserted into the coil slots 23 across at least two or more adjacent coil slots. In this way, the configuration of the present invention can be realized.

[0071] (12) An in-wheel motor 70 is employed that includes the rotating electric machine 1 having the configuration of the present invention, a rotor frame 50, and a stator frame that fixes the stator. This makes it possible to provide an in-wheel motor 70 that is low in power, high in output, and low in cost.

[0072] (13) A vehicle is employed that includes the rotor 10 of the rotating electric machine 1 having the configuration of the present invention and the in-wheel motor 70. In this way, the present invention can be applied to vehicles such as an electric motorcycle 80, for example.

[0073] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted.

[0074] REFERENCE SIGNS LIST 1 rotating electric machine 2 gap 10 rotor 11 rotor core 11a split core 11b core end 12 back yoke 12a convex portion 13 magnet slot 13a main pole magnet slot 13b spoke magnet slot 14 main pole magnet 15 spoke magnet 15a first spoke magnet slot 15b second spoke magnet slot 16 d-axis core 17 inter-magnet bridge 19 gap side claw portion 19a opening 20 stator 21 stator core 22 stator back yoke 23 coil slot 24 teeth 30 rotor core sheet 30a split core sheet 31 back yoke gap 31a circumferential width 40 magnetizing magnetic flux 41 leakage magnetic flux 42 leakage magnetic flux 43 coil current 50 rotor frame 60 ring-shaped spring 61 Ring-shaped spring protrusion 62 Core-frame gap 70 In-wheel motor 80 Electric motorcycle C Rotation axis Φ1 Magnetic flux contributing to torque

Claims

1. A rotor for a rotating electric machine comprising: a magnet; a rotor core into which the magnet is inserted; and a rotor frame that fixes the rotor core, wherein the magnet includes a main pole magnet whose magnetization direction faces radially and a spoke magnet whose magnetization direction faces circumferentially, the rotor core being formed by assembling a plurality of rotor core sheets, the rotor core sheet comprising: a main pole magnet slot into which the main pole magnet is inserted, a spoke magnet slot into which the spoke magnet is inserted, and a back yoke formed on the outer periphery of the main pole magnet slot and the spoke magnet slot, wherein the rotor core sheet has a plurality of divided core sheets that are adjacent to each other in the circumferential direction and arranged at a predetermined interval, and the back yoke has a back yoke air gap that is a first air gap provided at a position where the spoke magnet slot is formed, and the back yoke air gap is formed in at least one location in the rotor core.

2. A rotor for a rotating electric machine as described in claim 1, wherein the spoke magnet slots include a first spoke magnet slot provided at a position where the back yoke that unites two circumferentially adjacent divided core sheets is formed, and a second spoke magnet slot provided at a position where the back yoke gap is formed.

3. A rotor for a rotating electric machine according to claim 1, wherein the rotor core is formed by stacking the plurality of divided core sheets in the axial direction.

4. A rotor for a rotating electric machine according to claim 2, wherein the rotor core is formed by stacking a plurality of the divided core sheets one on top of the other in the axial direction.

5. A rotor for a rotating electric machine according to claim 2, wherein the rotor core has an opening facing the stator at a position where at least one of the first spoke magnet slot and the second spoke magnet slot is provided.

6. A rotor for a rotating electric machine according to claim 1, wherein the circumferential width of the back yoke gap is equal to or greater than the circumferential width of the spoke magnets.

7. A rotor for a rotating electric machine as claimed in claim 1, wherein the rotor core is fixed by the rotor frame and a ring-shaped spring having predetermined spring characteristics and integrally molded into a ring shape or molded into a C-shape, and a second air gap is provided between the rotor core and the rotor frame.

8. A rotor for a rotating electric machine according to claim 7, wherein the position of the second air gap in the circumferential direction coincides with the position of the back yoke air gap in the circumferential direction at least at one point.

9. A rotor for a rotating electric machine according to claim 7, wherein the rotor frame is made of a non-magnetic material.

10. A rotating electric machine comprising the rotor of claim 1 and a stator facing the rotor of said rotating electric machine across a predetermined gap.

11. A rotating electric machine according to claim 10, wherein the stator has coil slots into which coils are inserted, the coil slots being fractional slots such that the number of slots per pole per phase is a fraction, and the coils of the same phase are inserted into the coil slots across at least two or more adjacent coil slots.

12. An in-wheel motor comprising the rotating electric machine according to claim 10, the rotor frame, and a stator frame for fixing the stator.

13. A vehicle comprising the rotor of the rotating electric machine according to claim 1 and the in-wheel motor according to claim 12.

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