Rotating electric machine

Abstract

A magnet part (42) is oriented such that a radial component of the magnetic flux on a d axis, which is the magnetic pole center, is greater than a circumferential component, and the circumferential component of the magnetic flux on a q-axis, which is the magnetic pole boundary, is greater than the radial component. A stator core (52) has an annular back yoke and a plurality of teeth (54) protruding from the back yoke in the radial direction. The teeth do not have a flange part at a leading end section (54a), and a stator coil (51) can be disposed up to the leading end section. A conducting wire of the stator coil is spirally wound around the outer periphery of the teeth to the leading end section.

Description

Rotating electrical machine Cross-reference to related applications

[0001] This application is based on Japanese Application No. 2024-166180 filed on September 25, 2024, the contents of which are incorporated herein by reference.

[0002] This disclosure relates to a rotating electrical machine.

[0003] For example, there is a motor (see Patent Document 1) including a stator having a plurality of teeth on an outer peripheral portion and stator coils wound around each tooth, and a rotor having a plurality of magnets annularly arranged so as to face the stator. The magnets are formed such that their easy magnetization directions sequentially change angles within the magnets, and the magnetic distribution thereof is a first magnet from the circumferential end portion, which is a portion facing adjacent magnets, to the opposing surface portion, which is the center of the magnet and faces the stator, and a second magnet whose magnetic distribution is from the center of the opposing surface portion toward the circumferential end portion are alternately arranged annularly. According to the above configuration, it is said that the magnetic distribution generated by the magnets on the stator side can be made closer to a sine wave.

[0004] Japanese Patent Application Laid-Open No. 2015-89224

[0005] By the way, the teeth of the stator core of the motor (rotating electrical machine) described in Patent Document 1 have flange portions at their tip ends. The present disclosure's inventors have noticed that when the magnetic distribution generated by the magnets on the stator side is close to a sine wave and the tooth portions have flange portions, magnetic flux is likely to leak between the flange portions. Furthermore, since the tooth portions have flange portions, the amount of stator coils that can be arranged on the tooth portions decreases, and the removability of the stator coils from the teeth deteriorates when the stator coils are reused as resources.

[0006] This disclosure has been made to solve the above problems, and its main object is to reduce magnetic flux leakage between teeth, increase the amount of stator coils arranged on the teeth, and improve the removability of the stator coils from the teeth in a rotating electrical machine in which the magnetic distribution generated by magnets on the stator side is made closer to a sine wave.

[0007] A first means for solving the above problem is a rotating electric machine comprising: a rotor having a magnet section containing a plurality of magnetic poles and supported to be rotatable; and a stator having a stator core and stator coils and arranged opposite to the rotor, wherein the magnet section is oriented such that the radial component of the magnetic flux is greater than the circumferential component at the d-axis, which is the center of the magnetic pole, and the circumferential component of the magnetic flux is greater than the radial component at the q-axis, which is the boundary of the magnetic pole; the stator core has an annular back yoke and a plurality of teeth projecting radially from the back yoke; the teeth do not have a flange at their tip, and the stator coils can be arranged up to the tip; and the conductors of the stator coils are wound spirally around the outer circumference of the teeth up to the tip.

[0008] According to the above configuration, the rotating electric machine has a magnetic section containing multiple magnetic poles and a rotor that is rotatably supported.

[0009] Here, the magnet section is oriented such that the radial component of the magnetic flux is greater than the circumferential component at the d-axis, which is the center of the magnetic pole, and the circumferential component of the magnetic flux is greater than the radial component at the q-axis, which is the boundary of the magnetic pole. As a result, the magnetic distribution generated on the stator side by the magnet section can be made closer to a sine wave, thereby suppressing noise and vibration during rotor rotation. However, if the magnetic distribution generated on the stator side by the magnet section is close to a sine wave and the teeth have flanges, magnetic flux tends to leak between the flanges.

[0010] In this respect, the multiple teeth projecting radially from the back yoke do not have flanges at their tips. Therefore, magnetic flux leakage between the teeth can be reduced. Furthermore, it is possible to arrange the stator coils up to the tips of the teeth, and the conductors of the stator coils are wound spirally around the outer circumference of the teeth up to the tips. Therefore, the amount of stator coils that can be placed on the teeth can be increased. And, when reusing the stator coils as resources, the absence of flanges at the tips of the teeth improves the ease of removing the stator coils from the teeth. Thus, in a rotating electric machine in which the magnetic distribution generated on the stator side by the magnet section approaches a sine wave, significant effects can be achieved, such as reducing magnetic flux leakage between the teeth, increasing the amount of stator coils that can be placed on the teeth, and improving the ease of removing the stator coils from the teeth.

[0011] The above-mentioned and other purposes, features and advantages of this disclosure will become clearer from the following detailed description with reference to the accompanying drawings. The drawings are: Figure 1, an exploded perspective view showing the rotor and stator of a rotating electric machine; Figure 2, a perspective view showing the inside of the stator of Figure 1; Figure 3, a schematic diagram showing a comparison between the teeth of a comparative example and the teeth of this embodiment; Figure 4, a perspective view showing the assembly of the stator coil; Figure 5, a perspective view showing the removal of the stator coil; Figure 6, a cross-sectional view of the rotor; Figure 7, a partially enlarged view showing an enlarged portion of Figure 6; and Figure 8, a diagram showing the relationship between the electric angle and magnetic flux density for the magnet of this embodiment. Figure 9 shows the relationship between the electric angle and magnetic flux density for the comparative example magnet, Figure 10 shows the flow of magnetic flux near the tip of the teeth of the comparative example, Figure 11 shows the flow of magnetic flux near the tip of the teeth of the reference example, Figure 12 shows the amount of magnetic flux near the tip of the teeth of the comparative example, Figure 13 shows the amount of magnetic flux near the tip of the teeth, Figure 14 shows the amount of magnetic flux from near the tip to near the base of the teeth, Figure 15 is a schematic diagram showing the cross-section of the conductor, and Figure 16 shows the strands. Figure 17 is a schematic diagram showing the twist of the stator coil wound on the bobbin and the teeth, Figure 18 is a schematic diagram showing the assembly and removal of the bobbin to the teeth, Figure 19 is a schematic diagram showing an example of modification of the stator coil wound on the bobbin and the teeth, Figure 20 is a schematic diagram showing an example of modification of the assembly and removal of the bobbin to the teeth, Figure 21 is a partially enlarged view showing an example of modification of the magnet part, Figure 22 is a schematic diagram showing the flow of magnetic flux in the magnet part of Figure 22, and Figure 23 is Figure 24 is a schematic diagram showing the assembly configuration of the stator coil, Figure 25 is a schematic diagram showing the assembly configuration of the stator coil in the reference example, Figure 26 is a schematic diagram showing the coil pitch of a short-winding stator coil, Figure 27 is a schematic diagram showing the coil pitch of a full-winding stator coil in the comparative example, Figure 28 is a schematic diagram showing the relationship between the number of magnetic poles, the number of slots, and the coil thickness, and Figure 29 is a schematic diagram showing the relationship between the number of magnetic poles, the number of slots, and the coil thickness in the reference example.

[0012] The following describes one embodiment of a rotating electric machine mounted on a vehicle, with reference to the drawings. The rotating electric machine can be used, for example, as a motor, generator, and MG (Motor Generator). It can be widely used for industrial, automotive, home appliance, office automation equipment, amusement machines, and the like.

[0013] As shown in Figures 1 and 2, the rotating electric machine 10 according to this embodiment is a synchronous multiphase AC motor and has an outer rotor structure (external rotation structure). The rotating electric machine 10 is equipped with a rotating shaft 11 (only a portion is shown). In the following description, the direction in which the rotating shaft 11 extends is called the axial direction, the direction extending radially from the center of the rotating shaft 11 is called the radial direction, and the direction extending circumferentially with respect to the rotating shaft 11 is called the circumferential direction.

[0014] The rotating electric machine 10 comprises a rotor 40 and a stator 50. Both the rotor 40 and the stator 50 are arranged coaxially with the rotating shaft 11 and assembled in a predetermined order in the axial direction to constitute the rotating electric machine 10.

[0015] The rotor 40 has a rotor carrier 41 formed in a hollow cylindrical shape and an annular magnet portion 42 provided radially inward of the rotor carrier 41. The rotor carrier 41 is substantially cup-shaped and functions as a magnet holding member. The rotor carrier 41 has a cylindrical magnet holding portion 43. The magnet portion 42 is attached to the inner circumferential surface of the magnet holding portion 43. In other words, the rotor 40 is an SPM (Surface Permanent Magnet) rotor with the magnet portion 42 arranged on its surface. The rotor carrier 41 is fixed to the rotation shaft 11. As a result, the rotor 40 rotates integrally with the rotation shaft 11.

[0016] The rotating shaft 11 and the rotor 40 are rotatably supported in a housing (not shown). This allows the rotor 40 to rotate freely within the housing.

[0017] The magnet section 42 is composed of multiple magnets arranged radially inside the magnet holding section 43, with their magnetic poles alternating along the circumferential direction. However, the details of the magnet section 42 will be described later.

[0018] The stator 50 is located radially inward of the rotor 40. The stator 50 includes a frame 59, a stator coil 51, and a stator core 52.

[0019] The frame 59 is roughly cup-shaped and has a flange portion 59a, a cylindrical portion 59b, and a bottom portion 59c. The stator core 52 is attached to the outer circumference of the cylindrical portion 59b.

[0020] The stator core 52 is formed in an annular shape from laminated steel plates made of soft magnetic material. The stator core 52 has an annular back yoke 53 and a plurality of teeth 54 projecting radially from the back yoke 53. The teeth 54 are formed, for example, in a rectangular prism shape (columnar shape) and are formed with the same thickness (approximately the same thickness) from the base to the tip. That is, the teeth 54 do not have a flange at the tip portion 54a. The tip portion 54a is a predetermined portion of the tooth 54 near the very tip. The teeth 54 can be arranged from the base portion 54c (see Figure 14) to the tip portion 54a.

[0021] The stator coil 51 is formed by winding a wire in a spiral shape. The wire of the stator coil 51 is wound spirally (annularly) around the outer circumference of each tooth 54. The wire of the stator coil 51 is wound from the base 54c to the tip 54a of the tooth 54. In other words, the stator coil 51 is positioned from the base 54c to the tip 54a of the tooth 54.

[0022] The stator coil 51 is positioned opposite the annular magnet section 42 with a predetermined air gap in between. The stator coil 51 consists of multiple phase windings. Each of these phase windings is constructed by connecting multiple conductors arranged in the circumferential direction at a predetermined pitch. In this embodiment, a three-phase winding of U, V, and W phases and a three-phase winding of X, Y, and Z phases are used, and by using two sets of these three-phase windings, the stator coil 51 is configured as a six-phase winding.

[0023] Figure 3 is a schematic diagram showing a comparison between the teeth 154 of the comparative example and the teeth 54 of this embodiment. The teeth 154 of the comparative example have a flange portion 154b at the tip portion 154a. Therefore, the conductor wire 60 cannot be wound up to the tip portion 154a, and the conductor wire 60 is wound up to the part of the teeth 154 that is closer to the base portion 54c than the flange portion 154b. The teeth 54 of this embodiment do not have a flange portion 154b at the tip portion 54a. Therefore, the conductor wire 60 can be wound up to the tip portion 54a, and the conductor wire 60 is wound up to the tip portion 54a on the teeth 54. Consequently, the number of turns of the conductor wire 60 on the teeth 54 can be increased compared to the number of turns of the conductor wire 60 on the teeth 154. Alternatively, the number of turns of the wire 60 around tooth 54 can be made the same as the number of turns of the wire 60 around tooth 154, so that the thickness of the wire 60 around tooth 54 is greater than the thickness of the wire 60 around tooth 154. In other words, the amount of wire 60 placed around tooth 54 can be increased compared to the amount of wire 60 placed around tooth 154.

[0024] Figure 4 is a perspective view showing the assembly configuration of the stator coil 51. The stator coil 51 is formed in an annular shape by pre-winding the conductor 60 in a spiral. Since the teeth 54 do not have a flange portion 154b, the annular stator coil 51 can be assembled to the outer circumference of the teeth 54 from the radial direction. That is, each phase winding of the stator coil 51 is wound around the teeth 54. As shown in Figure 24, the inner surface 51a of the annular stator coil 51 and the outer surface 54d of the teeth 54 can be made parallel, making it easy to assemble the stator coil 51 to the teeth 54. In the reference example shown in Figure 25, it is difficult to make the inner surface 51a of the annular stator coil 51 and the outer surface 54d of the teeth 54 parallel, making it difficult to assemble the stator coil 51 to the teeth 54. The stator coil 51 can also be formed by sequentially winding the conductor 60 in a spiral around the outer circumference of the teeth 54.

[0025] Furthermore, in this embodiment, as shown in Figure 26, the stator coil 51 is a short-section winding, and the coil pitch is less than an electrical angle of 180°. That is, the spacing between adjacent phase windings of the same phase is less than an electrical angle of 180°. There is no overlap between phase windings at the coil end, and the height Hc1 of the coil end can be reduced. By reducing the height Hc1 of the coil end, the resistance of the coil end can be reduced. In the comparative example shown in Figure 27, the stator coil 51 is a full-section winding, and the coil pitch is an electrical angle of 180°. In order to avoid overlap between phase windings at the coil end, the height Hc2 of the coil end is higher than the height Hc1.

[0026] Furthermore, in this embodiment, as shown in Figure 28, the number of magnetic poles of the magnet section 42 is made less than the number of slots (i.e., the number of teeth 54), thereby reducing the central angle θ1 formed by the centerlines of adjacent teeth 54. This makes it possible to reduce the thickness Wc1 of the stator coil 51 and lower the height of the coil end. Consequently, the resistance of the coil end can be reduced. In the reference example shown in Figure 29, the number of magnetic poles of the magnet section 42 is greater than the number of slots (i.e., the number of teeth 54), and the central angle θ2 formed by the centerlines of adjacent teeth 54 is greater than the central angle θ1. As a result, the thickness Wc2 of the stator coil 51 is greater than the thickness Wc1, and the height of the coil end cannot be lowered.

[0027] Figure 5 is a perspective view showing how the stator coil 51 is removed. Since the teeth 54 do not have a flange portion 154b, the annular stator coil 51 can be removed radially from the teeth 54. As shown in Figure 24, the inner surface 51a of the annular stator coil 51 and the outer surface 54d of the teeth 54 can be made parallel, making it easy to remove the stator coil 51 from the teeth 54. In the reference example shown in Figure 25, it is difficult to make the inner surface 51a of the annular stator coil 51 and the outer surface 54d of the teeth 54 parallel, making it difficult to remove the stator coil 51 from the teeth 54. Note that even when the stator coil 51 is formed by sequentially winding the conductor 60 spirally around the outer circumference of the teeth 54, the stator coil 51 can be removed radially from the teeth 54.

[0028] Figure 6 is a cross-sectional view of the rotor 40. Figure 7 is a magnified view of a part of Figure 6. For the sake of explanation, the number of magnetic poles of the magnet section 42 shown in Figures 6 and 7 is less than the number of magnetic poles of the magnet section 42 shown in Figure 1. The magnet section 42 uses permanent magnets whose easy magnetization axis is controlled by orientation. The magnetic flux density of the magnet section 42 is 1.0 [T] or higher.

[0029] The magnet section 42 is annular in shape and is located inside the rotor carrier 41 (more specifically, radially inside the magnet holding section 43). The magnet section 42 has a first magnet 91 and a second magnet 92, each being anisotropic magnet with different magnetic poles. The first magnet 91 and the second magnet 92 are arranged alternately in the circumferential direction. The first magnet 91 is the magnet that becomes the north pole in the rotor 40, and the second magnet 92 is the magnet that becomes the south pole in the rotor 40. The first magnet 91 and the second magnet 92 are permanent magnets made of rare earth magnets such as neodymium magnets.

[0030] In each magnet 91 and 92, the magnetization direction extends in an arc shape between the d-axis, which is the center of the magnetic pole, and the q-axis, which is the boundary of the magnetic pole. In each magnet 91 and 92, the magnetization direction is radial on the d-axis side and circumferential on the q-axis side. That is, the magnet section 42 is oriented such that the radial component of the magnetic flux is greater than the circumferential component on the d-axis, and the circumferential component of the magnetic flux is greater than the radial component on the q-axis. In the magnet section 42, the magnetic flux flows in an arc shape between adjacent N and S poles due to each magnet 91 and 92, so the magnetic path is longer compared to, for example, a radial anisotropic magnet. Therefore, as shown in Figure 8, the magnetic flux density distribution is close to a sine wave. As a result, unlike the magnetic flux density distribution of a radial anisotropic magnet shown as a comparative example in Figure 9, the magnetic flux can be concentrated at the magnetic pole position, and the torque of the rotating electric machine 10 can be increased. In Figures 8 and 9, the horizontal axis represents the electric angle, and the vertical axis represents the magnetic flux density. Furthermore, in Figures 8 and 9, the 90° on the horizontal axis represents the d-axis (i.e., the magnetic pole center), and the 0° and 180° on the horizontal axis represent the q-axis.

[0031] Furthermore, the sinusoidal matching ratio of the magnetic flux density distribution should be, for example, 40% or higher. In this way, the amount of magnetic flux in the central part of the waveform can be reliably improved compared to using radially or parallel-oriented magnets with a sinusoidal matching ratio of around 30%. Moreover, if the sinusoidal matching ratio is 60% or higher, the amount of magnetic flux in the central part of the waveform can be reliably improved compared to a magnetic flux concentration arrangement called a Halbach arrangement.

[0032] In the comparative example shown in Figure 9, the magnetic flux density changes abruptly near the q-axis. The steeper the change in magnetic flux density, the greater the eddy currents generated in the stator coil 51. In contrast, in this embodiment, the magnetic flux density distribution is close to a sine wave. Therefore, the change in magnetic flux density near the q-axis is smaller than the change in magnetic flux density of a radial anisotropic magnet. This makes it possible to suppress the generation of eddy currents.

[0033] Figure 10 shows the flow of magnetic flux near the tip 154a of the comparative example tooth 154. Figure 10 shows the results of a simulation modeling the magnet part 42 and the tooth 154. Note that the conductor wire 60 has been omitted for simplicity of the model. In the magnet part 42, magnetic flux is generated near the d-axis (i.e., the center of the magnetic pole) in a direction perpendicular to the magnetic pole surface, and this magnetic flux takes the shape of an arc, moving further away from the d-axis as it moves away from the magnetic pole surface. The magnetic flux perpendicular to the magnetic pole surface is stronger. For this reason, if the tooth 154 has a flange part 154b at the tip 154a, the distance between the flange parts 154b (i.e., the distance between the teeth 154) becomes narrower. Consequently, as shown by the white arrows, magnetic flux is more likely to leak between the flange parts 154b.

[0034] Figure 11 shows the flow of magnetic flux near the tip 54a of the tooth 54 in the reference example. Figure 11 shows the results of a simulation using a model of the magnet part 42 and the tooth 54. Note that the conductor wire 60 has been omitted for simplicity of the model. The magnet part 42 is the same as the magnet part 42 in Figure 10. Since the tooth 54 does not have a flange 154b at the tip 54a, it is possible to suppress the narrowing of the spacing between the teeth 54. Therefore, even when the magnet part 42 is used, leakage of magnetic flux between the teeth 54 can be suppressed. Note that even in this embodiment in which the conductor wire 60 is wound up to the tip 54a of the tooth 54, the effect of eliminating the flange 154b is generally the same as in the reference example in Figure 11.

[0035] Figure 12 shows the amount of magnetic flux near the tip 154a of the comparative example tooth 154. In this figure, magnetic flux is represented by lines, and the more lines there are, the greater the amount of magnetic flux. Because the tooth 154 has a flange 154b at the tip 154a, the magnetic flux passes more easily through the flange 154b, and the amount of magnetic flux passing through the conductor 60 near the tip 154a is reduced.

[0036] Figure 12 shows the amount of magnetic flux near the tip 154a of the comparative example tooth 154. In this figure, magnetic flux is represented by lines, and the more lines there are, the greater the amount of magnetic flux. Because the tooth 154 has a flange 154b at the tip 154a, the magnetic flux passes more easily through the flange 154b, and the amount of magnetic flux passing through the conductor 60 near the tip 154a is reduced.

[0037] Figure 13 shows the amount of magnetic flux near the tip 54a of the tooth 54 in this embodiment. In this figure, magnetic flux is represented by lines, and the more lines there are, the greater the amount of magnetic flux. Since the tooth 54 does not have a flange 154b at the tip 54a, the magnetic flux can easily pass through the conductor 60. As a result, as shown by circle A, the amount of magnetic flux passing through the conductor 60 near the tip 54a increases, and the eddy current loss W in the conductor 60 tends to be large. The eddy current loss W is expressed by the following formula: W ∝ 1 / ρ・f^2・B^2・d^2. ρ is the resistivity, f is the frequency, B is the magnetic flux density, and d is the width of the conductor cross-section. f^2 represents f squared.

[0038] Figure 14 shows the amount of magnetic flux from the tip 54a to the base 54c of the tooth 54. As shown by circle A, the amount of magnetic flux from the magnet part 42 passing through the conductor 60 wound around the outer circumference of the tip 54a of the tooth 54 is greater than the amount of magnetic flux from the magnet part 42 passing through the conductor 60 wound around the outer circumference of the base 54c of the tooth 54, as shown by circle B. For this reason, eddy current loss W tends to be large in the conductor 60 in the part close to the magnet part 42.

[0039] Figure 15 is a schematic diagram showing a cross-section of a conductor 60. The conductor 60 has a bundle of multiple strands 61. Therefore, the width d1 of the cross-section of a single strand 61 can be made smaller than the width d0 of the cross-section of the conductor 60. This makes it possible to reduce the eddy current loss W of the conductor 60. Each strand 61 has a conductor 61a and a strand coating 61b. The conductor 61a is formed in a linear shape from, for example, copper, aluminum, or an alloy thereof. The strand coating 61b is formed from, for example, a resin (insulator) and covers the conductor 61a. The conductor 60 has a common coating 60a that covers the bundled strands 61. The common coating 60a is formed from, for example, a resin (insulator) different from the resin that forms the strand coating 61b. The coefficient of linear expansion of the strand coating 61b and the coefficient of linear expansion of the common coating 60a are different.

[0040] Figure 16 is a schematic diagram showing the twisting of the wire strands 61. Multiple wire strands 61 are twisted together in a spiral shape.

[0041] The embodiment described in detail above has the following advantages.

[0042] The magnet section 42 is oriented such that the radial component of the magnetic flux is greater than the circumferential component at the d-axis, which is the center of the magnetic pole, and the circumferential component of the magnetic flux is greater than the radial component at the q-axis, which is the boundary of the magnetic pole. As a result, the magnet section 42 can bring the magnetic distribution generated on the stator 50 side closer to a sine wave, thereby suppressing noise and vibration when the rotor 40 rotates.

[0043] ・The plurality of teeth 54 protruding radially from the back yoke 53 do not have a flange portion 154b at the tip portion 54a. Therefore, magnetic flux leakage between the teeth 54 can be reduced. Further, the stator coil 51 can be arranged up to the tip portion 54a of the teeth 54, and the conductor 60 of the stator coil 51 is spirally wound around the outer periphery of the teeth 54 up to the tip portion 54a. Therefore, the amount of the stator coil 51 arranged on the teeth 54 can be increased. And when the stator coil 51 is reused as a resource, since there is no flange portion 154b at the tip portion 54a of the teeth 54, the removability of the stator coil 51 from the teeth 54 can be improved. Thus, in the rotating electric machine 10 in which the magnetic distribution generated by the magnet portion 42 on the stator 50 side approaches a sine wave, it is possible to reduce magnetic flux leakage between the teeth 54, increase the amount of the stator coil 51 arranged on the teeth 54, and improve the removability of the stator coil 51 from the teeth 54, and thus a remarkable effect can be achieved.

[0044] ・Since there is no flange portion 154b at the tip portion 54a of the teeth 54, the magnetic flux density of the magnetic flux passing through the conductor 60 wound around the tip portion 54a of the teeth 54 close to the magnet portion 42 becomes high, and the eddy current loss W of the conductor 60 wound around the tip portion 54a becomes large. The eddy current loss W is proportional to the square of the width d of the cross section of the conductor. In this regard, the conductor 60 has a plurality of bundled strands 61. Therefore, the width d1 of the cross section of one strand 61 can be reduced, and the eddy current loss W can be reduced.

[0045] ・Since there is no flange portion 154b at the tip portion 54a of the teeth 54, the magnetic flux passing through the conductor 60 close to the magnet portion 42 increases. When the magnetic flux passing through the conductor 60 close to the magnet portion 42 is large, the eddy current loss W in the conductor 60 close to the magnet portion 42 becomes large. In such a configuration, since the conductor 60 is constituted by a plurality of bundled strands 61, the effect of reducing the eddy current loss W becomes high. When the conductor 60 is constituted by a plurality of strands 61, the copper ratio (conductor ratio) decreases. However, with the configurations shown in FIGS. 24, 26, and 28, the height Hc1 of the coil end can be reduced, and the resistance of the coil end can be reduced, so that the decrease in the copper ratio can be compensated.

[0046] - When the linear expansion rate of the strand coating 61b is the same as that of the common coating 60a, there is a possibility that both the strand coating 61b and the common coating 60a will crack in a specific use environment. In this regard, since the linear expansion rate of the strand coating 61b is different from that of the common coating 60a, even if one coating cracks in a specific use environment, the other coating is less likely to crack and remains.

[0047] - Since each strand 61 is twisted, there are portions on one strand 61 where the directions of magnetic field application are opposite to each other. Therefore, the back electromotive voltage caused by the magnetic field is canceled out, and the eddy current can be reduced.

[0048] - When a magnet portion 42 that generates a sinusoidal magnetic distribution is adopted on the stator 50 side, if a magnetic material exists between the magnet portion 42 and the stator 50, the sinusoidal magnetic distribution generated on the stator 50 side may be distorted. In this regard, the magnet portion 42 adopts a SPM rotor arranged on the surface of the rotor 40, and the teeth 54 do not have a flange portion 154b at the tip portion 54a. Therefore, it becomes easier to maintain the sinusoidal magnetic distribution, and the effect of suppressing noise and vibration during the rotation of the rotor 40 becomes remarkable.

[0049] - When the tip portion 54a of the teeth 54 has a flange portion 154b, the higher the magnetic flux density of the magnet portion 42, the more likely magnetic flux leakage occurs between the flange portions 154b. In this regard, since the magnetic flux density of the magnet portion 42 is as high as 1.0 T or more, the effect of reducing magnetic flux leakage due to the teeth 54 not having a flange portion 154b at the tip portion 54a becomes high.

[0050] Incidentally, the above embodiment can also be implemented with the following modifications. For the same parts as those in the above embodiment, the same reference numerals are used, and the description thereof is incorporated by reference.

[0051] - The magnetic flux density of the magnet portion 42 may be less than 1.0 [T]. The plurality of strands 61 do not have to be twisted in a spiral shape. The linear expansion rate of the strand coating 61b and the linear expansion rate of the common coating 60a may be the same. The conducting wire 60 may be a single-core wire composed of one conductor.

[0052] As shown in Figure 17, the stator 50 is equipped with a bobbin 70 around which a wire 60 is wound, and one bobbin 70 may be attached to each tooth 54. With this configuration, as shown in Figure 18, the stator coil 51 can be assembled to one tooth 54 by attaching the bobbin 70 around which the wire 60 is wound to the tooth 54. The stator coil 51 can be removed from the tooth 54 by removing the bobbin 70 around which the wire 60 is wound to the tooth 54. This improves the ease of assembling the stator coil 51 to the tooth 54 and the ease of removing the stator coil 51 from the tooth 54. Furthermore, since one bobbin 70 is attached to each tooth 54, the stator coil 51 can be assembled and removed on a tooth-by-teeth basis, making it easier to handle the stator coil 51.

[0053] As shown in Figure 19, the stator 50 is equipped with a bobbin 71 on which the wire 60 is wound, and one bobbin 71 may be attached to every two teeth 54. With this configuration, as shown in Figure 20, the stator coil 51 can be assembled to two teeth 54 by attaching the bobbin 71 on which the wire 60 is wound to two teeth 54. The stator coil 51 can be removed from two teeth 54 by removing the bobbin 71 on which the wire 60 is wound to two teeth 54. This improves the ease of assembling the stator coil 51 to the teeth 54 and the ease of removing the stator coil 51 from the teeth 54. Furthermore, since one bobbin 71 is attached to every two teeth 54, the stator coil 51 can be assembled and removed in units of two teeth, making it easier to handle the stator coil 51.

[0054] - A bundled bobbin can be used that is attached to all the teeth 54 of the stator core 52 at once. The bundled bobbin is divided into two parts in the axial direction and has a tooth fitting portion that fits into each tooth 54. After attaching the two-part bundled bobbin to the stator core 52 from both sides in the axial direction, a wire 60 is wound around the outer circumference of the tooth fitting portion to form the stator coil 51. Even with this configuration, the wire 60 can be removed radially while leaving the bundled bobbin in place.

[0055] As shown in Figure 21, the magnet section 42 may be configured using a magnet arrangement called a Halbach arrangement. That is, the magnet section 42 has a first magnet 131 whose magnetization direction (direction of magnetic poles) is radial and a second magnet 132 whose magnetization direction (direction of magnetic poles) is circumferential, with the first magnets 131 arranged at predetermined intervals in the circumferential direction, and the second magnets 132 arranged between adjacent first magnets 131 in the circumferential direction. The first magnets 131 and the second magnets 132 are permanent magnets made of rare earth magnets such as neodymium magnets.

[0056] The first magnets 131 are arranged circumferentially spaced apart from each other such that the poles on the side facing the stator 50 (radially inward) alternate between being north poles and south poles. The second magnets 132 are arranged next to each first magnet 131 such that the orientation of their circumferential magnetic poles alternates between being opposite. In this case as well, the magnet section 42 is oriented such that the radial component of the magnetic flux in the d-axis is greater than the circumferential component, and the circumferential component of the magnetic flux in the q-axis is greater than the radial component.

[0057] Furthermore, a magnetic body 133 made of a soft magnetic material is arranged on the radially outer side of the first magnet 131, that is, on the side of the magnet holding portion 43 of the rotor carrier 41. For example, the magnetic body 133 may be made of electromagnetic steel sheet, soft iron, or powdered iron core material. Each magnet 131, 132 and the magnetic body 133 are fixed to each other, for example, by adhesive. In the magnet portion 42, the radially outer side of the first magnet 131 is on the opposite side from the stator 50, and the magnetic body 133 is provided on the side opposite to the stator 50 (anti-stator side) of the radial sides of the first magnet 131.

[0058] A key 134 is formed on the outer circumference of the magnetic body 133 as a protrusion that projects radially outward, i.e., toward the magnet holding portion 43 of the rotor carrier 41. A key groove 135 is formed on the inner circumferential surface of the magnet holding portion 43 as a recess for accommodating the key 134 of the magnetic body 133. The protruding shape of the key 134 and the groove shape of the key groove 135 are the same, and the same number of key grooves 135 are formed corresponding to the keys 134 formed on each magnetic body 133. The engagement of the key 134 and the key groove 135 suppresses circumferential (rotational) misalignment between the first magnet 131 and the second magnet 132 and the rotor carrier 41.

[0059] In the magnet section 42, the magnetic flux density at the first magnet 131 can be increased by arranging the first magnet 131 and the second magnet 132 alternately. Therefore, in the magnet section 42, a concentration of magnetic flux on one side can be created, thereby strengthening the magnetic flux on the side closer to the stator 50.

[0060] Furthermore, by arranging the magnetic material 133 radially outward of the first magnet 131, that is, on the side opposite the stator, partial magnetic saturation radially outward of the first magnet 131 can be suppressed, and consequently, demagnetization of the first magnet 131 caused by magnetic saturation can be suppressed. As a result, it is possible to increase the magnetic force of the magnet section 42. In essence, the magnet section 42 of this embodiment is configured such that the part of the first magnet 131 that is prone to demagnetization is replaced with the magnetic material 133.

[0061] As shown in Figure 22, a magnetic material 133 is provided between the magnetic pole surface of the first magnet 131 and the inner circumferential surface of the magnet holder 43 on the anti-stator side of the first magnet 131, allowing magnetic flux to pass through the magnetic material 133. Therefore, magnetic saturation in the magnet holder 43 can be suppressed, and resistance to demagnetization is improved. Note that, as shown in Figure 23, a configuration without the magnetic material 133 can also be adopted.

[0062] The rotor 40 may be an IPM (Interior Permanent Magnet) rotor in which permanent magnets are embedded inside the rotor 40. In that case, the magnetic part is composed of the permanent magnets and the magnetic material surrounding them. The rotating electric machine 10 may also have an inner rotor structure (internal rotation structure).

[0063] Furthermore, the above embodiments and their modifications can be combined and implemented to the extent possible.

[0064] The following describes characteristic configurations extracted from each embodiment and each modification described above. [Configuration 1] A rotating electric machine (10) comprising: a rotor (40) rotatably supported and having a magnet section (42) including a plurality of magnetic poles; a stator (50) having a stator core (52) and stator coils (51) and arranged opposite to the rotor, wherein the magnet section is oriented such that the radial component of the magnetic flux is greater than the circumferential component at the d-axis, which is the center of the magnetic pole, and the circumferential component of the magnetic flux is greater than the radial component at the q-axis, which is the boundary of the magnetic pole; the stator core has an annular back yoke (53) and a plurality of teeth (54) projecting radially from the back yoke; the teeth do not have a flange at their tip (54a), and the stator coils can be arranged up to the tip; and the conductors (60) of the stator coils are wound spirally around the outer circumference of the teeth up to the tip. [Configuration 2] The rotating electric machine according to Configuration 1, wherein the conductor has a plurality of bundled strands (61). [Configuration 3] The rotating electric machine according to Configuration 2, wherein the amount of magnetic flux from the magnet part passing through the conductor wound around the outer circumference of the tip of the teeth is greater than the amount of magnetic flux from the magnet part passing through the conductor wound around the outer circumference of the base (54c) of the teeth. [Configuration 4] The rotating electric machine according to Configuration 2 or 3, wherein the strands have an insulating strand coating (61b) on their outer surface, the conductor has an insulating common coating (60a) on its outer surface, and the linear expansion coefficient of the strand coating and the linear expansion coefficient of the common coating are different. [Configuration 5] The rotating electric machine according to any one of Configurations 2 to 4, wherein the plurality of strands are twisted in a spiral shape. [Configuration 6] The rotating electric machine according to any one of Configurations 1 to 5, comprising a bobbin (70) on which the conductor is wound, with one bobbin attached to each of the teeth. [Configuration 7] The rotating electric machine according to any one of Configurations 1 to 6, wherein the magnet portion is arranged on the surface of the rotor. [Configuration 8] The rotating electric machine according to any one of Configurations 1 to 7, wherein the magnetic flux density of the magnet portion is 1.0 T or more.[Configuration 9] The stator coil has a plurality of phase windings, the plurality of phase windings are wound around the plurality of teeth, and the spacing between adjacent phase windings of the same phase is less than an electrical angle of 180°, the rotating electric machine according to Configuration 2 or 3. [Configuration 10] The number of magnetic poles of the magnet section is less than the number of teeth, the rotating electric machine according to any one of Configurations 1 to 9.

[0065] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A rotating electric machine (10) comprising: a rotor (40) having a magnet section (42) containing multiple magnetic poles and supported to be rotatable; a stator (50) having a stator core (52) and stator coils (51) and positioned opposite the rotor, wherein the magnet section is oriented such that the radial component of the magnetic flux is greater than the circumferential component at the d-axis, which is the center of the magnetic pole, and the circumferential component of the magnetic flux is greater than the radial component at the q-axis, which is the boundary of the magnetic pole; the stator core has an annular back yoke (53) and a plurality of teeth (54) projecting radially from the back yoke; the teeth do not have a flange at their tip (54a), and the stator coils can be positioned up to the tip; and the conductors (60) of the stator coils are spirally wound around the outer circumference of the teeth up to the tip.

2. The rotating electric machine according to claim 1, wherein the conductor has a plurality of bundled strands (61).

3. The rotating electric machine according to claim 2, wherein the amount of magnetic flux from the magnet portion passing through the conductor wound around the outer circumference of the tip portion of the teeth is greater than the amount of magnetic flux from the magnet portion passing through the conductor wound around the outer circumference of the base portion (54c) of the teeth.

4. The rotating electric machine according to claim 2 or 3, wherein the individual wires have an insulating individual wire coating (61b) on their outer surface, the conductor has an insulating common coating (60a) on its outer surface, and the coefficient of thermal expansion of the individual wire coating and the coefficient of thermal expansion of the common coating are different.

5. The rotating electric machine according to claim 2 or 3, wherein the plurality of strands are twisted in a spiral shape.

6. The rotating electric machine according to any one of claims 1 to 3, comprising a bobbin (70) on which the conductor wire is wound, wherein one bobbin is attached to each of the teeth.

7. The rotating electric machine according to any one of claims 1 to 3, wherein the magnet portion is arranged on the surface of the rotor.

8. The rotating electric machine according to any one of claims 1 to 3, wherein the magnetic flux density of the magnet portion is 1.0 T or more.

9. The rotating electric machine according to claim 2 or 3, wherein the stator coil has a plurality of phase windings, the plurality of phase windings are wound around the plurality of teeth, and the spacing between adjacent phase windings of the same phase is less than an electrical angle of 180°.

10. The rotating electric machine according to claim 8, wherein the number of magnetic poles of the magnet portion is less than the number of teeth.

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