Rotor and rotating electric machine

Abstract

To improve a structure that suppresses the temperature rise of a permanent magnet embedded in a rotor.SOLUTION: A rotor has a shaft extending along the central axis, an iron core to which the shaft is fixed, and magnets forming magnetic poles in the circumferential direction of the iron core. The magnets are arranged in each of a plurality of layers at different radial positions of the iron core. The magnets are divided into a plurality of sections in the axial direction through the iron core, and the number of sections in the axial direction varies according to the surrounding environment.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotor and a rotating electric machine. [Background technology]

[0002] For example, in motors used in electric vehicles such as EVs, HEVs, and PHEVs, overheating of the motor leads to a decrease in performance and reliability, so reducing heat generation is an important issue. Conventionally, technologies to reduce heat generation in motors have been studied.

[0003] Motors used in electric vehicles, for example, include motors that employ an interior permanent magnet rotor in which permanent magnets are embedded. It is known that such motors generate heat due to eddy currents that occur in the permanent magnets while in operation. Patent Document 1 discloses an invention that reduces eddy current loss in the magnets and prevents increases in magnet temperature that cause demagnetization by dividing the permanent magnets in the direction along the rotor's rotation axis (hereinafter referred to as the axial direction). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-220440 Summary of the Invention [Problem to be solved by the invention]

[0005] When dividing a permanent magnet in the axial direction, it is possible to arrange the divided magnets at a fixed size so that the temperature of the permanent magnet remains below the desired maximum magnet temperature. Magnets positioned at both axial ends tend to have a lower magnet temperature than the average due to their good cooling efficiency, while magnets positioned in the axial center tend to have a higher magnet temperature than the average due to their poor cooling efficiency. For this reason, the axial center has the highest magnet temperature, and the optimal number of divisions is determined for the axial center. However, increasing the number of divisions increases the number of production processes, leading to increased costs.

[0006] Furthermore, in a rotor made up of multiple magnets, magnets arranged on the outer diameter side of the rotating shaft are more susceptible to the influence of demagnetizing fields than magnets arranged on the inner diameter side.

[0007] In the past, for example, in a configuration in which multiple magnets are arranged radially, no consideration had been given to a structure that could suppress temperature without increasing the number of divisions too much, and there was room for improvement in the structure that suppresses temperature rise of permanent magnets.

[0008] An object of the present invention is to provide a rotating electric machine having an improved structure for suppressing temperature rise of permanent magnets embedded in a rotor. [Means for solving the problem]

[0009] A rotor according to one aspect of the present invention includes a shaft extending along a central axis, an iron core to which the shaft is fixed, and magnets that form magnetic poles in the circumferential direction of the iron core, the magnets being arranged in a plurality of layers at different radial positions of the iron core, and the magnets being divided into a plurality of axial sections that penetrate the iron core in the axial direction. The magnet with a high loss density has a larger number of divisions than the magnet with a low loss density. .

[0014] The rotor according to the above aspect includes: The magnets arranged in the layers with higher loss density among the plurality of layers are divided into a larger number of parts than the magnets arranged in the layers with lower loss density among the plurality of layers. .

[0015] The present invention The rotor according to one aspect of the present invention comprises: A rotor includes a shaft extending along a central axis, an iron core to which the shaft is fixed, and magnets that form magnetic poles in the circumferential direction of the iron core, the magnets being arranged in a plurality of layers at different radial positions of the iron core, the magnets penetrating the iron core in the axial direction and divided into a plurality of magnets in the axial direction, and the magnets that are easily demagnetized have a larger number of divisions than the magnets arranged between the magnets that are easily demagnetized. .

[0016] The present invention The rotor according to one aspect of the present invention comprises: A rotor having a shaft extending along a central axis, an iron core to which the shaft is fixed, and magnets forming magnetic poles in the circumferential direction of the iron core, the magnets being arranged in a plurality of layers at different radial positions of the iron core, the magnets penetrating the iron core in the axial direction and divided into a plurality of pieces in the axial direction, the magnets having gaps at both ends being divided into a greater number of pieces than the magnets arranged between the magnets having gaps at both ends, .

[0017] A rotating electric machine according to one aspect of the present invention includes the rotor and a stator disposed radially outside the rotor with an air gap interposed therebetween. [Effects of the Invention]

[0018] According to one aspect of the present invention, it is possible to provide a rotating electric machine having an improved structure for suppressing a temperature rise of a permanent magnet embedded in a rotor. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of a motor according to a first embodiment of the present invention. [Figure 2] 2 is an enlarged view of a part of the cross-sectional view shown in FIG. 1 in the motor according to the first embodiment of the present invention. FIG. [Figure 3] FIG. 3 is a perspective view of the portion shown in FIG. 2. [Figure 4] 2 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to the first embodiment of the present invention. FIG. [Figure 5] FIG. 10 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to a fourth embodiment of the present invention. [Figure 8] 1. FIG. 9 is an enlarged view of a part of the cross-sectional view shown in FIG. 1 in a motor according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, in order to make the description easier to understand, structures and elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, the same elements will be given the same reference numerals in the drawings. Note that the shapes, dimensions, etc. of each element shown in the drawings are shown schematically and do not represent the actual shapes, dimensions, etc.

[0021] First Embodiment FIG. 1 is a cross-sectional view of a motor according to a first embodiment of the present invention. The motor 1 of the first embodiment is an example of a rotating electric machine. The motor 1 is an inner rotor type motor. FIG. 1 shows a cross-section perpendicular to the rotation axis Ax of the motor 1. In FIG. 1, the direction in which the rotation axis Ax of the motor 1 extends is perpendicular to the plane of the page.

[0022] Unless otherwise specified, the direction along the extension of the rotation axis Ax, i.e., the direction parallel to the rotation axis Ax, is simply referred to as the "axial direction." Furthermore, the radial direction centered on the rotation axis Ax is simply referred to as the "radial direction." Furthermore, the circumferential direction centered on the rotation axis Ax, i.e., around the central axis J, is simply referred to as the "circumferential direction." In the axial direction, the side pointed to by the arrow indicating the axial direction in Figure 3 (described later) is referred to as the "one axial side," and the opposite side is referred to as the "other axial side." In the radial direction, the side closer to the rotation axis Ax is referred to as the "radially inner side," and the side away from the rotation axis Ax is referred to as the "radially outer side."

[0023] The motor 1 has a rotor 2 and a stator 3. The rotor 2 has an iron core 4, a shaft 5, and permanent magnets 6. The shaft 5 is coaxial with the rotation axis Ax and extends in the axial direction. The rotor 2 is cylindrical and coaxial with the rotation axis Ax. The rotor 2 is an example of an embedded magnet rotor in which the permanent magnets 6 are embedded. The stator 3 is an example of a stator.

[0024] The stator 3 is cylindrical and coaxial with the rotation axis Ax. The stator 3 houses the rotor 2 in a space on the radially opposite side. The stator 3 is arranged radially outward from the rotor 2 with a gap between them. On the inner periphery of the stator 3, multiple teeth 3a are arranged at equal intervals in the circumferential direction, each protruding radially inward toward the rotation axis Ax. The spaces between adjacent teeth 3a form slots 3b. Stator coils are housed in the slots 3b.

[0025] The motor 1 controls the current flowing through the stator coil to sequentially switch the magnetic field of the stator 3, causing the rotor 2 to rotate around the rotation axis Ax by the attractive or repulsive force with the magnetic field of the permanent magnet 6 arranged on the rotor 2.

[0026] The iron core 4 of the rotor 2 is a cylindrical member formed, for example, by laminating punched silicon steel plates in the axial direction. An insulating adhesive is interposed between the individual silicon steel plates that make up the iron core 4, so that the individual silicon steel plates are insulated from one another. The iron core 4 is coaxial with the rotation axis Ax. A shaft 5 is fixed to the axial center of the iron core 4 along the rotation axis Ax. The shaft 5 is fixed, for example, by being inserted into the iron core 4. The shaft 5 is rotatably supported by bearings.

[0027] The rotor 2 of the first embodiment is an eight-pole rotor, and a plurality of permanent magnets 6 are arranged in a predetermined arrangement on the iron core 4 of the rotor 2 so as to form eight main poles at equal intervals along the circumferential direction. The permanent magnets 6 are arranged so that adjacent main poles in the circumferential direction of the rotor 2 have opposite polarities.

[0028] Figure 2 is an enlarged view of a portion of the cross-sectional view shown in Figure 1. Figure 2 shows one of the eight main poles. The other poles are the same as those in Figure 2, so illustration and repeated explanation will be omitted. Figure 3 is a perspective view of the portion shown in Figure 2.

[0029] The iron core 4 of this embodiment has through holes 7a, 7b, 7c, and 7d that accommodate the permanent magnets 6. The through holes 7a, 7b, 7c, and 7d pass through the iron core 4 in the axial direction. The through hole 7a accommodates the permanent magnet 6a of the permanent magnets 6. The through hole 7b accommodates the permanent magnet 6b of the permanent magnets 6. The through hole 7c accommodates the permanent magnet 6c of the permanent magnets 6. The through hole 7d accommodates the permanent magnet 6d of the permanent magnets 6.

[0030] Although the through holes 7a, 7b, 7c, and 7d have different orientations and sizes, they have similar shapes, so the shape of the through hole 7a will be described as a representative, and descriptions of the through holes 7b, 7c, and 7d will be omitted.

[0031] The through holes 7a are arranged such that the radially outer sides are offset counterclockwise by an angle of 90 degrees or less in the circumferential direction from the direction parallel to the radial direction. The cross-sectional shape of the through holes 7a is a shape that extends in this direction.

[0032] Through hole 7b is disposed at a position offset clockwise in the circumferential direction relative to through hole 7a. Through hole 7b is disposed in a direction offset by an angle of 90 degrees or less clockwise in the circumferential direction with respect to a direction parallel to the radial direction, and the cross-sectional shape of through hole 7b is a shape extending in this direction.

[0033] The through holes 7c are arranged radially outward of the through holes 7a. The through holes 7c are arranged so that the radially outer side is offset by an angle of up to 90 degrees counterclockwise in the circumferential direction from the direction parallel to the radial direction. The cross-sectional shape of the through holes 7c is a shape that extends in this direction.

[0034] Through hole 7d is disposed radially outward of through hole 7b. Through hole 7d is disposed at a position shifted clockwise in the circumferential direction relative to through hole 7c. Through hole 7d is disposed in a direction shifted by an angle of 90 degrees or less clockwise in the circumferential direction with respect to a direction parallel to the radial direction. The cross-sectional shape of through hole 7a is a shape extending in this direction.

[0035] In this embodiment, permanent magnets 6a and 6b are located at approximately the same radial position and are referred to as the first layer, while permanent magnets 6c and 6d are located at approximately the same radial position and are referred to as the second layer. Permanent magnets 6a and 6a are arranged radially inward of permanent magnets 6c and 6d. As described above, in this embodiment, the magnets are arranged in two layers in a two-layer arrangement, but the present invention is not limited to this and may be arranged in a single layer in which magnets are arranged in one layer, or in a multi-layer arrangement in which magnets are arranged in two or more layers.

[0036] The through hole 7a has a central portion 7a1 in which the permanent magnet 6a is embedded. The through hole 7a has an end portion 7a2 radially outward from the central portion 7a1. The through hole 7a has an end portion 7a3 radially inward from the central portion 7a1. The width of the central portion 7a1 in a direction perpendicular to the line connecting the end portions 7a2 and 7a3 is shorter than the widths of the end portions 7a2 and 7a3. The permanent magnet 6a fitted into the central portion 7a1 of the through hole 7a does not reach the end portions 7a2 and 7a3. The end portions 7a2 and 7a3 function as flux barriers.

[0037] The axial length of each of the permanent magnets 6a, 6b, 6c, and 6d is approximately equal to the axial length of each of the through holes 7a, 7b, 7c, and 7d. Each of the permanent magnets 6a, 6b, 6c, and 6d axially penetrates the iron core 4. Taking permanent magnet 6a as a representative, both axial ends of permanent magnet 6a reach both ends of iron core 4 and are close to the outside of iron core 4, so heat dissipation is easy and the temperature does not rise as easily as in the axial center of permanent magnet 6a.

[0038] Each of the permanent magnets 6a, 6b, 6c, and 6d is divided in the axial direction. Each of the permanent magnets 6a, 6b, 6c, and 6d has a structure in which a plurality of rectangular parallelepiped magnets are arranged in the axial direction. The shape of each of the permanent magnets 6a, 6b, 6c, and 6d is not limited to a rectangular parallelepiped. In this embodiment, the division pattern of each of the permanent magnets 6a, 6b, 6c, and 6d is a first pattern extending from the axial center to one axial side, and a second pattern extending from the axial center to the other axial side.

[0039] FIG. 4 is a schematic side cross-sectional view showing an example of the division pattern of the permanent magnet 6 according to the first embodiment of the present invention. In this embodiment, permanent magnets 6a and 6b are examples of inner-circumference-side magnets, and permanent magnets 6c and 6d are examples of outer-circumference-side magnets. In FIG. 4, permanent magnet 6a is shown as an inner-circumference-side magnet, and permanent magnet 6c is shown as an outer-circumference-side magnet. In this embodiment, the first pattern and the second pattern have the same magnet division pattern from the axial center toward the axial end, but the present invention is not limited to this, and the first pattern and the second pattern may have different division patterns.

[0040] In FIG. 4, the letters a, b, c, and d in the permanent magnets 6a and 6c indicate the respective divided magnets. The permanent magnet 6a is divided into magnet a, magnet b, magnet c, magnet d, magnet d, magnet c, magnet b, and magnet a, in this order, from one axial end toward the other axial end. Magnets with the same name, such as magnet a at one axial end and magnet a at the other axial end, have the same axial length. The axial length of magnet b is shorter than that of magnet a. The axial length of magnet c is shorter than that of magnet b. The axial length of magnet d is shorter than that of magnet c. In this embodiment, the permanent magnet 6c is also divided into magnet a, magnet b, magnet c, magnet d, magnet d, magnet c, magnet b, and magnet a, in this order, from one axial end toward the other axial end. The number of divided magnets shown in FIG. 4 is merely an example, and the present invention is not limited thereto.

[0041] In this embodiment, the number of magnet divisions decreases from the axial center toward the axial ends. That is, the permanent magnets 6a and 6c are divided into more fine parts at the axial center than at the axial ends.

[0042] In the example of Figure 4, when the magnet is divided in the axial direction, the division dimensions are such that the axial length of the magnet at the center of the axial direction is less than the axial length of the magnet at the end of the axial direction. A longer axial length of the magnet means that the number of divisions in the axial direction of the magnet is fewer.

[0043] According to this embodiment, in a configuration in which multiple magnets are arranged in the radial direction, the permanent magnets 6a and 6c are divided into smaller pieces at the axial center than at the axial ends, thereby suppressing the temperature rise of the permanent magnets embedded in the rotor 2. Furthermore, according to this embodiment, the total number of divisions of the magnet in the axial direction can be effectively reduced, thereby reducing manufacturing costs.

[0044] In this embodiment, the number of divisions of the magnet in the axial direction is varied depending on the surrounding environment, i.e., ease of heat dissipation. In other words, by reducing the number of divisions in areas where heat dissipation is easy and increasing the number of divisions in areas where heat dissipation is difficult, it is possible to prevent temperature increases while reducing the total number of divisions of the magnet in the axial direction and reduce manufacturing costs.

[0045] Second Embodiment 5 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to a second embodiment of the present invention. In the second embodiment, the structures shown in FIGS. 1, 2 and 3 are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0046] In FIG. 5, permanent magnet 6a is divided into magnet a, magnet b, magnet c, magnet d, magnet d, magnet d, magnet d, magnet c, magnet b, and magnet a, in that order, from one axial end toward the other axial end. In this embodiment, permanent magnet 6c is also divided into magnet a, magnet b, magnet c, magnet d, magnet d, magnet d, magnet d, magnet c, magnet b, and magnet a, in that order, from one axial end toward the other axial end. The number of magnet divisions shown in FIG. 5 is an example, and the present invention is not limited to this. In this embodiment, four magnets d, which have the shortest axial length, are arranged side by side at the axial center, thereby increasing the number of magnet divisions at the axial center. Note that multiple magnets with the same axial length may be arranged adjacent to each other in the axial direction.

[0047] In the example of Figure 5, the division dimensions when the magnet is divided in the axial direction are such that the axial length of the magnet at the center of the axial direction is less than or equal to the axial length of the magnet at the end of the axial direction. However, if the number of divisions of the outer peripheral magnet and the inner peripheral magnet is the same, it is desirable that the axial length of the axially central magnet be less than the axial length of the axially end magnet.

[0048] According to this embodiment, in a configuration in which multiple magnets are arranged in the radial direction, the permanent magnets 6a and 6c are divided into smaller pieces at the axial center, thereby suppressing the temperature rise of the permanent magnets embedded in the rotor 2. Furthermore, according to this embodiment, the total number of divisions of the magnet in the axial direction can be effectively reduced, thereby reducing manufacturing costs.

[0049] Third Embodiment 6 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to a third embodiment of the present invention. In the third embodiment, the structures shown in FIGS. 1, 2 and 3 are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0050] 6, permanent magnet 6a is divided into six magnets b, all of which have the same axial length. In this embodiment, permanent magnet 6c is divided into 22 magnets a, all of which have the same axial length. In this embodiment, the axial length of magnet a is shorter than the axial length of magnet b.

[0051] 6, since the loss density of the outer magnet is greater than the loss density of the inner magnet, the number of axial divisions of the outer magnet is greater than the number of axial divisions of the inner magnet. However, depending on the operating range of motor 1, the loss density of the outer magnet may be less than the loss density of the inner magnet, so the number of axial divisions of the outer magnet may be less than the number of axial divisions of the inner magnet.

[0052] According to this embodiment, in a configuration in which multiple magnets are arranged in the radial direction, the outer circumferential magnets are divided more finely than the inner circumferential magnets, thereby suppressing the temperature rise of the permanent magnets embedded in the rotor 2. Furthermore, according to this embodiment, the total number of divisions of the magnet in the axial direction can be effectively reduced, thereby reducing manufacturing costs. Furthermore, according to this embodiment, by dividing the magnets into equal axial lengths, manufacturing costs can be reduced.

[0053] In this embodiment, the number of divisions in the axial direction of the magnet is varied depending on the surrounding environment, namely, loss density. That is, by increasing the number of divisions for magnets with high loss density and decreasing the number of divisions for magnets with low loss density, it is possible to reduce the total number of divisions in the axial direction of the magnet and reduce manufacturing costs while preventing temperature rise.

[0054] <Fourth embodiment> 7 is a schematic side cross-sectional view showing an example of a division pattern of a permanent magnet 6 according to a fourth embodiment of the present invention. In the fourth embodiment, the structures shown in FIGS. 1, 2 and 3 are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0055] In FIG. 7, permanent magnet 6a is divided into magnet a, magnet b, magnet c, magnet d, magnet d, magnet d, magnet d, magnet c, magnet b, and magnet a, in that order, from one axial end toward the other axial end. In this embodiment, permanent magnet 6c is divided into magnet e, magnet f, magnet f, and magnet e, in that order, from one axial end toward the other axial end. The axial length of magnet f is shorter than the axial length of magnet e. The number of divisions of the magnet shown in FIG. 7 is just an example, and the present invention is not limited to this. In the example of FIG. 7, a combination of the division methods shown in FIGS. 4, 5, and 6 is used.

[0056] According to this embodiment, in a configuration in which multiple magnets are arranged in the radial direction, the permanent magnets 6a and 6c are divided more finely at the axial center than at the axial ends, thereby suppressing the temperature rise of the permanent magnets embedded in the rotor 2. Also, according to this embodiment, in a configuration in which multiple magnets are arranged in the radial direction, the outer peripheral magnets are divided more finely than the inner peripheral magnets, thereby suppressing the temperature rise of the permanent magnets embedded in the rotor 2. Also, according to this embodiment, the total number of axial divisions of the magnet can be effectively reduced, thereby reducing manufacturing costs.

[0057] Fifth Embodiment Fig. 8 is an enlarged view of a portion of the cross-sectional view shown in Fig. 1 in a motor according to a fifth embodiment of the present invention. In this embodiment, the arrangement of magnets in a plane perpendicular to the axial direction is different from that shown in Fig. 2.

[0058] In this embodiment, permanent magnets 16a, 16b, 16c, 16d, 16e, and 16f are used as permanent magnets 6. The iron core 4 has through holes that accommodate the permanent magnets 16a, 16b, 16c, 16d, 16e, and 16f.

[0059] Permanent magnet 16a is arranged such that its radially outer side is offset counterclockwise by an angle of 90 degrees or less in the circumferential direction from the direction parallel to the radial direction. Permanent magnet 16b is arranged in a position offset clockwise in the circumferential direction from permanent magnet 16a. Permanent magnet 16b is arranged such that its radially outer side is offset clockwise by an angle of 90 degrees or less in the circumferential direction from the direction parallel to the radial direction. Permanent magnet 16c is arranged between permanent magnets 16a and 16b in the circumferential direction and at the same radially inner position as permanent magnets 16a and 16b in the radial direction.

[0060] Permanent magnet 16d is arranged radially outward of permanent magnet 16a, permanent magnet 16e is arranged radially outward of permanent magnet 16b, and permanent magnet 16f is arranged radially outward of permanent magnet 16c.

[0061] Permanent magnet 16d is arranged such that its radially outer side is offset counterclockwise by an angle of 90 degrees or less in the circumferential direction from the direction parallel to the radial direction. Permanent magnet 16e is arranged in a position offset clockwise in the circumferential direction from permanent magnet 16d. Permanent magnet 16e is arranged such that its radially outer side is offset clockwise by an angle of 90 degrees or less in the circumferential direction from the direction parallel to the radial direction. Permanent magnet 16f is arranged between permanent magnets 16d and 16e in the circumferential direction and at the same radially inner position as permanent magnets 16d and 16e in the radial direction.

[0062] Permanent magnets 16a, 16b, 16d, and 16e each have a gap at both ends that functions as a flux barrier. Permanent magnets 16c and 16ef are disposed between magnets with gaps at both ends. Two magnets with gaps at both ends are easily demagnetized. In this embodiment, the number of axial divisions of the two easily demagnetized magnets with gaps at both ends is set to be greater than the number of axial divisions of the magnet disposed between the magnets with gaps at both ends. In the example of FIG. 8, for example, one permanent magnet 16c is disposed between permanent magnets 16a and 16b, but multiple magnets may be disposed between permanent magnets 16a and 16b.

[0063] According to this embodiment, by dividing the permanent magnets 16a and 16b more finely than the permanent magnet 16c, it is possible to suppress the temperature rise of the permanent magnets embedded in the iron core 4. Furthermore, according to this embodiment, it is possible to effectively reduce the total number of divisions of the magnet in the axial direction, thereby reducing manufacturing costs.

[0064] In this embodiment, the number of divisions in the axial direction of the magnet is varied depending on the surrounding environment, namely the susceptibility to demagnetization. That is, by increasing the number of divisions for magnets that are prone to demagnetization and decreasing the number of divisions for magnets placed between magnets that are prone to demagnetization, it is possible to reduce the total number of divisions in the axial direction of the magnet while preventing temperature rise, thereby reducing manufacturing costs.

[0065] In this embodiment, permanent magnets 16a, 16b, and 16c may be defined as a first layer, and permanent magnets 16d, 16e, and 16f may be defined as a second layer, and division may be performed using the division patterns in the axial direction of the magnets shown in Figures 4 to 7.

[0066] According to the present invention as described above, by increasing the number of axial divisions of the magnet in the axial center where heat dissipation is poor and the magnet temperature is high, and decreasing the number of axial divisions of the magnet at the axial ends where heat dissipation is good and the magnet temperature is low, it is possible to reduce the total number of divisions while lowering the average magnet temperature.

[0067] Furthermore, according to the present invention, the total number of divisions can be reduced by increasing the number of axial divisions of the outer magnet, which is more susceptible to harmonic currents, and decreasing the number of axial divisions of the inner magnet, which is less susceptible to harmonic currents. Note that, depending on the operating range of the motor, the loss density of the outer magnet may be smaller than the loss density of the inner magnet. In this case, the number of axial divisions of the outer magnet may be smaller than the number of axial divisions of the inner magnet. Magnet loss is eddy current loss caused by harmonic currents, and by dividing the magnet and insulating it between the magnets, eddy currents can be reduced and loss can be reduced. Therefore, by increasing the number of axial divisions of the magnet at the axial center and the number of axial divisions of either the outer magnet or the inner magnet, whichever has the higher loss density, loss can be reduced and heat generation can be suppressed.

[0068] Furthermore, according to the present invention, by increasing the number of divisions of two magnets with gaps at both ends and decreasing the number of divisions of one or more magnets placed between them, it is possible to reduce the total number of divisions while mitigating the effects of demagnetization due to anti-magnetic fields.

[0069] In the present invention, the number of divisions of the magnet in the axial direction may be determined according to a combination of the ease of heat dissipation, loss density, and ease of demagnetization in the surrounding environment.

[0070] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. The present invention also includes combinations of the various embodiments. In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0071] 1...motor, 2...rotor, 3...stator, 4...iron core, 5...shaft, 6...permanent magnet

Claims

1. a shaft extending along a central axis; an iron core to which the shaft is fixed; a magnet that forms magnetic poles in the circumferential direction of the iron core; and the magnets are arranged in a plurality of layers at different radial positions of the iron core, The magnet is divided into a plurality of pieces in the axial direction by penetrating the iron core in the axial direction, The magnet with a high loss density has a larger number of divisions than the magnet with a low loss density. A rotor characterized by:

2. The magnets arranged in the layers with higher loss density among the plurality of layers have a larger number of divisions than the magnets arranged in the layers with lower loss density among the plurality of layers.

2. The rotor according to claim 1 .

3. a shaft extending along a central axis; an iron core to which the shaft is fixed; a magnet that forms magnetic poles in the circumferential direction of the iron core; and the magnets are arranged in a plurality of layers at different radial positions of the iron core, The magnet is divided into a plurality of pieces in the axial direction by penetrating the iron core in the axial direction, The magnets that are easily demagnetized have a larger number of divisions than the magnets that are arranged between the magnets that are easily demagnetized. A rotor characterized by:

4. a shaft extending along a central axis; an iron core to which the shaft is fixed; a magnet that forms magnetic poles in the circumferential direction of the iron core; and the magnets are arranged in a plurality of layers at different radial positions of the iron core, The magnet is divided into a plurality of pieces in the axial direction by penetrating the iron core in the axial direction, The magnet having gaps at both ends has a larger number of divisions than the magnet arranged between the magnets having gaps at both ends. A rotor characterized by:

5. A rotor according to any one of claims 1 to 4; a stator disposed radially outside the rotor via an air gap; having A rotating electric machine characterized by:

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