Embedded magnet rotor and rotating electric machine

Abstract

To provide an embedded magnet type rotor that can suppress torque reduction due to magnetic flux leakage. [Solution] An embedded magnet rotor has multiple magnetic poles formed in the circumferential direction of an iron core, and each magnetic pole is arranged such that a magnet having a portion where two rectangular parts are connected by a bent portion extends in the circumferential direction. The magnetization orientation of the rectangular portion of the magnet is parallel orientation, and the magnetization orientation of the bent portion is radial orientation.

Description

Technical Field

[0001] The present invention relates to an embedded magnet type rotor and a rotating electric machine.

Background Art

[0002] Conventionally, in order to achieve high torque density and high output density of a rotating electric machine, various embedded magnet type rotors in which a plurality of magnets are arranged in a V shape for one pole have been proposed. For example, Patent Document 1 discloses a configuration of a rotor in which six plate-like magnets for one pole are arranged in two layers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration of Patent Document 1 described above, there is room for improvement in that magnetic flux leakage occurs from the gaps between the plurality of magnets arranged in a V shape, which may cause a decrease in torque.

[0005] The present invention has been made in view of the above situation, and provides an embedded magnet type rotor capable of suppressing a decrease in torque due to magnetic flux leakage. [[ID=?]]

Means for Solving the Problems

[0006] One aspect is an embedded magnet type rotor in which a plurality of magnetic poles are formed in the circumferential direction of an iron core, and magnets each having a portion where two rectangular portions are connected by a bent portion are arranged so as to extend in the circumferential direction. The magnetization orientation of the rectangular portion of the magnet is a parallel orientation, and the magnetization orientation of the bent portion is a radial orientation.

[0007] In one embodiment described above, the magnet may be formed in a V-shape with two rectangular sections connected by a single bent section. Alternatively, the V-shaped magnet may be arranged straddling the magnetic pole center with each end of the rectangular section facing the outer circumference and the bent section facing the axial center.

[0008] In one embodiment described above, the magnet may be formed in a U-shape with a second rectangular portion connected to both ends of a first rectangular portion via bent portions. Alternatively, the magnet may be arranged straddling the magnetic pole center with each end of the second rectangular portion facing the outer circumference and the first rectangular portion facing the axial center.

[0009] In one embodiment described above, multiple magnets may be arranged at one magnetic pole so as to form multiple layers in the radial direction. Another embodiment of the rotating electric machine comprises a stator and an embedded magnet type rotor as described in one embodiment above. [Effects of the Invention]

[0010] According to one embodiment, an embedded magnet rotor is provided that can suppress the reduction in torque due to magnetic flux leakage. can. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of the rotating electric machine of this embodiment. [Figure 2] This figure shows an example of the configuration of one magnetic pole of the rotor in this embodiment. [Figure 3] This figure shows the magnets of the rotor in this embodiment. [Figure 4] This is an enlarged view of the vicinity of the magnet on the outer circumference of the rotor in this embodiment. [Figure 5] (a) is a diagram showing the relationship between the magnetic cross-sectional area and torque in the rotor of this embodiment and comparative example, and (b) is a diagram showing the relationship between the magnetic cross-sectional area and torque ripple in the rotor of this embodiment and comparative example. [Figure 6] This figure shows an example of the configuration of one magnetic pole of the rotor in the first modified example. [Figure 7]It is a diagram showing a configuration example of one magnetic pole of the rotor in the second modification. [Figure 8] It is a diagram showing the magnet of the rotor applied in FIG. 7. [Figure 9] It is a diagram showing a configuration example of one magnetic pole of the rotor in the third modification.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, for the sake of easy understanding of the explanation, structures and elements other than the main part of the present invention will be described in a simplified or omitted manner. Also, in the drawings, the same elements are denoted by the same reference numerals. Note that the shapes, dimensions, etc. of each element shown in the drawings are schematically shown and do not represent actual shapes, dimensions, etc.

[0013] Also, in the following description, the direction parallel to the extension direction of the rotation axis Ax of the rotating electrical machine is referred to as the axial direction, the circumferential direction centered on the rotation axis Ax is simply referred to as the circumferential direction, and the radial direction centered on the rotation axis Ax is simply referred to as the radial direction. [[ID=二十一]] [[ID=二十二]]

[0014] [[ID=二十三]] FIG. 1 is a cross-sectional view showing a cross section in a direction orthogonal to the rotation axis Ax of the rotating electrical machine of the present embodiment. The rotating electrical machine 1 shown in FIG. 1 is, for example, an inner rotor type motor, and has a rotor 2 which is an example of an embedded magnet type rotor, and a cylindrical stator 3 disposed on the outer periphery of the rotor 2. In FIG. 1, the extension direction of the rotation axis Ax of the rotating electrical machine 1 is perpendicular to the paper surface.

[0015] The stator 3 houses the rotor 2 with an air gap in the central space portion centered on the rotation axis Ax. On the inner peripheral side of the stator 3, a plurality of teeth 3a protruding radially inward toward the rotation axis Ax are provided at equal intervals in the circumferential direction. Slots 3b are formed between adjacent teeth 3a. Coils (not shown) are mounted in the slots 3b of the stator 3 along the outer periphery of the rotor 2.

[0016] In the rotating electrical machine 1, by sequentially switching the magnetic field of the stator 3 through current control of the coil, the rotor 2 rotates about the rotation axis Ax due to the attractive or repulsive force with the magnetic field of the rotor 2.

[0017] The rotor 2 has an iron core 4, a shaft 5, and magnets 6. The iron core 4 of the rotor 2 is, for example, a cylindrical member formed by axially laminating punched silicon steel sheets. An insulating layer is interposed between the individual silicon steel sheets constituting the iron core 4, and the individual silicon steel sheets are insulated from each other. And a shaft 5 is fitted along the rotation axis Ax in the axial center portion of the iron core 4. In the rotating electrical machine 1, the shaft 5 is rotatably supported by a bearing (not shown).

[0018] A plurality of magnets 6 are arranged in a predetermined array on the iron core 4 of the rotor 2 so that a plurality of magnetic poles are formed at equal intervals along the circumferential direction. The magnetic poles adjacent to each other in the circumferential direction of the rotor 2 have opposite polarities. In the first embodiment, a rotor 2 having eight magnetic poles formed in the circumferential direction is shown, but the number of magnetic poles of the rotor 2 is not limited to the above.

[0019] FIG. 2 is a diagram showing a configuration example of one magnetic pole of the rotor 2 in the present embodiment. FIG. 3 is a diagram showing the magnet 6 of the rotor 2 in the present embodiment. FIG. 4 is an enlarged view of the vicinity of the magnet on the outer peripheral side of the rotor in the present embodiment.

[0020] Magnet holes extending in the axial direction are formed in the iron core 4 of the rotor 2, and magnets 6 extending in the axial direction are respectively fitted into the magnet holes. As shown in FIG. 2, three magnets 6 bent in a V shape are arranged in one magnetic pole of the rotor 2. One magnet 6 is arranged on the outer peripheral side (first layer) and two magnets 6 are arranged on the axial center side (second layer), and they are arranged to form two layers in one magnetic pole. In the example of FIG. 2, all three magnets 6 have the same shape.

[0021] The magnets 6 positioned on the outer circumference are placed on the iron core 4, straddling the d-axis (the axis connecting the axis of rotation and the center of any magnetic pole that generates magnetic torque), with a V-shaped groove located on the axis side of the rotor 2 and two ends facing outwards. The two magnets 6 positioned on the axis side are also placed on the iron core 4 at an angle such that the distance between them increases from the axis side of the rotor 2 towards the outer circumference. At each magnetic pole, the magnets 6 are arranged in a symmetrical pattern with respect to the d-axis.

[0022] Furthermore, as shown in Figures 2 and 4(a), flux barriers 7 are formed at each end of the magnet 6 in the iron core 4. The flux barriers 7 are air gaps that communicate with the magnet holes and function to suppress harmonic components included in the waveform of the magnetic flux density of the rotor 2 and to adjust the distribution of magnetic flux density in the rotor 2.

[0023] As shown in Figure 3, each magnet 6 has a shape that integrally includes two rectangular sections 6a that form a rectangular parallelepiped when viewed from the axial direction, and an arc-shaped bent section 6b connecting the two rectangular sections 6a. The thickness t of the magnet 6 is constant in the rectangular sections 6a and the bent section 6b. In this embodiment, the longitudinal lengths of the two rectangular sections 6a are formed to be the same. Furthermore, the longitudinal length of the rectangular sections 6a is set to be sufficiently longer than the arc length of the bent section 6b.

[0024] As shown in Figure 3(b), the rectangular portion 6a of the magnet 6 is in a parallel orientation, where the magnetization orientation is uniformly aligned in the thickness direction of the magnet 6 (the short axis direction of the rectangular portion 6a). On the other hand, the bent portion 6b of the magnet 6 is in a radial orientation, where the magnetization orientation at each position is oriented toward the center of curvature of the bent portion 6b.

[0025] The magnet 6 described above is formed, for example, by bonding a plate magnet that forms the rectangular portion 6a and an arc magnet that forms the bent portion 6b. Bonding is advantageous because it suppresses eddy current losses due to the formation of an adhesive layer at the boundary between the rectangular portion 6a and the bent portion 6b. Alternatively, the magnet 6 may be formed by controlling the magnetization orientation of the rectangular portion 6a and the bent portion 6b during magnetization, thereby integrally forming the rectangular portion 6a and the bent portion 6b without bonding. In the case of integral molding described above, the advantage is that it reduces manufacturing time because there is no bonding required.

[0026] In the rotor 2 of this embodiment, a V-shaped magnet 6, formed by connecting two rectangular sections 6a with a bent section 6b as described above, is used in the section (first layer) that straddles the d-axis. In the rotor 2 of this embodiment, compared to the case where two magnets are arranged opposite each other in a V-shape across the d-axis instead of the above-mentioned magnet 6, there is no gap between the two magnets, so torque reduction due to magnetic flux leakage from the gap is suppressed.

[0027] Furthermore, for example, when forming a V-shaped magnet by filling the magnet holes of the iron core 4 with bonded magnets (resin-bonded magnets made by mixing magnet powder with a binder and solidifying it), the magnet holes are filled with bonded magnets without any gaps. In the case of the above-mentioned bonded magnets, it is relatively difficult to control the magnetization orientation to parallel or radial orientation in different parts. Also, in the case of the above-mentioned bonded magnets, it becomes difficult to form a flux barrier adjacent to the magnet ends to control the magnetic flux, which can degrade the magnetic flux distribution characteristics of the rotating electric machine. On the other hand, in the rotor 2 of this embodiment, a magnet 6 that has been pre-formed into a V-shape is fitted into the magnet hole of the iron core 4. Therefore, in this embodiment, a desired magnetization orientation can be given to the rectangular portion 6a and the bent portion 6b of the magnet 6, and a gap portion (flux barrier 7) communicating with the magnet hole can be formed in a desired shape in the end region of the magnet 6. Therefore, in this embodiment, the characteristics of the magnetic flux distribution of the rotating electric machine 1 can be further improved.

[0028] Furthermore, in the rotor 2 of this embodiment, as shown in Figure 4(a), the magnet 6 can be positioned on the iron core 4 by fitting the V-shaped magnet 6 having a bent portion 6b with the magnet hole in the iron core 4. Therefore, for the first layer of magnets 6 on the outer circumference in this embodiment, it is not necessary to form a positioning rib 4a for positioning the magnet 6 on the iron core 4, as shown in Figure 4(b). In the design of this type of positioning rib, it is necessary to consider the punchability of the electromagnetic steel sheet and the stress caused by the pressure of the magnet, but in this embodiment, the positioning rib 4a can be omitted, thereby improving the design freedom of the flux barrier 7 in the rotor 2.

[0029] Furthermore, the V-shaped magnet 6 used in this embodiment allows for relatively free adjustment of the characteristics of the rotating electric machine 1 by changing the dimensions of the rectangular portion 6a and the bent portion 6b, as well as the shape and position of the bent portion 6b, compared to the case where an arc-shaped magnet is used. As a result, the rotating electric machine 1 using the rotor 2 of this embodiment can reduce torque ripple while maintaining torque, compared to a rotating electric machine using a rotor with an arc-shaped magnet.

[0030] Figure 5(a) shows the relationship between the magnetic cross-sectional area and torque in the rotor of this embodiment and in a comparative example rotor using arc-shaped magnets. In Figure 5(a), the vertical axis represents the magnetic cross-sectional area of ​​the rotor ([mm²). 2 The horizontal axis shows torque ([Nm]). In Figure 5(a), the characteristics of this embodiment are shown by a solid line, and the characteristics of the comparative example are shown by a dashed line. From Figure 5(a), it can be seen that the change in torque with respect to the cross-sectional area of ​​the magnet is almost the same between this embodiment and the comparative example.

[0031] Figure 5(b) shows the relationship between the magnetic cross-sectional area and torque ripple in the rotor of this embodiment and the rotor of the comparative example described above. In Figure 5(b), the vertical axis represents the torque per unit area of ​​the rotor's magnetic cross-sectional area ([Nm / mm²). 2The horizontal axis shows torque ripple ([%]). In Figure 5(b), the characteristics of this embodiment are shown by a solid line, and the characteristics of the comparative example are shown by a dashed line. According to Figure 5(b), the torque per unit area of ​​the magnet is higher in this embodiment than in the comparative example when the torque ripple is the same. In other words, it can be seen that this embodiment can reduce torque ripple more effectively than the comparative example.

[0032] <Explanation of variations> Figure 6 shows an example of the configuration of one magnetic pole of the rotor 2 in the first modified example of this embodiment. In the following descriptions of each modified example, elements common to the above embodiment are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0033] As shown in Figure 6, six V-shaped magnets 6 are arranged on one magnetic pole of the rotor 2. Specifically, the magnets 6 are arranged in three layers on one magnetic pole: one on the outer circumference (first layer), two in the middle (second layer), and three on the axial side (third layer). In the example in Figure 6, all six magnets 6 have the same shape.

[0034] The magnets 6 positioned on the outer circumference are placed on the iron core 4, straddling the d-axis, with a V-shaped groove located on the axis side of the rotor 2 and two ends facing outwards. The two magnets 6 positioned in the middle are placed on the iron core 4 at an angle such that the distance between them increases from the axis side of the rotor 2 towards the outer circumference. Furthermore, the three magnets 6 positioned on the axis side are arranged to surround the three magnets in the middle. At each magnetic pole, the magnets 6 are arranged in a symmetrical pattern with respect to the d-axis. According to the first modified example, in addition to the same effects as in the above embodiment, arranging the magnets 6 in three layers makes it easier to optimize the magnetic flux distribution characteristics of one magnetic pole compared to the configuration of the above embodiment. As a result, the efficiency of the rotating electric machine 1 can be further improved in the first modified example.

[0035] Figure 7 shows an example of the configuration of one magnetic pole of the rotor 2 in a second modified example of this embodiment. Figure 8 shows the magnet 8 of the rotor 2 applied in Figure 7.

[0036] The rotor 2 of the second modified example is a modification of the above embodiment in which the magnets 6 are arranged in two layers, and is an example in which a U-shaped magnet 8 is arranged on the axial side (second layer). As shown in Figure 8, the U-shaped magnet 8 used in the second modified example has a shape in which, when viewed from the axial direction, a second rectangular portion 8c is connected to both ends of a first rectangular portion 8a located in the center via bent portions 8b. The V-shaped magnet 6 arranged on the outer circumference (first layer) is the same as in the above embodiment.

[0037] As shown in Figure 7, the first rectangular section 8a located in the center of the U-shaped magnet 8 is positioned on the iron core 4 so as to extend in a direction perpendicular to the d-axis, and the two second rectangular sections 8c located at each end are positioned on the iron core 4 at an angle such that the distance between them widens towards the outer circumference. In other words, in the magnet 8, the first rectangular section 8a faces the axis, and each end of the second rectangular section 8c faces the outer circumference.

[0038] As shown in Figure 8(b), the first rectangular section 8a and the second rectangular section 8c are both parallel oriented, with their magnetization orientations uniformly aligned in the thickness direction of the magnet 8 (the short axis direction of the first rectangular section 8a and the second rectangular section 8c). On the other hand, the bent section 8b of the magnet 8 is radially oriented, with the magnetization orientation at each position directed toward the center of curvature of the bent section 8b. In the magnet 8 shown in Figure 8, the thickness t of the magnet 8 is constant in the first rectangular section 8a, the bent section 8b, and the second rectangular section 8c. Furthermore, the first rectangular section 8a is formed to be longer in the long axis direction than the second rectangular section 8c. The same effects as those of the above embodiment can be obtained by the second modification.

[0039] Figure 9 shows an example of the configuration of one magnetic pole of the rotor 2 in a third modified example of this embodiment. The third modified rotor 2 is an example in which V-shaped magnets 6 with different lengths along the long axis of the rectangular portion 6a are applied, and the magnets 6 are arranged in a pattern that is asymmetrical with respect to the d axis.

[0040] In Figure 9, the V-shaped magnet 6 on the outer circumference (first layer) is formed such that the length of the rectangular portion 6a on the leading side of the rotor 2 in the forward rotation direction (left side in the figure) is longer than the length of the rectangular portion 6a on the lagging side of the rotor 2 in the forward rotation direction (right side in the figure). The V-shaped magnet 6 on the outer circumference is positioned on the iron core 4 such that the valley Cv of the V is shifted toward the lagging side of the d axis in the forward rotation direction. Further axially (second layer) than the V-shaped magnet 6, a U-shaped magnet 8 similar to that in the second modified example is positioned on the iron core 4.

[0041] According to the third modification, in addition to the same effects as in the above embodiment, magnetic saturation on the leading side in the forward rotation direction is mitigated under load, while magnetic saturation is more likely to occur on the lagging side in the forward rotation direction. Therefore, magnetic saturation on the leading and lagging sides in the forward rotation direction approaches uniformity within one magnetic pole, and the torque of the rotating electric machine 1 can be significantly improved. In the third modified example, the U-shaped magnet 6 may be made asymmetrical by changing the length along the long axis of the second rectangular portion 8c of the U-shaped magnet 8 or the bending angle of one of the two bent portions 6b.

[0042] The present invention is not limited to the above embodiments and modifications, and various improvements and design changes may be made without departing from the spirit of the invention.

[0043] In the above embodiment, the case where the rotating electric machine 1 is a motor was described, but the embedded magnet rotor of the present invention may also be applied to the rotor of a generator.

[0044] Furthermore, in the rotor of the present invention, the V-shaped bent magnets 6 may be arranged in an inverted V shape such that the V-shaped valley faces the outer circumference.

[0045] Furthermore, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0046] 1...Rotating electric machine, 2...Rotor, 3...Stator, 4...Core, 5...Shaft, 6...Magnet, 6a...Rectangular section, 6b...Bent section, 7...Flux barrier, 8...Magnet, 8a...First rectangular section, 8b...Bent section, 8c...Second rectangular section

Claims

1. An embedded magnet type rotor having multiple magnetic poles formed in the circumferential direction of the iron core, Each of the aforementioned magnetic poles is arranged such that a magnet having a portion where two rectangular sections are connected by a bent section extends in the circumferential direction. The magnet has a parallel magnetization orientation in the rectangular portion and a radial magnetization orientation in the bent portion. Embedded magnetic rotor.

2. The magnet is formed in a V-shape, with two rectangular sections connected by one bent section. The embedded magnet type rotor according to claim 1.

3. The V-shaped magnet is positioned so that each end of the rectangular portion faces the outer circumference and the bent portion faces the axis, straddling the magnetic pole center. The embedded magnet type rotor according to claim 2.

4. The magnet is formed in a U-shape, with a second rectangular section connected to each end of the first rectangular section via the bent sections. The magnet is positioned so as to straddle the magnetic pole center, with each end of the second rectangular portion facing the outer circumference and the first rectangular portion facing the axial center. The embedded magnet type rotor according to claim 1.

5. Multiple magnets are arranged at each magnetic pole so as to form a multilayer in the radial direction. The embedded magnet type rotor according to claim 1.

6. Stator and, The embedded magnet type rotor according to any one of claims 1 to 5 A rotating electric machine equipped with the following features.

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