Rotor of rotating electrical machine

Abstract

A rotor of a rotating electrical machine in which a plurality of holes are formed in an annular rotor core, the plurality of holes constituting a plurality of magnetic poles arranged at equal intervals in the circumferential direction by means of insertion of fixed permanent magnets, and each of the holes being provided with a plurality of holes for each of the magnetic poles. The hole is composed of two inner side holes located on the inner side in the radial direction and one outer side hole located on the outer side in the radial direction compared with the inner side holes. The two inner side holes are composed of a first inner side hole located on the rotation direction side of the rotor and a second inner side hole located on the reverse rotation direction side relative to the first inner side hole. The first inner hole and the second inner hole are disposed so as to face each other about the d-axis, where the d-axis is the central axis of the magnetic pole, and the q-axis is an axis offset by 90 DEG in electrical angle from the d-axis. The rotor core is provided with a void portion which is a recess provided in the outer peripheral portion of the rotor core and which communicates with the second inner hole.

Description

Technical Field

[0001] The present invention relates to a rotor of a rotating electric machine, and more particularly to a rotor of a rotating electric machine capable of reducing periodic torque fluctuations, namely, torque ripples, generated during rotation. Background Art

[0002] In recent years, efforts to achieve a low-carbon or decarbonized society have led to the development of electrification in vehicles, aiming to reduce CO2 emissions and improve energy efficiency. Reducing torque ripple, the fluctuation in torque produced during rotation, has become a challenge in rotating electrical machines. In particular, when using a two-phase motor as the rotating electrical machine, large torque ripple of up to four times the electrical angle is likely to occur.

[0003] Patent Document 1 discloses a structure in which, in a rotor of a rotating electrical machine having holes for inserting and fixing permanent magnets provided at equal intervals in the circumferential direction, a substantially semicircular gap is provided radially outward between adjacent holes.

[0004] [Prior Art Literature]

[0005] (Patent Document)

[0006] Patent Document 1: Japanese Patent No. 6435838 Summary of the Invention

[0007] [Problems to be solved by the invention]

[0008] However, it is desired to have a rotor structure, i.e., a gap portion disclosed in Patent Document 1, which increases the strength of the partition wall that divides the hole portion for inserting and fixing the permanent magnet and the gap portion, thereby achieving high-speed rotation of the rotating motor, and in particular, reducing the large fourth-order torque pulsation generated when the rotating motor is a two-phase motor.

[0009] The purpose of this application is to solve the above-mentioned problem by reducing the torque ripple of the rotating electrical machine through research on the rotor structure, and thereby contribute to improving energy efficiency.

[0010] [Technical means to solve the problem]

[0011] To achieve the aforementioned object, the present invention provides a rotor for a rotating electrical machine, comprising an annular rotor core, the rotor core having a plurality of holes formed therein for inserting and securing permanent magnets therein to form a plurality of magnetic poles arranged at equal intervals in the circumferential direction. The holes comprise, for each magnetic pole, two inner holes located radially inwardly and one outer hole located radially outwardly of the inner holes. The two inner holes comprise a first inner hole located in the direction of rotation of the rotor and a second inner hole located in the direction opposite to the first inner hole. When the central axis of the magnetic pole is defined as the d-axis and the axis offset 90° in electrical angle from the d-axis is defined as the q-axis, the first inner hole and the second inner hole are disposed so as to face each other about the d-axis. A gap is provided in the rotor core. The gap is a recess formed in the outer circumference of the rotor core and communicates with the second inner hole.

[0012] Furthermore, a second feature is that the gap portion is located on the magnetic path of the q-axis on the side in the reverse rotation direction of the rotor with respect to the d-axis.

[0013] In addition, the third feature is that the first inner hole and the second inner hole are respectively formed into a long strip shape that is rectangular when viewed axially and can accommodate the permanent magnet, and are symmetrically inclined with each other in a manner such that the other end farther from the d-axis than the one end closer to the d-axis is located radially outward.

[0014] Furthermore, the fourth feature is that the circumferential dimension of the gap portion increases as it goes toward the radially outer side.

[0015] In addition, the fifth feature is that the circumferential dimension of the radially outer side of the gap portion is at least 1 / 4 of the circumferential length of one magnetic pole of the rotor core, and the radial dimension of the gap portion is at least 1 / 10 of the radius of the rotor core.

[0016] Furthermore, a sixth feature is that the first inner hole and the second inner hole are separated by a partition wall extending in the radial direction, and the partition wall is inclined so that the radial outer side is located on the rotation direction side of the rotor rather than the radial inner side when viewed in the axial direction.

[0017] Furthermore, the seventh feature is that the rotating electrical machine is a two-phase motor.

[0018] (Effects of the Invention)

[0019] According to the first feature, in the rotor of the rotating electrical machine, there is a circular rotor core, and a plurality of holes are formed in the rotor core. The plurality of holes are used to form a plurality of magnetic poles arranged at equal intervals in the circumferential direction by inserting and fixing permanent magnets. Moreover, for each of the magnetic poles, the holes are composed of two inner holes located radially inward and one outer hole located radially outward of the inner holes. The two inner holes are composed of a first inner hole located on the rotation direction side of the rotor and a second inner hole located on the reverse rotation direction side relative to the first inner hole. When the center axis of the magnetic pole is set as the d-axis, and the axis deviated by 90° from the d-axis in electrical angle is set as the q-axis, the first inner hole and the second inner hole are arranged opposite to each other with the d-axis as the center, and a gap portion is provided on the rotor core. The gap portion is a recess provided on the outer peripheral portion of the rotor core and is connected to the second inner hole. Therefore, by providing the gap portion, the torque starting from between the outer hole and the second inner hole and pointing to the radially outer side of the rotor core and the reverse rotation direction can be reduced, thereby reducing the torque pulsation of the rotating motor.

[0020] According to the second feature, the gap portion is located in the magnetic circuit of the q-axis on the reverse rotation direction side of the rotor relative to the d-axis. Therefore, by providing the gap portion in the magnetic circuit of the q-axis, the torque generated by the magnetic circuit of the q-axis can be reduced, and the torque pulsation of the rotating motor can be reduced.

[0021] According to the third feature, the first inner hole and the second inner hole are each formed into a rectangular strip shape when viewed axially so as to allow the permanent magnet to be inserted therein, and are symmetrically inclined with respect to each other so that the other end farther from the d-axis is located radially outward relative to the one end closer to the d-axis. Therefore, the outer hole and the inner hole can be arranged close to each other, thereby reducing the radial dimension of the rotor core.

[0022] According to the fourth feature, the circumferential dimension of the gap increases radially outward. This ensures the strength of the portion where the second inner hole communicates with the gap, while also increasing the circumferential dimension of the gap at the radially outward position. This further enhances the effect of reducing torque ripple.

[0023] According to the fifth feature, the circumferential dimension of the radially outer side of the aforementioned gap portion is more than 1 / 4 of the circumferential length of one magnetic pole of the aforementioned rotor core, and the radial dimension of the aforementioned gap portion is more than 1 / 10 of the radius of the aforementioned rotor core, so the torque pulsation of the rotating motor can be effectively reduced.

[0024] According to the sixth feature, the first inner hole and the second inner hole are separated by a radially extending partition wall. The partition wall is inclined so that the radially outer side is located on the rotational direction side of the rotor relative to the radially inner side when viewed in the axial direction. Therefore, it is generally believed that, particularly when a magnetic flux barrier is provided at the end of the first inner hole and the end of the second inner hole that are closer to the d-axis, which serves as a space not occupied by the permanent magnet and through which magnetic flux does not pass, the partition wall separating the first inner hole and the second inner hole is likely to become thinner. Furthermore, the provision of the gap may cause a deviation in the centrifugal force distribution, leading to torsional stress concentration on the partition wall. In contrast, forming the partition wall along the direction of the centrifugal force can mitigate the effects of torsional stress.

[0025] According to the seventh feature, the aforementioned rotating motor is a two-phase motor. Therefore, when the rotating motor is a two-phase motor, there is less overlap of spatial magnetic flux, which easily generates a spatial fourth-order high frequency and a large torque pulsation of the fourth order of electrical angle, but the fourth-order torque pulsation can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a front view (axial view) of the rotating electrical machine.

[0027] Figure 2 This is a front view of a rotor constituting a rotating electrical machine.

[0028] Figure 3 This is a front view of the rotor core and stator that form one magnetic pole.

[0029] Figure 4 This is a front view of the rotor core that forms one magnetic pole.

[0030] Figure 5 This is an enlarged view of the rotor core near the gap. DETAILED DESCRIPTION

[0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a front view (axial view) of a rotating electrical machine 1 according to one embodiment of the present invention. Figure 2 This is a front view of a rotor 10 constituting a rotating electrical machine 1. The rotating electrical machine 1 is an inner rotor type two-phase motor in which a rotor 10 having a rotating shaft (not shown) is housed within the inner periphery of an annular stator core 2 around which a plurality of stator coils 3 are wound.

[0032] The rotor core 11 constituting the rotor 10 is formed by laminating a plurality of electromagnetic steel sheets punched into an annular shape. A plurality of permanent magnets 20 are inserted and fixed at predetermined positions in a plurality of holes provided in the rotor core 11. This forms eight magnetic poles M in this embodiment.

[0033] The central axis of the magnetic pole M, which passes through the rotation center C of the rotor core 11, constitutes the d-axis (d), which is the direction of the excitation magnetic flux. Furthermore, the axis offset 90° in electrical angle from the d-axis constitutes the q-axis (q), which is the direction of the armature magnetic flux. The rotating electric machine 1 of this embodiment primarily rotates the rotor 10 in the counterclockwise direction as shown. The rotor core 11 of this embodiment is characterized in that a gap 30, which is a recessed portion provided on the outer periphery of the rotor core 11, is formed between the d-axis and the q-axis, which is located in the opposite direction of rotation relative to the d-axis (clockwise in the figure).

[0034] Figure 3 This is a front view of the rotor core 11 and stator 2, which form a single magnetic pole M. The same reference numerals as previously described denote identical or equivalent parts. The rotor core 11 is formed with a plurality of rectangular holes, viewed axially, for inserting and securing the permanent magnets 20. These holes consist of two inner holes 13 and 14 located radially inward, and an outer hole 12 located radially outward of these inner holes 13 and 14. The d-axis passes through the rotation center C of the rotor core 11 and the center of the permanent magnet 20 inserted and secured in the outer hole 12.

[0035] Meanwhile, the inner holes 13 and 14 consist of a first inner hole 13 located on the rotational side relative to the d-axis, and a second inner hole 14 located on the counter-rotational side relative to the d-axis. These holes are arranged facing each other with the d-axis as the center. More specifically, the first inner hole 13 and the second inner hole 14 each have a rectangular, axially oriented strip shape suitable for inserting the permanent magnet 20. They are tilted radially outward relative to one end closer to the d-axis and symmetrically arranged relative to each other. This allows the outer hole 12 and the inner holes 13 and 14 to be positioned close together, reducing the radial dimension of the rotor core 11.

[0036] Here, when the rotating electrical machine is configured as a two-phase motor, spatial magnetic flux overlap is minimal, easily generating a spatial fourth-order high frequency, resulting in large torque pulsation of the fourth order in electrical angle. This is caused by torque T (shown as a black arrow) originating between the outer hole 12 and the second inner hole 14 and directed radially outward and in the opposite direction of rotation. Therefore, in this embodiment, by providing a gap 30, which is a recessed portion formed on the outer periphery of the rotor core 11 and communicates with the second inner hole 14, it is possible to reduce torque T and, thereby, reduce the fourth-order torque pulsation of the rotating electrical machine 1.

[0037] The gap 30 is located on the q-axis magnetic path P (dashed arrow in the figure) on the reverse rotation side of the rotor 10 relative to the d-axis. This reduces the torque T generated by the q-axis magnetic path P and the torque ripple of the rotating electric machine 1.

[0038] Figure 4This is a front view of the rotor core 11 corresponding to one magnetic pole M. In this embodiment, the gap 30 is formed such that its circumferential dimension increases radially outward. This ensures the strength of the portion where the second inner hole 14 communicates with the gap 30, while also increasing the circumferential dimension of the gap 30 radially outward, further enhancing the torque ripple reduction effect.

[0039] Furthermore, the circumferential dimension L1 of the radially outer portion of the gap 30 is at least 1 / 4 of the circumferential length A of a single magnetic pole M, and the radial dimension L2 of the gap 30 is at least 1 / 10 of the radius R of the rotor core 11. This effectively reduces torque ripple in the rotating electrical machine 1. The first inner hole 13 and the second inner hole 14 are separated by a partition wall 15 located on the d-axis.

[0040] Figure 5 This is an enlarged view of the rotor core 11 near the gap 30. As previously described, the gap 30 is formed so that its circumferential dimension increases radially outward, and is connected to the end of the second inner hole 14 farther from the d-axis via the connecting portion 31. Experiments have shown that if the overall size of the gap 30 is smaller than that of the present embodiment, or if the opening area on the outer circumference of the rotor core 11 is smaller, the torque ripple reduction effect is reduced.

[0041] Furthermore, flux barriers 13a and 14a are provided at the d-axis ends of the first inner hole 13 and the d-axis ends of the second inner hole 14, serving as spaces not occupied by the permanent magnets 20 and preventing magnetic flux from passing through. This makes it easier to reduce the thickness of the partition wall 15 separating the first inner hole 13 and the second inner hole 14. Furthermore, it is generally believed that the provision of the gap 30, which is used to reduce torque ripple, causes a deviation in the centrifugal force distribution, concentrating torsional stress on the partition wall 15. Therefore, in this embodiment, the partition wall 15 is tilted so that the radially outer side is located closer to the rotational direction of the rotor 10 than the radially inner side, as viewed in the axial direction. This formation of the partition wall 15 along the direction of the centrifugal force mitigates the effects of torsional stress.

[0042] The configuration of the rotating electrical machine, the shape and structure of the stator and rotor, the shape of the rotor core and the number of weight-reducing holes, the number of magnetic poles, the shape and number of permanent magnets, the shape and number of holes, the shape and size of the gaps, the shape of the partition walls, and the like are not limited to the above-described embodiment and may be modified in various ways. The above-described embodiment illustrates a configuration in which the rotor's primary rotational direction is counterclockwise when viewed in the axial direction of the rotating electrical machine. However, when the rotor's primary rotational direction is clockwise, the provision of the gap on the opposite side of the d-axis can achieve the same torque ripple reduction effect as in the above-described embodiment. The rotor structure of the rotating electrical machine of this embodiment is not limited to two-phase motors and can also be applied to three-phase and five-phase motors.

[0043] Reference numerals

[0044] 1: Rotating motor

[0045] 10: Rotor

[0046] 11: Rotor core

[0047] 12: Outer hole

[0048] 13: First inner hole (hole)

[0049] 14: Second inner hole (hole)

[0050] 15: Next door

[0051] 20: Permanent magnet

[0052] 30: Gap

[0053] M: Magnetic pole

[0054] d: d-axis

[0055] q: q-axis

[0056] P: q-axis magnetic circuit

[0057] A: Circumferential length of a magnetic pole

[0058] R: radius of the rotor core

[0059] L1: Circumferential dimension of the gap on the radially outer side

[0060] L2: Radial dimension of the gap

Claims

1. A rotor of a rotating electrical machine, characterized in that: A rotor core having a circular shape, The rotor core is provided with a plurality of holes for inserting and fixing permanent magnets to form a plurality of magnetic poles arranged at equal intervals in the circumferential direction, and The holes are composed of two inner holes located radially inwards and one outer hole located radially outwards of the inner holes for each of the magnetic poles. The two inner holes are composed of a first inner hole located on the rotation direction side of the rotor and a second inner hole located on the reverse rotation direction side relative to the first inner hole. When the central axis of the magnetic pole is set as the d-axis and the axis offset by 90 degrees in electrical angle from the d-axis is set as the q-axis, the first inner hole and the second inner hole are arranged facing each other with the d-axis as the center. The rotor core is provided with a gap portion, which is a recess provided in the outer peripheral portion of the rotor core and communicates with the second inner hole.

2. The rotor of the rotating electrical machine according to claim 1, wherein The gap portion is located on the magnetic path of the q-axis on the reverse rotation direction side of the rotor with respect to the d-axis.

3. The rotor of the rotating electrical machine according to claim 1 or 2, wherein: The first inner hole and the second inner hole are each formed into a rectangular strip shape when viewed axially so as to allow the permanent magnet to be inserted, and are symmetrically inclined with one end farther from the d-axis than the other end closer to the d-axis being located radially outward.

4. The rotor of a rotating electrical machine according to claim 1 or 2, wherein: The circumferential dimension of the gap portion increases toward the radially outer side.

5. The rotor of the rotating electrical machine according to claim 4, wherein The circumferential dimension of the radially outer side of the gap is at least 1 / 4 of the circumferential length of one magnetic pole of the rotor core. The radial dimension of the gap portion is equal to or greater than 1 / 10 of the radius of the rotor core.

6. The rotor of the rotating electrical machine according to claim 3, wherein The first inner hole and the second inner hole are separated by a partition wall extending in the radial direction. The partition wall is inclined so that the radially outer side is located on the rotation direction side of the rotor rather than the radially inner side when viewed in the axial direction.

7. The rotor of a rotating electrical machine according to claim 1 or 2, wherein: The aforementioned rotating electrical machine is a two-phase motor.

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