JP2021097434A - Rotor for rotary electric machine, and rotary electric machine - Google Patents

Abstract

To implement loss reduction and noise reduction.SOLUTION: A rotor 4 comprises a rotor core 20 and magnets 30 and 40 which are embedded within the rotor core 20. The magnets 30 and 40 are V-shaped in a d-axis Ld defined as a symmetry axis and disposed side by side in a radial direction of the rotor core 20. The rotor core 20 includes recesses 51 and 52 on an outer peripheral surface. When an angle formed from two radii passing both outer peripheral end angles Ep1 of the innermost magnet 30 in a view in an axial direction of the rotor core 20 is defined as a first magnet opening angle V1, an angle formed from two radii passing both outer peripheral end angles Ep2 of the outermost magnet 40 is defined as a second magnet opening angle V2 and a range with an angle Vw1 formed from two radii passing an inner edge Fp1 of a pair of recesses 51 defined as a lower limit and with an angle Vw2 formed from two radii passing an outer edge Fp2 of a pair of recesses 51 defined as an upper limit is defined as a recess opening angle Wd, following inequalities (1) 31°≤V1≤35°, (2) 16°≤V2≤20° and (3) 34°≤Wd≤44° are satisfied.SELECTED DRAWING: Figure 4

Description

The present invention relates to a rotor of a rotary electric machine and a rotary electric machine.

In a rotary electric machine mounted on a hybrid vehicle, an electric vehicle, or the like, a magnetic field is formed in the stator core by supplying an electric current to the coil, and a magnetic attraction force or a repulsive force is generated between the magnet of the rotor and the stator core. As a result, the rotor rotates with respect to the stator.

As a rotor used in a rotary electric machine, so-called IPM (Interior Permanent Magnet), in which a magnet (for example, a permanent magnet) is embedded in each of a plurality of magnet insertion holes inside the rotor core when viewed from the axial direction of the rotor core, is known. Has been done. For example, in Patent Document 1, in an IPM motor, in order to increase the reluctance torque, a magnet having a multi-layer structure (for example, a two-layer structure) and having an inverted circular cross section (the center of the arc is on the d-axis and the arc is formed). (Magnets arranged with their apex facing the shaft side and both ends of the arc facing the q-axis direction) are disclosed.

Japanese Unexamined Patent Publication No. 2003-88019

However, due to the widespread use of electric vehicles, there is room for improvement in achieving low loss and low noise.

Therefore, an object of the present invention is to provide a rotor of a rotary electric machine and a rotary electric machine capable of realizing low loss and low noise.

(1) The rotor (for example, the rotor 4 in the embodiment) of the rotary electric machine (for example, the rotary electric machine 1 in the embodiment) according to one aspect of the present invention includes a rotor core (for example, the rotor core 20 in the embodiment) and the rotor core. A magnet embedded therein (for example, the first magnet 30 and the second magnet 40 in the embodiment) is provided, and the magnet is a d-axis (for example, a d-axis Ld in the embodiment) when viewed from the axial direction of the rotor core. ) Is the axis of symmetry, and a V-shape that opens outward in the radial direction of the rotor core is formed, and a plurality of rows are arranged side by side in the radial direction of the rotor core. 52), the recesses are arranged in at least a pair with the d-axis as the axis of symmetry when viewed from the axial direction of the rotor core, and the plurality of rows are arranged when viewed from the axial direction of the rotor core. The angle formed by two radii passing through the outer peripheral end angle (for example, the first outer peripheral end angle Ep1 in the embodiment) of the innermost magnet (for example, the first magnet 30 in the embodiment) located on the innermost circumference of the magnet. The first magnet opening angle V1, the outer peripheral end angle (for example, the second outer peripheral end angle Ep2 in the embodiment) of the outermost magnet (for example, the second magnet 40 in the embodiment) located on the outermost circumference of the plurality of rows of magnets. The angle formed by the two radii passing through is the second magnet opening angle V2, and the angle formed by the two radii passing through the inner end edge of the pair of dents (for example, the inner end edge Fp1 in the embodiment) is the lower limit, and the pair of dents is formed. When the range with the upper limit of the angle formed by the two radii passing through the outer edge (for example, the outer edge Fp2 in the embodiment) is defined as the recessed opening range Wd, the following equations (1) to (3) are satisfied.
31 ° ≤ V1 ≤ 35 ° ... (1)
16 ° ≤ V2 ≤ 20 ° ... (2)
34 ° ≤ Wd ≤ 44 ° ... (3)
(2) In one aspect of the present invention, the rotor core has a gap (for example, q in the embodiment) between the outer peripheral edge angle of the outermost magnet (for example, the second outer peripheral edge angle Ep2 in the embodiment) and the recess. It may have a second gap on the shaft side).
(3) In one aspect of the present invention, the number of pole pairs of the rotor core may be four pole pairs.
(4) The rotary electric machine according to one aspect of the present invention (for example, the rotary electric machine 1 in the embodiment) is arranged in the annular stator (for example, the stator 3 in the embodiment) and the stator in the radial direction with respect to the stator. The rotor (for example, the rotor 4 in the embodiment) described above is provided.
(5) In one aspect of the present invention, the stator may have 48 slots (eg, slot 13 in the embodiment).

According to the aspect of (1) above, by satisfying the above equations (1) to (3), the fluctuation of the magnetic flux flowing from the rotor to the stator becomes a sinusoidal shape, so that the iron loss due to the rotor core is reduced and the iron loss is reduced. Torque ripple and radial force can be reduced. Therefore, low loss and low noise can be realized.
According to the aspect (2) above, the rotor core has a gap between the outer peripheral end angle of the outermost magnet and the recess, so that the wraparound of the magnetic flux can be further suppressed.
According to the aspect (3) above, the arrangement of magnets and the like can be optimized when the number of pole pairs of the rotor core is four pole pairs.
According to the aspect (4) above, a rotary electric machine capable of achieving low loss and low noise can be realized by providing the annular stator and the rotor arranged inside the stator in the radial direction. Can be provided.
According to the aspect (5) above, the stator has 48 slots, so that the arrangement of the coils and the like can be optimized.

The schematic block diagram of the rotary electric machine which concerns on embodiment. FIG. II is a view taken along the line II of FIG. 1 when the rotor according to the embodiment is viewed from the axial direction. FIG. 2 is an enlarged view of a main part of FIG. 2 when the rotor according to the embodiment is viewed from the axial direction. Explanatory drawing of arrangement of magnet and dent according to embodiment. Explanatory drawing of the magnetic flux flowing from a rotor to a stator. Explanatory drawing of the amount of magnetic flux flowing into a stator. Explanatory drawing of time derivative of the amount of magnetic flux flowing into a stator. Explanatory drawing of the effect of loss reduction. Explanatory drawing of the effect of torque ripple reduction. Explanatory drawing of stress generated in a conventional rotor. The explanatory view of the stress generated in the rotor of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment, a rotary electric machine (traveling motor) mounted on a vehicle such as a hybrid vehicle or an electric vehicle will be described.

<Rotating machine>
FIG. 1 is a schematic configuration diagram showing an overall configuration of the rotary electric machine 1 according to the embodiment. FIG. 1 is a diagram including a cross section cut by a virtual plane including the axis C.
As shown in FIG. 1, the rotary electric machine 1 includes a case 2, a stator 3, a rotor 4, and a shaft 5.

The case 2 has a tubular box shape for accommodating the stator 3 and the rotor 4. A refrigerant (not shown) is housed in the case 2. A part of the stator 3 is immersed in the refrigerant in the case 2. For example, as the refrigerant, ATF (Automatic Transmission Fluid) or the like, which is a hydraulic oil used for lubrication of a transmission, power transmission, or the like, is used.

The shaft 5 is rotatably supported by the case 2. In FIG. 1, reference numeral 6 indicates a bearing that rotatably supports the shaft 5. Hereinafter, the direction along the axis C of the shaft 5 is referred to as the “axial direction”, the direction orthogonal to the axis C is referred to as the “diameter direction”, and the direction around the axis C is referred to as the “circumferential direction”.

The stator 3 includes a stator core 11 and a plurality of layers (for example, U phase, V phase, W phase) coils 12 mounted on the stator core 11.
The stator core 11 has an annular shape arranged coaxially with the axis C. The stator core 11 is fixed to the inner peripheral surface of the case 2. For example, the stator core 11 is formed by laminating a plurality of electromagnetic steel sheets (silicon steel sheets) in the axial direction. The stator core 11 may be a so-called compaction core obtained by compression molding a metal magnetic powder (soft magnetic powder).

The stator core 11 has a slot 13 into which the coil 12 is inserted. A plurality of slots 13 are arranged at intervals in the circumferential direction (see FIG. 2). For example, in this embodiment, the stator core 11 has 48 slots 13 (see FIG. 2). For example, the stator 3 has a distributed winding or SC (segment conductor) structure.

The stator core 11 has teeth 14 that project inward in the radial direction. A plurality of teeth 14 are arranged at intervals in the circumferential direction (see FIG. 2). For example, in this embodiment, the stator core 11 has 48 teeth 14 (see FIG. 2). Seen from the axial direction, the teeth 14 have a T-shape (see FIG. 5). The teeth 14 have a teeth main body 14a extending in the radial direction and a flange portion 14b extending in the circumferential direction from the radial inner end (tip) of the teeth main body 14 (see FIG. 5). A slot 13 is formed between two teeth 14 adjacent to each other in the circumferential direction.

The coil 12 is wound around each tooth 14 via the slot 13. The coil 12 includes an insertion portion 12a inserted into the slot 13 of the stator core 11 and a coil end portion 12b protruding axially from the stator core 11. The stator core 11 generates a magnetic field when a current flows through the coil 12.

<Rotor>
The rotors 4 are arranged at intervals on the inner side in the radial direction with respect to the stator 3. The rotor 4 is fixed to the shaft 5. The rotor 4 is configured to be rotatable around the axis C integrally with the shaft 5. The rotor 4 includes a rotor core 20, magnets 30, 40 (first magnet 30, second magnet 40), and an end face plate 23. For example, the magnets 30 and 40 are permanent magnets.

The rotor core 20 has an annular shape arranged coaxially with the axis C. The rotor core 20 has a shaft fixing hole 8 in which the shaft 5 is press-fitted and fixed inside in the radial direction. The rotor core 20 is formed by laminating a plurality of electromagnetic steel sheets (silicon steel sheets) in the axial direction. The rotor core 20 may be a so-called compaction core obtained by compression molding a metal magnetic powder (soft magnetic powder).

The end face plates 23 are arranged at both ends in the axial direction with respect to the rotor core 20. The end face plate 23 covers at least the magnet insertion holes 21 and 22 (first insertion hole 21, second insertion hole 22) in the rotor core 20 from both ends in the axial direction. The end face plate 23 is in contact with the outer end surface of the rotor core 20 in the axial direction.

The rotor core 20 has a plurality of magnet insertion holes 21 and 22 that penetrate the rotor core 20 in the axial direction. The plurality of magnet insertion holes 21 and 22 are arranged at intervals in the circumferential direction on the outer peripheral portion of the rotor core 20. Magnets 30 and 40 are embedded in the magnet insertion holes 21 and 22, respectively.

FIG. 2 is a view taken along the line II of FIG. 1 when the rotor 4 according to the embodiment is viewed from the axial direction. In FIG. 2, the shaft 5 and the end face plate 23 are not shown.
When viewed from the axial direction, the plurality of magnet insertion holes 21 and 22 are arranged in a V shape. Specifically, the two magnet insertion holes 21 and 22 adjacent to each other in the circumferential direction when viewed from the axial direction have a V shape that opens outward in the radial direction. The magnet insertion holes 21 and 22 are formed so as to correspond to the shapes of the magnets 30 and 40.

The magnet insertion holes 21 and 22 are arranged side by side in a plurality of rows (for example, two rows in this embodiment) in the radial direction of the rotor core 20. Hereinafter, the magnet insertion holes 21 (innermost insertion holes) located on the inner side (innermost circumference) in the radial direction of the two rows of magnet insertion holes 21 and 22 are referred to as "first insertion holes 21", and the two rows of magnet insertion holes 21. , 22, the magnet insertion hole 22 (outermost insertion hole) located on the outer side (outermost circumference) in the radial direction is also referred to as “second insertion hole 22”. The first insertion hole 21 has a larger opening area than the second insertion hole 22.

The rotor 4 of the present embodiment is an IPM in which magnets 30 and 40 are embedded in each of a plurality of magnet insertion holes 21 and 22 inside the rotor core 20. In the present embodiment, the number of pole pairs of the rotor core 20 is 4 pole pairs (8 poles). In the present embodiment, a pair of magnet insertion holes 21 and 22 arranged in a V shape when viewed from the axial direction are arranged in a plurality of pairs (8 pairs in the example of FIG. 2) at substantially equal intervals in the circumferential direction. .. That is, a plurality of pairs of magnet insertion holes 21 and 22 are arranged at substantially every 45 ° interval in the circumferential direction on the outer peripheral portion of the rotor core 20.

In the present embodiment, a pair of magnets 30 and 40 arranged in a V shape when viewed from the axial direction are arranged in a plurality of pairs (8 pairs in the example of FIG. 2) at substantially equal intervals in the circumferential direction. That is, the plurality of pairs of magnets 30 and 40 are arranged substantially at intervals of 45 ° in the circumferential direction on the outer peripheral portion of the rotor core 20. The faces of the pair of magnets 30 and 40 facing each other in the circumferential direction have the same polarity (N pole or S pole). In each pair of magnets 30 and 40, the polarities of the magnetic poles (the portion sandwiched between the pair of magnets 30 and 40 in the rotor core 20) formed on the outer peripheral surface of the rotor core 20 by the magnets 30 and 40 are arranged alternately in the circumferential direction. Is magnetized to. In FIG. 2, the arrow Vd indicates the d-axis direction of the magnetic pole composed of the magnets 30 and 40, and the arrow Vq indicates the q-axis direction.

When viewed from the axial direction, the two magnets 30 and 40 adjacent to each other in the circumferential direction form a V shape that opens outward in the radial direction. In the figure, the reference numeral Ld indicates the d-axis of the magnetic pole composed of the magnets 30 and 40, and the reference numeral Lq indicates the q-axis. Seen from the axial direction, the d-axis Ld corresponds to a virtual straight line (a virtual straight line passing through the center of the magnetic pole) that passes through the axis C and bisects between a pair of V-shaped magnets 30 and 40. Seen from the axial direction, the q-axis Lq corresponds to a virtual straight line (a virtual straight line passing through the center between magnetic poles) that passes through the axis C and bisects between two pairs of magnets 30 and 40 adjacent to each other in the circumferential direction. To do.

The magnets 30 and 40 are arranged side by side in a plurality of rows (for example, two rows in the present embodiment) in the radial direction of the rotor core 20. Hereinafter, the magnet 30 (innermost magnet) located on the inner side (innermost circumference) in the radial direction of the two rows of magnets 30 and 40 is referred to as the "first magnet 30", and the outer side of the two rows of magnets 30 and 40 in the radial direction (innermost magnet). The magnet 40 (outermost magnet) located on the innermost circumference) is also referred to as a "second magnet 40".

As shown in FIG. 3, the first magnet 30 is embedded in each of the plurality of first insertion holes 21 inside the rotor core 20. The first magnet 30 has a rectangular parallelepiped shape having a rectangular cross-sectional shape orthogonal to the axial direction. The two first magnets 30 are arranged line-symmetrically with the d-axis Ld as the axis of symmetry. The end of the first magnet 30 on the d-axis side is located radially inside the end of the first magnet 30 on the q-axis side. The two first magnets 30 are arranged so as to gradually move away from the d-axis Ld from the end on the d-axis side toward the end on the q-axis side.

The rotor core 20 includes a first convex portion 31 for positioning and fixing the first magnet 30. The first convex portion 31 is arranged inside the rotor core 20 so as to face each of the plurality of first insertion holes 21. In the figure, reference numeral 32 is a first protrusion protruding toward the end of the first magnet 30 on the q-axis side, and reference numeral 33 is a first protrusion 32 and a first protrusion 31 for relaxing stress concentration. The through holes formed between the two are shown respectively.

The rotor core 20 has first flux barriers 35 and 36 for suppressing magnetic flux leakage from both ends of the first magnet 30 in the longitudinal direction to the rotor core 20. The first flux barriers 35 and 36 are cavities penetrating the rotor core 20 in the axial direction. Hereinafter, the first flux barrier 35 located at the end on the d-axis side of the first magnet 30 is referred to as the "d-axis side first gap 35", and the first flux barrier 35 located at the end on the q-axis side of the first magnet 30. 36 is also referred to as “q-axis side first void 36”. When viewed from the axial direction, the d-axis side first gap 35 has a larger opening area than the q-axis side first gap 36.

The rotor core 20 has a first bridge portion 37 that partitions two d-axis side first gaps 35 that are adjacent to each other in the circumferential direction. The first bridge portion 37 is located on the d-axis Ld when viewed from the axial direction. The first bridge portion 37 extends along the d-axis Ld. For example, it is preferable that the radial width W1 of the first bridge portion 37 is as narrow as possible within a range that satisfies the mechanical strength of the rotor core 20 (for example, to the extent that it is not deformed when the rotor rotates or the like).

The second magnet 40 is embedded in each of the plurality of second insertion holes 22 inside the rotor core 20. The second magnet 40 has a rectangular parallelepiped shape having a rectangular cross-sectional shape orthogonal to the axial direction. Seen from the axial direction, the second magnet 40 has an outer shape smaller than that of the first magnet 30. The two second magnets 40 are arranged line-symmetrically with the d-axis Ld as the axis of symmetry. The end of the second magnet 40 on the d-axis side is located radially inside the end of the second magnet 40 on the q-axis side. The two second magnets 40 are arranged so as to gradually move away from the d-axis from the end on the d-axis side toward the end on the q-axis side. The d-axis side end of the second magnet 40 is located between the d-axis side end and the q-axis side end of the first magnet 30 in the radial direction. The end of the second magnet 40 on the q-axis side is located radially outside the end of the first magnet 30 on the q-axis side.

Seen from the axial direction, the two second magnets 40 have a V shape that opens wider than the two first magnets 30. Hereinafter, the opening angle A1 of the two V-shaped first magnets 30 is the "first V-shaped angle A1", and the opening angle A2 of the two V-shaped second magnets 40 is the "second V-shaped angle A2". Also called. The second V-shaped angle A2 is larger than the first V-shaped angle A1 (A2> A1).

The rotor core 20 includes a second convex portion 41 for positioning and fixing the second magnet 40. The second convex portion 41 is arranged inside the rotor core 20 so as to face each of the plurality of second insertion holes 22. In the figure, reference numeral 42 is a second protrusion protruding toward the end of the second magnet 40 on the q-axis side, and reference numeral 43 is a second protrusion 42 and a second protrusion 41 for relaxing stress concentration. The through holes formed between the two are shown respectively.

The rotor core 20 has second flux barriers 45 and 46 for suppressing magnetic flux leakage from both ends of the second magnet 40 in the longitudinal direction to the rotor core 20. The second flux barriers 45 and 46 are cavities penetrating the rotor core 20 in the axial direction. Hereinafter, the second flux barrier 45 located at the d-axis side end of the second magnet 40 is referred to as the “d-axis side second gap 45”, and the second flux barrier 45 located at the q-axis side end of the second magnet 40. 46 is also referred to as “q-axis side second gap 46”. When viewed from the axial direction, the d-axis side second gap 45 has an opening area smaller than that of the d-axis side first gap 35. The second gap 46 on the q-axis side is a gap between the outer peripheral end angle Ep2 of the second magnet 40 and the second recess 52 (recess).

The rotor core 20 has a second bridge portion 47 that partitions two d-axis side second gaps 45 adjacent to each other in the circumferential direction. The second bridge portion 47 is located on the d-axis Ld when viewed from the axial direction. The second bridge portion 47 extends along the d-axis Ld. The radial width W2 of the second bridge portion 47 is smaller than the radial width W1 of the first bridge portion 37 (W2 <W1). For example, it is preferable that the radial width W2 of the second bridge portion 47 is as narrow as possible within a range that satisfies the mechanical strength of the rotor core 20 (for example, to the extent that it is not deformed when the rotor rotates or the like).

The rotor core 20 has recesses 51 and 52 (first recess 51, second recess 52) on the outer peripheral surface of the rotor core 20. When viewed from the axial direction, the recesses 51 and 52 have a curved shape (arc shape) that is recessed inward in the radial direction. Hereinafter, of the two types of recesses 51 and 52, the recess 51 facing the q-axis side first gap 36 on the outer peripheral surface of the rotor core 20 is located on the d-axis Ld side of the "first recess 51" and the first recess 51. The dent 52 is also referred to as a "second dent 52".

The first recess 51 is formed over the axial direction of the portion of the outer peripheral surface of the rotor core 20 facing the first gap 36 on the q-axis side. When viewed from the axial direction, a plurality of pairs of the first recesses 51 are arranged with the d-axis Ld as the axis of symmetry. The two first recesses 51 are arranged line-symmetrically with the d-axis Ld as the axis of symmetry.

When viewed from the axial direction, the second recess 52 has a curved shape (arc shape) that is recessed inward in the radial direction. The second recess 52 may have a shallower depth than the first recess 51. The second recess 52 is formed in the axial direction of a portion of the outer peripheral surface of the rotor core 20 that faces between the first gap 36 on the q-axis side and the second gap 46 on the q-axis side. When viewed from the axial direction, a plurality of pairs of the second recesses 52 are arranged with the d-axis Ld as the axis of symmetry. The two second recesses 52 are arranged line-symmetrically with the d-axis Ld as the axis of symmetry.

<Arrangement of first magnet 30, second magnet 40 and recesses 51 and 52>
As a result of diligent studies, the present inventor has made the first magnet 30, the second magnet 40, and the recesses 51 and 52 optimally arranged so that the magnetic flux fluctuation flowing from the rotor 4 to the stator 3 has a sinusoidal shape, and the rotor core has a sinusoidal shape. It has been found that the iron loss due to 20 can be reduced and the torque ripple and radial force can be reduced. Hereinafter, the specific arrangement of the first magnet 30, the second magnet 40, and the first recess 51 will be described.

As shown in FIG. 4, when viewed from the axial direction of the rotor core 20, the angle formed by the two radii passing through the outer peripheral end angle Ep1 of the first magnet 30 is the angle formed by the first magnet opening angle V1 and the outer peripheral end angle Ep2 of the second magnet 40. The angle formed by the two radii passing through is the second magnet opening angle V2, and the angle Vw1 formed by the two radii passing through the inner edge Fp1 of the pair of first recesses 51 is the lower limit, and the outer edge Fp2 of the pair of first recesses 51 is set as the lower limit. The range with the upper limit of the angle Vw2 formed by the two radii passing through is defined as the recessed opening range Wd.

Here, the first magnet opening angle V1 is a virtual straight line passing through the center of the rotor core 20 (axis C) and the outer peripheral end angle Ep1 of the first magnet 30, the center of the rotor core 20, and the outer peripheral other end angle Ep1 of the first magnet 30 ( It means an angle formed by a virtual straight line passing through an end angle opposite to the outer peripheral end angle of the first magnet 30 in the circumferential direction.
The second magnet opening angle V2 is a virtual straight line passing through the center of the rotor core 20 and the outer peripheral end angle Ep2 of the second magnet 40, the center of the rotor core 20 and the outer peripheral other end angle Ep2 of the second magnet 40 (second magnet 40 in the circumferential direction). It means the angle formed by the virtual straight line passing through (the end angle opposite to the one end angle of the outer circumference).
The dent opening range Wd is a virtual straight line passing through the center of the rotor core 20 and the inner edge Fp1 of one of the first dents 51, and the inner edge Fp1 of the center of the rotor core 20 and the other first dent 51 (one of the first in the circumferential direction). The lower limit is the angle Vw1 formed by the virtual straight line passing through the inner edge of the first recess 51 located on the opposite side of the recess 51, and the center of the rotor core 20 and the outer edge Fp2 of one of the first recess 51 are set. A virtual straight line passing through and a virtual straight line passing through the center of the rotor core 20 and the outer edge Fp2 of the other first recess 51 (the outer edge of the first recess 51 located on the opposite side of the first recess 51 in the circumferential direction). It means an angle range with the upper limit value of the angle Vw2 formed by the line.

In the present embodiment, the first magnet opening angle V1, the second magnet opening angle V2, and the recessed opening range Wd satisfy the following equations (1) to (3), respectively.
31 ° ≤ V1 ≤ 35 ° ... (1)
16 ° ≤ V2 ≤ 20 ° ... (2)
34 ° ≤ Wd ≤ 44 ° ... (3)

In the example of FIG. 4, the first magnet opening angle V1 is smaller than the lower limit value Vw1 of the recess opening range Wd. The shape of the recess in the present embodiment is curved, but the shape is not limited to this, and various shapes can be adopted as long as the recess opening range Wd is within the range of the above equation (3).

<Principle>
Next, the magnetic flux flowing from the rotor 4 to the stator 3 will be described by focusing on one tooth 14 of the stator 3. FIG. 5 is an explanatory diagram of the magnetic flux flowing from the rotor 4 to the stator 3. Arrows in the figure indicate the flow of magnetic flux.
When focusing on one tooth 14 of the stator 3, the magnetic flux flowing into the tooth 14 from the rotor 4 is defined as Ψ. Then, the potential difference V in the steel sheet for generating the eddy current in the electromagnetic steel sheet due to the change in the magnetic flux Ψ is expressed by the following equation (11).

Then, the Joule heat W generated by the eddy current generated in the steel sheet is represented by the following equation (12).

From the above equation (12), in order to reduce the iron loss due to the rotor core 20, it is necessary to reduce the time variation of the magnetic flux Ψ. That is, in order to reduce the loss, it is important to reduce the harmonic component and make the magnetic flux fluctuation flowing from the rotor 4 into the teeth 14 a sinusoidal shape.

Next, the reason why the loss worsens when a high frequency component is included will be described.
When the magnetic flux fluctuation is decomposed by frequency, it can be seen that the magnetic flux fluctuation can be expressed by the sum of the waves of each frequency.
Since the magnetic flux fluctuation is a superposition of waves, the magnetic flux Ψ can be decomposed as shown in the following equation (21). In equation (21), i is a frequency component.

Similarly, Joule heat W can be decomposed as shown in the following equation (22).

From the above equations (21) and (22), the harmonic components (Ψ2 + Ψ3 + ... + Ψn in the equation) are added to the loss, so how to reduce the harmonic components (magnetic flux fluctuation). It is important to make it closer to the sinusoidal shape) in order to reduce the loss.

<Effect>
FIG. 6 is an explanatory diagram of the amount of magnetic flux flowing into the stator 3. FIG. 6 shows a change in the amount of magnetic flux when the vertical axis is the amount of magnetic flux flowing from the rotor 4 to the stator 3 and the horizontal axis is the rotation angle [deg] of the rotor 4. In FIG. 6, the solid line graph shows the case where the first magnet 30, the second magnet 40 and the recesses 51 and 52 are optimally arranged (the present embodiment), and the alternate long and short dash line graph shows only the first magnet 30 and the second magnet 40. Is the optimum arrangement (a modified example having no recesses 51 and 52 with respect to the present embodiment), and the graph of the alternate long and short dash line is the case of the arrangement of single-layer V-shaped magnets (see FIG. 10) (conventional case). Are shown respectively.

As shown in FIG. 6, in the case of the present embodiment, it can be confirmed that the magnetic flux fluctuation is closer to the sinusoidal shape as compared with the conventional case and the modified example. For example, in the conventional case, the portion where the magnetic flux fluctuation is large (circled portion) is reduced in the present embodiment.
In the case of the modified example as well, it can be confirmed that the magnetic flux fluctuation is closer to the sinusoidal shape as compared with the conventional case.

FIG. 7 is an explanatory diagram of the time derivative of the amount of magnetic flux flowing into the stator. FIG. 7 shows the change in the time derivative of the amount of magnetic flux when the vertical axis is the time derivative of the amount of magnetic flux flowing from the rotor 4 to the stator 3 and the horizontal axis is the rotation angle [deg] of the rotor. Similarly to the above, in FIG. 7, the solid line graph shows the present embodiment, the one-dot chain line graph shows a modified example, and the two-dot chain line graph shows the conventional case.

As shown in FIG. 7, in the case of the present embodiment, it can be confirmed that the portion (circled portion) in which the change in the time derivative of the magnetic flux amount is large can be reduced as compared with the conventional case and the modified example.
In the case of the modified example as well, it can be confirmed that the portion (circled portion) in which the change in the time derivative of the magnetic flux amount is large can be reduced as compared with the conventional case.

FIG. 8 is an explanatory diagram of the effect of loss reduction. FIG. 8 shows a comparison of losses when the vertical axis represents the loss [W] and the horizontal axis represents each configuration example. Similarly to the above, in FIG. 8, when the first magnet 30, the second magnet 40 and the recess are optimally arranged in the “present embodiment”, only the first magnet 30 and the second magnet 40 are optimally arranged in the “deformation example”. In the case of arrangement, "conventional" indicates the case of arrangement of single-layer V-shaped magnets (see FIG. 10).

As shown in FIG. 8, in the case of this embodiment, it can be confirmed that the loss can be significantly reduced as compared with the conventional case and the modified example.
In the case of the modified example as well, it can be confirmed that the loss can be significantly reduced as compared with the conventional case.

FIG. 9 is an explanatory diagram of the effect of reducing torque ripple. FIG. 9 shows the change in torque when the vertical axis is the torque [Nm] of the rotary electric machine and the horizontal axis is the rotation angle [deg] of the rotor. Similarly to the above, in FIG. 9, the solid line graph shows the present embodiment, and the two-dot chain line graph shows the conventional case.

As shown in FIG. 9, in the case of this embodiment, it can be confirmed that the torque ripple can be reduced as compared with the conventional case.

In principle, torque ripple and radial forces are generated by the electromagnetic force between the rotor and the stator. Therefore, in the magnetic circuit having a sinusoidal shape of the magnetic flux fluctuation as in the present embodiment, the torque ripple and the radial force can be significantly reduced as compared with the conventional case.

Next, the advantages of design strength due to the two-layer V-shaped magnet structure will be described.
First, the conventional model will be described. FIG. 10 is an explanatory diagram of stress generated in the conventional rotor 4X. In FIG. 10, reference numerals 31X, 32X, 33X are three magnets arranged so as to form a V shape that opens outward in the radial direction, and reference numeral 35X is a flux barrier that covers the outer peripheral ends of the side magnets 32X, 33X. 38X indicates an outer peripheral beam portion facing the flux barrier 35X on the outer periphery of the rotor core 20X. The V-shaped angle AX of the conventional model (opening angle of the two side magnets 32X and 33X having a V-shape) is about 140 °.

In the conventional case, since the V-shaped angle AX of the magnets 32X and 33X is large (about 140 °), the centrifugal force of the magnets 32X and 33X (force generated in the direction of the arrow in the figure) during rotor rotation causes the outer beam portion 38X. Stress increases. In the figure, reference numeral PwX indicates a portion of the rotor core 20X (rotor yoke) having the weakest strength (hereinafter, also referred to as “the weakest portion of the yoke”) (circled portion). In the conventional case, since the weakest portion PwX of the yoke is the outer peripheral beam portion 38X, groove processing (formation of a dent) around the outer peripheral beam portion 38X is restricted. In particular, the conventional model has a disadvantageous shape for a high rotation type motor (for example, a rotation speed of 10,000 rpm or more).

On the other hand, in this embodiment, as shown in FIG. 11, the V-shaped angle A1 (first V-shaped angle) of the magnet (first magnet 30) is smaller than the conventional one (about 110 °). In the figure, reference numeral Pw is the weakest portion of the yoke, reference numeral 38 is the first outer peripheral beam portion facing the q-axis side first gap 36 on the outer periphery of the rotor core 20, and reference numeral 39 is from the first outer peripheral beam portion 38 on the outer periphery of the rotor core 20. Also shows the thick parts located closer to the q-axis. In the case of the present embodiment, most of the centrifugal force (force generated in the direction of the arrow in the figure) of the first magnet 30 is applied to the thick portion 39. Since the thick portion 39 acts as a strong beam, the strength of the first magnet 30 against the centrifugal force becomes very high. Therefore, in the present embodiment, grooving around the first outer peripheral beam portion 38 becomes easy. That is, according to the present embodiment, it becomes easy to process around the outer peripheral beam portion (for example, to form the dents 51 and 52), which has been conventionally restricted in processing.

As described above, the rotor 4 of the rotary electric machine 1 of the above embodiment includes a rotor core 20 and magnets 30 and 40 embedded inside the rotor core 20, and the magnets 30 and 40 are in the axial direction of the rotor core 20. A V-shape that opens outward in the radial direction of the rotor core 20 with the d-axis Ld as the axis of symmetry is formed, and a plurality of rows are arranged side by side in the radial direction of the rotor core 20, and the rotor core 20 is recessed in the outer peripheral surface of the rotor core 20. The recesses 51 and 52 have 51 and 52, and the recesses 51 and 52 are arranged in at least a pair with the d-axis Ld as the axis of symmetry when viewed from the axial direction of the rotor core 20, and the recesses 51 and 52 of the magnets 30 and 40 in a plurality of rows when viewed from the axial direction of the rotor core 20. The angle formed by the two radii passing through the outer peripheral both end angles Ep1 of the innermost magnet 30 located on the innermost circumference is the first magnet opening angle V1, and the outermost magnet 40 located on the outermost circumference among the multiple rows of magnets 30 and 40. The angle formed by the two radii passing through the outer peripheral edge angles Ep2 is the second magnet opening angle V2, and the angle Vw1 formed by the two radii passing through the inner edge Fp1 of the pair of dents 51 is the lower limit, and the outer edge of the pair of dents 51 When the range with the upper limit of the angle Vw2 formed by the two radii passing through Fp2 as the upper limit is the recessed opening range Wd, the following equations (1) to (3) are satisfied.
31 ° ≤ V1 ≤ 35 ° ... (1)
16 ° ≤ V2 ≤ 20 ° ... (2)
34 ° ≤ Wd ≤ 44 ° ... (3)
According to this configuration, by satisfying the above equations (1) to (3), the fluctuation of the magnetic flux flowing from the rotor 4 to the stator 3 has a sinusoidal shape, so that iron loss due to the rotor core 20 is reduced and torque ripple is performed. And the radial force can be reduced. Therefore, low loss and low noise can be realized.

In the above embodiment, the rotor core 20 has a gap 46 (second gap on the q-axis side) between the outer peripheral end angle Ep2 of the outermost magnet 40 and the recess 52, so that the wraparound of the magnetic flux can be further suppressed.

In the above embodiment, the number of pole pairs of the rotor core 20 is four pole pairs, so that the arrangement of the magnets 30 and 40 and the like can be optimized.

The rotary electric machine 1 of the above embodiment can realize low loss and low noise by including the annular stator 3 and the rotor 4 arranged inside the stator 3 in the radial direction. The rotary electric machine 1 can be provided.

In the above embodiment, the stator 3 has 48 slots 13 so that the arrangement of the coils 12 and the like can be optimized.

Hereinafter, a modified example of the embodiment will be described. In each modification, the same components as those in the embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the above-described embodiment, the rotor 4 has been described with reference to an example of having a two-layer V-shaped magnet structure having a first magnet 30 and a second magnet 40, but the present invention is not limited to this. For example, the rotor 4 may have a V-shaped magnet structure having three or more layers including a third magnet. That is, the magnets have a V shape that opens outward in the radial direction of the rotor core 20 with the d-axis as the axis of symmetry when viewed from the axial direction of the rotor core 20, and are arranged side by side in three or more rows in the radial direction of the rotor core 20. May be good.

In the above-described embodiment, the rotor core 20 has been described with reference to an example in which the rotor core 20 has a second recess 52 located on the d-axis side of the first recess 51, but the present invention is not limited to this. For example, the rotor core 20 does not have to have the second recess 52. That is, the rotor core 20 may have only the first recess 51. For example, the rotor core 20 does not have to have recesses 51 and 52 on the outer peripheral surface.

In the above-described embodiment, the number of pole pairs of the rotor core 20 has been described by giving an example of four pole pairs, but the present invention is not limited to this. For example, the number of pole pairs of the rotor core 20 can be appropriately changed according to the required specifications.

In the above-described embodiment, the stator has been described with reference to an example having 48 slots 13, but the present invention is not limited to this. For example, the number of slots 13 arranged can be appropriately changed according to the required specifications.

In the above-described embodiment, the rotary electric machine 1 has been described with reference to an example in which the rotary electric machine 1 is a traveling motor mounted on a vehicle such as a hybrid vehicle or an electric vehicle, but the present invention is not limited to this. For example, the rotary electric machine 1 may be a motor for power generation, a motor for other purposes, or a rotary electric machine (including a generator) other than for vehicles.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and configurations can be added, omitted, replaced, and other changes can be made without departing from the spirit of the present invention. Yes, it is also possible to appropriately combine the above-mentioned modification examples.

1 ... Rotating machine 3 ... Stator 4 ... Rotor 13 ... Slot 20 ... Rotor core 30 ... First magnet (magnet)
40 ... Second magnet (magnet)
46 ... Second gap on the q-axis side (void)
51 ... First dent (dent)
52 ... Second dent (dent)
Ep1 ... First outer peripheral edge angle (outermost peripheral edge angle of the innermost magnet)
Ep2 ... Second outer peripheral edge angle (outermost peripheral edge angle of the outermost magnet)
Fp1 ... Inner edge Fp2 ... Outer edge Ld ... d-axis V1 ... First magnet opening angle V2 ... Second magnet opening angle Wd ... Recessed opening range

Claims (5)

With the rotor core
With a magnet embedded inside the rotor core,
The magnets have a V shape that opens outward in the radial direction of the rotor core with the d-axis as the axis of symmetry when viewed from the axial direction of the rotor core, and are arranged in a plurality of rows in the radial direction of the rotor core.
The rotor core has a recess on the outer peripheral surface of the rotor core.
The recesses are arranged in at least a pair with the d-axis as the axis of symmetry when viewed from the axial direction of the rotor core.
Seen from the axial direction of the rotor core
The angle formed by the two radii passing through the outer peripheral corners of the innermost magnet located on the innermost circumference of the plurality of rows of magnets is the angle formed by the first magnet opening angle V1.
The angle formed by the two radii passing through the outer peripheral end corners of the outermost magnet located on the outermost circumference of the plurality of rows of magnets is the angle formed by the second magnet opening angle V2.
When the lower limit is the angle formed by the two radii passing through the inner edge of the pair of dents and the upper limit is the angle formed by the two radii passing through the outer edge of the pair of dents, the dent opening range Wd is defined.
A rotor for a rotary electric machine, which satisfies the following equations (1) to (3).
31 ° ≤ V1 ≤ 35 ° ... (1)
16 ° ≤ V2 ≤ 20 ° ... (2)
34 ° ≤ Wd ≤ 44 ° ... (3) The rotor of a rotary electric machine according to claim 1, wherein the rotor core has a gap between the outer peripheral end angle of the outermost magnet and the recess. The rotor of a rotary electric machine according to claim 1 or 2, wherein the number of pole pairs of the rotor core is four pole pairs. With an annular stator,
A rotary electric machine comprising the rotor according to any one of claims 1 to 3, which is arranged inside the stator in the radial direction. The rotary electric machine according to claim 4, wherein the stator has 48 slots.

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