JP2018082562A - Rotor for magnet-embedded motor and magnet-embedded motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance durability against centrifugal force of a rotor, and suppress an occurrence of stress concentration to a rotor core, thereby preventing a deformation of the rotor core and a dispersion of a permanent magnet.SOLUTION: A rotor 10 for magnet-embedded motor in which a permanent magnet 16 is embedded in a rotor core 12 where a plurality of rotor core plates 12a are laminated along a rotor axis direction has a reinforcing plate 18 interposed between a plurality of rotor core plates, and a permanent magnet stored in a magnet attaching space formed in the rotor axis direction by a first magnet attaching hole 14 formed in a plurality of rotor core plates and a second magnet attaching hole 20 formed in the reinforcing plate. Both ends of the first magnet attaching hole and the second magnet attaching hole have border lines composed of continuous curve lines, a first gap s1 is formed between both ends of the permanent magnet and the border line of the first magnet attaching hole, and a second gap s2 is formed between both ends of the permanent magnet and the border line of the second magnet attaching hole.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a rotor for an embedded magnet motor and an embedded magnet motor including the rotor.

In recent years, electric motors are required to be smaller and faster in order to improve the performance of devices to which they are attached. Since the centrifugal force increases as the speed of the electric motor increases, durability against the centrifugal force is required. A magnet-embedded motor (IPM motor) in which a permanent magnet is embedded in a rotor core is more durable against centrifugal force than a magnet surface-attached motor (SPM motor) in which a permanent magnet is disposed on the surface of a rotor core.
In addition, the magnet-embedded motor has an advantage that reluctance torque generated by the rotating magnetic field of the stator can be used in addition to magnet torque (attraction force or repulsive force generated between the stator and the permanent magnet). In some cases, a gap is formed in the mounting hole of the permanent magnet in order to increase the reluctance torque, but the formation of the gap may weaken the durability against centrifugal force.

Patent Document 1 discloses means for covering a permanent magnet with a circular protective ring in order to prevent the permanent magnet from floating and scattering during high-speed rotation in an SMP motor.
Patent Document 2 discloses a means for preventing scattering of permanent magnets by using an intermediate plate interposed between a plurality of laminated rotor core plates forming a rotor core and fixed plates provided at both axial ends of the rotor core. Has been.

JP 2005-312250 A JP 2008-099479 A

The means for covering the permanent magnet with the circular tubular protective ring disclosed in Patent Document 1 has a problem of reducing the torque generated in the rotor core in order to widen the gap between the stator and the rotor core.
The magnet-embedded motor disclosed in Patent Document 2 has a rectangular outline of a mounting hole for attaching a permanent magnet, so stress concentration occurs at a portion where a discontinuous outline is formed at high speed rotation, and deformation or breakage occurs. There is a risk.

  Some embodiments improve durability of the rotor against centrifugal force and suppress stress concentration in the rotor core in an embedded magnet motor, thereby preventing deformation of the rotor core and scattering of permanent magnets. The purpose is to do.

(1) The rotor for an embedded magnet motor according to at least one embodiment,
A rotor for a magnet-embedded motor in which a permanent magnet is embedded in a rotor core obtained by laminating a plurality of rotor core plates along the rotor axial direction,
A reinforcing plate interposed between the plurality of rotor core plates;
The permanent magnet accommodated in the magnet mounting space formed in the rotor axial direction by the first magnet mounting hole formed in the plurality of rotor core plates and the second magnet mounting hole formed in the reinforcing plate;
With
Both ends of the first magnet mounting hole and the second magnet mounting hole have a contour line constituted by a continuous curved line,
A first gap is formed between both ends of the permanent magnet and the contour line of the first magnet mounting hole, and a first gap is formed between both ends of the permanent magnet and the contour line of the second magnet mounting hole. Two voids are formed.

According to the configuration of (1) above, the durability against the centrifugal force of the rotor core can be improved by interposing the reinforcing plate between the plurality of laminated rotor core plates. Thereby, deformation of the rotor core and scattering of the permanent magnet can be prevented.
Moreover, since the outline of the both ends of a 1st magnet attachment hole and a 2nd magnet attachment hole has a continuous curve line and does not have a discontinuous line, a 1st magnet attachment hole and a 2nd magnet attachment hole Around the periphery, the rotor core plate and the reinforcing plate can suppress stress concentration, thereby suppressing the deformation of the rotor core and the scattering of the permanent magnets.
The reinforcing plate preferably includes a high-strength material such as fiber reinforced plastic (FRP) if it is a thin, hard steel plate or non-metal. Further, it is desirable that the reinforcing plate is made of a material that does not allow eddy current to flow, such as FRP having a large electric resistance, and stainless steel, titanium or the like as a metal. Heat generation can be suppressed by suppressing the generation of eddy currents.

(2) In one embodiment, in the configuration of (1),
The cross-sectional area of the second gap is smaller than the cross-sectional area of the first gap.
The first gap formed at both ends of the rotor core plate is for generating reluctance torque, and the reluctance torque can be increased by forming the cross-sectional area relatively large. On the other hand, the 2nd space | gap formed in the both ends of a reinforcement board is formed in order to make the outline of the both ends of a 2nd magnet attachment hole into a continuous curve line, and if cross-sectional area is enlarged more than necessary, it will reinforce. The strength of the plate is lowered, and the purpose of preventing the permanent magnets from scattering cannot be achieved. Therefore, the cross-sectional area of the second gap is formed smaller than the cross-sectional area of the first gap.
In this way, the first gap and the second gap can be uniquely designed for each purpose.

(3) In one embodiment, in the configuration of (1) or (2),
The plurality of magnet mounting spaces are formed in the circumferential direction of the rotor core at the outer peripheral portion of the rotor core, and the plurality of permanent magnets are mounted in each of the plurality of magnet mounting spaces. Since a plurality of permanent magnets are disposed in the circumferential direction of the rotor core on the outer peripheral portion of the rotor, both the magnet torque and the reluctance torque can be increased. Further, by dividing the permanent magnet into a plurality of parts, generation of eddy current can be suppressed and heat generation due to eddy current can be suppressed.

(4) In one embodiment, in any one of the configurations (1) to (3),
In the magnet mounting space, the plurality of permanent magnets are divided along the rotor axial direction and arranged in series.
According to the configuration of (4) above, since the plurality of permanent magnets are divided along the rotor axial direction and arranged in series, the generation of eddy currents can be suppressed and heat generation due to eddy currents can be suppressed.

(5) In one embodiment, in any one of the configurations (1) to (4),
The plurality of reinforcing plates are interposed between the plurality of rotor core plates at different positions in the rotor axial direction.
According to the configuration of (5) above, by distributing a plurality of reinforcing plates in the rotor axial direction, durability against centrifugal force can be uniformly imparted to the entire rotor core, and by adjusting the number of reinforcing plates, Sufficient durability can be imparted to the rotor core as required.

(6) In one embodiment, in the configuration of (5),
For each of the permanent magnets, two or more reinforcing plates are arranged in the rotor axial direction.
According to the configuration of (6) above, the centrifugal force applied to each rotor core plate can be suppressed below the yield point of the rotor core plate.

(7) In one embodiment, in any one of the configurations (1) to (6),
The first gap has a semi-elliptical shape.
According to the configuration of (7) above, by making the first gap a semi-elliptical shape, it is possible to avoid stress concentration in the rotor core plate forming the first gap, and to reduce the reluctance torque generated in the rotor core plate. Can be increased.

(8) In one embodiment, in any one of the configurations (1) to (7),
The cross section of the second gap has a semicircular shape or a semielliptical shape.
According to the configuration of (8) above, by making the cross section of the second gap semi-circular or semi-elliptical, it is possible to avoid stress concentration in the reinforcing plate that forms the first gap, and to the rotor core plate. The applied centrifugal force can be suppressed below the yield point.

(9) A magnet-embedded motor according to some embodiments includes:
The magnet-embedded motor rotor having any one of the constitutions (1) to (8) is provided.
According to the configuration of (9), since the reinforcing plate is interposed between the plurality of laminated rotor core plates, the durability against the centrifugal force of the rotor core can be improved, whereby the deformation of the rotor core and the scattering of the permanent magnets can be achieved. Can be prevented.
In addition, the contour lines at both ends of the first magnet mounting hole and the second magnet mounting hole have continuous curved lines and no discontinuous lines, so stress concentration occurs in the rotor core plate and the reinforcing plate. Can be suppressed.

(10) In one embodiment, in the configuration of (9),
The rotational speed of the magnet-embedded motor rotor is 10,000 rpm or more.
According to the configuration of (10), the durability against centrifugal force generated in the rotor is improved even when the rotor rotation speed of the embedded magnet motor having the configuration of (9) is high speed rotation of 10,000 rpm or more. In addition, it is possible to suppress the occurrence of stress concentration in the rotor core and the reinforcing plate, thereby preventing damage to the rotor core and scattering of the permanent magnets.

  According to some embodiments, in a magnet-embedded motor, damage to the rotor core is improved by improving durability against centrifugal force generated during high-speed rotation and suppressing stress concentration from occurring in the rotor core and the reinforcing plate. And scattering of permanent magnets can be prevented.

It is sectional drawing of the magnet embedded type motor which concerns on one Embodiment. It is a perspective view which shows a part of magnet embedded motor which concerns on one Embodiment. It is a perspective view which shows the reinforcement board which concerns on one Embodiment. It is a chart which shows the number of sheets and shape of a reinforcing board which were used for measurement of principal stress. It is a diagram which shows the main stress added to the rotor core board which concerns on one Embodiment. It is a diagram which shows the main stress added to the rotor core board which concerns on one Embodiment. It is a diagram which shows the main stress added to the permanent magnet which concerns on one Embodiment. It is sectional drawing of the magnet embedded type motor as a comparative example. It is a perspective view which shows the reinforcement board as a comparative example.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of other constituent elements.

As shown in FIG. 1 and FIG. 2, a rotor for a magnet-embedded motor (hereinafter also referred to as “IPM rotor”) 10 according to at least one embodiment is a rotor core in which a plurality of rotor core plates 12 a are stacked along the rotor axial direction. 12 has a configuration in which a permanent magnet 16 is embedded. A nonmagnetic reinforcing plate 18 is interposed between the plurality of laminated rotor core plates 12a.
Each rotor core plate 12 a is formed with a first magnet mounting hole 14, and the reinforcing plate 18 is formed with a second magnet mounting hole 20. The first magnet mounting hole 14 and the second magnet mounting hole 20 are orthogonal to the rotor axial direction (arrow a direction in FIG. 1) so that these contour lines overlap with the rotor axial direction (arrow a direction in FIG. 2). Formed at the same position on the surface, a magnet mounting space is formed in the rotor axial direction.

  Both ends of the first magnet mounting hole 14 and the second magnet mounting hole 20 have a contour line constituted by a continuous curved line, and between the both ends of the permanent magnet 16 and the contour line of the first magnet mounting hole 14. A first gap s1 is formed in the first. A second gap s <b> 2 is formed between both ends of the permanent magnet 16 and the contour line of the second magnet mounting hole 20.

According to the above configuration, the rotor core 12 can improve durability against the centrifugal force generated by the rotation of the rotor core 12 by interposing the reinforcing plate 18 between the plurality of laminated rotor core plates 12a. Thereby, deformation of the rotor core 12 and scattering of the permanent magnet 16 can be prevented. Further, as described above, the reinforcing plate 18 is desirably made of a material that can suppress the generation of eddy currents in the rotor core 12 and can suppress the heat generation due to the eddy currents.
Further, the contour lines at both ends of the first magnet mounting hole 14 and the second magnet mounting hole 20, that is, the contour lines forming the first air gap s1 and the second air gap s2, have a continuous curved line, Does not have a continuous line. Therefore, the rotor core plate 12a and the reinforcing plate 18 can suppress stress concentration around the first magnet mounting hole 14 and the second magnet mounting hole 20, and the deformation of the rotor core 12 and the scattering of the permanent magnet 16 can be suppressed.

In one embodiment, the rotor core plate 12a is made of, for example, a magnetic metal having a plate thickness of 0.35 mm or less, and the rotor core 12 is made of a laminate of the rotor core plates 12a. As the magnetic metal, for example, an iron-based metal such as silicon steel, pure iron, alloy steel, or the like is used. Since the rotor core 12 is configured by stacking a large number of rotor core plates 12a, heat generation due to generation of eddy currents can be suppressed.
In one embodiment, the reinforcing plate 18 is made of, for example, titanium or stainless steel that is a non-magnetic material.

In one embodiment, the attachment holes 22 are formed in each of the large number of rotor core plates 12a and the reinforcing plates 18, and the attachment holes are formed in the rotor axial direction by stacking the rotor core plates 12a. It is fixed integrally by a fixture (not shown) inserted into the mounting hole 22.
In one embodiment, the rotor core 12 is fixed integrally with the rotary shaft 24 on the outer peripheral side of the rotary shaft 24.
In one embodiment, as shown in FIGS. 1 and 2, the magnet-embedded motor 1 includes a rotating shaft 24, a rotor core 12, a stator core 26 disposed on the outer peripheral side of the rotor core 12, and the stator core 26 in the rotor axial direction. And a coil 28 embedded in a number of grooves formed along the line. The stator core 26 is configured by laminating a number of thin magnetic plates.

In one embodiment, the cross-sectional area of the second gap s2 is smaller than the cross-sectional area of the first gap s1.
The first gap s1 formed at both ends of the rotor core plate 12a is for generating reluctance torque, and the reluctance torque can be increased by forming the cross-sectional area relatively large. On the other hand, the second gap s2 formed at both ends of the reinforcing plate 18 is formed so that the contour lines at both ends of the second magnet mounting hole 20 are continuous curved lines. The strength of the reinforcing plate 18 is lowered, and the purpose of preventing the permanent magnets 16 from being scattered cannot be achieved. Therefore, the cross-sectional area of the second gap s2 is formed smaller than the cross-sectional area of the first gap s1.
Further, by forming the cross-sectional area of the second air gap s2 smaller than the cross-sectional area of the first air gap s1, it is possible to uniquely design the first air gap and the second air gap for each purpose.

In one embodiment, as shown in FIGS. 1 and 2, the magnet mounting space formed by the plurality of first magnet mounting holes 14 and the second magnet mounting holes 20 is the outer peripheral portion of the rotor core 12 in the circumferential direction of the rotor core 12. The plurality of permanent magnets 16 are formed and attached to each of the plurality of magnet mounting spaces.
Magnet torque is generated by the magnetic flux expressed by the magnetic force lines Lm formed across the rotor core 12 and the stator core 26, and reluctance torque is generated by the magnetic flux expressed by the magnetic force lines Lm formed between the permanent magnets 16.
Since the plurality of permanent magnets 16 are arranged along the circumferential direction of the rotor core 12 on the outer periphery of the rotor core 12, both the magnet torque and the reluctance torque can be increased.

  In one embodiment, as shown in FIGS. 2 and 3, the permanent magnet 16 has a rectangular parallelepiped shape, has a short side in the motor radial direction, and a long side is arranged in the motor circumferential direction. The first magnet mounting hole 14 and the second magnet mounting hole 20 extend in the circumferential direction of the motor in accordance with the cross-sectional shape of the permanent magnet 16, and a first gap s1 and a second gap s2 are formed at both ends.

FIG. 8 shows a magnet-embedded motor 100 as a comparative example, and FIG. 9 shows a reinforcing plate 118 as a comparative example.
In IPM motor 100 shown in FIG. 8, the magnet mounting space S ₀ which are formed at the two ends of the magnet mounting hole 106 has a pseudo-circular wide cross-sectional area. If having the magnet mounting space S _0, provides optimal electromagnetic analysis on reluctance torque, it is also suppressed magnetic lines short circuit the permanent magnet alone. The distortion of the magnetic field lines intersecting the stator core 104 through the air gap between the rotor core 102 and the stator core 104 generates torque.

However, thin and bridge portion 108 that extends laterally connecting the radially outer region of the magnet mounting space S _0, a post portion 110 extending from the circumferential direction intermediate portion of the bridge portion 108 on the shaft center side of the rotor core 102 Therefore, the centrifugal force generated during high-speed rotation may exceed these tensile strengths. Therefore, the bridge part 108 and the support | pillar part 110 may deform | transform or break, and there exists a possibility that the permanent magnet 114 attached to the magnet attachment hole 106 cannot be hold | maintained.
Therefore, the first gap s1 is preferably a semi-elliptical shape that can increase the reluctance torque from a semi-circular shape. By making it semi-elliptical, the bridge part 108 can be thickened and the tensile strength of the bridge part 108 can be increased. Moreover, by making it a semi-elliptical shape and lengthening the short circuit path of the magnetic field lines of the permanent magnet alone, the short circuit path can be reduced and the torque applied to the rotor core 12 can be increased.

  In the comparative example shown in FIG. 9, the magnet mounting hole 120 formed in the reinforcing plate 118 interposed between the rotor core plates has a rectangular shape that matches the cross-sectional shape of the permanent magnet 114. Therefore, stress concentration tends to occur at the corners, and there is a risk of deformation or damage.

In one embodiment, a plurality of permanent magnets 16 are arranged in series along the rotor axial direction in a magnet mounting space formed along the rotor axial direction by the plurality of first magnet mounting holes 14 and the second magnet mounting holes 20. Is done. In FIG. 2, the IPM motor 1 is partially illustrated in the rotor axis direction, and only one permanent magnet 16 is disposed in the rotor axis direction. In practice, however, a plurality of permanent magnets 16 are arranged in the rotor mounting direction. Arranged in series along the direction.
In this way, the generation of eddy currents can be suppressed by arranging a plurality of permanent magnets 16 in series along the rotor axial direction instead of extending one permanent magnet 16 along the rotor axial direction. Heat generation due to eddy current can be suppressed.

In one embodiment, the plurality of reinforcing plates 18 are interposed between the plurality of rotor core plates 12a at different positions in the rotor axial direction. That is, the plurality of reinforcing plates 18 are arranged in a distributed manner between the rotor core plates 12a in the rotor axial direction.
According to the above configuration, the plurality of reinforcing plates 18 are distributed and arranged in the rotor axial direction, whereby durability against centrifugal force can be uniformly imparted to the entire rotor core, and the number of reinforcing plates 18 can be adjusted to adjust the rotor core 12. Sufficient strength can be imparted if necessary.

In one embodiment, as shown in FIGS. 2 and 3, two or more reinforcing plates 18 are disposed in the rotor axial direction for each permanent magnet.
As a result, the centrifugal force applied to the rotor core 12 can be suppressed below the yield point of each rotor core plate 12a.

  In one embodiment, the cross section of the first gap s1 has a semi-elliptical shape. By making the cross section of the first gap s1 a semi-elliptical shape, it is possible to avoid stress concentration in the rotor core plate 12a that forms the first gap s1. Further, the centrifugal force applied to the rotor core plate 12a can be suppressed to less than the yield point of the rotor core plate 12a. In addition, the reluctance torque can be increased by making the cross section of the first gap s1 a semi-elliptical shape.

  In one embodiment, the cross section of the second gap s2 has a semicircular shape or a semielliptical shape. By making the cross section of the second gap s2 semi-circular or semi-elliptical, it is possible to avoid stress concentration at the reinforcing plate 18 forming the second gap s2, and yield the centrifugal force applied to the reinforcing plate 18 It can be kept below the point. In addition, the reluctance torque can be increased by making the cross section of the second gap s2 a semi-elliptical shape, and the displacement of the permanent magnet 16 in both end directions can be prevented by making the semi-circular shape.

4-7, a magnetic steel plate (electromagnetic steel plate) is used as the rotor core plate 12a, a stainless steel plate is used as the reinforcing plate 18, the first gap s1 is semi-elliptical, and the second gap s2 is square, semi-circular or The main stress applied to each rotor core plate 12a and each reinforcing plate 18 and the compressive stress applied to the permanent magnet 16 in the case of a semi-elliptical shape are obtained.
The horizontal axis of FIGS. 5-7 shows the number of each test body shown in FIG. 4, the vertical axis | shaft of FIG.5 and FIG.6 shows the main stress added to each rotor core board 12a, and the vertical axis | shaft of FIG. The compressive stress applied to 16 is shown. In FIG. 4, for example, the number of reinforcing plates 18 / three magnets means that three permanent magnets 16 are arranged in the rotor axial direction per permanent magnet as shown in FIG.

In FIG. 5, line A indicates the main stress applied to the rotor core plate 12 a, and point D indicates when the pseudo-circular gap shown in FIG. 8 is provided at both ends of the first magnet mounting hole 14 and the second magnet mounting hole 20. The main stress applied to the rotor core plate 12a is shown. The main stress applied to the rotor core plate 12a is less than the yield point of the rotor core plate 12a in numbers 2, 3, 5, 6, and 8.
Therefore, it can be seen from FIG. 5 that when the first gap s1 is semi-elliptical, the second gap s2 formed in the reinforcing plate 18 is preferably semicircular or semi-elliptical. It can also be seen that two or more reinforcing plates 18 are preferably arranged in the rotor axial direction per permanent magnet.

In FIG. 6, line B indicates the main stress applied to the reinforcing plate 18. Numbers 2, 3, 5, 6, 8, and 10 are the main stresses applied to the reinforcing plate 18 being less than the yield point of the reinforcing plate 18.
Therefore, it can be seen from FIG. 6 that the cross section of the second gap s2 formed in the reinforcing plate 18 is preferably semicircular or semielliptical.

  In FIG. 7, line C indicates the main stress applied to the permanent magnet 16. The numbers 2 to 9 indicate that the compressive stress applied to the permanent magnet 16 is lower than the magnet bending force. Therefore, it can be seen from FIG. 9 that the cross section of the second gap s2 formed in the reinforcing plate 18 may be semicircular, semielliptical, or rectangular in order to be less than the magnet bending force. In addition, since the main stress applied to the permanent magnets 16 with numbers 1 and 10 exceeds the magnet bending force, the number of permanent magnets 16 arranged in the rotor axial direction per permanent magnet should be 2 to 4. I understand that.

  According to some embodiments, in a magnet-embedded motor, durability of the rotor against centrifugal force is improved and stress concentration is suppressed from occurring in the rotor core, thereby preventing deformation of the rotor core and scattering of permanent magnets. Can be prevented.

DESCRIPTION OF SYMBOLS 1,100 Embedded magnet motor 10 Rotor for embedded magnet motors 12, 102 Rotor core 12a Rotor core plate 14 First magnet mounting hole 16, 114 Permanent magnet 18, 118 Reinforcement plate 20 Second magnet mounting hole 22 Mounting hole 24 Rotating shaft 26 , 104 Stator core 28 Coil 102 Rotor core 106 Magnet mounting hole 108 Bridge section 110 Post section Lm Magnetic field line S ₀ Magnet mounting space s1 First gap s2 Second gap

Claims (10)

A rotor for a magnet-embedded motor in which a permanent magnet is embedded in a rotor core obtained by laminating a plurality of rotor core plates along the rotor axial direction,
A reinforcing plate interposed between the plurality of rotor core plates;
The permanent magnet accommodated in the magnet mounting space formed in the rotor axial direction by the first magnet mounting hole formed in the plurality of rotor core plates and the second magnet mounting hole formed in the reinforcing plate;
With
Both ends of the first magnet mounting hole and the second magnet mounting hole have a contour line constituted by a continuous curved line,
A first gap is formed between both ends of the permanent magnet and the contour line of the first magnet mounting hole, and a first gap is formed between both ends of the permanent magnet and the contour line of the second magnet mounting hole. A rotor for a magnet-embedded motor, wherein two gaps are formed.   The rotor for a magnet-embedded motor according to claim 1, wherein a cross-sectional area of the second air gap is smaller than a cross-sectional area of the first air gap.   The plurality of magnet mounting spaces are formed in the circumferential direction of the rotor core at an outer peripheral portion of the rotor core, and the plurality of permanent magnets are mounted in each of the plurality of magnet mounting spaces. The rotor for motors with embedded magnets as described.   4. The magnet-embedded motor rotor according to claim 1, wherein a plurality of the permanent magnets are arranged in series along the rotor axial direction in the magnet mounting space. 5.   5. The magnet-embedded motor rotor according to claim 1, wherein the plurality of reinforcing plates are interposed between the plurality of rotor core plates at different positions in the rotor axial direction.   6. The rotor for a magnet-embedded motor according to claim 5, wherein two or more reinforcing plates are arranged in the rotor axial direction for each of the permanent magnets.   The rotor for a magnet-embedded motor according to any one of claims 1 to 6, wherein the first gap has a semi-elliptical shape.   8. The rotor for a magnet-embedded motor according to claim 1, wherein a cross section of the second gap has a semicircular shape or a semielliptical shape.   9. A magnet-embedded motor comprising the rotor for a magnet-embedded motor according to any one of claims 1 to 8.   10. The magnet-embedded motor according to claim 9, wherein the rotation speed of the magnet-embedded motor rotor is 10,000 rpm or more.

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