JPH059148U - Permanent magnet rotor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a permanent magnet rotor which has high energy efficiency and in which the outer peripheral ring portion of the electromagnetic steel sheet is not easily broken by the high speed rotation of the rotor. [Structure] A plurality of openings 6 for magnet pieces are provided in the vicinity of the outer periphery of a circular electromagnetic steel sheet 4, and the electromagnetic steel sheet 4 is formed in the vicinity of a connecting portion 9 of steel sheets formed between adjacent openings 6 for magnet pieces or the ends thereof. The inner steel plate 4a and the outer steel plate 4b are separated from each other, the inner steel plates 4a are laminated to form the yoke body 2a, and the outer side surfaces of the yoke body 2a alternate with the N poles and the S poles.
A plurality of permanent magnet pieces for field magnets 3a, 3
b, 3c, 3d are attached, and these permanent magnet pieces for field 3
A plurality of outer steel plates 4 were fitted onto the outer circumferences of a, 3b, 3c3d to form the yoke outer peripheral portion 2b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention inserts multiple permanent magnet pieces for field around the outer circumference of a cylindrical yoke, Permanent magnet rotation that prevents the permanent magnet pieces for field from scattering due to centrifugal force during rotation. Regarding the child.

[0002]

[Prior art]

  FIG. 15 is an exploded view of a conventional permanent magnet rotor. This conventional permanent magnet The rotor 29 includes a yoke 30, field permanent magnet pieces 31a, 31b, 31c and 31d. It consists of The yoke 30 is formed by laminating a large number of electromagnetic steel plates 32 integrally. Has been. Each electromagnetic steel plate 32 has a rotary shaft opening 33 into which the rotary shaft is fitted and inserted. , A sector shape in which the permanent magnet pieces 31a, 31b, 31c, 31d for field magnet are press-fitted into the peripheral portion. It has a magnet piece opening 34. Field permanent magnet pieces 31a, 31b, 31c, 31d is formed in a fan shape in cross section, and as shown in the figure, the outer side surfaces are alternately N poles and S poles. It is press-fitted into the magnet piece opening 34 so as to have the magnetism of the pole. Magnet piece near the periphery Since it has the opening 34 for a magnetic field, the electromagnetic steel plate 32 has the outer periphery and the permanent magnet piece 31a for a field. , 31b, 31c, 31d, the outer peripheral ring portion 35 and the permanent magnet for the field. A steel plate body 36 formed inside the magnet pieces 31a, 31b, 31c, 31d; It has a connecting portion 37 that connects the outer peripheral ring portion 35 and the steel plate body portion 36.

[0003]   When the permanent magnet rotor 29 rotates at high speed, as shown in FIG. The permanent magnet pieces 31a, 31b, 31c, 31d receive the centrifugal force F and are radially outwardly moved. Try to scatter. On the other hand, the connecting portion 37 is arranged radially inward of the outer peripheral ring portion 35. A pulling force T that pulls to As a result, the outer peripheral ring portion 35 of the electromagnetic steel plate 32 is continuously connected. Near the outer end of the connecting portion 37, as shown in the figure, a shearing force S is applied.

[0004]

[Problems to be solved by the device]

  However, the permissible stress is generally small with respect to the shear force in the outer ring of electromagnetic steel sheets. Since the permanent magnet rotor rotates at a high speed, Could be broken and the permanent magnet pieces for field could be scattered.   On the other hand, in order to increase the permissible stress against shearing force, It is conceivable to widen the width of the magnetic field, but make sure to fully utilize the magnetic force of the permanent magnet pieces for field. However, there is a problem that the efficiency of the motor becomes low.   Therefore, the object of the present invention is to achieve high energy efficiency and to realize high-speed rotation of the rotor. Provides a permanent magnet rotor that prevents the outer ring of electromagnetic steel plates from easily breaking To do.

[0005]

[Means for Solving the Problems]

  In order to achieve the above-mentioned object, the permanent magnet rotor of the first invention is a circular electromagnetic steel. A plurality of magnet piece openings are provided near the outer periphery of the plate, and are formed between the adjacent magnet piece openings. The electromagnetic steel plates are separated at the joints of the steel plates or near their ends to separate the inner and outer steel plates. A side steel plate, and the inner steel plates are laminated to form a yoke body portion. Attach multiple permanent magnet pieces for field to the outer periphery of the main body, and A plurality of the outer steel plates are fitted around the circumference to form a yoke outer peripheral portion.   The permanent magnet rotor according to the second aspect of the present invention has a plurality of circular magnetic steel plates in the vicinity of the outer periphery thereof. An opening for a magnet piece is provided, and a connecting portion of steel plates formed between the openings for adjacent magnet pieces or Has a through hole near its inner end that is easily broken by a predetermined centrifugal force. A large number of electromagnetic steel sheets are laminated to form a yoke, and a plurality of fields are placed in the opening for the magnet piece of this yoke. A permanent magnet piece for magnetism is inserted.   Furthermore, the permanent magnet rotor according to the third aspect of the present invention is provided with a plurality of circular magnetic steel plates in the vicinity of the outer periphery thereof. A magnet piece opening is provided, and the width of the connecting portion of the steel sheet formed between the adjacent magnet piece openings is wide. To form a stress relaxation part that stretches and deforms by a predetermined centrifugal force, A large number of magnetic steel sheets having this stress relaxation portion are laminated to form a yoke, A plurality of permanent magnet pieces for field magnets are inserted into the openings for magnet pieces.

[0006]

[Action]

  The permanent magnet rotation of the present invention in which the electromagnetic steel plate is divided into an outer steel plate and an inner steel plate When the permanent magnet rotor rotates at high speed, the child is connected to the outer ring of the electromagnetic steel plate. Since the shearing stress is not generated by the tensile force of the It is converted into tensile stress in the circumferential direction of the outer peripheral ring portion of the magnetic steel sheet. Generally the outer circumference of electrical steel The ring part has a large allowable stress against the tensile stress in the circumferential direction. The outer ring of the steel plate can withstand the large centrifugal force of the rotor and It is possible to prevent the magnet pieces from scattering.   In addition, a permanent magnet rotor having through-holes near the connecting portion of the electromagnetic steel plate or its inner end According to the above, since the through hole is provided in the connecting portion, stress concentrates on the part where the through hole is provided. However, in combination with the small cross-sectional area of that part, it breaks more easily than other parts of the electrical steel sheet. It As a result, the centrifugal force of the permanent magnet piece for field is generated by the rotation of the permanent magnet rotor. When the value reaches the specified value, the electrical steel sheet is first broken at the through-hole part of the connection part. This prevents breakage of the outer peripheral ring portion of the electromagnetic steel sheet due to shearing force, Prevents the permanent magnet pieces for field from scattering.

[0007]   Further, according to the permanent magnet rotor in which the stress relaxation part is provided at the connecting part of the electromagnetic steel plates, A narrow stress relaxation part is provided at the joint, so centrifugal force is generated by rotating the permanent magnet rotor. When the force temporarily increases, the stress relaxation part expands and deforms, and the outer peripheral ring of the electromagnetic steel plate Relieves the shear stress of the part, which prevents the outer ring of the electromagnetic steel plate from breaking. it can.

[0008]

【Example】

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.   1 is an exploded view of a part of a permanent magnet rotor according to a first embodiment of the present invention. There is. The permanent magnet rotor 1 includes a yoke 2 and field permanent magnet pieces 3a, 3b, 3c, 3d. It consists of and. The yoke 2 is formed by integrally laminating a large number of electromagnetic steel plates 4. ing. Each electromagnetic steel plate 4 is made of a circular steel plate having an insulating coating on its surface. The shaped steel plate 4 has a rotary shaft opening 5 into which the rotary shaft is fitted and the rotary shaft opening 5 A caulking pin opening 14 is provided in the periphery, and field permanent magnet pieces 3a, 3b are provided in the vicinity of the outer periphery. , 3c, 3d are inserted to have fan-shaped openings 6 for magnet pieces. Magnet piece near the periphery Due to the provision of the opening 6 for the magnet, each electromagnetic steel plate 4 is separated from the outer periphery thereof and the opening 6 for the magnet piece. An outer peripheral ring portion 7 formed between and a steel plate body formed inside the magnet piece opening 6 It has a portion 8 and a connecting portion 9 that connects the outer peripheral ring portion 7 and the steel plate body portion 8. In the first embodiment, the electromagnetic steel plate 4 is formed at the center of the connecting portion 9 as shown in FIG. The inner steel plate 4 which is cut in the vicinity of the portion and is composed of the steel plate body 8 and a part of the connecting portion 9. a and an outer steel plate 4b formed of the outer peripheral ring portion 7 and a part of the connecting portion 9 are formed.

[0009]   In order to assemble this permanent magnet rotor 1, a large number of inner steel plates 4a are laminated to form a yoke. The body portion 2a is formed, and the outer side surfaces are alternately arranged on the outer periphery of the yoke body portion 2a as N poles. And the permanent magnet pieces 3a, 3b, 3c, 3d for the field are attached so as to show the magnetism of the S pole, Further, a plurality of outer steel plates 4b are fitted on the outer sides of the field magnet permanent magnet pieces 3a, 3b, 3c, 3d. Put on and assemble.

[0010]   Next, the operation of the permanent magnet rotor 1 based on the above structure will be described below with reference to FIG. explain.   FIG. 2 shows a cross section of the assembled permanent magnet rotor 1. Yoke body Field permanent magnet pieces 3a, 3b, 3c, 3d are attached to the outer circumference of 2a, and The yoke outer peripheral portion 2b is fitted. When the permanent magnet rotor 1 does not rotate, the yaw The connecting portion 9 of the electromagnetic steel plate 4 that constitutes the contact 2 is placed at the cutting portion p due to the preload at the time of assembly. Are pushing each other. When this permanent magnet rotor 1 rotates at high speed, The magnetic permanent magnet pieces 3a, 3b, 3c, 3d are rotated by the centrifugal force F as shown in the figure. Attempts to scatter radially outward of the trochanter. On the other hand, the yoke outer peripheral portion 2b is far The permanent magnet pieces 3a, 3b, 3c, 3d for field are held against the heart force F. Centrifugation When the force F is large, the yoke outer peripheral portion 2b is pulled outward in the radial direction of the permanent magnet rotor 1. By being stretched, the cut portions p of the connecting portions 9 of the electromagnetic steel plate 4 are separated from each other.   When the cut parts p of the connecting parts 9 of the electromagnetic steel plate 4 are separated from each other during high speed rotation Since the connecting portion 9 does not generate a tensile force inward in the radial direction against the centrifugal force F, the connecting portion 9 No shear stress is generated in the outer peripheral ring portion 7 near 9 All the forces are converted into circumferential tensile stress H of the outer peripheral ring portion 7. Generally electrical steel sheet The outer peripheral ring portion 7 of No. 4 has a large permissible range with respect to the tensile stress in the circumferential direction. Since the permissible range for radial shear stress is small, this permanent magnet rotor 1 has a large size. The permanent magnet pieces for field magnets 3a, 3b, 3c, It can hold 3d. That is, in the permanent magnet rotor 1 of the first embodiment, According to this, without increasing the width of the outer peripheral ring portion of the electromagnetic steel sheet, the permanent magnet piece for field magnet is used. It is possible to prevent the scattering accident.

[0011]   FIG. 3 is an exploded view of a part of a permanent magnet rotor according to a second embodiment of the present invention. It As shown in FIG. 3, in which the same parts as those in FIG. The permanent magnet rotor 1 is formed by cutting the outer end of the connecting portion 9 of the electromagnetic steel plate 4 to form an electromagnetic steel plate. The outer steel plate 4b of No. 4 is formed in a simple ring shape. Thus, the outer steel plate 4b Is formed into a simple ring shape so that the connecting portion 9 of the electromagnetic steel plate 4 is aligned during assembly. Assembling the permanent magnet rotor 1 is extremely easy because there is no need to combine them.   FIG. 4 shows a cross section of the permanent magnet rotor 1 according to the second embodiment in a direction orthogonal to the rotation axis. is doing. As is apparent from FIG. 4, the second embodiment also differs from the first embodiment. Similarly, when the permanent magnet rotor 1 rotates at high speed, the field permanent magnet pieces 3a, The centrifugal force F generated in 3b, 3c, 3d is the tensile stress H of the outer peripheral ring portion 7 of the electrical steel sheet 4. Therefore, the outer peripheral ring portion 7 has a large allowable stress against the centrifugal force F. It is possible to prevent the permanent magnet pieces for field from scattering.

[0012]   FIG. 5 is an exploded view of a part of a permanent magnet rotor according to a third embodiment of the present invention. It The permanent magnet rotor 1 according to this embodiment is provided near the inner end of the connecting portion 9 of the electromagnetic steel plate 4. It is cut in advance and divided into an inner steel plate 4a and an outer steel plate 4b. Of the connecting part 9 As shown in FIG. 5, the cut portion of the inner end engages with the inner steel plate 4a, It has a shape that can slide in any direction.   FIG. 6 shows a permanent magnet rotor 1 according to a third embodiment of the present invention in a direction orthogonal to the rotation axis. The cross section is shown. As is apparent from FIG. 6, the permanent magnet rotor according to the third embodiment. 1, the position of each permanent magnet piece 3a, 3b, 3c, 3d for field is accurately determined. Therefore, it is possible to prevent the rotation failure due to the displacement of the permanent magnet pieces. Further, since the inner end of the connecting portion 9 of the electromagnetic steel plate 4 can slide in the radial direction of the rotor, The inner end of the connecting portion 9 slides against a large centrifugal force F, and shear stress is applied to the outer peripheral ring portion 7. Does not occur. As a result, the permanent magnet rotor 1 of this third embodiment is Similarly to the permanent magnet rotor of the second embodiment, it has a large allowable stress with respect to the centrifugal force F. However, it is possible to prevent the permanent magnet pieces for field from scattering.

[0013]   FIG. 7 is an exploded view of a part of a permanent magnet rotor 1 according to a fourth embodiment of the present invention. There is. In the permanent magnet rotor 1 of the fourth embodiment, a through hole is formed in the connecting portion 9 of the electromagnetic steel plate 4. 10 is drilled. The yoke 2 is formed by laminating a large number of the electromagnetic steel plates 4. Permanent magnetism for field so that the outer side surface is alternately N pole and S pole in the second magnet piece opening 6. Stone pieces 3a, 3b, 3c, 3d are inserted.   FIG. 8 shows a cross section of the permanent magnet rotor 1 according to the fourth embodiment in a direction orthogonal to the rotation axis. is doing. As shown in FIG. 8, a permanent magnet for field is provided in the opening 6 for magnet piece of the electromagnetic steel plate 4. Pieces 3a, 3b, 3c, 3d are inserted and attached, and these permanent magnet pieces for field magnet 3a, Centrifuges 3b, 3c, and 3d radially outward by the high-speed rotation of the permanent magnet rotor 1. Receive force F. The electromagnetic steel plate 4 of the permanent magnet rotor 1 of the fourth embodiment is an outer ring. Since the portion 7 and the steel plate body 8 are connected by the connecting portion 9, the centrifugal force F causes As a result, tensile stress is generated in the connecting portion 9. The connecting portion 9 is provided with a through hole 10. Therefore, the stress is concentrated around the through hole 10 due to its shape, and Due to the small cross-sectional area of the side, a large tensile stress T is generated in this portion. Therefore , When the permanent magnet rotor 1 rotates at a speed equal to or higher than a predetermined speed, The portion where the through hole 10 is provided breaks before the other portion of the electromagnetic steel plate 4. Connecting part 9 After the fracture, the centrifugal force F is applied to the tensile stress in the circumferential direction of the outer peripheral ring portion 7 of the electromagnetic steel plate 4. It is transformed and has the strength to withstand the greater centrifugal force F. That is, this fourth implementation According to the example permanent magnet rotor 1, the outer peripheral ring portion 7 of the electromagnetic steel plate 4 is The connecting portion 9 is broken before it is broken, and as a result, the permanent magnet pieces for field magnets 3a, 3b, 3c are broken. , 3d can withstand a larger centrifugal force F without scattering.

[0014]   FIG. 9 shows another embodiment of the present invention in which the through hole 10 is provided near the inner end of the connecting portion 9. Is shown. In this embodiment, the through hole 10 is formed in the connecting portion 9 of the electromagnetic steel plate 4. By providing it in the vicinity of the end, it is possible to punch the steel plate body 8 having a relatively large area. And prevent processing failures such as deformation and twisting due to drilling in the narrow connecting part 9. can do.

[0015]   FIG. 10 is a partial exploded view of a permanent magnet rotor 1 according to a fifth embodiment of the present invention. There is. In the permanent magnet rotor 1 according to the fifth embodiment, the connecting portion 9 of the electromagnetic steel plate 4 is A narrow stress relaxation portion 11 is provided, and a plurality of electromagnetic steel plates 4 are laminated to form a yoke 2. Then, the field permanent magnet pieces 3a, 3b, 3c, 3d are inserted into the magnet piece openings 6 of the yoke 2. It is included.   FIG. 11 shows a cross section of the permanent magnet rotor 1 according to the fifth embodiment in a direction orthogonal to the rotation axis. Shows. As shown in FIG. 11, a permanent magnet for field is provided in the opening 6 for magnet piece of the electromagnetic steel plate 4. The magnet pieces 3a, 3b, 3c, 3d have magnetic poles of N pole and S pole alternately on the outer side surfaces. And the permanent magnet pieces 3a, 3b, 3c, 3d for field are permanently attached. Due to the high speed rotation of the magnet rotor 1, a centrifugal force F outward in the radial direction is received. This fifth In the electromagnetic steel plate 4 of the permanent magnet rotor 1 of the embodiment, the outer peripheral ring portion 7 and the steel plate body portion 8 are Since they are connected by the connecting portion 9, a tensile stress is applied to the connecting portion 9 by the centrifugal force F. Occurs. In the permanent magnet rotor 1 according to the present embodiment, the connecting portion 9 has a narrow stress relaxation portion 11. Is provided, the centrifugal force F causes the stress relaxation portion 11 to have a greater force than other portions. A large tensile stress T is generated. When the centrifugal force F increases temporarily, the connecting part The stress relaxation portion 11 of 9 is stretched and deformed by the tensile stress T which is temporarily increased, This centrifugal force F prevents the outer peripheral ring portion 7 of the electromagnetic steel plate 4 from breaking. This If the elongation deformation of the stress relaxation portion 11 is within the elastic range, the centrifugal force F becomes small. In addition, the connecting portion 9 can return to its original length again. In this way, this 5th real According to the permanent magnet rotor 1 of the example, the stress relaxation portion 11 of the connecting portion 9 of the electromagnetic steel plate 4 is used. The shearing stress of the outer peripheral ring portion 7 due to the centrifugal force F is relaxed, and The scattering of 3a, 3b, 3c and 3d is prevented.

[0016]   The permanent magnet rotor 1 of the first to fifth embodiments described above has good motor characteristics. For this reason, the width of the outer peripheral ring portion of the electromagnetic steel sheet is reduced. But electromagnetic steel sheet When the width of the outer ring of the The outer ring is thinner than the outer ring, and the permanent magnet piece for field magnet is the outer ring of the electromagnetic steel plate. May be exposed from the gap between the parts. On the other hand, on both ends of the laminated electromagnetic steel sheets Place the end plate with the projection that presses the outer ring of the electromagnetic steel plate, Therefore, the end plate and the electromagnetic steel plate can be fastened together.   FIG. 12 shows a permanent magnet rotor provided with the above end plate provided with a protrusion for pressing the outer peripheral ring portion. 2 shows a side cross section of FIG. In this permanent magnet rotor 1, a large number of electromagnetic steel plates 4 are laminated. A yoke 2 is formed, and a plurality of field permanent magnet pieces 3 are inserted and attached near the outer periphery of the yoke 2. is doing. End plates 12 are arranged on the upper and lower end surfaces of the yoke 2, and the end plates 12 and the electromagnetic steel The plate 4 is integrally fastened by caulking pins 13. There is an electric charge on the periphery of the end plate 12. Protrusions for pressing the outer peripheral ring portion 7 of the magnetic steel plate 4 are provided.   13 and 14 show the above end plate provided with a protrusion for pressing the outer peripheral ring portion. . In FIG. 13, the end plate 12 is made of a circular steel plate having a relatively high rigidity. A rotary shaft opening 5 is provided at the center of the rotary shaft, and caulking pins are provided at predetermined positions around the rotary shaft opening 5. It has an opening 14 for connection. This end plate 12 is a magnetic steel plate 4 over the entire circumference of the peripheral portion. It has a protrusion 12a for pressing the outer peripheral ring portion 7. The protrusion 12a of the end plate 12 is As shown in FIG. 14, only the outer peripheral ring portion outside the central portion of each field magnet permanent magnet piece It may be provided only on a part of the peripheral edge of the end plate 12 so as to press.   The protrusion 12 a of the end plate 12 presses the outer peripheral ring portion 7 of the electromagnetic steel plate 4. The outer peripheral ring portion 7 of the electromagnetic steel plate 4 is in close contact with each other, and the permanent magnet piece 3 for field is exposed. Never.

[0017]   Also, in any of the above permanent magnet rotors according to the present invention, the permanent magnet rotor Since the yoke of is formed by laminating a large number of electromagnetic steel plates insulated from each other, The eddy current induced during rotation of the permanent magnet rotor is small in proportion to the width of the electrical steel sheet. Therefore, the energy loss due to the eddy current is small.

[0018]

[Effect of device]   According to the present invention, when the permanent magnet rotor rotates at high speed, the outer peripheral phosphorus of the electromagnetic steel plate is The permanent magnet rotor is shaped to relieve the shear stress caused by the tensile force of the connecting part As a result, the outer ring of the electromagnetic steel plate can withstand the large centrifugal force of the rotor. It is possible to prevent the accidental scattering of the permanent magnet pieces for field by the high speed rotation of the permanent magnet rotor. You can stop.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view of a permanent magnet rotor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the permanent magnet rotor according to the first embodiment of the present invention in a direction orthogonal to the rotation axis.

FIG. 3 is an exploded perspective view of a part of a permanent magnet rotor according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a permanent magnet rotor according to a second embodiment of the present invention in a direction orthogonal to the rotation axis.

FIG. 5 is an exploded perspective view of a part of a permanent magnet rotor according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view of a permanent magnet rotor according to a third embodiment of the present invention in a direction orthogonal to the rotation axis.

FIG. 7 is a partially exploded perspective view of a permanent magnet rotor according to a fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view of a permanent magnet rotor according to a fourth embodiment of the present invention in a direction orthogonal to the rotation axis.

FIG. 9 is a cross-sectional view of a permanent magnet rotor according to another aspect of the fourth embodiment of the present invention, taken in a direction orthogonal to the rotation axis.

FIG. 10 is an exploded perspective view showing a part of a permanent magnet rotor according to a fifth embodiment of the present invention.

FIG. 11 is a cross-sectional view of a permanent magnet rotor according to a fifth embodiment of the present invention in a direction orthogonal to the rotation axis.

FIG. 12 is a side sectional view of a permanent magnet rotor according to the present invention including an end plate provided with a protrusion that presses an outer peripheral ring portion of an electromagnetic steel plate.

FIG. 13 is a perspective view of an end plate provided with a protrusion that presses the outer peripheral ring portion of the electromagnetic steel plate.

FIG. 14 is a perspective view of an end plate partially provided with a protrusion for pressing the outer peripheral ring portion of the electromagnetic steel plate.

FIG. 15 is an exploded perspective view of a part of a conventional permanent magnet rotor in which a field permanent magnet piece is press-fitted inside a yoke formed by stacking steel plates.

FIG. 16 is a cross-sectional view of a conventional permanent magnet rotor in which a field magnet permanent magnet piece is press-fitted into a yoke formed by stacking steel plates in a direction orthogonal to a rotation axis.

[Explanation of symbols]

1 Permanent magnet rotor 2 York 2a Yoke body 2b Outer part of yoke 3a Permanent magnet pieces for field 3b Permanent magnet piece for field 3c Permanent magnet piece for field 3d permanent magnet piece for field 4 electromagnetic steel sheet 5 Rotation shaft opening 6 Magnet opening 7 Outer ring part 8 Steel plate body 9 connection 10 through holes 11 Stress relaxation section

Claims (3)

[Scope of utility model registration request] 1. A plurality of openings for magnet pieces are provided in the vicinity of the outer periphery of a circular electromagnetic steel sheet, and the electromagnetic steel sheets are separated at the connecting portions of the steel sheets formed between the openings for adjacent magnet pieces or in the vicinity of their ends. An inner steel plate and an outer steel plate are formed, the inner steel plates are laminated to form a yoke main body, and a plurality of field permanent magnet pieces are attached to the outer periphery of the yoke main body. A permanent magnet rotor, wherein a plurality of the outer steel plates are fitted to the outer periphery of the yoke to form a yoke outer peripheral portion. 2. A plurality of openings for magnet pieces are provided in the vicinity of the outer circumference of a circular electromagnetic steel sheet, and a predetermined centrifugal force is applied to a connecting portion of the steel sheets formed between the openings for adjacent magnet pieces or in the vicinity of the inner end thereof by a predetermined centrifugal force. A permanent magnet rotation characterized by forming a through hole for breaking, laminating a large number of these electromagnetic steel sheets to form a yoke, and inserting a plurality of permanent magnet pieces for field into the opening for magnet pieces of this yoke. Child. 3. A predetermined centrifugal force is provided by providing a plurality of openings for magnet pieces in the vicinity of the outer periphery of a circular electromagnetic steel sheet, and providing a narrow portion at a connecting portion of the steel sheets formed between the openings for adjacent magnet pieces. To form a stress relaxation portion that undergoes elongation deformation, and a plurality of electromagnetic steel sheets having this stress relaxation portion are laminated to form a yoke, and a plurality of field permanent magnet pieces are inserted into the magnet piece openings of the yoke. A permanent magnet rotor characterized in that.