JP6169135B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor including a stator and a rotor.

  2. Description of the Related Art Conventionally, an electric motor including a stator around which a coil is wound and a rotor having a permanent magnet that is rotatably arranged inside the stator is known. In such an electric motor, a shaft is provided integrally with the rotor, and the shaft is rotated by rotating the rotor.

  Patent Document 1 describes an internal-magnet-type motor that includes a shaft that is inserted into the center of a rotor core that constitutes a rotor, and permanent magnets that are arranged at a plurality of locations surrounding the shaft in the rotor core. Yes. In this motor, two bridges are formed at each position where a permanent magnet is arranged in the rotor. Patent Document 2 describes a motor having a rotor including a permanent magnet and two shafts arranged with the rotor sandwiched in the axial direction of the rotating shaft. In this motor, the rotor and the two shafts are connected to each other in a separable manner in the axial direction of the rotating shaft by a connecting member such as a bolt.

Japanese Patent Laid-Open No. 10-174323 Japanese Patent Laid-Open No. 10-32946

  However, in the technique of Patent Document 1, since permanent magnets are arranged at a plurality of locations on the rotor core, the number of bridges in the rotor increases, and magnetic flux leakage may increase. Moreover, in the technique of patent document 2, since the number of parts increases, an assembly precision may fall.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the electric motor which can suppress the leakage of magnetic flux and can suppress the fall of an assembly precision.

  In order to solve the above-described problems and achieve the object, the present invention provides a stator having a coil, a rotor core rotatably provided inside the stator, and a rotor core along a rotation center axis of the rotor core. And a rotor having a penetrating shaft, the rotor having a magnet arrangement portion straddling between the rotor core and the shaft, and the permanent magnet is arranged in the magnet arrangement portion.

  According to the present invention, it is possible to suppress the leakage of magnetic flux and to suppress the decrease in assembly accuracy.

Sectional drawing which shows the electric motor which concerns on Embodiment 1. FIG. The figure which shows the rotor iron core which concerns on Embodiment 1. FIG. The figure which shows the rotor iron core which concerns on Embodiment 1. FIG. The figure which shows the shaft which concerns on Embodiment 1. The figure which shows the shaft which concerns on Embodiment 1. The figure which shows the rotor iron core and shaft which concern on Embodiment 1. FIG. The figure which shows the rotor iron core and shaft which concern on Embodiment 1. FIG. The figure which shows the rotor which concerns on Embodiment 1. FIG. The figure which shows the rotor which concerns on Embodiment 1. FIG. Sectional drawing which shows the electric motor which concerns on Embodiment 2. FIG. The figure which shows the shaft which concerns on Embodiment 2. The figure which shows the shaft which concerns on Embodiment 2. The figure which shows the shaft which concerns on Embodiment 2. The figure which shows the rotor core which concerns on Embodiment 2. FIG. The figure which shows the rotor core which concerns on Embodiment 2. FIG. The figure which shows the rotor core which concerns on Embodiment 2. FIG. The figure which shows the rotor core and shaft which concern on Embodiment 2. FIG. The figure which shows the rotor core and shaft which concern on Embodiment 2. FIG. The figure which shows the rotor which concerns on Embodiment 2. FIG. The figure which shows the rotor which concerns on Embodiment 2. FIG. The figure which shows the other structure of the rotor which concerns on Embodiment 2. FIG. Sectional drawing which shows the electric motor which concerns on Embodiment 3. The figure which shows the structure of the permanent magnet which concerns on a modification The figure which shows the structure of the permanent magnet which concerns on a modification

  Below, the electric motor which concerns on embodiment of this invention is demonstrated in detail based on drawing. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
1 is a cross-sectional view showing an electric motor 1 according to Embodiment 1. FIG. As shown in FIG. 1, the electric motor 1 includes a stator 10 and a rotor 20.

  The stator 10 includes a stator iron core 11 and a coil 12 wound around a tooth 11 a of the stator iron core 11. The stator core 11 has a plurality of electromagnetic steel plates stacked in a first direction D1, which is the axial direction of the central axis AX. The electromagnetic steel plates are fixed by caulking, welding, or welding.

  The teeth 11a protrude from the outer peripheral portion of the stator 10 toward the center. Two teeth 11a are provided in the circumferential direction. The two teeth 11a are arranged every 180 ° in the direction around the central axis AX. Therefore, one set of two teeth 11a arranged in point symmetry with respect to the central axis AX is formed in the stator 10. An insulating resin or insulating paper, which is an insulating material, is disposed on the teeth 11a by integral molding or fitting. The coil 12 is wound on an insulating material for each tooth 11a.

  The rotor 20 includes a rotor core 21 that is rotatably disposed inside the stator 10, a shaft 22 that rotates integrally with the rotor core 21, and a permanent magnet 24 that is inserted into the rotor core 21 and the rotor 22. ing. 2 and 3 are diagrams showing the rotor core 21 according to the first embodiment. FIG. 2 shows the shape of the rotor core 21 as viewed from the first direction D1. FIG. 3 shows a shape along the section AA in FIG. As shown in FIGS. 2 and 3, the rotor core 21 is provided to be rotatable around the axis of the central axis. The central axis of the rotor core 21 is disposed at a position that coincides with the central axis AX of the stator core 11. Therefore, the stator iron core 11 and the rotor iron core 21 have a common center axis AX. Hereinafter, even when the central axis of the rotor iron core 21 is described, the central axis AX is used.

  The rotor iron core 21 has a plurality of electromagnetic steel plates stacked in a first direction D1, which is the first direction D1. The rotor core 21 has a shaft insertion hole 21a along the center axis AX. The shaft insertion hole 21a is formed through the rotor core 21 in the first direction D1.

  The rotor core 21 has a magnet arrangement hole 21b. A part of the permanent magnet 24 is arranged in the magnet arrangement hole 21b. The magnet arrangement hole 21b is formed through the rotor iron core 21 in the first direction D1. Further, when one end surface 21c in the first direction D1 of the rotor core 21 is viewed from the first direction D1, the magnet arrangement hole 21b has a part of the shaft insertion hole 21a protruding outward in the radial direction of the rotor core 21. Is formed. In this case, the magnet arrangement hole 21b is linearly formed in the second direction D2 that is the protruding direction. Further, in the magnet arrangement hole 21 b, the dimension w <b> 1 in the third direction D <b> 3 that is the width direction orthogonal to the second direction D <b> 2 is set according to the thickness of the permanent magnet 24.

  A bridge portion 21d is formed between the circumferential portion of the end surface 21c and both ends of the magnet arrangement hole 21b in the second direction D2. The bridge portion 21d is subjected to centrifugal force stress when the rotor core 21 rotates. Therefore, the dimension of the bridge portion 21d in the radial direction of the rotor core 21 is set to a dimension that is not damaged by the stress.

  4 and 5 are diagrams showing the shaft 22 according to the first embodiment. FIG. 4 shows the shape of the shaft 22 viewed from the first direction D1. FIG. 5 shows a shape along the section BB in FIG. As shown in FIGS. 4 and 5, the shaft 22 is formed in a cylindrical shape using a magnetic material and is inserted into the shaft insertion hole 21 a of the rotor iron core 21. The shaft 22 and the rotor iron core 21 are fixed by shrink fitting, press fitting, or adhesion. In the shaft 22, one end surface 22 a in the first direction D <b> 1 is flush with the end surface 21 c of the rotor core 21.

  A magnet arrangement groove 22 b is formed on the end surface 22 a of the shaft 22. The magnet arrangement groove 22b is formed through the shaft 22 in the radial direction. The magnet arrangement groove 22b is formed linearly. The dimension w2 in the width direction perpendicular to the longitudinal direction of the magnet arrangement groove 22b is set according to the thickness of the permanent magnet 24, and is equal to the dimension w1 in the width direction of the magnet arrangement hole 21b. The dimension of the magnet arrangement groove 22b in the first direction D1 is equal to the dimension of the rotor core 21 in the first direction D1.

  6 and 7 are views showing the rotor iron core 21 and the shaft 22 according to the first embodiment. FIG. 6 shows a shape of the rotor iron core 21 to which the shaft 22 is mounted as viewed from the first direction D1. FIG. 7 shows a shape along the CC cross section in FIG. As shown in FIGS. 6 and 7, the rotor core 21 and the shaft 22 are arranged in a state where the magnet arrangement hole 21 b and the magnet arrangement groove 22 b are aligned on a straight line. In this case, the magnet arrangement hole 21b and the magnet arrangement groove 22b communicate with each other. A magnet arrangement portion 23 is formed by the magnet arrangement hole 21b and the magnet arrangement groove 22b in such a state of communication. The magnet arrangement part 23 is formed between the rotor core 21 and the shaft 22. The magnet arrangement part 23 is formed linearly in the second direction D2 when viewed in the first direction D1. The magnet arrangement part 23 is arranged at the center of the rotor core 21 and the shaft 22 in the second direction D2 and the third direction D3. In addition, the magnet arrangement | positioning part 23 may be arrange | positioned in the position shifted | deviated from the center of the rotor iron core 21 and the shaft 22 in the 2nd direction D2 or the 3rd direction D3.

  8 and 9 are diagrams showing the rotor 20 according to the first embodiment. FIG. 8 shows the shape of the rotor 20 viewed from the first direction D1. FIG. 9 shows a shape along the section DD in FIG. As shown in FIGS. 8 and 9, one permanent magnet 24 is arranged in the magnet arrangement portion 23. The permanent magnet 24 is formed in a rectangular plate shape. Among the permanent magnets 24, the first surface 24a side is an N pole, and the second surface 24b side is an S pole.

  The permanent magnet 24 is formed in a size that can be accommodated without being press-fitted into the magnet arrangement portion 23. When a gap is formed between the permanent magnet 24 and the magnet arrangement hole 21b or the magnet arrangement groove 22b in order to suppress displacement or backlash of the permanent magnet 24, a resin may be poured into the gap. Moreover, the structure which arrange | positions an elastic member in the magnet arrangement | positioning part 23, and hold | maintains the permanent magnet 24 with the elastic force of an elastic member may be sufficient. The dimension of the permanent magnet 24 in the first direction D1 is equal to the dimension of the magnet arrangement hole 21b and the magnet arrangement groove 22b in the first direction D1. Thereby, the end surface 24c of the permanent magnet 24 in the first direction D1 is flush with the end surface 21c of the rotor core 21 and the end surface 22a of the shaft 22 in a state where the permanent magnet 24 is disposed in the magnet arrangement portion 23.

  As the permanent magnet 24, a neodymium magnet manufactured by sintering, hot pressing or hot extrusion is used. The permanent magnet 24 may be a ferrite sintered magnet or a bonded magnet. When a bonded magnet is used for the permanent magnet 24, it may be integrally formed in the magnet arrangement hole 21b and the magnet arrangement groove 22b. In this case, the permanent magnet 24 can be arranged in the magnet arrangement hole 21b and the magnet arrangement groove 22b without any gap.

  Both ends of the permanent magnet 24 in the second direction D2 are accommodated in the magnet arrangement hole 21b. Moreover, the center part of the 2nd direction D2 among the permanent magnets 24 is accommodated in the magnet arrangement | positioning groove | channel 22b. Thus, the permanent magnet 24 is disposed between the rotor core 21 and the shaft 22. By disposing the permanent magnet 24, the two-pole rotor 20 is configured. Thus, by setting the number of poles to two, controllability during high-speed rotation can be stabilized, and iron loss can be reduced.

  In the electric motor 1 described above, when the rotor 20 is manufactured, first, in a state where the magnet arrangement hole 21b formed in the rotor iron core 21 and the magnet arrangement groove 22b formed in the shaft 22 communicate with each other in the second direction D2, The rotor core 21 and the shaft 22 are joined. By this joining, a magnet arrangement portion 23 is formed by the magnet arrangement hole 21b and the magnet arrangement groove 22b. Next, the permanent magnet 24 is arranged in the magnet arrangement part 23. In this case, the permanent magnet 24 is inserted in the first direction D1 with respect to the magnet arrangement portion 23. If a gap is formed between the rotor core 21 and the shaft 22 and the permanent magnet 24 after the permanent magnet 24 is inserted into the magnet arrangement portion 23, resin may be poured into the gap to fix the permanent magnet 24. .

  As described above, according to the first embodiment, since the place where the permanent magnet 24 is arranged is one place of the magnet arrangement portion 23, the number of the bridge portions 21d in the rotor core 21 can be suppressed to two. Thereby, leakage of the magnetic flux from the bridge part 21d can be suppressed. Moreover, since it is not necessary to divide the rotor iron core 21 and the shaft 22, the number of parts can be suppressed. Thereby, the fall of an assembly precision can be suppressed.

  In addition, according to the first embodiment, since the size of the bridge portion 21d is set to a size that does not break due to the centrifugal force stress during rotation, durability is ensured even if the bridge portion 21d is limited to two. It can be secured. Furthermore, since the shaft 22 is formed using a magnetic material, a part of the shaft 22 can be used as a magnetic path. Thereby, even if there is one permanent magnet 24, magnetic force can be secured.

Embodiment 2. FIG.
FIG. 10 is a sectional view showing the electric motor 2 according to the second embodiment. In the second embodiment, the same components as those of the electric motor 1 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified. As shown in FIG. 10, the electric motor 2 includes a stator 10 and a rotor 30. In the second embodiment, since the configuration of the rotor 30 is different from that of the first embodiment, the description will focus on the differences.

  As shown in FIG. 10, the rotor 30 includes a rotor core 31 that is rotatably arranged inside the stator 10, and a shaft 32 that rotates integrally with the rotor core 31. 11 to 13 are diagrams showing the shaft 32 according to the second embodiment. FIG. 11 shows the shape of the shaft 32 viewed from the first direction D1. FIG. 12 shows a shape along the section EE in FIG. FIG. 13 is a perspective view of the shaft 32.

  As shown in FIGS. 10 to 13, a step portion 32 c is formed on the end surface 32 a side of the shaft 32 in the first direction D <b> 1. In the first direction D1, the size of the stepped portion 32c is smaller than the size of the magnet arrangement groove 32b. That is, the step 32c is formed shallower than the magnet arrangement groove 32b in the first direction D1. Further, the step portion 32c is formed linearly along the second direction D2. In the third direction D3, the dimension of the stepped part 32c is larger than the dimension of the magnet arrangement groove 32b. That is, the step 32c is formed with a width wider than the magnet arrangement groove 32b in the third direction D3.

  By forming the stepped portion 32c, a protruding portion 35 protruding from the stepped portion 32c in the first direction D1 is formed on the end surface 32a side of the shaft 32. The protruding portion 35 is a receiving portion that receives centrifugal force acting on the rotor core 31 when the rotor 30 rotates. The protrusion part 35 is arrange | positioned in the position which pinches | interposes the magnet arrangement | positioning groove | channel 32b in the 3rd direction D3. The radially outer side of the shaft 32 of the protrusion 35 is formed in a cylindrical surface shape. Further, the radially inner side of the shaft 32 of the projecting portion 35 is formed in a planar shape.

  14 to 16 are views showing a rotor core 31 according to the second embodiment. FIG. 14 shows a shape of the rotor core 31 viewed from the first direction D1. FIG. 15 shows a shape along the section FF in FIG. FIG. 16 shows a shape along the section GG in FIG.

  As shown in FIGS. 14 to 16, the rotor core 31 is formed with an insertion hole 31 e into which the protruding portion 35 is inserted separately from the magnet arrangement hole 31 b. The insertion hole 31e is formed to have the same shape and size as the shape of the protruding portion 35 when viewed from the first direction D1. Further, the insertion hole 31e is disposed at a position overlapping the protrusion 35 in the third direction D3.

  A partition wall 31f is formed between the magnet arrangement hole 31b and the insertion hole 31e in the third direction D3 on the end surface 31c of the rotor core 31. The outer side of the rotor core 31 in the radial direction of the partition wall 31f is formed in a planar shape. In the first direction D1, the dimension of the partition wall 31f is smaller than the dimension of the rotor core 31.

  17 and 18 are views showing the rotor core 31 and the shaft 32 according to the second embodiment. FIG. 17 shows the shape of the rotor core 31 with the shaft 32 mounted as viewed from the first direction D1. FIG. 18 shows a shape along the section HH in FIG. As shown in FIGS. 17 and 18, the rotor core 31 and the shaft 32 are arranged in a state where the magnet arrangement holes 31b and the magnet arrangement grooves 32b are arranged in a straight line. In this case, the magnet arrangement hole 31b and the magnet arrangement groove 32b communicate with each other. The magnet arrangement portion 33 is formed by the magnet arrangement hole 31b and the magnet arrangement groove 32b in such a state of communication. The magnet arrangement portion 33 is formed between the rotor core 31 and the shaft 32.

  When the shaft 32 is inserted into the shaft insertion hole 31a of the rotor core 31, the protruding portion 35 is inserted into the insertion hole 31e. Since the protrusion 35 and the insertion hole 31e have the same shape and dimensions when viewed from the first direction D1, the protrusion 35 and the rotor core 31 inserted into the insertion hole 31e are orthogonal to the first direction D1. Engaged in the second direction D2, the third direction D3, and the direction around the center axis AX.

  When the rotor 30 rotates, centrifugal force acts on the rotor core 31. Due to this centrifugal force, stress acts on the bridge portion 31d. On the other hand, since the projecting portion 35 is provided on the shaft 32, a part of the centrifugal force acting on the rotor core 31 is received when the rotor 30 rotates. For this reason, the stress which arises in the bridge part 31d is reduced.

  Further, since the partition wall 31f is provided, the positioning in the first direction D1 is performed at a position where the step portion 32c of the shaft 32 contacts the partition wall 31f. In the first direction D1, the dimension of the protrusion 35 is equal to the dimension of the partition wall 31f. For this reason, the end surface 35 a in the first direction D <b> 1 of the projecting portion 35 is flush with the end surface 35 c of the rotor core 31.

  In the first direction D1, the dimension of the protrusion 35 may be the same as the dimension of the rotor core 31. In this case, the shaft insertion hole 31a is not provided, and the insertion hole 31e and the partition wall 31f are formed over the entire rotor core 31 in the first direction D1. Further, only the protruding portion 35 of the shaft 32 is inserted into the insertion hole 31 e of the rotor iron core 31.

  19 and 20 show the rotor 30 according to the second embodiment. FIG. 19 shows a shape of the rotor 30 viewed from the first direction D1. FIG. 20 shows a shape along the II cross section in FIG. As shown in FIGS. 19 and 20, the permanent magnet 24 is formed in a rectangular plate shape, and one permanent magnet 24 is arranged in the magnet arrangement portion 33. Among the permanent magnets 24, the first surface 24a side is an N pole, and the second surface 24b side is an S pole.

  As described above, according to the second embodiment, the place where the permanent magnet 24 is arranged is one place of the magnet arrangement portion 33 as in the first embodiment, and therefore the number of the bridge portions 31d in the rotor core 31 is the same. Can be reduced to two. Thereby, the leakage of the magnetic flux from the bridge part 31d can be suppressed. Moreover, since it is not necessary to divide the rotor iron core 31 and the shaft 32, the number of parts can be reduced. Thereby, the fall of an assembly precision can be suppressed.

  Further, according to the second embodiment, since the shaft 32 has the protruding portion 35 that receives the centrifugal force acting on the rotor core 31 when the rotor 30 rotates, the stress generated in the bridge portion 31d can be reduced. . Thereby, since it is not necessary to thicken the dimension of the bridge part 31d in the radial direction, leakage of magnetic flux can be suppressed.

  FIG. 21 is a cross-sectional view showing another configuration of the rotor 30 according to the second embodiment. As shown in FIG. 21, the rotor core 31 includes a plurality of electromagnetic steel plates 34 stacked in the first direction D1, and a fixing portion 36 that is disposed on the outer peripheral side of the insertion hole 31e and fixes the plurality of electromagnetic steel plates 34. . The fixing portion 36 is formed along the first direction D1. The fixing part 36 is a fixing structure by caulking, rivets, bolts or resin molding. Thereby, since the fixing | fixed part 36 can receive the centrifugal force in the radial direction outer side of the protrusion part 35, the stress which arises in the bridge | bridging part 31d can be reduced.

Embodiment 3 FIG.
FIG. 22 is a cross-sectional view showing electric motor 3 according to the third embodiment. In the third embodiment, the same components as those of the electric motor 1 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  As shown in FIG. 22, the electric motor 3 includes a stator 40 and a rotor 20. The configuration of the rotor 20 is the same as that in the first embodiment. Note that the rotor 30 according to the second embodiment may be used. The stator 40 includes a stator iron core 41 and a coil 42 wound around a tooth 41 a of the stator iron core 41. The stator iron core 41 has a plurality of electromagnetic steel plates stacked in a first direction D1, which is the axial direction of the central axis AX. The electromagnetic steel plates are fixed by caulking, welding, or welding.

  The teeth 41a protrude toward the center of the stator 40. Four teeth 41a are provided in the circumferential direction. The four teeth 41a are arranged every 90 ° in the direction around the central axis AX. Therefore, two sets of two teeth 11a are formed on the stator 40 so as to be symmetrical with respect to the central axis AX. An insulating resin or insulating paper, which is an insulating material, is disposed on the teeth 41a by integral molding or fitting.

  The coil 42 is wound on an insulating material for each tooth 41a. The coils 42 wound around the two tooth portions 41b arranged at point-symmetrical positions with respect to the central axis AX are connected in series. The two coils 42 connected in series have the same phase. The stator 40 according to the third embodiment has a two-phase structure having two sets of in-phase coils 42.

  As described above, the rotor 20 can also be applied to the two-phase electric motor 3. Therefore, in the electric motor 3 as well, since the place where the permanent magnet 24 is arranged is one place of the magnet arrangement part 23, the number of the bridge parts 21 d in the rotor core 21 can be suppressed to two. Thereby, leakage of the magnetic flux from the bridge part 21d can be suppressed. Moreover, since it is not necessary to divide the rotor iron core 21 and the shaft 22, the number of parts can be suppressed. Thereby, the fall of an assembly precision can be suppressed. Note that the rotor 20 according to the first embodiment or the rotor 30 according to the second embodiment can be similarly applied to a configuration having three or more sets of coils having the same phase, that is, a configuration having three or more phases. .

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part. In the above embodiment, the configuration in which the permanent magnet 24 is formed in a rectangular plate shape and the first surface 24a and the second surface 24b are formed in a planar shape has been described. However, the present invention is not limited to this.

  23 and 24 are diagrams showing a configuration of a permanent magnet 24 according to a modification. The rotor 20A shown in FIG. 23 is formed in a shape in which the first surface 24a and the second surface 24b are curved in a convex shape. With this configuration, the magnetic flux waveform can be made closer to a sine wave than when the first surface 24a and the second surface 24b are formed in a planar shape. Further, the rotor 20B shown in FIG. 24 is formed in a shape in which the first surface 24a and the second surface 24b are curved in a concave shape. With this configuration, the magnetic flux waveform can be made closer to a sine wave than when the first surface 24a and the second surface 24b are formed in a planar shape. Moreover, compared with the structure shown in FIG. 23, the demagnetization proof stress of the both ends of the 2nd direction D2 can be improved.

  D1 1st direction, D2 2nd direction, D3 3rd direction, AX center axis, w1, w2 dimensions, 1, 2, 3 Electric motor 10, 40 Stator, 11, 41 Stator core, 11a, 41a Teeth, 12, 42 Coil, 20, 30 rotor, 21, 31 rotor core, 21a, 31a shaft insertion hole, 21b, 31b magnet placement hole, 21c, 22a, 24c, 31c, 32a, 35a, 35c end face, 21d, 31d bridge part, 22, 32 Shaft, 22b, 32b Magnet arrangement groove, 23, 33 Magnet arrangement part, 24 Permanent magnet, 24a 1st surface, 24b 2nd surface, 31e Insertion hole, 31f Partition, 32c Stepped part, 34 Electrical steel plate, 35 Protruding part, 36 fixed part, 41b teeth part.

Claims (10)

A stator having a coil;
A rotor core rotatably provided inside the stator, and a rotor having a shaft passing through the rotor core along a central axis of rotation of the rotor core;
The rotor has a magnet arrangement part straddling between the rotor core and the shaft, and a permanent magnet is arranged in the magnet arrangement part. The magnet arrangement part has a magnet arrangement hole formed in the rotor core and a magnet arrangement groove formed in the shaft,
The electric motor according to claim 1, wherein the rotor iron core and the shaft are fixed in a state where the magnet arrangement hole and the magnet arrangement groove communicate with each other. The electric motor according to claim 2, wherein the magnet arrangement hole is formed by leaving both ends of the rotor core in a radial direction of the rotor core. The electric motor according to claim 2, wherein the magnet arrangement groove is formed to penetrate the shaft in a radial direction of the rotor. The electric motor according to any one of claims 1 to 4, wherein the magnet arrangement portion is formed at an end portion of the shaft in an axial direction of the central axis. The electric motor according to any one of claims 1 to 5, wherein the permanent magnet is disposed at a center in a radial direction of the rotor. The electric motor according to any one of claims 1 to 6, wherein the shaft includes a receiving portion that receives a centrifugal force that acts on the rotor iron core when the rotor rotates. The receiving portion has a protruding portion protruding in the axial direction of the central axis,
The rotor iron core has an insertion hole for inserting the protrusion,
The electric motor according to claim 7, wherein the rotor core and the protruding portion inserted into the insertion hole are arranged in a state of being engaged in a direction orthogonal to the central axis. The magnet arrangement portion has a magnet arrangement hole formed in the rotor core;
The electric motor according to claim 8, wherein a dimension of the insertion hole is smaller than a dimension of the magnet arrangement hole in an axial direction of the central axis. The rotor iron core includes a plurality of electromagnetic steel plates stacked in an axial direction of the central axis, and a fixing portion that is disposed on an outer peripheral side of the insertion hole and fixes the plurality of electromagnetic steel plates. 9. The electric motor according to 9.

Images