JP4415176B2 - Induction motor having a ring-shaped stator coil - Google Patents

Description

Detailed Description of the Invention

Detailed Description of the Invention

  The present invention relates to a single-phase induction motor such as a capacitor motor, a capacitor start motor, and a split phase start motor operated by a single-phase AC power source, and a three-phase induction motor operated by a three-phase AC power source. The present invention relates to a system and a stator core structure.

  Conventionally, as this type of electric motor, for example, when a three-phase induction motor is taken as an example, a structure as shown in FIG. 10 is generally adopted. FIG. 10 (a) is an axial half sectional side view, and a U / V / W phase coil 110 is provided on the stator core 120 as shown in FIG. 10 (b). After being wound, the terminal treatment such as connection between windings and lead wire connection is performed.

Problems to be solved by the invention

  In the conventional three-phase induction motor as described above, since the U / V / W-phase coils 110 are distributed in the circumferential direction and wound, the length of the coil end protruding from the axial end surface of the stator core 120 is long. There is a problem that the size h, the weight, the efficiency, and the cost reduction are difficult due to the increase in the length h and the increase in the winding amount and the copper loss. A single-phase induction motor also has the same problem because the main and auxiliary windings are distributed around the stator core in the circumferential direction.

  The present invention has been made to solve the above-mentioned problems, and since there is no coil end, it is small, light, and highly efficient. Further, it is an induction motor that is easy to process at the end of the winding and is low-cost. The purpose is to obtain winding method and stator core structure.

Means for solving the problem

In order to achieve the above-described object, an induction motor according to the present invention is formed by axially dividing a stator and winding a plurality of coils in a ring shape, and the center of the ring of each coil and the center of the rotating shaft substantially coincide. The stator cores that constitute the magnetic circuit are provided on the outer peripheral side and both axial end sides of each coil, and the magnetic pole teeth are arranged on the inner peripheral side in the circumferential direction of the rotating shaft with the coil interposed therebetween. They are alternately formed at positions shifted by π (rad) in electrical angle with each other, and each magnetic pole tooth part is provided with a magnetic pole piece, and a gap between the magnetic pole piece and the magnetic pole tooth part is formed between the magnetic pole piece and the magnetic pole tooth part. They are connected by a bridge portion formed of the same material, and are configured such that the magnetic pole teeth of each coil are shifted in the circumferential direction of the rotation axis by a predetermined angle and overlapped in the axial direction.

  Embodiments of an induction motor according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 FIG.
1 to 4 show an example in which the present invention is applied to a capacitor motor as a four-pole single-phase induction motor having two types of stator windings divided in the axial direction as Embodiment 1 of the induction motor according to the present invention. Show. FIG. 1 is a side view of a half cross-section in the axial direction. A phase / B phase coils 10 and 11 and lead wires 13 and a stator 20, a cage rotor 80, a rotating shaft 90, a bearing member 91, a bracket 92, It consists of a frame 93 and the like. In this embodiment, the A phase coil forms the main winding, and the B phase coil forms the auxiliary winding.

  The A-phase and B-phase coils 10 and 11 are divided in the axial direction of the rotary shaft 90 and wound so that the centers of the rings of the coils 10 and 11 and the centers of the rotary shafts 90 substantially coincide with each other. The insulation process is performed, and the lead wire 13 is connected to the single-phase AC power supply 15 together with the capacitor 14 as shown in FIG.

  The stator 20 includes coils 10 and 11, rear stator cores 21 and 22 on the outer peripheral side of the coils 10 and 11, and side surface stator cores 24 to 27 on both ends in the axial direction of the coils 10 and 11. The back stator core 21 and the side stator cores 24, 25 are magnetically connected to each other, and the magnetic pole teeth 30, provided with magnetic pole pieces 40, 41 on the inner peripheral side of the side stator cores 24, 25, respectively. 31 is formed. The B-phase stator core is configured in the same manner, and magnetic pole teeth 32 and 33 having magnetic pole pieces 42 and 43 are formed on the inner peripheral side.

  The cage rotor 80 includes a secondary conductor 81 that is short-circuited by a short-circuit ring at both ends in the axial direction, and includes magnetic pole teeth 30 to 33 and magnetic pole pieces 40 to 43 of the A-phase / B-phase coils 10 and 11. The rotary shaft 90 and the bearing member 91 are rotatably supported by a predetermined air gap.

  3 (a) to 3 (d) show the configurations of the side stator cores 24 to 27 and the convex magnetic pole tooth portions 30 to 33 formed on the inner peripheral side of the side stator cores 24 to 27, as shown in FIG. 3 is a view seen through from the load side (shaft end side), and other components are omitted in the figure. FIG. 3A is a side stator core 24 on the side opposite to the load of the A-phase coil 10, and the magnetic pole tooth portion 30 has its circumferential center aligned with the position of the match mark 36 at 12 o'clock. The watch is formed at two locations so as to be at the 6 o'clock position of the timepiece shifted by 2π (rad) in electrical angle. FIG. 3B shows the load-side side stator core 25 of the A-phase coil 10, and the magnetic pole tooth portion 31 has a center in the circumferential direction formed on the anti-load-side side stator core 24. It is formed at a position shifted by π (rad) in electrical angle with respect to the center of the tooth portion 30. As a result, the four-pole magnetic poles pass through the back stator core 21 (not shown), and the magnetic pole teeth 30 and the magnetic pole pieces 40 and the magnetic pole teeth 31 of the side stator cores 24 and 25 sandwich the A-phase coil 10. The pole pieces 41 are alternately formed in the circumferential direction on the inner circumferential side.

  FIG. 3C shows a side stator core 26 on the side opposite to the load side of the B-phase coil 11, and the pole tooth portion 32 has a center in the circumferential direction on the side stator core on the side opposite to the load side of the A-phase coil 10. The electrical angle is shifted by π / 2 (rad) with respect to the center of the magnetic pole tooth portion 30 formed at 24. FIG. 3D shows a load side side stator core 27 of the B-phase coil 11, and the magnetic pole tooth portion 33 has a magnetic center formed on the side stator core 26 on the side opposite to the load in the circumferential direction. It is formed at a position shifted by π (rad) in electrical angle with respect to the center of the tooth portion 32. As a result, the four-pole magnetic pole passes through the rear stator core 22 (not shown) at a position away from the magnetic pole teeth 30 and 31 of the A-phase coil 10 by an electrical angle of π / 2 (rad). The magnetic pole teeth 32 and the magnetic pole pieces 42 of the side stator cores 26 and 27 and the magnetic pole teeth 33 and the magnetic pole pieces 43 are alternately formed in the circumferential direction on the inner peripheral side with the coil 11 interposed therebetween.

  4 (a) to 4 (f) show the configuration of the side stator core, and FIGS. 4 (a) and 4 (c) show the side stator core 24 of the A-phase coil 10 (not shown). 25 is a view seen through the load side (shaft end side) from the non-load side in FIG. 1 in the same manner as described above, and FIG. 4B is a cross-sectional view along the line AA in FIG. ) Shows a cross section BB of FIG. A magnetic pole piece 40 having the same inner diameter as that of the magnetic pole tooth portion 30 is provided on the magnetic pole tooth portion 30 of the side stator core 24 on the side opposite to the load in the direction of the side stator core 25 on the load side. Is provided on the inner diameter side. A magnetic pole piece 41 having the same inner diameter as that of the magnetic pole tooth portion 31 is provided on the magnetic pole tooth portion 31 of the side stator core 25 on the load side in the direction opposite to the magnetic pole piece 40 and in the direction of the side stator core 24 on the antiload side. I have.

FIG. 4E shows a state in which the side stator cores 24 and 25 having the pole pieces 40 and 41 are assembled, and FIG. 4F shows a cross section CC of FIG. The pole piece 40 formed on the side stator core 24 is configured to be shorter than the axial end face of the side stator core 25 by a predetermined dimension a, and the pole piece 41 formed on the side stator core 25 is the same. In addition, it is configured to be shorter than the axial end surface of the side stator core 24 by a predetermined dimension a. Then, the magnetic pole tooth portion 30 and the magnetic pole piece 40 of the side stator core 24 and the magnetic pole tooth portion 31 and the magnetic pole piece 41 of the side stator iron core 25 that are adjacent poles in the circumferential direction form an inter-polar portion of width t. Has been.

FIG. 5 shows a case where the width t = 0 of the inter-pole portion of FIG. 4 (e) and the magnetic pole pieces adjacent to each other in the circumferential direction, the magnetic pole tooth portions, and the magnetic pole pieces are connected by a thin bridge portion.

Fig.5 (a) shows the state which assembled the side stator iron cores 24 and 25 of the U-phase coil 10 (illustration omitted) similarly to FIG.4 (e). The magnetic pole tooth portion 30 and the magnetic pole piece 40 of the side stator core 24 are opposed to the cage rotor 80 (not shown in the drawing) to the magnetic pole tooth portion 31 and the magnetic pole piece 41 of the side stator iron core 25 adjacent to each other in the circumferential direction. Are connected by a bridge portion E on the inner peripheral side. 5B is an enlarged view of the bridge portion E of FIG. 5A, and s indicates the thickness of the bridge portion E in the radial direction. FIG. 5C shows a cross-section CC of FIG. 5A, and the inner peripheral side facing the cage rotor 80 has a continuous cylindrical shape excluding the portion of the dimension a. The stator cores of other coils are similarly configured.

  The stator 20 maintains the above-described positional relationship between the A-phase and B-phase coils 10 and 11, the outer-side back stator cores 21 and 22 and the side stator cores 24-27 of each coil. However, it is configured to overlap in the axial direction.

  In this embodiment, for example, the magnetic flux generated by the A-phase coil 10 is generated from the outer peripheral side rear stator core 21 → side stator core 24 → magnetic pole tooth portion 30 and magnetic pole piece 40 → predetermined air gap → A magnetic path surrounding the cage rotor 80 → predetermined air gap → magnetic pole tooth portion 31 and magnetic pole piece 41 → side stator core 25 → back stator core 21 is formed, and is linked to the ring-shaped coil 10 to be connected to the axis. The change in the magnetic flux generated in the direction can be changed to the change in the magnetic flux in the rotation direction. The magnetic flux generated by the B-phase coil 11 can be caused to act in the same manner, and the magnetic pole tooth portion 32 is moved in the circumferential direction by an electrical angle of π / 2 (corresponding to the phase difference caused by the capacitor 14 connected to the power source. rad), the coils 10 and 11 generate a two-phase rotating (moving) magnetic field around the rotating shaft 90, and the current flowing in the secondary conductor 81 due to electromagnetic induction acts on the rotating magnetic field to generate torque. And the cage rotor 80 can be driven to rotate. Further, by changing the connection position of the capacitor 14 or the like, the rotating shaft 90 can be rotated in reverse as in the conventional capacitor motor.

According to the configuration as described above, since there is no portion corresponding to the coil end, it is possible to reduce the copper loss by reducing the amount of copper wire used in the coil, improving the efficiency of the single-phase induction motor and reducing the cost. And small size and light weight can be realized. Further, since the number of coils in each phase is at least one each, the coil winding work and terminal processing can be greatly simplified, which can contribute to the improvement of productivity. Furthermore, the occurrence of vibration and noise can be suppressed by improving the rigidity of the pole piece by the bridge portion between the poles.

Embodiment 2. FIG.
6 to 8 show an example in which the induction motor according to Embodiment 2 of the present invention is applied to a four-pole three-phase induction motor having three types of stator windings divided in the axial direction. FIG. 6 is a side view of a half cross section in the axial direction, and U, V, and W phase coils 10 to 12 and lead wires 13, a stator 20, a cage rotor 80, a rotating shaft 90, a bearing member 91, and a bracket 92. , Frame 93 and the like.

  The coils 10 to 12 of the U, V, and W phases are divided in the axial direction of the rotating shaft 90, so that the center of the ring of each coil 10 to 12 and the center of the rotating shaft 90 substantially coincide with each other. On the other hand, it is wound in the same direction. Each coil is appropriately insulated and connected in a Y shape, and then connected to a three-phase AC power supply 16 by a lead wire 13 as shown in FIG.

  The stator 20 is composed of coils 10 to 12, rear stator cores 21 to 23 on the outer peripheral side thereof, and side surface stator cores 24 to 29 on both axial sides of the coils 10 to 12. The phase back stator core 21 and the side stator cores 24 and 25 are magnetically connected to each other, and magnetic pole teeth provided with pole pieces 40 and 41 on the inner peripheral side of the side stator cores 24 and 25, respectively. Portions 30 and 31 are formed respectively. The V / W-phase stator cores are also configured in the same manner, and magnetic pole teeth 32 to 35 having magnetic pole pieces 42 to 45 are formed on the inner peripheral side.

  The cage rotor 80 includes a secondary conductor 81 that is short-circuited by a short-circuit ring at both ends in the axial direction, and includes magnetic pole tooth portions 30 to 35 of the respective U, V, and W phase coils 10 to 12, and magnetic pole pieces 40 to 40. 45 and a predetermined air gap, and are rotatably supported by a rotating shaft 90 and a bearing member 91.

  8 (a) to 8 (f) are diagrams showing the configuration of the side stator cores 24 to 29, the convex magnetic pole tooth portions 30 to 35 formed on the inner peripheral side thereof, and the magnetic pole pieces 40 to 45, respectively. 6 is a view seen through from the opposite load side to the load side (shaft end side), and other components are omitted in the drawing. FIG. 8A shows the side stator core 24 on the opposite side of the U-phase coil 10 and the magnetic pole tooth portion 30 has its circumferential center aligned with the position of the match mark 36 at 12:00 on the watch, It is formed in two places so as to be at the 6 o'clock position of the timepiece shifted by 2π (rad) in electrical angle. FIG. 8B is a side stator core 25 on the load side of the U-phase coil 10, and the magnetic pole tooth portion 31 has a magnetic pole formed at the center in the circumferential direction on the side stator core 24 on the anti-load side. It is formed at a position shifted by π (rad) in electrical angle with respect to the center of the tooth portion 30. As a result, the four-pole magnetic poles pass through the rear stator core 21 (not shown), and the magnetic pole teeth 30 and the magnetic pole pieces 40 and the magnetic pole teeth 31 and 31 of the side stator iron cores 24 and 25 sandwich the U-phase coil 10. The pieces 41 are alternately formed in the circumferential direction on the inner circumferential side.

  FIG. 8C shows the side stator core 26 on the side opposite to the load side of the V-phase coil 11, and the pole tooth portion 32 is centered in the circumferential direction on the side stator core on the side opposite to the load side of the U-phase coil 10. The electrical angle is shifted by 2π / 3 (rad) with respect to the center of the magnetic pole tooth portion 30 formed at 24. FIG. 8D is a side stator core 27 on the load side of the V-phase coil 11, and the magnetic pole tooth portion 33 has a center in the circumferential direction formed on the side stator core 26 on the anti-load side. It is formed at a position shifted by π (rad) in electrical angle with respect to the center of the tooth portion 32. As a result, as in the case of the U-phase coil 10, the four-pole magnetic pole passes through the back stator core 22 (not shown), and the magnetic pole teeth 32 of the side stator cores 26 and 27 sandwich the V-phase coil 11. The magnetic pole pieces 42, the magnetic pole tooth portions 33 and the magnetic pole pieces 43 are alternately formed in the circumferential direction on the inner peripheral side.

  FIG. 8E shows a side stator core 28 on the side opposite to the load side of the W-phase coil 12, and the pole tooth portion 34 is centered in the circumferential direction on the side stator core on the side opposite to the load side of the U-phase coil 10. The electrical angle is shifted by 4π / 3 (rad) with respect to the center of the magnetic pole tooth portion 30 formed at 24. FIG. 8 (f) is a load side side stator core 29 of the W-phase coil 12, and the magnetic pole tooth portion 35 has a circumferential center formed on the antiload side side stator core 28. It is formed at a position shifted by π (rad) in electrical angle with respect to the center of the tooth portion 34. As a result, as in the case of the U / V phase, the 4-pole magnetic pole passes through the back stator core 23 (not shown), and the magnetic pole teeth 34 of the side stator cores 28 and 29 sandwich the W-phase coil 12. The magnetic pole pieces 44, the magnetic pole tooth portions 35, and the magnetic pole pieces 45 are alternately formed in the circumferential direction on the inner peripheral side.

The magnetic pole tooth portion 30 and the magnetic pole piece 40 of the side stator core 24 of the U-phase coil 10 are side surfaces that are adjacent to each other in the circumferential direction as in FIGS. 4 (a) to 4 (f) of the first embodiment. The magnetic pole tooth portion 31 and the magnetic pole piece 41 of the stator core 25 form an inter-electrode portion with a width t. As in FIG. 5 of the first embodiment, the inter-electrode portion width t = 0 and a thin bridge portion. It is connected with. The stator cores of other coils are similarly configured.

  The stator 20 has the above-described positional relationship between the U, V, and W phase coils 10 to 12, the outer side rear stator cores 21 to 23, and the side stator cores 24 to 29 of the coils. It is configured to be superposed in the axial direction while maintaining.

  In this embodiment, for example, the magnetic flux generated by the U-phase coil 10 is generated from the outer side rear stator core 21 → side stator core 24 → magnetic pole tooth portion 30 and magnetic pole piece 40 → predetermined air gap → A magnetic path surrounding the cage rotor 80 → predetermined air gap → magnetic pole tooth portion 31 and magnetic pole piece 41 → side stator core 25 → back stator core 21 is formed, and is linked to the ring-shaped coil 10 to be connected to the axis. The change in the magnetic flux generated in the direction can be changed to the change in the magnetic flux in the rotation direction. The magnetic flux generated by the V / W phase coils 11 and 12 can be similarly actuated, and the magnetic pole teeth 32 and 34 are shifted by 2π / 3 (rad) in electrical direction in the circumferential direction corresponding to the phase difference of the power source. Therefore, by supplying a three-phase AC power source to the coils 10 to 12, a three-phase rotating magnetic field around the rotating shaft 90 is generated, and the current flowing in the secondary conductor 81 due to the electromagnetic induction action becomes a rotating magnetic field. Acting to generate torque, the cage rotor 80 can be driven to rotate. Furthermore, as with conventional three-phase induction motors, the phase rotation order is reversed by replacing any two of the U, V, and W phase coils with the power supply and making reverse connections. The direction of the torque acting on the cage rotor 80 is reversed, and the rotating shaft 90 can be rotated in the reverse direction. In addition, when the winding directions of the coils 10 to 12 are not the same, the magnetic pole teeth can be similarly actuated by, for example, shifting the magnetic pole teeth by π (rad) by an electrical angle in the circumferential direction of the rotating shaft.

According to the configuration as described above, since there is no portion corresponding to the coil end, it is possible to reduce the copper loss by reducing the amount of copper wire used in the coil, improve the efficiency of the three-phase induction motor, and reduce the cost. And small size and light weight can be realized. Further, since the number of phases of the coils requires only one each minimum, can contribute the windings of the coil working and terminal treatment greatly can simplified improvement of productivity, further, side stator Dimensional accuracy on the inner circumference side of the iron core and pole piece can be improved, and by optimizing the dimensions and shape of the bridge part, the rigidity of the pole piece is improved while suppressing a decrease in gap magnetic flux density due to leakage flux Therefore, the generation of vibration and noise can be reduced.

Embodiment 3 FIG.
FIG. 9 shows Embodiment 3 of the induction motor according to the present invention. In the third embodiment, as a means for realizing the configuration of the above-described embodiment, a part of the stator core is laminated and integrated using a plate-like magnetic member.

  9 shows the side stator cores 24 and 25 of the coil 10 (omitted in the drawing) from the anti-load side to the load side (shaft end side) in FIG. 1 or FIG. 6 as in the first or second embodiment. The figure seen through is shown. A magnetic pole tooth portion 30 is formed on the side stator core 24 of FIG. 9A, and a magnetic pole piece 41 is adjacent to the magnetic pole tooth portion 30 on the side stator core 24 of FIG. They are connected by the part E and formed integrally. Similarly, in the side stator core 25 of FIG. 9 (d), the pole piece 40 adjacent to the magnetic pole tooth portion 31 is integrally connected by the bridge portion E, and the side stator of FIG. 9 (e) is formed. A magnetic pole tooth portion 31 is formed on the iron core 25. In FIG. 9C, the pole piece 40 and the pole piece 41 are integrally formed by being connected by the bridge portion E, and are supported so as to be sandwiched between the side stator cores 24 and 25. .

  Each of the parts shown in FIGS. 9A to 9E is obtained by manufacturing a plate-like magnetic member by pressing, and simultaneously laminating and fixing the required number of pieces by means of a squeeze 47. It can also be fixed by caulking pins, screwing, welding or the like. The stator cores of the other coils have the same structure, and after applying appropriate insulation treatment and winding the coils of each phase, they are shrink-fitted into the cylindrical back stator core 21 and the like and press-fitted. is there. Note that the back stator core 21 and the like can also be configured by being laminated and integrated using a plate-like magnetic member.

  According to the manufacturing method as described above, since a highly accurate stator core can be easily manufactured at low cost, the characteristics and productivity of the induction motor can be improved, and the cost can be reduced. In addition to the above-described manufacturing method, a stator core can be manufactured using a dust core.

Although the first to third embodiments are applied to the present invention when the number of poles of the single-phase / three-phase induction motor is four, the induction motor according to the present invention has a different number of poles. Also effective. The induction motor according to the present invention can easily obtain an electric motor having the optimum number of poles without being influenced by the inner diameter dimension of the stator, the number of slots, and the like, unlike the conventional induction motor. In addition, the induction motor according to the present invention is suitable for a built-in type because the coil portion is not exposed, and furthermore, since each coil is wound independently, varnish processing or the like is not required in low-voltage models. It can be easily insulated even in high-voltage models and can be easily separated and reused when discarded. Furthermore, the induction motor according to the present invention can be operated at a variable speed by an inverter drive or the like as in the case of a conventional induction motor.

The invention's effect

As can be understood from the above description, according to the induction motor according to the present invention, the stator is axially divided and wound with a plurality of coils in a ring shape, and each coil is provided on the outer peripheral side and the axially opposite ends. A stator core that constitutes the magnetic circuit is provided, and on the inner circumference side, the magnetic pole tooth portion provided with the magnetic pole piece is shifted by a predetermined angle in the circumferential direction of the rotating shaft, and the poles are connected by a bridge portion and overlapped in the axial direction. By combining them together, there is no portion corresponding to the coil end, so the amount of copper wire used in the coil can be reduced and copper loss can be reduced, improving the efficiency of the induction motor and reducing costs. And small size and light weight can be realized. In addition, the dimensional accuracy and rigidity of the stator core can be improved, and vibration and noise can be reduced.

FIG. 3 is a side view of a half cross section in the axial direction of the single-phase induction motor in the first embodiment. FIG. 2 is a connection diagram of a single-phase induction motor in the first embodiment. It is the figure which looked at the structure of the magnetic pole tooth part of the side stator iron core in Embodiment 1 through the load side from the non-load side. The structure of the side stator core and the pole piece in the first embodiment is shown. The structure of the side stator core and the pole piece in the first embodiment and the second embodiment is shown. FIG. 5 is a side view of a half cross section in the axial direction of a three-phase induction motor in a second embodiment. FIG. 5 is a connection diagram of a three-phase induction motor in a second embodiment. It is the figure which saw through the structure of the magnetic pole tooth part of the side stator iron core in Embodiment 2 from the anti-load side to the load side. It is the figure which looked at the structure of the side stator iron core and pole piece in Embodiment 3 through the load side from the non-load side. The three-phase induction motor of a prior art example is shown, (a) is an axial direction half cross-sectional side view, (b) is a winding development view.

10-12 Stator coil, 13 Lead wire, 14 Capacitor, 15 Single-phase power supply, 16 Three-phase power supply, 20 Stator, 21-23 Rear stator core, 24-29 Side stator core, 30-35 Magnetic pole teeth , 36 Match mark, 40-45 pole piece, 47 Crushing position of scooping, 80 cage rotor, 81 secondary conductor, 90 rotating shaft, 91 bearing member, 92 bracket, 93 frame, 110 conventional coil, 120 conventional coil Stator core, a Predetermined gap / dimension, E bridge part, h coil end length, s bridge part radial thickness, t inter-pole width

Claims (1)

In an inner rotor type induction motor in which a stator having magnetic pole teeth facing each other through a predetermined air gap is disposed outside a rotor, the stator is divided into a plurality of rings in the form of rings divided in the axial direction. The stator cores that wrap the coils and are arranged so that the center of the ring of each coil and the center of the rotating shaft substantially coincide with each other, and that constitute the magnetic circuit on each of the outer peripheral side and the both axial ends of each coil. provided, wherein the inner peripheral side of the stator core, the magnetic pole teeth are formed alternately at positions displaced [pi (rad) in electrical angle in the circumferential direction of the rotary shaft across the coil, further wherein each The magnetic pole tooth portion includes a magnetic pole piece, and the poles formed by the magnetic pole piece and the magnetic pole tooth portion are connected by a bridge portion formed of the same material as the magnetic pole piece and the magnetic pole tooth portion, and each coil The magnetic pole tooth portion of the rotary shaft has a predetermined angle in the circumferential direction of the rotating shaft Rashi, the induction motor which is characterized by being configured as superimposed in the axial direction.

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