JP2021164262A - motor - Google Patents

Abstract

To provide a motor capable of reducing a cogging torque without providing a skew.SOLUTION: A motor comprises: a stator; and a pair of rotors 20 which rotates around a center shaft, and is laminated in a shaft direction. Each rotor 20 includes: an inner core part 24; a first outer core part 25; a second outer core part 26 arranged at a position different from that of the first outer core part 25 in a circumferential direction; a first magnet 27 arranged on an outer side of a radial direction from the first outer core part 25; and a second magnet 28 arranged between the inner core part 24 and the second outer core part 26 in the radial direction. A first magnetic pole part 51 structured by the first outer core part 25 and the first magnet 27, which are arranged in the radial direction, and a second magnetic pole part 52 structured by the second magnet 28 and the second outer core part 26 in the radial direction are alternately arranged in the circumferential direction. The first magnetic pole part 51 and the second magnetic pole part 52 of the pair of rotors 20 are arranged in parallel to the shaft direction, and both circumferential positions are the same.SELECTED DRAWING: Figure 3

Description

The present invention relates to a motor.

The motor includes a rotor and a stator. The motor can suppress vibration and noise by reducing the cogging torque. In the conventional motor, for example, as described in Patent Document 1, a step skew is provided in the rotor and the stator to reduce the cogging torque.

Japanese Unexamined Patent Publication No. 2004-159492

If the skew is provided, the manufacturing process of the motor is increased and the productivity is lowered.

One object of the present invention is to provide a motor capable of reducing cogging torque without providing skew.

One aspect of the motor of the present invention includes a tubular stator and a pair of rotors that are located radially inside the stator, rotate about a central axis, and are stacked in the axial direction. The rotor has an inner core portion, a first outer core portion located radially outside the inner core portion, and a first outer core portion located radially outside the inner core portion in the circumferential direction. A second outer core portion arranged at a position different from the above, a first magnet arranged radially outside the first outer core portion, and the inner core portion and the second outer core portion in the radial direction. It has a second magnet arranged between the two. In a cross-sectional view perpendicular to the central axis, the second magnet has a portion located radially outward as it is separated from the center in the circumferential direction of the second outer core portion and the center line passing through the central axis in the circumferential direction. Have. A first magnetic pole portion composed of the first outer core portion and the first magnet arranged in the radial direction, and a second magnetic pole portion composed of the second magnet and the second outer core portion arranged in the radial direction. And are arranged alternately in the circumferential direction. The first magnetic pole portion of one of the pair of rotors and the second magnetic pole portion of the other are arranged side by side in the axial direction and have the same circumferential position with each other.

According to the motor of one aspect of the present invention, the cogging torque can be reduced without providing skew.

FIG. 1 is a cross-sectional view schematically showing the motor of the present embodiment. FIG. 2 is a perspective view schematically showing a rotor of the motor of the present embodiment. FIG. 3 is a cross-sectional view showing a cross section of FIG. 1 III-III. FIG. 4 is a cross-sectional view showing an IV-IV cross section of FIG. FIG. 5 is a schematic view showing an electric power steering device including the motor of the present embodiment. FIG. 6 is a cross-sectional view showing a part of the rotor of the motor of the modified example of this embodiment. FIG. 7 is a cross-sectional view showing a part of the rotor of the motor of the modified example of the present embodiment.

The motor 10 according to the embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, in the present embodiment, the direction in which the central axis J of the motor 10 extends is simply referred to as the "axial direction". In this embodiment, the axial direction is the vertical direction. The upper side (+ Z) corresponds to one side in the axial direction, and the lower side (−Z) corresponds to the other side in the axial direction. Further, the radial direction centered on the central axis J is simply referred to as "diameter direction". Of the radial directions, the direction closer to the central axis J is called the radial inner side, and the direction away from the central axis J is called the radial outer side. Further, the circumferential direction centered on the central axis J is simply called "circumferential direction". In the present embodiment, as shown in FIGS. 3 and 4, the predetermined rotation direction in the circumferential direction when viewed from the axial direction is referred to as θ1 on one side of the circumferential direction, and the rotation direction opposite to the predetermined rotation direction is called. , Called θ2 on the other side in the circumferential direction. Specifically, in the top view of the rotor 20, the counterclockwise direction centered on the central axis J is called the one side θ1 in the circumferential direction, and the clockwise direction centered on the central axis J is called the other side θ2 in the circumferential direction. Called. The vertical direction, the upper side, and the lower side are names for simply explaining the relative positional relationship of each part, and the actual arrangement relationship, etc. is an arrangement relationship, etc. other than the arrangement relationship, etc. indicated by these names. You may.

As shown in FIG. 1, the motor 10 of the present embodiment includes a cylindrical stator 30 centered on a central axis J, a rotor 20 located radially inside the stator 30, a housing 11, and a plurality of bearings. 15 and 16 are provided. The motor 10 is an inner rotor type motor. The rotor 20 rotates about the central axis J with respect to the stator 30.

The housing 11 houses the rotor 20 and the stator 30. The housing 11 has a cylindrical shape extending in the axial direction. The housing 11 has a peripheral wall 11a, a top wall 11b, a bottom wall 11c, and a bearing holding wall portion 11d. The peripheral wall 11a has a cylindrical shape extending in the axial direction. The top wall 11b closes the opening on the upper side of the peripheral wall 11a. The bottom wall 11c closes the opening on the lower side of the peripheral wall 11a. The bottom wall 11c holds the bearing 16. The bearing holding wall portion 11d is fixed to the peripheral wall 11a. The bearing holding wall portion 11d holds the bearing 15.

A pair of rotors 20 are provided side by side in the axial direction. The pair of rotors 20 are stacked in the axial direction. As shown in FIGS. 1 and 2, the pair of rotors 20 have a first rotor 20A and a second rotor 20B arranged at a position different from that of the first rotor 20A in the axial direction. In the present embodiment, the first rotor 20A is located above the second rotor 20B, and the second rotor 20B is located below the first rotor 20A.

The rotor 20 includes a shaft 21, a rotor core 22, a plurality of magnets 23 located at the radial outer ends of the rotor core 22, and arranged side by side in the circumferential direction, a groove 29, and a holder 40. The rotor core 22 has an inner core portion 24, a first outer core portion 25, and a second outer core portion 26. The plurality of magnets 23 include a first magnet 27 and a second magnet 28. That is, the rotor 20 has an inner core portion 24, a first outer core portion 25, a second outer core portion 26, a first magnet 27, and a second magnet 28.

The shaft 21 is a columnar shape extending in the axial direction about the central axis J. The shaft 21 may have a cylindrical shape. The shaft 21 is rotatably supported around the central axis J by a plurality of bearings 15 and 16. The plurality of bearings 15 and 16 are arranged at intervals in the axial direction and are supported by the housing 11. That is, the shaft 21 is supported by the housing 11 via a plurality of bearings 15 and 16.

The rotor core 22 has a cylindrical shape extending in the axial direction. The rotor core 22 is made of a magnetic material (ferromagnetic material), and is made of, for example, iron, steel, stainless steel, or the like. The rotor core 22 is configured by laminating a plurality of electromagnetic steel sheets in the axial direction. The rotor core 22 has a larger outer diameter than the shaft 21. The rotor core 22 has a smaller axial length than the shaft 21. The inner peripheral surface of the rotor core 22 is fixed to the outer peripheral surface of the shaft 21. The rotor core 22 is fixed to the shaft 21 by press fitting, adhesion, or the like. The rotor core 22 is located between the pair of bearings 15 and 16 in the axial direction.

As shown in FIGS. 3 and 4, the inner core portion 24 constitutes a radial inner portion of the rotor core 22. The inner core portion 24 has a cylindrical shape extending in the axial direction about the central axis J. The inner core portion 24 has a shaft hole 24a and a lightening hole 24b. The shaft hole 24a is located on the central axis J and penetrates the inner core portion 24 in the axial direction. The shaft 21 is inserted into the shaft hole 24a. The lightening hole 24b penetrates the inner core portion 24 in the axial direction. A plurality of lightening holes 24b are provided at intervals in the circumferential direction. The plurality of lightening holes 24b are arranged at equal pitches in the circumferential direction. According to this embodiment, the weight of the rotor 20 can be reduced, the material cost can be reduced, and the like by providing the lightening hole 24b.

The first outer core portion 25 constitutes a part of the radial outer portion of the rotor core 22. The first outer core portion 25 is located radially outside the inner core portion 24. The first outer core portion 25 projects radially outward from the inner core portion 24 in a part in the circumferential direction. A plurality of first outer core portions 25 are provided at intervals in the circumferential direction. In the present embodiment, each rotor 20 is provided with four first outer core portions 25 at equal pitches in the circumferential direction.

The second outer core portion 26 constitutes a part of the radial outer portion of the rotor core 22. The second outer core portion 26 is located radially outside the inner core portion 24, and is arranged at a position different from that of the first outer core portion 25 in the circumferential direction. The second outer core portion 26 is arranged at a position radially outward from the inner core portion 24 in a part in the circumferential direction. A plurality of second outer core portions 26 are provided at intervals in the circumferential direction. In the present embodiment, each rotor 20 is provided with four second outer core portions 26 at equal pitches in the circumferential direction. In each rotor 20, the first outer core portion 25 and the second outer core portion 26 are alternately arranged in the circumferential direction.

At least one of the first outer core portion 25 and the second outer core portion 26 is integrated with the inner core portion 24. In the present embodiment, the first outer core portion 25 is integrated with the inner core portion 24. According to this embodiment, the number of parts of the rotor 20 can be reduced, and the manufacturing process and manufacturing cost of the motor 10 can be reduced. The configurations of the first outer core portion 25 and the second outer core portion 26 other than the above will be described separately later.

The magnet 23 is a permanent magnet. Each magnet 23 is fixed to the outer peripheral portion of the rotor core 22 by a holder 40, an adhesive or the like.

The first magnet 27 is arranged radially outside the first outer core portion 25. The first magnet 27 is arranged on the radial outer surface of the rotor 20 and is exposed to the radial outer surface. The first outer core portion 25 and the first magnet 27 overlap each other when viewed from the radial direction. The first magnetic pole portion 51 is formed by the first outer core portion 25 and the first magnet 27 arranged in the radial direction. That is, the rotor 20 has a first magnetic pole portion 51. The first magnetic pole portion 51 is a surface magnet type (SPM) magnetic pole portion. A plurality of first magnetic pole portions 51 are provided at intervals in the circumferential direction. In the present embodiment, each rotor 20 is provided with four first magnetic pole portions 51 at equal pitches in the circumferential direction.

The first magnet 27 has a plate shape, and a pair of plate surfaces face in the radial direction. The first magnet 27 has a radial outer surface 27a facing the radial outer side, a radial inner side surface 27b facing the radial inner side, and a first side surface 27c facing the circumferential direction. The radial outer surface 27a has a convex curved surface shape that bulges outward in the radial direction. The radial inner side surface 27b has a planar shape extending in a direction perpendicular to the radial direction. A pair of first side surfaces 27c are provided on the first magnet 27. Each first side surface 27c has a planar shape extending in a direction perpendicular to the circumferential direction. Each first side surface 27c is connected to a circumferential end of the radial outer surface 27a and a circumferential end of the radial inner side 27b. According to the present embodiment, by providing the first magnet 27 with a pair of first side surfaces 27c, it is possible to suppress the formation of sharp corners at both ends of the first magnet 27 in the circumferential direction, and the first magnet 27 The structure of the first magnet 27 can be simplified while suppressing the corner chipping.

As shown in FIGS. 3 and 4, the length of the first side surface 27c is 1 mm or more in a cross-sectional view perpendicular to the central axis J. When the length of the first side surface 27c is 1 mm or more, the corner chipping of the first magnet 27 is suppressed more stably.

The second magnet 28 is arranged between the inner core portion 24 and the second outer core portion 26 in the radial direction. The second magnet 28 and the second outer core portion 26 overlap each other when viewed in the radial direction. The second magnetic pole portion 52 is formed by the second magnet 28 and the second outer core portion 26 arranged in the radial direction. That is, the rotor 20 has a second magnetic pole portion 52. The second magnetic pole portion 52 is an embedded magnet type (Interior Permanent Magnet: IPM) magnetic pole portion. A plurality of second magnetic pole portions 52 are provided at intervals in the circumferential direction. In the present embodiment, each rotor 20 is provided with four second magnetic pole portions 52 at equal pitches in the circumferential direction.

The second magnet 28 has a plate shape, and a pair of plate surfaces face in the radial direction. The second magnet 28 has a radial outer surface 28a that faces the outer side in the radial direction, a radial inner side surface 28b that faces the inner side in the radial direction, and a second side surface 28c that faces the circumferential direction. A plurality of second side surfaces 28c are provided on the second magnet 28. Each second side surface 28c is connected to a circumferential end of the radial outer surface 28a and a circumferential end of the radial inner side surface 28b. The configuration of the second magnet 28 other than the above will be described later separately.

As shown in FIG. 2, the first magnetic pole portion 51 and the second magnetic pole portion 52 are alternately arranged in the circumferential direction. Of the pair of rotors 20, one first magnetic pole portion 51 and the other second magnetic pole portion 52 are arranged side by side in the axial direction and have the same circumferential position. That is, the circumferential position of the first magnetic pole portion 51 of the first rotor 20A and the circumferential position of the second magnetic pole portion 52 of the second rotor 20B are the same as each other, and the second magnetic pole portion 52 of the first rotor 20A The circumferential position of the second rotor 20B and the circumferential position of the first magnetic pole portion 51 of the second rotor 20B are the same as each other.

More specifically, when viewed from the axial direction, the central portion in the circumferential direction of the first magnetic pole portion 51 of the first rotor 20A and the central portion in the circumferential direction of the second magnetic pole portion 52 of the second rotor 20B overlap each other. The central portion in the circumferential direction of the second magnetic pole portion 52 of the first rotor 20A and the central portion in the circumferential direction of the first magnetic pole portion 51 of the second rotor 20B are arranged so as to overlap each other. That is, in this embodiment, the rotor 20 is not skewed. Further, in the present embodiment, when viewed from the axial direction, both ends of the first magnetic pole portion 51 of the first rotor 20A in the circumferential direction and both ends of the second magnetic pole portion 52 of the second rotor 20B in the circumferential direction are formed. Both ends of the second magnetic pole portion 52 of the first rotor 20A in the circumferential direction and both ends of the first magnetic pole portion 51 of the second rotor 20B in the circumferential direction are arranged so as to overlap each other. It should be noted that, when viewed from the axial direction, both ends of the first magnetic pole portion 51 of the first rotor 20A in the circumferential direction and both ends of the second magnetic pole portion 52 of the second rotor 20B in the circumferential direction overlap each other. Both ends of the second magnetic pole portion 52 of the first rotor 20A in the circumferential direction and both ends of the first magnetic pole portion 51 of the second rotor 20B in the circumferential direction do not have to be arranged so as to overlap each other. That is, the fact that the rotor 20 is not skewed means that the center of the first magnetic pole portion 51 of the first rotor 20A in the circumferential direction and the circumference of the second magnetic pole portion 52 of the second rotor 20B when viewed from the axial direction. The central part of the direction is arranged so as to overlap each other.

According to the present embodiment, among the pair of rotors 20, the waveform of the cogging torque generated in the first rotor 20A and the waveform of the cogging torque generated in the second rotor 20B can be generated in opposite phases to each other. .. That is, the cogging torque of the first rotor 20A and the cogging torque of the second rotor 20B cancel each other out, and the difference between the maximum value and the minimum value of the waveform of the combined cogging torque, that is, the fluctuation range can be suppressed to be small. Therefore, the cogging torque of the motor 10 as a whole can be reduced without providing skew. The manufacturing process of the motor 10 is reduced, and the productivity is improved. Moreover, the antiphase can be generated in the torque ripple. That is, since the torque ripple generated in the first rotor 20A and the torque ripple generated in the second rotor 20B are generated in opposite phases, they cancel each other out, and the maximum value and the minimum value of the combined torque ripple waveform are obtained. The difference between the two, that is, the fluctuation range, can be kept small. Therefore, according to the present embodiment, it is possible to reduce the cogging torque and reduce the torque ripple while suppressing the torque decrease due to the skewing. Then, the vibration and noise generated by the motor 10 can be reduced.

As shown in FIGS. 3 and 4, the second magnet 28 is separated from the center in the circumferential direction of the second outer core portion 26 and the center line C passing through the central axis J in the circumferential direction in a cross-sectional view perpendicular to the central axis J. Therefore, it has a portion located on the outer side in the radial direction. Specifically, the portion of the second magnet 28 on one side θ1 in the circumferential direction (one side magnet 28A described later) and the portion θ2 on the other side in the circumferential direction (the other magnet 28B described later) are from the center line C. It is located on the outer side in the radial direction as the distance from the circumferential direction increases. According to the present embodiment, the magnetic flux extending from the radial outer surface 28a of the second magnet 28 to the stator 30 approaches the center line C as it goes outward in the radial direction, so that the magnetic flux of the second magnet 28 is transferred to the second outer core. It is easy to concentrate on the central part in the circumferential direction of the part 26. As a result, the fluctuation range of the waveform of the combined cogging torque can be suppressed to be smaller. The vibration and noise of the motor 10 are further reduced, and the motor performance is improved.

The second magnet 28 is arranged in a V-shape or a U-shape in a cross-sectional view perpendicular to the central axis J. In the present embodiment, the second magnet 28 is arranged in a V-shape or a U-shape that opens radially outward with the center line C as the center in this cross-sectional view. Both ends in the circumferential direction of the second magnet 28 are located radially outside the central portion in the circumferential direction of the second magnet 28. According to the present embodiment, the magnetic flux extending from the radial outer surface 28a of the second magnet 28 to the stator 30 can be stably brought closer to the center line C as it goes outward in the radial direction.

Both ends of the second magnet 28 in the circumferential direction are located radially inward of both ends of the first magnet 27 in the circumferential direction. Therefore, while the second magnet 28 is arranged in a V-shape or a U-shape, the function of the second magnetic pole portion 52, which is an embedded magnet type, can be stably secured.

The second magnet 28 has a one-sided magnet 28A located on one side θ1 in the circumferential direction with respect to the center line C, and a other-side magnet 28B located on the other side θ2 in the circumferential direction with respect to the center line C. That is, one second magnet 28 is composed of one side magnet 28A and the other side magnet 28B.

The one-side magnet 28A has a plate shape, and a pair of plate surfaces face in the radial direction. Of the radial outer surface 28a of the second magnet 28, the portion arranged on the one-side magnet 28A is located radially outer as the distance from the center line C toward the circumferential one-side θ1. Of the radial inner side surface 28b of the second magnet 28, the portion arranged on the one-side magnet 28A is located on the outer side in the radial direction as the distance from the center line C toward the circumferential one-side θ1.

The other side magnet 28B has a plate shape, and a pair of plate surfaces face in the radial direction. Of the radial outer surface 28a of the second magnet 28, the portion arranged on the other magnet 28B is located radially outer as the distance from the center line C toward the other side θ2 in the circumferential direction. Of the radial inner side surface 28b of the second magnet 28, the portion arranged on the other side magnet 28B is located radially outward as the distance from the center line C toward the other side θ2 in the circumferential direction.

The one-side magnet 28A and the other-side magnet 28B are aligned in the circumferential direction. The one-side magnet 28A and the other-side magnet 28B are arranged apart from each other in the circumferential direction. According to the present embodiment, the second magnet 28 is composed of one side magnet 28A and the other side magnet 28B which are separated from each other. Therefore, it is easy to make the direction of the magnetic flux extending from the portion of the one-side magnet 28A to the stator 30 and the direction of the magnetic flux extending from the portion of the other-side magnet 28B to the stator 30 of the radial outer surface 28a different from each other. Is. Each magnetic flux extending from the one-side magnet 28A and the other-side magnet 28B to the stator 30 can be stably brought closer to the center line C as it goes outward in the radial direction. Further, the shapes of the one-side magnet 28A and the other-side magnet 28B can be simplified, and the second magnet 28 can be easily manufactured.

The one-side magnet 28A and the other-side magnet 28B have the same shape as each other. According to this embodiment, the one-side magnet 28A and the other-side magnet 28B can be used as a common member (common product). Therefore, it is easy to manage and assemble the parts.

In the one-side magnet 28A, the north pole faces one side in the radial direction and the south pole faces the other side in the radial direction. In the other side magnet 28B, the north pole faces one side in the radial direction and the south pole faces the other side in the radial direction. When one side in the radial direction corresponds to the inner side in the radial direction, the other side in the radial direction corresponds to the outer side in the radial direction. When one side in the radial direction corresponds to the outer side in the radial direction, the other side in the radial direction corresponds to the inner side in the radial direction. According to the present embodiment, the orientation of the magnetic poles of the one-side magnet 28A and the orientation of the magnetic poles of the other-side magnet 28B are the same in the radial direction, so that the function of the second magnet 28 is stable.

Of the radial inner side surfaces of the second outer core portion 26, both end portions in the circumferential direction are located radially outside the central portion in the circumferential direction. In other words, the radial inner side surface of the second outer core portion 26 is located radially inward from both end portions toward the central portion in the circumferential direction. According to the present embodiment, the radial outer surface 28a of the second magnet 28 that comes into contact with the radial inner surface of the second outer core portion 26 is formed in a V-shape, a U-shape, or the like that opens radially outward. Cheap. Therefore, the magnetic flux extending from the radial outer surface 28a of the second magnet 28 to the stator 30 can be stably brought closer to the center line C toward the radial outer side.

The first outer core portion 25 has a pedestal portion 25b. The pedestal portion 25b is located at the radial outer end portion of the first outer core portion 25. The pedestal portion 25b comes into contact with the first magnet 27 from the inside in the radial direction, and the dimension in the circumferential direction becomes smaller toward the outer side in the radial direction. According to the present embodiment, the pedestal portion 25b of the first outer core portion 25 is separated from the second magnet 28 adjacent to each other in the circumferential direction as it goes outward in the radial direction. The leakage flux of the first outer core portion 25 can be suppressed. The circumferential dimension of the pedestal portion 25b is equal to or larger than the circumferential dimension of the first magnet 27. In the present embodiment, the circumferential dimension of the radial outer end of the pedestal portion 25b is the same as the circumferential dimension of the radial inner end of the first magnet 27. According to the present embodiment, the pedestal portion 25b can stably support the radial inner side surface 27b of the first magnet 27 over the entire circumferential direction.

The groove portion 29 is recessed in the radial direction from the radial outer surface of the rotor 20 and extends in the axial direction. In the present embodiment, the groove 29 extends over the entire length of the rotor 20 in the axial direction and opens at the upper end surface and the lower end surface of the rotor 20, respectively. A plurality of groove portions 29 are provided at intervals in the circumferential direction. In the present embodiment, eight groove portions 29 are provided in each rotor 20 at equal pitches in the circumferential direction.

The groove 29 is located between the first magnet 27 and the second magnet 28 that are adjacent to each other in the circumferential direction. The groove portion 29 is arranged between the first magnetic pole portion 51 and the second magnetic pole portion 52 in the circumferential direction. At least a part of the groove portion 29 becomes smaller in the circumferential direction toward the outer side in the radial direction. In the present embodiment, the radial inner end portion of the groove portion 29 becomes narrower in the circumferential direction toward the outer side in the radial direction. According to the present embodiment, it is possible to prevent the holding portion 42 of the holder 40 arranged in the groove portion 29, which will be described later, from coming out of the groove portion 29 in the radial direction.

The holder 40 is made of resin. The holder 40 has a holding portion 42 and a connecting portion 43. The holding portion 42 is arranged in the groove portion 29. The holding portion 42 extends in the axial direction. A plurality of holding portions 42 are provided at intervals in the circumferential direction. The number of holding portions 42 is the same as the number of groove portions 29. The holding portion 42 comes into contact with the first magnet 27 and the second magnet 28 in the circumferential direction. According to the present embodiment, the first magnet 27 and the second magnet 28 can be pressed from the circumferential direction by the holding portion 42. The movement of the first magnet 27 and the second magnet 28 in the circumferential direction is suppressed.

The holding portion 42 contacts the first magnet 27 and the second outer core portion 26 from the outside in the radial direction. The holding portion 42 presses the first magnetic pole portion 51 and the second magnetic pole portion 52 from the outside in the radial direction. According to the present embodiment, the holding portion 42 suppresses the movement of the first magnet 27, the second magnet 28, and the second outer core portion 26 to the outside in the radial direction. As a result, the rotational strength when the rotor is rotated 20 times is stably increased.

As shown in FIG. 1, the connecting portion 43 is arranged on the end face of the rotor 20 facing the axial direction. In the present embodiment, the connecting portion 43 is provided on the upper end surface of the first rotor 20A and the lower end surface of the second rotor 20B, respectively. The connecting portion 43 extends in the circumferential direction. The connecting portion 43 is, for example, an annular shape centered on the central axis J. The connecting portion 43 is connected to the axial end portion of each holding portion 42. That is, the connecting portion 43 is connected to the holding portion 42. The connecting portion 43 and the plurality of holding portions 42 are portions of a single member.

The stator 30 faces the rotor 20 with a radial gap. The stator 30 surrounds the rotor 20 from the outside in the radial direction to the entire circumference in the circumferential direction. The stator 30 has a stator core 31, an insulator 32, and a coil 33.

The stator core 31 is an annular shape centered on the central axis J. The stator core 31 has a cylindrical shape extending in the axial direction. The stator core 31 surrounds the rotor 20 from the outside in the radial direction. Although not particularly shown, the stator core 31 is composed of a plurality of electromagnetic steel sheets laminated in the axial direction. The stator core 31 is fixed to the inner peripheral surface of the housing 11. The stator core 31 and the housing 11 are fixed by, for example, shrink fitting or press fitting.

The stator core 31 has a core back 31a and a plurality of teeth 31b. The core back 31a has a cylindrical shape centered on the central axis J. The radial outer surface of the core back 31a is fixed to the inner peripheral surface of the peripheral wall 11a. Specifically, the core back 31a is fixed to the peripheral wall 11a in a state where the radial outer surface of the core back 31a and the inner peripheral surface of the peripheral wall 11a are in contact with each other. The teeth 31b project radially inward from the radial inner surface of the core back 31a. The plurality of teeth 31b are arranged at intervals in the circumferential direction. In this embodiment, a plurality of teeth 31b are arranged at equal pitches in the circumferential direction. The radial inner surface of each tooth 31b faces the radial outer surface of the rotor 20 with a gap.

The insulator 32 is attached to the stator core 31. The insulator 32 is made of an insulating material. The insulator 32 is made of, for example, resin. The insulator 32 is arranged in an annular shape about the central axis J.

The coil 33 is attached to the stator core 31 via the insulator 32. A plurality of coils 33 are provided side by side in the circumferential direction. The number of coils 33 is the same as the number of teeth 31b. Each coil 33 is attached to each tooth 31b via an insulator 32. The coil 33 is configured by winding a conducting wire around the teeth 31b via a part of the insulator 32.

The motor 10 of this embodiment is, for example, a three-phase motor. The three phases are U phase, V phase and W phase. In the case of a three-phase motor, each of the U-phase, V-phase, and W-phase coils 33 is composed of one of a first conductor, a second conductor, and a third conductor.

Next, an example of a device equipped with the motor 10 of the present embodiment will be described. In this embodiment, an example in which the motor 10 is mounted on the electric power steering device 100 will be described.

As shown in FIG. 5, the electric power steering device 100 is mounted on the steering mechanism of the wheels of an automobile. The electric power steering device 100 is a device that reduces the steering force by flood control. The electric power steering device 100 of the present embodiment includes a motor 10, an oil pump 116, a steering shaft 114, and a control valve 117.

The steering shaft 114 transmits the input from the steering 111 to the axle 113 having the wheels 112. The oil pump 116 generates oil in the power cylinder 115. The power cylinder 115 transmits a hydraulic driving force to the axle 113. The control valve 117 controls the oil in the oil pump 116. In the electric power steering device 100, the motor 10 is mounted as a drive source of the oil pump 116.

The electric power steering device 100 of the present embodiment includes the motor 10 of the present embodiment. Therefore, the electric power steering device 100 having the same effect as the motor 10 described above can be obtained.

The present invention is not limited to the above-described embodiment, and the configuration can be changed without departing from the spirit of the present invention, for example, as described below.

FIG. 6 shows a modified example of the motor 10 described in the above-described embodiment. In this modification, as shown in FIG. 6, the second magnet 28 of the rotor 20 is arranged in a U shape in a cross-sectional view perpendicular to the central axis J. The second magnet 28 has a one-side magnet 28A, a other-side magnet 28B, and an intermediate magnet 28C. The intermediate magnet 28C is located between the one-side magnet 28A and the other-side magnet 28B in the circumferential direction. In the illustrated example, the intermediate magnet 28C is located on the center line C in this cross-sectional view. The one-side magnet 28A and the intermediate magnet 28C are arranged apart from each other in the circumferential direction. The other side magnet 28B and the intermediate magnet 28C are arranged apart from each other in the circumferential direction. That is, the one-side magnet 28A, the intermediate magnet 28C, and the other-side magnet 28B are arranged apart from each other in the circumferential direction. The intermediate magnet 28C has a plate shape, and a pair of plate surfaces face in the radial direction. Of the radial outer surface 28a of the second magnet 28, the portion arranged on the intermediate magnet 28C has a planar shape extending in the direction perpendicular to the radial direction. Of the radial inner side surface 28b of the second magnet 28, the portion arranged on the intermediate magnet 28C has a planar shape extending in the direction perpendicular to the radial direction. The one-side magnet 28A, the other-side magnet 28B, and the intermediate magnet 28C have the same shape as each other. The one-side magnet 28A, the other-side magnet 28B, and the intermediate magnet 28C are common members (common products). Similar to the one-side magnet 28A and the other-side magnet 28B, the intermediate magnet 28C has an N pole facing one side in the radial direction and an S pole facing the other side in the radial direction. Also in this modified example, the same action and effect as those of the above-described embodiment can be obtained.

In the above-described embodiment, the radial inner surface 27b of the first magnet 27 is planar, the radial outer surface 25a of the first outer core portion 25 is planar, and these are in contact with each other as an example. However, it is not limited to this. FIG. 7 shows a modified example of the motor 10 described in the above-described embodiment. In this modification, as shown in FIG. 7, the radial outer surface 25a of the first outer core portion 25 has a convex curved surface shape that bulges outward in the radial direction, and the radial inner surface 27b of the first magnet 27 is formed. , It is a concave curved surface that is recessed outward in the radial direction, and these come into contact with each other. In this case, both the radial outer surface 27a and the radial inner surface 27b of the first magnet 27 are curved surfaces that are convex outward in the radial direction. That is, the first magnet 27 has an arch shape that is convex outward in the radial direction when viewed from the axial direction.

In the above-described embodiment, the motor 10 is mounted on the electric power steering device 100, but the present invention is not limited to this. The motor 10 may be used in, for example, pumps, brakes, clutches, vacuum cleaners, dryers, sealing fans, washing machines, refrigerators and the like.

In addition, each configuration described in the above-described embodiments and modifications may be combined as long as the gist of the present invention is not deviated, and the configurations may be added, omitted, replaced, or otherwise changed. Further, the present invention is not limited to the above-described embodiments, but is limited only to the scope of claims.

10 ... motor, 20 ... rotor, 20A ... first rotor, 20B ... second rotor, 24 ... inner core part, 25 ... first outer core part, 26 ... second outer core part, 27 ... first magnet, 28 ... 2nd magnet, 28A ... one side magnet, 28B ... other side magnet, 30 ... stator, 51 ... first magnetic pole part, 52 ... second magnetic pole part, C ... center line, J ... central axis, θ1 ... circumferential direction one side , Θ2 ... The other side in the circumferential direction

Claims (8)

Cylindrical stator and
It is provided with a pair of rotors, which are located radially inside the stator, rotate about a central axis, and are laminated in the axial direction.
The rotor
Inner core part and
The first outer core portion located radially outside the inner core portion and
A second outer core portion that is located radially outside the inner core portion and is arranged at a position different from that of the first outer core portion in the circumferential direction.
A first magnet arranged radially outside the first outer core portion,
It has a second magnet arranged between the inner core portion and the second outer core portion in the radial direction.
In a cross-sectional view perpendicular to the central axis, the second magnet has a portion located radially outward as it is separated from the center in the circumferential direction of the second outer core portion and the center line passing through the central axis in the circumferential direction. Have and
A first magnetic pole portion composed of the first outer core portion and the first magnet arranged in the radial direction, and a second magnetic pole portion composed of the second magnet and the second outer core portion arranged in the radial direction. And are arranged alternately in the circumferential direction,
The first magnetic pole portion of one of the pair of rotors and the second magnetic pole portion of the other are arranged side by side in the axial direction and have the same circumferential position with each other.
motor. The second magnet is arranged in a V-shape or a U-shape in a cross-sectional view perpendicular to the central axis.
The motor according to claim 1. Both ends in the circumferential direction of the second magnet are located radially outside the central portion in the circumferential direction of the second magnet.
The motor according to claim 1 or 2. Both ends in the circumferential direction of the second magnet are located radially inside the both ends in the circumferential direction of the first magnet.
The motor according to any one of claims 1 to 3. Of the radial inner side surfaces of the second outer core portion, both end portions in the circumferential direction are located radially outside the central portion in the circumferential direction.
The motor according to any one of claims 1 to 4. The second magnet is
A one-sided magnet located on one side in the circumferential direction from the center line,
It has a magnet on the other side located on the other side in the circumferential direction with respect to the center line.
The one-side magnet and the other-side magnet are arranged apart from each other in the circumferential direction.
The motor according to any one of claims 1 to 5. The one-sided magnet has a plate shape and has a plate shape.
The other side magnet has a plate shape and has a plate shape.
The one-sided magnet and the other-sided magnet have the same shape as each other.
The motor according to claim 6. In the one-sided magnet, the north pole faces one side in the radial direction and the south pole faces the other side in the radial direction.
In the other side magnet, the north pole faces one side in the radial direction and the south pole faces the other side in the radial direction.
The motor according to claim 6 or 7.

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