JP7131563B2 - Rotors, motors and electric power steering devices - Google Patents

Description

The present invention relates to rotors, motors, and electric power steering devices.

Generally, a motor has a rotor and a stator. The rotor has at least one magnet. Both cogging torque and torque ripple must be reduced in order to reduce the vibration and noise generated by the motor.

Conventional motors reduce cogging torque by providing projections and skews that cause phase reversal. Skew is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2002-200010. Also, by increasing the sine wave factor of the induced voltage, the torque ripple is reduced.

Japanese Patent No. 5414887

Cogging torque is generally counteracted by applying skew to generate and cancel the opposite phase, but there was a problem that applying skew would lead to a decrease in torque. Moreover, the cogging torque and the torque ripple have a trade-off relationship with respect to the skew angle, and it is difficult to reduce both the cogging torque and the torque ripple.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a rotor, a motor, and an electric power steering apparatus capable of reducing cogging torque while suppressing torque drop and reducing torque ripple.

One aspect of the rotor of the present invention includes a shaft having a central axis, a rotor core fixed to the shaft, and a magnet portion and a magnetic portion provided radially side by side on the radially outer surface of the rotor core. A plurality of sets of the magnet portion and the magnetic portion are arranged on the radially outer surface of the rotor core in the circumferential direction and the axial direction, and the plurality of the sets are arranged on the radially outer surface of the rotor core. A first set in which the magnet portion is arranged and the magnetic portion is arranged on the radial outer surface of the magnet portion, and a first set in which the magnetic portion is arranged on the radial outer surface of the rotor core and the magnetic portion is arranged in the radial direction and a second set in which the magnet portion is arranged on the outer surface, and the first set is arranged in the circumferential direction in a first portion along the axial direction of the radial outer surface of the rotor core. In a second portion of the radially outer surface of the rotor core that is different from the first portion along the axial direction, the second sets are arranged in the circumferential direction, and when viewed from the axial direction, the first The first set of portions and the second set of the second portions are arranged in an overlapping arrangement.

Further, one aspect of the motor of the present invention includes the rotor described above and a stator facing the rotor with a gap in the radial direction.

Moreover, one aspect of the electric power steering apparatus of the present invention includes the motor described above.

ADVANTAGE OF THE INVENTION According to the rotor, the motor, and the electric power steering device of one aspect of the present invention, cogging torque can be reduced while suppressing torque reduction, and torque ripple can be reduced.

FIG. 1 is a schematic cross-sectional view of a rotor and a motor of one embodiment. FIG. 2 is a perspective view of a rotor of one embodiment. 3 is an enlarged sectional view showing a part of the III-III section of FIG. 1. FIG. 4 is an enlarged sectional view showing a part of the IV-IV section of FIG. 1. FIG. FIG. 5 is a graph showing the waveform of the cogging torque of the motor of one embodiment. FIG. 6 is a graph showing the waveform of the torque ripple of the motor of one embodiment. FIG. 7 is an enlarged cross-sectional view showing part of a rotor of a modified example of one embodiment. FIG. 8 is a schematic diagram showing an electric power steering device according to one embodiment.

In the following description, the axial direction of the central axis J, that is, the direction parallel to the vertical direction is simply referred to as the "axial direction", the radial direction around the central axis J is simply referred to as the "radial direction", and the central axis J is simply referred to as the "circumferential direction". In this embodiment, 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. Note that the vertical direction, upper side, and lower side are simply names for explaining the relative positional relationship of each part, and the actual arrangement relationship etc. is not the arrangement relationship etc. indicated by these names. may

As shown in FIG. 1, the motor 10 of this embodiment includes a rotor 20, a stator 30, a housing 11, and a plurality of bearings 15,16. As shown in FIGS. 1 to 4, the rotor 20 includes a shaft 21 having a central axis J, a rotor core 22, a plurality of magnet portions 23a and 23b, a plurality of magnetic portions 24a and 24b, a cover portion 25, Prepare.

The shaft 21 extends vertically along the central axis J. As shown in FIG. In the example of this embodiment, the shaft 21 has a cylindrical shape extending in the axial direction. The shaft 21 is rotatably supported around the central axis J by a plurality of bearings 15 and 16 . A plurality of bearings 15 and 16 are axially spaced from each other and supported by the housing 11 . The housing 11 is cylindrical.

The shaft 21 is fixed to the rotor core 22 by press fitting, bonding, or the like. That is, rotor core 22 is fixed to shaft 21 . Note that the shaft 21 may be fixed to the rotor core 22 via a resin member or the like. That is, shaft 21 is directly or indirectly fixed to rotor core 22 . The shaft 21 is not limited to the cylindrical shape, and may be cylindrical, for example.

The rotor core 22 is, for example, a laminated steel plate configured by laminating a plurality of electromagnetic steel plates in the axial direction. The rotor core 22 is tubular. The rotor core 22 has a polygonal outer shape when viewed from the axial direction (see FIG. 2). A radial outer surface of the rotor core 22 has a plurality of flat portions 22a arranged in the circumferential direction. In the example of this embodiment, the outer shape of the rotor core 22 is octagonal. The radial outer surface of the rotor core 22 has eight flat portions 22a arranged in the circumferential direction. The planar portion 22a has a planar shape extending in a direction perpendicular to the radial direction. The flat portion 22 a extends axially on the radial outer surface of the rotor core 22 . The flat portion 22a is arranged on the radially outer surface of the rotor core 22 over the entire length in the axial direction. In the example of this embodiment, the axial length of the plane portion 22a is greater than the circumferential length.

The rotor core 22 has a through hole 22h, a hole portion 22b, and a groove portion 22c. The through hole 22h is arranged at the center of the rotor core 22 when viewed from the axial direction. The through hole 22h penetrates the rotor core 22 in the axial direction. The shaft 21 is inserted into the through hole 22h.

The hole 22b penetrates the rotor core 22 in the axial direction. A plurality of holes 22b are arranged in the rotor core 22 at intervals in the circumferential direction. In the example of this embodiment, the holes 22b are arranged in the rotor core 22 at regular intervals in the circumferential direction. The hole 22b has a circular shape when viewed from the axial direction. According to the present embodiment, the weight of the rotor core 22 can be reduced by hollowing out the rotor core 22 with the holes 22b, and the material cost can be reduced.

The groove portion 22c is recessed radially inward from the radial outer surface of the rotor core 22 and extends in the axial direction. The groove portion 22c is arranged on the radial outer surface of the rotor core 22 over the entire length in the axial direction. The groove portion 22c is arranged between a pair of circumferentially adjacent flat portions 22a on the radial outer surface of the rotor core 22 and opens radially outward. A plurality of groove portions 22c are arranged in the rotor core 22 at intervals in the circumferential direction. The grooves 22c are arranged in the rotor core 22 at regular intervals in the circumferential direction. The groove width of the groove portion 22c becomes smaller toward the radially outer side. When viewed from the axial direction, the groove 22c is wedge-shaped.

The magnet portions 23a and 23b are permanent magnets. The magnetic portions 24a and 24b are made of a magnetic material (ferromagnetic material), such as iron, stainless steel, or steel. As shown in FIGS. 3 and 4, the magnet portions 23a and 23b and the magnetic portions 24a and 24b are provided radially side by side on the radial outer surface of the rotor core 22. As shown in FIGS. The magnet portions 23a and 23b and the magnetic portions 24a and 24b are provided on the plane portion 22a so as to overlap each other in the radial direction. In a cross-sectional view perpendicular to the central axis J, the magnet portions 23a and 23b and the magnetic portions 24a and 24b are radially laminated on the plane portion 22a and provided one each (two in total).

A plurality of sets P1 and P2 of the magnet portions 23a and 23b and the magnetic portions 24a and 24b arranged in the radial direction are provided on the radial outer surface of the rotor core 22 so as to be arranged in the circumferential direction and the axial direction, respectively. In the example of the present embodiment, the pairs P1 and P2 arranged in the axial direction are arranged with no space between them in the axial direction. The sets P1, P1 and the sets P2, P2 arranged in the circumferential direction are spaced from each other in the circumferential direction. A groove portion 22c is arranged between a pair of sets P1, P1 adjacent in the circumferential direction. A groove portion 22c is arranged between a pair of sets P2, P2 adjacent in the circumferential direction.

The multiple sets P1 and P2 include a first set P1 and a second set P2. In the first set P1, the magnet portion 23a is arranged on the radially outer surface of the rotor core 22, and the magnetic portion 24b is arranged on the radially outer surface of the magnet portion 23a. That is, the first set P1 has the magnet portion 23a and the magnetic portion 24b arranged in this order from the flat portion 22a toward the radially outer side. The magnet portion 23a of the first set P1 is covered from the radially outer side by the magnetic portion 24b. The magnet portion 23a is arranged radially inward in the first set P1. The magnet part 23a can be said to be, for example, an interior permanent magnet (IPM) type.

In the second set P2, the magnetic portion 24a is arranged on the radially outer surface of the rotor core 22, and the magnet portion 23b is arranged on the radially outer surface of the magnetic portion 24a. That is, the second set P2 has the magnetic portion 24a and the magnet portion 23b arranged in this order from the flat portion 22a toward the radially outer side. The magnet portion 23b is arranged radially outward in the second set P2. The magnet part 23b can be said to be, for example, a surface permanent magnet (SPM).

In the example of the present embodiment, the shape of the magnet portion 23a of the first set P1 and the shape of the magnetic portion 24a of the second set P2 are the same. Also, the shape of the magnetic portion 24b of the first set P1 and the shape of the magnet portion 23b of the second set P2 are the same.

The magnet portion 23a and the magnetic portion 24a are each plate-shaped. The magnet portion 23a and the magnetic portion 24a are rectangular plates. As shown in FIGS. 3 and 4, when viewed from the axial direction, the magnet portion 23a of the first set P1 and the magnetic portion 24a of the second set P2 each have a circumferential length larger than a radial length. It has a large rectangular shape. The radially inner side surface and the radially outer side surface of the magnet portion 23a each have a planar shape extending in a direction perpendicular to the radial direction. The radially inner side surface and the radially outer side surface of the magnetic portion 24a each have a planar shape extending in a direction perpendicular to the radial direction.

The magnet portion 23b and the magnetic portion 24b are each plate-shaped. When viewed from the radial direction, the magnet portion 23b and the magnetic portion 24b have a square shape. The magnet portion 23b and the magnetic portion 24b increase in thickness in the radial direction from both end portions in the circumferential direction toward the central portion (inner side in the circumferential direction). When viewed from the axial direction, the magnetic portion 24b of the first set P1 and the magnet portion 23b of the second set P2 each have a straight radial inner surface and a convex curved radial outer surface. A radially inner surface of the magnetic portion 24b has a planar shape extending in a direction perpendicular to the radial direction. A radially outer surface of the magnetic portion 24b has a curved surface that protrudes radially outward when viewed from the axial direction. A radially inner surface of the magnet portion 23b has a planar shape extending in a direction perpendicular to the radial direction. A radially outer surface of the magnet portion 23b has a curved surface that protrudes radially outward when viewed from the axial direction. When viewed from the axial direction, the magnetic portion 24b and the magnet portion 23b are substantially D-shaped.

In the example of the present embodiment, in the first set P1, both circumferential ends of the magnet portion 23a and both circumferential ends of the magnetic portion 24b are arranged to overlap each other when viewed in the radial direction. That is, the circumferential positions of both ends of the magnet portion 23a in the circumferential direction are the same as the positions of both ends of the magnetic portion 24b in the circumferential direction. Both circumferential ends of the magnet portion 23a and the magnetic portion 24b (that is, the first set P1) and both circumferential ends of the plane portion 22a overlap when viewed in the radial direction. In the illustrated example, the circumferential positions of both ends of the flat portion 22a are arranged slightly outside the circumferential positions of both ends of the first set P1 in the circumferential direction. That is, the circumferential length of the plane portion 22a is greater than the circumferential length of the first set P1.

In addition, in the second set P2, both circumferential ends of the magnetic portion 24a and both circumferential ends of the magnet portion 23b are arranged to overlap each other when viewed from the radial direction. That is, the circumferential positions of both circumferential ends of the magnetic portion 24a are the same as the circumferential positions of both circumferential ends of the magnet portion 23b. In addition, both circumferential ends of the magnetic portion 24a and the magnet portion 23b (that is, the second set P2) and both circumferential ends of the plane portion 22a overlap each other when viewed in the radial direction. In the illustrated example, the circumferential positions of both ends of the flat portion 22a are arranged slightly outside in the circumferential direction of the circumferential positions of both ends of the second set P2. That is, the circumferential length of the plane portion 22a is greater than the circumferential length of the second set P2.

The volume of the magnet portion 23a of the first set P1 and the volume of the magnetic portion 24a of the second set P2 are the same as each other. The volume of the magnetic portion 24b of the first set P1 is the same as the volume of the magnet portion 23b of the second set P2. According to the present embodiment, the shape, characteristics, etc. of the first set P1 (the magnet portion 23a and the magnetic portion 24b) and the shape, characteristics, etc. of the second set P2 (the magnetic portion 24a and the magnet portion 23b) are can be equalized. As a result, the effects of the present embodiment, which will be described later, can be obtained more stably.

In a first portion (first stage, first region) S1 along the axial direction of the radial outer surface of the rotor core 22, the first set P1 is arranged in the circumferential direction. In the first portion S1, a plurality of first sets P1 are arranged on the radially outer surface of the rotor core 22 at regular intervals in the circumferential direction. In a second portion (second stage, second region) S2 different from the first portion S1 along the axial direction of the radial outer surface of the rotor core 22, the second set P2 is arranged in the circumferential direction. . In the second portion S2, a plurality of the second sets P2 are arranged on the radial outer surface of the rotor core 22 at regular intervals in the circumferential direction.

When viewed in the axial direction, the first set P1 of the first portions S1 and the second set P2 of the second portions S2 are arranged to overlap. In the present embodiment, when viewed from the axial direction, the circumferential center of the first set P1 of the first portions S1 and the circumferential center of the second set P2 of the second portions S2 placed on top of each other. Also, when viewed from the axial direction, both circumferential ends of the first set P1 of the first portions S1 and both circumferential ends of the second set P2 of the second portions S2 overlap each other. placed. Therefore, the magnet portions 23a and 23b are not skewed, and the magnet portions 23a and 23b are arranged straight in the axial direction.

FIG. 5 is a graph showing the waveform of the cogging torque of the motor 10 having the rotor 20 of this embodiment. FIG. 6 is a graph showing the torque ripple waveform of the motor 10 of this embodiment. As shown in FIGS. 5 and 6, according to the present embodiment, cogging torque can be generated in opposite phases without skewing the magnet portions 23a and 23b. That is, since the cogging torque generated in the first portion S1 and the cogging torque generated in the second portion S2 are generated in opposite phases to each other, they cancel each other out, and the fluctuation width of the combined gogging torque waveform (combined cogging torque (difference between the maximum and minimum values of ) can be kept small. Also, it is possible to generate an opposite phase in the torque ripple. That is, since the torque ripple generated in the first portion S1 and the torque ripple generated in the second portion S2 are generated in opposite phases to each other, they cancel each other out, and the fluctuation range of the synthesized torque ripple waveform (the synthesized torque difference between the maximum and minimum values of ripple) can be kept small. Therefore, according to the present embodiment, cogging torque can be reduced while suppressing torque reduction, and torque ripple can be reduced. Vibration and noise generated by the motor 10 can also be reduced.

Moreover, by arranging the magnet portions 23a and 23b and the magnetic portions 24a and 24b side by side in the radial direction, it is possible to reduce the amount of magnets (permanent magnets) used while suppressing a decrease in torque. Specifically, for example, a magnet portion (not shown) having the same volume as the sum of the volume of the magnet portion 23a (23b) and the volume of the magnetic portion 24b (24a) per set P1 (P2) is set to the diameter of the rotor core 22. A configuration (hereinafter referred to as a reference example) in which a plurality of magnets are arranged on the outer side surface in the same manner as in the present embodiment is compared with the usage of each magnet in the present embodiment. In this case, compared with the reference example, in this embodiment, it is possible to reduce the amount of magnets used to about half while suppressing the decrease in torque to about 20%. In other words, the amount of magnet used can be reduced without lowering the torque. In general, the ratio of the cost of magnets to the cost of the entire rotor 20 is high, so according to this embodiment, the cost of the entire rotor 20 can be easily reduced.

In the present embodiment, the same number of first portions S1 and second portions S2 are arranged alternately in the axial direction on the radial outer surface of the rotor core 22 . That is, the sum of the number of the first portions S1 and the number of the second portions S2 is an even number, and the first portions S1 and the second portions S2 are arranged alternately in the axial direction. As a result, the above-described effect of reducing cogging torque and torque ripple can be obtained more stably. In the example of the present embodiment, one first portion S1 and one second portion S2 are arranged axially on the radial outer surface of the rotor core 22 . Therefore, the above effects can be obtained with a simple structure.

The cover portion 25 has a cylindrical shape centered on the central axis J. As shown in FIG. In the example of this embodiment, the cover part 25 is cylindrical. The cover portion 25 surrounds the rotor core 22, the magnet portions 23a and 23b, and the magnetic portions 24a and 24b from the radial outside. The inner peripheral surface of the cover portion 25 and the radially outer end portion of the first set P1 are in contact with each other or face each other with a gap therebetween. Specifically, the inner peripheral surface of the cover portion 25 and the circumferential central portion of the radial outer surface of the first set P1 are in contact with each other or face each other with a gap therebetween. The inner peripheral surface of the cover portion 25 and the radially outer end portion of the second set P2 are in contact with each other or face each other with a gap therebetween. Specifically, the inner peripheral surface of the cover portion 25 and the circumferential center portion of the radially outer surface of the second set P2 are in contact with each other or face each other with a gap therebetween. The rotor core 22, the magnet portions 23a and 23b, and the magnetic portions 24a and 24b are arranged with an air gap G in the radial direction between them and the inner peripheral surface of the cover portion 25. As shown in FIG. According to the present embodiment, even if the magnet portions 23a, 23b and the magnetic portions 24a, 24b are radially laminated on the radial outer surface of the rotor core 22, the cover portion 25 allows the magnet portions 23a, 23b and the magnetic portions 23a, 23b and It is possible to suppress radially outward movement of the magnetic portions 24a and 24b. A resin portion may be filled between the cover portion 25 and the rotor core 22, the magnet portions 23a and 23b and the magnetic portions 24a and 24b.

FIG. 7 shows a modification of the rotor 20 of this embodiment. This rotor 20 includes a resin molded portion 26 instead of or together with the cover portion 25 . The resin molded portion 26 is provided on the radial outer surface of the rotor core 22 . A plurality of resin molded portions 26 are arranged on the radial outer surface of the rotor core 22 at intervals in the circumferential direction. The resin molded portion 26 extends along the groove portion 22c. The resin mold portion 26 is formed by insert-molding melted resin together with the rotor core 22 and solidifying it.

The resin molded portion 26 has an anchor portion 26a and a movement suppressing portion 26b. The anchor portion 26a is formed by filling the groove portion 22c with molten resin and solidifying it. The anchor portion 26a extends axially. The circumferential width of the anchor portion 26a increases radially inward. The movement suppressing portion 26b is located radially outside the anchor portion 26a and is connected to the anchor portion 26a. The movement suppressing portion 26 b is arranged at the radially outer end portion of the resin molded portion 26 . The movement suppressing portion 26b protrudes toward both sides (one side and the other side) in the circumferential direction with respect to the anchor portion 26a. The movement suppressing portion 26b has a plate-like shape with a plate surface facing the radial direction. The movement suppressing portion 26b extends in the axial direction. The movement suppressing portion 26b is arranged radially outward of the flat portion 22a with a gap therebetween. When viewed from the radial direction, the movement suppressing portion 26b and the flat portion 22a are arranged to overlap each other.

After forming the resin molded portion 26, the set P1, P2 is inserted between the flat portion 22a and the movement suppressing portion 26b. The pair P1, P2 is, for example, press-fitted between the flat portion 22a and the movement suppressing portion 26b. According to the present embodiment, the wedge-shaped groove portion 22c is provided on the radially outer surface of the rotor core 22, so that the resin mold portion 26 can function. That is, it is possible to provide the resin molded portion 26 that is prevented from coming off in the radial direction with respect to the groove portion 22c. The magnet portions 23a and 23b and the magnetic portions 24a and 24b can be pressed from the radially outer side by the resin molded portion 26, and the radially outward movement of the magnet portions 23a and 23b and the magnetic portions 24a and 24b can be suppressed.

As shown in FIG. 1, the stator 30 has a stator core 31, insulators 30Z, and multiple coils 30C. The stator core 31 has an annular shape centering on the central axis J. As shown in FIG. Stator core 31 surrounds rotor 20 on the radially outer side of rotor 20 . The stator core 31 faces the rotor 20 with a gap in the radial direction. That is, the stator 30 faces the rotor 20 with a gap in the radial direction. The stator core 31 is, for example, a laminated steel plate configured by laminating a plurality of electromagnetic steel plates in the axial direction.

The stator core 31 has a substantially annular core back 31a and a plurality of teeth 31b. In this embodiment, the core back 31a has an annular shape centered on the central axis J. As shown in FIG. The teeth 31b extend radially inward from the radial inner surface of the core back 31a. The outer peripheral surface of the core back 31 a is fixed to the inner peripheral surface of the peripheral wall portion of the housing 11 . The plurality of teeth 31b are arranged on the radially inner surface of the core back 31a at intervals in the circumferential direction. In this embodiment, a plurality of teeth 31b are arranged at regular intervals in the circumferential direction.

The insulator 30Z is attached to the stator core 31 . The insulator 30Z has a portion that covers the teeth 31b. A material of the insulator 30Z is, for example, an insulating material such as resin.

Coil 30</b>C is attached to stator core 31 . A plurality of coils 30C are attached to stator core 31 via insulators 30Z. The plurality of coils 30C are configured by winding conductive wires around the respective teeth 31b via insulators 30Z.

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

As shown in FIG. 8, the electric power steering device 100 is mounted on a steering mechanism for the wheels of an automobile. The electric power steering device 100 is a device that reduces steering force by hydraulic pressure. An electric power steering device 100 of this embodiment includes a motor 10 , a steering shaft 114 , an oil pump 116 and a control valve 117 .

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

An electric power steering device 100 of this embodiment includes the motor 10 of this embodiment. Therefore, the electric power steering apparatus 100 having the same effects as the motor 10 described above can be obtained.

It should be noted that the present invention is not limited to the above-described embodiments, and, for example, as described below, changes in configuration can be made without departing from the gist of the present invention.

The shapes of the magnet portions 23a and 23b and the shapes of the magnetic portions 24a and 24b are not limited to the examples described in the above embodiments. Also, the volume of the magnet portion 23a of the first set P1 and the volume of the magnet portion 23b of the second set P2 may be different from each other. The volume of the magnetic portion 24b of the first set P1 and the volume of the magnetic portion 24a of the second set P2 may be different from each other.

Instead of or while providing the cover portion 25 and the resin molded portion 26 on the rotor 20, the planar portion 22a, the magnet portions 23a and 23b, and the magnetic portions 24a and 24b, which are in contact with each other in the radial direction, are fixed by adhesion or the like. good too.

In the above-described embodiment, the rotor core 22 and the magnetic portions 24a and 24b are provided on the rotor 20 as separate members, but the present invention is not limited to this. The rotor core 22 and the magnetic portions 24a, 24b may be a single member. Alternatively, the magnet portion 23a may be embedded in the magnetic portion 24b provided integrally with the rotor core 22 . In this case, the cover portion 25 may surround the second portion S2 from the radially outer side. This can prevent the magnet portion 23b from coming off in the second portion S2.

In the above embodiment, an example in which the motor 10 is mounted on the electric power steering device 100 was given, but the present invention is not limited to this. Motor 10 can be used in a variety of appliances such as pumps, brakes, clutches, vacuum cleaners, dryers, ceiling fans, washing machines and refrigerators.

In addition, within the scope that does not deviate from the spirit of the present invention, each configuration (component) described in the above-described embodiments, modifications, notes, etc. may be combined, and addition, omission, replacement, and other Change is possible. Moreover, the present invention is not limited by the embodiments described above, but only by the claims.

Reference Signs List 10 motor 20 rotor 21 shaft 22 rotor core 22b hole 22c groove 23a, 23b magnet portion 24a, 24b magnetic portion 25 cover portion 30 stator 100 Electric power steering device, J... Central shaft, P1, P2... Group, P1... First group, P2... Second group, S1... First part, S2... Second part

Claims (15)

a shaft having a central axis;
a rotor core fixed to the shaft;
a magnet portion and a magnetic portion provided side by side in the radial direction on the radial outer surface of the rotor core,
A plurality of sets of the magnet portion and the magnetic portion are arranged in the radial direction outer surface of the rotor core in the circumferential direction and in the axial direction, and
The plurality of said sets are
a first set in which the magnet portion is arranged on the radial outer surface of the rotor core and the magnetic portion is arranged on the radial outer surface of the magnet portion;
a second set in which the magnetic portion is arranged on the radially outer surface of the rotor core and the magnet portion is arranged on the radially outer surface of the magnetic portion;
The first set is arranged in the circumferential direction in a first portion along the axial direction of the radially outer surface of the rotor core,
In a second portion of the radially outer surface of the rotor core that is different from the first portion along the axial direction, the second sets are arranged in the circumferential direction,
A rotor wherein, viewed in the axial direction, the first set of the first portions and the second set of the second portions are arranged to overlap. A rotor according to claim 1, wherein
When viewed from the axial direction, the circumferential central portion of the first set of the first portions and the circumferential central portion of the second set of the second portions are arranged to overlap each other. , rotor. 3. The rotor according to claim 1 or 2,
When viewed from the axial direction, both circumferential ends of the first set of the first portion and both circumferential ends of the second set of the second portion overlap each other. , rotor. The rotor according to any one of claims 1 to 3,
The rotor, wherein the same number of the first portions and the second portions are alternately arranged in the axial direction on the radial outer surface of the rotor core. A rotor according to claim 4,
The rotor, wherein the first portion and the second portion are axially arranged one by one on the radially outer surface of the rotor core. The rotor according to any one of claims 1 to 5,
the shape of the magnet portion of the first set and the shape of the magnetic portion of the second set are the same;
The rotor, wherein the shape of the magnetic portion of the first set and the shape of the magnet portion of the second set are the same. A rotor according to claim 6, wherein
Seen from the axial direction,
each of the magnet portion of the first set and the magnetic portion of the second set has a rectangular shape whose length in the circumferential direction is greater than the length in the radial direction;
The rotor, wherein each of the magnetic portion of the first set and the magnet portion of the second set has a straight radial inner surface and a convex curved radial outer surface. A rotor according to claim 6 or 7,
the volume of the magnet portion of the first set and the volume of the magnetic portion of the second set are the same;
The rotor, wherein the volume of the magnetic portion of the first set and the volume of the magnet portion of the second set are the same. The rotor according to any one of claims 1 to 8,
The rotor, wherein the rotor core has a hole extending axially through the rotor core. A rotor according to claim 9, wherein
The rotor, wherein a plurality of the holes are arranged in the rotor core at intervals in the circumferential direction. The rotor according to any one of claims 1 to 10,
The rotor core has a groove portion recessed radially inward from a radial outer surface of the rotor core and extending in the axial direction,
In the rotor, the groove portion is arranged between a pair of pairs of the pairs adjacent in the circumferential direction and opens radially outward, and the width of the groove becomes smaller toward the radially outer side. The rotor according to any one of claims 1 to 11,
A rotor comprising a cover portion that surrounds the rotor core, the magnet portion, and the magnetic portion from the radial outside. 13. The rotor of claim 12, wherein
The rotor, wherein the cover portion surrounds the second portion from the radial outside. A rotor according to any one of claims 1 to 13;
and a stator facing the rotor with a gap in the radial direction. An electric power steering device comprising the motor according to claim 14.

Images