CN113472169B - Motor with a motor housing - Google Patents
Motor with a motor housing Download PDFInfo
- Publication number
- CN113472169B CN113472169B CN202110324086.3A CN202110324086A CN113472169B CN 113472169 B CN113472169 B CN 113472169B CN 202110324086 A CN202110324086 A CN 202110324086A CN 113472169 B CN113472169 B CN 113472169B
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- magnet
- core portion
- circumferential direction
- magnetic pole
- outer core
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- 238000012986 modification Methods 0.000 description 9
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- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
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- 229920005989 resin Polymers 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- -1 for example Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
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- 239000013585 weight reducing agent Substances 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
- H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
- H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Permanent Field Magnets Of Synchronous Machinery (AREA)
Abstract
And a motor having a stator and a pair of rotors which rotate around a central axis and are stacked in the axial direction. The rotor has: an inner core part; a first outer core portion; a second outer core portion disposed at a position different from the first outer core portion in the circumferential direction; a first magnet disposed radially outward of the first outer core portion; and a second magnet disposed between the inner core portion and the second outer core portion in the radial direction. The second magnet has a portion that is located radially outward as being away from a center line passing through a center of a circumferential direction of the second outer core portion and the center axis in a circumferential direction in a cross-sectional view perpendicular to the center axis. The first magnetic pole portions composed of the first outer core portions and the first magnets arranged in the radial direction and the second magnetic pole portions composed of the second magnets and the second outer core portions arranged in the radial direction are alternately arranged in the circumferential direction. One of the first magnetic pole portions and the other of the second magnetic pole portions of the pair of rotors are arranged in an axial direction, and the circumferential positions of the first magnetic pole portions and the second magnetic pole portions are the same.
Description
Technical Field
The present invention relates to a motor.
Background
The motor has a rotor and a stator. The motor can suppress vibration or noise by reducing cogging torque. For example, as described in patent document 1, in a conventional motor, a stage skew (STAGE SKEW) is provided to a rotor and a stator to reduce cogging torque.
Patent document 1: japanese patent application laid-open No. 2004-159792
If the skew is provided, the manufacturing process of the motor increases, and productivity decreases.
Disclosure of Invention
An object of the present invention is to provide a motor capable of reducing cogging torque without providing skew.
One embodiment of the present invention is a motor including: a cylindrical stator; and a pair of rotors which are located radially inward of the stator and rotate about a central axis, and which are stacked in the axial direction. The rotor has: an inner core part; a first outer core portion located radially outward of the inner core portion; a second outer core portion located radially outward of the inner core portion and disposed at a position different from the first outer core portion in the circumferential direction; a first magnet disposed radially outward of the first outer core portion; and a second magnet disposed between the inner core portion and the second outer core portion in a radial direction. The second magnet has a portion that is located radially outward as being away from a center line passing through a center of a circumferential direction of the second outer core portion and the center axis in a circumferential direction in a cross-sectional view perpendicular to the center axis. First magnetic pole portions composed of the first outer core portions and the first magnets arranged in the radial direction and second magnetic pole portions composed of the second magnets and the second outer core portions arranged in the radial direction are alternately arranged 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 in an axial direction, and the circumferential positions of the first magnetic pole portion and the second magnetic pole portion are the same.
According to the motor of one embodiment of the present invention, cogging torque can be reduced without providing skew.
Drawings
Fig. 1 is a sectional view schematically showing a 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 section III-III of fig. 1.
Fig. 4 is a cross-sectional view showing a section IV-IV of fig. 1.
Fig. 5 is a schematic view showing an electric power steering apparatus having a motor of the present embodiment.
Fig. 6 is a cross-sectional view showing a part of a rotor of a motor according to a modification of the present embodiment.
Fig. 7 is a cross-sectional view showing a part of a rotor of a motor according to a modification of the present embodiment.
Description of the reference numerals
10: A motor; 20: a rotor; 20A: a first rotor; 20B: a second rotor; 24: an inner core part; 25: a first outer core portion; 26: a second outer core part; 27: a first magnet; 28: a second magnet; 28A: a side magnet; 28B: a magnet on the other side; 30: a stator; 51: a first magnetic pole portion; 52: a second magnetic pole portion; c: a center line; j: a central axis; θ1: one side in the circumferential direction; θ2: and the other side in the circumferential direction.
Detailed Description
A motor 10 according to an embodiment of the present invention will be described with reference to the accompanying 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 the present embodiment, the axial direction is the up-down direction. The upper side (+Z) corresponds to one axial side, and the lower side (-Z) corresponds to the other axial side. The radial direction centered on the central axis J is simply referred to as "radial direction". The direction in the radial direction toward the center axis J is referred to as the radial inner side, and the direction away from the center axis J is referred to as the radial outer side. In addition, the circumferential direction centered on the central axis J is simply referred to as "circumferential direction". In the present embodiment, a predetermined rotational direction in the circumferential direction is referred to as a circumferential direction one side θ1, and a rotational direction opposite to the predetermined rotational direction is referred to as a circumferential direction other side θ2 when viewed in the axial direction as shown in fig. 3 and 4. Specifically, in a plan view of the rotor 20, a counterclockwise direction about the central axis J is referred to as a circumferential direction one side θ1, and a clockwise direction about the central axis J is referred to as a circumferential direction other side θ2. The vertical direction, the upper side, and the lower side are only names for explaining the relative positional relationship of the respective parts, and the actual arrangement relationship and the like may be other than the arrangement relationship and the like shown by these names.
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 positioned radially inward of the stator 30, a housing 11, and a plurality of bearings 15 and 16. 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 of the upper side of the peripheral wall 11 a. The bottom wall 11c closes the opening of the lower side of the peripheral wall 11 a. The bottom wall 11c holds the bearing 16. The bearing holding wall 11d is fixed to the peripheral wall 11 a. The bearing retaining wall portion 11d retains the bearing 15.
The rotor 20 is provided with a pair in an axial direction. A pair of rotors 20 are stacked in the axial direction. As shown in fig. 1 and 2, the pair of rotors 20 includes a first rotor 20A and a second rotor 20B disposed at a position different from 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 positioned at the radially outer end of the rotor core 22 and arranged in a 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 have a first magnet 27 and a second magnet 28. That is, the rotor 20 includes 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 has a cylindrical shape extending in the axial direction with the central axis J as the center. The shaft 21 may have a cylindrical shape. The shaft 21 is supported rotatably about the central axis J by a plurality of bearings 15, 16. The plurality of bearings 15, 16 are disposed at intervals in the axial direction and supported by the housing 11. That is, the shaft 21 is supported by the housing 11 via the 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), for example, iron, steel, stainless steel, or the like. The rotor core 22 is formed by stacking a plurality of electromagnetic steel plates in the axial direction. The rotor core 22 has an outer diameter larger than that of the shaft 21. The length of rotor core 22 in the axial direction is smaller than that of 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 axially located between the pair of bearings 15, 16.
As shown in fig. 3 and 4, the inner core portion 24 constitutes a radially inner portion in 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 weight reducing 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 24 a. The weight-reducing hole 24b penetrates the inner core portion 24 in the axial direction. The weight-reducing holes 24b are provided in plurality at intervals from each other in the circumferential direction. The plurality of weight-reducing holes 24b are arranged at equal intervals in the circumferential direction. According to the present embodiment, the weight reduction holes 24b can reduce the weight of the rotor 20, the material cost, and the like.
The first outer core portion 25 constitutes a part of a radially outer portion in the rotor core 22. The first outer core portion 25 is located radially outward of the inner core portion 24. The first outer core portion 25 protrudes radially outward from the inner core portion 24 at a part of the circumferential direction. The first outer core portions 25 are provided in plurality at intervals from each other in the circumferential direction. In the present embodiment, four first outer core portions 25 are provided on each rotor 20 at equal intervals in the circumferential direction.
The second outer core portion 26 constitutes a part of a radially outer portion in the rotor core 22. The second outer core portion 26 is located radially outward of the inner core portion 24 and is disposed at a position different from the first outer core portion 25 in the circumferential direction. The second outer core portion 26 is disposed at a position radially outward away from the inner core portion 24 at a part of the circumferential direction. The second outer core portions 26 are provided in plurality at intervals from each other in the circumferential direction. In the present embodiment, four second outer core portions 26 are provided on each rotor 20 at equal intervals in the circumferential direction. In each rotor 20, the first outer core portions 25 and the second outer core portions 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 integral with the inner core portion 24. In the present embodiment, the first outer core portion 25 is integral with the inner core portion 24. According to the present embodiment, the number of components of the rotor 20 can be reduced, and the manufacturing process and manufacturing cost of the motor 10 can be reduced. The structures other than those described above of the first outer core portion 25 and the second outer core portion 26 will be described 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 disposed radially outward of the first outer core portion 25. The first magnet 27 is disposed on the radially outer side surface of the rotor 20 and is exposed radially outward. 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 constituted by the first outer core portion 25 and the first magnet 27 arranged in the radial direction. That is, the rotor 20 has the first magnetic pole portion 51. The first magnetic pole 51 is a Surface magnet (Surface PERMANENT MAGNET: SPM) magnetic pole. The first magnetic pole portions 51 are provided in plurality at intervals from each other in the circumferential direction. In the present embodiment, four first magnetic pole portions 51 are provided at equal intervals in the circumferential direction on each rotor 20.
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 radially outer side surface 27a facing radially outward, a radially inner side surface 27b facing radially inward, and a first side surface 27c facing circumferentially. The radially outer side surface 27a has a convex curved surface that bulges radially outward. The radially inner side surface 27b is formed in a planar shape extending in a direction perpendicular to the radial direction. The first magnet 27 is provided with a pair of first side surfaces 27c. Each first side surface 27c is formed in 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 radially outer side surface 27a and a circumferential end of the radially inner side surface 27 b. According to the present embodiment, by providing the pair of first side surfaces 27c on the first magnet 27, formation of sharp corners at both circumferential end portions of the first magnet 27 is suppressed, so that corner defects of the first magnet 27 can be suppressed, and the structure of the first magnet 27 can be simplified.
As shown in fig. 3 and 4, the length of the first side surface 27c is 1mm or more in a cross-sectional view perpendicular to the central axis J. If the length of the first side surface 27c is 1mm or more, the corner defect of the first magnet 27 is more stably suppressed.
The second magnet 28 is disposed radially between the inner core portion 24 and the second outer core portion 26. The second magnet 28 and the second outer core portion 26 overlap each other when viewed from the radial direction. The second magnetic pole portion 52 is constituted by the second magnet 28 and the second outer core portion 26 arranged in the radial direction. That is, the rotor 20 has the second magnetic pole portion 52. The second magnetic pole 52 is a magnetic pole embedded in a magnet (inter PERMANENT MAGNET: IPM). The second magnetic pole portions 52 are provided in plurality at intervals from each other in the circumferential direction. In the present embodiment, four second magnetic pole portions 52 are provided at equal intervals in the circumferential direction on each rotor 20.
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 radially outer side surface 28a facing radially outward, a radially inner side surface 28b facing radially inward, and a second side surface 28c facing circumferentially. The second magnet 28 is provided with a plurality of second side surfaces 28c. Each second side surface 28c is connected to a circumferential end of the radially outer side surface 28a and a circumferential end of the radially inner side surface 28 b. The structure of the second magnet 28 other than the above will be described later.
As shown in fig. 2, the first magnetic pole portions 51 and the second magnetic pole portions 52 are alternately arranged in the circumferential direction. The first magnetic pole portion 51 of one of the pair of rotors 20 and the second magnetic pole portion 52 of the other are arranged in an axial direction, and the circumferential positions of the first magnetic pole portion and the second magnetic pole portion are the same. 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 identical to each other, and the circumferential position of the second magnetic pole portion 52 of the first rotor 20A and the circumferential position of the first magnetic pole portion 51 of the second rotor 20B are identical to each other.
More specifically, when viewed from the axial direction, the circumferential center portion of the first magnetic pole portion 51 of the first rotor 20A and the circumferential center portion of the second magnetic pole portion 52 of the second rotor 20B are arranged so as to overlap each other, and the circumferential center portion of the second magnetic pole portion 52 of the first rotor 20A and the circumferential center portion of the first magnetic pole portion 51 of the second rotor 20B are arranged so as to overlap each other. That is, in the present embodiment, the rotor 20 is not biased. In the present embodiment, when viewed from the axial direction, both ends in the circumferential direction of the first magnetic pole portion 51 of the first rotor 20A and both ends in the circumferential direction of the second magnetic pole portion 52 of the second rotor 20B are arranged so as to overlap each other, and both ends in the circumferential direction of the second magnetic pole portion 52 of the first rotor 20A and both ends in the circumferential direction of the first magnetic pole portion 51 of the second rotor 20B are arranged so as to overlap each other. It is not necessarily required that both ends in the circumferential direction of the first magnetic pole portion 51 of the first rotor 20A and both ends in the circumferential direction of the second magnetic pole portion 52 of the second rotor 20B are arranged so as to overlap each other when viewed from the axial direction, and both ends in the circumferential direction of the second magnetic pole portion 52 of the first rotor 20A and both ends 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, the rotor 20 is not biased, that is, the circumferential center portion of the first magnetic pole portion 51 of the first rotor 20A and the circumferential center portion of the second magnetic pole portion 52 of the second rotor 20B are arranged so as to overlap each other when viewed from the axial direction.
According to the present embodiment, 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 of the pair of rotors 20 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 resultant cogging torque, that is, the fluctuation width can be suppressed to be small. Therefore, the cogging torque of the motor 10 as a whole can be reduced without providing a skew. The manufacturing process of the motor 10 is reduced, and the productivity is improved. In addition, torque ripple can be caused to be in opposite phases. That is, the torque ripple generated in the first rotor 20A and the torque ripple generated in the second rotor 20B are generated in opposite phases to each other, and thus they cancel each other, so that the difference between the maximum value and the minimum value of the waveform of the resultant torque ripple, that is, the fluctuation width can be suppressed to be small. Therefore, according to the present embodiment, the cogging torque can be reduced while suppressing a torque reduction caused by applying a skew, and the torque ripple can be reduced. Further, vibration and noise generated by the motor 10 can be reduced.
As shown in fig. 3 and 4, the second magnet 28 has a portion that is located radially outward as being circumferentially distant from a center line C passing through the center of the second outer core portion 26 in the circumferential direction and the center axis J in a cross-sectional view perpendicular to the center axis J. Specifically, a portion of the second magnet 28 on one side θ1 in the circumferential direction (one side magnet 28A described later) and a portion of the second magnet on the other side θ2 in the circumferential direction (the other side magnet 28B described later) are located radially outward as they are away from the center line C in the circumferential direction. According to the present embodiment, since the magnetic flux extending from the radially outer side surface 28a of the second magnet 28 toward the stator 30 approaches the center line C as it goes radially outward, the magnetic flux of the second magnet 28 is easily concentrated at the circumferential center portion of the second outer core portion 26. This can suppress the fluctuation range of the waveform of the resultant cogging torque to be smaller. Vibration or noise of the motor 10 is further reduced, so that motor performance is improved.
In a cross-sectional view perpendicular to the central axis J, the second magnet 28 is arranged in a V-shape or a U-shape. In the present embodiment, the second magnet 28 is arranged in a V-shape or a U-shape that is open radially outward around the center line C in the cross-sectional view. Both end portions of the second magnet 28 in the circumferential direction are located radially outward of the central portion of the second magnet 28 in the circumferential direction. According to the present embodiment, the magnetic flux extending from the radially outer side surface 28a of the second magnet 28 to the stator 30 can be made to approach the center line C stably as it goes radially outward.
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, the second magnet 28 can be arranged in a V-shape or a U-shape, and the function as the second magnetic pole 52 of the embedded magnet can be ensured stably.
The second magnet 28 has one side magnet 28A located on one side θ1 in the circumferential direction from the center line C and the other side magnet 28B located on the other side θ2 in the circumferential direction from the center line C. That is, one second magnet 28 is constituted by 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 thereof face in the radial direction. The portion of the radially outer side surface 28A of the second magnet 28, which is disposed on the one side magnet 28A, is located radially outward away from the center line C toward the circumferential direction side θ1. The portion of the radially inner surface 28b of the second magnet 28, which is disposed on the one side magnet 28A, is located radially outward away from the center line C toward the circumferential direction side θ1.
The other side magnet 28B has a plate shape, and a pair of plate surfaces thereof face in the radial direction. The portion of the radially outer side surface 28a of the second magnet 28, which is disposed on the other side magnet 28B, is located radially outward away from the center line C as going to the other side θ2 in the circumferential direction. The portion of the radially inner side surface 28B of the second magnet 28, which is disposed on the other side magnet 28B, is located radially outward away from the center line C as going to the other side θ2 in the circumferential direction.
The one-side magnet 28A and the other-side magnet 28B are arranged in the circumferential direction. The one-side magnet 28A and the other-side magnet 28B are disposed 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 separate from each other. Therefore, the direction of the magnetic flux extending from the portion of one side magnet 28A to the stator 30 in the radial outer side surface 28A and the direction of the magnetic flux extending from the portion of the other side magnet 28B to the stator 30 are easily made different from each other. Each magnetic flux extending from one magnet 28A and the other magnet 28B toward the stator 30 can be made to approach the center line C stably as it goes radially outward. In addition, 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 the present embodiment, the one-side magnet 28A and the other-side magnet 28B can be made to be a common member (common article). Therefore, the management and assembly of the components are easy.
The N pole of one side magnet 28A faces one radial side and the S pole faces the other radial side. The other side magnet 28B has an N pole facing one radial side and an S pole facing the other radial side. 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 radially outer side, the other side in the radial direction corresponds to the radially inner side. 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 identical to each other in the radial direction, so the function of the second magnet 28 is stabilized.
The second outer core portion 26 has both end portions in the circumferential direction located radially outward of the central portion in the circumferential direction, of the radially inner side surface. In other words, the radially inner side surfaces of the second outer core portions 26 are located radially inward in the circumferential direction as going from the both end portions toward the center portion. According to the present embodiment, the radially outer side surface 28a of the second magnet 28 that contacts the radially inner side surface of the second outer core portion 26 is easily formed in a V shape, a U shape, or the like that opens radially outward. Therefore, the magnetic flux extending from the radially outer side surface 28a of the second magnet 28 to the stator 30 can be made to approach the center line C stably as it goes radially outward.
The first outer core portion 25 has a pedestal portion 25b. The pedestal portion 25b is located at a radially outer end portion of the first outer core portion 25. The pedestal portion 25b is in contact with the first magnet 27 from the radially inner side, and the circumferential dimension of the pedestal portion 25b becomes smaller toward the radially outer side. According to the present embodiment, the pedestal portion 25b of the first outer core portion 25 is distant from the circumferentially adjacent second magnet 28 as it goes radially outward. 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 greater than the circumferential dimension of the first magnet 27. In the present embodiment, the circumferential dimension of the radially outer end portion of the pedestal portion 25b is the same as the circumferential dimension of the radially inner end portion of the first magnet 27. According to the present embodiment, the radially inner surface 27b of the first magnet 27 can be stably supported over the entire circumferential direction by the pedestal portion 25b.
The groove 29 is recessed radially inward from the radially outer side surface of the rotor 20, and extends in the axial direction. In the present embodiment, the groove 29 extends over the entire axial length of the rotor 20, and opens at the upper end surface and the lower end surface of the rotor 20. The groove portions 29 are provided in plurality at intervals from each other in the circumferential direction. In the present embodiment, eight groove portions 29 are provided at equal intervals in the circumferential direction in each rotor 20.
The groove 29 is located between the first magnet 27 and the second magnet 28 adjacent in the circumferential direction. The groove 29 is disposed between the first magnetic pole 51 and the second magnetic pole 52 in the circumferential direction. The groove width in the circumferential direction of at least a part of the groove 29 decreases as going radially outward. In the present embodiment, the groove width in the circumferential direction of the radially inner end portion of the groove portion 29 becomes narrower as going radially outward. According to the present embodiment, the later-described holding portion 42 of the holder 40 disposed in the groove 29 is prevented from coming out of the groove 29 to the radial outside.
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 disposed in the groove portion 29. The holding portion 42 extends in the axial direction. The holding portions 42 are provided in plurality at intervals from each other in the circumferential direction. The number of holding portions 42 is the same as the number of groove portions 29. The holding portion 42 is in 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 first magnet 27 and the second magnet 28 are restrained from moving in the circumferential direction.
The holding portion 42 is in contact with the first magnet 27 and the second outer core portion 26 from the radially outer side. The holding portion 42 presses the first magnetic pole portion 51 and the second magnetic pole portion 52 from the radially outer side. According to the present embodiment, the movement of the first magnet 27, the second magnet 28, and the second outer core portion 26 to the radial outside is suppressed by the holding portion 42. This stably increases the rotational strength of the rotor 20 when rotating.
As shown in fig. 1, the connection portion 43 is disposed on an end surface of the rotor 20 in the axial direction. In the present embodiment, the connection portions 43 are provided on the upper end surface of the first rotor 20A and the lower end surface of the second rotor 20B, respectively. The connection portion 43 extends in the circumferential direction. The connection portion 43 is, for example, annular with the central axis J as the center. The connecting portion 43 is connected to an axial end 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 part of one member.
The stator 30 and the rotor 20 are opposed to each other with a gap therebetween in the radial direction. The stator 30 surrounds the rotor 20 over the entire circumferential range from the radially outer side. The stator 30 includes a stator core 31, an insulator 32, and a coil 33.
Stator core 31 has a ring shape centered on 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 radially outer side. Although not particularly shown, stator core 31 is composed of a plurality of electromagnetic steel plates stacked in the axial direction. Stator core 31 is fixed to the inner peripheral surface of case 11. The stator core 31 and the housing 11 are fixed by, for example, press-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 radially outer surface of core back 31a is fixed to the inner circumferential surface of circumferential wall 11a. Specifically, the core back 31a is fixed to the peripheral wall 11a in a state where the radially outer side surface of the core back 31a is in contact with the inner peripheral surface of the peripheral wall 11a. The teeth 31b protrude radially inward from the radially inner surface of the core back 31 a. The plurality of teeth 31b are arranged at intervals in the circumferential direction. In the present embodiment, the plurality of teeth 31b are arranged at equal intervals in the circumferential direction. The radially inner side surface of each tooth 31b faces the radially outer side surface of the rotor 20 with a gap therebetween.
The insulator 32 is mounted 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 annularly arranged around the central axis J.
The coil 33 is mounted on the stator core 31 via an insulator 32. The coils 33 are provided in plurality in a circumferential direction. The number of coils 33 is the same as the number of teeth 31 b. Each coil 33 is mounted on each tooth 31b via an insulator 32. The coil 33 is formed by winding a wire around the teeth 31b via a part of the insulator 32.
The motor 10 of the present 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 coil 33 of the U-phase, V-phase, and W-phase is constituted by any one of the first wire, the second wire, and the third wire.
Next, an example of a device mounted with the motor 10 of the present embodiment will be described. In the present embodiment, an example in which the motor 10 is mounted in the electric power steering apparatus 100 will be described.
As shown in fig. 5, the electric power steering apparatus 100 is mounted on a steering mechanism of a wheel of an automobile. The electric power steering device 100 is a device that reduces steering force by hydraulic pressure. 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 an input from the steering 111 to an axle 113 having wheels 112. The oil pump 116 generates hydraulic pressure in the power cylinder 115. The power cylinder 115 transmits a driving force based on hydraulic pressure to the axle 113. The control valve 117 controls the oil of the oil pump 116. In the electric power steering device 100, the motor 10 is mounted as a drive source for the oil pump 116.
The electric power steering apparatus 100 of the present embodiment includes the motor 10 of the present embodiment. Accordingly, the electric power steering apparatus 100 that achieves the same effects as the motor 10 described above is obtained.
The present invention is not limited to the above-described embodiments, and, for example, as described below, structural changes and the like can be made without departing from the scope of the present invention.
Fig. 6 shows a modification of the motor 10 described in the above 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 one side magnet 28A, the 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, in this cross-sectional view, the intermediate magnet 28C is located on the center line C. The side magnets 28A and the intermediate magnets 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 disposed apart from each other in the circumferential direction. The intermediate magnet 28C has a plate shape, and a pair of plate surfaces thereof face in the radial direction. The portion of the radially outer side surface 28a of the second magnet 28, which is disposed in the intermediate magnet 28C, is in a planar shape extending in a direction perpendicular to the radial direction. The portion of the radially inner surface 28b of the second magnet 28, which is disposed in the intermediate magnet 28C, is in a planar shape extending in a 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). The intermediate magnet 28C has the same N pole facing one side in the radial direction and the S pole facing the other side in the radial direction as the one-side magnet 28A and the other-side magnet 28B. In this modification, the same operational effects as those of the above embodiment are obtained.
In the above embodiment, the radially inner side surface 27b of the first magnet 27 is planar, and the radially outer side surface 25a of the first outer core portion 25 is planar, and the radially outer side surfaces are in contact with each other, but the present invention is not limited thereto. Fig. 7 shows a modification of the motor 10 described in the above embodiment. In this modification, as shown in fig. 7, the radially outer side surface 25a of the first outer core portion 25 has a convex curved surface shape bulging radially outward, and the radially inner side surface 27b of the first magnet 27 has a concave curved surface shape recessed radially outward, and they are in contact with each other. In this case, the radially outer side surface 27a and the radially inner side surface 27b of the first magnet 27 are curved surfaces protruding radially outward. That is, the first magnet 27 has an arcuate shape protruding radially outward when viewed from the axial direction.
In the above embodiment, the motor 10 is mounted in the electric power steering apparatus 100, but the present invention is not limited to this. The motor 10 may be used for, for example, a pump, a brake, a clutch, a vacuum cleaner, a dryer, a ceiling fan, a washing machine, a refrigerator, and the like.
The configurations described in the above embodiments, modifications, and the like may be combined, and the configurations may be added, omitted, replaced, and other modifications without departing from the spirit of the present invention. The present invention is not limited to the above embodiments, but is limited only by the claims.
Claims (8)
1. A motor, comprising:
A cylindrical stator; and
A pair of rotors which are located radially inward of the stator and rotate about a central axis, and which are stacked in the axial direction,
The rotor has:
an inner core part;
a first outer core portion located radially outward of the inner core portion;
A second outer core portion located radially outward of the inner core portion and disposed at a position different from the first outer core portion in the circumferential direction;
a first magnet disposed radially outward of the first outer core portion; and
A second magnet disposed radially between the inner core portion and the second outer core portion,
The second magnet has a portion located radially outward as being away from a center line passing through a center of a circumference of the second outer core portion and the center axis in a circumferential direction in a cross-sectional view perpendicular to the center axis, a magnetic flux extending from a radially outer side surface of the second magnet toward the stator approaches the center line as being directed radially outward,
A first magnetic pole portion constituted by the first outer core portion and the first magnet arranged in the radial direction and a second magnetic pole portion constituted by the second magnet and the second outer core portion arranged in the radial direction are alternately arranged in the circumferential direction, the shapes of the first magnetic pole portion and the second magnetic pole portion are different,
The first magnetic pole portion of one of the pair of rotors and the second magnetic pole portion of the other are arranged in an axial direction, and the circumferential positions of the first magnetic pole portion and the second magnetic pole portion are the same.
2. The motor according to claim 1, wherein,
In a cross-sectional view perpendicular to the central axis, the second magnet is arranged in a V-shape or a U-shape.
3. The motor according to claim 1 or 2, wherein,
The second magnet has circumferential ends located radially outward of a circumferential center portion of the second magnet.
4. The motor according to claim 1 or 2, wherein,
The second magnet has circumferential ends located radially inward of the circumferential ends of the first magnet.
5. The motor according to claim 1 or 2, wherein,
The second outer core portion has both end portions in the circumferential direction located radially outward of the central portion in the circumferential direction.
6. The motor according to claim 1 or 2, wherein,
The second magnet has:
A side magnet located on a side of the center line in the circumferential direction; and
A magnet on the other side located on the other side in the circumferential direction from the center line,
The one-side magnet and the other-side magnet are disposed apart from each other in the circumferential direction.
7. The motor according to claim 6, wherein,
The one side magnet is plate-shaped,
The magnet at the other side is plate-shaped,
The one side magnet and the other side magnet have the same shape as each other.
8. The motor according to claim 6, wherein,
The N pole of the magnet at one side faces to one radial side, the S pole faces to the other radial side,
The N pole of the magnet on the other side faces to one radial side, and the S pole faces to the other radial side.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020063571A JP2021164262A (en) | 2020-03-31 | 2020-03-31 | motor |
| JP2020-063571 | 2020-03-31 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113472169A CN113472169A (en) | 2021-10-01 |
| CN113472169B true CN113472169B (en) | 2024-05-24 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110324086.3A Active CN113472169B (en) | 2020-03-31 | 2021-03-26 | Motor with a motor housing |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2021164262A (en) |
| CN (1) | CN113472169B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013153637A (en) * | 2011-12-26 | 2013-08-08 | Asmo Co Ltd | Rotor and motor |
| JP2016082777A (en) * | 2014-10-20 | 2016-05-16 | アスモ株式会社 | motor |
| CN107852051A (en) * | 2015-07-21 | 2018-03-27 | 阿斯莫株式会社 | Motor |
| WO2019069539A1 (en) * | 2017-10-06 | 2019-04-11 | 日本電産株式会社 | Rotor, motor, and electric power steering device |
-
2020
- 2020-03-31 JP JP2020063571A patent/JP2021164262A/en active Pending
-
2021
- 2021-03-26 CN CN202110324086.3A patent/CN113472169B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013153637A (en) * | 2011-12-26 | 2013-08-08 | Asmo Co Ltd | Rotor and motor |
| JP2016082777A (en) * | 2014-10-20 | 2016-05-16 | アスモ株式会社 | motor |
| CN107852051A (en) * | 2015-07-21 | 2018-03-27 | 阿斯莫株式会社 | Motor |
| WO2019069539A1 (en) * | 2017-10-06 | 2019-04-11 | 日本電産株式会社 | Rotor, motor, and electric power steering device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2021164262A (en) | 2021-10-11 |
| CN113472169A (en) | 2021-10-01 |
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