JP2012222867A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor of which the axial dimension is suppressed and which enables highly accurate positioning of magnets in the circumferential direction.SOLUTION: A magnet holder 32A includes a positioning plate 82A having a plurality of projections 821A projecting from faces on radial inner sides of magnets 33A to radial outer sides, and the plurality of magnets 33A are disposed in circumferential positions defined by the plurality of projections 821A. Thus, the magnets 33A are highly accurately positioned in the circumferential direction and a counter-electromotive force waveform of the motor is stabilized.

Description

  The present invention relates to an inner rotor type motor.

2. Description of the Related Art Conventionally, an inner rotor type motor that rotates a rotating unit having a magnet inside a coil is known. For example, Japanese Patent Application Laid-Open No. 2006-109575 describes a brushless motor including a rotor having a magnet and a stator disposed on the outer peripheral side of the rotor. Japanese Patent Application Laid-Open No. 2009-261191 describes a motor including a stator fixed inside a motor housing and a rotor having a plurality of segment magnets arranged to face the inner surface of the stator core. ing.
JP 2006-109575 A JP 2009-261191 A

  In Japanese Patent Application Laid-Open No. 2006-109575, a magnet is fitted on the outer peripheral surface of the yoke (paragraph 0049). However, when attaching a plurality of magnets to the outer peripheral surface of the yoke disclosed in Japanese Patent Application Laid-Open No. 2006-109575, it is difficult to determine the circumferential position of each magnet because adjacent magnets attract each other. When the yoke is a press-molded product, it is difficult to provide the yoke with a shape for positioning the magnet in the circumferential direction.

  If the circumferential positions of the plurality of magnets are shifted, variations in the circumferential magnetic poles will vary. The variation in magnetic poles is a factor that disturbs the back electromotive force waveform during motor operation. When the back electromotive force waveform is disturbed, the electrical characteristics of the motor deteriorate. In addition, since torque pulsation occurs, vibration and noise may occur.

  On the other hand, Japanese Patent Application Laid-Open No. 2009-261191 describes that a boundary projection for locking a segment magnet is provided on a rotor yoke (claim 1 and the like). However, in Japanese Patent Application Laid-Open No. 2009-261191, bearings for supporting the shaft are arranged above and below the prismatic rotor yoke (paragraphs 0015 and 0022, FIG. 1). With such a structure, it is difficult to suppress the axial dimension of the motor.

  In particular, the rotor yoke disclosed in JP 2009-261191 is a laminate of a plurality of steel plates (paragraph 0015). Conventionally, it has been difficult to stack a plurality of steel plates so as to form a covered cylindrical yoke as disclosed in JP-A-2006-109575. That is, it has been a problem accompanied by technical difficulties to achieve both the reduction of the dimension of the motor in the axial direction and the positioning of the magnet with high accuracy in the circumferential direction by making the yoke a covered cylinder.

  An object of the present invention is to provide a motor capable of suppressing the axial dimension of the motor and positioning the circumferential position of the magnet with high accuracy, thereby stabilizing the back electromotive force waveform of the motor. is there.

  An exemplary first invention of the present application includes a stationary portion and a rotating portion that rotates about a central axis that extends vertically, and the rotating portion includes a shaft that is disposed along the central axis, and the shaft. And a magnet holder having a cylindrical portion extending downward from an outer peripheral portion of the lid portion, and a plurality of magnets fixed to an outer peripheral surface of the magnet holder, and the stationary portion Holds a coil disposed outside the magnet in the radial direction, a stator core having a plurality of teeth serving as a magnetic core of the coil, a bearing portion that rotatably supports the shaft, and the stator core and the bearing portion. And the bearing portion is disposed on the radially inner side of the cylindrical portion, and the magnet holder projects radially outward from the radially inner surface of the magnet. Includes a positioning plate having a plurality of protruding portions, the plurality of magnets is a motor disposed in the circumferential position defined by the plurality of protrusions.

  According to the exemplary first invention of the present application, the axial position of the magnet and the axial position of the bearing portion can be overlapped. For this reason, the dimension of the axial direction of a motor can be controlled. The magnet can be positioned with high accuracy in the circumferential direction by the plurality of protrusions. For this reason, the back electromotive force waveform of the motor can be stabilized.

FIG. 1 is a longitudinal sectional view of a motor. FIG. 2 is a longitudinal sectional view of the motor. FIG. 3 is a top view of the magnet holder and the rotor magnet. FIG. 4 is a bottom view of the magnet holder and the rotor magnet. FIG. 5 is a longitudinal sectional view of the magnet holder and the rotor magnet. FIG. 6 is a diagram conceptually showing a state in which the electromagnetic steel plate constituting the stator core and the electromagnetic steel plate constituting the magnet holder are obtained from the same electromagnetic steel plate. FIG. 7 is a longitudinal sectional view of the motor.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the following, the shape and positional relationship of each part will be described with the direction along the central axis of the motor as the vertical direction and the bearing side on the lid part of the magnet holder as the bottom. However, this defines the vertical direction for the convenience of explanation, and does not limit the posture when the motor according to the present invention is used.

<1. First Embodiment>
FIG. 1 is a longitudinal sectional view of a motor 1A according to a first embodiment of the present invention. As shown in FIG. 1, the motor 1A includes a stationary part 2A and a rotating part 3A. The rotating part 3A rotates around a central axis 9A that extends vertically.

  The rotating unit 3A includes a shaft 31A, a magnet holder 32A, and a plurality of magnets 33A. The shaft 31A is disposed along the central axis 9A. The magnet holder 32A includes a lid portion 321A fixed to the shaft 31A and a cylindrical portion 322A extending downward from the outer peripheral portion of the lid portion 321A. The magnet 33A is fixed to the outer peripheral surface of the magnet holder 32A.

  The stationary part 2A includes a case 21A, a stator core 22A, a coil 23A, and a bearing part 27A. The coil 23A is disposed on the outer side in the radial direction of the magnet 33A. The stator core 22A has a plurality of teeth 222A that serve as the magnetic core of the coil 23A. The bearing portion 27A is a mechanism for rotatably supporting the shaft 31A. The case 21A holds the stator core 22A and the bearing portion 27A.

  As shown in FIG. 1, the bearing portion 27A is disposed on the radially inner side of the cylindrical portion 322A of the magnet holder 32A. For this reason, the axial position of the magnet 33A and the axial position of the bearing portion 27A can be overlapped. Thereby, the dimension of the axial direction of the motor 1A can be suppressed.

  The magnet holder 32A includes a positioning plate 82A having a plurality of protrusions 821A. The protruding portion 821A protrudes radially outward from the radially inner surface of the magnet 33A. The plurality of magnets 33A are disposed at circumferential positions defined by the plurality of protrusions 821A. Accordingly, the plurality of magnets 33A are positioned with high accuracy in the circumferential direction. As a result, the back electromotive force waveform of the motor 1A is stabilized.

<2. Second Embodiment>
<2-1. Overall configuration of motor>
Subsequently, a second embodiment of the present invention will be described.

  The motor of this embodiment is mounted on household appliances, such as an air conditioner and a refrigerator, and is used as a drive source of a fan or a pump, for example. However, the motor of the present invention may be a motor used for other known applications. For example, the motor of the present invention may be mounted on OA equipment, medical equipment, automobiles, etc., and generate various driving forces. Hereinafter, a device on which the motor 1 is mounted is referred to as a “drive device”.

  FIG. 2 is a longitudinal sectional view of the motor 1 according to the present embodiment. As shown in FIG. 2, the motor 1 includes a stationary part 2 and a rotating part 3. The stationary part 2 is fixed to the frame of the drive device. The rotating unit 3 is supported so as to be rotatable with respect to the stationary unit 2.

  The stationary portion 2 of the present embodiment includes a case 21, a stator core 22, a coil 23, an upper insulating member 24, a lower insulating member 25, a circuit board 26, and a bearing portion 27.

  The case 21 is a metal member that holds the stator core 22 and the bearing portion 27. The case 21 has a bottom portion 211, an outer cylindrical portion 212, an inner cylindrical portion 213, and an annular protrusion 214. The bottom portion 211 is a substantially flat portion extending in the radial direction (a direction orthogonal to the central axis; the same applies hereinafter) below the coil 23. The outer cylindrical portion 212 is a substantially cylindrical portion that extends upward from the outer peripheral portion of the bottom portion 211. The inner cylindrical portion 213 is a substantially cylindrical portion that extends upward on the radially inner side of the bottom portion 211. The annular protrusion 214 is a portion protruding downward from the bottom portion 211 between the bottom portion 211 and the inner cylindrical portion 213. When the motor 1 is attached to the drive device, the annular protrusion 214 is fitted into the frame of the drive device.

  The case 21 of this embodiment is obtained by pressing an alloy plate containing iron as a main component. Press work is more suitable for mass production than other methods such as casting and cutting. However, the case of the present invention may be obtained by other methods.

  The stator core 22 and the coil 23 are parts that function as an armature of the motor 1. The stator core 22 is made of a laminated steel plate in which electromagnetic steel plates such as silicon steel plates are laminated in the axial direction (the direction along the central axis 9; the same applies hereinafter). The stator core 22 includes an annular core back 221 and a plurality of teeth 222 that protrude radially inward from the core back 221. The core back 221 is held by the outer cylindrical portion 212 of the case 21.

  The coil 23 is configured by a conductive wire wound around the teeth 222. When a drive current is applied to the coil 23, a radial magnetic flux is generated in the teeth 222, which is a magnetic core. And the torque of the circumferential direction generate | occur | produces by the effect | action of the magnetic flux between the teeth 222 and the rotor magnet 33 by the side of the rotation part 3. FIG. As a result, the rotating unit 3 rotates about the central axis 9 with respect to the stationary unit 2.

  The upper insulating member 24 and the lower insulating member 25 are resin members that electrically insulate the stator core 22 and the coil 23 from each other. The upper insulating member 24 is disposed on the upper side of the stator core 22. The lower insulating member 25 is disposed below the stator core 22. In other words, the stator core 22 is sandwiched between the upper insulating member 24 and the lower insulating member 25.

  The upper insulating member 24 and the lower insulating member 25 are interposed between the tooth 222 and the coil 23 and have a portion that electrically insulates the tooth 222 and the coil 23 from each other. Further, the upper insulating member 24 has an annular portion 241 that is continuous in the circumferential direction on the radially outer side of the coil 23. A plurality of fixing pins 242 for fixing the circuit board 26 are provided on the upper surface of the annular portion 241.

  The circuit board 26 is a board on which an electronic circuit for applying a driving current to the coil 23 is mounted. The circuit board 26 is fixed to the upper surface of the annular portion 241 of the upper insulating member 24. Specifically, the fixing pin 242 of the upper insulating member 24 is inserted into the through hole provided in the circuit board 26, and the upper end portion of the fixing pin 242 is welded to the upper surface of the circuit board 26. A magnetic sensor 261 for detecting the number of rotations of the rotating unit 3 is provided on the lower surface of the circuit board 26. For the magnetic sensor 261, for example, a Hall element is used.

  The bearing portion 27 is a mechanism for rotatably supporting the shaft 31 on the rotating portion 3 side. The bearing portion 27 is held by the inner cylindrical portion 213 of the case 21. For the bearing portion 27, for example, a ball bearing that relatively rotates an outer ring and an inner ring via a sphere is used. However, another type of bearing such as a slide bearing or a fluid bearing may be used for the bearing portion 27.

  The rotating unit 3 according to the present embodiment includes a shaft 31, a magnet holder 32, a plurality of rotor magnets 33, and a sensor magnet 34.

  The shaft 31 is a substantially cylindrical member that extends in the vertical direction along the central axis 9. The shaft 31 rotates about the central axis 9 while being supported by the bearing portion 27 described above. The lower end portion of the shaft 31 protrudes downward from the case 21. Further, the upper end portion of the shaft 31 protrudes above the circuit board 26. A lower end portion or an upper end portion of the shaft 31 is connected to a drive unit of the drive device via a power transmission mechanism such as a gear.

  The magnet holder 32 is a member that rotates together with the shaft 31 on the radially inner side of the stator core 22 and the coil 23. The magnet holder 32 has a lid part 321 and a cylindrical part 322. The lid portion 321 is a portion that extends in the radial direction above the bearing portion 27. The inner peripheral portion of the lid portion 321 is fixed to the outer peripheral surface of the shaft 31. The cylindrical portion 322 is a substantially cylindrical portion that extends downward from the outer peripheral portion of the lid portion 321.

  The plurality of rotor magnets 33 are fixed to the outer peripheral surface of the cylindrical portion 322 of the magnet holder 32. A radially outer surface of each rotor magnet 33 is a magnetic pole surface facing the stator core 22 and the coil 23. The plurality of rotor magnets 33 are arranged at equal intervals in the circumferential direction so that N-pole magnetic pole faces and S-pole magnetic pole faces are alternately arranged.

  The sensor magnet 34 is fixed to the upper surface of the lid portion 321 of the magnet holder 32. The sensor magnet 34 has magnetic poles arranged at a finer pitch than the rotor magnet 33. During the operation of the motor 1, the magnetic sensor 261 of the circuit board 26 described above detects the magnetic pole of the sensor magnet 34. The circuit board 26 receives the detection signal from the magnetic sensor 261 and controls the drive current to the coil 23 while accurately detecting the rotational speed of the rotating unit 3.

<2-2. About the installation mode of the bearing part>
As described above, the motor 1 includes the substantially cylindrical magnet holder 32 with a lid. And the bearing part 27 is arrange | positioned under the cover part 321 of the said magnet holder 32, and the radial inside of the cylindrical part 322. As shown in FIG. The bearing portion 27, the cylindrical portion 322 of the magnet holder 32, and the rotor magnet 33 of this embodiment are arranged so that their axial positions overlap each other. Thereby, the axial direction dimension of the motor 1 is suppressed. The bearing portion 27 supports the shaft 31 at a height position close to the center of gravity of the magnet holder 32.

  Assuming that bearing portions are provided at two locations, the upper position and the lower position of the magnet holder 32, and the upper and lower bearing portions are held by separate members, due to processing errors and assembly errors between the members, An inclination of the shaft 31 may occur. On the other hand, in the present embodiment, the bearing portion 27 is disposed only on the lower side of the lid portion 321. And the bearing part 27 is supported by case 21 which is a single member. For this reason, the inclination of the shaft 31 hardly occurs.

  Moreover, in this embodiment, the stator core 22 and the bearing part 27 are hold | maintained at case 21 which is a single member. For this reason, the coaxiality of the stator core 22 and the bearing part 27 can be improved compared with the case where the stator core 22 and the bearing part 27 are held by separate members. Therefore, the coaxiality between the stator core 22 and the rotor magnet 33 can also be improved.

  If the coaxiality between the stator core 22 and the rotor magnet 33 is improved, the back electromotive force waveform during operation of the motor 1 is stabilized. If it does so, the pulsation of a torque will be suppressed and the vibration and noise of the motor 1 will be reduced.

<2-3. Detailed structure of magnet holder>
Next, a more detailed structure of the magnet holder 32 will be described. FIG. 3 is a top view of the magnet holder 32 and the plurality of rotor magnets 33. FIG. 4 is a bottom view of the magnet holder 32 and the plurality of rotor magnets 33. FIG. 5 is a longitudinal sectional view of the magnet holder 32 and the rotor magnet 33 as viewed from the VV position in FIGS. 3 and 4.

  The magnet holder 32 of the present embodiment is made of a laminated steel plate in which a plurality of electromagnetic steel plates are laminated in the axial direction. For example, a silicon steel plate is used as the electromagnetic steel plate. The plurality of electromagnetic steel plates include a plurality of first steel plates 41 constituting the lid portion 321 and a plurality of second steel plates 42 constituting the cylindrical portion 322. A first circular hole 412 for inserting the shaft 31 is provided at the center of the first steel plate 41. In the center of the second steel plate 42, a second circular hole 422 larger than the first circular hole is provided.

  If a cylindrical magnet holder with a lid is produced by press working, a curved surface is generated at the boundary between the upper surface of the lid and the outer peripheral surface of the cylindrical portion. On the other hand, if the magnet holder 32 is made of a laminated steel plate as in the present embodiment, a curved surface similar to that of press working does not occur between the upper surface of the lid portion 321 and the outer peripheral surface of the cylindrical portion 322.

  For this reason, in the magnet holder 32 which consists of laminated steel plates, the plane part for arrange | positioning the sensor magnet 34 on the upper surface of the cover part 321 can be ensured more widely. Therefore, the sensor magnet 34 can be more stably disposed on the upper surface of the lid portion 321. As a result, the inclination of the sensor magnet 34 with respect to the central axis 9 is reduced.

  Similarly, in the magnet holder 32 made of laminated steel plates, a wider contact surface with the rotor magnet 33 can be secured on the outer peripheral surface of the cylindrical portion 322. For this reason, the part used as the back yoke of the rotor magnet 33 can be expanded.

  Further, if the magnet holder 32 is made of a laminated steel plate, the radial thickness of the cylindrical portion 322, that is, the radial dimension of the second steel plate 42 can be arbitrarily set. For this reason, the radial thickness of the cylindrical portion 322 can be freely designed as compared with the case where the magnet holder is manufactured by press working. For example, it is easy to increase the radial thickness of the cylindrical portion 322 and to enlarge the portion that becomes the back yoke of the rotor magnet 33.

  If the part which becomes the back yoke of the rotor magnet 33 is enlarged, the iron loss of the motor 1 is reduced. As a result, the back electromotive force during operation of the motor 1 is increased, and energy efficiency is improved.

  As shown in FIGS. 3 and 5, a plurality of first protrusions 411 protruding outward in the radial direction are provided on the outer periphery of the first steel plate 41. The plurality of first protrusions 411 are arranged at equal intervals in the circumferential direction. The number of first protrusions 411 included in one first steel plate 41 matches the number of rotor magnets 33. The radially outer end of the first protrusion 411 is located radially outward from the radially inner surface of the rotor magnet 33 fixed to the magnet holder 32.

  As shown in FIGS. 4 and 5, among the plurality of second steel plates 42, a plurality of second steel plates 42 arranged at the lowermost portion have a plurality of protrusions projecting outward in the radial direction. A second protrusion 421 is provided. The plurality of second protrusions 421 are provided at positions below each of the plurality of first protrusions 411. Therefore, the plurality of second protrusions 421 are also arranged at equal intervals in the circumferential direction. The number of second protrusions 421 included in one second steel plate 42 matches the number of rotor magnets 33. The radially outer end of the second protrusion 421 is located radially outward from the radially inner surface of the rotor magnet 33 fixed to the magnet holder 32.

  The upper part of each rotor magnet 33 is arrange | positioned between a pair of 1st protrusion parts 411 adjacent to the circumferential direction. Moreover, the lower part of each rotor magnet 33 is arrange | positioned between a pair of 2nd protrusion parts 421 adjacent to the circumferential direction. As described above, the plurality of rotor magnets 33 are arranged at circumferential positions defined by the plurality of protrusions 411 and 421. That is, in this embodiment, the 1st steel plate 41 which has the 1st protrusion part 411, and the 2nd steel plate 42 which has the 2nd protrusion part 421 function as a positioning plate which positions the rotor magnet 33 in the circumferential direction. Yes.

  When the motor 1 is manufactured, the circumferential position of each rotor magnet 33 can be easily and accurately positioned using the first protrusion 411 and the second protrusion 421. In particular, even when the rotor magnets 33 that are pre-magnetized are arranged, the rotor magnets 33 can be positioned while preventing the adjacent rotor magnets 33 from being attracted by a magnetic force. If the plurality of rotor magnets 33 are accurately positioned in the circumferential direction, the back electromotive force waveform during the operation of the motor 1 is stabilized. If it does so, the pulsation of a torque will be suppressed and the vibration and noise of the motor 1 will be reduced. Moreover, the shift | offset | difference of the gravity center of the rotation part 3 is also suppressed.

  In the present embodiment, the first protrusion 411 is provided near the upper end of the outer peripheral surface of the magnet holder 32. A second protrusion 421 is provided near the lower end of the outer peripheral surface of the magnet holder 32. The magnet holder 32 has a body portion 323 that is not provided with a protrusion at an axial position between the first protrusion 411 and the second protrusion 421. The trunk | drum 323 of this embodiment is comprised with the several 2nd steel plate 42 which does not have a protrusion part.

  If a protrusion is continuously provided from the upper end to the lower end of the outer peripheral surface of the magnet holder 32, the magnetic flux that wraps around the protrusion increases. On the other hand, in the structure of the present embodiment, a space without a protruding portion is ensured between the adjacent rotor magnets 33 and on the radially outer side of the trunk portion 323. For this reason, the said space becomes a flux barrier and the magnetic flux which goes around to a protrusion part is suppressed. As a result, the switching of the magnetic flux in the circumferential direction becomes clear, and the magnetic characteristics of the motor 1 are improved.

  Moreover, the outer peripheral surface of the trunk | drum 323 is a cylindrical surface without an unevenness | corrugation. For this reason, an adhesive for fixing the rotor magnet 33 can be easily applied to the outer peripheral surface of the body portion 323. When applying the adhesive, an adhesive nozzle is brought close to the outer peripheral surface of the body 323. Then, while rotating the magnet holder 32 around the central axis 9, the adhesive is discharged from the nozzle to the outer peripheral surface of the body portion 323. In this way, the adhesive can be applied quickly without bringing the tip of the nozzle into contact with the protrusions 411 and 421.

  Note that the axial position of the protrusion is not limited to the example of this embodiment. For example, the protruding portion may be provided only in one of the upper position and the lower position of the trunk portion 323. Moreover, the protrusion part may be provided in axial direction positions other than an upper end part and a lower end part. In this embodiment, the whole magnet holder 32 consists of laminated steel plates. For this reason, a protrusion part can be provided in the magnetic steel sheet arrange | positioned in arbitrary axial direction positions. Further, the protruding portion may be provided continuously from the upper end portion to the lower end portion of the outer peripheral surface of the magnet holder 32.

  When producing the magnet holder 32, first, each steel plate is laminated | stacked one by one inside a predetermined metal mold | die, stamping out the 1st steel plate 41 and the 2nd steel plate 42 from a flat steel plate. Subsequently, the plurality of steel plates are fixed to each other by caulking a plurality of portions of the laminated steel plates in the axial direction. Thereafter, the magnet holder 32 made of a laminated steel plate is taken out from the mold.

  The magnet holder 32 has a plurality of first caulking portions 51 and a plurality of second caulking portions 52 formed by the above caulking step. The plurality of first steel plates 41 constituting the lid portion 321 are fixed to each other by the first caulking portion 51. The plurality of second steel plates 42 constituting the cylindrical portion 322 are fixed to each other by the second caulking portion 52. The plurality of first caulking portions 51 and the plurality of second caulking portions 52 are arranged at equal intervals in the circumferential direction, respectively.

  The plurality of first steel plates 41 are provided with a plurality of through holes 53 at positions overlapping the second caulking portion 52 in plan view. The upper end portion of the second caulking portion 52 is fitted to the lower portion of the through hole 53. As a result, the lowermost first steel plate 41 and the uppermost second steel plate 42 are fixed.

  When the magnet holder 32 is disposed inside the mold, a stress directed radially inward from the side of the mold acts on the first steel plate 41 and the second steel plate 42. Since the first steel plate 41 and the second steel plate 42 have different sizes of circular holes provided in the center, the amount of strain inward in the radial direction due to the stress differs between the first steel plate 41 and the second steel plate 42. .

  Here, if the caulking portion is formed over both the first steel plate 41 and the second steel plate 42 without providing the through hole 53 in the first steel plate 41, the first steel plate 41 and the second steel plate 42 are formed. It is fixed in a state where the strain amount is different. Then, when the magnet holder 32 is taken out from the mold, there is a possibility that a problem such as remaining bending in the cylindrical portion 322 may occur.

  On the other hand, in this embodiment, the through-hole 53 is formed in the 1st steel plate 41 previously, and the 2nd crimping part 52 is formed in the position which overlaps with the said through-hole 53 in planar view after that. That is, the through hole 53 of the first steel plate 41 and the second caulking portion 52 of the second steel plate 42 are formed separately. Thereby, it is prevented that the 1st steel plate 41 and the 2nd steel plate 42 are fixed in the state from which distortion amount differs.

  When the difference in strain is within an allowable range, a caulking portion is formed over both the first steel plate 41 and the second steel plate 42 without providing the through hole 53 in the first steel plate 41. May be.

  Since the caulking portions 51 and 52 and the through hole 53 prevent the flow of magnetic flux in the radial direction and the circumferential direction, they can be a factor for reducing the magnetic path in the magnet holder 32. However, in the present embodiment, the plurality of first caulking portions 51 are provided at the same circumferential position as the protruding portions 411 and 421. A part of the second caulking portion 52 and the through hole 53 are also provided at the same circumferential position as the protruding portions 411 and 421. At the circumferential position, the magnetic path is expanded by the protrusions 411 and 421. As a result, the reduction of the magnetic path caused by the first caulking portion 51 and the second caulking portion 52 is compensated.

  The stator core 22 and the magnet holder 32 of the present embodiment are both made of laminated steel plates. Further, the stator core 22 and the magnet holder 32 do not overlap each other in plan view. For this reason, as shown in FIG. 6, the electromagnetic steel plate 61 constituting the stator core 22 and the first steel plate 41 or the second steel plate 42 constituting the magnet holder 32 can be punched from the same electromagnetic steel plate 71.

  In this case, electromagnetic steel plates of the same material and the same thickness are used for the stator core 22 and the magnet holder 32. In this way, resources can be used effectively and the amount of waste can be reduced. As a result, the manufacturing cost of the motor 1 can be suppressed and the burden on the environment can be reduced.

<3. Third Embodiment>
Subsequently, a third embodiment of the present invention will be described focusing on differences from the second embodiment. FIG. 7 is a longitudinal sectional view of a motor 1B according to the third embodiment. The motor 1B of FIG. 7 is different from the motor 1 of the second embodiment in that the configuration of the magnet holder 32B and the encoder 28B are included.

  First, the configuration of the magnet holder 32B will be described. The magnet holder 32B in FIG. 7 has a rotor core 81B and a positioning plate 82B. The rotor core 81B has a lid portion 321B and a cylindrical portion 322B. The lid portion 321B is a portion that extends in the radial direction above the bearing portion 27B. The inner peripheral portion of the lid portion 321B is fixed to the outer peripheral surface of the shaft 31B. The cylindrical portion 322B is a substantially cylindrical portion that extends downward from the outer peripheral portion of the lid portion 321B.

  The rotor core 81B of the present embodiment is a press-formed product obtained by pressing an alloy plate containing iron as a main component. For this reason, compared with the case where a rotor core is produced by casting or cutting, the rotor core 81B can be mass-produced at low cost.

  The positioning plate 82B is a flat plate-like member disposed on the upper surface of the lid portion 321B of the rotor core 81B. The inner peripheral portion of the positioning plate 82B is fixed to the outer peripheral surface of the shaft 31B. The positioning plate 82B of the present embodiment is made of a laminated steel plate in which a plurality of electromagnetic steel plates are laminated in the axial direction. For example, a silicon steel plate is used as the electromagnetic steel plate.

  A plurality of protruding portions 821B protruding outward in the radial direction are provided on the outer peripheral portion of the positioning plate 82B. The plurality of protrusions 821B are arranged at equal intervals in the circumferential direction. The number of protrusions 821B included in the positioning plate 82B matches the number of rotor magnets 33B. An end portion on the radially outer side of the protruding portion 821B is located on the radially outer side from the radially inner surface of the rotor magnet 33B.

  The upper part of each rotor magnet 33B is arrange | positioned between a pair of protrusion parts 821B adjacent to the circumferential direction. That is, the plurality of rotor magnets 33B are arranged at circumferential positions defined by the plurality of protrusions 821B. At the time of manufacturing the motor 1B, the circumferential positions of the rotor magnets 33B are easily and accurately positioned using the plurality of protrusions 821B. If the plurality of rotor magnets 33B are accurately positioned in the circumferential direction, the back electromotive force waveform during the operation of the motor 1B is stabilized. If it does so, the pulsation of a torque will be suppressed and the vibration and noise of the motor 1B will be reduced.

  If a shape equivalent to the protruding portion 821B is to be formed on the rotor core 81B by press processing, the press processing step is greatly complicated. However, in this embodiment, a positioning plate 82B having a protruding portion 821B is arranged separately from the rotor core 81B. For this reason, the protrusion part 821B can be provided easily.

  Further, if the rotor core 81B and the positioning plate 82B are separate members, various combinations of a plurality of types of rotor cores 81B and a plurality of types of positioning plates 82B are possible. For example, even when the shape of the positioning plate 82B is changed according to the required specifications, the rotor core 81B can be used without changing the shape.

  In addition, the positioning plate 82B may be arrange | positioned at the upper surface side of the rotor core 81B like FIG. 7, and may be arrange | positioned under the rotor core 81B. However, when the positioning plate 82B is disposed on the upper surface side of the rotor core 81B, it is easier to dispose the case 21B and the bearing portion 27B below the lid portion 321B of the rotor core 81B. The positioning plate 82B may be disposed above the upper surface of the rotor core 81B with a gap.

  The stator core 22B and the positioning plate 82B of the present embodiment are both made of laminated steel plates. Further, the stator core 22B and the positioning plate 82B do not overlap each other in plan view. For this reason, the electromagnetic steel plate constituting the stator core 22B and the electromagnetic steel plate constituting the positioning plate 82B can be punched from the same electromagnetic steel plate. In this case, electromagnetic steel plates of the same material and thickness are used for the stator core 22B and the positioning plate 82B. In this way, resources can be used effectively and the amount of waste can be reduced. As a result, the manufacturing cost of the motor 1B can be suppressed, and the burden on the environment can be reduced.

  In the example of FIG. 7, an encoder 28 </ b> B is provided on the upper surface side of the circuit board 26 </ b> B instead of the magnetic sensor 261 and the sensor magnet 34. The encoder 28B includes a detection unit 281B installed on the upper surface of the circuit board 26B, and a detected plate 282B attached to the shaft 31B. The detected plate 282B is provided with a plurality of slits arranged in the circumferential direction. The detection unit 281B detects the number of rotations of the rotation unit 3B by optically detecting the plurality of slits of the detection plate 282B.

<4. Modification>
As mentioned above, although exemplary embodiment of this invention was described, this invention is not limited to said embodiment.

  The protrusion of the positioning plate may have a function of fixing the rotor magnet as well as positioning of the rotor magnet. For example, the protruding portion may be protruded to a position on the outer side in the radial direction, and the rotor magnet may be press-fitted between the adjacent protruding portions. If it does in this way, the adhesive agent for fixing a rotor magnet to a magnet holder can be omitted.

  Further, the positioning plate may be punched from the same electromagnetic steel plate as the stator core as in the second embodiment or the third embodiment, or may be punched from a different electromagnetic steel plate. Good.

  Further, the positioning plate does not necessarily need to be made of a laminated steel plate. The positioning plate may be made of a single steel plate, or may be made of a material such as a resin that is not a metal.

  The case may be composed of two or more members. For example, the case may have a first case member that holds the stator core and a second case member that holds the bearing portion.

  Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

  The present invention can be used for an inner rotor type motor.

1, 1A, 1B Motor 2, 2A Stationary portion 3, 3A, 3B Rotating portion 9, 9A Center shaft 21, 21A, 21B Case 22, 22A Stator core 23, 23A Coil 24 Upper insulating member 25 Lower insulating member 26, 26B Circuit board 27, 27A, 27B Bearing portion 28B Encoder 31, 31A, 31B Shaft 32, 32A, 32B Magnet holder 33, 33B Rotor magnet 33A Magnet 34 Sensor magnet 41 First steel plate 42 Second steel plate 51 First caulking portion 52 Second caulking portion 53 Through-hole 61 Electromagnetic steel plate constituting stator core 71 Electromagnetic steel plate 81B Rotor core 82A, 82B Positioning plate 321, 321A, 321B Lid portion 322, 322A, 322B Cylindrical portion 323 Body portion 411 First projecting portion 412 First circular hole 421 First 2 protrusions 422 Second circular hole 821A, 821B protrusion

Claims (9)

A stationary part;
A rotating part that rotates about a central axis extending vertically;
With
The rotating part is
A shaft disposed along the central axis;
A magnet holder having a lid portion fixed to the shaft and a cylindrical portion extending downward from an outer peripheral portion of the lid portion;
A plurality of magnets fixed to the outer peripheral surface of the magnet holder;
Have
The stationary part is
A coil disposed radially outside the magnet;
A stator core having a plurality of teeth serving as a magnetic core of the coil;
A bearing that rotatably supports the shaft;
A case for holding the stator core and the bearing portion;
Have
The bearing portion is disposed on the radially inner side of the cylindrical portion,
The magnet holder includes a positioning plate having a plurality of projecting portions projecting radially outward from a radially inner surface of the magnet,
The plurality of magnets are motors arranged at circumferential positions defined by the plurality of protrusions. The motor according to claim 1,
The magnet holder is composed of a laminated steel sheet in which a plurality of electromagnetic steel sheets are laminated in the axial direction,
The motor in which the plurality of electromagnetic steel plates include the positioning plate. The motor according to claim 2,
The magnet holder has a caulking portion in which the plurality of electromagnetic steel plates are deformed in the axial direction,
The motor in which the circumferential position of the caulking portion and the circumferential position of the protruding portion are substantially the same. The motor according to claim 2,
The plurality of electrical steel sheets are:
One or more first steel plates having a first circular hole in the center and constituting the lid;
A second circular hole larger than the first circular hole in the center, and one or more second steel plates constituting the cylindrical portion; and
Have
The cylindrical portion has a crimped portion in which the one or more second steel plates are deformed in the axial direction,
The one or more first steel plates have a through hole provided at a position overlapping the caulking portion in plan view. The motor according to claim 1,
The magnet holder is
A rotor core having the lid portion and the cylindrical portion;
A motor having the positioning plate which is a separate member from the rotor core. The motor according to claim 5, wherein
The rotor core is a motor that is a press-formed product. The motor according to claim 5 or 6,
The positioning plate is a motor disposed on an upper surface side of the lid portion. The motor according to any one of claims 1 to 7,
The magnet holder has a body portion on which the protruding portion is not provided,
The positioning plate is a motor arranged at at least one of an upper position and a lower position of the body portion. In the motor according to any one of claims 1 to 8,
The stator core is a motor made of a laminated steel plate in which electromagnetic steel plates having the same material and thickness as the positioning plate are laminated in the axial direction.

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