JP2015163038A - inner rotor type brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner rotor type motor which inhibits vibration and noise.SOLUTION: An inner rotor type motor includes: a stator core 21; a rotor 10 which rotates around a rotation axis R relative to the stator core 21; a bearing part 30 which rotatably supports the rotor 10; a bearing holder 40 which holds the bearing part 30; and a housing 70 including a cylindrical part 71. The stator core 21 is fixed to an inner peripheral surface of the cylindrical part 71. The stator core 21 fits in the bearing holder 40.

Description

  The present invention relates to an inner rotor type brushless motor, and more particularly to an inner rotor type brushless motor capable of suppressing vibration and noise.

  Inner rotor type brushless motors are used as a drive source for office machines such as copiers and multifunction machines. In recent years, household appliances used in the home are also being replaced by brushless motors that have been used in the past with brush motors that have been used in the past.

  For this type of inner rotor type brushless motor, there is a demand for higher output (higher efficiency) and lower price. As a technique for coping with these requirements, for example, in Patent Documents 1 and 2 below, an inner rotor type brushless motor including a rotor, a pair of bearings that rotatably support the rotor, and a bearing housing that holds the bearings Has been proposed.

  Patent Document 1 listed below discloses a motor including a rotor, a stator, two bearings that rotatably support the rotor, and a cover member. The rotor includes a shaft, a cylindrical rotor holder fixed to the shaft, and a rotor magnet fixed to the outer peripheral surface of the rotor holder. The cover member includes an outer cylinder portion that supports the stator on the inner surface, an inner cylinder portion that is coaxial with the outer cylinder portion and supports two bearings on the inner surface, a lower end of the outer cylinder portion, and a lower end of the inner cylinder portion And a bottom portion for connecting the two. The outer protrusion of the insulator of the stator is in contact with the bottom of the cover member. Thereby, the stator is positioned in the central axis direction.

  Patent Document 2 listed below discloses a motor including a rotor portion, a stator portion, a housing that houses the rotor portion and the stator portion, and a bearing mechanism. The rotor portion includes a shaft protruding downward from the opening at the bottom, a cylindrical rotor core attached to the shaft, and a magnet attached to the outer peripheral surface of the rotor core. The stator is fixed to the inner peripheral surface of the cylindrical portion of the housing. The housing includes a cylindrical portion, a bottom portion that covers the lower end of the cylindrical portion and has an opening formed in the center, and a cylindrical bearing holding portion that protrudes upward along the central axis from the opening of the bottom portion. Yes. The bearing mechanism is held on the inner peripheral surface of the bearing holding portion.

Japanese Patent Application Laid-Open No. 2011-167054 JP 2007-181314 A

  Conventional inner rotor type motors such as an inner rotor type brushless motor have a problem that the coaxiality (coaxiality accuracy) between the stator and the rotor is poor. The coaxiality between the stator and the rotor here means the coaxiality between the rotation space of the rotor formed by the tip of the salient pole of the stator and the outer peripheral surface of the rotor.

  In the motor of Patent Document 1, the coaxiality between the stator and the rotor is affected by the component accuracy of each of the shaft, the rotor holder, the bearing, the cover member, and the stator. For this reason, it is difficult to increase the coaxiality between the stator and the rotor. In addition, since the cover member is formed by pressing a single metal plate member, it is not easy to increase the coaxiality between the outer cylinder portion and the inner cylinder portion of the cover member.

  In the motor of Patent Document 2, the coaxiality between the stator and the rotor is affected by the accuracy of the parts of the shaft, the rotor core, the bearing, the cylindrical portion of the housing, the bearing holding portion, and the stator. For this reason, it is difficult to increase the coaxiality between the stator and the rotor.

  If the concentricity between the rotor and the stator is low, the distance between the stator salient pole and the rotor magnet varies depending on the rotational position of the rotor, so that vibration occurs in the rotor. Due to this vibration, the housing to which the motor is attached makes noise. In particular, when the inner rotor type motor is attached to a device used in a relatively quiet place such as office equipment and household appliances, this problem can be prominent.

  The present invention is to solve the above-described problems, and an object thereof is to provide an inner rotor type motor capable of suppressing vibration and noise.

  An inner rotor type motor according to one aspect of the present invention includes a stator core, a rotor that rotates about a rotation axis with respect to the stator core, a bearing portion that rotatably supports the rotor, a bearing holder that holds the bearing portion, The stator core is fixed to the inner peripheral surface of the housing cylindrical portion, and the stator core and the bearing holder are fitted.

  Preferably, in the inner rotor type motor, the housing further includes a bottom portion extending in an inner diameter direction from the housing cylindrical portion, and the bearing holder is provided on the outer diameter side of the inner cylinder portion that holds the bearing portion and the inner cylinder portion. The outer cylinder part, the holder-side fitting part fitted to the stator core, the inner cylinder part and the outer cylinder part connected to each other, and the bottom part. And a buttock fixed to the head.

  Preferably, in the inner rotor type motor, the stator core includes a back yoke having an annular shape and a plurality of salient pole portions protruding in an inner diameter direction from the back yoke, and at least two salient poles among the plurality of salient pole portions. The part includes a salient pole part side fitting part that fits with the holder side fitting part.

  Preferably, in the inner rotor type motor, the salient pole part-side fitting part is a groove formed continuously at the other end part in the rotation axis direction and the inner diameter side end part of at least two salient pole parts.

  Preferably, in the inner rotor type motor, the salient pole part-side fitting part is formed at a position deviated from a central part in the circumferential direction in each of the at least two salient pole parts.

  In the inner rotor type motor, preferably, the inner peripheral surface of at least two salient pole portions, the inner peripheral surface of the holder-side fitting portion, and the inner peripheral surface of the outer cylinder portion are closer to the outer diameter side than the outer peripheral surface of the rotor. Exists.

  Preferably, in the inner rotor type motor, the stator core is configured by a plurality of core plates stacked in the direction of the rotation axis, and the plurality of core plates are at least one disposed on the side close to the holder side fitting portion. Each of the plurality of salient pole portions includes a first core plate configured by a core plate and a second core plate configured by a plurality of core plates disposed on a side away from the holder side fitting portion. Includes a salient pole part main body around which a coil is wound, and a tip part provided on the inner diameter side of the salient pole part main body, and the salient pole part side fitting part is a core plate constituting the first core plate In the case where each of the plurality of core plates constituting the second core plate is viewed in a plane having the rotation axis as a normal line. Each of the plurality of core plates constituting the second core plate includes a core plate protrusion that protrudes in the same direction along the rotation axis at a position overlapping with the through hole. Connected.

  Preferably, in the inner rotor type motor, the salient pole portion side fitting portion is formed on the inner diameter side with respect to a position where the coil in the stator core is wound.

  Preferably, in the inner rotor type motor, the salient pole part-side fitting part is formed on the entire tip part of at least two salient pole parts along the rotation axis.

  Preferably, in the inner rotor type motor, the salient pole part-side fitting part is formed in a number of salient pole parts corresponding to a natural number times the number of phases of the coil wound around the stator core among the plurality of salient pole parts, And it forms in the salient pole part which exists in the position of line symmetry.

  Preferably, in the inner rotor type motor, the bearing portion includes two bearings, and the flange portion connects a position between the two bearings in the inner cylinder portion and the outer cylinder portion.

  Preferably, in the inner rotor type motor, the housing further includes a passage hole for allowing the bearing holder to pass therethrough, and the inner circumferential surface of the passage hole and the outer circumferential surface of the bearing holder are opposed to each other with a space therebetween.

  According to the present invention, it is possible to provide an inner rotor type motor capable of suppressing vibration and noise.

1 is an external perspective view schematically showing a configuration of a motor in a first embodiment of the present invention. It is sectional drawing along the II-II line of FIG. It is sectional drawing which expands and shows structures, such as the rotor 10, the bearing holder 40, and the stator core 21, in the motor shown in FIG. It is an external appearance perspective view which shows typically the structure of the bearing holder 40 shown in FIG. It is an external appearance perspective view which shows typically the structure of the stator core 21 shown in FIG. It is a fragmentary sectional perspective view which shows the state which combined the bearing holder 40 and the stator core 21 in the 1st Embodiment of this invention. It is an external appearance perspective view which shows typically the structure of the bearing holder 40 in the motor of the 2nd Embodiment of this invention. It is an external appearance perspective view which shows typically the structure of the stator core 21 in the motor of the 2nd Embodiment of this invention. It is a fragmentary sectional perspective view which shows the state which combined the bearing holder 40 and the stator core 21 in the 2nd Embodiment of this invention. FIG. 10 is a cross-sectional view taken along line XX in FIG. 9. It is an external appearance perspective view which shows typically the structure of the bearing holder 40 in the motor of the 3rd Embodiment of this invention. It is an external appearance perspective view which shows typically the structure of the stator core 21 in the motor of the 3rd Embodiment of this invention. It is a fragmentary sectional perspective view which shows the state which combined the bearing holder 40 and the stator core 21 in the 3rd Embodiment of this invention. In the third embodiment of the present invention, a state in which the magnetic pole boundary 15a of the rotor magnet 15 approaches the end of the tip 27 while the rotor magnet 15 rotates counterclockwise with respect to the stator core 21 is schematically illustrated. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the following embodiments, a case where the inner rotor type motor is a brushless motor will be described. There may be.
[First Embodiment]

  FIG. 1 is an external perspective view schematically showing the configuration of the motor according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  1 and 2, the motor in the present embodiment is an inner rotor type brushless motor having a so-called cantilever bearing structure. The motor mainly includes a rotor 10, a stator 20, a bearing portion 30, a bearing holder 40, a mounting plate 50, a housing 70, and a cover 80. The attachment plate 50 includes a plurality of attachment holes 51 for inserting screws (not shown) or the like when attaching the motor to a desired device. A housing 70 is fixed on the mounting plate 50 by welding or the like. An upper portion of the housing 70 is open, and a cover 80 is provided on the housing 70 so as to close the opening. The housing 70 and the cover 80 are engaged with each other. In the space formed by the housing 70 and the cover 80, a part of the rotor 10, the stator 20, the bearing portion 30, and a part of the bearing holder 40 are arranged.

  The rotor 10 rotates relative to the stator 20 (relative to the stator core 21) about the rotation axis R. The rotor 10 includes a shaft 11, a rotor yoke 12, and a rotor magnet 15. The shaft 11 has a cylindrical shape and extends in the direction of the rotation axis R. The rotor yoke 12 has a covered cylindrical shape. The rotor yoke 12 includes a mounting hole 13 a, a lid portion 13, and a cylindrical portion 14. The attachment hole 13 a is formed in the center portion of the lid portion 13. The lid portion 13 has a disk shape and extends from the mounting hole 13a in the outer diameter direction. The shaft 11 passes through the attachment hole 13a in the direction of the rotation axis R, and is attached to the lid portion 13 by press fitting or the like. The cylindrical portion 14 extends downward in FIG. 2 along the rotation axis R from the outer diameter side end portion of the lid portion 13. The rotor magnet 15 is fixed to the outer peripheral surface of the cylindrical portion 14 by, for example, adhesion. The rotor magnet 15 is magnetized alternately in N and S poles along the circumferential direction (rotation direction of the rotor 10).

  The stator 20 is fixed to the housing 70. The stator 20 includes a stator core 21, an insulator 22, and a coil 23. The stator core 21 is fitted with the bearing holder 40. The coil 23 is wound around the stator 20. The insulator 22 insulates the stator core 21 and the coil 23 from each other. Specifically, the insulator 22 covers the upper surface in FIG. 2 of the stator core 21, the lower surface in FIG. 2 of the stator core 21 excluding the portion contacting the upper surface of the outer cylinder portion 43 in the bearing holder 40, and the side surface of the stator core 21. Yes. The coil 23 is wound around the stator core 21 from above the insulator 22.

  The bearing part 30 supports the rotor 10 rotatably. The bearing portion 30 includes bearings 31 and 32. Each of the bearings 31 and 32 is disposed at a different position along the rotation axis R, and is spaced apart from each other. In each of the bearings 31 and 32, the inner portion holds the shaft 11, and the outer portion is held by the bearing holder 40. Each of the bearings 31 and 32 may be a rolling bearing or a sliding bearing.

  The housing 70 has a bottomed cylindrical shape. The housing 70 includes a cylindrical portion 71 (an example of a housing cylindrical portion), a bottom portion 72, and a passage hole 72a. The cylindrical portion 71 extends upward in FIG. 2 along the rotation axis R from the outer diameter side end portion of the bottom portion 72. The stator core 21 is fixed to the inner peripheral surface of the cylindrical portion 71 by, for example, adhesion. The bottom portion 72 has a disc shape and extends from the cylindrical portion 71 in the inner diameter direction. A passage hole 72 a is formed at the center of the bottom 72. The mounting plate 50 further includes a passage hole 52 in the central portion. The passage holes 52 and 72a have, for example, the same diameter. The passage holes 52 and 72a allow the shaft 11 and the bearing holder 40 to pass in the direction of the rotation axis R. The inner peripheral surfaces of the passage holes 52 and 72a and the outer peripheral surface of the bearing holder 40 are opposed to each other with a gap in the radial direction.

  The cover 80 has a covered cylindrical shape. The cover 80 includes a through hole 80a, a lid portion 81, and a cylindrical portion 82. The through hole 80 a is formed in the central portion of the lid portion 81. The shaft 11 passes through the through hole 80a in the direction of the rotation axis R, and faces the lid portion 81 in the radial direction with a space therebetween. The lid portion 81 has a disk shape and extends from the through hole 80a in the outer diameter direction. The cylindrical portion 82 extends downward in FIG. 2 along the rotation axis R from the outer diameter side end portion of the lid portion 81. The lower end portion of the cylindrical portion 82 in FIG. 2 is engaged with the upper end portion of the cylindrical portion 71 in FIG.

  A circuit board 61 on which an electronic component (not shown) is mounted is fixed to the upper end portion of the insulator 22 in FIG. A conductive wire of the coil 23 is connected to the circuit board 61. The circuit board 61 includes a through hole 61a at the center. The shaft 11 passes through the through-hole 61a in the direction of the rotation axis R, and is opposed to the circuit board 61 in the radial direction with a space therebetween. An elastic body 62 made of a wave spring, for example, is sandwiched between the bearing 32 and the bearing holder 40. The elastic body 62 applies a preload in the direction of the rotation axis R to the bearing 32.

  The motor is assembled by the following method, for example. The bearing holder 40 in a state where the rotor 10 is combined is inserted into the passage hole 72 a of the housing 70. Subsequently, the flange portion 42 of the bearing holder 40 is brought into contact with the bottom portion 72 of the housing 70. Next, the stator 20 is inserted into the cylindrical portion 71 of the housing 70. And the stator 20 and the housing 70 are fixed by adhesion | attachment, press fit, etc. in the state which contact | abutted the lower end part of the stator core 21 to the upper surface of the outer cylinder part 43 of the bearing holder 40. FIG.

  FIG. 3 is an enlarged cross-sectional view showing the configuration of the rotor 10, the bearing holder 40, the stator core 21 and the like in the motor shown in FIG. FIG. 4 is an external perspective view schematically showing the configuration of the bearing holder 40 shown in FIG.

  Referring to FIGS. 3 and 4, bearing holder 40 includes an inner cylinder part 41, a flange part 42, an outer cylinder part 43, and nine protrusions 44 (an example of a holder-side fitting part). It is out. The inner cylinder portion 41 is a portion that holds the bearing portion 30 and extends along the rotation axis R. The outer cylinder portion 43 is provided on the outer diameter side of the inner cylinder portion 41 and extends along the rotation axis R. The inner cylinder part 41 and the outer cylinder part 43 are coaxial. The protruding portion 44 is a portion that fits with the stator core 21 and is provided at the upper end portion in FIG. Each of the protrusions 44 is provided at a position corresponding to the groove 24 and is provided at equal intervals along the circumferential direction. Each inner peripheral surface IN2 of the protrusion 44 has an arc shape when viewed in a plane having the rotation axis R as a normal line. The flange part 42 connects the inner cylinder part 41 and the outer cylinder part 43 to each other. The collar portion 42 is fixed to the bottom portion 72 (FIG. 2) of the housing 70. The flange 42 connects, for example, a position between the bearing 31 and the bearing 32 and the outer cylinder 43. Moreover, the collar part 42 is extended in the internal diameter direction, for example from the lower end part in FIG. The bearing holder 40 is made of, for example, resin or aluminum die casting. When the bearing holder 40 is made of resin, the bearing holder 40 can be formed at a low cost.

  FIG. 5 is an external perspective view schematically showing the configuration of the stator core 21 shown in FIG. FIG. 6 is a partial cross-sectional perspective view showing a state in which the bearing holder 40 and the stator core 21 are combined in the first embodiment of the present invention.

  5 and 6, the stator core 21 is composed of a plurality of magnetic steel plates 21a stacked in the rotation axis R direction. The stator core 21 includes a back yoke 25 and a plurality of salient pole portions 26. Stator core 21 in the present embodiment is used for a three-phase brassless motor and has nine (9 poles) salient pole portions 26. The back yoke 25 has an annular shape and is fixed to the inner peripheral surface of the cylindrical portion 71 (FIG. 2). Each of the plurality of salient pole portions 26 is arranged at equal intervals in the circumferential direction and protrudes from the back yoke 25 toward the inner diameter direction. Each of the plurality of salient pole portions 26 has a substantially T-shape when viewed in a plane having the rotation axis R as a normal line. Each of the plurality of salient pole portions 26 includes a salient pole portion main body 28, a tip end portion 27, and a groove 24 (an example of a salient pole portion-side fitting portion). The salient pole body 28 is a portion around which the coil 23 (FIG. 2) is wound via the insulator 22. The tip portion 27 is a portion around which the coil 23 is not wound, and is provided on the inner diameter side of the salient pole portion main body 28. The circumferential width of the tip 27 is wider than the circumferential width of the salient pole body 28. The groove 24 is a portion that fits into the protrusion 44 and is formed continuously at the lower end of FIG. The groove 24 is formed in the central portion in the circumferential direction at the distal end portion 27. The groove 24 is formed only in at least one (three in this case) magnetic steel plate 21a disposed on the side close to the protrusion 44 (lower side in FIG. 5).

  The groove 24 may be formed in the lower end portion (lower surface) of the stator core 21 and may be formed in the entire tip portion 27 (on all the magnetic steel plates 21a) along the rotation axis R.

  When the lower surface of the stator core 21 comes into contact with the upper surface of the outer cylindrical portion 43 of the bearing holder 40 during the assembly of the motor, the groove 24 of the stator core 21 and the protrusion 44 of the bearing holder 40 are fitted. Thereby, the position of the circumferential direction (rotation direction) of the bearing holder 40 with respect to the stator core 21 and the position of radial direction are fixed. In order to position the stator core 21 and the bearing holder 40 with higher accuracy, it is preferable that the ceiling surface of the groove 24 and the upper surface of the protrusion 44 contact each other.

  Further, the inner peripheral surface IN1 of the tip portion 27, the inner peripheral surface IN2 of the protrusion 44, and the inner peripheral surface IN3 of the outer cylinder portion 43 have substantially the same diameter, and are more external than the outer peripheral surface of the rotor 10. Exists on the radial side. Thereby, the rotor magnet 15 (FIG. 2) can be extended in the lower direction in FIG. 2 than the stator core 21, and the center position of the stator core 21 in the direction of the rotation axis R and the center of the rotor magnet 15 in the direction of the rotation axis R. Each degree of freedom with respect to position increases. As a result, most of the lines of magnetic force generated from the coil 23 can be received by the rotor magnet 15, and the motor can be driven efficiently.

  According to the present embodiment, the center of rotor 10 and the center of stator core 21 are positioned using bearing holder 40. That is, when the groove 24 of the salient pole portion 26 and the protrusion 44 of the bearing holder 40 are fitted, the circumferential position (rotation direction) and radial position of the bearing holder 40 with respect to the stator core 21 are fixed. Thereby, the influence which the component accuracy of the housing 70 has on the coaxiality between the stator 20 and the rotor 10 can be weakened, and the rotation space of the rotor 10 formed by the tip portion 27 of the stator 20 and the outer peripheral surface of the rotor 10 can be reduced. The coaxiality of is improved. The distance between the stator tip 27 and the rotor magnet 15 is stabilized regardless of the rotational position of the rotor 10. As a result, motor vibration and noise can be suppressed.

  Further, since the position of the stator core 21 in the direction of the rotation axis R with respect to the housing 70 is fixed by the fitting of the groove 24 and the protrusion 44, the housing 70 is not required to have high dimensional accuracy.

  Further, since the bottom portion 72 of the housing 70 is in contact with the stator core 21 via the bearing holder 40, the resonance point of the housing 70 and the mounting plate 50 is increased, and noise due to resonance of the housing 70 and the mounting plate 50 is suppressed. be able to.

  [Second Embodiment]

  FIG. 7 is an external perspective view schematically showing the configuration of the bearing holder 40 in the motor according to the second embodiment of the present invention.

  Referring to FIG. 7, bearing holder 40 in the present embodiment includes nine protrusions 44 having a cylindrical shape.

  FIG. 8 is an external perspective view schematically showing the configuration of the stator core 21 in the motor according to the second embodiment of the present invention. FIG. 9 is a partial cross-sectional perspective view showing a state where the bearing holder 40 and the stator core 21 are combined in the second embodiment of the present invention. 10 is a cross-sectional view taken along line XX in FIG.

  8 to 10, the stator core 21 is configured by a plurality of magnetic steel plates 21 a (an example of a stator core) stacked in the direction of the rotation axis R. Each of the plurality of magnetic steel plates 21a includes a connecting hole (a dowel, a depression) 91a formed on the upper surface of the salient pole body 28, and a projection 92a projecting downward in FIG. Is included. Each of the connecting hole 91a and the protrusion 92a is formed at an overlapping position when viewed in a plane having the rotation axis R as a normal line, and has substantially the same diameter. The connection hole 91a of a certain magnetic steel plate 21a is fitted to the protrusion 92a of the adjacent magnetic steel plate 21a at the upper portion, and the protrusion 92a of the certain magnetic steel plate 21a is connected to the connection hole 91a of the adjacent magnetic steel plate 21a at the lower portion. It is mated. Thereby, each of the some magnetic steel plate 21a is mutually connected.

  The plurality of magnetic steel plates 21a includes a first group GP1 and a second group GP2. The first group GP1 is composed of at least one magnetic steel plate 21a disposed on the side close to the protrusion 44 (the lower side in FIG. 10). The magnetic steel plates 21a of the second group GP1 are composed of a plurality of magnetic steel plates 21a arranged on the side away from the protrusions 44 (upper side in FIG. 10).

  The magnetic steel plate 21a constituting the first group GP1 further includes a through hole 29 formed in the tip portion 27. The through hole 29 is fitted with the protrusion 44.

  Each of the plurality of magnetic steel plates 21a constituting the second group GP2 protrudes downward in FIG. 10 at a connecting hole (dwelling, depression) 91b formed on the upper surface of the tip portion 27 and the lower surface of the tip portion 27. It further includes a protrusion 92b (an example of a core plate protrusion). Each of the through hole 29, the connecting hole 91 b, and the protrusion 92 b is formed at an overlapping position when viewed in a plane having the rotation axis R as a normal line, and has substantially the same diameter. The through hole 29, the connecting hole 91b, and the protruding portion 92b are provided on the inner diameter side of the connecting hole 91a and the protruding portion 92a, and are provided at positions where no coil is formed. The connection hole 91b of a certain magnetic steel plate 21a constituting the second group GP2 is fitted to the protrusion 92a of the adjacent magnetic steel plate 21a at the upper portion, and the projection of the certain magnetic steel plate 21a constituting the second group GP2. The part 92b is fitted to the protrusion 92b of the magnetic steel plate 21a adjacent at the lower part. Thereby, each of the some magnetic steel plate 21a which comprises 2nd group GP2 is mutually connected.

  The total depth of the through holes 29 when viewed in the entire stator core 21 is the height of the protrusions 44 (see FIG. 10) of the magnetic steel plates 21a disposed on the side close to the protrusions 44 (the lower side in FIG. 10). It can be adjusted by forming the through-holes 29 in the number of magnetic steel plates 21a deeper than the length in the middle and vertical direction.

  Further, since the depth of the through hole 29 only needs to be deeper than the height of the protruding portion 44, the entire stator core 21 may be formed only by the first group GP1.

  Since the configuration of the motor in the present embodiment other than the above is the same as the configuration of the motor in the first embodiment, the same members are denoted by the same reference numerals, and the description thereof will not be repeated.

  According to the present embodiment, the through hole 29 of the magnetic steel plate 21a constituting the first group GP1 and the protrusion 44 of the bearing holder 40 are fitted to each other, whereby the circumferential direction of the bearing holder 40 with respect to the stator core 21 ( The position in the rotation direction) and the position in the radial direction are fixed. As a result, the coaxiality between the rotation space of the rotor 10 formed by the front end portion 27 of the stator 20 and the outer peripheral surface of the rotor 10 is improved, and the front end portion 27 of the stator and the rotor magnet regardless of the rotation position of the rotor 10. The distance to 15 is stabilized. As a result, motor vibration and noise can be suppressed.

  In addition, the through holes 29 are easily formed by punching the positions of the connection holes 91b and the protrusions 92b in the magnetic steel plate 21a when each of the magnetic steel plates 21a constituting the stator core 21 is formed by sheet metal pressing. Can do. For this reason, the stator core 21 can be easily manufactured using a conventional mold structure.

  [Third Embodiment]

  FIG. 11 is an external perspective view schematically showing the configuration of the bearing holder 40 in the motor according to the third embodiment of the present invention.

  Referring to FIG. 11, bearing holder 40 in the present embodiment includes four protrusions 44. Each of the protrusions 44 is provided at a position corresponding to the groove 24 and is provided at equal intervals along the circumferential direction. Each inner peripheral surface IN2 of the protrusion 44 has an arc shape when viewed in a plane having the rotation axis R as a normal line.

  FIG. 12 is an external perspective view schematically showing the configuration of the stator core 21 in the motor according to the third embodiment of the present invention. FIG. 13 is a partial cross-sectional perspective view showing a state where the bearing holder 40 and the stator core 21 are combined in the third embodiment of the present invention.

  Referring to FIGS. 12 and 13, stator core 21 in the present embodiment is used for a two-phase brushless motor, and has four (four poles) salient pole portions 26. Each of the plurality of salient pole portions 26 includes a groove 24 (an example of a salient pole portion-side fitting portion). The groove 24 is formed at the inner diameter side end portion of the distal end portion 27. The groove 24 is formed at a position deviated, for example, in the clockwise direction from the central portion of the distal end portion 27 in the circumferential direction. The groove 24 is formed along the rotation axis R in the entire tip portion 27 (on all the magnetic steel plates 21a).

  Since the configuration of the motor in the present embodiment other than the above is the same as the configuration of the motor in the first embodiment, the same members are denoted by the same reference numerals, and the description thereof will not be repeated.

  According to the present embodiment, the groove 24 in the vicinity of the lower surface of the stator core 21 and the protrusion 44 of the bearing holder 40 are fitted to each other, so that the position and diameter of the bearing holder 40 in the circumferential direction (rotational direction) with respect to the stator core 21. The position of the direction is fixed. As a result, the coaxiality between the rotation space of the rotor 10 formed by the front end portion 27 of the stator 20 and the outer peripheral surface of the rotor 10 is improved, and the front end portion 27 of the stator and the rotor magnet regardless of the rotation position of the rotor 10. The distance to 15 is stabilized. As a result, motor vibration and noise can be suppressed.

  In addition, since the groove 24 is formed at a position deviated from the central portion in the circumferential direction at the tip portion 27, the cogging torque can be reduced and the start-up of the two-phase brushless motor can be stabilized. This will be described below.

  FIG. 14 shows that in the third embodiment of the present invention, the rotor magnet 15 rotates counterclockwise with respect to the stator core 21, and the magnetic pole boundary 15a approaches the end of the tip 27. FIG.

  Referring to FIG. 14, cogging torque is unevenness in rotational torque. The cause of the cogging torque is that the magnetic poles are not smoothly switched when the salient pole part and the rotor magnet facing it move relatively. Therefore, cogging torque is generated in a situation where the circumferential end of the salient pole part is located near the boundary between the magnetic poles of the rotor magnet.

  When the boundary 15 a of the magnetic pole of the rotor magnet 15 approaches the end of the tip portion 27, the groove 24 forms a larger gap with the rotor magnet 15 than the other portions of the tip portion 27. For this reason, compared with the magnetic flux density which acts on the part 27a, the magnetic flux density which acts on the part 27b becomes relatively weak. Torque that suppresses the peak of cogging torque is generated due to the difference in magnetic flux density. As a result, the cogging torque can be reduced and the starting of the two-phase brushless motor can be stabilized.

  [Others]

  In the above-described embodiment, the case where the salient pole portion-side fitting portions are formed in all the salient pole portions of the stator core has been described. However, the salient pole portion-side fitting portion is formed of a plurality of salient pole portions of the stator core. Of these, it may be formed only on some salient pole parts, and the fitting position between the fitting part of the bearing holder and the salient pole part of the stator core, and the number of fitting parts are arbitrary. The salient pole part-side fitting part is preferably formed at the tip of at least two salient pole parts.

  The salient pole part-side fitting parts are formed on the number of salient pole parts corresponding to a natural number multiple of the number of phases of the coil wound around the stator core among the plurality of salient pole parts, and exist at line-symmetric positions. It is preferable to be formed in the pole part. For example, in the first embodiment, since the motor is a three-phase brassless motor, the salient pole portion-side fitting portion exists in a line-symmetric position among the nine salient pole portions 26 shown in FIG. Preferably, each of the three salient pole portions 26a, 26d, and 26g, or each of the six salient pole portions 26a, 26b, 26d, 26g, and 26i is formed. Thereby, the distortion of the stator 20 due to excitation when the coil 23 is energized tends to be uniform with respect to the radial center of the stator 20, and the coaxiality between the rotor 10 and the stator 20 can be further improved.

  In the above-described embodiment, the configuration in which the two bearings support the rotor has been described, but the number of bearings that support the rotor is arbitrary.

  In the above-described embodiment, the case where the groove or hole is provided on the stator core side and the projection portion to be fitted to the bearing holder side is provided, but the projection portion is provided on the stator core side and the bearing holder side is provided. A groove or hole may be provided to mate with this.

  The above-described embodiments can be combined as appropriate. For example, in the motor of the second embodiment, the configuration in which the groove is formed in the entire tip portion 27 along the rotation axis R in the third embodiment is applied to the second embodiment. You may form the through-hole 29 in the whole front-end | tip part 27 along the rotating shaft R (in all the magnetic steel plates 21a). Further, by applying the configuration in which the groove 44 is formed only in the lower end portion of the stator core 21 in the first embodiment to the third embodiment, the groove 44 is provided in the motor of the third embodiment. May be formed only on the lower end portion (a part of the magnetic steel plate 21a) of the stator core 21.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10 Rotor 11 Shaft 12 Rotor yoke 13 Rotor yoke cover 13a Rotor yoke mounting hole 14 Rotor yoke cylindrical portion 15 Rotor magnet 15a Magnetic pole boundary 20 Stator 21 Stator core 21a Magnetic steel plate 22 Insulator 23 Coil 24 Stator core groove 25 Stator core back yoke 26, 26a, 26b, 26c, 26d, 26e, 26f, 26g, 26h, 26i Stator pole part of stator core 27 Tip part of salient pole part 27a, 27b Part of tip part 28 Salient pole part main body 29 Through hole of salient pole part 30 Bearing Parts 31, 32 Bearing 40 Bearing holder 41 Inner cylinder part of bearing holder 42 Bearing holder collar 43 Bearing holder outer cylinder part 44 Bearing holder projection part 50 Mounting plate 51 Mounting plate mounting hole 52 Mounting plate passage hole 61 Circuit board 61 Circuit board through-hole 62 Elastic body 70 Housing 71 Housing cylindrical portion 72 Housing bottom 72a Housing passage hole 80 Cover 80a Cover through-hole 81 Cover lid portion 82 Cover cylindrical portion 91a, 91b Connecting hole 92a, 92b Projection Part GP1, GP2 Magnetic steel plate group IN1, IN2, IN3 Inner peripheral surface R Rotating shaft

Claims (12)

A stator core;
A rotor that rotates about a rotation axis with respect to the stator core;
A bearing that rotatably supports the rotor;
A bearing holder for holding the bearing portion;
A housing including a housing cylindrical portion,
The stator core is fixed to the inner peripheral surface of the housing cylindrical portion,
An inner rotor type motor in which the stator core and the bearing holder are fitted. The housing further includes a bottom portion extending in an inner diameter direction from the housing cylindrical portion,
The bearing holder is
An inner cylinder portion for holding the bearing portion;
An outer cylinder provided on the outer diameter side of the inner cylinder;
A holder-side fitting portion that is provided at one end of the outer cylinder portion in the direction of the rotation axis and is fitted to the stator core;
2. The inner rotor type motor according to claim 1, further comprising a flange part that connects the inner cylinder part and the outer cylinder part to each other and is fixed to the bottom part. The stator core is
A back yoke having an annular shape;
A plurality of salient pole portions protruding in an inner diameter direction from the back yoke,
The inner rotor type motor according to claim 2, wherein at least two salient pole portions of the plurality of salient pole portions include salient pole portion side fitting portions that fit with the holder side fitting portion.   4. The inner rotor according to claim 3, wherein the salient pole part-side fitting part is a groove formed continuously at the other end part in the rotation axis direction and the inner diameter side end part of the at least two salient pole parts. Type motor.   5. The inner rotor type motor according to claim 4, wherein the salient pole portion-side fitting portion is formed at a position deviated from a circumferential central portion of each of the at least two salient pole portions.   The inner peripheral surface of the at least two salient pole portions, the inner peripheral surface of the holder-side fitting portion, and the inner peripheral surface of the outer cylinder portion are present on the outer diameter side of the outer peripheral surface of the rotor. The inner rotor type motor according to any one of 3 to 5. The stator core is composed of a plurality of core plates stacked in the rotation axis direction,
The plurality of core plates are disposed on a side away from the holder-side fitting portion and a first core plate constituted by at least one core plate arranged on a side close to the holder-side fitting portion. A second core plate constituted by a plurality of core plates,
Each of the plurality of salient pole parts is
A salient pole body around which a coil is wound;
A tip provided on the inner diameter side of the salient pole body, and
The salient pole part side fitting part is a through hole formed in the tip part of the at least two salient pole parts in the core plate constituting the first core plate,
Each of the plurality of core plates constituting the second core plate protrudes in the same direction along the rotation axis at a position overlapping with the through hole when viewed in a plane having the rotation axis as a normal line. The inner rotor type motor according to claim 3, wherein each of the plurality of core plates constituting the second core plate is coupled to each other by fitting of the core plate protrusions.   The inner rotor type motor according to any one of claims 3 to 7, wherein the salient pole part side fitting part is formed on an inner diameter side of a position where a coil in the stator core is wound.   The inner rotor type motor according to any one of claims 3 to 8, wherein the salient pole part-side fitting part is formed on the entire tip part of the at least two salient pole parts along the rotation axis. .   The salient pole part side fitting part is formed in a number of salient pole parts corresponding to a natural number multiple of the number of phases of the coil wound around the stator core among the plurality of salient pole parts, and is in a line-symmetrical position. The inner rotor type motor according to any one of claims 3 to 9, wherein the inner rotor type motor is formed on a salient pole portion that exists. The bearing portion includes two bearings,
The inner rotor type motor according to any one of claims 2 to 10, wherein the flange portion connects a position between the two bearings in the inner cylinder portion and the outer cylinder portion. The housing further includes a passage hole through which the bearing holder passes.
The inner rotor type motor according to any one of claims 2 to 11, wherein an inner peripheral surface of the passage hole and an outer peripheral surface of the bearing holder are opposed to each other with an interval therebetween.

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