JP2013013243A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact motor having improved operational efficiency.SOLUTION: In a portion where a rotor yoke 11 and a rotor cup 14 faces each other, air gaps 15 are formed in regions including spaces between adjacent magnetic pole portions 12 and 12. Fitting portions 17 are formed in spaces between the circumferentially adjacent air gaps 15 and 15. Each of the fitting portions 17 has a projection 11b, and a depression 40b, that fix the rotor yoke 11 and the rotor cup 14.

Description

  The present invention relates to a rotor yoke holding structure applicable to an electric motor, in particular, both an outer rotor type electric motor and an inner rotor type electric motor.

  Conventionally, as an electric motor, for example, a plurality of permanent magnets are arranged on the inner peripheral side (or outer peripheral side) of the rotor yoke, and an electric current is applied to a stator coil arranged opposite to the inner peripheral (or outer peripheral side) of the rotor to generate the coil. An outer rotor type (or inner rotor type) electric motor configured to rotate a rotor by a rotating magnetic field is known.

  In the electric motor described in Patent Document 1, a plurality of ribs projecting in the radial direction are formed on the inner peripheral surface of the impeller that holds the rotor yoke, and the rotor yoke is press-fitted into the rib, whereby the inner peripheral surface of the impeller and the outer periphery of the rotor yoke The rotor yoke is held while forming a gap with the surface.

  Further, in the electric motor described in Patent Document 2, two peripheral wall portions made of materials having different thermal expansion coefficients are formed on the inner peripheral surface of the cup-type rotor hub holding the rotor yoke so as to be separated from each other in the axial direction, and the rotor yoke is formed on the peripheral wall portion. By crimping, the rotor yoke is held while forming a gap between the inner peripheral surface of the cup-type rotor hub and the outer peripheral surface of the rotor yoke.

  By the way, in an electric motor having a rotor yoke that holds a permanent magnet, when stress is generated in the rotor yoke, the direction of the magnetic field is difficult to change due to the stress. Hysteresis loss occurs due to an increase in energy required for magnetic field change for driving by this, but by generating a fitting pressure in a part like the motors described in Patent Documents 1 and 2, Hysteresis loss can be suppressed.

JP 2009-234331 A Japanese Patent No. 2990304

  However, between the rotor yoke and the holding member that holds the rotor yoke (corresponding to an impeller in Patent Document 1 and a cup-type rotor hub in Patent Document 2), magnetic flux leakage is particularly likely to occur between adjacent magnetic pole portions. When magnetic flux leakage occurs, the eddy current loss generated in the holding member is generally larger than the eddy current loss generated in the rotor yoke. In the electric motors described in Patent Documents 1 and 2, no consideration is given to the positional relationship between the fitting portion and the magnetic pole portion.

  In addition, in the electric motors described in Patent Documents 1 and 2, since the rotor yoke is held only by the surface pressure generated between the rotor yoke and the holding member, there is a risk that slip torque may be generated due to temperature change or aging deterioration of the use environment. is there. In order to suppress the generation of slip torque, it is necessary to increase the size of the rotor yoke and the holding member so as to withstand press-fitting stress and centrifugal force.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electric motor that can be reduced in size while improving operating efficiency.

In order to achieve the above object, the invention according to claim 1
An annular rotor yoke made of a magnetically permeable material (for example, rotor yokes 11 and 51 in the embodiments described later);
A holding member (for example, rotor cups 14 and 14A and rotor holder 54 in the embodiments described later) disposed on the radially inner side or radially outer side of the rotor yoke and holding the rotor yoke;
A rotor having a plurality of magnetic pole portions (for example, magnetic pole portions 12 and 52 in the embodiments described later) provided at predetermined intervals in the circumferential direction on the rotor yoke and arranged so that adjacent magnetic poles have different polarities ( For example, rotors 10 and 50) in embodiments described later,
An electric motor including a stator (e.g., stators 20 </ b> A and 20 </ b> B in embodiments described later) provided with a plurality of coils (e.g., coils 22 in embodiments described later) disposed so as to face the rotor in the radial direction. For example, an outer rotor type electric motor 1A and an inner rotor type electric motor 1B) in an embodiment described later,
A gap portion (for example, gap portions 15 and 55 in the embodiments described later) is formed in a region including the gap between the adjacent magnetic pole portions, and is adjacent in the circumferential direction at the facing portion between the rotor yoke and the holding member. Consists of convex portions (for example, convex portions 11b and 51b in the embodiments described later) and concave portions (for example, concave portions 40b and 54b in the embodiments described later) for fixing the rotor yoke and the holding member between the gap portions. A fitting part (for example, fitting parts 17 and 57 in an embodiment described later) is formed.

In addition to the configuration of claim 1, the invention according to claim 2
The fitting portion is provided at a circumferential center of the magnetic pole portion.

In addition to the configuration of claim 1 or 2, the invention according to claim 3
The protrusion formed on one of the rotor yoke and the holding member and the recess formed on the other of the rotor yoke and the holding member are press-fitted and fixed by the fitting portion.

In order to achieve the above object, the invention according to claim 4 provides:
An annular rotor yoke made of a magnetically permeable material (for example, a rotor yoke 11 in an embodiment described later);
A holding member (for example, a rotor cup 14B in an embodiment described later) disposed on the radially outer side of the rotor yoke and holding the rotor yoke;
A rotor (for example, a magnetic pole part 12 in an embodiment described later) provided in the rotor yoke at a predetermined interval in the circumferential direction and arranged so that adjacent magnetic poles have different polarities (for example, a magnetic pole part 12 in an embodiment described later) A rotor 10) in an embodiment described later;
An electric motor (e.g., a stator (e.g., a stator 20 </ b> A in an embodiment described later)) that is disposed so as to face the rotor in the radial direction and includes a plurality of coils (e.g., a coil 22 in an embodiment described later). An outer rotor type electric motor 1A) in an embodiment described later,
In the region including between the adjacent magnetic pole portions, the outer peripheral surface of the rotor yoke is exposed from the holding member,
In a region overlapping with a part of the magnetic pole portion in the circumferential direction, a convex portion (for example, a convex portion 11b in an embodiment described later) and a concave portion (for example, described later) that selectively fix the rotor yoke and the holding member. The fitting part (For example, the fitting part 17 in embodiment mentioned later) comprised from the convex part 40b) of this embodiment is formed.

The invention according to claim 5 includes, in addition to the configuration of claim 4,
The fitting portion is provided at a circumferential center of the magnetic pole portion.

The invention according to claim 6 includes, in addition to the configuration of claim 4 or 5,
The protrusion formed on one of the rotor yoke and the holding member and the recess formed on the other of the rotor yoke and the holding member are press-fitted and fixed by the fitting portion.

  According to the first aspect of the present invention, the gap between the rotor yoke and the holding member is formed between the magnetic pole portions where the magnetic flux is particularly large, so that the magnetic flux is prevented from flowing into the rotor cup. Even if the radial width is not increased, eddy current loss can be suppressed, motor efficiency can be improved, and the electric motor can be downsized. Further, by forming a fitting portion composed of a convex portion and a concave portion for fixing the rotor yoke and the holding member between the gap portions adjacent in the circumferential direction, there is no need to press-fit the rotor yoke over the entire circumference. It is possible to prevent the generation of stress in the portion and reduce the hysteresis loss due to the residual stress.

  According to the second aspect of the present invention, the hysteresis loss can be further suppressed by providing the fitting portion at the center in the circumferential direction of the magnetic pole portion with a small change in magnetic flux density.

  According to invention of Claim 3, generation | occurrence | production of a noise and a vibration can be suppressed by press-fitting and fixing by a fitting part.

  According to the invention of claim 4, since the outer peripheral surface of the rotor yoke is exposed from the holding member, the region including between the adjacent magnetic pole portions is formed, so that the magnetic flux to the holding member between the magnetic pole portions where the magnetic flux wraps around is large. The wraparound is suppressed, and the eddy current loss can be suppressed and the motor efficiency can be improved without increasing the radial width of the rotor yoke, and the electric motor can be downsized. In addition, in the region overlapping with a part of the magnetic pole portion in the circumferential direction, a fitting portion composed of a convex portion and a concave portion for selectively fixing the rotor yoke and the holding member is formed, so that the rotor yoke is entirely Therefore, it is not necessary to press-fit over the entire area, stress generation at other portions can be prevented, and hysteresis loss due to residual stress can be reduced.

  According to the invention of claim 5, the hysteresis loss can be further suppressed by providing the fitting portion at the center in the circumferential direction of the magnetic pole portion with a small change in magnetic flux density.

  According to invention of Claim 6, generation | occurrence | production of a noise and a vibration can be suppressed by press-fitting and fixing by a fitting part.

It is sectional drawing of the outer rotor type | mold electric motor of 1st Embodiment of this invention. It is a front view of the outer rotor shown in FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is a front view of the outer rotor of the 1st modification. It is a perspective view of the outer rotor of the 2nd modification. It is sectional drawing of the inner rotor type electric motor of 2nd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
<First Embodiment>
As shown in FIGS. 1 to 3, the outer rotor type electric motor 1 </ b> A of the present embodiment includes a stator 20 </ b> A and an annular rotor 10 that is disposed opposite to the outer side in the radial direction of the stator 20 </ b> A via a slight gap. It is prepared for.

  The stator 20A includes a stator core 21 in which a plurality of teeth project radially toward the outer side in the radial direction, and a plurality of coils 22 arranged in a substantially annular shape as a whole by being wound around each tooth via an insulator. Is provided.

  The rotor 10 has a substantially annular rotor yoke 11, a plurality of magnetic pole portions 12 made of permanent magnets 12 a fixed to the inner peripheral surface of the rotor yoke 11, a rotor shaft 11 that holds the rotor yoke 11 radially inward, and a rotating shaft (not shown). ) And a disc-shaped rotor cup 14 which is fixed to the outer periphery. The rotating shaft is rotatably supported with respect to the motor housing by a bearing (not shown), and the rotor 10 is driven to rotate about the axis O by a rotating magnetic field generated by the stator 20A.

  The rotor yoke 11 is configured by laminating a plurality of annular electromagnetic steel plates made of a magnetically permeable material in the axial direction, and a plurality (four in this embodiment) projecting radially outward on the outer peripheral surface 11a. Convex portions 11b are formed at predetermined intervals in the circumferential direction.

  The plurality of magnetic pole portions 12 are alternately provided in the circumferential direction so that adjacent magnetic poles in the circumferential direction are different from each other, and each magnetic pole portion 12 includes two permanent magnets 12a. In addition, each magnetic pole part 12 may be comprised with the one permanent magnet 12a.

  The rotor cup 14 is made of a steel material, and a shaft connecting portion 41 connected to the rotating shaft is integrally formed on one end side in the axial direction of the annular portion 40 disposed on the radially outer side of the stator 20A. The end side is open. On the inner circumferential surface 40a of the annular portion, voids 15 that are recessed outward in the radial direction are arranged at predetermined intervals in the circumferential direction. The gap portion 15 is provided between the magnetic pole portions 12 and 12 adjacent in the circumferential direction, and is provided so as to overlap the magnetic pole portions 12 and 12 adjacent in the circumferential direction in the circumferential direction. Further, the gap 15 has an axial length that is substantially equal to the axial length of the rotor yoke 11 or is set to be equal to or longer than the axial length of the rotor yoke 11.

Here, the reason why the gap 15 is provided will be described.
As a result of intensive studies by the present inventors, when the rotor cup 14 is made of steel, the magnetic flux to the rotor cup 14 is particularly generated between the magnetic pole portions 12 and 12 adjacent to each other in the circumferential direction (hereinafter also referred to as a region between the magnetic pole portions). It turns out that wraparound occurs. This wraparound can be avoided by sufficiently increasing the radial width (hereinafter also referred to as the rotor yoke width), which is the radial thickness of the rotor yoke 11, but the rotor yoke width is determined by the rotor cup due to restrictions on the mountability to the vehicle. 14 is set irrespective of the wraparound of the magnetic flux to 14.

  Since this wrap-around occurs beyond the region between the magnetic pole portions, the air gap portion 15 is provided as a flux barrier by providing the air gap portion 15 so as to overlap the magnetic pole portions 12 and 12 adjacent in the circumferential direction in the circumferential direction. It functions and can effectively suppress the magnetic flux from flowing into the rotor cup 14. On the other hand, it is known that as the distance from the magnetic pole part region is increased, the amount of magnetic flux is reduced, so that the required rotor yoke width is reduced, and the magnetic flux wraps around the rotor cup 14 even without the gap part 15.

  Therefore, in the present embodiment, the gap 15 is provided in the vicinity of the region between the magnetic pole portions of the inner circumferential surface 40a of the annular portion and in the vicinity thereof to prevent the magnetic flux from entering the rotor cup 14, and the magnetic poles of the inner circumferential surface 40a of the annular portion A recess 40 b that selectively fits with the protrusion 11 b of the rotor yoke 11 is provided in a place away from the inter-region.

  Further, the recess 40b is formed between the gaps 15 adjacent in the circumferential direction and so as to be recessed radially outward from the annular inner peripheral surface 40a of the rotor cup 14, and together with the protrusion 11b of the rotor yoke 11, the fitting portion 17 is formed. Configure. By fitting the convex portion 11 b of the rotor yoke 11 into the concave portion 40 b of the rotor cup 14, the fitting pressure is relatively increased and the rotor yoke 11 is fixed to the rotor cup 14. Accordingly, the rotational power from the rotor yoke 11 is transmitted to the rotor cup 14 via the fitting portion 17 to rotate a rotating shaft (not shown). Conversely, the rotation of the rotating shaft is transmitted from the rotor cup 14 to the rotor yoke 11 via the fitting portion 17.

  In the fitting part 17, it is preferable that the outer peripheral surface of the convex part 11b and the inner peripheral surface of the recessed part 40b are fixed by press-fitting. As a result, the rotor yoke 11 is securely fixed to the rotor cup 14. At this time, it is preferable that the circumferential direction both end surfaces of the convex part 11b and the circumferential direction both end surfaces of the recessed part 40b are fixed by light press-fitting. Thereby, generation | occurrence | production of a noise and a vibration is suppressed.

  Moreover, it is preferable that this fitting part 17 is provided in the circumferential center of each magnetic pole part 12. Since the magnetic flux wraps around the rotor cup 14 at the center in the circumferential direction of each magnetic pole portion 12, hysteresis loss is small even if the fitting portion 17 is formed at the circumferential center of each magnetic pole portion 12.

  In this embodiment, four fitting parts 17 are formed at equal intervals in the circumferential direction. However, the number of fitting parts 17, the circumferential width, height, and axial length of the convex part 11 b are determined according to the electric motor. It is set as appropriate so as to satisfy the required strength based on the maximum torque. In order to increase the required strength, it is effective to increase the number of fitting portions 17, increase the circumferential width and axial length of the convex portion 11b, or reduce the height of the convex portion 11b. The shape of the concave portion 40b can be adjusted according to the shape of the convex portion 11b.

  As described above, in the outer rotor type electric motor 1A of the present embodiment, the annular inner circumferential surface 40a of the rotor cup 14 and the outer circumferential surface 11a of the rotor yoke 11 are opposed to each other in the radial direction to form an opposed portion. Is formed with a gap 15 in a region including between the magnetic pole parts 12 adjacent to each other in the circumferential direction, and a fitting part 17 is formed between the gaps 15 adjacent to each other in the circumferential direction. Therefore, according to the present embodiment, the air gap portion 15 prevents the magnetic flux from entering the rotor cup 14 and suppresses the eddy current loss and improves the motor efficiency without increasing the radial width of the rotor yoke 11. The electric motor can be reduced in size.

  Moreover, since the fitting part 17 is comprised from the recessed part 40b formed in the annular part inner peripheral surface 40a and the convex part 11b formed in the rotor yoke 11, it is not necessary to press-fit the rotor yoke 11 over the perimeter. Hysteresis loss due to residual stress can be reduced.

  Moreover, the fitting part 17 can suppress a hysteresis loss more by providing in the circumferential direction center of the magnetic pole part 12 with few magnetic flux density changes.

  Further, in the case of the outer rotor type electric motor 1A, since the tensile stress due to the press-fitting of the rotor yoke 11 is lowered by the generated stress of the rotor cup 14, the required strength can be reduced, the cost is reduced by the thinning, and the flexibility of layout. Can be improved.

FIG. 4 shows a first modification of the present embodiment.
In this modification, the gap portion 15A formed in the rotor cup 14A continuously forms one gap portion between the fitting portions 17 adjacent in the circumferential direction. Thereby, the rotor cup 14A can be reduced in weight. As described above, the gap portion only needs to be provided in the region between the magnetic pole portions, and may be formed so as to overlap with a part of the magnetic pole portion 12 as in the above-described embodiment. It may be formed across a plurality of magnetic pole portions 12.

FIG. 5 shows a second modification of the present embodiment.
In this modification, the rotor cup 14B is configured by a plurality of (four in this embodiment) shaft coupling portions 41 in which the edge portions 43 are formed only at the portions where the fitting portions 17 are formed. It is held on the inner side in the radial direction and is fixed to the rotating shaft. In the portion where the fitting portion 17 is not formed, the outer peripheral surface 11a of the rotor yoke 11 is exposed from the rotor cup 14B into the motor housing without the edge 43 of the rotor cup 14B.

  That is, in this modification, the region including the area between the adjacent magnetic pole portions 12 and 12 is formed by exposing the outer peripheral surface 11a of the rotor yoke 11 from the rotor cup 14B. Thus, the wraparound of the magnetic flux to the rotor cup 14B is suppressed, and the eddy current loss can be suppressed and the motor efficiency can be improved without increasing the radial width of the rotor yoke 11, and the electric motor can be downsized. Further, the region overlapping with a part of the magnetic pole portion 12 in the circumferential direction is composed of a convex portion 11b and a concave portion 40b that are selectively fixed by relatively increasing the fitting pressure between the rotor yoke 11 and the rotor cup 14B. Since the fitting portion 17 is formed, it is not necessary to press-fit the rotor yoke 11 over the entire circumference, and stress generation at other portions can be prevented, and hysteresis loss due to residual stress can be reduced.

Second Embodiment
Next, an inner rotor type electric motor according to a second embodiment of the present invention will be described.
As shown in FIG. 6, the inner rotor type electric motor 1 </ b> B of the present embodiment includes a stator 20 </ b> B and an annular rotor 50 that is disposed opposite to the inner side in the radial direction of the stator 20 </ b> B with a slight gap. Is done.

  The stator 20B includes a stator core 21 having a plurality of teeth projecting radially inward in the radial direction, and a plurality of coils 22 arranged in a generally annular shape by being wound around each tooth via an insulator. Is provided.

  The rotor 50 is fixed to a substantially annular rotor yoke 51, a plurality of magnetic pole portions 52 made of permanent magnets 52a embedded radially outside the rotor yoke 51, and the flange portion 31 of the rotary shaft 30, and the rotor yoke 51 is placed radially outward. And a rotor holder 54 to be held. The rotating shaft 30 is rotatably supported with respect to the motor housing by a bearing (not shown), and the rotor 50 is rotationally driven around the axis O by a rotating magnetic field generated by the stator 20B.

  The rotor yoke 51 is configured by laminating a plurality of annular electromagnetic steel plates made of a magnetically permeable material in the axial direction. ) Convex portions 51b are formed at predetermined intervals in the circumferential direction.

  The plurality of magnetic pole portions 52 are alternately provided in the circumferential direction so that adjacent magnetic poles in the circumferential direction are different from each other, and each magnetic pole portion 52 includes two permanent magnets 52a. Each magnetic pole part 52 may be constituted by one permanent magnet 52a.

  The rotor holder 54 is made of a steel material, and a plurality (four in this embodiment) of void portions 55 that are recessed radially inward are arranged at equal intervals in the circumferential direction on the holder outer peripheral surface 54a. The plurality of gaps 55 are formed so as to cover all the regions between the magnetic poles 52 and 52 adjacent in the circumferential direction. Further, the gap portion 55 has an axial length that is substantially equal to the axial length of the rotor yoke 51 or is set to be equal to or longer than the axial length of the rotor yoke 51.

  The reason for providing the gap portion 55 is to make it function as a flux barrier as in the first embodiment. By providing the gap portion 55, the rotor yoke 51 to the rotor holder 54 at the opposed portion of the rotor holder 54 and the rotor yoke 51 is provided. The wraparound of the magnetic flux, particularly the wraparound of the magnetic flux from the rotor yoke 51 to the rotor holder 54 between the magnetic pole portions 52 and 52 adjacent in the circumferential direction can be effectively suppressed.

  Further, the outer circumferential surface 54a of the rotor holder 54 is fitted between the convex portion 51b of the rotor yoke 51 so as to overlap with a part of the magnetic pole portion 52 in the circumferential direction between the gap portions 55 adjacent in the circumferential direction. The recess 54b is formed so as to be recessed radially inward from the holder outer peripheral surface 54a of the rotor holder 54. The concave portion 54 b constitutes a fitting portion 57 together with the convex portion 51 b of the rotor yoke 51. By fitting the convex portion 51 b of the rotor yoke 51 into the concave portion 54 b of the rotor holder 54, the fitting pressure is relatively increased and the rotor yoke 51 is fixed to the rotor holder 54. Accordingly, the rotational power from the rotor yoke 51 is transmitted to the rotor holder 54 via the fitting portion 57, and the rotation shaft is rotated. Conversely, the rotation of the rotating shaft is transmitted from the rotor holder 54 to the rotor yoke 51 via the fitting portion 57.

  In the fitting part 57, it is preferable that the outer peripheral surface of the convex part 51b and the inner peripheral surface of the recessed part 54b are fixed by press-fitting. Thereby, the rotor yoke 51 is securely fixed to the rotor holder 54. At this time, it is preferable that the circumferential direction both end surfaces of the convex part 51b and the circumferential direction both end surfaces of the recessed part 54b are fixed by light press-fitting. Thereby, generation | occurrence | production of a noise and a vibration is suppressed.

  The fitting portion 57 is preferably provided at the center in the circumferential direction of each magnetic pole portion 52. Since the magnetic flux around the rotor holder 54 is small at the center in the circumferential direction of each magnetic pole portion 52, even if the fitting portion 57 is formed at the center in the circumferential direction of each magnetic pole portion 52, the hysteresis loss is small.

  Also in this embodiment, the number of fitting parts 57, the width in the circumferential direction of the convex part 51b, the height, and the axial length are appropriately adjusted so as to satisfy the required strength based on the maximum torque of the electric motor. .

  As described above, in the inner rotor type electric motor 1B of the present embodiment, the holder inner peripheral surface 54a of the rotor holder 54 and the outer peripheral surface 51a of the rotor yoke 51 face each other in the radial direction to form a facing portion. A gap portion 55 is formed in a region including between the magnetic pole portions 52 and 52 adjacent in the circumferential direction, and a fitting portion 57 is formed between the gap portions 55 and 55 adjacent in the circumferential direction. Therefore, also in the present embodiment, the gap portion 55 suppresses the magnetic flux from entering the rotor holder 54, and the eddy current loss can be suppressed and the motor efficiency can be improved without increasing the radial width of the rotor yoke 51. The electric motor can be reduced in size.

  Since the fitting portion 57 is composed of a concave portion 54b formed on the holder inner peripheral surface 54a and a convex portion 51b formed on the rotor yoke 51, there is no need to press-fit the rotor yoke 51 over the entire circumference, and residual stress It is possible to reduce the hysteresis loss due to.

  Further, in the fitting portion 57, the rotor yoke 11 and the rotor holder 54 are fixed by fitting the convex portion 51b and the concave portion 54b. Therefore, the fitting portion 57 can be formed relatively small, and the inner rotor type electric motor 1B can be reduced in size. Can be

  Moreover, the fitting part 57 can suppress a hysteresis loss more by providing in the circumferential direction center of the magnetic pole part 52 with few magnetic flux density changes.

  Further, in the case of the inner rotor type electric motor 1B, since the stress generated in the rotor yoke 51 is only centrifugal force, the required required strength can be reduced, and the use of a high strength electrical steel sheet can be eliminated.

In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, as a fitting part, the convex part 11b formed in the rotor yoke 11, the fitting part 17 which consists of the recessed part 40b formed in the rotor cup 14, the convex part 51b formed in the rotor yoke 51, and the concave part 54b formed in the rotor holder 54 However, the relationship between the convex part and the concave part may be reversed. That is, a recess may be formed in the rotor yoke, and a protrusion may be formed in a holding member such as a rotor cup or a rotor holder to constitute the fitting portion.
Further, the rotor holder 54 may be formed integrally with the flange portion 31 of the rotating shaft 30.

1A Outer rotor type electric motor 1B Inner rotor type electric motor 10, 50 Rotor 11, 51 Rotor yoke 11b, 51b Convex part 12, 52 Magnetic pole part 14, 14A, 14B Rotor cup 15, 55 Gap part 17, 57 Fitting part 20A, 20B Stator 22 Coil 40b, 54b Recess 54 Rotor holder

Claims (6)

An annular rotor yoke made of a magnetically permeable material;
A holding member that is disposed radially inside or radially outside the rotor yoke and holds the rotor yoke;
A rotor provided with a plurality of magnetic pole portions provided in the rotor yoke at predetermined intervals in the circumferential direction and arranged so that adjacent magnetic poles have different polarities,
A stator that is arranged to face the rotor in the radial direction and includes a plurality of coils,
A gap portion is formed in a region including the gap between the adjacent magnetic pole portions at a facing portion between the rotor yoke and the holding member, and the rotor yoke and the holding member are fixed between the gap portions adjacent in the circumferential direction. An electric motor characterized in that a fitting portion comprising a convex portion and a concave portion is formed.   The electric motor according to claim 1, wherein the fitting portion is provided at a circumferential center of the magnetic pole portion.   The convex portion formed on one of the rotor yoke and the holding member and the concave portion formed on the other of the rotor yoke and the holding member are press-fitted and fixed by the fitting portion. 2. The electric motor according to 2. An annular rotor yoke made of a magnetically permeable material;
A holding member that is disposed radially outside the rotor yoke and holds the rotor yoke;
A rotor provided with a plurality of magnetic pole portions provided in the rotor yoke at predetermined intervals in the circumferential direction and arranged so that adjacent magnetic poles have different polarities,
A stator that is arranged to face the rotor in the radial direction and includes a plurality of coils,
In the region including between the adjacent magnetic pole portions, the outer peripheral surface of the rotor yoke is exposed from the holding member,
A fitting portion composed of a convex portion and a concave portion for selectively fixing the rotor yoke and the holding member is formed in a region overlapping with a part of the magnetic pole portion in the circumferential direction. Electric motor.   The electric motor according to claim 4, wherein the fitting portion is provided in a circumferential center of the magnetic pole portion.   The convex portion formed on one of the rotor yoke and the holding member and the concave portion formed on the other of the rotor yoke and the holding member are press-fitted and fixed by the fitting portion. 5. The electric motor according to 5.

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