Rotor unit, rotating electric machine and method for manufacturing a rotor unit

Abstract

Rotor unit (32) for a rotating electric machine (1), wherein the rotor unit (32) has the following features: a ring-shaped rotor core (41) comprising a plurality of steel layers (411) laminated vertically; a plurality of magnets (43) arranged in a circumferential direction around the rotor core (41); and a holder (42) made of resin and arranged to hold the plurality of magnets (43); wherein the holder (42) comprises a plurality of partitioning sections (60) extending vertically along an outer peripheral surface of the rotor core (41), and a coupling section (70) connecting the plurality of partitioning sections (60); wherein the rotor core (41) and the holder (42) are made of a cast material in order to be fixed to each other; wherein a resin section defining the holder (42) is present between the plurality of steel layers (411) defining the rotor core (41) in the outer peripheral surface of the rotor core (41); and wherein the majority of magnets (43) are pressed between adjacent partitioning sections (60), wherein each of the partitioning sections (60) includes the following features: a column-shaped section (62) extending radially between a pair of the plurality of magnets (43) that are adjacent to each other; an engagement section (61) extending radially from the column-shaped section (62) into a vertically extending groove section (52) formed in the outer peripheral surface of the rotor core (41), wherein the engagement section (61) engages the groove section (52); and a wall section (63) extending circumferentially from the columnar section (62), the upper end of which is located at a lower position than an upper end of the columnar section (62), and which partially covers a radial outer surface of the pair of the plurality of magnets (43); and wherein an inner peripheral surface of the wall section (63) comprises an inclined surface (631) which gradually approaches the outer peripheral surface of the rotor core (41) from an upper end downwards.

Description

[0001] The present invention relates to a rotor unit, a rotating electrical machine and a method for manufacturing a rotor unit.

[0002] An internal rotor-type motor is known from the prior art, which rotates a rotor unit with magnets inside a coil. WO 2006 / 008964 A1, for example, discloses a brushless motor with a stator and a rotor (rotor) arranged inside the stator.

[0003] The rotor of WO 2006 / 008964 A1 comprises a rotor shaft, a rotor core, a magnet holder, and six rotor magnets. Paragraph

[0026] of WO 2006 / 008964 A1 discloses that the rotor core is fixed to the rotor shaft, and the six rotor magnets are attached to an outer periphery of the rotor core. Additionally, paragraph

[0027] of WO 2006 / 008964 A1 discloses that the magnet holder is fixed to the rotor shaft.

[0004] Additionally, paragraph

[0029] of WO 2006 / 008964 A1 discloses that a fitting projection of the magnet holder is fitted into an electrode holder mounting groove formed on an outer peripheral portion of the rotor core. In WO 2006 / 008964 A1, such a fitting piece prevents a holder arm of the magnet holder from sliding out of the rotor core in a radial direction.

[0005] However, WO 2006 / 008964 A1 does not teach or suggest how to achieve axial fixation strength between the rotor core and the magnet holder. In particular, if the rotor core and the magnet holder are not firmly fixed in an axial direction when the magnets are press-fitted to the magnet holder in the axial direction, there is a problem that the rotor core and the magnet holder may be separated from each other due to the stress at the time of press-fitting.

[0006] JP 2011-67057 A discloses a brushless motor with a rotor core, magnets, and a magnet holder made of a resin. The rotor core contains grooves into which projections of arms engage, allowing the magnets to be pressed between the arms of the magnet holder.

[0007] US 4 910 861 A describes a rotor assembly for an electric motor and a method for its manufacture, in which a plurality of arcuate permanent magnets are arranged in angularly connected adjacent positions to surround the outer circumference of a rotor core. The exposed outer peripheral surfaces of the magnets are encapsulated by means of a plastic-molded sleeve to secure them in fixed position on the core.

[0008] The present invention is based on the object of providing an improved rotor unit, a rotating electrical machine comprising a rotor unit and a method for producing a rotor unit.

[0009] This object is achieved by a rotor unit according to claim 1, a rotating electrical machine according to claim 6 and by a method for producing a rotor unit according to claim 7.

[0010] Advantageous further developments of the invention are specified in the subclaims.

[0011] According to embodiments of the present invention, a resin portion defining the retainer is provided in the outer peripheral surface of the rotor core between the plurality of steel sheets defining the rotor core. This improves the fixing strength of the rotor core and the retainer.

[0012] According to embodiments of the present invention, the manufacturing process of the rotor core and the holder is shortened by molding. Additionally, a resin portion defining the holder is provided between the plurality of steel sheets defining the rotor core. This improves the fixing strength of the rotor core and the holder. Furthermore, since separation between the rotor core and the holder is prevented, the plurality of magnets can be easily press-fitted.

[0013] Embodiments of the present invention achieve an improvement in the perpendicular alignment of the upper end surface of the thrust portion with respect to the outer surface of the shaft.

[0014] The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings. Fig. 1 is a perspective view of a rotor unit according to a preferred embodiment of the present invention. Fig. 2 is a longitudinal sectional view in the vicinity of a boundary portion between a rotor core and a holder according to a preferred embodiment of the present invention. Fig. 3 is a longitudinal sectional view of an engine according to a preferred embodiment of the present invention. Fig. 4 is a perspective view of the rotor unit according to a preferred embodiment of the present invention. Fig. 5 is a plan view of the rotor unit according to a preferred embodiment of the present invention. Fig. 6 is a longitudinal sectional view of the rotor unit according to a preferred embodiment of the present invention. Fig. 7 is a partial perspective view of the rotor core and a magnet holder according to a preferred embodiment of the present invention. Fig. 8 is a flowchart showing a manufacturing process of the rotor unit according to a preferred embodiment of the present invention. Fig. 9 is a longitudinal sectional view showing the state where pouring is performed according to a preferred embodiment of the present invention. Fig. 10 is a partial longitudinal sectional view of the rotor unit according to a preferred embodiment of the present invention before a magnet is press-fitted. Fig. 11 is a partial longitudinal sectional view of the rotor assembly according to a preferred embodiment of the present invention after the magnet has been press-fitted.

[0015] Exemplary preferred embodiments of the present invention are described below with reference to the drawings. In addition, the shapes and positional relationships of respective portions are described such that a direction along the center axis of a rotating electrical machine is a vertical direction. However, this defines the vertical direction merely for convenience of description and does not limit the posture of a rotor unit and a rotating electrical machine according to various preferred embodiments of the present invention when used.

[0016] Fig. 1 is a perspective view of a rotor unit 32A for a rotating electrical machine in accordance with a preferred embodiment of the present invention. As shown in Fig. 1, the rotor unit 32A includes a rotor core 41A, a holder 42A, and a plurality of magnets 43A.

[0017] The rotor core 41A is preferably an annular member made, for example, of vertically laminated steel sheets. The holder 42A is a resin-made member that holds the magnets 43A. The holder 42A includes a plurality of partitioning portions 60A and a coupling portion 70A. The plurality of partitioning portions 60A each extend vertically along the outer peripheral surface of the rotor core 41A. The coupling portion 70A connects the plurality of partitioning portions 60A. The plurality of magnets 43A are arranged circumferentially around the rotor core 41A. Each magnet 43A is press-fitted into a pair of partitioning portions 60 that are adjacent to each other.

[0018] When manufacturing the rotor unit 32A, the rotor core 41A is first placed inside a mold. Then, resin is injected into the mold in a fluid state. By injecting the resin, the holder 42A is molded into a mold having the plurality of partitioning portions 60A and a coupling portion 70A. Thereafter, the magnet 43A is press-fitted between a pair of partitioning portions 60A that are adjacent to each other.

[0019] Thus, in the present preferred embodiment, the rotor core 41A and the holder 42A are fixed to each other by molding. Therefore, the manufacturing process of the rotor core 41A and the holder 42A is shortened. Fig. 2 is a longitudinal sectional view in the vicinity of a boundary portion between the rotor core 41A and the holder 42A. As shown in Fig. As shown in FIG. 2, a portion of the resin defining the holder 42A is provided in the outer peripheral surface of the rotor core 41A, directly adjacent to a plurality of steel sheets 411A defining the rotor core 41A. This firmly fixes the rotor core 41A and the holder 42A. In addition, since the separation between the rotor core 41A and the holder 42A is prevented, the magnets 43A can be easily press-fitted.

[0020] A more specific preferred embodiment of the present invention will be described below.

[0021] Fig. 3 is a longitudinal sectional view of the motor 1, which is an example of a rotating electrical machine manufactured according to a preferred embodiment of the present invention. The motor 1 of the present preferred embodiment is preferably mounted on an automobile and is used to generate a driving force for, for example, a power steering system. As shown in Fig. 3, the motor 1 comprises a fixed section 2 and a rotating section 3. The rotating section 3 is rotatably mounted with respect to the fixed section 2.

[0022] The fixed portion 2 of the present preferred embodiment preferably comprises a housing 21, a cover portion 22, an armature 23, a lower bearing 24 and an upper bearing 25.

[0023] The housing 21 is a bottomed, cylindrical or substantially cylindrical housing that houses the armature 23, the lower bearing 24, and the rotating portion 3. A recess 211 that holds the lower bearing 24 is located in the center of the bottom of the housing 21. The cover portion 22 is a flat or substantially flat plate-shaped member that closes an upper opening of the housing 21. A circular hole 321 that holds the upper bearing 25 is located in the center of the cover portion 22.

[0024] The armature 23 generates a magnetic flux in response to a drive current. The armature 23 includes a stator core 26 and a coil 27. The stator core 26 is made, for example, of laminated steel layers, with a plurality of steel layers laminated in an axial direction (ie, a direction along the central axis 9).

[0025] The stator core 26 preferably includes an annular core back 261 and a plurality of teeth 262 projecting from the core back 261 toward the inside in a radial direction (i.e., a direction orthogonal to the central axis 9). The core back 261 is fixed to the inner peripheral surface of the side wall of the housing 21. The coil 27 is preferably defined by conductive wires wound around each tooth 262 of the stator core 26.

[0026] The lower bearing 24 and the upper bearing 25 rotatably support a shaft 31 on the side of the rotating portion 3. Ball bearings that allow an outer ring and an inner ring to rotate relatively via balls are preferably used for the lower bearing 24 and the upper bearing 25 of the present preferred embodiment.

[0027] An outer ring 241 of the lower bearing 24 is preferably fixed to the recess 211 of the housing 21. In addition, an outer ring 251 of the upper bearing 25 is preferably fixed to the edge of the circular hole 221 of the cover portion 22. On the other hand, inner rings 242 and 252 of the lower bearing 24 and the upper bearing 25 are preferably fixed to the shaft 31. For this reason, the shaft 31 is rotatably supported with respect to the housing 21 and the cover portion 22.

[0028] The rotating portion 3 of the present preferred embodiment preferably includes the shaft 31, a pair of rotor units 32 and 33, and a cover 34.

[0029] The shaft 31 is preferably a cylindrical or substantially cylindrical member extending vertically along the central axis 9. The shaft 31 rotates about the central axis 9 and is supported by the above-described lower bearing 24 and upper bearing 25. In addition, the shaft 31 preferably includes a head 311 projecting upward from the cover portion 22. The head 311 is preferably coupled to a power steering device of an automobile via a power transmission mechanism, such as a gear.

[0030] The pair of rotor units 32 and 33 and the cover 34 rotate together with the shaft 31 radially within the armature 23. The pair of rotor units 32 and 33 preferably each includes a rotor core 41, a magnet holder 42, and a plurality of magnets 43. The pair of rotor units 32 and 33 are arranged in the axial direction in a state where the units are reversed. The detailed structure of the rotor units 32 and 33 is described below.

[0031] The cover 34 is a cylindrical or substantially cylindrical member that supports the pair of rotor units 32 and 33. The cover 34 is arranged to cover the outer peripheral surface of the rotor units 32 and 33 and portions of the upper and lower end surfaces of the rotor units. Therefore, the pair of rotor units 32 and 33 are preferably maintained in a state where the units are brought close to each other or brought into contact with each other.

[0032] In such a motor 1, when a drive current is applied to the coil 27 of the fixed portion 2, a radial magnetic flux is generated in the plurality of teeth 262 of the stator core 26. Then, a circumferential torque is generated by the action of the magnetic flux between the teeth 262 and the magnet 43, and the rotating portion 3 rotates about the central axis 9 with respect to the fixed portion 2. As the rotating portion 3 rotates, a driving force is transmitted to the power steering device coupled to the shaft 31.

[0033] As described above, the motor 1 of the present preferred embodiment preferably includes the pair of rotor units 32 and 33. The detailed structure of the rotor unit 32 arranged on the lower side will be described below. Although the rotor unit 33 is arranged on the upper side in a state where the rotor unit 32 arranged on the lower side is vertically reversed, since its structure is equivalent to that of the lower rotor unit 32, a repeated description thereof will be omitted.

[0034] Fig. 4 is a perspective view of the rotor unit 32. Fig. 5 is a plan view of the rotor unit 32. As shown in the Fig. 4 and Fig. 5, the rotor unit 32 includes the rotor core 41, the magnet holder 42, and the plurality of magnets 43.

[0035] The rotor core 41 is an annular member fixed to the shaft 31. The rotor core 41 is made of laminated steel sheets, with electromagnetic steel sheets being vertically laminated. The rotor core 41 of the present preferred embodiment has a regular polygonal columnar appearance. A through hole 51, which allows the shaft 31 to be inserted therethrough, is provided in the center of the rotor core 41. In addition, the outer peripheral surface of the rotor core 41 is provided with a plurality of groove portions 52 extending in the axial direction. The groove portions 52 are recessed radially inward at boundary portions of a plurality of planes defining the outer peripheral surface of the rotor core 41.

[0036] The magnet holder 42 is a resin-made component that holds the magnets 43. The magnet holder 42 includes a plurality of partitioning portions 60 and a coupling portion 70 that connects lower ends of the plurality of partitioning portions 60. The plurality of partitioning portions 60 are arranged at equal or substantially equal intervals in the circumferential direction. Each partitioning portion 60 extends in the axial direction along the side surface of the rotor core 41 in the vicinity of each groove portion 52 of the rotor core 41. The coupling portion 70 is a circular portion located below the plurality of partitioning portions 60. A radially inner portion of the coupling portion 70 comes into contact with the lower surface of the rotor core 41.

[0037] Fig. Figure 6 is a longitudinal sectional view of the rotor unit 32 seen from position AA in Fig. 5. In the present preferred embodiment, the magnet holder 42 is defined on the surface of the rotor core 41 in an integrated manner by overmolding. When overmolding is performed, resin is injected into a mold to be formed in a state where the rotor core 41 is previously placed within the mold. Then, the rotor core 41 and the magnet holder 42 are fixed to each other by curing the resin.

[0038] In Fig. 6 shows a portion of a boundary between the rotor core 41 and the magnet holder 42 in an enlarged manner. As shown in the enlarged view, gaps 412 are present between adjacent ones of the plurality of steel sheets 411 defining the rotor core 41 in the vicinity of the outer peripheral surface of the rotor core 41. A portion of the resin defining the magnet holder 42 is present in the gaps 412. This is provided as a resin in a fluid state that enters the gaps 412 of the rotor core 41 when molding is performed.

[0039] Regarding the rotor core 41 and the magnet holder 42 of the present preferred embodiment, both components slightly bite into each other at their boundary portions. Consequently, the rotor core 41 and the magnet holder 42 are firmly fixed. Specifically, resin is present in an axial gap formed between one steel layer 411 and an adjacent steel layer 411. For this reason, axial relative movement between the rotor core 41 and the magnet holder 42 is prevented.

[0040] The plurality of steel layers 411 defining the rotor core 41 are preferably obtained, for example, by stamping. For this reason, as shown in the enlarged view in Fig. 6, a curved portion 413 is formed at the end of each steel layer according to the direction of punching. In the present preferred embodiment, the curved portion 413 is curved toward an upper side. For this reason, upward detachment of the rotor core 41 with respect to the magnet holder 42 is further prevented.

[0041] In addition, each partitioning section 60 of the present preferred embodiment includes, as shown in the Fig. 4 and Fig. 5, an engaging portion 61 is held in each groove portion 52 of the rotor core 41. At the time of molding, the engaging portion 61 is defined when the resin that has flowed into the groove portion 52 hardens. For this reason, a gap is not easily generated between the engaging portion 61 and the rotor core 41 in the groove portion 52. Accordingly, the rotor core 41 and the magnet holder 42 are fixed even more firmly.

[0042] Specifically, in the present preferred embodiment, the engagement portion 61, whose widthwise dimension increases toward the inside in the radial direction, engages the groove portion 52, whose widthwise dimension decreases toward the inside in the radial direction. This further prevents radial separation of the rotor core 41 and the magnet holder 42.

[0043] The plurality of magnets 43 are arranged around the rotor core 41. Each magnet 43A is preferably arcuate or substantially arcuate on an outer diameter side thereof and linear or substantially linear on the inner diameter side thereof, and is press-fitted, for example, into a pair of partitioning portions 60 adjacent to each other. The radially outer surface of the magnet 43 is a magnetic pole surface facing the armature 23. The plurality of magnets 43 are arranged at equal or substantially equal intervals so that an N magnetic pole surface and an S magnetic pole surface are alternately arranged in the circumferential direction. In addition, for example, a sintered magnet based on an Nd-Fe-B alloy can be used for a magnet 43.

[0044] Fig. Fig. 7 is a partial perspective view of the rotor core 41 and the magnet holder 42. The detailed shape of the magnet holder 42 will be described with reference to the Fig. 4, Fig. 5 and Fig. 7 described.

[0045] The partitioning portion 60 of the magnet holder 42 includes a columnar portion 62 and a wall portion 63. The columnar portion 62 is a portion extending in the radial direction between the magnets 43 that are adjacent to each other. The wall portion 63 is a portion extending toward one side or the other side in the circumferential direction from the columnar portion 62. The radially outer surface of the magnet 43 is partially covered with the wall portion 63.

[0046] An upper end of the wall portion 63 is located at a lower position than an upper end of the rotor core 41. For this reason, when a magnet 43 is mounted, the lower end of the magnet 43 is brought into contact with the side surface of the rotor core 41, so that the magnet 43 can be positioned in the radial direction. The magnet 43 positioned in the radial direction can be press-fitted radially inward by the wall portion 63.

[0047] In addition, the upper end of the wall portion 63 is located at a lower position than an upper end of the columnar portion 62. For this reason, when a magnet 43 is mounted, the lower end of the magnet 43 can be easily inserted between the pair of columnar portions 62 that are adjacent to each other. In addition, the magnet 43 can be positioned by the pair of columnar portions 63 in the radial direction, and then the magnet 43 can be press-fitted radially inward from the wall portion 63.

[0048] When the magnet 43 is positioned in this way in the radial direction and the circumferential direction, preload at the time of press-fitting is prevented. Accordingly, it is possible to prevent the magnet 43 from abrading the partitioning portions 60 of the magnet holder 42 and generating dust at the time of press-fitting.

[0049] Additionally, in the present preferred embodiment, an inclined surface 631 is provided in the vicinity of an upper end of the radially inner surface of the wall portion 63. The inclined surface 631 gradually approaches the outer peripheral surface of the rotor core 41 from an upper end downward. The inclined surface 631 guides the magnet 43 radially inward from the wall portion 63 at the time of press-fitting the magnet 43. This facilitates the press-fitting work of the magnet 43. In addition, if the magnet 43 is guided to an appropriate position, prestressing of the load at the time of press-fitting is further prevented. Consequently, the generation of dust accompanying press-fitting is further prevented.

[0050] In addition, when such an inclined surface 631 is provided, the vicinity of the upper end of the wall portion 63 can be easily separated from a mold at the time of molding. Thus, the inclined surface 631 has technical value at both the time of press-fitting and molding.

[0051] The coupling portion 70 preferably includes a bottom surface 71 located below the magnet 43. This means that the bottom surface 71 is also arranged at a circumferential position between the partitioning portions 60 that are adjacent to each other. The bottom surface of the magnet 43 after press-fitting faces the upper surface of the bottom surface 71 in the axial direction, and the bottom surface of the magnet 43 and the upper surface of the bottom surface 71 separate or come into contact with each other. In addition, the bottom surface 71 preferably includes a recess 72 below both ends of the magnet 43 in the circumferential direction. The recess 72 of the present preferred embodiment is preferably provided at a position surrounded by the side surface of the rotor core 41, the columnar portion 62, and the wall portion 63.

[0052] Even if the magnet 43 contacts the columnar portion 62 or the wall portion 63 at the time of press-fitting the magnet 43 and generates dust, the dust is accommodated in the recess 72. For this reason, it is possible to prevent a problem that dust gets stuck between the upper surface of the bottom surface 71 and the lower surface of the magnet 43, thereby deviating the axial position of the magnet 43. In addition, the recess 72 is sealed by the lower surface of the magnet 43 after press-fitting and becomes a closed space. For this reason, scattering of the dust accommodated in the recess 72 to the outside is prevented.

[0053] In addition, at the time of press-fitting the magnet 43, the columnar portion 62 receives a larger load from the magnet than the wall portion 63. Accordingly, the columnar portion 62 is more likely to become a source of dust than the wall portion 63. When this point is taken into consideration, it is preferable that the recess 72 is provided at least at a position adjacent to the lower end of the columnar portion 62.

[0054] An example of a method for manufacturing the rotor unit 32 will be described below with reference to Fig. 8 to 11 described. Fig. 8 is a flowchart showing a manufacturing process of the rotor unit 32. Fig. 9 is a longitudinal sectional view showing the state in which pouring is performed. The position of the cut of Fig. 9 is equivalent to the position AA in Fig. 5 after production. In addition, the Fig. 10 and Fig. 11 Longitudinal sectional views showing the state in which the magnet 43 is press-fitted to the magnet holder 42. The positions of the sections of the Fig. 10 and Fig. 11 are equivalent to the position WB in Fig. 5 after production.

[0055] When manufacturing the rotor unit 32, a pair of molds 81 and 82 and the previously manufactured rotor core 41 are first prepared (step S1). The pair of molds 81 and 82 define a cavity 83 inside the pair of molds 81 and 82 by bringing opposing surfaces into contact with each other. The cavity 83 corresponds to the shape of the rotor core 41 and the magnet holder 42. The rotor core 41 is made of laminated steel sheets in which steel sheets subjected to stamping are laminated in the axial direction.

[0056] Next, the rotor core 41 is placed inside the pair of molds 81 and 82 (step S2). Here, the rotor core 41 is first inserted into one mold 81. Then, the upper portion of the mold 81 is closed by the other mold 82. Consequently, the cavity 83 is formed inside the molds 81 and 82, resulting in a state where the rotor core 41 is placed in the cavity 83.

[0057] Thereafter, resin 421 in a fluid state is injected into the cavity 83 (step S3). Here, as in Fig. 9, the resin 421 in the fluid state is injected into the cavity through a gate 821 provided in the mold 802. The resin 421 in the fluid state also flows into the groove portions of the rotor core 41. In addition, in the side surface of the rotor core 41, the resin 421 in a fluid state also enters spaces among the plurality of steel sheets 411 defining the rotor core 41.

[0058] When the resin 421 in the fluid state disperses in the cavity 83, the resin 421 is cooled and solidified in the mold 81 and 82 (step S4), so that the resin 421 in the mold 81 and 82 solidifies into the magnet holder 42. The magnet holder 42 is formed in a mold having the plurality of partitioning portions 60 and the coupling portion 70, including the above-described engaging portion 61, the columnar portion 62, the wall portion 63, the inclined surface 631, the bottom surface 71, and the recess 72.

[0059] Additionally, the rotor core 401 and the magnet holder 42 are fixed upon solidification of the resin. Consequently, in the side surface of the rotor core 41, a portion of the resin defining the magnet holder 42 is present under the plurality of steel sheets 411 that define the rotor core 41. Consequently, the rotor core 41 and the magnet holder 42 are firmly fixed.

[0060] Thereafter, the pair of molds 81 and 82 are opened, and the rotor core 41 and the magnet holder 42 are separated from the molds 81 and 82 (step S5). The inclined surface 631 is located at the upper end of the wall portion 63 of the magnet holder 42. For this reason, the wall portion 63 can be easily separated from the mold 82.

[0061] The above steps S1 to S5 are an example of the casting. Consequently, the rotor core 41 and the magnet holder 42 are made of Fig. 6. At the time of casting, both the molding of the magnet holder 42 and the fixing of the rotor core 41 and the magnet holder 42 are performed. For this reason, the process of manufacturing the rotor core 41 and the magnet holder 42 is shortened.

[0062] Subsequently, a magnet 43 is provided, and the magnet 43 is positioned at a position to be inserted with respect to the rotor core 41 and the magnet holder 42 (step S6). Here, first, a lower end of the magnet 43 is brought close to the side surface of the rotor core 41 via the wall portion 63, as indicated by an arrow 84 in Fig. 10. Then, the lower end of the magnet 43 is brought into contact with the side surface of the rotor core 41. This determines the radial position of the magnet 43. Further, the lower end of the magnet 43 is inserted between a pair of columnar portions 62 that are adjacent to each other. This determines the circumferential position of the magnet 43.

[0063] Next, the magnet 43 is moved downwards as indicated by an arrow 85 in Fig. 10. Here, the inclined surface 631 is provided at the upper end of the wall portion 63. For this reason, even if the position of the magnet 43 is slightly deviated, when the lower end of the magnet 43 is moved along the inclined surface 631, the magnet 43 is guided radially inward by the wall portion 63. This determines the position of the magnet 43 even more accurately.

[0064] Thereafter, the magnet 43 is press-fitted to the pair of columnar portions 62 adjacent to each other and the wall portion 63 (step S7). In the above step S6, the magnet 43 is positioned in the radial direction and the circumferential direction. Therefore, preload at the time of press-fitting is prevented. Consequently, dust generation accompanying the press-fitting is prevented.

[0065] In addition, the magnet holder 42 of the present preferred embodiment includes the recess 72 under both ends of the magnet 43 in the circumferential direction. For this reason, even if the magnet 43 abrades a part of the partitioning portion 60 at the time of press-fitting, generating dust 86, as shown in Fig. 11, the dust 86 is accommodated in the recess 72. For this reason, it is possible to prevent a problem in which dust gets stuck between the upper surface of the bottom surface 71 and the lower surface of the magnet 43, causing the axial position of the magnet 43 to deviate. In addition, the recess 72 is sealed by the lower surface of the magnet 43 after press-fitting. For this reason, the dust 86 accommodated in the recess 72 is prevented from spreading to the outside.

[0066] In addition, the rotor core 41 and the magnet holder 42 are firmly fixed to each other by the molding process. Therefore, the stress at the time of press-fitting the magnet 43 prevents the rotor core 41 and the magnet 42 from separating from each other. Accordingly, the magnet 43 can be easily press-fitted.

[0067] If a plurality of magnets are to be arranged inside the mold at the time of the above pouring, it is necessary to fix the magnets to the surface of the rotor core by adhesive or the like. In contrast, in the present preferred embodiment, the magnet 43 is press-fitted into the magnet holder 42 after the pouring is completed and the curing is performed. For this reason, the time and expense for adhering the magnet 43 to the rotor core 41 can be saved. In addition, a plurality of magnets 43 can be easily positioned with high accuracy.

[0068] Features of the above-described preferred embodiments and modifications thereof may be appropriately combined as long as no conflict arises.

[0069] The inclined surface 631 of the magnet holder 42 may, for example, be a curved surface as shown in Fig. 7, or may be a planar surface. Additionally, a chamfered inclined surface may be provided not only on the magnet holder 42 but also on the lower end of the magnet 43. If so, the magnet 43 can be press-fitted to the magnet holder 42 more smoothly. In addition, generation of dust accompanying the press-fitting can be further prevented.

[0070] The number of partitioning sections 60 of the magnet holder 42 and the number of magnets 43 may differ from those of the above preferred embodiments. In addition, the coupling section 70 of the magnet holder 42 may connect sections other than the lower ends of the plurality of partitioning sections 60.

[0071] In addition, the number of rotor units 32 included in the rotating portion 3 of the motor 1 may alternatively be one, or may be three or more.

[0072] In addition, the rotating electric machine of various preferred embodiments of the present invention may be the above motor 1 used for power steering, for example, or may be motors used for other portions of an automobile. For example, the rotating electric machine of a preferred embodiment of the present invention may be a motor for generating the driving force of an electric motor vehicle. In addition, the rotating electric machine according to various preferred embodiments of the present invention may be a motor used for any other desired purpose, such as an electric power-assisted bicycle, an electric motorcycle, home electronics, office automation equipment, a medical instrument, or the like.

[0073] In addition, a generator may also be formed with the structure equivalent to the motor of the above preferred embodiments or a modification thereof. The rotating electrical machine of the present invention may be a generator used, for example, for an automobile, an electric power-assisted bicycle, wind power generation, or the like.

[0074] In addition, the respective elements appearing in the above-described preferred embodiments or modifications thereof can be appropriately combined with each other within any range where no inconsistency occurs.

[0075] The preferred embodiments of the present invention and modifications thereof can be applied to a rotor unit, a rotating electrical machine, and a method of manufacturing a rotor unit.

[0076] While preferred embodiments of the present invention have been described above, it should be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Claims

[1] Rotor unit (32) for a rotating electrical machine (1), wherein the rotor unit (32) has the following features: an annular rotor core (41) comprising a plurality of steel layers (411) laminated vertically; a plurality of magnets (43) arranged in a circumferential direction around the rotor core (41); and a holder (42) made of resin and arranged to hold the plurality of magnets (43); wherein the holder (42) comprises a plurality of partitioning sections (60) extending vertically along an outer peripheral surface of the rotor core (41), and a coupling section (70) connecting the plurality of partitioning sections (60); wherein the rotor core (41) and the holder (42) are made of a molded material so as to be fixed to each other; wherein a resin portion defining the holder (42) is provided between the plurality of steel layers (411) defining the rotor core (41) in the outer peripheral surface of the rotor core (41); and wherein the plurality of magnets (43) are pressed between adjacent partitioning sections (60), wherein each of the partitioning sections (60) comprises the following features: a columnar portion (62) extending radially between a pair of the plurality of magnets (43) adjacent to each other; an engagement portion (61) extending radially from the columnar portion (62) into a vertically extending groove portion (52) formed in the outer peripheral surface of the rotor core (41), the engagement portion (61) engaging the groove portion (52); and a wall portion (63) extending circumferentially from the columnar portion (62), the upper end of which is located at a lower position than an upper end of the columnar portion (62), and which partially covers a radially outer surface of the pair of the plurality of magnets (43); and wherein an inner peripheral surface of the wall portion (63) includes an inclined surface (631) gradually approaching the outer peripheral surface of the rotor core (41) from an upper end downward. [2] The rotor unit (32) according to claim 1, wherein an upper end of the wall portion (63) is located at a lower position than an upper end of the rotor core (41). [3] The rotor unit according to claim 1 or 2, wherein a dimension of the groove portion (52) in a width direction decreases outward in the radial direction; and a dimension of the engaging portion (61) in a width direction increases inwardly in the radial direction. [4] Rotor unit (32) according to one of claims 1 to 3, in which the coupling portion (70) comprises a bottom side facing a lower surface of the magnets (43); the underside comprises a recess (72) along the circumferential direction, which is located under two ends of a magnet (43); and the recess (72) is sealed by the magnet (43). [5] The rotor unit (32) according to any one of claims 1 to 4, wherein ends of the plurality of steel layers (411) in a vicinity of the outer peripheral surface of the rotor core (41) are curved toward an upper side. [6] Rotating electrical machine (1) having the following features: a fixed section (2); and a rotating section (3) which is rotatably mounted with respect to the fixed section (2); wherein the rotating portion (2) comprises a rotor unit (32) according to any one of claims 1 to 5, and a shaft (31) inserted into the rotor core (41); and wherein the fixed portion (2) comprises a bearing (24, 25) which rotatably supports the shaft (31), and an armature (23) which is arranged radially outside the rotor unit (32). [7] A method for manufacturing a rotor unit (32) according to any one of claims 1 to 5, the method comprising the following steps: a) arranging the rotor core (41) inside a mold (81, 82) and injecting resin in a fluid state into the mold (81, 82) to mold the holder (42) so that the plurality of partitioning portions (60) extending vertically along an outer peripheral surface of the rotor core (41) and the coupling portion (70) connecting the partitioning portions (60) are formed; and b) after step a), pressing the plurality of magnets (43) between adjacent partitioning sections (60).

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