Rotor, rotary electric machine and drive device

Abstract

To provide a rotor capable of suppressing an occurrence of contamination when a shaft and a rotor core are assembled with each other.SOLUTION: One aspect of a rotor 20 of the present invention is a rotor rotatable around a center axial line, and includes: a shaft 21 that extends along the center axial line; an annular rotor core 24 in which the shaft is inserted; and a cap 60 that is provided on the shaft at one side in an axial direction of the rotor core. The cap has: an opposing portion 40 that surrounds the shaft from an external side in a radial direction, and is brought into contact with an end surface of the rotor core directed to the one side in the axial direction; and a cover portion 5b that is positioned at the one side in the axial direction of the opposing portion. A gap G is provided between an inner circumferential surface of the opposing portion and an outer circumferential surface of the shaft, and the cover portion covers the gap from the one side in the axial direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a rotor, a rotating electric machine, and a drive device. [Background technology]

[0002] In a rotating electric machine, a rotor having a shaft and a rotor core fixed to each other is known. Known fastening structures for the shaft and the rotor core include a structure in which the shaft and the rotor core are fixed by key fitting and a structure in which the shaft and the rotor core are fixed by press fitting. For example, Patent Document 1 discloses a structure in which the shaft and the rotor core are key fitted to each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-259689 A Summary of the Invention [Problem to be solved by the invention]

[0004] When inserting a shaft into a through hole in a rotor core, contamination may occur due to contact between the shaft and the rotor core when assembling them. This makes the manufacturing process more complicated, such as requiring post-processing to remove contamination after insertion.

[0005] In view of the above circumstances, an object of the present invention is to provide a rotor, a rotating electric machine, and a drive device that can suppress the occurrence of contamination when assembling a shaft and a rotor core. [Means for solving the problem]

[0006] One aspect of a rotor of the present invention is a rotor rotatable around a central axis, comprising a shaft extending along the central axis, an annular rotor core into which the shaft is inserted, and a cap provided on the shaft on one axial side of the rotor core, the cap having an opposing portion that surrounds the shaft from the radial outside and contacts an end face facing one axial side of the rotor core, and a cover portion located on one axial side of the opposing portion, with a gap provided between an inner surface of the opposing portion and an outer surface of the shaft, and the cover portion covering the gap from one axial side.

[0007] One aspect of a rotating electric machine of the present invention includes the rotor described above, and a stator surrounding the rotor from the radial outside.

[0008] One aspect of a drive device of the present invention includes the above-described rotating electric machine and a power transmission mechanism that transmits power of the rotating electric machine. Effect of the Invention

[0009] According to one aspect of the present invention, it is possible to provide a rotor, a rotating electric machine, and a drive device that can suppress the occurrence of contamination when assembling a shaft and a rotor core. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a conceptual diagram of a drive device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view of the shaft of the embodiment. [Diagram 3] FIG. 3 is an exploded perspective view of the cap according to the embodiment. [Figure 4] FIG. 4 is a perspective view of the cap according to the embodiment. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a portion corresponding to region V shown in FIG. [Figure 6] FIG. 6 is a partial cross-sectional view of the rotor of the first modified example. [Figure 7] FIG. 7 is a partial cross-sectional view of a rotor according to the second modification. [Figure 8]FIG. 8 is a partial cross-sectional view of a rotor according to the third modification. [Figure 9] FIG. 9 is a partial cross-sectional view of a rotor according to the fourth modification. [Figure 10] FIG. 10 is a partial cross-sectional view of a rotor according to the fifth modification. [Figure 11] FIG. 11 is a schematic cross-sectional view of an opposing portion and a shaft of the sixth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a driving device according to an embodiment will be described with reference to the drawings. In the following description, unless otherwise specified, a direction parallel to the central axis J of the rotating electric machine 2 (Y-axis direction) will be simply referred to as the "axial direction", a radial direction centered on the central axis J will be simply referred to as the "radial direction", and a circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, will be simply referred to as the "circumferential direction". However, the above "parallel direction" also includes a substantially parallel direction.

[0012] <Drive unit> FIG. 1 is a conceptual diagram of a drive device 1 according to an embodiment. The drive device 1 of this embodiment is mounted on a vehicle that uses a rotating electric machine as a power source, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV), and is used as the power source thereof.

[0013] The drive device 1 includes a rotating electric machine 2, a power transmission mechanism 50, a resolver 28, and a housing 6. The drive device 1 may further include an inverter (not shown) that controls the rotating electric machine 2.

[0014] The housing 6 accommodates the rotating electric machine 2, the power transmission mechanism 50, and the resolver 28. Inside the housing 6, the spaces accommodating the rotating electric machine 2, the power transmission mechanism 50, and the resolver 28 are partitioned from one another.

[0015] The resolver 28 has a resolver rotor 28a and a resolver stator 28b. The resolver rotor 28a has a plurality of magnets arranged along the circumferential direction. The resolver rotor 28a rotates around the central axis J together with the rotor 20 of the rotating electric machine 2. The resolver stator 28b is fixed to the housing 6. The resolver stator 28b surrounds the resolver rotor 28a from the radial outside. The resolver stator 28b has a coil that is excited by a change in magnetic flux accompanying the rotation of the resolver rotor 28a. The resolver 28 measures the rotation angle of the resolver rotor 28a by detecting the excitation of this coil.

[0016] <Power transmission mechanism> The power transmission mechanism 50 is connected to the rotor 20 to transmit the power of the rotating electric machine 2 and output it to an output shaft 57. The power transmission mechanism 50 has a first shaft 54, a second shaft 55, a first gear 51, a second gear 52, a third gear 53, and a differential gear 56. The differential gear 56 has a ring gear 56g and a pair of output shafts 57. Wheels (not shown) are attached to the ends of the pair of output shafts 57, respectively.

[0017] The first shaft 54 ​​extends in the axial direction around the central axis J. The first shaft 54 ​​is connected to the rotor 20 of the rotating electric machine 2 and rotates together with the rotor 20. The first gear 51 is provided on the outer peripheral surface of the first shaft 54. The second shaft 55 rotates around an intermediate axis J2 parallel to the central axis J. The second gear 52 and the third gear 53 are provided on the outer peripheral surface of the second shaft 55. The second gear 52 meshes with the first gear 51. The third gear 53 meshes with a ring gear 56g of the differential device 56. The differential device 56 transmits the torque transmitted from the third gear 53 to the output shaft 57 while absorbing the speed difference between the left and right wheels when the vehicle turns. The torque output from the rotating electric machine 2 is transmitted to the ring gear 56g of the differential device 56 via the first shaft 54, the first gear 51, the second gear 52, the second shaft 55, and the third gear 53, and is output to a pair of output shafts 57 via a differential mechanism of the differential device 56. The output shafts 57 rotate around a differential axis J3.

[0018] <Rotary Electric Machines> The rotating electric machine 2 of this embodiment is an inner rotor type three-phase AC motor. The rotating electric machine 2 has both a function of outputting power as a motor and a function of generating electricity as a generator. The rotating electric machine 2 may be used as either a motor or a generator. In addition, the configuration of the rotating electric machine 2 is not limited to this embodiment, and may be, for example, an AC motor with four or more phases.

[0019] The rotating electric machine 2 includes a rotor 20 that is rotatable about a central axis J that extends in the horizontal direction, and a stator 30 that is positioned radially outward of the rotor 20.

[0020] <Stator> The stator 30 is held in the housing 6. The stator 30 surrounds the rotor 20 from the radial outside. The stator 30 has an annular stator core 32 centered on a central axis J, a coil 31 attached to the stator core 32, and an insulating material (not shown) interposed between the stator core 32 and the coil 31.

[0021] The stator core 32 has an annular core back portion and a plurality of teeth portions extending radially inward from the core back portion and aligned in the circumferential direction. Coil wire is arranged between the teeth portions. The coil wire located between adjacent teeth portions constitutes a coil 31. The coil 31 has a pair of coil ends 31a that protrude in the axial direction from both axial end faces of the stator core 32. A portion of the coil wire that connects between the slots of the stator core 32 is formed in the coil ends 31a.

[0022] <Rotor> The rotor 20 includes a shaft 21 , a rotor core 24 fixed to the outer circumferential surface of the shaft 21 , a plurality of magnets 25 fixed to the rotor core 24 , and a pair of caps 60 .

[0023] The rotor core 24 is columnar and extends along the central axis J. The rotor core 24 has a pair of end faces 24f facing both axial sides. The rotor core 24 is also provided with a third hole portion 24c, a plurality of vent holes 24a, 24b, and a plurality of retaining holes 24h. The third hole portion 24c, the vent holes 24a, 24b, and the retaining holes 24h penetrate the rotor core 24 in the axial direction.

[0024] The third hole portion 24c extends in the axial direction around the central axis J. The shaft 21 is press-fitted into the third hole portion 24c. That is, the shaft 21 in this embodiment is press-fitted into the inner circumferential surface 24q of the rotor core 24, and thereby fixed to the inner circumferential surface 24q.

[0025] The third hole portion 24c in this embodiment is substantially circular when viewed from the axial direction. However, the shape of the third hole portion 24c is not limited to this embodiment. The rotor core 24 is annular due to the provision of the third hole portion 24c. In this specification, "annular" means a shape formed of a series of loops, and is not necessarily limited to a circular ring shape. Therefore, when the rotor core 24 is viewed from the axial direction, the surface facing the radially outward and the surface facing the radially inward of the rotor core 24 do not necessarily have to be circular.

[0026] The multiple ventilation holes 24a, 24b include a first ventilation hole 24a and a second ventilation hole 24b. That is, the rotor core 24 is provided with the first ventilation hole 24a and the second ventilation hole 24b. The rotor 20 of this embodiment is provided with, for example, four first ventilation holes 24a and four second ventilation holes 24b. The first ventilation holes 24a and the second ventilation holes 24b have mutually different flow directions of air flowing therethrough.

[0027] The multiple holding holes 24h are arranged in the circumferential direction. A magnet 25 is housed in each of the holding holes 24h. The magnet 25 is fixed to the inner surface of the holding hole 24h, for example, by an adhesive or the like. The magnet 25 may be fixed in the holding hole 24h by other fixing means such as crimping, press fitting, or a foam sheet, or by a combination of these means. The openings on both axial sides of the holding hole 24h are covered with caps 60. This makes it possible to prevent fragments of the magnet 25 from scattering from the holding hole 24h of the rotor 20 even if a part of the magnet 25 is missing.

[0028] The shaft 21 extends along a central axis J. The shaft 21 is rotatable about the central axis J. A rotor core 24, a pair of caps 60, and a resolver rotor 28a are fixed to an outer circumferential surface 21p of the shaft 21. The pair of caps 60 are located on both axial sides of the rotor core 24. The resolver rotor 28a is fixed to an end of the shaft 21 on one axial side (+Y).

[0029] FIG. 2 is a perspective view of the shaft 21. A step is provided on the outer peripheral surface 21p of the shaft 21. The outer peripheral surface 21p of the shaft 21 has a first portion 21a, a second portion 21b, two third portions 21c, a fourth portion 21d, a fifth portion 21e, a sixth portion 21f, and a seventh portion 21g. The first portion 21a, the second portion 21b, the third portion 21c, the fourth portion 21d, the fifth portion 21e, the sixth portion 21f, and the seventh portion 21g have different outer diameters. The outer diameter of the shaft 21 becomes smaller toward one side and the other side in the axial direction, respectively, with respect to the fourth portion 21d. Each portion will be described below.

[0030] The fourth portion 21d is a portion of the outer peripheral surface 21p that has the largest outer diameter. The fourth portion 21d is a portion of the outer peripheral surface 21p that has the largest axial length. The fourth portion 21d is a portion that faces the inner peripheral surface 24q of the rotor core 24. That is, the shaft 21 is press-fitted into the rotor core 24 at the fourth portion 21d. The fourth portion 21d is provided with a plurality of grooves 21h. The grooves 21h are provided by subjecting the fourth portion 21d to machining, such as knurling. The plurality of grooves 21h extend in the axial direction at the fourth portion 21d. In this embodiment, the plurality of grooves 21h extend over the entire axial length of the fourth portion 21d. The plurality of grooves 21h are also arranged at intervals in the circumferential direction at the fourth portion 21d. The grooves 21h are arranged at substantially equal intervals over the entire circumferential area of ​​the fourth portion 21d. The grooves 21h may be arranged in at least a portion of the fourth portion 21d in the axial direction. Similarly, the grooves 21h may be provided in at least a portion of the fourth portion 21d in the circumferential direction.

[0031] The third portion 21c is located on one side and the other side of the fourth portion 21d in the axial direction. The two third portions 21c have shapes symmetrical to each other in the axial direction. The third portion 21c has a smaller outer diameter than the fourth portion 21d. A cap 60 is fixed to the third portion 21c. The third portion 21c is provided with a plurality of grooves 21i by, for example, machining such as knurling. The plurality of grooves 21i extend in the axial direction in the third portion 21c. In this embodiment, the plurality of grooves 21i extend over the entire axial length of the third portion 21c. In addition, the plurality of grooves 21i are arranged at intervals in the circumferential direction in the third portion 21c. In this embodiment, the plurality of grooves 21i are arranged at approximately equal intervals over the entire circumferential length of the third portion 21c. Note that it is sufficient that the grooves 21i are arranged in at least a part of the third portion 21c in the axial direction. Similarly, the groove portion 21i may be provided in at least a partial area of ​​the third portion 21c in the circumferential direction.

[0032] The second portion 21b is provided on the other axial side (-Y side) of one of the third portions 21c located on the other axial side (-Y side). The second portion 21b has a smaller outer diameter than the third portion 21c.

[0033] The first portion 21a is provided on the other axial side (-Y side) of the second portion 21b. The first portion 21a is located at the end of the shaft 21 on the other axial side (-Y side). The first portion 21a has a smaller outer diameter than the second portion 21b. For example, a bearing is attached to the first portion 21a, and the first portion 21a is supported by the housing 6.

[0034] The fifth portion 21e is provided on one axial side (+Y side) of the other third portion 21c located on the one axial side (+Y side). The fifth portion 21e has an outer diameter smaller than that of the third portion 21c.

[0035] The sixth portion 21f is provided on one axial side (+Y side) of the fifth portion 21e. The sixth portion 21f has a smaller outer diameter than the fifth portion 21e. For example, a bearing is attached to the sixth portion 21f, and the sixth portion 21f is supported by the housing 6.

[0036] The seventh portion 21g is provided on one axial side (+Y side) of the sixth portion 21f. The seventh portion 21g is located at the end of the shaft 21 on one axial side (+Y side). The seventh portion 21g has a smaller outer diameter than the sixth portion 21f. The resolver rotor 28a is fixed to the seventh portion 21g by press-fitting. The seventh portion 21g is provided with a plurality of grooves 21j by machining such as knurling. The plurality of grooves 21j are provided at the end of the seventh portion 21g on one axial side (+Y side). The plurality of grooves 21j are arranged at intervals in the circumferential direction in the seventh portion 21g. In this embodiment, the plurality of grooves 21j are arranged at approximately equal intervals over the entire circumferential area of ​​the seventh portion 21g. It is sufficient that the grooves 21j are provided in at least a part of the third portion 21c in the circumferential direction. By providing the groove 21j in the seventh portion 21g, a part of the inner circumferential surface of the resolver rotor 28a is deformed during press-fitting and enters the groove 21j. This allows the resolver rotor 28a to be stably fixed to the shaft 21.

[0037] As shown in Fig. 1, shaft 21 has a recess 29 that opens at an end on the other axial side (-Y side). Recess 29 is substantially circular about central axis J when viewed in the axial direction. A first shaft 54 ​​of power transmission mechanism 50 is inserted into recess 29. The inner circumferential surface of recess 29 and the outer circumferential surface of first shaft 54 ​​are connected by, for example, spline fitting. That is, shaft 21 has recess 29 that opens at an end on one or the other axial side, into which an end of another shaft is inserted.

[0038] In this embodiment, the end of recess 29 on one axial side (+Y side) is located on the other axial side (-Y side) of fourth portion 21d of shaft 21. As described above, fourth portion 21d is press-fitted into rotor core 24. Therefore, recess 29 is arranged at a different position from rotor core 24 in the axial direction. According to this embodiment, it is possible to suppress a decrease in rigidity of the portion of shaft 21 that axially overlaps with rotor core 24 due to recess 29. In other words, it is possible to suppress deformation of shaft 21 due to press-fitting into rotor core 24.

[0039] In this embodiment, a part of the recess 29 is disposed radially inside the third portion 21c of the shaft 21. Although the third portion 21c is a portion that is press-fitted into the cap 60, the force applied from the cap 60 to the third portion 21c is smaller than the force applied from the rotor core 24 to the fourth portion 21d. Therefore, even if the axial position of the recess 29 overlaps with the axial position of the third portion 21c, deformation of the shaft 21 is unlikely to occur.

[0040] <Cap> 1, the caps 60 are located on one axial side and the other axial side of the rotor core 24. The caps 60 are provided on the shaft 21. The cap 60 has a fan 4 and a fixing member 5.

[0041] In this embodiment, the cap 60 is composed of multiple members (the fan 4 and the fixed member 5). However, the cap 60 may be composed of a single member. Furthermore, the fan 4 and the fixed member 5 in this embodiment are separate members from the shaft 21. However, the cap 60 may be part of the shaft 21, either in part or in its entirety. In other words, at least a portion of the parts constituting the cap 60 may be configured as a single member together with the shaft 21.

[0042] The pair of caps 60 have the same configuration. In the following description, when distinguishing between the pair of caps 60, one located on the +Y side of rotor core 24 is referred to as a first cap 60A, and the other located on the -Y side of rotor core 24 is referred to as a second cap 60B. When distinguishing between the pair of fans 4, the fan 4 of the first cap 60A is referred to as a first fan 4A, and the fan 4 of the second cap 60B is referred to as a second fan 4B.

[0043] The fans 4 are attached to one axial side and the other axial side of the rotor core 24. That is, one of the pair of fans 4 is attached to an end face 24f facing one axial side of the rotor core 24, and the other of the pair of fans 4 is attached to an end face 24f facing the other axial side of the rotor core 24. The pair of fans 4 rotate around the central axis J together with the rotor core 24. The pair of fans 4 are each located radially inside the coil ends 31a. In this embodiment, the pair of fans 4 have the same shape as each other. The pair of fans 4 have different attachment angles around the central axis J with respect to the rotor core 24.

[0044] The fan 4 of the present embodiment is made of an aluminum alloy and is formed by aluminum die casting. The fan 4 may be made of a resin material or another metallic material.

[0045] The fan 4 of this embodiment covers the end face 24f of the rotor core 24. The fan 4 also covers the multiple holding holes 24h of the rotor core 24. This can prevent the magnets 25 from popping out of the holding holes 24h. The fan 4 can also prevent fragments of the magnets 25 from scattering from the rotor 20 even if a part of the magnet 25 is missing. That is, according to this embodiment, the fan 4 also functions as an end plate that covers the openings of the holding holes 24h. Therefore, according to this embodiment, there is no need to provide a separate member that covers the openings of the holding holes 24h, and the rotor 20 can be easily manufactured with a reduced number of parts.

[0046] The fan 4 is provided with a plurality of inlet passages 45 and a plurality of outlet passages 46. The plurality of inlet passages 45 and the plurality of outlet passages 46 are each connected to one of the plurality of air holes 24a, 24b.

[0047] The first fan 4A and the second fan 4B are attached to the rotor core 24 at different angles around the central axis J. When the first fan 4A is attached to the rotor core 24, the inflow passage 45 is connected to the second vent hole 24b, and the outflow passage 46 is connected to the first vent hole 24a. On the other hand, when the second fan 4B is attached to the rotor core 24, the inflow passage 45 is connected to the first vent hole 24a, and the outflow passage 46 is connected to the second vent hole 24b. Therefore, the first vent hole 24a connects the inflow passage 45 of the second fan 4B to the outflow passage 46 of the first fan 4A. Also, the second vent hole 24b connects the inflow passage 45 of the first fan 4A to the outflow passage 46 of the second fan 4B.

[0048] The outflow passage 46 extends along the radial direction and opens toward the radial outside. When the rotor 20 rotates, the air inside the outflow passage 46 is subjected to centrifugal force accompanying the rotation around the central axis J of the fan 4. As a result, the air inside the outflow passage 46 flows outward in the radial direction. As the air flows out from the outflow passage 46, negative pressure is generated inside the vent holes 24a, 24b connected to the outflow passage 46. As a result, air flows into the vent holes 24a, 24b through the inflow passage 45. An air flow along the axial direction is formed in the vent holes 24a, 24b. Furthermore, in this embodiment, the air flowing outward in the radial direction from the outflow passage 46 hits the coil end 31a and cools the coil 31.

[0049] Fig. 3 is an exploded perspective view of the first cap 60A. Fig. 4 is a perspective view of the first cap 60A seen from a different direction than that of Fig. 3. In the following description, the position and shape of each part of the cap 60 will be described based on the posture of the first cap 60A in Figs. 3 and 4. The second cap 60B is fixed to the shaft 21 and the rotor core 24 in a position and posture that is the axial inversion of the following description.

[0050] As shown in FIG. 3, the fan 4 has an opposing portion 40, an annular rib 41, and a plurality of convex portions 47 (four in this embodiment).

[0051] The facing portion 40 has a disk shape extending perpendicular to the axial direction. When viewed from the axial direction, the facing portion 40 has a substantially circular shape centered on the central axis J. The facing portion 40 has a first surface 40a facing the other axial side (-Y side) and a second surface 40b facing one axial side (+Y side). The first surface 40a faces an end surface 24f of the rotor core 24.

[0052] 4, the opposing portion 40 is provided with a first hole portion 40h, a plurality of (four in this embodiment) through holes 42, and a plurality of (four in this embodiment) recesses 43. The first hole portion 40h and the through holes 42 penetrate the opposing portion 40 in the axial direction.

[0053] When viewed in the axial direction, the first hole 40h has a substantially circular shape centered on the central axis J. The shaft 21 is inserted into the first hole 40h. The inner diameter of the first hole 40h is larger than the outer diameter of the shaft 21. A method of fixing the fan 4 to the shaft 21 will be described later.

[0054] When viewed from the axial direction, the through holes 42 and the recesses 43 are arranged alternately in the circumferential direction. When the first fan 4A is viewed from the axial direction, the opening of the through hole 42 in the first surface 40a overlaps with the second vent hole 24b, and the recesses 43 overlap with the first vent hole 24a. The recesses 43 are provided in the first surface 40a. The opening of the recesses 43 on the other axial side (-Y side) is covered by the end surface 24f of the rotor core 24. The recesses 43 have a connection portion 43a overlapping with the first vent hole 24a, and a groove portion 43b extending radially outward from the connection portion 43a and opening at the outer edge of the facing portion 40. In addition, the space surrounded by the recesses 43 and the end surface 24f of the rotor core 24 is connected to the vent hole 24a and forms an outlet path 46. On the other hand, the through hole 42 is connected to the vent hole 24b and forms an inlet path 45.

[0055] As shown in FIG. 3, the annular rib 41 protrudes from the second surface 40b of the opposing portion 40 toward one axial side (+Y side). The annular rib 41 has a substantially circular ring shape centered on the central axis J. The annular rib 41 is provided along the outer edge of the second surface 40b. The annular rib 41 can be used, for example, as a cutting allowance used to correct imbalance of the rotor 20. That is, in a balance correction process after the rotor 20 is assembled, the imbalance of the rotor 20 can be corrected by machining a part of the annular rib 41. As the machining applied to the annular rib 41, for example, cutting can be applied to a surface of the annular rib 41 facing radially outward.

[0056] The multiple convex portions 47 protrude from the second surface 40b of the opposing portion 40 toward one axial side (+Y side). The multiple convex portions 47 are arranged at equal intervals in the circumferential direction on the radially inner side of the annular rib 41. The convex portions 47 are located between the through holes 42 adjacent to each other in the circumferential direction. Also, the convex portions 47 overlap the concave portions 43 when viewed in the axial direction. The convex portions 47 have an inner side surface 47f facing radially inward and a tip surface 47h facing one axial side. When viewed in the axial direction, the inner side surface 47f is a substantially arc-shaped surface centered on the central axis J.

[0057] A groove 40g is provided in a tip surface 47h of the convex portion 47. The groove 40g extends along the radial direction and is recessed from the tip surface 47h toward the other axial side (-Y side). The groove 40g is provided in two of the four convex portions 47 that are located on opposite sides of the central axis J.

[0058] The fixed member 5 is disposed on one axial side (+Y side) of the fan 4. The fixed member 5 axially faces the fan 4. The fixed member 5 is made of, for example, a metal material.

[0059] The fixing member 5 has a cylindrical portion 5d into which the shaft 21 is press-fitted, and a cover portion 5b that protrudes radially outward from the cylindrical portion 5d and extends in the circumferential direction. The cylindrical portion 5d is cylindrical and centered on the central axis J. The inner peripheral surface of the cylindrical portion 5d forms the second hole portion 5h. That is, the fixing member 5 has the second hole portion 5h into which the shaft 21 is inserted. The fixing member 5 of this embodiment has a simple shape and can be easily manufactured by employing a manufacturing method such as press working.

[0060] The shaft 21 is press-fitted into the cylindrical portion 5d, whereby the fixing member 5 is fixed to the outer surface of the shaft 21. The cover portion 5b is disposed radially inside the plurality of convex portions 47. The outer edge 5c of the cover portion 5b is circular with the center on the central axis J when viewed from the axial direction. The outer edge 5c of the cover portion 5b fits into the inner surface 47f of the plurality of convex portions 47. This allows the fan 4 to be aligned radially with respect to the cover portion 5b. The cover portion 5b also contacts the second surface 40b of the fan 4 from one axial side (+Y side). The fan 4 is fixed to the shaft 21 in the axial direction by being sandwiched between the rotor core 24 and the cover portion 5b. The outer edge 5c of the cover portion 5b is not limited to a circular shape when viewed from the axial direction, and may be another shape such as a polygonal shape.

[0061] In this embodiment, the outer edge 5c of the fixed member 5 is provided with a plurality of (two in this modification) protrusions 5a that protrude radially outward. The two protrusions 5a are arranged on opposite sides (i.e., symmetrically) with respect to the central axis J. The protrusions 5a are arranged in the recessed groove 40g. The circumferential surface of the protrusions 5a faces the inner surface of the recessed groove 40g in the circumferential direction. In this way, the fixed member 5 limits the circumferential movement of the fan 4 relative to the fixed member 5.

[0062] FIG. 5 is an enlarged cross-sectional view of the rotor 20 of a portion corresponding to region V in FIG. As shown in FIG. 5, the facing portion 40 contacts the end face 24f of the rotor core 24 at the first surface 40a, and contacts the cover portion 5b of the fixed member 5 at the second surface 40b.

[0063] In this embodiment, the outer edge of the cover portion 5b is located radially inward from the through holes 42. That is, the cover portion 5b is provided at a position different from the through holes 42 when viewed in the axial direction. Therefore, the cover portion 5b is less likely to obstruct the flow of air passing through the through holes 42. Between adjacent through holes 42 in the circumferential direction, the cover portion 5b may be located radially outward from the through holes 42.

[0064] The shaft 21 is press-fitted into the third hole portion 24c of the rotor core 24. Therefore, the inner peripheral surface 24q of the third hole portion 24c contacts the outer peripheral surface 21p of the shaft 21 over the entire circumferential area. Similarly, the shaft 21 is press-fitted into the second hole portion 5h of the fixing member 5. Therefore, the inner peripheral surface 5q of the second hole portion 5h contacts the outer peripheral surface 21p of the shaft 21 over the entire circumferential area. On the other hand, the inner diameter of the first hole portion 40h provided in the facing portion 40 is larger than the outer diameter of the shaft 21. Therefore, a gap G is provided between the inner peripheral surface 40q of the first hole portion 40h and the outer peripheral surface 21p of the shaft 21. In this embodiment, the gap G is provided in an annular shape over the entire circumferential area around the central axis J. Note that the gap G does not necessarily have to be annular as long as it extends in the circumferential direction around the central axis J. The gap G may extend in the circumferential direction and may be generally C-shaped or generally arc-shaped when viewed from the axial direction, for example.

[0065] As described above, the outer peripheral surface 21p of the shaft 21 is provided with the fourth portion 21d into which the rotor core 24 is press-fitted, and the third portion 21c into which the fixing member 5 is press-fitted. The outer diameter of the third portion 21c is smaller than that of the fourth portion 21d. Therefore, a step portion 21k is provided at the boundary portion between the third portion 21c and the fourth portion 21d. Meanwhile, in this embodiment, the inner diameter of the first hole portion 40h of the facing portion 40 is constant over the entire axial length. Also, the inner peripheral surface 40q of the facing portion 40 faces the outer peripheral surface 21p of the shaft 21 at the boundary portion between the third portion 21c and the fourth portion 21d. Therefore, between the inner peripheral surface 40q and the outer peripheral surface 21p, the radial dimension of the gap G at the end portion on one axial side (+Y side) is larger than the radial dimension of the gap G at the end portion on the other axial side (-Y side).

[0066] An end of the gap G on the other axial side (-Y) is covered by the rotor core 24. On the other hand, an end of the gap G on one axial side (+Y) is covered by the cover portion 5b of the fixed member 5. For this reason, the gap G is a closed space. Note that "closed space" here means a state in which fine solid contaminants such as metal dust in the gap G are not discharged to the outside, or are difficult to discharge. In other words, the gap G does not have to be in a state in which the inflow and outflow of fluid is suppressed (a so-called sealed state).

[0067] That is, according to this embodiment, the cap 60 has a facing portion 40 that surrounds the shaft 21 from the radial outside and contacts the end face 24f of the rotor core 24, and a cover portion 5b that is located on one axial side (+Y) of the facing portion 40. Also, a gap G is provided between an inner circumferential surface 40q of the facing portion 40 and an outer circumferential surface 21p of the shaft 21. The cover portion 5b covers the gap G from one axial side.

[0068] When the shaft 21 is inserted into the third hole portion 24c of the rotor core 24, the shaft 21 may come into contact with the inner circumferential surface 24q of the rotor core 24, causing a portion of one of the shafts to be scraped off, resulting in contamination. In particular, when the shaft 21 is press-fitted into the inner circumferential surface 24q of the rotor core 24, as in this embodiment, contamination may be more likely to occur. When the shaft 21 is inserted into the third hole portion 24c of the rotor core 24, contamination is likely to accumulate near the opening of the third hole portion 24c on the side where the shaft 21 is inserted.

[0069] According to this embodiment, the facing portion 40 surrounds the opening of the third hole portion 24c from the radially outer side. Therefore, contaminants can be accommodated in the gap G between the inner circumferential surface 24q of the facing portion 40 and the outer circumferential surface 21p of the shaft 21. Furthermore, since the gap G is covered by the cover portion 5b of the fixing member 5 from one axial side, the contaminants in the gap G can be kept in the gap G. According to this embodiment, even if contaminants are generated when assembling the shaft 21 and the rotor core 24, it is not necessary to perform a separate process of removing the contaminants, and the manufacturing process can be simplified.

[0070] The gap G in this embodiment extends annularly along the circumferential direction. Therefore, the gap G can accommodate and retain contaminants over the entire circumferential direction. As shown in FIG. 3, the cover portion 5b of the fixing member 5 fits into the inner surface 47f of the multiple convex portions 47 of the fan 4, so that the center position of the fan 4 is aligned with the center of the shaft 21. This allows the radial width of the gap G between the inner peripheral surface 40q of the first hole portion 40h and the outer peripheral surface 21p of the shaft 21 to be approximately uniform along the circumferential direction. This allows the gap G to retain contaminants uniformly at any position in the circumferential direction.

[0071] According to this embodiment, it is possible to simplify the shapes of the shaft 21 and the rotor core 24 compared to a case in which the rotor core and the shaft are keyed together. This makes it possible to easily manufacture the shaft 21 and the rotor core 24, reducing the manufacturing cost and facilitating the manufacture of the rotor 20.

[0072] Furthermore, according to this embodiment, grooves 21h are provided on the outer circumferential surface 21p of the shaft 21, which faces the inner circumferential surface 24q of the rotor core 24. Therefore, a part of the inner circumferential surface 24q of the rotor core 24 is deformed during press-fitting and enters the grooves 21h. This allows the shaft 21 and the rotor core 24 to be firmly fixed in the circumferential direction.

[0073] In the present embodiment, the shaft 21 and the rotor core 24 are fixed to each other by press-fitting the shaft 21 into the rotor core 24. However, the method of fixing the shaft 21 and the rotor core 24 is not limited to the present embodiment. For example, the shaft 21 and the rotor core 24 may be fixed to each other by fitting a key into a key groove provided on the outer circumferential surface of the shaft and the inner circumferential surface of the rotor core. Even in this case, contamination caused by contact between the shaft and the rotor core when assembling the shaft and the rotor core can be contained in the gap G. The shaft 21 and the rotor core 24 may be fixed to each other by an adhesive. In this case, when the shaft is inserted into the rotor core, uncured adhesive is pushed out from the gap between the shaft 21 and the rotor core 24. The pushed-out adhesive remains in the gap G, so that it is possible to prevent the adhesive that protrudes from the gap between the shaft 21 and the rotor core 24 from adhering to other members or other parts of the shaft 21 and the rotor core 24 other than the parts that constitute the gap.

[0074] In this embodiment, the cap 60 has a fixed member 5 having a cover portion 5b, and a fan 4 having a facing portion 40. That is, in the cap 60 of this embodiment, the cover portion 5b and the facing portion 40 are separate members. The fixed member 5 is fixed to the shaft 21. On the other hand, the fan 4 is located between the fixed member 5 and the rotor core 24 in the axial direction. In addition, the fan 4 has a first hole portion 40h through which the shaft 21 is inserted.

[0075] The cap 60 of this embodiment not only keeps contaminants in the gap G, but also acts as a fan to send air into the rotor core 24. According to this embodiment, the facing portion 40 and the cover portion 5b are made of separate members, so that the fan 4 and the fixed member 5 can each be made of an optimal material. This makes it possible to configure the cap 60 that is lightweight overall and can contain contaminants and send out air through the gap G described above.

[0076] In this embodiment, the fixing member 5 has a second hole 5h through which the shaft 21 is inserted. The shaft 21 is press-fitted into an inner peripheral surface 5q of the second hole 5h. Therefore, there is no need to provide a separate fixing structure for the fixing member 5 and the shaft 21, and the rotor 20 can be easily manufactured. Note that a screw thread may be formed on the inner peripheral surface of the fixing member to make the fixing member 5 side a female thread, and a screw thread may be formed on the outer peripheral surface of the shaft 21 to make the shaft side a male thread, thereby fixing the fixing member 5 and the shaft 21 by a screw structure.

[0077] Furthermore, when the fixing member 5 is press-fitted into the shaft 21, the fixing member 5 is moved to one axial side relative to the shaft 21. The fixing member 5 is located on one axial side (+Y side) of the gap G. Therefore, the gap G can accommodate contamination that occurs when the shaft 21 is press-fitted into the second hole portion 5h. That is, the gap G in this embodiment can contain not only contamination that occurs when the shaft 21 is press-fitted into the rotor core 24, but also contamination that occurs when the fixing member 5 is press-fitted into the shaft 21.

[0078] According to this embodiment, a groove 21i is provided on the outer circumferential surface 21p of the shaft 21, which faces the inner circumferential surface 5q of the second hole portion 5h. Therefore, a part of the inner circumferential surface 5q of the fixing member 5 is deformed during press-fitting and enters the groove 21i. This makes it possible to prevent the shaft 21 from moving circumferentially relative to the fixing member 5.

[0079] <Modification> Next, rotors of modified examples that can be used in the above-described embodiment will be described. In the following description of each modified example, the same components as those in the embodiment or modified example already described will be denoted by the same reference numerals, and the description thereof will be omitted.

[0080] (Variation 1) 6 is a partial cross-sectional view of rotor 120 of modified example 1, showing a portion corresponding to region V in FIG. 1. As in the above-described embodiment, rotor 120 of this modified example has shaft 121, rotor core 24, and cap 60. Cap 60 has fan 4 and fixed member 5. Shaft 121 is press-fitted into rotor core 24 and fixed member 5.

[0081] The shaft 121 of this modification has a first outer circumferential surface 121p, a second outer circumferential surface 121q, and an outer circumferential step surface 121t. The first outer circumferential surface 121p and the second outer circumferential surface 121q are surfaces that face radially outward. The outer circumferential step surface 121t is a surface that faces one axial side (the +Y side).

[0082] The first outer peripheral surface 121p faces in the radial direction an inner peripheral surface 24q of the rotor core 24. At least a portion of the first outer peripheral surface 121p contacts with the inner peripheral surface 24q of the rotor core 24 in the radial direction.

[0083] The second outer peripheral surface 121q is located on one axial side (+Y side) of the first outer peripheral surface 121p. The second outer peripheral surface 121q has a smaller outer diameter than the first outer peripheral surface 121p. The second outer peripheral surface 121q faces an inner peripheral surface 40q of the facing portion 40 in the radial direction. The second outer peripheral surface 121q also faces an inner peripheral surface 5q of the fixed member 5 in the radial direction. At least a portion of the second outer peripheral surface 121q is in contact with the inner peripheral surface 5q of the fixed member 5 in the radial direction.

[0084] The outer peripheral step surface 121t connects the first outer peripheral surface 121p and the second outer peripheral surface 121q. The outer peripheral step surface 121t extends along a plane perpendicular to the axial direction. The outer peripheral step surface 121t of this modified example is disposed flush with the end surface 24f of the rotor core 24. That is, the axial position of the outer peripheral step surface 121t coincides with the end surface 24f of the rotor core 24. The outer peripheral step surface 121t does not necessarily have to be flush with the end surface 24f of the rotor core 24. That is, the axial position of the outer peripheral step surface 121t may be different from the axial position of the end surface 24f of the rotor core 24. The outer peripheral step surface 121t does not necessarily have to be flat, and may have irregularities.

[0085] According to this modification, the shaft 121 has a first outer peripheral surface 121p facing the inner peripheral surface 24q of the rotor core 24, and a second outer peripheral surface 121q facing the inner peripheral surface 40q of the facing portion 40 and having a smaller outer diameter than the first outer peripheral surface 121p. The gap G is surrounded by the inner peripheral surface 40q of the facing portion 40, the end face 24f of the rotor core, the outer peripheral step surface 121t, and the second outer peripheral surface 121q. The gap G is provided radially inward of the inner peripheral surface 40q of the facing portion 40. In the radial direction, the gap G is located between the inner peripheral surface 40q of the facing portion 40 and the second outer peripheral surface 121q. This makes it possible to ensure a large gap G in the radial direction, making it easier to accommodate contaminants inside the gap G. The inner peripheral surface 40q may be located radially outward or radially inward of the inner peripheral surface 24q. That is, the opposing portion 40 may be in axial contact only with the end face 24f of the rotor core 24, or may be in axial contact with both the end face 24f and the outer circumferential step surface 121t of the rotor core 24. When the opposing portion 40 is in axial contact with both the end face 24f and the outer circumferential step surface 121t of the rotor core 24, the gap G is surrounded by the outer circumferential step surface 121t, the second outer circumferential surface 121q, the fixing member 5, and the inner circumferential surface 40q.

[0086] (Variation 2) 7 is a partial cross-sectional view of rotor 220 of modified example 2, showing a portion corresponding to region V in FIG. 1. As in the above-described embodiment, rotor 220 of this modified example has shaft 21, rotor core 24, and cap 260. Cap 260 has fan 204 and fixed member 5. Opposing portion 240 has first hole 240h provided therein. Shaft 21 is press-fitted into rotor core 24 and fixed member 5.

[0087] The facing portion 240 of this modification has a first inner peripheral surface 240p, a second inner peripheral surface 240q, and an inner peripheral step surface 240t as the inner peripheral surfaces of the first hole portion 240h. The first inner peripheral surface 240p and the second inner peripheral surface 240q are surfaces that face radially inward. The inner peripheral step surface 240t is a surface that faces the other axial side (-Y side).

[0088] The gap G is located between the outer circumferential surface 21p of the shaft 21 and the opposing portion 240 in the radial direction. That is, the gap G is located between the first inner circumferential surface 240p and the second inner circumferential surface 240q in the radial direction. The first inner circumferential surface 240p and the second inner circumferential surface 240q face the outer circumferential surface 21p of the shaft 21 in the radial direction via the gap G. The second inner circumferential surface 240q is located on one axial side (+Y side) of the first inner circumferential surface 240p. The second inner circumferential surface 240q has a smaller inner diameter than the first inner circumferential surface 240p. The inner circumferential step surface 240t connects the first inner circumferential surface 240p and the second inner circumferential surface 240q. The inner circumferential step surface 240t extends along a plane perpendicular to the axial direction. The gap G is located in the axial direction between the inner circumferential step surface 240t and the end face 24f of the rotor core 24. Note that the inner circumferential step surface 240t may be flat or may have projections and recesses as long as it extends along a plane perpendicular to the axial direction.

[0089] According to this modification, the facing portion 240 has a first inner circumferential surface 240p located on the rotor core 24 side in the axial direction, which has a larger inner diameter than a second inner circumferential surface 240q located on the opposite side of the rotor core 24. Therefore, the gap G provided between the facing portion 240 and the shaft 21 in the radial direction is wider on the rotor core 24 side in the axial direction. This ensures that the gap G provided on the radial inner side of the facing portion 240 is large in the radial direction, making it easier to accommodate contaminants in the gap G. Note that in this modification, the second inner circumferential surface 240q may be in contact with the outer circumferential surface 21p of the shaft 21. That is, the gap G may be surrounded by the first outer peripheral surface 21p, the fixed member 5, the second inner peripheral surface 240q, the inner peripheral step surface 240t, the first inner peripheral surface 240p, and the end face 24f of the rotor core, or may be surrounded by the first outer peripheral surface 21p, the fixed member 5, the inner peripheral step surface 240t, the first inner peripheral surface 240p, and the end face 24f of the rotor core.

[0090] (Variation 3) FIG. 8 is a partial cross-sectional view of a rotor 320 according to the third modification, showing a portion corresponding to region V in FIG. The rotor 320 of this modification has a configuration that combines the above-mentioned modifications 1 and 2. The shaft 121 of this modification has the same configuration as that of the modification 1. Moreover, the cap 260 of this modification has the same configuration as that of the modification 2.

[0091] The rotor 320 of this modified example includes a shaft 121, a rotor core 24, and a cap 260. The cap 260 includes a fan 204 and a fixed member 5. The shaft 121 is press-fitted into the rotor core 24 and the fixed member 5.

[0092] That is, the shaft 121 of this modification has a first outer peripheral surface 121p, a second outer peripheral surface 121q, and an outer peripheral step surface 121t. The first outer peripheral surface 121p faces an inner peripheral surface 24q of the rotor core 24. The second outer peripheral surface 121q is located on one axial side (+Y side) of the first outer peripheral surface 121p. The second outer peripheral surface 121q has a smaller outer diameter than the first outer peripheral surface 121p. The outer peripheral step surface 121t connects the first outer peripheral surface 121p and the second outer peripheral surface 121q. In addition, the facing portion 240 of this modification has a first inner peripheral surface 240p, a second inner peripheral surface 240q, and an inner peripheral step surface 240t. The second inner peripheral surface 240q is located on one axial side (+Y) of the first inner peripheral surface 240p. The second inner circumferential surface 240q has an inner diameter smaller than that of the first inner circumferential surface 240p. The inner circumferential step surface 240t connects the first inner circumferential surface 240p and the second inner circumferential surface 240q. The second outer circumferential surface 121q and the first inner circumferential surface 240p face each other in the radial direction via a gap G. The gap G is located between the facing portion 240 and the second outer circumferential surface 121q in the radial direction. That is, the gap G is located between the first inner circumferential surface 240p and the second inner circumferential surface 240q and the second outer circumferential surface 121q in the radial direction.

[0093] According to this modification, a large gap G can be secured in the radial direction between the second outer peripheral surface 121q, which has a smaller outer diameter than the other parts, and the first inner peripheral surface 240p, which has a larger inner diameter than the other parts, and it becomes easier to accommodate contaminants in the gap G. In this modification, the second inner peripheral surface 240q may be in contact with the second outer peripheral surface 121q of the shaft 121. The gap G may be surrounded by the second outer peripheral surface 121q, the fixing member 5, the second inner peripheral surface 240q, the inner peripheral step surface 240t, the first inner peripheral surface 240p, the end surface 24f of the rotor core 24, and the outer peripheral step surface 121t, or may be surrounded by the second outer peripheral surface 121q, the fixing member 5, the inner peripheral step surface 240t, the first inner peripheral surface 240p, the end surface 24f of the rotor core 24, and the outer peripheral step surface 121t. The outer peripheral step surface 121t does not necessarily have to be flush with the end surface 24f of the rotor core 24. That is, the axial position of the outer peripheral step surface 121t may be different from the axial position of the end surface 24f of the rotor core 24. The inner peripheral step surface 240t may face both the end surface 24f of the rotor core 24 and the outer peripheral step surface 121t in the axial direction, or may face only the end surface 24f of the rotor core 24. In other words, if the inner peripheral step surface 240t is formed, the first inner peripheral surface 240p may be radially outward from the first outer peripheral surface 121p, or may be radially inward. If the inner peripheral step surface 240t is formed, the facing portion 240 may be in contact with both the end surface 24f of the rotor core 24 and the outer peripheral step surface 121t, or may be in contact with only the end surface 24f of the rotor core 24.

[0094] (Variation 4) FIG. 9 is a partial cross-sectional view of rotor 420 of modified example 4, showing a portion corresponding to region V in FIG. 1. As in the above-described embodiment, rotor 420 of this modified example includes shaft 21, rotor core 24, and cap 460. Cap 460 of this modified example is composed of a single member. That is, in this modified example, cap 460 is formed as a single member including a fan and a fixed member. Note that, as long as gap G can be formed, cap 460 may have only a fixed member and may not have a fan. Shaft 21 is press-fitted into rotor core 24 and cap 460.

[0095] The cap 460 is annular. The cap 460 has a facing portion 440 and a cover portion 405b. The facing portion 440 and the cover portion 405b are arranged side by side in the axial direction. The facing portion 440 and the cover portion 405b are each annular.

[0096] The facing portion 440 has an inner circumferential surface 440q facing radially inward. The inner circumferential surface 440q surrounds the shaft 21 from the radially outer side. The inner circumferential surface 440q faces the outer circumferential surface 21p of the shaft 21 in the radial direction. The facing portion 440 contacts the end surface 24f of the rotor core 24 in the axial direction. A gap G is provided between the inner circumferential surface 440q of the facing portion 440 and the outer circumferential surface 21p of the shaft 21.

[0097] The cover portion 405b is located on one axial side (+Y) of the opposing portion 440. An inner circumferential surface 405q of the cover portion 405b contacts an outer circumferential surface 21p of the shaft 21 in the radial direction. The cover portion 405b covers the gap G from one axial side (+Y). More specifically, an inner circumferential step surface connecting the inner circumferential surface 440q of the opposing portion 440 and the inner circumferential surface 405q of the cover portion 405b faces the end surface 24f of the rotor core 24 in the axial direction. The gap G is covered from one axial side (+Y side) by the inner circumferential step surface.

[0098] According to this modification, similarly to the above-described embodiment, gap G can easily accommodate contamination that occurs when shaft 21 is press-fitted into rotor core 24 and when shaft 21 is press-fitted into cap 460. Also, according to this modification, cap 460 can be formed from a single member. Therefore, the number of parts of rotor 420 can be reduced.

[0099] (Variation 5) 10 is a partial cross-sectional view of rotor 520 of modified example 5, showing a portion corresponding to region V in FIG. 1. As in the above-described embodiment, rotor 520 of this modified example includes shaft 521, rotor core 24, and cap 560. Cap 560 of this modified example has opposing portion 540 and cover portion 505b. Cover portion 505b is a part of shaft 521. Shaft 521 is press-fitted into rotor core 24.

[0100] The facing portion 540 has an inner circumferential surface 540q facing radially inward. The inner circumferential surface 540q surrounds the shaft 521 from the radially outer side. The inner circumferential surface 540q faces an outer circumferential surface 521p of the shaft 21 in the radial direction. The facing portion 540 contacts the end surface 24f of the rotor core 24 in the axial direction. A gap G is provided between the inner circumferential surface 540q of the facing portion 540 and the outer circumferential surface 521p of the shaft 521.

[0101] The cover portion 505b protrudes radially outward from the outer circumferential surface 521p of the shaft 521. In this modification, the cover portion 505b extends in an annular shape along the circumferential direction. The cover portion 505b is located on one axial side (+Y) of the facing portion 540. The cover portion 505b overlaps with at least a part of the facing portion 540 on the one axial side (+Y). Preferably, the cover portion 505b contacts with at least a part of the facing portion 540 on the one axial side (+Y). The cover portion 505b faces the end face 24f of the rotor core 24 in the axial direction. The cover portion 505b covers the gap G from the one axial side (+Y). The cover portion 505b does not necessarily have to be annular, but may extend along the circumferential direction.

[0102] According to this modification, similarly to the above-described embodiment, it becomes easier to accommodate contamination generated when shaft 521 is press-fitted into rotor core 24 in gap G. Also, according to this modification, by providing cover portion 505b, which is a part of cap 560, on outer circumferential surface 521p of shaft 521, it is possible to reduce the number of parts of rotor 520.

[0103] (Variation 6) 11 is a schematic cross-sectional view of the facing portion 640 of the cap 660 and the shaft 21 according to Modification 6. This modification differs from the above-described embodiment in that the gaps G are arranged discretely along the circumferential direction.

[0104] In this modification, a plurality of first recesses 640e (four in this modification) are provided on the inner peripheral surface 640q of the facing portion 640. The plurality of first recesses 640e are arranged at equal intervals along the circumferential direction. The inner peripheral surface 640q of the facing portion 640 contacts the outer peripheral surface 21p of the shaft 21 at a portion other than the first recesses 640e. Therefore, in this modification, a plurality of gaps G are provided between the inner peripheral surface 640q of the facing portion 640 and the outer peripheral surface 21p of the shaft 21 and arranged along the circumferential direction. In this modification, the circumferential width, radial width, and axial width of the plurality of gaps G are equal to each other.

[0105] In this modification, an inner peripheral surface 624q of a rotor core 624 is provided with a plurality of second recesses 624e (four in this modification) arranged in the circumferential direction, and press-fit portions 624d located between adjacent second recesses 624e in the circumferential direction. In this modification, the second recesses 624e and the press-fit portions 624d are arranged alternately in the circumferential direction. An inner peripheral surface 640q of the facing portion 640 is press-fitted into the shaft 21 at the press-fit portions 624d. When viewed from the axial direction, the press-fit portions 624d overlap the gap G. According to this modification, contamination occurring in the plurality of press-fit portions 624d arranged discretely in the circumferential direction can be accommodated in the gap G.

[0106] In this modification, a case has been described in which the first recess 640e is provided on the inner circumferential surface 640q of the facing portion 640, thereby providing the gap G between the inner circumferential surface 640q of the facing portion 640 and the outer circumferential surface 21p of the shaft 21. However, the gap G may be provided by providing a recess in a portion of the outer circumferential surface 21p of the shaft 21 that faces the facing portion. In addition, in this modification, the circumferential width, radial width, and axial width of the multiple gaps G may all be different for each gap G, or at least one gap G may have the same width. In addition, the multiple gaps G shown in this modification may be combined with other modifications.

[0107] Although various embodiments and modifications of the present invention have been described above, the configurations and combinations thereof in each embodiment and modification are merely examples, and addition, omission, substitution, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0108] For example, in the above embodiment, the coil is a bendable conductor attached to the stator, and the lead wire extending from the coil has a structure in which multiple conductor wires are bundled with a crimp terminal. However, the coil may be a segment coil made of a highly rigid rectangular wire, and the lead wire extending from the coil may also be a single rectangular wire.

[0109] The present technology can be configured as follows. (1) A rotor rotatable around a central axis, comprising: a shaft extending along the central axis; an annular rotor core into which the shaft is inserted; and a cap located on one axial side of the rotor core and provided on the shaft, wherein the cap has an opposing portion surrounding the shaft from the radially outside and in contact with an end face facing one axial side of the rotor core, and a cover portion located on one axial side of the opposing portion, wherein a gap is provided between an inner surface of the opposing portion and an outer circumferential surface of the shaft, and the cover portion covers the gap from one axial side. (2) The rotor according to (1), wherein the shaft is press-fitted into the inner circumferential surface of the rotor core. (3) The rotor according to (2), wherein a groove is provided on an outer circumferential surface of the shaft that faces an inner circumferential surface of the rotor core. (4) A rotor described in any one of (1) to (3), wherein the cap has a fixed member fixed to the shaft and an opposing member located between the fixed member and the rotor core in the axial direction and having a first hole portion through which the shaft is inserted, the opposing member has the opposing portion, and the fixed member has the cover portion. (5) The rotor described in (4), wherein the fixing member has a second hole portion through which the shaft is inserted, the shaft is press-fitted into the inner circumferential surface of the second hole portion, and a groove portion is provided on the outer circumferential surface of the shaft that faces the inner circumferential surface of the second hole portion. (6) A rotor as described in (4) or (5), wherein the fixing member has a cylindrical tubular portion centered on the central axis and the cover portion protruding radially outward from the other axial end of the cylindrical portion and extending circumferentially. (7) The rotor described in any one of (1) to (6), wherein the shaft has a first outer peripheral surface facing an inner peripheral surface of the rotor core, a second outer peripheral surface facing an inner peripheral surface of the opposing portion and having an outer diameter smaller than that of the first outer peripheral surface, and an outer peripheral step surface connecting the first outer peripheral surface and the second outer peripheral surface. (8) The rotor described in any one of (1) to (6), wherein the opposing portion has a first inner circumferential surface, a second inner circumferential surface located on one axial side of the first inner circumferential surface and having a smaller inner diameter than the first inner circumferential surface, and an inner circumferential step surface connecting the first inner circumferential surface and the second inner circumferential surface. (9) The rotor described in any one of (1) to (6), wherein the shaft has a first outer peripheral surface facing an inner peripheral surface of the rotor core, a second outer peripheral surface located on one axial side of the first outer peripheral surface and having an outer diameter smaller than the first outer peripheral surface, and an outer peripheral step surface connecting the first outer peripheral surface and the second outer peripheral surface, and the opposing portion has a first inner peripheral surface, a second inner peripheral surface located on one axial side of the first inner peripheral surface and having an inner diameter smaller than the first inner peripheral surface, and an inner peripheral step surface connecting the first inner peripheral surface and the second inner peripheral surface, and the second outer peripheral surface and the first inner peripheral surface radially face each other via the gap. (10) The rotor according to any one of (1) to (9), wherein the gap extends annularly along the circumferential direction. (11) The rotor according to any one of (1) to (9), wherein a plurality of the gaps are provided between an inner peripheral surface of the opposing portion and an outer peripheral surface of the shaft and are aligned in a circumferential direction. (12) A rotor as described in any one of (1) to (11), wherein the shaft has a recess that opens at one end in the axial direction and into which the end of the other shaft is inserted, and the recess is positioned at a different position in the axial direction from the rotor core. (13) A rotor described in any one of (1) to (12), wherein the rotor core has an air hole penetrating in the axial direction, the opposing portion has a through hole connected to the air hole and penetrating the opposing portion in the axial direction, and the cover portion is provided at a position different from the through hole when viewed in the axial direction. (14) A rotating electric machine comprising: a rotor according to any one of (1) to (13); and a stator surrounding the rotor from a radially outer side. (15) A drive device comprising: a rotating electric machine according to (14); and a power transmission mechanism that transmits power of the rotating electric machine. [Explanation of symbols]

[0110] 1... drive device, 2... rotating electric machine, 5... fixed member, 5b, 405b, 505b... cover portion, 5d... cylinder portion, 5h... second hole portion, 5q, 24q, 40q, 405q, 440q, 540q, 624q, 640q... inner peripheral surface, 20, 120, 220, 320, 420, 520... rotor, 21, 121, 521... shaft, 21h, 21i, 21j... groove portion, 21p, 521p... outer peripheral surface, 24, 624... rotor core, 24a, 2 4b...ventilation hole, 24f...end surface, 29...recess, 30...stator, 40,240,440,540,640...opposing portion, 40h,240h...first hole portion, 42...through hole, 50...power transmission mechanism, 60,260,460,560,660...cap, 121p...first outer peripheral surface, 121q...second outer peripheral surface, 121t...outer peripheral step surface, 240p...first inner peripheral surface, 240q...second inner peripheral surface, 240t...inner peripheral step surface, G...gap, J...central axis

Claims

1. A rotor rotatable about a central axis, A shaft extending along a central axis; an annular rotor core into which the shaft is inserted; a cap located on one axial side of the rotor core and provided on the shaft, The cap is an opposing portion that surrounds the shaft from the radially outer side and contacts an end surface of the rotor core that faces one axial side; a cover portion located on one axial side of the opposing portion, A gap is provided between an inner circumferential surface of the opposing portion and an outer circumferential surface of the shaft, The cover portion covers the gap from one axial side. Rotor.

2. The shaft is press-fitted into the inner circumferential surface of the rotor core. The rotor of claim 1 .

3. A groove is provided on an outer circumferential surface of the shaft, the groove being located in a portion facing an inner circumferential surface of the rotor core. A rotor as claimed in claim 2.

4. The cap is A fixing member fixed to the shaft; an opposing member located between the fixed member and the rotor core in the axial direction and having a first hole portion through which the shaft is inserted, The opposing member has the opposing portion, The fixing member has the cover portion. The rotor of claim 1 .

5. The fixing member has a second hole portion through which the shaft is inserted, The shaft is press-fitted into the inner circumferential surface of the second hole portion, A groove is provided on an outer circumferential surface of the shaft, the groove being located in a portion facing an inner circumferential surface of the second hole portion. A rotor according to claim 4.

6. The fixing member is A cylindrical portion having a cylindrical shape centered on the central axis line; The cover portion protrudes radially outward from the other axial end of the cylindrical portion and extends in the circumferential direction. A rotor according to claim 4.

7. The shaft is a first outer circumferential surface facing an inner circumferential surface of the rotor core; a second outer circumferential surface facing the inner circumferential surface of the facing portion and having an outer diameter smaller than that of the first outer circumferential surface; and an outer circumferential step surface connecting the first outer circumferential surface and the second outer circumferential surface. The rotor of claim 1 .

8. The facing portion is A first inner circumferential surface; a second inner circumferential surface located on one axial side of the first inner circumferential surface and having an inner diameter smaller than that of the first inner circumferential surface; an inner peripheral step surface connecting the first inner peripheral surface and the second inner peripheral surface; The rotor of claim 1 .

9. The shaft is a first outer circumferential surface facing an inner circumferential surface of the rotor core; a second outer circumferential surface located on one axial side of the first outer circumferential surface and having an outer diameter smaller than that of the first outer circumferential surface; an outer circumferential step surface connecting the first outer circumferential surface and the second outer circumferential surface; The facing portion is A first inner circumferential surface; a second inner circumferential surface located on one axial side of the first inner circumferential surface and having an inner diameter smaller than that of the first inner circumferential surface; an inner peripheral step surface connecting the first inner peripheral surface and the second inner peripheral surface, The second outer circumferential surface and the first inner circumferential surface face each other in a radial direction with the gap therebetween. The rotor of claim 1 .

10. The gap extends annularly along the circumferential direction. A rotor according to any one of claims 1 to 9.

11. A plurality of the gaps are provided between an inner peripheral surface of the opposing portion and an outer peripheral surface of the shaft, the gaps being arranged in a circumferential direction. A rotor according to any one of claims 1 to 9.

12. The shaft has a recess that opens at one end in the axial direction and into which an end of another shaft is inserted, The recess is disposed at a position different from the rotor core in the axial direction. The rotor of claim 1 .

13. The rotor core has an air hole passing through in the axial direction, The facing portion has a through hole that is connected to the air hole and passes through the facing portion in the axial direction, The cover portion is provided at a position different from the through hole when viewed in the axial direction. The rotor of claim 1 .

14. A rotor according to claim 1; A stator surrounding the rotor from the radially outer side. Rotating electric motor.

15. A rotating electric machine according to claim 14; a power transmission mechanism that transmits power of the rotating electric machine.

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