Rotary electric machine

Abstract

To provide a rotary electric machine capable of reliably suppressing reduction of motor performance while stabilizing a behavior of a rotor.SOLUTION: A rotary electric machine comprises a stator 22 and a rotor 23 which is provided to be freely rotatable with respect to the stator 22. The stator 22 includes a stator core 24 and a coil 26 which is wound around the stator core 24. The rotor 23 includes a rotor shaft 27 which is supported by a first bearing 16A in a cantilevered manner and rotated around a rotation axis A, a rotor core 42 which is fixed closer to an end 27a of the rotor shaft 27 on an opposite side of the first bearing 16A, and a magnet 43 which is provided on a peripheral surface of the rotor core 42. A center Cs of the stator core 24 in a direction of the rotation axis A is positioned closer to the first bearing 16A than a center Cm of the magnet 43 in the direction of the rotation axis A.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine. [Background technology]

[0002] Examples of rotating electric machines include electric motors and generators. Some electric motors include a stator and a rotor rotatably mounted relative to the stator. The stator includes a stator core and a coil wound around the stator core. The rotor includes a rotor shaft, a rotor core fixed to the rotor shaft, and magnets mounted on the rotor core. The magnets are arranged with their magnetic poles aligned in a circumferential direction. With this configuration, when current is supplied to the coils, a flux linkage is formed in the stator core. Magnetic attraction and repulsion are generated between this flux linkage and the magnets, causing the rotor to continue rotating.

[0003] However, if the magnet is shifted to one side of the motor shaft in the direction of its axis of rotation, the center of gravity of the rotor will move away from the center of the rotor shaft in the direction of its axis of rotation, and even a slight deflection will cause a large dynamic imbalance, making the rotor's behavior unstable. In a so-called geared motor, in which an electric motor and a reducer are integrated, the rotor shaft is sometimes cantilevered by a bearing provided in the reducer to reduce the size of the geared motor. In such a case, if the rotor is moved closer to the bearing to account for dynamic imbalance, the center of the magnet's rotational axis will be misaligned with the center of the stator's rotational axis. This can result in the magnet's effective magnetic flux not effectively contributing to the rotor's rotational torque, potentially resulting in a deterioration in motor performance.

[0004] Therefore, a technique has been proposed for improving the dynamic imbalance of the rotor to stabilize the behavior of the rotor while suppressing the deterioration of the motor characteristics (see, for example, Patent Document 1). In this structure, the positions of both end faces of the magnet in the direction of the rotation axis are on the same plane as the both end faces of the stator core in the direction of the rotation axis or are located further outward in the direction of the rotation axis than these end faces. The position of the end face of the rotor core opposite the bearing is located closer to the bearing than the position of the end face of the magnet opposite the bearing. The position of the bearing-side end face of the rotor core is located closer to the bearing than the position of the bearing-side end face of the magnet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-35187 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-mentioned conventional technology, both the magnet and the rotor core are spaced apart from the stator core in the direction of the rotation axis, leaving room for improvement in motor performance.

[0007] Therefore, the present invention provides a rotating electric machine that can reliably suppress a decrease in motor performance while stabilizing the behavior of the rotor. [Means for solving the problem]

[0008] In order to solve the above problems, in a first aspect of the present invention, a rotating electric machine comprises a stator and a rotor rotatably arranged relative to the stator, the stator having a stator core and a coil wound around the stator core, the rotor having a rotor shaft cantilevered on a bearing and rotating around a rotation axis, a rotor core fixed to the rotor shaft near the end opposite the bearing, and a magnet arranged on the circumferential surface of the rotor core, and the center of the stator core in the direction of the rotation axis is located closer to the bearing than the center of the magnet in the direction of the rotation axis.

[0009] This configuration allows the entire rotor to generate a thrust force in the bearing direction due to magnetic attraction, thereby stabilizing the behavior of the rotor and reliably suppressing a decline in motor performance.

[0010] In a second aspect of the present invention, in the rotating electric machine of the first aspect, the stator core has a cylindrical back yoke portion and a plurality of tooth portions that protrude radially from the circumferential surface of the back yoke portion and around which the coil is wound, and a jumper portion of the coil that is routed between predetermined tooth portions is arranged on one of both end faces of the stator core in the rotational axis direction, and both end faces of the magnet in the rotational axis direction protrude from both end faces of the stator core in the rotational axis direction, and the protruding length of the magnet from one end face of the stator core may be shorter than the protruding length of the magnet from the other end face of the both end faces of the stator core in the rotational axis direction.

[0011] Of the two end faces of the stator core in the direction of the rotation axis, the end face on which the coil crossover wire is located is more likely to become hotter than the other end face on which the crossover wire is not located. Therefore, by making the length of the magnet protruding from one end face of the stator core shorter than the length of the magnet protruding from the other end face of the stator core, thermal damage to the magnet can be suppressed, thereby more reliably suppressing deterioration of motor performance.

[0012] In a third aspect of the present invention, in the rotating electric machine of the first or second aspect, the center of the stator core in the direction of the rotational axis may be located between the center of the magnet in the direction of the rotational axis and the center of the rotor core in the direction of the rotational axis.

[0013] This configuration minimizes the misalignment of the entire rotor (rotor core and magnet) relative to the stator core in the direction of the rotation axis, thereby reliably preventing a decrease in motor performance. On the other hand, the amount of misalignment between the rotor core and the magnet in the direction of the rotation axis can be increased. This allows for a greater amount of thrust to be generated in the entire rotor in the direction of the rotation axis due to magnetic attraction. This stabilizes the position of the rotor in the direction of the rotation axis relative to the stator core. This reduces variation in motor performance and stabilizes it.

[0014] In a fourth aspect of the present invention, in the rotating electric machine of the third aspect, the rotor core has a cylindrical core main body and a plurality of salient poles formed to protrude radially outward from the outer peripheral surface of the core main body, the plurality of salient poles extending along the rotation axis direction and arranged at predetermined intervals in the circumferential direction, the magnets are each arranged between two of the salient poles adjacent to each other in the circumferential direction, and the amount of deviation of the center of the salient pole in the rotation axis direction from the center of the magnet in the rotation axis direction may be greater than the amount of deviation of the center of the salient pole in the rotation axis direction from the center of the stator core in the rotation axis direction.

[0015] The salient poles generate reluctance torque, which rotates the rotor core in a way that reduces the magnetic resistance (reluctance) of the magnetic path of the interlinked magnetic flux. By making the offset of the center of the salient pole in the direction of the rotation axis from the center of the magnet in the direction of the rotation axis greater than the offset of the center of the salient pole in the direction of the rotation axis from the center of the rotation axis of the stator core in the direction of the rotation axis, the ratio of magnet torque to reluctance torque can be increased. This reduces the effect of iron loss due to reluctance torque, and suppresses degradation of motor performance.

[0016] In a fifth aspect of the present invention, in the rotating electric machine of any one of the first to third aspects, the rotor core has a core body portion formed in a cylindrical shape and a plurality of salient poles formed so as to protrude radially outward from an outer circumferential surface of the core body portion, the plurality of salient poles extending along the rotation axis direction and arranged at predetermined intervals in the circumferential direction, the magnets are respectively arranged between two of the salient poles adjacent to each other in the circumferential direction, and two holders are provided on both end surfaces of the rotor core in the rotation axis direction and restrict movement of the magnets in the rotation axis direction and circumferential direction, and each of the holders is provided with a holder for holding the core body portion. The holder may have an annular portion disposed on both end faces and on a radially inner side surface of the magnet, a plurality of legs protruding radially outward from the outer peripheral surface of the annular portion and disposed between two circumferentially adjacent magnets, and end plate portions integrally connected to the annular portion and the legs on the side opposite the rotor core, wherein when the length between the end plate portions of the two holders is L1, the length of the magnet in the rotational axis direction is L2, and the amount of deviation of the center of the salient pole in the rotational axis direction from the center of the stator core in the rotational axis direction is L3, the length L1, the length L2, and the amount of deviation L3 may satisfy L1-L2>L3.

[0017] With this configuration, the magnet can be easily positioned relative to the rotor core by the holder. Since the misalignment between the stator core and rotor core in the direction of the rotation axis can be minimized, the decrease in reluctance torque can be suppressed. In addition, the decrease in magnet torque can be suppressed, so the decrease in motor performance can be suppressed.

[0018] In a sixth aspect of the present invention, in the rotating electric machine of the fifth aspect, a magnet cover is attached to the rotor core from one side in the direction of the rotation axis and covers the rotor core, the magnet, and the holder, and each of the holders may have protrusions formed on both circumferential sides of each of the legs and abutting against both circumferential sides of the magnet.

[0019] With this configuration, the magnet can be reliably positioned in the circumferential direction relative to the rotor core by the holder. The magnet cover also reliably protects the rotor core, magnet, and holder. Because the magnet cover is attached to one side of the rotor core in the direction of the rotation axis, the magnet is pressed against the holder, which is located on the other side of the rotor core in the direction of the rotation axis, when the magnet cover is attached. The end of the magnet on the side pressed against the holder is pushed outward by the protrusion toward the opposite side. In other words, the magnet gradually widens toward the outside in the circumferential direction as it moves downstream in the attachment direction of the magnet cover. This makes it easier to attach the magnet cover along the magnet, improving the assembly of the rotating electric machine. [Effects of the Invention]

[0020] According to the present invention, it is possible to reliably suppress a decrease in motor performance of a rotating electric machine while stabilizing the behavior of the rotor of the rotating electric machine. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view of a motor with a reducer according to an embodiment of the present invention; [Figure 2] 1 is a cross-sectional view taken along the rotation axis of a motor with a reducer according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view taken along the rotation axis of an electric motor according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view taken along the rotation axis of a rotor according to an embodiment of the present invention. [Figure 5] FIG. 2 is a perspective view of a rotor according to an embodiment of the present invention. [Figure 6] FIG. 2 is an exploded perspective view of a rotor according to an embodiment of the present invention. [Figure 7] 2 is a plan view of a rotor core and a magnet according to an embodiment of the present invention, viewed from the direction of the rotation axis. FIG. [Figure 8] 5A to 5C are cross-sectional views illustrating the manufacturing process of the rotor according to the embodiment of the present invention, and show the respective steps. DETAILED DESCRIPTION OF THE INVENTION

[0022] Next, an embodiment of the present invention will be described with reference to the drawings.

[0023] <Motor with reduction gear> FIG. 1 is a perspective view of a motor with a reducer 1 as a rotating electric machine according to an embodiment of the present invention. The speed reducer-equipped motor 1 serves as a drive source for electrical equipment (such as wipers, power windows, sunroofs, and power seats) mounted on a vehicle, for example. As shown in Figure 1, the motor with a reducer 1 comprises a housing 10 that forms the outer shell of the motor with a reducer 1, an electric motor 20 provided in the housing 10, a reducer 30 provided within the housing 10 that reduces the rotation of the electric motor 20 and outputs it, and a controller 4 provided within the housing 10 that controls the drive of the electric motor 20.

[0024] FIG. 2 is a cross-sectional view showing the speed reducer-equipped motor 1. As shown in FIG. 1 and 2, the housing 10 is made of a material with excellent heat dissipation properties, such as aluminum die-cast. The housing 10 includes a housing main body 11 that holds the electric motor 20 and the reducer 30, and a cover 12.

[0025] The housing body 11 has a reducer accommodating section 13 with an opening 13a formed on one side. The reducer accommodating section 13 accommodates the reducer 30. The reducer accommodating section 13 is formed by a bottom 13b and a peripheral wall 13w that rises from the outer periphery of the bottom 13b. The opening 13a is formed by the peripheral wall 13w.

[0026] The reducer accommodating section 13 is formed with a shaft accommodating groove 14 that accommodates a worm shaft 31 (described later) and a wheel accommodating recess 15 that accommodates a worm wheel 32. A pair of bearings 16A, 16B (first bearing 16A and second bearing 16B) that rotatably support the worm shaft 31 (rotor shaft 27) are provided at both axial ends of the shaft accommodating groove 14 within the reducer accommodating section 13. The electric motor 20 and the reducer 30 are arranged side by side along the rotational axis A of the worm shaft 31.

[0027] A cylindrical motor accommodating portion 17 is integrally formed on the outer periphery of the housing body 11, protruding outward from the peripheral wall portion 13w along the rotation axis A. The motor accommodating portion 17 accommodates a portion of the electric motor 20. A shaft insertion hole 17a is formed inside the motor accommodating portion 17, penetrating the peripheral wall portion 13w and communicating with the first bearing 16A of the pair of bearings 16A, 16B. A boss 19 protruding from the bottom 13b to the side opposite the opening 13a is integrally formed with the housing body 11. A through-hole (not shown) communicating with the wheel-accommodating recess 15 is formed in the boss 19.

[0028] A cover 12 is provided to close the opening 13a of the reducer accommodating portion 13. The cover 12 is fastened to the housing main body 11 at multiple locations on its outer periphery with bolts (not shown). A connector receiving portion 12c is formed in the cover 12. The connector receiving portion 12c is adjacent to the motor accommodating portion 17 when the cover 12 is attached to the housing main body 11. The connector receiving portion 12c is formed in a cylindrical shape and has a terminal (not shown) inside. An external power supply connector (not shown) is connected to the connector receiving portion 12c, and an external power source (not shown) is electrically connected to the terminal.

[0029] <Electric motor> 3 is a cross-sectional view taken along the rotation axis A of the electric motor 20. In the following description, the direction parallel to the rotation axis A is referred to as the axial direction, the direction around the rotation axis A is referred to as the circumferential direction, and the direction perpendicular to the axial and circumferential directions is referred to as the radial direction. As shown in Figure 3, the electric motor 20 includes a motor cover 21 attached to the motor housing section 17, a cylindrical stator 22 housed within the motor housing section 17 and the motor cover 21 and arranged coaxially with the rotation axis A, and a rotor 23 arranged radially inside the stator 22 and rotatable relative to the stator 22.

[0030] The motor cover 21 is formed into a cylindrical shape with a bottom by applying a deep drawing press process to a metal plate such as iron. A flange 21a (see also FIG. 1) that protrudes radially outward is formed at the open end of the motor cover 21. The motor cover 21 is fastened to the motor housing portion 17 by bolts 21b inserted through the flange 21a.

[0031] <Stator> The stator 22 is disposed along the inner peripheral surface of the motor cover 21. The stator 22 includes a stator core 24, an insulator 29 attached to the stator core 24, a coil 26 wound around the stator core 24, and a terminal holder 9 disposed on the stator core 24. The stator core 24 is formed by stacking a plurality of steel plates 24p. However, the stator core 24 is not limited to being formed by stacking a plurality of steel plates 24p, and may be formed by, for example, pressure molding soft magnetic powder.

[0032] The stator core 24 includes a cylindrical back yoke portion 7 and a plurality of teeth 25 that protrude radially inward from the inner peripheral surface of the back yoke portion 7. The outer peripheral surface of the back yoke portion 7 is fitted into the inner peripheral surface of the motor cover 21. The teeth 25 extend radially and are arranged at equal intervals in the circumferential direction.

[0033] The insulators 29 are made of insulating resin. The insulators 29 have inner wall portions 29a formed radially inside the teeth 25 and outer wall portions 29b formed radially outside the teeth 25. The inner wall portions 29a and the outer wall portions 29b are formed so as to surround the teeth 25 and rise up from the teeth 25. The coils 26 are wound around each tooth 25 so that the coils 26 are stored in coil storage portions 29c formed by the inner wall portions 29a and the outer wall portions 29b.

[0034] The coil 26 has a crossover portion 26a that is routed between predetermined teeth 25. The crossover portion 26a is disposed on the end surface 24a of the stator core 24 that faces the reducer 30 and radially outside the outer wall portion 29b of the insulator 29. Furthermore, a terminal holder 9 is disposed on an end surface 24a of the stator core 24. The terminal holder 9 is provided with a terminal 9a that is connected to the controller 4. The controller 4 and the coil 26 are electrically connected via this terminal 9a.

[0035] <Rotor> Fig. 4 is a cross-sectional view taken along the axial direction of the rotor 23. Fig. 5 is a perspective view of the rotor 23. As shown in FIGS. 4 and 5, the rotor 23 includes a rotor shaft 27 arranged coaxially with the rotation axis A, and a rotor body 28 fitted and fixed to the rotor shaft 27.

[0036] The rotor body 28 includes a rotor core 42 that is press-fitted onto the rotor shaft 27, a magnet 43 that is attached to the rotor core 42, magnet holders 44A, 44B (first magnet holder 44A, second magnet holder 44B) for holding the magnet 43, and a magnet cover 45. The magnet holders 44A, 44B are arranged to sandwich the magnet 43 in the axial direction, thereby preventing the magnet 43 from falling off from the rotor core 42 in the axial direction.

[0037] <Rotor core> FIG. 6 is an exploded perspective view of the rotor 23. As shown in FIG. 4 to 6, the rotor shaft 27 is integrally formed with a worm shaft 31 that constitutes the reducer 30 (see also FIG. 2). A rotor core 42 is fitted and fixed to the rotor shaft 27 near an end 27a on the opposite side from the reducer 30. The rotor core 42 is formed by stacking a plurality of steel plates 42p. However, the rotor core 42 is not limited to being formed by stacking a plurality of steel plates 42p, and may be formed, for example, by pressure molding soft magnetic powder. The axial thickness of the rotor core 42 is the same as the axial thickness of the stator core 24.

[0038] The rotor core 42 includes a cylindrical rotor core body 47 and a plurality of salient pole portions 48 that protrude radially outward from an outer peripheral surface 47b of the rotor core body 47. A through-hole 47a that penetrates the rotor core body 47 in the axial direction is formed in the radial center of the rotor core body 47. The rotor shaft 27 is press-fitted into the through-hole 47a, for example, to fit and fix the rotor core 42 to the rotor shaft 27 (see also FIG. 3). This allows the rotor shaft 27 and the rotor core 42 to rotate integrally. The rotor shaft 27 is press-fitted into the through-hole 47a. Alternatively, the rotor shaft 27 may be inserted into the through-hole 47a, and the rotor core 42 may be fit and fixed to the rotor shaft 27 using an adhesive or the like.

[0039] The multiple salient pole portions 48 are arranged, for example, four at equal intervals of 90° in the circumferential direction. The salient pole portions 48 are formed to extend over the entire axial direction of the rotor core body 47. In other words, the axial thickness of the rotor core body 47 and the axial thickness of the salient pole portions 48 are the same. The salient pole portions 48 are formed so that both side surfaces 48a that face each other in the circumferential direction are parallel. In other words, the salient pole portions 48 are formed so that the circumferential width dimension is uniform in the radial direction. One groove 48c is formed over the entire axial direction in the radially outer end portion 48b of the salient pole portion 48. The groove 48c is located in the circumferential center of the outer end portion 48b.

[0040] <Magnet> FIG. 7 is a plan view of the rotor core 42 and the magnet 43 as viewed from the axial direction. 6 and 7, the magnets 43 are arranged on the outer peripheral surface 47b of the rotor core body 47, and between adjacent salient pole portions 48 in the circumferential direction. That is, four magnets 43 are arranged. The magnets 43 are segment-type magnets with a sector-shaped cross section along the radial direction.

[0041] The magnet 43 has an inner peripheral surface 43a on the radially inner side, an outer peripheral surface 43b on the radially outer side, and side surfaces 43c on both circumferential sides. The inner peripheral surface 43a and the outer peripheral surface 43b are formed in an arc shape when viewed in the axial direction. The side surface 43c has an inner surface 43d located on the radially inner side and connected to the inner peripheral surface 43a, and an outer surface 43e located on the radially outer side and connected to the outer peripheral surface 43b.

[0042] The inner surface 43d faces the side surface 48a of the salient pole portion 48 in the radial direction. The inner surface 43d and the side surface 48a of the salient pole portion 48 are substantially parallel. The contact between the inner surface 43d and the side surface 48a of the salient pole portion 48 determines the positioning of the magnet 43 in the circumferential direction. The outer surface 43e is formed flat and inclined so as to gradually separate in the circumferential direction from the side surface 48a of the salient pole portion 48 as it moves radially outward from the connection portion with the inner surface 43d. In one magnet 43, the two outer surfaces 43e on both sides in the circumferential direction are parallel to each other.

[0043] The axial length of each magnet 43 is longer than the axial length of rotor core 42. Therefore, when assembled to rotor core 42, each magnet 43 has a first overhang portion 43f protruding from a first end face 42a of rotor core 42 on the axial side of reducer 30, and a second overhang portion 43g protruding from a second end face 42b of rotor core 42 on the axial side opposite to reducer 30 (toward end 27a of rotor shaft 27).

[0044] Such magnets 43 are preferably magnetized so that the orientation of the magnetization (magnetic field) is parallel along the radial direction (thickness direction). Each magnet 43 is arranged so that the magnetic poles alternate in the circumferential direction. Therefore, in this embodiment, the rotor 23 has four magnetic poles. The salient pole portions 48 of the rotor core 42 are located at the boundaries of the magnetic poles (pole boundaries). For example, a sintered ferrite magnet is used as the magnet 43. However, the present invention is not limited to this, and instead of the sintered ferrite magnet, a ferrite bonded magnet, a neodymium bonded magnet, a neodymium sintered magnet, or the like can also be used as the magnet 43.

[0045] <Magnet holder> Of the two magnet holders 44A, 44B, the first magnet holder 44A is disposed on the first end face 42a of the rotor core 42. Of the two magnet holders 44A, 44B, the second magnet holder 44B is disposed on the second end face 42b of the rotor core 42. The magnet holders 44A, 44B are disposed symmetrically in the axial direction around the rotor core 42. For this reason, the magnet holders 44A, 44B will be described using the same reference numerals.

[0046] Each of the magnet holders 44A, 44B includes a disk-shaped end plate portion 44c and a core placement portion 44d formed integrally with the end plate portion 44c. The material of each of the magnet holders 44A, 44B may be, for example, a non-magnetic resin material. The outer diameter of the end plate portion 44c is approximately the same as the diameter of an imaginary circle (not shown) that passes through the outer peripheral surface 43b of the magnet 43 attached to the rotor core 42. An opening 44e is formed in the radial center of the end plate portion 44c. A plurality of reinforcing ribs 44k are formed to protrude from an inner surface 44i of the end plate portion 44c facing the rotor core 42. Each reinforcing rib 44k extends radially from the opening 44e to the outer peripheral edge 44f.

[0047] The core arrangement portion 44d protrudes from the inner surface 44i of the end plate portion 44c toward the rotor core 42. The core arrangement portion 44d includes a cylindrical annular portion 44g and a plurality of leg portions 44h that protrude radially outward from the outer circumferential surface of the annular portion 44g. The annular portion 44g is disposed coaxially with the opening 44e of the end plate portion 44c. The inner diameter of the annular portion 44g is the same as the inner diameter of the opening 44e.

[0048] The multiple leg portions 44h extend from the annular portion 44g along the inner surface 44i of the end plate portion 44c to the outer peripheral edge 44f of the end plate portion 44c. The multiple leg portions 44h are, for example, four, arranged at equal intervals of 90° in the circumferential direction. The leg portions 44h are formed so that the opposing side surfaces 44j in the circumferential direction are parallel. In other words, the leg portions 44h are formed so that the circumferential width dimension is uniform in the radial direction. The circumferential width of the leg portions 44h is slightly smaller than the circumferential width of the salient pole portions 48 of the rotor core 42.

[0049] A pair of positioning protrusions 41 are integrally formed on both side surfaces 44j of the leg portion 44h. The positioning protrusions 41 are formed along the axial direction and over the entire axial length of the leg portion 44h. A tapered portion 41a is formed at the tip of the positioning protrusion 41 on the rotor core 42 side. The tapered portion 41a is formed so that the height of the tapered portion 41a protruding radially from the side surface 44j of the leg portion 44h gradually decreases toward the tip.

[0050] With this configuration, when the magnet 43 and the magnet holders 44A, 44B are attached to the rotor core 42, the tip of the annular portion 44g opposite the end plate portion 44c abuts against both axial end surfaces (first end surface 42a and second end surface 42b of the rotor core 42) of the rotor core main body 47. The tip of the leg portion 44h opposite the end plate portion 44c abuts against both axial end surfaces (first end surface 42a and second end surface 42b of the rotor core 42) of the salient pole portion 48.

[0051] That is, the magnet holders 44A, 44B are arranged on both axial end surfaces 42a, 42b of the rotor core 42 so as to axially sandwich the rotor core 42. The magnet 43 is arranged between the magnet holders 44A, 44B. In this case, when the length between the end plate portions 44c of the magnet holders 44A and 44B is L1 and the axial length of the magnet 43 is L2, the lengths L1 and L2 are as follows: L1>L2 (1) Therefore, the magnet 43 is held by the magnet holders 44A, 44B so that it can move in the axial direction, but is restricted from moving in the axial direction beyond a predetermined amount. After the magnet cover 45 is attached to the rotor core 42, the magnet 43 is fixed by the magnet cover 45, and its movement in the axial direction is restricted.

[0052] Additionally, the inner surface 43d of the magnet 43 is pressed from both sides in the circumferential direction against the positioning protrusions 41 of either of the magnet holders 44A, 44B. Therefore, the magnet 43 is positioned in the circumferential direction by each of the magnet holders 44A, 44B. The magnet 43 and the magnet holders 44A, 44B are covered by a magnet cover 45.

[0053] <Magnetic cover> The magnet cover 45 is made of a non-magnetic material such as stainless steel. As shown in Figures 4 to 6, the magnet cover 45 has a cylindrical portion 45a that covers the outer peripheral surface 43b of the magnet 43 and the outer peripheral edge 44f of each magnet holder 44A, 44B, and two flange portions 45b, 45c (first flange portion 45b, second flange portion 45c) integrally molded at both axial ends of the cylindrical portion 45a.

[0054] The inner peripheral surface of the cylindrical portion 45a is pressed against the outer peripheral surface 43b of the magnet 43. This prevents the magnet 43 from falling off the rotor core . Of the two flanges 45b, 45c, the first flange 45b covers the end plate 44c of the first magnet holder 44A from the outside in the axial direction. The first flange 45b is formed in an annular shape so as to protrude radially inward from the end of the cylindrical portion 45a on the first magnet holder 44A side.

[0055] Of the two flange portions 45b, 45c, the second flange portion 45c covers the end plate portion 44c of the second magnet holder 44B from the outside in the axial direction. The second flange portion 45c is formed in an annular shape so as to protrude radially inward from the end of the cylindrical portion 45a on the second magnet holder 44B side. With this configuration, the rotor core 42, the magnet 43, and the magnet holders 44A and 44B are integrated by the magnet cover.

[0056] <Axial positional relationship between rotor core, magnet, and stator core> Next, the axial positional relationship between the rotor core 42, the magnet 43, and the stator core 24 will be described with reference to FIGS. First, as described above, the length L1 between the end plate portions 44c of the magnet holders 44A, 44B and the axial length L2 of the magnet 43 satisfy formula (1). As a result, as shown in Fig. 4, when the second overhang portion 43g of the magnet 43 abuts against the end plate portion 44c of the second magnet holder 44B, a gap G is formed between the first overhang portion 43f and the end plate portion 44c of the first magnet holder 44A. The gap G is G = L1 - L2 (2) Meet the following.

[0057] In other words, when the second overhang portion 43g of the magnet 43 abuts against the end plate portion 44c of the second magnet holder 44B, the following is satisfied: The protruding length of the first overhang portion 43f from the first end face 42a of the rotor core 42 is defined as Lh1, and the protruding length of the second overhang portion 43g from the second end face 42b of the rotor core 42 is defined as Lh2. These protruding lengths Lh1 and Lh2 are Lh1 <Lh2 ···(3) Meet the following.

[0058] Since a reinforcing rib 44k is formed on the inner surface 44i of the end plate portion 44c, the state in which the second overhang portion 43g of the magnet 43 abuts against the end plate portion 44c of the second magnet holder 44B actually means the state in which the second overhang portion 43g abuts against the reinforcing rib 44k of the end plate portion 44c. However, the protruding height of the reinforcing rib 44k from the inner surface 44i of the end plate portion 44c is negligible with respect to the above equations (2) and (3). Therefore, the state in which the magnet 43 (second overhang portion 43g) abuts against the end plate portion 44c is synonymous with the state in which the magnet 43 abuts against the inner surface 44i if the reinforcing rib 44k is not provided on the end plate portion 44c, and the state in which the magnet 43 abuts against the reinforcing rib 44k.

[0059] Next, as shown in FIG. 3, the axial center Cs of the stator core 24 is located closer to the reducer 30 than the axial center Cm of the magnet 43. The axial center Cr of the rotor core 42 is located closer to the reducer 30 than the axial center Cs of the stator core 24. Therefore, the axial center Cs of the stator core 24 is located between the axial center Cm of the magnet 43 and the axial center Cr of the rotor core 42.

[0060] Furthermore, when the amount of deviation of the axial center Cp of the salient pole portion 48 from the axial center Cm of the magnet 43 is defined as A1, and the amount of deviation of the axial center Cp of the salient pole portion 48 from the axial center Cs of the stator core 24 is defined as A2, the deviation amounts A1 and A2 are expressed as follows: A1>A2 (4) Meet the following.

[0061] Furthermore, when the amount of deviation of the axial center Cr of the rotor core 42 from the axial center Cs of the stator core 24 is defined as L3, this deviation L3 and the gap G between the first overhang portion 43f of the magnet 43 and the end plate portion 44c of the first magnet holder 44A are expressed as follows: G>L3 (5) Meet the following. In this embodiment, the axial thickness of the rotor core body 47 and the axial thickness of the salient pole portion 48 are the same, so the axial center Cr of the rotor core 42 and the axial center Cp of the salient pole portion 48 are at the same position.

[0062] <Reducer> Returning to Fig. 2, the reducer 30 includes a worm shaft 31 rotatably supported at both ends by a pair of bearings 16A, 16B, and a worm wheel 32 meshed with the worm shaft 31. A rotor shaft 27 is integrally formed with the end of the worm shaft 31 rotatably supported by the first bearing 16A of the pair of bearings 16A, 16B, which is on the electric motor 20 side. In other words, the rotor shaft 27 is cantilevered by the first bearing 16A.

[0063] A worm gear portion 31g is formed between the pair of bearings 16A and 16B on the worm shaft 31. The worm gear portion 31g is formed so that its outer diameter is larger than the outer diameter of the worm shaft 31 (rotor shaft 27). Such a worm gear portion 31g is formed by, for example, rolling. The worm shaft 31 may be configured as a separate body from the rotor shaft 27, and the worm shaft 31 and the rotor shaft 27 may be integrated by being connected to each other.

[0064] The worm wheel 32 is formed in a disk shape. An outer peripheral gear portion 32g that meshes with the worm gear portion 31g is formed on the outer peripheral surface of the worm wheel 32. The worm wheel 32 is accommodated in the wheel accommodating recess 15 of the reducer accommodating portion 13 of the housing body 11. An output shaft 33 is provided on the worm wheel 32 on the side facing the bottom 13b of the reducer accommodating portion 13. The output shaft 33 protrudes from the radial center of the worm wheel 32. The output shaft 33 is disposed coaxially with the rotation center of the worm wheel 32. The tip of the output shaft 33 protrudes outside the housing main body 11 through a through-hole in a boss portion 19 formed in the housing main body 11. A spline 33a is formed on the tip of the output shaft 33 to connect to an electrical component (not shown).

[0065] In addition, a sensor magnet (not shown) is provided on the worm wheel 32. The rotational position of this sensor magnet is detected by a magnetic detection element 61 (described later) provided in the controller 4. In other words, the rotational position of the worm wheel 32 is detected by the magnetic detection element 61 of the controller 4.

[0066] <controller> The controller 4 has a controller board 62 on which a magnetic detection element 61 is mounted. The controller board 62 is disposed on the inner surface of the cover 12. The magnetic detection element 61 mounted on the controller board 62 faces the sensor magnet of the worm wheel 32.

[0067] Terminals 9a of the terminal holder 9 are connected to the controller board 62. This electrically connects the controller board 62 and the coil 26 via the terminals 9a. Terminals (not shown) of a connector receiving portion 12c (see FIG. 1) provided on the cover 12 are electrically connected to the controller board 62. In addition to the magnetic detection element 61, the controller board 62 is also equipped with a power module consisting of switching elements such as a FET (Field Effect Transistor) that controls the drive voltage supplied to the coil 26, and a capacitor that smooths the voltage (neither of which is shown).

[0068] <Operation of a motor with a reducer> Next, the operation of the speed reducer-equipped motor 1 will be described. In the speed reducer-equipped motor 1, when power is supplied from the controller 4 to each coil 26 of the electric motor 20, a predetermined interlinkage magnetic flux is formed in the stator 22 (teeth 25). A magnetic attraction force or repulsion force (magnetic torque) is generated between this interlinkage magnetic flux and the magnet 43 of the rotor 23.

[0069] Furthermore, interlinkage magnetic flux from stator 22 flows through salient pole portions 48 of rotor core 42. At this time, a reluctance torque is generated that rotates rotor core 42 so as to reduce the magnetic resistance (reluctance) of the magnetic path of the interlinkage magnetic flux. The magnetic torque and reluctance torque continuously rotate the rotor 23. When the rotor 23 rotates, the worm shaft 31 integrated with the rotor shaft 27 rotates, which in turn rotates the worm wheel 32 meshed with the worm shaft 31. This in turn rotates the output shaft 33 connected to the worm wheel 32, driving desired electrical equipment.

[0070] Incidentally, the rotor 23 rotates with the rotor shaft 27 supported in a cantilever manner by the first bearing 16A. In the rotor 23, when the second overhang portion 43g of the magnet 43 abuts against the end plate portion 44c of the second magnet holder 44B, the protruding length Lh1 of the first overhang portion 43f and the protruding length Lh2 of the second overhang portion 43g satisfy the above formula (3). In other words, the axial center Cr of the rotor core 42 is shifted toward the reducer 30 (first bearing 16A) with respect to the axial center Cm of the magnet 43.

[0071] Here, the specific gravity of rotor core 42 is generally greater than the specific gravity of magnet 43. Therefore, the center of gravity of rotor 23 as a whole is shifted toward first bearing 16A. As a result, when runout occurs due to rotation of rotor 23, dynamic imbalance of rotor 23 can be suppressed. Furthermore, the axial center Cs of the stator core 24 is located closer to the first bearing 16A than the axial center Cm of the magnet 43. This allows a thrust force to be generated by magnetic attraction in the direction of the first bearing 16A for the entire rotor 23. This further reduces dynamic imbalance of the rotor 23 when runout occurs due to rotation of the rotor 23.

[0072] Moreover, the axial center Cr of the rotor core 42 is located closer to the reducer 30 than the axial center Cs of the stator core 24. Therefore, the center of gravity of the rotor 23 as a whole can be shifted closer to the first bearing 16A relative to the stator core 24. As a result, when runout occurs due to rotation of the rotor 23, dynamic imbalance of the rotor 23 can be further suppressed.

[0073] More specifically, the axial center Cs of the stator core 24 is located between the axial center Cm of the magnet 43 and the axial center Cr of the rotor core 42. Therefore, the entire rotor 23 does not shift to one side in the axial direction relative to the stator core 24. As a result, the misalignment of the entire rotor 23 relative to the stator core 24 can be minimized. Therefore, the magnetic misalignment between the stator 22 and the rotor 23 can be minimized, and a decrease in the motor performance of the electric motor 20 can be suppressed.

[0074] The protruding length Lh1 of the first overhang portion 43f and the protruding length Lh2 of the second overhang portion 43g satisfy the above formula (3), so that the magnet 43 can be spaced as far away from the reducer 30 (first bearing 16A) as possible. Here, the crossover portion 26a of the coil 26 is disposed on the end face 24a of the stator core 24 on the side of the reducer 30. Of the two axial end faces of the stator core 24, the end face 24a on the side where the crossover portion 26a is disposed is more likely to become hotter due to the location of the crossover portion 26a. Therefore, by separating the magnet 43 as far as possible from the reducer 30 (first bearing 16A), thermal damage to the magnet 43 can be suppressed.

[0075] Furthermore, the deviation A1 of the axial center Cp of the salient pole portion 48 from the axial center Cm of the magnet 43 and the deviation A2 of the axial center Cp of the salient pole portion 48 from the axial center Cs of the stator core 24 satisfy the above formula (4). Therefore, the ratio of magnet torque to reluctance torque can be increased in the electric motor 20. This reduces the effect of iron loss in the rotor 23 due to reluctance torque, and suppresses a decrease in the motor performance of the electric motor 20.

[0076] Furthermore, the amount of misalignment L3 of the axial center Cr of the rotor core 42 relative to the axial center Cs of the stator core 24 and the gap G between the first overhang portion 43f of the magnet 43 and the end plate portion 44c of the first magnet holder 44A satisfy the above formula (5). Therefore, the amount of axial misalignment between the stator core 24 and the rotor core 42 can be made as small as possible, which also suppresses a decrease in reluctance torque. In addition, because a decrease in magnet torque can also be suppressed, a decrease in the motor performance of the electric motor 20 can also be suppressed.

[0077] <Motor manufacturing method> Next, a method for manufacturing the rotor 23, specifically, the manufacturing steps of the rotor 23, will be described with reference to Figures 3, 4, and 8(a) to 8(c). Figure 8 is a cross-sectional view illustrating the manufacturing steps of the rotor 23, and (a) to (c) show each step. First, as shown in Figure 8(a), magnets 43 are arranged on the outer peripheral surface 47b of the rotor core body 47, between the salient pole portions 48 adjacent in the circumferential direction. A first magnet holder 44A is arranged on the first end face 42a of the rotor core 42. A second magnet holder 44B is arranged on the second end face 42b of the rotor core 42. In this state, each magnet 43 is movable in the axial direction between the end plate portions 44c of the magnet holders 44A, 44B.

[0078] The rotor core 42, magnet 43, and magnet holders 44A, 44B assembled in this manner are placed on a mounting table 51 with the second magnet holder 44B facing downward. Then, the magnet cover 45 is fitted into the rotor core 42 by being pressed from above the first magnet holder 44A side with the second flange portion 45c side facing downward. At this time, for example, the first flange portion 45b side of the magnet cover 45 is held by the holding portion 53 of the pressing machine 52. The second flange portion 45c is not crimped and is slanted (flared) radially outward.

[0079] 8(b), as the magnet cover 45 is pushed into the rotor core 42, the cylindrical portion 45a of the magnet cover 45 is fitted to the rotor core 42, the magnet 43, and each of the first magnet holders 44A. At this time, frictional resistance between the inner peripheral surface of the cylindrical portion 45a and the outer peripheral surface 43b of the magnet 43 causes the second overhang portion 43g of the magnet 43 to abut against the end plate portion 44c of the second magnet holder 44B (see arrow Y1 in FIG. 8(b)).

[0080] As a result, the second overhang portion 43g is slightly pushed outward in the radial direction by the positioning protrusion 41 (see FIG. 6) of the second magnet holder 44B (see arrow Y2 in FIG. 8(b)). A tapered portion 41a is formed at the tip of the positioning protrusion 41 on the rotor core 42 side. Therefore, the tapered portion 41a acts as a guide to smoothly push outward in the radial direction. 8(b), the two-dot chain line shows the posture of the magnet 43 in which the second overhang portion 43g is pushed open by the positioning protrusion 41. The angle of the magnet 43 shown by the two-dot chain line is exaggerated for ease of understanding.

[0081] Because the second overhang portion 43g is pushed outward in the radial direction by the positioning protrusions 41, the magnets 43 are gradually tilted outward in the radial direction as they move toward the second magnet holder 44B. When viewed as a whole, the four magnets 43 are in a state in which they widen toward the second magnet holder 44B. This allows the magnets 43 themselves to act as guides, making it easier to push the magnet cover 45 into the rotor core 42. Furthermore, it is possible to prevent galling from occurring between the inner circumferential surface of the cylindrical portion 45a of the magnet cover 45 and the outer circumferential surface 43b of the magnet 43 (particularly near the first overhang portion 43f).

[0082] 8(c), the magnet cover 45 is pushed in until the first flange portion 45b of the magnet cover 45 abuts against the first magnet holder 44A. This causes the inner peripheral surface of the cylindrical portion 45a to be completely fitted onto the outer peripheral surface 43b of the magnet 43. In this state, the second flange portion 45c of the magnet cover 45 protrudes further toward the mounting table 51 (downward) than the second magnet holder 44B.

[0083] 4, the protruding second flange portion 45c of the magnet cover 45 is crimped radially inward, so that the second flange portion 45c abuts against the end plate portion 44c of the second magnet holder 44B. This results in the rotor core 42, magnet 43, magnet holders 44A, 44B, and magnet cover 45 being assembled together, completing the manufacturing process for the rotor 23.

[0084] As described above, in the electric motor 20, the axial center Cs of the stator core 24 is located closer to the first bearing 16A than the axial center Cm of the magnet 43. This allows a thrust force to be generated by magnetic attraction in the direction of the first bearing 16A for the entire rotor 23. This stabilizes the behavior of the rotor 23 and reliably prevents a decrease in the motor performance of the electric motor 20.

[0085] The protruding length Lh1 of the first overhang portion 43f and the protruding length Lh2 of the second overhang portion 43g satisfy the above formula (3). Therefore, the magnet 43 can be spaced as far as possible from the reducer 30 (first bearing 16A). In other words, the magnet 43 can be spaced as far as possible from the crossover portion 26a of the coil 26. Therefore, heat damage to the magnet 43 caused by the crossover portion 26a of the coil 26 can be suppressed, and deterioration of motor performance can be further reliably suppressed.

[0086] The axial center Cs of the stator core 24 is located between the axial center Cm of the magnet 43 and the axial center Cr of the rotor core 42. Therefore, the entire rotor 23 does not shift to one side in the axial direction relative to the stator core 24. As a result, the misalignment of the entire rotor 23 relative to the stator core 24 can be minimized. Therefore, the magnetic misalignment between the stator 22 and the rotor 23 can be minimized, and a decrease in the motor performance of the electric motor 20 can be suppressed.

[0087] On the other hand, the amount of axial misalignment between the rotor core 42 and the magnet 43 can be increased. This allows a thrust force to be generated in the entire rotor 23 in the axial direction due to magnetic attraction. This makes it possible to stabilize the axial position of the rotor 23 relative to the stator core 24. As a result, variations in the motor performance of the electric motor 20 can be suppressed and stabilized.

[0088] The deviation A1 of the axial center Cp of the salient pole portion 48 from the axial center Cm of the magnet 43 and the deviation A2 of the axial center Cp of the salient pole portion 48 from the axial center Cs of the stator core 24 satisfy the above formula (4). Therefore, the ratio of magnet torque to reluctance torque can be increased in the electric motor 20. This reduces the effect of iron loss in the rotor 23 due to reluctance torque, and suppresses a decrease in the motor performance of the electric motor 20.

[0089] Furthermore, the amount of misalignment L3 of the axial center Cr of the rotor core 42 relative to the axial center Cs of the stator core 24 and the gap G between the first overhang portion 43f of the magnet 43 and the end plate portion 44c of the first magnet holder 44A satisfy the above formula (5). Therefore, the amount of axial misalignment between the stator core 24 and the rotor core 42 can be made as small as possible, which also suppresses a decrease in reluctance torque. In addition, because a decrease in magnet torque can also be suppressed, a decrease in the motor performance of the electric motor 20 can also be suppressed.

[0090] The rotor 23 includes two magnet holders 44A and 44B and a magnet cover 45. The magnet cover 45 can reliably protect the rotor core 42, the magnet 43, and the magnet holders 44A and 44B. The magnet holders 44A and 44B make it easy to position the magnet 43 relative to the rotor core 42.

[0091] Positioning protrusions 41 are integrally formed on the leg portions 44h of each of the magnet holders 44A, 44B. These positioning protrusions 41 press against the inner surfaces 43d of the magnets 43 from both sides in the circumferential direction, thereby ensuring reliable positioning of the magnets 43 relative to the rotor core 42 in the circumferential direction.

[0092] Furthermore, when the magnet cover 45 is attached from the first magnet holder 44A side, the second overhang portion 43g is pushed outward in the radial direction by the positioning protrusions 41 of the second magnet holder 44B. As a result, when the four magnets 43 are viewed as a whole, the magnets 43 are in a state where they are flared toward the second magnet holder 44B side. This allows the magnets 43 themselves to act as guides, making it easier to press the magnet cover 45 into the rotor core 42. Furthermore, it is possible to prevent galling from occurring between the inner circumferential surface of the cylindrical portion 45a of the magnet cover 45 and the outer circumferential surface 43b of the magnet 43 (particularly near the first overhang portion 43f). This improves the ease of assembly of the rotor 23, and ultimately the ease of assembly of the electric motor 20.

[0093] This makes it possible to stabilize the behavior of the rotor 23 while reliably suppressing the deterioration of the motor performance of the electric motor 20, thereby contributing to Goal 7 of the United Nations-led Sustainable Development Goals (SDGs), "Ensure access to affordable, reliable, sustainable and modern energy for all," and Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0094] The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention. For example, the reduction geared motor 1 has been described as being used as a drive source for electrical equipment (such as wipers, power windows, sunroofs, and power seats) mounted on a vehicle. However, this is not limiting, and the reduction geared motor 1 can be used in a variety of electrical devices. Also, the electric motor 20 alone can be used in a variety of electrical devices. The configuration of the above-described embodiment can also be used for a generator instead of the electric motor 20.

[0095] In the above-described embodiment, the case where the axial thickness of the rotor core body 47 and the axial thickness of the salient pole portion 48 are the same has been described. The case where the axial center Cr of the rotor core 42 and the axial center Cp of the salient pole portion 48 are at the same position has been described. However, this is not limited thereto, and the axial thickness of the rotor core body 47 and the axial thickness of the salient pole portion 48 do not have to be the same. In this case, the axial center Cr of the rotor core 42 and the axial center Cp of the salient pole portion 48 may be misaligned. The above-described offset amount A1 of the axial center Cp of the salient pole portion 48 from the axial center Cm of the magnet 43 and the offset amount A2 of the axial center Cp of the salient pole portion 48 from the axial center Cs of the stator core 24 only refer to the salient pole portion 48, and are not synonymous with the axial center Cr of the rotor core 42 and the axial center Cp of the salient pole portion 48.

[0096] In the above embodiment, the rotor 23 includes four magnets 43, and the number of magnetic poles is four. However, the number of magnetic poles of the rotor 23 is not limited to this, and it is sufficient that the number of magnetic poles of the rotor 23 is two or more. The rotor core 42 does not necessarily have to include the salient pole portion 48. In this case, the magnet 43 may be formed in a cylindrical shape so as to cover the outer peripheral surface 47b of the rotor core body 47. [Explanation of symbols]

[0097] 1...motor with reducer (rotating electric machine), 4...controller, 7...back yoke portion, 9...terminal holder, 9a...terminal, 10...housing, 11...housing body, 12...cover, 12c...connector receiving portion, 13...reduction gear receiving portion, 13a...opening, 13b...bottom, 13w...peripheral wall portion, 14...shaft receiving groove, 15...wheel receiving recess, 16A...first bearing, 16B...second bearing, 17...motor receiving portion, 17a...shaft insertion hole, 19...boss portion, 20...electric motor, 21...motor cover Bar, 21a... flange, 21b... bolt, 22... stator, 23... rotor, 24... stator core, 24a... end face, 24p... steel plate, 25... teeth, 26... coil, 26a... crossover portion, 27... rotor shaft, 27a... end (tip), 28... rotor body, 29... insulator, 29a... inner wall portion, 29b... outer wall portion, 29c... coil storage portion, 30... reducer, 31... worm shaft, 31g... worm gear portion, 32... worm wheel, 32g... outer gear portion, 33... Output shaft, 33a...spline, 41...positioning protrusion (protrusion), 41a...tapered portion, 42...rotor core, 42a...first end face, 42b...second end face, 42p...steel plate, 43...magnet, 43a...inner peripheral surface, 43b...outer peripheral surface, 43c...side surface, 43d...inner surface, 43e...outer surface, 43f...first overhang portion, 43g...second overhang portion, 44A...first magnet holder, 44B...second magnet holder, 44c...end plate portion, 44d...core arrangement portion, 44e...opening portion, 44f...outer peripheral edge, 44g...annular portion, 44h...leg portion, 44i...inner surface, 44j...side surface, 44k...reinforcing rib, 45...magnet cover, 45a...cylindrical portion, 45b...first flange portion, 45c...second flange portion, 47...rotor core main body (core main body portion), 47a...through hole, 47b...outer peripheral surface, 48...salient pole portion, 48a...side surface, 48b...outer end portion, 48c...groove portion, 51...mounting table, 52...pressure machine, 53...gripping portion, 61...magnetic detection element, 62...controller board, A...rotation axis

Claims

1. a stator; a rotor rotatably provided relative to the stator; Equipped with The stator includes: A stator core; a coil wound around the stator core; and The rotor is a rotor shaft that is cantilevered by the bearing and rotates around a rotation axis; a rotor core fixed to the rotor shaft near the tip end on the opposite side from the bearing; a magnet provided on the circumferential surface of the rotor core; and The center of the stator core in the direction of the rotation axis is located closer to the bearing than the center of the magnet in the direction of the rotation axis. A rotating electric machine characterized by:

2. The stator core is A cylindrical back yoke part, a plurality of teeth that protrude radially from a peripheral surface of the back yoke portion and around which the coil is wound; and a crossover portion of the coil routed between predetermined teeth is disposed on one of both end faces of the stator core in the rotation axis direction, Both end surfaces of the magnet in the direction of the rotation axis protrude beyond both end surfaces of the stator core in the direction of the rotation axis, a protruding length of the magnet from the one end face of the stator core is shorter than a protruding length of the magnet from the other end face of the stator core in the rotation axis direction; 2. The rotating electrical machine according to claim 1.

3. The center of the stator core in the direction of the rotational axis is located between the center of the magnet in the direction of the rotational axis and the center of the rotor core in the direction of the rotational axis.

3. The rotating electric machine according to claim 1 or 2.

4. The rotor core is a core body portion formed in a cylindrical shape; a plurality of salient poles formed so as to protrude radially outward from the outer circumferential surface of the core body; and The plurality of salient poles extend along the rotation axis direction and are arranged at predetermined intervals in the circumferential direction, The magnets are disposed between two adjacent salient poles in the circumferential direction, a deviation amount of the center of each salient pole in the rotational axis direction from a center of each magnet in the rotational axis direction is larger than a deviation amount of the center of each salient pole in the rotational axis direction from a center of each stator core in the rotational axis direction; 4. The rotating electrical machine according to claim 3.

5. The rotor core is a core body portion formed in a cylindrical shape; a plurality of salient poles formed so as to protrude radially outward from the outer circumferential surface of the core body; and The plurality of salient poles extend along the rotation axis direction and are arranged at predetermined intervals in the circumferential direction, The magnets are disposed between two adjacent salient poles in the circumferential direction, two holders provided on both end surfaces of the rotor core in the rotation axis direction, restricting movement of the magnet in the rotation axis direction and restricting movement in a circumferential direction; Each of the holders is an annular portion disposed on each of the end surfaces of the core body and on a radially inner side surface of the magnet; a plurality of leg portions that protrude radially outward from an outer circumferential surface of the annular portion and are disposed between two of the magnets that are adjacent to each other in the circumferential direction; an end plate portion integrally connected to the annular portion and the leg portion on the opposite side from the rotor core; and The length between the end plate portions of the two holders is L1, The length of the magnet in the direction of the rotation axis is L2, When the amount of deviation of the center of the salient pole in the rotational axis direction from the center of the stator core in the rotational axis direction is L3, The length L1, the length L2, and the deviation amount L3 are L1-L2>L3 fulfill, 3. The rotating electric machine according to claim 1 or 2.

6. a magnet cover attached to the rotor core from one side in the rotation axis direction and covering the rotor core, the magnet, and the holder; Each of the holders has a protrusion formed on each of the leg portions on both circumferential sides thereof, the protrusion abutting against each of the magnets on both circumferential sides thereof.

6. The rotating electrical machine according to claim 5.

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