Electric Motor

Abstract

The present invention provides an electric motor capable of high-speed rotation. The electric motor (10) comprises: a shaft (2); at least two bearings, namely a bearing (4a) and a bearing (4b), which are used to support the shaft (2); a magnet (3) which is supported by the shaft (2) between the two bearings (4a) and the bearing (4b); a stator (5) which surrounds the magnet (3); and a magnetic component (6a) and a magnetic component (6b) which are arranged between the magnet (3) and the bearings (4a) and the bearings (4b) in the length direction of the shaft (2), and the magnetic component (6a) and the magnetic component (6b) have an outer diameter larger than the outer diameter of the magnet (3).

Description

Technical Field

[0001] The present invention relates to an electric motor. Background Art

[0002] An electric motor as described below is known, which includes: a stator having a coil wound on a stator core; a rotor having a rotating shaft fixed to the rotor core and permanent magnets embedded in the peripheral portion of the rotor core; and a pair of balance rings inserted on the rotating shaft and fixed to both sides of the rotor core (see patent document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: JP2012-39732A Summary of the invention

[0006] Problems to be solved by the invention

[0007] Depending on the purpose of the motor, it is desirable to rotate the rotor at a high speed of, for example, 50,000 revolutions per minute. When rotating the motor at high speed, for example, it is desirable to reduce the outer diameter of the magnet mounted on the rotor to reduce the centrifugal force generated when the rotor rotates.

[0008] However, in conventional electric motors including the electric motor disclosed in Patent Document 1, it is difficult to achieve high-speed rotation for the following reasons.

[0009] First, in conventional motors, since the bearing material contains magnetic metals such as iron, a part of the magnetic flux generated by the magnet of the rotating rotor sometimes flows toward the outer ring of the bearing as leakage flux. In conventional motors, eddy currents are sometimes generated in the bearings due to the leakage flux toward the outer ring of the bearing. In conventional motors, the eddy currents sometimes apply brakes to the bearings, which act as impedance to the rotational force of the rotor.

[0010] Furthermore, in order to make the motor rotate at high speed, it is necessary to ensure the balance of the rotor with high precision. Generally speaking, the work of balancing the rotor is performed by reducing the weight of the balancing component by cutting after the balancing component is mounted on the shaft. However, in conventional motors, it is not easy to reduce the weight of the balancing component mounted on the rotor because the cutting tool needs to be carefully operated when the distance between the magnet and the balancing component along the axial direction is close.

[0011] The present invention takes the above-mentioned problem as an example, and an object of the present invention is to provide a motor capable of high-speed rotation.

[0012] In order to achieve the above-mentioned purpose, the electric motor involved in the present invention includes: a shaft; at least two bearings, which are used to support the shaft; a magnet, which is supported by the shaft between at least two bearings; a stator, which surrounds the magnet; and a magnetic component, which is arranged between the magnet and at least one bearing in the length direction of the shaft, and the magnetic component has an outer diameter larger than the outer diameter of the magnet.

[0013] In the electric motor according to one aspect of the present invention, the magnetic member has an outer diameter smaller than an outer diameter of the bearing.

[0014] In the electric motor according to one aspect of the present invention, in the longitudinal direction of the shaft, the distance between the bearing and the magnetic member is shorter than the distance between the magnetic member and the magnet.

[0015] In the electric motor according to one aspect of the present invention, the magnetic member is spaced a predetermined distance from the bearing and the magnet in the longitudinal direction of the shaft.

[0016] An electric motor according to one aspect of the present invention includes a rotor including a shaft and a magnet, wherein the magnetic member is a balancing member of the rotor.

[0017] In the electric motor according to one aspect of the present invention, the magnetic member has a surface portion facing the bearing in the longitudinal direction of the shaft, and the surface portion facing the bearing is provided with a recessed portion, a hole portion, or a protruding portion.

[0018] In the electric motor according to one aspect of the present invention, in the longitudinal direction of the shaft, the distance between the magnet and the magnetic member is longer than the distance of the air gap.

[0019] In an electric motor according to one aspect of the present invention, a plurality of bearings are provided, the plurality of bearings include two bearings, and the magnetic members are provided in the plurality of bearings, respectively.

[0020] According to the electric motor of the present invention, high-speed rotation can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a perspective view schematically showing the structure of the electric motor according to the embodiment of the present invention.

[0022] Figure 2 for Figure 1 A cross-sectional view along the axis of the motor shown.

[0023] Figure 3 To schematically illustrate Figure 1 A top view of the structure of the balancing component of the electric motor shown.

[0024] Figure 4 To schematically illustrate Figure 1A cross-sectional view showing the structure of a balancing component of an electric motor.

[0025] Figure 5 To schematically illustrate Figure 1 A cross-sectional view of a modified example of a balancing member for an electric motor shown in FIG.

[0026] Figure 6 for Figure 1 The cross-sectional view of the motor along the axis line shown is a diagram for explaining the dimensions and arrangement of the shaft, the bearing, and the balancing member.

[0027] Figure 7 To show Figure 1 A table showing the relationship between the mechanical load and the ratio of the distance from the magnet to the bearing to the air gap in the motor shown.

[0028] Figure 8 To show Figure 1 FIG. 4 is a graph showing the relationship between the mechanical load and the ratio of the distance from the magnet to the bearing to the air gap in the motor shown.

[0029] Fig. 9 To show Figure 1 The ratio of the distance from the magnet to the balance member to the air gap, the mechanical load, and Figure 1 A table showing the relationship between the torque of the motor and the ratio of the torque of the motor without a balancing component.

[0030] Fig.10 To show Figure 1 FIG. 1 is a graph showing the relationship between the ratio of the distance from the magnet to the balance member to the air gap, the mechanical load, and the ratio of the torque of the motor to the torque of the motor not including the balance member in the motor shown. DETAILED DESCRIPTION

[0031] Hereinafter, a motor according to an embodiment of the present invention will be described with reference to the drawings.

[0032] The overall structure of the motor

[0033] The overall structure of a motor according to an embodiment of the present invention will be described.

[0034] Figure 1 It is a perspective view schematically showing the structure of the electric motor 10 according to the embodiment of the present invention. Figure 2 is a cross-sectional view of the motor 10 along the axis x.

[0035] For the sake of convenience, the following Figure 1 The direction perpendicular to the axis x direction (hereinafter also referred to as "radial direction") is set as the front side of the motor 10. Figure 2 In the direction of the axis x shown in the figure, the direction of arrow a is set as the upper side a, and the direction of arrow b is set as the lower side b. In addition, in the radial direction, the direction away from the axis x ( Figure 2 The direction of the arrow c) is set as the outer peripheral side c, and the direction toward the axis x ( Figure 2 The direction of the arrow d) is set to the inner side d.

[0036] The motor 10 includes: a shaft 2; at least two bearings supporting the shaft 2, namely, a bearing 4a and a bearing 4b; a magnet 3 supported by the shaft 2 and rotating together with the shaft 2; and a stator 5 surrounding the magnet 3. In addition, the motor 10 includes a balance member 6a and a balance member 6b as a magnetic member, which are arranged between the magnet 3 and at least one of the bearing 4a and the bearing 4b in the longitudinal direction of the shaft 2, rotate together with the shaft 2, and have an outer diameter larger than the outer diameter of the magnet 3. The structure of the motor 10 will be described in detail below.

[0037] The housing 1 defines the general shape of the motor 10 and accommodates the components of the motor 10. The housing 1 includes a housing body 11 formed in a hollow cylindrical shape with upper and lower cover portions opened; an upper cover portion 12 mounted on a cover portion on the upper side (one end side) a of the housing body 11; and a lower cover portion 13 mounted on a cover portion on the lower side (the other end side) b of the housing body 11.

[0038] The upper cover 12 has a substantially disc shape corresponding to the shape of the cover surface of the housing body 11 in order to seal the housing body 11 from the upper side a. In addition, the upper cover 12 has a bearing holding hole 12a as a hole for holding the bearing 4a through which the shaft 2 passes. The lower cover 13 has a substantially disc shape corresponding to the shape of the cover surface of the housing body 11 in order to seal the housing body 11 from the lower side b. In addition, the lower cover 13 has a bearing holding hole 13a as a hole for holding the bearing 4b through which the shaft 2 passes.

[0039] The shaft 2 is a member such as a round rod whose extension direction (length direction), that is, the axis x direction, is the length direction. The shaft 2 rotates around the axis x direction. The shaft 2 is supported in the bearing retaining holes 12a and 13a of the housing 1 via bearings 4a and 4b. The front end portion (one end) of the shaft 2 is exposed to the outside of the housing 1 from the bearing retaining holes 12a and 13a of the housing 1. The portion (the other end) of the front end portion of the shaft 2 exposed from the direction of the lower side b becomes the output shaft, which transmits the rotational force generated by the motor 10 to the outside.

[0040] The schematic shape of the magnet 3 is, for example, a cylindrical shape. The magnet 3 has an axis x direction as a length direction, and is provided with a through hole that penetrates the center of the magnet 3, that is, a shaft through hole 31. The magnet 3 is supported by the shaft 2 at a position between the bearing 4a and the bearing 4b in the interior of the housing 1. The magnet 3 supported by the shaft 2 rotates together with the shaft 2. The shaft 2 and the magnet 3 constitute the rotor 7 in the motor 10.

[0041] The bearing 4a is mounted on the upper cover 12 of the upper side a of the housing 1. The bearing 4b is mounted on the lower cover 13 of the lower side b of the housing 1. The bearings 4a and 4b are, for example, ball bearings. In the present invention, there is no particular limitation on the type of bearing. The bearings 4a and 4b are, for example, respectively composed of inner rings 41a and 41b and outer rings 42a and 42b arranged in a manner such that the axis x direction becomes the central axis, and rolling elements 43a and 43b provided between the inner rings 41a and 41b and the outer rings 42a and 42b. The bearings 4a and 4b support the shaft 2 using the inner circumferential surfaces 44a and 44b of the inner rings 41a and 41b.

[0042] The bearings 4a and 4b rotatably support the shaft 2 at any position in the axis x direction of the shaft 2. Specifically, the bearing 4a rotatably supports the upper side a portion of the shaft 2 in the axis x direction by inserting the shaft 2 into the inner circumferential surface 44a. The bearing 4b rotatably supports the lower side b portion of the shaft 2 in the axis x direction by inserting the shaft 2 into the inner circumferential surface 44b. In the bearings 4a and 4b, the inner rings 41a and 41b, the outer rings 42a and 42b, and the rolling elements 43a and 43b are all made of a metal having magnetism, and are generally formed of an alloy containing iron. The outer diameters of the outer rings 42a and 42b of the bearings 4a and 4b are larger than the outer diameter of the magnet 3 in the radial direction. That is, in the bearings 4a and 4b, the outer rings 42a and 42b are arranged at a position outside the outer periphery of the magnet 3 in the radial direction.

[0043] The stator 5 is held on the inner circumference of the housing body 11. Specifically, the stator 5 is arranged inside the housing body 11 at a position corresponding to the magnet 3 in the axis x direction (the length direction of the shaft 2), and is arranged at a position farther from the shaft 2 than the magnet 3 in the radial direction. The stator 5 is composed of a stator core, a coil, and an insulator. The stator core is formed into an annular shape so as to surround the magnet 3, the coil is wound on an extension portion extending from the stator core to the inner circumference d, and the insulator insulates the stator core from the coil. The stator 5 is arranged in a manner such that the annular inner circumference of the stator core surrounds the magnet 3. A gap AG is provided between the inner circumference of the stator core and the outer circumference of the magnet 3.

[0044] The shapes of the shaft 2 , the magnet 3 , the bearings 4 a and 4 b , and the stator 5 may be any shapes that can realize the rotational motion of the rotor 7 in the electric motor 10 , and are not limited to the above examples.

[0045] The balancing member 6a is arranged between the magnet 3 and the bearing 4a in the axis x direction of the shaft 2. The balancing member 6b is arranged between the magnet 3 and the bearing 4b in the axis x direction of the shaft 2. The balancing members 6a and 6b have through holes 61a and 61b which penetrate in the center with the axis x direction as the length direction. The balancing members 6a and 6b are provided, for example, corresponding to the number of the bearings 4a and 4b. The balancing members 6a and 6b rotate with the rotor 7, that is, the shaft 2 and the magnet 3, with the axis x direction as the center. The balancing members 6a and 6b function as a balancer to prevent the eccentric motion of the rotor 7 when it rotates with the axis x direction as the center.

[0046] The balance members 6a and 6b are formed of a magnetic member having a relatively high specific gravity, such as a Fe-Cu based sintered member, etc. That is, the balance members 6a and 6b function as a path for a magnetic flux to pass through.

[0047] Figure 3 FIG. 1 is a top view schematically showing the structure of the balancing components 6a and 6b of the motor 10. Figure 4 1 is a cross-sectional view schematically showing the structure of the balancing components 6a and 6b of the motor 10. Figure 3 as well as Figure 4 As shown, the balancing members 6a and 6b are provided with the through holes 61a and 61b and holes 63a and 63b extending in the direction of the axis x on the surface 62a and 62b. The holes 63a and 63b function as mass adjustment parts for eliminating eccentricity when the balancing members 6a and 6b rotate together with the rotor 7.

[0048] The holes 63a and 63b are formed by cutting the face parts 62a and 62b of the balancing members 6a and 6b from either the upper side a or the lower side b toward the other side using a cutting tool such as a drill. The face parts 62a and 62b form faces that are opposite to the bearings 4a and 4b in the axial line x direction of the shaft 2. After the balancing members 6a and 6b are mounted on the shaft 2 together with the magnet 3, the holes 63a and 63b can be set at predetermined positions in the face parts 62a and 62b. The formation positions of the holes 63a and 63b in the face parts 62a and 62b are determined as follows, that is, for the purpose of eliminating the eccentric motion of the rotor 7 during rotation, and taking into account the balance of the center of gravity in the radial direction of the rotor 7.

[0049] In addition, in the above description, as an example of the mass adjustment part in the present invention, the hole portions 63a and 63b that pass through the axis x direction of the balance components 6a and 6b are shown, but in the present invention, the shape of the mass adjustment part and the position of the mass adjustment part in the surface parts 62a and 62b are not limited to the above examples. Figure 5 FIG. 2 is a cross-sectional view schematically showing a modified example of the balancing components 6a and 6b of the motor 20. Figure 5 As shown, the above-mentioned quality adjustment unit is not Figure 3 as well as Figure 4 The through holes such as the holes 63a and 63b shown in the figure may be, for example, recessed portions 64a and 64b formed on the surfaces of the balancing members 6a and 6b facing the upper side a or the lower side b (see FIG. Figure 5 (a)) or convex portions 65a, 65b (see Figure 5 (b)). In addition, regarding the mass adjustment portion, the shape of the hole is not limited to the above example.

[0050] [Dimensions and configuration of magnets, bearings, and balancing components]

[0051] Next, refer to Figure 6 , the dimensions and arrangement of the magnet 3, the bearings 4a, 4b, and the balance members 6a, 6b in the motor 10 are described. Figure 6 for Figure 1 The cross-sectional view of the electric motor 10 taken along the axis x direction is a schematic diagram for explaining the sizes and arrangements of the magnet 3, the bearings 4a, 4b, and the balancing members 6a, 6b.

[0052] like Figure 6 As shown, the balance member 6a is arranged between the magnet 3 and the bearing 4a in the axis x direction of the shaft 2. In addition, the balance member 6b is arranged between the magnet 3 and the bearing 4b in the axis x direction of the shaft 2.

[0053] The outer diameter DB1 of the balance member 6a is larger than the outer diameter DM of the magnet 3 and smaller than the outer diameter DR1 of the outer ring 42a of the bearing 4a. The relationship among the outer diameter DB1 of the balance member 6a, the outer diameter DM of the magnet 3 and the outer diameter DR1 of the outer ring 42a of the bearing 4a is expressed by the following formula (1).

[0054] DM<DB1<DR1 (1)

[0055] The outer diameter DB2 of the balance member 6b is larger than the outer diameter DM of the magnet 3 and smaller than the outer diameter DR2 of the outer ring 42b of the bearing 4b. The relationship among the outer diameter DB2 of the balance member 6b, the outer diameter DM of the magnet 3 and the outer diameter DR2 of the outer ring 42b of the bearing 4b is expressed by the following formula (2).

[0056] DM<DB2<DR2 (2)

[0057] It should be noted that as long as the relationship between the above-mentioned formulas (1) and (2) is maintained, the dimensions of the outer diameter DB1 and the outer diameter DB2 can be the same value or different values. Similarly, as long as the relationship between the above-mentioned formulas (1) and (2) is maintained, the dimensions of the outer diameter DR1 and the outer diameter DR2 can be the same value or different values.

[0058] Since the balance members 6a and 6b, which are made of a magnetic body and rotate together with the shaft 2, reduce the magnetic flux from the magnet 3 entering the bearings 4a and 4b, the change in the magnetic flux density from the magnet 3 passing through the bearings 4a and 4b can be reduced, and the generation of eddy currents in the outer rings 42a and 42b of the bearings 4a and 4b can be prevented. In particular, by making the outer diameters DB1 and DB2 of the balance members 6a and 6b have the relationship of the above-mentioned equations (1) and (2), it is possible to prevent the magnetic flux from the magnet 3 toward the magnetic member other than the stator 5, that is, the leakage magnetic flux, from the magnet 3 toward the bearings 4a and 4b. That is, the balance members 6a and 6b can prevent the magnetic force generated by the eddy current generated in the outer rings 42a and 42b of the bearings 4a and 4b from applying a braking force to the shaft 2 through the magnet 3.

[0059] In addition, the eddy current generated in the bearings 4a and 4b decreases as the distance from the magnet 3 to the bearings 4a and 4b increases. However, since the distance from the fulcrum (bearings 4a and 4b) to the center of the rotational motion (magnet 3) increases, the vibration of the rotor 7 increases due to the centrifugal force generated by the rotational motion. Therefore, in the motor 10, in order to achieve high-speed rotation of the motor, it is effective to reduce the leakage flux entering the bearings 4a and 4b by the balance components 6a and 6b formed by the magnetic components described above, and prevent the vibration of the motor 10 caused by the centrifugal force.

[0060] The balancing member 6a is spaced a predetermined distance A1 from the bearing 4a in the direction of the axis x of the shaft 2. Furthermore, the balancing member 6a is spaced a predetermined distance B1 from the magnet 3 in the direction of the axis x of the shaft 2. The balancing member 6b is spaced a predetermined distance A2 from the bearing 4b in the direction of the axis x of the shaft 2. Furthermore, the balancing member 6b is spaced a predetermined distance B2 from the magnet 3 in the direction of the axis x of the shaft 2.

[0061] Here, the distance A1 between the balance member 6a and the bearing 4a is shorter than the distance B1 between the balance member 6a and the magnet 3 in the axial x direction of the shaft 2. The relationship between the distance A1 between the balance member 6a and the bearing 4a and the distance B1 between the balance member 6a and the magnet 3 is expressed by the following formula (3).

[0062] A1<B1 (3)

[0063] In addition, the distance A2 between the balance member 6b and the bearing 4b is shorter than the distance B2 between the balance member 6b and the magnet 3 in the axial x direction of the shaft 2. The relationship between the distance A2 between the balance member 6b and the bearing 4b and the distance B2 between the balance member 6b and the magnet 3 is expressed by the following formula (4).

[0064] A2<B2 (4)

[0065] In addition, the distance A1 and the distance A2 may be the same distance or different distances. Similarly, the distance B1 and the distance B2 may be the same distance or different distances.

[0066] As described above, by arranging the balance members 6a, 6b made of a magnetic body near the bearings 4a, 4b relative to the magnet 3, it is possible to prevent the generation of leakage magnetic flux from the magnet 3 toward the bearings 4a, 4b. In other words, by arranging the balance members 6a, 6b near the bearings 4a, 4b relative to the magnet 3, it is possible to further prevent the bearings 4a, 4b from being braked.

[0067] In the motor 10, the distances B1 and B2 between the magnet 3 and the balancing members 6a and 6b are preferably longer than the gap AG. By making the distances B1 and B2 longer than the gap AG as described above, the motor 10 can make the magnetic path a path from the magnet 3 toward the stator 5, thereby reducing the leakage flux and improving the magnetic efficiency. In addition, by making the distances B1 and B2 longer than the gap AG, the leakage flux can be reduced, so the motor 10 can prevent the bearings 4a and 4b from being braked by eddy currents.

[0068] Furthermore, in the motor 10, if Figure 3 As shown, holes 63a and 63b as mass adjustment parts for canceling the eccentric motion of the rotor 7 by adjusting the masses of the balancing members 6a and 6b are provided in the surface parts 62a and 62b facing away from each other in the axis x direction of the balancing members 6a and 6b.

[0069] When the surface parts 62a and 62b are cut from the axis x direction to adjust the mass of the balancing parts 6a and 6b, if the balancing parts 6a and 6b are in contact with other parts without a gap in the axis x direction, other parts may be cut by mistake. In this case, the diameter and feed rate of the cutting tool need to be precisely controlled so that the cutting tool does not penetrate the balancing parts 6a and 6b.

[0070] In addition, when it is difficult to cut the face portions 62a and 62b of the balancing members 6a and 6b, it is also possible to cut the side portions of the balancing members 6a and 6b, but it is difficult to cut the side portions of the balancing members 6a and 6b, which are thin flat members. In addition, in this case, there is a possibility that cutting chips and the like will fly out from the side portions, causing the torque when the shaft 2 rotates to increase, and the load when the rotor 7 rotates to increase.

[0071] In the motor 10, the balancing members 6a and 6b are respectively spaced apart from the magnet 3 by predetermined distances B1 and B2 in the axial line x direction of the shaft 2, and spaced apart from the bearings 4a and 4b by predetermined distances A1 and A2. Therefore, according to the motor 10, it is possible to easily operate the cutting tool in the cutting process for adjusting the mass of the balancing members 6a and 6b when performing the balancing adjustment. That is, according to the motor 10, it is possible to easily perform the cutting process for adjusting the mass of the balancing members 6a and 6b when performing the balancing adjustment.

[0072] [Study on the ratio of the distance from the magnet to the balance member to the air gap]

[0073] Reference Figures 7 to 10 The ratios RB1 and RB2 of the distances B1 and B2 from the magnet 3 to the balancing members 6 a and 6 b in the motor 10 to the air gap AG were examined.

[0074] First, in the motor 10, in order to determine the ratios RB1 and RB2 of the distances B1 and B2 to the gap AG, the ratios RB0a and RB0b of the distances from the magnet 3 to the bearings 4a and 4b to the gap AG are changed. Furthermore, in the motor 10, the change in the mechanical load ML caused by changing RB0a and RB0b is studied. The mechanical load refers to the load inside the motor generated when the motor is rotated in a non-energized state. The mechanical load mainly includes friction load and magnetic load. The friction load is generated by the friction generated between the rolling elements and the retainer of the bearing when the motor rotates, or the friction generated by the grease inside the motor. The magnetic load is generated by the attraction (cogging effect) between the magnet and the stator when the motor rotates.

[0075] Figure 7 The table shows the relationship between the mechanical load ML and the distances (A1+B1+C1) and (A2+B2+C2) from the magnet 3 to the bearings 4a and 4b in the motor 10, and the ratios RB0a (A1+B1+C1 / AG) and RB0b (A2+B2+C2 / AG) of the gap AG. Figure 8 It is a graph showing the relationship between the mechanical load ML in the motor 10 and the ratios RB0a (A1+B1+C1) and RB0b (A2+B2+C2) of the distances (A1+B1+C1) and (A2+B2+C2) from the magnet 3 to the bearings 4a and 4b with respect to the gap AG.

[0076] exist Figure 7 as well as Figure 8 In FIG. 1 , the ratios RB0a and RB0b of the distance from the magnet 3 to the bearings 4a and 4b to the gap AG represent the ratios of the distances from the magnet 3 to the bearings 4a and 4b when the gap AG is set to 1. Figure 7 as well as Figure 8As shown in FIG. 1 , the ratios RB0a and RB0b of the distance from the magnet 3 to the bearings 4a and 4b to the gap AG were changed to 1.5, 2.2, 2.8, and 3.5, and the mechanical load ML in these cases was measured.

[0077] according to Figure 7 and Figure 8 It is found that in the motor 10, when the ratios RB0a and RB0b of the distance from the magnet 3 to the bearings 4a and 4b to the gap AG are between 2.2 and 2.8, the degree of reduction in the mechanical load ML is greater than that before and after.

[0078] Next, the ratios RB1 and RB2 of the distances B1 and B2 to the gap AG in the motor 10 are studied. In the following description, the motor not including the balancing components 6a and 6b is referred to as the motor of the reference example. The ratios RB1 and RB2 of the distances B1 and B2 to the gap AG are studied based on the mechanical load ML of the motor 10, the mechanical load ML2 of the motor not including the balancing components 6a and 6b, and the ratio TR of the torque of the motor 10 to the torque of the motor not including the balancing components 6a and 6b.

[0079] Fig. 9 The table shows the relationship between the ratio RB1 (B1 / AG), RB2 (B2 / AG) of the distances B1 and B2 from the magnet 3 to the balancing members 6a and 6b in the motor 10 to the gap AG, the mechanical load ML, the mechanical load ML2, and the ratio TR of the torque of the motor 10 to the torque of the motor of the reference example. Fig.10 The graph shows the relationship between the ratio RB1 (B1 / AG), RB2 (B2 / AG) of the distance B1 and B2 from the magnet 3 to the balancing components 6a and 6b in the motor 10 to the gap AG, the mechanical load ML, the mechanical load ML2, and the torque of the motor 10 and the ratio TR of the motor of the reference example. In the motor of the reference example, since the balancing components 6a and 6b are not included, the change in the mechanical load ML2 corresponds to the change in the distance from the magnet to the bearing. Fig. 9 In the column of the distance, "-" indicates the ratio TR of the mechanical load ML2 in the motor of the reference example without the balancing components 6a and 6b and the torque of the motor 10 to the torque of the motor of the reference example. In the present embodiment, the ratios RB1 and RB2 of the distance B2 to the gap AG are measured in the state where the magnet 3 is in contact with the balancing components 6a and 6b ( Fig. 9 The mechanical load ML is between "0" in the figure and 3.5.

[0080] according to Fig. 9 as well as Fig.10It can be seen that, in particular, when the ratio RB1 and RB2 of the distance B2 from the magnet 3 to the balancing members 6a and 6b is between 1.5 and 2.8, the mechanical load ML of the motor 10 is significantly reduced compared to the mechanical load ML2 of the motor of the reference example. That is, it can be seen that in this embodiment, when the ratio RB1 and RB2 of the distance from the magnet 3 to the balancing members 6a and 6b to the gap AG is between 1.5 and 2.8, the efficiency of the motor 10 is improved compared to before and after.

[0081] In addition, according to Fig. 9 and Fig.10 It can be seen that the ratio TR of the torque of the motor 10 to the motor of the reference example is 1.0 or more in the region where the ratios RB1 and RB2 of the distance from the magnet 3 to the balancing members 6a and 6b to the gap AG are 1.5 or more. That is, it can be seen that the motor 10 generates a greater torque than the motor of the reference example in the region where the ratios RB1 and RB2 of the distance from the magnet 3 to the balancing members 6a and 6b to the gap AG are 1.5 or more.

[0082] according to Figures 7 to 10 It can be seen that when the ratios RB1 and RB2 of the distance from the magnet 3 to the balancing members 6a and 6b to the gap AG in the motor 10 are between 1.5 and 2.8, the mechanical load ML is reduced and a torque greater than that of the motor of the reference example is generated. Therefore, it can be said that it is ideal to set the ratios RB1 and RB2 of the distance from the magnet 3 to the balancing members 6a and 6b to the gap AG in the range of 1.5 to 2.8 in the motor 10.

[0083] As described above, according to the electric motor 10 , high-speed rotation can be achieved.

[0084] The embodiments of the present invention are described above, but the present invention is not limited to the motor 10 involved in the above embodiments of the present invention, but includes all the concepts of the present invention and the claims. In addition, the various components can be appropriately and selectively combined to exert at least part of the above-mentioned problems and effects. For example, the shape, material, configuration, size, etc. of each component in the above embodiments can be appropriately changed according to the specific use of the present invention.

[0085] Description of symbols

[0086] 1 housing; 2 shaft; 3 magnet; 4a bearing; 4b bearing; 5 stator; 6a balance member; 6b balance member; 7 rotor; 10 motor; 11 housing body; 12 upper cover; 13 lower cover; 31 shaft through hole; 41a inner ring; 41b inner ring; 42a outer ring; 42b outer ring; 43a rolling element; 43b rolling element; 44a inner circumferential surface; 44b inner circumferential surface; 61a through hole; 61b through hole; 62a face; 62b face; 63a hole; 63b hole; 64a recess; 64b recess; 65a convex portion; 65b convex portion.

Claims

1. An electric motor, comprising: axis; at least two bearings for supporting the shaft; A cylindrical magnet and two magnetic components supported by the shaft between the at least two bearings; a stator, which surrounds the cylindrical magnet, One of the two magnetic members is disposed between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft and is located closer to the one bearing. The other of the two magnetic members is arranged between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft and is located closer to the other bearing. The two bearings include rolling elements and outer rings formed of magnetic metal. The two magnetic components form a path for the magnetic flux generated by the cylindrical magnet to pass through. In the radial direction of the shaft, the size of the one magnetic component is smaller than the size of the outer ring of the one bearing, In the radial direction of the shaft, the size of the other magnetic component is smaller than the size of the outer ring of the other bearing, The magnetic member has an outer diameter larger than an outer diameter of the magnet.

2. An electric motor, comprising: axis; 2 bearings for supporting the shaft; A cylindrical magnet and two components supported by the shaft between the two bearings; a stator, which surrounds the cylindrical magnet, One of the two components is disposed between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft and is located closer to the one bearing. The other of the two components is arranged between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft and is located closer to the other bearing. The two bearings include rolling elements and outer rings formed of magnetic metal. The two components constitute a path for the magnetic flux generated by the cylindrical magnet to pass through. In the radial direction of the shaft, the size of the one component is smaller than the size of the outer ring of the one bearing, In the radial direction of the shaft, the size of the other component is smaller than the size of the outer ring of the other bearing.

3. An electric motor, comprising: axis; 2 bearings for supporting the shaft; A cylindrical magnet and two components supported by the shaft between the two bearings; a stator, which surrounds the cylindrical magnet, In the longitudinal direction of the shaft, the first portion of the shaft is located between the cylindrical magnet and one of the two bearings and is located closer to the one bearing, and one of the two components is supported by the first portion of the shaft. In the longitudinal direction of the shaft, the second portion of the shaft is located between the cylindrical magnet and the other of the two bearings and is located closer to the other bearing, and the other of the two components is supported by the second portion of the shaft. The two bearings include rolling elements and outer rings formed of magnetic metal. The two components constitute a path for the magnetic flux generated by the cylindrical magnet to pass through. In the radial direction of the shaft, the size of the one component is smaller than the size of the outer ring of the one bearing, In the radial direction of the shaft, the size of the other component is smaller than the size of the outer ring of the other bearing.

4. The electric motor according to claim 2 or 3, wherein: The one member is spaced a predetermined distance from the one bearing and the cylindrical magnet in the longitudinal direction of the shaft.

5. The electric motor according to claim 2 or 3, wherein: The one component is a magnetic body, The other component is a magnetic body.

6. An electric motor, comprising: axis; 2 bearings for supporting the shaft; A cylindrical magnet and two components supported by the shaft between the two bearings; a stator, which surrounds the cylindrical magnet, One of the two members is arranged between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft. The other of the two components is arranged between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft. The one component is arranged on the one bearing side relative to the stator, The other component is arranged on the other bearing side relative to the stator, The two bearings include rolling elements and outer rings formed of magnetic metal. The two components constitute a path for the magnetic flux generated by the cylindrical magnet to pass through. In the longitudinal direction of the shaft, the distance between the one bearing and the one component is smaller than the distance between the one component and the cylindrical magnet. In the longitudinal direction of the shaft, the distance between the other bearing and the other component is smaller than the distance between the other component and the cylindrical magnet. In the radial direction of the shaft, the size of the one component is smaller than the size of the outer ring of the one bearing, In the radial direction of the shaft, the size of the other component is smaller than the size of the outer ring of the other bearing.

7. The electric motor according to claim 6, wherein: The one member is spaced a predetermined distance from the one bearing and the cylindrical magnet in the longitudinal direction of the shaft.

8. The electric motor according to claim 6 or 7, wherein: comprising a rotor having the shaft and the cylindrical magnet, The one component or the other component is a balancing component of the rotor.

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