Electric motor

Abstract

The invention provides a motor capable of realizing high-speed rotation. An electric motor (10) is provided with: a shaft (2); at least two bearings (a bearing (4a) and a bearing (4b)) for supporting the shaft (2); a magnet (3) supported by the shaft (2) between the two bearings (4a, 4b); a stator (5) surrounding the magnet (3); and a magnetic member (6a) and a magnetic member (6b) disposed between the magnet (3) and the bearing (4a) and the bearing (4b) in the longitudinal direction of the shaft (2), the magnetic member (6a) and the magnetic member (6b) having an outer diameter larger than the outer diameter of the magnet (3).

Description

This application is a divisional application of the patent application with the application number 201910628116.2, the application date of July 12, 2019, and the invention title of "Motor". Technical Field

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

[0002] A motor is known as described below, which includes: a stator in which a coil is wound around a stator core; a rotor in which a rotating shaft is fixed to a rotor core, and permanent magnets are embedded in a peripheral portion of the rotor core; and a pair of balance rings which are inserted into the rotating shaft and fixed to both sides of the rotor core (see Patent Document 1). Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. JP2012-39732A Summary of the Invention Problems to be Solved by the Invention

[0004] For a motor, depending on its use, it is desired to rotate the rotor at a high speed of, for example, 50,000 revolutions per minute. When the motor is rotated at a high speed, for example, it is desired to reduce the outer diameter of the magnet mounted on the rotor, thereby reducing the centrifugal force generated when the rotor rotates.

[0005] However, in conventional motors including the motor disclosed in Patent Document 1, it is difficult to achieve high-speed rotation for the following reasons.

[0006] First, in a conventional motor, since the material of the bearing contains ferromagnetic metals such as iron, a part of the magnetic flux generated by the magnet of the rotating rotor sometimes flows as leakage flux in the direction of the outer ring of the bearing. In a conventional motor, eddy currents sometimes occur in the bearing due to this leakage flux in the direction of the outer ring of the bearing. In a conventional motor, sometimes a braking force is applied to the bearing due to these eddy currents, which becomes an impedance to the rotational force of the rotor.

[0007] Moreover, in order to rotate the motor at a high speed, it is necessary to ensure the balance of the rotor with high precision. Generally, the operation of achieving the balance of the rotor is performed by cutting the weight of the balance member after installing the balance member on the shaft by cutting or the like. However, in a conventional motor, since it is necessary to carefully operate the cutting tool when the distance between the magnet and the balance member in the axial direction is close, etc., the processing for reducing the mass of the balance member mounted on the rotor is not easy.

[0008] Taking the above problems as an example, an object of the present invention is to provide a motor capable of achieving high-speed rotation. Means for Solving the Problems

[0009] To achieve the above object, the motor according to the present invention includes: a shaft; at least two bearings for supporting the shaft; a magnet supported by the shaft between at least two bearings; a stator surrounding the magnet; and a magnetic member disposed between the magnet and at least one bearing in the longitudinal direction of the shaft, the magnetic member having an outer diameter larger than the outer diameter of the magnet.

[0010] In the motor according to one aspect of the present invention, the magnetic member has an outer diameter smaller than the outer diameter of the bearing.

[0011] In the 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.

[0012] In the motor according to one aspect of the present invention, the magnetic member is spaced apart from the bearing and the magnet by a predetermined distance in the longitudinal direction of the shaft.

[0013] In the motor according to one aspect of the present invention, it includes: a rotor including a shaft and a magnet, and the magnetic member is a balance member of the rotor.

[0014] In the motor according to one aspect of the present invention, in the longitudinal direction of the shaft, the magnetic member has a face opposed to the bearing, and a recess, a hole, or a protrusion is provided on the face opposed to the bearing.

[0015] In the 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.

[0016] In the motor according to one aspect of the present invention, it includes a plurality of bearings, the plurality of bearings including two bearings, and the magnetic member is provided in each of the plurality of bearings.

[0017] According to the motor of the present invention, high-speed rotation can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A perspective view schematically showing the configuration of a motor according to an embodiment of the present invention. Figure 2 For Figure 1 A cross-sectional view taken along the axis of the motor shown. Figure 3 For schematically showing Figure 1 A top view of the configuration of the balance member of the motor shown. Figure 4 For schematically showing Figure 1Cross-sectional view of the configuration of the balance component of the motor shown Figure 5 To schematically show Figure 1 Cross-sectional view of a modified example of the balance component of the motor shown Figure 6 For Figure 1 Cross-sectional view of the motor shown along the axis, a diagram for explaining the dimensions and configurations of the shaft, bearings, and balance components Figure 7 To show Figure 1 Table showing the relationship between the mechanical load in the motor shown and the ratio of the distance from the magnet to the bearing to the air gap Figure 8 To show Figure 1 Graph showing the relationship between the mechanical load in the motor shown and the ratio of the distance from the magnet to the bearing to the air gap Figure 9 To show Figure 1 In the motor shown, the ratio of the distance from the magnet to the balance component to the air gap, the mechanical load, and Figure 1 Table showing the relationship between the torque of the motor shown and the ratio of the torque of the motor without the balance component Figure 10 To show Figure 1 Graph showing the relationship between the ratio of the distance from the magnet to the balance component to the air gap, the mechanical load, and the ratio of the torque of the motor shown to the torque of the motor without the balance component in the motor shown Detailed implementation mode

[0019] Hereinafter, the motor according to the embodiment of the present invention will be described with reference to the drawings

[0020] Overall configuration of the motor The overall configuration of the motor according to an embodiment of the present invention will be described Figure 1 Stereogram schematically showing the configuration of the motor 10 according to the embodiment of the present invention Figure 2 Cross-sectional view of the motor 10 along the axis x

[0021] Hereinafter, for the sake of convenience of explanation Figure 1 The direction perpendicular to the axis x direction shown (hereinafter, also referred to as "radial direction") is set as the front of the motor 10. In addition, for the sake of convenience of explanation hereinafter Figure 2 On the axis x direction shown, the arrow a direction is set as the upper side a, and the arrow b direction is set as the lower side b. In addition, in the radial direction, the direction away from the axis x ( Figure 2 Arrow c direction) is set as the outer peripheral side c, and the direction toward the axis x ( Figure 2The direction of arrow d (direction of the inner peripheral side d).

[0022] The electric motor 10 includes: a shaft 2; at least two bearings that support 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 that surrounds the magnet 3. In addition, the electric motor 10 includes a balance member 6a and a balance member 6b as magnetic members, 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. Hereinafter, the configuration of the electric motor 10 will be specifically described.

[0023] The housing 1 determines the general shape of the electric motor 10 and houses the components of the electric motor 10 described above. The housing 1 includes: a housing main body 11, which is formed in a hollow cylindrical shape with upper and lower cover portions open; an upper cover portion 12, which is mounted on the cover portion on the upper side (one end side) a of the housing main body 11; and a lower cover portion 13, which is mounted on the cover portion on the lower side (the other end side) b of the housing main body 11.

[0024] The upper cover portion 12 has a substantially disc shape corresponding to the shape of the cover surface of the housing main body 11 in order to seal the housing main body 11 from the upper side a. In addition, the upper cover portion 12 has a bearing holding hole 12a as a hole for holding the bearing 4a through which the shaft 2 passes. The lower cover portion 13 has a substantially disc shape corresponding to the shape of the cover surface of the housing main body 11 in order to seal the housing main body 11 from the lower side b. In addition, the lower cover portion 13 has a bearing holding hole 13a as a hole for holding the bearing 4b through which the shaft 2 passes.

[0025] The shaft 2 is, for example, a round bar member having the extending direction (longitudinal direction), that is, the axis x direction, as the longitudinal direction. The shaft 2 rotates about the axis x direction. The shaft 2 is supported in the bearing holding holes 12a and 13a of the housing 1 via the bearings 4a and 4b. The front end portion (one end) of the shaft 2 protrudes from the bearing holding holes 12a and 13a of the housing 1 to the outside of the housing 1. The portion (the other end) of the front end portion of the shaft 2 that protrudes from the direction of the lower side b becomes an output shaft and transmits the rotational force generated by the electric motor 10 to the outside.

[0026] The schematic shape of the magnet 3 is, for example, a cylindrical shape. The magnet 3 has the axis x direction as the longitudinal 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 inside 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 a rotor 7 in the electric motor 10.

[0027] The bearing 4a is mounted on the upper cover portion 12 of the upper side a of the housing 1. The bearing 4b is mounted on the lower cover portion 13 of the lower side b of the housing 1. The bearings 4a and 4b are, for example, ball bearings. In the present invention, the type of the bearing is not particularly limited. The bearings 4a and 4b are each composed of an inner ring 41a, 41b and an outer ring 42a, 42b arranged with the axis x direction as the central axis, and rolling elements 43a, 43b provided between the inner rings 41a, 41b and the outer rings 42a, 42b. The bearings 4a and 4b support the shaft 2 by means of the inner peripheral surfaces 44a, 44b of the inner rings 41a, 41b.

[0028] The bearings 4a and 4b rotatably support the shaft 2 at any position in the axial direction x of the shaft 2. Specifically, the bearing 4a supports the upper side a portion of the shaft 2 in the axial direction x in a rotatable manner by inserting the shaft 2 into the inner peripheral surface 44a. The bearing 4b supports the lower side b portion of the shaft 2 in the axial direction x in a rotatable manner by inserting the shaft 2 into the inner peripheral surface 44b. Among the bearings 4a and 4b, the inner rings 41a, 41b, the outer rings 42a, 42b, and the rolling elements 43a, 43b are all made of a magnetic metal, and generally formed of an iron-containing alloy. The bearings 4a and 4b have an outer diameter of the outer rings 42a, 42b that is larger than the outer diameter of the magnet 3 in the radial direction. That is, in the radial direction, the outer rings 42a, 42b of the bearings 4a and 4b are arranged at a position outside the outer periphery of the magnet 3.

[0029] The stator 5 is held on the inner peripheral surface of the housing main body 11. Specifically, the stator 5 is arranged inside the housing main body 11 at a position corresponding to the magnet 3 in the axial direction x (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 in a ring shape so as to surround the magnet 3. The coil is wound around an extension portion extending from the stator core toward the inner peripheral side d. The insulator insulates the stator core from the coil. The stator 5 is arranged so that the ring-shaped inner peripheral surface of the stator core surrounds the magnet 3. A gap AG is provided between the inner peripheral surface of the stator core and the outer peripheral surface of the magnet 3.

[0030] In addition, regarding the shapes of the shaft 2, the magnet 3, the bearings 4a and 4b, and the stator 5, as long as they can achieve the rotational movement of the rotor 7 in the motor 10, they are not limited to the above examples.

[0031] The balance members 6a are arranged between the magnet 3 and the bearing 4a in the axial direction x of the shaft 2. The balance members 6b are arranged between the magnet 3 and the bearing 4b in the axial direction x of the shaft 2. The balance members 6a, 6b have through holes 61a, 61b penetrating therethrough in the axial direction x with the axial direction x as the length direction at the center. The balance members 6a, 6b are provided, for example, corresponding to the number of the bearings 4a, 4b. The balance members 6a, 6b rotate about the axial direction x together with the rotor 7, that is, the shaft 2 and the magnet 3. The balance members 6a, 6b function as balancers to prevent the eccentric movement of the rotor 7 when rotating about the axial direction x.

[0032] The balance members 6a, 6b are formed of magnetic members having a relatively high specific gravity, such as Fe-Cu sintered members. That is, the balance members 6a, 6b function as paths for magnetic flux to pass through.

[0033] Figure 3 Fig. is a plan view schematically showing the configuration of the balance members 6a, 6b of the motor 10. In addition, Figure 4 Fig. is a cross-sectional view schematically showing the configuration of the balance members 6a, 6b of the motor 10. As Figure 3 and Figure 4 shown, the balance members 6a, 6b are provided with the above-mentioned through holes 61a, 61b and hole portions 63a, 63b penetrating in the axial direction x on the faces 62a, 62b. The hole portions 63a, 63b function as mass adjustment portions for eliminating eccentricity when the balance members 6a, 6b rotate together with the rotor 7.

[0034] The hole portions 63a, 63b are formed by machining the faces 62a, 62b of the balance members 6a, 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 faces 62a, 62b form faces opposed to the bearings 4a, 4b in the axial direction x of the shaft 2. After the balance members 6a, 6b are mounted on the shaft 2 together with the magnet 3, the hole portions 63a, 63b can be provided at predetermined positions on the faces 62a, 62b. The formation positions of the hole portions 63a, 63b on the faces 62a, 62b are determined as follows, that is, for the purpose of eliminating the eccentric movement during the rotation of the rotor 7 and considering the balance of the center of gravity in the radial direction of the rotor 7.

[0035] In addition, in the above description, as an example of the mass adjustment portion in the present invention, the hole portions 63a, 63b penetrating in the axial direction x of the balance members 6a, 6b are shown, but in the present invention, the shape of the mass adjustment portion and the position of the mass adjustment portion on the faces 62a, 62b are not limited to the above examples. Figure 5 Fig. is a cross-sectional view schematically showing a modification example of the balance members 6a, 6b of the motor 20. As Figure 5As shown, the above-mentioned mass adjustment part is not Figure 3 and Figure 4 through holes such as the hole parts 63a and 63b shown. For example, they can be recessed parts 64a and 64b formed on the upper side a or the lower side b of the surfaces of the balance parts 6a and 6b (refer to Figure 5 (a)) or protruding parts 65a and 65b (refer to Figure 5 (b)). In addition, for the above-mentioned mass adjustment part, the shape of the hole is not limited to the above examples.

[0036] [Dimensions and Arrangements of Magnet, Bearings, and Balance Parts] Next, with reference to Figure 6 , the dimensions and arrangements of the magnet 3, the bearings 4a and 4b, and the balance parts 6a and 6b in the motor 10 will be described. Figure 6 For Figure 1 a cross-sectional view in the axial direction x of the motor 10 shown, it is a schematic view for explaining the dimensions and arrangements of the magnet 3, the bearings 4a and 4b, and the balance parts 6a and 6b.

[0037] As Figure 6 shown, the balance part 6a is arranged between the magnet 3 and the bearing 4a in the axial direction x of the shaft 2. In addition, the balance part 6b is arranged between the magnet 3 and the bearing 4b in the axial direction x of the shaft 2.

[0038] The outer diameter DB1 of the balance part 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 part 6a, the outer diameter DM of the magnet 3, and the outer diameter DR1 of the outer ring 42a of the bearing 4a is shown in the following formula (1).

[0039] DM < DB1 < DR1 (1)

[0040] The outer diameter DB2 of the balance part 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 part 6b, the outer diameter DM of the magnet 3, and the outer diameter DR2 of the outer ring 42b of the bearing 4b is shown in the following formula (2).

[0041] DM < DB2 < DR2 (2)

[0042] It should be noted that as long as the relationships of the above formulas (1) and (2) are 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 relationships of the above formulas (1) and (2) are maintained, the dimensions of the outer diameter DR1 and the outer diameter DR2 can be the same value or different values.

[0043] Since the balance components 6a and 6b, which are made of a magnetic material and rotate together with the shaft 2, reduce the magnetic flux from the magnet 3 from entering the bearings 4a and 4b, it is possible to reduce the change in the magnetic flux density of the magnetic flux from the magnet 3 passing through the bearings 4a and 4b, and it is possible to prevent eddy currents from being generated in the outer rings 42a and 42b of the bearings 4a and 4b. In particular, by making the outer diameters DB1 and DB2 of the balance components 6a and 6b have the relationships of the above formulas (1) and (2), it is possible to prevent the magnetic flux, that is, the leakage magnetic flux, from the magnet 3 toward the magnetic components other than the stator 5 from reaching the bearings 4a and 4b. That is, the balance components 6a and 6b can prevent a braking force from being applied to the shaft 2 via the magnet 3 by the magnetic force generated by the eddy currents generated in the outer rings 42a and 42b of the bearings 4a and 4b.

[0044] In addition, the eddy currents generated in the bearings 4a and 4b decrease 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 magnetic flux entering the bearings 4a and 4b by the balance components 6a and 6b formed by the magnetic components described above, and to prevent the vibration of the motor 10 caused by the centrifugal force.

[0045] The balance component 6a is located at a predetermined distance A1 from the bearing 4a in the axial direction x of the shaft 2. In addition, the balance component 6a is located at a predetermined distance B1 from the magnet 3 in the axial direction x of the shaft 2. The balance component 6b is located at a predetermined distance A2 from the bearing 4b in the axial direction x of the shaft 2. In addition, the balance component 6b is located at a predetermined distance B2 from the magnet 3 in the axial direction x of the shaft 2.

[0046] Here, the distance A1 between the balance component 6a and the bearing 4a is shorter than the distance B1 between the balance component 6a and the magnet 3 in the axial direction x of the shaft 2. The relationship between the distance A1 between the balance component 6a and the bearing 4a and the distance B1 between the balance component 6a and the magnet 3 is shown by the following formula (3).

[0047] A1 < B1 (3)

[0048] In addition, the distance A2 between the balance component 6b and the bearing 4b is shorter than the distance B2 between the balance component 6b and the magnet 3 in the axial direction x of the shaft 2. The relationship between the distance A2 between the balance component 6b and the bearing 4b and the distance B2 between the balance component 6b and the magnet 3 is shown by the following formula (4).

[0049] A2 < B2 (4)

[0050] In addition, the distance A1 and the distance A2 can be the same distance or different distances. Similarly, the distance B1 and the distance B2 can be the same distance or different distances.

[0051] By arranging the balance members 6a and 6b made of a magnetic material near the bearings 4a and 4b rather than the magnet 3 as described above, it is possible to prevent the leakage magnetic flux from the magnet 3 toward the bearings 4a and 4b. That is, by arranging the balance members 6a and 6b near the bearings 4a and 4b rather than the magnet 3, it is possible to further prevent braking from being applied to the bearings 4a and 4b.

[0052] In the electric motor 10, it is preferable that the distances B1 and B2 between the magnet 3 and the balance members 6a and 6b are longer than the air gap AG. By making the distances B1 and B2 longer than the air gap AG as described above, the electric motor 10 can make the magnetic path a path from the magnet 3 toward the stator 5, and thus can reduce the leakage magnetic flux and improve the magnetic efficiency. In addition, by making the distances B1 and B2 longer than the air gap AG, the leakage magnetic flux can be reduced, and thus the electric motor 10 can prevent braking from being applied to the bearing 4a and the bearing 4b due to eddy currents.

[0053] In addition, in the electric motor 10, as Figure 3 shown, the hole portions 63a and 63b, which are mass adjustment portions for eliminating the eccentric motion of the rotor 7 by adjusting the mass of the balance members 6a and 6b, are provided on the facing surfaces 62a and 62b that face away from each other in the axial direction x of the balance members 6a and 6b.

[0054] In the case of performing machining on the surfaces 62a and 62b from the axial direction x in order to adjust the mass of the balance members 6a and 6b, if the balance members 6a and 6b are in contact with other components without a gap in the axial direction x, there is a possibility of accidentally machining the other components. In this case, it is necessary to precisely control the diameter and feed rate of the cutting tool so that the cutting tool does not penetrate the balance members 6a and 6b.

[0055] In addition, in the case where it is difficult to machine the surfaces 62a and 62b of the balance members 6a and 6b, machining the sides of the balance members 6a and 6b is also considered, but it is difficult to machine the sides of the thin flat members, that is, the balance members 6a and 6b. In addition, in this case, there is a possibility that the torque during rotation of the shaft 2 becomes large and the load during rotation of the rotor 7 increases due to cutting chips or the like flying out from the sides.

[0056] In the electric motor 10, the balance members 6a and 6b are respectively at a predetermined distance B1 and B2 from the magnet 3 in the axial direction x of the shaft 2, and at a predetermined distance A1 and A2 from the bearings 4a and 4b. Therefore, in the electric motor 10, in the cutting process for adjusting the mass of the balance members 6a and 6b during balance adjustment, the operation of the cutting tool can be easily performed. That is, in the electric motor 10, during balance adjustment, the cutting process for adjusting the mass of the balance members 6a and 6b can be easily performed.

[0057] [Study on the ratio of the distance from the magnet to the balance member to the air gap] Refer to Figures 7 to 10 , and study the ratios RB1 and RB2 of the distances B1 and B2 from the magnet 3 to the balance members 6a and 6b in the electric motor 10 with respect to the air gap AG.

[0058] First, in the electric motor 10, in order to determine the ratios RB1 and RB2 of the distances B1 and B2 from the magnet 3 to the balance members 6a and 6b with respect to the air gap AG, the ratios RB0a and RB0b of the distances from the magnet 3 to the bearings 4a and 4b with respect to the air gap AG are changed. And, in the electric motor 10, the change in the mechanical load ML caused by changing RB0a and RB0b is studied. The mechanical load is the load inside the electric motor generated when the electric motor rotates in a non-energized state. This mechanical load mainly includes a frictional load and a magnetic load. The frictional load is generated by the friction between the rolling elements and the retainer of the bearing when the electric motor rotates, or the friction generated by the grease inside the electric motor, etc. The magnetic load is generated by the attractive force (cogging effect) between the magnet and the stator when the electric motor rotates.

[0059] Figure 7 A table showing the relationship between the mechanical load ML in the electric motor 10 and the ratios RB0a(A1 + B1 + C1 / AG) and RB0b(A2 + B2 + C2 / AG) of the distances (A1 + B1 + C1) and (A2 + B2 + C2) from the magnet 3 to the bearings 4a and 4b with respect to the air gap AG. Figure 8 A graph showing the relationship between the mechanical load ML in the electric motor 10 and the ratios RB0a(A1 + B1 + C1 / AG) and RB0b(A2 + B2 + C2 / AG) of the distances (A1 + B1 + C1) and (A2 + B2 + C2) from the magnet 3 to the bearings 4a and 4b with respect to the air gap AG.

[0060] In Figure 7 and Figure 8 , the ratios RB0a and RB0b of the distances from the magnet 3 to the bearings 4a and 4b with respect to the air gap AG represent the ratios of the distances from the magnet 3 to the bearings 4a and 4b when the air gap AG is set to 1. In addition, as Figure 7 and Figure 8As shown, the ratios RB0a and RB0b of the distances from the magnet 3 to the bearings 4a and 4b with respect to the air gap AG are changed to 1.5, 2.2, 2.8, and 3.5, and the mechanical load ML in this case is measured.

[0061] According to Figure 7 and Figure 8 It can be seen that in the motor 10, when the ratios RB0a and RB0b of the distances from the magnet 3 to the bearings 4a and 4b with respect to the air gap AG are between 2.2 and 2.8, the degree of reduction in the mechanical load ML is greater compared to before and after.

[0062] Next, the ratios RB1 and RB2 of the distances B1 and B2 with respect to the air gap AG in the motor 10 are studied. In the following description, the motor without the balance members 6a and 6b is referred to as the reference example motor. Based on the mechanical load ML of the motor 10, the mechanical load ML2 of the motor without the balance members 6a and 6b, and the ratio TR of the torque of the motor 10 to the torque of the motor without the balance members 6a and 6b, the ratios RB1 and RB2 of the distances B1 and B2 with respect to the air gap AG are studied.

[0063] Figure 9 Table showing the relationships between the ratios RB1 (B1 / AG) and RB2 (B2 / AG) of the distances B1 and B2 from the magnet 3 to the balance members 6a and 6b with respect to the air gap AG in the motor 10, the mechanical load ML, the mechanical load ML2, and the ratio TR of the torque of the motor 10 to the torque of the reference example motor. Figure 10 Graph showing the relationships between the ratios RB1 (B1 / AG) and RB2 (B2 / AG) of the distances B1 and B2 from the magnet 3 to the balance members 6a and 6b with respect to the air gap AG in the motor 10, the mechanical load ML, the mechanical load ML2, and the ratio TR of the torque of the motor 10 to the reference example motor. In the reference example motor, since the balance members 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. In Figure 9 the column of distance, "-" represents the mechanical load ML2 and the ratio TR of the torque of the motor 10 to the torque of the reference example motor in the reference example motor without the balance members 6a and 6b. In the present embodiment, the mechanical load ML is measured when the ratios RB1 and RB2 of the distance B2 with respect to the air gap AG are between the state where the magnet 3 is in contact with the balance members 6a and 6b ( Figure 9 "0" in

[0064] According to Figure 9 and Figure 10It can be seen that especially when the ratios RB1 and RB2 of the distance B2 from the magnet 3 to the balance members 6a and 6b are 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 in the reference example. That is, it can be seen that in the present embodiment, when the ratios RB1 and RB2 of the distance from the magnet 3 to the balance members 6a and 6b to the air gap AG are between 1.5 and 2.8, the efficiency of the motor 10 is improved compared to before and after.

[0065] In addition, according to Figure 9 and Figure 10 It can be seen that in the region where the ratios RB1 and RB2 of the distance from the magnet 3 to the balance members 6a and 6b to the air gap AG of the motor 10 are 1.5 or more, the torque ratio TR of the motor 10 to the motor in the reference example is 1.0 or more. That is, it can be seen that in the region where the ratios RB1 and RB2 of the distance from the magnet 3 to the balance members 6a and 6b to the air gap AG are 1.5 or more, the motor 10 generates a larger torque than the motor in the reference example.

[0066] 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 balance members 6a and 6b to the air gap AG in the motor 10 are between 1.5 and 2.8, the mechanical load ML decreases and a larger torque than the motor in the reference example is generated. Therefore, it can be said that in the motor 10, it is ideal to set the ratios RB1 and RB2 of the distance from the magnet 3 to the balance members 6a and 6b to the air gap AG between 1.5 and 2.8.

[0067] As described above, according to the motor 10, high-speed rotation can be achieved.

[0068] The embodiments of the present invention have been described above, but the present invention is not limited to the motor 10 according to the above-described embodiments of the present invention, but includes all modes included in the concept of the present invention and the claims. In addition, the respective configurations can be appropriately selectively combined to achieve at least a part of the above-described problems and effects. For example, the shapes, materials, arrangements, dimensions, etc. of the respective constituent elements in the above-described embodiments can be appropriately changed according to the specific usage mode of the present invention.

[0069] Reference Numeral Explanation 1 Housing; 2 Shaft; 3 Magnet; 4a Bearing; 4b Bearing; 5 Stator; 6a Balancing Component; 6b Balancing Component; 7 Rotor; 10 Motor; 11 Housing Body; 12 Upper Cover Portion; 13 Lower Cover Portion; 31 Shaft Through-Hole; 41a Inner Ring; 41b Inner Ring; 42a Outer Ring; 42b Outer Ring; 43a Rolling Element; 43b Rolling Element; 44a Inner Peripheral Surface; 44b Inner Peripheral Surface; 61a Through-Hole; 61b Through-Hole; 62a Face Portion; 62b Face Portion; 63a Hole Portion; 63b Hole Portion; 64a Concave Portion; 64b Concave Portion; 65a Convex Portion; 65b Convex Portion

Claims

1. A motor, which comprises: a shaft; at least two bearings for supporting the shaft; a magnet supported by the shaft between the at least two bearings; a stator surrounding the magnet; a magnetic component disposed between the magnet and at least one of the bearings in the longitudinal direction of the shaft, the magnetic component having an outer diameter larger than the outer diameter of the magnet.

2. The motor according to claim 1, wherein the magnetic component has an outer diameter smaller than the outer diameter of the bearing.

3. The motor according to claim 1 or 2, wherein in the longitudinal direction of the shaft, the distance between the bearing and the magnetic component is shorter than the distance between the magnetic component and the magnet.

4. The motor according to any one of claims 1 to 3, wherein the magnetic component is spaced apart from the bearing and the magnet by a predetermined distance respectively in the longitudinal direction of the shaft.

5. The motor according to any one of claims 1 to 4, comprising a rotor, the rotor including the shaft and the magnet, the magnetic component being a balance component of the rotor.

6. The motor according to claim 5, wherein in the longitudinal direction of the shaft, the magnetic component has a face facing the bearing, and a recess, a hole or a protrusion is provided on the face facing the bearing.

7. The motor according to claim 5 or 6, wherein in the longitudinal direction of the shaft, the distance between the magnet and the magnetic component is longer than the distance of the air gap.

8. The motor according to any one of claims 1 to 7, having a plurality of bearings including the two bearings, the magnetic components are respectively provided on the plurality of bearings.

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