Motor

Abstract

To provide a motor capable of realizing high-speed rotation.SOLUTION: A motor 10 comprises: a shaft 2; at least two bearings 4a and 4b supporting the shaft 2; a magnet 3 supported by the shaft 2 between the two bearings 4a and 4b; a stator 5 enclosing the magnet 3; and a magnetic member 6a and a magnetic member 6b each disposed between the magnet 3 and the bearings 4a / 4b in a length direction of the shaft 2. The magnetic member 6a and the magnetic member 6b have outer diameters that are larger than an outer diameter of the magnet 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A motor is known that includes a stator with a coil wound around a stator core, a rotor with a rotating shaft fixed to the rotor core and permanent magnets embedded in the periphery of the rotor core, and a pair of balance rings inserted and fixed on both sides of the rotor core on the rotating shaft (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-39732 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the application, motors are required to rotate their rotors at high speeds, for example, 50,000 revolutions per minute. When rotating a motor at high speeds, it is desirable to reduce the centrifugal force generated when the rotor rotates, for example by reducing the outer diameter of the magnets attached to the rotor.

[0005] However, with conventional motors, including the motor disclosed in Patent Document 1, it has been difficult to achieve high-speed rotation due to the following factors.

[0006] First, in conventional motors, the bearing material contains magnetic metals such as iron, so some of the magnetic flux generated by the magnet in the rotating rotor can leak toward the outer ring of the bearing. In conventional motors, this leakage flux can generate eddy currents in the bearing. In conventional motors, these eddy currents can apply braking to the bearing, creating resistance to the rotational force of the rotor.

[0007] Furthermore, to rotate a motor at high speed, it is necessary to ensure the rotor is balanced with high precision. Generally, balancing a rotor is achieved by attaching a balance member to the shaft and then reducing the weight of the balance member through machining or other processes. However, in conventional motors, the axial distance between the magnet and the balance member is short, requiring careful operation of the cutting tool, making it difficult to reduce the mass of the balance member attached to the rotor.

[0008] The present invention addresses the above-mentioned problem as an example, and has an object to provide a motor that can achieve high-speed rotation. [Means for solving the problem]

[0009] In order to achieve the above object, the motor of the present invention comprises a shaft, at least two bearings supporting the shaft, a magnet supported on the shaft between the at least two bearings, a stator surrounding the magnet, and a magnetic member arranged 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 a motor according to one aspect of the present invention, the distance between the bearing and the magnetic member in the longitudinal direction of the shaft is shorter than the distance between the magnetic member and the magnet.

[0012] In a 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.

[0013] A motor according to one aspect of the present invention includes a rotor having a shaft and a magnet, and the magnetic member is a balance member for the rotor.

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

[0015] In a motor according to one aspect of the present invention, the distance between the magnet and the magnetic member in the longitudinal direction of the shaft is longer than the distance of the air gap.

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

[0017] The motor according to the present invention can achieve high speed rotation. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing a schematic configuration of a motor according to an embodiment of the present invention; [Figure 2] 2 is a cross-sectional view taken along the axis of the motor shown in FIG. 1. [Figure 3] 2 is a plan view schematically showing the configuration of a balance member of the motor shown in FIG. 1. FIG. [Figure 4] 2 is a cross-sectional view schematically showing the configuration of a balance member of the motor shown in FIG. 1. FIG. [Figure 5] 1. FIG. 4 is a cross-sectional view schematically showing a modified example of the balance member of the motor shown in FIG. [Figure 6] FIG. 2 is a cross-sectional view taken along the axis of the motor shown in FIG. 1, illustrating the dimensions and arrangement of the shaft, bearings, and balance members. [Figure 7] 2 is 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 in FIG. 1. [Figure 8] 2 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 in FIG. 1. [Figure 9]2 is a table showing the relationship between the distance from the magnet to the balance member relative to the air gap, the mechanical load, and the ratio of the torque of the motor shown in FIG. 1 to the torque of a motor not provided with a balance member in the motor shown in FIG. 1. [Figure 10] 2 is a graph showing the relationship between the distance from the magnet to the balance member relative to the air gap, the mechanical load, and the ratio of the torque of the motor shown in FIG. 1 to the torque of a motor without a balance member. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A motor according to an embodiment of the present invention will now be described with reference to the drawings.

[0020] [Overall motor configuration] The overall configuration of a motor according to an embodiment of the present invention will be described. Fig. 1 is a perspective view showing a schematic configuration of a motor 10 according to an embodiment of the present invention, and Fig. 2 is a cross-sectional view of the motor 10 taken along an axis x.

[0021] In the following description, for convenience, the direction perpendicular to the axis x direction shown in Fig. 1 (hereinafter also referred to as the "radial direction") will be referred to as the front side of motor 10. Also, in the following description, for convenience, the direction of arrow a in the axis x direction shown in Fig. 2 will be referred to as the upper side a, and the direction of arrow b in the axis x direction will be referred to as the lower side b. Also, in the radial direction, the direction away from axis x (the direction of arrow c in Fig. 2) will be referred to as the outer circumferential side c, and the direction toward axis x (the direction of arrow d in Fig. 2) will be referred to as the inner circumferential side d.

[0022] Motor 10 includes a shaft 2, at least two bearings 4a and 4b that support shaft 2, a magnet 3 that is supported by shaft 2 and rotates together with shaft 2, and a stator 5 that surrounds magnet 3. Motor 10 also includes balance members 6a and 6b as magnetic members that are arranged between magnet 3 and at least one of bearings 4a and 4b in the longitudinal direction of shaft 2, rotate together with shaft 2, and have an outer diameter larger than that of magnet 3. The configuration of motor 10 will be described in detail below.

[0023] The case 1 determines the general shape of the motor 10 and houses the above-mentioned components of the motor 10. The case 1 includes a case main body 11 formed in a hollow cylindrical shape with upper and lower lids open, an upper lid 12 attached to the lid on the upper side (one end side) a of the case main body 11, and a lower lid 13 attached to the lid on the lower side (the other end side) b of the case main body 11.

[0024] The upper cover 12 has a generally disk-like shape corresponding to the shape of the cover surface of the case body 11 in order to close the case body 11 from the upper side a. The upper cover 12 also has a bearing retaining hole 12a as a hole for retaining the bearing 4a through which the shaft 2 is passed. The lower cover 13 has a generally disk-like shape corresponding to the shape of the cover surface of the case body 11 in order to close the case body 11 from the lower side b. The lower cover 13 also has a bearing retaining hole 13a as a hole for retaining the bearing 4b through which the shaft 2 is passed.

[0025] The shaft 2 is, for example, a round bar member whose longitudinal direction is the axis x, which is the direction in which it extends (longitudinal direction). The shaft 2 rotates around the axis x. The shaft 2 is supported in bearing retaining holes 12a and 13a of the case 1 via bearings 4a and 4b. The tip (one end) of the shaft 2 is exposed to the outside of the case 1 through the bearing retaining holes 12a and 13a of the case 1. The part (other end) of the tip of the shaft 2 that is exposed from the lower side b serves as the output shaft and transmits the rotational force generated by the motor 10 to the outside.

[0026] The magnet 3 has a general cylindrical shape, for example. The magnet 3 has a shaft through-hole 31 as a through-hole that passes through the center of the magnet 3, with the axis x direction as the longitudinal direction. The magnet 3 is supported by the shaft 2 at a position between the bearings 4a and 4b inside the case 1. The magnet 3 supported by the shaft 2 rotates together with the shaft 2. The shaft 2 and the magnet 3 form the rotor 7 of the motor 10.

[0027] The bearing 4a is attached to the upper cover 12 on the upper side a of the case 1. The bearing 4b is attached to the lower cover 13 on the lower side b of the case 1. The bearings 4a and 4b are, for example, ball bearings. In the present invention, the type of bearing is not particularly limited. The bearings 4a and 4b are, for example, composed of inner rings 41a and 41b and outer rings 42a and 42b arranged so that their central axes are in the direction of the axis x, 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 by inner circumferential surfaces 44a and 44b of the inner rings 41a and 41b.

[0028] The bearings 4a and 4b rotatably support the shaft 2 at any position in the direction of the axis x of the shaft 2. Specifically, the bearing 4a rotatably supports an upper side a portion of the shaft 2 in the direction of the axis x by inserting the shaft 2 into its inner circumferential surface 44a. The bearing 4b rotatably supports a lower side b portion of the shaft 2 in the direction of the axis x by inserting the shaft 2 into its inner circumferential surface 44b. The bearings 4a and 4b each have inner rings 41a and 41b, outer rings 42a and 42b, and rolling elements 43a and 43b, all made of magnetic metal, typically an alloy containing iron. The outer rings 42a and 42b of the bearings 4a and 4b have outer diameters that are larger than the outer diameter of the magnet 3 in the radial direction. In other words, the outer rings 42a and 42b of the bearings 4a and 4b are positioned radially outward of the outer periphery of the magnet 3.

[0029] The stator 5 is held on the inner peripheral surface of the case body 11. Specifically, the stator 5 is disposed inside the case body 11 at a position corresponding to the magnet 3 in the direction of the axis x (the longitudinal direction of the shaft 2), and at a position farther from the shaft 2 in the radial direction than the magnet 3. The stator 5 is composed of a stator core formed in an annular shape so as to surround the magnet 3, a coil wound around an extension extending from the stator core to the inner peripheral side d, and an insulator that insulates the stator core from the coil. The stator 5 is disposed so that the annular inner peripheral surface of the stator core surrounds the magnet 3. An air gap AG is provided between the inner peripheral surface of the stator core and the outer peripheral surface of the magnet 3.

[0030] The shapes of the shaft 2, magnet 3, bearings 4a and 4b, and stator 5 are not limited to the above example, as long as they allow the rotor 7 in the motor 10 to rotate.

[0031] The balancing member 6a is disposed between the magnet 3 and the bearing 4a in the direction of the axis x of the shaft 2. The balancing member 6b is disposed between the magnet 3 and the bearing 4b in the direction of the axis x of the shaft 2. The balancing members 6a and 6b have through holes 61a and 61b in their centers that run longitudinally along the axis x. The balancing members 6a and 6b are provided in numbers corresponding to the number of bearings 4a and 4b. The balancing members 6a and 6b rotate around the axis x together with the rotor 7, i.e., the shaft 2 and magnet 3. The balancing members 6a and 6b function as balancers that prevent eccentric motion when the rotor 7 rotates around the axis x.

[0032] The balance members 6a and 6b are made of a magnetic material having a relatively high specific gravity, such as an Fe-Cu sintered material, etc. In other words, the balance members 6a and 6b function as a path through which magnetic flux passes.

[0033] Fig. 3 is a plan view schematically showing the configuration of the balance members 6a and 6b of the motor 10. Fig. 4 is a cross-sectional view schematically showing the configuration of the balance members 6a and 6b of the motor 10. As shown in Figs. 3 and 4, the balance members 6a and 6b have the above-mentioned through holes 61a and 61b and holes 63a and 63b penetrating in the direction of the axis x on their surfaces 62a and 62b. The holes 63a and 63b function as mass adjustment parts for eliminating eccentricity when the balance members 6a and 6b rotate together with the rotor 7.

[0034] The holes 63a, 63b are formed in the surfaces 62a, 62b of the balance members 6a, 6b by cutting from either the upper side a or the lower side b toward the other using a cutting tool such as a drill. The surfaces 62a, 62b form surfaces that face the bearings 4a, 4b in the direction of the axis x of the shaft 2. The holes 63a, 63b can be formed at predetermined positions on the surfaces 62a, 62b after the balance members 6a, 6b are assembled to the shaft 2 together with the magnet 3. The positions at which the holes 63a, 63b are formed in the surfaces 62a, 62b are determined in consideration of balancing the center of gravity of the rotor 7 in the radial direction so as to eliminate eccentric motion during rotation of the rotor 7.

[0035] In the above description, the holes 63a, 63b penetrating the balance members 6a, 6b in the direction of the axis x are shown as an example of a mass adjustment portion in the present invention. However, the shape of the mass adjustment portion and the position of the mass adjustment portion on the surface portions 62a, 62b in the present invention are not limited to the above example. FIG. 5 is a cross-sectional view schematically showing a modified example of the balance members 6a, 6b of the motor 20. As shown in FIG. 5, the mass adjustment portion does not have to be a through hole like the holes 63a, 63b shown in FIGS. 3 and 4, but may be, for example, recesses 64a, 64b (see FIG. 5(a)) or protrusions 65a, 65b (see FIG. 5(b)) formed on the surface facing the upper side a or lower side b of the balance members 6a, 6b. Furthermore, the shape of the holes in the mass adjustment portion is not limited to the above example.

[0036] [Dimensions and arrangement of magnets, bearings, and balance members] Next, the dimensions and arrangement of the magnet 3, bearings 4a and 4b, and balance members 6a and 6b in the motor 10 will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of the motor 10 in Fig. 1 taken along the axis x, and is a schematic diagram for describing the dimensions and arrangement of the magnet 3, bearings 4a and 4b, and balance members 6a and 6b.

[0037] 6, balancing member 6a is disposed between magnet 3 and bearing 4a in the direction of axis x of shaft 2. Balancing member 6b is disposed between magnet 3 and bearing 4b in the direction of axis x of shaft 2.

[0038] 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 between 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).

[0039] DM <DB1<DR1 (1)

[0040] 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 between 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).

[0041] DM <DB2<DR2 (2)

[0042] The dimensions of the outer diameters DB1 and DB2 may be the same or different as long as the relationship between the above formulas (1) and (2) is maintained. Similarly, the dimensions of the outer diameters DR1 and DR2 may be the same or different as long as the relationship between the above formulas (1) and (2) is maintained.

[0043] The balance members 6a, 6b, which are made of a magnetic material and rotate together with the shaft 2, reduce the penetration of magnetic flux from the magnet 3 into the bearings 4a, 4b, thereby minimizing the change in magnetic flux density from the magnet 3 passing through the bearings 4a, 4b and preventing eddy currents from occurring in the outer rings 42a, 42b of the bearings 4a, 4b. In particular, the balance members 6a, 6b, having outer diameters DB1, DB2 that satisfy the relationship of equations (1) and (2) above, can prevent leakage magnetic flux, which is magnetic flux from the magnet 3 traveling toward magnetic components other than the stator 5, from traveling toward the bearings 4a, 4b. In other words, the balance members 6a, 6b can prevent a braking force from being applied to the shaft 2 via the magnet 3 due to magnetic forces generated by eddy currents in the outer rings 42a, 42b of the bearings 4a, 4b.

[0044] The eddy currents generated in the bearings 4a, 4b decrease as the distance from the magnet 3 to the bearings 4a, 4b increases. However, as the distance from the fulcrum (bearings 4a, 4b) to the center of rotation (magnet 3) increases, the centrifugal force caused by the rotational motion increases, causing greater wobble of the rotor 7. Therefore, in motor 10, using balance members 6a, 6b made of the magnetic material described above to reduce leakage flux entering the bearings 4a, 4b while preventing wobble of motor 10 caused by centrifugal force is effective in realizing high-speed rotation of the motor.

[0045] Balancing member 6a is spaced a predetermined distance A1 from bearing 4a in the direction of axis x of shaft 2. Balancing member 6a is spaced a predetermined distance B1 from magnet 3 in the direction of axis x of shaft 2. Balancing member 6b is spaced a predetermined distance A2 from bearing 4b in the direction of axis x of shaft 2. Balancing member 6b is spaced a predetermined distance B2 from magnet 3 in the direction of axis x of shaft 2.

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

[0047] A1 <B1 (3)

[0048] Furthermore, the distance A2 between the balancing member 6b and the bearing 4b is shorter than the distance B2 between the balancing member 6b and the magnet 3 in the direction of the axis x of the shaft 2. The relationship between the distance A2 between the balancing member 6b and the bearing 4b and the distance B2 between the balancing member 6b and the magnet 3 is expressed by the following formula (4).

[0049] A2 <B2 (4)

[0050] Note that distance A1 and distance A2 may be the same or different distances, and similarly, distance B1 and distance B2 may be the same or different distances.

[0051] As described above, by arranging the balance members 6a and 6b made of a magnetic material closer to the bearings 4a and 4b than the magnet 3, it is possible to prevent the occurrence of leakage magnetic flux from the magnet 3 toward the bearings 4a and 4b. In other words, by arranging the balance members 6a and 6b closer to the bearings 4a and 4b than the magnet 3, it is possible to better prevent braking from being applied to the bearings 4a and 4b.

[0052] In motor 10, distances B1 and B2 between magnet 3 and balance members 6a and 6b are preferably longer than air gap AG. In this way, by making distances B1 and B2 longer than air gap AG, motor 10 can direct the magnetic path from magnet 3 to stator 5, thereby reducing leakage magnetic flux and improving magnetic efficiency. Furthermore, by making distances B1 and B2 longer than air gap AG, leakage magnetic flux can be reduced, and motor 10 can prevent braking caused by eddy currents from being applied to bearings 4a and 4b.

[0053] In addition, in the motor 10, as shown in FIG. 3, holes 63a, 63b serving as mass adjustment sections for adjusting the mass of the balance members 6a, 6b to eliminate eccentric motion of the rotor 7 are provided in the surfaces 62a, 62b of the balance members 6a, 6b that face each other in the direction of the axis x.

[0054] When cutting surfaces 62a, 62b from the direction of axis x to adjust the mass of balance members 6a, 6b, if balance members 6a, 6b and other members are in close contact with each other in the direction of axis x, there is a risk of accidentally cutting the other members. 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 balance members 6a, 6b.

[0055] Furthermore, if it is difficult to grind the surface portions 62a, 62b of the balancing members 6a, 6b, grinding the side surfaces of the balancing members 6a, 6b is an option, but grinding the side surfaces of the balancing members 6a, 6b is difficult because they are thin, flat members. In this case, there is also a risk that shavings or the like will fly out from the side surfaces, increasing the moment when the shaft 2 rotates and increasing the load on the rotor 7 when it rotates.

[0056] In motor 10, balance members 6a and 6b are spaced apart by predetermined distances B1 and B2 from magnet 3 and predetermined distances A1 and A2 from bearings 4a and 4b in the direction of axis x of shaft 2. Therefore, according to motor 10, when performing balance adjustment, a cutting tool can be easily operated in cutting processing to adjust the masses of balance members 6a and 6b. That is, according to the motor 10, when performing balance adjustment, cutting work for adjusting the mass of the balance members 6a and 6b can be easily performed.

[0057] [Consideration of the ratio of the distance from the magnet to the balance member to the air gap] 7 to 10, the ratios RB1 and RB2 of the distances B1 and B2 from the magnet 3 to the balance members 6a and 6b to the air gap AG in the motor 10 will be considered.

[0058] First, in motor 10, to determine the ratios RB1 and RB2 of the distances B1 and B2 to the air gap AG, the ratios RB0a and RB0b of the distances from magnet 3 to bearings 4a and 4b to the air gap AG are changed. Then, we consider how the mechanical load ML of motor 10 changes when RB0a and RB0b are changed. The mechanical load is the load inside the motor that occurs when the motor is rotated without being powered on. This mechanical load mainly consists of a friction load and a magnetic load. The friction load is caused by friction between the rolling elements of the bearings and the cage as the motor rotates, or friction caused by grease inside the motor. The magnetic load is caused by the attractive force (cogging) between the magnet and stator as the motor rotates.

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

[0060] 7 and 8, the ratios RB0a and RB0b of the distance from the magnet 3 to the bearings 4a and 4b to the air gap AG indicate the ratio of the distance from the magnet 3 to the bearings 4a and 4b when the air gap AG is set to 1. Also, as shown in Figures 7 and 8, the ratios RB0a and RB0b of the distance from the magnet 3 to the bearings 4a and 4b to the air gap AG were changed to 1.5, 2.2, 2.8, and 3.5, and the mechanical load ML in these cases was measured.

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

[0062] Next, we will consider the ratios RB1 and RB2 of the distances B1 and B2 to the air gap AG in motor 10. In the following explanation, the motor without balancing members 6a and 6b will be referred to as the reference motor. The ratios RB1 and RB2 of the distances B1 and B2 to the air gap AG will be considered based on the mechanical load ML of motor 10, the mechanical load ML2 of the motor without balancing members 6a and 6b, and the ratio TR of the torque of motor 10 to the torque of the motor without balancing members 6a and 6b.

[0063] FIG. 9 is a table showing the relationship between the ratios RB1 (B1 / AG) and RB2 (B2 / AG) of the distances B1 and B2 from the magnet 3 to the balancing members 6a and 6b relative 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 that of the reference motor. FIG. 10 is a graph showing the relationship between the ratios RB1 (B1 / AG) and RB2 (B2 / AG) of the distances B2 from the magnet 3 to the balancing members 6a and 6b relative 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 that of the reference motor. Because the motor of the reference motor does not include balancing members 6a and 6b, changes in the mechanical load ML2 correspond to changes in the distance from the magnet to the bearing. In FIG. 9, the "-" in the distance column indicates the mechanical load ML2 of the motor of the reference motor without balancing members 6a and 6b, and the ratio TR of the torque of the motor 10 to that of the reference motor. In this embodiment, the mechanical load ML was measured when the ratios RB1 and RB2 of the distance B2 to the air gap AG were changed from a state in which the magnet 3 and the balance members 6a and 6b were in contact ("0" in FIG. 9) to 3.5.

[0064] 9 and 10, it can be seen that the mechanical load ML of motor 10 is significantly reduced compared to the mechanical load ML2 of the motor of the reference example, particularly when the ratios RB1, RB2 of the distance B2 from magnet 3 to balance members 6a, 6b are between 1.5 and 2.8. In other words, it can be seen that in this embodiment, the efficiency of motor 10 is improved when the ratios RB1, RB2 of the distances from magnet 3 to balance members 6a, 6b to the air gap AG are between 1.5 and 2.8, compared to before and after that range.

[0065] 9 and 10, it can be seen that the ratio TR of the torque of motor 10 to that of the motor of the reference example is 1.0 or greater in the region where the ratios RB1, RB2 of the distances from magnet 3 to balance members 6a, 6b to air gap AG are 1.5 or greater. In other words, it can be seen that motor 10 generates a greater torque than the motor of the reference example in the region where the ratios RB1, RB2 of the distances from magnet 3 to balance members 6a, 6b to air gap AG are 1.5 or greater.

[0066] 7 to 10, it can be seen that when the ratios RB1, RB2 of the distance from the magnet 3 to the magnetic members 6a, 6b to the air gap AG in motor 10 are between 1.5 and 2.8, the mechanical load ML decreases and a greater torque can be generated than in the motor of the reference example. Therefore, it can be said that in motor 10, it is desirable to set the ratios RB1, RB2 of the distance from the magnet 3 to the balance members 6a, 6b to the air gap AG between 1.5 and 2.8.

[0067] As described above, the motor 10 can achieve high speed rotation.

[0068] Although the present invention has been described above as an embodiment, it is not limited to the motor 10 according to the above embodiment of the present invention, and includes all aspects encompassed by the concept of the present invention and the scope of the claims. Furthermore, the various components may be appropriately and selectively combined to achieve at least some of the above-described problems and advantages. For example, the shape, material, arrangement, size, etc. of the various components in the above embodiment may be appropriately modified depending on the specific use of the present invention. [Explanation of symbols]

[0069] 1...Case, 2...Shaft, 3...Magnet, 4a...Bearing, 4b...Bearing, 5...Stator, 6a...Balancing member, 6b...Balancing member, 7...Rotor, 10...Motor, 11...Case 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...Surface portion, 62b...Surface portion, 63a...Hole portion, 63b...Hole portion, 64a...Recess, 64b...Recess, 65a...Convex portion, 65b...Convex portion

Claims

1. A shaft and two bearings supporting the shaft; a cylindrical magnet and two members supported by the shaft between the two bearings; a stator surrounding the cylindrical magnet, The two members face the cylindrical magnet in the longitudinal direction of the shaft, one of the two members is disposed between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft, the other of the two members is disposed between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft, The two bearings each include a rolling element and an outer ring made of a magnetic metal, the two members form a path through which magnetic flux generated from the cylindrical magnet passes, In the longitudinal direction of the shaft, the one member is located closer to the one bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the other member is located closer to the other bearing than the cylindrical magnet, a dimension of the one member in a radial direction of the shaft is smaller than a dimension of an outer ring of the one bearing, a dimension of the other member in a radial direction of the shaft is smaller than a dimension of an outer ring of the other bearing; Motor.

2. A shaft, two bearings supporting the shaft; a cylindrical magnet and two members supported by the shaft between the two bearings; a stator surrounding the cylindrical magnet, The two members face the cylindrical magnet in the longitudinal direction of the shaft, one of the two members is disposed between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft, the other of the two members is disposed between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft, The two bearings each include a rolling element and an outer ring made of a magnetic metal, the two members form a path through which magnetic flux generated from the cylindrical magnet passes, In the longitudinal direction of the shaft, the one member is located closer to the one bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the other member is located closer to the other bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the distance between the end of the one member on the cylindrical magnet side and the cylindrical magnet is smaller than the distance between the end of the other member on the cylindrical magnet side and the cylindrical magnet, a dimension of the one member in a radial direction of the shaft is smaller than a dimension of an outer ring of the one bearing, a dimension of the other member in a radial direction of the shaft is smaller than a dimension of an outer ring of the other bearing; Motor.

3. A shaft, two bearings supporting the shaft; a cylindrical magnet and two members supported by the shaft between the two bearings; a stator surrounding the cylindrical magnet, The two members face the cylindrical magnet in the longitudinal direction of the shaft, one of the two members is disposed between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft, the other of the two members is disposed between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft, The two bearings each include a rolling element and an outer ring made of a magnetic metal, the two members form a path through which magnetic flux generated from the cylindrical magnet passes, In the longitudinal direction of the shaft, the one member is located closer to the one bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the other member is located closer to the other bearing than the cylindrical magnet. Motor.

4. A shaft and two bearings supporting the shaft; a cylindrical magnet and two members supported by the shaft between the two bearings; a stator surrounding the cylindrical magnet, The two members face the cylindrical magnet in the longitudinal direction of the shaft, one of the two members is supported on a first portion of the shaft between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft; the other of the two members is supported by a second portion of the shaft between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft, The two bearings each include a rolling element and an outer ring made of a magnetic metal, the two members form a path through which magnetic flux generated from the cylindrical magnet passes, In a longitudinal direction of the shaft, the first portion of the shaft is located closer to the one bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the second portion of the shaft is located closer to the other bearing than the cylindrical magnet, a dimension of the one member in a radial direction of the shaft is smaller than a dimension of an outer ring of the one bearing, a dimension of the other member in a radial direction of the shaft is smaller than a dimension of an outer ring of the other bearing; Motor.

5. A shaft, two bearings supporting the shaft; a cylindrical magnet and two members supported by the shaft between the two bearings; a stator surrounding the cylindrical magnet, The two members face the cylindrical magnet in the longitudinal direction of the shaft, one of the two members is supported on a first portion of the shaft between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft; the other of the two members is supported by a second portion of the shaft between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft, The two bearings each include a rolling element and an outer ring made of a magnetic metal, the two members form a path through which magnetic flux generated from the cylindrical magnet passes, In a longitudinal direction of the shaft, the first portion of the shaft is located closer to the one bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the second portion of the shaft is located closer to the other bearing than the cylindrical magnet, a distance between a first portion of the shaft and the cylindrical magnet in a longitudinal direction of the shaft is smaller than a distance between a second portion of the shaft and the cylindrical magnet; a dimension of the one member in a radial direction of the shaft is smaller than a dimension of an outer ring of the one bearing, a dimension of the other member in a radial direction of the shaft is smaller than a dimension of an outer ring of the other bearing; Motor.

6. A shaft, two bearings supporting the shaft; a cylindrical magnet and two members supported by the shaft between the two bearings; a stator surrounding the cylindrical magnet, The two members face the cylindrical magnet in the longitudinal direction of the shaft, one of the two members is supported on a first portion of the shaft between the cylindrical magnet and one of the two bearings in the longitudinal direction of the shaft; the other of the two members is supported by a second portion of the shaft between the cylindrical magnet and the other of the two bearings in the longitudinal direction of the shaft, The two bearings each include a rolling element and an outer ring made of a magnetic metal, the two members form a path through which magnetic flux generated from the cylindrical magnet passes, In a longitudinal direction of the shaft, the first portion of the shaft is located closer to the one bearing than the cylindrical magnet, In the longitudinal direction of the shaft, the second portion of the shaft is located closer to the other bearing than the cylindrical magnet. Motor.

7. The one member is spaced a predetermined distance from the one bearing in the longitudinal direction of the shaft.

7. The motor according to claim 1.

8. the one member is a magnetic material, the other member is a magnetic material; A motor according to any one of claims 1 to 7.

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