阅读说明：本技术 电动机 (Electric motor ) 是由 癸生川幸嗣 于 2019-07-12 设计创作，主要内容包括：本发明提供一种电动机,其能够实现高速旋转。电动机(10)包括：轴(2)；至少2个轴承,即轴承(4a)及轴承(4b),其用于支承轴(2)；磁铁(3),其在2个轴承(4a)及轴承(4b)之间,被轴(2)支承；定子(5),其包围磁铁(3)；以及磁性部件(6a)及磁性部件(6b),其在轴(2)的长度方向上,被配置在磁铁(3)与轴承(4a)及轴承(4b)之间,磁性部件(6a)及磁性部件(6b)具有比磁铁(3)的外径大的外径。(The invention provides a motor capable of realizing high-speed rotation. The motor (10) includes: a shaft (2); at least 2 bearings, namely a bearing (4a) and a bearing (4b), for supporting the shaft (2); a magnet (3) supported by the shaft (2) between the 2 bearings (4a) and the bearings (4 b); a stator (5) that surrounds the magnet (3); and a magnetic member (6a) and a magnetic member (6b) which are arranged between the magnet (3) and the bearings (4a) and (4b) in the longitudinal direction of the shaft (2), wherein the magnetic member (6a) and the magnetic member (6b) have outer diameters larger than the outer diameter of the magnet (3).)

1. An electric motor, comprising:

a shaft;

at least 2 bearings for supporting the shaft;

a magnet supported by the shaft between the at least 2 bearings;

a stator surrounding the magnet;

a magnetic member disposed between the magnet and at least 1 of the bearings in a longitudinal direction of the shaft,

the magnetic member has an outer diameter larger than an outer diameter of the magnet.

2. The motor according to claim 1, wherein,

the magnetic member has an outer diameter smaller than an outer diameter of the bearing.

3. The motor according to claim 1 or 2,

the distance between the bearing and the magnetic member is shorter than the distance between the magnetic member and the magnet in the longitudinal direction of the shaft.

4. The motor according to any one of claims 1 to 3,

the magnetic member is spaced apart from the bearing and the magnet by a predetermined distance in a longitudinal direction of the shaft.

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

the magnetic component is a balance component of the rotor.

6. The motor according to claim 5, wherein,

the magnetic member has a surface portion facing the bearing in a longitudinal direction of the shaft, and a concave portion, a hole portion, or a convex portion is provided in the surface portion facing the bearing.

7. The motor according to claim 5 or 6,

the distance between the magnet and the magnetic member is longer than the distance of the gap in the longitudinal direction of the shaft.

8. The motor according to any one of claims 1 to 7, having a plurality of bearings including the 2 bearings,

the magnetic members are respectively provided at the plurality of bearings.

Technical Field

The present invention relates to an electric motor.

Background

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

Disclosure of Invention

Problems to be solved by the invention

For the motor, it is desirable to rotate the rotor at a high speed of, for example, 50000 revolutions per minute, depending on the use thereof. When the motor is rotated at a high speed, for example, it is desirable to reduce the outer diameter of the magnet attached to the rotor so as to reduce the centrifugal force generated when the rotor rotates.

However, in the conventional motor including the motor disclosed in patent document 1, it is difficult to realize high-speed rotation for the following reasons.

First, since a conventional motor includes a magnetic metal such as iron as a material of a bearing, a part of a magnetic flux generated by a magnet of a rotating rotor may be directed toward an outer ring of the bearing as a leakage magnetic flux. In the conventional motor, eddy current may be generated in the bearing by the leakage magnetic flux in the direction of the outer ring of the bearing. In a conventional motor, the eddy current may brake a bearing, thereby providing resistance to the rotational force of a rotor.

In order to rotate the motor at a high speed, it is necessary to ensure the balance of the rotor with high accuracy. Generally, the operation of balancing the rotor is performed by attaching a balancing member to the shaft and then cutting the balancing member to reduce the weight of the balancing member. However, in the conventional motor, since the cutting tool needs to be carefully operated when the distance between the magnet and the balancer member in the axial direction is close to each other, the machining for reducing the mass of the balancer member attached to the rotor is not easy.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a motor capable of realizing high-speed rotation. Means for solving the problems

In order to achieve the above object, a motor according to the present invention includes: a shaft; at least 2 bearings for supporting the shaft; a magnet which is supported by the shaft between at least 2 bearings; a stator surrounding the magnet; and a magnetic member disposed between the magnet and at least 1 of the bearings in a longitudinal direction of the shaft, the magnetic member having an outer diameter larger than an outer diameter of the magnet.

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

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

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.

An electric motor according to an aspect of the present invention includes: a rotor including a shaft and a magnet, and the magnetic member is a balance member of the rotor.

In the 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 concave portion, a hole portion, or a convex portion.

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

In the motor according to one aspect of the present invention, the plurality of bearings includes 2 bearings, and the magnetic members are provided in the plurality of bearings, respectively.

According to the motor of the present invention, high-speed rotation can be achieved.

Drawings

Fig. 1 is a perspective view schematically showing a structure of a motor according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view of the motor shown in fig. 1 along an axis.

Fig. 3 is a plan view schematically showing the configuration of a balance member of the motor shown in fig. 1.

Fig. 4 is a sectional view schematically showing the configuration of a balance member of the motor shown in fig. 1.

Fig. 5 is a cross-sectional view schematically showing a modification of the balancer member of the motor shown in fig. 1.

Fig. 6 is a cross-sectional view of the motor shown in fig. 1 along an axis, and is a view for explaining the size and arrangement of a shaft, a bearing, and a balance member.

Fig. 7 is a table showing a relationship between a mechanical load and a distance from a magnet to a bearing with respect to a gap in the motor shown in fig. 1.

Fig. 8 is a graph showing a relationship between a mechanical load and a distance from a magnet to a bearing with respect to a gap in the motor shown in fig. 1.

Fig. 9 is a table 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 shown in fig. 1 to the torque of the motor not including the balance member in the motor shown in fig. 1.

Fig. 10 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 in fig. 1.

Detailed Description

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

Integral construction of electric motors

The overall structure of the motor according to one embodiment of the present invention will be described.

Fig. 1 is a perspective view schematically showing the structure of a motor 10 according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of the motor 10 along the axis x.

For convenience of explanation, a direction perpendicular to the axis x direction shown in fig. 1 (hereinafter, also referred to as a "radial direction") is referred to as a front surface of the motor 10. For convenience of explanation, the arrow a direction is referred to as an upper side a and the arrow b direction is referred to as a lower side b in the axis x direction shown in fig. 2. In the radial direction, a direction away from the axis x (the direction of arrow c in fig. 2) is referred to as an outer peripheral side c, and a direction toward the axis x (the direction of arrow d in fig. 2) is referred to as an inner peripheral side d.

The motor 10 includes: a shaft 2; at least 2 bearings for supporting the shaft 2, i.e., a bearing 4a and a bearing 4 b; a magnet 3 supported by the shaft 2 and rotating together with the shaft 2; and a stator 5 surrounding the magnet 3. The motor 10 includes a balancer member 6a and a balancer member 6b as magnetic members, which are disposed between the magnet 3 and at least 1 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 that of the magnet 3. The structure of the motor 10 will be specifically described below.

The housing 1 defines a schematic shape of the motor 10 and houses the components of the motor 10. The housing 1 includes: a housing body 11 formed in a hollow cylindrical shape with upper and lower lid portions open; an upper cover 12 attached to a cover on an upper side (one end side) a of the housing main body 11; and a lower cover 13 attached to the cover on the lower side (the other end side) b of the housing body 11.

The upper cover portion 12 has a substantially circular disk shape corresponding to the shape of the cover surface of the case body 11 so as to seal the case body 11 from the upper side a. Further, 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 13 has a substantially circular disk shape corresponding to the shape of the cover surface of the case body 11 so as to seal the case body 11 from the lower side b. Further, 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.

The shaft 2 is, for example, a circular rod member having an axis x direction as a longitudinal direction, which is an extending direction (longitudinal direction). The shaft 2 rotates about the axis x direction. The shaft 2 is supported in bearing holding holes 12a, 13a of the housing 1 via bearings 4a, 4 b. The tip end (one end) of the shaft 2 is exposed to the outside of the housing 1 from the bearing holding holes 12a and 13a of the housing 1. A portion (the other end portion) of the distal end portion of the shaft 2 exposed in the direction of the lower side b serves as an output shaft, and transmits the rotational force generated by the motor 10 to the outside.

The magnet 3 has a cylindrical shape, for example. The magnet 3 has a longitudinal direction in the x-axis direction, and a shaft through hole 31, which is a through hole penetrating the center of the magnet 3, is provided. 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 form a rotor 7 in the motor 10.

The bearing 4a is attached to the upper cover 12 on the upper side a of the housing 1. The bearing 4b is attached to the lower cover 13 on the lower side b of the housing 1. The bearings 4a and 4b are ball bearings, for example. In the present invention, the type of the bearing is not particularly limited. The bearings 4a and 4b are constituted by, for example, inner rings 41a and 41b and outer rings 42a and 42b arranged so that the axis x direction is the central axis, and rolling elements 43a and 43b provided between the inner rings 41a and 41b and the outer rings 42a and 42 b. The bearings 4a and 4b support the shaft 2 by the inner circumferential surfaces 44a and 44b of the inner rings 41a and 41 b.

The bearings 4a, 4b rotatably support the shaft 2 at arbitrary positions in the axis x direction of the shaft 2. Specifically, the bearing 4a rotatably supports a portion of the upper side a in the axis x direction of the shaft 2 by inserting the shaft 2 into the inner peripheral surface 44 a. The bearing 4b rotatably supports a portion of the lower side b in the axis x direction of the shaft 2 by inserting the shaft 2 into the inner peripheral surface 44 b. 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 made of a metal having magnetism, and are generally formed of an alloy containing iron. The bearings 4a and 4b have outer rings 42a and 42b having outer diameters larger than the outer diameter of the magnet 3 in the radial direction. That is, the bearings 4a and 4b are arranged radially, and the outer rings 42a and 42b are arranged outside the outer periphery of the magnet 3.

The stator 5 is held on the inner peripheral surface of the housing main body 11. Specifically, the stator 5 is disposed inside the housing body 11 at a position corresponding to the magnet 3 in the x-axis direction (longitudinal direction of the shaft 2) and at a position farther from the shaft 2 than the magnet 3 in the radial direction. The stator 5 is configured by a stator core formed in a ring shape so as to surround the magnet 3, a coil wound around an extension portion extending from the stator core to the inner peripheral side d, and an insulator insulating 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. A gap AG is provided between the inner peripheral surface of the stator core and the outer peripheral surface of the magnet 3.

The shapes of the shaft 2, the magnet 3, the bearings 4a and 4b, and the stator 5 are not limited to the above examples as long as they are shapes that can realize the rotational motion of the rotor 7 in the motor 10.

The balance member 6a is disposed between the magnet 3 and the bearing 4a in the axis x direction of the shaft 2. The balance member 6b is disposed between the magnet 3 and the bearing 4b in the axis x direction of the shaft 2. The balance members 6a and 6b have through holes 61a and 61b penetrating through the centers thereof in the longitudinal direction of the axis x. The balance members 6a, 6b are provided corresponding to the number of bearings 4a, 4b, for example. The balance members 6a and 6b rotate about the axis x direction together with the rotor 7, that is, the shaft 2 and the magnet 3. The balancer members 6a and 6b function as balancers that prevent eccentric motion of the rotor 7 when rotating about the axis x direction.

The balance members 6a and 6b are formed of a magnetic member having a relatively high specific gravity, such as an Fe — Cu sintered member. That is, the balance members 6a and 6b function as paths through which magnetic fluxes pass.

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 structure of the balance members 6a and 6b of the motor 10. As shown in fig. 3 and 4, the balance members 6a and 6b have the through holes 61a and 61b and the holes 63a and 63b penetrating in the axis x direction in the surface portions 62a and 62 b. The holes 63a and 63b function as mass adjusting portions for eliminating eccentricity when the balancing members 6a and 6b rotate together with the rotor 7.

The holes 63a and 63b are formed by cutting the surface portions 62a and 62b of the balance members 6a and 6b from one of the upper side a and the lower side b to the other side using a cutting tool such as a drill. The surface portions 62a and 62b form surfaces facing the bearings 4a and 4b in the axis x direction of the shaft 2. After the balance members 6a and 6b are attached to the shaft 2 together with the magnet 3, the holes 63a and 63b can be provided at predetermined positions in the face portions 62a and 62 b. The positions of the holes 63a and 63b formed in the surface portions 62a and 62b are determined in order to cancel the eccentric motion during the rotation of the rotor 7, and in consideration of the balance of the center of gravity in the radial direction of the rotor 7.

In the above description, the holes 63a and 63b penetrating in the axis x direction of the balance members 6a and 6b have been described as an example of the mass adjuster in the present invention, but the shape of the mass adjuster and the position of the mass adjuster in the face portions 62a and 62b are not limited to the above examples. Fig. 5 is a cross-sectional view schematically showing a modification of the balancer members 6a and 6b of the motor 20. As shown in fig. 5, the mass adjuster may be, for example, concave portions 64a and 64b (see fig. 5 a) or convex portions 65a and 65b (see fig. 5 b) formed on the surfaces of the balance members 6a and 6b facing the upper side a or the lower side b, instead of the through holes such as the holes 63a and 63b shown in fig. 3 and 4. Further, the shape of the hole is not limited to the above-described example for the mass adjuster.

[ sizes and arrangements of magnets, bearings, and balance members ]

Next, dimensions and arrangements of the magnet 3, the bearings 4a and 4b, and the 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 of fig. 1 taken along the axis x direction, and is a schematic diagram for explaining the dimensions and arrangement of the magnet 3, the bearings 4a and 4b, and the balance members 6a and 6 b.

As shown in fig. 6, the balancer member 6a is disposed between the magnet 3 and the bearing 4a in the axis x direction of the shaft 2. Further, the balance member 6b is disposed between the magnet 3 and the bearing 4b in the axis x direction of the shaft 2.

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 4 a. 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 equation (1).

DM＜DB1＜DR1 (1)

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 4 b. 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 equation (2).

DM＜DB2＜DR2 (2)

The dimensions of the outer diameter DB1 and the outer diameter DB2 may be the same or different values as long as the relationship between the above expressions (1) and (2) is maintained. Similarly, the dimensions of the outer diameters DR1 and DR2 may be the same or different values as long as the relationship between the above equations (1) and (2) is maintained.

Since the balance members 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 variation in the magnetic flux density from the magnet 3 passing through the bearings 4a and 4b, and to prevent the generation of eddy currents in the outer rings 42a and 42b of the bearings 4a and 4 b. In particular, the balance members 6a and 6b can prevent magnetic fluxes from the magnet 3 toward the magnetic members other than the stator 5, that is, leakage magnetic fluxes from the bearings 4a and 4b, by having the outer diameters DB1 and DB2 have the relationships of the above-described equations (1) and (2). That is, the balance members 6a and 6b can prevent the braking force from being applied to the shaft 2 via the magnet 3 by the magnetic force generated by the eddy current generated in the outer rings 42a and 42b of the bearings 4a and 4 b.

Further, 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) becomes long, the vibration of the rotor 7 becomes large due to the centrifugal force generated by the rotational motion. Therefore, in the motor 10, in order to realize high-speed rotation of the motor, it is effective to reduce leakage magnetic flux entering the bearings 4a and 4b by the balance members 6a and 6b formed of the magnetic members described above, and to prevent vibration of the motor 10 due to centrifugal force.

The balance member 6a is spaced a prescribed distance a1 from the bearing 4a in the axis x direction of the shaft 2. The balance member 6a is spaced apart from the magnet 3 by a predetermined distance B1 in the direction of the axis x of the shaft 2. The balance member 6b is spaced a prescribed distance a2 from the bearing 4b in the axis x direction of the shaft 2. The balance member 6B is spaced apart from the magnet 3 by a predetermined distance B2 in the axis x direction of the shaft 2.

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 axis x direction of the shaft 2. The relationship between the distance a1 between the balancer member 6a and the bearing 4a and the distance B1 between the balancer member 6a and the magnet 3 is expressed by the following equation (3).

A1＜B1 (3)

Further, 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 axis x direction of the shaft 2. The relationship between the distance a2 between the balancer member 6B and the bearing 4B and the distance B2 between the balancer member 6B and the magnet 3 is expressed by the following equation (4).

A2＜B2 (4)

The distance a1 and the distance a2 may be the same distance or different distances. Likewise, the distance B1 and the distance B2 may be the same distance or different distances.

By disposing the balance members 6a and 6b made of magnetic material in the vicinity of the bearings 4a and 4b with respect to the magnet 3 as described above, it is possible to prevent leakage magnetic flux from the magnet 3 to the bearings 4a and 4b from occurring. That is, by disposing the balance members 6a and 6b in the vicinity of the bearings 4a and 4b with respect to the magnet 3, it is possible to further prevent the bearings 4a and 4b from being braked.

In the motor 10, the distances B1, B2 between the magnet 3 and the balance members 6a, 6B are preferably longer than the gap AG. By making the distances B1 and B2 longer than the air gap AG as described above, the motor 10 can make the magnetic path the way from the magnet 3 to the stator 5, and thus the leakage flux can be reduced to improve the magnetic efficiency. Further, since the distances B1 and B2 are longer than the gap AG, the leakage magnetic flux can be reduced, and the motor 10 can prevent the braking from being applied to the bearing 4a and the bearing 4B by the eddy current.

In the motor 10, as shown in fig. 3, holes 63a and 63b as mass adjusting portions for adjusting the masses of the balance members 6a and 6b to cancel the eccentric motion of the rotor 7 are provided in the surface portions 62a and 62b facing away from each other in the axis x direction of the balance members 6a and 6 b.

When the surface portions 62a and 62b are cut from the axis x direction in order to adjust the mass of the balance members 6a and 6b, if the balance members 6a and 6b contact other members without a gap in the axis x direction, there is a possibility that the other members are cut by mistake. In this case, the diameter and feed amount of the cutting tool need to be precisely controlled so that the cutting tool does not penetrate the balance members 6a and 6 b.

In addition, when it is difficult to cut the surface portions 62a and 62b of the balance members 6a and 6b, it is also conceivable to cut the side surfaces of the balance members 6a and 6b, but it is difficult to cut the side surfaces of the thin flat members, that is, the balance members 6a and 6 b. In this case, cutting chips and the like may fly out from the side surface, which may increase the moment when the shaft 2 rotates and increase the load when the rotor 7 rotates.

In the motor 10, the balancer members 6a and 6B are spaced from the magnet 3 by predetermined distances B1 and B2 and from the bearings 4a and 4B by predetermined distances a1 and a2, respectively, in the direction of the axis x of the shaft 2. Therefore, according to the motor 10, the operation of the cutting tool can be easily performed in the cutting process for adjusting the mass of the balance members 6a and 6b at the time of the balance adjustment. That is, according to the motor 10, the cutting work for adjusting the mass of the balance members 6a and 6b can be easily performed at the time of the balance adjustment.

[ study of the ratio of the distance from the magnet to the balance member to the air gap ]

Referring to fig. 7 to 10, ratios RB1 and RB2 of distances B1 and B2 from the magnet 3 to the balance members 6a and 6B to the gap AG in the motor 10 were examined.

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. In the motor 10, changes in the mechanical load ML caused by changing RB0a and RB0b were examined. The mechanical load is a load generated in the motor when the motor is rotated in a non-energized state. The mechanical load is mainly a frictional load and a magnetic load. The friction load is generated by friction generated between the rolling elements of the bearing and the cage when the motor rotates, friction generated by grease inside the motor, or the like. The magnetic load is generated by an attractive force (cogging) between the magnet and the stator when the motor rotates.

Fig. 7 is a table showing the relationship between the mechanical load ML and the distances from the magnet 3 to the bearings 4a and 4B (a1+ B1+ C1) and (a2+ B2+ C2) in the motor 10 with respect to the ratios RB0a (a1+ B1+ C1/AG) and RB0B (a2+ B2+ C2/AG) of the gap AG. Fig. 8 is a graph showing the relationship between the mechanical load ML and the distances from the magnet 3 to the bearings 4a and 4B (a1+ B1+ C1) and (a2+ B2+ C2) in the motor 10 with respect to the ratios RB0a (a1+ B1+ C1/AG) and RB0B (a2+ B2+ C2/AG) of the air gap AG.

In fig. 7 and 8, the ratios RB0a, RB0b of the distance from the magnet 3 to the bearings 4a, 4b to the gap AG indicate the ratio of the distance from the magnet 3 to the bearings 4a, 4b when the gap AG is set to 1. Further, as shown in fig. 7 and 8, the mechanical load ML in this case was measured by changing the ratios RB0a, RB0b of the distance from the magnet 3 to the bearings 4a, 4b to the gap AG by 1.5, 2.2, 2.8 and 3.5.

As is apparent from fig. 7 and 8, in the motor 10, the mechanical load ML is reduced to a greater extent than before and after when the ratio RB0a, RB0b of the distance from the magnet 3 to the bearings 4a, 4b to the gap AG is between 2.2 and 2.8.

Next, ratios RB1 and RB2 of the distances B1 and B2 to the gap AG in the motor 10 were examined. In the following description, a motor that does not include the balancer members 6a and 6b is referred to as a motor of a reference example. The ratios RB1, RB2 of the distances B1, B2 to the gap AG were investigated based on the mechanical load ML of the motor 10, the mechanical load ML2 of the motor excluding the balance members 6a, 6B, and the ratio TR of the torque of the motor 10 to the torque of the motor excluding the balance members 6a, 6B.

Fig. 9 is a table showing relationships among the distance B1 from the magnet 3 to the balance members 6a, 6B, the ratio RB1(B1/AG) of B2 to the gap AG, the ratio RB2(B2/AG), 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 in the motor 10. Fig. 10 is a graph showing the relationship between the distance B1 from the magnet 3 to the balance members 6a, 6B, the ratio RB1(B1/AG) of B2 to the gap AG, RB2(B2/AG), 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 10. In the motor of the reference example, since the balance members 6a, 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 fig. 9, "-" in the column of the distance indicates the mechanical load ML2 in the motor of the reference example and the ratio TR of the torque of the motor 10 to the torque of the motor of the reference example, which do not include the balance members 6a, 6 b. In the present embodiment, the mechanical load ML is measured between the state (0 in fig. 9) in which the magnet 3 is in contact with the balance members 6a and 6B and the mechanical load ML is measured, with the ratios RB1 and RB2 of the distance B2 to the gap AG.

As is clear from fig. 9 and 10, particularly when the ratios RB1 and RB2 of the distance B2 from the magnet 3 to the balance members 6a and 6B are 1.5 to 2.8, the mechanical load ML of the motor 10 is significantly reduced as compared with the mechanical load ML2 of the motor of the reference example. That is, in the present embodiment, it is found that the efficiency of the motor 10 is improved when the ratio RB1, RB2 of the distance from the magnet 3 to the balance members 6a, 6b to the gap AG is between 1.5 and 2.8 as compared to before and after the ratio.

As is apparent from fig. 9 and 10, in the motor 10, in a region where the ratio RB1, RB2 of the distance from the magnet 3 to the balance members 6a, 6b to the gap AG is 1.5 or more, the ratio TR of the torque of the motor 10 to the motor of the reference example is 1.0 or more. That is, it is found that the motor 10 generates a larger torque than the motor of the reference example in the region where the ratio RB1, RB2 of the distance from the magnet 3 to the balance members 6a, 6b to the gap AG is 1.5 or more.

As can be seen from fig. 7 to 10, when the ratio RB1, RB2 of the distance from the magnet 3 to the balance members 6a, 6b to the gap AG in the motor 10 is between 1.5 and 2.8, the mechanical load ML decreases, and a larger torque is generated than in the motor of the reference example. Therefore, it can be said that in the motor 10, it is preferable to set the ratios RB1, RB2 of the distance from the magnet 3 to the balance members 6a, 6b to the gap AG to be 1.5 to 2.8.

As described above, the motor 10 can realize high-speed rotation.

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, and includes all the embodiments included in the concept of the present invention and the claims. Further, at least a part of the above-described problems and effects can be exhibited by appropriately and selectively combining the respective configurations. For example, the shape, material, arrangement, size, and the like of each component in the above embodiments can be appropriately changed according to a specific use mode of the present invention.

Description of the reference symbols

1, a shell; 2, a shaft; 3, a magnet; 4a bearing; 4b a bearing; 5a stator; 6a balance member; 6b a balance member; 7, a rotor; 10 an electric motor; 11 a housing body; 12 an upper cover part; 13a lower cover part; a 31-axis through hole; 41a inner ring; 41b inner ring; 42a outer ring; 42b an outer ring; 43a rolling body; 43b rolling elements; 44a inner peripheral surface; 44b an inner peripheral surface; 61a through holes; 61b through holes; 62a face; 62b a face; 63a hole part; 63b hole parts; 64a recess; 64b a recess; 65a convex part; 65b convex part