Magnetic bearing structure

Abstract

To provide a bearing structure that facilitates positioning in a rotation axis direction.SOLUTION: A magnetic bearing structure comprises a shaft that rotates with a stretching direction as a rotation axis, an inner ring connected to the shaft, and an outer ring provided on the outer periphery of the inner ring. The inner ring and the outer ring are each composed of a bond magnet, and are provided so that the same poles face each other. In a cross-section in a rotation axis direction, one of the outer ring and the inner ring has a recess that houses the other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a magnetic bearing structure. [Background technology]

[0002] There is a technology for providing magnets as a bearing structure for a motor. For example, Patent Document 1 describes a configuration in which two or more ring-shaped permanent magnets are provided on a shaft, and the permanent magnets are arranged so as to face two or more ring-shaped permanent magnets provided on the bearing side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-217744 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology described in Patent Document 1, the task of positioning the permanent magnet provided on the shaft and the permanent magnet provided on the bearing side so that they face each other in the direction of the rotation axis of the shaft is cumbersome. Therefore, a bearing structure that allows easy positioning in the direction of the rotation axis has been desired. [Means for solving the problem]

[0005] The present disclosure has been made to solve the above-mentioned problems, and can be realized in the following forms. According to one embodiment of the present disclosure, there is provided a magnetic bearing structure. The magnetic bearing structure includes a shaft that rotates about a rotation axis in a direction of extension, an inner ring joined to the shaft, and an outer ring provided on the outer periphery of the inner ring. The inner ring and the outer ring are each composed of a bonded magnet, and are provided so that the same poles face each other, and in a cross section including the rotating shaft, one of the outer ring and the inner ring has a recess that accommodates the other. The outer ring has the recess and a second protruding portion. The second protruding portion is provided in the outer ring at a position in the recess that is the furthest from the rotating shaft, and protrudes so as to be in contact with the inner ring.

[0006] (1) According to one embodiment of the present disclosure, there is provided a rotor with a magnetic bearing structure. The magnetic bearing structure includes a shaft that rotates with the extension direction as its axis of rotation, an inner ring bonded to the shaft, and an outer ring provided on the outer periphery of the inner ring. The inner ring and the outer ring are each composed of a bonded magnet, and are provided so that the same poles face each other, and in a cross section in the direction of the rotation axis, one of the outer ring and the inner ring has a recess that accommodates the other. According to this form of magnetic receiving structure, the inner ring and the outer ring are made of bonded magnets, and therefore can be elastically deformed. Therefore, the outer ring and the inner ring can be assembled so that the inner ring is housed in the recess of the outer ring, or the outer ring is housed in the recess of the inner ring. Also, it is possible to prevent the inner ring from significantly deviating from a predetermined range relative to the outer ring in the axial direction. Therefore, it is easy to position the shaft in the axial direction. (2) In the magnetic bearing structure of the above embodiment, the inner ring has a first protrusion, the outer ring has the recess, and the first protrusion is provided at a position opposite to a position in the recess that is farthest from the rotating shaft, and may protrude so as to contact the outer ring. In this embodiment, the first protruding portion can prevent fluid present on one side of the inner ring from leaking out to the other side through the gap between the outer ring and the inner ring. (3) In the magnetic bearing structure of the above embodiment, the outer ring may have the recess and a second protrusion, and the second protrusion may be provided at a position in the recess that is farthest from the rotating shaft and protrude so as to contact the inner ring. In this embodiment, the second protruding portion can prevent fluid present on one side of the inner ring from leaking out to the other side through the gap between the outer ring and the inner ring. (4) In the magnetic bearing structure of the above embodiment, the inner ring has the recess, and the outer ring has a third protrusion, which is provided at a position opposite to a position in the recess that is the shortest distance from the rotating shaft, and which protrudes so as to contact the inner ring. In this embodiment, the third protrusion can prevent fluid present on one side of the inner ring from leaking through the gap between the outer ring and the inner ring to the other side. Furthermore, due to centrifugal force, fluid is more likely to accumulate in the larger diameter part of the inner edge of the outer ring than in the smaller diameter part of the inner edge of the outer ring. Because the inner ring has a recess, even if fluid flows from the outside into the gap between the outer ring and the inner ring, it is scattered in the direction opposite to the flow of the fluid, thereby further preventing the fluid from leaking out. (5) In the magnetic bearing structure of the above embodiment, the inner ring may have the recess and a fourth protrusion, and the fourth protrusion may be provided at a position in the recess that is the shortest distance from the rotating shaft and may protrude so as to contact the outer ring. In this embodiment, the fourth protrusion can prevent fluid present on one side of the inner ring from leaking through the gap between the outer ring and the inner ring to the other side. Furthermore, due to centrifugal force, fluid is more likely to accumulate in the larger diameter part of the inner edge of the outer ring than in the smaller diameter part of the inner edge of the outer ring. Because the inner ring has a recess, even if fluid flows from the outside into the gap between the outer ring and the inner ring, it will be scattered in the opposite direction to the flow of the fluid, further preventing the fluid from leaking out.

[0007] The present disclosure can be realized in various forms, for example, in the form of a rotor including the magnetic bearing structure of the present embodiment, a manufacturing method of a rotor, and the like. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a portion of a rotor having a magnetic bearing structure. [Diagram 2] FIG. 11 is a schematic diagram showing a schematic configuration of a part of a rotor in a second embodiment. [Diagram 3] FIG. 11 is a schematic diagram showing a schematic configuration of a part of a rotor in a third embodiment. [Figure 4] FIG. 13 is a schematic diagram showing a schematic configuration of a part of a rotor in a fourth embodiment. [Diagram 5]FIG. 13 is a schematic diagram showing a schematic configuration of a portion of a rotor in a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A. First embodiment: FIG. 1 is a schematic diagram showing a schematic configuration of a part of a rotor 100 having a magnetic bearing structure according to an embodiment of the present disclosure. FIG. 1 is a cross-sectional view of the rotor 100 in a plane including a rotation axis Ax described later. FIG. 1 shows an x-axis, a y-axis, and a z-axis that are perpendicular to each other. The x-axis is in the direction of the rotation axis Ax. These axes correspond to the axes shown in FIG. 1 and subsequent figures. The rotor 100 includes a shaft 10, an inner ring 20, and an outer ring 30. The rotor 100 is, for example, a rotating body included in a motor.

[0010] The shaft 10 rotates about a rotation axis Ax in the extension direction. The shaft 10 is, for example, a substantially cylindrical member.

[0011] The inner ring 20 is a member joined to the shaft 10. The inner ring 20 rotates with the rotation of the shaft 10. The inner ring 20 is composed of a bonded magnet. The inner ring 20 has a lower elastic modulus than the shaft 10. In this embodiment, the inner ring 20 has a first convex portion 21. As shown in FIG. 1, the first convex portion 21 has a substantially triangular shape that inclines toward the apex so as to move away from the rotation axis Ax as the coordinate value in the +x-axis direction increases, and then inclines from the apex so as to move toward the rotation axis Ax.

[0012] The outer ring 30 is provided on the outer periphery of the inner ring 20. In this embodiment, the outer ring 30 is supported by a support provided on the outside of the outer ring 30 and rotates around the rotation axis Ax. The outer ring 30 is made of a bonded magnet. The outer ring 30 has a lower elastic modulus than the shaft 10. The outer ring 30 may be made of the same bonded magnet as the inner ring 20, or may be made of a bonded magnet having a higher elastic modulus than the inner ring 20. In this embodiment, the outer ring 30 has a first recess 31 that accommodates the first protrusion 21. As shown in FIG. 1, the first recess 31 forms a substantially triangular space that inclines toward the apex so as to move away from the rotation axis Ax as the coordinate value in the +x-axis direction increases, and then inclines from the apex so as to move toward the rotation axis Ax.

[0013] In a cross-sectional view taken along a plane including the rotation axis Ax, the maximum distance from the rotation axis Ax to the outer contour of the inner ring 20 housed in the first recess 31 is greater than the minimum distance from the rotation axis Ax to the outer contour of the first recess 31. Thus, the inner ring 20 can be prevented from significantly deviating from a predetermined range in the direction of the rotation axis Ax.

[0014] The inner ring 20 and the outer ring 30 are formed with oriented magnetization, for example, by injection molding using a mold in which a magnetic field is formed. The inner ring 20 and the outer ring 30 may be magnetized after being formed. The magnetic force at each position of the inner ring 20 and the magnetic force at each position of the outer ring 30 are approximately the same. Furthermore, the inner ring 20 and the outer ring 30 are symmetrical about the rotation axis Ax and about a plane perpendicular to the rotation axis Ax. Therefore, during the rotation of the rotor 100, the magnetic force is symmetrical about the rotation axis Ax and about a plane perpendicular to the rotation axis Ax.

[0015] The inner ring 20 and the outer ring 30 are provided so that the same magnetic poles face each other. For example, when viewed along the direction of the rotation axis Ax, the inner circumference side of the inner ring 20 has an N pole, and the outer circumference side of the inner ring 20 has an S pole. When viewed along the direction of the rotation axis Ax, the inner circumference side of the outer ring 30 has an S pole, and the outer circumference side of the outer ring 30 has an N pole.

[0016] According to the magnetic receiving structure of the rotor 100 of this embodiment described above, the inner ring 20 and the outer ring 30 are made of bonded magnets and can be elastically deformed. Therefore, the inner ring 20 can be assembled so as to be housed in the first recess 31 of the outer ring 30. Also, it is possible to prevent the inner ring 20 from significantly deviating from a predetermined range in the direction of the rotation axis Ax. Therefore, it is easy to position the shaft 10 in the direction of the rotation axis Ax.

[0017] B. Second embodiment: 2 is a schematic diagram showing a schematic configuration of a rotor 100B equipped with a magnetic bearing structure in the second embodiment. The magnetic bearing structure in the second embodiment differs from the magnetic bearing structure in the first embodiment in that an inner ring 20B has a protrusion 40, and other configurations are the same as those in the first embodiment.

[0018] The protruding portion 40 is provided at a position on the inner ring 20B facing the position at which the first recess 31 is most distant from the rotation axis Ax, and is a portion that protrudes so as to contact the outer ring 30B. In the present application, the protruding portion 40 protrudes so as to contact the position at which the first recess 31 is most distant from the rotation axis Ax. The protruding portion 40 is formed, for example, from a bonded magnet, and is formed together with the inner ring 20B by the mold that forms the inner ring 20B.

[0019] When the rotor 100B is used in a reducer, it is required that the lubricating grease Gr injected for gear lubrication not leak to the outside. In FIG. 2, the lubricating grease Gr is provided on the +y axis direction side of the rotor 100B, and the protruding portion 40 suppresses the lubricating grease Gr from leaking to the -y axis direction side of the rotor 100B. The lubricating grease Gr that has entered between the inner ring 20B and the outer ring 30B from the +y axis direction side of the rotor 100B moves along the outer ring 30B to a position in the first recess 31 that is the largest distance from the rotation axis Ax by the centrifugal force caused by the rotation of the rotor 100B. Since the protruding portion 40 is provided at a position facing the position in the first recess 31 in the inner ring 20B that is the largest distance from the rotation axis Ax, the lubricating grease Gr remains at the position in the first recess 31 that is the largest distance from the rotation axis Ax. That is, the protruding portion 40 can suppress the lubricating grease Gr from leaking to the -y axis direction side of the rotor 100B.

[0020] According to the magnetic bearing structure provided in the rotor 100B of this embodiment described above, when a magnetic bearing is used in a reducer, the protrusion 40 can prevent the lubricating grease Gr injected for gear lubrication from leaking out from the gap between the outer ring 30B and the inner ring 20B.

[0021] C. Third embodiment: 3 is a schematic diagram showing a schematic configuration of a rotor 100C equipped with a magnetic bearing structure according to the third embodiment. The magnetic bearing structure according to the third embodiment differs from the magnetic bearing structure according to the first embodiment in that the inner ring 20 has a second recess 22C and the outer ring 30 has a protrusion 40C, but the other configurations are the same as those of the first embodiment.

[0022] The outer ring 30C has a second protrusion 32C and a protrusion 40C. The second protrusion 32C has a substantially triangular shape that inclines toward the apex so as to approach the rotation axis Ax and inclines away from the apex to the rotation axis Ax as the coordinate value in the +x-axis direction increases. A detailed description of the protrusion 40C will be given later.

[0023] The inner ring 20C has a second recess 22C that houses the second protrusion 32C. The second recess 22C forms a substantially triangular space that inclines toward the apex so as to approach the rotation axis Ax and inclines from the apex so as to move away from the rotation axis Ax as the coordinate value in the +x-axis direction increases.

[0024] In the outer ring 30C accommodated in the second recess 22C, the smallest distance from the rotation axis Ax to the outer ring 30C is smaller than the largest distance from the rotation axis Ax to the second recess 22C. Therefore, it is possible to prevent the inner ring 20 from significantly deviating from a predetermined range in the direction of the rotation axis Ax.

[0025] The protrusion 40C is provided at a position facing the position of the second recess 22C in the outer ring 30C that is the farthest from the rotation axis Ax, and is a portion that protrudes so as to contact the inner ring 20C. In the present application, the protrusion 40C protrudes so as to contact the apex of the second recess 22C, which is the position of the second recess 22C that is the farthest from the rotation axis Ax. The protrusion 40C is formed, for example, from a bonded magnet, and is formed together with the outer ring 30C by the mold that forms the outer ring 30C.

[0026] In FIG. 3, the lubricating grease Gr is provided on the +y-axis direction side of the rotor 100C. The lubricating grease Gr that has entered between the inner ring 20C and the outer ring 30C from the +y-axis direction side of the rotor 100C returns to the +y-axis direction side of the rotor 100C along the outer ring 30C due to the centrifugal force caused by the rotation of the rotor 100C. In addition, the lubricating grease Gr that has moved to the position at the smallest distance from the rotation axis Ax in the second recess 22C also remains at the position at the smallest distance from the rotation axis Ax in the second recess 22C because the protrusion 40C is provided at a position facing the position at the smallest distance from the rotation axis Ax in the second recess 22C in the outer ring 30C. In other words, the protrusion 40C can suppress the lubricating grease Gr from leaking out to the -y-axis direction side of the rotor 100C.

[0027] According to the magnetic bearing structure of the rotor 100 of the present embodiment described above, for example, when a magnetic bearing is used in a reducer, the lubricating grease Gr injected for gear lubrication can be prevented from leaking out by the protrusion 40C. In addition, the lubricating grease Gr is more likely to accumulate in the large diameter part of the inner edge of the outer ring 30C due to centrifugal force than in the small diameter part of the inner edge of the outer ring 30C. Since the outer ring 30C has a protrusion, even if the lubricating grease Gr flows from the outside into the gap between the outer ring 30C and the inner ring 20C, it is scattered in the opposite direction to the flow-in direction of the lubricating grease Gr, so that the lubricating grease Gr can be more effectively prevented from leaking out.

[0028] D. Fourth embodiment: 4 is a schematic diagram showing a schematic configuration of a rotor 100D equipped with a magnetic bearing structure according to a fourth embodiment. The magnetic bearing structure according to the fourth embodiment is different from the magnetic bearing structure according to the first embodiment in that the space formed by the first protruding portion 21D of the inner ring 20D and the first recessed portion 31D of the outer ring 30D is not substantially triangular, but the other configurations are the same as those of the first embodiment. This fourth embodiment also has substantially the same effects as the first embodiment.

[0029] E. Fifth embodiment: 5 is a schematic diagram showing a schematic configuration of a rotor 100E equipped with a magnetic bearing structure according to a fifth embodiment. The magnetic bearing structure according to the fifth embodiment is different from the magnetic bearing structure according to the first embodiment in that the outer ring 30E is not inclined and is not symmetrical with respect to a plane perpendicular to the rotation axis Ax, and the inner ring 20E does not have a first protrusion 21. The other configurations are the same as those of the first embodiment. The fifth embodiment also has almost the same effects as the first embodiment.

[0030] The first recesses 31E of the outer ring 30E are all spaced the same distance from the rotation axis Ax, that is, the first recesses 31E do not have an inclination.

[0031] In the outer ring 30E, the distance from the rotation axis Ax of the outer wall forming the first recess 31E on the -x-axis direction side of the first recess 31E is greater than the distance from the rotation axis Ax of the outer wall forming the first recess 31E on the +axis direction side of the first recess 31E. The inner ring 20E and the outer ring 30E are magnetized such that, during rotation of the rotor 100, the magnetic force is symmetrical about the rotation axis Ax and is symmetrical about a plane perpendicular to the rotation axis Ax.

[0032] F. Other Embodiments: (F1) In the above-described embodiment, the inner ring 20 and the outer ring 30 rotate about the rotation axis Ax. However, this is not limiting, and only the inner ring 20 may rotate about the rotation axis Ax.

[0033] (F2) In the above-described embodiment, the first recess 31 accommodates the entire inner ring 20. This is not limiting, and the first recess 31 may accommodate only a portion of the inner ring 20.

[0034] (F3) In the second embodiment described above, the inner ring 20B has one protrusion 40. This is not limiting, and the inner ring 20B may have a plurality of protrusions 40. The protrusions 40 are preferably provided so that, during rotation of the rotor 100B, the magnetic force is symmetrical about the rotation axis Ax, and the magnetic force is symmetrical about a plane perpendicular to the rotation axis Ax.

[0035] (F4) In the second embodiment described above, the inner ring 20B has a protruding portion 40. Instead of this, the outer ring 30B may have a protruding portion 40. The protruding portion 40 of the outer ring 30B is preferably provided at a position in the first recess 31 that is farthest from the rotation axis Ax, and protrudes so as to contact the apex of the first convex portion 21 of the inner ring 20B. Also, the inner ring 20B and the outer ring 30B may each have a protruding portion. In this case, it is preferable that the protruding portion is provided so that the magnetic force is symmetrical about the rotation axis Ax and is symmetrical about a plane perpendicular to the rotation axis Ax during rotation of the rotor 100B.

[0036] (F5) In the second embodiment described above, the protrusion 40 is provided at a position on the inner ring 20B facing the position at which the first recess 31 is the longest from the rotation axis Ax, and protrudes so as to be in contact with the position at which the first recess 31 is the longest from the rotation axis Ax. Not limited to this, the protrusion 40 may be provided at any position on the inner ring 20B. Also, the protrusion 40 may protrude so as to be in contact with the outer ring 30B, and may protrude so as to be in contact with a position different from the position at which the first recess 31 is the longest from the rotation axis Ax. It is preferable that the protrusion 40 is provided so that the magnetic force is symmetrical about the rotation axis Ax and is symmetrical about a plane perpendicular to the rotation axis Ax during rotation of the rotor 100B.

[0037] (F6) In the third embodiment described above, the outer ring 30C has a protruding portion 40C. Instead of this, the inner ring 20C may have a protruding portion 40C. It is preferable that the protruding portion 40C of the inner ring 20C is provided at a position in the second recess 22C where the distance from the rotation axis Ax is the smallest, and protrudes so as to contact the apex of the second convex portion 32C of the outer ring 30C. In addition, the outer ring 30C and the inner ring 20C may each have a protruding portion. In this case, it is preferable that the protruding portion is provided so that the magnetic force is symmetrical about the rotation axis Ax and is symmetrical about a plane perpendicular to the rotation axis Ax during rotation of the rotor 100C.

[0038] (F7) In the third embodiment described above, the protrusion 40C is provided at a position on the outer ring 30C that faces the position at which the distance from the rotation axis Ax in the second recess 22C is the smallest, and protrudes so as to contact the position at which the distance from the rotation axis Ax in the second recess 22 is the smallest. Not limited to this, the protrusion 40C may be provided at any position on the outer ring 30C. Also, the protrusion 40C may protrude so as to contact a position different from the position at which the distance from the rotation axis Ax in the second recess 22 is the smallest as long as it protrudes so as to contact the inner ring 20C. It is preferable that the protrusion 40C is provided so that the magnetic force is symmetrical about the rotation axis Ax and is symmetrical about a plane perpendicular to the rotation axis Ax during the rotation of the rotor 100C.

[0039] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be appropriately replaced or combined in order to solve the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0040] 10...shaft, 20, 20B, 20C, 20D, 20E...inner ring, 21, 21D, 21E...first convex portion, 22C...second concave portion, 30, 30B, 30C, 30D, 30E...outer ring, 31, 31D, 31E...first concave portion, 32C...second convex portion, 40, 40C...protruding portion, 100, 100B, 100C, 100D, 100E...rotor

Claims

1. A magnetic bearing structure, A shaft that rotates around the extension direction as a rotation axis; an inner ring joined to the shaft; an outer ring provided on an outer periphery of the inner ring, The inner ring and the outer ring are each formed of a bonded magnet, and are provided so that the same poles face each other, In a cross section including the rotation axis, one of the outer ring and the inner ring has a recess that accommodates the other of the outer ring and the inner ring, the outer ring has the recess and a second protrusion, A magnetic bearing structure, wherein the second protrusion is provided on the outer ring at a position in the recess that is the farthest from the rotation shaft and protrudes so as to contact the inner ring.

2. A magnetic bearing structure, A shaft that rotates around the extension direction as a rotation axis; an inner ring joined to the shaft; an outer ring provided on an outer periphery of the inner ring, The inner ring and the outer ring are each formed of a bonded magnet, and are provided so that the same poles face each other, In a cross section including the rotation axis, one of the outer ring and the inner ring has a recess that accommodates the other of the outer ring and the inner ring, The inner ring has the recess and a fourth protrusion, A magnetic bearing structure, wherein the fourth protrusion is provided at a position on the inner ring where the distance from the rotation shaft to the recess is the smallest, and protrudes so as to contact the outer ring.

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