JP3083886U - Rotor pivot structure - Google Patents

Abstract

(57) Abstract: A rotor has a relatively small contact area with a support member when a rotating shaft of a rotor does not rotate, and at the moment when the rotating shaft starts to rotate, a relatively stable rotation is immediately obtained. The present invention provides a rotor pivoting structure capable of extending the life by stable rotation of the rotor and reducing noise. SOLUTION: A first support member, a second support member, a support member and a fixing member fixed in a fixed position are fixedly provided inside a metal shaft tube, and a through hole is provided in the first support member and the second support member. Is drilled, and a flange is projected from the peripheral wall of the through hole,
A support portion is formed in the support member, a through hole is formed in the fixing member, and the rotation shaft of the rotor passes through the through holes of the first support member and the second support member from one end thereof, and an end face of the rotation shaft. Can be in contact with the support portion of the support member, the locking groove recessed in the rotation shaft can be locked with the fixed member, the rotation shaft and the first support member, the flange of the second support member It is configured to have a minimum gap or a small contact.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a structure for pivotally attaching a rotor, and in particular, a rotating shaft of the rotor and a support member for supporting the rotation of the rotor have a minimum contact area, and the rotor rotates stably and without bias. The present invention relates to a rotor pivoting structure that can be used.

[0002]

[Prior art]

 Conventionally, this type is as follows.

[0003] In Japanese Patent Application No. 2001-1275 filed in Japan by the applicant of the present invention, one end of a metal shaft tube is fixed to a base, and a support tube is provided inside the metal shaft tube. A support member and a fixed member fixed at a fixed position are fixedly provided. The support tube has a flange protruding from the peripheral wall of the through hole, a support member is formed in the support member, and a through hole is formed in the fixed member so as to be opened and closed. A rotating shaft is vertically provided at the center of the rotor, and a locking groove is formed in the rotating shaft. The rotating shaft of the rotor passes through the through hole of the support tube from one end thereof, and the end surface of the rotating shaft is a support member. Can be brought into contact with the supporting portion. The locking groove recessed in the rotating shaft can be locked with the fixing member, and the rotating shaft and the flange of the support pipe are configured so as to have a minimum clearance or to make a slight contact.

[0004] Further, in Japanese Utility Model Application No. 2001-3204 filed in Japan by the applicant of the present invention, a structure in which a fixing member is fitted inside a shaft tube is disclosed. A support member is fitted to the bottom of the shaft tube. The support member is used for abutting one end face of a rotating shaft of the motor, and a buckle groove for engaging with a fixing member is formed in the rotating shaft, and an auxiliary pivoting portion is fitted. The auxiliary pivot portion is configured to have a minimum gap with the inner peripheral wall of the shaft tube.

[0005]

In the above-described conventional rotor pivoting structure, a main technique and a flange 222 are protruded from the support tube 22, and a minimum gap is provided between the flange 222 and the rotating shaft 31. It is configured to make contact between or slightly. An auxiliary rotation shaft 33 is fitted on the rotation shaft 31 and is formed so as to have a minimum gap between the auxiliary pivoting portion 33 and the inner peripheral wall of the shaft tube 2. The support member 22 for supporting the base 31 is also configured to have a minimum contact area. However, when the rotating shaft 31 is not rotating inside the shaft tube, the rotating shaft 31 is supported by a single fulcrum between the flange 222 and the rotating shaft 31, so that the rotating shaft 31 does not rotate and the shaft tube does not rotate. It is formed so as to be non-parallel to the center line and to have a relatively large amount of skew. Therefore, there is a problem that a relatively large swing or friction occurs at the moment when the rotating shaft 31 starts to rotate.

The present invention has been devised in view of such a problem, and an object of the present invention is to provide a relatively small distance between the rotor and the support member when the rotation shaft of the rotor does not rotate. An object of the present invention is to provide a pivoting structure of a rotor having a contact area and capable of obtaining a relatively stable rotation immediately at the moment when the rotating shaft starts to rotate.

A second object of the present invention is to provide a rotor pivoting structure that can extend the life of the rotor by the stable rotation of the rotor and reduce noise.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the pivot structure of the rotor according to the present invention is as follows. That is, the pivot structure of the rotor is constituted by the metal shaft tube and the rotor. A first support member, a second support member, and a support member are fixedly provided inside the metal shaft tube, a through hole is formed in the first support member and the second support member, and a flange projects from a peripheral wall of the through hole. The support member is provided with a support portion. A rotating shaft is vertically provided at the center of the rotor, and one end of the rotating shaft of the rotor passes through the through holes of the first support member and the second support member, and the end surface of the rotating shaft is in contact with the support portion of the support member. The rotation shaft and the flanges of the first support member and the second support member are formed so as to have a minimum clearance or to make a slight contact.

In addition, the rotor pivoting structure of the present invention can be configured as follows. 1. A fixing member fixed to a fixed position is fixed to the metal shaft tube, a through hole is formed in the fixing member, a locking groove is formed in the rotating shaft, and a locking groove is formed in the rotating shaft. The groove is formed so that it can be engaged with the fixing member. 2. The first support member, the second support member, the support member, and the fixing member are formed so as to be fitted to the inner peripheral wall of the metal shaft tube by an interference fit method. 3. The first support member, the second support member, and the support member are formed so as to be fitted to the inner peripheral wall of the metal shaft tube by an interference fit method, and the fixing member is fixed by being pressed by the first support member and the support member. It is formed as follows. 4. The first support member and the second support member are formed in a tube having a flange, and are formed so as to be directly fixed to the inner peripheral wall of the metal shaft tube by the flange. 5. The first support member and the second support member are connected so as to be integrated. 6. The metal shaft tube is bonded to the base, the base is provided with a balancing piece made of a magnetically conductive material, the rotor is provided with a permanent magnet, and the balancing piece and the permanent magnet provided with the rotor correspond to each other. It is formed so that it can suck each other. 7. It consists of a metal shaft tube and a rotor. A second support member and a support member are fixed inside the metal shaft tube, a through hole is formed in the second support member, a flange is protruded from a peripheral wall of the through hole, and the support member is supported. A part is formed. A rotation shaft is vertically provided at the center of the rotor, and a central projection of the rotation shaft connected to the rotor is formed on the auxiliary support member. The rotation shaft of the rotor passes through the through hole of the second support member, and the end surface of the rotation shaft can abut the support portion of the support member, and the central protrusion of the rotation shaft and the inner peripheral wall of the metal shaft tube, and The second support member is formed so as to have a minimum gap or a small contact between the flange and the rotation shaft. 8. A fixing member fixed to a fixed position is fixed to the metal shaft tube, a through hole is formed in the fixing member, a locking groove is formed in the rotating shaft, and a locking groove is formed in the rotating shaft. The groove is formed so that it can be engaged with the fixing member. 9. It consists of a metal shaft tube and a rotor. A second support member and a support member are fixed inside the metal shaft tube, a through hole is formed in the second support member, a flange is protruded from a peripheral wall of the through hole, and the support member is supported. A part is formed. A rotating shaft is suspended from the center of the rotor, and an auxiliary support member is fixed to the rotor. The rotation shaft of the rotor passes through the through hole of the second support member fixed to the metal shaft tube, and the end surface of the rotation shaft can abut on the support portion of the support member. The inner peripheral wall of the metal shaft tube and the flange of the second support member fixed to the metal shaft tube and the rotating shaft are formed so as to have a minimum clearance or to be in slight contact. 10. A fixing member fixed to a fixed position is fixed to the metal shaft pipe, a through hole is formed in the fixing member, a locking groove is formed in the rotating shaft, and a locking groove is formed in the rotating shaft. The groove is formed so that it can be engaged with the fixing member. 11. It consists of a metal shaft tube and a rotor. A support member is fixed inside the metal shaft tube, and a support portion is formed on the support member. A rotating shaft is suspended from the center of the rotor, and two auxiliary support members are fixed to the rotor. The end face of the rotating shaft of the rotor can abut on the supporting part of the supporting member, so that the two auxiliary supporting members of the rotating shaft and the inner peripheral wall of the metal shaft tube have a minimum clearance or a slight contact. It is formed so that 12. A fixing member fixed to a fixed position is fixed to the metal shaft pipe, a through hole is formed in the fixing member, a locking groove is formed in the rotating shaft, and a locking groove is formed in the rotating shaft. The groove is formed so that it can be engaged with the fixing member. 13. The auxiliary support member fixed to the rotating shaft is made of a plastic or rubber material. 14． An annular groove into which the auxiliary support member is fitted is recessed in the rotation shaft. 15. The metal shaft tube is bonded to the base, the base is provided with a balancing piece made of a magnetically conductive material, the rotor is provided with a permanent magnet, and the balancing piece and the permanent magnet provided on the rotor are correspondingly provided. It is formed so that it can suck each other.

[0010]

[Embodiment of the invention]

 An embodiment according to the present invention will be described below with reference to the drawings.

[0011]

Embodiment 1 FIGS. 1 and 2 are an exploded perspective view and a sectional view of an assembled state of a rotor pivoting structure according to a first embodiment of the present invention, mainly showing a base 1, a metal shaft tube 2, a rotor 3, and the like. It is composed of members.

The base 1 can be formed of a case body of a conventional motor or a heat dissipation fan. As a best mode of application, the base 1 is further provided with a fixed balancing piece 11 which is made of a magnetically conductive material and which attracts the permanent magnet 33 of the rotor 3 correspondingly. It is formed to be able to.

The metal shaft tube 2 is made of a magnetic conductive material, and one end of the metal shaft tube 2 can be fixed to the base 1. A conventional stator seat 12 is fitted on the outer peripheral wall of the metal shaft tube 2, and a flange 20 is protruded from the other end of the metal shaft tube 2 to prevent the stator seat 12 from coming out by the flange 20. Can be restricted. A first support member 21, a second support member 22, a support member 23, and a fixing member 24 are fixed inside the metal shaft tube 2, and the first support member 21, the second support member 22, the support member 23, and the fixing member are fixed. 24 and the inner peripheral wall of the metal shaft tube 2 can be fixed using various fixing methods. Among them, the first support member 21 is directly fixed to the inner peripheral wall of the metal shaft tube 2 by an interference fit method. Further, the second support member 22 and the support member 23 are fixed to the inner peripheral wall of the metal shaft tube 2 by an interference fit method, and the fixing member 24 is fixed by being pressed by the second support member 22 and the support member 23. The method performed is a relatively simple method.

The first support member 21 and the second support member 22 are provided with through holes 211 and 221 through which the rotation shaft 31 of the rotor 3 passes. The smaller the contact area between the first support member 21, the second support member 22 and the rotating shaft 31, the better. For example, as shown in FIGS. It is preferable that the flanges 212 and 222 protrude from the peripheral walls of the through holes 211 and 221.

The support member 23 has a support portion 230 formed thereon, and the support portion 230 may be formed of a bottom portion for sealing the support member 23, or may be transparent to the support member 23 as shown in FIGS. By forming the hole 231 and further covering with the support plate 232, the support portion 230 or the support plate 232 can abut on the end face of the rotating shaft 31 of the rotor 3.

The fixing member 24 can be formed of a conventional locking ring. The fixing member 24 is fixed at an appropriate position inside the metal shaft tube 2, and the fixing member 24 has a rotating shaft 31 of the rotor 3. An openable and closable through hole 241 is formed to penetrate through.

The rotor 3 has a rotation shaft 31 vertically suspended from its center position. The rotation shaft 31 penetrates through the through holes 211 and 221 of the first support member 21 and the second support member 22 and the through hole 241 of the fixing member 24. Then, the end surface of the rotating shaft 31 can abut on the support portion 230 or the support plate 232 of the support member 23. Further, a locking groove 32 is formed in the rotating shaft 31 so as to be locked with the fixing member 24 by the locking groove 32, so that the problem that the rotor 3 comes off is eliminated. The rotating shaft 31 and the flanges 212 and 222 of the first support member 21 and the second support member 22 are formed so as to have a minimum gap or to be in slight contact (as shown in FIG. 3). . Since the permanent magnet 33 is provided around the rotor 3 itself, the permanent magnet 33 can be guided to the stator seat 12 and can be attracted to each other in correspondence with the balancing piece 11.

[0018]

Embodiment 2 FIG. 4 is a sectional view of an assembled state of a rotor pivoting structure according to a second embodiment of the present invention, in which a first support member and a second support member are formed on an integral support member 25, and a support member is provided. A through hole 251 through which the rotating shaft 31 passes is bored in 25, and two flanges 252 project from a peripheral wall forming the through hole 251 of the support member 25. The two flanges 252 and the rotary shaft 31 are formed so as to have a minimum gap or a small contact, and the two flanges 252 are formed to have an appropriate distance. In a preferred embodiment, the two flanges 252 are preferably located at both ends of the peripheral wall of the through hole 251 of the support member 25, so that the support member 25 has a minimum contact area with the rotating shaft 31. Since the rotating shaft 31 can be supported by the support member 25, the amount of deviation from the center line of the shaft tube 20 becomes minimum when the rotating shaft 31 is not rotating, Further, when the rotating shaft 31 rotates, stable rotation can be obtained immediately.

[0019]

Third Embodiment FIG. 5 is a cross-sectional view of the assembled state of a rotor pivoting structure according to a third embodiment of the present invention. A single second support member 22 is fixed to the inner peripheral wall of the metal shaft tube 2. The second support member 22 is provided with a through hole 221 through which the rotating shaft 31 passes. A single flange 222 protrudes from the peripheral wall forming the through hole 221, and is formed so as to have a minimum gap between the single flange 222 and the rotating shaft 31 or to make a slight contact. In both cases, a central projection 34 having a relatively large diameter is formed at the center of the rotating shaft 31 connected to the rotor 3. Since the diameter of the central protrusion 34 is formed to be slightly smaller than the inner diameter of the metal shaft tube 2, the center protrusion 34 and the inner diameter of the metal shaft tube 2 are formed so as to have a minimum gap. Since the rotating shaft 31 can be supported by the central projecting portion 34 in this manner, by supporting the rotating shaft 31 jointly with the second support member 22, the eccentricity when the rotating shaft 31 is not rotating can be obtained. The amount will be the minimum.

[0020]

Fourth Embodiment FIG. 6 is a cross-sectional view of the assembled state of a rotor pivoting structure according to a fourth embodiment of the present invention. A single second support member 22 is fixed to the inner peripheral wall of the metal shaft tube 2. The second support member 22 is provided with a through hole 221 through which the rotating shaft 31 passes, and one flange 222 protrudes from a peripheral wall forming the through hole 221. The flange 222 and the rotating shaft 31 are formed so as to have a minimum gap or to make a slight contact. Further, an auxiliary support member 35 is fixed to the rotation shaft 31 of the rotor 3. The auxiliary support member 35 is made of a plastic or rubber material. As shown in FIG. 6, the rotary shaft 31 has an annular groove for fitting and fixing the auxiliary support member 35 therein. Since the diameter of the auxiliary support member 35 is formed to be slightly smaller than the inner diameter of the metal shaft tube 2, the auxiliary support member 35 and the inner diameter of the metal shaft tube 2 are formed so as to have a minimum gap. Since the rotation shaft 31 can be supported by the auxiliary support member 35 in this manner, by supporting the rotation shaft 31 jointly with the second support member 22, the bias when the rotation shaft 31 is not rotating can be adjusted. The amount of inclination becomes the minimum value.

[0021]

Embodiment 5 FIG. 7 is a sectional view of the assembled state of a rotor pivoting structure according to a fifth embodiment of the present invention, in which two auxiliary support members 35a and 35b are fixed to the rotating shaft 31 of the rotor 3. You. The two auxiliary support members 35a and 35b are made of plastic or rubber, and the auxiliary support members 35a and 35b are fixedly mounted on the rotating shaft 31. Since the diameters of the two auxiliary support members 35a and 35b are formed to be slightly smaller than the inner diameter of the metal shaft tube 2, the auxiliary support member 35 and the inner diameter of the metal shaft tube 2 are formed so as to have a minimum gap. Is done. Since the rotation shaft 31 can be supported by the two auxiliary support members 35a and 35b in this manner, the rotation shaft 31 is rotated by supporting the rotation shaft 31 in cooperation with the second support member 22. When it is not, the amount of skew becomes the minimum value.

[0022]

[Effect of the invention]

 According to the rotor pivoting structure of the present invention, the rotating shaft of the rotor abuts on the supporting portion or the supporting plate of the supporting member only by the end face of the rotating shaft, and the rotating shaft is made of metal by the auxiliary supporting member or the central projecting portion. It is formed so as to have a minimum gap or a little contact with the inner peripheral wall of the shaft pipe, or to have a minimum gap or a little contact with the rotating shaft by two support members. In this way, the amount of skew when the rotating shaft is not rotating is minimized, and stable rotation can be obtained immediately after the rotating shaft starts rotating. As a result, friction and noise due to rotation of the rotating shaft can be reduced to a minimum. Furthermore, since the rotor can be easily processed or manufactured even during assembly, there is an advantage that the production cost can be reduced.

The present invention may be embodied in other ways without departing from its spirit and essential characteristics. Accordingly, the preferred embodiments described herein are illustrative and not intended to be limiting.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a pivot structure of a rotor according to a first embodiment of the present invention.

FIG. 2 is a plan view of an assembled state of the rotor pivoting structure shown in FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a plan view of the assembled state of the pivoting structure of the rotor according to the second embodiment of the present invention.

FIG. 5 is a plan view of the assembled state of the pivoting structure of the rotor according to the third embodiment of the present invention.

FIG. 6 is a plan view of a fourth embodiment of the present invention illustrating an assembled state of a pivoting structure of a rotor.

FIG. 7 is a plan view of the fifth embodiment of the present invention, showing the assembled state of the pivoting structure of the rotor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base 11 Fixed part 12 Localization member 13 Shaft seat 14 Bearing 15 Screw member 16 Cap 17 Balancing piece 2 Stator set 20 Center hole 21 Silicon steel piece 22 Coil 23 Insulation ring 231 Center hole 3 Rotor 31 Rotation axis 32 Induction ring 33 Ring Permanent magnet 34 Blade 35 Magnetic insulating layer

Claims (16)

[Utility model registration claims] 1. A rotor pivot structure comprising a metal shaft tube (2) and a rotor (3), wherein a first support member (21), a second support member (21) and a second support member are provided inside the metal shaft tube (2). A support member (22) and a support member (23) are fixedly provided, and the first support member (21) and the second support member (22) have through holes (21).
1,221), a flange (212,222) protrudes from the peripheral wall of the through hole (211, 221), a support portion (230) is formed on the support member (23), and the rotor (3) is formed. ), A rotating shaft (31) is vertically provided, and one end of the rotating shaft (31) of the rotor (3) has through holes (211, 211, 21 22
While passing through 1), the end face of the rotating shaft (31) can abut on the support portion (230) of the support member (23),
The rotation shaft (31) and the flanges (212, 222) of the first support member (21) and the second support member (22) are formed so as to have a minimum gap or to make a slight contact. The pivot structure of the rotor. 2. A fixing member (24) fixed to a fixed position is fixed to the metal shaft tube (2), a through hole (241) is formed in the fixing member (24), and a rotating shaft (24) is formed. A locking groove (32) is recessed in 31), and a locking groove (32) recessed in the rotating shaft (31) is formed so as to be able to lock with the fixing member (24). The pivotal attachment structure for a rotor according to claim 1, wherein: 3. The first support member (21), the second support member (22), the support member (23) and the fixing member (24).
3. The structure according to claim 2, wherein the rotor is fixed to the inner peripheral wall of the metal shaft tube by an interference fit. 4. The first support member (21), the second support member (22) and the support member (23) are formed so as to be fixed to the inner peripheral wall of the metal shaft tube (2) by an interference fit method. The pivoting structure of the rotor according to claim 3, wherein the fixing member (24) is formed so as to be pressed and fixed by the first support member (21) and the support member (23). 5. The first support member (21) and the second support member (22) are formed in a tube having a flange (212, 222), and the metal shaft tube (2) is formed by the flange (212, 222). The pivotal attachment structure for a rotor according to claim 1, wherein the rotor is formed so as to be directly fixed to an inner peripheral wall of the rotor. 6. The structure according to claim 1, wherein the first support member and the second support member are connected so as to be integrated. 7. The metal shaft tube (2) is bonded to a base (1), the base (1) is provided with a balancing piece (11) made of a magnetic conductive material, and the rotor (3) is mounted on the rotor (3). A permanent magnet (33) is provided, and the balancing piece (11) and the permanent magnet (33) provided around the rotor (3) are formed so as to be able to attract each other correspondingly. A pivot structure for a rotor according to claim 1. 8. A pivot structure of a rotor constituted by a metal shaft tube (2) and a rotor (3), wherein a second support member (22) and a support member are provided inside the metal shaft tube (2). (23) is fixed, a through hole (221) is formed in the second support member (22), and a flange (222) is protruded from the peripheral wall of the through hole (221). Is formed with a support portion (230), a rotation shaft (31) is vertically provided at the center of the rotor (3), and a central protruding portion (34) of the rotation shaft (31) connected to the rotor (3) is The rotation shaft (31) of the rotor (3) is formed on the auxiliary support member, passes through the through hole (221) of the second support member (22), and the end surface of the rotation shaft (31) is formed on the support member (23). Can be brought into contact with the support portion (230) of the rotating shaft (31). The inner peripheral wall of the slave shaft pipe (2), the flange (222) of the second support member (22) and the rotating shaft (3).
1) A pivoting structure of a rotor, wherein the rotor is formed so as to have a minimum gap or a small contact therebetween. 9. A fixing member (24) fixed to a fixed position is fixed to the metal shaft tube (2), a through hole (241) is formed in the fixing member (24), and a rotating shaft (24) is formed. A locking groove (32) is recessed in 31), and a locking groove (32) recessed in the rotating shaft (31) is formed so as to be able to lock with the fixing member (24). The pivotal attachment structure for a rotor according to claim 8, wherein: 10. A metal shaft tube (2) and a rotor (3).
Wherein a second support member (22) and a support member (23) are fixed inside the metal shaft tube (2), and the second support member (22) is fixed to the second support member (22). Is formed with a through hole (221), a flange (222) protrudes from the peripheral wall of the through hole (221), a support portion (230) is formed on the support member (23), and the rotor (3) A rotation shaft (31) is vertically provided at the center, an auxiliary support member (35) is fixed to the rotor (3), and a rotation shaft (31) of the rotor (3) is fixed to the metal shaft tube (2). While passing through the through hole (221) of the second support member (22) provided, the end surface of the rotating shaft (31) is supported by the support portion (230) of the support member (23).
Of the auxiliary support member (35) of the rotating shaft (31), the inner peripheral wall of the metal shaft tube (2), and the second support member (22) fixed to the metal shaft tube (2). A pivoting structure for a rotor, wherein the rotor has a minimum clearance or a small contact between the flange and the rotating shaft. 11. A fixing member (24) fixed at a fixed position is fixed to the metal shaft tube (2), and the fixing member (24) is fixed.
Is provided with a through hole (241), a rotation groove (32) is formed in the rotating shaft (31), and a locking groove (32) formed in the rotation shaft (31) is fixed to the fixing member ( The pivoting structure of the rotor according to claim 10, wherein the rotor is formed so as to be able to engage with (24). 12. Metal shaft tube (2) and rotor (3)
A support member (23) is fixedly provided inside the metal shaft tube (2),
A support part (230) is formed on the support member (23), a rotation shaft (31) is vertically installed at the center of the rotor (3), and two auxiliary support members (35a, 35a) are provided on the rotor (3).
35b) is fixed, and the rotating shaft (3) of the rotor (3) is fixed.
The end face of 1) can abut on the support portion (230) of the support member (23), the two auxiliary support members (35a, 35b) of the rotating shaft (31) and the inner peripheral wall of the metal shaft tube (2). A pivotal attachment structure of the rotor, wherein the rotor is formed so as to have a minimum clearance or a small contact. 13. A fixing member (24) fixed to a fixed position is fixed to said metal shaft tube (2), and said fixing member (24) is fixed.
Is provided with a through hole (241), a rotation groove (32) is formed in the rotating shaft (31), and a locking groove (32) formed in the rotation shaft (31) is fixed to the fixing member ( The pivotable structure of the rotor according to claim 12, wherein the rotor is formed so as to be able to engage with (24). 14. An auxiliary support member (35, 35a, 35b) fixed to the rotating shaft (31) is made of a plastic or rubber material.
13. The pivotal attachment structure of the rotor according to 0 or 12. 15. The rotor according to claim 10, wherein an annular groove for receiving an auxiliary support member (35, 35a, 35b) is formed in the rotating shaft (31). Pivot structure. 16. The metal shaft tube (2) is bonded to a base (1), the base (1) is provided with a balancing piece (11) made of a magnetic conductive material, and the rotor (3) is mounted on the rotor (3). A permanent magnet (33) is provided, and the balancing piece (11) and the permanent magnet (33) provided around the rotor (3) are formed so as to be able to attract each other correspondingly. 13. The structure for pivotally attaching a rotor according to claim 8, 10 or 12.