JPH05344674A - Bearing device for motor - Google Patents

Abstract

PURPOSE:To materialize the downsizing and noise reduction of a motor by supporting the bearing in thrust direction and radial direction by means of a pair of magnetic pole pieces attached to a stator part and a rotor part, using a magnetic bearing making use of the resiliency or attraction of a magnet. CONSTITUTION:The bearing in thrust direction and radial direction are constituted by a pair or magnetic pole pieces attached to a stator part and a rotor part. Magnets 4 and 4' on rotor side and magnets 8 and 8' on stator side are magnetized so that the opposed sides may be of the same poles or different poles with each other. By constituting it this way, resiliency or attraction works both in thrust direction and in radial direction, and the rotor part of a motor is kept in noncontact condition to the stator part. Hereby, the motor can be downsized and the noise can be reduced, and further it can be rotated with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a motor, and more particularly to a bearing structure that can be stably rotated at a low load in a motor that is small and rotates at high speed such as a cylinder motor of a VTR. is there.

[0002]

2. Description of the Related Art As a conventional bearing of a motor, a ball bearing is generally used. As another bearing structure, as described in JP-A-60-140518, downsizing of a motor and low noise are achieved. A structure using a hydrodynamic bearing for the purpose of achieving a longer life and a longer life and a magnetic bearing structure utilizing a magnetic repulsive force as described in JP-A-55-60719.

[0003]

In the above-mentioned prior art, in the case of a motor that rotates at a high speed such as a cylinder motor of a VTR, in the case of a ball bearing, the rotor portion and the stator portion are in contact with each other. Rotational unevenness increases,
There have been problems that the jitter performance is deteriorated, noise is increased, and the life of the bearing itself is short. Furthermore, when the rotation speed of the motor is increased,
In order to increase the rigidity of the ball bearing, it is necessary to use a ball bearing having a large shape, which causes a problem that the motor structure becomes large.

Further, in the case of a hydrodynamic bearing which utilizes a hydrodynamic levitation force of a fluid to rotate a rotating part and a fixed part in a non-contact manner, reduction of noise of a motor, prolongation of life, downsizing and the like are realized. However, there is a problem that the viscosity of the fluid becomes high at low temperature and the rotating load becomes large due to the temperature characteristics of the fluid, and conversely, at high temperature, the viscosity of the fluid decreases and it becomes impossible to obtain a predetermined flying height. there were. Furthermore, in the case of hydrodynamic bearings, the rotation direction is limited to one direction,
There was a problem that it could not be used at low speed rotation. Furthermore, when the magnetic bearing of the conventional structure is used, the bearing can be supported in a non-contact manner like the hydrodynamic bearing and is not affected by temperature changes like the hydrodynamic bearing, but the structure becomes complicated. There was a problem that the cost became high. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to realize a motor bearing device that is small in size, low in noise, low in load, long in service, low in cost, and highly accurate in rotation.

[0005]

In order to achieve the above object, according to the present invention, a magnetic bearing utilizing the repulsive force or attractive force of a magnet is used as a bearing, and the bearing support in the thrust direction and the radial direction is used for the stator part and the rotor. The structure is made by a pair of magnetic pole pieces attached to the section.

Further, a bearing for supporting the thrust direction by utilizing the attractive force generated between the rotor magnet of the motor and the stator yoke, and the thrust direction is supported by a pair of thrust bearings provided in the stator part and the rotor part. It has a structure.

[0007]

The stator and rotor of the motor are provided with a pair of magnetic pole pieces facing each other in both the thrust and radial directions. The facing surfaces of the magnetic pole pieces provided on the stator portion and the rotor portion are magnetized so that they have the same or different polarities. This allows
A repulsive force or a suction force is generated between the magnetic pole piece provided on the stator side and the magnetic pole piece provided on the rotor side, and the rotor portion of the motor is held in a non-contact state with the stator portion.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to each embodiment shown in FIGS. Each of the following embodiments shows an example in which the bearing device according to the present invention is incorporated into a cylinder motor used in a VTR or the like. However, the motor to which the bearing device according to the present invention is applied may be a motor for various other uses. Needless to say, it is included.

1 and 2 relate to a first embodiment of the present invention, and FIG. 1 is a cross-sectional view of a motor bearing device of this embodiment incorporated into a cylinder motor. In this embodiment, FIG.
As shown in FIG. 2, ring-shaped rotor-side magnets 4 and 4'are attached to the upper and lower sides of the shaft 1, and a cup-shaped stator-side magnet having a central hole at a position facing the rotor-side magnets 4 and 4 '. 8, 8'are provided to form a magnetic bearing. A rotor yoke 2 is fixed to the shaft 1, and a rotor magnet 3 for separately driving a motor, which is divided into N poles and S poles, is attached to the rotor yoke 2. A stator coil 5 is provided by a coil holder 6 at a position facing the rotor magnet 3.
Is attached to the lower cylinder 7. Further, a rotary yoke 9 attached to the rotor yoke 2 is provided at a position facing the opposite surface of the stator coil 5, and these constitute a motor.

FIG. 2 shows an enlarged view of the bearing portion of this embodiment. As shown in the figure, the rotor side magnet 4,
4'is fixed to the shaft 1, the stator-side magnet 8'is fixed directly to the lower cylinder 7, the stator-side magnet 8 is fixed to the lower cylinder 7 via the mounting member 22, and the rotor-side magnets 4 and 4'and the stator. Side magnet 8,
8'is opposed to each other in both the thrust direction and the radial direction. As described above, according to the present embodiment, the thrust direction and radial direction bearings can be configured by the pair of magnetic pole pieces attached to the stator part and the rotor part. The rotor-side magnets 4 and 4'and the stator-side magnets 8 and 8'are magnetized so that the surfaces facing each other have the same polarity. With this structure, a repulsive force acts in both the thrust direction and the radial direction to support the rotor portion in a non-contact manner. In addition,
In this embodiment, the N poles face each other, but the S poles may face each other. Also, the rotor side magnets 4, 4 '
Alternatively, the stator side magnets 8 and 8 ′ may be opposed to each other with different poles, and the attraction force of the magnets may be used to achieve a balance.

In the thrust direction, the repulsive force between the stator-side magnet 8 and the rotor-side magnet 4 is balanced with the repulsive force between the stator-side magnet 8'and the rotor-side magnet 4 ', so that the respective gaps in the thrust direction are predetermined. It is necessary to adjust the coercive force in the thrust direction so that the value becomes. Actually, the self-weight of the rotor part acts on the repulsive force of the magnet, so if the magnetic forces in the thrust direction are the same,
The gap between the stator side magnet 8 and the rotor side magnet 4 becomes narrower than the gap between the stator side magnet 8'and the rotor side magnet 4'due to the gravity of the rotor portion. Therefore, for example, in order to make the value of the gap between the stator-side magnet 8 and the rotor-side magnet 4 equal to the value of the gap between the stator-side magnet 8'and the rotor-side magnet 4 ', the magnetic force of the rotor-side magnet 4 is set to the rotor-side. The magnetizing force is made larger than that of the magnet 4'or the magnetizing force of the stator side magnet 8 is made larger than that of the stator side magnet 8 ', so that the repulsive force between the stator side magnet 8 and the rotor side magnet 4 becomes large. Will be adjusted.

The structure of the cylinder shown in FIG. 1 will be additionally described. The stator side core 12 of a known rotary transformer is attached to the lower cylinder 7, and the rotor side core 13 of the rotary transformer is opposed to the stator side core 12.
It is fixed to the shaft 1 by. An upper cylinder 15 is attached to the upper portion of the rotating disk 14, and a rotating magnetic head 17 mounted on a head base 16 is attached to the outer peripheral portion of the upper cylinder 15. The rotary magnetic head 17 records and reproduces signals on and from a recording medium (not shown) such as a magnetic tape while rotating with the motor. Figure 1
Reference numeral 18 denotes a rotation signal detection board, which is an FG magnet 1 attached to the rotor yoke 2 for detecting a rotation speed signal.
9 and changes in the magnetic field of the PG magnet 10 for detecting the rotational position are detected, and a motor rotation signal such as an FG signal or a tack signal is obtained.

As described above, in this embodiment, the bearings of the motor can be supported in both the thrust direction and the radial direction by the repulsive force or the attractive force of the pair of magnetic pole pieces provided in the stator portion and the rotor portion. With the structure. As a result, it is possible to realize a motor bearing device having a small rotational unevenness, a simple structure, a small size, low friction, low noise, a long service life, and the problems of increased rotational friction load due to temperature change and insufficient flying height. You can

FIG. 3 is a sectional view of a cylinder motor according to a second embodiment of the present invention. In this embodiment, cylindrical rotor-side magnets 20 and 20 'having flange portions are provided above and below the shaft 1, and a ring-shaped stator-side magnet 21 is provided at a position facing the rotor-side magnets 20 and 20'. , 21 'are provided to form a magnetic bearing. The stator-side magnet 21 ′ is attached directly to the lower cylinder 7, and the other stator-side magnet 21 is attached to the lower cylinder 7 via an attachment member 22. In this embodiment as well, as in the first embodiment, the rotor-side magnets 20, 2
0'and the magnets 21 and 21 'on the stator side face each other in both the thrust direction and the radial direction, and repel each other by magnetizing the facing faces to have the same or different polarities. A force or a suction force works, and the rotor portion of the motor can be supported in a non-contact manner. In this embodiment as well, it is necessary to adjust the magnetic force in the thrust direction as in the case of the first embodiment, and the gap in the thrust direction between the stator-side magnet 21 and the rotor-side magnet 20, the stator-side magnet 21 'and the rotor. When the value of the gap in the thrust direction with the side magnet 20 'is the same, the magnetic force in the thrust direction of the rotor side magnet 20 is made larger than the magnetic force of the rotor side magnet 20', or the thrust force of the stator side magnet 21 is increased. The magnitude of the magnetic force in the direction needs to be larger than the magnetic force of the stator-side magnet 21 '. Other cylinder structures are the same as those in the first embodiment.

With this structure, the same effect as that of the first embodiment can be obtained in this embodiment as well.

4 and 5 relate to a third embodiment of the present invention, FIG. 4 is a sectional view of a cylinder motor according to the present embodiment, and FIG. 5 is an enlarged view of a bearing portion of FIG. As shown in FIG. 4, in this embodiment, a cylindrical rotor-side magnet 23 having a flange portion attached to the shaft 1 and a cup-shaped stator-side magnet 24 having a central hole provided in the inner peripheral portion of the lower cylinder 7 are provided. With, the structure is such that a magnetic bearing is formed. As shown in the enlarged view of the bearing portion in FIG. 5, a pair of rotor-side magnets 23 and stator-side magnets 24 are provided so as to face each other in both the thrust direction (the thrust direction at the two upper and lower positions) and the radial direction. .. The radial bearing portion 32 has a thrust bearing portion 31a in the thrust direction so that the same poles (N poles in the figure) face each other.
In the thrust bearing portion 31b, the rotor-side magnet 23 and the stator-side magnet 24 are magnetized so that different poles face each other and attract force acts, and in the thrust bearing portion 31b, the same poles face each other and repulsive force acts.

With such a structure, also in this embodiment, the repulsive force or the attractive force of the magnet acts and the rotor portion of the motor can be supported in a non-contact manner. In the present embodiment, the N poles of the radial bearing portion 32 are opposed to each other, but the S poles may be opposed to each other, or the different poles may be opposed to each other to support the bearing by the attractive force of the magnet. May be According to the present embodiment, since the bearing can be configured only with a pair of magnetic pole pieces provided in the stator portion and the rotor portion, the bearing structure can be further simplified and the cost can be reduced. The same effects as those of the first and second embodiments can be obtained.

FIG. 6 is a sectional view of a cylinder motor according to a fourth embodiment of the present invention. In the present embodiment, a rotor magnet 3 provided on a rotor yoke 2'attached to a shaft 1,
The stator coil 5 and the stator yoke 29, which are fixed to the coil holder 6 attached to the lower portion of the lower cylinder 7 at a position opposed to this, constitute a motor. In this embodiment, the rotor magnet 3 and the stator yoke 29
The structure is such that the motor attraction force generated between and is used as part of the thrust magnetic bearing that supports the thrust direction of the rotor portion. Further, a ring-shaped rotor-side magnet 27 is provided on the surface of the rotor yoke 2'opposite to the surface on which the rotor magnet 3 is attached, and a ring-shaped shape is formed on the lower surface of the lower cylinder 7 so as to face the rotor-side magnet 27. The stator side magnet 28 having the above structure is provided to constitute another magnetic bearing in the thrust direction. The rotor-side magnet 27 and the stator-side magnet 28 are magnetized so that the surfaces facing each other have different polarities. The attractive force generated between the rotor-side magnet 27 and the stator-side magnet 28 is generated by the rotor magnet 3 of the motor.
Magnetization is performed so as to balance with the attractive force generated between the stator yoke 29 and the stator yoke 29. On the other hand, ring-shaped rotor-side magnets 25, 25 'are attached to the shaft 1, and ring-shaped stator-side magnets 26, 26' are provided on the inner peripheral portion of the lower cylinder 7 so as to face them. Are provided to form a radial magnetic bearing. Rotor side magnets 25, 25 'and stator side magnet 26,
The magnets 26 'are magnetized so that the surfaces facing each other have the same or different polarities, so that a repulsive force or an attractive force is generated between the rotor side magnets 25, 25' and the stator side magnets 26, 26 '. ..

By adopting such a structure, also in this embodiment, it is possible to support the rotor portion in a non-contact bearing by utilizing the repulsive force or attractive force of the magnet in the thrust direction and the radial direction. Further, in this embodiment, since the structure that utilizes the attractive force generated between the rotor magnet 3 of the motor and the stator yoke 29 is used as the means for supporting the bearing in the thrust direction, the structure is simplified as compared with the conventional magnetic bearing. In addition to being able to realize cost reduction, it is possible to obtain the same effects as those of the above-mentioned respective embodiments.

7 to 10 relate to the fifth embodiment of the present invention, and FIG. 7 is a sectional view of a cylinder motor of the present embodiment. In this embodiment as well, as in the fourth embodiment, the attractive force generated between the rotor magnet 3 of the motor and the stator yoke 29 is used to support the bearing in the thrust direction. On the surface of the rotor yoke 2'opposite to the surface on which the rotor magnet 3 is mounted, a ring-shaped rotor-side magnet 27 that constitutes another thrust magnetic bearing is mounted. An electromagnet 30 is provided on the lower surface of the lower cylinder 7 facing the rotor-side magnet 27 to generate a magnetic field by passing a current through the winding coil.
The rotor-side magnet 27 and the electromagnet 30 constitute another thrust magnetic bearing.

FIG. 8 shows a perspective view of the electromagnet 30.
As shown in the figure, the electromagnet 30 includes four electromagnets 30a, 30b, 30c and 30d which are obtained by dividing a disk into four.
It is composed by. These electromagnets 30a, 30b,
Winding coils 37a, 37 wound around 30c, 30d
A magnetic field is generated by supplying a predetermined current to b, 37c, and 37d, and an attractive force is generated between the magnetic field and the rotor-side magnet 27 provided at the opposing position. The attraction force generated between the electromagnet 30 and the rotor-side magnet 27 and the attraction force generated between the rotor magnet 3 of the motor and the stator yoke 29 are balanced to provide non-contact bearing support in the thrust direction. I do. As in the fourth embodiment, the bearings in the radial direction are supported by the rotor-side magnets 25 and 25 'provided on the shaft 1 and the stator-side magnet 26 provided on the inner peripheral portion of the lower cylinder 7 so as to face them. , 26 'are magnetized so that the opposite surfaces have the same or different polarities, and the rotor-side magnet 2
The non-contact bearing support in the radial direction is performed by the repulsive force or the attractive force generated between the magnets 5, 25 'and the stator side magnets 26, 26'.

In this embodiment, four electromagnets 30 are further provided.
By separately driving a, 30b, 30c, and 30d independently, the surface runout of the rotor can be corrected. Hereinafter, this surface shake correction method will be described. 9A shows the output of the surface wobbling signal in which the surface wobbling detection element 38 shown in FIG. 7 detects the surface wobbling of the rotor. A magnetic sensor or the like is used as the surface shake detection element 38, and the change in the magnetic field of the FG magnet 19 is detected by this. When the rotor has surface wobbling, the gap between the surface wobbling detection element 38 and the FG magnet 19 changes periodically, and the output of the surface wobbling detection element 38 is AM-modulated as shown in FIG. 9A. .. FIG. 9B shows the output of the tack signal, and the pulse signal is output once every one cycle (t) of the motor. FIG. 9C shows the electromagnets 30a, 30b, 30.
The c and 30d arrangements are developed on a plane, and the electromagnet 30
The position of "a" and the generation position of the tack signal are synchronized. Therefore, the electromagnet 30b is arranged at a position having a phase difference of t / 4 with respect to the tack signal, the electromagnet 30c is provided with t / 2 for the tack signal, and the electromagnet 30d is arranged at a position having a phase difference of 3t / 4 with respect to the tack position. There is.

FIG. 10 shows a block diagram of the surface shake correction means. The surface wobbling signal detected by the surface wobbling detection element 38 is input to the control circuit 34 from the input terminal 35 shown in FIG.
A tack signal is input to the control circuit 34 from the input terminal 36. The control circuit 34 outputs a correction signal to the drive circuits 33a, 33b, 33c, 33d that drive the electromagnets 30a, 30b, 30c, 30d by the surface wobbling signal and the tack signal, and outputs the correction signals to the winding coils 37a, 37b, 37c, 37d. It controls the flowing electromagnet drive current. Specifically, the control circuit 3
Based on the surface wobbling signal input to 4, the surface wobbling detection element 38
When the gap between the FG magnet 19 and the FG magnet 19 becomes narrow and the output of the surface wobbling detection element 38 becomes larger than the reference value, the drive current of the electromagnet is reduced. This weakens the magnetic field of the electromagnet 30 and weakens the attractive force generated between the electromagnet 30 and the rotor-side magnet 27.
The gap between and widens and returns to the prescribed gap. On the contrary, when the gap between the surface shake detecting element 38 and the FG magnet 19 becomes wider and the output of the surface shake detecting element 38 becomes smaller than the reference value, the drive current of the electromagnet is increased. As a result, the magnetic field of the electromagnet 30 becomes strong, the attractive force generated between the electromagnet 30 and the rotor-side magnet 27 becomes strong, and the gap between the surface wobbling detection element 38 and the FG magnet 19 becomes narrower and returns to a predetermined gap. At this time, as the correction signal output from the control circuit 34, a correction signal having no phase difference is supplied to the drive circuit 33a using the tack signal as a synchronization signal, and a correction signal having a t / 4 phase difference is supplied to the drive circuit 33b. A correction signal having a t / 2 phase difference is output to the drive circuit 33c, and a correction signal having a 3t / 4 phase difference is output to the drive circuit 33d. In this way, each electromagnet 3
Drive circuit 33 for driving 3a, 33b, 33c, 33d
By inputting a correction signal having a predetermined phase difference to a, 33b, 33c, and 33d, the surface runout of the rotor can be corrected.

With this structure, in this embodiment, since the surface runout of the rotor of the motor can be suppressed, it is possible to realize a motor that rotates with high precision and to obtain the same effects as those of the above-described embodiments. Obtainable. Further, the height in the thrust direction can be finely adjusted by adjusting the set value of the current supplied to the electromagnet 30 when the cylinder motor is assembled, and the head height position of the rotary magnetic head 17 can be adjusted and the rotary magnetic head 17 can be adjusted. The inductance value can be adjusted by adjusting the gap width of the transformer. Further, when the cylinder motor according to the present embodiment is mounted on a set such as a VTR, the height of the rotor portion is changed by changing the magnetic field strength of the electromagnet 30 when the magnetic tape is fast forwarded or rewound, and the upper cylinder is changed. 15 and lower cylinder 7
It is also possible to protect the rotary magnetic head 17 by floating the magnetic tape by changing the gap between and to increase the amount of air blown from the gap. Although the present embodiment has described the configuration using four electromagnets, the number of electromagnets may be increased to improve the accuracy of surface wobbling correction, or the number of electromagnets may be reduced for simplification.

Further, in each of the embodiments of the present invention, the plane-opposed rotary transformer is used in the cylinder motor, but this may be a cylindrical rotary transformer.

[0026]

As described above, according to the motor bearing device of the present invention, the stator side and the rotor side of the motor are provided with magnets facing each other in both the thrust direction and the radial direction, and the stator side and the rotor side are provided. By magnetizing opposite surfaces of the magnets provided in and to the same or different polarities, a repulsive force or an attractive force is generated between the magnets to support the rotor portion of the motor in a non-contact manner. As a result, a compact bearing device can be realized with a simple structure, so that the motor can be miniaturized.

Further, since the bearing can be supported in a non-contact manner, it is possible to realize a motor with less rotational unevenness and rotational load and low noise, and to extend the life of the bearing.

Further, since there is no influence of temperature change, there is no problem that the friction load increases at low temperature and there is no problem that the flying height becomes insufficient at high temperature.
A highly reliable motor can be realized.

Furthermore, by using the attraction force between the rotor magnet of the motor and the stator yoke to support the bearing in the thrust direction, the bearing structure can be simplified and the cost can be reduced.

Furthermore, since the gap between the stator and the rotor can be controlled by changing the strength of the magnetic field using an electromagnet, it is possible to realize a motor that rotates with high precision and eliminates surface runout of the rotor. it can.

[Brief description of drawings]

FIG. 1 is a sectional view of a cylinder motor according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a bearing portion of the cylinder motor of FIG.

FIG. 3 is a sectional view of a cylinder motor according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a cylinder motor according to a third embodiment of the present invention.

5 is an enlarged view of a bearing portion of the cylinder motor of FIG.

FIG. 6 is a sectional view of a cylinder motor according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view of a cylinder motor according to a fifth embodiment of the present invention.

8 is a perspective view of an electromagnet used in the cylinder motor of FIG.

FIG. 9 is an explanatory diagram for helping understanding of a surface shake correction method according to a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram of a control block for correcting surface shake according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 shaft 3 rotor magnet 4,4 'rotor side magnet 7 lower cylinder 8,8' stator side magnet 20,20 'rotor side magnet 21,21' stator side magnet 23 rotor side magnet 24 stator side magnet 25,25 'rotor side Magnet 26, 26 'Stator-side magnet 27 Rotor-side magnet 28 Stator-side magnet 29 Stator yoke 30 Electromagnet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriaki Masuda 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture

Claims (3)

[Claims] 1. A bearing device for a motor that rotatably supports the rotor portion with respect to the stator portion of a motor including a stator portion and a rotor portion, wherein the stator-side magnetic pole is magnetized to have N poles or S poles in the stator portion. And a rotor-side magnetic pole piece having the same polarity as or opposite to that of the stator-side magnetic pole piece attached to the stator portion in the rotor portion, in both the thrust direction and the radial direction with respect to the stator-side magnetic pole piece. A bearing device for a motor, wherein the bearings are mounted so as to face each other and support the rotor portion in a non-contact manner. 2. A bearing device for a motor, which rotatably supports the rotor portion with respect to the stator portion of a motor having a stator portion and a rotor portion, wherein the radial direction is supported by a magnetic bearing structure, and the rotor magnet of the motor is provided. A bearing device for a motor, wherein a magnetic attraction force between a stator yoke and a stator yoke is used as at least one of thrust bearings for supporting a thrust direction. 3. A bearing device for a motor, which rotatably supports the rotor portion with respect to the stator portion of a motor having a stator portion and a rotor portion, wherein a rotor-side magnetic pole magnetized to have N poles or S poles on the rotor portion. A bearing device for a motor, characterized in that an electromagnet is provided at a position facing the rotor-side magnetic pole piece in the stator portion, and means for controlling a current supplied to the electromagnet is provided.