JP2616216B2 - Electric motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor, and in particular, to recording used in an apparatus having a magnetic head for reading and writing magnetic recording signals of a magnetic disk which is a disk-shaped recording medium. The present invention relates to an electric motor for driving a medium circuit.

[Prior Art] As a conventional electric motor of this type, there is a technique disclosed in Japanese Utility Model Laid-Open No. 60-13563.

 FIG. 3 is a sectional view showing a conventional electric motor.

In the figure, reference numeral 1 denotes a rotating shaft of a motor, and 2 denotes a rotating body having a magnetic disk holding function. The rotating body 2 rotates integrally with the rotating shaft 1. 3 is an electric motor rotor,
4 is a yoke of the rotor 3, 5 is a permanent magnet disposed on the outer periphery of the yoke 4, 6 is a screw fixing the rotor 3 and the rotating shaft 1, 7 is a stator of the electric motor, and 8 is a stator of the electric motor. An iron core of the stator 7, a coil 9 wound around the iron core 8, a bearing mounting member 10, and bearings 11 and 12 rotatably supporting the rotating shaft 1 mounted on the bearing mounting member 10. 13 is a motor frame, 14 is a screw for fixing the stator 7 and the bearing mounting member 10, and 15 is a driving pin mounted on the rotating body 2, and the driving pin 15 is a rotating pin fixed to the magnetic disk. A window hole (not shown) of the plate is engaged. 16 is an index detecting element disposed on the frame 13, 17 is an index detecting magnet disposed on the rotor 3, and the index detecting element 16 One pulse is generated by the detection magnet 17 per rotation.

The electric motor having the above configuration is of a so-called outer rotor type in which the rotor 3 is located outside the stator 7, and the permanent magnets 5 of the rotor 3 generate a magnetic field in the radial direction of rotation.

[Problems to be Solved by the Invention] In the conventional outer rotor type electric motor as described above,
Some space was required between the rotor 3 and the stator 7. Further, the frame 13 or the bearing mounting member 10 is interposed between the stator 7 and the rotor 3 and the magnetic disk and the magnetic head (not shown). Therefore, there is a limit in reducing the thickness of the electric motor. For this reason, a thin inner rotor type electric motor in which the stator 7 is located outside the rotor 3 has been considered.

However, in order to use this type of motor in a disk device, the rotor must have a disk mounting function, and it is necessary to detect the number of rotations and the rotational position of the rotor. For this reason, a disk mounting function has been added to the rotor, and a magnet for detecting the number of rotations and the rotational position of the rotor has been attached. Further, a permanent magnet is provided on the outer periphery of the rotor via a yoke made of a ferromagnetic material, and the rotor is manufactured by integrating these permanent magnets.
Therefore, the manufacturing work of the rotor is troublesome, the number of working steps is increased, and the manufacturing cost is inevitably increased.

On the other hand, there is another prior art disclosed in Japanese Utility Model Laid-Open No. 55-143675. This technique discloses an inner rotor type motor having a rotor in which a yoke, a magnet, and a rotating shaft are integrally formed. However, there is no disclosure of a technical idea of a thin motor.

Further, the technology disclosed in Japanese Utility Model Laid-Open Publication No. 51-155309 discloses a technology of an inner rotor type electric motor having a rotor in which a detecting magnet is incorporated and a rotating magnet and a rotating shaft are integrally formed. However, there is no disclosure of a technical idea of a thin motor.

Japanese Patent Application Laid-Open No. 63-59757 discloses an electric motor in which a disk holding surface is formed integrally with a yoke of a rotor. However, here, too, there is nothing to disclose about thinning of the electric motor.

Further, the technology disclosed in Japanese Patent Application Laid-Open No. 63-18951 discloses a technology of a thin motor having a small thickness, but a disk mounting function, a magnetic field for detecting the number of rotations and a rotation position of a rotor, and the like. No technical idea is disclosed that the manufacturing operation of the rotor that generates simplification can be simplified.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a thin motor having a small thickness and a disk mounting function, a rotor for generating a magnetic field for detecting the number of rotations and a rotation position of the rotor can be easily manufactured. Things.

[Means for Solving the Problems] The electric motor according to the present invention includes a rotating shaft rotatably supported, and a ring-shaped driving magnet which rotates integrally with the rotating shaft and generates a magnetic field on an outer peripheral portion. Provided in the motor, comprising: a stator having a plurality of coils wound around a stator core, the rotor being located outside the rotor, wherein the rotor comprises a plastic magnet. A disk mounting surface for mounting a disk, a rotation speed detection surface that generates a magnetic field for detecting rotation speed, and an index detection surface that generates a magnetic field for index detection facing the index detection element arranged on the frame It is formed by molding.

[Operation] In the present invention, a disk mounting surface for mounting a disk, a rotation speed detection surface for detecting a rotation speed, and an index detection surface for detecting an index are integrally formed with a rotating body made of a plastic magnet of a rotor. Therefore, the rotor generates a magnetic field for detecting the disk mounting function, the number of rotations and the rotational position of the rotor, and furthermore, the rotor can be easily manufactured and the number of working steps can be reduced.

[Example] Hereinafter, an example of the present invention will be described.

FIG. 1 is a sectional view showing an electric motor according to one embodiment of the present invention, and FIG. 2 is a plan view of a rotor of the electric motor according to one embodiment of the present invention as viewed from a frame side.

In the figure, 21 is a rotating shaft of an electric motor, 22 is a rotating body made of a plastic magnet having a magnetic disk holding function, and this rotating body 22 rotates integrally with the rotating shaft 21. 23 is a disk mounting surface formed on the rotating body 22, 24 is a rotor yoke embedded in the rotating body 22, 25 is a rotor yoke 24
A driving magnet 26 composed of a permanent magnet disposed on the outer periphery of the rotating disk 22 has a driving pin mounted on the rotating body 22. The driving pin 26 has a window hole (not shown) of a rotating plate mounted on the magnetic disk. ). Reference numeral 27 denotes a rotation speed detection surface that generates a magnetic field for detecting the rotation speed, and 28 denotes an index detection surface that generates a magnetic field for detecting the index. The disk mounting surface 23, the rotational speed detecting surface 27, and the index detecting surface 28 are integrally formed with the rotating body 22. Reference numeral 29 denotes an arm plate made of a rigid body that supports the drive pin 26, and reference numeral 30 denotes a support member that supports the end of the arm plate 29 so as to be movable by the rotating body 22. 31 is a stator core, and 32 is a coil wound around the stator core 31. The rotor core 31 and the coil 32 constitute a stator of the electric motor. 40 is a frame that also serves as a circuit board, 41 is a frame
A bearing mounting member mounted on 40, 42 is a sintered oil-impregnated bearing that rotatably supports the rotating shaft 21, 43 is a sliding member having a low coefficient of friction interposed between the rotating body 22 and the sintered oil-impregnated bearing 42 It is. 47
Numeral denotes an index detecting element disposed on the frame 40, and outputs a signal for index detection by facing the index detecting surface 28. Reference numeral 50 denotes a magnetic shielding plate made of a ferromagnetic electromagnetic shielding material such as an iron plate, which covers an exposed portion of a coil 32 wound around a stator core 31 and a disk mounting surface 23 of a rotor driving magnet 25. Cover the exposed side.

The motor of this embodiment is configured as described above,
The stator core 31 is capable of transmitting magnetic flux in the direction of the radius of rotation of the electric motor, and forms iron core teeth for 15 angles of the entire circumference divided into 18 equal angular intervals, and 15 coils 32 are formed. It is wound. The outer peripheral surface of the iron core at a position corresponding to the three iron core teeth is concave toward the inner peripheral surface, and the inner peripheral surface is connected by the iron core. The concave portion is for the magnetic head to move without interfering with the stator. The driving magnet 25 of the rotor located on the inner peripheral side of the stator is
For example, the N and S poles are magnetized in the direction of the radius of rotation of the rotor at 24 equal intervals on the entire circumference. Fifteen coils 32 of the stator are wound every three coils in three phases, and are energized by 120 degrees according to the rotation angle of the rotor to generate a rotation torque in a certain direction.

As described above, the electric motor of this embodiment is of the inner rotor type in which the stator is located outside the rotor, and the stator is formed with the concave portion for moving the magnetic head, and the conventional outer rotor type is used. Since the gap for avoiding the interference between the stator and the rotor and the magnetic disk and the magnetic head as in the electric motor described above can be omitted, the thickness of the entire electric motor can be reduced.

Moreover, in this embodiment, the rotor is provided with a rotor yoke 24 made of a ferromagnetic material on the inner peripheral surface of the rotor driving magnet 25, and a disk mounting surface 23 is provided inside the rotor yoke 24.
Are supported by the rotating body 22. The rotor yoke 24 has a rotational speed detecting surface 27 formed by multipolar magnetization in the axial direction, and further has an index detecting surface inside thereof.
Has 28. The disk mounting surface 23, the rotational speed detecting surface 27, and the index detecting surface 28 of this rotor are all made of a plastic magnet made of the same material. Similarly, the rotating body 22 is also made of a plastic magnet, and these are the rotor yoke 24 and the rotating shaft. It is integrally molded with 21. Therefore, the manufacture of the rotor can be simplified as compared with the conventional example, and the number of work steps can be reduced.

When an electric motor having a rotor of this configuration is used in a disk device, a magnetic disk mounting surface is used.
A metallic rotating plate (not shown) fixed to the center of the magnetic disk is attracted to the magnetic disk 23 and rotates integrally with the rotor. In addition, the rotation speed detection surface 27 by multipolar magnetization has a magnetization pattern for FG for detecting the rotation speed and rotation angle of the rotor, and is separated from the rotation speed detection surface 27 by a slight gap. On the surface of the frame 40, an FG detection pattern (not shown) is formed by printed wiring. Then, a rotation signal proportional to the rotation speed is output by the rotation speed detection surface 27 and the opposing FG detection pattern (not shown). Further, the index detection surface 28 outputs an index detection signal for detecting the magnetic pole position of the rotor by facing the index detection element 47. It should be noted that the detection of the number of revolutions and the detection of the index employ a known technique.

As described above, the motor of this embodiment is a sintered oil-impregnated bearing.
The rotating shaft 21 rotatably supported by 42 and the previous rotating shaft
A rotor in which a ring-shaped driving magnet 25 that rotates integrally with and generates a magnetic field in the direction of the radius of rotation on the outer peripheral portion is disposed, and a plurality of stator cores 31 are located outside the rotor and are disposed outside the rotor. A stator on which a coil 32 is wound, a disk mounting surface 23 for mounting a disk integrally formed with a rotating body 22 made of a plastic magnet of the rotor, and a rotational speed detecting unit integrally formed with the rotating body 22 Speed detection surface that generates a magnetic field
27, and an index detection surface 28 that generates a magnetic field for index detection that is formed integrally with the rotating body 22.

That is, the electric motor of this embodiment has a disk mounting surface 23 for mounting a disk, a rotational speed detecting surface 27 for detecting a rotational speed, and an index detecting surface 28 for detecting an index. It is integrally molded. Therefore, the rotor has a disk mounting function,
A magnetic field is generated for detecting the number of rotations and the rotational position of the rotor, and the manufacturing work of the rotor is simplified and the number of man-hours can be reduced as compared with the conventional example. become. As a result, a thin motor having a small thickness can be manufactured at low cost.

By the way, in the above-described embodiment, the disk mounting surface 23, the rotation speed detecting surface 27, the index detecting surface 28, and the rotating body 22 are integrally formed, but in addition, the driving magnet 25 is also integrally formed. Is also good.

[Effects of the Invention] As described above, the present invention relates to a rotor having a ring-shaped driving magnet that rotates integrally with a rotatably supported rotating shaft and generates a magnetic field on an outer peripheral portion. In a motor having a stator positioned outside and having a plurality of coils wound around a stator core, the rotor has a disk mounting surface for mounting a disk integrally formed on a rotating body made of a plastic magnet. A rotation number detection surface that generates a rotation number detection magnetic field integrally formed with the rotating body;
The rotor has a disk mounting function, a rotation function, and a simple structure including an index detection surface which is integrally formed with the rotating body and generates a magnetic field for index detection facing the index detection element disposed on the frame. Since a magnetic field for detecting the number of rotations and the rotation position of the rotor is generated, and the rotor can be manufactured easily and the number of working steps can be reduced, a thin and thin motor can be manufactured at low cost. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an electric motor according to one embodiment of the present invention, FIG. 2 is a plan view of a rotor of the electric motor according to one embodiment of the present invention, as viewed from a frame side, FIG. 3 is a sectional view showing a conventional electric motor. In the figure, 21: rotating shaft, 22: rotating body 23: disk mounting surface, 24: rotor yoke 25: driving magnet, 27: rotation detecting surface 28: index detecting surface 31: stator core, 32: coil 41: bearing Mounting member, 42: sintered oil-impregnated bearing 47: index detecting element. In the drawings, the same reference numerals and symbols indicate the same or corresponding parts.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-59757 (JP, A) JP-A-63-18951 (JP, A) JP-A-62-12364 (JP, A) JP-A-51- 69109 (JP, A) Fully open, 55-143675 (JP, U) Fully open, 51-155309 (JP, U)

Claims (1)

(57) [Claims] A rotor provided with a rotatable shaft rotatably supported thereon, a ring-shaped driving magnet which rotates integrally with the rotation shaft and generates a magnetic field on an outer peripheral portion, and the rotor. And a stator having a plurality of coils wound around a stator core, wherein the rotor comprises a rotating body made of a plastic magnet, a disk mounting surface for mounting a disk, and a rotation speed. An electric motor comprising: a rotation speed detection surface for generating a magnetic field for detection; and an index detection surface for generating a magnetic field for index detection facing an index detection element disposed on a frame.