JPH11332202A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle motor which shows high productivity even if the vibration-proof structure of an armature is provided in it. SOLUTION: The armature 11 of a spindle motor 1 is molded with resin so as to have the outer circumferences of the salient poles 72 of a stator core 7 and coils 12 wound on the salient poles 72 covered with a resin layer 8 and, further, have open slots between the salient poles filled with the resin layer 8. The inner circumferential surface 711 and lower surface side inner circumferential part 714 of the stator core 7 which are brought into contact with a frame 2 protrude from the inner circumferential edge 83 of the resin layer 8 toward the inner side in a radial direction. The tip surfaces 731 of the salient poles of the stator core 7 protrude from the outer circumferential edge 84 of the resin layer 8 toward the outer side in a radial direction. As the armature 11 only can be molded with resin, the armature 11 molded with resin beforehand can be attached to the frame 2. Therefore, the productivity of the motor 1 can be improved in comparison with the productivity in the case that resin is applied after the armature 11 is attached to the frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor used as, for example, a rotary drive of a hard disk. More specifically, the present invention relates to an anti-vibration structure for an armature mounted on a spindle motor.

[0002]

2. Description of the Related Art A spindle motor used as a rotary drive of a hard disk is provided with a hub (rotor) rotatably supported by a frame, a rotor magnet mounted on the hub, and a frame mounted so as to face the rotor magnet. It has a held armature. This armature includes a stator core having a plurality of radially extending salient poles, and a coil wound around the salient poles, and a tip end surface of the salient pole faces the rotor magnet.

In the spindle motor having this configuration, when the salient poles of the armature vibrate due to a change in the magnetic field between the rotor magnet and the armature during driving of the motor, the vibration is transmitted to the entire motor through the frame, and the switching noise increases. There's a problem. Therefore, Japanese Patent Application Laid-Open No. 9-2756
No. 59 and Utility Model Registration No. 2549057, the resin is filled between the salient poles of the stator core and between the lower end face of the stator core and the bottom plate of the frame, thereby lowering the armature. A structure is adopted in which the side halves are resin-molded and the rigidity thereof is increased to prevent vibration of the armature.

[0004]

However, in such an armature anti-vibration structure, the resin is filled between the armature and the frame, so that the operation of filling the resin is performed by mounting the armature on the frame. You can do it only after you have done it. Therefore, there is a problem that workability at the time of assembling the motor is poor.

[0005] In view of the above problems, an object of the present invention is to provide:
An object of the present invention is to provide a spindle motor with high productivity even if it has an armature anti-vibration structure.

[0006]

In order to solve the above-mentioned problems, the present invention provides a frame, a rotor rotatably supported on the frame, a rotor magnet mounted on the rotor, and the rotor In a spindle motor having an armature held by the frame so as to face a magnet, the armature is fitted to a core holder of the frame and has an annular base contacting a positioning step of the core holder. A stator core having a plurality of salient poles extending radially from the base and having a distal end surface facing the rotor magnet; a coil wound around the salient pole; a contact portion of the stator core with the core holder portion; A resin layer that covers the periphery of the salient pole and the coil and fills an open slot between the salient poles while exposing the tip side of the salient pole. Characterized in that it comprises a.

In the present invention, the salient poles and coils of the armature are covered with the resin layer, and the open slots are filled with the resin layer to connect the plurality of salient poles with the resin layer. be able to. Therefore, the vibration of the armature caused by the fluctuation of the magnetic field between the armature and the rotor magnet when the motor is driven can be reduced, so that the switching noise can be reduced. In this way, the entire periphery of the salient poles and the coil of the armature is covered with resin, and the resin is filled in the open slot, so that the lower half of the armature is filled by filling the resin between the armature and the frame. The effect of reducing the vibration is high as compared with the conventional structure in which the resin is molded. Further, unlike the conventional structure in which resin is filled between the armature and the frame, the armature alone can be resin-molded. Therefore, when assembling the motor, the armature that has been resin-molded in advance may be mounted on the frame.
The productivity of the motor can be increased as compared with the conventional method of filling the resin after the armature is mounted on the frame. Furthermore, even if the armature is molded in advance with resin, the contact portion between the stator core and the frame is exposed from the resin, so that the dimensional accuracy of this portion remains high. Therefore, even if the armature having a structure in which the annular base of the stator core is fitted into the core holder of the frame and the base is brought into contact with the positioning step of the core holder is resin-molded, the armature is higher than the frame. Can be mounted with precision. Further, since the tip end surface of the salient pole facing the rotor magnet is also exposed from the resin, the outer diameter of the stator core remains high in accuracy. Therefore, the gap between the rotor magnet and the front end surface of the salient pole can be reduced to the limit as compared with the case where the front end surface of the salient pole is covered with the resin.
Therefore, the efficiency of the magnetic circuit between the rotor magnet and the armature can be increased, so that the torque of the motor can be improved.

In the present invention, it is preferable that a terminal of the coil is led out of the resin layer and wired to a connection terminal of a wiring member fixed to the frame.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

(Overall Structure) FIG. 1 is a half sectional view showing a spindle motor according to the present invention. In FIG. 1, a spindle motor 1 is used as a rotary drive of a hard disk, and includes a frame 2, a shaft 3 extending upward from the center of the frame 2, and first and second shafts 3 supported by the shaft 3. It has ball bearings 5 and 6 and a hub 4 (rotor) rotatably supported on the shaft 3 via the first and second ball bearings 5 and 6.

The frame 2 has a thick cylindrical central portion 21.
An annular bottom portion 22 extending horizontally from the central portion 21;
An outer peripheral cylindrical portion 23 rising from the outer peripheral edge of the bottom portion 22;
A flange portion 24 is provided which protrudes outward from an upper end portion of the outer peripheral cylindrical portion 23. A core holder portion 25 formed of an annular protrusion is formed on the outer peripheral side of the central portion 21, and the armature 11 is mounted on an outer peripheral surface 251 of the core holder portion 25. The central portion 21 has a lower end portion 33 of the shaft 3.
Has been fixed.

The hub 4 has a body 41 formed in a thick cylindrical shape.
It has. The middle part of the body 41 is a step 42 projecting outward.
1 is a mounting surface of the hard disk. A projecting portion 43 projecting further outward is formed at the lower end of the body portion 41, and a cylindrical portion 44 extends downward from the outer peripheral edge of the projecting portion 43. Outer peripheral surface 4 of cylindrical portion 44
Reference numeral 41 denotes a labyrinth seal that faces the inner peripheral surface 231 of the outer cylindrical portion 23 of the frame 2 at a small interval. A cylindrical rotor magnet 15 is provided on the inner peripheral surface 442 of the cylindrical portion 44 via the cylindrical yoke 14.
It is attached so as to face 1.

The inner ring 51 of the first ball bearing 5 is bonded to the upper end 31 of the shaft 3, and the inner ring 61 of the second ball bearing 6 is bonded to the lower end 33 of the shaft 3. ing. Second ball bearing 6
Is mounted on the upper surface 212 of the central portion 21 formed in the frame 2. Also, the upper surface 2 of the central portion 21
An annular concave portion 213 is formed in the second ball bearing 12 so that the outer ring 62 of the second ball bearing 6 does not contact the upper surface 212 of the central portion 21. The inner peripheral surface 252 of the core holder portion 25 protruding from the outer periphery of the concave portion 213 faces the outer peripheral surface 621 of the outer ring 62 of the second ball bearing 6 at a very small interval to form a labyrinth seal.

On the other hand, a bearing holding hole 410 is formed inside the body 41 of the hub 4. Bearing holding hole 410
A step 45 protruding inward is formed on the inner peripheral surface 411 of the. The outer ring 52 of the first ball bearing 5 is mounted on the upper annular end surface 451 of the step 45, and the outer ring 62 of the second ball bearing 6 abuts on the lower annular end surface 452 of the step 45. . In this state, the outer rings 52, 62 of the first and second ball bearings 5, 6 are bonded to the inner peripheral surface 411 of the bearing holding hole 410.

The inner peripheral surface 4 of the bearing holding hole 410
A seal member 16 for preventing lubricating oil or the like added to the first ball bearing 5 from scattering to the outside of the motor is mounted above a portion of the motor 11 where the first ball bearing 5 is mounted. I have.

(Armature 11) FIG.
2B is a cross-sectional view taken along line II ′ of FIG. 2A. 1 and 2 (A), (B)
As shown in FIG. 1, the armature 11 includes a stator core 7 and a coil 12 wound around the stator core 7.

The stator core 7 is formed by laminating a plurality of core plates 70 having the same shape and fixing them by caulking. The stator core 7 protrudes radially from an annular base 71 and an outer peripheral surface 712 of the base 71. A plurality of salient poles 72 are provided, and a flange portion 73 that extends in the circumferential direction at the tip of each salient pole 72 is provided. The coil 12 is wound around each salient pole 72.

The base 72 is a mounting portion for the frame 2. That is, the annular core holder 25 formed in the frame 2 is fitted into the central hole 710 of the base 72, the inner peripheral surface 711 of the central hole 710 abuts the outer peripheral surface 251 of the core holder 25, and the lower end surface of the base 71. Of the core holder 25 abuts on the positioning step 214 projecting from below the core holder 25. The adhesive 18 is applied between the upper inclined surface 253 of the core holder 25 and the inner peripheral surface 711 of the central hole 710, and the armature 11 is fixed to the frame 2.

The distal end surface 731 (the outer peripheral surface of the flange portion 73) of each salient pole 72 of the armature 11 mounted as described above faces the inner peripheral surface 151 of the rotor magnet 15 with a gap.

Here, in the spindle motor 1 of the present embodiment, the armature 11 and the rotor magnet 15 are driven when the motor is driven.
The armature 11 is resin-molded in order to prevent the salient poles 72 of the armature 11 from vibrating due to the fluctuation of the magnetic field between the armature 11 and the armature 11.

FIG. 3A is a plan view showing a state in which the armature 11 is resin-molded, and FIG.
FIG. 2 is a sectional view taken along line II ′. As shown in FIGS. 3A and 3B, the armature 11 is covered with a resin layer 8 of, for example, polycarbonate. This resin layer 8 comprises an armature 11
Is formed in an annular shape. That is, the resin layer 8
Is a portion 81 covering the periphery of each salient pole 72 of the stator core 7 and the coil 12 wound around each salient pole 72;
The portions 82 filled in the open slots 720 between the two are alternately continuous, and have a ring shape as a whole. The vertical cross-sectional shape of the resin layer 8 is formed in a substantially rectangular shape that thinly covers the periphery of the coil 12.

The inner peripheral side of the stator core 7 projects radially inward from the inner peripheral edge 83 of the resin layer 8. Therefore, the inner peripheral surface 711 (abutting portion) of the base 71 abutting on the outer peripheral surface 251 of the core holder 25 formed on the frame 2 and the positioning step 214 projecting from below the core holder 25 abut. The inner peripheral portion 714 (contact portion) on the lower end side of the base 71 is in a state of being exposed from the resin layer 8.

Further, on the outer peripheral side of the stator core 8, the distal end surface 731 (the outer peripheral surface of the flange portion 73) of each salient pole 72 slightly protrudes radially outward from the outer peripheral edge 84 of the resin layer 8,
It is exposed from the resin layer 8.

The terminal 121 of the coil 12 is directly led out of the resin layer 8. Terminal 121 of this coil 12
1, a connector 17 (wiring member) is attached to the bottom plate 22 of the frame 2 as shown in FIG. The connector 17 includes a base 173 fixed to the lower surface of the bottom plate 22 and a cylindrical projection 174 protruding from the base 173 and inserted into a through hole 215 formed in the bottom plate 22.
It has. The terminal 121 of the coil 12 is
It is drawn out of the motor through a coil terminal guide hole 171 formed in 74 and is electrically connected to a connection terminal 172 attached to a base 173 of the connector 17.

As described above, the spindle motor 1 of this embodiment
Here, the entire periphery of the salient poles 72 and the coil 12 of the armature 11 is covered with the resin layer 8, and the open slots 720 are filled with the resin layer 8 to connect the plurality of salient poles 72 with the resin layer 8. Therefore, since the rigidity of the armature 11 can be increased, the vibration of the armature 11 caused by the fluctuation of the magnetic field between the armature 11 and the rotor magnet 15 when the motor is driven can be reduced. Therefore, switching noise of the spindle motor 1 can be reduced.

Further, unlike the conventional structure in which the resin is filled between the armature and the frame, the armature 11 can be resin-molded by itself. 2 only needs to be attached. Therefore, the productivity of the motor can be increased as compared with the conventional method of filling the resin after mounting the armature on the frame.

Further, when the armature 11 is mounted on the frame 2, the inner peripheral surface 711 of the base 71 which comes into contact with the frame 2,
The inner peripheral portion 714 on the lower end side of the base 71 is
, The dimensional accuracy of these parts remains high. Accordingly, the armature 11 has a structure in which the annular base 71 of the stator core 7 is fitted into the core holder 25 of the frame 2, and the inner peripheral portion 714 on the lower end side of the base 71 is brought into contact with the positioning step 214 of the core holder 25. , The armature 11 can be attached to the frame 2 with high accuracy.

Furthermore, since the tip end surface 731 of the salient pole 72 facing the rotor magnet 15 is also exposed from the resin layer 8, the outer diameter of the stator core 7 remains highly accurate. Therefore, compared to the structure in which the distal end surface 731 of the salient pole 72 is covered with resin, the resin layer 8
Therefore, the gap G between the inner peripheral surface 151 of the rotor magnet 15 and the distal end surface 731 of the salient pole 72 can be reduced to the limit. Therefore, the efficiency of the magnetic circuit between the rotor magnet 15 and the armature 11 can be increased, and the torque of the spindle motor 1 can be improved.

(Results of Measurement of Noise) Next, results of measurement of noise due to vibration generated when the conventional motor and the motor 1 of the present embodiment are driven will be described.

FIG. 4A is a graph showing noise when a conventional motor whose armature is not covered with resin is driven.
FIG. 4B is a graph showing noise when driving a conventional motor in which resin is filled between the armature and the bottom plate of the frame and the lower half of the armature is resin-molded, and FIG. 6 is a graph showing noise when the motor 1 is driven.
In these figures, the horizontal axis indicates the frequency of the noise waveform, and the vertical axis indicates the amplitude of the noise waveform. FIG. 4 (A)
4B and the solid line L2 shown in FIG. 4B, as can be seen, the amplitude of the noise waveform (solid line L2) of the motor in which the lower half of the armature is resin-molded is as follows. The noise waveform of the motor that has not been used (solid line L
The amplitude is smaller than 1). As described above, even if the lower half of the armature is simply resin-molded, there is an effect of reducing noise, but the solid line L2 shown in FIG.
As can be seen by comparing the solid line L shown in FIG. 5, the amplitude of the noise waveform (solid line L) of the motor 1 of the present embodiment is larger than the amplitude of the noise waveform (solid line L1) of the motor in which the lower half of the armature is resin-molded. , Is even smaller. Therefore, like the spindle motor 1 of the present embodiment, the salient poles 72 of the armature 11
The armature 11 is covered so that the entire periphery of the coil 12 is covered with resin, and the open slot 720 is filled with resin.
Is more effective in reducing noise (vibration) than the conventional structure in which the lower half of the armature is resin-molded.

(Another Embodiment) In the above embodiment,
The terminal 121 of the coil 12 is connected to the connector 17 fixed to the bottom plate 22 of the frame 2.
The terminal 121 of the coil 12 may be electrically connected to a wiring board 17A (wiring member) attached to the lower surface of the bottom plate 22, as in the motor 1A shown in FIG. In this case, coil 1
The resin 19 may be filled in a through hole 215 formed in the bottom plate 22 so that the second terminal 121 passes therethrough.

[0032]

As described above, in the spindle motor of the present invention, the entire periphery of the salient poles and the coil is covered with the resin layer, and the open slots are filled with the resin layer to connect the plurality of salient poles with the resin layer. Since the armature is resin-molded, the rigidity of the armature can be increased. Therefore, the vibration of the armature caused by the fluctuation of the magnetic field between the armature and the rotor magnet when the motor is driven can be reduced, so that the switching noise can be reduced. Also, unlike the conventional structure in which resin is filled between the armature and the frame, the armature can be resin-molded as a single unit.When assembling the motor, simply attach the resin-molded armature to the frame in advance. Good. Therefore,
The productivity of the motor can be increased as compared with the case where the resin is filled after the armature is mounted on the frame. further,
Since the contact portion between the armature and the frame is exposed from the resin, the mounting accuracy of the armature to the frame can be improved. Furthermore, since the distal end surface of the salient pole facing the rotor magnet is also exposed from the resin, the gap between the rotor magnet and the distal end surface of the salient pole can be narrowed, and the torque of the motor can be improved.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a spindle motor to which the present invention is applied.

2A is a plan view showing an armature of the motor shown in FIG. 1, and FIG. 2B is a cross-sectional view taken along line II ′ of FIG. 2A.

3A is a plan view showing a state in which the armature of the motor shown in FIG. 1 is resin-molded, and FIG.
FIG. 2 is a sectional view taken along line II ′.

FIG. 4A is a graph showing noise of a conventional motor whose armature is not covered with resin, and FIG. 4B is a graph showing noise of a conventional motor in which the lower half of the armature is resin-molded. It is.

FIG. 5 is a graph showing noise of the motor shown in FIG. 1;

FIG. 6 is a half sectional view showing a spindle motor according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1A Spindle motor 2 Frame 3 Fixed shaft 4 Hub (rotor) 7 Stator core 8 Resin layer 11 Armature 12 Coil 15 Rotor magnet 17 Connector (wiring member) 17A Wiring board (wiring member) 25 Core holder part 71 Base 72 Salient pole 121 Terminal of coil 214 Positioning step 251 Outer peripheral surface of core holder 172 Connection terminal 711 Inner peripheral surface of base (contact portion) 712 Outer peripheral surface of base 714 Inner peripheral portion of base (contact portion) 720 Open slot 731 Salient pole Tip face of

Claims (2)

[Claims] 1. A frame, a rotor rotatably supported on the frame, a rotor magnet mounted on the rotor, and an armature held by the frame so as to face the rotor magnet. In the spindle motor, the armature is fitted in a core holder of the frame, and has an annular base that abuts a positioning step of the core holder. The armature radially extends from the base and has a front end face facing the rotor magnet. A stator core having a plurality of salient poles, a coil wound around the salient pole, a contact portion of the stator core with the core holder portion, and the salient pole and the coil with a tip end side of the salient pole exposed. A resin layer that covers the periphery of the motor and fills the open slots between the salient poles. 2. The spindle motor according to claim 1, wherein a terminal of the coil is led out of the resin layer and wired to a connection terminal of a wiring member fixed to the frame.