JPH08228465A - Spindle motor - Google Patents

Abstract

PURPOSE: To increase producibility without needing pressing jigs and also reduce rotation inequality and a rotation loss. CONSTITUTION: This spindle motor comprises: a frame 12; a stator core 3 fixed to the frame 12 winding a coil 4; and a hub for rotating a drive magnet opposing this stator core 3. The frame 12 has a core fixing part 20 comprising a first fixing part 21 and a second fixing part 22, and the first fixing part 21 has a large diameter part 21b and a small diameter part 21a formed on a peripheral surface, and the stator core 3 is lightly pressed into the large diameter part 21b, and further adhesives 24 fill a space P between the small diameter part 21a and the inner peripheral surface of the stator core 3, and the second fixing part 22 comprises a horizontal end surface for the axial direction and abuts against one end surface of the stator core 3 to support the stator core 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a spindle motor used in a hard disk drive device or the like. More specifically, it relates to a fixing structure for the frame and the stator core.

[0002]

2. Description of the Related Art As a conventional spindle motor, there is, for example, US Pat. No. 5,407,677, the structure of which is shown in FIG. In FIG. 4, a frame 1 is a fixed support portion having a portion attached to a hard disk drive device, and a fixed shaft 6 is provided upright in the center thereof. Ball bearings 13 and 1 each having an inner ring fitted to the fixed shaft 6.
4 are arranged at appropriate intervals. A stator core 3 having a plurality of radially projecting salient poles is fixed to the frame 1. An insulating resin is applied to the surface of the stator core 3, and coils 4 are wound around the salient poles. On the other hand, the outer rings of the ball bearings 13 and 14 are fitted and fixed in the inner holes of the cylindrical hub 15. Therefore, the hub 15 is rotatably supported by the ball bearings 13 and 14 with respect to the fixed shaft 6. The hub 15 has a flange portion on the lower end side for mounting a disk such as a hard disk, and a cylindrical yoke 16 is fixed to the lower end surface of this flange portion. A ring-shaped drive magnet 17 is mounted on the inner peripheral surface of the yoke 16, and the drive magnet 17 faces the salient poles of the stator core 3 at an appropriate interval. When a current is passed through the coil 4, the hub 15 and the disk rotate due to the electromagnetic action of the stator core 3 and the drive magnet 17.

A procedure for fixing the stator core 3 to the frame 1 in the spindle motor shown in FIG. 4 will be described with reference to FIG. As shown in FIG. 5A, a central hole 3a is formed in the stator core 3 around which the coil 4 is wound. Then, after inserting the shaft 6 into the central hole 3a, the stator core 3 is moved in the direction of the arrow to move the frame 1
The lower end surface of the stator core 3 is brought into contact with the stepped portion 7 formed in. At this time, as shown in FIG.
A gap s of about 0.1 mm is formed between the inner peripheral surface of the central hole 3a and the outer peripheral surface 10 of the frame 1. That is,
Although the stator core 3 is inserted into the frame 1, the stator core 3 is not fixed to the frame 1 at this stage.

When the stator core 3 is fixed to the frame 1, the upper portion of the coil 4 is pressed by the pressing jig 9 as shown in FIG.
Hold horizontally to the axis. That is, the stator core 3 and the drive magnet 17 facing the stator core 3 are concentric in the radial direction, and the axial center of the stator core 3 and the center of the drive magnet 17 are aligned in the axial direction. So that the holding jig 9
Is used to hold the stator core 3.

With the stator core 3 held in this manner, the ultraviolet curable adhesive 8 is filled in the gap s between the frame 1 and the stator core 3 and in the vicinity thereof. After the adhesive 8 is filled, ultraviolet rays are irradiated from an ultraviolet irradiator (not shown) to cure the adhesive 8, and the frame 1 and the stator core 3 are completely fixed. In addition, as a matter of course, until the adhesive 8 is cured, the pressing jig 9
The upper part of the coil 4 is pressed by.

The adhesive 8 may be applied to the outer peripheral surface 10 of the frame 1 in advance before the stator core 3 is inserted. Further, Japanese Patent Laid-Open No. 1-295653 discloses a method of press-fitting and fixing the stator core 3 into the frame 1.

[0007]

As described above, the gap s is formed between the frame 1 and the stator core 3, and the ultraviolet curing adhesive 8 is applied to the gap s to fix the stator core 3 to the frame 1. In the fixing method, since the holding jig 9 must be held until the ultraviolet curable adhesive 8 is completely hardened, not only the manufacturing process becomes complicated, but also depending on the number of the holding jigs 9. The production capacity is limited and the productivity is getting worse.

Further, since the pressing jig 9 must be held until the ultraviolet curing adhesive 8 filled in the gap s is completely hardened, the center of the fixed shaft 6 erected on the frame 1 It is difficult to align the centers of the stator cores 3 with each other, and as shown in FIG. 6, the centers may be displaced from each other. As a result, the stator core 3
Since the salient poles and the drive magnet 17 are unevenly spaced, uneven rotation and loss occur when the motor is rotationally driven.

Further, in the method of press-fitting the stator core 3 into the frame 1 as in Japanese Patent Laid-Open No. 1-295653,
Since the amount of plastic deformation of the frame 1 is large, the distortion remains in the frame 1. That is, frame 1
Is distorted, the mounting accuracy of the components mounted on it deteriorates, which in turn adversely affects the rotation characteristics of the motor.

The present invention has been made in order to solve the problems of the prior art as described above, and provides a fixing structure for the stator core 3 and the frame 1 which can improve the productivity without the need for a pressing jig. It is the one we are trying to provide. In addition, the center of the frame 1 and the fixed shaft 6 and the stator core 3
The objective is to realize a spindle motor that matches the centers of and, and has less uneven rotation and loss.

[0011]

To achieve the above object, in a spindle motor according to a first aspect of the present invention, a frame, a stator core wound with a coil and fixed to the frame, and a drive magnet facing the stator core are provided. A frame having a core fixing portion including a first fixing portion and a second fixing portion, and the first fixing portion has a large diameter portion formed on a peripheral surface. And a small diameter portion, the stator core is lightly press-fitted into the large diameter portion, and an adhesive is filled in a gap between the small diameter portion and the inner peripheral surface of the stator core.
The fixed portion is composed of an end face that is horizontal with respect to the axial direction, and contacts the one end face of the stator core to hold the stator core.

According to the invention described in claim 2,
In the described spindle motor, the adhesive is a thermosetting adhesive. Further, in the invention according to claim 3,
The spindle motor according to claim 1, wherein the adhesive is
It is used as a moisture-curable adhesive.

According to the invention described in claim 4,
In the described spindle motor, the stepped portion between the large diameter portion and the small diameter portion is inclined toward the second fixed portion side. Further, in the invention described in claim 5, in the spindle motor according to claim 1, the large-diameter portion is projected from the small-diameter portion toward the outer side in the radial direction over the entire circumference. In addition, in the invention according to claim 6, in the spindle motor according to claim 1, the large-diameter portion is projected from the small-diameter portion to a plurality of positions outward in the radial direction. Further, in the invention according to claim 7, in the spindle motor according to claim 1, an adhesive reservoir to which an adhesive is applied is formed in a portion of the frame facing the stator core.

Further, in the spindle motor according to the present invention, a frame, a stator core around which a coil is wound and which is fixed to a core fixing portion formed on the frame, and a drive magnet facing the stator core are provided for rotation. Hub, a stator core, a positioning portion that is lightly press-fitted into the core fixing portion and positioned with respect to the frame, and a gap that is formed between the core fixing portion and the stator core and that is filled with an adhesive. It is lightly press-fitted, the gap is filled with an adhesive, and the stator core is fixed to the core fixing portion.

Further, in the invention described in claim 9, in the spindle motor according to claim 8, there is an adhesive reservoir formed between the core fixing portion and the stator core, and the adhesive is applied to the core. The glue and the gap are filled with the adhesive. In addition, in the invention described in claim 10, in the spindle motor according to claim 8, the adhesive is a thermosetting adhesive. Furthermore, in the invention described in claim 11, in the spindle motor according to claim 8, the adhesive is a moisture-curable adhesive.

In the spindle motor of the present invention, the core fixing portion is formed on the frame. Then, the stator core is lightly press-fitted into this core fixing portion. The frame has a first fixing portion and a second fixing portion that serve as positioning portions, and the stator core is lightly press-fitted into the large-diameter portion of the first fixing portion. After that, the gap formed between the core fixing portion and the stator core, specifically, the gap between the small diameter portion of the first fixing portion and the inner peripheral surface of the stator core is filled with the adhesive. Since the stator core is fixed to the frame in this way, the pressing jig that has been conventionally required is not necessary, and the center of the stator core and the center of the frame and the fixed shaft are surely aligned with each other. Can be assembled.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Referring to FIGS. 1 to 3,
An embodiment of the present invention will be described.

FIG. 1A is a half sectional view of an embodiment of a spindle motor of the present invention, showing a state in which a stator core 3 is fixed to a frame 12. Figure 1 (B)
It is a principal part enlarged view of FIG. 1 (A). It should be noted that the description of the members of the spindle motor of the present invention having the same structure as the conventional spindle motor shown in FIGS. 4 to 6 will be omitted.

In FIG. 1, the frame 12 is made of an aluminum alloy, a zinc alloy, or the like. The frame 12 has a core fixing portion 20 having a first fixing portion 21 and a second fixing portion 22. The first fixing portion 21 and the second fixing portion 22 constitute a positioning portion.

The first fixing portion 21 has a small diameter portion 21a and a large diameter portion 21b formed on the peripheral surface, and the small diameter portion 21
The centers of a and the large-diameter portion 21b coincide with the center of the fixed shaft 6 erected on the frame 12. And the large diameter portion 21
In this embodiment, the outer diameter of b is larger than the inner diameter of the central hole 3a of the stator core 3 by about 0.002 mm to 0.010 mm. Further, the axial length of the light press-fitting portion of the stator core 3 is 0.6 mm to 0.7 mm. Further, the step portion 23 between the small diameter portion 21a and the large diameter portion 21b is the second
The taper surface is inclined toward the fixed portion 22 side.

On the other hand, the second fixing portion 22 is the frame 12
The end surface is horizontal with respect to the standing direction of the fixed shaft 6 that is erected on the. Further, a portion (upper part in the drawing) where the frame 12 faces the stator core 3 has an inclined tapered surface 26, and an adhesive reservoir 25 is formed. The adhesive pool 25 is adapted to facilitate application of the adhesive 24, which will be described later, and the excess adhesive 24 applied.
Are not scattered. Further, since the adhesive area of the adhesive 24 is increased, the adhesive strength is also increased.

A coil 4 is wound around the stator core 3. The stator core 3 is lightly press-fitted into the large diameter portion 21b of the first fixing portion 21 of the frame 12, and
A part of the lower end surface of the stator core 3 comes into contact with the second fixing portion 22, so that the stator core 3 is positioned with respect to the frame 12. Further, the gap p formed between the small diameter portion 21a of the frame 12 and the inner peripheral surface of the stator core 3 and the adhesive reservoir 25 are filled with the adhesive 24 to firmly fix the stator core 3 and the frame 12 together. . The adhesive 24 is not particularly limited and, for example, an ultraviolet curable adhesive, a thermosetting adhesive or a moisture curable adhesive can be used.

Here, the step of fixing the stator core 3 to the frame 12 in the spindle motor of the present invention will be described.
This will be described in detail with reference to FIG.

First, the press-fitting reference surface 12a, which is the bottom surface of the frame 12, is placed on the receiving table 18. The press-fitting reference surface 12a is formed vertically, that is, horizontally with respect to the axial direction. Next, as shown in FIG. 2A, when the stator core 3 is lowered from above the frame 12, the stator core 3 hits the step portion 23. At this time, the stator core 3 is not yet fixed to the frame 12.

Next, as shown in FIG. 2B, the press-fitting jig 19 is lowered perpendicularly to the press-fitting reference surface 12a, and the stator core 3 is lightly press-fitted into the large diameter portion 21b of the frame 12. The "light press-fitting" is to press-fit the stator core 3 into the large-diameter portion 21b of the frame 12 with a relatively small force. In other words, even if the stator core 3 is press-fitted into the large-diameter portion 21b of the frame 12, the outer peripheral portion of the large-diameter portion 21b is slightly deformed, but the other parts of the frame 12 are press-fitted with a force that does not cause deformation. It means to do. Here, the outer diameter of the large diameter portion 21b is slightly larger than the inner diameter of the central hole 3a of the stator core 3, but since the material of the frame 12 is an aluminum alloy or the like that is softer than the material of the stator core 3, By lightly press-fitting the stator core 3, only the outer peripheral portion of the large diameter portion 21b is deformed and temporarily fixed. Since the step portion 23 has a tapered shape, light press-fitting can be smoothly performed.

Further, when the press-fitting jig 19 is continuously lowered,
Temporary fixing is completed in a state where a part of the end surface of the stator core 3 comes into contact with the second fixing portion 22 of the frame 12 and is positioned with respect to the frame 12. That is, the second fixing portion 22
Like the press-fitting reference surface 12a, is formed horizontally with respect to the axial direction, so that the stator core 3 is also fixed horizontally with respect to the axial direction. Further, since the center of the large diameter portion 21b and the center of the fixed shaft 6 coincide with each other, the center of the stator core 3 is also fixed to coincide with the center of the fixed shaft 6.

As described above, the stator core 3 has the large diameter portion 21.
Since it is lightly press-fitted into b, as described above, the large diameter portion 21
Although the outer peripheral portion of b is deformed, the amount of deformation is small, and thus the deformation hardly leaves the entire frame 12. That is, when the frame 12 is lightly press-fitted, the frame 12 is not distorted, so that the rotation characteristics of the spindle motor are not adversely affected.

Next, when the light press-fitting is completed and the stator core 3 is positioned and temporarily fixed to the frame 12,
Inner peripheral surface of the stator core 3 and the small diameter portion 21a of the frame 12
A gap p is formed between the outer peripheral surface and the outer peripheral surface. Therefore, after the light press-fitting is completed, the adhesive pool 25 is coated with a thermosetting adhesive as the adhesive 24, and the gap p is filled with the adhesive 24.

As described above, since the stator core 3 is positioned and temporarily fixed to the frame 12 by light press-fitting, the stator core 3 does not shift in position or float in the axial direction. Further, a pressing jig that has been used conventionally when injecting the adhesive 24 is not required. Before lightly press-fitting the stator core 3, the adhesive 24 may be applied to the outer peripheral surface of the small-diameter portion 21a in advance and fixed by adhesion.

Further, in the present embodiment, a thermosetting adhesive is used as the adhesive 24, but by using this thermosetting adhesive, it is possible to obtain a stator set or a motor finished product which has been conventionally used. It can be completely cured by high temperature baking. This high temperature baking is performed to secure the rigidity of the motor by completely curing the adhesive 24 and to degas the adhesive 24. It is to put in. Incidentally, instead of applying a thermosetting adhesive,
A moisture-curable adhesive may be filled as the adhesive 24.
When the stator set is washed with pure water or the like in a state where the moisture-curable adhesive is filled, the moisture-curable adhesive is completely cured by moisture, and the bonding force between the frame 12 and the stator core 3 is increased.

As described above, by using the thermosetting adhesive or the moisture curable adhesive as the adhesive 24,
The curing equipment such as an ultraviolet irradiator required for curing the ultraviolet curable adhesive can be removed from the manufacturing process.
This makes it possible to reduce costs and simplify the process.

Next, FIG. 3 shows a state of a light press-fitting portion between the stator core 3 and the frame 12 as a cross-sectional view. FIG.
In (A), the large diameter portion 21b of the frame 12 is the small diameter portion 21a.
Shows a state in which the stator core 3 is temporarily fixed to the frame 12 by projecting from the outside toward the outer side in the radial direction.

FIG. 3B shows the large diameter portion 21 of the frame 12.
It shows a state where b projects from the small-diameter portion 21a toward the outer side in the radial direction at a plurality of locations (four locations in the figure), and the stator core 3 is temporarily fixed to the frame 12. When the large-diameter portion 21b of the frame 12 is formed into a shape as shown in FIG. 3 (B), the bonding area between the outer peripheral surface of the small-diameter portion 21a and the inner peripheral surface of the central hole 3a of the stator core 3 is slightly increased although the manufacturing process is slightly increased. The adhesive strength can be increased.

In both states of FIG. 3A and FIG. 3B, the stator core 3 is connected to the large diameter portion 21 of the frame 12.
Since the center of the central hole 3a of the stator core 3 and the center of the frame 12, that is, the center of the fixed shaft 6 coincide with each other by lightly press-fitting into b, the protrusion of the stator core 3 as seen in the structure of the conventional example. The non-uniformity of the gap between the pole and the drive magnet is eliminated, and a highly reliable spindle motor without rotation unevenness or rotation loss can be obtained.

[0035]

As described above, in the spindle motor of the present invention, it is not necessary to use a pressing jig, and the cost for that can be reduced. Further, the production pace is not leveled off due to the shortage of the pressing jig. Further, the small diameter portion and the large diameter portion are formed in the core fixing portion, the stator core is lightly press-fitted into the core fixing portion such as the large diameter portion, and the adhesive is applied to the gap between the small diameter portion and the inner peripheral surface of the stator core. By filling, the center of the stator core and the center of the frame and the fixed shaft are surely aligned with each other, and it is possible to provide a highly reliable spindle motor without uneven rotation and loss.

[Brief description of drawings]

FIG. 1 is a diagram showing a coupled state of a frame and a stator core in an embodiment of a spindle motor of the present invention,
(A) is a half sectional view, and (B) is an enlarged view of a main part of (A).

2A and 2B are views for explaining a process of lightly press-fitting the frame and the stator core of the spindle motor of FIG.
FIG. 4B is a diagram showing a state immediately before light press-fitting, and FIG. 6B is a diagram showing a state after light press-fitting.

FIG. 3 is a cross-sectional view showing a state of a light press-fitting portion between a frame and a stator core of the spindle motor shown in FIG. 1, and FIG. 3A shows a case where a large-diameter portion projects radially outwardly over the entire circumference. In the figure, (B) is a diagram showing a case where the large-diameter portion projects radially outward at a plurality of locations.

FIG. 4 is a sectional view of a conventional spindle motor.

FIG. 5 is a diagram illustrating a step of connecting a frame and a stator core in a conventional spindle motor.

FIG. 6 is a cross-sectional view of a conventional spindle motor.

[Explanation of symbols]

 3 stator core 4 coil 6 fixed shaft 12 frame 21 first fixed portion 21a small diameter portion 21b large diameter portion 22 second fixed portion 23 stepped portion 24 adhesive 25 adhesive pool 26 taper surface p gap

Claims (11)

[Claims] 1. A frame, a stator core wound with a coil and fixed to the frame, and a hub having a drive magnet facing the stator core and rotating, wherein the frame includes a first fixing portion. And a second fixing portion, and the first fixing portion has a large diameter portion and a small diameter portion formed on the peripheral surface, and the stator core is lightly press-fit into the large diameter portion. At the same time, the gap between the small diameter portion and the inner peripheral surface of the stator core is filled with an adhesive, and the second fixing portion has an end surface that is horizontal with respect to the axial direction, and contacts the one end surface of the stator core. The spindle motor is characterized in that it holds the stator core. 2. The spindle motor according to claim 1, wherein the adhesive is a thermosetting adhesive. 3. The spindle motor according to claim 1, wherein the adhesive is a moisture curable adhesive. 4. A stepped portion between the large diameter portion and the small diameter portion,
The spindle motor according to claim 1, wherein the spindle motor is inclined toward the second fixed portion side. 5. The spindle motor according to claim 1, wherein the large-diameter portion is formed so as to project from the small-diameter portion outward in the radial direction over the entire circumference. 6. The spindle motor according to claim 1, wherein the large-diameter portion is formed so as to project from the small-diameter portion outward in the radial direction at a plurality of locations. 7. The spindle motor according to claim 1, wherein an adhesive pool to which an adhesive is applied is formed in a portion of the frame facing the stator core. 8. A frame, a stator core wound with a coil and fixed to a core fixing portion formed on the frame, a hub having a drive magnet facing the stator core and rotating, and the stator core. The stator core is lightly press-fitted into the core fixing part and positioned with respect to the frame, and a gap formed between the core fixing part and the stator core is filled with an adhesive. While being pressed in,
The spindle motor, wherein the gap is filled with the adhesive, and the stator core is fixed to the core fixing portion. 9. An adhesive reservoir, which is formed between the core fixing portion and the stator core, to which the adhesive is applied, and the adhesive reservoir and the gap are filled with the adhesive. 9. The spindle motor according to claim 8, wherein. 10. The spindle motor according to claim 8, wherein the adhesive is a thermosetting adhesive. 11. The spindle motor according to claim 8, wherein the adhesive is a moisture curable adhesive.