JP2938509B2 - motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for, for example, an optical / magnetic disk drive,
The present invention mainly relates to a motor such as a spindle motor for driving a disk having a small diameter of 2.5 inches or 3.5 inches.

(Conventional technology and its disadvantages)

In recent years, optical and magnetic disks have been reduced in size and weight, and tended to increase in capacity.

Accordingly, the spindle motor is inevitably made smaller and thinner. In addition, the spindle motor has a problem of securing a predetermined output, which is a contradictory factor, and is the present state of the art today.

Reducing the diameter of the disk, which is the medium, is proceeding in the direction of reducing the spindle hub diameter.On the other hand, within the spindle motor, a suitable bearing space is required to secure both the rigidity of the spindle hub and high rotational accuracy. And

The structure of the motor adopts an outer rotor system with a radial air gap structure that generates a large amount of torque per unit volume. In such an outer rotor type motor, a magnet that generates driving torque by a rotor magnet and a stator is used. Circuit space is being further reduced. For this reason, dimensional restrictions on the stator constituting the magnetic circuit space are received from both the outside and the inside of the spindle motor. Therefore, a stator having a small outer diameter and a larger inner diameter is required.

However, such a stator core is formed by laminating a plurality of core plates. The laminated core plate is provided with a sharp rod-shaped mold pin (pressing means) as disclosed in Japanese Utility Model Application Laid-Open Nos. 62-140858 and 1-1116544. When the core plate is laminated and fixed by caulking, if the core area is small, the caulking pressure will not be evenly distributed on the core, resulting in uneven thickness and partial Swelling occurs. If the thickness unevenness occurs, a predetermined lamination thickness cannot be obtained, causing not only a problem in assembling the spindle motor, but also a gap between the laminated core plates, resulting in a decrease in motor efficiency due to an increase in magnetic resistance. Invite.
In addition, the crimping strength is likely to be reduced, and if the core is displaced or tilted, a contact accident with the rotor magnet may be caused.

〔Purpose〕

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a motor capable of securely fixing a core plate without adversely affecting a magnetic circuit, corresponding to a reduction in size and weight. To provide.

(Summary of the Invention)

According to the present invention, a stator in which a coil is wound around a core, a rotor that is relatively rotatable with respect to the stator, and a rotor magnet that is mounted on the rotor so as to face a side surface of the stator. In the outer rotor type motor having the above, the core of the stator is formed by stacking a plurality of annular core plates, but the inner peripheral edge is pressed in the axial direction by a cylindrical pressing means, and the There is provided a motor characterized by being subjected to plastic working so as to form a convex portion on one end surface of the entire inner peripheral edge portion and a concave portion on the other end surface thereof and joined thereto. The axial direction is a direction in which the core plates are stacked.

In such a motor, the pack plastic working is performed on the inner peripheral edge of the core plate in a laminated state, so that even though the effective caulking area is small, a uniform and sufficient caulking force can be applied to the core plate. There is no unevenness in the laminated thickness of the cores, and no gap between the cores is generated. Also,
Since the portion subjected to the pack plastic working is a portion that does not substantially affect the magnetic circuit formed by the stator and the rotor magnet, that is, the position of the inner peripheral edge of the core, the influence on the magnetic circuit is small, and the motor There is no substantial reduction in efficiency.

In addition, since the pressing means for performing plastic working for connecting the core plate is cylindrical, the strength is large as compared with a conventional sharp rod-shaped mold pin, and an accident such as breakage during plastic working is extremely large. Less. In addition, the protrusions and recesses of the inner peripheral edge of the core formed by plastic working can be used for holding the core or positioning it at a predetermined position when coating the core.

〔Example〕

Hereinafter, a specific example of a motor according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a cross section of a spindle motor for driving a 2.5 inch disk, for example.

1 is a hub as a rotor, 2 is a bracket, 3 and 4
Is a bearing, 5 is a stator, 57 is a stator coil, 7 is a rotor magnet, 8 is a recording magnetic disk, and 9 is a clamp member.

The bracket 2 has a circular shape, and outer ring portions of a pair of bearings 3 and 4 are fitted and fixed to an inner peripheral surface 24 of a cylindrical portion 22 provided at a substantially central portion thereof. Face 23
, A stator 5 around which a stator coil 57 is wound is fitted. An outer peripheral surface 23 of the cylindrical portion 22 has an outer diameter on the upper side (upper side in the drawing in FIG. 1) smaller than the outer diameter on the lower side (lower side in the drawing in FIG. 1) to form a positioning step. ing. The hub 1 has a shaft portion 11 and a hub portion 12 integrally formed, and an outer peripheral surface 14 of the shaft portion 11 and the bearing 3
And 4 are fitted and fixed to the inner ring portion. Therefore, the hub 1 is rotatably supported on the bracket 2 via the bearings 3 and 4.

The rotor magnet 7 is annularly disposed on the inner peripheral surface of the hub portion 12 of the hub 1 so as to face the stator 5. That is, the present embodiment is composed of an outer rotor type spindle motor based on the relative rotation between the stator and the rotor magnet.

After the disc 8 is placed on the flange 13 outside the hub 1, the clamp 9 is screwed to the outer end 16 of the hub to be held so as to rotate integrally with the hub 1.
For example, a 2.5 inch or 3.5 inch disk has a mounting inner diameter of 20 mm to 25 mm.
mm, and the corresponding outer diameter of the hub 1 is also about
It is 20mm to 25mm, so the inside of the spindle motor must be kept within this dimension. The material of the hub 1 is usually a non-magnetic material such as aluminum or stainless steel (SU
A magnetic material such as S416) is used. A magnet auxiliary or reinforcing member (not shown) is embedded in the hub 1 to secure a predetermined hub rigidity by the strength adapted to the material, or to change the material and shape of the rotor magnet 7 to be used.

On the other hand, the inner diameter of the stator 5 is 6 mm in consideration of the outer diameter of the bearings 3 and 4 and the thickness of the cylindrical portion 22 of the bracket 2.
To 12 mm. Then, a space for winding the stator coil 57 must be secured in a region between the outer diameter and the inner diameter of the stator 5. As the disk drive becomes thinner, it becomes necessary to secure a space in the radial direction of the bearing, and the difference between the outer diameter and the inner diameter of the stator 5 tends to be reduced.

FIG. 2 is a perspective view of the stator 5, and the stator coil 57 shown in FIG. 1 is omitted.

The core 59 of the stator 5 includes an annular core back portion 53, a plurality of pole piece portions 52 extending radially from the core back portion 53, and a tooth portion 51 extending circumferentially at the tip of the pole piece portion 52. The core 59 is formed by laminating a predetermined number of core plates of electromagnetic steel sheets, then fixing the core 59 at a predetermined position, and pressing a cylindrical pressing means on the inner peripheral edge 55 of the core back portion 53 in the axial direction (this embodiment). 1 (upward in the drawing in FIG. 1), an annular concave portion is formed on the pressed surface and an annular convex portion is formed on the other end surface around the entire inner peripheral edge 55 of the core back portion 53. By performing the plastic working, the concave portions and the convex portions of the adjacent core plates are fitted into each other, and are held, that is, crimped by the strong frictional force of the contact surfaces thereof.

For example, when a core plate having a thickness of 0.5 mm is laminated to a thickness of 5 mm to 10 mm, the plastic width (caulking width) of the inner peripheral edge 55 is 0.5 m
m or more. And the other surface becomes a projection. At the same time, the applied force acts evenly on the entire core surface from the inner peripheral edge of the core back portion 53 to the teeth portion 51 through the pole piece portion 52 along the radial direction outward, and the plurality of core plates are connected. Is done. Then, a homogeneous core 59 can be obtained without generating a gap between the mutually adjacent core plates. In addition,
The mold pin (pressing means) for plastic working is reduced in size as the diameter of the core 59 is reduced. The rigidity and the strength of the cylindrical shape are higher than those of the cylindrical shape, so that accidents such as breakage are extremely reduced.

The core 59 thus caulked is subjected to a coating process on the wound core surface for electrical insulation from the stator coil. Coating is performed on the outer periphery 56 of the core 59.
Is applied to the surface of the core 59 excluding the inner peripheral portion 54. In particular, the inner peripheral portion 54 of the core 59 prevents excess coating from adhering during coating. At the time of coating, a jig (not shown) for holding both ends of the stator 5 is used. The core 59 described above is formed by plastic working
Since the inner peripheral edge of 53 has a concave portion formed on the surface pressed by the pressing means at the time of plastic working and a convex portion formed on the other surface, these concave portions and convex portions are fitted to a jig and attached. And can be used for centering.

1 and 2, the space between the upper end face 58 of the stator coil 57 and the inner bottom face 15 of the hub 1 is, for example, 2.5
1 mm for inch or 3.5 inch disk drive spindle motors
The gap is as follows. Therefore, if the shape of the stator coil is poor, a contact accident with the inner bottom surface 15 of the hub 1 is likely to occur. In this embodiment, the convex portion generated by the plastic working of the stator 5 is directed to the inner bottom surface 15 of the hub 1, and in this state, the core 59 is mounted on the positioning step on the outer peripheral surface of the cylindrical portion 22 of the mounting bracket 2. It is placed and fitted externally. As a result, the magnetic space of the stator 5 with respect to the rotor magnet 7 moves downward by the amount of the plastic working deformation of the core 59, and the gap increases, so that the inner bottom surface 15 of the hub 1 and the stator coil 57 contact accidents are effectively prevented.

The embodiment according to the present invention has been described above. However, the present invention is not limited to this embodiment, and may be arbitrarily changed or modified. For example, the spindle motor may be of any type, such as a shaft rotating type and a fixed shaft type, and the core lamination thickness, plastic working width, depth, and the like accompanying plastic working of the stator core may be arbitrarily set. Further, the present invention can be similarly applied to other types of motors other than the spindle motor.

〔effect〕

The present invention has the above-described configuration, and thus has the following effects.

In response to the miniaturization and thinning of the motor, even if the core of the stator is reduced in size and the core area is reduced, the pressing force accompanying plastic deformation applied to the core plate is evenly applied to the entire circumference. The core plate can be securely connected to form the core, and the effect on the magnetic circuit is small, so that the motor efficiency does not decrease. Further, since the pressing means used for the plastic working is cylindrical, accidents such as breakage at the time of pressing are extremely reduced. In addition, since there are concave portions and convex portions all around the inner peripheral edge of the core, it is easy to hold the core when coating the core.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spindle motor according to an embodiment of the present invention. FIG. 2 is a perspective view of the stator in FIG. DESCRIPTION OF SYMBOLS 1 ... Hub 2 ... Bracket 3 ... Bearing 4 ... Bearing 5 ... Stator 55 ... Inner peripheral edge 57 ... Stator coil 7 ... Rotor magnet 8 ... Disk 9 ... Clamp member 51 ... Teeth portion 52 …… Pole piece part 53 …… Core back part

Claims (1)

(57) [Claims] A stator having a core wound with a coil; a rotor rotatable relative to the stator; a rotor magnet mounted on the rotor facing a side surface of the stator; In the outer rotor type motor having the above, the core of the stator is formed by laminating a plurality of annular core plates, and the inner peripheral edge is pressed in the axial direction by a cylindrical pressing means, so that the inside of the core is A motor characterized by being subjected to plastic working so that a convex portion is formed on one end surface of the entire peripheral portion and a concave portion is formed on the other end surface thereof.