JPH08322220A - Spindle motor - Google Patents

Abstract

PURPOSE: To provide a spindle motor which can be assembled easily and manufactured at a low cost. CONSTITUTION: In a spindle motor constituted of a shaft 13 fixed to a fixing member, rotor hub 10 which is supported by the shaft 13 and holds a recording medium put on the outer periphery of the hub 10, stator 14 which is held on the fixing member side, rotor magnet 23 fixed to the hub 10 so that the magnet 23 can be faced to the stator 14, etc., the hub 10 is composed of a resin material. A center hole 17 into which the shaft 13 is inserted is formed at the axial position of the hub 10 and a very small clearance is formed between the shaft 13 and the hole 17 of the hub 10. In addition, the hub 10 is supported by the shaft 13 so that the hub 10 can freely rotate upon the shaft 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a spindle motor for rotationally driving a recording disk, and more particularly to a spindle motor which is easy to assemble and can be manufactured relatively inexpensively.

[0002]

2. Description of the Related Art FIG. 5 shows a commonly used spindle motor 1a. A shaft 13a is erected and fixed on the base member 12a, and a rotor hub 26 is pivotally supported via a ball bearing 25. The rotor hub 26 is formed of a cylindrical hub 27 and a yoke 28, and a rotor magnet 23 a is attached inside the yoke 28. Further, a plurality of recording disks 15 are stacked on the outer peripheral side of the hub 27 via a spacer 24, and are pressed and held by the tip end side of a clamp member 30 screwed by a screw 29. On the other hand, a stator 14a is held by the base member 12a and is arranged so as to face the rotor magnet 23a. Substrate 3 provided on the base member 12a side
1 to the stator 14a by energizing the stator 1
Electromagnetic action occurs between the rotor 4a and the rotor magnet 23a, the rotor hub 26 rotates, and information is recorded on the recording disk 15.

[0003]

In the case of the above-mentioned conventional spindle motor 1a, the rotor hub is made of a metal member processed with high precision, and the work of fitting the ball bearing 25 is required at the time of assembly. In addition, a screw hole for screwing the clamp member 30 is processed, and the clamp member 30 is screwed.
Installation work is required due to 9. Further, the miniaturization of the ball bearing 25 is required as the motor is miniaturized, but the miniature ball bearing 25 is expensive in terms of cost. On the other hand, there is a demand for a spindle motor that is more easily assembled and can be manufactured at low cost. In addition, in view of recent advances in motor rotation control technology, there is a need for higher precision rotation of the spindle motor.

The present invention has been made in view of the above demands and circumstances, and an object of the present invention is to provide a spindle motor which is easy to assemble and can be manufactured at low cost.

[0005]

A shaft fixed to a fixed member, a rotor hub pivotally supported by the fixed member to hold recording media stacked on the outer peripheral side, a stator held on the fixed side, and the stator. In a spindle motor including a rotor magnet and the like fixed to the rotor hub so as to face the rotor hub, the rotor hub is made of a resin material,
A center hole into which the shaft is inserted is formed at an axial center position of the rotor hub, and a minute gap is formed between the shaft and the center hole of the rotor hub, so that the rotor hub rotates with respect to the shaft. It is characterized by being supported freely. In addition, it is preferable that an axial retaining member that engages with each other is formed at a contact portion between an outer peripheral surface of the shaft and an inner peripheral surface of the central hole that faces the outer peripheral surface.

Holding means for holding the recording medium on the rotor hub is provided, and the holding means is rotatably inserted into a key-shaped groove formed on the upper side of the rotor hub and the outer circumference of the rotor hub. It is composed of a clamp member having a locking portion on the circumferential side that is detachably fitted to the groove, and the groove is composed of a locking groove along the circumferential direction and an opening communicating with the locking groove and opening upward. good. In particular, it is desirable that the locking portion of the clamp member be formed with a locking projection for strengthening the locking with the locking groove.

[0007]

As the rotation support means of the rotor hub, a sleeve bearing is adopted by a simple assembling work in which the shaft is inserted into the rotor hub made of resin. Further, the recording disk is pressed by the clamp member and fixed to the rotor hub only by fitting the clamp member into the rotor hub from above and engaging the locking portion with the key-shaped groove formed in the hub. Therefore, the assemblability of the spindle motor can be greatly improved and the cost can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an axial sectional view showing the overall structure of this embodiment, and FIG.
4 is a schematic cross-sectional view for explaining the outline of the method for manufacturing the rotor hub of this embodiment, FIG. 3 is a perspective view for explaining the locking structure of the rotor hub and the clamp member of this embodiment, and FIG.
FIG. 7 is a partial plan view for explaining a method of engaging and disengaging the groove of the rotor hub and the locking portion of the clamp member.

First, the overall structure of the spindle motor 1 of this embodiment will be described. The spindle motor 1 is roughly divided into a base member 12, which serves as a fixing member, a shaft 13, a rotor hub 10, a stator 14, etc., and a recording disk 15
A clamp member 4 is provided for holding the rotor hub 10 on the rotor hub 10.

The base member 12 is made of a flat plate member, and a shaft 13 is erected and fixed at a substantially central portion thereof. A recessed groove 16 for locking is formed in the middle portion of the shaft 13.

The rotor hub 10 comprises a hub 2 and a yoke 11 fitted below the hub 2. The hub 2 has a cylindrical shape and forms the center hole 17, and in this embodiment, is made of a resin material formed by insert molding. By inserting the shaft 3 into the center hole 17 of the hub 2, the sleeve bearing portion 3 is formed. The shaft 1 is provided in the center hole 17.
A convex portion 18 that fits into the concave groove 16 of No. 3 is formed. Groove 1
The rotor hub 10 is prevented from coming off by the engagement between the 6 and the convex portion 18.

FIG. 2 shows an outline of manufacturing the hub 2 of this embodiment by the insert molding method. Reference numeral 19 is a lower mold, the shaft 13 is detachably supported, and the upper mold 2
With 0, a space 21 having the same shape as the shape of the hub 2 is formed inside them. Further, the hub 2 is formed with a groove 7 for mounting a clamp member 4 to be described later on the hub 2. At the time of this molding, the groove forming die 2 is formed to form the groove 7.
0a is separately fitted into the upper mold 20. The lower mold 19, the upper mold 20, and the groove forming mold 20a are made of metal. From the injection molding machine (not shown), apply the heated liquid resin material to the upper mold 2
It is injected from the injection port 22 of 0 and cooled. Then, by removing the respective molds, the modeled hub 2 is taken out.

The thermal expansion coefficient A of the shaft 13 and the thermal expansion coefficient B of the resin material are set to A> B in advance, and when both are cooled, the shaft 13 having a large thermal expansion coefficient is the resin material. It contracts significantly compared to the hub 2. As a result, a gap is formed between the center hole 17 of the hub 2 and the shaft 13. This gap becomes the sleeve bearing portion 3,
The hub 2 is rotatably supported on the shaft 13.

In FIG. 1, a rotor magnet 23 is attached inside the yoke 11. A stator 14 is held on the base member 12 side. The stator 14 is connected to a substrate side (not shown) provided on the base member 12 side.

Next, the clamp structure of the recording disk 15 will be described. The hub 2 is formed with a flange portion 2A for supporting the recording disk 15. The recording disks 15 are inserted into the outer periphery of the hub 2 and supported on the flange portion 2A, and are sequentially stacked via the spacer 24. The clamp member 4 of the present embodiment is pressed against the uppermost recording disk 15, and the pressing force causes the recording disk 15 to rotate.
It is held at 0. As shown in FIG. 3, the clamp member 4 is composed of a ring-shaped member that can be inserted into the hub 2, and a plurality of (three in the figure) locking portions 5 project radially and are integrally formed on the inner hole side thereof. Formed. Further, the locking portion 5 has a hub 2
A protruding portion 5a is formed in order to strengthen the locking with the. The three locking portions 5 are arranged at equal intervals in the circumferential direction. Further, on the outer periphery of the clamp member 4, there is provided a catch groove 6 for facilitating the clamping of the clamp member with a finger or a jig. On the other hand, a key-shaped groove 7 is provided above the hub 2. The groove 7 is integrally formed when the hub 2 is molded. The groove 7 is composed of a locking groove 8 along the circumferential direction and an opening 9 communicating with the locking groove 8 and opening upward. The locking groove 8 has a groove width substantially the same as the thickness dimension of the locking portion 5 of the clamp member 4, and the opening 9 has a width dimension slightly larger than the circumferential width dimension of the locking portion 5. Consisting of having.

As shown in FIG. 4B, the clamp member 4 can be inserted into the hub 2 by aligning the clamp member 4 with the hub 2 and aligning the locking portion 5 with the opening 9. Next, when the catch groove 6 is held with a finger or a jig and the clamp member 4 is rotated, the locking portion 5 fits into the locking groove 8 as shown in FIG. Then, due to the action of the protruding portion 5 formed on the locking portion 5, the locking portion 5 and the locking groove 8 are firmly fitted, and the clamp member 4 is reliably held on the hub 2 side. Since the groove 7 and the clamp member 4 are formed so that the lower surface of the clamp member 4 can be pressed against the upper surface of the recording disk 15 in this state, the recording disk 15 is held on the rotor hub 10 side by the pressing force of the clamp member 4. It

As described above, in this embodiment, the shaft 1
3, the rotor hub 10 is fixed by insert molding,
Recording disks 15 stacked on the outer circumference of the rotor hub 10.
Assembling the clamp member 4 to the hub 2 completes the assembly work of the main part of the spindle motor 1. Therefore, the assembly work becomes extremely easy. Further, the rotor hub 10 does not need to be processed with high precision, and screw processing for clamping is also unnecessary. Further, it is not necessary to use the expensive ball bearing 25, and the cost can be reduced.

In the present embodiment, the lubrication between the sleeve bearing portion 3 and the shaft 13 is carried out. However, by pre-filling a minute gap between them with oil, abrasion of both can be prevented.

Although the embodiment of the spindle motor according to the present invention has been described above, the present invention is not limited to such an embodiment, and various changes and modifications can be made without departing from the scope of the present invention.

[0020]

According to the present invention, the following remarkable effects are obtained. 1) By forming a slight gap between the hub 2 and the shaft 13 and adopting it as the sleeve bearing portion 3, the bearing structure is simple and inexpensive, and the assemblability is improved. 2) By insert-molding the rotor hub with a resin material, the locking groove is also integrally molded, so that the assembling property can be simplified and the weight can be reduced, and the cost can be reduced. 3) The recording disc can be held only by engaging the locking portion of the clamp member with the key-shaped groove of the rotor hub, which simplifies the holding structure and improves the assembling property.

[Brief description of drawings]

FIG. 1 is an axial sectional view showing the overall structure of an embodiment of the present invention.

FIG. 2 is a schematic axial cross-sectional view for explaining the method of molding the hub of the present embodiment.

FIG. 3 is a perspective view of a clamp member and a hub for explaining the locking structure of the present embodiment.

FIG. 4 is a partial plan view showing an engagement state between a locking portion and a groove according to the present embodiment.

FIG. 5 is an axial sectional view showing the overall structure of a conventional spindle motor.

[Explanation of symbols]

 1 Spindle Motor 2 Hub 4 Clamp Member 7 Groove 10 Rotor Hub 12 Base Member 13 Shaft 14 Stator 15 Recording Disk 16 Recessed Groove 17 Center Hole 18 Convex 23 Rotor Magnet

Claims (4)

[Claims] 1. A shaft fixed to a fixing member, a rotor hub pivotally supported by the fixing member and holding a recording medium stacked on the outer peripheral side, a stator held on the fixing member side, and a stator facing the stator. In the spindle motor including a rotor magnet and the like fixed to the rotor hub, the rotor hub is made of a resin material, and a central hole into which the shaft is inserted is formed at an axial center position of the rotor hub. A spindle motor is characterized in that a minute gap is formed between the rotor hub and the center hole thereof, and the rotor hub is rotatably supported with respect to the shaft. 2. The spindle motor according to claim 1, wherein an axial retainer for engaging with each other is formed at a contact portion between an outer peripheral surface of the shaft and an inner peripheral surface of the central hole facing the outer peripheral surface. 3. Holding means for holding the recording medium on the rotor hub is provided, and the holding means is rotatably attached to a key-shaped groove formed above the rotor hub and the outer circumference of the rotor hub. And a clamp member having an engaging portion on its inner peripheral side that is detachably fitted to the groove, the groove communicating with the engaging groove along the circumferential direction and opening upward. The spindle motor according to claim 1, wherein the spindle motor comprises an opening. 4. The spindle motor according to claim 3, wherein a locking protrusion for strengthening locking with the locking groove is formed in the locking portion of the clamp member.