JP2000092803A - Spindle motor having vibration isolating structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration isolating structure which does not cause quality dispersion and workability degradation and, in addition, does not readily cause the fracture, etc., of an O-ring, etc., when a stator is attached to a shaft through an elastic body, such as the O-ring, etc. SOLUTION: In assembling a spindle motor 20, a press-fitting sleeve 34 made of a thermally expandable metal or resin is put on an elastic body 32 which is put on a shaft 30 as a vibration isolating material before a stator 36 is assembled with the surface of the elastic body 32. Before the sleeve 34 is put on the elastic body 32, the sleeve 34 is expanded to such a degree that the sleeve 34 can be put on the elastic body 32 by clearance fit by heating the sleeve 34 to a prescribed temperature. Thereafter, the stator 36 is put in the sleeve 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a spindle motor for rotating a magnetic disk medium. More specifically, the present invention is also applicable when the speed of the motor is increased to rotate the magnetic disk medium at a high speed.
The present invention relates to a novel spindle motor having an anti-vibration structure that always performs a quiet rotational driving operation without generating noise.

[0002]

2. Description of the Related Art Conventionally, as a spindle motor of this type, an armature, that is, a stator is fixed to a shaft fixed to a housing, and the vertical position of the shaft is mounted on a spindle hub via a bearing, and the spindle A plurality of disc-shaped recording media are mounted on the outer peripheral portion of the hub via a spacer, and the magnet and the yoke are disposed on the inner peripheral portion of the spindle hub at a slight interval facing the stator fixed to the shaft. Opposite arrangements are known.

However, in such a spindle motor, when the motor rotates at a relatively low speed, the oscillating motion of the armature is small, and this oscillation is not a serious problem.

However, in order to increase the rotation speed of the spindle motor with the speeding up of the magnetic disk device as in recent years, it is necessary to increase the value of the current flowing to the stator. When the value of the current flowing through the stator is increased, the stator oscillates accordingly. This oscillatory motion of the stator is transmitted to the shaft, which in turn excites the housing supporting the shaft, and further the cover, which has the problem of generating loud noise.

In order to solve such a problem, FIG.
As shown in FIG. 1, a magnetic disk medium 1 for storing information is stacked and mounted on an outer peripheral portion via a spacer 9, and a spindle hub 2 having a magnet 4 and a yoke 5 at a central portion of an inner surface; Two bearings 3, 3 having outer rings supported on respective inner surfaces of an upper end and a lower end
A shaft 7 having upper ends and lower ends supporting respective inner races of the two bearings 3, and having an armature 6 fixed at a position corresponding to the magnet 4 and the yoke 5 in the center; 7. A spindle motor for a magnetic disk device comprising a housing 8 for fixing and supporting a lower end of the magnetic disk device 7, wherein two O-rings 13, 13 are provided between the armature 6 and the shaft 7. Spindle motor announced (Patent No. 27)
No. 34873). In FIG. 4, reference numeral 10 denotes a clamp ring, 11 denotes a base, and 12 denotes a cover.

The spindle motor according to Japanese Patent No. 2734873 provides an anti-vibration structure in which O-ring elastic members 13 are arranged between an armature, that is, a stator 6 and a shaft 7, and in principle, is provided. In order to rotate the medium 1 at a higher speed, even if the value of the current flowing to the stator 6 is increased, the vibration of the stator 6 induced by the current is hardly transmitted to the shaft 7, and therefore, the housing supporting the shaft 7 8, and furthermore, it is possible to prevent the cover 12 from being excited, which is expected to greatly contribute to prevention of noise generation of the spindle motor during the above-described high-speed rotation movement.

[0007]

However, in the spindle motor according to the above-mentioned patent, the O-rings 13 and 13 not only function as an anti-vibration material but also securely fix the armature or the stator 6 to the shaft 7. It must also have a function as a fixing member for performing the operation. Therefore, when assembling the spindle motor, these O-rings 13 are maintained in the elastically deformable region so as to provide an anti-vibration function, and are pressed and crushed as much as possible to provide a fixing function, In this state, it is necessary to mount the stator 6 around the O-ring 13. For this reason, when attaching the O-ring 13 to the shaft 7, the O-ring 13 must be assembled to the shaft 7 while being stretched by a strong force, and the work is extremely difficult. Further, when the stator 6 is inserted onto the O-ring 13 thus assembled, it often happens that the O-ring bites into the stator or the O-ring is twisted. This poses structural problems such as quality variations, poor workability, and easy occurrence of breakage of the O-ring. The present invention solves these problems.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a heat-expandable press-fit sleeve made of metal or resin is fitted on the surface of an elastic body as a vibration-proof material inserted and arranged in a shaft. At the time of the joint arrangement, the press-fit sleeve is raised to a predetermined temperature in advance, and is expanded to a size that causes a clearance fit with respect to the elastic body 32, thereby solving the above-described problem.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a motor 20 showing only a main part of a motor 20 having a novel vibration-proof structure according to the present invention. The motor 20 of the present invention shown in FIG. 1 includes a fixed portion 22, a rotating portion 24, and a disk enclosure portion 26 surrounding the fixed portion 22 and the rotating portion 24.

The fixed portion 22 includes a shaft 30 and at least one pair of Os mounted at an intermediate position of the shaft 30.
An elastic body 32 made of a ring or a vibration-proof rubber, a press-fit sleeve 34 made of metal, for example, aluminum, fitted on the outer peripheral portion of the elastic body 32;
Known stator or armature 3 mounted on the outer peripheral portion of
And 6.

The elastic body 32 preferably has a cylindrical shape made of a vibration isolating rubber or the like, and generates a stator 36 generated when a current value flowing to the stator 36 is increased in order to increase the rotation speed of the spindle motor 20. Has an anti-vibration function of preventing the oscillation motion of the shaft 30 from being transmitted to the shaft 30.

A metal sleeve 34 is fitted into the elastic body 32 by inserting a hot can or by swallowing. For this reason, the sleeve 34 provides a function of keeping the elastic body 32 having an anti-vibration function in the elastic deformation region with respect to the shaft 30 and pressing and holding the elastic body 32 in a pressurized state. In this way, in the present device, when the elastic body 32 is mounted on the shaft 30, the elastic body 32 can be maintained in advance in the elastic deformation region while stretching the elastic body 32 with a strong force as in the motor of FIG. There is no need to pressurize and hold in a crushed state, and the elastic body 32 can be inserted into the shaft 30 very easily.

The stator 36 is known per se, and the stator 36 is easily mounted and fixed to the outer surface of the metal sleeve 34 by known means. In the present device, as shown in FIG.
The elastic body 32 is not fixed to the elastic body 32 but is fixed to the press-fit sleeve 34 surrounding the elastic body 32 under pressure, so that the elastic body 32 bites the stator when the stator 36 is mounted. There is no accident of getting stuck or twisting. For this reason, structural problems such as variation in quality and poor workability, which have been problems of known spindle motors, and further, occurrence of an accidental breakage of the elastic body have been completely solved.

On the other hand, the rotating part 24 is constituted by a hub 40 made of, for example, stainless steel, and a magnet 42 fixed by a known means at a position facing the stator 36 on the inner surface of the hub 40. ing.
As will be apparent to those skilled in the art, if the hub 40 is made of aluminum, for example, the magnet 4
2 is the hub 4 via a yoke fixed to the hub 40.
Fixed to 0. A plurality of recording media (not shown) are mounted on the outer surface of the hub 40 via a plurality of spacers (not shown) in the same manner as shown in FIG. At the lower end of the hub 40, a flange 44 for holding the recording medium and the spacer is formed.

The fixed portion 22 and the rotating portion 24 are opposed to each other with a small space between the stator 36 and the magnet 42 by a pair of bearings 50, 50 attached to the upper and lower ends of the shaft 30. As described above, they are connected and held in a predetermined positional relationship with each other.

Further, the disk enclosure portion 26
4, a housing 60 to which the shaft 30 is fixed, a base (not shown), and a cover (not shown) forming an outer frame of the motor 20, similarly to the motor shown in FIG.
It consists of.

In the motor 20 of the present invention, the fixed part 22, the rotating part 24, the disk enclosure part 2
6, the shaft 30, the elastic body 32, and the stator 3
6, the detailed structure and operation of the hub 40, the magnet 42, the bearing 50, the housing 60, the base, and the cover are substantially the same as those of the conventional example as shown in FIG.

FIGS. 2 and 3 show an assembling procedure for manufacturing the fixed portion 22 which is a characteristic portion of the motor 20 of the present invention. FIG. 2 (A) shows the elastic member 3 attached to the shaft 30.
2B shows a state before mounting, and FIG.
The state after attaching the elastic body 32 is shown. The surface of the shaft 30 is finished to a predetermined finishing accuracy as usual. At least two O-rings or elastic bodies 32 made of vibration-proof rubber are inserted and mounted on the shaft 30 from its end. At this time, this elastic body 3
No. 2 does not need to be mounted on the stator while being kept in the elastic deformation region and pressed and crushed as much as possible, unlike the motor shown in FIG. 4 described above. Therefore, the mounting of the elastic body 32 can be performed easily, quickly and accurately. The elastic body 32 is connected to the shaft 30
After fitting on one end of the
It is installed at a predetermined position shown in (B).

Next, as shown in FIGS. 2C and 3A, a press-fit sleeve 34 is fitted from one end of the shaft 30 onto an elastic body 32 installed on the shaft 30.
At this time, it is necessary to increase the temperature of the press-fitting sleeve 34 in advance and expand the press-fitting sleeve 34 to a size that causes a clearance fit with respect to the elastic body 32. This eliminates the "cut" or "breakage" or "twist" of the elastic body 32 such as the O-ring by inserting the sleeve 34 into the shaft 30 and the elastic body 32 or shrink-fitting the shaft 34 and the elastic body 32. The purpose is to obtain a stable vibration damping action which is the purpose. Therefore, the press-fit sleeve 34
Is preferably formed of a material having a temperature expansion coefficient as high as possible and having sufficient strength as a press-fitting material, for example, an aluminum material. Thus, the press-fit sleeve 3
As shown in FIG. 3 (A), 4 is inserted onto an elastic body 32 installed on a shaft 30 and positioned there. When the elastic body 32 is a pair of O-rings, the sleeve 34 has a length enough to completely cover the space between the upper and lower sides, and when the elastic body 32 is a member having a cylindrical shape, it has at least its elasticity. It is desirable to have a length enough to cover the entire body 32.

Thereafter, as shown in FIGS. 3B and 3C, the stator 36 is inserted from one end of the shaft 30, and the stator 36 is pressed into the sleeve 34 and positioned at a predetermined position. Here, the coefficient of thermal expansion of the stator 36 is lower than the coefficient of thermal expansion of the sleeve 34, and usually,
The stator 36 is pressed into the stator 34 at room temperature.

The fixing portion (22 in FIG. 1) formed in this way is fixed to a bearing (50 in FIG. 1) by a known procedure.
To the rotating part (reference numeral 24 in FIG. 1) to complete the assembly of the motor 20.

The method of using the spindle motor according to the present invention is the same as the conventional one. In the above-described embodiment, the press-fit sleeve 34 is made of aluminum. However, the press-fit sleeve 34 can be made of another metal material or resin material as long as the thermal expansion is relatively easy.

[0023]

In the spindle motor according to the present invention, since the sleeve is inserted into the elastic body in a state where the sleeve is expanded in temperature, there is some gap between the elastic body and the sleeve. The occurrence of "torsion of the elastic body" and "cutting of the elastic body" can be completely prevented. For this reason, the durability of the spindle motor has been significantly increased. As described above, in the spindle motor according to the present invention, the gap between the sleeve and the elastic body can be set sufficiently large in consideration of the expansion of the gap due to temperature expansion in advance in design. The workability of assembling the motor is remarkably improved as compared with a conventional structure in which the gap between the stator and the elastic body cannot be adjusted in advance as in the conventional structure shown in FIG. Further, by press-fitting a stator having a low coefficient of thermal expansion into the outer peripheral portion of the sleeve having a high coefficient of thermal expansion at room temperature, it is possible to minimize the decrease in the joining strength of the elastic body due to the temperature expansion of the sleeve. With the spindle motor according to the present invention, it is possible to provide a spindle motor having a strength at least approximately equal to or higher than the joining strength of the elastic body in a spindle motor having a conventional structure without a sleeve.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a motor having a novel anti-vibration structure according to the present invention, showing only a main part of the motor.

FIG. 2 is a diagram showing an assembling procedure for manufacturing a fixed portion which is a characteristic portion of the motor of the present invention.

FIG. 3 is a diagram showing an assembling procedure for manufacturing a fixed portion which is a characteristic portion of the motor of the present invention.

FIG. 4 is a cross-sectional view showing an example of a known spindle motor having an anti-vibration structure.

[Description of Signs] 20 Spindle motor 22 Fixed part 24 Rotating part 26 Disk enclosure part 30 Shaft 32 Elastic body 34 Press-fit sleeve 36 Stator 40 Hub 42 Magnet 50 Bearing

Claims (8)

[Claims] 1. A spindle motor comprising a fixed portion, a rotating portion, and a disk enclosure portion, wherein the fixed portion includes a shaft and a vibration-proof material inserted and disposed in the shaft. An elastic body 32, a metal or resin heat-expandable press-fit sleeve 34 fitted and arranged on the surface of the elastic body 32 by flicking;
Stator 3 press-fitted on the surface of sleeve 34
The rotating part 24 has a function of disposing a magnetic disk medium on the outer surface side, and comprises a hub 40 having a magnet 42 on the inner surface side. The fixed part 22 and the rotating part 24 The stator 36 of the fixed portion 22 and the magnet 42 of the rotating portion 24 are opposed to each other at a predetermined interval, and the shaft 30 of the fixed portion 22 is fixed to the disk enclosure portion 26. A spindle motor having an anti-vibration structure in which a rotating portion surrounded by a portion is rotatable via a bearing with respect to a fixed portion. 2. The sleeve according to claim 1, wherein the sleeve has a function of holding the elastic body in a resilient deformation region with respect to the shaft and holding the elastic body in a pressurized state. Spindle motor. 3. The spindle motor according to claim 1, wherein the elastic body comprises at least a pair of O-rings. 4. The spindle motor according to claim 1, wherein the elastic body is a member having a cylindrical shape made of a vibration-proof rubber. 5. The sleeve according to claim 1, wherein
Is formed of an aluminum material. 6. A method of manufacturing a spindle motor 20 having an anti-vibration structure, comprising a fixed part 22, a rotating part 24, and a disk enclosure part 26, the method comprising: providing a shaft 30; The elastic body 32 as a vibration-proof material is mounted on the shaft 30 and positioned at a predetermined position, and a heat-expandable press-fit sleeve 34 made of metal or resin is placed on the elastic body 32 installed on the shaft 30.
Into the sleeve 34 and the stator 36
To form a fixed portion 22 by press-fitting and positioning at a predetermined position, to prepare a hub 40 for mounting a magnetic disk medium on the outer surface, and to mount a magnet 42 on the inner surface of the hub 40 to rotate. Forming the portion 24; the bearing 5 mounted on the shaft 30 of the fixed portion 22 at an upper and lower position so that the stator 36 of the fixed portion 22 and the magnet 42 of the rotating portion 24 face each other at a small interval.
0, the fixed part 22 and the rotating part 24 are assembled to each other. By fixing the end of the shaft 30 of the fixed part 22 to the disk enclosure part 26, the assembled body of the fixed part 22 and the rotating part 24 is assembled. When the press-fit sleeve 34 is fitted on the elastic body 32, the temperature of the sleeve 34 is raised in advance, so that the press-fit sleeve 34 becomes a gap with respect to the elastic body 32. A method for manufacturing a spindle motor having an anti-vibration structure, characterized in that the spindle motor is expanded to a maximum. 7. The method for manufacturing a spindle motor according to claim 6, wherein said sleeve is formed of an aluminum material. 8. The method for manufacturing a spindle motor according to claim 6, wherein the thermal expansion coefficient of the stator is lower than the thermal expansion coefficient of the sleeve, and the stator is pressed into the sleeve at room temperature. .