JP3354263B2 - Spindle motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor incorporated in various OA equipment and the like for rotating a recording disk such as a magnetic disk or a magneto-optical disk.

[0002]

2. Description of the Related Art In a spindle motor for rotating a recording disk such as a magnetic disk or a magneto-optical disk, unclean oil particles and air (gas) containing a lubricant and a contamination of a bearing member and the like existing inside the motor body are removed. A labyrinth sealing means and a magnetic fluid sealing device are provided to prevent the disk from entering the disk storage space.

[0003] The labyrinth sealing means has a configuration in which a bracket or housing as a stationary member and a rotor hub as a rotating member are arranged with a slight gap therebetween, and these are formed in a concave or convex shape and combined. , Tokiko Sho 58
Various publications have been proposed in addition to JP-A-10785. By reducing the gap or complicating the shape of the uneven portion, the sealing performance can be further improved.

A magnetic fluid sealing device comprises magnetomotive force means constituted by combining a permanent magnet and a pole piece, and a magnetic fluid which forms a seal layer by means of the magnetomotive force and is attracted and held. Various proposals have been made in addition to JP-A-60-76053.

[0005]

However, according to the above-described spindle motor, in the labyrinth sealing means and the magnetic fluid sealing device, in order to enhance and maintain the sealing performance, it is necessary to use a predetermined structure such as a rotor hub or a bracket. It is necessary to process and finish the part precisely and assemble it with high precision. In addition, care must be taken to prevent air leakage at other parts of the spindle motor. For this reason, contrary to the improvement in the sealing performance described above, the labor involved in processing and assembling the motor increases, and some measures have been desired to reduce the manufacturing cost.

The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to maintain and improve the sealing performance for sealing the inside and outside of a motor. There is no need for processing and assembly with it.
An object of the present invention is to provide a spindle motor with high reliability and high productivity.

[0007]

[MEANS FOR SOLVING THE PROBLEMS] A bracket and a shaft are provided.
A stationary member consists of a ball bearing mounted on the shaft, the spindle motor provided with the rotor hub to be relatively rotated supported with respect to the stationary member through a該玉bearing, said shaft definitive to the stationary member Base position of
The part where the ball bearing of the shaft is fixed is
The first large-diameter portion is formed to be
A diameter portion and a position closer to the distal end of the shaft than the first large diameter portion.
From the part where the ball bearing of the shaft is fixed
An annular slide formed with a large diameter and a smaller diameter than the first large diameter portion.
And the inner ring of the ball bearing is fixed.
A second large-diameter portion formed with an end surface for positioning in the axial direction
The sleeve member has a center hole formed in the
2 and abuts on the end face of the first large diameter portion.
Annular disk part and the axial direction located at the outer peripheral end of the disk part
The annular sleeve member is disposed around the entire outer periphery of the ball bearing with a slight gap with respect to the outer ring side end of the ball bearing and the outer ring portion outer peripheral portion connected thereto. The clearance between the annular sleeve member and the ball bearing constitutes a labyrinth seal means for substantially sealing the inside and outside of the motor.

In the spindle motor, it is preferable that a labyrinth sealing means is provided on the outer peripheral side of the annular sleeve member so that an inner peripheral portion of the rotor hub is surrounded and positioned over the entire periphery with a small gap.

[0009]

According to the spindle motor having the above structure,
The annular sleeve member is disposed with a small gap over the entire circumference with respect to the outer ring portion side end portion of the ball bearing and the outer ring portion outer peripheral portion connected thereto. As a result, labyrinth sealing means is formed between the annular sleeve member and the outer ring portion. At this time, the labyrinth sealing means can be obtained only by forming the annular sleeve member into a predetermined shape and fixing it coaxially to the stationary member. That is, the other side of the labyrinth sealing means is the outer ring portion of the ball bearing, and has a predetermined dimensional accuracy. Therefore, by using this as it is, there is no need for special processing for securing the sealing performance or consideration for assembly.

In the spindle motor, the inner peripheral portion of the rotor hub is positioned with a small gap over the entire circumference with respect to the outer peripheral side of the rising portion of the annular sleeve member. And a labyrinth sealing means by the rotor hub. Therefore, the sealing performance can be further improved, and no special member or the like is required.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle motor according to the present invention will be described with reference to the accompanying drawings. First, a first embodiment will be described with reference to FIGS.

FIG. 1 shows the overall configuration of a spindle motor, which includes a stationary member constituted by a bracket 8 and a shaft 4, and a rotor hub 6 which is rotatable relative to the stationary member.

The rotor hub 6 is made of stainless steel and has a substantially cylindrical shape. The rotor hub 6 includes a cylindrical portion 6a on which a magnetic disk is mounted on a peripheral surface, and a small-diameter convex portion 6 for fixing a ball bearing 10 provided at an upper end portion of the cylindrical portion 6a.
b, an annular clamp holding portion 6c formed around the convex portion 6b, and a flange-shaped disk mounting portion 6d located at the lower end of the cylindrical portion 6a and expanded in the radial direction from the outer diameter of the cylindrical portion 6a. Consists of The cylindrical yoke member 12 is mounted on the disk mounting portion 6.
It is caulked and fixed by the caulking part 9 provided on the lower surface 6e of d, and is fixed using an adhesive as needed.

The cylindrical rotor magnet 5 includes a yoke 12
Is positioned at the step 12a on the inner periphery of the yoke, and is adhered and fixed to the inner periphery of the yoke. The space 33 formed by the step portion 12a of the yoke 12, the caulked portion 9, and the rotor magnet 5 is:
The groove for the adhesive for fixing the yoke, the relief of the caulked portion 9, and the reduction of the magnetic flux dispersion from the magnet are performed.

A boss 8a for fixing the stator 7 is provided at the center of the bracket 8, and the shaft 4 is press-fitted into the center hole of the boss 8a to form a stationary member. Also, a flange portion 8b on the outer peripheral portion of the bracket 8
Is a fixing portion when mounted on a disk drive.

The stator 7 includes a lower end surface of the rotor hub 6, an inner peripheral surface 5a of the rotor magnet 5, and a bottom surface 8 of the bracket 8.
c and the outer peripheral surface of the boss portion 8a, the boss portion 8 is opposed to the rotor magnet 5 in the annular space 13.
a is fixed to the peripheral surface.

During rotation, a pair of ball bearings 10 and 11 are rotatably supported as bearing means between the upper part of the shaft 4 which is a fixed shaft and the cylindrical portion 6a of the hub member 6.

The rotor hub 6 is driven to rotate relative to the stationary member by electromagnetic interaction between the stator 7 mounted on the bracket 8 as a stationary member and the rotor magnet 5 integrated with the rotor hub 6.

The upper ball bearing 10 is fitted and bonded to the upper end of the shaft. The upper end surface of the ball bearing 10 is entirely covered with a cap-shaped sealing member 14 including the ball bearing 10 and the shaft 4 so as not to be directly exposed to the disk accommodation space. Therefore, it is possible to prevent the lubricant and the like from inside the ball bearings 10 and 11 from scattering outside the motor.

On the other hand, the lower ball bearing 11 is fitted and bonded to the middle of the shaft 4 with the position defined by the end face of the boss 8a. The upper half of the outer ring portion of the ball bearing 11 is fitted to the inner periphery of the rotor hub 6 and is fixed by bonding.

The upper half portion of the boss portion 8a is provided with an annular sleeve member 15 having an L-shaped cross section.
b. The sleeve member 15, as shown in FIG. 2 consists of a cylindrical rising portion 15b protruded upward from the outer periphery of the circular <br/> plate portion 15a of the disk portion 15a Toko, the upper end of the boss portion 8a 8d on the outer periphery
, And a rising portion 15b extends into a stepped concave portion 6h provided on the inner peripheral portion of the lower end of the rotor hub 6.

Here, the upper surface of the disk portion 15a of the sleeve member 15 is opposed to the lower end surface 11a of the outer ring portion of the ball bearing 11 via a minute gap 16a, and the inner peripheral surface of the rising portion 15b is formed on the outer peripheral portion of the outer ring portion. 11b via a minute gap 16b.

The gaps 16a and 16b form labyrinth sealing means for substantially sealing the inside and outside of the motor, so that oil mist from the ball bearings 10 and 11 and outgas of the adhesive can be easily formed outside the motor (in the disk chamber). ) Is prevented.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In the illustrated spindle motor, the shaft 1
A stationary member is formed by integrating the bracket 7 and the bracket 18, and a rotor hub 21 is rotatably supported via ball bearings 19 and 20 in the upper half of the shaft 17.

A holder 23 holding a magnetic fluid sealing device 22 is fixed to the rotor hub 21, and a magnetic ring 24 is provided on the outer periphery of the shaft 17 facing the sealing device 22.

The magnetic fluid sealing device 22 comprises a magnetic circuit unit in which an annular magnet 22a is sandwiched between ferromagnetic pole pieces 23b and 23c, and a magnetic fluid filled and held in a gap between the unit and the shaft 17. Is done. The magnetic fluid layer formed by the magnetic fluid partitions the inside and outside of the motor, and prevents oil mist and outgas generated from the ball bearings 19 and 20 from scattering to the outside of the motor.

The protective cap 25 mounted on the upper surface of the unit prevents the magnetic fluid from scattering to the outside when the magnetic fluid scatters due to a pressure difference or the like.

The rotor hub 21 has a cylindrical portion 21a on the periphery of which a magnetic disk is mounted, a disk mounting portion 21b located at the lower end of the cylindrical portion 21a, and a disk mounting portion 21b.
A cylindrical portion 21c and the like extending downward from b are provided, and a rotor magnet 26 is fixed to the inner periphery of the cylindrical portion 21c. The base of the shaft 17 is formed to have a large diameter, and a stator 27 is fitted around the outer periphery of the base.
To be opposed.

An intermediate step 28 is provided at the center of the shaft 17 between the position where the lower ball bearing 20 is mounted and the position where the stator 27 is mounted. This intermediate stage 2
Numeral 8 regulates the position of the inner ring of the ball bearing 20 and forms a fitting attachment portion for the annular sleeve member 29.

As shown in FIG. 4, the sleeve member 29 has a fitting base portion 29a on the inner peripheral side and a disk portion 29 at the center.
b, and a rising portion 29c upward on the outer peripheral portion side, and the fitting base portion 29a is fitted and fixed to the outer periphery of the intermediate step portion 28 in a state where the fitting base portion 29a is positioned at a step between the stator fixing base portion, The rising portion 29c is inserted into the stepped concave portion 21d at the lower end of the inner peripheral portion of the rotor hub 21.

At this time, the disk portion 29 of the sleeve member 29
b has an upper surface opposed to a lower end surface 20a of the outer ring portion of the ball bearing 20 via a minute gap 30a, and a rising portion 29c of the sleeve member 29 has an inner peripheral surface having an outer peripheral portion 20b of the outer ring portion of the ball bearing 20. At the same time, the outer peripheral portion thereof is opposed to the peripheral surface of the stepped recess 21d via the minute gap 30c. The three minute gaps 30a, 30b, 30c form a labyrinth seal structure for substantially sealing the inside and outside of the motor.

Therefore, in addition to the labyrinth sealing function by the two minute gaps 30a and 30b between the sleeve member 29 and the outer ring of the ball bearing 20, the labyrinth sealing function by the minute gap 30c between the sleeve member 29 and the rotor hub 21. And it is possible to more effectively prevent oil mist, outgas, and the like generated from inside the ball bearings 19 and 20 from scattering outside the motor.

Here, the bracket 18, which is a stationary member, is provided with a thread groove 31 formed by thread cutting on the outer peripheral surface thereof. The outer peripheral surface of the bracket 18 is covered by a cylindrical portion 21c of the rotor hub 21 with a slight gap 32 therebetween.

Accordingly, when the cylindrical portion 21c facing the outside rotates with respect to the thread groove 31 on the outer peripheral surface of the bracket 18, a dynamic pressure is generated by the relative movement between the two, and the inner peripheral portion of the cylindrical portion 21c is generated from outside the bracket 18. Gap 32 between the surface
An air flow is generated through the motor and entering the interior of the motor.

This dynamic pressure depends on the shape of the thread groove 31 and the gap 3
If the pressure inside the motor is not abnormally increased by adjusting the interval or the like, the rotor magnet 26 or the stator 27
Out of the fixing adhesive, etc., can be prevented from flowing out from below the motor.

Although the embodiments of the spindle motor according to the present invention have been described above, the present invention is not limited to such embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. is there.

[0038]

According to the spindle motor of the present invention, between the disk portion and the rising portion of the annular sleeve member fixed to the stationary member, and the side end portion and the outer peripheral surface of the outer ring portion of the ball bearing. Since the small gaps forming the labyrinth seal means are formed, a continuous two-stage labyrinth seal can be formed and a high sealing effect can be obtained. In addition, since the labyrinth seal can be formed using the outer ring of the ball bearing, a predetermined dimensional accuracy can be easily obtained, and no special consideration is required in the processing for defining the minute gap, thereby saving labor in processing and assembly. The effect that can be achieved is obtained.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing a first embodiment of a spindle motor according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG.

FIG. 3 is an overall sectional view showing a second embodiment of the spindle motor according to the present invention.

FIG. 4 is an enlarged sectional view showing a main part of FIG.

FIG. 5 is an enlarged sectional view showing a main part of a seal structure between the bracket and the rotor hub of FIG. 3;

[Explanation of symbols]

 6,21 Rotor hub 8,18 Bracket 10,19 Upper ball bearing 11,20 Lower ball bearing 15,29 Annular sleeve member 15a, 29b Disk portion 15b, 29c Rise 16a, 16b, 30a, 30b, 30c Small gap

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 5/10 H02K 5/16 H02K 5/173 F16C 33/80

Claims (2)

(57) [Claims] (1)Consists of a bracket and a shaftStillness
A stop member,The shaftBall bearing mounted on the ball bearing and the ball bearing
Rotor that is supported for relative rotation with respect to the stationary member via
A spindle motor comprising a hub, wherein the stationary memberAt the position of the base of the shaft in
Larger diameter than the part of the shaft where the ball bearing is fixed
A first large-diameter portion formed and to which the stator is fitted and fixed;
Located at the distal end side of the shaft from the first large diameter portion,
The shaft is larger in diameter than the part where the ball bearing is fixed
An annular sleeve member formed smaller in diameter than the first large diameter portion;
Are fitted and fixed externally, and the inner ring of the ball bearing is
And a second large-diameter portion having an end face for positioning.
And  In the sleeve member,Center hole fits in the second large diameter portion
An annular ring that is joined and abuts against the end face of the first large diameter portionDisk
Part and an axial rising part located at the outer peripheral end of the disk part are formed.
The sleeve member may be configured such that the disk portion is an outer ring portion of the ball bearing.
To the side edgeallPlaced with a slight gap around the circumference
BeWhenIn both cases, the rising portion is on the outer peripheral portion of the outer ring portion of the ball bearing.
On the entire circumference with a slight gap,
Due to the gap between the sleeve member and the ball bearing,
A labyrinth seal means that substantially seals the inside and outside of the
A spindle motor. 2. An inner peripheral portion of the rotor hub is positioned on the outer peripheral side of the rising portion of the outer periphery of the annular sleeve member with a small gap over the entire circumference, and a labyrinth is formed by the clearance between the sleeve member and the rotor hub. 2. The spindle motor according to claim 1, wherein sealing means is provided.