JPH0686499A - Spindle motor - Google Patents

Abstract

PURPOSE:To seal/up the inside of a spindle motor reliably and thereby to prevent impure air from leak outside by fitting a magnetic fluid seal and a filter member. CONSTITUTION:A magnetic fluid seal 10 so provided as to be interposed between a magnetic ring 25 and a spacer member 6 is fitted on the outside in the direction of the 29 of rotation of a lower-side ball bearing 8. On the outside in the direction of the axis 29 of rotation of an upper-side ball bearing 7, a filter member 9 is provided in such a manner that it is stuck on the top side of a stepped part 40 in the small-diameter part 22 of a hub member 1. By the magnetic fluid seal 10 and the filter member 9 provided in this way, impure air existing in an internal space 41 of a spindle motor can be prevented from leaking out into an external space 42 of the spindle motor. Since no air pressure difference occurs between the inside and the outside of the spindle motor, in addition, a burst or scattering of a magnetic fluid in the magnetic fluid seal does not occur even when the environment of the operation of the spindle motor changes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor used for rotationally driving a recording disk such as an optical / magnetic disk.

[0002]

2. Description of the Related Art For example, a labyrinth seal is used in a spindle motor used in a magnetic disk drive or the like as a sealing means for preventing unclean air inside from leaking to the disk chamber (that is, outside the spindle motor). Has been. The labyrinth seal makes a gap between a hub member, which is a rotating body, and a bracket (housing), which is a stationary member, close to each other and substantially seals the inside and outside of the spindle motor. Further, another sealing means is a magnetic fluid seal. The magnetic fluid seal is provided so as to be interposed between the hub member and, for example, a fixed shaft, and is mounted on the outer side (outward of the spindle motor) of each of the pair of ball bearings that rotatably supports the hub member. The inside and outside of the spindle motor are sealed by the magnetic fluid seal layer.

[0003]

However, in the labyrinth seal, the gap formed between the hub member and the bracket communicates the inside and the outside of the spindle motor, and the rotation of the spindle motor is stopped. During this period, the labyrinth seal's sealing function cannot be fully obtained. Therefore, it is necessary to form the communication path long and minute, which has been a factor of increasing the manufacturing cost required for this. In addition, while the magnetic fluid seal has high sealing performance, the magnetic fluid seal layer that seals the inside and outside of the spindle motor bursts and scatters due to a rise in the temperature of the motor and changes in internal and external atmospheric pressure. Due to this, the sealing function may be lost.

The present invention has been made in view of the above problems existing in the prior art. The problem is that the present invention can be carried out easily at a low manufacturing cost, and the spindle can be used. An object of the present invention is to provide a highly reliable spindle motor that reliably seals the inside of the motor and prevents unclean air from leaking to the outside of the spindle motor.

[0005]

In order to achieve the above object, as a first means of a spindle motor of the present invention, a hub member on which a recording disk is mounted, a stationary member, the hub member and the stationary member. A first and a second bearing member provided between the hub member and the stationary member, wherein the hub member is a spindle motor driven to rotate relative to the stationary member; Between the stationary member,
A magnetic fluid seal is mounted on the outer side of the first bearing member in the rotational axis direction, and a filter member is provided on the hub member on the outer side of the rotational axis of the second bearing member,
A spindle motor is provided, wherein the magnetic fluid seal and the filter member substantially prevent unclean air from leaking from the inside of the spindle motor.

As a second means of the spindle motor of the present invention, a hub member on which a recording disk is mounted,
A stationary member and first and second bearing members provided between the stationary member and the hub member, wherein the hub member is driven to rotate relative to the stationary member. A spindle motor; the first and second bearing members are loaded with a lubricant, the first bearing member is loaded with more lubricant than the second bearing member, and The first bearing member is loaded with a filling amount of the lubricant that blocks the communication of air in the direction of the rotation axis; the rotation axis of the first bearing member between the hub member and the stationary member. A labyrinth seal formed by the hub member and the stationary member is formed outward in the direction, and a filter member is provided on the hub member outward in the rotation axis direction of the second bearing member. With the filter member Substantially to prevent unclean air is leaking from the inside spindle motor, the spindle motor is provided, characterized in that.

[0007]

In the spindle motor of the first means among the spindle motors according to the present invention, a magnetic fluid seal is mounted between the hub member and the stationary member on the outer side in the rotational axis direction of the first bearing member. There is. This prevents unclean air from leaking from the first bearing member side. Next, since the filter member is provided on the hub member outside the rotation axis of the second bearing member, it is possible to prevent unclean air from leaking from the second bearing member side. Since the inside and the outside of the spindle motor are sealed by these sealing means, unclean air inside the motor does not leak out. Moreover, since the filter member allows air to pass therethrough, the inside and the outside of the spindle motor are in communication with each other. Therefore, since there is no difference in atmospheric pressure between the inside and the outside of the spindle motor, bursting or scattering of the magnetic fluid in the magnetic fluid seal does not occur.

Next, in the spindle motor of the second means among the spindle motors of the present invention, the hub member is provided between the hub member and the stationary member in the outer side in the rotation axis direction of the first bearing member. A labyrinth seal is formed by the stationary member, and the first bearing member is
The amount of lubricant loaded blocks the air communication in the direction of the rotation axis. Therefore, of course, scattering and leakage of the lubricant itself from the first bearing member side is suppressed,
The impure air containing this is prevented from leaking to the outside of the spindle motor in combination with the labyrinth seal effect. Further, on the outer side in the rotation axis direction of the second bearing member,
Since the filter member is provided on the hub member,
Leakage of unclean air from the second bearing member side is prevented. Moreover, since the filter member is permeable to air,
Since the inside and the outside of the spindle motor are in communication with each other and the second bearing member substantially communicates with air, there is no pressure difference between the inside and outside of the spindle motor. Therefore, the first
Also, the lubricant loaded in the bearing member is not pushed out of the spindle motor.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a spindle motor according to the present invention will be described in detail with reference to FIGS. FIG. 1 shows a first embodiment of a spindle motor of the present invention, for example, a spindle motor for rotationally driving a magnetic disk. FIG. 1 is a sectional view showing the entire structure. In FIG. 1, the member 1 is a hub member on which the magnetic disk 5 is mounted. The hub member 1 has a cup shape that penetrates the top and bottom of the drawing, and is made of, for example, an aluminum material. The magnetic disk 5 has a flange portion 21 on the outer peripheral portion 19 of the hub member 1.
The required number of sheets are mounted by stacking them in the order from the top of the figure. Spacers 43 are provided between the mounted magnetic disks 5. The clamp member 11 is attached to the magnetic disk 5 located at the uppermost portion, and thus the magnetic disk 5 is held. Then, the small diameter portion 22 of the hub member 1
The magnetic disk 5 is integrally fixed to the hub member 1 by screwing the screw 13 into the screw hole 15 provided in the. An annular rotor magnet 4 is fixed by adhesion to the substantially central portion of the inner peripheral portion 18 of the hub member 1 via a yoke member 14 made of a ferromagnetic material. The rotor magnet 4 is alternately magnetized with N poles and S poles in the circumferential direction, and is provided with a predetermined number of poles.

The member 2 is a shaft as a stationary member, and is made of an iron material or the like. Although not shown, a base member of the magnetic disk drive is attached to the lower side of the shaft 2 in the figure, and a hole 3 provided at the lower end of the shaft 2 is provided.
1 is fitted and positioned. Then, the shaft 2 and the base member are fixed to each other by screwing into the screw hole 17 using a screw (not shown). A pair of upper and lower ball bearings 7, 8 are mounted on both ends of the shaft 2, and an inner ring portion 34 of the upper ball bearing 7 and an inner ring portion 32 of the lower ball bearing 8 are attached to an outer peripheral portion 38 of the shaft 2. It is fixed by press fitting or adhesion. The inner ring portion 32 of the lower ball bearing 8
Is positioned and fixed in the direction of the rotation axis 29 by the step portion 28 formed on the shaft 2. The outer ring portion 35 of the upper ball bearing 7 is adhesively fixed to the inner peripheral portion 39 of the small diameter portion 22 of the hub member 1, and the outer ring portion 33 of the lower ball bearing 8 is similarly bonded to the inner peripheral portion 23 of the spacer member 6. Adhesively fixed. Further, the outer peripheral portion 24 of the spacer member 6 is fixed to the inner peripheral portion 18 of the hub member 1. As a result, the hub member 1 is rotatably supported by the shaft 2 via the upper and lower spherical bearings 7 and 8 and is coaxially rotated with respect to the rotation axis 29.

An armature 3 is fitted in and fixed to the shaft 2 at a substantially central portion thereof. The armature 3 is positioned in the direction of the rotation axis 29 by the step portion 28 formed on the shaft 2. The armature 3 includes a stator core 36 formed by laminating a required number of thin electromagnetic steel plates, and an armature coil 37 wound around the stator core 36. The armature 3 is arranged so as to face the rotor magnet 4 mounted on the hub member 1, and has teeth with a required number of magnetic poles. The lead wire 12 drawn out from the armature coil 37 is led to the lower side of the shaft 2, that is, the base member side (not shown), through the slit-shaped notch 16 formed in the shaft 2, and electrically connected. Therefore, the lead wire 1
When the required electric power is applied to the hub 2, the hub member 1 is moved to the shaft 2 by the electromagnetic action of the armature 3 and the rotor magnet 4.
It is driven to rotate relative to. The member 20 attached to the lower end of the flange 21 of the hub member 1 is a rotation detection magnet. The rotation detection magnet 20 is formed in an annular shape and is arranged so as to face a detector provided on a base member (not shown).

On the outer side of the lower ball bearing 8 in the direction of the rotation axis 29, that is, on the lower side in the figure, it is provided between the magnetic ring 25 fitted in the outer peripheral portion 38 of the shaft 2 and the spacer member 6. The magnetic fluid seal 10 is attached. The magnetic fluid seal 10 is a donut-shaped magnet 4
5 and two tabular pole pieces 46 and 47 made of a magnetic material that sandwich the magnet 45. The outer peripheral surface of the spacer member 6 is adhered and fixed to the stepped inner peripheral portion 30 of the spacer member 6. A magnetic fluid 27 is filled and held in a space between the pole pieces 46 and 47 and the magnetic ring 25 facing each other, and the magnetic fluid sealing layer is used to particularly downward from the lower ball bearing 8 (outward of the spindle motor). Seals unclean air that is about to leak out. In addition, in the spindle motor of the present embodiment, as a holding portion for the magnetic fluid 27,
The magnetic ring 25 for forming a magnetic path with the pole pieces 46 and 47 is used. This is the outer peripheral portion 3 of the shaft 2.
This is because there is a slit-shaped notch groove 16 formed on the surface 8. Therefore, for example, in order to lead out the lead wire 12, if the through hole is provided in the shaft 2 instead of the cutout groove 37, the above-mentioned magnetic ring 25 becomes unnecessary. Further, when the shaft 2 is made of a non-magnetic material such as an aluminum material, it goes without saying that it is effective to mount the magnetic ring 25. Magnetic fluid seal 1 in the direction of rotation axis 29
On the outer side of 0, that is, on the lower side of the figure, a magnetic fluid protection cap 26 is attached to the spacer member 6.

A filter member 9 is provided on the outer side of the upper ball bearing 7 in the direction of the rotation axis 29, that is, on the upper side in the drawing. The filter member 9 includes the small diameter portion 22 of the hub member 1.
Is attached and provided on the upper surface of the step portion 40 in
This closes the upper ball bearing 7 to the outside of the spindle motor (upper part in the figure). As the filter member 9, for example, a member formed by laminating a fluororesin PTFE (polytetrafluoroethylene) on a support base made of polyethylene scrim or polyester non-woven fabric can be used. And the filter 9 has a collection efficiency of 99.997%.
(However, it has a capacity of 0.1 μm dust). The filter member 9 seals unclean air which is about to leak from the upper ball bearing 7 in the upward direction of the drawing (outward of the spindle motor). As is clear from the figure, the filter member 9 rotates integrally with the hub member 1,
The filter performance is improved compared to the stationary state. Thus, the magnetic fluid seal 10 and the filter member 9 can effectively prevent the unclean air existing in the spindle motor internal space 41 from leaking to the spindle motor external space (that is, the magnetic disk indoor space) 42. . Moreover, since the filter member 9 allows air to pass therethrough, the spindle motor inner space 41 and the outer space 42 are in communication with each other. Therefore, since there is no pressure difference between the inside and the outside of the spindle motor, bursts or scattering of the magnetic fluid in the magnetic fluid seal does not occur even if the temperature of the spindle motor rises or the operating environment changes.

Next, a second embodiment of the spindle motor according to the present invention will be described in detail with reference to FIG. The spindle motor of the second embodiment is also a spindle motor that rotationally drives a magnetic disk as in the first embodiment already described. FIG. 2 is a sectional view showing the whole. In FIG. 2, the member 67 is an upper base member that defines the disk chamber of the magnetic disk drive device, and the member 70 is also a lower base member. These upper and lower base members 67, 70
Are integrally formed of, for example, an aluminum material. A part of the lower base member 70 also serves as a bracket (housing) of the spindle motor, and a bracket (housing) of the spindle motor is formed by a portion of the annular recess 93 and the annular side wall 89 which are lowered by one step as shown in the figure.
Is prescribed. A hole 88 is provided in the center of the annular recess 93 in the radial direction, and the lower end of the shaft 52 is press-fitted into the hole 88 and fixed. Therefore, in the spindle motor of the second embodiment, the lower base member 70 and the shaft 52 form a stationary member.

A pair of upper and lower ball bearings 57 and 58 are mounted on both ends of the shaft 52.
The inner ring portion 85 and the inner ring portion 83 of the lower ball bearing 58 are fixed to the outer peripheral portion 87 of the shaft 52 by press fitting or bonding. The inner ring portion 83 of the lower ball bearing 58 is positioned and fixed in the direction of the rotation axis 79 by the step portion 78 formed on the shaft 52. The outer ring portion 86 of the upper ball bearing 57 is connected to the inner peripheral portion 91 of the small diameter portion 72 of the hub member 51.
Similarly, the outer ring portion 84 of the lower ball bearing 58 is also adhesively fixed to the inner peripheral portion 92 of the spacer member 56. Further, the outer peripheral portion 90 of the spacer member 56 is fixed to the inner peripheral portion 68 of the hub member 1. As a result, the hub member 51 is rotatably supported by the shaft 52 via the ball bearings 57 and 58 located on the upper and lower sides, and the rotation axis 79 is provided.
Is rotated coaxially with respect to.

A flange portion 71 for positioning and mounting the magnetic disk 55 is formed on the outer peripheral portion 69 of the hub member 51. First, the magnetic disk 55 is mounted on the collar portion 71. Next, an annular groove 75 formed on the top of the collar 71
An O-ring 61, which is a clamp member, is attached to the. Further, the second magnetic disk 55 is inserted through the spacer member 73.
And the O-ring 61 is similarly mounted in the annular groove 75. The snap ring 63 is fitted and fixed to the annular groove 76 at the uppermost portion. O ring 6 at this time
The contact portion between the magnetic disk 55 and the magnetic disk 55 (indicated as the upper surface of the inner peripheral end in the figure) also acts on the magnetic disk 55 side by the contracting force of the O-ring 61. Due to this acting force, the magnetic disk 55 is integrally fixed to the hub member 51 with an even holding force.

A rotor magnet 54 is attached and fixed to the inner peripheral portion 68 of the hub member 51. Hub member 5
Since 1 is made of, for example, magnetic stainless steel, the rotor yoke shown in the spindle motor of the first embodiment is omitted. An armature 53 is attached to a substantially central portion of the shaft 52 so as to face the rotor magnet 54. The armature 53 includes an armature coil 82, a stator core 81, and an armature coil 82, similar to the spindle motor of the first embodiment.
Is wound and formed. The armature 53 is positioned and fixed in the direction of the rotation axis 79 by the step portion 78 of the shaft 52. The lead wire 62 drawn out from the armature coil 82 is inserted into the tube 60 made of an insulating resin, and led out of the spindle motor through the slit-shaped notch 66 formed in the shaft 52.

The annular concave portion 93 of the lower base member 70 and the bottom surface portion 94 of the spacer member 56 are arranged so as to face each other with a minute gap, and the annular side wall 89 of the lower base member 70 and the hub member 51 are arranged. The outer peripheral portion 69 at the lower end of
Similarly, they are arranged to face each other with a minute gap. These constitute a labyrinth seal 64 that forms a communication path from the lower ball bearing 58 of the spindle motor to the external space 74 of the spindle motor (that is, the disk interior space) 74. That is, the labyrinth seal 64 is positioned outside (spindle motor) of the lower ball bearing 58 in the direction of the rotation axis 79, and is provided between the hub member 51 and the lower base member 70.

With respect to the labyrinth seal 64, the lower ball bearing 58 is loaded with a lubricant, which is more loaded than normal. That is, the sphere 99 and the cage 97, which are formed inside the bearing, (and the shield member 95)
The lubricant is loaded in the voids other than the above, but the amount of the lubricant that sufficiently closes the voids is loaded. Specifically, the ratio of the amount of the lubricant to the void portion is achieved by filling 25% to 30% or more depending on the type of the ball bearing. For this reason, the binding force of the lubricant itself is increased, and the scattering of fine particles of the lubricant can be effectively suppressed. A shield member 95 is provided on the lower ball bearing 58 to further enhance this effect. Thus
Air communication is blocked in the direction of the rotation axis 79 of the lower ball bearing 58 (the vertical direction in the drawing). For this reason, the labyrinth seal 64 has a relatively simple structure, yet has a sufficient sealing function, and does not require complicated and accurate machining and assembly as in the conventional case.

A filter member 59 is provided on the outer side of the upper ball bearing 57 in the direction of the rotation axis 79, that is, on the upper side in the drawing. The filter member 59 is provided while being positioned and adhered to the upper surface of the annular groove 65 in the small diameter portion 72 of the hub member 51, whereby the upper ball bearing 57 is closed to the outside of the spindle motor (upper part of the drawing). To do.
The filter member 59 uses the same members and materials used in the first embodiment. The upper ball bearing 57 is loaded with a lubricant, but unlike the lower ball bearing 58, a normal amount of lubricant is loaded. (The ratio of the amount of lubricant to the void in the ball bearing is 15% to 25%.) Therefore, there is air communication in the direction of the rotation axis 79 (upper and lower in the figure) of the upper ball bearing 57, and Compared to the side ball bearing 58, scattering of fine particles of the lubricant is more likely to occur, but the filter member 5
By means of 9, it is possible to effectively seal the impure air (including fine particles of the lubricant) which is about to leak from the upper ball bearing 57 in the upward direction of the drawing (outward of the spindle motor). The upper ball bearing 57 shown in the drawing includes a shield member 9
Although 6 is provided, there is substantially no problem even if omitted, so that the thickness of the ball bearing itself can be reduced, and the spindle motor can be made thinner.

Thus, the labyrinth seal 64 and the filter member 59 effectively prevent the unclean air existing in the spindle motor internal space 80 from leaking to the spindle motor external space (that is, the magnetic disk indoor space) 74. You can Moreover, since the filter member 59 and the upper ball bearing 57 allow air to pass therethrough, the spindle motor inner space 80 and the outer space 74 are in communication with each other. Therefore, since there is no pressure difference between the inside and the outside of the spindle motor, even if the temperature of the spindle motor rises or the operating environment changes, the lubricant loaded in the lower ball bearing 58 may be extruded and extruded. Absent.

As described above, design changes and modifications can be freely made without departing from the spirit of the present invention. In the spindle motor of the first embodiment, the hub member 1 is rotatably supported by the shaft 2 as a stationary member, but like the spindle motor of the second embodiment, it is formed integrally with the lower base member 70. May be. Alternatively, the reverse combination may be used. The filter members 9 and 59 are not limited to the above-described configurations and materials, and can be freely designed such as shape, thickness, and attachment method. Further, it goes without saying that the configurations and shapes of the magnetic fluid seal 10 and the labyrinth seal 64 can be freely selected. In addition, in the spindle motor of the second embodiment, the loading amount of the lubricant of the lower ball bearing 58 is increased with respect to the upper ball bearing 57, but in addition to this, the viscosity of the lubricant is adjusted to obtain a better sealing effect. Can be enhanced.

[0023]

Since the spindle motor of the present invention has the above-mentioned structure, it has the following effects. In other words, it can be carried out easily without incurring much manufacturing cost.
Moreover, the inside of the spindle motor is securely sealed so that unclean air does not leak to the outside of the spindle motor.
A highly reliable spindle motor can be obtained.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an entire spindle motor according to a second embodiment of the present invention.

[Explanation of symbols]

 1,51 Hub member 2,52 Shaft 3,53 Armature 4,54 Rotor magnet 5,55 Magnetic disk 9,59 Filter member 12,62 Lead wire 16,66 Notch groove 10 Magnetic fluid seal 25 Magnetic ring 64 Labyrinth seal

Claims (2)

[Claims] 1. A hub member on which a recording disk is mounted,
A stationary member and first and second bearing members provided between the stationary member and the hub member, wherein the hub member is driven to rotate relative to the stationary member. A spindle motor comprising: the first member between the hub member and the stationary member;
A magnetic fluid seal is mounted on the outer side of the bearing member in the rotational axis direction, and a filter member is provided on the hub member on the outer side of the rotational axis direction of the second bearing member. A spindle motor, wherein the filter member substantially prevents unclean air from leaking from the inside of the spindle motor. 2. A hub member on which a recording disk is mounted,
A stationary member and first and second bearing members provided between the stationary member and the hub member, wherein the hub member is driven to rotate relative to the stationary member. And a lubricant is loaded in the first and second bearing members,
The first bearing member is loaded with a larger amount of lubricant than the second bearing member, and the first bearing member has a filling amount of lubrication that blocks air communication in the rotation axis direction. An agent is loaded, the first member between the hub member and the stationary member
A labyrinth seal formed by the hub member and the stationary member is formed outside the bearing member in the rotation axis direction, and a filter member is provided on the hub member outside the rotation shaft direction of the second bearing member. By the labyrinth seal and the filter member,
A spindle motor, which substantially prevents unclean air from leaking from the inside of the spindle motor.