JPH0296981A - Spindle motor - Google Patents

Abstract

PURPOSE:To prevent dust from infiltration into a spindle motor and, at the same time, to expand the bearing interval and to eliminate the vibration of the rotary shaft of the motor by sealing hermetically a lower bearing section including the lower end face of the shaft with a cover when an upper and lower bearings are supported by attaching the rotary shaft of the spindle motor to a housing. CONSTITUTION:When the rotary shaft 2 of this spindle motor is inserted into a through hole provided on a housing, a lower ball bearing 4 is provided on the bottom section of the housing 1 and, at the same time, an upper ball bearing 3 is provided on the upper section at a distance from the bottom section to support the lower surface of a collar on the rotary shaft 2 with the upper ball bearing 3. In such a constitution, the lower ball bearing 4 section including the exposed lower end of the rotary shaft 2 is hermetically sealed with a newly fitted cover 8 to prevent the infiltration of dust into the inside. A stator 5, magnet 6, and hub 7 surrounding the stator 5 and magnet 6 are provided on the outside of the projecting part of the cover 1 supporting the upper ball bearing 3 as usual.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spindle motor, and particularly to a spindle motor for a magnetic disk drive.

[Conventional technology]

In conventional spindle motors, the rotating shaft part is exposed to the outside of the device, so air containing a large amount of dust passes from the ball bearing part through the inside of the spindle motor, where the pressure decreases due to the high speed rotation of the shaft. be sucked into equipment that requires high environmental conditions.

For this reason, as shown in FIG. 2, a magnetic fluid seal 9 is installed on the top of the housing 1 that holds the rotating shaft to improve the airtightness of the rotating shaft and prevent dust from entering from outside.

[Problem to be solved by the invention]

The conventional spindle motor mentioned above has a magnetic fluid seal installed inside the housing, so it is not possible to secure a wide gap between the upper and lower ball bearings that support the rotating shaft, which causes axial wobbling or falling of the rotating shaft. However, magnetic fluid seals also have the disadvantage that when the pressure difference between the inside and the outside is large, the magnetic fluid ruptures and scatters.

[Means to solve the problem]

The spindle motor of the present invention includes a housing, a ball bearing attached to the housing, a rotating shaft held by the ball bearing, a hub fixed to the rotating shaft and rotating together, and a hub installed in the housing. A spindle motor having a stator and a magnet installed in the hub at a position opposite to the stator, including a cover attached to a position surrounding the end surface of the rotating shaft of the housing.

〔Example〕

The present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.

The spindle motor is fixed to the magnetic disk device by a housing 1. The rotating shaft 2 and the hub 7 are connected to the housing 1
It is held in the center by an upper ball bearing 3 and a lower ball bearing 4, and is rotated by a stator fixed to the housing 1 and a magnet 6 fixed to the hub 7.

Since the rotating shaft 2 passes through the inside of the housing 1, the air inside and outside the magnetic disk mounting is exchanged through the gap between the upper and lower ball bearings. Furthermore, while the spindle motor is rotating, the pressure inside the hub 7 is low, so that air containing a large amount of dust flows into the hub 7 through the ball bearing.

For this reason, a cover 8 is installed at the lower part of the housing 1 at a position where the rotating shaft 2 is exposed to the outside so as to seal the rotating shaft 2 and the lower ball bearing 4, thereby blocking the inside and outside of the spindle motor.

〔Effect of the invention〕

As explained above, the spindle motor of the present invention prevents dust from entering the inside of the magnetic disk drive from the outside by installing a cover that seals the rotating shaft and ball bearings in the part where the rotating shaft is exposed to the outside. This has the effect of widening the spacing between the ball bearings that support the rotating shaft, reducing shaft runout and tilting. Furthermore, since there is no possibility of seal rupture due to the high pressure difference between the inside and outside of the magnetic disk device, it is possible to provide a high quality and highly reliable magnetic disk device that can increase the internal pressure of the magnetic disk device. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing an example of the conventional technology. DESCRIPTION OF SYMBOLS 1...Housing, 2...Rotating shaft, 3...Upper ball bearing, 4...Lower ball bearing, 5...
... Stator, 6... Magnet, 7... Hub, 8
...Cover 9...Magnetic fluid seal.

Claims (1)

[Claims] a housing, a ball bearing attached to the housing, a rotating shaft held by the ball bearing, a hub fixed to the rotating shaft and rotating together, a stator installed in the housing, and a shaft inside the hub. and a magnet installed at a position facing the stator, the spindle motor comprising a cover attached to a position surrounding the end face of the rotating shaft of the housing.