Noise damping device of rotation driving apparatus

Details Noise damping device of rotation driving apparatus Noise damping device of rotation driving apparatus

1999-06-24

2002-03-26

Dang, Khanh (Department: 2837)

Acoustics

Sound-modifying means

Mechanical vibration attenuator

C369S247100, C369S263100, C360S097020

Reexamination Certificate

active

06360843

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a noise damping device of a rotation driving apparatus, which can dampen noise caused by air flow generated when disks such as hard disks installed within a housing are rotated.
2. Description of the Related Art
As an example of a rotation driving apparatus, a hard disk drive (HDD) shown in
FIG. 1
comprises a housing including a base frame
12
installed in a computer main body (not shown) for supporting hard disks
18
and a cover frame
14
assembled to the base frame
12
for protecting the hard disks
18
, and a noise damping device.
The hard disks
18
are rotated by a driving source such as a spindle motor (not shown) installed on the base frame
12
so that a predetermined data recording/reproducing means (not shown) can record data on the hard disks
18
or reproduce the data recorded on the hard disks
18
.
The noise damping device is attached to the outer surface of the cover frame
14
by an adhesive such as a bond or a double-sided bonding tape so that the noise damping device can absorb noise generated within the housing
10
, and comprises a damper member
16
usually manufactured of stainless steel in a thin plate structure.
In the above structure, when the hard disks
18
are rotated at high speed so as to record data on the hard disks
18
or reproduce the recorded data, noise is generated within the housing
10
.
The noise can be classified into, for example, a structure-borne sound such as a solid-borne sound generated when impact and vibrations which a structural body experiences from a driving source propagate through the structural body, and a pneumatic or flow sound such as an air-borne sound generated when a structural body is forcibly vibrated by air flow. The air-borne sound is generated by an irregular eddy flow between a first boundary layer
22
and a second boundary layer
24
wherein the first boundary layer
22
flows in a direction away from a rotation center D between the hard disks
18
and the cover frame
14
, and the second boundary layer
24
flows from outer sides to the rotation center D as shown in FIG.
2
.
The noise generated in the housing
10
can be absorbed and reduced, to a certain extent, by the damper member
16
. However, in the above conventional art, since the damper member
16
for damping noise must be separately attached to the outer surface of the housing
10
, the manufacturing cost is high and more assembly operations are required. In addition, when the temperature within the computer main body rises, the bonding force of the adhesive deteriorates due to heat generated in the computer main body.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a noise damping device of a rotation driving apparatus, the structure of which is improved so that noises can be dampened by fundamentally suppressing abnormal air flow generated when disks rotate within a housing.
Accordingly, to achieve the above objective, there is provided a noise damping device of a rotation driving apparatus comprising: a housing; and at least one rotating disk installed to be rotated by a driving source within the housing, wherein the rotating disk and the housing are assembled to satisfy the following Equation,
&dgr;
m
<h<&dgr;
m
+1.5&dgr;
f
where &dgr;
m
is the thickness of air layers which move from a rotation center of the rotating disk to the outside thereof and are distributed around the rotating disk when the rotating disk rotates at a normal operating speed, &dgr;
f
is the thickness of air layers which move from the outside of the rotating disk to the rotation center thereof and are distributed around an upper inside surface and the base surface of a housing, which face the rotating disk, and h is the distance between the rotating disk and the upper inside surface or the base surface of the housing.
In addition, it is preferable that the housing includes a base frame for supporting the rotating disk, and a cover frame assembled to the base frame to cover the rotating disk. The cover frame is installed on the base frame so that the following Equation can be satisfied,
 &dgr;
m
<h
1
<&dgr;
m
+1.5&dgr;
f
where h
1
is the distance between the rotating disk and the cover frame.
Additionally, it is preferable that the rotating disk is installed on the base frame so that the following Equation can be satisfied,
&dgr;
m<
h
2
<&dgr;
m
+1.5&dgr;
f
where h
2
is the distance between the rotating disk and the base frame.


REFERENCES:
patent: 5761184 (1998-06-01), Dauber et al.
patent: 5781373 (1998-07-01), Larson et al.
patent: 6097568 (2000-08-01), Ekhoff
patent: 6177173 (2001-01-01), Nelson

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