Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-07-06
2002-09-24
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C360S099080, C360S098070
Reexamination Certificate
active
06455965
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spindle motor for driving a magnetic disk employed for a hard disk drive device of a computer.
2. Description of the Related Art
In a hard disk drive device, the development of a large capacity hard disk drive device has been recently promoted. In order to meet the demand for such a large capacity in the hard disk drive device, the spindle motor used in the hard disk drive device must rotate at high speed.
As an example of the spindle motor employed for the hard disk drive device, a device shown in
FIG. 2
has been known. This spindle motor (spindle motor for driving a magnetic disk)
1
comprises a base member
3
provided with a stator
2
and a hub
5
provided with a magnet
4
opposing to the stator
2
. The hub
5
is formed in a substantially tubular shape with a prescribed height so that a magnetic disk (not shown) is fitted to its outer peripheral portion.
The hub
5
comprises a substantially annular hub main body
6
for holding the magnetic disk; a tubular portion with a bottom (hub tubular portion)
7
connected to one end portion (the lower side in
FIG. 2
) of the hub main body
6
; and a tubular hub extended portion
8
extended from the other end portion (the upper side in
FIG. 2
) of the hub main body
6
.
A fixed shaft
10
standing upright on the base member
3
is inserted into a hole (hub hole)
9
formed in the hub main body
6
and the hub extended portion
8
. A bearing cartridge assembly
11
is interposed between the fixed shaft
10
and the hub
5
. The hub
5
is rotatably supported on the fixed shaft
10
through the bearing cartridge assembly
11
.
The bearing cartridge assembly
11
is a bearing (ball bearing) of a type comprising one outer ring
12
and two inner rings (reference numerals are omitted) with a prescribed distance provided therebetween. The end portion of the outer ring
12
in the side of the base member
3
(the lower side in
FIG. 2
, hereinafter referred to as lower outer ring end portion
12
a
) protrudes downward from the hub main body
6
in FIG.
2
. An end portion in the side opposed to the lower outer ring end portion
12
a
of the outer ring
12
(the upper side in
FIG. 2
, hereinafter referred to as upper outer ring end portion
12
b
) substantially reaches the front end portion of the hub extended portion
8
.
In this spindle motor
1
, since the widthwise dimension (span) of the outer ring
12
of the bearing cartridge assembly
11
is relatively large, the rigidity of the bearing cartridge assembly (bearing)
11
is high, and accordingly, the unsteadiness of the hub
5
is prevented and running accuracy is high.
In the spindle motor
1
, it has been desired to reduce the weight thereof In order to attain the purpose, it may be taken into consideration to reduce the length dimension of the fixed shaft
10
and the widthwise dimension (vertical dimension in
FIG. 2
) of the bearing cartridge assembly
11
and determine the height of the hub
5
so as to be substantially equal to the height of the end face of the fixed shaft
10
and the end portion of the bearing cartridge assembly
11
whose dimensions are reduced as described above.
However, in the attempt described above, the widthwise dimension (vertical dimension in
FIG. 2
) of the bearing cartridge assembly
11
is reduced, so that the rigidity of the bearing cartridge assembly
11
is undesirably lowered. Accordingly, the hub
5
is apt to be unsteady upon operation of the spindle motor
1
, so that running accuracy may possibly be deteriorated.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above circumstances, and an object of the present invention is therefore to provide a spindle motor in which the high rigidity of a bearing can be maintained and the weight can be decreased.
For achieving the object described above, according to one aspect of the present invention, there is provided a spindle motor comprising:
a hub to which a magnetic disk is fitted;
a base member;
a fixed shaft vertically provided on the base member; and
a bearing,
the hub being rotatably supported on the fixed shaft through the bearing, characterized in that
an end portion of an outer ring of the bearing at the front end side of the fixed shaft is set to protrude relative to a bearing holding portion of the hub on which the outer ring of the bearing is held.
REFERENCES:
patent: 5045738 (1991-09-01), Hishida et al.
patent: 5138209 (1992-08-01), Chuta et al.
patent: 5160866 (1992-11-01), Hishida et al.
patent: 5639168 (1997-06-01), Noguchi et al.
patent: 5698919 (1997-12-01), Obara
patent: 5821646 (1998-10-01), Chuta et al.
patent: 5841210 (1998-11-01), Obara
patent: 5844748 (1998-12-01), Dunfield et al.
patent: 5860749 (1999-01-01), Hirakawa et al.
patent: RE36086 (1999-02-01), Hishida et al.
patent: 5880545 (1999-03-01), Takemura et al.
patent: 5933292 (1999-08-01), Obara
patent: 5940247 (1999-08-01), Karis
patent: 6217221 (1999-09-01), Abe et al.
patent: 6181513 (2000-01-01), Obara
patent: 2001/0022478 (2001-09-01), Obara et al.
patent: 03277157 (1991-12-01), None
patent: 000592214 (1993-07-01), None
patent: 000597678 (1993-09-01), None
patent: 06153447 (1994-04-01), None
Merriam-Webster's Collrgiate Dictionary, 10th ed., Merriam-Webster Incorporated, pp. 1006-1007.
Elkassabgi Heba Yousri
Minebea Co. Ltd.
Tamai Karl
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