Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
2001-11-13
2004-05-04
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S296000, C384S535000
Reexamination Certificate
active
06729764
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a metal bearing liner and an improved axial flow fan motor provided with the same.
2. Description of Related Art
Various types of office automation (OA) apparatuses have a large number of electronic circuits enclosed in the housing thereof, whereby heat may be generated by the electronic circuits giving a bad influence on some of electronic devices of the apparatus. The remarkable technical advancement of a microprocessor unit (hereinafter referred to as “MPU”) for a personal computer (PC) has been realized leading to a further improvement for higher-integration, higher respond speed and higher-functionality. On the other hand, the heat generated by the MPU has been continuously increased in its amount contrary to the fact that the housing space tends to be reduced in order to downsize the main body of the apparatus. Accordingly, it has become an important technical task to devise effective measures against heat.
An OA apparatus in general is provided with a ventilation hole formed on a side wall of the housing thereof, and an axial flow fan motor
21
(see
FIG. 7
) is provided on the back side wall of the ventilation hole (inside of the housing) in order to radiate the generated heat from the MPU to the outside of the housing. The axial flow fan motor
21
shown in
FIG. 7
is one of the examples of the axial flow type fan motors wherein an impeller
23
rotates in a resin-made casing
22
. As shown in
FIGS. 7 and 8
, a motor housing
24
is integrally formed with the casing
22
at the substantially center thereof, and a substantially cylindrical metal bearing liner
25
formed by an insert molding is set so as to stand at the center of the motor housing
24
.
As shown in
FIG. 7
, the outer peripheral surfaces of a pair of bearings
26
are fitted and fixed on the inner peripheral surface of the bearing liner
25
in such a manner that a shaft
27
is rotatably supported by those bearings
26
. Moreover, a motor yoke
29
is fixed to the shaft
27
through a zinc die-cast-made bush
28
. The base portion
23
a
of the impeller
23
is fixed on the outer peripheral surface
29
a
of the motor yoke
29
, and a magnet
34
is disposed on the inner peripheral surface
29
b
of the yoke
29
. And, the shaft
27
, the motor yoke
29
, the impeller
23
and the magnet
34
constitute a rotary part.
Furthermore, as shown in
FIG. 7
, a stator
31
composed of a stator core
31
a
and stator wire
31
b
wound therearound is fitted on the outer peripheral surface
30
of the bearing liner
25
. A PC board
32
composed of electronic circuits is provided beneath the stator
31
. In the present axial flow fan motor
21
, the PC board
32
controls the current to be supplied to the stator
31
. A reference numeral
33
in
FIG. 7
refers to a lead wire for supplying a power source current to the electronic circuits on the PC board
32
.
The axial flow fan motor
21
thus structured is required to obtain a high cooling performance, a low current consumption, quietness, and a long life. Accordingly, the bearings
26
for supporting the rotary part are needed to reduce torque and noise and to elongate the life. Furthermore, the bearing liner
25
holding the bearings
26
is required to have a high roundness and cylindricality in its bearing fitting portions
35
(see
FIG. 8
) to which the outer rings of the bearings
26
are fitted. Consequently, the conventional bearing liner
25
has been formed by a cutting work in order to obtain a high accuracy. That is, the outer peripheral surface
30
has to be provided so as to form a ring-shaped groove
36
preventing the fall out of the bearing liner
25
and a knurl
37
preventing the rotation of the bearing liner
25
. Such cutting work of the bearing liner
25
is intricate and requires frequent tooling change and many process, which increase the manufacturing cost of the bearing liner
25
resulting in the cost increase of the axial flow fan motor
21
.
SUMMARY OF THE INVENTION
The present invention was made in light of the above, and it is an object of the present invention to provide a metal bearing liner and an axial flow fan motor provided with the same formed by an insert molding to the resin-made motor housing thereof. In the present invention, the metal bearing liner conventionally formed by a cutting work can be formed by a press work while maintaining a requisite accuracy so that the manufacturing cost of the metal bearing liner, that is, the cost of the axial flow fan motor is reduced.
For attaining the aforementioned object, according to the first aspect of the present invention, there is provided a metal bearing liner formed into a substantially cylindrical shape and performed for an insert molding to a resin-made motor housing, which has an inner peripheral surface to which a bearing for supporting a shaft of a rotary part is fitted, wherein the metal bearing liner is formed by sequentially performing a plurality of press processes over a progressive sheet material.
In the aforementioned structure, the metal bearing liner with a requisite accuracy can be obtained through the press work.
According to the second aspect of the present invention, a plurality of projecting portions for positioning the bearing are provided on the inner peripheral surface of the bearing liner.
In the aforementioned structure, the bearing can be positioned in the axial direction of the bearing liner.
According to the third aspect of the present invention, a flange is provided at the base portion of the bearing liner and a notch is disposed at a side edge of the flange.
In the aforementioned structure, because the insert molding is performed for the metal bearing liner to a resin-made motor housing, the flange can prevent the come out of the bearing liner and the notch can also prevent the rotation of the bearing liner.
According to the fourth aspect of the present invention, the insert molding is performed for the bearing liner to the motor housing by inpouring a resin into recesses formed on the back of the projecting portions.
In the aforementioned structure, it will be possible to perform the insert molding for the bearing liner to the motor housing, by which the resin inpours into the recesses of the bearing liner, so that the come out as well as the rotation of the bearing liner with respect to the motor housing can be prevented.
According to the fifth aspect of the present invention, there is provided the axial flow fan motor including the metal bearing liner formed into a substantially cylindrical shape and performed for the insert molding to the resin-made motor housing in such a manner that the bearing liner stands therein, in which the metal bearing liner is formed by sequentially performing a plurality of press processes over a progressive sheet material
In the aforementioned structure, the metal bearing liner can be formed through the press work (progressive press work) instead of conducting the conventional cutting work when performing the insert molding to the motor housing in the axial flow fan motor.
REFERENCES:
patent: 3924908 (1975-12-01), Gotham et al.
patent: 4746231 (1988-05-01), Hoshino
patent: 4783608 (1988-11-01), Gruber et al.
patent: 4955791 (1990-09-01), Wrobel
patent: 5319851 (1994-06-01), Ikezawa et al.
patent: 6312159 (2001-11-01), Ishida et al.
patent: 42 24 817 (1994-02-01), None
patent: 0 011 957 (1980-06-01), None
Kobayashi Eiichi
Matsumoto Kaoru
Sawayama Kazunori
Footland Lenard A.
Minebea Co. Ltd.
Oliff & Berridg,e PLC
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