Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2000-06-26
2002-04-09
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S423100
Reexamination Certificate
active
06368081
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement of a blower for use in various kinds of office automation apparatus.
2. Description of the Related Art
In various kinds of office automation apparatus, since a large number of electronic circuits are housed in a box of the apparatuses, it is difficult to discharge heat generated by electronic components forming the electronic circuits, and thus, there is a fear that a part of the electronic components may be broken or deteriorated. In particular, in the context of the recent trend toward miniaturization of office automation apparatuses, since the apparatuses are miniaturized while the quantity of heat generated almost remains the same, how to deal with the heat is an important technical problem to be solved. In order to solve the problem, an air vent for attaching a blower therein is provided in a side wall of an apparatus to discharge the heat inside to the outside of the apparatus, thereby preventing damage due to the heat generated inside.
An example of a conventionally often used blower is described with reference to FIG.
3
. Sign
1
shows a casing which is tubular. An integrally molded housing
2
is provided on the right in
FIG. 3
inside the casing
1
. A bearing liner
3
is inserted into the housing
2
. Outer races of bearings
4
and
5
are supported by the inner side of the bearing liner
3
, and a shaft
6
is inserted into the inner races of the bearings
4
and
5
. A race
7
is attached to the lower end of the shaft
6
for preventing the shaft
6
from falling off and for axially positioning the shaft
6
.
Knurl
8
is provided on the upper end of the shaft
6
, and is fixed to a boss
9
formed by die casting zinc. Springs
10
are provided between the boss
9
and the inner race of the bearing
4
for providing thrust load on the bearing
4
. A center portion of a cup-like motor yoke
11
is fixed to the boss
9
. On the boss
9
, the central portion of a cup shaped yoke
11
is fixed, and on the inner peripheral portion, a ring shaped magnet
12
is fixed. A body portion
15
of an impeller
14
provided with blades
13
is fixed to the outer peripheral portion of the motor yoke
11
. The shaft
6
, the motor yoke
11
and the impeller
14
form a rotating portion.
A stater core
17
around which a stator winding
16
is wound, is provided in the inner peripheral portion of the motor yoke
11
to form a fixed portion. A pin-like connection terminal
18
is provided in a projected manner from the stator core
17
downwardly to pierce a PC board
19
supported by the housing
2
. An electronic circuit is mounted on the PC board
19
for controlling the current to be supplied to the stator winding
16
.
FIG. 4
is a front view of the impeller
14
shown separately from the other elements in
FIG. 3
, and
FIG. 5
is a half section of the impeller
14
taken along the line
5
—
5
in FIG.
4
. As shown in
FIG. 4
, the blades
13
are arc-like. The large number of blades
13
are attached to the body portion
15
radially to form the impeller
14
. The configuration of the body portion
15
is, as shown in
FIG. 5
, formed in an outwardly cup shape. To the radially extended portion
15
a
the inner peripheral portions of the blades
13
are fixed.
The blower structured as described above is used by mounting on an air vent in a box of an office automation apparatus. The blower is attached such that the top in
FIG. 3
is the outer side of the box of the office automation apparatus and the shaft
6
is horizontally oriented. In that state, when power is supplied through the control circuit on the PC board
19
, controlled current passes through the stator winding
16
to generate magnetic flux through the stator core
17
. Then, the magnetic interference between the magnetic flux and the magnetic flux generated by the magnet
12
rotates the rotating portion. Due to the rotation of the impeller
14
, the air sucked from the center of the impeller
14
flows radially by the centrifugal force. The air is then collected in the casing
1
and is discharged from an outlet (not shown) provided in the casing
1
. By this blowing, the inside of the box is cooled.
The required characteristics of a blower of this kind is represented as the relationship between the pressure P and the flowing rate Q, i.e., the P-Q characteristics. Among blowers of a given size, one with a high air flow pressure and with a large amount of air flow is determined to be one with satisfactory P-Q characteristics. When circumstances do not allow the blower to be larger and still the P-Q characteristics have to be improved, the improvement can be attained by increasing the number of rotations. However, there is a problem that merely increasing the number of rotations not only increases the noise when the blower is in operation but also shortens the lifetime of the blower.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above, and an object of the invention is to provide a blower suitable for use in severe circumstances.
In order to solve the above-mentioned problem, according to a first aspect of the present invention, there is provided a blower in which a shaft is rotatably supported in a tubular casing, a cup shaped motor yoke is fixed to the shaft, and a body portion of an impeller comprising a large number of blades on an outer peripheral portion is fixed to the motor yoke, characterized in that substantially ring-like openings are provided at a portion where the blades of the body portion are mounted and on a circumference around the shaft.
According to a second aspect of the present invention, in the blower as described in the first aspect of the present invention, it is characterized in that the openings substantially form a long opening in an arc along the direction of the arrangement of the large number of blades.
In a blower structured as mentioned in the above, when the impeller is rotating, air flows through the openings provided according to the present invention.
REFERENCES:
patent: RE37261 (2001-07-01), Schmider et al.
Freay Charles G.
Minebea Co. Ltd.
Oliff & Berridg,e PLC
Rodriguez William H
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