Fluid reaction surfaces (i.e. – impellers) – Perimetric blading extending axially between annular members
Reexamination Certificate
2000-07-03
2002-02-12
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Perimetric blading extending axially between annular members
C416S184000, C416S187000, C416S20000R, C416S203000, C415S119000
Reexamination Certificate
active
06345956
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an impeller of a blower, and more particularly, to an air-guiding impeller of a centrifugal blower having air-guiding ribs with a geometrical configuration for modulating the distribution of airflow.
2. Description of the Related Art
A centrifugal blower has a generally cylindrical impeller which is driven by a motor and the like disposed at the center thereof and which rotates in one direction so as to pull air in along its central axis as it rotates, and then forces the air radially outwardly, turning the air ninety degrees in effect. According to their air-intake path, the centrifugal blowers can further be divided into two categories: the single-suction blowers and the dual-suction blowers. A single-suction blower pulls air from only one side of the blower, while the dual-suction blower draws air in from both sides of the blower. Such centrifugal blowers are widely used in computers, copiers, printers, etc., to circulate the internal air for cooling.
A conventional centrifugal blower makes a lot of noise while performing the air circulation. For instance, a runner of a sirocco type fan has been disclosed in the Japanese Patent No. 126510 (hereinafter referred to as '510 reference), as shown in
FIGS. 1A and 1B
. A main plate
2
made of a thick iron plate, which is fixed to a boss
3
of a rotary shaft
1
of the driving motor of the blower, transmits a rotary torque to the impeller comprising a plurality of blades
4
. Each blade
4
is fixed at one end to one side of the main plate
2
at the outer periphery of the plate
2
, and fixed at the other end to a side plate
5
. The main plate
2
has several holes
6
to reduce the difference in the rigidity (or the distortion) of plates
2
and
5
, and, in turn, reduce the stress produced in each blade
4
. Since two ends of each blade
4
are fixed to plates
2
and
5
respectively, so the blade
4
can be placed in a severe environment, for example, the blades can sustain a high temperature blast. This is the primary object of '510 reference. A thin sheet
7
is further fastened onto the other side of the main plate
2
so as to seal the holes
6
for blocking the air passage.
FIG. 1C
is a diagram showing the airflow path, illustrated by dotted lines, of a blower using the prior impeller structure shown in FIG.
1
A. As the length of the blade
4
increases, the strength of the whole impeller decreases. So, it makes the fabricating processes more difficult. Moreover, in most cases, the intake air leaves the impeller before it can reach the lower end of blades
4
, resulting in an empty area D in the airflow path and thus deteriorating the performance of impeller.
The '510 reference also shows a second prior art shown in
FIGS. 2A and 2B
, wherein the rotary torque is transmitted to the impeller through a main plate
2
as in the above-described prior art. The main plate
2
is a thicker iron plate without any hole on it. An annular side plate
5
made of a thin iron plate is connected to the boss
3
of the rotary shaft
1
through several radial ribs
9
so as to reduce rigidity difference between plates
2
and
5
, and stress produced in each blade
4
. Each radial rib
9
is of a plane shape and is provided merely for connecting the plate
5
to the boss
3
and is integrally formed on the same plane with respect to the plate
5
. However, the plane-shaped rib
9
is likely to disturb the inlet airflow of the blower, and thus deteriorate the fluid kinetics of the impeller.
Another embodiment of the '510 reference is shown in FIG.
3
. This embodiment is similar to the above-described embodiments except that two intermediate annular plates
12
and
13
are interposed between the main plate
2
and the side plate
5
. Each of the intermediate annular plate
12
and
13
is provided with several holes, each of which fastens one of the blades
4
and prevents an intermediate portion of each blade
4
from becoming distorted. Each of the intermediate annular plate
12
and
13
is connected to the boss
3
of the rotary shaft
1
through several radial ribs
14
. The radial ribs
14
are provided purely for connecting the intermediate annular plate
12
and
13
as described in the Japanese specification and are integrally formed on the same plane with respect to the intermediate annular plate
12
and
13
.
Shown in
FIG. 4
is another conventional impeller structure
31
, which comprises a main plate
32
and a plurality of blades
34
integrally formed with the main plate
32
and evenly disposed along outer periphery on both sides of the main plate
32
. Each upper blade
34
located on the top surface of main plate
32
aligns with a lower blade
34
in vertical direction. Therefore, these blades
34
of impeller
31
are “aligned” , and the impeller
31
is called a “collateral impeller” . Rotary torque from the rotary shaft
33
of the motor is transmitted to the blades
34
by the main plate
32
. With this structure, the impeller
31
can be mounted into a dual-suction blower successfully. Compared to the blades
4
of
FIG. 1A
, the length of each blade
34
of
FIG. 4
is only half of that of the blade
4
, thereby increasing the strength of every blade and making the fabrication of the impeller easier.
Another impeller
41
is provided to reduce the noise, as shown in FIG.
5
. It is known that the noise generated by a blower relates to the rotation speed and the dimension of its impeller. As the edge of blade passes through the tongue of the blower, it hums, which causes the noise. The impeller
41
is composed of a main plate
42
, a plurality of upper blades
44
integrally formed with the main plate
42
and evenly disposed along the outer rim on the upper side of the main plate
42
, and a plurality of lower blades
44
′ disposed in a similar manner on the lower side of the main plate
42
. The upper blades
44
and the lower blades
44
′are alternately disposed. Rotary torque from the motor
43
is transmitted to the blades
44
and
44
′ by the main plate
42
. Comparing the impeller
41
with the impeller
31
shown in
FIG. 4
, the length of a blade edge passing through the tongue of the blower per unit time is reduced by half, while the frequency of the hum increases. As a result, the noise generated by the impeller
41
can be reduced effectively by carrying a lower amplitude.
FIGS. 6A-6C
are diagrams showing the airflow path of an impeller having a structure as shown in
FIGS. 4
or
5
. Referring to
FIG. 6A
, the main plate
42
has no hole for airflow. The impeller
41
works well in a dual-suction blower when the air-intake path on both sides of blower is fluent. However, when a blower is mounted closely on a surface W, as shown in
FIG. 6B
, the airflow path from the lower side of the blower is blocked. As a result, the performance of the impeller deteriorates. In addition, when the impeller
41
is mounted onto a single-suction blower, as shown in
FIG. 6C
, the main plate
42
blocks the supply of airflow from the upper side. Thus, the intake airflow can only be applied to the upper blades. Thus, the impeller
41
becomes even less inefficient when mounted onto a single-suction blower.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an impeller of a blower having air-guiding ribs with a geometrical configuration and formed on a different plane with respect to an annular frame, thereby modulating the distribution of airflow more evenly, reducing the noise generated during the operations of the blower, and increasing the air suction force and the intake airflow.
It is still an object of the invention to provide an impeller of a blower having air-guiding ribs with a geometrical configuration which is adaptable for either a dual-suction blower or a single-suction blower.
It is yet still another object of the invention to provide an impeller of a blower which can eliminate an empty area of the intake airflow formed within the impeller by providing air-guid
Bacon & Thomas PLLC
Delta Electronics , Inc.
Verdier Christopher
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