Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Casing having tangential inlet or outlet
Reexamination Certificate
1999-05-14
2001-03-13
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Casing having tangential inlet or outlet
C415S206000, C415S212100
Reexamination Certificate
active
06200093
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dual-intake fan which is a so-called sirocco fan used for venting air, and more particularly, to a fan having a structure in which a portion of an exhaust outlet is formed to be inclined while the centers of a scroll housing and an impeller are disposed to be eccentric so that noise can be reduced while air flow can be effectively guided by the scroll housing to the maximum extent and the air flow rate can be increased.
2. Description of the Related Art
In general, a fan, as a device which generates air flow, is widely used in various equipments and facilities. In particular, in a microwave oven provided with a fume hood, which is used in a domestic kitchen, a fan is installed at an upper portion of the microwave oven so as to vent odors and smoke generated in a gas range installed below the microwave oven. That is, as shown in
FIGS. 1 and 2
, after the odors and smoke generated in the gas range are drawn into the lower part of the microwave oven, the odor and smoke are taken into a fan
10
along air flow passages, and then are vented to the outside through an exhaust outlet
10
a
of the fan
10
. Here, the exhaust outlet
10
a
of the fan
10
may be installed as shown
FIG. 2
, or may be configured so that the exhaust outlet
10
a
is installed to face upward and the odors and smoke can be vented to the outside by connecting a duct to the exhaust outlet
10
a
. As a matter of course, in the microwave provided with the fume hood, a magnetron
2
for generating an electromagnetic wave so as to cook food supplied into a cooking chamber
1
a
, and a fan
3
for cooling the magnetron
2
. Reference numerals
1
,
4
, and
11
indicate a case, a door and a motor, respectively.
FIG. 3
shows a front view of a conventional fan,
FIG. 4
shows a left side view of the fan shown in
FIG. 3
,
FIG. 5
shows a left side view of the fan shown in
FIG. 3
illustrating a flow velocity distribution measured by a laser Doppler velocimeter (LDV) at the exhaust outlets of the fan, and
FIG. 6
shows a front view of the fan shown in
FIG. 3
, in which a flow velocity distribution at an air inlet of the fan is expressed by velocity vectors.
As shown in
FIGS. 3 and 4
, a conventional fan
20
comprises impellers
21
for rotating so as to create air flow, scroll housings
22
for guiding the flow of air drawn by the impeller
21
, bell mouths installed around air inlets
22
a
formed at the scroll housings
22
for guiding intake air flow.
Here, the impeller
21
comprises a plurality of blades
21
a
for rotating so as to create air flow, rims
21
b
installed at both ends of the blades
21
a
for supporting the blades, and a separating member
21
c
connected to a motor
30
as a driving means while connected to center portions of the blades.
In addition, the air inlets
22
a
are formed at the motor side and the flow passage side of the scroll housing
22
, and an exhaust outlet
22
b
for venting the air drawn into the scroll housing
22
through the air inlets
22
is formed at the scroll housing
22
. Here, the reference location or boundary location of the exhaust outlet
22
b
is called a cutoff C′.
In the above structure, when the motor
30
is supplied with electric power and the impeller
21
rotates, air is drawn in through the air inlet
22
b
by the pressure due to the rotation of the impeller
21
. After the drawn air is moved to the exhaust outlet
22
b
in accordance with the guidance of the scroll housing
22
having a gradually expanding passage from the cutoff C′, the air is vented to the outside. That is, the entering air to which the dynamic energy is imparted by the blades
21
a
, the air is vented to the outside through the exhaust outlet
22
b
while recovering static energy from the dynamic energy.
Reference numerals S′ and I′ indicate the center of the air inlet
22
a
of the scroll housing
22
a
and the rotation center of the impeller
21
, respectively.
However, in the conventional fan
20
, since the exhaust outlet
22
b
of the scroll housing
22
has a rectangular shape parallel to the rotating shaft of the impeller
21
, it was found that relatively large flow loss occurs at the edge portions, i.e., the peripheral portions of the exhaust outlet
22
b
as shown in
FIG. 5
, as a result of an experiment of measuring a flow velocity distribution at the exhaust outlet
22
b
with the laser Doppler velocimeter. In other words, the air flow having a recovered pressure, i.e., raised static energy while flowing along the scroll housing
22
forms a wide flow loss area due to the growth of boundary layers at the edge portions of the exhaust outlet
22
b
. Accordingly, there are problems in which while such flow loss at the exhaust outlet reduces the air flow rate, the lost energy is converted into noise and increases noise.
In addition, since the conventional fan
20
is designed so that the center I′ of the impeller is simply coincident with the center S′ without considering the flow velocity distribution at the air inlet
22
a
, as shown in
FIG. 6
when examining the flow velocity distribution at the air inlet
22
a
of the fan, there is a problem in which a flow loss area L is formed in an area where the rotation angle &thgr;′ is in the range from −90° to 90° when examined in terms of the rotation angle &thgr;′.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a fan capable of increasing the air flow rate and simultaneously reducing noise by disposing the center of an impeller to be eccentric with respect to the center of a scroll housing and forming the lower portion of an exhaust outlet of the scroll housing to be inclined so that the formation of a flow loss area can be prevented.
Accordingly, to achieve the above objective, there is provided a fan including an impeller on which a plurality of blades are installed for rotating so as to create air flow, and a scroll housing formed so that the air drawn in through an air inlet by the impeller can be guided along a gradually expanding passage of the scroll housing, and the lower portion of an exhaust outlet is composed of at least one incline formed to be inclined upward toward any one side.
In addition, there is provided a fan including an impeller on which a plurality of blades are installed for rotating so as to create air flow, and a scroll housing formed so that the air drawn in through an air inlet by the impeller can be guided along a gradually expanding passage of the scroll housing, and the rotation center of the impeller and the center of the air inlet can be disposed to be eccentric.
REFERENCES:
patent: 5813834 (1998-09-01), Hopfensperger et al.
patent: 5839879 (1998-11-01), Kameoka et al.
Lee Joon Sei
Park Sung Il
LG Electronics Inc.
Look Edward K.
Rodriguez Hermes
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