U.S. patent application number 11/026233 was filed with the patent office on 2005-07-28 for local exhaust ventilator with rotating swirler.
This patent application is currently assigned to POSTECH Foundation. Invention is credited to Lee, Jin Won, Lee, Sang Min.
Application Number | 20050164628 11/026233 |
Document ID | / |
Family ID | 34793209 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050164628 |
Kind Code |
A1 |
Lee, Sang Min ; et
al. |
July 28, 2005 |
Local exhaust ventilator with rotating swirler
Abstract
The present invention relates to a local exhaust ventilator
which has a rotating swirler to make a swirl flow for increasing
exhaust efficiency by expanding an exhaust region. Disclosed is a
local exhaust ventilator with a simplified structure, wherein noise
due to interference of turbulence is reduced and exhaust gas is
removed at a wide area. The local exhaust ventilator includes a
disk-shaped swirler rotatably mounted at an exhaust tube, a wing
installed at the swirler perpendicular thereto to form a swirl
flow, and a driving unit installed at the exhaust tube to rotate
the swirler.
Inventors: |
Lee, Sang Min; (Busan-city,
KR) ; Lee, Jin Won; (Kyungsangbuk-do, KR) |
Correspondence
Address: |
KENNEDY COVINGTON LOBDELL & HICKMAN, LLP
214 N. TRYON STREET
HEARST TOWER, 47TH FLOOR
CHARLOTTE
NC
28202
US
|
Assignee: |
POSTECH Foundation
Kyungsangbuk-do
KR
|
Family ID: |
34793209 |
Appl. No.: |
11/026233 |
Filed: |
December 30, 2004 |
Current U.S.
Class: |
454/341 |
Current CPC
Class: |
F24F 7/025 20130101;
F04D 29/281 20130101; F24F 2221/46 20130101; F24F 2007/001
20130101; F04D 25/166 20130101 |
Class at
Publication: |
454/341 |
International
Class: |
F24F 007/007 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 31, 2003 |
KR |
10-2003-0101883 |
Claims
What is claimed is:
1. A local exhaust ventilator comprising: a disk-shaped swirler
rotatably mounted at an exhaust tube; a wing installed at the
swirler perpendicular thereto to form a swirl flow; and a driving
unit installed at the exhaust tube to rotate the swirler.
2. The local exhaust ventilator of claim 1, wherein the wing has a
linear structure.
3. The local exhaust ventilator of claim 1, wherein the wing has a
curved structure bent toward the central axis of the swirler.
4. The local exhaust ventilator of claim 1, wherein the angle
between the rotation axis of the swirler and an inclined side of
the swirler is in the range from 60.degree. to 120.degree..
5. The local exhaust ventilator of claim 4, wherein the wing is
spaced apart from the exhaust tube by a predetermined distance, and
is elongated outwardly such that the length of the wing is
enlarged.
6. The local exhaust ventilator of claim 1, wherein the driving
unit has a structure where the swirler is rotatably fitted to the
outer circumference of the exhaust tube via a bearing with a
circular rack mounted along the top thereof, and a pinion gear is
installed at the rotation shaft of a driving motor provided
external to the exhaust tube while being coupled to the rack.
7. A local exhaust ventilator comprising: a swirler comprising an
annular plate which is placed near an inlet of an exhaust pipe and
which rotates about an axis of the exhaust pipe, and a plurality of
blades which are placed along an outer rim of the annular plate,
each blade being fixed in the radial direction on the annular plate
while protruding toward the exhaust pipe; a driving unit installed
within the exhaust pipe and having a shaft of the swirler attached
thereto for rotating the swirler.
8. The local exhaust ventilator of claim 7, further comprising a
swirler cover comprising a ring-shaped top cover which covers a top
of the blades and provides a first gap between an outer surface of
the exhaust pipe and an inner rim of the top cover, and a
ring-shaped bottom cover which covers a bottom of the blades and is
positioned apart from the top cover by a second gap.
9. The local exhaust ventilator of claim 8, wherein the swirler
cover forms a gap space between the top cover and the bottom cover
such that the gap space decreases in height as the distance from
the rotational axis of the swirler increases in a radial
direction.
10. The local exhaust ventilator of claim 8, wherein the top cover
has a hole with a diameter larger than the outer diameter of the
exhaust pipe, and the bottom cover has a hole with a diameter close
to the inner diameter of the exhaust pipe.
11. The local exhaust ventilator of claim 8, wherein each blade is
in a streamlined shape of which the height decreases as a distance
from the rotational axis of the swirler is increased in a radial
direction.
12. The local exhaust ventilator of claim 11, wherein the top cover
of the swirler cover is formed in a shape contoured to the shape of
the blade of the swirler.
13. The local exhaust ventilator of claim 8, wherein the outer
portion of the blade extends in a radial direction beyond the outer
rim of the annular plate.
14. The local exhaust ventilator of claim 8, wherein each blade of
the swirler is straight in a radial direction.
15. The local exhaust ventilator of claim 8, wherein each blade of
the swirler is curved toward the perimeter of the annular
plate.
16. The local exhaust ventilator of claim 8, wherein each blade of
the swirler is fixed perpendicular to the surface of the annular
plate.
17. The local exhaust ventilator of claim 8, wherein the driving
unit comprises a driving motor which is mounted inside the exhaust
pipe by brackets, and a driving rod of the driving motor which is
fixed at the center of rotation of the swirler and which rotates
the swirler.
Description
BACKGROUND OF THE INVENTION
[0001] (a) Field of the Invention
[0002] The present invention relates to an exhaust ventilator, and,
in particular, to a local exhaust ventilator which has a rotating
swirler to produce a swirl flow for increasing exhaust efficiency
by expanding an exhaust region.
[0003] (b) Description of the Related Art
[0004] Generally local exhaust ventilators are utilized in homes,
restaurants, and factories that generate pollutants, and, in
particular, they can be used where local pollutants are produced
far from a main ventilator, where the ventilator is not easily
installed near the source of the pollutants, and where the
pollutants are produced momentarily.
[0005] However, conventional local exhaust ventilators for these
purposes have some shortcomings, as follows. The capture speed
necessary for the removal of the pollutants decreases rapidly along
the axial direction so that the conventional local exhaust
ventilators are not effective to eliminate pollutants occurring far
from the exhaust pipe, and, therefore, the exhaust pipe needs to be
installed as near to the source of the pollutants as possible. The
near-installed exhaust pipe, however, can be an obstacle to a
working line, and is inefficient for pollutant removal due to
workers moving around near the exhaust pipe.
[0006] In order to overcome these shortcomings of the conventional
local exhaust ventilators, swirl flow has been introduced to an
exhaust ventilator, which blows a similar amount of air to that of
the exhausted air into the surrounding space. The blown air
produces a swirl flow that increases the exhaust efficiency by
using the concentrated swirl flow in the intake process of the
exhaust ventilator.
[0007] Such an exhaust ventilator, however, makes noises resulting
from the turbulence generated by the interference between the flow
being drawn and the flow being blown in the narrow area under the
exhaust pipe, and raises the possibility of spreading the
pollutants farther in the space by the blown flow. Also, additional
facilities, such as a flow pipe, a filter, and a blower, are
required to generate the swirl flow.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, a local exhaust
ventilator is provided that reduces noise due to turbulence-induced
interference and removes exhaust gas over a larger area.
[0009] Further in accordance with the present invention, a local
exhaust ventilator is provided that involves a simplified
structure, an economic production cost, and easy installation,
maintenance, and repair.
[0010] The present invention discloses a local exhaust ventilator
comprising a disk-shaped swirler rotatably mounted at an exhaust
tube, a wing installed at the swirler perpendicular thereto to form
a swirl flow, and a driving unit installed at the exhaust tube to
rotate the swirler.
[0011] The wing may have a linear structure or a curved structure
bent toward the central axis of the swirler.
[0012] The angle between the rotation axis of the swirler and an
inclined side of the swirler may be in the range from 60.degree. to
120.degree.. The wing may be spaced apart from the exhaust tube a
predetermined distance, and be elongated outwardly such that the
length of the wing is enlarged.
[0013] The driving unit may have a structure where the swirler is
rotatably fitted to the outer circumference of the exhaust tube via
a bearing with a circular rack mounted along the top thereof, and a
pinion gear may be installed at the rotation shaft of a driving
motor provided external to the exhaust tube while being coupled to
the rack.
[0014] In accordance with one form of the present invention, a
local exhaust ventilator is provided that increases exhaust
efficiency by radial swirl flow entraining air from above an
exhaust pipe. A swirler, which is an annular plate with blades, is
installed in an exhaust pipe and rotates inside a swirler cover
having a peripheral gap along the outer surface of the exhaust pipe
and another peripheral gap along the outer rim of the swirler
cover.
[0015] Further in accordance with one form of the present
invention, a local exhaust ventilator is provided in which a
protective cover for the rotating swirler secures the safety of
workers moving around under the system. In another exemplary
embodiment of the present invention, a local exhaust ventilator
includes a swirler, a swirler cover, and a driving unit.
[0016] The swirler may include an annular plate positioned near an
inlet of an exhaust pipe and which rotates about the axis of the
exhaust pipe, and a plurality of blades which are placed along an
outer rim of the annular plate, each blade being fixed in the
radial direction on the annular plate while protruding toward the
exhaust pipe.
[0017] The swirler cover may include a ring-shaped top cover which
covers a top of the blades and provides a first gap between an
outer surface of the exhaust pipe and inner rim of the top cover,
and a ring-shaped bottom cover which covers a bottom of the blades
and is positioned apart from the top cover by a second gap.
[0018] The driving unit may be installed within the exhaust pipe
and rotates the swirler by way of a swirler shaft attached
thereto.
[0019] The gap space between the top cover and the bottom cover of
the swirler cover may decrease in height as the distance from the
rotational axis of the swirler increases in a radial direction.
[0020] Also, with a swirler cover, the top cover has a hole larger
than the outer diameter of the exhaust pipe, and the bottom cover
has a hole with a diameter close to the inner diameter of the
exhaust pipe.
[0021] Each blade may be formed in a streamlined shape with the
height of each swirler blade decreasing as the distance from the
rotational axis of the swirler increases in a radial direction, and
the top cover of the swirler cover may be formed in a shape
contoured to the shape of the swirler blade.
[0022] The outer portion of the swirler blade can extend in a
radial direction beyond the outer rim of the annular plate. Each
swirler blade may be straight in a radial direction or curved
toward the perimeter of the annular plate. Each blade of the
swirler can be fixed perpendicular to the surface of the annular
plate.
[0023] The driving unit may include a driving motor mounted inside
the exhaust pipe by brackets, and a driving rod of the driving
motor fixed at the center of rotation of the swirler and which
rotates the swirler.
[0024] According to one form of the local exhaust ventilator of the
present invention, the swirler is operated with the instant
generation of a local contamination source, thereby enhancing the
energy efficiency. Furthermore, a tornado-like flow is induced due
to the interaction thereof with the ground surface, thereby
removing the contamination source generated at the ground in an
effective manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above and other advantages of the present invention will
become more apparent by describing embodiments thereof in detail
with reference to the accompanying drawings, in which:
[0026] FIG. 1 is a schematic longitudinal sectional view of a local
exhaust ventilation system according to an embodiment of the
present invention;
[0027] FIG. 2 is a schematic longitudinal sectional view of a local
exhaust ventilation system according to another embodiment of the
present invention;
[0028] FIG. 3 illustrates a swirler installed at the local exhaust
ventilator according to an embodiment of the present invention;
[0029] FIG. 4 illustrates a variant of the swirler shown in FIG.
3;
[0030] FIG. 5 is a perspective external view of a swirler with a
protection unit;
[0031] FIGS. 6A and 6B illustrate the operational state of the
local exhaust ventilator according to an embodiment of the present
invention, depending upon the rotation speed of the swirler;
[0032] FIGS. 7A and 7B illustrate the operational state of the
local exhaust ventilator according to an embodiment of the present
invention, depending upon the angle of the swirler;
[0033] FIG. 8 is a longitudinal sectional view of a local exhaust
ventilator according to an exemplary embodiment of the present
invention;
[0034] FIG. 9 is a transverse sectional view of a local exhaust
ventilator according to an exemplary embodiment of the present
invention; and
[0035] FIG. 10 is a transverse sectional view of a local exhaust
ventilator according to another exemplary embodiment of the present
invention.
DETAILED DESCRIPTION
[0036] The present invention will be described more fully
hereinafter with reference to the accompanying drawings, in which
various embodiments of the invention are shown.
[0037] As shown in FIG. 1, the local exhaust ventilator includes a
swirler 10 installed at an exhaust tube 50 to form a swirl flow,
and a driving unit for rotating the swirler 10.
[0038] Swirlers are largely classified into an inner drive type and
an outer drive type. With the inner drive type shown in FIG. 1, the
driving unit is formed with a driving motor 20 fixed to the inner
circumference of the exhaust tube 50 via a bracket 21. The swirler
10 rotates around the rotation shaft of the driving motor 20
extended external to the exhaust tube 50 while being fixed
thereto.
[0039] Furthermore, with the outer drive type shown in FIG. 2, the
swirler 10 is installed at the outer circumference of the exhaust
tube 50 via a bearing 30 such that it can be rotated. A circular
rack 31 is mounted on the top of the swirler 10. A driving motor 32
is installed external to the exhaust tube 50, and a pinion gear 33
is provided at the rotation shaft of the driving motor 32 and
coupled to the rack 31.
[0040] With the above structure, the driving power of the driving
motor 32 is transmitted to the swirler 10 via the rack 31 and the
pinion gear 33 to thereby rotate the swirler 10.
[0041] The outer drive type is more preferable than the inner drive
type in that the swirler, the bearing, and the motor can be
modulated in a simplified manner while being attached to the common
exhaust tube 50, and motor failure due to the contamination source
can be minimized.
[0042] The driving unit is not limited to the above structure, but
may bear any other structure provided that the swirler 10 can
rotate around the central axis of the exhaust tube 50.
[0043] The swirler 10 rotates around the exhaust tube 50 to
generate a swirl flow. The swirler 10 is formed with a disk body
and a wing 11 vertically installed at the bottom of the disk
body.
[0044] The wing 11 substantially generates the swirl flow when the
swirler 10 is rotated. The swirl flow characteristic is varied
depending upon the installation direction or location of the wing
11 with respect to the swirler 10. The wing 10 may be installed
distant from the central axis of the swirler 10, or close thereto
with a linear or curved structure.
[0045] FIG. 3 illustrates the curved structure of the wing 11 bent
toward the central axis of the swirler 10, and FIG. 4 illustrates
the linear structure thereof.
[0046] Furthermore, the driving speed (the rotation speed) of the
swirler 10 influences the air flow around the exhaust tube 50. It
is preferable to rotate the swirler 10 at 1300.about.1700 rpm.
[0047] A protection cover may be installed external to the swirler
to protect the facility, and prevent possible safety failures due
to the high speed rotation of the swirler.
[0048] As shown in FIG. 5, the cover has a disk-shaped top cover 60
installed at the exhaust tube 50 while being extended to the
backside of the swirler 10, a donut-shaped bottom cover 61 placed
forward of the wing 11 of the swirler 10, and supports 62
vertically installed at the frontal end of the top cover 60 while
being spaced apart from each other by a predetermined distance to
support the bottom cover 61.
[0049] The swirler 10 and the wing 11 are protected by the top
cover 60 and the bottom cover 61, and the lateral side of the wing
11 disposed between the bottom cover and the top cover opens to
blow the air for forming the swirl flow.
[0050] The operation principle of the local exhaust ventilator
according to the present invention will be now explained.
[0051] When the swirler 10 is rotated with the exhaust operation
shown in FIG. 6A, the air flow made below the swirler 10 is
simultaneously influenced by the centrifugal force and the
centripetal force due to the exhaust operation so that it is not
moved in the radial direction, but is rotated by the rotation speed
of the swirler 10. In this case, the flow not moved in the radial
direction is like an imaginary flux wall (air curtain).
[0052] The local exhaust ventilator is operated while constantly
maintaining the amount of exhaust gas so that it takes in the air
below the air curtain rather than the air external to the air
curtain. The air expelled to the outside by the swirler 10 is
introduced to the location of the intake air, and is directed
toward the exhaust tube 50. Based on such an operation principle,
as shown in FIG. 6A, a secondary swirl flow 40 is formed below the
swirler 10 while being rotated in the direction perpendicular to
the rotation direction of the swirler 10. Of course, the secondary
swirl flow is a part of the primary swirl flow (air curtain)
rotated around the axis of the exhaust tube 50.
[0053] The secondary swirl flow 40 continually receives the
required energy by the swirler 10, and rotates at a predetermined
speed so that it has a role of intruding the air below the
secondary swirl flow 40 into the exhaust tube 50. In this way, the
influential area of the exhaust flow is amplified downwards while
enlarging the ventilating area.
[0054] The formation location of the secondary swirl flow 40 is
varied depending upon the rotation speed of the swirler 10. As
shown in FIG. 6B, when the rotation speed of the swirler increases,
the effect of the centrifugal force increases so that the secondary
swirl flow 40 is generated at the area more distant from the
swirler.
[0055] With the lower rotation speed of the swirler 10, the
secondary swirl flow 40 is formed below the swirler so that a
complicated and strong turbulence is formed below the swirler with
increased noise. Furthermore, as the contaminants are diffused
within the turbulence, the contamination source in the exhaust flow
is liable to be diffused. By contrast, when the secondary swirl
flow 40 is formed distant from the swirler, the noise is diminished
due to the clear isolation of the secondary swirl flow 40 from the
exhaust flow, and the diffusion possibility of the contamination
source due to the swirler is removed. Furthermore, a wide
ventilating area is formed due to the secondary swirl flow 40
spread external to the swirler.
[0056] The flow characteristic is influenced by the shape of the
swirler, that is, the size and axial angle thereof. As the radius
of the swirler is increased, the swirl flow becomes stronger, and
the exhaust depth becomes enlarged at the same rotation speed. As
shown in FIG. 6A, the swirler 10 commonly proceeds perpendicular to
the axis thereof.
[0057] As shown in FIG. 7A, when the angle .theta. between the
rotation axis and the inclined side of the swirler 10 is in the
range from 60.degree. to 90.degree., the secondary swirl flow 40
can be brought downwards close to the ground. As shown in FIG. 7B,
the angle .theta. between the rotation axis and the inclined side
of the swirler 10 is in the range from 90.degree. to 120.degree.,
the exhaust depth is decreased compared to the case where the
inclined side is angled at 90.degree., but the secondary swirl flow
40 is stabilized so that the noise is reduced and the exhaust flow
is also formed in a stable manner.
[0058] It is also preferable to shape the wing 11 attached to the
swirler 10 correctly. With the rotation of the swirler 10, the flow
around the swirler is rotated due to the Wing 11 attached to the
swirler. Therefore, with a larger sectional area of the wing, the
amount of flow to be rotated is increased. As the rotation speed of
the swirler is higher with the larger radius, the outer length of
the wing should be elongated. Furthermore, in order to prevent the
contamination source from being diffused due to the swirler, the
wing should be attached to the swirler while being spaced apart
from the exhaust tube 50 by a predetermined distance. In order to
extrude a larger amount of flow to the outside, it may be
considered to make a linear wing as well as a curved wing.
[0059] FIG. 8 is a longitudinal sectional view of a local exhaust
ventilator according to an exemplary embodiment of the present
invention, and FIG. 9 is a transverse sectional view of a local
exhaust ventilator according to an exemplary embodiment of the
present invention.
[0060] According to the embodiment, a local exhaust ventilator 60
includes a swirler 70 which is installed in the vicinity of an
inlet of the exhaust pipe 62 and produces a swirl flow while
rotating, a swirler cover 80 which covers the top and the bottom of
the blades 77 of the swirler 70, and a driving unit 90 which is
mounted within the exhaust pipe 62 and rotates the swirler 70.
[0061] The swirler 70 includes an annular plate 73 which is placed
near the end of the exhaust pipe 62 and rotates about the axis of
the exhaust pipe 62, and a plurality of blades 77 which are placed
along the outer rim of the annular plate 73 and are attached
vertically in a radial direction on the annular plate 73. Each
blade 77 protrudes toward the exhaust pipe 62.
[0062] The annular plate 73 has a hole of at least the same size as
the inner diameter of the exhaust pipe 62, and the outer diameter
of the annular plate 73 is larger than that of the exhaust pipe 62.
The annular plate 73 has a plurality of spokes 75 connecting the
center of rotation 71 of the swirler 70 to the inner rim of the
annular plate 73. Because the spokes 75 are positioned at the inlet
of the exhaust pipe 62, about three spokes, as seen in FIG. 8 and
FIG. 9, are preferable, in order not to block the incoming flow
through the inlet of the exhaust pipe 62.
[0063] The blades 77 placed around the outer rim of the annular
plate 73 are preferably fixed vertically on the top surface of the
annular plate 73, with the outer portion of the blades extending in
the radial direction beyond the outer rim of the annular plate 73.
Each blade 77, as seen in FIG. 8, has a streamlined shape of which
the height decreases with an increase in the distance from the
rotational axis. Because the blade 77 serves as a working part of
the swirler 70 for producing the swirl flow, the blade 77 with the
streamlined shape can draw a large quantity of air from above the
inlet of the exhaust pipe 62 and then exhaust it in a radially
outward direction.
[0064] Also, each blade 77 is straight in the radial direction as
seen in FIG. 9.
[0065] The swirler cover 80 includes a top cover 82 covering the
top of the blade 77, and a bottom cover 86 covering the bottom of
the blade 77.
[0066] The top cover 82 is in a ring shape which has a hole larger
than the outer diameter of the exhaust pipe 62, and is positioned
to form a first gap I between the outer surface of the exhaust pipe
62 and the inner rim of the top cover 82. And, the bottom cover 86
is in a ring shape which has a hole with a diameter similar to the
inner diameter of the exhaust pipe 62, and is positioned apart from
the top cover 82 to form a second gap II between the outer rims of
both the bottom cover 86 and the top cover 82.
[0067] In particular, the top cover 82 is in a rounded shape
contoured to the shape of the blades 77 such that the height of the
top cover 82 increases as the distance from a center of rotation 71
of the swirler 70 decreases, and the height of the top cover 82
decreases as the distance from the center of rotation 71 of the
swirler 70 increases. The bottom cover 86 is formed in a flat
shape, and therefore the gap space between the top cover 82 and the
bottom cover 86 decreases as the distance from the rotational axis
of the swirler decreases in the radial direction. Due to this
particular shape, the swirler cover 80 makes the air drawn by the
swirler 70 accelerate through the radially contracted space and
produces the strong swirl flow when the air is expelled to the
outside.
[0068] The swirler cover 80 also protects the blade 77 by covering
both the top and bottom of the blade 77.
[0069] The top cover 82 is mounted on the outside of the exhaust
pipe 62 by a plurality of supporting rods 58. In order to not block
the air flow through the first gap I between the outer surface of
the exhaust pipe 62 and the top cover 82, the supporting rods 58
are preferably positioned equidistant to each other, and four or
six supporting rods may be used.
[0070] A plurality of guide blades 84 connect the top cover 82 to
the bottom cover 86 at the outer portions of both the top cover 82
and bottom cover 86. The guide blade 84 positioned in the radial
direction along the perimeter is attached vertically to both the
top cover 82 and the bottom cover 86. It is preferable for the
guide blades 84 to be uniformly placed equidistantly. Each of the
guide blades 84 may be placed at a position corresponding to each
blade 77, and the number of guide blades 84 may be the same as the
number of the blades 77. However, there is no restriction in the
number and the position of the guide blades 84 with respect to the
blades 77. Therefore, each of the guide blades 84 seen in FIG. 9 is
straight in the radial direction in the illustrated embodiment.
[0071] The swirler 70 is rotated by a driving unit, as illustrated
in FIG. 8, including a driving motor 93 which is mounted inside the
exhaust pipe 62 by brackets 91, and a driving rod 95 of the driving
motor 93 that extends to the end of the exhaust pipe 62 and is
fixed at the center of rotation 71 of the swirler 70. However, the
driving unit 90 of the present invention does not necessarily have
this configuration only, and it can have any configuration such
that it can rotate the swirler about the axis of the exhaust
pipe.
[0072] On the other hand, the swirler 70, the swirler cover 80 and
the driving unit 90, as described above, can be assembled in a
single module which can be attached to an existing exhaust pipe
directly and used immediately.
[0073] As seen in FIG. 10, the local exhaust ventilator of the
illustrated embodiment is the same as that of the previous
embodiment except for the shapes of the blades 102 attached
vertically to the annular plate 73 and of the guide blades 104
connecting the top cover 82 to the bottom cover 86 around the outer
rims thereof and forming a gap between them.
[0074] The blades 102 of the swirler in the illustrated embodiment
are curved toward the perimeter of the annular plate 73, and the
guide blades 104 are also curved toward the perimeter of the bottom
cover 86. It is preferable that the curvature of the blades 102 is
opposite to that of the guide blades 104. The opposite curvature
plays a role in helping the air accelerated by the swirler 70 to
have a strong swirl flow.
[0075] Following is the working principle of the local exhaust
ventilator of the present invention.
[0076] Under the proper working state, as illustrated in FIG. 8,
the flow a above the inlet of the exhaust pipe 62 is pulled by the
rotating swirler 70 through the first gap I to the inside of the
swirler cover 80, and is pushed radially by the swirler blade 77 to
the outside through the second gap II while forming the swirl flow
b. At this time, the air is accelerated and expelled by the swirler
cover 80 and the guide blade 84 while maintaining the swirl
component. The flow below the inlet of the exhaust pipe 62 is
divided into two kinds of flow by the accelerated outgoing swirl
flow: one flow c is pushed radially outward; and the other flow d
is entrained by the exhaust ventilator 60 toward the axis of the
exhaust pipe 62. Because the flow rate of the exhaust ventilator 60
is kept constant under the working state, the exhaust ventilator 60
exhausts an additional volume of air which is the same amount as
the air pushed in the radial direction. Therefore, the interaction
between these two kinds of flow expands the exhaust region in the
axial direction.
[0077] The radially pushed swirl flow c and d moves toward the axis
of the exhaust pipe 62 because of the exhausting process, and forms
the secondary swirl flow e under the swirler 70. The secondary flow
e keeps rotating at a constant speed with the energy supplied by
the swirler 70, and plays a role in pushing the air under the
secondary swirl flow into the exhaust pipe 62. By this principle,
the air is accelerated toward the inlet of the exhaust pipe 62 so
that the exhaust region expands.
[0078] Also, as the swirl flow that is widely spread in the radial
direction is entrained toward the axis of the exhaust pipe 62 by
the exhausting process, the rotation of the swirl flow becomes more
vigorous by the conservation of the angular momentum. This causes a
low pressure distribution under the exhaust pipe 62 which strongly
boosts the exhaust flow.
[0079] As explained above, the local exhaust ventilator using the
swirler of the present invention can enhance the performance of
exhaust ventilation by making a radial swirl flow which is produced
by a swirler, a swirler cover, and air entrained from above the
inlet of an exhaust pipe. Also, it can prevent pollutants from
being rebroadcast and can make it possible for the efficient
removal of the pollutant occurring in a local area.
[0080] Since the swirler, the swirler cover, and the driving unit
can be assembled in a single module which can be simply attached to
an existing exhaust pipe, there is no need for further investment
in the facility.
[0081] In addition, the safety of workers near the local exhaust
ventilator can be secured by the swirler cover which surrounds the
swirler blades that rotate at a high speed.
[0082] Although various embodiments of the present invention have
been described in detail hereinabove, it should be dearly
understood that many variations and/or modifications of the basic
inventive concepts herein taught which may appear to those skilled
in the art will still fall within the spirit and scope of the
present invention, as defined in the appended claims.
* * * * *