U.S. patent application number 14/250447 was filed with the patent office on 2015-10-15 for fan dampers of centrifugal fan.
The applicant listed for this patent is Yu-Pei Chen. Invention is credited to Yu-Pei Chen.
Application Number | 20150292518 14/250447 |
Document ID | / |
Family ID | 54264729 |
Filed Date | 2015-10-15 |
United States Patent
Application |
20150292518 |
Kind Code |
A1 |
Chen; Yu-Pei |
October 15, 2015 |
Fan Dampers of Centrifugal Fan
Abstract
A centrifugal fan is provided with an electric motor; an
impeller driven by the electric motor; and fan dampers around an
inner surface of fan housing and surrounding the impeller. Each fan
damper has a windward, concave surface facing a rotational
direction of the impeller. A spiral airflow created by the impeller
passes the windward curved portions of the fan dampers and the
motor toward an outlet. A portion of the kinetic energy of the
spiral airflow is transmitted axially and the remaining kinetic
energy of the spiral airflow is converted into static pressure to
convey the spiral airflow toward the outlet so as to converge the
spiral airflow from the electric motor to the outlet, thereby
causing most of the spiral airflow to flow axially when it reaches
the outlet.
Inventors: |
Chen; Yu-Pei; (Zhubei City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chen; Yu-Pei |
Zhubei City |
|
TW |
|
|
Family ID: |
54264729 |
Appl. No.: |
14/250447 |
Filed: |
April 11, 2014 |
Current U.S.
Class: |
60/786 ;
415/203 |
Current CPC
Class: |
F04D 29/444 20130101;
F04D 17/16 20130101 |
International
Class: |
F04D 29/44 20060101
F04D029/44 |
Claims
1. A centrifugal fan comprising: an inlet housing including an
axial inlet; an outlet housing including an axial outlet, the
outlet housing being secured to the outlet housing to define an
interior; an electric motor disposed in the interior; an impeller
disposed in the interior and driven by the electric motor; and a
plurality of fan dampers disposed around an inner surface of the
interior and surrounding the impeller, each of the fan dampers
having a windward, concave surface facing a rotational direction of
the impeller; wherein a spiral airflow created by the impeller
passes the windward curved portions of the fan dampers and the
motor toward the outlet, and wherein a portion of the kinetic
energy of the spiral airflow is transmitted axially and the
remaining kinetic energy of the spiral airflow is converted into
static pressure to convey the spiral airflow toward the outlet so
as to converge the spiral airflow from the electric motor to the
outlet, thereby causing most of the spiral airflow to flow axially
when it reaches the outlet.
2. The centrifugal fan of claim 1, wherein the fan dampers are
formed integrally with the inlet housing or the outlet housing.
3. The centrifugal fan of claim 1, wherein the fan dampers are
manufactured separately prior to securing to an inner surface of
the inlet housing or the outlet housing.
4. The centrifugal fan of claim 1, wherein each of the fan damper
has a windward end and a leeward end, wherein the impeller has a
disc, wherein the windward end is at angle of 0-45 degrees with
respect to the disc with the angle being increased axially, and
wherein the leeward end is at angle of 70-90 degrees with respect
to the disc.
5. A centrifugal fan comprising: a fan housing; an impeller
disposed in a forward end of the fan housing; a starter motor
disposed adjacent to the impeller in the fan housing; a combustion
chamber disposed in an intermediate portion of the fan housing; a
turbine disposed in a rear end of the fan housing; and a plurality
of fan dampers disposed proximate to an inner surface of the fan
housing and around the impeller, each of the fan dampers having a
windward, concave surface facing a rotational direction of the
impeller; wherein a spiral airflow created by the impeller passes
the windward curved portions of the fan dampers toward the
combustion chamber, wherein a portion of the kinetic energy of the
spiral airflow is transmitted axially and the remaining kinetic
energy of the spiral airflow is converted into static pressure to
convey the spiral airflow toward the combustion chamber, wherein
fuel is injected into the combustion chamber to mix with air prior
to combustion, and wherein the combusted mixture rotates the
turbine to generate mechanical energy.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to centrifugal fans and more
particularly to a centrifugal fan having improved fan dampers for
effectively directing spiral airflow to axial airflow.
[0003] 2. Description of Related Art
[0004] Typically, a mechanical fan can be classified as an axial
type fan having a high volumetric flow rate and a centrifugal type
fan (i.e., centrifugal fan) having a high static pressure.
Centrifugal fans are particularly suitable to narrow outlet or
complicated pipes. A centrifugal fan can be either a spiral air fan
having an inlet and an outlet at angle of about 90-degree with
respect to the inlet, or a linear air fan having an inlet, an
impeller, and an outlet arranged in a straight line.
[0005] A typical centrifugal fan is shown in FIG. 1. Within an
inlet housing 12, a hub of an impeller 13 is driven by a motor
shaft of an electric motor 14. Thus, air is sucked into the inlet
housing 12 via an inlet 10 and in turn the air is converted into a
spiral air flow by the fan blades of the impeller 13. The spiral
air flow presses against a diverging section 11 of an inner surface
of the inlet housing 12 for diffusing so as to convert a portion of
kinetic energy into static pressure. The static pressure further
conveys the air flow forward to press against a convergent section
15 of an inner surface of an outlet housing 17. Finally, a great
volume of pressurized air is outputted through an inlet 16.
[0006] However, only a portion of the kinetic energy is converted
into static pressure by the diverging section 11 of the inner
surface of the inlet housing 12. That is, a substantial portion of
airflow is not directed to an axial direction before leaving the
outlet 16.
[0007] Thus, the need for improvement still exists.
SUMMARY OF THE INVENTION
[0008] It is therefore one object of the invention to provide a
centrifugal fan comprising an inlet housing including an axial
inlet; an outlet housing including an axial outlet, the outlet
housing being secured to the outlet housing to define an interior;
an electric motor disposed in the interior; an impeller disposed in
the interior and driven by the electric motor; and a plurality of
fan dampers disposed around an inner surface of the interior and
surrounding the impeller, each of the fan dampers having a
windward, concave surface facing a rotational direction of the
impeller; wherein a spiral airflow created by the impeller passes
the windward curved portions of the fan dampers and the motor
toward the outlet, and wherein a portion of the kinetic energy of
the spiral airflow is transmitted axially and the remaining kinetic
energy of the spiral airflow is converted into static pressure to
convey the spiral airflow toward the outlet so as to converge the
spiral airflow from the electric motor to the outlet, thereby
causing most of the spiral airflow to flow axially when it reaches
the outlet.
[0009] The above and other objects, features and advantages of the
invention will become apparent from the following detailed
description taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a broken away view of a typical centrifugal
fan;
[0011] FIG. 2 is a perspective view of a centrifugal fan according
to a first preferred embodiment of the invention;
[0012] FIG. 3 is an exploded view of the centrifugal fan shown in
FIG. 2;
[0013] FIG. 4 is a sectional view of the centrifugal fan shown in
FIG. 2;
[0014] FIG. 5 schematically depicts airflow through the
impeller;
[0015] FIG. 6 is a chart showing airflow speed at the outlet and
rotational speed of the impeller for the centrifugal fan of the
first preferred embodiment of the invention having fan dampers and
for a typical centrifugal fan without fan dampers;
[0016] FIG. 7 is a chart showing volumetric flow rate at the outlet
and rotational speed of the impeller for the centrifugal fan of the
first preferred embodiment of the invention having fan dampers and
for a typical centrifugal fan without fan dampers;
[0017] FIG. 8 is a perspective view of a centrifugal fan according
to a second preferred embodiment of the invention; and
[0018] FIG. 9 is a chart showing pressure in the combustion chamber
and rotational speed of the impeller for the centrifugal fan of the
second preferred embodiment of the invention having fan dampers and
for a typical centrifugal fan without fan dampers.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Referring to FIGS. 2 to 7, a centrifugal fan in accordance
with a first preferred embodiment of the invention comprises the
following components as discussed in detail below.
[0020] A bowl-shaped inlet housing 21 has a projecting inlet 20 at
one end of its axis. A bowl-shaped outlet housing 25 has a
projecting outlet 26 at one end of its axis. The inlet housing 21
and the outlet housing 25 are secured together to form a fan
housing having an interior 27. An impeller 23 and an electric motor
24 are provided in the interior 27. A ring 28 is provided on an
inner surface of the inlet housing 21 (or the outlet housing 25 in
other embodiments). A plurality of equally spaced fan dampers 22
are formed on an inner surface of the ring 28 facing the impeller
23 surrounded by the ring 28. Each fan damper 22 has a windward,
concave surface facing a rotational direction of the impeller
23.
[0021] The impeller 23 is driven by the motor 24 to create an
airflow which pass curved surfaces of the fan dampers 22 and the
motor 24 toward the outlet 26 in which a portion of the kinetic
energy of the spiral airflow is transmitted axially and the
remaining kinetic energy of the spiral airflow is converted into
static pressure to convey the airflow toward the outlet 26. The
airflow converges from the motor 24 to the outlet 26. As a result,
most of the spiral airflow flows axially when it reaches the outlet
26.
[0022] Alternatively, the ring 28 is eliminated and the fan dampers
22 are formed integrally on an inner surface of the inlet housing
21 or the outlet housing 25 in other embodiments.
[0023] Still alternatively, the ring 28 is eliminated and the fan
dampers 22 are manufactured separately prior to securing to an
inner surface of the inlet housing 21 or the outlet housing 25 in
other embodiments.
[0024] Preferably, the fan damper 22 is an elongated, curved plate
having a smooth surface so that spiral airflow reaching its
windward can be directed to flow axially after leaving its leeward.
This has the benefit of increasing airflow along an axis of the
centrifugal fan.
[0025] The fan damper 22 has a windward end 30 and a leeward end
32. The impeller 23 has a disc 31 with the fan blades equally
spaced apart and formed proximate to an edge of one surface facing
the inlet 20. The windward end 30 is at angle of 0-45 degrees with
respect to the disc 31 in which the angle is increased axially. The
leeward end 32 is at angle of 70-90 degrees with respect to the
disc 31.
[0026] It is preferred that the greater of the angle between the
windward end 30 and the disc 31 within a range the air control
efficiency increases. Also, the greater of the angle between the
leeward end 32 and the disc 31 within a range the air control
efficiency increases. However, turbulence is created when the angle
is greater than either range, and the turbulence can affect fan
energy usage. An optimum angle can be obtained based on a
rotational speed of the impeller 23. Practically, the angle can be
increased for high speed impeller and the angle can be decreased
for low speed impeller.
[0027] Referring to FIG. 6 specifically, it is a chart showing
airflow speed at the outlet 26 and rotational speed of the impeller
23 for the centrifugal fan of the first preferred embodiment of
invention having fan dampers 22 and for a typical centrifugal fan
without fan dampers. As shown, the airflow speed at the outlet 26
increases about linearly as the rotational speed of the impeller 23
increases. Specifically, the airflow speed at the outlet is 13 m/s
without the provision of fan dampers and the airflow speed at the
outlet 26 is 18.2 m/s with the provision of fan dampers 22 when the
rotational speed of the impeller 23 is 9,000 rpm (revolutions per
minute). This means that the airflow speed at the outlet 26
increases by about 40% with the provision of the fan dampers 22
according to the first preferred embodiment of centrifugal fan of
the invention.
[0028] Referring to FIG. 7 specifically, it is a chart showing
volumetric flow rate at the outlet 26 and rotational speed of the
impeller 23 for the centrifugal fan of the second preferred
embodiment of invention having fan dampers 22 and for a typical
centrifugal fan without fan dampers. As shown, the volumetric flow
rate at the outlet 26 increases about linearly as the rotational
speed of the impeller 23 increases. Specifically, the volumetric
flow rate at the outlet is 0.0313 m.sup.3/s without the provision
of fan dampers and the volumetric flow rate at the outlet 26 is
0.0441 m.sup.3/s with the provision of fan dampers 22 when the
rotational speed of the impeller 23 is 9,000 rpm. This means that
the volumetric flow rate at the outlet 26 increases by about 41%
with the provision of the fan dampers 22 according to the second
preferred embodiment of centrifugal fan of the invention.
[0029] Referring to FIGS. 8 and 9, a centrifugal fan in accordance
with a second preferred embodiment of the invention is shown. The
characteristics of the second preferred embodiment are
substantially the same as that of the first preferred embodiment
except the following:
[0030] The centrifugal fan is particularly used in a turbine
engine. The centrifugal fan includes a fan housing 51, an impeller
52 disposed in an inlet of the fan housing 51, a starter motor (not
shown) disposed in the fan housing 51, a combustion chamber 53
disposed in an intermediate portion of the fan housing 51, a
turbine 54 disposed in an outlet of the fan housing 51, and a
plurality of fan dampers 60 disposed proximate to an inner surface
of the fan housing 51 and around leeway ends of fan blades of the
impeller 52. The fan damper 60 is an elongated, curved plate having
a smooth surface so that spiral airflow leaving the impeller 52 and
reaching its windward can be directed to flow axially after leaving
its leeward. It is noted that the fan damper 60 has a windward,
concave surface facing a rotational direction of the impeller
52.
[0031] In operation, the impeller 52 is driven by the starter motor
to create an airflow which passes curved surfaces of the fan
dampers 60 toward the combustion chamber 53. Thus, pressure in the
combustion chamber 53 increases. Fuel is injected into the
combustion chamber 53 to mix with the pressurized air prior to
combustion. The combusted mixture rotates the turbine 54 to
generate mechanical energy in which a portion of the kinetic energy
of the combusted mixture is used to rotate the impeller 52, thereby
finishing a thermal cycle of the turbine engine.
[0032] The spiral airflow generated by the impeller 52 is converted
into axial airflow and static pressure for increasing pressure in
the combustion chamber 53. As a result, thermal efficiency of the
turbine engine is increased.
[0033] Referring to FIG. 9 specifically, it is a chart showing
pressure in the combustion chamber 53 and rotational speed of the
impeller 52 for the centrifugal fan of the second preferred
embodiment of the invention having fan dampers 60 and for a typical
centrifugal fan without fan dampers. As shown, the pressure in the
combustion chamber 53 increases about linearly as the rotational
speed of the impeller 52 increases. Specifically, the pressure in
the combustion chamber is 19.42 kpa without the provision of fan
dampers and the pressure in the combustion chamber 53 is 24.87 kpa
with the provision of fan dampers 60 when the rotational speed of
the impeller 52 is 1.2 Mach. This means that pressure in the
combustion chamber 53 increases by about 28% with the provision of
the fan dampers 60 according to the second preferred embodiment of
centrifugal fan of the invention.
[0034] While the invention has been described in terms of preferred
embodiments, those skilled in the art will recognize that the
invention can be practiced with modifications within the spirit and
scope of the appended claims.
* * * * *