U.S. patent application number 11/148383 was filed with the patent office on 2006-05-11 for centrifugal fan.
Invention is credited to Tsan-Nan Chien, Yu-Nien Huang, Ping-Sheng Kao, Yu Liu.
Application Number | 20060099071 11/148383 |
Document ID | / |
Family ID | 36316503 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060099071 |
Kind Code |
A1 |
Kao; Ping-Sheng ; et
al. |
May 11, 2006 |
Centrifugal fan
Abstract
A centrifugal fan is described. The centrifugal fan is suitable
for a portable electrical apparatus. A tongue shape is formed from
a volute sidewall of a casing of the centrifugal fan. The volute
sidewall is formed with at least one groove substantially extending
horizontally at the tongue shape. Therefore, when the blades rotate
to generate a wake flow to blow on a surface of the volute sidewall
at the tongue shape, noise generated by the centrifugal fan can be
reduced.
Inventors: |
Kao; Ping-Sheng; (Hsinchu
City, TW) ; Chien; Tsan-Nan; (Taipei City, TW)
; Liu; Yu; (Tao Yuan City, TW) ; Huang;
Yu-Nien; (Chung Li City, TW) |
Correspondence
Address: |
RABIN & BERDO, P.C.;Suite 500
1101 14 Street
Washington
DC
20005
US
|
Family ID: |
36316503 |
Appl. No.: |
11/148383 |
Filed: |
June 9, 2005 |
Current U.S.
Class: |
415/206 |
Current CPC
Class: |
F04D 29/667 20130101;
F04D 29/422 20130101 |
Class at
Publication: |
415/206 |
International
Class: |
F04D 29/44 20060101
F04D029/44 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2004 |
TW |
93133855 |
Claims
1. A centrifugal fan, suitable for a portable electrical apparatus,
comprising: a casing, the casing having a volute sidewall to define
a cavity and an outlet, wherein a tongue shape is formed from the
volute sidewall on at least one side of the outlet; blades disposed
around and vertically with a rotational axis on the casing; and at
least one groove set on the volute sidewall, the groove
substantially extending horizontally at the tongue shape.
2. The centrifugal fan according to claim 1, wherein the portable
electrical apparatus is a notebook personal computer (PC).
3. The centrifugal fan according to claim 1, wherein the groove has
a rectangular cross-section.
4. The centrifugal fan according to claim 1, wherein the groove has
a rounded cross-section
5. The centrifugal fan according to claim 1, wherein the groove is
such located that a part of the groove faces the blades along a
height direction of the blades.
6. The centrifugal fan according to claim 5, wherein the groove is
such located that the groove faces the blades at a midpoint of the
height direction of the blades.
7. A casing of centrifugal fan, suitable for a portable electrical
apparatus, comprising: a bottom plate; a volute sidewall to define
a cavity and an outlet, wherein a tongue shape is formed from the
volute sidewall on at least one side of the outlet; and at least
one groove formed on the tongue shape of the volute sidewall, the
groove substantially extending horizontally at the tongue
shape.
8. The casing of centrifugal fan according to claim 7, wherein the
portable electrical apparatus is a notebook PC.
9. The casing of centrifugal fan according to claim 7, wherein the
groove has a rectangular cross-section.
10. The casing of centrifugal fan according to claim 7, wherein the
groove has a rounded cross-section.
11. The casing of centrifugal fan according to claim 7, wherein the
bottom plate rotatably supports blades thereon, and wherein the
groove is such located that a part of the groove faces the blades
along a height direction of the blades after the blades are
supported on the bottom plate.
12. The casing of centrifugal fan according to claim 11, wherein
the groove is such located that the groove faces the blades at a
midpoint of the height direction of the blades.
Description
RELATED APPLICATIONS
[0001] The present application is based on, and claims priority
from, Taiwan application Ser. No. 93133855, filed Nov. 5, 2004, the
disclosure of which is hereby incorporated by reference herein in
its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a centrifugal fan, and more
particularly, to a centrifugal fan with a surface of a volute
sidewall at a tongue shape being formed with at least one groove
substantially extending horizontally.
[0004] 2. Description of the Related Art
[0005] A heat dissipation module is necessary to provide effective
heat dissipation for a portable electrical apparatus, and
especially for a notebook personal computer (PC), so as to allow
the best performance. When heat accumulates in and cannot dissipate
from the apparatus, the electrical devices and the apparatus as a
whole cannot work normally. The computer system, in particular,
will crash. However, in order to satisfy the market requirement for
mobilization, sufficient space cannot be possibly formed in the
casing of the notebook PC for natural convection. Because heat
dissipation design for high-frequency devices has encountered its
bottleneck, the heat dissipation module of the notebook PC tends to
dissipate heat with forced convection generated by a centrifugal
fan.
[0006] Reference is made to FIGS. 1 and 1A, which depict a
perspective view and a top plan view showing a centrifugal fan of
the prior art. The centrifugal fan 10, installed in a portable
electrical apparatus such as a notebook PC, comprises a casing 11
and blades 31. The casing 11 has a volute sidewall 13 and a bottom
plate 15, and the casing 11 defines a cavity 17 and an outlet 19. A
volute channel 21 is jointly defined by the cavity 17 and the
outlet 19, and a tongue shape 23 is formed from the volute sidewall
13 on a side of the outlet 19. The blades 31 are disposed
vertically with a rotational axis 33 on the bottom plate 15 in the
cavity 17. Rotation of blades 31 drives a horizontal airflow 25.
The horizontal airflow 25 can be exhausted via dynamic and static
pressures generated by the horizontal airflow 25 passing through
the volute channel 21.
[0007] The outlet 19 of the prior art uses a curved surface and
divergent duct with a constant cross-section, which means a surface
16 of the volute sidewall 13 at the tongue shape 23 is parallel to
the rotational axis 33. This makes the airflow generate dynamic and
static pressure, which resists outside force to achieve the effect
of heat dissipation.
[0008] Reference is made to FIG. 2, which depicts a schematic
diagram showing a wake flow generated by the centrifugal fan of the
prior art blowing on the volute sidewall at the tongue shape. When
the wake flow 35 generated by the blades 31 is blowing on the
surface 16 of the volute sidewall 13 at the tongue shape 23, each
blasting point 41 is generated and regarded as a sound source that
generates narrow band noise 43. Because the surface 16 of the
volute sidewall 13 at the tongue shape 23 is parallel to the
rotational axis 33, according to the superposition principle, the
narrow band noise 43 with a large amplitude 45 and constant blade
pass frequency will be generated. Once it is necessary to enhance
the efficiency of the heat dissipation, the flow rate and the wind
velocity must be increased. However, the more the rotational speed
and the flow rate are increased, the higher the frequency of the
noise band is. Therefore, the noise is increasing. The trade off
between the noise and the heat dissipation is a serious
problem.
SUMMARY OF THE INVENTION
[0009] It is an aspect of the present invention to provide a
centrifugal fan suitable for a portable electrical apparatus. A
tongue shape is formed from the volute sidewall of a casing of the
centrifugal fan. The volute sidewall is formed with at least one
groove substantially extending horizontally at the tongue shape.
Therefore, when the blades rotate to generate a wake flow to blow
the surface of the volute sidewall at the tongue shape, noise
generated by the centrifugal fan can be reduced.
[0010] According to the aforementioned aspect of the present
invention, a centrifugal fan is provided, which is suitable for a
portable electrical apparatus and comprises a casing having a
bottom plate and a volute sidewall disposed on the bottom plate to
define a cavity and an outlet. A tongue shape is formed from the
volute sidewall on at least one side of the outlet; and blades are
disposed vertically with a rotational axis on the bottom plate of
the cavity. The volute sidewall is formed with at least one groove
substantially extending horizontally at the tongue shape.
[0011] In a preferred embodiment of the present invention, the
aforementioned portable electrical apparatus is a notebook PC.
[0012] In a preferred embodiment of the present invention, a
surface of the aforementioned volute sidewall at the tongue shape
is, for example, formed with on or more grooves substantially
extending horizontally.
[0013] The surface of the volute sidewall at the tongue shape of
the centrifugal fan of the invention is formed with at least one
groove substantially extending horizontally, resulting in easy
manufacture and improvement of the issue of noise caused by the
centrifugal fan.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The foregoing aspects and many of the attendant advantages
of this invention will become more readily appreciated as the same
becomes better understood by reference to the following detailed
description, when taken in conjunction with the accompanying
drawings, wherein:
[0015] FIGS. 1 and 1A depict a perspective view and a top plan view
showing a centrifugal fan of the prior art;
[0016] FIG. 2 depicts a schematic diagram showing a wake flow
generated by the centrifugal fan of the prior art blowing on the
volute sidewall at the tongue shape;
[0017] FIG. 3 depicts a perspective view showing a centrifugal fan
in accordance with a preferred embodiment of the present
invention;
[0018] FIG. 4 depicts a schematic diagram showing a wake flow
generated by the centrifugal fan in accordance with a preferred
embodiment of the present invention blowing on the volute sidewall
at the tongue shape;
[0019] FIG. 4A illustrates the location of the groove with respect
to the blades in accordance with a preferred embodiment of the
present invention;
[0020] FIG. 5 depicts a cross-sectional view of a surface of a
volute sidewall at a tongue shape in accordance with another
preferred embodiment of the present invention;
[0021] FIG. 6 depicts a cross-sectional view of a surface of a
volute sidewall at a tongue shape in accordance with another
preferred embodiment of the present invention;
[0022] FIG. 7A illustrates the blade pass frequency of a
centrifugal fan where no groove is formed to the surface of the
volute sidewall; and
[0023] FIG. 7B illustrates the blade pass frequency of a
centrifugal fan where one groove is formed to the surface of the
volute sidewall.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0024] Reference is made to FIG. 3, which depicts a perspective
view showing a centrifugal fan in accordance with a preferred
embodiment of the present invention. The centrifugal fan 100
installed in a portable electrical apparatus such as a notebook PC,
comprises a casing 111 and blades 131. The casing 111 has a volute
sidewall 113 and a bottom plate 115, and the casing 111 defines a
cavity 117 and an outlet 119. A volute channel 121 is jointly
defined by the cavity 117 and the outlet 119, and a tongue shape
123 is formed from the volute sidewall 113 on a side of the outlet
119. The blades 131 are disposed vertically with a rotational axis
133 on the bottom plate 115 in the cavity 117, and preferably, the
blades 131 are disposed vertically to the bottom plate 115.
Rotation of the blades 131 drives a horizontal airflow 125. The
horizontal airflow 125 can be exhausted via dynamic and static
pressure generated by the horizontal airflow 125 passing through
the volute channel 121. Meanwhile, when horizontal airflow 125 is
generated by the blades 131 rotating, the blades 131 blow on a
surface 116 of the volute sidewall 113 at the tongue shape 123. A
groove 118 is formed on the tongue shape 123 and substantially
extends horizontally to destruct the wave superposition resulted
from a wake flow 135 (as shown in FIG. 4) generated by the blades
131 rotating on the surface 116 of the volute sidewall 113 at the
tongue shape 123, so that the noise generated by the centrifugal
fan can be reduced. According to this invention, the groove 118 may
be integrally formed on the casing 111 by plastic injection
molding, metal casting or metal stamping.
[0025] Reference is made to FIG. 4, which depicts a schematic
diagram showing a wake flow 135 generated by the centrifugal fan in
accordance with a preferred embodiment of the present invention
blowing on the volute sidewall at the tongue shape. When the wake
flow 135 generated by the blades 131 is blowing on the surface 116
of the volute sidewall 113 at the tongue shape 123 (as shown in
FIG. 3), each blasting point 141 is generated and regarded as a
sound source that generates narrow band noise 143. Because the
surface 116 of the volute sidewall 113 at the tongue shape 123 is
formed with a groove 118 substantially extending horizontally, the
time at which each sound source is generated is different.
Therefore, comparing to priot amplitude 45 (as shown in FIG. 2),
the amplitude 145 can be substantially reduced as a result of less
constructive interference of sound waves generated by the sound
sources on different time; that is to say, the narrow band noise
143 is lessened.
[0026] According to this invention, a part of the groove 118
substantially extending horizontally on the surface 116 corresponds
to where the wake flow 135 of the blades 131 is blown. For example,
reference is made to FIG. 4A, the groove 118 formed on the surface
116 of the volute side wall 113 at the tongue shape 123 is located
to face the blades 131 at a midpoint of a height direction of the
blades 131. The groove 118 alternatively be located to face an
upper side or a lower side with respect to the height direction of
the blades 131, so long as a part of the groove 118 corresponds to
where the wake flow 135 of the blades 131 are blown. In addition,
the surface 116 of the volute sidewall 113 at the tongue shape 123
may also be formed with two ore more grooves 118 substantially
extending horizontally. FIG. 4A depicts a perspective view showing
a centrifugal fan in accordance with a preferred embodiment of the
present invention, where the groove 118 substantially extending
horizontally on the surface 116 is of a rectangular
cross-section.
[0027] FIG. 5 depicts a cross-sectional view of a surface of a
volute sidewall at a tongue shape in accordance with another
preferred embodiment of the present invention, wherein the surface
116 is formed thereon with two grooves 118 each of rectangular
cross-section. FIG. 6 depicts a cross-sectional view of a surface
of a volute sidewall at a tongue shape in accordance with another
preferred embodiment of the present invention, wherein the surface
116 is formed with a groove 118a of a rounded cross-section.
However, this invention is not limited the above number or
cross-sectional shapes of the grooves. Persons having ordinary
skills in the relevant art should be able to comprehend this
invention and utilizes other means, in accordance with the actual
needs, to adjust the number or cross-sectional shapes of the
grooves, or to combine plural grooves of different cross-sections
on the surface, which are not described in detail herein.
[0028] As mentioned above, the groove 118 formed on the surface of
the volute sidewall 113 at the tongue shape 123 can effectively
reduce the amplitude 145 of the noise. Hence, the broader band
noise is obtained to allow a user to experience a better quality of
sound.
[0029] FIG. 7A illustrates the blade pass frequency of a
centrifugal fan where no groove is formed to the surface of the
volute sidewall. Significant blade pass frequency can be observed
at the operation frequencies of 900 Hz and 1900 Hz. FIG. 7B
illustrates the blade pass frequency of a centrifugal fan where one
groove is formed to the surface of the volute sidewall. FIG. 7B
clearly illustrates the significant reduction of the blade pass
frequency at the operation frequencies of 900 Hz and 1900 Hz.
[0030] Therefore, according to the aforementioned preferred
embodiments, one advantage of the centrifugal fan of the present
invention is that the surface of the volute sidewall at the tongue
shape of the centrifugal fan is formed with at least one groove
substantially extending horizontally. Therefore, when the blades
rotate to generate a wake flow to blow on the surface of the volute
sidewall at the tongue shape, noise generated by the centrifugal
fan can be reduced.
[0031] As is understood by a person skilled in the art, the
foregoing preferred embodiments of the present invention are
illustrated of the present invention rather than limiting of the
present invention. It is intended that various modifications and
similar arrangements be included within the spirit and scope of the
appended claims, the scope of which should be accorded the broadest
interpretation so as to encompass all such modifications and
similar structure.
* * * * *