U.S. patent application number 11/477371 was filed with the patent office on 2007-10-25 for centrifugal fan.
This patent application is currently assigned to Quanta Computer Inc.. Invention is credited to Yu-Nien Huang, Chun-Fa Tseng, Cheng-Yu Wang, Shun-Ta Yu.
Application Number | 20070248459 11/477371 |
Document ID | / |
Family ID | 38619627 |
Filed Date | 2007-10-25 |
United States Patent
Application |
20070248459 |
Kind Code |
A1 |
Tseng; Chun-Fa ; et
al. |
October 25, 2007 |
Centrifugal fan
Abstract
A centrifugal fan includes a spiral housing, a driving mechanism
and multiple internally mounted impellers. The driving mechanism
and the centrifugal impeller, rotated by the driving mechanism, are
installed in the spiral housing. A spiral flow channel is defined
between the centrifugal impeller and the spiral housing. When the
centrifugal impeller rotates, airflow is sucked axially into the
spiral housing through an inlet opening and moves along each blade
of the centrifugal impeller into the spiral flow channel. The
centrifugal impeller includes a hub and multiple blades. Each blade
is secured to the hub at one end and has at least one vertical
convex strip or vertical concave strip at an opposite end, wherein
the vertical convex strip or vertical concave strip on each of
blade disturbs the airflow across thereof and reduces narrow-band
noise.
Inventors: |
Tseng; Chun-Fa; (Kaohsiung
City, TW) ; Huang; Yu-Nien; (Chung Li City, TW)
; Yu; Shun-Ta; (Taipei City, TW) ; Wang;
Cheng-Yu; (Hsinchu City, TW) |
Correspondence
Address: |
RABIN & Berdo, PC
1101 14TH STREET, NW, SUITE 500
WASHINGTON
DC
20005
US
|
Assignee: |
Quanta Computer Inc.
|
Family ID: |
38619627 |
Appl. No.: |
11/477371 |
Filed: |
June 30, 2006 |
Current U.S.
Class: |
415/206 |
Current CPC
Class: |
F04D 29/281 20130101;
F04D 29/681 20130101; F04D 29/30 20130101 |
Class at
Publication: |
415/206 |
International
Class: |
F04D 29/44 20060101
F04D029/44 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 24, 2006 |
TW |
95114589 |
Claims
1. A centrifugal fan, comprising: a housing, having an inlet
opening; a driving mechanism mounted in the housing; a centrifugal
impeller, driven by the driving mechanism, a flow channel is
defined between the centrifugal impeller and the housing, the
centrifugal impeller comprising: a hub; and multiple blades, each
of the multiple blades secured to the hub at one end and having at
least one vertical convex strip at an opposite end, when the
centrifugal impeller rotates, airflow is sucked axially into the
housing through the inlet opening, and moves along each of the
multiple blades, wherein the vertical convex strip at each of the
multiple blades disturbs the airflow across thereof and reduces
narrow-band noises.
2. The centrifugal fan of claim 1, wherein the driving mechanism is
a motor.
3. A centrifugal fan, comprising: a housing, having an inlet
opening; a driving mechanism, mounted in the housing; a centrifugal
impeller, driven by the driving mechanism, a flow channel is
defined between the centrifugal impeller and the housing, the
centrifugal impeller comprising: a hub; and multiple blades, each
of the multiple blades secured to the hub at one end and having at
least one vertical concave strip at an opposite end, when the
centrifugal impeller rotates, airflow is sucked axially into the
housing through the inlet opening, and moves along each of the
multiple blades, wherein the vertical concave strip at each of the
multiple blades disturbs the airflow across thereof and reduces
narrow-band noise.
4. The centrifugal fan of claim 3, wherein the driving mechanism is
a motor.
Description
RELATED APPLICATIONS
[0001] The present application is based on, and claims priority
from, Taiwan Application Serial Number 95114589, filed on Apr. 24,
2006, the disclosure of which is hereby incorporated by reference
herein in its entirety.
BACKGROUND
[0002] 1. Field of Invention
[0003] The present invention relates to a centrifugal fan. More
particularly, the present invention relates to a centrifugal fan
with noise reduction functionality.
[0004] 2. Description of Related Art
[0005] As notebook PCs become thinner, less space is available for
heat convection and heat dissipation components inside the notebook
PC case housing. High-frequency components, such as the CPU
(central processing unit) and graphics processing chip, also place
limitations on heat dissipation designs. Thus, the mainstream
method to dissipate heat is forced heat convection via a
centrifugal fan.
[0006] A centrifugal fan employs a spiral flow channel design to
convert dynamic air energy into static pressure so as to overcome
the high air flow impedance inside the notebook PC case housing.
However, high static pressure generating centrifugal fans face the
dual challenge of reducing noise and improving heat dissipation
efficiency. Noise can be divided into broadband noise and
narrowband noise, wherein narrowband noise is preferably eliminated
from a centrifugal fan.
[0007] FIG. 1 illustrates a perspective view of a conventional
centrifugal fan. A centrifugal fan 100 includes a spiral housing
102, which has a motor (not illustrated) and an internal
centrifugal impeller 104. When the motor rotates the centrifugal
impeller 104, driven airflow moves along a spiral flow channel 110.
A wake flow 112, coming out of blades 106 of the centrifugal
impeller 104, crashes against the inner walls of the spiral flow
channel 110, thereby creating a BPF (Blade Pass Frequency). BPF
often becomes high-frequency, narrow-band noise, especially in a
high static pressure generating centrifugal fan. BPF also generates
an annoying high-frequency, narrow-band noise when the wake flow
112 hits a cut-off 103 of a centrifugal fan 100.
SUMMARY
[0008] It is therefore an objective of the present invention to
provide a centrifugal fan with a noise reduction functionality so
as to reduce noise and improve the overall heat dissipation
efficiency.
[0009] In accordance with the foregoing and other objectives of the
present invention, a centrifugal fan includes a spiral housing, a
driving mechanism and multiple internally mounted impellers. The
driving mechanism and the centrifugal impeller, rotated by the
driving mechanism, are installed in the spiral housing. A spiral
flow channel exists between the centrifugal impeller and the spiral
housing. When the centrifugal impeller rotates, airflow is sucked
axially into the spiral housing through an inlet opening and moves
along each blade of the centrifugal impeller into the spiral flow
channel. The centrifugal impeller includes a hub and multiple
blades. Each of the blades is secured to the hub at one end and has
at least one vertical convex strip or vertical concave strip at an
opposite end, wherein the vertical convex strip or vertical concave
strip on each blade disturbs the airflow across thereof and reduces
narrow-band noises.
[0010] Thus, each blade of the centrifugal fan has a vertical
convex strip or a vertical concave strip at an end of the windward
side so as to disturb airflows across thereof, thereby decreasing
high-frequency and narrow-band noises. Such centrifugal impeller
design overcomes a challenge between noise reducing and heat
dissipation efficiency improving in a notebook computer.
[0011] It is to be understood that both the foregoing general
description and the following detailed description are by examples,
and are intended to provide further explanation of the invention as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention. In the
drawings,
[0013] FIG. 1 illustrates a perspective view of a conventional
centrifugal fan;
[0014] FIG. 2 illustrates a cross-sectional view of a centrifugal
fan according to one preferred embodiment of this invention;
and
[0015] FIGS. 3A and 3B respectively illustrate two types of
centrifugal impellers according to one preferred embodiment of this
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] Reference will now be made in detail to the present
preferred embodiments of the invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers are used in the drawings and the description
to refer to the same or like parts.
[0017] FIG. 2 illustrates a cross-sectional view of a centrifugal
fan according to one preferred embodiment of this invention. A
centrifugal fan 200 has a spiral housing 202. A centrifugal
impeller and a driving mechanism 208 (such as a motor) are
installed in the spiral housing 202. The centrifugal impeller
includes a hub 204 and multiple blades 206 (like blades 106 in FIG.
1). When the driving mechanism 208 rotates the centrifugal
impeller, rotating blades 206 constantly suck airflow along the
direction 214. The airflow moves axially into the spiral housing
202 through an inlet opening 202a, and then moves along each of
blades 206 (i.e. along the direction 216), and finally into a
spiral flow channel 207 (like the spiral flow channel 110 in FIG.
1). In order to distribute the airflow in the direction 216, a
vertical convex strip 205a or a vertical concave strip 205b is
formed at the end and the windward side of each blade 206 to
disturb the airflow across thereof. On the contrary, a conventional
blade has a flat surface on its windward side such that the airflow
along the direction 216 has a bigger impact against the spiral flow
channel 207 (i.e. inner walls of the housing 202). The bigger the
impact against the spiral flow channel 207, the more high-frequency
and narrow-band noises are generated.
[0018] In this preferred embodiment, a width d of the vertical
convex strip 205a or the vertical concave strip 205b is
approximately equal to the thickness of the blade 206. However, the
width d is not a constant value and its optimum value could vary
according to the blade length, blade rotation speed, flow channel
shape etc, and does not influence the dissipation performance of
the centrifugal fan. More than one vertical convex strip 205a or
vertical concave strip 205b may be formed on the blade 206 as long
as the dissipation performance of the centrifugal fan is not
influenced.
[0019] FIGS. 3A and 3B respectively illustrates two types of
centrifugal impellers according to one preferred embodiment of this
invention.
[0020] In FIG. 3A, a hub 204 and one blade 206a of blades 206 are
illustrated. The hub 204 and the blade 206a both rotate in the
direction 210. The vertical concave strips 205a are formed on the
windward side of the blade 206a, and the airflow 212a is therefore
disturbed and its impact on the cut-off 203 (like the cut-off 103
in FIG. 1) is reduced, thereby decreasing the high-frequency,
narrow-band noise.
[0021] In FIG. 3B, a hub 204 and one blade 206b of the blades 206
are illustrated. The hub 204 and the blade 206b both rotate in the
direction 210. The vertical convex strips 205b are formed on the
windward side of the blade 206b, and the airflow 212b is therefore
disturbed and its impact on the cut-off 203 (like cut-off 103 in
FIG. 1) is reduced, thereby decreasing the high-frequency and
narrow-band noises.
[0022] According to the preferred embodiments of the present
invention, each blade of the centrifugal fan has a vertical convex
strip or a vertical concave strip at the end of the blade, at the
windward side so as to disturb the airflow across thereof, thereby
decreasing the high-frequency, narrow-band noise. Such a
centrifugal impeller design reduces noise and improves heat
dissipation efficiency in a notebook PC.
[0023] It will be apparent to those skilled in the art that various
modifications and variations can be made to the structure of the
present invention without departing from the scope or spirit of the
invention. In view of the foregoing, it is intended that the
present invention cover modifications and variations of this
invention provided they fall within the scope of the following
claims and their equivalents.
* * * * *