U.S. patent application number 12/908059 was filed with the patent office on 2012-04-26 for fan structure.
This patent application is currently assigned to Zaward Corporation. Invention is credited to Cheng-Kang CHEN.
Application Number | 20120100001 12/908059 |
Document ID | / |
Family ID | 45973169 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120100001 |
Kind Code |
A1 |
CHEN; Cheng-Kang |
April 26, 2012 |
FAN STRUCTURE
Abstract
A fan structure includes a hub and a plurality of blades
extending from the periphery of the hub. The airflow generated by
the fan forms a boundary layer on the surface of each blade. The
present invention is characterized in that: each of the blades is
provided with a plurality of polygonal dents, a turbulent flow is
generated in each dent when the airflow passes through the dent, a
plurality of the turbulent flows collect together to form an air
film between the surface of blade and the boundary layer. By this
structure, the distance of separating points from the boundary
layer is extended, and the frictional force and noise caused by the
rotation of the blades are reduced.
Inventors: |
CHEN; Cheng-Kang; (Chung Ho
City, TW) |
Assignee: |
Zaward Corporation
|
Family ID: |
45973169 |
Appl. No.: |
12/908059 |
Filed: |
October 20, 2010 |
Current U.S.
Class: |
416/228 |
Current CPC
Class: |
F04D 29/681 20130101;
F04D 29/384 20130101; F04D 25/0613 20130101 |
Class at
Publication: |
416/228 |
International
Class: |
F04D 29/38 20060101
F04D029/38 |
Claims
1. A fan structure including a hub and a plurality of blades
extending from the periphery of the hub, the airflow generated by
the fan forming a boundary layer on the surface of each blade,
characterized in that: each of the blades is provided with a
plurality of polygonal dents, a turbulent flow is generated in each
dent when the airflow passes through the dent, and a plurality of
the turbulent flows collect together to form an air film between
the surface of blade and the boundary layer.
2. The fan structure according to claim 1, further including a
casing, the casing being formed into a square frame and having an
accommodating space, the hub and the blades being combined in the
accommodating space.
3. The fan structure according to claim 2, wherein the periphery of
the casing is formed with at least one recessed portion recessed
toward the accommodating space.
4. The fan structure according to claim 1, wherein two adjacent
sides of the polygonal dent form an angle.
5. The fan structure according to claim 1, wherein each of the
polygonal dents is formed into any one shape selected from the
group constituting of triangle, quadrangle, pentagon, hexagon,
heptagon and octagon.
6. The fan structure according to claim 1, wherein each of the
polygonal dents on the blades is formed into at least two shapes
selected from the group constituting of triangle, quadrangle,
pentagon, hexagon, heptagon and octagon.
7. The fan structure according to claim 1, wherein the blade
includes a first surface and a second surface opposite to the first
surface, the polygonal dents are provided on the first surface and
the second surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a fan, in particular to a
fan structure which is capable of reducing an aerodynamic drag.
[0003] 2. Description of Prior Art
[0004] A conventional heat-dissipating system applied to a computer
host or other electronic apparatus includes a heat-dissipating fan
for generating compulsive airflow for dissipating the heat to the
outside. Since the heat-dissipating fan operates for a long period
of time, the heat-dissipating effect thereof is much relevant to
its operating efficiency. On the other hand, if the noise generated
by the heat-dissipating fan is too large, the user will feel very
uncomfortable.
[0005] In general, airflow is generated when a fan rotates. The
airflow forms a thin layer, referred to as a boundary layer, when
it passes through the surface of blades of the fan. The boundary
layer of airflow may generate turbulent flows beyond separating
points where the airflow separates from the blades. The turbulent
flows may cause the blades to vibrate and thus generate undesirable
noise. Further, due to the turbulent flows, a frictional force may
generate between the surface of the blade and the airflow, which
deteriorates the rotating efficiency of the fan. According to
experimental data, controlling a flow field is one method for
reducing the frictional force and extending the distance of the
separating points from the boundary layer. Thus, it is an important
issue for the present Inventor to change the flow field around the
surface of an article so as to reduce the frictional force.
[0006] In view of the above, the present Inventor proposes a
reasonable and novel structure based on his research and expert
knowledge.
SUMMARY OF THE INVENTION
[0007] The present invention is to provide a fan structure, which
is capable of reducing a frictional force and noise generated by
the fan.
[0008] The present invention is to provide a fan structure, whereby
the rotation of blades is smoother, labor-saving and power-saving,
and the heat-dissipating efficiency of the fan is increased.
[0009] The present invention is to provide a fan structure
including a hub and a plurality of blades extending from the
periphery of the hub, the airflow generated by the fan forming a
boundary layer on the surface of each blade, characterized in that:
each of the blades is provided with a plurality of polygonal dents,
a turbulent flow is generated in each dent when the airflow passes
through the dent, and a plurality of the turbulent flows collect
together to form an air film between the surface of blade and the
boundary layer.
[0010] The present invention is to provide a fan structure, in
which the periphery of a casing is formed with recessed portions
recessed toward an accommodating space in the fan. With this
arrangement, more external air can be introduced into an intake
side and the exhaust resistance generated on an exhaust side can be
lowered.
[0011] The present invention is to provide a fan structure, in
which the polygonal dents provided on the surface of each blade is
formed into a shape selected from a group constituting of triangle,
quadrangle, pentagon, hexagon, heptagon and octagon. With this
arrangement, the fan can generate turbulent flows in each polygonal
dent at different rotating speeds.
[0012] In comparison with prior art, the fan structure of the
present invention is provided on the blade with a plurality of
polygonal dents. When the airflow passes through the surface of
each blade, the airflow is brought into contact with the periphery
of each polygonal dent to generate a turbulent flow. The turbulent
flow stays in the polygonal dent. A plurality of the turbulent
flows collect together to form an air film for separating the
surface of the blade from the boundary layer. Since the air film
can extend the distance of the separating points from the boundary
layer to thereby prevent the generation of the turbulent flows near
the blades, the noise and the frictional force generated by the
turbulent flows can be reduced. Therefore, the rotation of the
blades is smoother, labor-saving and power-saving, and the
heat-dissipating efficiency of the fan is increased.
BRIEF DESCRIPTION OF DRAWING
[0013] FIG. 1 is an assembled perspective view showing the external
appearance of the fan according to the present invention;
[0014] FIG. 2 is a perspective view showing the external appearance
of the hub and the blades according to the present invention;
[0015] FIG. 3 is an assembled cross-sectional view showing the hub
and the blades according to the present invention;
[0016] FIG. 4 is a schematic view showing the airflow generated by
the fan according to the present invention;
[0017] FIG. 5 is a schematic view showing the relationship between
the blade and the airflow generated by the fan according to the
present invention; and
[0018] FIG. 6 is a schematic view showing the blade according to a
second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The detailed description and technical contents of the
present invention will become apparent with the following detailed
description accompanied with related drawings. It is noteworthy to
point out that the drawings is provided for the illustration
purpose only, but not intended for limiting the scope of the
present invention.
[0020] Please refer to FIGS. 1 to 3. The present invention provides
a fan 1, which includes a casing 10, a hub 20 and a plurality of
blades 30 extending from the periphery of the hub 20.
[0021] The casing 10 is formed into a square frame and has an
accommodating space 100 therein. The hub 20 and the plurality of
blades 30 are combined in the accommodating space 100. The casing
10 comprises an intake side 11 and an exhaust side 12 opposite to
the intake side 11. The peripheries of the intake side 11 and the
exhaust side 12 are formed with a recessed portion 13 respectively
which is recessed toward the accommodating space 100. In the
present embodiment, four recessed portions 13 are provided, and
each recessed portion 13 is provided in the center of each side of
the casing 10.
[0022] The hub 20 and the blades 30 extending from the periphery of
the hub 20 are combined in the accommodating space 100. The
interior of the hub 20 has a shaft 21 and a motor (not shown). The
motor drives the shaft 21 of the hub 20 to rotate, which causes the
blades 30 provided at the periphery of the hub 20 to rotate
accordingly to thereby generate airflow.
[0023] Each of the blades 30 comprises a first surface 31 and a
second surface 32 opposite to the first surface 31. Each of the
blades 30 is provided on its surfaces with a plurality of polygonal
dents 33. These polygonal dents 33 may be formed into any one shape
selected from the group constituting of triangle, quadrangle,
pentagon, hexagon, heptagon and octagon. Thus, two adjacent sides
of the polygonal dent 33 form an angle. In the present embodiment,
the first surface 31 and the second surface 32 of the blade 30 are
provided with the polygonal dents 33. In practice, the polygonal
dents 33 may be only provided on the first surface 31 or the second
surface 32.
[0024] Please refer to FIGS. 4 and 5. FIG. 4 is a schematic view
showing the airflow generated by the fan according to the present
invention, and FIG. 5 is a schematic view showing the relationship
between the blade and the airflow generated by the fan according to
the present invention. When the fan 1 rotates, the recessed
portions 13 are configured to facilitate more external air to be
introduced into the intake side 11. When the airflow is exhausted
from the exhaust side 12, the recessed portions 13 are configured
to lower the exhaust resistance of the airflow.
[0025] The airflow A generated by the fan 1 forms a boundary layer
B on the surface of each blade 30. On the other hand, when the
airflow A passes through the periphery of each polygonal dent 31,
the airflow A generates a turbulent flow T in the polygonal dent
33. Many turbulent flows T collect together to form an air film
between the surface of the blade 30 and the boundary layer B. The
air film can extend the distance of separating points S from the
boundary layer B, so that the separating points S are formed
outside the blade 30. With this arrangement, the generation of the
turbulent flows can be prevented in the vicinity of the blades 30,
whereby the noise and the frictional force caused by the turbulent
flows can be reduced.
[0026] In the above structure, the turbulent flow T is often
generated at the periphery of each polygonal dent 33. Further, when
the speed of the airflow A increases, the turbulent flow A can be
generated more easily. Thus, when the speed of the airflow A is
larger, each of the polygonal dents 33 may be formed into a shape
of fewer sides such as a triangle or quadrangle shape. Contrarily,
when the speed of the airflow A is smaller, each of the polygonal
dents 33 may be formed into a shape of more sides such as a hexagon
or heptagon shape.
[0027] Please refer to FIG. 6, which shows the second embodiment of
the present invention. The difference between the second embodiment
and the first embodiment lies in that: the polygonal dents 33a on
the blade 30a may be formed into at least two shapes selected from
the group constituting of triangle, quadrangle, pentagon, hexagon,
heptagon and octagon.
[0028] Although the present invention has been described with
reference to the foregoing preferred embodiments, it will be
understood that the invention is not limited to the details thereof
Various equivalent variations and modifications can still occur to
those skilled in this art in view of the teachings of the present
invention. Thus, all such variations and equivalent modifications
are also embraced within the scope of the invention as defined in
the appended claims.
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