U.S. patent application number 13/906401 was filed with the patent office on 2013-12-05 for axial flow blower.
This patent application is currently assigned to DENSO CORPORATION. The applicant listed for this patent is DENSO CORPORATION. Invention is credited to Masaru Kamiya, Hideki Ooya.
Application Number | 20130323098 13/906401 |
Document ID | / |
Family ID | 49670496 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130323098 |
Kind Code |
A1 |
Ooya; Hideki ; et
al. |
December 5, 2013 |
AXIAL FLOW BLOWER
Abstract
TECHNICAL PROBLEM To provides a blower which aims at both a
noise reduction effect and the inherent blowing performance
SOLUTION TO PROGRAM An axial flow blower which is provided with an
electric motor, and a blower fan which has a hub which is attached
to said electric motor and a plurality of blades which are provided
at said hub in a radial manner, wherein in said axial flow blower,
a negative pressure surface of a leading edge of each said blade,
comprised of a negative pressure surface and a positive pressure
surface, is provided with a plurality of triangle shape projections
which have vertexes along the leading edge, and the positive
pressure surface of the leading edge of each said blade is not
provided with said triangle shape projections but is a smooth
continuous surface.
Inventors: |
Ooya; Hideki; (Kariya,
JP) ; Kamiya; Masaru; (Kariya, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya-city |
|
JP |
|
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
49670496 |
Appl. No.: |
13/906401 |
Filed: |
May 31, 2013 |
Current U.S.
Class: |
417/410.1 ;
416/236R |
Current CPC
Class: |
F04D 29/326 20130101;
F05D 2240/303 20130101; F04D 29/681 20130101; F04D 29/384
20130101 |
Class at
Publication: |
417/410.1 ;
416/236.R |
International
Class: |
F04D 29/38 20060101
F04D029/38 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2012 |
JP |
2012-124252 |
Claims
1. An axial flow blower which is provided with an electric motor,
and a blower fan which has a hub which is attached to said electric
motor, and a plurality of blades which are provided at said hub in
a radial manner, wherein in said axial flow blower, a negative
pressure surface of a leading edge of each of said blades,
comprised of a negative pressure surface and a positive pressure
surface, is provided with a plurality of triangle shape projections
which have vertexes along the leading edge, and the positive
pressure surface of the leading edge of each of said blades is not
provided with said triangle shape projections but is a smooth
continuous surface.
2. The axial flow blower as set forth in claim 1, wherein said
triangle shape projections have peaks with slanted side faces.
3. The axial flow blower as set forth in claim 1, wherein said
triangle shape projections have peaks with bottom sides which are
changed in size as said triangle shape projections closer to an
outer circumference of said blower fan.
4. The axial flow blower as set forth in claim 1, wherein said
triangle shape projections have peaks with vertexes which are
changed in angle as said triangle shape projections closer to an
outer circumference of said blower fan.
5. The axial flow blower as set forth in claim 1, wherein said
triangle shape projections have peaks with center directions which
are changed as said triangle shape projections closer to an outer
circumference of said blower fan.
6. The axial flow blower as set forth in claim 1, wherein a blade
trailing edge of each said blades is provided in the negative
pressure surface and the positive pressure surface with a plurality
of triangle shape projections which have vertexes at the blade
trailing edge.
7. The axial flow blower which is provided with an electric motor
and a blower fan which has a hub which is attached to said electric
motor and a plurality of blades which are provided at said hub in a
radial manner, wherein in said axial flow blower, a leading edge of
each said blade blades, comprised of a negative pressure surface
and a positive pressure surface, is provided in the negative
pressure surface and the positive pressure surface with a plurality
of triangle shape projections which have vertexes along the leading
edge, and angles formed by valleys of said plurality of triangle
shape projections at said positive pressure surface are
respectively larger than angles formed by said valleys at said
negative pressure surface.
8. The axial flow blower as set forth in claim 1, wherein said
blower fan has backward curved blades or forward curved blades.
9. A blower fan which is provided with a hub which is attached to a
drive device and a plurality of blades which are provided at said
hub and have a negative pressure surface and a positive pressure
surface, wherein in said blower fan, a negative pressure surface of
a leading edge of each said blade has a first slanted side, which
is slanted with respect to the flow direction of the air flow, and
a second slanted side, which is slanted with respect to the flow
direction of the air flow, in a different direction from said first
slanted side and is provided with a plurality of projections which
project out into the upstream side of flow of the air flow, and
said positive pressure surface of a leading edge of each said blade
is not provided with said triangle shape projections but is a
smooth continuous surface.
Description
TECHNICAL FIELD
[0001] The present invention relates to an axial flow blower, more
particularly relates to a structure of a fan blade which achieves
both noise reduction and blowing performance.
DESCRIPTION OF THE RELATED ART
[0002] An axial flow blower is required to provide both blowing
performance and low noise. PTL1 discloses to provide a plurality of
triangle shape projections in a sawtooth manner (below, referred to
as "serrations") in a chord line direction of a leading edge of a
blade as a whole to try to reduce the noise of operation of the
blower fan 1. The positive pressure surface and the negative
pressure surface of a blade of the axial flow blower become as
shown in FIGS. 1A to 10. The serrations of the related art of PTL1
are formed so as to run from the negative pressure surface to the
positive pressure surface. For this reason, while the noise
reduction effect which serrations create is large, since the
serrations are present at the positive pressure surface side, they
constitute minus factors in maintaining the lift. Sometimes, the
inherent blowing performance of the case with no serrations cannot
be obtained.
CITATION LIST
Patent Literature
[0003] PTL1: Japanese Unexamined Patent Publication No.
2000-087898A
SUMMARY OF INVENTION
Technical Problem
[0004] The present invention, in view of the above problems,
provides a blower which aims at both a noise reduction effect and
the inherent blowing performance of a blade by the provision of a
plurality of triangle shape projections in the chord line direction
of a leading edge part of the blade as a whole at just the negative
pressure surface.
Solution to Problem
[0005] To solve the above problem, the aspect of the invention of
claim 1 provides an axial flow blower (10) which is provided with
an electric motor (300), and a blower fan (1) which has a hub (4)
which is attached to said electric motor (300), and a plurality of
blades (3) which are provided at said hub (4) in a radial manner,
wherein in said axial flow blower, a negative pressure surface of a
leading edge (6) of each said blade (3), comprised of a negative
pressure surface and a positive pressure surface, is provided with
a plurality of triangle shape projections which have vertexes along
the leading edge (6), and the positive pressure surface of the
leading edge (6) of each said blade (3) is not provided with said
triangle shape projections but is a smooth continuous surface.
[0006] To solve the above problem, the aspect of the invention of
claim 7 provides an axial flow blower (10) which is provided with
an electric motor (300) and a blower fan (1) which has a hub (4)
which is attached to said electric motor (300) and a plurality of
blades (3) which are provided at said hub (4) in a radial manner,
wherein in said axial flow blower, a leading edge (6) of each said
blade (3), comprised of a negative pressure surface and a positive
pressure surface, is provided in the negative pressure surface and
the positive pressure surface with a plurality of triangle shape
projections which have vertexes along the leading edge (6), and
angles (.phi.2) formed by valleys (3-2) of said plurality of
triangle shape projections at said positive pressure surface are
respectively larger than angles (.phi.1) formed by said valleys at
said negative pressure surface.
[0007] Note that the reference numerals given above are
illustrations showing the correspondence with specific means
described in the embodiments described later.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1A is an explanatory view for explaining a general
axial flow blower.
[0009] FIG. 1B is a cross-sectional view along the line A-A of FIG.
1A.
[0010] FIG. 1C is an explanatory view for explaining, a positive
pressure surface and a negative pressure surface of a blade of FIG.
1B etc.
[0011] FIG. 2 is a front schematic view of a first embodiment of
the present invention.
[0012] FIG. 3 is an example of the results of simulation which
analyzes the structure of flow around leading edge serrations.
[0013] FIG. 4 is an explanatory view of the results of simulation
of FIG. 3.
[0014] FIG. 5 is a cross-sectional view of a blade of the
simulation of FIG. 3.
[0015] FIG. 6 is a perspective view of a first embodiment of the
present invention.
[0016] FIG. 7 is an explanatory view of a first embodiment of the
present invention.
[0017] FIG. 8 is a perspective view of a second embodiment of the
present invention.
[0018] FIG. 9 is an explanatory view of a sixth embodiment of the
present invention.
DESCRIPTION OF EMBODIMENTS
[0019] Below, referring to the figures, embodiments of the present
invention will be explained. In the embodiments, parts of the same
configuration are assigned the same reference notations and the
explanations omitted. Referring to FIG. 2, the blower 10 is
comprised of a blower fan 1 arranged inside of a shroud 200. It is
a so-called electric blower which is driven to rotate by an
electric motor 300. The blower 10 is fastened to the engine side of
an automobile radiator by mounting parts 250 which are provided
near the four corners of the shroud 200 and blows cooling use air
to a core part of the radiator. The outer shape of the shroud 200
is a rectangular shape corresponding to a core part of a radiator.
At its substantial center, a ring shaped shroud ring part 210 which
encompasses the blower fan 1 by its outer circumference is formed.
This shroud ring part 210 is provided at the shroud 200 so as to be
positioned at the outside of the ring 2 of the blower fan 1 in the
radial direction. In the present embodiment, the ring 2 of the
blower fan 1 may also be omitted. The blower 10 and later explained
blades 3 of the present invention are not limited to automobile
radiator use and may also be applied for general industrial
use.
[0020] Between the shroud ring part 210 and the rectangular shape
outer circumference of the shroud 200, an air guide part 220 which
expands toward the upstream side of the blower fan 1 is formed. At
the center of the shroud ring part 210, a circular motor holding
part 230 is formed. This motor holding part 230 is supported by a
plurality of motor stays 240 which extend in a radial shape outward
in the radial direction and are connected to the shroud ring part
210. At the motor holding part 230, an electric motor 300 is
fastened. The shaft of the electric motor 300 and the hub 4 of the
blower fan 1 (see FIG. 7) are fastened together. The blower 10 is
configured by these blower fan 1, electric motor 300, etc. The hub
4 of the blower fan 1 is tubular in shape and is provided with a
plurality of blades 3 in a radial manner. The chord line C,
positive pressure surface, negative pressure surface, angle of
attack a, lift, etc. of a blade 3 are the same as the general
definitions such as shown in FIGS. LA to 1C.
[0021] First, at the start, the effects of serrations which form
the basis of the present invention will be explained. The
simulation of FIG. 3 is for the case of the blade cross-section of
FIG. 5 (blade cross-section of the present invention explained
later). FIG. 3 is a view of the leading edge seen from the top
position. The arrow marks (tangential velocity) which are shown in
FIG. 3 are projections of the speed vectors of the flows around the
serrations on the projection plane (S plane of FIG. 4) vertical to
the Y-Z plane. It will be seen that flows are formed so as to
circle in toward the top surfaces of the peaks from the valleys at
the two sides. At the serrations, first, small swirls occur at the
tips of the peaks. These grow to large swirls the further toward
the valleys. Further, behind the peaks, downward flows are formed.
Due to this, it is believed that the flow separation which
particularly easily occurs at the fast flow rate negative pressure
surface is pushed downward to the surface and flow separation is
reduced. Due to this, it is possible to ease the disturbances near
the blade surfaces and suppress pressure fluctuations at the blade
surfaces so as to create an effect leading to noise reduction.
First Embodiment
[0022] In the present embodiment, the effects of the
above-mentioned serrations are utilized while reducing the rotating
noise of the blower fan. The inherent objective of a blower fan,
that is, the blowing performance, is kept from being impaired so as
to realize both noise reduction and blowing performance (lift). As
shown in FIGS. 6 and 7, in the present embodiment, the triangle
shapes (serrations) which are provided at the leading edges are
provided at only the negative pressure surfaces. The positive
pressure surfaces are made the usual blade bottom surfaces, as
shown in the cross-sectional view along the line B-B of FIG. 7, so
as to maintain the inherent blowing performance (lift). That is,
the negative pressure surface of the leading edge 6 of each blade
3, comprised of a negative pressure surface and the positive
pressure surface, is provided with a plurality of triangle shape
projections which have vertexes along the leading edge 6. On the
other hand, the positive pressure surface of the leading edge 6 of
the blade 3 is not provided with triangle shape projections, but
forms a smooth continuous surface. The triangle shape projections
have first slanted sides 3a, which are slanted with respect to the
flow direction of the air flow, and second slanted sides 3b, which
are slanted with respect to the flow direction of the air flow, in
a different direction from the first slanted sides 3a. The triangle
shape projections are formed continuously.
[0023] As the effect created by the serrations, flow separation is
reduced near the blade surfaces of the negative pressure surfaces
and disturbances near the blade surfaces are eased. Further, by
keeping down pressure fluctuations at the blade surfaces, noise
reduction is realized. The present embodiment not only can achieve
both noise reduction and blowing performance (lift), but also can
perform blowing work more efficiently than even conventional blower
fans, so lower torque is realized and the power used becomes
smaller, so this leads to energy saving.
Second Embodiment
[0024] The second embodiment is characterized as follows. The side
surfaces 3-3 of the peaks 3-1 of the triangle shape projections are
slanted like the slopes of mountains. The side surfaces 3-3 of the
peaks 3-1, as shown in FIG. 8, are slanted, so that the angles
.phi.2' formed by the valleys at the bottom surfaces 3-4 of the
valleys between one peak 3-1 and another peak 3-1 becomes greater
than the angle .phi.1 formed by the valleys at the negative
pressure surface. The slanted surfaces may be flat or may be
curved. They may be provided at both side surfaces 3-3 of the peaks
3-1 or at single sides. The angles .phi.1 and .phi.2' formed by the
valleys are made angles at the planes vertical to the axial center
of the blower fan (same for later explained (.phi.2). In the
present embodiment, at the serrations, smooth swirls are formed.
These grow into larger swirls the further toward the valleys.
Further, at the rear of the peaks, downward flows are formed. These
push the flow separation downward and can reduce the flow
separation.
Third Embodiment
[0025] The sizes "a" of the bottom sides of the peaks 3-1, the
angles .psi. of the vertexes, and the center directions "O" of the
triangle shape projections (see FIG. 8) are changed as the
projections become closer to the outer circumference or ring 2 of
the blower fan 1. In the blower fan 1, sometimes distinctive, flows
are formed in the flow of air flow in the radial direction. If
dealing with the flows by suitably changing the sizes "a" of the
bottom sides of the peaks 3-1, the angles .psi. of the vertexes,
and, the center directions O, it is possible to reduce the flow
separation even more. As these distinctive flows, diagonal flows,
or, back flows from the outer circumference or ring 2 of the blower
fan 1 etc. may be mentioned. In the present embodiment, the peaks
3-1 of the triangle shape projections are modified for these flows
(turning center direction "O" in direction of air flow etc.) Due to
this, it is possible to control the flows so as to minimize the
noise which is generated due to the disturbance of the air
flow.
[0026] Further, in the case of an axial flow blower, the further to
the outer circumference side of the blower fan 1, the faster the
flow rate is. Sometimes it is effective to increase the size "a" of
the bottom side or reduce the angle .psi. of the vertex the further
to the outer diameter side of the blades. It is possible to control
the fast flow rate flow where separation easily occurs, by changing
the shapes of the peaks 3-1 of the triangle shape projections.
Fourth Embodiment
[0027] The fourth embodiment, while not shown, provides serrations
which run through the blade thickness at the trailing edge 7 of the
blade 3. This is an embodiment where, in the embodiments explained
above, the negative pressure surface to the positive pressure
surface of the trailing edge 7 of the blade 3 is provided with a
plurality of triangle shape projections along the trailing edge 7.
In addition to the effects of the embodiments explained up to here,
the disturbances in the back flow of the blades can be reduced, so
it is possible to obtain the effects of noise reduction, reduction
of the air flow, and prevention of the increase of the drive
torque.
Fifth Embodiment
[0028] The fifth embodiment is an embodiment in the case of
applying the embodiments which were explained above to a shape of
blade such as shown in FIG. 7, where the end at the outer
circumferential side is swept back from the direction of rotation,
that is, a backward curved blade (sweptback blade). Of course, the
invention may also be applied to a shape of blade where the end at
the outer circumferential side is swept forward from the direction
of rotation, that is, a forward curved blade (forward swept
blade).
Sixth Embodiment
[0029] In the sixth embodiment, the leading edge 6 of blade 3 in
the negative pressure surface and the positive pressure surface 3
is provided with a plurality of triangle shape projections which
have vertexes along the leading edge 6.
[0030] In this embodiment, the angles .phi.2 which are formed by
the valleys 3-2 of the plurality of triangle shape projections at
the positive pressure surface are all larger than the angles .phi.1
which are formed by the valleys of the negative pressure surface.
In this case as well, the positive pressure surface can maintain
the blowing performance (lift), compared with negative pressure
surface. When the angles .phi.2=180 degrees, the result becomes
included in the second embodiment. Further, when the angles .phi.2
are close to 180 degrees, it is possible to obtain substantially
the same effects as the second embodiment. Of course, if the angles
.phi.2 are larger than the angles .phi.1, the positive pressure
surface can maintain the blowing performance (lift) compared with
negative pressure surface.
EXPLANATION OF REFERENCE NUMBER
[0031] 1 blower fan [0032] 3 blade [0033] 4 hub [0034] 300 electric
motor
* * * * *