U.S. patent application number 14/404259 was filed with the patent office on 2015-06-04 for air blower.
The applicant listed for this patent is DENSO CORPORATION. Invention is credited to Masaru Kamiya, Hideki Ooya, Kenji Yoshida.
Application Number | 20150152875 14/404259 |
Document ID | / |
Family ID | 49673479 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150152875 |
Kind Code |
A1 |
Kamiya; Masaru ; et
al. |
June 4, 2015 |
AIR BLOWER
Abstract
An air blower is provided with a drive motor and an air blowing
fan which has a hub mounted to the drive motor and blades which are
provided to the hub. The air blower is characterized in that
serrations comprising triangle-shaped protrusions are provided to
the front edge of each of the blades so as to be arranged along the
front edge and in that the pitch, the height, or the direction of
the serrations is changed according to the flow of air at a radial
position on the air blowing fan.
Inventors: |
Kamiya; Masaru;
(Toyoake-shi, JP) ; Ooya; Hideki; (Toyoake-shi,
JP) ; Yoshida; Kenji; (Anjo-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION |
Kariya-city, Aichi-pref. |
|
JP |
|
|
Family ID: |
49673479 |
Appl. No.: |
14/404259 |
Filed: |
May 31, 2013 |
PCT Filed: |
May 31, 2013 |
PCT NO: |
PCT/JP2013/065282 |
371 Date: |
November 26, 2014 |
Current U.S.
Class: |
416/147 |
Current CPC
Class: |
F05D 2240/303 20130101;
F04D 29/667 20130101; F04D 29/326 20130101; F04D 19/002 20130101;
F04D 29/384 20130101; F04D 27/002 20130101; F04D 29/681
20130101 |
International
Class: |
F04D 27/00 20060101
F04D027/00; F04D 19/00 20060101 F04D019/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 31, 2012 |
JP |
2012-124250 |
Claims
1. A blower comprising a drive motor and a blower fan having a hub
which is attached to said drive motor, and a plurality of blades
which are provided at said hub, wherein said blades are provided at
their blade leading edge parts with serrations comprised of
pluralities of triangular shape projecting parts along the blade
leading edge parts and said serrations are changed in pitch,
height, or direction according to the flows of air at radial
direction positions of said blower fan.
2. The blower according to claim 1, wherein said serrations have a
pitch or height which becomes larger as the serrations are further
to the blade outside diameter side.
3. The blower according to claim 1, wherein said serrations have an
angle of vertices which becomes smaller as the serrations are
further to the blade outside diameter side.
4. The blower according to claim 1, wherein said serrations have a
direction in the circumferential direction of the blower fan.
5. The blower according to claim 1, wherein said serrations have a
direction in the direction of flow of air other than the
circumferential direction of the blower fan.
6. The blower according to claim 1, wherein said serrations have a
pitch, height, or direction made a magnitude or a direction
corresponding to a back flow at the blade end part.
7. The blower according to claim 1, wherein said blades have a
blade trailing edge part with serrations comprised of a plurality
of triangular shape projecting parts along the blade trailing edge
part.
8. The blower according to claim 7, wherein said serrations of said
blade trailing edge part have a pitch or height smaller than said
serrations of said blade leading edge part.
9. The blower according to claim 7, wherein said serrations of said
blade leading edge part and said serrations of said blade trailing
edge part are different in set position in radial direction
position of the blower fan.
10. A blower fan having a hub which adapts to be attached to a
drive unit, and a plurality of blades which are provided at said
hub, wherein each said blade has a first portion of a blade leading
edge part of said blade which has a first distance in the radial
direction from the center of rotation of said blade, and a second
portion of a blade leading edge part of said blade which has a
second distance in the radial direction from the center of rotation
of said blade, said blade leading edge part is provided with a
plurality of serrations which stick out to an upstream side of flow
of air, wherein said serrations have first slanted sides which are
slanted with respect to a direction of flow of air, and second
slanted sides which are slanted in a different direction from said
first slanted sides with respect to a direction of flow of air, and
at least one of a pitch, height, and direction of said projections
at said first portion differs from at least one of a pitch, height,
and direction of said projections at said second portion.
Description
TECHNICAL FIELD
[0001] The present invention relates to an axial flow blower,
centrifugal blower, diagonal flow blower, etc., more particularly
relates to a structure of a fan blade which can suppress
disturbances in the air flow and reduce noise.
BACKGROUND ART
[0002] Better blower performance and lower noise are being sought
from axial flow blowers etc. PLT 1 discloses providing a plurality
of triangular shape projections in a sawtooth manner (hereinafter
referred to as "serrations") in a chord line direction with an all
leading edge part of each blade to reduce the noise of rotation due
to the blower fan.
[0003] In general, the flow of air near a blade surface of a blower
greatly differs depending on the part. The further to the outer
circumference side in the radial direction of the blower fan the
blower fan is, the higher the flow rate is. Further, the direction
of the air flow at the outer circumference side of the blower fan,
with respect to the direction of rotation, greatly changes
depending on the design of the blade (forward curved blade or
backward curved blade). That is, in a forward curved blade (forward
swept wing), the flow becomes an axial flow which concentrates at
the blade center, while in a backward curved blade (sweptback
wing), the flows becomes a slanted flow which heads toward the
blade outer circumferential direction. Furthermore, at the blade
end part, a back flow also occurs from a positive pressure surface
to a negative pressure surface side. In such a prior art as PLT 1,
serrations which were provided with a blade could not sufficiently
suitably deal with changes in the flow of air depending on the
portion of the blade and a sufficient noise reduction effect
sometimes could not be obtained. Further, a drop in the air flow
was sometimes caused or the drive torque increased and a drop in
efficiency was caused.
CITATIONS LIST
Patent Literature
[0004] PLT 1: Japanese Unexamined Patent Publication No.
2000-087898
SUMMARY OF INVENTION
Technical Problem
[0005] The present invention, in consideration of the problem,
provides a blower which prevents a drop in the air flow while
effectively reducing the fan noise.
Solution to Problem
[0006] To solve the problem, an aspect of the invention of claim 1
provides a blower comprising a drive motor and a blower fan having
a hub which is attached to the drive motor, and a plurality of
blades which are provided at the hub, wherein the blades are
provided at their blade leading edge parts with serrations
comprised of pluralities of triangular shape projecting parts along
the blade leading edge parts and the serrations are changed in
pitch, height, or direction according to the flows of air at radial
direction positions of the blower fan.
[0007] To solve the problem, an aspect of the invention of claim 10
provides a blower fan having a hub which adapts to be attached to a
drive unit, and a plurality of blades which are provided at said
hub, wherein
each said blade has a first portion of a blade leading edge part of
said blade which has a first distance in the radial direction from
the center of rotation of said blade, and a second portion of a
blade leading edge part of said blade which has a second distance
in the radial direction from the center of rotation of said blade,
said blade leading edge part is provided with a plurality of
serrations which stick out to an upstream side of flow of air,
wherein said serrations have first slanted sides which are slanted
with respect to a direction of flow of air, and second slanted
sides which are slanted in a different direction from said first
slanted sides with respect to a direction of flow of air, and at
least one of a pitch, height, and direction of said projections at
said first portion differs from at least one of a pitch, height,
and direction of said projections at said second portion. Note that
the parenthesized reference notations show the correspondence with
specific examples which are described in the later mentioned
embodiments.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a front schematic view of a first embodiment of
the present invention.
[0009] FIG. 2 is a schematic view of a blade of a first embodiment
of the present invention.
[0010] FIG. 3 is a view of one example of the results of simulation
analyzing the structure of the flow around leading edge serrations
by CFD (computational fluid dynamics).
[0011] FIG. 4 is an explanatory view of the results of simulation
of FIG. 3.
[0012] FIG. 5 is a cross-sectional view of a blade of the
simulation of FIG. 3.
[0013] FIG. 6A is an explanatory view for explaining a general
axial flow blower.
[0014] FIG. 6B is a cross-sectional view developed along the line
A-A of FIG. 6A.
[0015] FIG. 6C is an explanatory view for explaining a positive
pressure surface and a negative pressure surface of a blade of FIG.
6B.
[0016] FIG. 7 is a schematic view of a blade of a second embodiment
of the present invention.
[0017] FIG. 8 is a schematic view of a blade of a third embodiment
of the present invention.
[0018] FIG. 9 is a schematic view of a blade of a fourth embodiment
of the present invention.
[0019] FIG. 10 is a schematic view of a blade of a fifth embodiment
of the present invention.
[0020] FIG. 11 is a schematic view of a blade of a sixth embodiment
of the present invention.
[0021] FIG. 12 is a schematic view of a blade of a seventh
embodiment of the present invention.
[0022] FIG. 13 is a schematic view of a blade of an eighth
embodiment of the present invention.
[0023] FIG. 14 is a schematic view of a blade of a ninth embodiment
of the present invention.
DESCRIPTION OF EMBODIMENTS
[0024] Below, referring to the figures, embodiments of the present
invention will be explained. In the embodiments, parts configured
the same will be assigned the same reference notations and
explanations will be omitted.
First Embodiment
[0025] Referring to FIG. 1, a blower 10 is a so-called electric
blower comprising a blower fan 1 which is placed in a shroud 200
and which is driven to rotate by a drive motor (electric motor)
300. The blower 10 is fastened to an engine side of an automobile
radiator by mounts 250 which are provided near the four corners of
the shroud 200 and blows air for cooling use to the core part of
the radiator. The outside shape of the shroud 200 forms a
rectangular shape corresponding to the core part of the radiator.
At the approximate center, a ring-shaped shroud ring part 210 is
formed so as to encircle the blower fan 1 by its outer
circumference. 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. There may also be no ring 2
of the blower fan 1 in the present embodiment. The blower 10 and
the later explained blades 3 of the present invention are not
limited to use for an automobile radiator. They are may be used for
general industrial use. The explanation will mainly be given for an
axial flow blower, but similar effects can be obtained even for a
centrifugal blower, diagonal flow blower, and cross-flow blower.
The drive motor 300 is not necessarily limited to an electric
motor.
[0026] Between the shroud ring part 210 and the rectangular shape
outer circumference part of the shroud 200, an air conduit 220 is
formed which expands toward the upstream side of air of the blower
fan 1. 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 radiately
to the outside 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. 2) are fastened. The blower 10
comprises this blower fan 1, electric motor 300, etc. The hub 4 of
the blower fan 1 is cylindrical in shape and is provided with a
plurality of blades 3 in the radial direction.
[0027] Parameters of the blades 3 such as the chord line C,
positive pressure surface, negative pressure surface, angle of
attack a, lift, etc. are the same as the general definitions such
as shown in FIGS. 6A to 6C. Further, a blade shape where the blade
end part at the outer circumference side is curved backward in the
direction of rotation of the blower fan 1 will be called a
"backward curved blade", while a blade shape where the blade end
part at the outer circumference side is curved forward in the
direction of rotation of the blower fan 1 will be called a "forward
curved blade". At the blade leading edge part of the blade 3, a
plurality of serrations (triangular shape projecting parts) are
formed. The serrations have first slanted sides 3a which are
slanted with respect to the direction of flow of air and second
slanted sides 3b which are slanted in a different direction from
the first slanted sides 3a with respect to the direction of flow of
air (see FIG. 7). In the triangular shape projecting parts which
form the serrations, here, the bottom side of the triangular shape
projecting part will be called the "pitch p" of the serrations
(triangular shape projecting parts), the line segment bisecting the
vertex a of the triangular shape projecting part will be called the
"direction" of the serrations (triangular shape projecting parts),
and the distance of the bisecting line segment of the vertex to the
bottom side will be called the "height h" of the serrations
(triangular shape projecting parts). The larger "size" of the
serrations (triangular shape projecting parts) indicates the larger
of the pitch or height of the serrations. The vertexes a of the
triangular shape projecting parts are called vertexes a of the
serrations. In the case where the sides of the triangular shapes
are curved, the shapes are generally based on these.
[0028] First, to start, the effects of the serrations which form
the basis of the present invention will be explained. The
simulation of FIG. 3 is the case where the triangular shape
projecting parts of the serrations are the same shapes in the
direction of the blade leading edge. FIG. 3 is a view of a blade
leading edge as seen from an upper position. The arrow marks which
are shown in FIG. 3 show projections of the tangential velocity of
the flows around the serrations on the projection plane of the X-Z
plane (S plane of FIG. 4). A flow from the valley parts at the two
sides to the top surface of a peak part can be seen as occurring.
At the serrations, first, at the tip parts of the peaks, small
vortexes occur. These grow to large vortexes further toward the
valleys. Further, backward the peaks, it is believed that downward
flows occurred by the vortexes, press down the flow separation,
which particularly easily occurs at the negative pressure surface
with the large flow rate, and therefore reduce the flow separation.
Due to this, the disturbances near the blade surface are eased and
the fluctuation of pressure at the blade surface is suppressed, so
it becomes possible to obtain an effect leading to lower noise.
[0029] The first embodiment of the present invention is an
embodiment changing the pitch, height, or direction of the
serrations according to the flow of air at the radial direction
position of the blower fan 1, in order to utilize the above basic
effect of the serrations. That is, the first embodiment differs in
at least one of the pitch, height, and direction of serrations in
the first portion and second portion which are different in
distance in the radial direction of the blower fan from the center
Q of rotation of the blade 3. As one example of the first portion
and second portion of the blade 3, parts differing in the flow rate
of air (flow rates of FIGS. 7 and 8) and directions of flow etc.
may be mentioned. However the invention is not limited to these
portions, but portions of any two locations along the blade 3. The
flow of air near the blade surfaces of the blower greatly differ
depending on the portion. The nearer to the outer circumference
side in the radial direction of the blower fan the portion of the
blade is, the higher the flow rate is. Further, at a forward curved
blade, the flow becomes an axial flow which concentrates at the
blade center, while at a backward curved blade, the flow becomes a
diagonal flow which heads toward the outer circumferential
direction of the blade. Furthermore, at the blade outer end part, a
back flow arises from the positive pressure surface to the negative
pressure surface. Changing the pitch, height, or direction of
serrations in accordance with the flow of air at radial direction
positions of the blower fan 1 (at least two locations) is extremely
important in reducing the flow separation. Due to this, the basic
effect of the serrations is exhibited, disturbances near the blade
surfaces are eased, and pressure fluctuations at the blade surfaces
are suppressed, so it becomes possible to obtain an effect leading
to lower noise.
[0030] The first embodiment is a fan which is characterized by
providing flow control shapes which minimize the noise which is
produced due to disturbance of the air at different positions of
the blades. Due to the flow control shapes, the effect is obtained
of both noise reduction and prevention of a drop in the air flow
and increase of the drive torque. The blades have serration shape
(sawtooth teeth) portions. The serration shapes are changed
according to the flow of air. According to this, it is possible to
suitably set the serration shapes at the individual portions which
differ in direction of air flow and flow rate, so it is possible to
realize the effect of both noise reduction and the prevention of
both a drop of the air flow and increase of the drive torque.
Second and Third Embodiments
[0031] The second and third embodiments are embodiments
corresponding to the case where the air near a blade surface of the
blower flows in the circumferential direction of the blower fan.
The second embodiment, as shown in FIG. 7, is characterized in that
the further to the blade outside diameter side the blade is, the
larger the sizes of the serrations are made. The serrations are
directed toward the circumferential direction of the blower fan.
According to this, the size of the serrations is increased at the
portion with a large flow rate at the blade outer circumference
side, and the whirled air flow which is formed at the serrations,
becomes weaker at a portion further toward the blade inside
circumference side and becomes stronger at a portion further toward
the blade outer circumference side. Due to this, at the flow with a
high flow rate where flow separation would easily occur, it is
possible to form a downward flow toward the blade surface and
reduce the flow separation to obtain the effect of both noise
reduction and the prevention of a drop in the air flow and increase
of the drive torque at the blade as a whole.
[0032] The third embodiment, as seen in FIG. 8, is characterized in
that the further to the blade outside diameter side the blade is,
the more acute the vertices a of the serrations is. According to
this, the serration angle is made acute at the portion of the large
flow rate at the blade outer circumference side, and the whirled
air flow which is formed at the serrations becomes weaker at a
portion further to the blade inside circumference side and becomes
stronger at a portion further to the blade outer circumference
side. Due to this, at the flow with a high flow rate where flow
separation would easily occur, it is possible to strengthen the
downward flow at the blade surfaces formed at the serration valley
parts in order to achieve both noise reduction, and prevention of
both a drop in air flow and increase in drive torque in the blade
as a whole. The invention is not limited to the case of making the
pitch p of the serrations constant and increasing the height h of
the serrations to make the angle acute. It is also possible to make
the serration angle acute, regardless of the length of the bottom
sides of the triangular shaped projections, at the portions with a
large flow rate at the blade outer circumference side.
Fourth Embodiment
[0033] The fourth embodiment, as seen in FIG. 9, is characterized
in that the blade trailing edge 7 is also provided with serrations
and in that the blade leading edge 6 and blade trailing edge 7 are
changed in serration shapes. When the blade trailing edge 7 is
provided with serrations, since the flow at the high pressure blade
positive pressure surface and the flow at the low pressure blade
negative pressure surface are mixed near the blade trailing edge,
the flows of the two surfaces gradually cross due to the
serrations, so it is possible to suppress the disturbances in the
flow of air of the blade trailing edge. The blade leading edge 6
and the blade trailing edge 7 may be suitably set with serration
shapes. If the blade trailing edge 7 is made smaller in size of
serrations compared with the blade leading edge 6, the serrations
at the blade leading edge side, which are provided for suppressing
flow separation, can be made larger so as to form a radiated flow.
On the other hand, the serrations at the blade trailing edge side,
which are provided for suppressing disturbances of the air flow,
can be made smaller so as to make the flows at the positive and
negative pressure surfaces gradually cross. Therefore, the effect
is obtained of both noise reduction, and the prevention of both a
drop in the air flow and increase of the drive torque. It is also
possible to change the range of provision of serrations between the
blade trailing edge and the blade leading edge, and possible to
provide serrations at only suitable positions of the blade leading
edge 6 and blade trailing edge 7.
[0034] In the following fifth and sixth embodiments, embodiments
are explained which correspond to the case where the flow of air
near the blade surfaces of the blower is a diagonal flow slanted
with respect to the circumferential direction of the blower
fan.
Fifth and Sixth Embodiments
[0035] The fifth embodiment, as shown in FIG. 10, is an embodiment
corresponding to the case where the flow of air near the blade
surfaces of the blower is a diagonal flow. The fifth embodiment
matches the direction of the serrations of the blade leading edge
with the direction of diagonal flow. The sixth embodiment, as shown
in FIG. 11, is characterized by changing the range of provision of
serrations between the blade trailing edge 7 and the blade leading
edge 6. For example, when the air flow becomes a diagonal flow such
as with a backward curved blade, the air flows on the blade surface
in the direction to the outer circumference, from the blade leading
edge 6 toward the blade trailing edge 7. At this time, at the blade
leading edge side where there is interference with the air flow at
all positions of the blade, serrations are provided over a wide
range, while at the blade trailing edge side, serrations are
provided at only the parts with remarkable diagonal flow, so noise
reduction and prevention of a drop of air flow and increase of
drive torque can both be realized.
[0036] The following seventh and eighth embodiments are embodiments
corresponding to the case where the flow of air near the blade
surface of the blower is a back flow from the positive pressure
surface of the blade end part to the negative pressure surface
side.
Seventh and Eighth Embodiments
[0037] The seventh embodiment, as shown in FIG. 12, is
characterized by making the serration shapes of the blade end part
smaller. According to this, the serration shapes are made smaller
at the blade end part where the disturbance of the air flow due to
the back flow is large, so the swirl of the air flow formed at the
serrations is subdivided. Due to this, the disturbance of the air
flow at the blade end part can be reduced, so the effect is
obtained of noise reduction, and prevention of both a drop in air
flow and increase of drive torque. The eighth embodiment, as shown
in FIG. 13, is characterized by making the serration shapes of the
blade end part at the blade trailing edge 7 smaller. Operational
effects similar to the seventh embodiment are obtained.
Ninth Embodiment
[0038] The ninth embodiment, as shown in FIG. 14, is an embodiment
which makes the direction of the serrations of the blade leading
edge 6 match the direction of diagonal flow and makes the serration
shapes of the blade end part match the air flow due to the back
flow, so as to deal with the flow of air near the blade surface of
the blower. The ninth embodiment is included in the first
embodiment. According to this, it is possible to set the direction
of the serrations to match the direction of flow, so the effect is
obtained of noise reduction, and prevention of both a drop in air
flow and increase in drive torque. Of course, combinations of the
fifth and sixth embodiments for the diagonal flow and the seventh
and eighth embodiments for the back flow is included in the ninth
embodiment. The present invention was described with reference to
specific embodiments selected in accordance with the purpose of
illustration, but it is clear that a person skilled in the art
could conceive of numerous modifications without departing from the
basic concept of the present invention and scope of disclosure of
the same.
REFERENCE SIGNS LIST
[0039] 1 blower fan [0040] 3 blade [0041] 4 hub [0042] 300 drive
motor
* * * * *