U.S. patent application number 14/990265 was filed with the patent office on 2016-10-06 for impeller and blower.
The applicant listed for this patent is Nidec Corporation. Invention is credited to Ryosuke Hayamitsu.
Application Number | 20160290352 14/990265 |
Document ID | / |
Family ID | 55650024 |
Filed Date | 2016-10-06 |
United States Patent
Application |
20160290352 |
Kind Code |
A1 |
Hayamitsu; Ryosuke |
October 6, 2016 |
IMPELLER AND BLOWER
Abstract
An impeller is fixed to a shaft concentric with a center axis
extending in an up-down direction and is rotatable about the center
axis together with the shaft. The impeller includes a boss portion
which is fixed to the shaft and extends in an axial direction, an
impeller body portion, a plurality of blade portions arranged on an
upper surface of the impeller body portion, and a rib portion
arranged on a lower surface of the impeller body portion. The
impeller body portion extends downward from an upper end of the
boss portion while being widened in a radial direction, and is
arranged to surround the boss portion in a circumferential
direction. When viewed in the axial direction, a front side end
portion of the rib portion is curved toward a rotation direction
back side as the rib portion extends from a radial inner side
toward a radial outer side.
Inventors: |
Hayamitsu; Ryosuke; (Kyoto,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nidec Corporation |
Kyoto |
|
JP |
|
|
Family ID: |
55650024 |
Appl. No.: |
14/990265 |
Filed: |
January 7, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/4233 20130101;
F04D 25/02 20130101; F04D 25/06 20130101; F04D 17/16 20130101; F04D
29/263 20130101; F04D 29/667 20130101; F04D 29/053 20130101; F04D
29/281 20130101 |
International
Class: |
F04D 29/28 20060101
F04D029/28; F04D 29/42 20060101 F04D029/42; F04D 29/053 20060101
F04D029/053; F04D 29/26 20060101 F04D029/26; F04D 17/16 20060101
F04D017/16; F04D 25/02 20060101 F04D025/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2015 |
JP |
2015-070177 |
Claims
1. An impeller which is directly or indirectly fixed to a shaft
concentric with a center axis extending in an up-down direction and
arranged to rotate about the center axis together with the shaft,
the impeller comprising: a boss portion which is fixed to the shaft
and arranged to extend in an axial direction; an impeller body
portion extending downward from an upper end of the boss portion
while being widened in a radial direction, the impeller body
portion arranged to surround the boss portion in a circumferential
direction; a plurality of blade portions arranged on an upper
surface of the impeller body portion; and a rib portion arranged on
a lower surface of the impeller body portion, wherein when viewed
in the axial direction, a front side end portion as a rotation
direction front side end portion of the rib portion is curved
toward a rotation direction back side as the rib portion extends
from a radial inner side toward a radial outer side.
2. The impeller of claim 1, wherein the rib portion is connected to
the boss portion.
3. The impeller of claim 1, wherein the rib portion includes a
plurality of rib portions, and the number of the rib portions
differs from the number of the blade portions.
4. The impeller of claim 1, wherein a radial outer end of the rib
portion is arranged at a radial outer edge of the impeller body
portion.
5. The impeller of claim 1, wherein when viewed in the axial
direction, a back side end portion as a rotation direction back
side end portion of the rib portion is curved toward the rotation
direction back side as the rib portion extends from the radial
inner side toward the radial outer side.
6. The impeller of claim 5, wherein a dimension between the front
side end portion and the back side end portion of the rib portion
is substantially uniform.
7. The impeller of claim 1, wherein when viewed in the axial
direction, a back side end portion as a rotation direction back
side end portion of the rib portion has a straight shape.
8. The impeller of claim 1, wherein when viewed in the axial
direction, the rib portion intersects one of the blade
portions.
9. The impeller of claim 1, wherein when viewed in the axial
direction, the blade portions are curved toward the rotation
direction back side as the blade portions extend from the radial
inner side toward the radial outer side.
10. The impeller of claim 9, wherein a curvature of the rib portion
differs from a curvature of each of the blade portions.
11. The impeller of claim 1, wherein an axial dimension of the rib
portion is one half or more of an axial distance between a
position, in which the impeller body portion and the boss portion
are connected to each other, and a lower end of the impeller body
portion.
12. The impeller of claim 11, wherein the axial dimension of the
rib portion is equal to the axial distance between the position, in
which the impeller body portion and the boss portion are connected
to each other, and the lower end of the impeller body portion.
13. The impeller of claim 1, wherein the rib portion includes a
plurality of rib portions uniformly arranged along the
circumferential direction.
14. A blower comprising: the impeller of claim 1; a motor provided
with the shaft and arranged to rotate the impeller about the center
axis; and a housing arranged to accommodate the impeller.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present disclosure relates to an impeller and a
blower.
[0003] 2. Description of the Related Art
[0004] In the related art, there is available an impeller for a
blower, which is molded with a resin. In this case, the interior of
a hub portion is formed into a cavity, thereby suppressing
generation of distortion, i.e., a so-called sink mark, which may be
generated when molding the impeller with a resin.
[0005] If the interior of the hub portion is formed into a cavity,
the thickness of the hub portion becomes thin. For that reason,
there is a possibility that the strength of the hub portion is
reduced and the hub portion is deformed during rotation. In order
to prevent deformation of the hub portion, reinforcing ribs are
provided in the cavity of the hub portion.
[0006] In a blower, if the impeller having the reinforcing ribs is
rotated, there is a possibility that an air enters the cavity of
the hub portion and a turbulent flow is generated between the
reinforcing ribs of the cavity. Thus, the pressure of an air
applied to the impeller increases and the shaft power for rotating
the impeller becomes larger. This may reduce the blowing efficiency
of the impeller.
SUMMARY OF THE INVENTION
[0007] In one aspect of the present disclosure, there is provided
an impeller which is directly or indirectly fixed to a shaft
concentric with a center axis extending in an up-down direction and
arranged to rotate about the center axis together with the shaft.
The impeller includes: a boss portion which is fixed to the shaft
and arranged to extend in an axial direction; an impeller body
portion; a plurality of blade portions arranged on an upper surface
of the impeller body portion; and a rib portion arranged on a lower
surface of the impeller body portion. The impeller body portion
extends downward from an upper end of the boss portion while being
widened in a radial direction. The impeller body portion is
arranged to surround the boss portion in a circumferential
direction. When viewed in the axial direction, a front side end
portion as a rotation direction front side end portion of the rib
portion is curved toward a rotation direction back side as the rib
portion extends from a radial inner side toward a radial outer
side.
[0008] The above and other elements, features, steps,
characteristics and advantages of the present disclosure will
become more apparent from the following detailed description of the
preferred embodiments made with reference to the attached drawings.
The above and other elements, features, steps, characteristics and
advantages of the present invention will become more apparent from
the following detailed description of the preferred embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view illustrating a centrifugal fan
according to one preferred embodiment.
[0010] FIG. 2 is an exploded perspective view illustrating the
centrifugal fan according to one preferred embodiment.
[0011] FIG. 3 is a sectional view taken along line III-III in FIG.
1, illustrating the centrifugal fan according to one preferred
embodiment.
[0012] FIG. 4 is a perspective view illustrating an impeller
according to one preferred embodiment.
[0013] FIG. 5 is a bottom view illustrating the impeller according
to one preferred embodiment.
[0014] FIG. 6 is a bottom view illustrating an impeller according
to another example of one preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] An impeller and a blower according to one preferred
embodiment of the present disclosure will now be described with
reference to the drawings. In the preferred embodiment described
below, descriptions will be made on a centrifugal fan as one
example of a blower.
[0016] The scope of the present disclosure is not limited to the
preferred embodiment described below but may be arbitrarily changed
without departing from the scope of the technical idea of the
present disclosure. In the drawings referred to below, for the sake
of making individual configurations easily understandable,
individual structures are sometimes shown in the reduced scale and
number differing from those of actual structures.
[0017] In the drawings, an XYZ coordinate system is appropriately
shown as a three-dimensional rectangular coordinate system. In the
XYZ coordinate system, the Z-axis direction is a direction parallel
to the axial direction of a center axis J illustrated in FIG. 1.
The X-axis direction is a direction orthogonal to the Z-axis
direction and orthogonal to an exhaust port 62 illustrated in FIG.
1. The Y-axis direction is a direction orthogonal to both the
X-axis direction and the Z-axis direction.
[0018] In the following description, the extension direction of the
center axis J (the Z-axis direction is an up-down direction. The
positive side (+Z side) in the Z-axis direction will be referred to
as an "upper side". The negative side (-Z side) in the Z-axis
direction will be referred to as a "lower side". The terms "up-down
direction", "upper side" and "lower side" are used merely for the
purpose of descriptions and are not intended to limit the actual
positional relationships or the actual directions. Unless
specifically mentioned otherwise, the direction (the Z-axis
direction) parallel to the center axis J will be merely referred to
as an "axial direction". The radius direction extending from the
center axis J will be merely referred to as a "radial direction".
The circumference direction about the center axis J (.theta..sub.Z
direction), namely the direction extending around the center axis
J, will be merely referred to as a "circumferential direction".
[0019] In the subject specification, the phrase "extending in the
axial direction" includes not only a case where something extends
strictly in the axial direction but also a case where something
extends in a direction inclined at an angle of less than about 45
degrees with respect to the axial direction. In the subject
specification, the phrase "extending in the radial direction"
includes not only a case where something extends strictly in the
radial direction, namely in the direction perpendicular to the
axial direction but also a case where something extends in a
direction inclined at an angle of less than 45 degrees with respect
to the radial direction.
[0020] FIG. 1 is a perspective view of a centrifugal fan 10
according to one preferred embodiment. FIG. 2 is an exploded
perspective view of the centrifugal fan 10 according to one
preferred embodiment. FIG. 3 is a sectional view of the centrifugal
fan taken along line III-III in FIG. 1. FIG. 3 is a sectional view
of the centrifugal fan 10 which is viewed in the direction
orthogonal to an exhaust port 62 (in the X-axis direction).
[0021] The centrifugal fan 10 is a blower. As illustrated in FIGS.
1 to 3, the centrifugal fan 10 preferably includes a housing 20, an
impeller 30 and a motor 40.
[0022] As illustrated in FIG. 3, the motor 40 is accommodated
within the housing 20. The motor 40 is arranged radially inward of
a motor cover portion 27 which will be described later. The motor
40 preferably includes a shaft 41 which is concentric with the
center axis J extending in the up-down direction. The upper end
portion of the shaft 41 protrudes toward the upper side of a motor
cover portion 27 through an output shaft hole 27a which will be
described later.
[0023] The motor 40 is disposed below the impeller 30. The motor 40
rotates the impeller 30 about the center axis J. In the present
preferred embodiment, the motor 40 rotates the impeller 30
counterclockwise (in the +.theta..sub.Z direction) when viewed from
the upper side toward the lower side.
[0024] In the following descriptions, there may be a case where the
counterclockwise forward side (+.theta..sub.Z side) when viewed
from the upper side toward the lower side is referred to as a
"rotation direction front side" and the clockwise (-.theta..sub.Z)
forward side (-.theta..sub.Z side) when viewed from the upper side
toward the lower side is referred to as a "rotation direction back
side".
[0025] The housing 20 preferably includes an upper housing 21 and a
lower housing 22. That is to say, the housing 20 is configured by
interconnecting two separate members. The housing 20 accommodates
the impeller 30 and the motor 40.
[0026] The upper housing 21 accommodates the impeller 30 at the
radial inner side thereof. The upper housing 21 preferably includes
an upper housing cover portion 23 and an upper housing wall portion
24.
[0027] The upper housing cover portion 23 is arranged above the
impeller 30. That is to say, the upper housing cover portion
overlaps with the impeller 30 in the axial direction. The upper
housing cover portion 23 includes the intake port 61. The intake
port 61 axially extends through the upper housing cover portion
23.
[0028] The upper housing cover portion 23 preferably includes a
cover inner edge portion 23a extending downward from the inner edge
of the intake port 61. The cover inner edge portion 23a has a
tubular shape. The lower end of the cover inner edge portion 23a is
arranged radially inward of an inner edge 33a of the shroud portion
33. The intake port 61 communicates with the interior of the
impeller 30 through the inside of the cover inner edge portion
23a.
[0029] The upper housing cover portion 23 is radially widened along
the shape of the below-mentioned shroud portion 33 of the impeller
30. The upper housing cover portion 23 is shaped to extend downward
and radially outward. In other words, the upper housing cover
portion 23 preferably includes a curved surface or a slant surface
inclined with respect to the center axis J.
[0030] The upper housing wall portion 24 is connected to the lower
end of the upper housing cover portion 23. The upper housing wall
portion 24 is arranged radially outward of the impeller 30. The
upper housing wall portion 24 surrounds the impeller 30 in the
circumferential direction.
[0031] The lower housing 22 is attached to the lower side of the
upper housing 21. The lower housing 22 preferably includes a motor
cover portion 27, a lower housing bottom portion 28 and a lower
housing wall portion 26.
[0032] The motor cover portion 27 has a roofed tubular shape opened
downward. The motor 40 is disposed radially inward of the motor
cover portion 27. The motor cover portion 27 covers the motor 40.
The motor cover portion 27 has an output shaft hole 27a axially
extending through a cover region of the motor cover portion 27.
[0033] The impeller 30 is arranged above the motor cover portion
27. The lower housing bottom portion 28 extends radially outward
from the lower end of the motor cover portion 27. The lower housing
wall portion 26 extends upward from the radial outer end of the
lower housing bottom portion 28. The axial position of the upper
end of the lower housing wall portion 26 is the same as the axial
position of the upper surface of the motor cover portion 27.
[0034] The housing 20 preferably includes an intake port 61, a flow
path 50 and an exhaust port 62. The intake port 61 is a hole opened
upward and arranged to bring the outside and inside of the housing
20 into communication with each other. The intake port 61 is
arranged above the impeller 30. As illustrated in FIGS. 1 and 2,
when seen in a plan view, the edge of the intake port 61 has a
circular shape centered at the center axis J. The plan-view shape
of the edge of the intake port 61 is not limited to the circular
shape and is not particularly limited.
[0035] As illustrated in FIG. 3, the flow path 50 is provided
within the housing 20. The flow path 50 interconnects the intake
port 61 and the exhaust port 62. The flow path 50 has, e.g., a
scroll shape or substantially scroll shape. The flow path 50
preferably includes an upper flow path 51 and a lower flow path 52.
That is to say, the upper flow path 51 and the lower flow path 52
have, e.g., a scroll shape or substantially scroll shape.
[0036] As used herein, the term "scroll shape" refers to a shape in
which the radial dimension of the flow path grows larger as the
flow path extends in the circumferential direction. The expression
"the flow path has a scroll shape" includes a case where at least
one of the upper flow path and the lower flow path has a scroll
shape. That is to say, the expression "the flow path has a scroll
shape" includes a case where only the upper flow path has a scroll
shape, a case where only the lower flow path has a scroll shape and
a case where both the upper flow path and the lower flow path have
a scroll shape.
[0037] The upper flow path 51 and the lower flow path 52 are
disposed along the axial direction. The lower flow path 52 is
arranged below the upper flow path 51. The lower flow path 52 is
connected to the upper flow path 51. In the present preferred
embodiment, the boundary between the upper flow path 51 and the
lower flow path 52 is the boundary between the upper housing 21 and
the lower housing 22.
[0038] In the present preferred embodiment, the entirety of the
upper flow path 51 is arranged within the upper housing 21. That is
to say, the upper housing 21 preferably include the entirety of the
upper flow path 51. At least a portion of the upper flow path 51 is
arranged between the upper wall portion inner circumferential
surface 24a and the impeller 30 in the radial direction.
[0039] While not shown in the drawings, the upper flow path has an
annular shape or substantially annular shape. The upper flow path
51 extends along the housing inner circumferential surface 20a. The
air introduced into the upper flow path 51 from the impeller 30
flows through the upper flow path 51 in the same direction as the
rotation direction of the impeller 30 (in the +.theta..sub.Z
direction). The entirety of the upper flow path 51 is opened
downward. A part of the air flowing through the upper flow path 51
is introduced into the lower flow path 52 until the air reaches the
exhaust port 62.
[0040] As illustrated in FIG. 2, the entirety of the lower flow
path 52 is arranged inside the lower housing 22. That is to say,
the lower housing 22 preferably includes the entirety of the lower
flow path 52. In other words, the lower flow path 52 is arranged
between the outer circumferential surface of the motor cover
portion 27 and the inner circumferential surface of the housing
20.
[0041] The lower flow path 52 extends along the inner
circumferential surface of the housing 20. The air introduced from
the upper flow path 51 into the lower flow path 52 flows through
the lower flow path 52 in the same direction as the rotation
direction of the impeller 30 (in the -.theta..sub.Z direction). One
circumferential end (the +.theta..sub.Z side end) of the lower flow
path 52 is opened toward the exhaust port 62. The other
circumferential end (the -.theta..sub.Z side end) of the lower flow
path 52 is closed with respect to the exhaust port 62.
[0042] In the case of closing one circumferential end of the lower
flow path, it is preferable that one end of the lower flow path is
closed in the circumferential direction. That is to say, even when
closing one circumferential end of the lower flow path, one
circumferential end of the lower flow path may be opened
upward.
[0043] The exhaust port 62 is arranged radially outward of the
impeller 30. In the present preferred embodiment, the exhaust port
62 is opened in the direction (X-axis direction) orthogonal to the
axial direction. As illustrated in FIG. 1, the exhaust port 62 is
defined by connecting an upper housing 21 and a lower housing 22
which will be described later. The exhaust port 62 is connected to
the upper flow path 51 and the lower flow path 52.
[0044] In FIG. 3, the airflow is indicated by thick arrows. As
illustrated in FIG. 3, if the motor 40 rotates the impeller 30, an
air is introduced into the housing 20 through the intake port 61.
The air introduced into the housing 20 is blown toward the radial
outer side of the impeller 30 through the interior of the impeller
30, namely through the gap between the shroud portion 33 and the
impeller body portion 31 which will be described later. The air
blown radially outward from the impeller 30 is moved through the
upper flow path 51 and the lower flow path 52 and is discharged to
the outside of the housing 20 from the exhaust port 62.
[0045] The impeller 30 is disposed above the motor 40. The impeller
30 is fixed to the upper end portion of the shaft 41. Thus, the
impeller 30 is rotatable (in the .+-..theta..sub.Z directions)
about the center axis J together with the shaft 41.
[0046] FIG. 4 is a perspective view illustrating the impeller 30.
FIG. 5 is a bottom view illustrating the impeller 30. In the
subject specification, the term "bottom view" refers to a view seen
from the lower side toward the upper side.
[0047] As illustrated in FIGS. 2, 4 and 5, the impeller 30
preferably includes a boss portion 34, an impeller body portion 31,
blade portions 32, a shroud portion 33 and rib portions 35. In the
present preferred embodiment, the impeller 30 is a single member.
In the present preferred embodiment, the impeller 30 is made of a
resin. The impeller 30 may be made of other materials.
[0048] As illustrated in FIG. 3, the boss portion 34 extends in the
axial direction. The boss portion 34 has a fitting hole 34a opened
downward. The upper end portion of the shaft 41 is fitted to the
fitting hole 34a. Thus, the boss portion 34 is fixed to the shaft
41. That is to say, the impeller 30 is directly fixed to the shaft
41 in the boss portion 34.
[0049] The impeller body portion 31 extends downward from the upper
end of the boss portion 34 while being widened in the radial
direction. The impeller body portion 31 has an umbrella shape or
substantially umbrella shape. In other words, the impeller body
portion 31 has a curved surface or a slant surface inclined with
respect to the center axis J. As illustrated in FIGS. 3 and 4, the
impeller body portion 31 surrounds the boss portion 34 in the
circumferential direction. A cavity AH exists radially inward of
the impeller body portion 31. The cavity AH is a space surrounded
by the impeller body portion 31 and the boss portion 34.
[0050] As illustrated in FIG. 3, the impeller body portion 31
preferably includes a body portion upper surface 31a, which is the
upper surface of the impeller body portion 31, and a body portion
lower surface 31b, which is the lower surface of the impeller body
portion 31. The body portion upper surface 31a is a gentle slant
surface which extends downward from the center axis J toward the
radial outer side.
[0051] The body portion lower surface 31b is connected to the boss
portion 34 at the radial inner end thereof. The body portion lower
surface 31b is a gentle slant surface which extends downward from
the radial inner side toward the radial outer side. The body
portion lower surface 31b is similar to the body portion upper
surface 31a. The body portion lower surface 31b is substantially
parallel to the body portion upper surface 31a. The thickness of
the impeller body portion 31 is substantially uniform.
[0052] The blade portions 32 are arranged on the body portion upper
surface 31a. The blade portions 32 extend upward from the body
portion upper surface 31a. The upper ends of the blade portions 32
are connected to the shroud portion 33. As illustrated in FIG. 5,
the blade portions 32 are uniformly arranged along the
circumferential direction. When viewed in the axial direction, the
blade portions 32 extend with a curvature on the body portion upper
surface 31a. In the example illustrated in FIG. 5, each of the
blade portions 32 has a single curvature.
[0053] The radial outer ends of the blade portions 32 are arranged
at the radial outer edge of the body portion upper surface 31a. The
radial inner ends of the blade portions 32 are arranged radially
inward of the radial outer edge of the impeller body portion 31.
When viewed in the axial direction, the blade portions 32 are
curved toward the rotation direction back side (-.theta..sub.Z
side) as the blade portions 32 extend from the radial inner side
toward the radial outer side. It is therefore possible to reduce
the pressure of an air applied to the blade portions 32 when the
impeller 30 rotates. This makes it possible to reduce the shaft
power applied by the motor 40.
[0054] The thickness L5 of the blade portions 32 is substantially
uniform. Thus, it is possible to suppress generation of a sink mark
which may be generated when the blade portions 32 are manufactured
by injection-molding a resin.
[0055] The blade portions 32 preferably include a plurality of
first blade portions 32a and a plurality of second blade portions
32b. The first blade portions 32a and the second blade portions 32b
are alternately disposed along the circumferential direction. The
radial inner ends of the first blade portions 32a are arranged
radially inward of the radial inner ends of the second blade
portions 32b.
[0056] In the example illustrated in FIG. 5, the blade portions 32
includes five first blade portions 32a and five second blade
portions 32b. That is to say, the number of the blade portions 32
in example illustrated in FIG. 5 is, e.g., ten. The number of the
blade portions 32 is not limited to the aforementioned number.
[0057] As illustrated in FIG. 3, the shroud portion 33 is arranged
above the blade portions 32. The shroud portion 33 is connected to
the impeller body portion 31 via the blade portions 32. As
illustrated in FIG. 2, the shroud portion 33 has an annular shape
centered at the center axis J or substantially annular shape. The
shroud portion 33 is shaped to extend radially outward and
downward.
[0058] As illustrated in FIG. 4, the rib portions 35 are arranged
on the body portion lower surface 31b. The rib portions 35 are
disposed within the cavity AH. In the present preferred embodiment,
the rib portions 35 are connected to the boss portion 34. This
makes it possible to enhance the strength of the impeller body
portion 31.
[0059] As illustrated in FIG. 5, when viewed in the axial
direction, the rib portions 35 extend with a curvature on the body
portion lower surface 31b. When viewed in the axial direction, the
front side end portions 35a as the rotation direction front side
(+.theta..sub.Z side) end portions of the rib portions 35 are
curved toward the rotation direction back side (-.theta..sub.Z
side) as the rib portions 35 extend from the radial inner side
toward the radial outer side.
[0060] In this regard, it is assumed that the air flowing through
the flow path 50 is introduced into an axial gap AP between the
impeller 30 and the motor cover portion 27 illustrated in FIG. 3.
The air introduced into the gap AP moves upward due to, e.g., screw
holes arranged on the upper surface of the motor cover portion 27,
and flows into the cavity AH. At this time, if a plurality of rib
portions is radially disposed so as to extend in the radial
direction, there may be a case where a turbulent flow is generated
between the respective rib portions. Thus, the pressure of an air
applied to the impeller 30 increases and the shaft power of the
motor 40 becomes larger. There is possibility that the blowing
efficiency of the impeller 30 is reduced.
[0061] In contrast, according to the present preferred embodiment,
the front side end portions 35a of the rib portions 35 are curved
toward the rotation direction back side (-.theta..sub.Z side). For
that reason, if the impeller 30 rotates, the air existing between
the rib portions 35 is discharged from the cavity AH. This makes it
possible to suppress generation of a turbulent flow within the
cavity AH and to reduce the pressure of an air applied to the
impeller 30. It is therefore possible to reduce the shaft power of
the motor 40. As a result, it is possible to suppress reduction of
the blowing efficiency.
[0062] Furthermore, it is possible to discharge the air, which may
otherwise generate a turbulent flow and stay within the cavity AH,
from the cavity AH. Thus, it is possible to suppress a loss of the
air introduced from the intake port 61 into the housing 20. This
makes it possible to enhance the blowing efficiency of the
centrifugal fan 10.
[0063] As the air is discharged from the cavity AH, there is
generated a flow of air which moves from the cavity AH toward the
flow path 50 via the gap AP. Thus, it is possible to restrain the
air from flowing into the cavity AH via the gap AP and to further
suppress generation of a turbulent flow within the cavity AH.
[0064] In the case where the flow path 50 has a scroll shape, the
air existing in the flow path 50 is easily introduced into the gap
AP and a turbulent flow is easily generated within the cavity AH.
However, in the present preferred embodiment, it is possible to
suppress generation of a turbulent flow within the cavity AH.
[0065] If the air introduced from the gap AP into the cavity AH
impinges against the rib portions 35, there is a possibility of
generation of a noise. However, in the present preferred
embodiment, it is possible to restrain the air from flowing into
the cavity AH. This makes it possible to restrain the air from
impinging against the rib portions 35 and generating a noise.
[0066] In the present disclosure, the expression "a certain subject
is curved toward the rotation direction back side" includes a case
where a certain subject as a whole bulges toward the rotation
direction back side. That is to say, a portion of a certain subject
may bulge toward the rotation direction front side or a portion of
a certain subject may have a straight shape, as long as a certain
subject as a whole bulges toward the rotation direction back
side.
[0067] When viewed in the axial direction, the back side end
portions 35b as the rotation direction back side (-.theta..sub.Z
side) end portions of the rib portions 35 are curved toward the
rotation direction back side as the rib portions 35 extend from the
radial inner side toward the radial outer side. That is to say, the
back side end portions 35b are curved toward the same side as the
front side end portions 35a. Thus, it is easy to make uniform the
thickness of the rib portions 35.
[0068] In the present preferred embodiment, the dimension between
the front side end portions 35a and the back side end portions 35b
of the rib portions 35, namely the thickness L4 of the rib portions
35, is substantially uniform. Thus, it is possible to suppress
generation of a sink mark which may be generated when the impeller
30 is manufactured by injection-molding a resin. Thus, according to
the present preferred embodiment, it is possible to manufacture the
impeller 30 with high dimensional accuracy.
[0069] In the present disclosure, the expression "the dimension of
a certain subject is substantially uniform" includes a case where
the dimension ratio with respect to the average dimension of a
certain subject is about 0.8 or more and 1.2 or less in any
position.
[0070] As illustrated in FIG. 5, the radial inner end portions of
the rib portions 35 are connected to the boss portion 34. The
radial outer end portions of the rib portions 35 are arranged at
the radial outer edge of the body portion lower surface 31b. That
is to say, the radial outer end portions of the rib portions 35 are
arranged at the radial outer edge of the impeller body portion 31.
Thus, in the radial direction, it is possible to broaden the range
over which the rib portions 35 are arranged. This makes it easy to
discharge the air from the interior of the cavity AH.
[0071] As illustrated in FIG. 3, the axial dimension L2 of the rib
portions 35 is one half or more of the axial dimension L3 of the
cavity AH. The axial dimension L3 of the cavity AH refers to the
axial distance between the position P, in which the impeller body
portion 31 and the boss portion 34 are connected to each other, and
the lower end of the impeller body portion 31. Thus, it is possible
to enhance the strength of the impeller body portion 31. Since the
rib portions 35 can be provided to further extend toward the radial
outer side, it is easy to discharge the air existing within the
cavity AH.
[0072] The axial dimension L2 of the rib portions 35 refers to the
axial dimension of the rib portions 35 measured in the radial inner
end portions of the rib portions 35. The dimension L2 is the
maximum value of the axial dimension of the rib portions 35.
[0073] In the present preferred embodiment, the axial dimension L2
of the rib portions 35 is equal to the axial dimension L3 of the
cavity AH. That is to say, the rib portions 35 extend from the
position P to the lower end of the impeller body portion 31 in the
axial direction. Thus, it is possible to further enhance the
strength of the impeller body portion 31. Since the rib portions 35
can be provided to extend to the radial outer edge of the impeller
body portion 31, it is possible to further discharge the air
existing within the cavity AH.
[0074] The axial dimension L2 of the rib portions 35 is one half or
more of the axial dimension L1 of the impeller body portion 31.
Thus, it is possible to secure the strength of the impeller body
portion 31.
[0075] As illustrated in FIG. 5, the impeller 30 preferably
includes a plurality of rib portions 35. Thus, it is possible to
further enhance the strength of the impeller body portion 31. The
rib portions 35 are uniformly disposed along the circumferential
direction. Thus, it is possible to uniformly discharge the air from
the interior of the cavity AH in the circumferential direction.
[0076] In the example illustrated in FIG. 5, the number of the rib
portions 35 is seven. In the present preferred embodiment, the
number of the rib portions 35 differs from the number of the blade
portions 32. In the case where the number of the rib portions 35 is
equal to the number of the blade portions 32, there is a risk that
the impeller 30 resonates due to the flow of the air discharged by
the rib portions 35 and the flow of the air discharged by the blade
portions 32. If the impeller 30 resonates, there is a possibility
that a load is applied to the shaft 41 and the shaft power of the
motor 40 is increased.
[0077] In contrast, according to the present preferred embodiment,
it is possible to suppress resonation of the impeller 30 because
the number of the rib portions 35 differs from the number of the
blade portions 32. As a result, it is possible to suppress the
increase in the shaft power of the motor 40.
[0078] When viewed in the axial direction, the rib portions 35
intersect the blade portions 32. Thus, it is possible to further
enhance the strength of the impeller body portion 31. In the
present preferred embodiment, each of the rib portions 35 has one
curvature. The curvature of each of the rib portions 35 differs
from the curvature of each of the blade portions 32. For that
reason, when viewed in the axial direction, the rib portions 35 can
intersect the blade portions 32.
[0079] The present disclosure is not limited to the preferred
embodiment described above. The present disclosure may employ, for
example, the configurations which will be described below. In the
following descriptions, there may be a case where the same
configurations as described above are appropriately designated by
like reference symbols with the descriptions thereof omitted.
[0080] As long as the front side end portions 35a are curved toward
the rotation direction back side (-.theta..sub.Z side), the shape
of the back side end portions 35b is not particularly limited. The
back side end portions 35b may have a configuration illustrated in
FIG. 6. FIG. 6 is a bottom view illustrating an impeller 130
according to another example of one preferred embodiment.
[0081] As illustrated in FIG. 6, the impeller 130 preferably
includes a plurality of rib portions 135. When viewed in the axial
direction, the front side end portions 135a as the rotation
direction front side (+.theta..sub.Z side) end portions of the rib
portions 135 are curved toward the rotation direction back side
(-.theta..sub.Z side) as the rib portions 135 extend from the
radial inner side toward the radial outer side. When viewed in the
axial direction, the back side end portions 135b as the rotation
direction back side (-.theta..sub.Z side) end portions of the rib
portions 135 have a straight shape. That is to say, the shape of
the rib portions 135 viewed in the axial direction is a
substantially semi-elliptical shape.
[0082] Thus, it is possible to increase the dimension between the
front side end portions 135a and the back side end portions 135b of
the rib portions 135, namely the thickness L6 of the rib portions
135. This enables the curved front side end portions 135a to
discharge the air existing within the cavity AH. It is therefore
possible to further enhance the strength of the impeller body
portion 31 while reducing the pressure of an air applied to the
impeller 130.
[0083] Each of the front side end portions 35a may have a plurality
of curvatures. In this case, the curvatures may include curvatures
whose center positions are arranged at the opposite sides of the
front side end portions 35a in the rotation direction
(.theta..sub.Z direction). Each of the front side end portions 135a
may have a straight section.
[0084] The number of the rib portions 35 is not particularly
limited and may be six or less or eight or more. That is to say, it
is preferred that the number of the rib portions 35 is at least one
or more. The number of the rib portions 35 may be equal to the
number of the blade portions 32.
[0085] The rib portions 35 may have an identical shape or different
shapes. In addition to the rib portions 35, there may be provided
straight rib portions extending in the radial direction when viewed
in the axial direction.
[0086] The rib portions 35 may not be connected to the boss portion
34. In this case, the rib portions 35 may be connected to only the
impeller body portion 31. The rib portions 35 may be connected to
the boss portion 34 via other portions.
[0087] The impeller 130 is directly or indirectly fixed to the
shaft 41. That is to say, the impeller 130 may be indirectly fixed
to the shaft 41.
[0088] In the example illustrated in FIG. 3, the boss portion 34 is
fitted to the shaft 41. However, the boss portion 34 may be fixed
to the shaft 41 in any way. For example, the boss portion 34 may be
fixed to the shaft 41 by a screw.
[0089] Each of the blade portions 32 may have a plurality of
curvatures. The number of the blade portions 32 is not particularly
limited.
[0090] The impeller 30 may not include the shroud portion 33.
[0091] the upper housing 21 may include the entirety of the upper
flow path 51 and the entirety of the lower flow path 52. The
housing 20 may be configured by axially interconnecting three or
more independent members. The housing 20 may be a single
member.
The flow path 50 may not have a scroll shape. The motor 40 may not
be accommodated within the housing 20.
[0092] The impeller of the present disclosure may be applied to not
only the centrifugal fan but also other kinds of blowers such as a
mixed flow fan and the like. The use of the impeller and the blower
according to the present disclosure is not particularly
limited.
[0093] Features of the above-described preferred embodiments and
the modifications thereof may be combined appropriately as long as
no conflict arises.
[0094] While preferred embodiments of the present invention have
been described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
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