Field
[0001] The present invention relates to an axial flow blade and a blower that includes the
axial flow blade.
Background
[0002] There is a blower that is installed in a location such as an office or a living room
and that rotates a blade by an electric motor to blow air. As disclosed in Patent
Literature 1, the blower has a structure in which the central portion of the blade,
connecting the electric motor and the blade with each other, is constituted by a boss
through which a shaft of the electric motor extends, and a hub having a cylindrical
shape with its one end open and having vanes located on the hub. In this structure,
a space is formed by being surrounded by the hub and a face of the electric motor
located closer to the blade.
Citation List
Patent Literature
[0003] Patent Literature 1: Japanese Patent Application Laid-open No.
H5-018398
Summary
Technical Problem
[0004] In the blower having the above structure, a resonance phenomenon such as air column
resonance or Helmholtz resonance occurs in the space surrounded by the electric motor
and the hub of the blade at a frequency determined by the dimensions of the space.
When the resonance frequency matches the frequency of bearing sound or the like of
the electric motor, the sound is amplified to become operating noise. In order to
reduce the amplification of the sound by shifting the resonance frequency from the
frequency of bearing sound or the like of the electric motor, it is necessary to change
the dimensions of the space in the hub of the blade. However, the dimensions of the
space may not be simply changed in view of the possible influence on the required
performance.
[0005] As described above, in the blower having the structure in which a space is formed
by being surrounded by the hub and the face of the electric motor located closer to
the blade, it is difficult to prevent an increase in the level of operating noise
caused by resonance.
[0006] The present invention has been made in view of the above problems, and an object
of the present invention is to provide a blower that can easily prevent an increase
in the level of operating noise even when the blower has a structure in which a space
is formed by being surrounded by a hub and a face of an electric motor located closer
to a blade.
Solution to Problem
[0007] In order to solve the above problems and achieve the object, the present invention
includes a boss through which a shaft of an electric motor extends, the electric motor
rotating the shaft about a rotational axis. The present invention includes a hub having
a cylindrical shape opened on a side closer to the electric motor, the hub being coaxial
with the boss and surrounding a periphery of the boss. The present invention includes
a partition plate installed in the hub to partition a space in the hub into two or
more spaces.
Advantageous Effects of Invention
[0008] The blower according to the present invention has an effect where it is possible
to easily prevent an increase in the level of operating noise even when the blower
has a structure in which a space is formed by being surrounded by a hub and a face
of an electric motor located closer to a blade.
Brief Description of Drawings
[0009]
FIG. 1 is a perspective view of a circulator fan that is a blower using an axial flow
blade according to a first embodiment of the present invention.
FIG. 2 is a side sectional view of the circulator fan according to the first embodiment.
FIG. 3 is an enlarged partial cross-sectional view illustrating the axial flow blade
of the circulator fan according to the first embodiment.
FIG. 4 is an exploded perspective view illustrating an attachment structure of an
electric motor and a blade of the circulator fan according to the first embodiment.
FIG. 5 is an enlarged side sectional view illustrating an interior of a hub of the
circulator fan according to the first embodiment.
FIG. 6 is an enlarged side sectional view illustrating an interior of the hub of a
circulator fan according to a second embodiment of the present invention.
FIG. 7 is an enlarged side sectional view illustrating an interior of a hub of a circulator
fan according to a third embodiment of the present invention.
FIG. 8 is a perspective view of a partition plate that partitions the interior of
the hub of the circulator fan according to the third embodiment.
Description of Embodiments
[0010] An axial flow blade and a blower according to embodiments of the present invention
will be described in detail below with reference to the accompanying drawings. The
present invention is not limited to the embodiments.
First embodiment.
[0011] FIG. 1 is a perspective view of a circulator fan that is a blower using an axial
flow blade according to a first embodiment of the present invention. FIG. 2 is a side
sectional view of the circulator fan according to the first embodiment. As illustrated
in FIGS. 1 and 2, a circulator fan 1 that is a blower includes: a stand 2 for floor
installation; and a body frame 3 held by the stand 2 in such a manner that the body
frame 3 is vertically pivotable. In the body frame 3, an electric motor 100 and an
electric unit 4 are mounted. The electric unit 4 adjusts a voltage to be applied to
the electric motor 100 and thereby changes the drive speed. An external power supply
is provided to the electric unit 4 through a power cord 5. An axial flow blade 200
is attached to a shaft 101 of the electric motor 100. When the electric motor 100
is driven, the axial flow blade 200 rotates so that the circulator fan 1 blows air
forward.
[0012] FIG. 3 is an enlarged partial cross-sectional view illustrating the axial flow blade
of the circulator fan according to the first embodiment. FIG. 3 illustrates the side
of the electric motor 100, while illustrating the cross-section of the axial flow
blade 200. FIG. 4 is an exploded perspective view illustrating an attachment structure
of the electric motor and the blade of the circulator fan according to the first embodiment.
As illustrated in FIGS. 3 and 4, a central portion 201 of the axial flow blade 200
is constituted by a boss 202 and a hub 205. In the boss 202, a boss hole 203 is formed
into which the shaft 101 of the electric motor 100 is fitted. A vane 204 is located
on the hub 205. The hub 205 has a cylindrical shape with its one end open. The center
axis of the hub 205 is coaxial with the center axis of the boss 202. In a state in
which the axial flow blade 200 is attached to the shaft 101, an open end 206 of the
hub 205 faces toward the electric motor 100. An end face 207 of the boss 202 is located
in the hub 205 more inward from the open end 206.
[0013] Meanwhile, the shaft 101 of the electric motor 100 is provided with a groove 104
between a tip end portion 102 and an electric motor frame 103. A C-ring 105 is engaged
with the groove 104. At the tip end portion 102, a D-cut shaped screw portion 107
is formed. The shaft 101 is inserted through the boss hole 203, and thereafter a cap
nut 108 is tightened onto the screw portion 107, so that the axial flow blade 200
is fixed to the shaft 101. At this time, a drive transmission plate 300 is interposed
between the axial flow blade 200 and the cap nut 108. A resin washer 106 serving as
an abutting portion and a partition plate 400 are interposed between the boss 202
and the C-ring 105 and fixed between them.
[0014] The drive transmission plate 300 is formed with a hole 302 at the center of a plate
surface 301. The hole 302 has a shape identical to the D-shape of the tip end portion
102 of the shaft 101. At edges 303 and 304 of the plate surface 301, clicks 305 and
306 are provided respectively and are positioned perpendicular to the plate surface
301. The hole 302 is engaged with the D-shaped screw portion 107, and the clicks 305
and 306 are engaged respectively with insertion holes 209 and 208 provided on a front
surface 205a of the hub 205, so that rotation of the shaft 101 is transmitted to the
axial flow blade 200.
[0015] The partition plate 400 is formed with a hole 402 at the center of a plate surface
401. The hole 402 has a diameter equal to the diameter of the shaft 101. The partition
plate 400 has an outer diameter smaller than the inner diameter of the hub 205.
[0016] FIG. 5 is an enlarged side sectional view illustrating an interior of the hub of
the circulator fan according to the first embodiment. When the partition plate 400
along with the axial flow blade 200 are assembled to the electric motor 100: the partition
plate 400 is located in the hub 205 and partitions, a space 500 formed between the
hub 205 and the electric motor 100 as illustrated in FIG. 3, into a space 501 and
a space 502. The partition plate 400 partitions the space 500 into the space 501 and
the space 502. This causes resonance in the space 502 located closer to the electric
motor 100 relative to the partition plate 400. In a case where the partition plate
400 is installed, the dimension of the space where resonance occurs in the rotational-axis
direction of the axial flow blade 200 is changed: from "A+B" that is the sum of a
dimension A between the partition plate 400 and the front surface 205a of the hub
205 and a dimension B between the partition plate 400 and the electric motor frame
103; to the dimension B between the partition plate 400 and the electric motor frame
103. Also in the case where the partition plate 400 is installed, the volume of the
space where resonance occurs is changed: from "V1+V2" that is the sum of a volume
V1 of the space 501 between the partition plate 400 and the front surface 205a of
the hub 205 and a volume V2 of the space 502 between the partition plate 400 and the
electric motor frame 103; to the volume V2 of the space 502 between the partition
plate 400 and the electric motor frame 103. In a case where there is not the partition
plate 400, resonance occurs in the space 500 in its entirety with the volume "V1+V2".
Accordingly, in the case where there is not the partition plate 400, the frequency
of sound to be amplified in the space 500 is different from the frequency of sound
to be amplified when resonance occurs in the space 502. Therefore, the frequency of
air column resonance and Helmholtz resonance is changed by installing the partition
plate 400. Because there is a gap between the inner diameter of the hub 205 and an
outer circumference 403 of the partition plate 400, Helmholtz resonance also occurs
in the space 501. An effect of muffling the resonance is thus obtained. It is allowable
that in the space 501, the hub 205 is provided with a rib extending parallel to the
rotational axis so as to form two or more spaces when the partition plate 400 is attached.
That is, the partition plate 400 is installed to change the volume of the space where
resonance occurs between the partition plate 400 and the electric motor 100. Thus,
the sound that might have been amplified when there is not the partition plate 400
can be prevented from being amplified after the installation of the partition plate
400.
[0017] The circulator fan 1 according to the first embodiment can prevent operating noise
from being amplified without changing the shape of the axial flow blade 200. Therefore,
the circulator fan 1, having a structure in which the space 500 is formed by being
surrounded by the hub 205 and the face of the electric motor 100 located closer to
the axial flow blade 200, can easily prevent an increase in the level of operating
noise caused by resonance.
Second embodiment.
[0018] FIG. 6 is an enlarged side sectional view illustrating an interior of a hub of a
circulator fan according to a second embodiment of the present invention. In FIG.
6, constituent elements identical to those according to the first embodiment are denoted
by like reference signs, and detailed descriptions thereof are omitted. The hub 205
of the axial flow blade 200 in the circulator fan 1 according to the second embodiment
is formed with engagement portions 210, 211, 212, and 213 protruding inward from the
inner-diameter side. The partition plate 400 is fixed to the axial flow blade 200
by being fitted at the outer circumference 403 between the engagement portions 210
and 212 and between the engagement portions 211 and 213. While the partition plate
400 can be fitted in a state of being elastically deformed and warped between the
engagement portions 211 and 213, it is also allowable to use another fitting method.
The diameter of the hole 402 of the partition plate 400 is larger than an outer diameter
of the boss 202, and thus a gap is provided between the boss 202 and the hole 402
of the partition plate 400. Other constituent elements are identical to those according
to the first embodiment.
[0019] The partition plate 400 is installed in the hub 205 and partitions the space 500
formed between the hub 205 and the electric motor 100 into a space 503 and a space
504. As the partition plate 400 partitions the space 500 into the space 503 and the
space 504, the resonance is generated in the space 504 located closer to the electric
motor 100 relative to the partition plate 400. In a case where the partition plate
400 is installed, the dimension of the space where resonance occurs in the rotational-axis
direction of the axial flow blade 200 is changed: from "C+D" that is the sum of a
dimension C between the partition plate 400 and the front surface 205a of the hub
205 and a dimension D between the partition plate 400 and the electric motor frame
103; to the dimension D between the partition plate 400 and the electric motor frame
103. Also in the case where the partition plate 400 is installed, the volume of the
space where resonance occurs is changed: from "V3+V4" that is the sum of a volume
V3 of the space 503 between the partition plate 400 and the front surface 205a of
the hub 205 and a volume V4 of the space 504 between the partition plate 400 and the
electric motor frame 103; to the volume V4 of the space 504 between the partition
plate 400 and the electric motor frame 103. Therefore, the frequency of air column
resonance and Helmholtz resonance is changed by installing the partition plate 400.
Because there is a gap between the outer diameter of the boss 202 and the hole 402
of the partition plate 400, Helmholtz resonance also occurs in the space 503. An effect
of muffling the resonance is thus obtained.
[0020] The circulator fan 1 according to the second embodiment can prevent operating noise
from being amplified without changing the shape of the axial flow blade 200. Therefore,
the circulator fan 1, having a structure in which the space 500 is formed by being
surrounded by the hub 205 and the face of the electric motor 100 located closer to
the axial flow blade 200, can easily prevent an increase in the level of operating
noise caused by resonance.
Third embodiment.
[0021] FIG. 7 is an enlarged side sectional view illustrating an interior of the hub of
a circulator fan according to a third embodiment of the present invention. FIG. 8
is a perspective view of a partition plate that partitions the interior of the hub
of the circulator fan according to the third embodiment. In FIGS. 7 and 8, constituent
elements identical to those according to the first embodiment are denoted by like
reference signs, and detailed descriptions thereof are omitted. The axial flow blade
200 of the circulator fan 1 according to the third embodiment includes engagement
portions 214, 215, 216, and 217 on the outer side of the boss 202. The partition plate
400 is formed with the hole 402 on the plate surface 401. The hole 402 has a diameter
equal to the diameter of the boss 202. The partition plate 400 has an outer diameter
smaller than the inner diameter of the hub 205. The boss 202 extends through the hole
402. The partition plate 400 is interposed between the engagement portions 214 and
216 and between the engagement portions 215 and 217 and is thereby fixed to the axial
flow blade 200. While the partition plate 400 can be fitted in a state of being elastically
deformed and warped between the engagement portions 214 and 216 and between the engagement
portions 215 and 217, it is also allowable to use another fitting method. At least
one hole 404 is formed around the hole 402 through which the boss 202 extends. That
is, at least one hole 404 is formed on the plate surface 401 in addition to the hole
402 through which the boss 202 extends. Other constituent elements are identical to
those according to the first embodiment. While the shape and size of the hole 404
and the number of holes 404 are not particularly limited, because the partition plate
400 rotates along with the axial flow blade 200, it is preferable that the holes 404
are positioned in such a manner as to maintain the rotational balance.
[0022] The partition plate 400 installed in the hub 205 partitions the space 500 into the
space 501 and the space 502, and thereby it is the space 502 where resonance occurs
as illustrated in FIG. 7. In a case where the partition plate 400 is installed, the
dimension of the space where resonance occurs in the rotational-axis direction of
the axial flow blade 200 is changed: from "A+B" that is the sum of the dimension A
between the partition plate 400 and the front surface 205a of the hub 205 and the
dimension B between the partition plate 400 and the electric motor frame 103; to the
dimension B between the partition plate 400 and the electric motor frame 103. Also
in the case where the partition plate 400 is installed, the volume of the space where
resonance occurs is changed: from "V1+V2" that is the sum of the volume V1 of the
space 501 between the partition plate 400 and the front surface 205a of the hub 205
and the volume V2 of the space 502 between the partition plate 400 and the electric
motor frame 103; to the volume V2 of the space 502 between the partition plate 400
and the electric motor frame 103. Therefore, the frequency of air column resonance
and Helmholtz resonance is changed by installing the partition plate 400. There is
a gap between the inner diameter of the hub 205 and the outer circumference 403 of
the partition plate 400, and the partition plate 400 is formed with the holes 404
on the plate surface 401. Thus, Helmholtz resonance also occurs in the space 501.
An effect of muffling the resonance is thus obtained in an extended area including
the plate surface 401 on which there are the holes 404.
[0023] The circulator fan 1 according to the third embodiment can prevent operating noise
from being amplified without changing the shape of the axial flow blade 200. Therefore,
the circulator fan 1, having a structure in which the space 500 is formed by being
surrounded by the hub 205 and the face of the electric motor 100 located closer to
the axial flow blade 200, can easily prevent an increase in the level of operating
noise caused by resonance.
[0024] The configurations described in the above embodiments are only examples of the content
of the present invention. The configurations can be combined with other well-known
techniques, and part of each of the configurations can be omitted or modified without
departing from the scope of the present invention.
Reference Signs List
[0025] 1 circulator fan, 2 stand, 3 body frame, 4 electric unit, 5 power cord, 100 electric
motor, 101 shaft, 102 tip end portion, 103 electric motor frame, 104 groove, 105 C-ring,
106 resin washer, 107 screw portion, 108 cap nut, 200 axial flow blade, 201 central
portion, 202 boss, 203 boss hole, 204 vane, 205 hub, 205a front surface, 206 open
end, 207 end face, 208, 209 insertion hole, 210, 211, 212, 213, 214, 215, 216, 217
engagement portion, 300 drive transmission plate, 301, 401 plate surface, 302, 402,
404 hole, 303, 304 edge, 305, 306 click, 400 partition plate, 403 outer circumference,
500, 501, 502, 503, 504 space.
1. An axial flow blade comprising:
a boss through which a shaft of an electric motor extends, the electric motor rotating
the shaft about a rotational axis;
a hub having a cylindrical shape opened on a side closer to the electric motor, the
hub being coaxial with the boss and surrounding a periphery of the boss; and
a partition plate installed in the hub to partition a space in the hub into two or
more spaces.
2. The axial flow blade according to claim 1, wherein
the partition plate is formed with a hole at a central portion thereof, the shaft
extending through the hole, and
the partition plate with the shaft extending through the hole is interposed between
the boss and a boss abutting portion located on the shaft, and is fixed to the boss.
3. The axial flow blade according to claim 1, wherein
the partition plate is formed with a hole at a central portion thereof, the shaft
extending through the hole,
the hub is formed with an engagement portion protruding inward from an inner surface
of the hub, and
the partition plate is fixed to the hub by engaging an outer circumferential portion
of the partition plate with the engagement portion.
4. The axial flow blade according to claim 1, wherein
the partition plate is formed with a hole at a center thereof, the boss extending
through the hole,
the boss is formed with an engagement portion protruding outward from an outer circumference
of the boss, and
the partition plate is fixed to the boss by engaging an edge of the hole of the partition
plate with the engagement portion.
5. The axial flow blade according to any one of claims 1 to 4, wherein the partition
plate is formed with at least one hole on a plate surface thereof in addition to the
hole through which the boss extends.
6. A blower comprising the axial flow blade according to any one of claims 1 to 5 and
the electric motor.