U.S. patent application number 14/878769 was filed with the patent office on 2016-05-19 for impeller for centrifugal fan and centrifugal fan.
The applicant listed for this patent is Minebea Co., Ltd.. Invention is credited to Manabu FUCHIBE.
Application Number | 20160138614 14/878769 |
Document ID | / |
Family ID | 55783320 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160138614 |
Kind Code |
A1 |
FUCHIBE; Manabu |
May 19, 2016 |
IMPELLER FOR CENTRIFUGAL FAN AND CENTRIFUGAL FAN
Abstract
There is provided an impeller for a centrifugal fan which
rotates around an axis extending from one side to the other side.
The impeller includes a main plate, a plurality of blades each
having one side portion located at the one side and the other side
portion located at the other side, the one side portion being
connected to a first surface of the main plate, and a connecting
ring which connects the other side portions of the blades. A first
circumferential groove to which a first balance weight is
attachable is formed in an outer circumferential portion of a
second surface of the main plate facing toward the one side. A
second circumferential groove to which a second balance weight is
attachable is formed in the connecting ring. An annular raised
portion is formed on the first surface at a portion corresponding
to the first circumferential groove.
Inventors: |
FUCHIBE; Manabu; (Saku-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Minebea Co., Ltd. |
Kitasaku-gun |
|
JP |
|
|
Family ID: |
55783320 |
Appl. No.: |
14/878769 |
Filed: |
October 8, 2015 |
Current U.S.
Class: |
416/144 ;
416/186R |
Current CPC
Class: |
F04D 29/282 20130101;
F04D 25/0613 20130101; F04D 29/662 20130101 |
International
Class: |
F04D 29/66 20060101
F04D029/66; F04D 29/28 20060101 F04D029/28; F04D 17/08 20060101
F04D017/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2014 |
JP |
2014-233618 |
Claims
1. An impeller for a centrifugal fan which rotates around an axis
extending from one side to the other side, the impeller comprising:
a main plate; a plurality of blades each having one side portion
located at the one side and the other side portion located at the
other side, the one side portion being connected to a first surface
of the main plate; and a connecting ring configured to connect the
other side portions of the plurality of blades, wherein a first
circumferential groove to which a first balance weight is
attachable is formed in an outer circumferential portion on a
second surface of the main plate, the second surface facing toward
the one side; a second circumferential groove to which a second
balance weight is attachable is formed in the connecting ring; and
an annular raised portion is formed on the first surface of the
main plate, at a location corresponding to the first
circumferential groove.
2. The impeller for the centrifugal fan according to claim 1,
wherein the main plate has a cup-shaped hub section protruding
toward the other side; and a shaft is fixed to the hub section.
3. The impeller for the centrifugal fan according to claim 1,
wherein the connecting ring is provided on an outer side of the
plurality of blades in a radial direction of the impeller, and
connects surfaces of the blades located on the outer side in the
radial direction.
4. The impeller for the centrifugal fan according to claim 1,
wherein the second circumferential groove is formed on a surface of
the connecting ring facing toward the other side.
5. The impeller for the centrifugal fan according to claim 1,
wherein the second circumferential groove is formed on an outer
side of the plurality of blades in a radial direction of the
impeller.
6. The impeller for the centrifugal fan according to claim 1,
wherein at least one of the first circumferential groove of the
main plate and the second circumferential groove of the connecting
ring has an inner circumferential wall portion and an outer
circumferential wall portion; the inner circumferential wall
portion is inclined relative to a radial direction of the impeller
at an angle .alpha.; the outer circumferential wall portion is
inclined relative to the radial direction at an angle .beta.; and
the angle .alpha. is smaller than the angle .beta..
7. The impeller for the centrifugal fan according to claim 1,
wherein an inner diameter of the connecting ring is greater than an
outer diameter of the main plate.
8. The impeller for the centrifugal fan according to claim 1,
wherein a thickness of the raised portion in the main plate is same
as or less than a thickness of the main plate.
9. A centrifugal fan comprising the impeller according to claim
1.
10. An impeller for a centrifugal fan, comprising: a disc-shaped
main plate; a plurality of blades arranged on a first surface of
the main plate; and a connecting ring connecting end portions of
the blades located at a side farther from the main plate; wherein a
first circumferential groove is formed in an outer circumferential
portion of a second surface of the main plate, the second surface
being opposite to the first surface; and a second circumferential
groove is provided in the connecting ring.
11. The impeller according to claim 10, wherein an annular raised
portion is provided on and projecting from the first surface of the
main plate; and the annular raised portion is provided at a back of
the first circumferential groove.
12. The impeller according to claim 11, wherein a thickness of the
raised portion in the main plate is not larger than a thickness of
the main plate.
13. The impeller according to claim 10, wherein the plurality of
blades are connected by the connecting ring on an outer
circumference side of the main plate.
14. The impeller according to claim 10, wherein the second
circumferential groove is provided on the connecting ring on a
surface located on a farther side from the first surface of the
main plate.
15. The impeller according to claim 10, wherein a partition wall is
provided inside of at least one of the first and second
circumferential grooves to partition at least one of the first and
second circumferential grooves in the circumferential
direction.
16. The impeller according to claim 10, wherein at least one of the
first circumferential groove and the second circumferential groove
has an inner circumferential wall portion and an outer
circumferential wall portion; the inner circumferential wall
portion is inclined relative to a radial direction of the main
plate at an angle .alpha.; the outer circumferential wall portion
is inclined relative to the radial direction at an angle .beta.;
and the angle .alpha. is smaller than the angle .beta..
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority from Japanese Patent
Application No. 2014-233618 filed on Nov. 18, 2014 and titled
"IMPELLER FOR CENTRIFUGAL FAN AND CENTRIFUGAL FAN", the disclosure
of which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present teaching relates to an impeller for a
centrifugal fan and a centrifugal fan, in particular, to an
impeller for a centrifugal fan and a centrifugal fan each having a
structure wherein blades of the impeller are connected to each
other with a connecting ring.
[0004] 2. Description of the Related Art
[0005] A centrifugal fan has been widely used for cooling,
ventilation, and air conditioning of various devices such as home
appliances, OA devices and industrial devices, and as air fans for
vehicles, and the like. A centrifugal fan of this kind is provided
with an impeller including a disc-shaped main plate to which a
driving shaft is fixed at a central portion of the main plate, and
a plurality of curved blades (vanes) fixed on a surface of the main
plate. Japanese Patent Application Laid-open No. 2014-088787
discloses this type of the centrifugal fan having such a structure
that a connecting ring is fixed to the end portions on the outer
circumferential (peripheral) side of the respective blades and
which connects the blades with each other.
[0006] Note that this kind of fan is provided with a mechanism for
suppressing any rotational imbalance generated in the impeller;
Japanese Patent Application Laid-open No. 2014-088787 describes
that the rotational balance of the impeller can be ensured by
providing a thickness-reduction section on the connecting ring
(paragraph [0105]). As a generally known method for adjusting the
rotational balance of the impeller, a balance weight cancelling the
rotational imbalance is attached to the impeller at a
circumferential location axisymmetric (symmetric with respect to
the rotational center of the impeller) to the location where a
rotational imbalance is present. Japanese Patent Application
Laid-open No. H11-210690 describes a turbo fan having a structure
in which a clip-shaped balance weight is clamped and attached to
the outer circumferential (peripheral) edge of a bell mouth
corresponding to the connecting ring of Japanese Patent Application
Laid-open No. 2014-088787.
SUMMARY
[0007] In the above methods for adjusting the rotational balance in
the conventional fan, the adjustment of the rotational balance
cannot be performed easily and quickly. Therefore, the mass
production of the impeller and fan is time-consuming.
[0008] The present teaching has been developed considering the
above situation, and a main object of the present teaching is to
provide an impeller for a centrifugal fan capable of performing the
adjustment of rotational balance easily and quickly and having
excellent mass productivity, and to provide a centrifugal fan using
such an impeller.
[0009] According to the first aspect of the present teaching, there
is provided an impeller for a centrifugal fan which rotates around
an axis extending from one side to the other side, the impeller
including: a main plate; a plurality of blades each having one side
portion located at the one side and the other side portion located
at the other side, the one side portion being connected to a first
surface of the main plate; and a connecting ring configured to
connect the other side portions of the plurality of blades, wherein
a first circumferential groove to which a first balance weight is
attachable is formed in an outer circumferential portion on a
second surface of the main plate, the second surface facing toward
the one side; a second circumferential groove to which a second
balance weight is attachable is formed in the connecting ring; and
an annular raised portion is formed on the first surface of the
main plate, at a location corresponding to the first
circumferential groove.
[0010] According to the second aspect of the present teaching,
there is provided an impeller for a centrifugal fan, including: a
disc-shaped main plate; a plurality of blades arranged on a first
surface of the main plate; and a connecting ring connecting end
portions of the blades located at a side farther from the main
plate;
wherein a first circumferential groove is formed in an outer
circumferential portion of a second surface of the main plate, the
second surface being opposite to the first surface; and a second
circumferential groove is provided in the connecting ring.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a vertical cross-sectional view of a centrifugal
fan related to an embodiment of the present teaching.
[0012] FIG. 2 is a plane view of an impeller provided on the
centrifugal fan.
[0013] FIG. 3 is an upper side perspective view of the
impeller.
[0014] FIG. 4 is a bottom side perspective view of the
impeller.
[0015] FIG. 5 is a cross-sectional view showing a circumferential
groove formed in the main plate.
[0016] FIG. 6 is a cross-sectional view showing a circumferential
groove formed in the connecting ring.
EMBODIMENTS
[0017] In the following, an embodiment related to the present
teaching will be explained with reference to the drawings.
[0018] <1. Basic Structure of Centrifugal Fan>
[0019] FIG. 1 is a vertical cross-sectional view of a centrifugal
fan 1 provided with an impeller 3 related to an embodiment, FIG. 2
is a plane view of the impeller 3, and FIGS. 3 and 4 are upper and
bottom side perspective views of the impeller 3, respectively. The
centrifugal fan 1 is provided with a plate-shaped base 2, the
impeller 3, and a motor 4 causing the impeller 3 to rotate.
[0020] In FIG. 1, the base 2 is depicted as a plate-shaped member
placed horizontally. The impeller 3 is rotatably supported on the
base 2 via a bearing 23. The impeller 3 has a disc-shaped main
plate 31 arranged parallel to the base 2, a plurality of blades
(vanes) 32 formed on the upper surface (a first surface) of the
main plate 31, and a connecting ring 33 arranged along the outer
peripheral portions of the blades 32. The impeller 3 is produced,
for example, by integrally molding the main plate 31, the plurality
of blades 32 and the connecting ring 33 with a synthetic resin.
[0021] As depicted in FIG. 1, the impeller 3 has the upper surface
serving as a fluid inlet port 301 and the side circumferential
(peripheral) surface serving as a fluid outlet (discharge) port
302, and the impeller 3 is rotated by the motor 4 in a direction
indicated by an arrow R in FIG. 2. When the impeller 3 is rotated,
air (fluid) is sucked from the fluid inlet port 301 and the air is
discharged from the fluid outlet port 302. The air is discharged in
a direction away from a shaft 34 fixed to the center of the
impeller 3.
[0022] As depicted in FIG. 1, a cup-shaped hub section 311 having a
cylindrical portion 312 and a lid portion 313 is formed in a
central portion of the main plate 31. The hub section 311 protrudes
upward from a flat portion of the main plate 31 which surrounds the
hub section 311, and the motor 4 is accommodated inside the hub
section 311. An upper end portion of the shaft 34, which extends in
the up and down direction penetrating through the motor 4, is fixed
to a central portion of the lid portion 313 of the hub section 311.
The shaft 34 is coaxially fixed to the hub section 311 by, for
example, the insert molding such that the shaft 34 is coincident
(coaxial) with the central axis of the cylindrical portion 312 of
the hub section 311. A boss 21 is formed at a central portion of
the base 2, and a sleeve 22 extending in the up and down direction
is upstandingly fixed inside the boss 21. Further, the shaft 34 is
rotatably supported inside the sleeve 22 via a pair of upper and
lower bearings 23. The bearings 23 are not limited to rolling
bearings; sliding bearings such as oil retaining bearings (oilless
bearings) may be used as the bearings 23.
[0023] As depicted in FIG. 2, each of the blades 32 is provided to
be inclined relative to the radial direction of the impeller 3 such
that an end portion on the outer peripheral side and an end portion
on the inner peripheral side of the blade 32 are located at
mutually different positions in the rotational direction of the
impeller 3, and each of the blades 32 is curved to project toward
the outer side in the radial direction of the impeller 3. With
this, the plurality of blades 32 provides a spiral form as a whole.
A gap is defined between the end portions on the inner peripheral
side of the blades 32 and the cylindrical portion 312 of the hub
section 311. The blades 32 are arranged to protrude on the main
plate 31 at equal intervals (distances) therebetween in the
circumferential direction, and the blades 32 are formed to have a
height greater than the height of the hub section 311. The
respective blades 32 are connected to one another by the connecting
ring 33. In some cases, the height of the blades 32 is set to be
smaller than the height of the hub section 311.
[0024] The connecting ring 33 is shaped to have an annular form
connecting upper end portions (end portions opposite to the end
portions at which the blades are connected to the main plate 31) of
the respective blades 32, located on the outer peripheral side of
the blades 32, and is shaped to protrude outwardly from the
respective blades 32 further toward the outer side in the radial
direction of the impeller 3. As depicted in FIG. 1, the connecting
ring 33 is connected to each of the blades 32 via a connecting
portion 331, and the inner diameter of the connecting ring 33 is
set to be same as or greater than the outer diameter of the main
plate 31. By setting the relationship between the inner diameter of
the connecting ring 33 and the outer diameter of the main plate 31
in such a manner, a mold (metal mold) for shaping the impeller 3
can be formed as a two-piece structure having a movable side part
and fixed side part. As a result, the cost of manufacturing the
impeller 3 can be lowered, with an increased productivity as
well.
[0025] As depicted in FIG. 1, the motor 4 which drives the rotation
of impeller 3 is composed of a stator 41 fixed to the outer
circumferential surface of the sleeve 22, and a rotor magnet 42
fixed to the inner circumferential surface of the cylindrical
portion 312 of the hub section 311 such that the rotor magnet 42
faces the stator 41 with a gap. A yoke 421 is fixed on the outer
circumferential side of the rotor magnet 42. The stator 41 is
composed of stator cores 411 extending radially from the sleeve 22
toward the rotor magnet 42, insulators 412 attached to the stator
cores 412 respectively, and coils 413 wound around the insulators
412 respectively. A circuit board 414 controlling the rotational
drive of the impeller 3 is arranged at the lower side of the stator
41.
[0026] In the motor 4, the electric current controlled by a driving
circuit of the circuit board 414 is made to flow in the coil 413
via the circuit board 414, and the stator cores 411 are
successively excited. With this, the impeller 3 to which the rotor
magnet 42 is fixed is rotated about the shaft 34 in the direction
indicated by the arrow R in FIG. 2. When the impeller 3 is rotated,
the plurality of blades 32 is rotated integrally to thereby
generate the following blowing action. That is, the air is sucked
from the fluid inlet port 301 located at the upper side of the
impeller 3 and the air is discharged from the fluid outlet port 302
located at the lateral side of the impeller 3.
[0027] <2. Mechanism for Adjusting Rotational Balance>
[0028] Next, an explanation will be made about a mechanism for
adjusting the rotational balance of the impeller 3. As depicted in
FIG. 5, a circumferential groove (first circumferential groove) 314
which is open downward and extends in full circumference is formed
on the lower surface (a second surface, a surface facing toward one
side in the axial direction) of the main plate 31 of the impeller 3
in the outer circumferential portion (i.e. a portion defined on the
outside of the middle position between the outer and inner
circumferences, in the radial direction of the main plate 31) of
the main plane. On the other hand, as depicted in FIG. 6, a
circumferential groove (second circumferential groove) 334 which is
open upward and extends in full circumference is formed on the
upper surface (a surface facing toward the other side in the axial
direction) of the connecting ring 33.
[0029] As depicted in FIG. 5, an annular raised portion 315 along
the circumferential groove 314 is formed in the main plate 31 at a
location above the circumferential groove 314 (on the other side in
the axial direction). Thickness 315t of the raised portion 315 is
set to be same as or thinner than thickness 31t of the main plate
31.
[0030] According to the impeller 3 related to the embodiment,
balance weights W having an appropriate weight can be attached to
the inside of either or both of the circumferential groove 314 of
the main plate 31 and the circumferential groove 334 of the
connecting ring 33, as depicted in FIGS. 5 and 6. By doing so, the
rotational balance is adjusted. A clay-like material, such as
putty, which has the plasticity and stickiness (adhesiveness) at a
time of the attachment, and which can be cured after the attachment
is appropriately used as the balance weight W. In a case of using
the putty, by using a tool such as a spatula to embed an
appropriate amount of the putty into the circumferential grooves
314 and/or 334, the putty can be attached to the circumferential
grooves 314 and/or 334 without allowing the putty from extruding
from the circumferential grooves 314 and 334.
[0031] In this embodiment, since the respective circumferential
grooves 314 and 334 to which the balance weights W can be attached
are arranged in the outer circumferential portions of the impeller
3, the rotational balance of the impeller 3 can be achieved
effectively by a smaller amount of the balance weights W than in a
case of attaching the balance weights W at any inner
circumferential portions of the impeller 3. Further, since each of
the circumferential grooves 314 and 334 is arranged at the outer
circumferential portions of the impeller 3 and the surrounding
portion around each of the circumferential grooves 314 and 334 is
free (any other structure is not present around each of the
circumferential grooves 314 and 334), the operation for attaching
the balance weights W to the grooves can be performed easily. As a
result, the rotational balance of the impeller 3 can be performed
easily and quickly, thereby achieving an excellent mass
productivity for the impeller 3. Furthermore, since the raised
portion 315 is formed in the main plate 31 at the location
corresponding to the circumferential groove 314, i.e., at the back
of circumferential groove 314, the thickness of the portion of the
impeller 3 at which the circumferential groove 314 is formed does
not become thin, and thus the strength of this portion is
ensured.
[0032] Moreover, since the inner diameter of the connecting ring 33
is set to be greater than the outer diameter of the main plate 31,
the balance weight W can be attached to the circumferential groove
334 of the connecting ring 33 at a location farther from the
rotational center of the impeller 3 than a conventional impeller,
thereby further reduction in the amount of the balance weight W can
be realized. Further, since the thickness 315t of the raised
portion 315 formed in the main plate 31 at the position above the
circumferential groove 314 is set to be same as or less than the
thickness 31t of the main plate 31, it is possible to suppress any
excessive protrusion of the raised portion 315 while ensuring the
strength provided by the raising portion 315.
[0033] Furthermore, in the circumferential groove 314 of the main
plate 31, an inner circumferential wall portion 314a and an outer
circumferential wall portion 314b which compose the circumferential
groove 314 are arranged as follows. That is, as depicted in FIG. 5,
the inner circumferential wall portion 314a is inclined relative to
the radial direction (the lower surface of the main plate 31) at an
angle .alpha. and the outer circumferential wall portion 314b is
inclined relative to the radial direction (the lower surface of the
main plate 31) at an angle .beta., where the angle .beta. is
approximately 90 degrees (right angle) and the angle .alpha. is
smaller than 90 degrees, for example, in a range of about 40
degrees to about 50 degrees. Note that, as depicted in FIG. 5, the
angle .alpha. means the angle defined between the inner
circumferential wall portion 314a and a portion of a line extending
along the main plate 31 in the radial direction of the main plate
31, the portion being defined on the outer side of the inner
circumferential wall portion 314a. Further, the angle .beta. means
the angle defined between the outer circumferential wall portion
314b and a portion of the line extending along the main plate 31 in
the radial direction of the main plate 31, the portion being
defined on the inner side of the outer circumferential wall portion
314b. By setting the angles .alpha. and .beta. in such a manner,
the width of the circumferential groove 314 becomes large, and thus
the balance weight W such as the putty can be easily attached to
the circumferential groove 314. At the same time, any separation of
the balance weight W from the circumferential groove 314 caused by
the centrifugal force can be suppressed.
[0034] Note that the circumferential groove 334 of the connecting
ring 33 may also be similarly formed such that the inclination
angle of an outer circumferential wall portion relative to the
radial direction (the upper surface of the connecting ring 33) is
greater than the inclination angle of an inner circumferential wall
portion relative to the radial direction (the upper surface of the
connecting ring 33). Further, pockets may be formed in each of the
circumferential grooves 314 and 334 by providing partition walls
which divide the internal annular space defined in each of the
circumferential grooves 314 and 334 in the circumferential
direction to thereby define the pockets. In each of the
circumferential grooves 314 and 334 having this configuration, it
is possible to suppress any displacement of the balance weight W in
the circumferential direction, as the balance weight W is attached
between the partition walls. Furthermore, the circumferential
groove formed in the connecting ring 33 may be formed at radially
outside location in relation to the blades 32.
[0035] According to the impeller related to the embodiment, the
rotational balance can be adjusted by arranging and attaching the
balance weight into each of the first circumferential groove of the
main plate and the second circumferential groove of the connecting
ring. Since the first circumferential groove of the main plate is
formed in the outer circumferential portion of the main plate, the
rotational balance can be adjusted effectively and with a smaller
amount of the balance weight than in a case of attaching the
balance weight in inner circumferential portion of the main plate.
Further, the first circumferential groove is formed in the outer
circumferential portion of the surface of the main plate on one
side in the axial direction, the second circumferential groove is
formed in the connecting ring connecting the other end portions of
the blades, and the first and second circumferential grooves are
both opened outward in the axial direction (any other structure is
not present at the outer side in the axial direction of each of the
first and second circumferential grooves). Thus, an operation for
attaching the balance weights to the grooves respectively can be
performed easily. As a result, the impeller related to the
embodiment is capable of realizing the adjustment of rotational
balance easily and quickly and has excellent mass-productivity.
Further, since the annular raised portion is formed in the main
plate at a portion corresponding to the first circumferential
groove, the thickness of the portion is not thinned and the
strength in the portion can be secured.
[0036] In the impeller related to the embodiment, since the
connecting ring is arranged on the radial outer side of the
plurality of blades, the amount of the balance weight to be
attached to the second circumferential groove formed in the
connecting ring can be made small.
[0037] In the impeller related to the embodiment, the
circumferential groove has a large width. Thus, in a case that the
balance weight is a clay-like material having plasticity, an
operation for attaching the balance weight to the outer
circumferential wall portion of the circumferential groove with a
spatula or the like can be performed easily. In addition, since the
balance weight is pressed against the outer circumferential wall
portion by the centrifugal force, any separation of the balance
weight from the circumferential groove can be suppressed.
[0038] In the impeller related to the embodiment, the balance
weight attached to the circumferential groove of the connecting
ring can be attached farther from the rotational center of the
impeller, as compared with a conventional impeller, thereby
contributing to reduce the amount of the balance weight.
[0039] In the impeller related to the embodiment, it is possible to
avoid an excessive protrusion (projection) of the raised position
while assuring the strength by the presence of the raised
portion.
[0040] According to the present embodiment, an impeller for a
centrifugal fan capable of adjusting the rotational balance easily
and in a short time, and having excellent mass productivity can be
provided, as well as a centrifugal fan using such an impeller can
be provided.
* * * * *