U.S. patent application number 16/546474 was filed with the patent office on 2019-12-12 for centrifugal fan.
The applicant listed for this patent is MINEBEA MITSUMI Inc.. Invention is credited to Seiya FUJIMOTO, Masaaki MATSUBARA, Kiyohisa NARA, Takuji YAMADA.
Application Number | 20190376523 16/546474 |
Document ID | / |
Family ID | 58558507 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190376523 |
Kind Code |
A1 |
YAMADA; Takuji ; et
al. |
December 12, 2019 |
CENTRIFUGAL FAN
Abstract
The application provides a centrifugal fan that can be easily
positioned when it is installed in a device or apparatus, which can
further improve positioning accuracy, and which can decrease noise,
even if it is made thin. In the centrifugal fan in which an
impeller is received inside a casing and air drawn in from a
suction port formed on the casing by rotating the impeller is
discharged from the casing to the outside of a blowing port, a
circular protruded portion is formed on a peripheral edge of the
suction port, and protrudes upwardly in a shaft direction from an
upper surface of the casing.
Inventors: |
YAMADA; Takuji; (Yaizu City,
JP) ; MATSUBARA; Masaaki; (Fukuroi City, JP) ;
FUJIMOTO; Seiya; (Fukuroi City, JP) ; NARA;
Kiyohisa; (Fukuroi City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MINEBEA MITSUMI Inc. |
Nagano |
|
JP |
|
|
Family ID: |
58558507 |
Appl. No.: |
16/546474 |
Filed: |
August 21, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15298778 |
Oct 20, 2016 |
10428827 |
|
|
16546474 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D 29/4226 20130101;
F04D 29/162 20130101; F04D 25/0613 20130101; F04D 25/0693 20130101;
F04D 25/08 20130101; F04D 29/601 20130101; F04D 25/06 20130101;
F04D 29/281 20130101 |
International
Class: |
F04D 29/16 20060101
F04D029/16; F04D 29/28 20060101 F04D029/28; F04D 29/42 20060101
F04D029/42; F04D 25/06 20060101 F04D025/06; F04D 25/08 20060101
F04D025/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2015 |
JP |
2015-209004 |
Feb 29, 2016 |
JP |
2016-037313 |
Claims
1. A centrifugal fan comprising: a casing formed by a lower casing
and an upper casing having a suction port; pillars interposed
between the lower casing and the upper casing; an impeller housed
in the casing and having a circular shroud, a main plate, and
blades arranged between the circular shroud and the main plate; and
a motor for rotating the impeller; wherein a circular protruded
portion for engaging with an object in which the centrifugal fan is
installed is formed on a peripheral edge of the suction port,
multiple concavities are formed on an upper surface of the upper
casing and arranged outside the circular protruded portion, wherein
the circular protruded portion protrudes upwardly in a shaft
direction from the upper surface of the upper casing, and air
sucked from the suction port by rotating the impeller is discharged
from a blowing port formed between the upper casing and the lower
casing.
2. The centrifugal fan according to claim 1, wherein the circular
shroud has a circular protruded portion, a circular groove is
arranged on a lower surface of the circular protruded portion of
the upper casing corresponding to the circular protruded portion of
the circular shroud, and a part of the circular protruded portion
of the circular shroud is housed in the circular groove.
3. The centrifugal fan according to claim 2, wherein a labyrinth
seal structure is formed between the circular groove and the
circular protruded portion formed on the circular shroud.
4. The centrifugal fan according to claim 2, wherein radial ribs
and circular ribs that connect the radial ribs are formed such that
an individual concavity is formed in the radial ribs and the
circular ribs.
5. The centrifugal fan according to claim 4, wherein the pillars
are arranged outside of an outermost individual concavity.
Description
Cross-Reference to Related Applications
[0001] This application claims the benefit of U.S. non-provisional
application Ser. No. 15/298,778, filed on Oct. 20, 2016 and
Japanese Application Nos. 2016-037313 filed on Feb. 29, 2016 and
2015-209004 filed on Oct. 23, 2015, all of which are incorporated
herein in its entirety by reference thereto.
TECHNICAL FIELD
[0002] The present invention relates to a centrifugal fan that can
be easily positioned when it is installed in a housing of another
device or apparatus.
BACKGROUND ART
[0003] A centrifugal fan is known as an air blower and is widely
used for cooling, ventilating, and air-conditioning in household
electrical appliances, office equipment and industrial equipment,
or air-conditioning and forcing air in an automobile, etc. As a
conventional centrifugal fan, a centrifugal fan in which a casing
is formed by an upper casing and a lower casing, and an impeller is
housed between the upper casing and the lower casing, and air drawn
in from a suction port by rotating the impeller is discharged
outwardly from a blowing port formed on a side surface between the
upper casing and the lower casing, is known (see Japanese
Unexamined Patent Application Publication No. 2012-207600).
[0004] FIG. 7 shows a centrifugal fan 100 described in Japanese
Unexamined Patent Application Publication No. 2012-207600. In the
centrifugal fan 100, a squared shaped casing 120 is formed by an
upper casing 121 and a lower casing 122, and an impeller 130 is
housed between the upper casing 121 and the lower casing 122. The
impeller 130 has a circular shroud 131. The air drawn in from a
suction port 110 by high-speed rotation of the impeller 130 is
passed through blades 135, it is blown outwardly from an out
periphery of the impeller 130, and it is discharged outwardly from
a blowing port 111 formed on a side surface between the upper
casing 121 and the lower casing 122.
[0005] In Japanese Unexamined Patent Application Publication No.
2012-207600, a specific structure in the case in which the
centrifugal fan is installed in a housing of another device or
apparatus is not described. The centrifugal fan described in this
document is fixed to a housing of a device or apparatus generally
by forming flanges which extend outwardly in a radial direction at
multiple positions, and by passing bolts, screws, etc., through
pass-through holes formed at the flanges.
[0006] However, in the case in which high accuracy of positioning
of the centrifugal fan is desired, the centrifugal fan cannot be
easily positioned and high accuracy of the positioning cannot be
easily performed, even if it is fixed to the housing of the device
or the apparatus by using the bolts, screws, etc., as described
above. Furthermore, in the centrifugal fan having a conventional
structure described in Japanese Unexamined Patent Application
Publication No. 2012-207600, it is necessary that the centrifugal
fan be made thin by decreasing total height thereof, when a
mounting space for the centrifugal fan is small. In this case,
since it is also necessary to use a thin type impeller, a
cross-sectional area of a passage at an air suction side of the
impeller is decreased, and ventilation resistance is increased, and
as a result, noise is increased.
[0007] In view of such circumstances, an object of the present
invention is to provide a centrifugal fan that can be easily
positioned when installed in a device or apparatus, which can
further improve positioning accuracy, and which can decrease noise,
even if it is made thin.
DISCLOSURE OF THE INVENTION
[0008] A first aspect of the present invention is characterized in
that a centrifugal fan, in which an impeller is received inside a
casing, air drawn in from a suction port formed on the casing by
rotating the impeller, is discharged from the casing to the outside
of a blowing port, and a circular protruded portion is formed on a
peripheral edge of the suction port, and protrudes upwardly in a
shaft direction from an upper surface of the casing.
[0009] In the first aspect of the present invention, it is
preferable that a circular groove be formed on a lower surface of
the circular protruded portion of the casing, and the circular
protruded portion be formed on a circular shroud that is a part of
members for composing the impeller, and be located in the circular
groove.
[0010] In the first aspect of the present invention, it is
preferable that a labyrinth seal structure be formed between the
circular groove and the circular protruded portion formed on the
circular shroud.
[0011] In the first aspect of the present invention, it is
preferable that the circular protruded portion formed on the
circular shroud be formed at an upper edge in a shaft direction of
the circular shroud.
[0012] In the first aspect of the present invention, it is
preferable that the circular protruded portion formed on the
circular shroud be formed on a step of an upper surface or an
inclined surface of the circular shroud.
[0013] In the first aspect of the present invention, it is
preferable that the casing be formed by an upper casing and a lower
casing, pillars be intervened between the upper casing and the
lower casing, and the blowing port be formed between the pillars
and on a side surface of the casing.
[0014] A second aspect of the present invention is characterized in
that a centrifugal fan, in which an impeller is received inside a
casing, air drawn in from a suction port formed on the casing by
rotating the impeller, is discharged from the casing to the outside
of a blowing port, and multiple gap portions for engaging with an
object in which the centrifugal fan is installed is formed on an
upper surface of the casing, the multiple gap portions comprise a
first gap portion composed by a circular protruded portion which
protrudes upwardly in a shaft direction and which is formed on a
peripheral edge of the suction port, and a second gap portion
formed outside in a radial direction of the circular protruded
portion, and the circular protruded portion protrudes upwardly from
the second gap portion.
[0015] In the second aspect of the present invention, it is
preferable that a circular groove be formed on a lower surface of
the circular protruded portion, and the circular protruded portion
be formed at an upper edge of a circular shroud which is a part of
members for composing the impeller, and a top of the circular
protruded portion be located in the circular groove.
[0016] In the second aspect of the present invention, it is
preferable that the top of the circular protruded portion formed at
an upper edge of the circular shroud be overlapped with a
peripheral side surface of the second gap portion, when it is
viewed from a perpendicular direction to a rotating shaft.
[0017] In the second aspect of the present invention, it is
preferable that a labyrinth seal structure formed between the
casing and the impeller be overlapped with a peripheral side
surface of the second gap portion, when it is viewed from a
perpendicular direction to a rotating shaft.
[0018] In the second aspect of the present invention, it is
preferable that a first step and a second step be formed on an
upper surface of a circular shroud, and the second gap portion of
the casing be opposite to the first step.
[0019] According to the present invention, a centrifugal fan that
can be easily positioned when it is installed in a device or
apparatus, that can further improve positioning accuracy, and that
can decrease noise, even if it is made thin, can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is an exploded perspective view showing a centrifugal
fan of a first embodiment of the present invention.
[0021] FIG. 2 is a cross-sectional view perspective view showing
the centrifugal fan in FIG. 1.
[0022] FIG. 3 is a partially enlarged view showing the centrifugal
fan in FIG. 2.
[0023] FIG. 4 is an exploded perspective view showing a centrifugal
fan of a second embodiment of the present invention.
[0024] FIG. 5 is a cross-sectional perspective view showing the
centrifugal fan in FIG. 4.
[0025] FIG. 6 is a partially enlarged view showing the centrifugal
fan in FIG. 5.
[0026] FIG. 7 is a cross-sectional view showing a conventional
centrifugal fan.
PREFERRED EMBODIMENTS OF THE INVENTION
1. First Embodiment
(1) Structure of Centrifugal Fan
[0027] FIG. 1 is an exploded perspective view showing a centrifugal
fan of a first embodiment of the present invention. FIG. 2 is a
cross-sectional perspective view showing the centrifugal fan in
FIG. 1. FIG. 3 is a partially enlarged view showing the centrifugal
fan in FIG. 2. In FIG. 2, the centrifugal fan 1 of the present
embodiment is shown. A basic structure of the centrifugal fan 1
includes a casing 2, which is a similar structure to that described
in Japanese Unexamined Patent Application Publication No.
2012-207600. The casing 2 is composed of an upper casing 3 and a
lower casing 4, and an impeller 8 is housed between the upper
casing 3 and the lower casing 4 (see FIG. 1).
[0028] Air drawn in from a suction port 35 by rotating the impeller
8 is passed through blades 10, and is discharged from blowing ports
36 formed on a side surface except for pillars 7 intervened between
the upper casing 3 and the lower casing 4 to the outside of the
casing 2 (outside in a radial direction). The impeller 8 is driven
and rotated by a motor 21 that is an outer rotor type brushless DC
motor. The motor 21 is mounted on a bottom surface of a concavity
5a formed on a motor base 5.
[0029] The motor 21 has a stator 22, as shown in FIG. 3. The stator
22 comprises a stator core 23 in which a desired number of cores in
a thin plate shape are laminated, an insulator 24 formed by an
upper insulator 24a and a lower insulator 24b mounted from both
sides in a shaft direction of the stator core 23, and a coil 25
wound around teeth of the stator core 23 via the insulator 24.
[0030] The core in a thin plate shape that forms the stator core 23
has multiple teeth (six teeth in FIG. 3) that extend to the outside
in a radial direction from a circular yoke. A bearing holding
portion 26 engages with an opening formed at the center of the
stator core 23, and the stator 22 is arranged outside of the
bearing holding portion 26. Bearings 27,28 are mounted inside of
the bearing holding portion 26, and a shaft 16 is rotatably
supported to the bearings 27,28. A circuit board 30 is mounted on
the lower insulator 24b, and the circuit board 30 is housed in the
concavity 5a.
[0031] A rotor 15 comprises the shaft 16, a boss portion 17 mounted
on the shaft 16, a rotor yoke 18 in a cup shape mounted on the boss
portion 17, and a circular magnet 19 fixed to the inside of the
rotor yoke 18. The rotor yoke 18 is fixed to the boss portion 17 by
calking.
[0032] The impeller 8 is connected with an outer periphery of the
rotor yoke 18 by using a flange 20. The impeller 8 comprises a
circular shroud 9, multiple blades 10, and a main plate 11 in a
disc shape, as shown in FIG. 1, and the blades 10 and the main
plate 11 are formed unitarily of resin. The blade 10 is formed in a
shaft direction on the main plate 11, has a shape which is bent and
tilted backwardly in a rotating direction, and is a backwardly
tilted blade in a rotating direction (a so-called turbo type
blade). All of the blades 10 have the same shape. The blades 10 and
the circular shroud 9 are joined by ultrasonic welding.
[0033] An upper surface of the circular shroud 9 has two steps, and
each step is formed to be a flat surface and an inclined surface is
formed between the steps, and a circular protruded portion 9a is
formed at an upper edge in a shaft direction of the circular shroud
9. An electrode of an ultrasonic welding device is easily contacted
by this flat surface of the step when the blades 10 and the
circular shroud 9 are joined by ultrasonic welding. A top of the
circular protruded portion 9a formed at an upper edge in a shaft
direction of the circular shroud 9 is located in a circular
concavity (groove) 3c formed at a lower surface of the upper casing
3 and it is covered with the upper casing 3.
[0034] The main plate 11 of the impeller 8 has an inclined surface
11a between an inner peripheral side and an outer peripheral side.
That is, the inner peripheral side of the impeller 8 is located at
an upper side in a shaft direction, the outer peripheral side of
the impeller 8 is located at a lower side in a shaft direction, and
the inclined surface 11a is located between the inner peripheral
side and the outer peripheral side.
[0035] The impeller 8 and the rotor 15 are joined in the following
manner. First, the circular flange 20 is welded on an outer
peripheral surface of the rotor yoke 18 by, for example, resistance
welding. Next, the main plate 11 is fixed to the flange 20. A pin
(not shown) is formed in one body on a lower surface at an inner
peripheral side of the main plate 11, this pin is engaged with a
pass-through hole formed on the flange 20, and the main plate 11 is
fixed to the flange 20 by calking, that is, by heating and
deforming a tip of the pin. Therefore, the impeller 8 is mounted on
the rotor 15.
[0036] An opening as the suction port 35 is formed at the center of
the upper casing 3, a circular protruded portion 3b that protrudes
upwardly in a shaft direction is formed on a periphery of the
opening, multiple concavities 3a (relief portions) are formed at an
outer peripheral side of the circular protruded portion 3b and at
an upper side of the upper casing 3, and multiple ribs are radially
formed between the concavities 3a (see FIG. 1). The upper casing 3
and the lower casing 4 are joined by intervening pillars 7 between
the upper casing 3 and the lower casing 4 and by fastening the
pillars 7 using fastening members such as screws. Specifically, the
pillars 7 are formed in one body by the upper casing 3 and resin,
and lower holes are formed on the pillars 7. Then, the upper casing
3 and the lower casing 4 are joined by passing the pillars 7
through a pass-through hole 6d of the lower casing 4 (a base plate
6), and by screwing tapping screws 40 into the lower holes of the
pillars 7 through pass-through holes 5d (see FIG. 1). Here, a
fastening means is not limited to this process, and for example,
the casings may be fixed by passing screws (or bolts) through the
pass-through holes of the pillars 7 from a side of the lower casing
4, and by fastening nuts from a side of the upper casing 3.
[0037] The lower casing 4 is formed by laminating a motor base 5
made of metal (for example, a steel plate) and the base plate 6
made of resin. The motor 21 is mounted on a lower surface of the
concavity 5a formed on the motor base 5. Side portions 6a (see FIG.
1) which extend downwardly are formed at four positions on an outer
peripheral edge of the base plate 6, and an outer periphery of four
sides of the motor base 5 is contacted with the inside of these
side portions 6a, so that the motor base 5 and the base plate 6 are
positioned.
[0038] Electronic components 31 such as a controlling IC or parts
for controlling and driving the motor 21, etc., is mounted on the
circuit board 30. Here, in order to prevent the impeller 8 from
contacting the electronic components 31 mounted on the circuit
board 30 in a limited space, the inclined surface 11a is formed on
the main plate 11, and a part of the electronic components 31 is
contained at a position of this inclined surface 11a. Therefore,
the impeller 8 can be prevented from contacting the electronic
components 31, and the centrifugal fan can be made thin in a shaft
direction.
(2) Features
[0039] An opening as the suction port 35 is formed at the center of
the upper casing 3, and the circular protruded portion 3b that
protrudes upwardly in a shaft direction is formed on a periphery of
the opening, and this circular protruded portion 3b protrudes
upwardly from an upper surface of the upper casing 3. When the
centrifugal fan 1 is installed in a housing of another device or
apparatus, the centrifugal fan 1 can be easily positioned in
mounting on the device or the apparatus and accuracy of the
positioning can be improved, by fitting this circular protruded
portion 3b as a socket-and-spigot structure. In addition, in
connection with size of the opening formed on the housing, it is
not necessary to consider variation in mounting the centrifugal fan
1.
[0040] The circular concavity (groove) 3c is formed on a lower
surface of the circular protruded portion 3b of the upper casing 3,
and a top of the circular protruded portion 9a formed at an upper
edge in a shaft direction of the circular shroud 9 is located in
the circular concavity (groove) 3c formed on a lower surface of the
upper casing 3. In this structure, the circular protruded portion
9a is covered with the upper casing 3. Then, a labyrinth seal
structure is formed between a side surface of the protruded portion
9a of the circular shroud 9 and the upper casing 3. According to
this labyrinth structure, a part of the air blown out from an outer
periphery of the impeller can be prevented from flowing in an
opposite direction to the suction port 35.
[0041] In addition, although the labyrinth structure is formed on
the lower surface of the circular protruded portion 3b of the upper
casing 3, the circular protruded portion 3b is located in the
device or the apparatus since the circular protruded portion 3b of
the upper casing 3 is used as a socket-and-spigot structure in
mounting to the device or the apparatus. Therefore, a height in a
shaft direction of the centrifugal fan 1 is substantially a height
from the lower surface of the lower casing 4 to the upper surface
of the upper casing 3, and an effective height can be
decreased.
[0042] A width in a radial direction of the circular protruded
portion 3b is not limited to a specific range, and the width may be
a width of a step which is located at a side of the suction port 35
formed on the upper surface of the circular shroud 9 or a width
having a position of an inclined surface formed between two
steps.
[0043] Although the protruded portion 9a of the circular shroud 9
is formed at the upper edge in a shaft direction, it is not limited
to this structure, and it may be formed on the step which is
located at a side of the suction port 35 or it may be formed at the
position of the inclined surface formed between two steps.
[0044] The circular concavity (groove) 3c formed on the lower
surface of the protruded portion 3b of the upper casing 3 is formed
at a position corresponding to the circular protruded portion 9a
formed on the circular shroud 9, and the top of the circular
protruded portion 9a is located in the circular concavity (groove)
3c.
[0045] This circular protruded portion 3b may be used as a position
for mounting the other members (for example, a cover, etc.), and
may be used for positioning, except that the circular protruded
portion 3b is used as a socket-and-spigot structure.
2. Second Embodiment
(1) Structure of Centrifugal Fan
[0046] FIGS. 4 and 5 show a centrifugal fan 1 of a second
embodiment of the present invention. A basic structure of the
centrifugal fan 1 is a similar structure to that described in
Japanese Unexamined Patent Application Publication No. 2012-207600.
The centrifugal fan 1 contains a casing 2. The casing 2 is composed
of an upper casing 3 and a lower casing 4. An impeller 8 is housed
between the upper casing 3 and the lower casing 4. Air is drawn in
from a suction port 35 by rotating the impeller 8, the air is
passed through blades 10, and is discharged from blowing ports 36
formed on a side surface except for pillars 7 intervened between
the upper casing 3 and the lower casing 4 to outside of the casing
2 (outside in a radial direction).
[0047] The lower casing 4 is formed by laminating a motor base 5
made of metal (for example, a steel plate) and the base plate 6
made of resin. A bearing holding portion 26 in an approximately
cylindrical shape is fixed to the motor base 5. Bearings 27,28 are
mounted inside the bearing holding portion 26, and a shaft 16 as a
rotating shaft is rotatably supported by the bearings 27,28.
[0048] A motor 21, which is an outer rotor type brushless DC motor,
is mounted on a bottom surface of a concavity 5a formed on the
motor base 5. The motor 21 has a lower insulator 24b, and the lower
insulator 24b contacts with the bottom surface of the concavity 5a.
A circuit board 30 is fixed to the lower insulator 24b, and the
circuit board 30 is also housed in the concavity 5a.
[0049] A stator 22, which composes the motor 21, is fixed to the
outside of the bearing holding portion 26. The stator 22 contains a
stator core 23 in which a desired number of cores made of soft
magnetic material in a thin plate shape such as a steel plate,
etc., are laminated, an insulator 24 formed by an upper insulator
24a and the lower insulator 24b mounted from both sides in a shaft
direction of the stator core 23 and made of resin, and a coil 25
wound around teeth of the stator core 23 via the insulator 24.
[0050] The core in a thin plate shape that forms the stator core 23
has multiple teeth (six teeth in FIG. 4) which extend to the
outside in a radial direction from a circular yoke, and the stator
core 23 is formed by laminating the cores in a thin plate shape. An
opening is formed at the center of the stator core 23, the bearing
holding portion 26 engages with the opening.
[0051] Side portions 6a (see FIG. 4) which extend downwardly are
formed at four positions on an outer peripheral edge of the base
plate 6, and an outer periphery of four sides of the motor base 5
is contacted with the inside of these side portions 6a, so that the
motor base 5 and the base plate 6 are positioned.
[0052] A rotor 15 contains the shaft 16 rotatably supported by the
bearings 27,28, a boss portion 17 mounted on the shaft 16, a rotor
yoke 18 in a cup shape fixed to the boss portion 17 by calking, and
a circular magnet 19 fixed to the inside of the rotor yoke 18. The
rotor 15 which is formed in one body with the below impeller 8, is
driven by the motor 21, and rotates against the stator 22.
[0053] The impeller 8 is fixed to the rotor 15. The impeller 8 is
formed of a circular shroud 9, multiple blades 10, and a main plate
11 in a disc shape, and the blades 10 and the main plate 11 are
formed unitarily of resin. The blade 10 is formed in a shaft
direction on the main plate 11, has a shape which is bent and
tilted backwardly in a rotating direction, and is a backwardly
tilted blade in a rotating direction (a so-called turbo type
blade). All of the blades 10 have the same shape, and the blades 10
and the circular shroud 9 are joined by for example, welding, and
the impeller 8 may be formed by different resin materials using a
two-color formation technique. An upper surface of the circular
shroud 9 has a first circular step 9b and a second circular step
9c, and each step 9b,9c is formed to be an approximately flat
surface and an inclined surface is formed between the steps 9b,9c,
and a circular protruded portion 9a is formed at an upper edge in a
shaft direction of the circular shroud 9. A top of the circular
protruded portion 9a formed at an upper edge in a shaft direction
of the circular shroud 9 is located in a circular concavity
(groove) 3c formed at a lower surface of the upper casing 3, and it
is covered with the upper casing 3.
[0054] The main plate 11 of the impeller 8 has an inclined surface
11a between an inner peripheral side and an outer peripheral side.
That is, the inner peripheral side of the impeller 8 is located at
an upper side in a shaft direction, the outer peripheral side of
the impeller 8 is located at a lower side in a shaft direction, and
the inclined surface 11a is located between the inner peripheral
side and the outer peripheral side.
[0055] The impeller 8 and the rotor 15 are joined by the following
manner. A pin 11b is formed in one body on a lower surface at an
inner peripheral side of the main plate 11, this pin 11b is engaged
with a pass-through hole formed on the flange 18a which extends
outwardly in a radial direction from an outer peripheral surface of
the rotor yoke 18, and the main plate 11 is fixed to the rotor yoke
18 by heat-calking or infrared-calking a tip of the pin 11b.
Therefore, the impeller 8 is mounted on the rotor 15.
[0056] Multiple concavities 3a (relief portions) are formed at an
upper side of the upper casing 3. The upper casing 3 and the lower
casing 4 are joined by intervening pillars 7 between the upper
casing 3 and the lower casing 4 and by fastening the pillars 7
using fastening members such as screws. Specifically, the pillars 7
are formed in one body by the upper casing 3 and resin. Then, the
upper casing 3 and the lower casing 4 are joined by screwing
tapping screws 40 into lower holes formed on the pillars 7 through
pass-through holes 5d,6d of the lower casing 4. Here, a fastening
means is not limited to this process. For example, the casings may
be fixed by passing screws (or bolts) through the pass-through
holes of the pillars 7 from a side of the lower casing 4, and by
fastening nuts from a side of the upper casing 3.
[0057] Electronic components 31 such as a controlling IC or parts
for controlling and driving the motor 21, etc., are mounted on the
circuit board 30. Here, in order to prevent the impeller 8 from
contacting the electronic components 31 mounted on the circuit
board 30 in a limited space, the inclined surface 11a is formed on
the main plate 11, and a part of the electronic components 31 is
contained at a position of this inclined surface 11a. Therefore,
the impeller 8 can be prevented from contacting the electronic
components 31, and the centrifugal fan can be made thin in a shaft
direction.
(2) Features
[0058] An opening as the suction port 35 is formed at the center of
the upper casing 3, and multiple gap portions (a first gap portion
and a second gap portion) are formed on an upper surface of the
upper casing 3. The circular protruded portion 3b (the first gap
portion) which protrudes upwardly in a shaft direction is formed on
a periphery of the opening, a second gap portion 3d is formed on an
outer peripheral portion of the circular protruded portion 3b, and
the protruded portion 3b (the first gap portion) protrudes upwardly
from the second gap portion 3d. For example, when the centrifugal
fan 1 is installed in a housing of a device or apparatus as an
object in which the centrifugal fan 1 is installed, the protruded
portion 3b (the first gap portion) and the second gap portion 3d
are fitted to a mounting hole or a duct formed on the housing of
the device or the apparatus as a socket-and-spigot structure. That
is, an outer peripheral side surface 3b' of the protruded portion
3b (the first gap portion) and an outer peripheral side surface 3d'
of the second gap portion 3d are contacted and fitted with an inner
periphery of the mounting hole of the device or the apparatus as an
object in which the centrifugal fan 1 is installed. According to
this structure, the centrifugal fan 1 can be easily positioned in
mounting on the device or the apparatus and accuracy of the
positioning can be improved. As a result, in connection with size
of the opening formed on the housing also, it is not necessary to
consider variation in mounting the centrifugal fan 1.
[0059] The circular concavity (groove) 3c is formed on a lower
surface of the circular protruded portion 3b of the upper casing 3,
and a top of the circular protruded portion 9a formed at an upper
edge in a shaft direction of the circular shroud 9 is located in
the circular concavity (groove) 3c formed on a lower surface of the
upper casing 3, so that the circular protruded portion 9a is
covered with the upper casing 3. Then, a labyrinth seal structure
is formed between a side surface of the protruded portion 9a of the
circular shroud 9 and the upper casing 3. According to this
labyrinth structure, a part of the air blown out from an outer
periphery of the impeller can be prevented from flowing in an
opposite direction to the suction port 35.
[0060] In addition, the first circular step 9b formed on the upper
surface of the circular shroud 9 is approximately flat. Therefore,
the second gap portion 3d of the upper casing 3 is formed at a
position opposing the first circular step 9b. A thick portion of
the first circular step 9b can be used as a position for adjusting
balance of the impeller 8. Specifically, the balance can be
adjusted by forming a concavity 9d at this thick portion of the
step 9b, and by mounting a weight to the formed concavity 9d as a
positive balance adjustment or removing a part of this thick
portion of the step 9b as a negative balance adjustment.
[0061] In the centrifugal fan having a conventional structure
described in Japanese Unexamined Patent Application Publication No.
2012-207600, it is necessary that the centrifugal fan be made thin
by decreasing the total height thereof, when a mounting space for
the centrifugal fan is small. In this case, since it is also
necessary to use a thin type impeller, a cross-sectional area of a
passage at an air suction side of the impeller is decreased, and
ventilation resistance is increased, and as a result, noise is
increased. In contrast, in the centrifugal fan 1 according to the
present invention, the protruded portion 3b (the first gap portion)
and the second gap portion 3d (or only the second gap portion 3d)
are engaged with the inside of the mounting hole or the duct formed
on a housing of the device or the apparatus (an object in which the
centrifugal fan is installed) as a socket-and-spigot structure.
According to this structure, a cross-sectional area of a passage at
an air suction side of the impeller 8 cannot be decreased; that is,
the cross-sectional area of a passage at an air suction side of the
impeller 8 can be increased more than that of the impeller of the
conventional centrifugal fan described in Japanese Unexamined
Patent Application Publication No. 2012-207600, even if a total
height of the centrifugal fan is the same as that of the
conventional centrifugal fan described in Japanese Unexamined
Patent Application Publication No. 2012-207600. As a result of
this, the ventilation resistance can be reduced, air volume
characteristics can be improved, the noise can be decreased, and
the centrifugal fan can be made thin.
[0062] In particular, in the present embodiment, the top 9a of the
circular protruded portion formed at an upper edge of the circular
shroud 9 is overlapped with the outer peripheral side surface 3d'
of the second gap portion 3d, when it is viewed from a direction
perpendicular to the rotating shaft (the shaft 16). That is,
labyrinth seal structure formed between the upper casing 3 and the
impeller 8 is overlapped with the outer peripheral side surface 3d'
of the second gap portion 3d. In this structure, the labyrinth seal
structure formed at an upper portion of the centrifugal fan 1, that
is, the labyrinth seal structure formed between the upper casing 3
and the impeller 8, is obtained in a structure of an object to be
installed, and therefore, the centrifugal fan 1 can be made thin
and the cross-sectional area of a passage at an air suction side of
the impeller 8 can be maintained.
[0063] Furthermore, in the centrifugal fan 1 of the present
embodiment, multiple gap portions (the first gap portion and the
second gap portion) are formed on the upper surface of the upper
casing 3, and the protruded portion 3b (the first gap portion) and
the second gap portion 3d (or only the second gap portion 3d) are
engaged with the inside of the mounting hole or the duct formed on
the housing of the device or the apparatus as a socket-and-spigot
structure. However, the third gap portion (or multiple gap
portions) is formed outwardly in a shaft direction of the second
gap portion, and the first gap portion, the second gap portion and
the third gap portion (or only the third gap portion) may be
engaged with the inside of a mounting hole or an air duct formed on
a housing of a device or apparatus, as a socket-and-spigot
structure. The gap portions may be placed at three positions or
more.
EXPLANATION OF REFERENCE SYMBOLS
[0064] 1 . . . centrifugal fan, 2 . . . casing, 3 . . . upper
casing, 3a . . . concavity, 3b . . . circular protruded portion
(first gap portion), 3c . . . circular concavity, 3d . . . second
gap portion, 4 . . . lower casing, 5 . . . motor base, 5a . . .
concavity, 5d . . . pass-through hole, 6 . . . base plate, 6a . . .
side portion, 6d . . . pass-through hole, 7 . . . pillar, 8 . . .
impeller, 9 . . . shroud, 9a . . . protruding portion, 10 . . .
blade, 11 . . . main plate, 11a . . . inclined surface, 11b . . .
pin, 15 . . . rotor, 16 . . . shaft, 17 . . . boss portion, 18 . .
. rotor yoke, 18a . . . flange, 19 . . . magnet, 20 . . . flange,
21 . . . motor, 22 . . . stator, 23 . . . stator core, 24 . . .
insulator, 24a . . . upper insulator, 24b . . . lower insulator, 25
. . . coil, 26 . . . bearing holding portion, 27 . . . bearing, 28
. . . bearing, 30 . . . circuit board, 31 . . . electronic
component, 35 . . . suction port, 36 . . . blowing port.
* * * * *