U.S. patent application number 13/350096 was filed with the patent office on 2012-08-09 for blower fan.
This patent application is currently assigned to Nidec Corporation. Invention is credited to Tatsuya AKASE, Naoki MATSUBA, Kazumi TAKESHITA.
Application Number | 20120201670 13/350096 |
Document ID | / |
Family ID | 46586786 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120201670 |
Kind Code |
A1 |
TAKESHITA; Kazumi ; et
al. |
August 9, 2012 |
BLOWER FAN
Abstract
A blower fan includes a motor unit including a rotary unit; a
plurality of blades fixed to an outer surface of the rotary unit
and arranged to be rotated about a center axis by the motor unit;
and a lower plate portion defined by a magnetic body and positioned
below the motor unit and the blades. The lower plate portion
includes a motor fixing portion, a curved portion, a peripheral
portion, and a plurality of ribs arranged to interconnect the motor
fixing portion and the peripheral portion either directly or
through the curved portion, the curved portion including a standing
portion extending upward from the outer edge portion of the motor
fixing portion and an upper surface portion extending radially
outward from an upper end of the standing portion, a plurality of
openings positioned below the blades being defined by the curved
portion, the peripheral portion, and the ribs.
Inventors: |
TAKESHITA; Kazumi; (Kyoto,
JP) ; AKASE; Tatsuya; (Kyoto, JP) ; MATSUBA;
Naoki; (Kyoto, JP) |
Assignee: |
Nidec Corporation
Kyoto
JP
|
Family ID: |
46586786 |
Appl. No.: |
13/350096 |
Filed: |
January 13, 2012 |
Current U.S.
Class: |
415/212.1 |
Current CPC
Class: |
F04D 29/522 20130101;
F04D 25/0613 20130101 |
Class at
Publication: |
415/212.1 |
International
Class: |
F01D 9/00 20060101
F01D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2011 |
JP |
2011-023184 |
Claims
1. A blower fan, comprising: a motor unit including a rotary unit;
a plurality of blades fixed to an outer surface of the rotary unit
of the motor unit and arranged to be rotated about a center axis by
the motor unit; and a lower plate portion defined by a magnetic
body and positioned below the motor unit and the blades; wherein
the lower plate portion includes a motor fixing portion to which
the motor unit is fixed, a curved portion provided in an outer edge
portion of the motor fixing portion, a peripheral portion, and a
plurality of ribs arranged to interconnect the motor fixing portion
and the peripheral portion either directly or through the curved
portion; the curved portion is arranged below a rotor magnet of the
rotary unit to annularly extend about the center axis, the curved
portion including a standing portion extending upward from the
outer edge portion of the motor fixing portion and an upper surface
portion extending radially outward from an upper end of the
standing portion, a plurality of openings positioned below the
blades being defined by the curved portion, the peripheral portion,
and the ribs.
2. The blower fan of claim 1, further comprising a sidewall portion
arranged to cover sides of the blades, the sidewall portion
including a lower end portion fixed to the peripheral portion.
3. The blower fan of claim 1, further comprising an upper plate
portion positioned above the motor unit and the blades, the upper
plate portion being made of metal or resin.
4. The blower fan of claim 2, further comprising an upper plate
portion positioned above the motor unit and the blades, the upper
plate portion being made of resin and continuously joined to the
sidewall portion.
5. The blower fan of claim 3, wherein the upper plate portion
includes an intake port axially overlapping with the blades and the
motor unit.
6. The blower fan of claim 1, wherein the ribs extend radially
outward from the upper surface portion of the curved portion.
7. The blower fan of claim 3, wherein the ribs are angled downward
as the ribs extend radially outward.
8. The blower fan of claim 1, wherein the curved portion further
includes a descending portion extending down from a radial outer
end portion of the upper surface portion, the ribs extending
radially outward from a lower end of the descending portion.
9. The blower fan of claim 6, wherein the ribs are perpendicular or
substantially perpendicular to the center axis.
10. The blower fan of claim 1, wherein the ribs extend radially
outward from the motor fixing portion, the curved portion being
provided in the outer edge portion of the motor fixing portion
between the ribs.
11. The blower fan of claim 1, wherein each of the blades includes
a lower edge including a straight portion extending from the outer
surface of the rotary unit in a direction perpendicular or
substantially perpendicular to the center axis, the upper surface
portion including a radial outer end portion radially positioned
between a radial outer end point of the straight portion and an
outer surface of the rotor magnet or radially positioned to
coincide with the outer surface of the rotor magnet.
12. The blower fan of claim 11, wherein the radial outer end
portion of the upper surface portion is positioned radially between
the outer surface of the rotary unit and the outer surface of the
rotor magnet or radially positioned to coincide with the outer
surface of the rotary unit or the outer surface of the rotor
magnet.
13. The blower fan of claim 1, wherein each of the blades includes
a lowermost portion positioned lower than the upper surface portion
of the curved portion.
14. The blower fan of claim 13, wherein the motor fixing portion is
positioned higher than the peripheral portion.
15. The blower fan of claim 1, wherein the curved portion includes
a portion extending upward from a radial outer end portion of the
upper surface portion.
16. The blower fan of claim 15, wherein the portion extending
upward from the radial outer end portion of the upper surface
portion is positioned radially outward of the rotor holder.
17. The blower fan of claim 1, wherein the motor unit further
includes a circuit board arranged above the motor fixing portion,
the motor fixing portion including hole portions or cutout portions
into which electronic parts mounted to the circuit board are
inserted.
18. The blower fan of claim 1, wherein the motor unit further
includes a circuit board arranged above the motor fixing portion,
the outer edge portion of the motor fixing portion including a
curved portion nonexistence region in which the curved portion is
not provided, the circuit board including an integrated circuit
positioned within the curved portion nonexistence region.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a blower fan arranged to
blow air.
[0003] 2. Description of the Related Art
[0004] Blower fans are conventionally arranged within the housings
of various kinds of electronic devices or home electric appliances.
For example, U.S. Patent Application Publication No. 2006-0273667
discloses a motor for use in a cooling fan or the like. The motor
includes a base, a rotor, and a balancing member as a magnetic
member. The balancing member is fixed to the upper surface of the
base and has a plurality of extension portions extending radially
outward. The rotor is arranged at the upper side of the base
through a bearing. In the motor, the ring-shaped magnet provided in
the rotor is axially opposed to the extension portion of the
balancing member. A magnetic attraction force is generated between
the extension portion and the magnet. This makes it is possible to
reduce vibration caused by the rotation of the motor.
[0005] In another conventional disk drive motor disclosed in
Japanese Patent Application Publication No. 2001-57755, a base
plate includes a disc-shaped base portion and a rotor guide piece
extending upward from the base portion. The rotor guide piece is
axially opposed to a ring-shaped permanent magnet of a rotor.
During rotation of the motor, a magnetic attraction force is
generated between the permanent magnet and the rotor guide piece.
The rotor makes stable rotation under the guidance of the rotor
guide piece. This makes it is possible to reduce rotational
vibration of the rotor. In a hard disk drive motor shown in FIG. 3
of Japanese Patent Application Publication No. 2005-192313, a
circumferentially-extending rib-shaped protrusion is formed in the
bottom portion of a base. The protrusion is vertically opposed to a
magnet portion of a rotor unit. During the rotation of the motor,
the lifting amount of the rotor unit can be adjusted by an
attraction force generated between the protrusion and the magnet
portion.
[0006] In a blower fan, however, a force may be applied to a rotary
unit in a direction that the rotary unit is moved away from a base
due to an impact applied from the outside and the vibration
generated during the operation of the blower fan. In this blower
fan, a magnetic member vertically opposed to the lower surface of a
rotor magnet is attached on the base whereby a magnetic attraction
force is generated between the magnetic member and the rotor
magnet. As a result, the rotary unit is prevented from moving in an
axial direction. However, a blower fan having an intake or exhaust
opening on the lower side thereof has a lower structure that is
more complex than a blower fan having no opening. For that reason,
if a magnetic member is provided in such a blower fan, the
complexity of the lower structure of the blower fan becomes even
greater and the number of parts required for the blower fan grows
higher.
SUMMARY OF THE INVENTION
[0007] Preferred embodiments of the present invention provide a
blower fan with an opening at a lower side thereof, which is
arranged to restrain axial movement of a rotary unit through the
use of a simple structure.
[0008] In accordance with a preferred embodiment of the present
invention, a blower fan includes a motor unit including a rotary
unit; a plurality of blades fixed to an outer surface of the rotary
unit of the motor unit and rotated about a center axis by the motor
unit; and a lower plate portion defined by a magnetic body and
positioned below the motor unit and the blades, wherein the lower
plate portion preferably includes a motor fixing portion to which
the motor unit is fixed, a curved portion provided in an outer edge
portion of the motor fixing portion, a peripheral portion and a
plurality of ribs arranged to interconnect the motor fixing portion
and the peripheral portion either directly or through the curved
portion, the curved portion being arranged below a rotor magnet of
the rotary unit to annularly extend about the center axis, the
curved portion including a standing portion extending upward from
the outer edge portion of the motor fixing portion and an upper
surface portion extending radially outward from an upper end of the
standing portion, a plurality of openings positioned below the
blades being defined by the curved portion, the peripheral portion
and the ribs.
[0009] With such a configuration, it is possible to restrain axial
movement of a rotary unit through the use of a simple
structure.
[0010] 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
[0011] FIG. 1 is a sectional view showing a blower fan according to
a preferred embodiment of the present invention.
[0012] FIG. 2 is a plan view of a lower plate portion of the blower
fan according to a preferred embodiment of the present
invention.
[0013] FIG. 3 is a partially enlarged sectional view of the blower
fan.
[0014] FIG. 4 is a partially enlarged plan view of the lower plate
portion.
[0015] FIG. 5 is a sectional view of a blower fan according to
another preferred embodiment of the present invention.
[0016] FIG. 6 is a sectional view of a blower fan according to a
further preferred embodiment of the present invention.
[0017] FIG. 7 is a sectional view of a blower fan according to
another further preferred embodiment of the present invention.
[0018] FIG. 8 is a perspective view of a lower plate portion
according to yet another further preferred embodiment of the
present invention.
[0019] FIG. 9 is a plan view of the lower plate portion shown in
FIG. 8.
[0020] FIG. 10 is a sectional view of a blower fan according to a
still further preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] In this description, the upper side along a center axis of a
motor in FIG. 1 will be just referred to as "upper" and the lower
side as "lower". The up-down direction is not intended to mean the
positional relationship or orientation of a blower fan with respect
to gravity when installed within an actual device. The direction
parallel or substantially parallel to the center axis will be
referred to as "axial", the direction perpendicular or
substantially perpendicular to the center axis will be referred to
as "radial", and the direction running around the center axis will
be referred to as "circumferential".
[0022] FIG. 1 is a sectional view showing a blower fan 1 according
to one preferred embodiment of the present invention. The blower
fan 1 is a centrifugal fan and is preferably used to cool
electronic parts arranged within, e.g., a notebook PC. The blower
fan 1 preferably includes a plurality of blades 11, a motor unit 12
and a housing 13. The blades 11 extend radially outward from the
motor unit 12. The blades 11 are rotated about a center axis J1 by
the motor unit 12.
[0023] The housing 13 accommodates the motor unit 12 and the blades
11. The housing 13 preferably includes an upper plate portion 131,
a lower plate portion 132, and a sidewall portion 133. The upper
plate portion 131 is preferably made of, for example, metal. The
upper plate portion 131 is positioned above the motor unit 12 and
the blades 11. The upper plate portion 131 preferably includes a
single intake port 151 axially overlapping with the blades 11 and
the motor unit 12. The intake port 151 will be hereinafter referred
to as "upper intake port 151". The upper intake port 151 has a
substantially circular shape about the center axis J1.
[0024] The lower plate portion 132 is preferably formed by pressing
a magnetic body, for example. The lower plate portion 132 is
positioned below the motor unit 12 and the blades 11. A plurality
of openings 152 arranged as intake ports are preferably defined in
the lower plate portion 132. The openings 152 will be hereinafter
referred to as "lower intake ports 152". The lower intake ports 152
are positioned below the blades 11. The sidewall portion 133 is
preferably made of, for example, resin. The sidewall portion 133
covers the side area of the blades 11. The upper plate portion 131
is fixed to the upper end of the sidewall portion 133 preferably
by, for example, screws or other fixing apparatus. The lower end of
the sidewall portion 133 is preferably combined with the lower
plate portion 132 by being embedded therein through, for example,
insert molding. In the blower fan 1, an exhaust port 153 shown at
the right side in FIG. 1 is defined by the upper plate portion 131,
the lower plate portion 132, and the sidewall portion 133. The
sidewall portion 133 may alternatively be provided by a method
other than insert molding and may be made of a material other than
resin.
[0025] The motor unit 12 is preferably an outer rotor type. The
motor unit 12 preferably includes a stationary unit 21 and a rotary
unit 22. The stationary unit 21 preferably includes a sleeve 23
arranged as a bearing, a bearing holder 24, a stator 210, and a
circuit board 25. The sleeve 23 includes a substantially
cylindrical shape about the center axis J1. The sleeve 23 is
preferably an oil-containing porous metal body. The bearing holder
24 preferably has a substantially cylindrical shape about the
center axis J1, the bearing holder 24 having a bottom. The bearing
holder 24 is arranged to hold the sleeve 23 therein. The bearing
holder 24 is preferably made of resin. The lower end of the bearing
holder 24 is combined, preferably through insert molding, with a
central hole portion 327 provided at the center of a motor fixing
portion 31. The bearing holder 24 may alternatively be formed by a
method other than insert molding and may be made of a material
other than resin if so desired.
[0026] The stator 210 preferably has a ring shape about the center
axis J1 and is attached to the outer surface of the bearing holder
24. The stator 210 preferably includes a stator core 211, an
insulator 212, and coils 213. The stator core 211 is preferably
formed by laminating thin silicon steel plates one above another,
but any other desirable stator forming method could be used
instead. The insulator 212 is preferably an insulating body
arranged to cover the surface of the stator core 211. The coils 213
are preferably defined by winding conductive wires on the insulator
212. The circuit board 25 is fixed to the lower portion of the
insulator 212. Thus, the lead wires extending from the stator 210
can be easily connected to the circuit board 25.
[0027] The rotary unit 22 preferably includes a shaft 221, a rotor
holder 222, a yoke 223, and a rotor magnet 224. The shaft 221 is
inserted into the sleeve 23 and is rotatably supported by the
sleeve 23. The rotor holder 222 preferably has a substantially
cylindrical shape about the center axis J1, the rotor holder 222
including a cover. The upper end portion of the shaft 221 is fixed
to the cover of the rotor holder 222. The blades 11 extend radially
outward from the outer surface 222a of the rotor holder 222. The
rotor holder 222 and the blades 11 are preferably provided as a
single monolithic member. In other words, the blades 11 are kept
fixed to the outer surface 222a of the rotor holder 222. A portion
111 of a lower edge 11a of each of the blades 11 adjoining to the
center axis J1 extends from the outer surface 222a of the rotor
holder 222 in a perpendicular or substantially perpendicular
relationship with the center axis J1. The portion 111 will be
hereinafter referred to as "straight portion 111". A radial outer
portion 112 of the lower edge 11a is positioned lower than the
straight portion 111. The shape of an upper edge 11b of each of the
blades 11 is the same or substantially the same as the vertically
inverted shape of the lower edge 11a.
[0028] The yoke 223 has a substantially cylindrical shape about the
center axis J1 and is fixed to the inner surface of the rotor
holder 222. The rotor magnet 224 has a substantially cylindrical
shape about the center axis J1 and is fixed to the inner surface of
the yoke 223.
[0029] In the motor unit 12, electric power is supplied to the
stator 210 whereby a torque about the center axis J1 is generated
between the rotor magnet 224 and the stator 210. Thus, the rotary
unit 22 and the blades 11 are rotated about the center axis J1.
Upon rotation of the blades 11, air is drawn into the housing 13
through the upper intake port 151 and the lower intake ports 152
and is discharged through the exhaust port 153.
[0030] FIG. 2 is a plan view of the lower plate portion 132. The
upper side in FIG. 2 corresponds to the right side in FIG. 1. The
lower plate portion 132 preferably includes a motor fixing portion
31, a curved portion 32, a plurality of ribs 33, and a peripheral
portion 34. The motor fixing portion 31 has a substantially
circular shape. The motor unit 12 is fixed to the motor fixing
portion 31. The motor fixing portion 31 includes a plurality of
circular small hole portions 313 and a large hole portion 314
defined around a central hole portion 327.
[0031] The curved portion 32 is provided in the outer edge portion
311 of the motor fixing portion 31. When seen in a plan view, the
curved portion 32 extends annularly about the center axis J1. A
certain region 312 of the outer edge portion 311 of the motor
fixing portion 31 preferably has a radially inwardly cut shape. The
curved portion 32 is not present in the region 312. The region 312
will be hereinafter referred to as "curved portion nonexistence
region 312".
[0032] FIG. 3 is a sectional view showing the portions of the
blower fan 1 positioned below the rotor magnet 224. The curved
portion 32 preferably includes a standing portion 321 and an upper
surface portion 322. The standing portion 321 extends upward from
the outer edge portion 311 of the motor fixing portion 31. The
upper surface portion 322 extends radially outward from the upper
end of the standing portion 321.
[0033] A radial outer end portion 322a of the upper surface portion
322 is positioned between the outer surface 222a of the rotor
holder 222 and the outer surface 224a of the rotor magnet 224 in
the radial direction. The radial outer portion 112 of the lower
edge 11a of each of the blades 11, i.e., the lowermost portion of
each of the blades 11, is positioned lower than the upper surface
portion 322.
[0034] As shown in FIG. 2, the ribs 33 are arranged at a regular
interval in the circumferential direction. When seen in a plan
view, the ribs 33 are angled with respect to the radial direction.
As illustrated in FIG. 3, the ribs 33 are angled downward as they
extend radially outward from the radial outer end portion 322a of
the upper surface portion 322. The angle of inclination of the ribs
33 with respect to the horizontal direction makes it is possible to
reduce the draft resistance caused by the ribs 33. The ribs 33
interconnect the motor fixing portion 31 and the peripheral portion
34 through the curved portion 32. The peripheral portion 34 is
positioned lower than the upper surface portion 322 of the curved
portion 32 in the axial direction. The radial outer end portion of
the peripheral portion 34 is fixed to the lower end portion of the
sidewall portion 133 shown in FIG. 1. As can be seen in FIGS. 2 and
3, the lower intake ports 152 are defined in the lower plate
portion 132 by the curved portion 32, the ribs 33 and the
peripheral portion 34.
[0035] The outer shape of the upper plate portion 131 shown in FIG.
1 is substantially the same as the outer shape of the lower plate
portion 132 from which the motor fixing portion 31, the curved
portion 32 and the ribs 33 are removed.
[0036] FIG. 4 is an enlarged plan view of the motor fixing portion
31. As indicated by double-dot chain lines in FIG. 4, the circuit
board 25 preferably includes a circular portion 251 and a
projection portion 252. The circular portion 251 is positioned
inside the curved portion and above the motor fixing portion 31.
The axial position of the circuit board 25 is substantially the
same as the axial position of the curved portion 32 in the axial
direction. The projection portion 252 protrudes from the circular
portion 251 toward the curved portion nonexistence region 312. An
integrated circuit 26 is attached to the lower surface of the
projection portion 252 and is positioned within the curved portion
nonexistence region 312. Electronic parts and downwardly protruding
pins (not shown) are preferably positioned on the lower surface of
the circular portion 251 in an opposing relationship with the hole
portions 313 and 314 of the motor fixing portion 31. If necessary,
the electronic parts and the pins are inserted into the hole
portions 313 and 314. By providing the hole portions 313 and 314,
it is possible to avoid interference of the motor fixing portion 31
with the circuit board 25 having electronic parts and the like and
allows the motor fixing portion 31 and the circuit board 25 to come
close to each other. As a result, it becomes possible to reduce the
thickness of the blower fan 1.
[0037] As shown in FIG. 3, the rotor magnet 224 is arranged to be
axially opposed to the upper surface portion 322 of the curved
portion 32. A magnetic attraction force is generated between the
rotor magnet 224 and the upper surface portion 322. Since the upper
surface portion 322 substantially annularly extends about the
center axis J1, the magnetic attraction force is substantially
uniformly generated in the circumferential direction between the
rotor magnet 224 and the upper surface portion 322. Accordingly, it
is possible to prevent upward movement of the rotary unit 22 even
if an upwardly-acting force, i.e., a force pulling the rotary unit
22 away from the motor fixing portion 31, is exerted on the rotary
unit 22 due to the impact applied from the outside or the vibration
generated during the operation of the blower fan 1. As a result,
the rotary unit 22 is prevented from fluctuating.
[0038] As described above, by providing the curved portion 32 in
the blower fan 1, it is possible to easily generate a thrust load
acting on the rotary unit 22. As compared with a blower fan in
which a magnetic member vertically opposed to a rotor magnet is
additionally provided on a motor fixing portion, it is possible to
prevent axial movement of the rotary unit 22 through the use of a
simple structure. It is also possible to reduce the number of parts
and the manufacturing cost. As compared with a blower fan provided
with a magnetic member, it is possible to reduce the thickness of
the blower fan 1. Since a thrust load is applied to the rotary unit
22 in the blower fan 1, it is possible to reduce electromagnetic
noises as compared with a case of using a so-called magnetic offset
by which the axial magnetic center of the stator 210 is offset
downward from the magnetic center of the rotor magnet 224. While it
is preferred in the blower fan 1 that the magnetic center of the
stator 210 axially coincides with the magnetic center of the rotor
magnet 224, the magnetic offset may be used in combination insofar
as electromagnetic noises do not matter.
[0039] Since the ribs 33 extend radially outward from the upper
surface portion 322 of the curved portion 32, it is possible to
place the curved portion 32 in the formation positions of the ribs
33. This makes it is possible to sufficiently generate a magnetic
attraction force between the rotor magnet 224 and the upper surface
portion 322 positioned below the rotor magnet 224. Since the ribs
33 are angled downward as they extend radially outward, it is
possible to secure a space for the radial outer portions of the
blades 11. Since the lowermost portion of the lower edge 11a of
each of the blades 11 is positioned lower than the upper surface
portion 322, it is possible to increase the blade area and the air
intake and exhaust amount. Due to the fact that the radial inner
portions of the ribs 33 are positioned higher than the motor fixing
portion 31 and peripheral portion 34, it is possible to broaden the
air flow path at the lower side of the blower fan 1 and to
efficiently perform the intake of air through the lower intake
ports 152.
[0040] Preferably, the radial outer end portion 322a of the upper
surface portion 322 is provided radially between a radial outer end
point 111a of the straight portion 111 of each of the blades 11 and
the outer surface 224a of the rotor magnet 224 as shown in FIG. 3.
The position of the radial outer end portion 322a may radially
coincide with the position of the outer surface 224a of the rotor
magnet 224. This makes it is possible to sufficiently secure the
magnetic action while reducing the draft resistance. More
preferably, the radial outer end portion 322a is positioned between
the outer surface 222a of the rotor holder 222 and the outer
surface 224a of the rotor magnet 224. Alternatively, the position
of the radial outer end portion 322a may radially coincide with the
position of the outer surface 222a of the rotor holder 222 or the
position of the outer surface 224a of the rotor magnet 224. This
makes it is possible to further reduce the draft resistance. This
holds true in another preferred embodiment of the lower plate
portion to be described below.
[0041] FIG. 5 is a view showing another preferred embodiment of the
lower plate portion. A lower plate portion 132a is provided with an
upwardly-raised curved portion 32a. The curved portion 32a
preferably includes a standing portion 321, an upper surface
portion 322 and a descending portion 323. The standing portion 321
extends upward from the outer edge portion 311 of the motor fixing
portion 31. The upper surface portion 322 extends radially outward
from the upper end of the standing portion 321. The descending
portion 323 extends downward from the radial outer end of the upper
surface portion 322. The ribs 33 extend radially outward from the
lower end of the descending portion 323.
[0042] The curved portion 32a extends substantially annularly about
the center axis J1 at the lower side of the rotor magnet 224. A
magnetic attraction force is substantially uniformly generated in
the circumferential direction between the rotor magnet 224 and the
upper surface portion 322. By providing the curved portion 32a in
the blower fan 1, it is possible to substantially prevent axial
movement of the rotary unit 22 through the use of a simple
structure.
[0043] In the lower plate portion 132a, the ribs 33 are connected
to the lower end of the descending portion 323, whereby the entire
portions of the ribs 33 can be positioned sufficiently lower than
the upper surface portion 322. As a result, it is possible to
easily secure a space for the blades 11. The radial outer portion
112 of the lower edge 11a of each of the blades 11 is positioned
lower than the upper surface portion 322 of the curved portion 32.
It is therefore possible to increase the blade area and the air
intake and exhaust amount.
[0044] FIG. 6 is a view showing a further preferred embodiment of
the lower plate portion. In a lower plate portion 132b, the ribs 33
extend from the upper surface portion 322 of the curved portion 32
in a perpendicular or substantially perpendicular relationship with
the center axis J1. A radial inner portion 341 of the peripheral
portion 34 extends upward and is connected to the radial outer end
portions of the ribs 33.
[0045] In the lower plate portion 132b, the ribs 33 connected to
the upper surface portion 322 are perpendicular or substantially
perpendicular to the center axis J1, whereby the entire portions of
the ribs 33 can be positioned above the motor fixing portion 31 and
the peripheral portion 34. Thus, a space 154 is defined below the
ribs 33. If the blower fan 1 is arranged in a narrow space within a
device, the motor fixing portion 31 and the peripheral portion 34
adjoin to the inner surface 9 of the device. Since air is guided
from the space 154 toward the lower intake ports 152, it is
possible to efficiently perform the intake of the air through the
lower intake ports 152. Inasmuch as the ribs 33 are positioned
closer to the portion of the outer surface 222a of the rotor holder
222 from which the blades 11 extend, it is possible to reduce the
draft resistance caused by the ribs 33.
[0046] FIG. 7 is a view showing a still further preferred
embodiment of the lower plate portion. In a lower plate portion
132c, the motor fixing portion 31 is positioned higher than the
peripheral portion 34. When the peripheral portion 34 adjoins to
the inner surface 9 of a device, a large space 155 is defined
between the motor fixing portion and the inner surface 9.
Accordingly, even when the blower fan 1 is arranged in a narrow
space of a device, it is possible to efficiently perform the intake
of air through the lower intake ports 152. The existence of the
space 155 at the lower side of the motor fixing portion 31 makes it
is possible to reduce the draft resistance caused by the motor
fixing portion 31 and the ribs 33. In the lower plate portion 132c,
the peripheral portion 34 is largely spaced apart downward from the
rotary unit 22. It is therefore possible to easily secure a space
for the blades 11.
[0047] FIG. 8 is a perspective view showing a still further
preferred embodiment of the lower plate portion. The sidewall
portion 133 fixed to the lower plate portion 132d is also shown in
FIG. 8. FIG. 9 is a plan view of the lower plate portion 132d and
the sidewall portion 133. The upper side in FIG. 9 corresponds to
the left lower side in FIG. 8. The lower plate portion 132d
preferably includes a circular motor fixing portion 31, a plurality
of bent pieces 35, a plurality of ribs 33, and a peripheral portion
34. The ribs 33 extend radially outward from the outer edge portion
311 of the motor fixing portion 31. Each of the bent pieces 35
preferably includes a standing portion 351 and an upper surface
portion 352. The standing portion 351 is provided in the outer edge
portion 311 of the motor fixing portion 31 between the adjoining
ribs 33 and extends upward from the outer edge portion 311. The
upper surface portion 322 has an arc shape about the center axis J1
and extends radially outward from the upper end of the standing
portion 351.
[0048] In the lower plate portion 132d, the bent pieces 35 are
arranged on the outer edge portion 311 of the motor fixing portion
31 at a regular interval in the circumferential direction, thereby
forming a curved portion 32b having a substantially ring shape
about the center axis J1. When the blower fan 1 is assembled, the
curved portion 32b is positioned below the rotor magnet 224. A
magnetic attraction force is generated between the curved portion
32b and the rotor magnet 224. This makes it is possible to prevent
the rotary unit 22 from moving upward.
[0049] In the lower plate portion 132d, the ribs 33 directly
interconnect the motor fixing portion 31 and the peripheral portion
34. Therefore, the ribs 33 can be made flush with the motor fixing
portion 31 and the peripheral portion 34. As a result, it is
possible to easily secure a space for the blades 11 at the upper
side of the ribs 33.
[0050] While certain preferred embodiments of the present invention
have been described above, the present invention is not limited to
the foregoing preferred embodiments but may be modified in many
different forms. For example, as shown in FIG. 10, a portion 324
extending upward from the radial outer end portion of the upper
surface portion 322 may be provided in the curved portion 32. In
this case, the rotor magnet 224 protrudes downward beyond the rotor
holder 222, whereby a magnetic attraction force can be generated
between the lower portion of the rotor magnet 224 and the portion
324 of the curved portion 32 in the radial direction. It is
therefore possible to reliably prevent the rotary unit 22 from
moving upward. In FIG. 10, the portion 324 may be positioned a
little radially outward of the rotor holder 222. In this case,
downwardly-flowing air is guided into the motor unit 12 through a
space between the curved portion 32 and the rotor holder 222,
thereby cooling, for example, the circuit board 25.
[0051] In the motor fixing portion 31, cutout portions arranged to
receive electronic parts and the like arranged on the lower surface
of the circuit board 25 may be provided in place of the hole
portions 313 and 314. While three ribs are preferably included in
the foregoing preferred embodiments, the number of the ribs 33 may
be two or any other number greater than three if so desired.
[0052] In the blower fan 1, the upper plate portion 131 may be
formed by die-casting aluminum, zinc, or other metals or may be
molded resin, for example. In these cases, the upper plate portion
131 may be formed into an outer shape greatly differing from that
of the lower plate portion 132. If the upper plate portion 131 is
made of molded resin, it is preferred that the upper plate portion
131 be continuously joined to the sidewall portion 133. The
technique of preventing movement of the rotary unit 22 through the
use of the curved portion 32, 32a, or 32b may be applied to a
blower fan in which air is drawn through only the lower intake
ports 152. This technique may also be applied to a fan that does
not have the upper plate portion 131 and the sidewall portion 133.
In this case, the members of a device accommodating the blower fan
1 serve as a sidewall portion and an upper plate portion. The
technique of preventing movement of the rotary unit 22 through the
use of the curved portion 32, 32a, or 32b may be applied to other
blower fans such as an axial flow fan.
[0053] The configurations of the foregoing preferred embodiments
and the modified examples may be appropriately combined unless
contradictory to one another.
[0054] The blower fan according to the present invention can be
used in cooling electronic parts within a housing or in feeding air
to different objects. Moreover, the blower fan can be used for
other purposes.
[0055] 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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