U.S. patent application number 11/223113 was filed with the patent office on 2006-03-23 for blower.
Invention is credited to Masahiro Miura, Tomomasa Nishikawa, Junichi Sudou.
Application Number | 20060062669 11/223113 |
Document ID | / |
Family ID | 36074195 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060062669 |
Kind Code |
A1 |
Nishikawa; Tomomasa ; et
al. |
March 23, 2006 |
Blower
Abstract
A casing is provided with an outer frame defining an internal
space and with a partition dividing the internal space into a fan
housing and a motor housing. The outer frame is formed with an
inlet and an outlet allowing fluid communication between the fan
housing and an exterior. The imaginary rotational axis of the fan
is substantially coincident with the imaginary central axis of the
inlet. The fan is positioned between the inlet and the motor. The
fan includes a mount portion mounted on the drive shaft, a
generally circular base plate formed integrally with the mount
portion, and a plurality of vanes protruding from the base plate
toward the inlet. The outer frame includes a slanted portion
adjacent to the inlet and slanted in such a manner that a distance
between the slanted portion and the imaginary central axis is
gradually reduced in a direction toward the inlet.
Inventors: |
Nishikawa; Tomomasa;
(Hitachinaka-shi, JP) ; Sudou; Junichi;
(Hitachinaka-shi, JP) ; Miura; Masahiro;
(Hitachinaka-shi, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Family ID: |
36074195 |
Appl. No.: |
11/223113 |
Filed: |
September 12, 2005 |
Current U.S.
Class: |
415/206 |
Current CPC
Class: |
F04D 29/281 20130101;
F04D 25/06 20130101; F04D 27/008 20130101 |
Class at
Publication: |
415/206 |
International
Class: |
F04D 29/44 20060101
F04D029/44 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2004 |
JP |
P2004-272014 |
Claims
1. A blower comprising: a casing provided with an outer frame
defining an internal space and with a partition dividing the
internal space into a fan housing and a motor housing, the outer
frame being formed with an inlet allowing fluid communication
between the fan housing and an exterior for sucking fluid into the
fan housing therethrough, and an outlet allowing fluid
communication between the fan housing and the exterior for
discharging fluid from the fan housing to the exterior
therethrough, the inlet having an imaginary central axis; a motor
disposed in the motor housing and having a drive shaft that extends
into the fan housing; and a fan disposed in the fan housing and
rotatable about an imaginary rotational axis by the motor, the
imaginary rotational axis being substantially coincident with the
imaginary central axis of the inlet, the fan being positioned
between the inlet and the motor, the fan comprising: a mount
portion mounted on the drive shaft; a generally circular base plate
formed integrally with the mount portion; and a plurality of vanes
protruding from the base plate toward the inlet, wherein the outer
frame comprises a slanted portion adjacent to the inlet and slanted
in such a manner that a distance between the slanted portion and
the imaginary central axis is gradually reduced in a direction
toward the inlet.
2. The blower according to claim 1, wherein each vane has an edge
on a side opposite from the motor; and wherein at least part of the
edge is slanted in such a manner that a distance between the at
least part of the edge and the imaginary central axis is gradually
reduced in a direction toward the inlet, allowing the at least part
of the edge to be substantially parallel to the slanted
portion.
3. The blower according to claim 1, wherein each vane has an edge
on a side opposite from the motor; and wherein the edge and the
slanted portion have a space therebetween allowing the edge and the
slanted portion to contact each other when the fan deforms during
rotation.
4. The blower according to claim 3, wherein the deformation of the
fan is caused when the motor rotates at an abnormal speed.
5. The blower according to claim 4, wherein the motor rotates at
the abnormal speed when a voltage greater than a rated voltage is
applied to the motor.
6. The blower according to claim 1, wherein the fan defines a
radial direction; and wherein the plurality of vanes extends in a
direction slanted with respect to the radial direction.
7. A blower comprising: a casing provided with an outer frame
defining an internal space and with a partition dividing the
internal space into a fan housing and a motor housing, the outer
frame being formed with an inlet allowing fluid communication
between the fan housing and an exterior for sucking fluid into the
fan housing therethrough, and an outlet allowing fluid
communication between the fan housing and the exterior for
discharging fluid from the fan housing to the exterior
therethrough, the inlet having an imaginary central axis; a motor
disposed in the motor housing and having a drive shaft that extends
into the fan housing; and a fan disposed in the fan housing and
rotatable about an imaginary rotational axis by the motor, the
imaginary rotational axis being substantially coincident with the
imaginary central axis of the inlet, the fan being positioned
between the inlet and the motor, the fan comprising: a mount
portion mounted on the drive shaft; a generally circular base plate
formed integrally with the mount portion; and a plurality of vanes
protruding from the base plate toward the inlet, wherein, when the
fan deforms during rotation, the base plate is contactable with the
partition and the plurality of vanes is contactable with the outer
frame.
8. The blower according to claim 7, wherein the fan defines a
radial direction; and wherein the plurality of vanes extends in a
direction slanted with respect to the radial direction.
9. The blower according to claim 7, wherein the deformation of the
fan is caused when the motor rotates at an abnormal speed.
10. The blower according to claim 9, wherein the motor rotates at
the abnormal speed when a voltage greater than a rated voltage is
applied to the motor.
11. The blower according to claim 7, wherein the outer frame
comprises a slanted portion adjacent to the inlet and slanted in
such a manner that a distance between the slanted portion and the
imaginary central axis is gradually reduced in a direction toward
the inlet.
12. The blower according to claim 11, wherein each vane has an edge
on a side opposite from the motor; and wherein at least part of the
edge is slanted in such a manner that a distance between the at
least part of the edge and the imaginary central axis is gradually
reduced in a direction toward the inlet, allowing the at least part
of the edge to be substantially parallel to the slanted
portion.
13. The blower according to claim 12, wherein the edge comprises
another part slanted in such a manner that a distance between the
another part of the edge and the imaginary central axis is
gradually increased in a direction toward the inlet; wherein the at
least part of the edge and the another part of the edge join
together to form a tip portion; and wherein the tip portion is
contactable with the slanted portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a blower, and more
particularly, to such portable blower having a blower mode to blow
away dust and the like, and a vacuum mode to suck in air to perform
dust collection or the like.
[0003] 2. Description of Related Art
[0004] One conventional blower is described in Japanese
patent-application publication No. 2002-339898. FIG. 7 shows the
structure of a conventional blower 101. As shown in FIG. 7, the
blower 101 includes an electric motor 108, a casing 105 having an
inlet 103 and an outlet 104, and a fan 106 disposed inside the
casing 105. When the motor 108 drives the fan 106 to rotate, the
fan 106 draws air through the inlet 103 and blows the air out
through the outlet 104.
[0005] The blower 101 can be used to perform blowing operations by
attaching a nozzle (not shown) to the outlet 104 and blowing fallen
leaves, wood chips, and the like with the air emitted through the
nozzle. The blower 101 can also be used for suction operations by
attaching a dust-collecting bag (not shown) to the outlet 104 and
attaching a nozzle or a hose (not shown) to the inlet 103 so that
small wood chips or the like can be drawn through the inlet 103 and
collected in the bag.
[0006] As shown in FIG. 7, the casing 105 of the blower 101 is
configured of three casing segments 105A, 105B, and 105C. In
addition to the inlet 103 and outlet 104, the casing 105 has a
motor housing for accommodating the motor 108, and a fan housing
for accommodating the fan 106. The motor housing is defined by the
casing segments 105A and 105B, while the fan housing is defined by
the casing segments 105B and 105C, which are joined by a fastening
member 117. A handle 102 is provided on the casing segment 105A for
enabling a user to grip the blower 101.
[0007] The inlet 103 is formed on the casing segment 105C and
protrudes along the rotational axis of the fan 106 in a direction
away from the motor 108. The inlet 103 is positioned so as to be
substantially coaxial with the rotational axis of the fan 106. The
inlet 103 includes ribs 103B to prevent large foreign matter from
entering the casing 105, and openings 103a formed between the ribs
103B and in fluid communication with the fan housing.
[0008] The outlet 104 is also in fluid communication with the fan
housing and is formed in a cylindrical shape by the casing segments
105B and 105C that protrude tangentially from the fan 106. An
attachment portion 113 is provided on the protruding end of the
casing segments 105B and 105C. For blowing operations, the nozzle
or hose is attached to the attachment portion 113.
[0009] The fan 106 is positioned between the inlet 103 and the
motor 108. The fan 106 includes a mount portion 106A that is
mounted on a drive shaft 107 of the motor 108, a base plate 106B
that is substantially circular or disc-shaped and formed integrally
with the mount portion 106A, and a plurality of vanes 106C
connected with the mount portion 106A and the base plate 106B and
positioned on the inlet 103 side of the base plate 106B.
SUMMARY
[0010] In the conventional blower 101 described above, the casing
segment 105C near the inlet 103 is formed to extend substantially
orthogonal to the rotational axis of the fan 106. The inlet 103 is
disposed on the casing segment 105C so that the central axis of the
inlet 103 is substantially coincident (coaxial) with the rotational
axis of the fan 106.
[0011] With the above-described construction, air is drawn into the
fan housing through the inlet 103, as indicated by an arrow A11.
The air then passes through spaces between the mount portion 106A
of the fan 106 and the inner surface of the casing segment 105C, as
indicated by arrows A12. However, since the casing 105 near the
inlet 103 extends orthogonal to the rotational axis of the fan 106,
as described above, the spaces between the mount portion 106A and
the inner surface of the casing segment 105C are small and produce
a large flow resistance.
[0012] Further, after passing through these spaces in the direction
of flow indicated by the arrows A12, the air changes direction to
flow perpendicular to the rotational axis of the fan 106 along the
inner surface of the casing segment 105C, as indicated by arrows
A13, producing a large flow resistance.
[0013] If the motor 108 rotates at an abnormal speed due to a
supplied voltage greater than the rated voltage, an abnormally
large centrifugal force will be applied to the fan 106, causing the
fan 106 to deform so that the base plate 106B and the vanes 106C
gravitate toward the casing segment 105B on the motor 108 side.
When this occurs, the base plate 106B of the fan 106 contacts the
inner surface of the casing segment 105B, thereby decelerating or
stopping the abnormal rotation of the fan 106. However, since the
contact with the base plate 106B of the fan 106 applies a large
force to the casing segment 105B, it is necessary to increase the
thickness and enhance the strength of the casing segment 105B.
These changes to the casing segment 105B increase the overall
weight of the blower 101, making the blower 101 more difficult to
operate.
[0014] In view of the foregoing, it is an object of the present
invention to provide a blower having a large suction capacity and a
large blowing capacity. It is another object of the present
invention to provide a blower that is easy to operate and that can
reduce the amount of deformation in the fan during abnormal
rotations and the like.
[0015] In order to attain the above and other objects, according to
one aspect, the present invention provides a blower. The blower
includes a casing, a motor, and a fan. The casing is provided with
an outer frame defining an internal space and with a partition
dividing the internal space into a fan housing and a motor housing.
The outer frame is formed with an inlet allowing fluid
communication between the fan housing and an exterior for sucking
fluid into the fan housing therethrough, and an outlet allowing
fluid communication between the fan housing and the exterior for
discharging fluid from the fan housing to the exterior
therethrough. The inlet has an imaginary central axis. The motor is
disposed in the motor housing and has a drive shaft that extends
into the fan housing. The fan is disposed in the fan housing and is
rotatable about an imaginary rotational axis by the motor. The
imaginary rotational axis is substantially coincident with the
imaginary central axis of the inlet. The fan is positioned between
the inlet and the motor. The fan includes a mount portion mounted
on the drive shaft, a generally circular base plate formed
integrally with the mount portion, and a plurality of vanes
protruding from the base plate toward the inlet. The outer frame
includes a slanted portion adjacent to the inlet and slanted in
such a manner that a distance between the slanted portion and the
imaginary central axis is gradually reduced in a direction toward
the inlet.
[0016] According to another aspect, the present invention provides
a blower. The blower includes a casing, a motor, and a fan. The
casing is provided with an outer frame defining an internal space
and with a partition dividing the internal space into a fan housing
and a motor housing. The outer frame is formed with an inlet
allowing fluid communication between the fan housing and an
exterior for sucking fluid into the fan housing therethrough, and
an outlet allowing fluid communication between the fan housing and
the exterior for discharging fluid from the fan housing to the
exterior therethrough. The inlet has an imaginary central axis. The
motor is disposed in the motor housing and has a drive shaft that
extends into the fan housing. The fan is disposed in the fan
housing and is rotatable about an imaginary rotational axis by the
motor. The imaginary rotational axis is substantially coincident
with the imaginary central axis of the inlet. The fan is positioned
between the inlet and the motor. The fan includes a mount portion
mounted on the drive shaft, a generally circular base plate formed
integrally with the mount portion, and a plurality of vanes
protruding from the base plate toward the inlet. When the fan
deforms during rotation, the base plate is contactable with the
partition and the plurality of vanes is contactable with the outer
frame.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other objects, features and advantages of the
invention will become more apparent from reading the following
description of the embodiments taken in connection with the
accompanying drawings in which:
[0018] FIG. 1 is a front view with a partial cross-section showing
a blower according to an embodiment of the present invention;
[0019] FIG. 2 is a side view with a partial cross-section showing
the blower according to the embodiment;
[0020] FIG. 3 is a perspective view showing a fan of the blower
according to the embodiment;
[0021] FIG. 4 is a plan view showing the fan of the blower
according to the embodiment;
[0022] FIG. 5 is a cross-sectional view of the fan taken along a
line V-V in FIG. 4;
[0023] FIG. 6 is an enlarged cross-sectional view illustrating the
relationship between a casing and the fan of the blower according
to the embodiment; and
[0024] FIG. 7 is a side view with a partial cross-section showing a
conventional blower.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] A blower 1 according to an embodiment of the present
invention will be described with reference to FIGS. 1 through 6.
The embodiment pertains to a compact and light-weight portable
blower also serving as a dust collector. The blower 1 includes a
casing 5 formed with an inlet 3 for sucking in air and an outlet 4
for blowing out air. The casing 5 has a handle 2 to be gripped by a
user's hand.
[0026] An electric motor 8 (FIG. 2) and a centrifugal fan 6 are
installed in the casing 5. The centrifugal fan 6 is drivingly
coupled to the electric motor 8 via a drive shaft 7 (FIG. 2)
described later, and is rotated by the rotation of the electric
motor 8. Air is sucked into the casing 5 through the inlet 3, and
is blown out through the outlet 4 by the centrifugal force
established by the rotation of the centrifugal fan 6. The outlet 4
is in fluid communication with a fan housing space 5g formed in the
casing 5, and is located on a tangential line of a base plate 6B
(FIG. 2) of the centrifugal fan 6 disposed in the fan housing space
5g. The outlet 4 is configured in a cylindrical shape by casing
segments 5B and 5C (FIG. 2) of the casing 5.
[0027] A portion around the outlet 4 serves as an attachment
portion 13 to which accessories such as a dust collection bag (not
shown) or a nozzle 20 is selectively attached. The inlet 3 has a
generally arcuate shape and is positioned in confrontation with and
coaxially with the centrifugal fan 6.
[0028] As shown in FIG. 1, when the blower 1 is used in a blower
mode to blow away dusts, fallen leaves, wood chips, etc., the
nozzle 20 or a hose (not shown) is attached to the attachment
portion 13 of the casing 5, while nothing is attached to the inlet
3. Blowing operation can be performed by directing the tip of the
nozzle 20 toward the dusts, small wood chips or other such objects
and blowing out pressurized air through the nozzle 20.
Incidentally, even without the nozzle 20 blowing operation can
still be performed by directing the outlet 4 toward the target and
blowing air out from the outlet 4.
[0029] Furthermore, when the blower 1 is to be operated in a
suction mode to collect dusts, wood chips, etc., the dust
collection bag (not shown) is attached to the attachment portion 13
of the casing 5, while a nozzle or a hose (not shown) is attached
to the inlet 3. Suction operation can be performed by directing the
tip of the nozzle or the hose toward dusts, small wood chips, or
other such objects and then sucking in the objects into the dust
collection bag.
[0030] The construction of the blower 1 is described in greater
detail with reference to FIG. 2. As shown in FIG. 2, the casing 5
is configured of three casing segments 5A, 5B, and 5C. The mutually
opposing casing segment 5B and casing segment 5C define the fan
housing space 5g for installing therein the centrifugal fan 6. The
casing segment 5B includes a circular partition 51 partitioning the
fan housing space 5g from a motor housing space 5f (described
later) and a peripheral wall 52. The casing segment 5B has a
bearing holder 53 for accommodating a bearing 18. The centrifugal
fan 6 is concentrically mounted on the drive shaft 7.
[0031] Note that part of the casing segments 5A, 5B, and 5C serves
as an outer frame (outer casing) which defines an internal space
therein. The partition 51 divides the internal space into the fan
housing space 5g and the motor housing space 5f.
[0032] A drive shaft through-hole 5k is formed at the center of the
circular partition 51 and within the bearing holder 53 for allowing
the drive shaft 7 to extend therethrough into the fan housing space
5g.
[0033] The casing segment 5A is connected to the casing segment 5B
with a bolt or the like at a position opposite to the fan housing
space 5g with respect to the partition 51. The casing segment 5A
has generally cylindrical cup shape and is coaxial with the
centrifugal fan 6. A bottom of the cup serves as an end wall of the
casing 5, and an open end of the casing segment 5A is fitted to the
casing segment 5B. Thus, the casing segment 5A defines therein a
motor housing space 5f where the electric motor 8 is supported. The
partition 51 separates the fan housing space 5g from the motor
housing space 5f. A bearing 19 is supported at a distal end of the
casing segment 5A. Thus, the drive shaft 7 is rotatably supported
to the casing 5 through these bearings 18 and 19.
[0034] The casing segment 5C is coupled to the casing segment 5B by
a fastening member 17 at a parting face 5M extending in a direction
perpendicular to the axis of the drive shaft 7. The casing segment
5C includes an end wall section in confrontation with the partition
51 of the casing segment 5B, and a peripheral wall 54 corresponding
to the peripheral wall 52 of the casing segment 5B. By the
combination of the casing segment 5B and the casing segment 5C,
single fan housing space 5g is provided. More specifically, the
partition 51, the peripheral wall 52 of the casing segment 5B, and
the end wall section and the corresponding peripheral wall 54 of
the casing segment 5C provide the fan housing space 5g.
[0035] The above-described inlet 3 is formed in the casing segment
5C coaxially with the centrifugal fan 6. A sleeve like protrusion
56 protrudes from the inlet 3 in the axial direction of the fan 6.
Thus, the nozzle or other accessory is detachably attached to the
sleeve like protrusion 56.
[0036] As described above, the inlet 3 is formed at an axial end of
the casing segment 5C and protrudes along the rotational axis RA of
the fan 6 in a direction away from the motor 8. The inlet 3 has an
imaginary central axis CA which is substantially coincident with
the rotational axis RA of the fan 6. In other words, the inlet 3 is
substantially coaxial with the fan 6. Ribs 3B are provided in the
inlet 3 to prevent large foreign matter from entering the casing 5.
Openings 3a are formed between the ribs 3B and are in fluid
communication with the fan housing space 5g.
[0037] As shown in FIGS. 2 and 6, the casing 5 (the casing segment
5C) near the inlet 3 has a slanted portion 55 that slants away from
the motor 8 in a direction toward the central axis CA. In other
words, the slanted portion 55 is positioned adjacent to the inlet 3
and slanted in such a manner that a distance D between the slanted
portion 55 and the central axis CA is gradually reduced in a
direction toward the inlet 3. Further, the slanted portion 55 has a
curved inner surface 5D.
[0038] As shown in FIGS. 3 and 4, the centrifugal fan 6 includes a
mount portion 6A, the base plate 6B, and a plurality of vanes 6C.
The base plate 6B is substantially circular or disc-shaped and is
formed integrally with the mount portion 6A. The drive shaft 7 is
fixed to the mount portion 6A by force-fitting or using fasteners
such as a nut. The plurality of vanes 6C protrudes from one surface
61 of the base plate 6B. The plurality of vanes 6C is also
connected with the mount portion 6A. The base plate 6B has an
opposite surface 62 positioned in direct confrontation with the
circular partition 51 (FIG. 2) of the casing segment 5B.
[0039] A plurality of through-holes 63 is formed in the base plate
6B. Each through-hole 63 is positioned between neighboring vanes
6C, and is positioned in an imaginary circle whose center is
coincident with the axis of the drive shaft 7.
[0040] As shown in FIG. 4, the vanes 6C are slanted with respect to
the radial direction of the fan 6. The vanes 6C curl to be convex
toward a rotational direction R of the fan 6 (the rotational
direction R is counterclockwise in FIGS. 3 and 4).
[0041] As shown in FIGS. 2, 3, and 6, the vanes 6C have protruding
portions 6D which protrude away from the motor 8 (to the right in
FIG. 2) at an intermediate position in the radial direction.
[0042] As shown in FIGS. 2 and 3, each vane 6C has a first edge 64
and a second edge 65 which extend on a side opposite from the motor
8. As shown in FIG. 2, the first edge 64 slants away from the motor
8 in a direction toward the central axis CA. In other words, the
first edge 64 is slanted in such a manner that a distance between
the first edge 64 and the central axis CA is gradually reduced in a
direction toward the inlet 3. Hence, the first edge 64
approximately follows the inner surface of the slanted portion 55.
That is, the first edge 64 extends substantially parallel to the
slanted portion 55 of the casing 5.
[0043] The second edge 65 is slanted in such a manner that a
distance between the second edge 65 and the central axis CA is
gradually increased in a direction toward the inlet 3. Thus the
first edge 64 and the second edge 65 join together to form a tip
portion 66 (FIGS. 3 and 5).
[0044] Next, the flow of air in the blower 1 will be described with
reference to FIG. 2. As the fan 6 is driven to rotate, air is drawn
into the casing 5 through the inlet 3 by the fan 6 in a flow
indicated by an arrow A1. The flow of air passes through the
openings 3a in a direction indicated by arrows A2, gradually
changing direction toward a direction orthogonal to the rotational
axis RA of the fan 6, so as to pass between the vanes 6C in a
curved path following the curved inner surface 5D of the slanted
portion 55 of the casing segment 5C. As the fan 6 rotates, the air
flows radially outwardly through the casing segments 5B and 5C and
is blown out through the outlet 4 in the direction indicated by
arrows A3.
[0045] As described above, the inner surface 5D of the casing
segment 5C near the inlet 3 has a curved shape that slopes away
from the motor 8 in a direction toward the central axis CA of the
inlet 3 (FIGS. 2 and 6). Therefore, it is possible to increase a
space 5s between the inner surface 5D of the casing segment 5C and
the mount portion 6A of the fan 6, through which air from the inlet
3 passes into the fan housing space 5g, thereby reducing the flow
resistance on the airflow. Further, since the inner surface 5D of
the casing segment 5C has a curved surface that allows the flow of
air to gradually change directions toward a direction orthogonal to
the rotational axis RA of the fan 6, the flow resistance on the
airflow can be decreased, thereby improving the suction capacity
and blowing capacity of the blower 1. Also, because the first edge
64 of the vanes 6C slopes along the curved inner surface 5D and
because the vanes 6C are positioned within the space 5s described
above, the air suction capacity and blowing capacity can be
improved.
[0046] If the motor 8 rotates at an abnormal speed due to a
supplied voltage higher than the rated voltage, a great centrifugal
force is applied to the fan 6, causing the fan 6 to deform.
However, the blower 1 according to the present embodiment can
suppress this deformation, as described below.
[0047] As shown in FIG. 4, the vanes 6C of the fan 6 are slanted
with regard to the radial direction of the fan 6 and bend from an
approximately central point CP of the vanes 6C.
[0048] Therefore, as shown in FIG. 5, a space 6s is formed between
an outermost portion 6M of the vanes 6C in the radial direction and
the mount portion 6A. Here, FIG. 5 is a cross-sectional view along
a line V-V in FIG. 4. Although center of gravity CG in the
outermost portion 6M of the vanes 6C lies in the approximate center
with respect to the axial direction RA of the fan 6, the space 6s
is formed between the outermost portion 6M of the vanes 6C and the
mount portion 6A, and the outermost portion 6M is connected
(coupled) only with the base plate 6B at a connection portion 6N.
Accordingly, when the fan 6 rotates, a centrifugal force CF is
applied to the outermost portion 6M, thereby producing a moment M
that attempts to slant the outermost portion 6M in a radially
outward direction about the connection portion 6N.
[0049] Therefore, if the motor 8 rotates at an abnormal speed or
the like, causing a large moment to be applied to the outermost
portion 6M of the vanes 6C, the base plate 6B also deforms toward
the motor 8 about a connection portion 6P at which the base plate
6B connects to the mount portion 6A. Hence, as shown in FIG. 6,
both the base plate 6B and the vanes 6C deform greatly.
[0050] Further, centrifugal force acts on the vanes 6C, which are
slanted with respect to the radial direction of the fan 6 (FIG. 4).
Hence, the vanes 6C may deform toward the radially outward
direction of the fan 6. Because of this deformation and the
deformation described earlier the fan 6 deforms toward the motor 8
as indicated by an arrow A4 (FIG. 2) during the abnormal
rotation.
[0051] As shown in FIG. 6, when the fan 6 deforms toward the motor
8 due to the abnormal rotation, the first edge 64 of the vanes 6C
contacts the inner surface 5D of the slanted portion 55. More
specifically, the tip portion 66 contacts the slanted portion 55.
Hence, this construction can suppress deformation of the vanes 6C
and can thereby reduce the abnormal deformation, damage, and the
like incurred by the fan 6.
[0052] During this deformation, the base plate 6B also contacts a
surface 5H of the partition 51. Therefore, the fan 6 contacts the
inner surface of the casing 5 at two locations, thereby
distributing the load applied to the casing 5. As a result, it is
not necessary to increase the thickness of the casing 5 so that the
casing 5 can withstand contact with the fan 6. Hence, the weight of
the components are not increased, thereby achieving a blower that
is lightweight and easy to operate.
[0053] Further, even when the vanes 6C are damaged or when cracks
are formed at the connection portion between the vanes 6C and the
mount portion 6A due to the abnormal rotation, the vanes 6C contact
the inner surface 5D of the casing 5 near the inlet 3. Therefore, a
broken piece or fragment of the fan 6 does not come off and impact
the casing 5.
[0054] While the invention has been described in detail with
reference to the specific embodiment thereof, it would be apparent
to those skilled in the art that various changes and modifications
may be made therein without departing from the spirit of the
invention.
* * * * *