Note: Descriptions are shown in the official language in which they were submitted.
1
BACKPACK BLOWER
RELATED APPLICATION
[0001] The present application claims priority to U.S. Provisional Patent
Application No.
62/570,584, filed October 10, 2017, the entire contents of which is hereby
incorporated by
reference.
FIELD
[0002] The invention relates to a blower and, more particularly, to an
impeller, impeller
housing, and coupler for a blower.
SUMMARY
[0003] Backpack leaf blowers generally produce a constant flow of air
through a nozzle,
tube, or other implement that may be manipulated by a user. In many instances,
the blower is
self-contained, including an internal combustion engine or other power source
configured to
generate the energy required to drive the device. However, internal combustion
engines can be
heavy, and, therefore, trade-offs are made between providing the maximum
blowing capacity
while minimizing the weight and bulkiness of the device.
[0004] In one independent aspect, a blower may generally include a
housing defining a
chamber, a motor supported by the housing, and a mixed flow fan assembly
supported in the
chamber and driven by the motor to generate an air flow, the fan assembly
including a pair of
mixed flow fans connected as a singular component, the fans being operable to
draw air in
opposing directions and to direct air radially outwardly.
[0005] In another independent aspect, a blower may generally include a
housing defining a
chamber, a motor supported by the housing and having a drive shaft defining an
axis, and an
impeller supported in the chamber and driven by the motor to generate an air
flow. The housing
may define a duct having an axial height and a transverse width, the width
being less than the
height.
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[0006] In yet another independent aspect, a blower may generally include a
housing defining
a chamber, a motor supported by the housing and having a drive shaft defining
an axis, an
impeller supported in the chamber and driven by the motor to generate an air
flow, the impeller
having an end defining a plurality of recesses, and a coupling operable to
couple the impeller to
the motor, the coupling including a hub connected to the drive shaft and
extending along the axis
and a plurality of ribs extending from the hub, each rib being engageable in a
recess to drivingly
connect the drive shaft to the impeller, each rib extending in a non-radial
direction from the hub.
[0007] In some constructions, the coupling is disposed in the chamber. In
some
constructions, each rib extends tangentially relative to a circle centered on
the axis.
[0008] In a further independent aspect, a blower may generally include a
housing at least
partially defining a chamber; a motor including a drive shaft defining a
rotational axis; an
impeller driven by the motor to generate an air flow in the chamber; and a
coupler operably
connected between the drive shaft and the impeller to transmit torque
therebetween, the coupler
being connected to one of the drive shaft and the impeller and including a
plurality of ribs
configured to engage the other of the drive shaft and the impeller, each rib
defining a rib axis
transverse to the rotational axis, each rib axis being arranged tangent to a
circle centered on the
rotational axis.
[0009] In another independent aspect, a backpack blower may generally
include a frame
operable to be supported by a user and including a back plate configured to be
positioned
proximate a back of the user; a housing supported by the frame and at least
partially defining a
chamber; a motor supported by the frame; and an impeller driven by the motor
about a rotational
axis to generate an air flow within the chamber. The chamber may define a
channel region
having a cross-sectional shape with an axial height and a transverse width,
the axial height being
greater than the transverse width, the axial height increasing from a first
position proximate the
back plate to a second position spaced from the back plate.
[0010] In yet another independent aspect, a blower may generally include a
housing at least
partially defining a chamber having a chamber inlet and a chamber outlet, the
chamber having a
non-circular cross-section proximate the chamber outlet; a tube assembly in
fluid communication
with the chamber, the tube assembly having a tube inlet coupled to the chamber
outlet and a tube
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outlet, the tube assembly having a non-circular cross-section proximate the
tube inlet; and an
impeller operable to generate an air flow within the chamber and through the
tube assembly.
[0011] In a further independent aspect, a blower may generally include a
housing at least
partially defining a chamber; and an impeller driven about a rotational axis
to generate an air
flow within the chamber, the impeller having a first axial end, an opposite,
second axial end, and
a periphery, the impeller defining a first airflow path having a first axial
inlet proximate the first
axial end and open in a first axial direction and a first radial outlet
extending about the periphery
and open in a substantially radial direction, the impeller defining a second
airflow path separate
from the first airflow path, the second airflow path having a second axial
inlet proximate a
second axial end and open in an opposite, second axial direction and a second
radial outlet
extending along the periphery of the impeller in a substantially radial
direction.
[0012] Other independent aspects of the invention will become apparent by
consideration of
the detailed description, claims and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view of a backpack blower.
[0014] FIG. 2 is a rear perspective view of the blower of FIG. 1.
[0015] FIG. 3 is a bottom perspective view of the blower of FIG. 1.
[0016] FIG. 4 is a side view of the blower of FIG. 1.
[0017] FIG. 5A is a cross-sectional view of the blower taken generally
along line 5A-5A of
FIG. 1.
[0018] FIG. 5B is a cross-sectional view of the blower taken generally
along line 5B-5B of
FIG. 1.
[0019] FIG. 6 is a cross-sectional view of the blower taken generally along
line 6-6 of FIG.
4.
[0020] FIG. 7 is a perspective view of the impeller of the blower of FIG.
1.
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[0021] FIG. 8 is a cross-sectional view of the impeller taken generally
along line 8-8 of
FIG. 7.
[0022] FIG. 9 is a perspective view of a coupler of the blower of FIG. 1.
[0023] FIG. 10 is a bottom view of the coupler of FIG. 9.
[0024] FIG. 11 is a perspective view of the impeller housing with an
exhaust tube coupled
thereto.
[0025] FIG. 12 is a section view taken along line 12-12 of FIG. 11.
[0026] FIG. 13 is a detailed view of the exhaust tube of FIG. 12.
DETAILED DESCRIPTION
[0027] Before any independent embodiments of the invention are explained in
detail, it is to
be understood that the invention is not limited in its application to the
details of construction and
the arrangement of components set forth in the following description or
illustrated in the
following drawings. The invention is capable of other independent embodiments
and of being
practiced or of being carried out in various ways. Also, it is to be
understood that the
phraseology and terminology used herein is for the purpose of description and
should not be
regarded as limiting.
[0028] Use of "including" and "comprising" and variations thereof as used
herein is meant to
encompass the items listed thereafter and equivalents thereof as well as
additional items. Use of
"consisting of" and variations thereof as used herein is meant to encompass
only the items listed
thereafter and equivalents thereof.
[0029] Relative terminology, such as, for example, "about",
"approximately",
"substantially", etc., used in connection with a quantity or condition would
be understood by
those of ordinary skill to be inclusive of the stated value and has the
meaning dictated by the
context (for example, the term includes at least the degree of error
associated with the
measurement of, tolerances (e.g., manufacturing, assembly, use) associated
with the particular
value, etc.). Such terminology should also be considered as disclosing the
range defined by the
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absolute values of the two endpoints. For example, the expression "from about
2 to about 4"
also discloses the range "from 2 to 4". The relative terminology may refer to
plus or minus a
percentage (e.g., 1%, 5%, 10% or more) of an indicated value.
[0030] FIGS. 1-5B illustrate a backpack blower 10. The blower 10 includes a
frame 14, a
power source, such as an engine 18, an impeller housing 22 defining a blower
volume or
chamber 26, and an impeller 30 at least partially positioned within the blower
volume 26 and
configured to rotate with respect to the impeller housing 22 about an axis of
rotation 34.
[0031] The illustrated frame 14 of the blower 10 generally has an L-shape
with a back plate
38 and a base portion 42 extending from the back plate 38. One or more straps
(e.g., shoulder
straps, a waist strap, etc. (not shown)) may be connected to the frame 14 to
support and position
the back plate 38 on a user's back.
[0032] As shown in FIGS. 1-3, the back plate 38 includes a contact surface
46 and a series of
apertures 50 to which the straps may be secured. In the illustrated
embodiment, the contact
surface 46 is substantially concave in shape being shaped to substantially
correspond with the
contour of the user's back. The contact surface 46 may also include (not
shown) padding, fabric
covering, etc. to provide improved comfort and fit.
[0033] The base portion 42 of the frame 14 is substantially U-shaped and
includes one or
more mounting locations or bosses 54 to which the impeller housing 22 may be
mounted (see
FIG. 3). As shown in FIG. 5A, the impeller housing 22 is coupled to the base
portion 42 of the
frame 14 with a plurality of vibration isolating elements 58, such as springs,
rubber bumpers, etc.
[0034] In the illustrated construction, the engine 18 is an internal
combustion engine having
a rotatable output shaft 62. In other constructions, the engine 18 may include
an electric motor,
pneumatic motor, hydraulic motor, etc.
[0035] As described below in more detail, the impeller housing 22 is
constructed to provide
for air flow expansion of compressed airflow at an outlet of the impeller 30
and a smooth, non-
turbulent entry into a plenum formed by the air duct. Such a shape results in
a low velocity air
flow in the curved section (to prevent stratification) and finally
acceleration into the nozzle. The
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illustrated oval shape moves the center of mass of the engine 18 as close to
the user as possible
and reduces the size of the blower 10.
[0036] The impeller housing 22 defines a pair of inlets 66, 70 in fluid
communication with
the blower volume 26 and an outlet 74. In use, the impeller 30 rotates with
respect to the
impeller housing 22 drawing in two separate airflows 78a, 78b of ambient air
via the two inlets
66, 70, respectively. The impeller 30 then accelerates and directs the
airflows 78a, 78b into the
blower volume 26 in which the airflows 78a, 78b are combined and expelled via
the outlet 74.
[0037] The base portion 42 of the frame 14 defines a central aperture 82
substantially
corresponding in size and shape to the second inlet 70 of the impeller housing
22 to allow
unobstructed airflow. In the illustrated embodiment, the base portion 42 is
oriented at an angle
86 with respect to the back plate 38 (see FIG. 4). By angling the base portion
42 upwardly (e.g.,
with the angle 86 being less than 90 degrees), the center of mass (CM) of the
backpack blower
is positioned closer to the user for ease of use and to reduce the stress
placed on the user's
back. In the illustrated construction, the angle 86 is between about 30
degrees and 60 degrees
(e.g., approximately 40 degrees).
[0038] As shown in FIGS. 1-6, the impeller housing 22 includes a first
clamshell body 90a,
coupled to a second clamshell body 90b to form the blower volume 26
therebetween. In the
illustrated embodiment, the clamshell bodies 90a, 90b are generally oriented
parallel to and
opposite one another and are coupled along their respective perimeters 94.
[0039] The blower volume 26 of the impeller housing 22 is enclosed between
the first and
second clamshell bodies 90a, 90b and includes a central region 98 positioned
proximate the
center of the impeller housing 22, a channel region 102 extending along the
perimeter 94 of the
impeller housing 22 to the outlet 74, and a transition region 106 extending
between and in fluid
communication with both the central region 98 and the channel region 102.
[0040] Illustrated in FIGS. 5A-5B, the central region 98 of the volume 26
is sized and shaped
to receive at least a portion of the impeller 30. The central region 98
includes the first inlet 66
defined by the first clamshell body 90a, the second inlet 70 separate from the
first inlet 66 and
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=4
4
defined by the second clamshell body 90b, and an annular opening in fluid
communication with
a transition region 106.
[0041] In the illustrated embodiment, the central region 98 is
bounded by an upper conical
wall portion 108 extending axially upwardly (e.g., toward the engine 18) and
radially inwardly to
define the first inlet 66 and a lower conical wall portion 112 extending
axially downwardly (e.g.,
away from the engine 18) and radially inwardly to define the second inlet 70.
Both inlets 66, 70
are substantially circular in cross-sectional shape and include a transitional
fairing 116 to
providing a smooth transition between the inlet 66, 70 and the impeller 30
positioned within the
central region 98.
[0042] Both conical wall portions 108, 112 also include an annular
groove 120 configured to
receive at least a portion of a corresponding annular wall 124 of the impeller
30. Once
assembled, the interaction between the wall 124 and the annular groove 120
form a tortuous path
or a labyrinth seal to minimize the flow of air from the higher pressure fan
outlets 192, 208, and
the lower pressure fan inlets 66, 70.
[0043] The lower conical wall portion 112 also includes a bearing
boss 128 proximate the
second inlet 70 and axially aligned with the axis 34 of the impeller 30. The
bearing boss 128 at
least partially receives a portion of a bearing 132 which, in turn, supports
the impeller 30 within
the blower volume 26.
[0044] As illustrated in FIGS. 5-6, the transition region 106 is
positioned radially outside of
the central region 98 and is configured to receive the airflows 78a, 78b from
the impeller 30 and
convey both airflows 78a, 78b to the channel region 102. In the illustrated
embodiment, the
transition region 106 is a substantially annular-shaped and maintains a
substantially even axial
height throughout. Furthermore, the transition region 106 slightly curves
axially downwardly as
it extends radially outwardly (see FIG. 5A-5B).
[0045] As illustrated, the transition region 106 includes one or more
vanes 136 configured to
direct the flow of air between the impeller 30 and the channel region 102.
More specifically,
each vane 136 extends between the clamshell bodies 90a, 90b and has an
elongated airfoil-like
cross-sectional shape. As shown in FIG. 6, the vanes 136 are angled in the
direction of airflow
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(e.g., counterclockwise). In the illustrated construction, the vanes 136
provide mounting bosses
for fasteners (not shown) connecting the clamshell bodies 90a, 90b and the
bracket supporting
the engine 18.
[0046] Illustrated in FIGS. 5-6, the channel region 102 includes an
elongated channel
extending along the perimeter 94 of the impeller housing 22 from a channel
inlet 152 to the
outlet 74. More specifically, the channel region 102 originates proximate
point A and extends
along an extension axis 140 in a substantially counter-clockwise pattern (in
FIG. 6) before
terminating proximate point B at the outlet 74. The channel region 102 extends
greater than
about 180 degrees and, in the illustrated embodiment, about 330 degrees to
about 360 degrees
(e.g., approximately 350 degrees) about the axis 34 of the impeller 30.
[0047] The cross-sectional shape of the channel region 102 in a plane
perpendicular to the
extension axis 140 is substantially oval in shape, with an axial height 144
greater than its
transverse or radial width 148 at each point along the axis 140. The channel
region 102 defines a
central plane 150 extending radially through the channel region 102 at the
midpoint of the height
(see FIG. 5A). In the illustrated embodiment, the cross-sectional area of the
channel region 102
increases from point A to point B and in the direction of airflow. Stated
differently, the axial
height 144 of the channel region 102 increases from a first position proximate
the back plate 38
to a second position spaced a greater distance from the back plate 38 than the
first position. With
the illustrated construction, the channel region 102 accommodates a relatively
increased volume
of airflow therethrough while minimizing the distance between the axis 34 and
the back plate 38
and between the axis and the radial periphery of the impeller housing 22.
[0048] The inlet 152 of the channel region 102 is formed into the sidewall
and opens to the
transition region 106. In the illustrated embodiment, the inlet 152 extends
along substantially the
entire length of the channel region 102 (e.g., from point A to point B);
however, in alternative
embodiments (not shown), only portions of the channel region 102 may include
an inlet 152.
[0049] The inlet 152 of the channel region 102 is offset from the cross-
sectional center of the
corresponding channel region 102. More specifically, the entire inlet 102 does
not cross the
central plane 150 of the channel region 102 (e.g., the inlet 102 is positioned
between the central
plane 150 and one axial extent 151 of the channel region 102; see FIG. 5A).
Stated differently,
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the chamber inlet 152 is completely positioned on one side of a midpoint of
the axial height of
the channel region 102. In addition, from the central region 98 and toward
channel region 102,
the transition region 106 moves (e.g., curves) away from the central plane 150
such that the inlet
152 of the channel region 102 is farther from the central plane 150 than the
outlet of the impeller
30. As illustrated, the airflows 78a, 78b enter the channel region 102 toward
one axial extent 151
of the channel region 102.
[0050] The illustrated location of the inlet 152 of the channel region 102,
configuration of
the transition region 106, and/or relatively larger volumetric size of the
channel region 102
(when compared to the transition region 106) may provide a non-turbulent and
low velocity entry
of the air flow into the channel region 102 to prevent stratification.
[0051] The impeller housing 22 also includes an exhaust nozzle 154 coupled
to the outlet 74
and providing a connection point for an external hose, tube, etc. The exhaust
nozzle 154
includes an outer annular wall 155 that transitions from a first cross-
sectional shape,
corresponding to the cross-sectional shape of the outlet 74, to a second cross-
sectional shape,
having a smaller area than the first cross-sectional shape. The exhaust nozzle
154 thus serves to
accelerate the airflow within the impeller housing 22.
[0052] Illustrated in FIGS. 5A-5B and 7-8, the illustrated impeller 30
includes a mixed flow
fan assembly with a pair of mixed flow fans connected or formed as a singular
component. The
mixed flow fan assembly includes a dual inlet mirrored mixed flow impeller is
operable to draw
air into the blower duct from two opposing directions from top and bottom
inlets. For example,
a top fan draws air across the engine 18 and into the blower duct (thereby
potentially providing
cooling to the engine 18) while a bottom fan draws air from a bottom side of
the blower
duct. Both fans may be formed similar to a centrifugal fan to direct the air
radially outwardly
into the blower duct as it leaves the blades of the respective fan. Such a
mixed flow fan
assembly may provide an increased volumetric flow rate for a given outer
diameter compared to
a single impeller which would be much larger, and require a larger housing, to
achieve the same
flow.
[0053] The impeller 30 includes a body 156 with a first conical surface 160
terminating at a
first axial end 164 and a second conical surface 168 terminating in a second
axial end 172. A
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first outer wall 176 is spaced a distance from the first conical surface 160
to define a first airflow
path 180a therebetween, and a second outer wall 184 is spaced a distance from
the second
conical surface 168 to define a second airflow path 180b therebetween. As
mentioned above,
rotation of the impeller 30 about the axis 34 draws separate airflows 78a, 78b
into respective
airflow paths 180a, 180b. Both airflows 78a, 78b are then accelerated by the
impeller 30 and
exhausted in radially outwardly into the transition region 106 of the blower
volume 26.
[0054] The first airflow path 180a is substantially annular in shape having
a first inlet 188
open in an axial direction proximate the first axial end 164 and a first
outlet 192 extending along
the periphery 196 in a substantially radial direction (see FIG. 8). The first
airflow path 180a is
shaped to smoothly transition the airflow 78a from a substantially axial
direction (e.g., into the
first inlet 188) to a substantially radial direction (e.g., out of the first
outlet 192). The first airflow
path 180a is also enclosed by the body 156 of the impeller 30 along its entire
length between the
first inlet 188 and the first outlet 192.
[0055] The first airflow path 180a also includes a plurality of vanes 200
positioned within
the airflow path 180a and extending between the first conical surface 160 and
the first outer wall
176. The vanes 200 are configured to accelerate the first airflow 78a as it
passes through the first
airflow path 180a. In the illustrated embodiment, the vanes 200 are swept in a
direction opposite
the direction of rotation of the impeller 30.
[0056] The second airflow path 180b is also substantially annular in shape
having a second
inlet 204 open in a substantially axial direction proximate the second axial
end 172 and a second
outlet 208 extending along the periphery 196 in a substantially radial
direction (see FIG. 8). The
second airflow path 180b is shaped to smoothly transition the second airflow
78b from a
substantially axial direction (e.g., into the second inlet 204) to a
substantially radial direction
(e.g., out of the second outlet 208). The second airflow path 180b is also
enclosed by the body
156 of the impeller 30 along its entire length between the second inlet 204
and the second outlet
208.
[0057] The second airflow path 180b also includes a plurality of vanes 200
positioned within
the airflow path 180b and extending between the second conical surface 168 and
the second
outer wall 184. The vanes 200 are configured to accelerate the second airflow
78b as it passes
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through the second airflow path 180b. In the illustrated embodiment, the vanes
200 are swept in
a direction opposite the direction of rotation of the impeller 30.
[0058] Proximate each outlet 192, 208, each conical wall portion 108, 112
defines a recess
210 receiving the associated outer wall 176, 184 of the impeller 30. With this
arrangement, the
inner surface of each outer wall 176, 184 is substantially flush with the
adjacent surface of the
conical wall portion 108, 112 to provide a smooth surface for the airflows
78a, 78b into the
transition region 106. Likewise, the surface of each inlet 66, 70 is
substantially flush with the
inner surface of the adjacent outer wall 176, 184 for entry of the airflows
78a, 78b. In the
illustrated embodiment, the outlets 192, 208 of the impeller 30 are positioned
axially closer to
the midpoint of the axial height of the channel region 102 than the chamber
inlet 152 (with the
upper outlet 192 being closest to the midpoint).
[0059] The impeller 30 also defines a coupling portion 212 proximate the
first axial end 164
and including an annular ridge 216 formed by the body 156 to define an
aperture 218. In the
illustrated embodiment, the annular ridge 216 includes a substantially
hemispherical outer
contour (see FIG. 7). The ridge 216 also defines a plurality of radially
oriented grooves 220
spaced (e.g., equally) about the circumference.
[0060] The impeller 30 also defines a support boss 232 aligned with the
axis 34 and
positioned proximate the second axial end 172. The support boss 232 is
configured to receive at
least a portion of the bearing 132 positioned in the bearing boss 128. The
support boss 232 and
the bearing boss 128 cooperate to position the impeller 30 within the central
region of the
impeller housing 22.
[0061] Illustrated in FIGS. 5A-5B and 9-10, the blower 10 also includes a
coupler 228
coupled to and extending between the output shaft 62 of the engine 18 and the
coupling portion
212 of the impeller 30. The coupler 228 is configured transmit torque between
the shaft 62 and
the impeller 30 so that the two elements to rotate together as a unit. The
coupler 228 is also
configured to allow some movement/misalignment between the output shaft 62 and
the impeller
30. In the illustrated embodiment, the coupler 228 and the bearing boss 128
define the location
of the impeller 30 within the impeller housing 22. The illustrated coupling
arrangement may
allow for a modular assembly the engine 18 may be separated from the impeller
housing 22.
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k
k
[0062] The coupler 228 includes a central hub 236, a semi-spherical
hood 240 extending
radially outwardly from the hub 236, and a plurality of ribs 244 extending
between the hub 236
and the hood 240. The shape of the annular ridge 216 substantially corresponds
to the inner
shape of the hood 240. The grooves 220 on the coupling portion 218 and ribs
244 are sized,
spaced and oriented to facilitate engagement.
[0063] The output shaft 62 of the engine 18 is rotatably coupled to a
threaded aperture
defined by the hub 236. The coupler 228 is connected to the coupling portion
212 of the
impeller 30. The coupling portion 212 is at least partially inserted into the
space formed between
the hood 240 and the hub 236 such that the hub 236 is at least partially
positioned within the
aperture 218 of the ridge 216 and each rib 244 is at least partially received
within a
corresponding one of the grooves 220. As shown in FIGS. 5A-5B, the outer
surface of the hood
240 merges into the outer surface of the impeller 30. Once assembled, the
coupling portion 212
engages with and interlocks with the coupler 228 allowing the coupler 228 and
impeller 30 to
rotate as a unit.
[0064] As best illustrated in FIG. 10, the ribs 244 of the coupler
228 are positioned such that
an axis 248 of each rib 244 does not pass through the axis 34 (e.g., is non-
radial). Rather, each
rib 244 and each rib axis 248 is offset from a radial orientation. As
illustrated, each rib 244 and
each axis 248 extends generally tangentially to a circle about the axis 34.
The illustrated
configuration of the coupler 228 may improve connection between the output
shaft 62 and the
impeller 30 and reduce noise produced during operation.
[0065] While the coupler 228 is shown being attached to the drive
shaft 62 with the ribs 244
engaging the impeller 30, it should be understood that, in alternative
embodiments (not shown),
the coupler 228 may be attached to the impeller 30 with the ribs 244 engaging
the drive shaft 62.
[0066] To operate the blower 10, the user starts the engine 18, and
the engine 18 rotates the
output shaft 62 which, in turn, causes the coupler 228 to rotate. The coupler
228 then transmits
the torque of the engine 18 to the impeller 30 via the engagement between the
ribs 244 and the
grooves 220. As such, the impeller 30 and the output shaft 62 rotate together
as a unit about the
axis 34.
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4-
[00671 Rotation of the impeller 30 draws in separate airflows 78a,
78b into the impeller
housing 22. The first airflow 78a is drawn into the first inlet 188 of the
impeller 30 via the first
inlet 66 of the impeller housing 22. The first airflow 78a is then accelerated
by the vanes 200 in
the first airflow path 180a and exhausted radially through the first outlet
192 and into the
transition region 106.
[0068] Simultaneously, the second airflow 78b is drawn into the
second inlet 204 of the
impeller 30 via the second inlet 70 of the impeller housing 22. The second
airflow 78b is then
accelerated by the vanes 200 in the second airflow path 180b and exhausted
radially through the
second outlet 208 and into the transition region 106.
[0069] After exiting the impeller 30, the two airflows 78a, 78b merge
into a single airflow
traveling radially outwardly over substantially the entire circumferential
length of the impeller
30. The combined airflow then continues to travel radially outwardly through
the transition
region 106 where it enters the channel region 102 of the blower volume 26.
[0070] In the channel region 102, the combined airflow originates
proximate point A and
travels in a counter clockwise-direction (in FIG. 6) along the channel region
102 and toward the
outlet 74. As the airflow travels along the channel region 102, additional air
is added to channel
region 102 via the inlet 152 along the entire length of the channel region
102. As such, the
volume of air increases as it travels along the length of the channel region
102 and is
accommodated by the increasing cross-sectional area of the channel region 102.
After the
combined airflow reaches the outlet 74, the combined airflow enters the
exhaust nozzle 154
which, as described above, tapers (e.g., the cross-sectional area decreases)
and accelerates the
combined airflow before it exits the blower 10.
[0071] FIGS. 11-13 illustrate another embodiment of the impeller
housing 22'. The impeller
housing 22' is substantially similar to the impeller housing 22, as described
above, and only
= differences will be described herein.
[0072] The impeller housing 22' includes an exhaust duct or tube 252'
coupled to the outlet
74' and configured to convey the combined airflow therethrough. The exhaust
duct 252' includes
a bellows or flexible portion 260' coupled to the outlet 74' and a rigid
portion 264' coupled to
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and extending from the flexible portion 260' to an exhaust port 268'. During
use, the combined
airflow enters the flexible portion 260' of the exhaust duct 252' via the
outlet 74', flows through
the flexible and rigid portions 260', 264', and is exhausted through the
exhaust port 268'.
[0073] As illustrated in FIG. 13, the flexible portion 260' of the exhaust
duct 252' is
substantially elongated in shape being formed from an outer wall 274' having a
first end 276', an
opposite second end 280', and at least partially defining a channel 256'
therethrough. During
use, the first end 276' of the flexible portion 260' is movable relative to
the second end 280'
while generally maintaining the cross-sectional shape and the integrity of the
channel 256' thus
assuring that air entering the first end 276' is directed and passes through
the second end 280'.
[0074] The outer wall 274' of the flexible portion 260' is generally formed
from a resilient
and flexible material, such as rubber, etc. The outer wall 274' has a
serpentine shape and
includes a flexible region or bellows portion 284' with a plurality of ribs
282' to permit the outer
wall 274' to expand, contract, and elastically deform.
[0075] In the illustrated implementation, the smallest cross-sectional area
formed by the
flexible region 284' of the outer wall 274' is at least as large as the cross-
sectional area of the
first end 276' of the flexible portion 260'. As such, the flexible region 284'
does not restrict the
flow of air therethrough. Proximate its inlet, the flexible region 284' has a
non-circular cross-
sectional shape. In particular, the inlet of the flexible region 284' is
substantially oval in shape.
[0076] Furthermore, the flexible portion 260' and the smallest cross-
sectional area of the
flexible region 284' have a cross-sectional shape substantially similar to the
cross-sectional
shape of the outlet 74' of the impeller housing 22', that is, having a height
that is greater than its
width. By having a cross-sectional shape that is similar to that of the outlet
74', the flexible
portion 260' reduces pressure head loss during operation.
[0077] The rigid portion 264' of the exhaust duct 252' is substantially
tubular in shape
having a body 286' with a first end 288' and an opposite second end 292'
forming the exhaust
port 268'. The body 286' of the rigid portion 264' also defines a second
channel 290' extending
therethrough and open to the exhaust port 268'. The first end 288' of the
rigid portion 264' is
14
CA 3020291 2018-10-10
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,
coupled to the second end 280' of the flexible portion 260' causing the second
channel 290' to
be in fluid communication with the first channel 256'.
[0078] In the illustrated embodiment, the body 286' of the rigid
portion 264' transitions in
cross-sectional shape from the first end 288' to the second end 292'. The
first end 288' has a
cross-sectional shape substantially similar to the cross-sectional shape of
the second end 280' of
the flexible portion 260' (e.g., non-circular or oval) and, likewise, to the
cross-sectional shape of
the outlet 74' of the impeller housing 22'. The second end 292' of the rigid
portion 264' is
substantially circular in cross-sectional shape and has a cross-sectional area
less than the cross-
sectional area of the first end 288'. As such, the rigid portion 264' of the
exhaust duct 252'
accelerates the airflow as it passes therethrough.
[00791 Although the invention has been described in detail with
reference to certain preferred
constructions, variations and modifications exist within the scope and spirit
of one or more
independent aspects of the invention as described.
[0080] One or more independent features and/or independent advantages
of the invention
may be set forth in the claims.
CA 3020291 2018-10-10
