Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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QUIET VACUUM CLEANER
Background
Field of the Invention
[01] The present invention relates, in general, to vacuum cleaners, and, in
particular, to
baclcpack vacuum cleaners.
Background of the Invention
[02] It is well-known that vacuum cleaning efficiency has been improved
through the
use of baclcpack vacuum cleaners. A backpack vacuum cleaner includes a
backpack
assembly, similar to that used in a hiking backpack, where the vacuum cleaner
assembly is
carried by a backpack frame of the backpack assembly. A vacuum cleaner hose
extends
from a top of the vacumn cleaner assembly and is connected to a vacuum cleaner
wand. A
distal end of the vacuum cleaner wand includes a vacuum cleaner floor tool. In
use, the
cleaner carries the backpack vacuum cleaner on his or her back using the
baclcpack
assembly, and directs the vacuum cleaner tool for cleaning the floor surface
through the
wand. Historically, much of the cleaning performed using backpack vacuum
cleaners
such as that done in office buildings or other comunercial settings was done
at night time,
by night-time cleaning personnel and janitors. Noise made by the backpack
vacuum
cleaners was not that big of an issue because most workers and visitors were
not present
during the vacuum cleaning, so the noise would not bother workers in the
office buildings
or other commercial settings. However, more recently, there is a trend to
clean during the
daytime, when workers and visitors in the office buildings or other commercial
settings
are present. One of the complaints by workers and visitors in the office
buildings or other
commercial settings of vacuum cleaning is the noise. The noise sources are
noises
associated with the motor and air movement noise at the vacuum tools and
exhaust.
[03] Motor noise has been addressed in the past by placing sound absorbing
materials in
the flow path. This reduces the system performance to an unacceptable level
and adds
weight to the vacuum cleaner. By restricting the flow path in this manner the
motor is
susceptible to overheating because it is not getting sufficient air for
cooling.
[04] Therefore, a need exists for a vacuum cleaner, especially a backpaclc
vacuum
cleaner, that overcomes the problems with prior art vacuum cleaners,
especially the
problems with prior art backpack vacuum cleaners.
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Summary
[05] The baclcpack vacuum cleaner of the present invention is light-weight and
significantly reduces the noise levels associated with the motor and air
movement noise at
the vacuum tools and exhaust while maintaining good system performance. The
vacuum
cleaner maintains large cross-sectional areas for exhaust flow, allowing
sufficient air flow
to provide the required cooling for the motor. The vacuum cleaner also directs
the air flow
to unique foam surfaces to obtain the required sound deadening.
[06] An aspect of the invention involves a light-weight, quiet vacuum cleaner
assembly
for a backpack vacuum cleaner including a backpack assembly for carrying the
vacuum
cleaner assembly on a user's back, a vacuum cleaner hose for vacuuming debris
from a
surface, and a filter for filtering out vacuumed debris. The light-weight,
quiet vacuum
cleaner assembly includes an air inlet for communicating with the vacuum
cleaner hose
and the filter; a vacuum motor for drawing air througli the vacuum cleaner
hose, air inlet,
and filter; a quiet exhaust assembly module in communication with the vacuum
motor for
expelling and quieting exhaust from the vacuum motor, and wherein the vacuum
cleaner
assembly weighs 2-12 lbs. and includes a flow rate (CFM) to noise (dbA) ratio
(flow
rate/noise) of at least 0.6.
[07] Another aspect of the invention involves a light-weight, quiet vacuum
cleaner
assembly for a baclcpack vacuuin cleaner including a backpack assembly for
carrying the
vacuum cleaner assembly on a user's back, a vacuum cleaner hose for vacuuming
debris
from a surface, and a filter for filtering out vacuumed debris. The light-
weight, quiet
vacuum cleaner asseinbly includes an air inlet for communicating witli the
vacuum cleaner
hose and the filter; a vacuum motor for drawing air through the vacuum cleaner
liose, air
inlet, and filter; a quiet exhaust assembly module in communication with the
vacuum
motor for expelling and quieting exhaust from the vacuum motor, and wherein
the vacuum
cleaner assembly weighs 2-12 lbs. and includes a suction (in. (H20)) to noise
(dbA) ratio
(suction/noise) of at least 0.6.
[08] Another aspect of the invention involves a light-weight, quiet vacuum
cleaner
assembly for a backpaclc vacuum cleaner including a backpack assembly for
carrying the
vacuum cleaner assembly on a user's back, a vacuum cleaner hose for vacuuming
debris
from a surface, and a filter for filtering out vacuumed debris. The light-
weight, quiet
vacuum cleaner assembly includes an air inlet for communicating with the
vacuum cleaner
hose and the filter, the air inlet including an intalce area; a vacuum motor
for drawing air
through the vacuum cleaner hose, air inlet, and filter; a quiet exhaust
assembly module in
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communication with the vacuum motor for expelling and quieting exhaust from
the
vacuum motor, and wherein the quiet exhaust assembly module includes a stage
of
exhaust openings having a total area and the ratio of the total area of the
stage of exhaust
openings to the intalce area of the air inlet is at least 3:1.
Brief Description of the Drawings
[09] The details of the present invention, both as to its structure and
operation, may be
gleaned in part by the accompanying drawings, in which like reference numerals
refer to
like parts, and in which:
[10] FIG. 1 is a perspective view of an embodiment of a quiet backpack vacuum
cleaner
with a vacuum cleaner hose, vacuum cleaner wand, and vacuum cleaner floor tool
attached
and the quiet backpack vacuum cleaner shown in use on the back of a user;
[11] FIG. 2 is perspective view of the backpack vacuum cleaner of FIG. 1;
[12] FIG. 3 is front elevational view of the backpack vacuum cleaner of FIG. 1
with the
back strap system, power cord assembly, two-speed switch asseinbly, and paper
filter bag
hidden for clarity;
[13] FIG. 4 is a front elevational view of a quiet exhaust assembly of the
backpack
vacuum cleaner witli the rest of the backpack vacuum cleaner shown in phantom;
[14] FIG. 5 is an enlarged front elevational view of the quiet exhaust
assembly module
of FIG. 4 with the exhaust air flow path shown; and
[15] FIG. 6 is an exploded perspective view of the quiet exhaust assembly
module of
FIGS. 4 and 5.
Detailed Description
[16] With reference to FIGS. 1-6, and initially FIGS. 1-3, an embodiment of a
quiet
backpack vacuum cleaner 100 will be described.
[17] Although the quiet vacuum cleaner 100 is shown and described as a
backpack
vacuum cleaner, the features of the vacuum cleaner 100 that make it a quiet,
high-
performance vacuum cleaner may be applied to additional types of vacuum
cleaners such
as, but not by way of limitation, canister vacuum cleaners and upright vacuum
cleaners.
[18] After reading this description it will become apparent to one skilled in
the art how
to implement the invention in various alternative embodiments and alternative
applications. However, although various embodiments of the present invention
will be
described herein, it is understood that these embodiments are presented by way
of example
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only, and not limitation. As such, this detailed description of various
alternative
embodiments should not be construed to limit the scope or breadth of the
present invention
as set forth in the appended claims.
[19] With reference to FIG. 1, the quiet backpack vacuum cleaner 100 includes
a
vacuum cleaner assembly 110 that is carried on a user's back via a backpack
assembly
120. A vacuum cleaner hose 130 extends from a top of the vacuum cleaner
assembly 110
and is connected to a vacuum cleaner wand 140. A distal end of the vacuum
cleaner wand
140 includes a vacuum cleaner floor tool 150, wliich engages the carpet or
otlzer floor
surface for cleaning the same.
[20] Witll reference additionally to FIG. 2, the backpack assembly 120
includes a
baclcpack strap system 160 connected to a vacuum cleaner support 170, which
carries the
vacuuin cleaner assembly 110. The backpack strap system 160 includes slioulder
straps
180 and a waist belt 190.
[21] The vacumn cleaner assembly 110 includes a main housing assembly 200, a
top
cap hose and air inlet 210 at a top end, and an opposite exhaust end 220. A
two-speed
switch assembly witll switch box 230 and a power cord assembly 240 are
connected to a
lower electrical section 260 (FIG. 3) of the vacuum cleaner assembly 110
througll
respective cords.
[22] With reference additionally to FIG. 3, the vacuum cleaner assembly 110
includes
an upper filter section 250 and a lower electrical section 260. The upper
filter section 250
includes an intalce filter and refuse bag 265, and a motor intake filter 280.
A lower portion
of the upper filter section 250 and the lower electrical section 260 carry a
quiet exhaust
assembly module 270.
[23] With reference to FIGS. 4-6, an embodiment of the quiet exlzaust assembly
module
270 will be described in more detail. The quiet exhaust assembly module 270
includes a
vacuum motor 290, an annular gasket 300, a motor housing 310, a quiet module
housing
320, acoustic panel 330, an annular director plate 340, an annular foam air
diffuser 350, an
annular acoustic panel 360, and a quiet module cap 370. Each of these quiet
exhaust
assembly module components will now be described in turn below.
[24] The vacuum motor 290 is a two-stage vacuuin motor having a cylindrical
head
with an underside.
[25] The annular gasket 300 is a neoprene gasket with an adhesive on one side.
The
annular gasket 300 is disposed between the underside of the cylindrical head
of the
vacuum motor 290 and an upper surface of the motor housing 310.
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[261 Threaded fasteners 380 are used to attach the vacuum motor 290 to the
motor
housing 310.
[27] The motor housing 310 has a generally cylindrical wall 3 82 with Stage 1
elongated
lateral slots 384 near a bottom of the motor housing 310. In the embodiment
shown, the
motor housing 310 includes four (4) Stage 1 slots 384 with three (3) of the
slots having a
dimension of 3.25 in. X 0.5 in. (3 Slots @ 3.25" X 0.5"= 4.875 sq. in.), and
the last slot
having a dimension of 2.25 in. X 1.0 in. (1 Slot @ 2.25" X 1.0" = 2.25 sq.
in.). Stage 1
air flow occurs through these slots 384. The total area of the Stage 1 slots
384 is 4.875 sq.
in. + 2.25 sq. in.= 7.125 sq. in. The bottom of the motor housing 310 includes
a plurality
of ribs 386 extending outwardly from the wall 382. The ribs 386 include
threaded bosses.
[28] Threaded fasteners 390 threadably engage the threaded bosses of the ribs
386 to
attach the quiet module housing 320 to the motor housing 310.
[29] The quiet module housing 320 includes a top surface 392 with star-shaped,
radiating ridges extending therefrom. The top surface 392 of the quiet module
1lousing
320 forins the bottom or floor of the motor housing 310 when the quiet module
housing
320 is connected to the motor housing 310. The quiet module housing 320 has a
frustoconical wall 394 with Stage 2 elongated lateral slots 396 near a top of
the quiet
module housing 320. In the embodiment shown, the quiet module housing 320
includes
four (4) Stage 2 slots 396 having a dimension of 3.00 in. X 0.5 in. (4 Slots @
3.00" X
0.5"= 6.0 sq. in.). Stage 2 air flow occurs through these slots 396. As
indicated above, the
total area of the Stage 2 slots 396 is 6.0 sq. in.
[30] The acoustic panel 330 includes two half-cylindrical members with an
outer
surface 398. The acoustic panel 330 is made of a unique, light-weiglit, high-
temperature,
fire-retardant foam material. The foam material is produced in flat sheets. An
adhesive is
added to a side of a flat 0.032 in. polycarbonate sheet, and the polycarbonate
sheet is
laminated to a side of the flat sheet of foam material. Two flat sheets of
foam material and
polycarbonate are bent into the half-cylinder configuration shown, with the
polycarbonate
sheet on the outer side of the acoustic panel 330. The two half-cylindrical
members are
placed together to form a cylinder around the quiet exhaust asseinbly module
270, as
shown in FIG. 5. The hoop stress in the polycarbonate sheet and acoustic panel
330 cause
the acoustic panel 330 to be held in place over the motor housing 310, quiet
module
housing 320, annular director plate 340, annular foam air diffuser 350,
annular acoustic
panel 360, and quiet module cap 370 without any adhesive. The unique, light-
weight,
high-temperature, fire-retardant foam material of the acoustic panel 330
provides
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maximum attenuation of the sound waves in the quiet exhaust assembly module
270. The
foam material used in the acoustic panels 330 is a high-performance polyimide
foam sold
as type HT-340 under the naine Solimide by INSPEC FOAMS, INC. of Plano,
Texas.
For mechanical properties, the foam material has a density (ASTM D 3574, Test
A) of 0.4
lb/ft3, and a tensile strength (ASTM D 3574, Test E) of 7 lb/inz. For thermal
properties,
the foam material has a therinal conductivity (ASTM C 518 at mean temperature
of 75 F)
of 0.32 (BTU=in)/(hr=ft3- F), and a continuous use temperature (recommended
maximum)
of 575 F. For flammability properties, the foam material has a radiant panel
flame spread
index (ASTM E 162) of 1, a non-flaming specific optical density (ASTM E 662)
of smoke
of 1, a flaming specific optical density of smoke (ASTM E 662) of 3, a flame
spread index
(ASTM E 84-95, Tested at a tliicluiess of 22 mm (0.9 in.)) of 0, a smoke
developed index
(ASTM E 84-95, Tested at a thiclcness of 22 mm (0.9 in.)) of 10. For steam
autoclave
aging properties (ASTM D 3574, Test J, Procedure J, and Test E), the foain
material has a
tensile strength retained of greater than 85% and a change in weight and
dimensions of
less than 3%. For acoustic properties, the foam material has the following
acoustical
absorption coefficients (sabins/ft2; ASTM C 423 and E 795, Type A Mounting) at
1 in.:
0.08 at 125 Hz, 0.22 at 250 Hz, 0.58 at 500 Hz, 0.93 at 1000 Hz, 0.94 at 2000
Hz, 0.81 at
4000 Hz. The foam material has the following acoustical absorption
coefficients
(sabins/ftZ; ASTM C 423 and E 795, Type A Mounting) at 2 in.: 0.34 at 125 Hz,
0.52 at
250 Hz, 0.86 at 500 Hz, 1.06 at 1000 Hz, 0.85 at 2000 Hz, 0.94 at 4000 Hz.
[31] The annular director plate 340 is a thin, annular sheet of polycarbonate
material
that serves as a barrier and directs air flow towards the center of the quiet
exhaust
assembly module 270.
[32] The annular foam air diffuser 350 serves to break up some line of sight
in the quiet
exhaust asseinbly module 270 and attenuate the air flow sound waves. The
annular foam
air diffuser 350 is made of a reticulated flexible polyester urethane foam
that has a
completely open cell, three-dimensional structure of skeletal strands which
give them
special filtering properties. The foam material used in the diffuser 350 is
sold as 20 PPI,
SIF Z under the name FOAMEX by Foamex Technical Products of Eddystone,
Pennsylvania. The homogeneous structure of the diffuser 350 helps minimize the
possibility of open channels which could drastically affect filter efficiency.
Each cell in
the mediuin is completely interconnected with all surrounding cells. This
allows for free
passage of air and at the same time provides high surface-area contact for
impingement of
dust particles. The resilience and strengtll of the diffuser 350 helps prevent
and strand
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displacement under normal operating conditions. In the embodiment shown, the
diffuser
350 includes a 20 pore size (average number of pores-per-linear-inch). At this
porosity,
the diffuser 350 includes a density of 1.9 lb/ft3, a tensile strength of 25
psi, an ultimate
elongation of 320%, a tear strength of 5.5 lb/in., a 50% compression set of 7,
a 25%
compression deflection of 0.42 psi, and a 65% compression deflection of 0.67
psi. The
diffuser 350 has excellent high-temperature characteristics. It can withstand
intermittent
temperatures as high as 225 F. At temperatures above 500 F, the material
beings to melt
with decoinposition and vaporization.
[33] The annular acoustic panel 360 is made of the same material as the
acoustic panel
330 described. The above description of the material used in the acoustic
panel 330 is
incorporated by reference here as though set forth in full.
[34] The quiet module cap 370 includes a circular dish-like configuration with
an
annular recess that receives the acoustic panel 360. A central boss 399
receives threaded
fastener 400 to mount the quiet module cap 370 and hold the intermittent
coinponents of
the quiet module housing 320 together. The quiet module cap 370 is made of a
polycarbonate material and includes eight (8) Stage 3 slots 402 having a
dimension of 2.0
in. X 0.36 in. (8 Slots @ 2.00" X 0.36 in = 5.76 sq. in.). Stage 3 air flow
occurs through
these slots 402. As indicated above, the total area of the Stage 3 slots 402
is 5.76 sq. in.
The quiet module cap 370 and threaded fastener 400 allow the quiet exhaust
assembly
module 270 to be easily field serviced. To service the quiet exhaust assembly
module 270,
a user simply unscrews the threaded fastener 400, and removes the quiet module
cap 370.
This provides easy access to the components of the quiet exhaust assembly
module 270 for
repair or replacement of the components. The entire quiet exllaust assembly
module 270
can also be easily replaced in this manner. As a result, the backpack vacuum
cleaner 100
is never down because of something in the quiet exhaust assembly module 270 of
the
backpack vacuum cleaner 100.
[35] A motor control module 410 is electrically coupled to the vacuum motor
290, two-
speed switch assembly with switch box 230, and power cord assembly 240. The
motor
control module 410 provides two-speed control of the vacuum motor 290. The
motor
control module 410 also includes a tliermal protection device for shutting off
the vacuuln
motor 290 when the temperature exceeds approximately 95 C.
[36] The baclcpack vacuum cleaner 100 will now be described in use. When the
user is
in the area desired for vacuuming, the user dons the backpack vacuum cleaner
100 using
the baclcpack strap system 160 in the same manner as putting on a backpack for
hilcing.
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This is easily performed because the baclcpack vacuum cleaner 100 is light-
weight (2-12
lbs.). In the einbodiment shown, the vacuuin cleaner assembly 110 weighs 11
lbs., 3 oz.
The user's arms are placed through the shoulder straps 180 and the shoulder
straps 180 are
tightened to a snug, yet comfortable condition on the user's shoulders. The
waist belt 190
is clipped together, and tightened to a snug, yet comfortable condition around
the user's
waist. Prior to or after doiming the backpack vacuum cleaner 100, the plug of
the power
cord assembly 240 is plugged into an electrical outlet. In an embodiment of
the baclcpack
vacuum cleaner 100 where the backpack vacuuin cleaner 100 has an onboard power
source (e.g., one or more batteries, fuel cells), plugging the power cord
assembly 240 into
an electrical outlet to power the bacicpack vacuum cleaner 100 may not be
necessary. The
backpack vacuum cleaner 100 is switched on using the two-speed switch assembly
230.
The two-speed switch assembly 230 is also used to control the speed of the
vacuum motor
290 between a high setting and low setting. In alternative embodiments, the
baclkpack
vacuuin cleaner 100 may have a nuinber of settings other than two settings
(e.g., 1, 3, 4,
etc.).
[37] In the embodiment shown, the backpack vacuum cleaner 100 performs @ about
70
CFM with about 70 in. (H20) of lift @ about 65 dbA on a high-speed motor
setting, and
about 40 CFM with about 40 in. (H20) of lift @ about 61 dbA on a low-speed
motor
setting. In a preferred embodiment, the backpack vacuum cleaner 100 includes a
flow rate
(CFM) to noise (dbA) ratio (flow rate/noise) of at least 0.6 and a suction
(in. (H20)) to
noise (dbA) ratio (suction/noise) of at least 0.6. In a more preferred
embodiment, the
baclcpaclc vacuum cleaner 100 includes a flow rate (CFM) to noise (dbA) ratio
(flow
rate/noise) of at least 1.0 and a suction (in. (H20)) to noise (dbA) ratio
(suction/noise) of at
least 1Ø
[38] Witli the vacuum motor 290 activated, air, dirt, and debris are drawn
through the
vacuum cleaner floor tool 150, vacuum cleaner wand 140, vacuum cleaner hose
130, and
air inlet 210 into the intake filter/refuse bag 265 (FIG. 3). The dirt and
debris is collected
by the intake filter/refuse bag 265 and air is drawn through the motor intake
filter 280 and
the vacuum motor 290. Exhaust air is expelled out of the bottom of the vacuum
motor
290, and into the motor housing 310. The exhaust air reflects off of and is
directed
radially outward along the star-shaped, radiating ridges on the top surface
392. The
exhaust air exits the motor housing 310 tllrough the Stage 1 slots 396. The
exhaust air
reflects off of the acoustic pane1330, dampening the sound level, around the
bottom of the
motor housing 310 and top of the quiet module housing 320, and into/through
the Stage 2
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slots 396 of the quiet module housing 320. The air then flows downward towards
the
director plate 340, and the director plate 340 directs the air flow radially
inward and down
towards the acoustic panel 360. Air flow reflects off of the acoustic panel
360, further
dampening the sound level, and outward through the air diffuser foam 350. The
air
diffuser foam 350 filters out exhaust particulates in the exhaust air flow and
further
dampens the sound levels without significantly impeding air flow. The exhaust
air
impinges the acoustic panel 410 as it exits the air diffuser foam. The exhaust
air then
flows downward, tllrough the stage 3 slots 402, and out of the quiet exhaust
assembly
module 270.
[39] With reference to FIGS. 2, 5, and 6, the air inlet 210 has a 1.5 in.
intalce diaineter
and an intake area of 1.77 sq. in. As indicated above, the total bypass area
for the Stage 1
slots 384 is 7.125 sq. in., the total bypass area for the Stage 2 slots 396 is
6.0 sq. in., and
the total bypass area for the Stage 3 slots 402 is 5.76 sq. in. The inventors
have
determined that it is desirable for the bypass areas in each stage of the
quiet exhaust
assembly module 270 to be at least 3 times that of the area of the air inlet
210. This
reduces friction and, thus, minimizes flow loss.
[40] The exhaust assembly module 270 incorporates the principles of "Line of
Sight"
and non-reflective surfaces to diminish sound levels (db). In the quiet
exhaust assembly
module 270, the vacuuin motor 290 is encapsulated in a housing, and air flow
is directed
to high-teinperature acoustic foam covered surfaces and through a condensed
labyrinth of
passages.
[41] The above features minimize the weight of the backpack vacuum cleaner
100,
maximize dissipation of sound levels in the backpack vacuuin cleaner 100, and
maximize
air flow in the backpack vacuum cleaner 100.
[42] The above description of the disclosed embodiments is provided to enable
any
person slcilled in the art to malce or use the invention. Various
modifications to these
embodiments will be readily apparent to those slcilled in the art, and the
generic principles
described herein can be applied to other embodiments without departing fiom
the spirit or
scope of the invention. Thus, it is to be understood that the description and
drawings
presented herein represent a presently preferred embodiment of the invention
and are
therefore representative of the subject matter which is broadly contemplated
by the present
invention. It is further understood that the scope of the present invention
fully
encompasses other embodiments that may become obvious to those skilled in the
art and
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that the scope of the present invention is accordingly limited by nothing
other than the
appended claims.
