Note: Descriptions are shown in the official language in which they were submitted.
CA 02558129 2006-08-31
VACUUM CLEANER WITH DIRT COLLECTION VESSEL
HAVING A STEPPED SIDEWALL
Technical Field
The present invention relates generally to the floor care equipment field
and, more particularly, to a vacuum cleaner equipped with a dirt collection
vessel having a stepped sidewall providing enhanced cleaning efficiency.
Background of the Invention
A vacuum cleaner is an electro-mechanical appliance utilized to effect
the dry removal of dust, dirt and other small debris from carpets, rugs,
fabrics
or other surfaces in domestic, commercial and industrial environments. In
order to achieve the desired dirt and dust removal, most vacuum cleaners
incorporate a rotary agitator. The rotary agitator is provided to beat dirt
and
debris from the nap of the carpet or rug while a pressure drop or vacuum is
used to force air entrained with this dirt and debris into the nozzle of the
vacuum cleaner. The particulate laden air is then drawn into a dirt collection
vessel. The air is then drawn through a filter before being directed through
the
motor of the suction generator to provide cooling. Finally, the air is
filtered to
remove any fine particles of carbon from the brushes of that motor or other
dirt
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2
that might remain in the airstream before being exhausted back into the
environment.
Often the dirt collection vessel is designed to produce cyclonic airflow
by providing that vessel with a dirt chamber having a cylindrical sidewall and
a
tangentially directed air inlet. This arrangement forces the air to swirl
around
the dirt collection chamber in the manner of a cyclone. The centrifugal force
that is produced causes dirt and debris to move toward and against the
cylindrical sidewall of the chamber while relatively clean air may be drawn
off
from the center of the chamber through a prefilter toward the main filter and
the suction generator.
Under most operating conditions most or all of the dirt and debris is
removed from the airstream by the cyclonic airflow. At times, however, some
dirt and debris remains entrapped within the airstream. Typically, that dirt
and
debris is relatively fine dirt particles of light weight which are not as
susceptible to the centrifugal separation force produced by the cyclonic
airflow.
However, larger debris is sometimes drawn toward and closes some of the
airstream apertures provided in the prefilter. In such a circumstance, the
cleaning efficiency of the vacuum cleaner becomes impaired.
The present invention relates to a vacuum cleaner equipped with a dirt
collection vessel having a stepped sidewall. The stepped sidewall functions to
better separate dirt and debris from the airstream by preventing it from being
drawn back upwardly in the dirt collection chamber after it settles toward the
bottom. As a consequence, any potential for that dirt and debris to be drawn
on
or into the intake or airstream apertures of the prefilter is greatly reduced
or
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3
eliminated. The vacuum cleaner therefore operates at peak cleaning efficiency
at all times.
Summary of the Invention
In accordance with the purposes of the present invention as described
herein, an improved vacuum cleaner is provided. That vacuum cleaner
includes a nozzle assembly with a suction inlet and a canister assembly. A
suction generator is carried on one of the canister assembly and nozzle
assembly. Similarly, a dirt collection vessel is carned on one of the canister
assembly and the nozzle assembly. The dirt collection vessel includes a base
wall, a sidewall and a dirt collection chamber. Further, the dirt collection
vessel is characterized by the sidewall having a first cylindrical section
with a
circumference C, and a second cylindrical section with a circumference CZ
where C1 > C2. Further the dirt collection vessel is characterized by a step
connecting the first cylindrical section with the second cylindrical section.
More specifically, describing the invention the circumference C, is
between about 18.8 in. and about 25.1 in. The circumference CZ is between
about 15.7 in. and about 22.0 in. Further the first cylindrical section has a
height H, of between about 6 in. and about 7 in. The second cylindrical
section
has a height HZ of between about 5 in. and about 6 in. Together the
circumference C, and the height H, define a volume V ~ of between about 169.6
in.3 and about 351.9 in.3 while the circumference CZ and the height HZ define
a
volume VZ of between about 98.2 in.3 and about 230.9 in3. Further the step has
a width between the first cylindrical section and the second cylindrical
section
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4
of between about 0.1 in. and about 2.5 in.
In addition a support is concentrically received in the first cylindrical
section. The support projects from the base wall. A prefilter is carried on
the
support. The prefilter includes a third cylindrical section that carries an
angled
flange. The flange and the third cylindrical section meet at a vertex V
defining
an included angle AZ of between about 135 to about 165 degrees. The vertex V
is received concentrically within the second cylindrical section. Further the
flange includes a straight, continuous face. An annular gap is provided
between the flange and the end of the second cylindrical section. The gap has
a
width of between about 0.5 in. and about 2.5 in.
Still further, a filter is provided in the dirt collection chamber. The filter
is carried on the prefilter. A lid including a top wall closes an end of the
dirt
collection vessel opposite the base wall. The lid includes an inlet in
communication with the dirt collection chamber and an outlet in
communication with an upstream side of the filter.
In one possible embodiment the nozzle assembly is pivotally connected
to the canister assembly. Further, a rotary agitator may be carried on the
nozzle
assembly adjacent the suction inlet. In addition the canister assembly may
include a control handle.
In accordance with yet another aspect of the present invention, the step
between the first cylindrical section and second cylindrical section may
include
a channel opening toward the base wall. In such an embodiment that channel
could be defined by the first cylindrical section, the second cylindrical
section
and the step. The channel may include an arcuate bottom wall.
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In the following description there is shown and described several
preferred embodiments of this invention, simply by way of illustration of some
of the modes best suited to carry out the invention. As it will be realized,
the
invention is capable of other different embodiments and its several details
are
5 capable of modification in various, obvious aspects all without departing
from
the invention. Accordingly, the drawings and descriptions will be regarded as
illustrative in nature and not as restrictive.
Brief Description of the Drawing
The accompanying drawing incorporated in and forming a part of this
specification, illustrates several aspects of the present invention, and
together with the description serves to explain certain principles of the
invention. In the drawing:
Figure 1 is a perspective, partially broken-away view of the floor
cleaning apparatus of the present invention;
Figure 2 is an exploded perspective view of the dirt collection vessel,
filter and flow control valve assembly of the apparatus illustrated in Figure
l;
Figure 3 is a cross-sectional view of the dirt collection vessel, filter and
flow control valve assembly in the first position allowing for normal vacuum
cleaner operation;
Figure 4 is a schematical plan view illustrating the first flow valve in the
first position allowing normal vacuum cleaner operation;
Figure 5 is a cross-sectional view similar to Figure 3 but illustrating the
flow control valve assembly in the second position allowing cleaning of a
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6
section of the filter;
Figure 6 is a schematical plan view similar to Figure 4 but showing the
first flow valve in the second position allowing air to be drawn through the
clean air inlet;
Figure 7 is a detailed top perspective view of the filter assembly;
Figure 8 is a schematical illustration of an additional filter cleaning
feature that may be utilized to clean dirt and debris from the filter in situ
in the
dirt collection vessel; and
Figure 9a-9c are detailed, schematical illustrations of three possible
embodiments of the stepped sidewall for a dirt collection vessel.
Reference will now be made in detail to the present preferred
embodiments of the invention, examples of which are illustrated in the
accompanying drawing figures.
Detailed Description of the Invention
Reference is now made to Figure 1 which illustrates the floor cleaning
apparatus 10 of the present invention. In the illustrated embodiment, the
floor
cleaning apparatus 10 comprises an upright vacuum cleaner. It should be
appreciated, however, that the apparatus 10 may just as easily be a canister
vacuum cleaner or a handheld vacuum cleaner.
As illustrated, the apparatus 10 includes a housing 12 including both a
nozzle assembly 14 and a canister assembly 16. The nozzle assembly 14
includes a suction inlet 18 through which air entrained with dirt and debris
is
drawn into the vacuum cleaner. A rotary agitator 20 is mounted to the nozzle
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7
assembly 14 and extends across the suction inlet 18.
The canister assembly 16 includes a handle 22 having a handgrip 24.
An actuator switch 26 for turning the vacuum cleaner on and off is provided
adjacent the handgrip. In addition the canister assembly 16 includes a cavity
or
receiver 28 for receiving and holding a dirt collection vessel 30. A suction
generator 32 is mounted in a compartment in the canister assembly 16. During
operation, the rotary agitator 20 beats dirt and debris from the nap of the
rug or
carpet being cleaned. The suction generator 32 draws air entrained with that
dirt and debris through the suction inlet 18 into the dirt collection vessel
30.
The dirt and debris is trapped in the dirt collection vessel 30 and the now
relatively clean air passes through and over the motor of the suction
generator
32 to provide cooling before being exhausted through an exhaust port (not
shown) back into the environment.
As best illustrated in Figure 2, the dirt collection vessel 30 comprises a
dirt cup section 36 and a lid section 38. The dirt cup section 36 comprises a
stepped sidewall 35 and a bottom wall 37. The benefits provided by the
stepped sidewall 35 will be discussed in greater detail below. The lid section
38 comprises a first element 40, second element 42 and third element 43. The
first element 40 includes the dirty air inlet 44 and a filter cavity 46. The
second
element 42 includes a clean air outlet 48 and a clean air inlet 50.
A filter, generally designated by reference numeral 52, is received in the
filter cavity 46 of the first element 40. The filter 52 includes a sidewall
54, a
hub 56 and multiple partitions 58 extending between the hub and the sidewall
(see also Figure 7). The partitions 58 serve to divide the filter 52 into
multiple
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8
sections 60. A filter media 62, of a type well known in the art, extends
between the sidewall 54, hub 56 and partitions 58 defining each section 60.
An inner support 64 extends upwardly in the dirt cup section 36 from the
bottom wall 37. A prefilter 66 rests on the inner support 64. The prefilter 66
includes a series of intake apertures 68 that allow airflow in a manner that
will
be described in greater detail below.
In the illustrated embodiment, the dirt collection vessel 30 is designed to
produce cyclonic airflow and thereby use centrifugal force to improve the
efficiency with which dirt and debris are removed from the airstream. More
specifically, as clearly illustrated in Figure 2, the dirt cup section 36, the
lid
section 38, the inner support 64, the prefilter 66 and the filter 52 are all
substantially cylindrical in shape. As illustrated in Figures 3 and 5, the
inner
support 64 and prefilter 66 are concentrically received in the stepped
sidewall
35 of the dirt cup section 36. The filter 52 is concentrically received in the
filter cavity 46 of the first element 40 of the lid section 38. The dirty air
inlet
44 is tangentially directed into the annular space S formed between (a) the
first
element 40 and stepped sidewall 35 on the outside and (b) the inner support 64
and prefilter 66 on the inside. The airstream flows around the annular space S
in a circular or vortex pattern generating centrifugal force that causes dirt
and
debris in the airstream to move outwardly toward the stepped sidewall 35
thereby causing the dirt and debris to collect in the dirt cup section 36.
Simultaneously, the relatively clean air is drawn through the intake apertures
68
provided in the prefilter 66 along the inner wall of the annular space S where
it
is then directed upwardly through the filter 52. Specifically, the air passes
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through the filter media 62 where any fine dirt and debris remaining in the
airstream is stopped while clean air passes through the media on through the
clean air outlet 48 to the suction generator 32. The direction of airflow
during
normal vacuum cleaner operation is shown by action arrows in Figure 3.
The flow control valve assembly of the present invention is generally
designated by reference numeral 70. As best illustrated in Figure 2, the flow
control valve assembly 70 comprises a first flow valve 72 carried by a
cooperative valve body 71 that covers the clean air inlet 50. As best
illustrated
in Figures 4 and 6, two first flow valves 72 are each pivotally connected to
the
valve body 71 by a pivot pin 74. A torsion spring 75 is provided on each first
flow valve 72. The torsion springs 75 function to bias the first flow valves
72
into a first position, illustrated in Figure 4 wherein the first flow valves
72
close the two opposed ports 73.
Each first flow valve 72 includes a first cam follower 76. Each cam
follower 76 engages a first cam 78 mounted to or integrally formed on the
underside of a first drive gear 80. The drive gear 80 is driven by an
actuator.
In the illustrated embodiment the actuator comprises a meshing second drive
gear 82 and a cooperating stepper motor 84. In alternative embodiments the
actuator may comprise, for example, a manual twist knob/finger wheel or an
electrical solenoid and activation switch. The operation of the stepper motor
84 and the first flow valve 72 will be described in greater detail below.
As further illustrated in Figure 2, an air guide 86 is keyed to the first
drive gear 80. More specifically, the first drive gear 80 includes a hexagonal
shaft 85 that is received in a hexagonal opening 87 provided in the hub 89 of
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the air guide 86. As should also be appreciated, the air guide 86 includes an
inlet 88 and an outlet 90. The inlet 88 extends concentrically around the hub
89 while the outlet 90 projects radially outwardly in an arc of A° (see
also
Figure 7).
5 Referring back to the filter 52, each section 60 also has an arc of
A°. In
the illustrated embodiment, the filter 52 includes eight partitions 58
dividing
the filter 52 into eight equal sections 60, each spanning a 45° arc.
Thus, the
outlet 90 of the air guide 86 also spans a 45° arc, matching the arc of
each
individual section 60 of the filter 52. Of course, sections of other sizes
could
10 be provided (e.g. 12 sections each having an arc of 30°, 10 sections
each
having an arc of 36°, 9 sections each having an arc of 40°, 6
sections each
having an arc of 60°).
The flow control valve assembly 70 also includes a second flow valve
92. The second flow valve 92 includes an outer sidewall 94 and a mounting
hub 96 concentrically received in that outer sidewall. A second cam 98 is
provided on the air guide 86. A cooperating second cam follower 100 engages
the second cam 98. The second cam follower 100 includes a mounting shaft
102 having a pointed end 104 and a channel 106. The pointed end 104 is
extended into the mounting hub 96 of the second flow valve 92 and that hub
engages in the channel 106 so as to secure the second flow valve to the
mounting shaft 102.
As further illustrated in Figure 2, the second cam follower 100 includes
a hexagonal head 108. The hexagonal head 108 is received in the hexagonal
opening 110 in the first element 40 so that the second cam follower 100 is
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11
keyed to the lid section 38 to prevent relative rotation. A coil spring 112 is
received around the shaft 102 and held in the hexagonal opening 110 in the hub
of the first element 40. The spring 112 biases the second cam follower 100
into engagement with the second cam 98 at all times. As best illustrated in
Figures 3 and 5, the second flow valve 92 is concentrically received within
the
prefilter 66. An annular seal 114 is connected between the lower margin of the
second flow valve 92 and the wall of the prefilter 66. The annular seal 114
extends fully circumferentially between these two components.
The operation of the flow control valve assembly 70 will now be
described in detail. During normal vacuum cleaner operation, the suction
generator 32 draws air from the suction inlet 18 through the dirt collection
vessel 30 where dirt and debris is trapped and then exhausts clean air from
the
exhaust port. In order to do this, the flow control valve assembly 70 is
positioned as illustrated in Figures 3 and 4 so that the first flow valve 72
closes
the ports 73 leading to the clean air inlet 50 and the second flow valve 92
opens
the annular passage 116 between the angled flange 118 at the top of the second
valve 92 and the sidewall of the prefilter 66 so that air may pass from the
annular space S through the intake apertures 68 and the filter media 62 of the
filter 52 before passing through the outlet 48 to the suction generator 32.
As the vacuum cleaner continues to operate, fine dirt particles not
removed from the airstream by the cyclonic action in the annular space S is
stripped from the airstream and trapped by the filter media 62 of the filter
52.
Over time, these fine dirt particles begin to close off the pores in the
filter
media 62 thereby restricting airflow. This not only causes the motor of the
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12
suction generator 32 to run hotter and at a lower efficiency, it also reduces
airflow thereby adversely affecting the cleaning efficiency of the vacuum
cleaner. Consequently, the airflow may become so restricted as to prevent the
vacuum cleaner from cleaning properly. It is then necessary to either clean or
S replace the filter 52.
The present invention allows the filter 52 to be cleaned in situ in a very
convenient and efficient manner. Specifically, the stepper motor 84 may be
activated to rotate the air guide 86 through an arc of 45° by means of
the
meshing drive gears 80, 82. This functions to rotate the air guide 86 so that
the
outlet 90 thereof is exactly aligned over or in registration with one of the
sections 60 of the filter 52. The rotation of the first drive gear 80
simultaneously causes the first cam 78 to rotate from the position shown in
Figure 4 to the position shown in Figure 6. As this occurs, the cam followers
76 rise up on the first cam 78 and the first flow valves 72 pivot about the
pins
74 opening the ports 73 leading to the clean air inlet 50.
As the stepper motor 84 rotates the drive gear 80, first cam 78 and air
guide 86, the second cam 98 is also rotated. The second cam follower 100
rides upward on the cam 98 raising the second flow valve 92 so that the upper
edge thereof engages the prefilter 66 above the intake apertures 68 around its
full circumference. Thus, it should be appreciated that as the ports 73 open
through movement of the first flow valve 72, the second flow valve 92 closes
the air passage from the prefilter 66 to the outlet 48. Accordingly, the
suction
generator 32 draws clean air through the ports 73 and the clean air inlet 50.
That air is then drawn through the inlet 88 of the air guide 86 and then
directed
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by the outlet 90 thereof through the single individual section 60 of the
filter 52
with which the outlet is aligned. Since the clean air is moving through the
selected section 60 of the filter 52 in a direction opposite that of normal
operation, dirt (and particularly fine dirt from the pores of the filter), is
forced
from the filter media 62. The dirt expelled from the section 60 of the filter
52
being cleaned has a tendency to be trapped in the lumen or particle trap 120
of
the inner support 64. This is due in large degree to the shape of the support
which includes a frustoconical upper end 122 connected to a substantially
cylindrically shaped lower end 124 by an intermediate bottleneck section 126
of smaller circumferential opening than the lower end. The relatively clean
air
is then drawn back through the other sections 60 of the filter 52 not aligned
with the outlet 90 of the air guide 86 before passing through the outlet 48
and
moving on to the suction generator 32.
As should be remembered, the outlet 90 of the air guide defines an arc
only as wide as one section 60 of the filter 52. In the presently illustrated
embodiment that section has an arc of 45°. This means the remaining
sections
of the filter 52 not aligned with the air guide 86 define an arc of
315°. This is a
much larger cross-sectional area than the 45° arc through which the air
initially
passes. The resulting pressure drop helps to insure that dirt and debris
cleaned
from the section 60 of the filter aligned with the air guide 86 falls out of
the
airstream downwardly into the particle trap 120 of the support 64 where it is
retained. Accordingly, the fine dust and dirt particles cleaned from the
selected
section 60 of the filter 52 are not thereby deposited on the other sections of
the
filter during the cleaning cycle.
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14
The cleaning cycle may last, for example, from about 1 to about 30
seconds and more typically from about 3 to about 15 seconds. The stepper
motor 84 may then be activated again to rotate the first and second drive
gears
80, 82, the first cam 78 and the second cam 98 to thereby move the first flow
valves 72 from the open position to the closed position and the second flow
valve 92 from the closed position to the open position (i.e. move the flow
valves 72, 92 from the positions illustrated in Figures 5 and 6 to the
positions
illustrated in Figures 3 and 4). This returns the vacuum cleaner 10 to normal
operation where dirt and debris are drawn from the suction inlet 18 through
the
dirty air inlet 44 into the dirt collection vessel 30. There cyclonic airflow
utilizes centrifugal force to efficiently remove dirt and debris from the
airstream. That dirt and debris is captured in the annular space S of dirt cup
section 36 as relatively clean air is drawn through the intake apertures 68 of
the
prefilter 66. That air then passes through the passage 116 to the filter 52
where
any remaining fine particles are stripped from the airstream before it passes
through the outlet 48 and travels to the suction generator 32. The airstream
then cools the motor of the suction generator 32 before being exhausted back
into the environment through the exhaust port. Of course, it should be
appreciated that the stepper motor 84 may just as easily be activated so as to
clean any number of the filter sections 60 before returning to normal
operation
mode, depending on the judgment of the vacuum cleaner operator.
Reference is now made to Figure 8 schematically illustrating an optional
additional feature of the present invention that may be provided to further
enhance the cleaning of the filter 52. A clicker 130 may be provided. In the
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illustrated embodiment the clicker 130 includes an elongated mounting arm
131 that is held on a stub shaft 132 secured to the lid section 38. A
resilient
flap 134 is provided at each end of the arm 131. As illustrated the tips of
the
flaps 134 engage the media 62 of the filter 52 between the sidewall 54 and the
5 hub 56. A drive motor 136 is provided. As illustrated in full line in Figure
8
the drive motor may be connected to the clicker 130 and activated to rotate
the
clicker with respect to the lid section 38 and the filter 52. As the clicker
130 is
rotated, the tips of the flaps 134 engage the peaks of the ribbed filter
material
62 thereby vibrating the filter material and effectively loosening dirt and
debris
10 from the pores thereof. While the vibration provides good cleaning action
when utilized alone, it is particularly effective when utilized with the
pneumatic cleaning mechanism previously described in this document.
In an alternative arrangement also illustrated in Figure 8, the drive motor
is connected to the filter 52 (note dash line in drawing Figure 8). In this
15 arrangement the filter 52 is rotated while the clicker 130 and lid section
38
remain stationary. The result is the same in that the tips of the flaps 134
engage
the peaks of the ribbed filter media 62 as the filter is rotated thereby
vibrating
the media and loosening dirt and debris therefrom.
Reference is now made to Figures 9a-9c which schematically illustrate
three possible embodiments of the stepped sidewall 35. As illustrated in
Figure
9a, the stepped sidewall 35 of the dirt cup section 36 includes a first
cylindrical
section 150 and a second cylindrical section 152 connected together by an
annular step 154. As illustrated the step 154 and first cylindrical section
150
define an included angle Al of 90 degrees.
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16
In the embodiment illustrated in Figure 9b, the stepped sidewall 35
again includes a first cylindrical section 150, a second cylindrical section
152
and an annular step 154 that interconnects those two cylindrical sections. In
this embodiment the annular step 154 in the first cylindrical section 150
defines
an included acute angle A,, that is, an angle A, less than 90 degrees. As a
result a channel 156 is formed between the step 154 in the first cylindrical
section 150 of the sidewall 35. This channel 156 opens towards the base wall
37 of the dirt cup section 36.
Figure 9c illustrates yet another possible embodiment of the stepped
sidewall 35. In this embodiment the stepped sidewall 35 includes a first
cylindrical section 150, a second cylindrical section 152 and an annular step
154 connecting the first and second cylindrical sections. Together, the
cylindrical sections 150, 152 and annular step 154 def ne a channel 156 that
opens toward the base wall 37 of the dirt cup section 36. As illustrated in
phantom line at the right side of Figure 9c that channel 156 may have an
arcuate bottom wall if desired.
In any of the embodiments illustrated in Figure 9a-9c, the first
cylindrical section 150 has a circumference CI that is between about 18.8 in.
and about 25.1 in. The second cylindrical section 152 has a circumference CZ
that is between about I5.7 in. and about 22.0 in. The first cylindrical
section
has a height H, that is between about 6 in. and about 7 in. and the second
cylindrical section 152 has a height HZ that is between about 5 in, and about
6
in. The first cylindrical section 150 therefore defines a volume V, of between
about 169.6 in.3 and about 351.9 in.3 while the second cylindrical section 152
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17
defines a volume VZ of between about 98.2 in.3 and about 230.9 in.3. The
annular step 154 has a width between the first cylindrical section 150 and the
second cylindrical section 152 of between about 0.1 in. and about 2.5 in.
As further illustrated in Figures 9a-9c, the inner support 64 projects
from the base wall 37 and carries the prefilter 66. The prefilter 66 includes
a
third cylindrical section 158 incorporating the plurality of intake apertures
68
(for simplicity of illustration only eight apertures are shown). An angled
flange
160 depends from the third cylindrical section 158. The third cylindrical
section 158 and angled flange 160 meet at a vertex V defining an included
angle AZ of between about 135 to about 165 degrees. The vertex V is received
concentrically within the second cylindrical section 152: that is, it is
positioned
above the step 154 in the illustrated embodiments. As illustrated the angled
flange 160 also presents a straight continuous face 162. An annular gap 164 is
provided between the flange 160 and the end 166 of the second cylindrical
section 152. The gap 164 has a width of between about 0.5 in. and about 2.5
in. Further, the geometry of the prefilter 66, first cylindrical section 150
and
angled flange 160 are such that the dimension E equals the dimension F.
In any of the embodiments illustrated in Figures 9a-9c, the stepped
sidewall 35 provides for more efficient and effective cyclonic separation of
dirt
and debris from the airstream. More specifically, air is delivered to the dirt
collection vessel 30 through the tangentially directed inlet 44. As a result
the
airstream moves in a vortex pattern in the annular space S. As a consequence,
centrifugal force acts upon dirt and debris in the airstream causing it to
move
toward the surface of the sidewall 35. As the airstream is forced and moves
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18
toward the base wall 37 of the dirt collection vessel 30, the dirt and debris
previously flowing against the second cylindrical section 152 crosses the step
154 and begins moving in engagement with the first cylindrical section 150.
The annular step 154 in the Figure 9a embodiment and the channel 156 in the
Figure 9b and 9c embodiments then act as a physical barrier that prevents any
dirt and debris moving along the first cylindrical section 1 ~0 from rising up
to
move along the second cylindrical section 152. Thus, dirt and debris is
essentially captured in the portion of the dirt collection vessel 30 defined
between the first cylindrical section 150, the step 154 and the base wall 37.
Consequently dirt and debris is prevented from rising toward the intake
aperture 68 in the prefilter 66. As a consequence, dirt and debris is
prevented
from interrupting or otherwise interfering with the passage of air through the
intake aperture 68 and peak cleaning efficiency is provided at all times.
The foregoing description of a preferred embodiment of the present
invention has been presented for purposes of illustration and description. It
is
not intended to be exhaustive or to limit the invention to the precise form
disclosed. Obvious modifications or variations are possible in light of the
above teachings. For example, the air guide 86 of the illustrated and
described
embodiment extends through an arc of A° matching each section 60 of the
filter
52. The air guide 86 may in fact have an arc that is a multiple of A°
so as to
allow the cleaning of more than one section of the filter at one time.
Further,
the filter cleaning function may be automatic. It may be automatically
initiated
after a certain time period of operation or upon some event occurnng such as
the movement of the control handle 22 into the upright or storage position.
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19
Further, it should be appreciated that clean air from the suction generator
exhaust can be recycled to clean the filter.
The embodiment was chosen and described to provide the best
illustration of the principles of the invention and its practical application
to
thereby enable one of ordinary skill in the art to utilize the invention in
various
embodiments and with various modifications as are suited to the particular use
contemplated. All such modifications and variations are within the scope of
the invention as determined by the appended claims when interpreted in
accordance with the breadth to which they are fairly, legally and equitably
entitled. The drawings and preferred embodiments do not and are not intended
to limit the ordinary meaning of the claims and their fair and broad
interpretation in any way.
