Note: Descriptions are shown in the official language in which they were submitted.
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Title: VACUUM CLEANER
FIELD OF THE INVENfTION
The present invention relates generally to full size
vacuum cleaners. In one particular embodiment, the invention relates
to a bagless vacuum cleaner such as those which use cyclonic
separation.
BACKGROUND OF THE INVENTION
Over the past century, vacuum cleaners have evolved
from simple combinations comprising a suction fan as the motive
force, a filter bag as the dirt catcher media a.nd a hose and floor nozzle
to conduct dirt from the floor or furniture into the filter bag. In early
models, the suction fan would draw air from the floor nozzle through
a cloth or paper filter bag. The cloth or filter bag had pores or air holes
smaller than much of the dirt and debris thereby capturing the dirt and
debris within the filter bag while permitting the air which transported
the dirt to the filter bag to exit the bag. The main physical
characteristic of this type of system is that .as cloth or paper filter bag
fills with dust, dirt, hair, fibres and other debris, the pressure drop
across the filter bag dramatically increases. This is due to the pores
becoming blocked or at least partially blocked as the bag is filled.
Therefore, the suction fan must be designed to continue to deliver
significant air flow as the back pressure against which it operates
dramatically increases.
A fan can either be optimized in terms of energy
efficiency to operate effectively under high flow low back pressure
conditions or effectively under high flow high back pressure
conditions. The design conditions imposed by the use of filter bag
media has caused fans for vacuum cleaners to be optimized to produce
high flow conditions under high back pressure conditions.
In the 1980's and 1990's, vacuum cleaners using cyclonic
cleaning action began to be designed and manufactured. These include
vacuum cleaners which use a plurality of cyclones (eg. two or three
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cyclones) as the main filtration means. Others use a single cyclone in
combination with other filter media which. can become blocked with
the passage of dirt there through. Even wiith vacuum cleaners which
utilized solely or primarily cyclonic cleaning action, the fan has been
designed to produce a high flow under high back pressure conditions.
Thus, the energy required to operate the vacuum cleaner is significant.
Starting in the 1980's, designs were developed for full size
upright vacuum cleaners (as opposed to hand held portable vacuum
cleaners). Examples of these are United Stai;es Patent Nos.
4, 173,809; 5,014,388; 5,020,186; 5,084,934; and 5,115,538. A
disadvantage with existing vacuum cleaner designs (both those which
use filter bag media as well as cyclonic separators) is that they require
large amounts of power as a consequence of the high flow, high back
pressure operating characteristics of the vacuum cleaner. Despite the
apparent advantages of a cordless vacuum cleaner, to date, the designs
for battery operated vacuum cleaners have not provided a product
having a sufficient operating life while, at the same time, being of a
sufficient weight to be attractive to consumers and also cost
competitive.
SUMMARY OF THE INVENTION
Surprisingly, it has been found that full size cyclonic
vacuum cleaners do not require a motor ;and fan assembly that are
capable of operating under high back pressure conditions and produce
a high seal suction to provide good cleaning efficiency. In particular, a
full size upright vacuum cleaner (eg. weighing about 15 to 20 pounds)
and having a dirt collection capacity of a standard upright vacuum
cleaner and having a continuous operating life of 30 to 45 minutes or
more, may be prepared using a cyclonic separation means as the sole
or primary filtration stage wherein the motor is preferably positioned
downstream from the cyclone and is desi~med to operate efficiently
under high flow, low back pressure conditions.
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According to the instant invention, cyclonic vacuum
cleaners employ motors that are designed for use at high air flow rates
(preferably 30 - 80 cfm or more) and a low back pressure (preferably 2
- 8 kpa). Such motors may weigh as little as 500 g yet still provide
sufficient motive power to produce a high air flow rate (eg. 30 - 50 cfm)
through the vacuum cleaner. Despite the weight of the motor and fan
assembly, the motor and fan assembly are still sufficiently powerful to
also power an air driven turbine which is drivingly connected (eg. by a
fan belt) to a rotatably mounted brush in the cleaning head of the
vacuum cleaner.
An advantage of the instant invention is that the motor
runs substantially cooler (eg. the exhaust aiir may be at a temperature
of about 45°C or less compared with, eg., 65°C). Accordingly,
the
motor is less likely to overheat.
A further advantage of this motor design is that, due to
the lower operating temperature, the overall durability of the vacuum
cleaner may be improved. For example, the motor shroud, the motor
mount and the air flow path downstream of the motor are typically
made from plastic. The long term durability of plastic components is
predicated upon the operating temperatures to which they are
exposed. Lowering the operating temperature will increase the
operating life of these components. Further, by operating at lower
temperatures, different plastics may be u~5ed for these components
and/or these components may be of a thinner wall construction while
still maintaining comparable durability.
This invention may be used with upright vacuum
cleaners, canister vacuum cleaners, back pack vacuum cleaners or
related applications which preferably employ at least one cyclone
separator but do not include a traditional porous bag as the filter
medium. It will be appreciated that the vacuum cleaner may also use a
supplemental filter medium which does not have a large change in
back pressure during normal operation (eg., the difference in the back
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pressure between when the supplemental filter member is clean and
newly installed and when the supplemental filter member requires
cleaning or replacement may vary by about 2 - 4 kpa). Examples of
such supplemental filter medium are HEI'A filters and electrostatic
filters.
In accordance with the instant invention, there is
provided a bagless vacuum cleaner comprising a housing having a
clean air outlet; a cleaning member having a dirty air inlet; an air flow
path extending from the dirty air inlet to the clean air outlet; a primary
filtration stage comprising at least one cyclone particle separator
positioned in the air flow path downstream from the dirty air inlet, the
air flow path including the primary filtration stage having an
operational back pressure from 2 - to 12 kpa when the air flow path is
not blocked; and, a motor and fan assembly having an air flow rate
sufficient to transport the dirt in an air stream to the primary filtration
stage and to cause cyclonic separation in the cyclone particle separator
of particulates suspended within the air stream over the normal
operational range of back pressure of the vacuum cleaner when the air
flow path is not blocked.
In one embodiment, the vacuum cleaner further
comprises a battery for powering the vacuum cleaner.
The air flow rate is preferably from 30 to 80 cfm and,
more preferably, from 40 to 50 cfm. The back pressure is preferably
from 2 to 8 kpa.
In another embodiment, the motor and fan assembly is
positioned in the air flow path downstream from the cyclone air outlet.
In another embodiment, the rr~otor and fan assembly has
a combined efficiency of at least 33% based on the conversion of
electrical input to the motor and fan assembly to air watts over the
normal operational back pressure of the air :flow path.
In another embodiment, the motor and fan assembly has
a combined efficiency of at least 50% based on the conversion of
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electrical input to the motor and fan assembly to air watts over a back
pressure of the air flow path from 2 to 10 kpa.
In accordance with the instant invention, there is also
provided a vacuum cleaner comprising a housing having a clean air
outlet; a cleaning member having a dirty air inlet; an air flow path
extending from the dirty air inlet to the clean air outlet and including a
primary filtration stage; and, a motor and fan assembly mounted in
the housing and positioned in the air flova path, the motor and fan
assembly constructed to provide a high air flow rate and overcome a
low back pressure over the normal operational back pressure of the air
flow path.
In one embodiment, the primary filtration stage includes
a cyclone and the motor and fan assembly have an air flow rate
sufficient to entrain dirt entering the dirty air inlet and to cause cyclonic
separation in the cyclone particle separator of particulates suspended
within the fluid stream over the normal operational range of back
pressure of the vacuum cleaner when the air flow path is not blocked.
In accordance with the instant invention, there is also
provided a vacuum cleaner comprising dirty air inlet means; clean air
outlet means; an air flow path extending from the dirty air inlet means
to the clean air outlet means; filtration means comprising cyclonic
separation means positioned in the air flow path downstream from the
dirty air inlet means, the cyclonic separation means having cyclonic air
inlet means and cyclonic air outlet means; and, motor and fan means
positioned in the air flow path, the motor and fan means constructed
to provide a high air flow rate and overcome a low back pressure over
the normal operational back pressure of the air flow path through the
filtration means.
In one embodiment, the cyclonic separation means has a
back pressure from 3 to 6 kpa.
BRIEF DESCRIPTION OF THE DRAWINC:S
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For a better understanding of the present invention, and
to show more clearly how it may be carried into effect, reference will
now be made by way of example to the accompanying drawings
which show an embodiment of the present invention, in which:
Figure 1 is a perspective view of an upright cyclonic
vacuum cleaner;
Figure 2 is a front elevational view of the vacuum cleaner
of Figure 1;
Figure 3 is a side elevational view of the vacuum cleaner
of Figure 1; and,
Figure 4 is a cross-section along line 4 - 4 in Figure 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
While the vacuum cleaner of the instant invention may
be of any variety known in the art, the following description is based
on a full size upright vacuum cleaner.
As shown in the Figures, upright cyclonic vacuum 10 has
a floor cleaning head 12 and an upper bocly portion 30. Upper body
portion 30 is preferably pivotally mounted t:o cleaning head 12 such as
by a ball joint so as to pivot rearwadly along axis 78. Accordingly,
upper body portion 30 may be positionable in an upright storage
position as shown in Figure 1 wherein upper body portion 30 extends
generally vertically upwardly from cleaning head 12 when in the
above the floor cleaning mode. Upper body portion 30 may be
lockingly positioned in this place by a locking means as is known in the
art. When the locking means is released, upper body portion 30 may
be pivoted rearwardly to the floor cleaning mode.
Typically cleaning head 12 is provided at the lower end of
upper body portion 30 of vacuum cleaner 10. It will be appreciated that
cleaning head 12 and upper body portion 30 may be of any design
known in the art.
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As shown in the Figures, clearing head 12 may comprise
a forward portion 14 and two rear portions 16 extending rearwardly
from the forward portion 14. Rear portions 16 are spaced apart and
define a space 18 there between. Cleaning head 12 has a dirty air inlet
20 which is positioned in forward portion 14 and, preferably, adjacent
the front end of forward portion 21 (see Figure 4). Preferably, cleaning
head 12 also comprises a transversely e;ctending, floor-contacting
rotating brush member 22 which is mounted for rotation in cleaning
head 12. Brush member 22 may be powered by an air driven turbine
positioned in the air flow stream of by an electrically powered motor.
A handle 24 and rear wheels 26 may be provided to facilitate
movement of vacuum cleaner 10 for cleaning a floor and the like.
Cleaning head 12 may also incorporate a forward set of wheels (not
shown) as is known in the art. Preferably, cleaning head 12 includes
battery means 80 (eg. one or more individual batteries) for powering
fan and motor 32.
If the vacuum cleaner is convertible for above the floor
cleaning, handle 24 may be hollow and be connected to a flexible hose
28 for connecting handle 24 in air flow communication with the dirt
filtration means in upper body portion 30.
Upper body portion 30 incorporates the filtration means
for removing entrained dirt from the dirty air which is introduced into
the vacuum cleaner, via, for example, dirty air inlet 20. Upper body
portion 30 has motor and fan assembly 32 provided therein to draw
the air through vacuum cleaner 10. Preferably, as shown in Figure 4,
motor and fan assembly 32 is positioned downstream from the
filtration means or at least preferably downstream from the primary
filtration means. For example, a secondary filtration means (such as a
HEPA filter or an electrostatic filter) may be positioned upstream from
motor and fan assembly 32. It will be appreciated that, depending
upon the construction of vacuum cleaner 10, the filtration means and
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motor and fan assembly 32 may be placed at any desired locations in
the vacuum cleaner.
Motor and fan assembly 32 i;s constructed to provide a
high air flow rate and overcome a low back pressure over the normal
operational back pressure of the air flow path, i.e. when the air flow
path is not blocked. Motor and fan assembly 32 may have an air flow
rate during normal operation of from 30 to 80 cfm, preferably from 30
to 60 cfm and more preferably from 40 to 50 cfm. Such a motor and
fan assembly 32 may have overcome a back pressure of from 2 to 12
kpa, preferably from 2 to 10 kpa, more preferably from 2 to 8 kpa and
most preferably from 3 to 6 kpa. In a particularly preferred
embodiment, the motor and fan assembly produces is selected to
overcome a back pressure in the air flow path (including at least the
primary filtration means) of 2 to 8 kpa at an air flow rate of 30 to 60
cfm.
The efficiency of a motor and fan assembly includes the
efficiency of the motor itself at converting the electrical input to the
motor to rotational movement of a shaft to which the fan is attached
and the efficiency of the motor at converting the rotation of the fan to
movement of the air (i.e. air watts). This combined efficiency of the
motor and fan assembly is preferably greater than 33%, more
preferably greater than 50% and most preferably greater than 75%.
The filtration means of the vacuum cleaner uses
members that have a substantially fixed open passage there through
when the vacuum cleaner is in use. Thus, as dirt is removed from the
air stream passing through the filtration means, the size of the air flow
path remains generally constant and there is not a large increase in
back pressure over the filter means as entrained dirt is removed from
the air stream passing through the vacuum cleaner and collected in the
filter means. The increase in back pressure is preferably 10 kpa or less,
more preferably 8 kpa or less and most preferably 4 kpa or less. The
increase in back pressure is based on the back pressure when the filter
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means is new or has just been emptied and the back pressure when the
filter means is full. Preferably, the filtration means, or at least the
primary filtration means, comprises one or more cyclone separators.
The pressure drop (i.e. back pressure) across a cyclone
separator during normal operation remains substantially constant (eg.
the pressure drop may be 4 - 6 kpa). This occurs since a cyclone
separator has an air flow passage there through (i.e. the cyclone air
inlet, the cyclone chamber in which the cyclonic filtration occurs and
the cyclone air outlet) which in normal operation is of a constant fixed
size. "Normal" operation means that the air flow path through the
vacuum cleaner is not blocked by large objects, eg. objects large
enough to block a portion of the air flov~~ path to the cyclone, the
cyclone air inlet or the cyclone air outlet do not enter the air stream of
the vacuum cleaner or that a sufficient amount of separated dirt does
not accumulate in the cyclone chamber so as to prevent efficient
cyclonic separation therein. This is in contrast with standard filter bags
which are used with vacuum cleaners that have small pores therein
(eg. about 10E) that become blocked with small dirt particles.
The vacuum cleaner may include two or more dirt
separation stages provided that each stage does not have an air flow
path that will become blocked as air to be filtered passes there through
during normal operation of the vacuum cleaner. For example, the
primary filtration means of the vacuum cleaner may be a cyclone
separator and the secondary stage filtration means may comprise a
HEPA filter or a electrostatic precipitator. If a HEPA filter is used, it will
typically be positioned downstream from the motor and fan assembly
so as to remove carbon dust that is produced by the motor. The
pressure drop over a HEPA filter may be only about 4 kpa even when
the HEPA filter is full and requires replacement or washing. Thus the
total back pressure across the filtration means may be about 4 - 6 kpa if
the filtration means is a single cyclone separator. If the filtration means
is a cyclone separator combined with a HEP.A filter or the like, then the
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total back pressure across the filtration means may be less than about
kpa, preferably less than 8 kpa and most; preferably less than about
6 kpa even when the HEPA filter is full. Accordingly, the motor and
fan are selected to have an optimum flow performance in terms of
5 flow and suction to match the normal suctic>n and flow of the filtration
means.
A cyclone separator 36 which may be used in conjunction
with this invention is shown in the Figures in which cyclone separator
36 is the primary filtration means. Cyclone separator 36 may be
10 positioned in the lower portion of upper body portion 30. Cyclone
separator 36 may comprise any type of dirt separation cyclone known
in the art, e.g. cylindrical or frusto-conical, ;and may comprise a single
cyclone or multiple cyclones (either in series and/or in parallel).
Preferably, cyclone separator 36 comprises. a single cyclone. Cyclone
separator 36 comprises cyclone bin 38 defining a cyclone chamber 86
having an inner wall 40 defining a dirt rotation surface and an air inlet
42, typically at upper end 48 thereof,. Air inlet 42 is adapted for
providing an air flow tangentially to an inner wall 40 of bin 38. Ein 38
also has a dirt collection surface or bottom 44 and a clean air outlet 46.
Upper end 48 of bin 38 is sealed, such as by its engagement with the
housing of upper body portion 30 from which it is removably attached
(eg. by means of handle 76) so as to enable bin 38 to be emptied.
If the vacuum cleaner is used in the upright vacuum
cleaner mode, the air flow path through vacuum cleaner 10
commences with an air supply conduit 54 provided in cleaner head 14
having an upstream portion 56 in flow communication with dirty air
intake 20 and a downstream portion 58 adjacent valve 60. Valve 60
may be an on-off rotatable valve which is provided in cleaning head 14
for connecting dirty air inlet 20 in air flow communication with cyclone
separator 36 when the vacuum cleaner is used in the floor cleaning
mode (i.e. the handle is rotated rearwardly). Cyclone separator 36 has
a central air feed tube 62 having an upstream portion 64 in air flow
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communication with valve 60 and a downstream portion 66 in air flow
communication with curved passageway 68. Curved passageway 68 is
curved upwardly and outwardly from downstream portion 66 to
cyclone air inlet 42.
Centrally located in upper end 48 of bin 38 is a clean air
outlet 46 for permitting withdrawal of air from bin 38. From clean air
outlet 46, the air flow may proceed to vacuum fan motor assembly 32
or to a second stage of filtration, such as a second cyclone or other
filtration means (eg. an electrostatic precipitator). From the second
stage of filtration, the cleaned air may be i:n air flow communication
with vacuum fan motor 32.
As shown in Figure 4, motor and fan assembly 32 is
provided at the upper end of the housing of upper body portion 30
downstream from clean air outlet 46. If required, a supplemental
filtration means may be provided in caviity 50 (eg. a second stage
cyclone or an electrostatic precipitator). Further, a secondary filtration
stage, eg. a HEPA filter, may be positioned downstream from motor
and fan assembly 32 in cavity 52.
If vacuum cleaner 10 is used in the above the floor
cleaning mode, then dirty air will travel to central feed tube 62 via hose
28 and transverse passage 70. Any valuing arrangement known in the
art may be used to connect hose 28 in air flow communication with
cyclone separator 36 when vacuum cleaner 10 is used in the above the
floor cleaning mode and to isolate distalL end 74 of hose 28 from
cyclone separator 36 when the vacuum cleaner is used in the floor
cleaning mode (eg. a valve may be provided at distal end 74 of hose
28). Hose 28 may be connected to any vacuum nozzle means as is
known in the art.
In operation, the vacuum fan motor 32 is activated to
induce an air flow through vacuum cleaner 10. The air flow causes a
partial vacuum to form at dirty air inlet 20. Air, and entrained dirt, is
drawn into upstream portion 56, with the aid of brush member 22. The
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dirty air flow moves upwardly to dirty air' inlet 42 arid is introduced
tangentially to bin 38. The airflow is then accelerated around inner wall
40, and proceeds generally downwardly along and around iruler wall
40 until it reaches a position towards boti:om 44 of bin 38, at which
point the air flow travels upwardly through the central portion of
cyclone bin 38.
Bin 38 may incorporate a wall 'which is a cylindrical sleeve
72 extending downwardly from outlet 46 to assist in preventing the
cleaned air travelling upwardly to outlet 46 from mixing with the dirty
air which is introduced into bin 38 via inlet 32.
While the above description constitutes the preferred
embodiment, it will be appreciated that the present invention is
susceptible to modification and change without departing from the fair
meaning of the proper scope of the accompanying claims.
It will be appreciated that additional dirt separation
stages may be incorporated into the vacuum cleaner. For example, a
an open mesh screen to prevent elongate material such as hair and the
like from travelling downstream may b~e positioned between the
cyclonic separation stage and motor and fan assembly 32. The cooled
air may then exit the vacuum cleaner or may pass through a further
filtration stage positioned upstream of motor and fan assembly 32.
It will be appreciated that rr~otor and fan assembly 32
may be positioned at any stage in the air flow path through vacuum
cleaner 10 provided a sufficient amount of dirt has been removed from
the air so as not to damage or unduly damage motor and fan assembly
32.
