Note: Descriptions are shown in the official language in which they were submitted.
CA 02330851 2001-O1-12
Title: VACUUM CLEANER CLEANING HEAD
FIELD OF THE INVENTION
This invention relates to the field of vacuum cleaners. In
particular, the invention relates to air flow in the cleaning head portion of
a
vacuum.
BACKGROUND OF THE INVENTION
Vacuum cleaners involve a suction fan typically driven by an
electric motor. The suction fan creates a negative pressure drawing
significant
amounts of air at relatively high flow rates through a cleaning head and into
a
dirt collection chamber. Typically the cleaning head includes a rotating
cleaning implement. The rotating cleaning implement typically involves
bristles but may also involve beater bars and the like. The purpose of the
rotating cleaning element is to impact the surface being cleaned such as
floors,
carpet, upholstery and the like so as to mechanically agitate the surface and
cause dirt particles to be raised up from the surface to be cleaned. Once the
particles are lifted from the surface to be cleaned, then the intention is
that
such dirt particles should become entrained in the air being drawn into the
suction fan.
The cleaning head of a vacuum typically defines a sole plate. The
sole plate is arranged generally opposite to and substantially parallel to the
surface to be cleaned. The sole plate defines a gap between the leading edge
of the sole plate and the surface to be cleaned. Air being drawn in by the
suction fan typically passes below the leading edge of the sole plate
travelling
rearwardly toward the cavity in which the brush is located. Some of the
incoming air passes below the axis of the cleaning implement more or less
along the surface to be cleaned and then passes upwardly into the vacuum
inlet or whatever tubing connects the vacuum inlet to the suction fan. This
air
flows in a relatively organized fashion. The air travels essentially in a
direction
parallel to the surface to be cleaned. This air stream entrains the liberated
dirt
particles and carries those particles into the suction conduit.
In many vacuum cleaning heads the cavity housing the cleaning
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implement is relatively large compared to the circumference of the circle
defined by the radially outermost rotating cleaning elements. The gap
between the cleaning head and the circle defined by the rotating elements
thus provides another path for incoming air being drawn into the suction
conduit. However, air passing above the axis of the cleaning implement, not
passing along or substantially next to the surface to be cleaned is not aiding
in
entraining particles which have been lifted from the surface to be cleaned.
Thus, in large measure this air is not productively assisting the cleaning
process.
The remainder of the incoming cleaning air passes beneath the
axis of the rotating brush and above the surface to be cleaned.
It would be desirable, if steps were taken to modify the flow
characteristics of the incoming air to assist in entraining dirt particles
which
have been lifted from the surface to be cleaned by the cleaning element. In
addition, it would be desirable to reduce air flow which does not entrain dust
particles which have been raised.
SUMMARY OF THE INVENTION
In accordance with this invention, a vacuum cleaner includes a
cleaning head. The cleaning head has a housing and the housing optionally
defines a brush cavity for containing an optional rotating cleaning implement
and a vacuum inlet aperture. The housing has a sole plate which, in use, will
be adjacent to a surface to be cleaned. The sole plate is adapted to direct
air
toward the vacuum inlet aperture. The cleaning head includes vortex inducing
structure for creating vortical flow in the air being directed toward the
vacuum inlet aperture.
In a preferred embodiment of the invention, the vacuum
cleaning head include structure for inducing a plurality of vortices in the
air
being directed toward the vacuum inlet aperture. Most preferably, the
vortices are oriented so that the axis of rotation of each vortex is
substantially
parallel to the surface to be cleaned so that air moving in the vortices
travels
closely adjacent the surface to be cleaned.
In another embodiment of the invention, the invention includes
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a method of entraining dirt particles in an air stream of a vacuum cleaner.
The
method includes the step of causing inlet air to be drawn between a sole plate
of a vacuum cleaning head and a surface to be cleaned and directing that air
toward a vacuum inlet aperture. The method also includes the steps of
inducing vortices in the incoming air to assist in entraining dust particles.
Preferably, the vortices created, cause the incoming air to rotate about axes
which are parallel to the surface to be cleaned and the vortices are closely
adjacent to she surface to be cleaned.
In a preferred aspect of the method, the method further
includes the step of inhibiting air flow through a secondary route between a
rotating cleaning element and a cavity in the cleaning head housing the
rotating element.
DETAILED DESCRIPTION OF THE DRAWINGS
A better understanding of the invention can be obtained from
reference to the following description of a preferred embodiment of the
invention, and in which:
Figure 1 illustrates the general arrangement of parts in a prior
art vacuum cleaner;
Figure 2 is a cross-sectional view through the cleaning head of
the prior art device illustrated in Figure 1;
Figure 3 is a view similar to Figure 2 showing a cross-section
through a cleaning head in accordance with a first embodiment of this
invention;
Figure 4 is a bottom view of a portion of the cleaning head of
Figure 3;
Figure 5 is a front view of the cleaning head of Figure 4;
Figure 6 is a view of one of the vortex inducing elements of the
cleaning head of Figure 3 showing a first form of vortex produced;
Figure 7 is a view similar to Figure 6 showing an alternate form
of vortex to be produced by the vortex inducing element;
Figure 8 is a diagrammatic illustration of vortices induced by the
structure shown in Figure 7;
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Figures 9a - a are front elevational views of the lower portion of
a cleaning head including vortex inducers according to the instant invention;
Figure 10 is a front perspective view of a sole plate including
vortex inducers according to the instant invention;
Figure 11 is a bottom plan view of the sole plate of Figure 11
showing the vortex inducers; and,
Figure 12 is a perspective view of the bottom of the sole plate of
Figure 11.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The general arrangement for a vacuum cleaner is illustrated in
Figure 1. Generally speaking, a vacuum cleaner 10 comprises a cleaning head
12, a body portion 14 and a handle 16. The body portion 14 may include a
motor 18 which drives a vacuum suction fan 20. The cleaning head 12 defines
a suction inlet conduit 22. The suction inlet conduit 22 of the cleaning head
12
is joined to a suction tube 24 in the body portion 14. The suction tube 24 of
the
body portion 14 terminates in an outlet 26. As shown in Figure 1, the vacuum
10 is placed to begin cleaning of a surface, in this case a carpet 30. Upon
operation, the suction fan 20 draws air into the vacuum 10. The air passes
beneath a sole plate 32 in a generally rearwardly direction as indicated by
arrow 34. The air will be drawn into the inlet conduit 22 and pass into the
suction tube 24. Upon exiting the outlet 26, the air, as shown by arrow 50,
enters the interior of the housing 14. The interior of the housing 14 may
separate the dirt from the air by means of various filter means or by using
cyclonic action or the like. Advantageously, the vacuum includes a final
filter
52 located just before the suction fan 20. Air, as shown by the arrows 54,
enters the final filter 52, passes through the suction fan 20 and then passes
over the motor 18 as shown by arrows 56 so that the motor is cooled. Air is
then exhausted from the vacuum through an outlet port as shown by arrow
58.
In Figure 1, the vacuum illustrated is what is referred to as an
upright vacuum. In another arrangement of these basic parts, a vacuum may
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be referred to as a canister vacuum. A canister vacuum will have a power
head similar to the power head 12 illustrated in Figure 1. However, the motor
18, the fan 20 and the dirt collection means may be located in a separate
module referred to as a canister. In a canister vacuum a handle is attached to
the cleaning head 12 rather than to the canister and suitable conduit means
are supplied to conduct the air from the conduit 22 in the cleaning head to
the
tube 24 within the canister.
Figure 2 is an enlarged view of a portion of the cleaning head 12
of the prior art device of Figure 1. The cleaning head 12 defines a cavity 60
for containing a rotating cleaning implement. As shown in Figure 2, the
rotating cleaning implement is a brush 62 having a plurality of radially
outwardly extending bristles 64. The bristles 64 may be arrayed about the
surface of the brush 62 in any convenient fashion. Typically these bristles
are
arranged in two rows which extend in spiral fashion along the surface of the
brush 62. The brush 62 rotates about an axis 66. As shown in Figure 2 the
brush is rotating counterclockwise as indicated by arrow 68.
As the brush rotates about the axis 66, the radially outwardly
limit of the bristles 64 describe a circle concentric on axis 66. This circle
is
illustrated by dotted line 70 in Figure 2. It will be observed that there is
substantial clearance between the circle 70 and the surface of the brush
cavity
60. This, in turn, means that as the air flows rearwardly as indicated by
arrow
34, the air stream splits into two streams, one indicated by arrow 36 and one
indicated by arrow 38. The air indicated by arrow 38 travels in the annular
gap between the circle 70 and the surface of the cavity 60 above the axis 66.
The air indicated by arrow 36 passes substantially along the carpet 30 beneath
the axis 66 of the rotating brush. The two air streams converge as indicated
by the arrows 38b and 36b where the air then enters an inlet aperture 80. The
two air streams merge as indicated by the arrow 82 and pass along the
suction inlet conduit 22.
Air indicated by the arrows 38 and 38b does not pass along
carpet 30 and thus does not materially assist in entraining particles which
have been raised from the carpet 30. The second component of the air
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indicated by the arrows 36 and 36b passes in a direction which is generally
parallel to the carpet 30 and serves to entrain particles raised up from the
carpet 30 by the action of the rotating brush 62.
Figure 3 is a view similar to Figure 2 and like parts have been
given similar numbers but with the prescript 1. Thus, the cleaning head 112 of
the vacuum cleaner 110 in accordance with this preferred embodiment is
positioned adjacent a surface to be cleaned, a carpet 130. The cleaning head
112 comprises a cavity 160. The cavity 160 accommodates a rotating brush 162
having a plurality of bristles 164. The radially outwardly limit of the
bristles
164 when rotating, define a circle 170. The brush 162 rotates about an axis
166.
The brush rotates counterclockwise as indicated by arrow 168. The cleaning
head 112 includes a sole plate 132 which is generally adjacent to the carpet
130. The cleaning head 112 also has a suction inlet conduit 122 having a
vacuum inlet aperture 180.
From review of Figure 3, it will be noted, that the circle 170
described by the tips of the bristles 164 is located substantially adjacent
the
surface of the cavity 160. The clearance between the circle 170 and the cavity
160 is reduced to a convenient minimum. The clearance must be such that the
tips of the bristles when the brush is installed, in its new condition, do not
strike the surface of the cavity 160 as the brush rotates. However, it is
desirable to reduce the clearance to an acceptable minimum so as to inhibit
any flow in the secondary flow route as indicated in the prior art in
connection with arrows 38 and 38b. Thus, in the embodiment illustrated in
Figure 4, for a given in-flow rate as shown at 134, more of the air is caused
to
pass adjacent to the carpet 130 by the virtual elimination of the secondary
air
flow route through the clearance gap between the surface of the cavity 160
and the brush 162. Because there is substantially no flow adjacent the surface
of the cavity 160, virtually all of the air passes in the general direction
indicated by arrow 137, below the axis of rotation 166 of the brush 162 and
adjacent the carpet 130. The air then passes, as indicated by arrow 183, into
the inlet aperture 180.
The cleaning head 112 further includes structure 190 for
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inducing at least one vortex in the incoming air stream. The vortex inducing
structure 190 may be located on the sole plate 132 and is intended to induce
at
least one vortex in the air being directed toward the vacuum inlet aperture
180 such that the airflow passing over the surface to be cleaned is
substantially vortical. The ratio of the width Wo of slots 200 to the width Ws
of the vortex inducer 190 preferably varies from 4:1 to 1:4, preferably from
3:1 to 1:3 more preferably from 1:2 to 2:1 and most preferably, is about 1:1.
Similarly, the ratio of the height Ho of slots 200 to the height Hs of the
vortex
inducer 190 preferably varies from 4:1 to 1:4, preferably from 3:1 to 1:3 more
preferably from 2:1 to 1:2 and most preferably, is about 1:1.
In the preferred embodiment shown in Figures 9b and 10 - 12,
the ratio of the width Wo of slots 200 to the width Ws of the vortex inducer
190 is 1:1 and the ratio of the height Ho of slots 200 to the height Hs of the
vortex inducer 190 is 1:1. Alternate workable profiles are shown in Figures 9a
- 9e. In the preferred embodiment shown in Figure 9a, the ratio of the width
Wo of slots 200 to the width Ws of the vortex inducer 190 is 1:2 and the ratio
of the height Ho of slots 200 to the height Hs of the vortex inducer 190 is
1:1.
In the preferred embodiment shown in Figure 9c, the ratio of the width Wo
of slots 200 to the width Ws of the vortex inducer 190 is 2:1 and the ratio of
the height Ho of slots 200 to the height Hs of the vortex inducer 190 is 1:1.
In
the preferred embodiment shown in Figure 9d, the ratio of the width Wo of
slots 200 to the width Ws of the vortex inducer 190 is 1:1 and the ratio of
the
height Ho of slots 200 to the height Hs of the vortex inducer 190 is 3:2. In
the
preferred embodiment shown in Figure 9e, the ratio of the width Wo of slots
200 to the width Ws of the vortex inducer 190 is 1:1 and the ratio of the
height
Ho of slots 200 to the height Hs of the vortex inducer 190 is 3:1.
As shown from the forgoing examples, when vortex inducers
190 are narrower than the slot 200 between them, effective vortices can also
be created (see Figure 9c). Alternately, when the vortex inducers may be
wider (e.g. twice as wide) than the slot between them, effective vortices can
also be created (see Figure 9a).
Preferably, a plurality of vortices are induced along essentially
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the entire length of the front of the vacuum cleaner. Thus, the air drawn in
by
the suction fan passes between the sole plate 132 and the carpet 130, as
indicated by arrow 134. The air passes through the vortex inducing structure
190 under the rotating brush 162 and into the aperture 180.
Figure 4 illustrates a portion of the sole plate 132 of the cleaning
head 112 illustrated in Figure 3. From reference to Figure 4, it will be noted
that the vortex inducing structure 190 comprises a plurality of blade members
190a. There are 12 such blade members 190a shown in Figure 4 which are
aligned to interact with the incoming air flow as indicated by the arrows 134.
Most of the air being drawn into the vacuum inlet port 182 will enter the
cleaning head 112 adjacent the leading edge 113. Wheels or other structure in
the cleaning head 112 may inhibit air flowing in from the sides of the
cleaning
head 112. As shown in Figure 4, the air stream indicated by arrows 134 is
flowing substantially rearwardly from the leading edge 113 toward the inlet
aperture 182. Each of the individual blade members 190a creates a vortex
downstream of the blade member 190a. This is indicated generally by the
lines 194.
Figure 5 illustrates the cleaning head 112 from the front, located
adjacent the carpet 130.
Figures 6 and 7 illustrate two slightly differently shaped blade
members 190a and 190b. The shape of the blade members can be any shape
which creates a downstream vortex in the air stream passing by the blade
member 190a or 190b respectively.
As shown in Figure 6, the blade member 190a creates a single
downstream vortex which may be substantially aligned with the general axis
of symmetry 191 of the blade member 190a. In this case, the air streams
passing along either side face of the blade member 190a meet to form the
vortex 194. The vortex 194 spins about an axis 195 which is aligned with axis
191. The precise shape, location and configuration of the vortex 194 will
dependent on the particular shape and configuration of the blade member
190a. A single vortex 194 for each such blade member 190a has been
illustrated in Figure 4.
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Figure 7 illustrates an alternately shaped blade member 190b.
Blade member 190b produces a pair of vortices on either side of the general
axis of symmetry 193 of the blade member 190b. These vortices are shown as
196a and 196b. The vortices 196a and 196b are caused to spin about axes 198a
and 198b respectively. For reasons which will be discussed below,
advantageously, the direction of spin in vortex 196a is opposite to the
direction of spin in the vortex 196b.
The vortex 194 is spinning about the axis 195 while the vortices
196a and 196b are spinning about their respective axes 198a and 198b. All
three of the axes 195,198a and 198b, lie substantially parallel to the carpet
130.
Thus, the axes of spin of the vortices may be said to coincide with the arrow
137 showing the general direction of air flow in Figure 3. Each vortex is
therefore spinning about an axis which is substantially parallel to the carpet
130. The axis 137, 198a and 198b are adjacent the carpet 130. As the air spins
about its respective axis, in the vortices as discussed above, the air impacts
the
floor with relatively high velocity. Because of the spinning of the air in the
vortices, there is highly turbulent flow of the air adjacent to the carpet
130.
Thus, there is substantially increased turbulence at the flow indicated by
arrow 137 in Figure 3 as opposed to the flow as indicated at arrow 36 in prior
art devices. The air flow has a rearward component generated by the suction
fan. In addition, the air has a spiralling component generated by the vortex
inducing structure 190. This increased turbulence in the air assists in
entraining dirt particles which have been liberated from the carpet 130 by the
brush 164.
Conveniently, the brush 164 may be formed similar to brushes
commonly used in the vacuum art. Such brushes contain a plurality of bristles
arranged in two rows. The rows are arranged in spiral fashion along the
length of the brush 162. Thus, each vortex 194, 196a or 196b respectively is
not effected by the bristles 164 of the brush 162 except on those occasions
when a bristle is directly aligned with the particular member 190a or 190b,
respectively. If there are two rows of bristles on the brush 162, then this
interruption of the vortex will occur only momentarily, twice during each
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revolution of the brush 162. The vortex, however, will remain in place during
the remainder of a rotation of the brush 162.
Preferably, as shown in Figure 7, the vortex inducing structure
190 includes blade members 190b which produce a pair of counter rotating
vortices 196a and 196b. These are shown in the front view in Figure 5. One
vortex 196a and one vortex 196b is induced by each individual blade member
190b. However, adjacent vortices 196a and 196b between adjacent blade
members 196b are rotating in complimentary directions. This is illustrated in
Figure 8. In figure 8, the vortices 196a and 196b for each of two blade
members 190b are illustrated. The outer elements of the adjacent vortices are
moving in the same direction. Thus, the turbulence of each vortex does not
dissipate but rather supplements the next adjacent vortex.
The plurality of vortices formed by the vortex inducing
structure 190 serves to assist in entraining dirt particles which are raised
from
the carpet 130 by the brush 162. The vortex may break up before the air
stream enters the vacuum inlet port 182. However, once dirt is entrained in
the air flow, the dirt tends to stay entrained. By utilizing the vortices as
explained herein, enhanced entrainment of the dirt raised by the cleaning
implement is achieved.
The vortex inducing structure 190 has been explained in
association with a plurality of individual members which are essentially tear
dropped shaped. Many other forms of vortex inducing structure may be
utilized.
The purpose of the vortex is to assist in entraining dirt raised by
the rotating cleaning element. Thus, the vortex inducing structure can be
located anywhere as convenient provided it produces vortices which are
effective to entrain dirt. As shown in Figure 3, the vortex inducing structure
can be attached to the sole plate 132 just forward of the cavity 160 for
containing the brush. However, the vortex inducing structure can be
mounted anywhere as desired.
In order to assist in maintaining the front of sole plate 132 at the
desired distance above the surface to be cleaned, wheels, glides or the like
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may be provided, preferably proximate leading edge 113, as is known in the
art. In the preferred embodiment of figures 10 - 12, wheel wells 202 are
provided adjacent opposed lateral sides of sole plate 132.
While the invention has been discussed in the context of certain
preferred embodiments, these embodiment are illustrative only. For the full
scope of the invention, reference should be made to the following claims. It
will be appreciated that cleaning head 112 may be utilized without the
operation of brush 162. Further, in some embodiments, cleaning head need
not include brush 162 or other like cleaning implement.
