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Title:
IMPROVED HOVER VACUUM CLEANING APPARATUS
Document Type and Number:
WIPO Patent Application WO/2007/068922
Kind Code:
A2
Abstract:
An improved hover vacuum cleaner (1) has a base with an outer wall (19) forming a cavity (20) and one or more keel skirts (22) which partition the cavity. Pressurised air extracted from the dust chamber is blown into the partitions, for example via a plenum in the outer wall (18) or a keel skirt. The keel skirts create separate air cushions for hovering, independent of each other, and each enhances the lift produced by the pressurised air leaving the cleaner. One or two of these air cushions may be compromised without affecting the performance of the remaining cushions. The cleaner also has two chambers (11, 12), connected by one or more conduits (9) so that the motor (16) extracts air from an inlet (4) through both chambers (11, 12) before expelling the air through the base. The motor (16) may be centrally mounted between the chambers (11, 12) for improved weight distribution.

Inventors:
MAILES MICHAEL T (CA)
Application Number:
PCT/GB2006/004662
Publication Date:
June 21, 2007
Filing Date:
December 13, 2006
Export Citation:
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Assignee:
SCOTCAN LTD (GB)
MAILES MICHAEL T (CA)
International Classes:
A47L7/06
Domestic Patent References:
WO1997012660A11997-04-10
WO2003016638A12003-02-27
Foreign References:
CA2301400A12001-09-20
US5799363A1998-09-01
JPH06133900A1994-05-17
DE1152507B1963-08-08
US3181636A1965-05-04
JPH04341229A1992-11-27
US3353621A1967-11-21
Attorney, Agent or Firm:
KENNEDYS PATENT AGENCY LIMITED (Glasgow G2 5QD, US)
Download PDF:
Claims:
Claims

1. A hover vacuum cleaning apparatus comprising: a chamber comprising a fluid inlet; an extraction means adapted to extract fluid from the chamber; an outer wall disposed substantially around the underside of the vacuum cleaning apparatus so as to form a cavity; and two or more output ports in fluid communication with the extraction means and adapted to allow the cavity to receive pressurised fluid from the extraction means, wherein the cavity comprises at least one partition adapted to partition the cavity so as to provide separate lifting fluid flows by restricting the fluid communication between the two or more output ports.

2. The hover vacuum cleaning apparatus of claim 1, wherein the at least one partition comprises at least one keel skirt.

3. The hover vacuum cleaning apparatus of claim 2, wherein the at least one keel skirt bisects the cavity.

4. The hover vacuum cleaning apparatus of any previous claim, wherein the outer wall comprises a plenum in fluid communication with the extraction means and adapted to receive the pressurised fluid from the extraction means and the plenum comprises the one or

more output ports adapted to allow the cavity to receive the pressurised fluid from the plenum.

5. The hover vacuum cleaning apparatus of any previous claim, wherein the at least one partition comprises a plenum in fluid communication with the extraction means and adapted to receive the pressurised fluid from the extraction means and the plenum comprises the one or more output ports adapted to allow the cavity to receive the pressurised fluid from the plenum.

6. The hover vacuum cleaning apparatus of any previous claim, wherein the output ports comprise output port filtering means.

7. The hover vacuum cleaning apparatus of claim 6, wherein the output port filtering means comprises a coarse filter.

8. The hover vacuum cleaning apparatus of any previous claim, wherein fluid flow into the cavity is sufficient to effect lift of the vacuum cleaning apparatus with respect to a surface when the vacuum cleaning apparatus is placed on the surface.

9. The hover vacuum cleaning apparatus of any previous claim, wherein the vacuum cleaning apparatus further comprises wheels.

10. The hover vacuum cleaning apparatus of any claim 9, wherein the wheels are retractable into the vacuum cleaning apparatus.

11. The hover vacuum cleaning apparatus of any of claims 9 to 10, wherein the plenum further comprises the wheels.

12. The hover vacuum cleaning apparatus of any of claims 9 to 11, wherein the apparatus further comprises an exhaust for the pressurised fluid from the extraction means when the wheels are in use.

13. A vacuum cleaning apparatus comprising: a first chamber comprising a fluid inlet; a second chamber; one or more fluid conduits enabling fluidic communication between the first chamber and the second chamber; and an extraction means adapted to extract fluid from the second chamber, wherein the one or more fluid conduits provide one or more fluid flow paths to extract fluid from the first chamber into the second chamber, causing fluid to be drawn into the first chamber via the fluid inlet.

14. The vacuum cleaning apparatus of claim 13, further comprising a base, the extraction means located centrally with respect to the base, and the first chamber and the second chamber located on the base and arranged around the extraction means.

15. The vacuum cleaning apparatus of claims 13 or 14, wherein the second chamber has substantially the same volume as the first chamber.

16. The vacuum cleaning apparatus of any of claims 13 to 15, wherein the vacuum cleaning apparatus is adapted to hover .

17. The vacuum cleaning apparatus of claim 16, adapted to hover when fluid is being extracted through the fluid inlet.

18. The vacuum cleaning apparatus of claims 16 or 17, adapted to hover when the apparatus is switched on.

19. The vacuum cleaning apparatus of any of claims 13 to 18, wherein the first chamber further comprises first filtering means.

20. The vacuum cleaning apparatus of claim 19, wherein the first filtering means comprises a coarse filter.

21. The vacuum cleaning apparatus of any of claims 19 to 20, wherein the first chamber is adapted to provide a first input fluid flow and a second input fluid flow between the input port and the one or more fluid conduits, the first input flow being through the first filtering means and the second input flow bypassing the first filtering means.

22. The vacuum cleaning apparatus of any of claims 13 to 21, wherein the second chamber further comprises second filtering means.

23. The vacuum cleaning apparatus of claim 22, wherein the second filtering means is a fine filter.

24. The vacuum cleaning apparatus of any of claims 13 to 23, wherein the second chamber is adapted to provide a working fluid flow between the one or more fluid conduits and the extraction means which makes use of substantially all of the volume of the second chamber .

25. The vacuum cleaning apparatus of claims 22 to 24, wherein the second filtering means is comprised of a portion of the second chamber adjacent the extraction means.

26. The vacuum cleaning apparatus of any of claims 13 to 25, wherein the one or more fluid conduits further comprise third filtering means.

27. The vacuum cleaning apparatus of any of claims 13 to 26, wherein the vacuum cleaning apparatus further comprises a first plenum in fluid communication with the extraction means such that the first plenum is pressurised with fluid extracted from the second chamber .

28. The vacuum cleaning apparatus of claim 27, wherein the first plenum comprises first plenum output ports.

29. The vacuum cleaning apparatus of claim 28, wherein the first plenum output ports facilitate a pressure release means in the event that the pressure of fluid inside the first plenum exceeds a threshold value.

30. The vacuum cleaning apparatus of any of claims 27 to 29, wherein the extraction means is housed within the first plenum.

31. The vacuum cleaning apparatus of any of claims 27 to 30, wherein the vacuum cleaning apparatus further comprises a second plenum arranged beneath the first plenum and is adapted to receive pressurised fluid from the first plenum.

32. The vacuum cleaning apparatus of claim 31, wherein the second plenum is disposed substantially circumferentially around the underside of the vacuum cleaning apparatus so as to form a cavity, the second plenum comprising one or more second plenum output ports to allow the cavity to receive pressurised fluid from the second plenum.

33. The vacuum cleaning apparatus of claim 32, wherein the second plenum output ports comprise second plenum output port filtering means.

34. The vacuum cleaning apparatus of claim 33, wherein the second plenum output port filtering means is a coarse filter.

35. The vacuum cleaning apparatus of any of claims 13 to 34, wherein the fluid flow into the cavity is sufficient to effect lift of the vacuum cleaning apparatus with respect to a surface when the vacuum cleaning apparatus is placed on the surface.

36. The vacuum cleaning apparatus of any of claims 32 to 35, wherein the cavity further comprises at least- one keel skirt, the at least one keel skirt adapted to partition the cavity so as to provide separate lifting fluid flows by restricting the fluid communication between two or more second plenum output ports.

37. The vacuum cleaning apparatus of any of claims 13 to 36, wherein the first chamber comprises a first removable cover.

38. The vacuum cleaning apparatus of any of claims 19 to 35, wherein the first chamber comprises a removable insert, the removable insert comprising the first filtering means.

39. The vacuum cleaning apparatus of any of claims 13 to 38, wherein the second chamber comprises a second removable cover.

40. The vacuum cleaning apparatus of claim 39, wherein the first and second removable covers comprise sealing gaskets disposed around the perimeters of the covers so as to provide a fluid seal with the rest of the chamber.

41. The vacuum cleaning apparatus of any of claims 13 to 40, wherein the input port is adapted to receive a hose or other suitable vacuum cleaner attachments.

42. The vacuum cleaning apparatus of any of claims 13 to 41, further comprising wheels

43. The vacuum cleaning apparatus of claim 42, wherein the wheels are retractable into the vacuum cleaning apparatus .

44. The vacuum cleaning apparatus of claims 42 or 43, wherein the second plenum further comprises the wheels .

45. The vacuum cleaning apparatus of any of claims 42 to 44, wherein the first plenum output ports provide an exhaust for the pressurised fluid in the first plenum when the wheels are in use.

Description:

Improved Vacuum Cleaning Apparatus

The present invention relates to improvements to vacuum cleaning apparatus, and to improvements of particular relevance to hover vacuum cleaning apparatus.

As is well known, with various developments made to address the problem of loss of suction caused by a blockage (e.g. when the bag/container is full) the extraction motor may be overloaded or overheat as it attempts to extract ^ against the blockage. Cyclonic separation type vacuum cleaners may not lose suction (as often advertised) but once full the extraction motor (s) is working against a blockage and may overheat.

Furthermore, vacuum cleaners generally are movable on wheels, of a variety of sizes and configurations. Notwithstanding the mechanical convenience of being able to wheel a vacuum cleaner about, the presence of wheels is in itself problematic. Wheels can get stuck, pick up dirt and transfer it from one place to another, and get tangled up with hair, string etc. Furthermore, wheels can cause damage to floorboards as they are repeatedly

W

run over the floor to vacuum clean. It is well known that wheels damage the edges of floorboards in particular. Wheeled vacuum cleaners are also not suitable for laminate flooring, where the wheels can actually leave marks on the surface.

One solution is to make a vacuum cleaner which hovers above the floor, removing the need for any physical contact between the vacuum cleaner and the floor.

Early hover vacuum cleaner performance was impeded significantly by poor stability and inefficient design. PCT Application Publication No. WO 00/16680 in the name M.J. Rooney and M. T. Mailes describes an underside arrangement comprising dished air chambers, an exhaust port and a groove in fluid communication therewith. Although this provides an elegant solution to the problem of poor stability, it places additional design and manufacturing constraints on the underside arrangement of the vacuum cleaner.

As vacuum cleaners fill up with dirt and dust, they begin to lose suction. Indeed, if suction decreases in the case of a single motor hover vacuum cleaner the decreased airflow will prevent it from being able to hover.

It is an object of the present invention to provide a more efficient vacuum cleaning apparatus. In light of the drawbacks of the prior art discussed above, it is also an object of at least one embodiment of the present invention to provide a vacuum cleaning apparatus capable of hovering with improved balance.

According to a first aspect of the present invention, there is provided a hover vacuum cleaning apparatus comprising: a chamber comprising a fluid inlet; an extraction means adapted to extract fluid from the chamber ; an outer wall disposed substantially around the underside of the vacuum cleaning apparatus so as to form a cavity; and two or more output ports in fluid communication with the extraction means and adapted to allow the cavity to receive pressurised fluid from the extraction means, wherein the cavity comprises at least one partition adapted to partition the cavity so as to provide separate lifting fluid flows by restricting the fluid communication between the two or more output ports.

This forms the basis for a hovering functionality whereby a fluid (e.g. air) "cushion" is created on the underside of the vacuum cleaning apparatus, within the confines of the outer wall.

Preferably the at least one partition comprises at least one keel skirt.

Preferably the at least one partition bisects the cavity.

Preferably the outer wall comprises a plenum in fluid communication with the extraction means and adapted to receive the pressurised fluid from the extraction means and the plenum comprises the one or more output ports

adapted to allow the cavity to receive the pressurised fluid from the plenum.

Alternatively the at least one partition comprises a plenum in fluid communication with the extraction means and adapted to receive the pressurised fluid from the extraction means and the plenum comprises the one or more output ports adapted to allow the cavity to receive the pressurised fluid from the plenum.

Preferably the output ports comprise output port filtering means.

Preferably the output port filtering means comprises a coarse filter.

Preferably the fluid flow into the cavity is sufficient to effect, lift of the vacuum cleaning apparatus with respect to a surface when the vacuum cleaning apparatus is placed on the surface.

Optionally the vacuum cleaning apparatus further comprises wheels.

The wheels will allow the vacuum cleaning apparatus to be moved when the hover is not in operation.

Optionally the wheels are retractable into the vacuum cleaning apparatus.

Optionally the plenum further comprises the wheels.

Optionally the apparatus further comprises an exhaust for the pressurised fluid from the extraction means when the wheels are in use.

According to a second aspect of the present invention, there is provided a vacuum cleaning apparatus comprising: a first chamber comprising a fluid inlet; a second chamber; one or more fluid conduits enabling fluidic communication between the first chamber and the second chamber; and an extraction means adapted to extract fluid from the second chamber, wherein the one or more fluid conduits provide one or more fluid flow paths to extract fluid from the first chamber into the second chamber, causing fluid to be drawn into the first chamber via the fluid inlet.

This leads to improved performance insofar as the extraction means is required only to extract fluid from the second chamber, relying on the extraction of fluid through the fluid conduits between the second chamber and the first chamber to extract fluid from the first chamber and subsequently effect suction through the fluid inlet. As a consequence, if the fluid inlet or the first chamber is blocked, the extraction means continues to extract fluid from the second chamber.

Preferably the vacuum cleaning apparatus further comprises a base, the extraction means located centrally with respect to the base, and the first chamber and the second chamber located on the base and arranged around the extraction means.

1

2 This offers particular benefits to hover vacuum cleaning

3 apparatus as it serves to provide an apparatus in which

4 weight is more evenly distributed and is subsequently

5 easier to control, and places less demands on the design

6 of the hover aspects. It also allows for the provision

7 of separate chambers for emptying. It also allows

8 convenient top-down access (relative to the base) to

9 allow the chambers to be emptied. 10

11 Preferably the second chamber has substantially the same

12 volume as the first chamber. ,13

14 This provide additional stability in that the apparatus

15 can be balanced around the extraction means, and also

16 benefits with regard to the distribution of the load on

17 the extraction means across both chambers . 18

19 Preferably the vacuum cleaning apparatus is adapted to

20 hover. Hovering may occur when in operation, that is

21 when fluid is being extracted through the fluid inlet, or

22 when the apparatus is switched on. 23

24 Preferably the first chamber further comprises first

25 filtering means. 26

27 Preferably the first filtering means comprises a coarse

28 filter. 29

30 Examples of such coarse filters are bag-type filters such

31 as those used in conventional upright vacuum cleaners, or

32 trays comprising a mesh to trap dirt and dust particles. 33

Preferably the first chamber is adapted to provide a first input fluid flow and a second input fluid flow between the input port and the one or more fluid conduits, the first input flow being through the first filtering means and the second input flow bypassing the first filtering means.

This further reduces the load on the extraction means when the first filtering means is blocked due to provision of a parallel fluid flow which still allows fluid flow through to the second chamber and on to the extraction means. Advantageously the first input fluid flow is adapted to retain substantially all of any dirt extracted through the input port, such that the second input fluid flow is substantially free from dirt.

Preferably the second chamber further comprises second filtering means.

Preferably the second filtering means is a fine filter.

An example of such a fine filter would be a HEPA or S- Class filter. HEPA/S-Class filters are capable of retaining at least 99.97% of particles as small as 0.3 μm in diameter. Alternatively ULPA filters can be used which are capable of retaining particles as small as 0.12 μm with an efficiency of 99.999%.

Preferably the second chamber is adapted to provide a working fluid flow between the one or more fluid conduits and the extraction means which makes use of substantially all of the volume of the second chamber.

Preferably the second filtering means is comprised of a portion of the second chamber adjacent the extraction means .

Preferably the one or more fluid conduits further comprise third filtering means.

Preferably the vacuum cleaning apparatus further comprises a first plenum in fluid communication with the extraction means such that the first plenum is pressurised with fluid extracted from the second chamber.

A plenum is an enclosure in which a fluid is at a pressure greater than that of the surroundings .

Optionally the first plenum comprises first plenum output ports.

The output ports provide an output for the pressurised fluid if the pressurised fluid is not to be subsequently used within the vacuum cleaner (e.g. for hovering) .

Optionally the first plenum output ports facilitate a pressure release means in the event that the pressure of fluid inside the first plenum exceeds a threshold value.

Preferably the extraction means is housed within the first plenum.

Preferably the vacuum cleaning apparatus further comprises a second plenum arranged beneath the first plenum and -is adapted to receive pressurised fluid from the first plenum.

Preferably the second plenum is disposed substantially circumferentially around the underside of the vacuum cleaning apparatus so as to form a cavity, the second plenum comprising one or more second plenum output ports to allow the cavity to receive pressurised f luid from the second plenum .

This forms the basis for a hovering functionality whereby a f luid ( e . g . air ) "cushion" is created on the underside of the vacuum cleaning apparatus , within the confines of said second plenum .

Preferably the second plenum output ports comprise second plenum output port f iltering means . Preferably the second plenum output port filtering means is a coarse f ilter .

Preferably the fluid flow into the cavity is sufficient to effect lift of the vacuum cleaning apparatus with respect to a surface when the vacuum cleaning apparatus is placed on the surface.

Preferably the cavity further comprises at least one keel skirt, the at least one keel skirt adapted to partition the cavity so as to provide separate lifting fluid flows by restricting the fluid communication between two or more second plenum output ports.

Preferably the first chamber comprises a first removable cover.

Preferably the first chamber comprises a removable insert, the removable insert comprising the first filtering means.

Preferably the second chamber comprises a second removable cover .

Preferably the first and second removable covers comprise sealing gaskets disposed around the perimeters of the covers so as to provide a fluid seal with the rest of the chamber.

Preferably, the input port is adapted to receive a hose or other suitable vacuum cleaner attachments.

Optionally the vacuum cleaning apparatus further comprises wheels. The wheels will allow the vacuum cleaning apparatus to be moved when there is no hover feature incorporated or if the hover is not in operation.

Optionally the wheels are retractable into the vacuum cleaning apparatus. Optionally the second plenum further comprises the wheels. Optionally the first plenum output ports provide an exhaust for the pressurised fluid in the first plenum when the wheels are in use.

The present invention will now be demonstrated by way of example only and with reference to the following figures in which:

Figure 1 illustrates schematically a cross-sectional side view of a vacuum cleaning apparatus in

accordance with an embodiment of the present invention;

Figure 2 illustrates schematically a cross-sectional side view (as shown in Figure 1) with detachable elements separated;

Figure 3 (a) and (b) illustrates schematically a cross-sectional (a) top-down view and (b) bottom-up view of the vacuum cleaning apparatus demonstrating the relative positions of components thereof;

Figure 4 illustrates schematically a cross-sectional end-on view of the vacuum cleaning apparatus, demonstrating the pressurisation of the upper and lower plenum;

Figures 5a and 5b illustrate schematically the underside of two embodiments of the vacuum cleaning apparatus, in figure 5a showing airflow relative to the lower plenum and keel skirts; and

Figure 6 illustrates schematically an airflow diagram showing the sequence of components through which the air flows.

With reference to Figures 1 to 4 there is shown an example of a hover vacuum cleaner 1 in accordance with the present invention, comprising a first chamber 2 and a second chamber 3. The first chamber 2 comprises an input port 4 disposed near the front-most end, adapted to receive a hose 5. Inside the first chamber 2 is a removable filter tray 6a which acts as a coarse filter

for removing dirt and dust particles from air drawn into the first chamber 2. This tray βa, when full, can be emptied and reinserted, or replaced each time.

The primary first chamber airflow 7 is from the hose 5, through the input port 4 , downwards through the removable filter tray 6a and out of the chamber 2. A secondary first chamber airflow 8 is established in parallel with the primary first chamber airflow 7, bypassing the removable filter tray 6a. It is envisaged that there will be a barrier (not shown) to prevent dirt or dust particles from being able to follow the secondary first chamber airflow 8, this may be by introducing some barrier which gravity acting on such a particle would not allow it to overcome, or by arrangement such that it is preferential for the particle to travel into the removable filter tray 6a. Also, the secondary first chamber airflow 8 is coarse filtered by a lower filter bed 6b, which serves to remove any dirt which has not been retained by the removable filter tray βa. It is envisaged that the lower filter bed 6b may also be arranged so as to provide a secondary course filtering to the removable filter tray 6a.

The second chamber 3 is connected to the first chamber 2 by means of a fluid conduit 9 which permits airflow therethrough. The fluid conduit 9 comprises a coarse filter 10 which prevents any particles which may have, for example, followed the secondary first chamber airflow 8 and bypassed the removable filter tray 6a and managed to pass through the lower filter bed 6b. The coarse filter 10 is also removable and/or replaceable, though

generally at less frequent intervals than that required for the removable filter tray 6a.

The first chamber 2 and the second chamber 3 are formed by first and second removable lids 11 and 12, respectively. Both lids 11 and 12 have a sealing gasket 13 located around the perimeter to form an airtight seal when the lids 11 and 12 are in place. This prevents leakage into the vacuum cleaner 1 and any resulting loss in suction. The removable lids allow access to the filters, etc. within, and facilitate dirt removal.

A fine filter 14 is located within the second chamber 3, at the location where the airflow through the chamber, i.e. the second chamber airflow 15, leaves the second chamber 3. This fine filter is, in this exemplary embodiment, a HEPA filter with an efficiency of 99.97% at a particle size of 0.3 μm. By coarse filtering in the first chamber 2 and separating the coarse filters 6a, 6b and 10 from the fine filter 14 by locating the fine filter 14 in the second chamber 3, the second chamber 3 can remain closed when removing and/or replacing the coarse filters 6a, 6b and 10. Opening the second chamber 3 would let dirt and dust in, and reduce the operating life of the fine filter 14. The fine filter 14 therefore needs replacing on a less frequent basis.

Air is extracted from the second chamber 3, through the fine filter 14, by means of an extractor motor (and fan) 16. The extractor motor 16 expels air into an upper plenum 17 in which the extractor motor 16 is housed. The effect of this is that the upper plenum 17 is pressurised with air which has been filtered by coarse 6a, 6b, 10 and

fine 14 filters. Beneath the upper plenum 17, on the base of the hover vacuum cleaner 1, is located a lower plenum 18.

The lower plenum 18 comprises an outer wall 19 which extends downwards and curves inwards with respect to the first 2 and second 3 chambers of the hover vacuum cleaner 1. This results in a cavity 20 being formed with a perimeter defined by the lower plenum 18. Pressurised air moves from the upper plenum 17 to the lower plenum 18 then flows from the lower plenum 18 into the cavity 20, the lower plenum 18 being arranged such that this airflow is relatively uniformly distributed. The air pressure within the cavity 20 enables the vacuum cleaner 1 to hover above a surface 21.

Figure 4 in particular illustrates the hover vacuum cleaner 1 hovering above a surface 21. The fluid conduits 9 joining the first chamber 2 and the second chamber 3 extend through the upper plenum 17. The extractor motor 16 is shown pumping air downwards to the lower plenum 18 where it is diverted into the cavity 20, thus providing an air-cushion.

The lower plenum 18 may comprise a number of exit ports (not shown) , that are calibrated and purpose-positioned so as to provide an optimum lifting effect.

Figure 5a demonstrates an advantageous lower plenum 18 and cavity 20 arrangement. Keel skirts 22 bisect the cavity 20 longitudinally and laterally so as to control the airflow and create four discrete cavities 20. The keel skirts 22 create four separate air cushions for

1 hovering, each independent of the others, and each

2 enhances the lift produced by the pressurised air leaving

3 the lower plenum. One or two of these air cushions may

4 be compromised without affecting the performance of the

5 remaining cushions. This configuration has particular

6 advantages in that the hover aspect is more efficient on

7 uneven surfaces, or surfaces with gaps or holes (such as

8 floorboards or tiles) . 9 0 Figure 5b demonstrates another lower surface and cavity 1 arrangement. One keel skirt 22 bisects the cavity 20 2 longitudinally so as to control the airflow and create 3 two discrete sub-cavities 20. The keel skirt 22 creates

14 two separate air cushions for hovering, each independent

15 of the other, and each enhances the lift produced by the

16 pressurised air from the motor. One of these air

17 cushions may be compromised without affecting the

18 performance of the remaining cushion. This configuration

19 also has particular advantages in that the hover aspect 20 is more efficient on uneven surfaces, or surfaces with

21 gaps or holes. The outer wall may be a plenum, as

22 described with reference to figure 5a, with air outlets

23 for the pressurised air from the motor. Alternatively,

24 the keel may comprise a plenum with the air outlets being

25 in the keel (or keels) . Another configuration is having

26 the air outlets in the base, i.e. the upper surface of 27 the cavity.

28

29 The advantage of hovering with improved balance in hover

30 cleaners, provided by the outer wall, output ports and

31 keel skirt (s) according to the present invention, is not

32 limited to cleaners with two chambers. ' 33

Finally, Figure 6 demonstrates schematically the sequence of steps through which air flows when the vacuum cleaner 1 is in operation. Air flows into the first chamber 2 and is coarse filtered 6a, 6b, 10. It then travels through the fluid conduits 9 to the second chamber 3, where it is subject to a fine filter 14 before travelling through the extractor motor 16 and into the upper plenum 17.

From the upper plenum 17 the air flows into the lower plenum 18 where it is subject to a further filter 23 before entering the cavity 20. This additional filter 23 is intended to remove any particles which are added to the airflow after passing through the fine filter 14. These may be, for example, carbon particles from the brushes in the extractor motor 16.

When it is not convenient to rely on the hover feature, wheels may be recessed into the base of the lower plenum 18. In the case where the vacuum cleaner is to be used in a non-hovering configuration, the upper plenum 17 may be vented to allow air to escape. In any case a pressure relief valve may be located on the upper plenum to prevent undue pressure build up in the event of a lower plenum blockage.

Wheels may be necessary if the surface is unsuitable for hovering, e.g. excessively dusty or excessively uneven. The wheels may pop down when required, or be a permanent feature. If permanent, they may be small enough or recessed to a sufficient degree that when hovering the wheels are substantially clear of the surface.

The extractor motor itself may be capable of operating at varying speeds, e.g. with a manual control located on the body of the vacuum cleaner. The varying speeds may produce varying degrees of lift which may be decided upon dependent on the surface. For example, a deep shag pile carpet might require more lift to raise the vacuum cleaner above the carpet. Conversely on laminate flooring the vacuum cleaner will not be required to hover as high.

These embodiments will facilitate a high performance vacuum cleaner capable of operating in a number of configurations from a basic wheeled system with HEPA filtered air being output from vents on the upper plenum to a "full-blown" hovering vacuum cleaner with variable speed options (either manual or automatic control) .

The foregoing description of the invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention herein intended.