GB2618413A

GB2618413A - Vacuum cleaning system

Info

Publication number: GB2618413A
Application number: GB2302856.6A
Authority: GB
Inventors: David Morte Morris Gareth; Gugala Mateusz
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2022-05-06
Filing date: 2023-02-27
Publication date: 2023-11-08
Also published as: WO2023214166A1; GB2618379A; GB202302856D0

Abstract

A vacuum cleaning system comprises a vacuum cleaner having a vacuum motor (12, fig 2), a dirt bin, a primary separation system (8, fig 2), a membrane filter 19, and an air valve arrangement 200 configured to control air flow through at least the membrane filter. The vacuum cleaner can operate in a surface cleaning mode of operation and a self-cleaning mode of operation. In the surface cleaning mode of operation, the vacuum cleaner is configured such that the vacuum motor draws dirty air from a dirty-air inlet through the dirt bin, the primary separation system and the membrane filter in a first airflow direction, and, in the self-cleaning mode of operation, the vacuum cleaner is configured to permit air to flow from the air valve arrangement through the membrane filter in a second airflow direction to clean dirt from the membrane filter. The membrane filter may be used as a pre-motor filter positioned upstream from the vacuum motor, or as a post-motor filter, positioned downstream from the vacuum motor, when considered in an airflow direction during a surface cleaning mode of operation.

Description

VACUUM CLEANING SYSTEM

BACKGROUND

Handheld vacuum cleaners and 'stick vacs' are popular household machines as they are lightweight and manoeuvrable compared to larger mains-connected cylinder and upright cleaners. The useful portability is usually achieved at least in part by being battery-powered, and many such machines now are bagless for convenience such that the collected dirt is stored in an integral dirt bin. Typically, handheld machines are used for frequent spot cleaning tasks but, as battery technology improves, the trend is towards longer cleaning operations. The trend for handheld vacuum cleaners to be the cleaner of choice for many households means that some users may prefer a larger dirt bin so that the cleaner can hold more dirt and debris between bin empties. However, the more compact size of battery-powered vacuum cleaners means that users have to perform regular maintenance such as bin emptying to keep them performing optimally. In addition to bin emptying, users are also required to carry out filter cleaning tasks occasionally in order to clean the fine air filters that such machines usually include to filter the discharged airflow. Such filters may meet I-TEPA standards of filtration so they need cleaning periodically to maintain their performance. Filter cleaning usually involves the user washing the filter in water and then leaving the filter to dry over an extended period, usually 24 hours or more during which time the vacuum cleaner cannot be used. It is desirable to be able to extend the life of such filters without requiring the user to wash them.

SUMMARY

In a first aspect, examples of the invention provide a vacuum cleaning system comprising a vacuum cleaner having a vacuum motor, a dirt bin, a primary separation system, a membrane filter, and an air valve arrangement configured to control air flow through at least the membrane filter. The vacuum cleaner is configured to be operable in a surface cleaning mode of operation and a self-cleaning mode of operation. In the surface cleaning mode of operation, the vacuum cleaner is configured such that the vacuum motor draws dirty air from a dirty-air inlet through the dirt bin, the primary separation system and the membrane filter in a first airflow direction, and, in the self-cleaning mode of operation, the vacuum cleaner is configured to permit air to flow from the air valve arrangement through the membrane filter in a second airflow direction to clean dirt from the membrane filter.

Usefully, therefore, airflow can be routed through the vacuum cleaner in a second direction to clean the caked on dirt from the membrane filter. The membrane filter may be used as a pre-motor filter positioned upstream from the vacuum motor, or as a post-motor filter, positioned downstream from the vacuum motor, when considered in an airflow direction during a surface cleaning mode of operation.

In addition to the air valve arrangement permitting air to flow through the membrane filter in the self-cleaning mode of operation, it may be further configured to cause air to flow across a surface of the membrane filter during the self-cleaning mode. Here, air flow across the surface of the membrane filter means that the air flows substantially parallel to the surface. By configuring the air valve arrangement to cause air to flow through the membrane filter, but also across the surface of the membrane filter during a self-cleaning mode of operation, the cleaning effect of the membrane filter is enhanced.

In some examples, the membrane filter is movably mounted within the vacuum cleaner, wherein said movement assists in dislodging dirt from the membrane filter. During this movement, the membrane filter is movable from a first position to a second position when the vacuum cleaner enters the self-cleaning mode of operation to assist in dislodging dirt from the membrane filter. The movement of the membrane filter may be combined with an impact from an impactor that is configured to provide a mechanical impact pulse to the membrane filter. This provides a further improvement to the cleaning of the filter during the self-cleaning mode of operation.

Movement of the membrane filter may be triggered by various events. In one example, movement of the membrane filter from the first position to the second position is caused by operation of the air valve arrangement. In another example, movement of the membrane filter from the first position to the second position is caused by opening of the dirt bin door. In either example, a mechanical or electronic triggering mechanism may trigger the movement of the membrane filter. Such movement may be powered by any suitable means, such as airflow through the membrane filter, or by way of a spring-loaded mechanism.

Although the reverse flow (in the second direction) of air through the membrane filter may be generated by the vacuum cleaner itself, in other examples of the invention, the vacuum cleaning system further comprises a docking station, wherein the docking station comprises a dirt storage chamber and an interface configured to mate with a dirt bin of the vacuum cleaner such that dirt expelled from the dirt bin through a bin opening is ejected into the dirt storage chamber of the docking station. In the self-cleaning mode of operation, the system is configured to: operate the vacuum generator to generate a partial vacuum in the dirt storage chamber and, once a sufficient negative pressure level has been generated, operating the air valve arrangement to cause a pulse of air to flow from the air valve arrangement through the membrane filter in the second airflow direction. In addition, the air valve arrangement may be adapted so that when it is operated when a sufficient negative pressure level has been generated, the air valve arrangement causes a pulse of air to flow into the dirt bin of the vacuum cleaner thereby to eject dirt from the dirt bin through the bin opening and into the dirt storage chamber.

The vacuum motor of the vacuum cleaner is used to discharge the dirt and dust in the vacuum cleaner into the dirt storage chamber of the docking station, which avoids the need for a further vacuum motor to be provided in the docking station. This reduces the energy usage for the bin emptying operation which improves system efficiency. The air pulsation function causes a high speed airflow through the bin to ensure that the dirt bin is emptied effectively and that dirt stuck to surfaces within the vacuum cleaner is removed during the emptying process.

Preferably the dirt bin is associated with a centrifugal or cyclonic separator which is adapted to cause a circulating flow of air which separates entrained dirt from the airflow. In this context, in one example the air valve arrangement is configured to generate a swirling air flow through the dirt bin. A swirling, or rotational, flow of air improves the efficiency with which the dirt is emptied from the bin compared to a flow of air that is directed generally axially through the dirt bin. Further, this type of airflow guards again dust getting stuck in localised patches inside the dirt bin.

The air valve arrangement may be operated by different methods. In one approach, the air valve arrangement may be electronically controlled and, as such, may be configured to communicate with a control system of the vacuum cleaner which commands the air valve arrangement to open and close intermittently in order to achieve the required one or more pulses of air. The time intervals which govern the opening and closing of the air valve arrangement may be set at a predetermined time period. Alternatively, the time intervals may be governed by the control system sensing the pressure within the dirt storage chamber of the docking chamber and actuating the air valve arrangement when a sufficient negative pressure has been detected. However, in another example the air valve arrangement is configured to be operated by differential pressure between the dirt bin and ambient environment.

Although a single pulse of high velocity air through the dirt bin of the vacuum cleaner may be sufficient to clear the membrane filter of dust, and, optionally, eject much of the dust, dirt and debris, preferably the air valve arrangement is configured to be operated repeatedly during sustained operation of the vacuum generator, thereby permitting a plurality of sequential air pulses to flow through the dirt bin. This is envisaged to a more thorough cleaning of the membrane filter of the vacuum cleaner, and a more effective ejection of dirt from the dirt bin. It should also be appreciated at this point that during the self-cleaning mode of operation, the airflow through the membrane filter may flow in the reverse direction, but also in the first airflow direction, for example as part of a pulsed operation to help dislodge dirt/caking from the membrane filter The dirt storage chamber may include a first chamber portion and a second chamber portion separated by a one way valve. Beneficially, this allows dirt to pass into the second chamber portion which is then trapped in that location by the valve. This reduces the tendency of dust to blow back out of the docking station, particularly when the vacuum cleaner is disengaged from it.

The second chamber portion of the dirt storage chamber may be removable or have a removable portion such as a bin, bucket or receptacle which allows the dirt stored therein to be removed. One option is for a removable air-permeable dirt bag to be provide in the second chamber portion which operates like a conventional vacuum cleaner bag. A user can therefore simply remove the bag when the docking station needs to be emptied. Since the docking station does not need to be portable, the bag can be made much larger than a typical vacuum cleaner bag so that it needs to be emptied less frequently, thereby providing particular convenience for the user.

In one example, the dirt storage chamber may include one or more air flow apertures to allow air to flow into it during the dirt bin emptying mode. This provides a flow of clean air to enter the dirt storage chamber during a bin emptying cycle which suppresses dirt blow back. Conveniently, the one or more air flow apertures are located in the first chamber portion.

In order to improve the cleaning effectiveness of the airflow in the dirt storage chamber, the one or more air flow apertures are configured to generate a swirling air flow around the dirt storage chamber.

The vacuum generator may create a negative pressure level in the dirt storage chamber by drawing air from the dirt storage chamber through the vacuum cleaner itself, as it would do during a normal vacuum cleaning operation. The system is envisaged to work particularly well with a vacuum cleaner which features a vacuum nozzle i.e. the suction inlet to the vacuum cleaner, which is at least in part surrounded by the bin door. This means that the bin door is engaged with the docking station and the vacuum nozzle accesses the interior of the dirt storage chamber for evacuating the air therefrom. Other configurations could however be acceptable. In such a situation, the interface between the vacuum cleaner and the docking station may be reconfigurable to enable it to mate, selectably, with a second vacuum cleaner. The docking station could then be used with different vacuum cleaning machines that are owned by the same user.

Features described above in connection with the first aspect of the invention are equally applicable to other aspects of the invention, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side view of a handheld vacuum cleaner; Figure 2 is another side view of the handheld vacuum cleaner of Figure 1 showing internal detail; Figure 3 is a view demonstrating how a dirt bin of the handheld vacuum cleaner of Figures I and 2 is emptied in a known manner; Figures 4 and S are side views of a vacuum cleaner system including a handheld vacuum cleaner and a docking station, wherein in Figure 4 the handheld vacuum cleaner is in an undocked position and wherein in Figure 5 the handheld vacuum cleaner is in a docked position; Figures 6, 7 and 8 are schematic views of a valve arrangement of the handheld vacuum cleaner in Figure 4 and 5 illustrating its principle of operation; Figures 9 and 10 show two phases of a bin emptying or self-cleaning' mode when the handheld vacuum cleaner is docked onto the docking station, wherein Figure 9 shows a phase of operation where the handheld vacuum cleaner operates to evacuate air rom the docking station, and wherein Figure 10 shows the handheld vacuum cleaner ejecting dirt into the docking station from the dirt bin of the vacuum cleaner; Figure 11 is a schematic view of an alternative example of a vacuum cleaner system including an alternative configuration of handheld vacuum cleaner docked onto a docking station; Figure 12 is a schematic view of a pre-motor filter in the form of a membrane filter housed within the handheld vacuum cleaner shown in the previous Figures, and includes an inset panel that illustrates components of the pre-motor filter in more detail, including a valve arrangement; Figure 13 is a schematic view of the pre-motor filter which shows the air valve arrangement controlling airflow through the pre-motor filter when the handheld vacuum cleaner is operating in a self-cleaning mode; Figure 14 is another schematic view of the pre-motor filter which shows the air valve arrangement controlling airflow through the pre-motor filter in an alternative route, also when the handheld vacuum cleaner is operating in a self-cleaning mode, Figure 15 is another schematic view of the pre-motor filter with the vacuum cleaner operating in a self-cleaning mode, wherein the pre-motor filter is being impacted by a mechanical agitation means or 'impactor'

DETAILED DESCRIPTION

Examples of the invention relate to a vacuum cleaning system including a vacuum cleaner which can in some examples be mated, engaged with, fitted to, or docked, to a corresponding docking station. Typically such docking stations are used as a power source to recharge a vacuum cleaner if that vacuum cleaner is battery powered However, the docking station and vacuum cleaner of the examples of the invention are configured to facilitate the removal and storage or dirt and debris that is emptied from the vacuum cleaner into the docking station. The vacuum cleaner may be battery powered, which is beneficial due to the portability advantages it provides, but this is not essential. Although vacuum cleaners in accordance with examples of the invention may be operated on the docking station to clear out dirt and debris, they may also in other examples be operated on their own without being docked onto a docking station.

Advantageously the vacuum cleaning system of the examples of the invention provides a vacuum-assisted bin emptying function without the need for an additional vacuum generator in the docking station. This makes the overall system less costly and more energy efficient.

Figures 1 to 3 show various views of a battery-powered or cordless handheld vacuum cleaner 2 which may be used in the system of the invention, thereby providing the reader with useful context.

Referring firstly to Figures 1 and 2, a handheld vacuum cleaner 2 comprises a main body 4 having an elongate handle 6, a primary separation system in the form of a cyclonic separating unit 8 having a longitudinal axis X and a cleaning tool 10, in the form of a nozzle, which is secured to the cyclonic separating unit 8. The cleaning tool 10 is detachable from the handheld vacuum cleaner which means it can be used for different cleaning tasks. In Figure 1, the cleaning tool 10 is in the form of a crevice tool.

However, in other examples, the cleaning tool 10 may be in the form of an elongated pipe or 'wand' which has a floor tool attached to its end distal from the vacuum cleaner 2. The cleaning tool 10 in this configuration therefore allows the vacuum cleaner to be used as a stick vac. The specific form of cleaning tool 10 which is used with the vacuum cleaner 2 is not important to the inventive concept but is shown in these Figures for context and completeness.

The cyclonic separating unit 8 extends away from the handle 6 such that the cleaning tool 10 is at the end of the cyclonic separating unit 8 which is furthest from the handle 6. The cleaning tool 10 extends away from the cyclonic separating unit 8 along the longitudinal axis X of the cyclonic separating unit 8.

The main body 4 further comprises a suction generator 11 comprising a motor 12 and impeller 13 which are located above and towards the rear of the handle 6. The components of the suction generator 11 are located in a motor housing or casing 15. The motor housing 15 is located adjacent to the cyclonic separator unit 8 so that airflow that exits the cyclonic separating unit 8 flows into the motor housing 15 to be expelled from the vacuum cleaner 2. The motor housing 15 may include a pre-motor filter 19 located in advance or upstream from the motor 12 and impeller with respect to the direction of airflow through the machine in order to filter out contaminants from the airstream that have not been separated by the cyclonic separating unit 8. The pre-motor filter 19 is shown schematically in Figure 2 and may take various structural configurations. The pre-motor filter 19 is positioned in a direction upstream of the motor 12 when considering the airflow direction through the cyclonic separating unit 8 and through the pre-motor 19 in normal operation of the vacuum cleaner. However, a post-motor filter (not shown) may be provided in addition to or instead of the pre-motor filter 19, in some

examples.

A battery 14 is located directly below the handle 6. An actuator in the form of a finger-operated trigger 16 is provided at an upper portion of the handle 6. A trigger guard 17 extends forwardly from the handle below the trigger 16. The handle 6 is arranged at an angle 01 with respect to the longitudinal axis X of the cyclonic separating unit 8 such that the handle 6 is in a pistol grip configuration. in the example shown, a handle axis H is arranged at 110 degrees with respect to the longitudinal axis X of the cyclonic separating unit 8. The angle is the included angle between the longitudinal axis X extending forward of the handle 6 and the portion of the handle axis H extending through the handle 6.

The cyclonic separating unit 8 comprises a primary cyclonic separator 18 and a plurality of secondary cyclonic separators 20 positioned downstream of the primary cyclonic separator 18. The primary cyclonic separator 18 is adjacent a first end of the cyclonic separating unit 8 and the secondary cyclonic separators 20 are adjacent a second end of the cyclonic separating unit 8 which is opposite the first end. The secondary cyclonic separators 20 are arranged in a circular array which extend about the longitudinal axis X of the cyclonic separating unit 8.

The primary cyclonic separator 18 comprises a separator body 22 in the form of a bin having a cylindrical outer wall 24 and an end wall 26. The cylindrical outer wall 24 defines a cyclonic separation chamber 28. In the example shown, it is the axis of the cyclonic separation chamber 28 which defines the longitudinal axis X of the cyclonic separating unit 8. A central duct 30 extends from the end wall 26 to an inlet 32 of the cyclonic separation chamber 28.

The cleaning tool 10 comprises a connector portion 33 and a nozzle portion 34 which define a duct 36 along the cleaning tool 10. The connector portion 33 has an outer diameter which is smaller than the inner diameter of the portion of the central duct 30 adjacent the end wall 26 such that the connector portion 33 can be inserted into the central duct 30 (as illustrated) thereby ensuring a rigid connection between the cleaning tool 10 and the cyclonic separating unit 8. This configuration is not essential, however, and the connector portion 33 may be configured in other ways to mate the cleaning tool 10 to the vacuum cleaner.

The cleaning tool 10 is provided with retaining features (not shown) which engage with the central duct 30 so as to secure the cleaning tool 10 to the central duct 30. The cleaning tool 10 further comprises an annular collar 43 that abuts the end wall 26 thereby holding the end wall 26 in the closed position, and so prevents accidental opening of the end wall 26 while the cleaning tool 10 is attached. The cleaning tool 10 has a manually operated catch 44 that is actuated in order to disengage the retaining features from the central duct 24 in order to remove the tool 10 from the cyclonic

II

separating unit 8 Again, it should be noted that these mechanical details are only exemplary and, as such, the cleaning tool 10 may take other forms and the cleaning tool 10 may be connected to the vacuum cleaner body 4 in other ways.

The central duct 30 and the duct 36 through the cleaning tool 10 together define an inlet duct 30, 36 which extends coaxially with the longitudinal axis X and through the end of the cyclonic separating unit 8 which is furthest from the handle 6. That is, through the end wall 26 of the separating unit. As shown here, the end wall 26 is perpendicular to the longitudinal axis X of the machine.

The inlet 32 of the cyclonic separation chamber 28 is spaced away from the end wall 26 and is located towards the end of the primary cyclonic separator 18 which is opposite the end of the cyclonic separating unit 8 to which the cleaning tool 10 is connected. The cyclonic separation chamber 28 therefore extends about or surrounds the portion of the inlet duct 30,36 formed by the central duct 30. A first portion of the central duct 30 leading from the end wall 26 extends along the axis X of the cyclonic separation chamber 28. A second portion of the central duct 30 extends from the first portion to the inlet 32 of the cyclonic separation chamber 28. The second portion extends in a direction which has both radial and circumferential components with respect to the cyclonic separation chamber 28 so as to promote rotational flow within the cyclonic separation chamber 28 during use.

The end wall 26 and the portion of the cylindrical outer wall 24 adjacent the end wall 26 define a dirt collector 38, which is in the form of a dirt collecting bin or more simply 'dirt bin', in which dirt separated from the incoming flow by the primary cyclonic separator 18 is collected.

The end wall 26 is connected to the cylindrical outer wall 24 by a pivot 40 and is held in a closed position by a user-operable catch 42. The end wall 26 can be moved from the closed position, in which dirt is retained within the dirt bin 38, to an open position, in which dirt can be removed from the dirt bin 38, by releasing the catch 42 and pivoting the end wall 26 away from the end of the cylindrical outer wall 24 The end wall 26 can therefore be considered to be a bin door of the dirt bin 38 which closes bin opening 27 of the dirt bin 38.

A cylindrical shroud 45 is disposed centrally within the cyclonic separation chamber 28 and extends coaxially with the axis of the chamber 28. Apertures 46 provided through the shroud 45 define a fluid outlet from the cyclonic separation chamber 28. Note that apertures 46 are shown as being distinct holes in Figure 2, although it is envisaged that in other examples the apertures 46 may be smaller and more numerous e.g. as part of a fine mesh or perforated membrane.

A duct 48, which is formed in part by the shroud 45, provides fluid communication between the outlet from the cyclonic separation chamber formed by the apertures 46 and inlets 49 of the secondary cyclonic separators 20. Each secondary cyclonic separator 20 has a solids outlet 50 at one end which is in communication with a fine dust collector 51 that extends along the side of the primary cyclonic separator 18. A fluid outlet 52 at the end of each of the secondary cyclonic separators 20 opposite the solids outlet 50.

In use, the handheld vacuum cleaner 2 is activated by a user pressing the trigger 16 with an index finger. Dirty air is drawn by the suction generator 11 through the inlet duct 30, 36 and through the inlet 32 into the cyclonic separation chamber 28. The rotational flow promoted by the second portion of the central duct 30 within the cyclonic separation chamber 28 produces a cyclonic action that separates relatively heavy or large dirt from the air. Cyclonic vacuum cleaners with dual cyclonic systems or a plurality of cyclonic systems are well-known in the art. Therefore, this discussion is provided for context and to illustrate one type of vacuum cleaner that is suitable for use within the examples of the invention.

Typically, the vacuum cleaner 2 is held such that the cyclonic separating unit 8 points downwardly from the handle 6. Dirt separated in the cyclonic separation chamber 28 therefore falls under the influence of gravity into the dirt bin 38. The partially cleaned air passes through the apertures 46 in the shroud 45 and is drawn along the duct 48 to the secondary cyclones 20. Smaller and lighter particles of dirt are separated from the air by the secondary cyclones 20 and expelled through the respective solids outlets into the fine dust collector 51. The cleaned air exits the secondary cyclones 20 via the respective fluid outlets 52 of the secondary cyclones 20 through the pre-motor filter 19 and suction generator 11, and the out of vents (not shown) at the rear of the main body 4.

Figure 3 shows the vacuum cleaner 2 being emptied in a known way. In order to empty the dirt bin 38 and the fine dust collector Si, the user first disconnects the cleaning tool 10. Then, whilst gripping the handle 6, the user points the vacuum cleaner 2 towards a suitable receptacle (e.g. a waste bin or bag) into which the dirt is to be emptied. The catch 42 is then released by the user and the end wall 26 pivoted from its closed position into its open position.

In an alternative arrangement, the inlet duct 30,36 may be spaced from the axis of the cyclonic separating unit 8. Nevertheless, the cyclonic separating unit 8 may be arranged to extend partly around a portion of the inlet duct or to entirely surround a portion of the inlet duct 30,36. For example, the inlet duct 30 may be recessed into the side of the cyclonic separating unit 8 such that duct extends within the profile of the cyclonic separating unit 8 when viewed along the axis of the cyclonic separating unit 8.

When emptying the vacuum cleaner 2, it will be appreciated that dirt and dust is ejected from the dirt bin 38 through the action of gravity. It is also known to include a mechanical agitator such as a plunger to urge the dirt out of the dirt bin 38. However, in an emptying operation, fine dust tends to float upwards which is undesirable for the user. Some examples of the invention are directed to address this issue.

Turning now to Figures 4 and 5, there is shown a schematic representation of the handheld vacuum cleaner 2 that is dockable with a docking station 60 thereby to define a vacuum cleaning system 62 although in other examples the vacuum cleaning system 62 may not require a docking station. The vacuum cleaner 2 shown in Figures 4 and 5 is similar in configuration to that shown in Figures 1 to 3. Therefore the same reference numerals will be used to refer to the same or similar parts.

In Figure 4, the handheld vacuum cleaner 2 is spaced from the docking station 60, whereas in Figure 5 the vacuum cleaner 2 is docked onto the docking station 60. As will become apparent from the discussion that follows, the vacuum cleaner 2 is operable in a bin emptying and/or 'self-cleaning' mode or of operation during which dirt contained in the dirt bin 38 is sucked into the docking station 60 due to a partial vacuum therein which has been generated by the vacuum cleaner 2.

Reference firstly will be made to the docking station 60. In this example, the docking station 60 has a generally cylindrical body 64 and is taller than it is wide. More specifically, its vertical height (as orientated in the Figures) is approximately three times its width, i.e. its diameter. It should be noted that the geometry shown here is only exemplary and as such the docking station 60 need not be cylindrical and may be differently shaped.

The body 64 of the docking station 60 is defined by a thin wall 66 having a base end 68 and a top end 70. The base end 68 rests on the floor (not shown) and stabilisation is benefitted by a flared stand 72 or foot. The foot 72 may be removable from the docking station 60 and is optional.

The top end 70 of the docking station 60 provides an interface 74 that is configured to engage with the vacuum cleaner 2. In principle the interface 74 may be configured in various ways, but it should provide the functionality that the central duct 33 of the vacuum cleaner 2 is able to communicate with the interior of the docking station 60 and that the pivotable end wall 26 of the dust collector 28 is able to open into the interior of the docking station 60 thereby exposing its contents.

In the illustrated example, the interface 74 is configured as an annular closure located on the top end 70 of the docking station 60. The interface 74 can be fixed to the body 64 of the docking station 60 so as to be removable and/or to be pivoted with respect to the body 64. Alternatively the interface 74 may be a fixed e.g. integral part of the docking station 60 such that it cannot be removed, although currently this is not considered preferable. An interface 74 that is removable may permit the replacement of a differently configured interface that is adapted for a different configuration of vacuum cleaner, as will be made apparent later.

The annular shape of the interface 74 defines a central opening 80 that is dimensioned to be comparable to that of the separator body 22 of the vacuum cleaner 2. The central opening 80 therefore receives the separator body 22 of the vacuum cleaner 2. Preferably the central opening 80 has a suitable sealing arrangement (not shown) such as a rubber lip seal or a type of fringe that seals against the outer surface of the separator body 22 although this is considered optional.

Turning now to the interior of the docking station 60, in Figure 4 and 5 it can be appreciated that the docking station 60 has a compartmentalised interior volume, in this example. In particular, the docking station 60 is configured to define a dirt storage chamber 82 and an intermediate chamber or antechamber 84. Both of these chambers 82,84 are surrounded by the interior volume 85 that is bounded by the outer wall 66 of the docking station 60. The intermediate chamber 84 provides a volume of space that leads from the interface 74 of the docking station 60 to the dirt storage chamber 82. The intermediate chamber 84 has a chamber wall 86 that is shaped in the form of a tapered chute and, as such, has a larger upper portion 87 which leads to a narrower throat portion 88. The vertical height of the throat portion 88 is, in the illustrated example, less than the vertical height of the upper portion 86. However, in other examples, the length of the throat portion 88 may be longer than this, which may provide benefits in terms of preventing dirt blow back from the dirt storage chamber 82.

A lower end of the throat portion 88 terminates at the dirt storage chamber 82. The dirt storage chamber 82 may depend or hang from the intermediate chamber 84, more specifically from the throat portion 88, in this example. Thus, the dirt storage chamber 82 may be removably clipped or otherwise be attached to the intermediate chamber 84.

A valve 89 separates the intermediate chamber 84, and more specifically the throat portion 88 thereof, from the dirt storage chamber 82. In this example, the valve 89 is a one-way or 'check' valve that is configured to permit dirt to travel into the dirt storage chamber 82 from the intermediate chamber 84, under the influence of a vacuum, as will be explained. Once pressure has normalised, the valve 89 closes to prevent dirt or dust travelling back into the throat portion 88 from the dirt storage chamber 82.

The dirt storage chamber 82 is shown here in the form of a generally oval shape, in cross section. However, this is for convenience only and as such the dirt storage chamber 82 may be either rigid or flexible in form. For example, it is envisaged that the dirt storage chamber 82 may be defined by a porous bag. The porous bag may be a woven or non-woven fabric, as may be used in conventional bagged vacuum cleaners which are known in the art. By virtue of the porosity of the dirt storage chamber 82, dirt and debris can be sucked into it due to vacuum in the interior volume 85 and whilst air can travel through the pores of the walls of the dirt storage chamber 82, dirt and debris is trapped inside. Instead of a porous bag, it is envisaged that the dirt storage chamber 82 may have a more rigid construction, for example as could be achieved by a porous fabric stretched over a skeletal frame or a porous fabric that is treated so as to have some rigidity. In either case, it is envisaged that the dirt storage chamber 82 is removable from the docking station. In this way, the dirt storage chamber 82 can be emptied, e.g. in a trash bin outside, or can be replaced with an empty dirt storage chamber 82. Although not shown in the figures, a suitable door may be provided in the wall 66 of the docking station 60 so that the dirt storage chamber 82 can be removed and replaced.

The upper portion 86 of the intermediate chamber 84 is provided with a set of apertures which allow air to enter the intermediate chamber 84 from the interior volume 85 of the docking station 60 This facilitates the formation of a vacuum within the docking station 60 by the vacuum cleaner 2, as will be described.

The apertures 90 may be valved to permit air to flow in one direction only, that is from the interior volume 85 of the docking station 60 to the interior of the intermediate chamber 84. In the illustrated example the apertures 90 may be configured to impart a swirl to the flow of air as it passes through the apertures 90 into the intermediate chamber 84. The valves of the apertures 90 may be in the form of slit valves of flap valves, for example.

As can be seen in the illustrated example, the intermediate chamber 84 is dimensioned such that it allows the dirt bin door 26 to pivot outwardly fully and hang down vertically inside the intermediate chamber 84, in the orientation of the drawings As has been discussed above, the vacuum cleaning system 62 is configured such that the vacuum cleaner 2 is operable, when docked on the docking station 60, to generate a vacuum within the intermediate chamber 84 and the dirt storage chamber 82 which is able to draw dirt and debris from the dirt bin 38 of the vacuum cleaner 2. This functionality is achieved during a bin emptying or self-cleaning mode of operation.

Such a mode may be a manual operation, as carried out by a user, or it may be an automatic operation which happens substantially without user intervention. In a broad sense, during a self-cleaning mode of operation, the vacuum cleaner 2 operates to generate a partial vacuum, compared to the ambient pressure level, in the dirt storage chamber 82 of the docking station 60. To this end, air within the dirt storage chamber 82 is drawn through the interior volume 85 and through the apertures 90 into the intermediate chamber 84, from where it is drawn into the vacuum cleaner 2. During this air evacuation process, the bin door 26 may be in an open position, but preferably it is closed. Opening of the bin door 26 may be achieved by a suitable bin opening mechanism 92. The bin opening mechanism is shown in Figures 4 and 5 as an actuating member 94 that is slidably attached to the separator body 22. The actuating member 92 includes a push rod 96 that engages with a part of the bin door 26. Sliding movement of the actuating member 94 drives the push rod 96 in a downwards direction, as shown in the drawings, which unlatches the bin door 26 so it can fall open under the influence of gravity, and due to the pressure differential across the bin door 26. The skilled person would appreciate that the bin opening function may be achieved in other ways. For example, an electronic system may be provided in which a servo-actuator is operable to open the bin door 26 in response to a button push by a user, or a pneumatic device that uses low pressure in the container to generate enough force to un-latch the bin catch 42.

Once a sufficient negative pressure level has been generated, an air valve arrangement 100 of the vacuum cleaner 2 is operated to admit a pulse of air into the dirt bin 38 which has the effect of ejecting dirt from the dirt bin 38 through the bin opening 27 and into the intermediate chamber 84. Dirt travels downwardly though the throat portion 88 and into the dirt storage chamber 82 where it is trapped by the porous walls. The airflow passages within the vacuum cleaner 2 can be configured to ensure that the pulse of air results in a high speed airflow through the machine that is effective at ejecting dirt from the dirt bin 38.

Although the air valve arrangement 100 is shown generally in Figures 4 and 5 t is shown in more detail in Figure 6, 7 and 8.

In a broad sense, the purpose of the air valve arrangement 100 is to allow a controlled burst or pulse of air to flow into and through the dirt bin 38 and out of the bin opening 27. As shown in Figures 6 to 8, the air valve arrangement 100 comprises one or more apertures 102 defined at an upper part of the separator body 22, near to the secondary cyclonic separators 20 (not shown in Figures 6, 7) Here, the apertures 102 are shown extending about the separator body 22 in a circumferential array. Other configurations would be acceptable but an array as shown provides an even spread of air to be admitted into the dirt bin 38 about the axis X of the separator body 22.

The opening state of the one or more apertures 102 are controlled by a valve member 104. The valve member 104 is movable between opened and closed positions. In the closed position the valve member 104 covers up the apertures 102 so that air is not able to flow through them. In the open position the valve member 104 uncovers the apertures 102 to allow air to flow through them. Figure 6 shows the valve member 104 in the closed position whereas Figure 7 shows the valve member 104 in the open position.

In the illustrated example the valve member 104 is configured as a collar or cuff that extends about the exterior of the separator body 22. As illustrated, the valve member 104 covers up the apertures 102 in the closed position and is moveable downwards (as oriented in the figures) by a distance sufficient to uncover the apertures 102, whereupon air is able to flow through the apertures. The valve member 104 may be biased into the closed position, for example by a suitably configured biasing spring (not shown) As shown in Figure 8, the apertures 102 may be configured to impart a rotational trajectory or swirl to the flow of air that enters the separator body 22. To this end, the apertures 102 may be defined by a series of vanes or louvres 106 that extend through the wall of the separator body 22 thereby defining the apertures 104 in the spaces between the vanes 106. The vanes 106 extend in a direction that is angled with respect to the radial direction from the central axis X. Here, the vanes 106 are shown as angled by approximately 45 degrees, although it should be appreciated that is only exemplary.

The movement of the valve member 104 may be controlled manually by the user of the vacuum cleaner 2. Alternatively, they may be controlled by an appropriate control system. The following discussion will focus on manual control of the valve member 104.

Having described the features of the docking station 60 and the vacuum cleaner 2, the discussion will now focus on how the vacuum cleaner 2 may be operated in order to carry out a self-cleaning operation, with a focus on Figures 9 and 10.

In Figure 9, the vacuum cleaner 2 is shown docked onto the interface 74 of the docking station 60. The vacuum cleaner 2 is operating, that is the vacuum cleaner 2 has been turned on by an operator/user, such that the suction generator 11 is drawing air along the inlet duct 30 of the vacuum cleaner 2 which evacuates air from the intermediate chamber 84, and also from the interior volume 85 of the docking station 60, which draws air out of the dirt storage chamber 82. As can be seen, air flows from the interior volume 85 through the apertures 90 in the intermediate chamber 84 which impart a swirling motion to the flow of air as it circulates around the intermediate chamber 84 and into the inlet duct 30 of the vacuum cleaner 2.

When a sufficient negative pressure is generated within the docking station 60, the dirt bin door 26 of the vacuum cleaner is opened. This may be achieved by the user actuating the bin opening mechanism 92. Currently it is envisaged that the bin emptying operation can be accomplished with the bin door 26 opened whilst the air within the docking station is being evacuated. However, it is believed that optimum results will be achieved with the bin door 26 closed until a sufficient vacuum has been generated in the docking station 60.

The level of vacuum that is considered to be efficient will depend on the power of the suction generator 11 and the volume or air within the docking station 60. However, it envisaged that a sufficient level of vacuum will be achieved between 0.5 and 2 seconds. For example, this could be achieved with a vacuum generator pumping approximately 20 litres per second in order to reduce the ambient pressure within the docking station from approximately 100kPa to approximately 75kPa. This represents a pressure drop of between 20kPa and 30kPa, and more preferably a pressure drop of between 23kPa and 28kPa. Whilst these values of pressure drop are considered to provide good results, it is possible for good functionality still to be achieved with a somewhat lower pressure drop.

In Figure 10, the bin door 26 of the vacuum cleaner 2 has been opened As a result, the interior of the dirt bin 38 is exposed to the vacuum present in the docking station 60, more specifically the intermediate chamber 84. Also, in this example, it will be noted that the vacuum generator 11 has been turned off by the user/operator. At this point, the air valve arrangement 100 is opened as can be seen by the valve member 104 being shown in a down or open position. This means that ambient air is drawn forcefully into the dirt bin 38 through the apertures 102, thereby causing a pulse of air to flow into the dirt bin 38 to eject the contents of the bin 38 into the docking station 60, as can be seen in Figure 10.

The flow of air from the dirt bin 38 into the docking station 60 flows through the intermediate chamber 84 and opens the valve 89 into the dirt storage chamber 82. The dirt and debris ejected from the dirt bin 38 of the vacuum cleaner 2 is therefore captured by the dirt storage chamber 82. Although the valve 89 is optional, its presence in this example of the invention ensures that dirt and debris is captured within the dirt storage chamber 82 and cannot travel back towards the vacuum cleaner 2.

At this point it should be noted that the open area or the apertures 102 should be configured to provide a high speed flow of air into the dirt bin 38. In configuring the open area of the apertures 102, account should also be taken of the negative pressure present in the docking station. It is believed that an open area of between 3500mm2 to 4500mm2 would provide a suitable air flow, and more preferably approximately 4000mm2. To ensure that the high speed air flow maintains flow speed through the dirt bin, one consideration is to ensure that the open area of the apertures 102 is not significantly more than the minimum cross sectional area of the volume inside the dirt bin 38, when taken in a plane perpendicular to the axis X of the separator body 22. If the cross sectional area of the dirt bin 28 is greater than the open area of the apertures 102 by more than a predetermined amount, this will result in the flow of air slowing down excessively as it progresses through the dirt bin 38 which could reduce the effectiveness of the air flow in ejecting the dirt and debris from the dirt bin 38. Therefore, it is preferred to configure the open area of the apertures 102 to be not smaller than 0.5 times the cross sectional area of the dirt bin.

Due to the high pressure differential between the dirt bin 38 and the docking station interior, and a large enough air bleed area through the apertures 102 of the air valve arrangement, the pulse of air into the docking station has a very high flow rate but only for short period of time. For example, it is believed that the above parameters are able to achieve a peak flow rate of around 2001/s with a pulse duration of below 0.1s. This results in a peak flow velocity of above 200m/s. If the flow area of the apertures 102 is smaller than the cross sectional area of the dirt bin 38, this has the effect of slowing down the flow speed through the dirt bin 38. However, even if the cross section area of the dirt bin is around twice that of the flow area of the apertures 102, flow speeds of above 100m/s are still achievable.

It should be noted that Figures 9 and 10 illustrate only single 'pulse' of air, which is achieved by, firstly, operating the suction generator 11 to establish a negative pressure within the dirt bin 38 (as illustrated by Figure 9), and then shutting off the suction generator 11 and opening the bin door 26 and the air valve arrangement 100 (as depicted in Figure 10) to generate a high speed airflow through the dirt bin 38. However, the operation may be performed more than once in order to provide a more effective and complete bin emptying operation. It should be appreciated that operation of the air valve arrangement 100 may be carried out repeatedly while the bin door 26 is in the open position; the bin door 26 is not required to be closed between actuations of the air valve arrangement 100. Furthermore, although it is envisaged that the vacuum generator 11 should be cycled on when the air valve arrangement 100 is closed, and cycled to off when the air valve arrangement 100 is open, it is believed that this is not essential for acceptable performance of bin emptying. Therefore, acceptable functionality may be achieved by opening and closing the air valve arrangement 100 whilst the vacuum generator 11 is operating. It should also be appreciated therefore that during the self-cleaning mode of operation, the vacuum cleaner may be operated whilst the air valve arrangement 100 is changing states. Airflow through the machine may flow in the reverse direction, but also in the first airflow direction. Li

In the example described above, the suction generator 11 and the air valve arrangement 100 are envisaged to be controlled manually by the user in order to achieve a bin emptying operation. However, the vacuum cleaner could be configured such that a self-cleaning operation is perfonned automatically under the control of a control system. For example, a suitable user-operable button or trigger may be provided on the vacuum cleaner 2 which the user may depress in order to drive a self-cleaning operation. Correspondingly, a control system of the vacuum cleaner 2 may be configured to control electronically the operation of the bin door 26, the air valve arrangement 100 and the suction generator 11 in an appropriate sequence in order to generate the required one or more pulses of high speed air through the dirt bin 38.

In another example, it is envisaged that the valve arrangement 100 may be responsive to the pressure within the dirt bin 38. For example, once a negative pressure has been established in the dirt bin 39 and the bin door 26 has been opened, the valve arrangement 100 may be configured to open when exposed to a pressure differential between the ambient pressure outside of the vacuum cleaner and the negative pressure inside the dirt bin 38. Such a pneumatically-driven system would improve energy efficiency of the system as it would not require any electrical energy to power it.

In the above examples, the air valve arrangement 100 is embodied as a cuff or collar-shaped valve member 104 that encircles the separator body 22 to selectively open and close the apertures 102. However, it should be appreciated that this specific configuration is just an example and the air valve arrangement could be embodied in different ways. In essence, the function of the air valve arrangement 100 is to permit a controllable flow of air to enter into the dirt bin 38 to flush out debris. So any configuration that permits this functionality would be acceptable. For example, it is envisaged that a reverse airflow could be permitted though the cyclonic separator system so as to flow out of the cylindrical shroud 45 (see Figure 2) into the dirt bin 38. The benefit of this is that the reverse airflow would assist in removing caked on dust that may partially block the pores of the shroud 45. It will therefore be appreciated that the flow of air through the dirt bin 38, whether it flows directly into the dirt bin 38 through the apertures 90, or whether it flow into the dirt bin through the cyclonic separator and the shroud 45 (which is a surface filter), can be considered to perform a cleaning action on at least one separating system of the vacuum cleaner 2. The reverse flow of air through the machine can also be configured to flow through one or more fibrous filters of the vacuum cleaner 2, for example through a HEPA filter or depth filter of the vacuum cleaner.

Figure 11 illustrates a further example of a vacuum cleaning system 62 in accordance with the invention comprising a docking station 60, and an alternative configuration of vacuum cleaner 110. In Figure 11, the docking station 60 is substantially as described in the above examples, so only the differences will be described here for brevity.

Turning to the vacuum cleaner 110, it should be appreciated that the vacuum cleaner is a cyclonic or bagless' vacuum cleaner as has been described in the previous examples.

As such, the vacuum cleaner 110 of this example has a main body 112 which includes a suction generator 114, and a handle 116. The handle depends downwardly from the main body 112. A cyclonic separator 118 is removably attached to the main body 112. The cyclonic separator 118 has an inlet duct 120 extending therefore through which dirt and debris is sucked into the vacuum cleaner 110. The cyclonic separator 118 is orientated along an axis Y, around which a circulating airflow is established during operation, as is well understood in the art. Notably, the separator axis Y is transverse to an axis Z defined by the elongated inlet duct 118, and in this example is perpendicular. This is in contrast to the vacuum cleaner 2 described in the above examples in which the axis of the inlet duct was aligned with the axis of the cyclonic separator.

The skilled person would appreciate that the type of vacuum cleaner 110 shown in Figure 11 is the same general configuration as vacuum cleaners available commercially from Dyson Technology Ltd, known as for example the 'DC16', DC30', V6' and 'V8'.

The docking station 60 has an interface 122 that is configured to dock with the vacuum cleaner 110. The interface 122 in this example performs the same function as the interface 74 in the previous examples of the invention, but is configured to adapt the differently configured vacuum cleaner 110 to the docking station 60.

As can be seen, the interface 122 includes a socket 124 that is sized to accept the lower end of the cyclonic separator 118 and to allow a bin door 126 thereof to open into the docking station 60, as shown in the Figure. Since the inlet duct 120 is oriented to be transverse to the axis Y of the cyclonic separator 118, the interface 122 also includes an inlet duct connector 128. The inlet duct connector 128 extends from the top of the interface 122 and couples to the front end of the inlet duct 120 of the vacuum cleaner 110. In this way when the suction generator 114 is operated, air is drawn from the docking station 60 through the interface 122 and inlet duct connector 128, into the cyclonic separator 118 through the inlet duct 120. This enables a bin emptying operation to be performed in the same way as described above.

In the examples described above, an advantage is gained by the suction generator being part of the vacuum cleaner, such that only one electric motor is needed to power the vacuum cleaner but also to drive the bin emptying operation. However, it is envisaged that in other examples a separate suction generator may be positioned in the docking station to drive the bin emptying operation. The separate suction generator would be in addition to a suction generator within the vacuum cleaner itself Therefore, in such an example, the suction generator in the docking station may be operated in the same way as the suction generator in the above described examples whilst the valve arrangement in the vacuum cleaner operates to generate the pulse air flow through the vacuum cleaner to assist in bin emptying.

As has been discussed above, in some examples the air valve arrangement 100 is configured to permit a controllable flow of air to enter into the dirt bin 38 to flush out debris. So any configuration that permits this functionality would be acceptable. For example, it is envisaged that a reverse airflow could be permitted though the cyclonic separator system so as to flow out of the cylindrical shroud 45 (see Figure 2) into the dirt bin 38. The benefit of this is that the reverse airflow would assist in removing caked on dust that may partially block the pores of the shroud 45. It will therefore be appreciated that the flow of air through the dirt bin 38, whether it flows directly into the dirt bin 38 through the apertures 90, or whether it flows into the dirt bin through the cyclonic separator and the shroud 45 (which is a surface filter), can be considered to perform a cleaning action on at least one separating system of the vacuum cleaner 2. The reverse flow of air through the machine can also be configured to flow through one or more fibrous or membrane filters of the vacuum cleaner 2, for example through a ITEPA filter of the vacuum cleaner. Further, it is envisaged that the reverse airflow could be used to flow through a pre-motor filter or a post-motor filter of the vacuum cleaner in order to provide a cleaning mechanism to fully or partially regenerate the filter which would reduce the need for a user to wash such filters regularly.

A further example of this principle will now be described with reference to Figures 12 to 15.

Referring firstly to Figure 12, there is shown in schematic form the handheld vacuum cleaner 2 as has been discussed in the previous illustrated examples and also further detail of the contents of the motor casing 15. As can be appreciated in the inset panel, the vacuum cleaner 2 comprises the vacuum motor 12 and impeller 13 which constitute the vacuum generator 11. A pre-motor filter 19 is positioned in advance of the vacuum motor 12, in the direction of airflow during a 'normal' or surface cleaning mode of operation. The direction of airflow during this mode is shown in Figure 12 by the arrows 'A' as flowing from the cyclonic separating unit 8, which can be considered to be the primary separation system of this example, and from there through the pre-motor filter 19 to the vacuum motor 12. As is known, the function of the pre-motor filter 19 is to filter fine contaminants from the airflow that may not have been removed from air by the cyclonic separating unit 8, or other primary separation system. Therefore, the pre-motor filter 19 provides a degree of protection for the vacuum motor 12 to protect it from fine contaminants and also moisture.

The pre-motor filter is 19 in the form of a membrane filter. The membrane filter is a thin sheet of material, for example of ePTFE (expanded polytetrofluoroethylene). The membrane filter may be carried on a suitable structure such as a frame to define any suitable shape. For example it may be arranged as a flat sheet, or curved into a cylindrical or barrel shape, as is shown schematically in Figure 12 or, moreover, pleated into numerous other forms. It should be noted that ePTFE is suitable as a membrane filter because it is a durable material and yet has porosity that can be selected in a range of values.

Currently an ePTFE membrane filter medium is considered useful as such mediums offer good chemical resistance, low pressure drop and high filtration efficiency, which makes them particularly suitable for the rigours of use within a vacuum cleaner whilst achieving low emissions in line with UEFA standard requirements. This is predominantly achieved through the fibrillation of the continuous PTFE film into a network of very fine nano-fibres which enter into a no-slip flow regime. This allows the elimination of the boundary layer around the fibres, greatly reducing drag, and therefore pressure drop, the fine nature of the fibrils (<50nm particularly, and less than 100nm) and close spacing also allows for high capture efficiency of particles of all sizes and clean cake formation on the surface of the filter. Whilst ePTFE is used as an example here, it is possible to achieve similar results with other polymers such as PU (polyurethane), PP (polypropylene), polyamide or PVDF (polyvinylidene fluoride) to name a few. Additionally, nanofibers generated through a range or manufacturing techniques including but not limited to electrospinning, force spinning and the nanofibrilaton methods known for ePTFE can be used. Usually these filters are used to provide efficiencies in the 99.99% @0.1 or 0.3um range, however membranes exist that can go as low as 75% or even 50% in this particle size. Fibril diameter may be determined by known techniques such as transmission electron microscopy (TEM) which would be understood by those skilled persons in the art.

The pre-motor filter 19 is contained within a filter chamber 150 defined by a filter housing 151. The filter housing 151 may be the motor casing 15 or may be a separate component which, moreover, may be removable from the motor casing 15.

As can be appreciated from Figure 12 the pre-motor filter 19 is configured to have an annular form which divides the filter chamber 150 into a first (outer) chamber portion 152 and second (inner) chamber portion 154. The outer chamber portion 152 and the inner chamber portion 154 are separated by the pre-motor filter 19, which is supported within the chamber 150 by a suitable filter support 156. The precise structure of the filter support 156 is not crucial, but its functionality is to support the pre-motor filter 19 within the motor casing 15 in a secure way so that the pre-motor filter 19 is able to perform its filtration function efficiently. The outer chamber portion 152 receives incoming air from the cyclonic separating unit 8 and that air then passes into the outer filter chamber portion 152 through an inlet 158, and then through the pre-motor filter 19 to the vacuum motor 12.

An air valve arrangement 200 is also provided to control air flow through the filter chamber 150 and, thus, the pre-motor filter 19. As shown, the air valve arrangement 200 includes at least one first valve element 160 that controls air flow through the outer chamber portion 152 and at least one second valve element 162 that control the flow of air through the inner chamber portion 154. The functionality of the first and second valve elements 162 will become apparent in the discussion that follows. At this point it should be noted that the presence of the second valve element 162 is not essential, but is provided as a potential enhancement to the overall functionality of the air valve arrangement 200.

The air valve arrangement 200 in Figure 12 has the same functionality as the air valve arrangement 100 as discussed in the previously illustrated examples. That is, the air valve arrangement 200 is operable when the vacuum cleaner 2 is in a self-cleaning mode of operation to enable a high speed airflow to be passed through the vacuum cleaner 2 in a direction that is reversed with respect to the direction of airflow through the machine in the surface cleaning mode of operation. In particular, the air valve arrangement 200 permits a high speed flow of air to flow through the pre-motor filter 19 in a reversed direction with the result that the pre-motor filter 19 is cleaned thereby restoring the pressure drop by a significant degree, which benefits filtering efficiency.

This means that the pre-motor filter 19 will require washing much less frequently than is typically the case and, potentially, that the need for filter washing will be entirely avoided.

At this point it should be appreciated that the flow of air through the membrane filter in the reverse direction during the self-cleaning mode of operation may be combined with a flow of air in the first airflow direction, which is the direction of airflow in the floor cleaning mode of operation. This may occur due to repeated cycling of the air valve arrangement whilst the vacuum motor continues to operate Figure 13 illustrates a first example of this functionality where the air valve arrangement 200 is operated to cause a reverse flow of air through the pre-motor filter 19. In this Figure, the at least one first valve element 160 is in a closed state, thereby preventing airflow into the outer chamber portion 152 directly, whilst the at least one second valve element 162 is in an open state, thereby allowing a reverse flow of air into the inner chamber portion 154 and through the pre-motor filter 19 into the outer chamber portion 152. From the outer chamber portion 152, air flows through the inlet 158 and to the cyclonic separating unit 8 It should be noted at this point that the open and closed operating states of the at least one first arid second valve elements 160,162 are shown schematically and, as such, the valve elements may be operated by any suitable means. For example, they may be electromagnetically operated or pneumatically operated. Also, they may be operated by differential pressure across the respective valve elements.

As can be seen in Figure 13, the pre-motor filter 19 bears a layer of dirt on its dirty side As the pre-motor filter 19 is a membrane filter, in this example, dirt is captured on its surface to form a layer or 'cake' This surface caking is as opposed to a thicker filter element such as a depth filter in which dirt particles tend to be collected within the interstices of the filter fibres, which is known generally as 'depth loading'.

The reverse flow of air through the pre-motor filter 19 as shown in Figure 13 is effective at removing this surface cake as the airflow blasts the cake from the surface of the pre-motor filter 19 whereupon it can be removed to a suitable location in the vacuum cleaner. For example, the surface cake can be discharged into the dirt bin of the vacuum cleaner and from there moved to the docking station if it is connected.

Figure 14 shows an enhancement to the example shown in Figure 13 in which a reverse airflow was routed through the inner chamber portion 154 and the pre-motor filter 19 by the at least one second valve element 162 being in an open state, whilst the at least one first valve element 160 is in a closed state. In the Figure 14 example, it will be noted that both the at least one first valve element 160 and the at least one second valve element 162 are in an open state. This means that a high speed flow of air is admitted into the inner chamber portion 154 and through the pre-motor filter 19 which therefore has the effect of backflushing the pre-motor filter 19, but that a high speed flow of air is also admitted directly into the outer chamber portion 152.

As can be appreciated from Figure 14, the flow of air entering the outer chamber portion 152 flows in a direction that is substantially parallel to the outer surface of the pre-motor filter 19. The air therefore flows across the surface of the pre-motor filter 19 which has the effect of scrubbing the built-up cake from the pre-motor filter 19 Therefore, the flow of air through the pre-motor filter 19 from the at least one second valve element 162 and the flow of air across the pre-motor filter 19 from the at least one first valve element 160 act together to enhance the cleaning effect of the reverse airflow during the self-cleaning mode of operation.

Note that the airflow is shown going in a downward direction through the outer chamber portion 152 in the orientation of the Figures Although there may be some turbulence within the airflow, it should be understood that the high speed airflow through the outer chamber portion 152 will substantially flow in the direction shown from the least one first valve element 160 of the outer chamber portion 154 to the inlet 158 which are axially aligned in the illustrated example.

S

A further enhancement is shown in the example of Figure 15. The structure shown in Figure 15 is similar to the example described above with reference to Figures 12 to 14, so only the differences will be described for brevity.

In the example of Figure 15, the pre-motor filter 19 is movably mounted within the filter housing 151, which movement assists with dislodging the dirt from the pre-motor filter 19. As shown, the pre-motor filter 19 is resiliently mounted to the filter support 156, which functionality is depicted here by one or more compression springs 170, although other resilient mounting means may be suitable.

The pre-motor filter 19 is shown in Figure 15 in a second (lower) position in which it has been moved away from the filter support 156 Although not shown, it should be noted that the pre-motor filter 19 would be movable into the second position from a first position in which the pre-motor filter 19 is in a relatively higher position compared to the second position so that the end of the pre-motor filter 19 abuts the filter support 156.

It should be noted at this point that the resilient mounting of the pre-motor filter 19 provided by the filter support 156 may be provided by an annularly shaped spring integrated into an air-impervious membrane to ensure that air does not bypass the pre-motor filter 19 A suitable trigger mechanism may be provided to enable the pre-motor filter 19 to move from the first position into the second position. The trigger mechanism may be served by the commencement of the high speed airflow rushing through the motor casing 15, through the air valve arrangement 200 and through the pre-motor filter 19.

Additionally, or alternatively, a further trigger mechanism may be provided to unlock the pre-motor filter 19 from the first position.

Although it will be apparent that the air valve arrangement 200 shown in Figure 15 is configured such that the at least one first valve element 160 is in a closed state and the at least one second valve element 12 is in an open state, it should be appreciated that both valve elements 160,162 may be in the open state, therefore enabling a backflushing' airflow through the pre-motor filter 19 and a 'scrubbing' airflow across the surface of the pre-motor filter, as described above with reference to Figure 14 From the above discussion, it will be appreciated that abrupt movement of the pre-motor filter 19 when a reverse flow of high speed air is caused to flow through it may help dislodge the caked dirt that has accumulated on its surface. To enhance this effect, a means of delivering an impact force to the pre-motor filter 19 as it moves from the first position to the second position may be provided.

Such an effect may be achieved by a suitable impactor 172, which is shown in Figure 15 in the form of a bump stop 174 that is positioned axially below the pre-motor filter 19. The bump stop 174 is shown schematically, and so it should be appreciated that it may take any suitable structural form to delivery the required functionality. For example, the bump stop 174 may be a fixed structure projecting from the filter housing 151 sized and positioned such that the pre-motor filter 19 hits the bump stop 174 after a predetermined distance of travel after the pre-motor filter 19 has begun its movement from the first position towards the second position, thereby resulting in a sharp deceleration of the pre-motor filter 19 to encourage any cake layer to dislodged from the filter surface.

In other examples, it is envisaged that the impactor 172 may be configured so that a mechanical impulse force may be delivered to the pre-motor filter 19 without it moving from its first position. For example the filter housing 151 could be equipped with a motorised flicker or comparable mechanism to impact the pre-motor filter 19.

Various modifications of the illustrated examples have already been described. The skilled person further would understand that other modifications may be made to the illustrated examples without departing from the invention as defined by the claims.

For example, in the examples described above in relation to Figures 12 to 15, the vacuum cleaner 2 includes a pre-motor filter 19 in the form of a membrane filter to filter out remaining contaminants in the airflow from the primary separation system 8. However, in other examples, it is envisaged that such a membrane filter may also be positioned as a post-motor filter. By 'post-motor' it is meant a filter that would be located downstream of the airflow motor 12 in the direction of airflow when the vacuum cleaner 2 is in a surface cleaning mode of operation. Still further, it is envisaged that one or more membrane filters could be located downstream and upstream of the airflow motor 12. As such, such a system would be considered as having both at least one pre-motor filter and at least one post-motor filter.

It should also be noted that although in the examples of Figures 12 to 15 the vacuum cleaner 2 is envisaged for use with the docking station 60 as described in the preceding examples, it is also envisaged that the vacuum cleaner 2 in Figures 12 to 15 may be used in the self-cleaning mode without the use of the docking station 60 Furthermore, although in the above examples the primary separation system has been described as comprising a cyclonic separating unit 8, it should be noted that the primary separation system may comprise a different separation means such as a bagged system or a non-cyclonic separator. Still further, as an option there may be only a single separation system rather than a primary and a secondary separation system as in the illustrated examples. For example the separation system may include a dirt collecting chamber having a filter, which may be a membrane filter, disposed therein for separating dirt and debris from the airflow through the machine.

Claims

CLAIMS1. A vacuum cleaning system comprising a vacuum cleaner having a vacuum motor, a dirt bin, a primary separation system, a membrane filter, and an air valve arrangement configured to control air flow through at least the membrane filter; wherein the vacuum cleaner is configured to be operable in a surface cleaning mode of operation and a self-cleaning mode of operation; wherein, in the surface cleaning mode of operation, the vacuum cleaner is configured such that the vacuum motor draws dirty air from a dirty-air inlet through the dirt bin, the primary separation system and the membrane filter in a first airflow direction, and wherein, in the self-cleaning mode of operation, the vacuum cleaner is configured to permit air to flow from the air valve arrangement through the membrane filter in a second airflow direction to clean dirt from the membrane filter.
2. The vacuum cleaning system of Claim 2, wherein the air valve arrangement is further configured to cause air to flow across a surface of the membrane filter during the self-cleaning mode.
3. The vacuum cleaning system of any of the preceding claims, wherein the membrane filter is selected from: an ePTFE membrane, PP membrane, PU membrane, 25 Polyamide membrane, and a PVDF membrane.
4. The vacuum cleaning system of Claim 3, wherein the filter element has a filter efficiency of at least 50% at a particle size of 0.3 micrometres.
5 The vacuum cleaning system of Claim 3 or Claim 4, wherein the filter element has an average fibril diameter of less than 100nm.
6. The vacuum cleaning system of any of Claims 1 to 5, wherein the membrane filter is movably mounted within the vacuum cleaner, wherein said movement assists in dislodging dirt from the membrane filter.S
7. The vacuum cleaning system of Claim 6, wherein the membrane filter is movable from a first position to a second position when the vacuum cleaner enters the self-cleaning mode of operation to assist in dislodging dirt from the membrane filter.
8. The vacuum cleaning system of Claim 7, wherein in moving from the first position to the second position the membrane filter contacts an impactor configured to provide a mechanical impact pulse to the membrane filter.
9. The vacuum cleaning system of any of Claims 6 to 8, wherein movement of the membrane filter from the first position to the second position is caused by operation of the air valve arrangement.
10. The vacuum cleaning system of any of Claims 6 to 8, wherein movement of the membrane filter from the first position to the second position is caused by opening of the dirt bin door.
11. The vacuum cleaning system of any of the preceding claims, wherein the membrane filter is at least a pre-motor filter, such that it is positioned upstream of the vacuum motor when considered in the direction of airflow in the surface cleaning mode of operation
12. The vacuum cleaning system of any of the preceding claims, wherein the membrane filter is at least a post-motor filter, such that it is positioned downstream of the vacuum motor when considered in the second airflow direction in the surface cleaning mode of operation.
13 The vacuum cleaning system of any one of the preceding claims, further comprising a docking station, wherein the docking station comprises a dirt storage chamber and an interface configured to mate with a dirt bin of the vacuum cleaner such that dirt expelled from the dirt bin through a bin opening is ejected into the dirt storage chamber of the docking station, wherein the vacuum cleaner is configured to evacuate air from the dirt storage chamber when docked with the docking station, wherein, in the self-cleaning mode, the vacuum cleaning system is configured to: operate the vacuum motor to generate a partial vacuum in the dirt storage chamber, and once a negative pressure level has been generated, operate the air valve arrangement to cause a pulse of air to flow from the air valve arrangement through the membrane filter in the second airflow direction.
14. The vacuum cleaning system of Claim 13, wherein one a negative pressure level has been generated, the air valve arrangement is operated to cause a pulse of air to flow into the dirt bin of the vacuum cleaner thereby to eject dirt from the dirt bin through the bin opening and into the dirt storage chamber.
15. The vacuum cleaning system of Claim 13 or 14, wherein the vacuum cleaner is configured such that the pulse of air admitted into the dirt bin during the self-cleaning mode flows firstly through the membrane filter.
16. The vacuum cleaning system of Claim 15, wherein the primary separation system includes at least one of a surface filter, a depth filter and a cyclonic separator.
17 The system of any one of the preceding claims, wherein the air valve arrangement has a total area that is configured to be not less than 0.5 times the cross sectional area of the dirt bin.
18. The system of any one of the preceding claims, wherein the air valve arrangement is configured to be operated by differential pressure between the dirt bin and ambient environment.
19. The system of any one of the preceding claims, wherein the air valve arrangement is configured to be operated repeatedly during sustained operation of the suction generator, thereby permitting a plurality of sequential air pulses to flow through the dirt bin.