Patent Description:
In conventional vacuum cleaner use, the filter bag can be difficult to orientate and fit into the vacuum cleaner. The bags must locate on at least one feature, which usually requires two hands to position. Removal of the filter bag is usually by hand, requiring the user to touch the bag during removal. Alternative vacuum cleaners operate using a bagless system, wherein the dust is contained within the vacuum cleaner without the use of a separate bag. In these types of vacuum cleaner, hair and long fibres can become entangled within the machine and require removal by hand or tool. Bagless vacuum cleaners often produce a dust "cloud" when being emptied.

<CIT> focuses on providing a space between the filter and internal vacuum chamber to increase air flow and also discloses a filter which may be collapsed but which is not self-erecting. <CIT> discloses a cartridge filter with closing features over the opening, which closing features are displaced in response to incoming airflow.

There are a number of problems that arise during use of conventional filter bags, as described above. The present invention seeks to provide a filter cartridge for use in vacuum cleaners, which can be easily inserted into the vacuum cleaner and removed from the vacuum cleaner with minimal input from the user. The invention also seeks to provide a filter cartridge which minimize the escape of dust during unloading from the vacuum cleaning machine.

Some or all of these aims (and others that will be evident to the skilled person) are met by the present invention in its various aspects, as will be evident from the following description.

According to one aspect of the invention there is provided a filter cartridge comprising:.

The filter cartridge has an opening provided through the first end wall for receiving air-entrained detritus into the interior, the opening being defined by the rigid support structure which spans and supports the first end wall of the cartridge. By rigid we mean that it provides enough rigidity to support the filter cartridge shape without collapsing under its own weight or due to an applied vacuum suction.

The rigid support structure of the first end wall of the filter cartridge comprises a central inner collar which defines the filter opening. There may also be an annular outer rim which defines a perimeter of the first end wall. The collar and rim portions of the rigid structure of the first end wall of the filter cartridge may be structurally attached/integrated as a unitary member. For example, the rigid support structure may be provided by a spider member with multiple spokes or arms which provide a connecting means between the collar and the rim portions of the rigid support structure.

Alternatively the rigid support structure may comprise a generally annular member formed with a central bore defined by a collar. The member may have an inner dished (e.g. frustoconical) portion which is convex away from the cartridge interior. The member may have an outer dished portion (e. eg frustoconical) which is concave so that the inner dished portion is inset back into the cartridge. The collar may be coterminous with a rim of the body portion of the filter.

A non-return valve is provided in the filter opening. By non-return valve we mean that the valve allows fluid (gas) to be drawn through the filter opening into the filter cartridge, but which prevents (or limits) flow of matter (gas or collected detritus) back out through the opening.

The non-return valve is provided with resilient constraint means which is adapted to adopt an open configuration in response to a threshold reduced pressure in the filter cartridge interior, and which closes, or substantially closes, when the pressure reverts to ambient.

The non-return valve comprises a flap of material which can deflect between a closed position in which the flap blocks the filter opening and an open position in which the flap is deflected away from the open position and into the filter interior. Preferably there is a single flap of material.

The flap may be made of sheet plastics material, such as polypropylene, PVC, polyester or another similar resilient polymer material. The flap is preferably oriented so that in the closed position the flap is generally transverse with respect to the longitudinal axis of the filter cartridge, which axis extends between the end caps thereof.

In deflecting between closed and open positions, the flap may have an edge region which is fixed and a body portion which articulates or pivots with respect to the edge region. The pivot may be provided by an elongate seam or weakness (e.g. locally thinned neck region). Alternatively, or in addition, the body portion of the flap may be sufficiently flexible to bend along its length in response to inward airflow into the cartridge.

The edge region may be fixed to a portion of a collar which defines the filter opening. Thus, the flap may cantilever from the said collar portion to obturate the opening when undeflected. The flap typically comprises a planar web of flexible plastics material.

Deflection-limiting stop or stops may be provided to limit the inward deflection of the flap or flaps.

A shroud is provided around the filter opening, projecting inwardly into the filter interior from the collar which defines the opening. The shroud may have a generally horseshoe shape.

The flap stop or stops may comprise one or more radially projecting nubs directed inwardly from the shroud inner surface. There may be two said nubs arranged to be diametrically opposed to one another.

The filter cartridge may be provided with an annular flange around the outer circumference of the support structure. The rigid support structure is preferably generally annular in form.

The support structure may be provided with a circumferential outer annular flange which renders the filter cartridge capable of being clamped between a rim and a lid of a vacuum chamber in which the filter cartridge may be located. The material for the cone facets or flap member material may comprise a transparent material. This allows a visual inspection to indicate whether the filter is full, even when the valve is closed.

The rigid support structure of the filter cartridge may be provided with one or more seals operative between the filter cartridge opening and an inlet port of a vacuum chamber in which the cartridge is accommodated when in use. An inner seal may be provided at the inner collar region of the filter cartridge opening of the rigid support structure.

The rigid support structure of the filter cartridge may be generally disc shaped and provided with a circumferential outer seal operative between the first end of the cartridge an internal wall of a cylindrical vacuum chamber in which the filter cartridge is accommodated when in use. The circumferential outer seal may be provided on an end face of the annular rim of the rigid support structure.

The filter membrane material may be a single layer, or multilayer of filter material. This material is typically flexible, by which we mean flexible enough to be collapsed flat when handled.

The filter cartridge may be collapsible, which is to say the body of the cartridge which defines the interior volume may be collapsed flat onto the rigid support structure.

The filter membrane material or web may be generally planar, and does not rely upon repeated pleats or folds to prevent buckling or increase surface area.

The filter membrane material of the filter cartridge may provide the side wall or walls of the cartridge. The filter membrane material of the filter cartridge may provide the second end wall of the cartridge.

In another aspect of the invention, structural reinforcement may be provided on one or more of the sidewall or walls, and/or second end wall of the filter cartridge, so that the filter cartridge enclosure is self-supporting but collapsible, so that the cartridge may adopt an erect use configuration and in a collapsed configuration the side wall or walls and second end of the filter cartridge are drawn together onto the rigid support structure of the first end so as to be flat-packed.

The structural reinforcement of the filter cartridge may act to bias the cartridge into the erect configuration, so that a collapsed cartridge will spontaneously adopt the erect configuration when a collapsing constraint is released.

The filter cartridge may have a generally cylindrical configuration. The first and second end walls may have a generally disc-shaped configuration. A cylindrical side wall may extend between the first and second ends of the filter cartridge.

The structural reinforcement of the filter cartridge may comprise one or more elongate seams joining filter membrane material portions. The seam may comprise overlapped, or pinched together, or butted together portions of filter membrane material. The portions of material may be joined by welding, such as ultrasonic welding, or fusion welding, or by adhesive such as hot melt adhesive.

The structural reinforcement of the filter bag may comprise one or more resiliently flexible elongate struts, such as wire or plastic spines, which struts when elastically deformed during collapse may provide the erection bias.

One or more of the seams of the filter cartridge may extend in the sidewall in an axial direction between the end walls. Alternatively, or in addition, the seams may extend helically around and along the sidewall between end walls.

One or more strut(s) may be integrated into one or more seam of the filter bag. Alternatively, one or more strut(s) may be attached to the sidewall filter membrane material of the filter cartridge.

Following is a description by way of example only and with reference to the accompanying drawings of various modes for putting the present invention into effect.

In <FIG>, a filter cartridge is shown generally as <NUM>. The filter cartridge comprises a first end portion <NUM>, a second end portion <NUM> and a body portion <NUM>. The first end portion <NUM> comprises a spider <NUM> member <NUM>, having eight cut out segments <NUM>, a central opening <NUM> and a non-return valve <NUM> best seen in <FIG>. The spider member <NUM> of the first end portion <NUM> has an outer annular seal <NUM> having a C-section. The seal extends circumferentially about the central axis A1 of the disc shaped main body. The seal <NUM> is mounted onto an outer circumferential edge region <NUM> of the spider member <NUM> as shown in <FIG>. The seal <NUM> thereby provides an annular upper lip 31and a corresponding lower annular lip <NUM> which protrudes from the underside of the spider member <NUM> as shown in <FIG>.

A further annular seal <NUM> is provided around the opening <NUM> in the spider member (as shown in <FIG>). The seal bead defines a rectangular sectioned lip <NUM> about the central axis A1 of the spider member <NUM>. The protruding lips <NUM>, <NUM> of the outer seal <NUM> and inner seal <NUM> provide a fluid seal when the filter is accommodated in the vacuum chamber of a vacuum cleaner (as shown in <FIG> for example) so that the suction air flow containing dust and small particles is directed into the filter cartridge <NUM> through the central opening <NUM> of the spider member <NUM>.

The central opening <NUM> of the spider member <NUM> provides an entry point for the dust and small particles drawn into the filter cartridge <NUM> by the vacuum cleaner during use. The opening <NUM> is defined by an annular collar <NUM>. The collar extends from a bottom face <NUM> of the spider member <NUM> downwards into the main body <NUM> of the filter cartridge <NUM>. Said collar assists in channelling the air flow into the filter cartridge <NUM> and provides a connecting face <NUM> for attachment of the non-return valve <NUM> to attach, as will be explained below.

The connecting face <NUM> is the outer cylindrical face of the annular collar <NUM>. The non-return valve <NUM> is a unitary moulded plastics member having a generally conical form and an annular collar <NUM>. The collar <NUM> comprises an inner face <NUM> which is fixed (for example by adhesive) to the outer face <NUM> of the annular collar <NUM>.

The conical portion <NUM> depends from the annular collar <NUM> of the non-return valve <NUM>. The conical portion is divided into a plurality of triangular segments <NUM> by radial slits <NUM> cut into the conical portion from the apex <NUM> of the conical portion to the collar.

The non-return valve <NUM> is made from a polymer material which is flexibly resilient. Thus, the triangular segments <NUM> may each splay outwardly to an open configuration to form an orifice, in response to reduced pressure cause by a suction drive of the vacuum cleaner in which the filter cartridge is placed. Thus air-entrained detritus may be drawn into the filter interior through the non-return valve. Once the suction is stopped, the segments flex back to the conical closed configuration. In this configuration the valve is closed so that escape of collected detritus is prevent or at least limited.

The underside <NUM> of spider member <NUM> has adhered thereto an annular web of filter material <NUM>. Said filter material has a central hole of diameter D (<FIG>). The outer diameter D5 of the filter material <NUM> is greater than the outside diameter D6 of the cut-out segments D7 in the spider member <NUM>. The aforementioned sizing allows the filter material <NUM> cover the segments gaps <NUM>.

The body portion <NUM> of the filter cartridge is a web of flexible porous material. The body has a flared upper annular shoulder <NUM> which is fixed to the outer underside region of the annular web <NUM>, typically by use of adhesive or welding.

<FIG> shows a section side section view A-A of the filter cartridge <NUM>. As mentioned above, the main body <NUM> of the filter cartridge <NUM> is made from a filter material. The filter material is structured to allow air to pass through, but to prevent the passing of dust and small particles collected during vacuum cleaning.

The lower end portion <NUM> comprises a disc shaped base section <NUM> which closes the cylindrical body portion <NUM> of the filter cartridge <NUM>. The base section of the body portion <NUM> has an annular flared shoulder region <NUM> which is fixed to a rim <NUM> of the base section <NUM> by way of a seam <NUM>, shown in <FIG>. In this way the filter material forms a complete enclosure for the collection of detritus which enters through the one-way conical valve.

In its first configuration, shown in <FIG>, the filter cartridge <NUM>, is self-supported against buckling by the cylindrical shape and structure of the filter cartridge main body <NUM>. The filter material <NUM> of the main body <NUM> may comprise a number of seams which join the filter material together, as will be described in more detail below. The filter may be collapsed by pushing down on the upper end <NUM> (per <FIG>) or by twisting the upper end relative to the lower end <NUM> as per <FIG>.

<FIG> show some of the options available for assembling the filter by joining the filter material. These comprise ultrasonic welding of abutting faces (<FIG>), ultrasonic welding of overlapping faces (<FIG>), adhesion of abutting edges using a bead of hot melt adhesive (<FIG>) and incorporation of elongate resilient reinforcement members in joined seams (<FIG>). The reinforcement members may comprise rods or ribbon struts, typically formed of metal or relatively rigid, but resiliently flexible, plastics material. These provide structural support for the cartridge, but also permit collapse of the cartridges under an applied axial or twisting pressure.

The seams may themselves provide structural support. <FIG> shows a single elongate longitudinally oriented seam, <FIG> has two diametrically opposed elongate longitudinally extending seams, <FIG> has three such seams, <FIG> has a single helically extending seam, and <FIG> has two parallel helically extending seams. Where seams overlap, or are welded/adhered or form local abutments, the stiffness of the structure is enhanced, while still permitting collapse of the filter for storage, or when on sale in packets.

<FIG> are side perspective view showing various structures and methods for collapsing the filter cartridge, in which the configuration of the expanded cartridges are shown in dashed lines. In <FIG> collapse is by axial pushing and twisting, in <FIG> the cartridge is folded until both end pieces are side-by-side, in <FIG> the cartridge upper end in simply pushed down in an axial direction (without twist), in <FIG> the lower portion of the cartridge is rolled-up, in <FIG> a single seam extends for just over two complete turns and may be collapsed simply by axial compression in the direction A1.

<FIG> shows a method for collapsing the filter cartridge wherein the first end portion <NUM> is pushed towards the second end portion <NUM> along the central axis A1 of the filter cartridge <NUM>. In said filter cartridge, a double-coiled helical spring feature <NUM> is present in the filter cartridge main body <NUM> which travels from the first end <NUM> to the second end base section <NUM> within the structure of the filter material. Upon collapsing of the filter cartridge <NUM>, the helical spring <NUM> is compressed as the first end portion <NUM> moves towards the second end portion <NUM> along the central axis A1 of the filter cartridge <NUM>. In storage and packaging, the filter cartridge will be held in its second configuration, once the filter cartridge <NUM> is released from its second configuration, it will return naturally to its first, uncompressed configuration when the helical spring <NUM> decompresses.

<FIG> show a filter cartridge <NUM> in accordance with the present invention, which is collapsed when the first end portion <NUM> is pushed towards the second end portion <NUM> along the central axis A1 of the filter cartridge <NUM>, whilst the first end portion <NUM> is rotated about the central axis A1 of the filter cartridge <NUM>. Said filter cartridge is supported by one or more straight struts <NUM> which travel the length of the filter cartridge body portion <NUM> from the first end <NUM> to the second end base <NUM>. The vertical struts <NUM> are fixed to the filter cartridge main body <NUM>.

The normal arrangement of the vertical struts <NUM> is straight, as shown in <FIG>, however, when the aforementioned pushing and twisting motion is applied to the filter cartridge <NUM>, the struts <NUM> deform in a corresponding manner to the filter cartridge main body <NUM>, as shown in <FIG>, until the filter cartridge reaches its second configuration. Once the filter cartridge <NUM> is released from its second configuration, it will return naturally to its first, uncompressed configuration when the struts <NUM> return to their natural arrangements.

<FIG>, <FIG> show schematically a filter cartridge <NUM> in accordance with the present invention in its first (expanded) configuration being inserted into a hand held vacuum cleaner <NUM> such that the filter cartridge sits horizontally in the vacuum cleaner. The filter cartridge is placed into the vacuum cleaner (arrow F in <FIG>) such that the second end portion <NUM> of the filter cartridge <NUM> sits next to a suction air inlet <NUM> for a vacuum drive (not shown) of the cleaner. The vacuum cleaner comprises an open-ended chamber <NUM>, which slides (arrow C in <FIG>) over the filter cartridge <NUM> to the until an interior face of the end cap <NUM> abuts against the inner seal <NUM> and outer seal <NUM> of the first end portion <NUM> of the filter cartridge <NUM>. The filter cartridge may be removed without touching the cartridge by axially shifting the chamber housing (as shown by the arrow R in <FIG>), and then inverting the vacuum cleaner so that the cartridge falls away. This is useful when the collected dust may contaminated or hazardous.

When the vacuum cleaner is used, air is sucked into the filter cartridge <NUM> through the nozzle <NUM>, which feeds into the central opening <NUM> of the filter cartridge by the suction motor behind the suction inlet <NUM>. Air is drawn through the filter material of the body <NUM> and the second end portion <NUM>. The filter body portion has a length which is less than the interior length of the vacuum chamber <NUM>, and a diameter that is less than that of the chamber <NUM>. This ensures a separation between the suction inlet orifice <NUM> and the filter end portion <NUM> and ensures that a lower pressure plenum is formed around the cartridge, in the annular space between filter body and chamber housing, when the suction motor is active.

<FIG> show schematically an alternative arrangement of a handheld vacuum cleaner <NUM> in which the filter cartridge <NUM> in accordance with the present invention sits in a vertical orientation in a vacuum chamber <NUM>. The chamber is fed by an elbow inlet pipe <NUM> in a lid <NUM> of the chamber. This inlet pipe is <NUM> fed by the nozzle tube <NUM>. The lid may be opened (arrow in <FIG>) to permit removal of the filter cartridge by manual vertical extraction, or by inverting the vacuum cleaner so that the cartridge drops out hands free.

A filter cartridge in accordance with the invention is shown generally as <NUM> in <FIG>. The cartridge has a cylindrical body portion <NUM> formed of a filter membrane material suitable for vacuum cleaner use. The body portion has an elongate welded seam <NUM> extending in an axial direction. A distal end <NUM> of the cartridge (best seen in <FIG>) comprises a flat disc of the filter membrane material, with a welded annular seam <NUM> formed by overlapping portions of the body portion distal edge and the outer region of the flat disc. A proximal end <NUM> of the filter cartridge is formed with as a unitary, generally annular support member <NUM> which is a moulding of plastics material. The support includes an inner frusto-conical portion <NUM> which tapers inwardly from an outer base region <NUM> to a central collar <NUM> around an inlet orifice <NUM>. A rim <NUM> is provided around the collar, which serves as a sealing bead when the cartridge is placed inside a vacuum cleaner. From the outer base region <NUM> the support includes a portion <NUM> which flares outwardly to an annular outer flange feature <NUM>.

In <FIG> the filter cartridge is shown before loading into a handheld vacuum cleaner <NUM>. The vacuum cleaner has a vacuum chamber <NUM> of generally cylindrical shape defined by a generally cylindrical housing <NUM>. The chamber has a proximal end provided with a collar <NUM>. A lower region of the collar is provided with a hinge <NUM> by which a lid member <NUM> is attached to the housing <NUM>. The lid member has a circular, dished configuration and a central inlet orifice <NUM>. An outer region of the lid member is provided with an inset semi-circular clamping member <NUM>. When the filter cartridge is inserted into the chamber <NUM>, the annular flange feature <NUM> abuts the collar <NUM>, with the support <NUM> nested in the chamber, set back from the flange feature. The lid member is then closed by pivoting around the hinge <NUM>. The outer edge of the lid member is held tightly against the flange feature <NUM> as the clamping member <NUM> is fastened to a retaining latch (not shown) on the upper edge of the collar <NUM>. This holds the cartridge in position and ensure an air-tight seal is maintained between the support <NUM>, collar <NUM> and lid member <NUM>. The central inlet orifice <NUM> of the lid member will receive one end of an elongate tubular nozzle (not shown), which (during use) will transport air-entrained detritus into the interior of the cartridge via the collar <NUM>, induced by a suction drive <NUM> provided at a distal end of the vacuum cleaner.

In <FIG> the distal side of the support member <NUM> is shown. A sectioned support member is shown in <FIG>. In <FIG> a shroud member <NUM> having a generally horse-shoe shape is shown surrounding the central collar <NUM> of the support. A chord feature <NUM> of the collar <NUM> is best seen in <FIG>. The chord feature provided a flat edge region to the collar inner edge. Three spaced apart studs <NUM> are provided along the chord feature. A transparent planar flap member <NUM> has the shape shown in <FIG> which corresponds to the inner shape of the collar <NUM>. Three spaced apart bores <NUM> are provided along one edge region of the flap member. Projecting out from the said one edge region is a tongue feature <NUM>. The flap member is placed over the three studs <NUM> with the bores receiving the studs. The studs are then heat pressed to fix the flap member in place. The tongue feature sits in a complementary shaped inset wedge <NUM>. The flap member acts as a cantilever closure which, at rest, obturates the inlet orifice <NUM>. When a vacuum suction is applied to the vacuum chamber <NUM>, the airflow into the filter cartridge through the orifice <NUM> causes the flap member to bend inwards, as shown in <FIG>. Two radially directed nubs <NUM>, <NUM> ore provided diametrically opposed to one another on the inside of the shroud <NUM>. These nubs serve as stops to the inward deflection of the flap member. Once the suction is removed, the flap member returns to the rest position. The shroud serves to help prevent egress of detritus in the filter cartridge interior via the inlet orifice by blocking radial travel of particles towards the collar, especially when the cartridge interior is almost full.

The test results shown if the graph <FIG> demonstrate that the filter cartridge of the second embodiment which uses a flap member (labelled PVC flap) is capable of being filled with a greater loading of dust (about <NUM>) than the filter cartridge of the first embodiment (<NUM>) which has a conical valve. Both of these embodiments of the invention achieve higher dust loads than a comparable handheld cyclonic vacuum cleaner with a correspondingly-dimensioned vacuum chamber, but without a filter cartridge or collection bag in the chamber. The filter cartridge with a flap member valve permits greater flow rates and a higher dust loading than the cartridge with the conical valve. However both of these perform better than the cyclonic cleaner, which has a performance which falls off steeply after a dust loading of <NUM>.

Claim 1:
A filter cartridge (<NUM>) for a vacuum cleaner comprising:
first and second opposite end walls, a side wall or walls which extend between the end walls so as to define an enclosure which surrounds a filter interior, wherein one or more of the walls comprises filter membrane material,
the cartridge (<NUM>) having an opening (<NUM>) provided through the first end wall (<NUM>) for receiving air-entrained detritus into the interior, the opening (<NUM>) being defined by a rigid support structure (<NUM>) which spans and supports the first end wall of the cartridge (<NUM>), and wherein the rigid support structure (<NUM>) of the first end wall (<NUM>) comprises a central inner collar (<NUM>) which defines the filter cartridge opening (<NUM>),
wherein a non-return valve is provided in the filter opening, which non-return valve is provided with resilient constraint means which is adapted to adopt an open configuration in response to a threshold reduced pressure in the cartridge interior, and which closes, or substantially closes, when the pressure reverts to ambient,
and characterised in that the non-return valve comprises a flap (<NUM>) of material which can deflect between a closed position in which the flap (<NUM>) blocks the filter opening (<NUM>) and an open position in which the flap (<NUM>) is deflected away from the open position and into the filter interior, and
wherein a shroud (<NUM>) is provided around the filter opening (<NUM>), projecting inwardly into the filter interior from the collar (<NUM>) which defines the opening (<NUM>).