Patent ID: 12193628

FIRST EMBODIMENT

InFIG.1a, a filter cartridge in accordance with the present invention is shown generally as20. The filter cartridge comprises a first end portion21, a second end portion22and a body portion23. The first end portion21comprises a spider member25, having eight cut out segments26, a central opening27and a non-return valve28best seen inFIG.2b. The spider member25of the first end portion21has an outer annular seal29having a C-section. The seal extends circumferentially about the central axis A1of the disc shaped main body25. The seal29is mounted onto an outer circumferential edge region32of the spider member25as shown inFIG.2c. The seal29thereby provides an annular upper lip31and a corresponding lower annular lip33which protrudes from the underside of the spider member as shown inFIG.2c.

A further annular seal34is provided around the opening27in the spider member (as shown inFIG.1a). The seal bead defines a rectangular sectioned lip35about the central axis A1of the spider member25. The protruding lips31,35of the outer seal29and inner seal34provide a fluid seal when the filter is accommodated in the vacuum chamber of a vacuum cleaner (as shown inFIG.9fore example) so that the suction air flow containing dust and small particles is directed into the filter cartridge20through the central opening27of the spider member25.

The central opening27of the spider member25provides an entry point for the dust and small particles drawn into the filter cartridge20by the vacuum cleaner during use. The opening27is defined by an annular collar36. The collar extends from a bottom face37of the spider member25downwards into the main body23of the filter cartridge20. Said collar assists in channeling the air flow into the filter cartridge20and provides a connecting face38for attachment of the non-return valve28to attach, as will be explained below. The connecting face38is the outer cylindrical face of the annular collar36.

The non-return valve28is a unitary moulded plastics member having a generally conical form and an annular collar39. The collar39comprises an inner face40which is fixed (for example by adhesive) to the outer face38of the annular collar36. The conical portion41depends from the annular collar39of the non-return valve28. The conical portion is divided into a plurality of triangular segments42by radial slits43cut into the conical portion from the apex44of the conical portion to the collar.

The non-return valve28is made from a polymer material which is flexibly resilient. Thus the triangular segments42may 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 underside37of spider member25has adhered thereto an annular web of filter material45. Said filter material has a central hole of diameter D (FIG.2c). The outer diameter D5of the filter material45is greater than the outside diameter D6of the cut-out segments D7in the spider member25. The aforementioned sizing allows the filter material45cover the segments gaps26.

The body portion23of the filter cartridge is a web of flexible porous material. The body has a flared upper annular shoulder47which is fixed to the outer underside region of the annular web45, typically by use of adhesive or welding.

FIG.2bshows a section side section view A-A of the filter cartridge20. As mentioned above, the main body23of the filter cartridge20is 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 portion22comprises a disc shaped base section48which closes the cylindrical body portion23of the filter cartridge20. The base section The body portion23has an annular flared shoulder region51which is fixed to a rim49of the base section48by way of a seam50, shown inFIG.2b. 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 inFIG.3a, the filter cartridge20is self-supported against buckling by the cylindrical shape and structure of the filter cartridge main body23. The filter material52of the main body23may 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 end21(perFIG.3b) or by twisting the upper end relative to the lower end22as perFIG.3c.

FIGS.5ato5dshow some of the options available for assembling the filter by joining the filter material. These comprise ultrasonic welding of abutting faces (FIG.5a), ultrasonic welding of overlapping faces (FIG.5b), adhesion of abutting edges using a bead of hot melt adhesive (FIG.5c) and incorporation of elongate resilient reinforcement members in joined seams (FIG.5d). 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.6ashows a single elongate longitudinally oriented seam,FIG.6bhas two diametrically opposed elongate longitudinally extending seams,FIG.6chas three such seams,FIG.6dhas a single helically extending seam, andFIG.6ehas 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.

FIGS.7ato7eare 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. InFIG.7acollapse is by axial pushing and twisting, inFIG.7bthe cartridge is folded until both end pieces are side-by-side, inFIG.7cthe cartridge upper end in simply pushed down in an axial direction (without twist), inFIG.7dthe lower portion of the cartridge is rolled-up, inFIG.7ea single seam extends for just over two complete turns and may be collapsed simply by axial compression in the direction A1.

FIG.7eshows a method for collapsing the filter cartridge wherein the first end portion21is pushed towards the second end portion22along the central axis A1of the filter cartridge20. In said filter cartridge, a double-coiled helical spring feature54is present in the filter cartridge main body23which travels from the first end24to the second end base section48within the structure of the filter material. Upon collapsing of the filter cartridge20, the helical spring54is compressed as the first end portion21moves towards the second end portion22along the central axis A1of the filter cartridge20. In storage and packaging, the filter cartridge will be held in its second configuration, once the filter cartridge20is released from its second configuration, it will return naturally to its first, uncompressed configuration when the helical spring54decompresses.

FIGS.8aand8bshow a filter cartridge20in accordance with the present invention, which is collapsed when the first end portion21is pushed towards the second end portion22along the central axis A1of the filter cartridge20, whilst the first end portion21is rotated about the central axis A1of the filter cartridge20. Said filter cartridge is supported by one or more straight struts55which travel the length of the filter cartridge body portion23from the first end24to the second end base48. The vertical struts55are fixed to the filter cartridge main body23.

The normal arrangement of the vertical struts55is straight, as shown inFIG.8a, however, when the aforementioned pushing and twisting motion is applied to the filter cartridge20, the struts55deform in a corresponding manner to the filter cartridge main body23, as shown inFIG.8b, until the filter cartridge reaches its second configuration. Once the filter cartridge20is released from its second configuration, it will return naturally to its first, uncompressed configuration when the struts55return to their natural arrangements.

FIGS.9,10aand10bshow schematically a filter cartridge20in accordance with the present invention in its first (expanded) configuration being inserted into a hand held vacuum cleaner58such that the filter cartridge sits horizontally in the vacuum cleaner. The filter cartridge is placed into the vacuum cleaner (arrow F inFIG.10b) such that the second end portion22of the filter cartridge20sits next to a suction air inlet59for a vacuum drive (not shown) of the cleaner. The vacuum cleaner comprises an open-ended chamber56, which slides (arrow C inFIG.10b) over the filter cartridge20to the until an interior face of the end cap57abuts against the inner seal34and outer seal29of the first end portion21of the filter cartridge20. The filter cartridge may be removed without touching the cartridge by axially shifting the chamber housing (as shown by the arrow R inFIG.10a), 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 cartridge20through the nozzle65, which feeds into the central opening27of the filter cartridge by the suction motor behind the suction inlet59. Air is drawn through the filter material of the body23and the second end portion22. The filter body portion has a length which is less than the interior length of the vacuum chamber56, and a diameter that is less than that of the chamber65. This ensures a separation between the suction inlet orifice59and the filter end portion22, 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.

FIGS.11ato11cshow schematically an alternative arrangement of a handheld vacuum cleaner60in which the filter cartridge20in accordance with the present invention sits in a vertical orientation in a vacuum chamber61. The chamber is fed by an elbow inlet pipe63in a lid64of the chamber. This inlet pipe is fed by the nozzle tube65. The lid may be opened (arrow inFIG.11a) 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.

Second Embodiment

A filter cartridge in accordance with a second embodiment of the invention is shown generally as200inFIG.12. The cartridge has a cylindrical body portion201formed of a filter membrane material suitable for vacuum cleaner use. The body portion has an elongate welded seam202extending in an axial direction. A distal end203of the cartridge (best seen inFIG.15) comprises a flat disc of the filter membrane material, with a welded annular seam204formed by overlapping portions of the body portion distal edge and the outer region of the flat disc. A proximal end205of the filter cartridge is formed with as a unitary, generally annular support member206which is a moulding of plastics material. The support includes an inner frusto-conical portion209which tapers inwardly from an outer base region210to a central collar207around an inlet orifice240. A rim208is provided around the collar, which serves as a sealing bead when the cartridge is placed inside a vacuum cleaner. From the outer base region210the support includes a portion212which flares outwardly to an annular outer flange feature211.

InFIG.13the filter cartridge is shown before loading into a handheld vacuum cleaner220. The vacuum cleaner has a vacuum chamber221of generally cylindrical shape defined by a generally cylindrical housing223. The chamber has a proximal end provided with a collar222. A lower region of the collar is provided with a hinge224by which a lid member225is attached to the housing223. The lid member has a circular, dished configuration and a central inlet orifice226. An outer region of the lid member is provided with an inset semi-circular clamping member227. When the filter cartridge is inserted into the chamber221, the annular flange feature211abuts the collar222, with the support206nested in the chamber, set back from the flange feature. The lid member is then closed by pivoting around the hinge224. The outer edge of the lid member is held tightly against the flange feature211as the clamping member227is fastened to a retaining latch (not shown) on the upper edge of the collar222. This holds the cartridge in position and ensure an air-tight seal is maintained between the support206, collar222and lid member225. The central inlet orifice226of 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 collar207, induced by a suction drive228provided at a distal end of the vacuum cleaner.

InFIGS.14aand14bthe distal side of the support member206is shown. A sectioned support member is shown inFIG.14c. InFIG.14a shroud member230having a generally horse-shoe shape is shown surrounding the central collar207of the support. A chord feature229of the collar207is best seen inFIG.15. The chord feature provided a flat edge region to the collar inner edge. Three spaced apart studs231are provided along the chord feature. A transparent planar flap member232is has the shape shown inFIG.15which corresponds to the inner shape of the collar227. Three spaced apart bores233are provided along one edge region of the flap member. Projecting out from the said one edge region is a tongue feature234. The flap member is placed over the three studs213with 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 wedge235. The flap member acts as a cantilever closure which, at rest, obturates the inlet orifice240. When a vacuum suction is applied to the vacuum chamber224, the airflow into the filter cartridge through the orifice240causes the flap member to bend inwards, as shown inFIGS.14band14c. Two radially directed nubs241,242ore provided diametrically opposed to one another on the inside of the shroud230. 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 graphFIG.16demonstrate 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 475 g) than the filter cartridge of the first embodiment (420 g) 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 200 g.

To summarise the present invention relates to a filter cartridge 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 having an opening provided through the first end wall for receiving air-entrained detritus into the interior, the opening being defined by a rigid support structure which spans and supports the first end wall of the cartridge. The cartridge typically includes a non-return valve which closes when suction is removed so as to help prevent collected detritus escaping from the filter cartridge interior. The valve may comprise a conical valve with flexible facets, or a cantilevered flap.