Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
  • A62B27/00—Methods or devices for testing respiratory or breathing apparatus for high altitudes
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
  • A62B18/00—Breathing masks or helmets, e.g. affording protection against chemical agents or for use at high altitudes or incorporating a pump or compressor for reducing the inhalation effort
  • A62B18/08—Component parts for gas-masks or gas-helmets, e.g. windows, straps, speech transmitters, signal-devices
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
  • A62B23/00—Filters for breathing-protection purposes
  • A62B23/02—Filters for breathing-protection purposes for respirators

Definitions

• This invention relates to a filter cartridge for a respiratory mask, to be used in areas and/or work where there is a high level of pollution and/or hazardous environment, and a method of manufacturing such a filter cartridge.
• PPE personal protection equipment
• Respiratory masks which are more suited to long-term use, and are more comfortable to wear, have a face-piece made from moulded rubber which is held over the wearer's nose and mouth by means of an adjustable head strap, or plurality of straps, conventionally made from an elasticated fabric or rubber.
• the face-piece forms a hermetic seal against the wearers face.
• Such respiratory masks have at least one opening on the side of the face-piece to which a filter cartridge can be fitted, often by engaging corresponding screw threaded attachment means on both the filter cartridge and the respiratory mask.
• a number of different types of filter cartridges are known in the art, and vary in properties of weight, size, longevity and filterability.
• Filter cartridges Single-, or few-, use cartridges are known which are advantageously smaller and lighter, but have a much shorter lifespan than more robust filter cartridges and/or may not be suitable for all types of hazardous environments.
• Such filter cartridges are known as 'pancake' or disc-filters and typically have the filter media exposed on the outer wall of the filter frame.
• filter cartridges are preferred, and typically comprise a hard outer casing in which the filter media is provided. It is important to ensure the respiratory mask and filter are fitted correctly before, and periodically during, the wearer's time in a hazardous environment, and in fact currently, health and safety regulations require a pre-use fit check each time a face-piece is worn and before entering the hazardous environment. Inadequate fit will cause a significant reduction in the protection afforded to the wearer, and will allow airborne contaminants and particulates to leak into the mask.
• Pre-use fit procedures vary according to the specific configuration of the respiratory mask and/or filter cartridge, For the type described above, wherein the mask itself requires at least one filter cartridge or disc filter to be fitted thereto, the procedure generally involves temporarily sealing the respiratory airflow which is defined through the filter cartridge at the location at which the filter cartridge is attached to the mask.
• a generally tubular connecting member is provided on the filter device that carries the means to attach the filter device over the opening in a face mask.
• a foam gasket seal is typically provided around the connecting member or around the opening in the face mask. This provides a deformable layer between the filter cartridge and the respiratory mask. When the filter cartridge is attached to the respiratory mask, the foam gasket seal is compressed in some areas, but able to expand into other areas where there may be a gap due to uneven surfaces, thus providing the required seal.
• Foam gasket seals must be attached to the filter cartridge material and/or respiratory mask by means of an adhesive.
• the adhesive it is known for the adhesive to fail and the foam gasket seal to become loose, dislodged or broken, thus rendering the filter cartridge and/or respiratory mask unusable.
• foam can become brittle and permanently deformed over time, and, depending on where it is fitted, can reduce the lifetime of the respiratory mask and/or filter cartridge.
• a filter cartridge for a respiratory mask comprising a first and second frame member pivotally connected together at one end, said first frame member comprising a connecting member configured to connect said filter cartridge to a respiratory mask for use and defining a breathing aperture therethrough which extends through said first frame member and defines a respiratory flow path when said filter cartridge is in a first configuration, said filter cartridge being configured to receive a filter media therein or thereon to filter air, in use, flowing along said respiratory flow path, said first and second frame members being selectively pivotally moveable relative to each other from said first configuration to a second configuration in which a seal is formed between said first and second frame members and said respiratory flow path is blocked, characterised in that said filter cartridge further comprises a double- sided gasket seal comprising a first seal portion that provides said seal between said first and second frame members in said second configuration, and a second seal portion on said connecting member configured to
• the filter cartridge may comprise a discfilter frame, wherein said first frame member comprises a generally planar base and said second frame member comprises an elongate lever pivotally mounted at one end to said first frame member.
• the connecting member may be a generally tubular member having a lower end portion that extends outwardly from a breathing aperture provided in said base, and the second seal portion may be provided around said lower end portion of said connecting member, at or adjacent to said base.
• the lever may include a cover portion configured to cover said breathing aperture to block said respiratory flow path in said second configuration, and wherein said first seal portion is provided around the periphery of said breathing aperture.
• the connecting member may be a generally tubular member that extends through a breathing aperture provided in said base and has a lower end portion and an upper end portion
• the lever may include a cover portion configured to cover the end of said upper end portion of said connecting member to block said respiratory flow path in said second configuration, and wherein said first seal portion is provided around the peripheral end of said upper end portion.
• the first and second seal portions may be connected by an integral joining strip that extends through a channel in said first frame member, and the gasket seal may be formed of a rubber resin material such as thermoplastic elastomer (TPE) rubber resin.
• TPE thermoplastic elastomer
• the filter cartridge may comprise an encased filter cartridge, wherein said first frame member comprises an at least partially open-topped base receptacle configured to receive therein a filter media, in use, and said second frame member comprises a cover pivotally mounted at one end to said base receptacle for selective pivotal movement between a first configuration, in which there is a gap between the upper edges of the base receptacle and the inner surface of the cover, said gap defining said respiratory air flow path, and a second configuration in which the inner surface of the cover covers the open top of the base receptacle and blocks the respiratory flow path.
• the first seal portion may extend around said upper edges of said base receptacle.
• a generally planar mesh cover may be provided across said open top of said base receptacle.
• the connecting member may be a generally tubular member that extends from or through a breathing aperture provided in said base receptacle and has a lower end portion, said second seal portion being provided around said lower end portion of said connecting member, at or adjacent to said base receptacle.
• first and second seal portions may be connected by an integral joining strip that extends through a channel in said base receptacle.
• a second breathing aperture may be provided in said cover, at or adjacent the end thereof opposite to the end at which it is pivotally connected to said base receptacle.
• the gasket seal may be formed of a rubber resin material such as a thermoplastic elastomer rubber resin.
• the breathing aperture may be provided longitudinally off-centre in said first frame member, nearer to the end at which the second frame member is pivotally connected to the first frame member than to the opposing end.
• a method of manufacturing a filter cartridge according to any of the preceding claims comprising the steps of: moulding said first frame member, said first frame member comprising a channel therethrough and defining a first recess around an opening in or of said first frame member forming said respiratory flow path and a second recess around said connecting member, said first and second recesses and said channel together defining a fluid flow path therethrough; performing an over-moulding process in respect of said first frame member by injecting into said fluid flow path a molten rubber resin to form said double-sided gasket seal, wherein rubber resin flowing into said first recess forms said first seal portion and rubber resin flowing into said second recess forms said second seal portion; moulding said second frame member; and assembling said first and second frame member to form a filter cartridge according to any of the preceding claims.
• the method may further comprise the step of transporting said assembled filter cartridge to a conveyor belt and applying, at said conveyor belt, a filter media on or to said
• first frame member may be moulded in a first cavity and said second filter member may be moulded separately in a second cavity, and automated transport means may be used to move at least one of said frame members to the same location as the other of said frame members for assembly.
• Automated transport means may also be used to transport said assembled filter frame to said conveyor belt.
• Such automated transport means may comprise one or more robotic devices.
• the rubber resin may be a thermoplastic elastomer (TPE) rubber resin.
• Figure 1 A is a schematic perspective cross-sectional view of a disc-filter according to a first exemplary embodiment of the present invention
• Figure 1 B is a schematic side cross-sectional view of the disc-filter of Figure 1 A
• Figure 1 C is a schematic perspective view of the frame member of the disc-filter of Figures 1 A and 1 B;
• Figure 2 is a schematic perspective view of the double-sided gasket seal of the disc-filter of Figure 1 A;
• Figure 3 is a schematic partial close-up view of the connecting member and gasket seal of the disc-filter of Figure 1 A;
• Figure 4 is a top view of the housing base of an encased filter style cartridge according to a second exemplary embodiment of the invention.
• Figure 5 is a bottom view of the housing base of Figure 4;
• Figure 6 is a schematic side view of an encased filter cartridge according to a second exemplary embodiment of the present invention.
• Figure 7 is a schematic cut-away view of the filter cartridge of Figure 6; and Figures 8A to 8D are schematic diagrams showing some of the steps of a method of manufacturing a dis-filter according to a first exemplary embodiment of the present invention.
• a disc filter style filter device according to a first exemplary embodiment of the present invention is illustrated, and comprises a lever 10 and frame member 12.
• the frame member 12 comprises a single piece of moulded plastic, of generally rectangular shape, with peripheral cut-out portions 1 1 to reduce the material used and the overall weight of the device.
• a generally circular breathing aperture 14 is provided in the frame member 12, the breathing aperture being located off-centre, i.e. nearer one end (hereinafter referred to as the 'front' end 12a) than the other.
• a generally tubular connecting member 16 extends through the breathing aperture 14, having an 'inner' end 14a extending beyond the inner side of the frame member 12 and an opposing 'outer' end 14b extending beyond the opposing 'outer' side of the frame member 12.
• a peripheral flange 18 extends radially outwardly from the connecting member 16, immediately below the above- mentioned outer side of the frame member 12.
• An extension portion 32 extends from the outer edge of the peripheral flange 18, toward the 'front' end 12a, and from the outer to the inner side, of the frame member 12.
• Struts 21 extend radially across the breathing aperture and meet at a generally central location therein, wherein a pin 23 is provided for receiving and supporting a rubber diaphragm (not shown).
• Connecting member 16 carries attachment means for attaching the filter device over an opening in a respiratory face mask.
• attachment means may be a twist-lock mechanism, as illustrated, but it will be understood by a person skilled in the art that other types of attachment means may be provided, and the present invention is not necessarily intended to be limited in this regard.
• a channel 19 extends through the peripheral flange 18 nearest the front end 12a, from the inner to the outer side of the frame member 12.
• the lever 10 is pivotally mounted to the frame member 12 adjacent the
• the lever 10 comprises an elongate piece of moulded plastic, again generally rectangular in shape, but shorter and narrower than the frame member 12. At one end, there is provided a mechanism for pivotally mounting it to the frame member 12, in this case the mechanism comprising a pair of stepped feet 25 which are received in respective openings 27 in the frame member 12. The mechanism, thus assembled, allows the lever 10 to be pivoted under manual force toward the frame member 12.
• a generally circular cap region 20, defined by a protruding rim 20a is formed on the 'inner' surface of the lever 10 such that, when assembled, the location of the cap region 20 corresponds to the location of the 'inner' end 14a of the connecting member 16.
• the lever 10 is biased away from the frame member 12 such that, at rest, it extends at an angle from the pivot point 22 away from the frame member 12.
• a user grips the frame member 12 at the 'rear' end 12b and the free end of the lever 10 between their thumb and forefinger, squeezing them together, to pivot the lever 10 toward the frame member 12 such that the protruding rim 20a of the cap region 20 covers the breathing aperture defined at the 'inner' end of the connecting member 16.
• a foam gasket seal would be provided around the periphery of the breathing aperture within the filter frame to provide a good seal between the cap region on the lever 10 and the breathing aperture.
• Prior art manufacturing techniques would not permit for the connecting member 16 to extend into the filter frame because it is not possible, using known techniques, to provide a foam gasket seal thereon.
• a second, separate foam gasket seal would be provided around the connecting member, immediately below the peripheral flange, to provide a good seal between the filter cartridge and the face mask, in use.
• the present invention comprises a unique, double-sided, overmoulded gasket seal, as described hereinafter.
• a disc filter according to a first exemplary embodiment of the present invention, comprises a gasket seal comprising a first seal portion 24 that extends around the periphery of the 'inner' end of the connecting member 16, and a second seal portion 26 that extends around the connecting member 16, immediately below the peripheral flange 18.
• the seal portions 24, 26 are connected by a narrow joining strip 28 that extends through the channel 19 through the peripheral flange 18.
• the double-sided gasket seal 30, comprising the first and second seal portions 24, 26 and the joining strip 28 is integrally formed of rubber resin such as, for example, thermoplastic elastomer (TPE) rubber, e.g. Dryflex ®.
• TPE thermoplastic elastomer
• the double-sided gasket seal 30 is formed by a single overmoulding process, as described later, wherein the molten rubber resin is injected at point B at the end of the extension portion 32 that extends from the outer edge of the peripheral flange 18 to the 'inner' surface of the frame member 12, such that it flows through a recess located around the periphery of the 'inner' end of the connecting member 16, through the channel 19 and through a recess located around the connecting member 16 immediately below the peripheral flange 18, so as to create the double-sided gasket seal 30 illustrated in Figure 2.
• a unique, double-sided, rubber gasket seal 30 is provided on both the inside and the outside of the frame member 12, that extends through the frame member 12 (via the channel 19).
• the filter frame (comprising the frame member 12, the lever 10 and the double-sided gasket seal 30) is encased within a filter media 13, with the Outer' end 14b of the connecting member 16 extending through an aperture or hole in the filter media 13.
• the assembly is attached to a respiratory face mask by locking the Outer' end of the connecting member 16 within an opening in the face mask, such that the 'front' end 12a of the frame member faces forward (i.e. the general direction in which the user is facing) and the 'rear' end 12b is directed rearwardly accordingly.
• the second seal portion 26 of the gasket seal 30 provides an airtight seal between the connecting member 16 and the face mask.
• the user squeezes the free end of the lever 10 (through the filter media 13) toward the frame member 12 using their thumb and forefinger, as described above, to bring the cap region 20 down over the first seal portion 24 around the 'inner' end of the connecting member 16, thereby sealing the breathing aperture. If the user tries to breathe, there should be no respiratory path at all if the filter device is fitted and operating correctly.
• the assembled filter cartridge comprises a housing cover 50, filter media 14, a housing base 52, and a unique double-sided gasket seal 30'; and the encased filter cartridge , thus assembled, can be fitted to the face-piece of a respiratory mask (not shown), via an opening therein, as before.
• the filter media 14 is held within the housing base 52 and covered by the housing cover 50.
• the housing cover has an intake aperture 58 at one end thereof, and side walls that extends down over the side edges of the housing base 52.
• a connecting member 16' extends from the bottom of the filter cartridge and is formed integrally with the housing base 52.
• the connecting member 16' of the present exemplary embodiment is shown to be a twist-lock mechanism, which engages with a corresponding aperture in the face-piece of a respiratory mask (not shown) to connect the filter cartridge within an opening in the respiratory mask, as and when required.
• a twist-lock mechanism engages with a corresponding aperture in the face-piece of a respiratory mask (not shown) to connect the filter cartridge within an opening in the respiratory mask, as and when required.
• other types of attachment mechanisms such as co-operative mating threads on the connecting member 16' and the aperture in the respiratory mask, or snap- or interference-fit, may be used.
• a breathing aperture 18' is provided through the bottom surface of the housing base 52 and the connecting member 16' extends outward therefrom.
• a respiratory airway is defined through the aperture 58 in the housing cover 50, through the filter media 14 held within the housing base 52, through the breathing aperture 18' and into a face-piece of the respiratory mask, when the filter cartridge is attached to a respiratory mask for use.
• Struts 22 extend radially inwardly across the breathing aperture 18' and meet in a generally central point.
• the struts 22 may provide support for a rubber circular diaphragm, as before.
• the inner surface of the housing cover 50 is provided, at the end opposite to that having therein the breathing aperture 58, with a pivot pin (not shown) which is cooperatively engaged with a pivot loop provided on an outer wall of the housing base 52.
• the pivot pin and pivot loop together form a fixed pivotal connected between the housing cover 50 and the housing base 52.
• the unique double-sided gasket seal 30' extends around the upper edges of the housing base 52 and also around the connecting member 16', immediately below the bottom surface of the housing base 52, to provide the dual functions of providing a seal between the upper edges of the housing base 52 and the inner surface of the housing cover 50 (during a negative pressure fit check) and also to seal the connecting member 16' against the edges of the opening in the face mask.
• the double-sided gasket seal 30' is formed by an overmoulding process using rubber resin.
• the housing base 52 is formed with a planar grid 52' across its upper edges and, during manufacture, molten rubber resin is injected at a point adjacent the end at which the pivotal connection between the cover 50 and the base 52 is located and flows through a recess provided around the upper edges of the housing base 52 and also through a recess provided around the connecting member 16', immediately below the housing base 52.
• a channel extends through the housing base 52, at or near the injection point, such that the first seal portion 30a' (around the upper edges of the base 52) and the second seal portion 30b' (around the connecting member 16') are integrally formed, in a single over-moulding process, with a joining strip (not shown) therebetween.
• the exemplary embodiments of the invention described above are advantageous for a number of reasons. Due to the manufacturing process, which will be described hereinafter, the cost per filter cartridge is reduced. When manufacturing multiple millions for sale with respiratory masks and/or as spares, this cost saving amounts to a significant increase in profit margins for the manufacturer, or ultimately a saving by the end user. Additionally, since the rubber gasket seals are more effective at creating a seal between two surfaces the cost saving represents an improvement in the quality and effectiveness of the end product. Rubber is more durable than foam, therefore the lifetime of the filter cartridges is extended and the quality of the seal is increased, with less material and labour expense to achieve it.
• FIGS. 8A-8D of the drawings a novel, fully automated, method of manufacturing filter cartridges having the unique double-sided gasket seals 30, 30' of the filter devices described above begins by separately moulding the two parts of the filter cartridge frame/housing.
• the disc-filter style cartridge of the first exemplary embodiment described above will be referenced by way of example only; however, it will be clear to the person skilled in the art that the manufacturing process can be modified to make the encased filter cartridge of the second exemplary embodiment described above.
• the frame memberl 2 of the filter cartridge is moulded in a first cavity 100.
• a robotic arm 102 moves the frame member 12 from a first cavity 100 to a second cavity 104, where a rubber resin (not shown) is over- moulded into and through the frame member 12, the injection point of the rubber resin being shown in Figure 1 A of the drawings indicated at arrow B. Meanwhile a separate tool moulds the lever 10 (not shown).
• Robotic arms bring the lever 10 and the frame member 12 together for assembly. Once assembled the frame member 12 and lever 10, complete with over-moulded double-sided gasket seal 24, form the main filter frame 1 12 of the disc-filter cartridge.
• the filter frames 1 12 are then deposited onto a conveyor belt 1 16 on which a continuous roll of fibrous filter media 1 10 is prepared with pre-punched holes.
• the pre-punched holes are equal in diameter to the connecting member 16 of the frame member 12.
• the connecting member 16 of each filter frame 1 12 is aligned with a pre-punched hole by a pair of robotic arms 106, 108. A series of manoeuvers by the robotic arms fold the filter media 1 10 over the filter frame 1 12.
• the filter media 1 10 is then secured in place by ultrasonically welding the filter media 1 10 around the perimeter of the filter frame 1 12, and also around the connecting member 16. Excess filter media 1 10 is removed by any suitable method known in the art, in this exemplary embodiment the completed disc-filter style cartridge is separated from the roll of filter media 1 10 by a fast-moving downward-acting cutter 1 14. It will be apparent to those skilled in the art that modifications to this method of manufacturing can be made in order to enable the process to be used for encased filter cartridges of the type described above with reference to a second exemplary embodiment of the present invention, and indeed other filter cartridges to which a gasket seal needs to be fitted both inside and outside the main filter cartridge frame.
• the method of manufacturing is fully-automated and therefore reduces labour costs and waste while improving uniformity and quality of the end product.
• the unique double-sided gasket seal 30, 30' present on the frame member 12/ housing base 52 presents a unique improvement over the prior art foam gasket seals.
• the gasket seal is replaced every time the filter cartridge is replaced and therefore very little wear builds up on the gasket seal during the lifetime of the filter cartridge, thereby improving safety and reliability.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Pulmonology (AREA)
• Respiratory Apparatuses And Protective Means (AREA)

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Publications (1)

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Citations (3)

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• 2017
  • 2017-04-19 GB GB1706201.9A patent/GB2561586B/en active Active
• 2018
  • 2018-04-19 ES ES18721445T patent/ES2968275T3/es active Active
  • 2018-04-19 PL PL18721445.7T patent/PL3612278T3/pl unknown
  • 2018-04-19 EP EP18721445.7A patent/EP3612278B1/de active Active
  • 2018-04-19 WO PCT/GB2018/051025 patent/WO2018193256A1/en unknown

Patent Citations (3)

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