Passive self purging microfibre capture device for laundering appliances

Abstract

A microfibre capture device, suitable for use in a washing machine, comprising a hollow elastomeric body 10 of generally annular geometry having an internal cavity with at least one baffle 20 definin

Description

[0002] The invention relates to devices for reducing microplastic pollution generated during textile laundering. More particularly, it concerns a passive, reusable microfibre capture device configured for free movement within a washing machine drum, operable to mechanically retain microfibres during washing and to automatically expel retained microfibres during spin cycles without user intervention. BACKGROUND OF THE INVENTION

[0003] Synthetic textiles release significant quantities of microfibres during domestic and commercial laundering. These fibres, typically ranging from tens of micrometres to several millimetres in length, are discharged with wash water and are insufficiently retained by wastewater treatment infrastructure, contributing to persistent environmental microplastic pollution.

[0004] Numerous approaches have been proposed to mitigate this problem. External in-line filters require plumbing modification, impose flow resistance, and necessitate frequent manual cleaning, thereby limiting consumer adoption. Textile containment systems, such as bags or mesh enclosures, impede garment motion, degrade washing performance, and capture only coarse debris. Chemical sorption-based devices rely on functionalised substrates or coatings that are costly to manufacture, vulnerable to surfactant degradation, and require periodic regeneration or replacement.

[0005] A common deficiency of existing solutions is the requirement to permanently retain captured fibres within the device, thereby necessitating user maintenance and eventual disposal. No known consumer-scale solution integrates a self-purging mechanism that automatically releases captured microfibres using forces inherently generated by the washing machine itself, particularly through elastic deformation of an annular body to reduce internal volume and induce targeted hydraulic flow for expulsion without valves or moving parts. Devices employing mixed materials further introduce end-of-life recycling complexity and increased manufacturing cost.

[0006] There exists a need for a durable, low-cost, user-independent microfibre capture device that operates passively within a washing machine drum, requires no modification to the appliance, automatically purges retained microfibres without manual intervention, and is readily manufacturable and recyclable. SUMMARY OF THE INVENTION

[0007] The invention addresses the aforementioned needs by providing a reusable microfibre capture device comprising a hollow, elastomeric body of generally toroidal or annular geometry defining a central flow aperture and an internal cavity. One or more baffle structures are integrally formed within the cavity and define a tortuous flow path having textured capture surfaces.

[0008] During a wash cycle, free tumbling of the device within the washing machine drum induces water flow through the cavity via the central aperture. Microfibres entrained in the wash liquor are mechanically retained on the textured baffle surfaces through interception, impaction, and frictional engagement, with the central aperture facilitating bidirectional flow to enhance capture efficiency.

[0009] During a spin cycle, centrifugal forces elastically deform the toroidal or annular body, reducing the effective volume of the internal cavity and inducing reverse or accelerated fluid flow. This deformation-driven hydraulic action dislodges retained microfibres and expels them from the cavity through the central aperture, returning them to the washing machine drum where they are captured by the machine's existing lint or debris filter. The reliance on the same central aperture for both ingress and egress is integral to the passive self-purging mechanism.

[0010] In a key aspect, the device is integrally formed from a unitary mass of elastomeric material, requiring no coatings, chemical functionalisation, moving parts, valves, or user maintenance. This unitary construction provides a passive, self-maintaining, and fully recyclable solution for reducing microfibre emissions during laundering. DETAILED DESCRIPTION OF EMBODIMENTS

[0011] With reference to the summary above, exemplary embodiments of the invention are now described in further detail. Overall Geometry and Hydrodynamic Operation

[0012] The microfibre capture device comprises a hollow body having a generally toroidal or annular geometry. The body defines a central flow aperture and an enclosed internal cavity extending circumferentially around the aperture. This geometry is critical for enabling free tumbling and bidirectional flow through the aperture, which distinguishes the device from non-apertured or linear designs that cannot achieve the same pressure-driven capture and purging mechanisms. Figure 1 illustrates a schematic cross-sectional view of a microfibre capture device according to an embodiment of the invention. The device comprises a hollow, elastomeric body (10) having a generally annular geometry defining a central flow aperture and an internal cavity extending circumferentially around the aperture. Disposed within the internal cavity is at least one baffle structure (20). The baffle structure extends circumferentially within the cavity to define a tortuous flow path. In the illustrated embodiment, the baffle structure comprises a curved or helical configuration arranged to increase fluid residence time within the cavity. The baffle structure comprises textured capture surfaces configured to mechanically retain microfibres entrained in wash liquor during a wash cycle through interception, impaction, and frictional engagement. The capture mechanism is purely mechanical and does not rely on chemical, electrostatic, or adhesive forces. The figure is schematic and not to scale; relative dimensions, curvature, surface texture, and baffle pitch may be varied without departing from the scope of the claims.

[0013] In exemplary embodiments, the outer diameter of the body is selected to permit free tumbling within domestic and commercial washing machine drums without interfering with drum rotation or textile motion. The inner diameter defining the central aperture is proportioned to generate adequate flow velocity during tumbling while maintaining structural integrity.

[0014] The wall thickness of the body is selected to permit elastic deformation under centrifugal loading encountered during spin cycles while maintaining structural integrity during repeated wash cycles. This deformation is essential for the self-purging mechanism, as it directly couples centrifugal force to hydraulic expulsion.

[0015] During washing, tumbling of the toroidal body within the wash liquor generates relative motion between the device and surrounding water, producing a pressure differential that drives water flow through the central aperture and internal cavity: The pressure differential is generated transiently by bluff-body wake effects during tumbling, not by sustained airfoil lift. Each tumble produces a momentary high-pressure region on the upstream face of the toroid while a low-pressure wake forms downstream, creating a jet through the central aperture that carries microfibres into the cavity. This mechanism requires no attached laminar flow or fixed angle of attack, making it robust in the chaotic environment of a washing machine drum. Internal Baffle Structure and Capture Surfaces

[0016] One or more baffle structures are integrally formed within the internal cavity. In preferred embodiments, the baffle structure comprises a helical baffle extending circumferentially along the cavity wall and defining a tortuous flow path.

[0017] The helical baffle may comprise a plurality of turns and may have a pitch angle configured to increase residence time of flowing water and increase the probability of microfibre interaction with internal surfaces. Non-helical or straight baffles are less effective for multi-scale capture.

[0018] The baffle structure comprises textured capture surfaces configured to mechanically retain microfibres. In some embodiments, the capture surfaces comprise multiple capture zones with differing texture scales. A proximal capture zone may include macroscopic ridges configured to intercept relatively large fibres, while a distal capture zone may include micro-textured surface features configured to retain smaller fibres through frictional engagement.

[0019] The capture mechanism is purely mechanical and does not rely on electrostatic, chemical, or adhesive forces, ensuring durability and compatibility with conventional detergents. Self-Purging Mechanism During Spin Cycles

[0020] During a spin cycle of the washing machine, centrifugal forces act on the mass of the toroidal body. Due to the elastomeric nature of the material, these forces induce elastic deformation of the body, including radial compression of the internal cavity.

[0021] This deformation reduces the effective cavity volume sufficiently to generate a hydraulic pressure increase that induces reverse or accelerated fluid flow through the central aperture. This action dislodges microfibres retained on the baffle surfaces and expels them back into the washing machine drum. The expelled fibres are subsequently transported with residual water and captured by the washing machine's existing lint or debris filter.

[0022] Following completion of the spin cycle, the body elastically returns to its original geometry, restoring the capture configuration for subsequent wash cycles. This mechanism achieves substantial purge efficiency per spin cycle. Materials and Construction

[0023] In a defining feature of a preferred embodiment, the body and the at least one baffle structure are integrally formed from a unitary mass of elastomeric material. This construction excludes devices where the body and baffle are separate components joined after formation. The unitary mass ensures uniform elasticity and structural continuity, which are beneficial for predictable deformation during the purge cycle and for end-of-life recyclability.

[0024] In alternative constructions, the baffle structure could be formed separately and subsequently joined to the body. Such a construction may, however, introduce potential points of failure, complicate recycling, and may not achieve the uniform elastic response of the unitary embodiment.

[0025] In preferred embodiments, the elastomeric material is a thermoplastic vulcanisate (TPV) having a Shore A hardness sufficient to enable repeatable elastic deformation without structural failure over the device's service life.

[0026] The material is inherently hydrophobic and does not require surface coatings or chemical modification to function. The use of a unitary material mass facilitates end-of-life recyclability and significantly reduces manufacturing complexity and cost.

[0027] The device is configured to withstand repeated exposure to wash temperatures, detergents, and mechanical loading over an extended service life without degradation of its elastomeric properties or capture performance. Manufacturing

[0028] The unitary device according to the preferred embodiment may be manufactured using a single-shot injection moulding process in which the toroidal geometry and internal baffle structures are formed simultaneously in a single mould cavity. No secondary assembly, coating, or surface treatment steps are required. This approach enables high-volume production at low per-unit cost. Alternative Embodiments

[0029] Alternative embodiments may include non-circular or ovoid annular geometries configured to bias tumbling behaviour within the drum. The outer surface of the body may include ribs, dimples, or protrusions to increase hydrodynamic drag and enhance tumbling motion.

[0030] Multiple devices of differing sizes may be used simultaneously within a washing machine drum to accommodate varying load sizes or fabric compositions. Further variations may include segmented cavities or variable-pitch baffles to optimise for specific fibre size distributions.

Claims

26Claims1. A microfibre capture device for use within a washing machine drum, comprising:a hollow body formed from an elastomeric material and having a generally annular geometry defining a central aperture and an internal cavity extending circumferentially around the aperture; andat least one baffle structure disposed within the internal cavity and defining a tortuous flow path having fibre-retaining surfaces,wherein the body is configured for free tumbling within a washing machine drum such that:(a) during a wash phase, tumbling of the body induces fluid flowthrough the central aperture and the internal cavity to mechanically retain microfibres on the fibre-retaining surfaces; and(b) during a spin phase, centrifugal forces elastically deform the body to reduce an effective volume of the internal cavity and thereby actively pump fluid from the cavity through the same central aperture to expel retained microfibres,the device thereby passively alternating between a capture state and a purge state without valves or moving parts.

2. A device according to claim 1, wherein the central aperture provides the sole fluid communication between the internal cavity and an exterior of the body.

3. A device according to claim 1 or 2, wherein the baffle structure extends circumferentially within the cavity to increase interaction between fluid flowing through the cavity and the fibre-retaining surfaces relative to a direct path through the cavity.

4. A device according to any preceding claim, wherein the baffle structure comprises a helical, curved, segmented, or spoked configuration defining the tortuous flow path.

5. A device according to any preceding claim, wherein the fibre-retaining surfaces comprise surface textures at multiple scales configured to mechanically engage microfibres of different sizes.

6. A device according to any preceding claim, wherein the body and the at least one baffle structure are integrally formed from a unitary mass of elastomeric material.

7. A device according to any preceding claim, wherein the elastomeric material is selected from thermoplastic vulcanizates, thermoplastic elastomers, thermoplastic polyurethanes, or blends thereof.

8. A device according to any preceding claim, wherein the body is configured to elastically recover toward an original geometry after cessation of centrifugal forces so as to restore the capture state for a subsequent wash phase.

9. A device according to any preceding claim, wherein an outer surface of the body comprises surface features configured to promote tumbling and fluid interaction within the washing machine drum.

10. A passive self-purging microfibre capture device comprising an elastomeric annular body having an internal cavity containing fibre-retaining structures and a single aperture communicating with the cavity,wherein tumbling motion of the body in wash liquor induces a first fluid flow through the aperture into the cavity to capture microfibres, and centrifugal elastic deformation of the body during spinning induces a second fluid flowthrough the same aperture that actively drives fluid from the cavity to expel captured microfibres,the transition between said flows being produced solely by a change between wash and spin operating conditions of a washing machine.13 02 2611. A device according to claim 10, wherein the fibre-retaining structures comprise at least one internal baffle defining a tortuous flow path within the cavity.

12. A device according to claim 10 or 11, wherein the body is formed as a single moulded component.

13. A device according to any of claims 10 to 12, wherein the device consists essentially of a recyclable polymer material.

14. A device according to any of claims 10 to 13, wherein the annular body has a toroidal geometry.

15. A device according to any of claims 10 to 14, wherein the cavity is configured such that elastic deformation during spinning produces a pressure increase that dislodges retained microfibres from the fibre-retaining structures.

16. A method of capturing and purging microfibres in a washing machine, comprising placing a microfibre capture device according to any of claims 1 to 15 in a washing machine drum with a textile load and operating the washing machine through a wash phase and a spin phase, wherein the device passively captures microfibres during the wash phase and expels captured microfibres during the spin phase by centrifugal elastic deformation.

17. A method according to claim 16, wherein the device remains within the drum fora plurality of consecutive wash and spin phases without removal or manual cleaning.

18. A method according to claim 16 or 17, comprising using a plurality of said devices concurrently within the drum.

19. A method according to any of claims 16 to 18, wherein microfibres expelled from the device are transported to a debris filter of the washing machine.

20. A method according to any of claims 16 to 19, wherein the device alternates between the capture state and the purge state solely in response to hydrodynamic and centrifugal forces generated by normal operation of the washing machine.13 02 26A

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