Security and airflow-limiting modular attachment assembly for the rear of a letterbox

Abstract

A security and airflow-limiting modular attachment assembly is provided for installation on the rear side of a letterbox. A security module 3 is configured to obstruct or prevent unauthorised access

Description

Field of the Invention

[0001] The present invention relates to modular security and airflow-limiting assemblies mountable at the rear of a letterbox formed in a door or wall, hereinafter referred to as the attachment assembly.

[0002] The assemblies are configured to obstruct or prevent unauthorised access—including fishing, lock tampering, or letterbox arson—while permitting repeated unhindered insertion of substantially all regular flexible mail items.

[0003] The assemblies further limit the uncontrolled passage of air, smoke (e.g., from a fire), and other environmental ingress, thereby enhancing security, draught-proofing, and environmental protection for a traditional letterbox of substantially horizontal width.

[0004] As used herein, the term “letterbox” refers to an opening formed through a structure, including a door or wall, for the delivery of mail items and is synonymous with “mail slot,” as commonly used in the UK. Background of the Invention

[0005] The publicly accessible traditional letterboxes allow anytime delivery of mail but present security risks and a likelihood of uncontrolled airflow, which is the transport of draught, smoke, dust, or other environmental contaminants.

[0006] Security solutions for the letterbox include letterbox security cowls or mail receptacles, which can be made of a variety of materials and shapes, and fitted at the back of the letterbox.

[0007] Although letterbox security cowls offer protection against fishing and access to locks through a letterbox, they allow passage of hazards, draughts, smoke, dust, or other environmental contaminants into a property. Furthermore, they do not prevent letterbox arson when flammable materials—typically liquid—are introduced and ignited, thereby blocking the primary escape route from the property.

[0008] Therefore, it is common to use mail receptacles that offer more protection. Among the known mail receptacles, there are mail receptacles configured to receive mail items inserted against the force of gravity. In case any volume of liquid is introduced through the letterbox, it will be drained by gravity out of the mail receptacle.

[0009] These mail receptacles are also distinctly unique and advantageous because they can be installed on both high and low letterboxes. This feature provides for letterbox protection in multiple doors with letterboxes at low level, and is also of a significant value for the long-time suffering postmen by providing protection from dog bites and trapped fingers at low-level letterboxes.

[0010] Among such mail receptacles, there are certain advantages in using open-top ones, having an opening at an upper region of the body.

[0011] Similar to the letterbox security cowls, these open-top mail receptacles do not have capacity issues because the opening allows mail items to pass through without being retained. This design results in a smaller size, a simpler structure, less protrusion from the surface, and lower costs.

[0012] Letterbox security cowls and mail receptacles are typically distinct from draught excluders and installed separately. Previous solutions designed primarily for security tend to offer none or poor sealing performance against airflow through the letterbox and the associated loss of the house heat.

[0013] They fail to provide a unified, modular assembly offering adjustability, multifunctional protection, and integrated performance.

[0014] Consequences include energy waste leading to higher energy bills, poor indoor air quality potentially causing mould growth, health and comfort issues, and even risk of loss of life from lethal poisonous gases, like odourless and invisible carbon monoxide. Buildings release more greenhouse gas emissions are into the atmosphere.

[0015] These risks must be prevented or mitigated, especially in doors, which are within the escape route.

[0016] Therefore, there is a need for a single modular attachment assembly for installation on the rear side of a letterbox that provides both security and airflow limiting at the rear of a letterbox and allows for repeated unhindered deliveries of substantially all regular flexible mail items. Summary

[0017] The present invention provides a security and airflow-limiting modular attachment assembly mountable at the rear of a letterbox formed through a structure, such as a door or wall.

[0018] The attachment assembly addresses the technical problem of preventing unauthorised access and extraction of items through the letterbox, while limiting uncontrolled airflow and environmental ingress, including smoke and draughts, without impeding repeated mail deliveries.

[0019] The attachment assembly comprises a security module and one or more airflow-limiting modules configured to cooperate with the security module.

[0020] The security module is configured to obstruct or prevent unauthorised access through the letterbox while permitting mail insertion, and comprises either a letterbox security cowl configured to receive mail items inserted downwards with the assistance of gravity toward an opening at a lower region of the body, or an open-top mail receptacle having an opening at an upper region of the body and configured to receive and retain mail items inserted upwards against the force of gravity, while optionally allowing delivered mail items to pass therethrough without being retained.

[0021] The airflow-limiting modules comprise one or more brush strip assemblies configured to limit passage of air, smoke, and environmental ingress through the letterbox and the security module, while providing obstruction supplementary to that provided by the security module against unauthorised access and extraction of items through the letterbox. Optionally, interfacesealing modules are provided at interfaces between assembly modules, the letterbox, and / or the rear face of the structure.

[0022] The attachment assembly may further comprise adjustable mounting brackets and a movable letterbox closure element. One or more components may be rigid, deformable, or foldable, and may be formed from fire-retardant, intumescent, heat-resistant, smoke-resistant, and / or low-smoke materials.

[0023] The invention provides a modular attachment assembly suitable for retrofitting or new installations, maintaining effective security and airflow limitation even where existing letterbox measures are absent, fail, or are compromised. Brief Description of the Drawings

[0024] With many possible embodiments of the proposed invention, only a few specific ones will now be described solely by way of examples with reference to the accompanying drawings as in Fig. 1-13 in which:

[0025] Fig. 1(a) - A rear perspective view of an embodiment of a letterbox security cowl with a firm configuration and fixing flanges folded outward.

[0026] Fig. 1(b) - A side sectional view of an embodiment of an attachment assembly featuring the letterbox security cowl, which is shown in Fig. 1(a), mounted on a rear face of a structure that has a letterbox with a sleeved letter plate.

[0027] Fig. 2(a) - A rear perspective view of an embodiment of a letterbox security cowl with a firm configuration and inward- folded fixing flanges.

[0028] Fig. 2(b) - A side sectional view of an embodiment of an attachment assembly featuring the letterbox security cowl, which is shown in Fig. 2(a), mounted on a rear face of a structure having a letterbox with a front-mounted letter plate.

[0029] Fig. 3 - A side sectional view of an embodiment of an attachment assembly featuring a letterbox security cowl with a firm configuration mounted on a rear face of a structure that has a letterbox with a sleeved letter plate.

[0030] Fig. 4 - A side sectional view of an embodiment of an attachment assembly featuring the embodiment of the letterbox security cowl, which is shown in Fig. 3, mounted on a rear face of a structure that has a front-mounted letterbox.

[0031] Fig. 5(a) - A rear perspective view of an embodiment of a letterbox security cowl with a firm configuration and inward- folded fixing flanges, which is composed of two portions.

[0032] Fig. 5(b) - A side sectional view of an embodiment of an attachment assembly featuring the letterbox security cowl, which is shown in Fig. 5(a), mounted on a rear face of a structure that has a letterbox with a sleeved letter plate.

[0033] Fig. 6(a) - A side sectional view of an embodiment of an attachment assembly featuring a letterbox security cowl with a foldable configuration, with its front wall formed by a flap of a rear-mounted portion of a sleeved letter plate, and with the extent of the flap's opening constrained by a limiter.

[0034] Fig. 6(b) - A front elevation of a rear face of a structure showing a brush strip assembly with a 45-degree configuration of a fixing carrier plate with bent portions at its ends, which are configured to form side walls of the letterbox security cowl, which is shown in Fig. 6(a).

[0035] Fig. 7 - A front elevation of a rear face of a structure having a letterbox and an interfacesealing element comprised of a sealing gasket fixed on the rear face of the structure.

[0036] Fig. 8(a) - the front elevation of the rear face of the structure, which is shown in Fig. 7, with two mounting brackets placed over the sealing gasket and attached to the structure by fixing elements. Also shown is a letterbox closure element that is placed beneath the open letterbox and has an attached brush strip assembly with a 90-degree configuration of a fixing carrier plate.

[0037] Fig. 8(b) - A side sectional view of the structure and the letterbox closure element, which is shown in Fig. 8(a).

[0038] Fig. 9 - A side sectional view of an embodiment of an attachment assembly featuring a letterbox security cowl with a firm configuration mounted on the rear face of the structure that is shown in Fig. 8(a).

[0039] Also shown are • three possible fixing positions for a front-mounted letter plate; and • a closure element with the attached brush strip assembly, which is positioned beneath the open letterbox.

[0040] Fig. 10 - A side sectional view of the attachment assembly, which is shown in Fig. 9, with the closure element position that substantially covers and shuts the letterbox.

[0041] Fig. 11(a) - A perspective view of an embodiment of an open-top mail receptacle with a firm configuration, which is configured to receive and retain mail items introduced against the force of gravity, has no front wall and an opening formed at a top region of the body.

[0042] Fig. 11(b) - A side sectional view of an embodiment of an attachment assembly with the open-top mail receptacle, which is shown in Fig. 11(a), mounted on a rear face of a structure with a letterbox.

[0043] Also shown are: • a brush strip assembly with a 180-degree configuration of a fixing carrier plate, which is mounted at a rear of the letterbox; • a closure element, which is assembled with an attached brush strip assembly with a 90-degree configuration of a fixing carrier plate, and positioned above the open letterbox; and • three possible fixing positions for the front-mounted letter plate.

[0044] Fig. 12(a) - A side sectional view of the attachment assembly, which is shown in Fig. 11(b), with the attached front-mounted letter plate and the inserted mail item.

[0045] Fig. 12(b) - A side sectional view of the embodiment of the attachment assembly, which is shown in Fig. 12 (a), with a mail item retained in the open-top mail receptacle.

[0046] Fig. 12(c) - A side sectional view of the attachment assembly, which is shown in Fig. 12(b) with a mail item bypassing the retained mail item and the opening at a top region of the mail receptacle.

[0047] Fig. 13 - A side sectional view of the attachment assembly, which is shown in Fig. 12(b), with the closure element position where it substantially covers and shuts the letterbox. Detailed Description

[0048] The invention relates to a security and airflow-limiting modular attachment assembly configured for mounting at a rear side of a letterbox formed through a structure, such as a door or wall, for the delivery of mail items, with the letterbox width substantially horizontal.

[0049] The attachment assembly comprises a security module and airflow-limiting modules configured to cooperate with the security module, together with fixing elements for securing the assembly to a rear face of the letterbox.

[0050] The attachment assembly is configured to provide prevention of unauthorised access— including resistance to fishing, tampering, and arson—while simultaneously limiting uncontrolled airflow, smoke propagation, draughts, and environmental ingress, without impeding normal mail delivery.

[0051] The security module may take the form of a letterbox security cowl or an open-top mail receptacle.

[0052] The letterbox security cowl is configured to receive mail items inserted downwards with the assistance of gravity toward an opening formed at a lower region of its body.

[0053] In certain embodiments the extending downward front wall of the security cowl is formed by a flap of a rear-mounted letter plate, and it has a limiter configured to restrict the extent of the flap opening.

[0054] The open-top mail receptacle configured to receive and retain mail items inserted upwards against the force of gravity, and having an opening formed at an upper region of a body of the receptacle that allows access to retained mail items and optionally permits delivered mail items to pass therethrough without being retained.

[0055] The body of the security module may be firm, such that it substantially maintains its shape under normal mail insertion and handling forces, or flexibly deformable, or foldable, configured to change its shape or fold substantially flat upon collision with an external obstacle while being able to withstand forces applied through the letterbox and to recover after the end of such collision or forces.

[0056] In some embodiments the security module includes one or more of the following features: fully or partly demountable, formed by assembly of a plurality of body portions, interfacesealing modules disposed at interfaces between the body portions, and adjustable fixing means and adjustable dimensions are provided to accommodate a variety of differently sized letterboxes.

[0057] The airflow-limiting modules are configured to cooperate with the security module to limit uncontrolled passage of air, smoke, and environmental ingress through the letterbox and through the security module, while providing obstruction supplementary to that provided by the security module against unauthorised access and extraction of items through the letterbox.

[0058] The airflow-limiting modules comprise one or more brush strip assemblies configured to allow repeated mail items to pass through the letterbox and therethrough with limited obstruction, and zero or more interface-sealing modules disposed at interfaces between modules of the assembly and the letterbox and / or a rear face of the structure, and optionally at interfaces between the modules themselves.

[0059] The brush strip assemblies comprises one or more of a core channel securing a plurality of elastic filament and a channel holder configured to receive the core channel and fixed to a fixing carrier plate.

[0060] The elastic filaments of the brush strips extend substantially across an opening in the letterbox and / or security module so as to limit passage of uncontrolled air, smoke, and environmental ingress through the letterbox and the security module, while providing supplementary obstruction against unauthorised access and extraction of items through the letterbox. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0061] Each fixing carrier plate can be provided in one of 45°, 90°, or 180° configurations and located inside, outside, or partially inside and partially outside the security module, being attached to at least one of: the rear face of the structure, the letterbox, the security module, the mounting brackets, the letterbox closure element, or any combination thereof, using appropriate fixing means.

[0062] The brush strip assembly may be configured with bent portions at its ends to form side walls of the security module.

[0063] The bent portions are formed from at least one of the components of the brush strip assembly and the brush strip assembly may be flexible, configured to follow any shape or contour of the letterbox aperture.

[0064] The assembly may further include interface-sealing elements disposed at interfaces between components of the assembly and a surface of a rear face surrounding the letterbox, thereby improving sealing performance.

[0065] The modules may be provided as separate components or as sub-assemblies and may be selectively combined, replaced, or omitted in accordance with installation requirements, regulatory constraints, or desired performance characteristics.

[0066] While each module can be handled independently, the inventive effect—providing both security and airflow limitation—is only achieved when the modules are installed together and the assembly functions as a single attachable unit while permitting modular construction and installation.

[0067] In some embodiments, the security and airflow-limiting modules may be integrated into a single unit to provide a coordinated technical effect in a unified assembly.

[0068] The attachment assembly is mountable directly to the letterbox, to the rear surface of the structure with a letterbox, such as door or wall surrounding the letterbox, or to both, depending on the configuration.

[0069] Mounting may be achieved by mounting brackets, fasteners, adhesive means, or combinations thereof, as described further below.

[0070] Mounting brackets are formed of a strong and rigid material and configured to provide adjustable spacing or orientation of the security module relative to the letterbox, and to accommodate a variety of letterbox sizes. They comprise fixing elements for attachment to the security module, the rear of the letterbox, or a surrounding structure.

[0071] The attachment assembly may further comprise a letterbox closure element to further enhance security and environmental protection when the letterbox is not in use. The closure element is movable to open and close the letterbox without damaging the rear face of the structure.

[0072] The letterbox closure element is made of strong rigid material and comprises one of: a sliding plate, a pivoting plate, a spring-loaded or self-returning plate, and a mechanically equivalent movable closure element.

[0073] In some embodiments, the letterbox closure element is guided and / or retained within the spacing gap defined between the mounting brackets and the security module, or is guided and / or retained by guide features provided by the security module and / or the mounting brackets.

[0074] The spacing gap is defined between the mounting brackets and the security module dimensioned to receive and retain at least one of the letterbox closure element and the fixing carrier plate.

[0075] The fixing carrier plate is located inside, outside, or partially inside and partially outside the security module, and is attached to at least one of: the rear face of the structure, the letterbox, the security module, the mounting brackets, the letterbox closure element, or any combination thereof, using appropriate fixing means.

[0076] The fixing carrier plate is retained within one or more spacing gaps defined between the security module and the mounting brackets, the security module and the rear face of the structure, the security module and the letterbox, the mounting brackets and the rear face of the structure, or the mounting brackets and the letterbox.

[0077] One or more of the components of the attachment assembly can be formed from or comprises fire-retardant, intumescent, heat-resistant, and smoke-resistant materials and / or low-smoke materials.

[0078] The attachment assembly is compatible with the letterbox having the letter plate mounted in front of, behind, or on opposite sides of the letterbox, or a sleeved letter plate formed by two letter plates disposed on opposite sides of the letterbox, and optionally connected by a sleeve extending through the letterbox aperture.

[0079] The or each letter plate includes a flap mounted on an axle adjacent to the upper or lower long side of the letterbox, the flap being configured to open outwardly or inwardly, with or without spring bias, and the letterbox further comprises zero or more airflow-limiting modules and an intumescent letterbox liner optionally disposed in the letterbox aperture. Advantages of the Invention

[0080] The assembly achieves both functional and protective advantages over existing solutions.

[0081] Enhanced security is provided in that the assembly obstructs or prevents unauthorised access and extraction of items through the letterbox.

[0082] The combination of a security module and additional obstructive features ensures a multilayered protective effect.

[0083] Optional letterbox closure elements may be provided to further enhance security and environmental protection.

[0084] Environmental protection is achieved by airflow-limiting modules cooperating with the security module to limit uncontrolled passage of air, smoke, draughts, and other environmental ingress through the letterbox.

[0085] By limiting such ingress, the assembly assists in maintaining interior temperature stability and reducing exposure to external environmental conditions.

[0086] Unimpeded and reliable mail delivery is maintained, as the assembly is configured to allow repeated insertion of substantially all regular flexible mail items through the letterbox.

[0087] Regular flexible mail items can be received and accessed without difficulty ensuring normal operation is maintained despite added security and environmental protection.

[0088] Modular integration is achieved by combining security and environmental protection functions in a single, easy-to-install modular assembly.

[0089] This modular configuration simplifies installation, maintenance, and replacement of individual components where required.

[0090] Material advantages may be realised in that one or more components may be formed from heat-resistant, smoke-resistant, and / or low-smoke materials, thereby enhancing fire safety.

[0091] Such materials provide additional protection and reduce smoke propagation in the event of a fire.

[0092] Where foldable or deformable materials are used, the components are capable of absorbing impacts and reducing the risk of damage to adjacent structures, such as a door or wall that might otherwise occur through collision with a rigidly configured security module.

[0093] Versatility and adaptability are provided in that the assembly is suitable for structures of different thicknesses, as the assembly is fixed only at the rear face of the structure.

[0094] The assembly can be configured to suit different letterbox designs and installation scenarios.

[0095] Individual components, including airflow-limiting modules and the security cowl, may be adjusted, replaced, or reconfigured as required.

[0096] Improved safety and compliance are achieved by reducing the risk of draught-related discomfort and contamination from outside air.

[0097] The assembly provides a simple practical solution for improving compartmentation in buildings comprising flats, and for enhancing protection of fire escape routes.

[0098] By limiting airflow and smoke passage, the assembly may assist in meeting applicable regulatory, fire safety, or building performance standards. Industrial Applicability

[0099] The invention is industrially applicable and may be manufactured, assembled, installed, and used in the building, construction, security, and property-fitting industries. In particular, the attachment assembly is suitable for use with letterboxes formed through doors, walls, panels, and other structural elements in residential, commercial, and institutional buildings.

[0100] The attachment assembly may be produced using conventional manufacturing processes and materials and may be retrofitted to existing letterboxes or incorporated during initial construction or refurbishment. The modular configuration allows the attachment assembly to be adapted to different letterbox sizes, formats, and installation constraints. Detailed Description of the Drawings

[0101] The invention will now be described with reference to illustrative embodiments. With many possible embodiments of the proposed invention, only a few specific ones will now be described solely by way of examples with reference to the accompanying drawings (as in Fig. 1-13).

[0102] Fig. 1(b) shows a side sectional view of an embodiment of an attachment assembly for the rear of a letterbox, featuring the letterbox security cowl 1 mounted on a rear face 7 of a structure 8 having a letterbox 9 formed through the structure 8 and including a sleeved letter plate 10.

[0103] The assembly comprises the letterbox security cowl 1 described with reference to Fig. 1(a).

[0104] The attachment assembly further comprises an embodiment of an airflow-limiting module configured to cooperate with the letterbox security cowl 1 comprised of a brush strip assembly with a 90-degree configuration of a fixing carrier plate 11, which is located inside the letterbox security cowl 1 and fixed to the face 7 of the structure 8.

[0105] The attachment assembly further comprises an embodiment of an interface-sealing module comprised of a sealing strip 12, which is disposed at the interfaces of the letterbox security cowl 1 with the rear face 7 of a structure 8.

[0106] The brush strip assembly with a 90-degree configuration of a fixing carrier plate 11 comprises a core channel 13 securing a plurality of elastic filaments 14.

[0107] The brush strip assembly further comprises a channel holder 15 configured to receive the core channel 13 and fixed to a fixing carrier plate 11.

[0108] The attachment assembly is mounted at the rear of the letterbox 9 as a single, easy-to-install modular assembly that combines security and environmental protection.

[0109] The letterbox security cowl 1 is fixed to the rear face 7 using fixing elements, for example screws, in the fixing holes 6.

[0110] The fixing carrier plate 11 is fixed to the rear face 7 using fixing elements, for example screws or a strong adhesive.

[0111] This simplifies installation, maintenance, and potential replacement of modules and components that can be adjusted or replaced as needed.

[0112] The plurality of elastic filaments 14 extend substantially across the entire opening 2. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0113] The attachment assembly effectively obstructs or prevents unauthorised access and extraction of items through the letterbox 9 and limits air flow, smoke flow, and environmental ingress through the letterbox 9.

[0114] Most regular mail items are flexible and can be repeatedly delivered by inserting through the letterbox 9 and the plurality of elastic filaments 14 without difficulty and the need for folding, ensuring normal operation is maintained despite added security and environmental protection.

[0115] Letterbox draught excluder of the sleeved letter plate 10 comprises a combination of sprung flaps 16 and twin brush strips with filaments 17 for a dual-action seal.

[0116] The attachment assembly for the rear of the letterbox 9 obstructs or prevents unauthorised access through the letterbox and provides supplementary to the letterbox security cowl 1 obstruction against unauthorised access and extraction of items through the letterbox.

[0117] This effect is in addition to the function of the sleeved letter plate 10 with flaps 16 and filaments 17 of the letterbox draught excluder, ensuring a multi-layered protective effect.

[0118] By limiting airflow and smoke passage, the attachment assembly helps to maintain interior temperature stability, limits exposure to outdoor elements and may assist in meeting regulatory or building safety standards.

[0119] This reduces risk of draft-related discomfort or contamination from outside air.

[0120] It provides additional fire safety and reduces smoke propagation in the event of a fire.

[0121] Components may be formed from heat-resistant, smoke-resistant, and / or low-smoke materials, thereby enhancing fire safety.

[0122] The effectiveness of the letterbox draught excluder is compromised when flaps 16 are kept open and filaments 17 are deflected by the inserted mail items or an object 18, which was lodged within the letterbox 9 when it was only partly inserted or prevented by the security cowl 1 from passing through.

[0123] In this case, the attachment assembly continues to effectively obstruct or prevent unauthorised access through the letterbox and limit air flow, smoke flow, and environmental ingress through the letterbox 9.

[0124] In use, the attachment assembly operates in accordance with the advantages described here and in the section “Advantages of the Invention”.

[0125] Fig. 2(a) shows a rear perspective view of an embodiment of a security module comprised of a letterbox security cowl 19 configured to receive mail items inserted downward toward an opening 20.

[0126] The body of the letterbox security cowl 19 is of a firm configuration.

[0127] The body comprises an opening 20 formed at a lower region of the body.

[0128] The body further comprises a front wall 21 extending downward.

[0129] The body further comprises side walls 22.

[0130] The body further comprises fixing flanges 23 folded inward.

[0131] The body further comprises fixing holes 24 and 25 provided in the fixing flanges 23 for receiving fixing elements, for example screws or nails, for attachment to a rear face of a structure.

[0132] Fig. 2(b) shows a sectional view of an embodiment of an attachment assembly for the rear of a letterbox, featuring the letterbox security cowl 19 mounted on a rear face 26 of a structure 27 having a letterbox 28 formed through the structure 27 and including a front-mounted letter plate 29.

[0133] The attachment assembly comprises the letterbox security cowl 19 described with reference to Fig. 2(a).

[0134] The attachment assembly further comprises an airflow-limiting module configured to cooperate with the letterbox security cowl 19, comprised of a brush strip assembly with a 90-degree configuration of a fixing carrier plate 30 located inside the letterbox security cowl 19 and fixed to the rear face 26 of the structure 27.

[0135] The attachment assembly further comprises an interface-sealing module comprised of a sealing strip 31 disposed at interfaces between the letterbox security cowl 19, the fixing carrier plate 30, and the rear face 26 of the structure 27.

[0136] The brush strip assembly comprises a core channel 32 securing a plurality of elastic filaments 33.

[0137] The brush strip assembly further comprises a channel holder 34 configured to receive the core channel 32 and fixed to the fixing carrier plate 30.

[0138] The attachment assembly is mounted at the rear of the letterbox 28 as a modular unit.

[0139] End regions of the fixing carrier plate 30 are positioned on the inwardly folded fixing flanges 23, and the fixing carrier plate 30 and the letterbox security cowl 19 are jointly fixed to the rear face 26 by fixing elements, such as screws 35, received in fixing holes 24.

[0140] The letterbox security cowl 19 is further secured to the rear face 26 by fixing elements, such as screws 36, received in fixing holes 25.

[0141] The plurality of elastic filaments 33 extends substantially across the entire opening 20. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0142] This mounting arrangement differs from that described with reference to Fig. 1(b) in that the fixing flanges 23 are folded inward and cooperate directly with the fixing carrier plate 30, while achieving the same functional cooperation between the security module, airflow-limiting module, and interface-sealing module.

[0143] Also, the difference is in that the sealing strip 31 is disposed at interface between the fixing carrier plate 30 and the rear face 26 of the structure 27.

[0144] The front-mounted letter plate 29 comprises a sprung flap 37 configured to limit airflow when in a closed position.

[0145] The assembly remains effective when sprung flap 37 is held open by inserted mail items or by an object 38 lodged within the letterbox 28 and prevented from passing through by the letterbox security cowl 19, and continues to operate in the same manner as described with reference to Fig. 1(b).

[0146] In use, the modular attachment assembly operates in accordance with the advantages described with reference to Fig. 1(b) and in the section “Advantages of the Invention”.

[0147] Fig. 3 shows a side sectional view of an embodiment of an attachment assembly for the rear of a letterbox featuring a security module comprised of a letterbox security cowl 39 mounted on a rear face 40 of a structure 41 having a letterbox 42 formed through the structure 41 and including a sleeved letter plate 43.

[0148] The attachment assembly comprises the letterbox security cowl 39 fixed to the rear face 40 by fixing elements received in fixing holes provided in flanges.

[0149] An airflow-limiting module is configured to cooperate with the letterbox security cowl 39 and comprised of a brush strip assembly having a 90-degree configuration of a fixing carrier plate 45 located inside the letterbox security cowl 39.

[0150] An interface-sealing module is comprised of a sealing strip 46, which is disposed at the interface between the letterbox security cowl 39 and the rear face 40 of a structure 41.

[0151] The letterbox security cowl 39 is configured to receive mail items inserted downward toward an opening 44 formed at a lower region of the body.

[0152] The body of the letterbox security cowl 39 is of a firm configuration.

[0153] The body of the letterbox security cowl 39 comprises the opening 44 formed at the lower region of the body.

[0154] The body of the letterbox security cowl 39 further comprises a front wall 50 extending downward.

[0155] The body of the letterbox security cowl 39 further comprises side walls (not shown).

[0156] The body of the letterbox security cowl 39 further comprises fixing flanges (not shown).

[0157] The body of the letterbox security cowl 39 further comprises fixing holes (not shown), which are provided in the fixing flanges for receiving fixing elements for attachment to the rear face 40.

[0158] The brush strip assembly comprises a core channel 47 securing a plurality of elastic filaments 48.

[0159] The brush strip assembly further comprises a channel holder 49 configured to receive the core channel 47 and fixed to the fixing carrier plate 45, which is fixed to an internal rear face of the extending downward front wall 50 by using fixing elements, such as a strong adhesive.

[0160] The plurality of elastic filaments 48 extends substantially across the entire opening 44. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0161] This mounting arrangement differs from that described with reference to Fig. 1(b) in that the fixing carrier plate 45 is fixed to an internal rear face of the extending downward front wall 50, while achieving the same functional cooperation between the security module, airflow-limiting module, and interface-sealing module.

[0162] Letterbox draught excluder in the sleeved letter plate 43 comprises a combination of sprung flaps 51 and twin brush strips with filaments 52 for a dual-action seal.

[0163] The attachment assembly remains effective when flaps 51 and filaments 52 are deflected by inserted mail items or by an object 53 lodged within the letterbox 42 and continues to operate in the same manner as described with reference to Fig. 1(b).

[0164] In use, the modular attachment assembly operates in accordance with the advantages described with reference to Fig. 1(b) and in the section “Advantages of the Invention”.

[0165] Fig. 4 shows a side sectional view of an embodiment of an attachment assembly for the rear of a letterbox featuring the security cowl 50 mounted on the rear face 40 of the structure 41 having the letterbox 42 formed through the structure 41 and including a front-mounted letter plate 54.

[0166] The attachment assembly comprises an airflow-limiting module configured to cooperate with the letterbox security cowl 50 comprised of a brush strip assembly with a 90-degree configuration of a fixing carrier plate 45 located inside the security cowl 39;

[0167] The attachment assembly further comprises a brush strip assembly with a 45-degree configuration of a fixing carrier plate 55 located outside the letterbox security cowl 50; and

[0168] The attachment assembly further comprises an interface-sealing module comprised of a sealing strip 46 disposed at the interface between the security cowl 50 and the rear face 40.

[0169] The brush strip assembly with a 45-degree configuration of a fixing carrier plate 55 comprises a core channel 56 securing a plurality of elastic filaments 57.

[0170] The brush strip assembly with a 45-degree configuration of a fixing carrier plate 55 further comprises a channel holder 58 configured to receive the core channel 56 and fixed to the fixing carrier plate 55.

[0171] The fixing carrier plate 55 is fixed to the rear face 40 by using fixing elements, such as screws 59.

[0172] The pluralities of elastic filaments 48 and 57 extend substantially across the entire opening 44.

[0173] This mounting arrangement differs from that described with reference to Fig. 3 in that the assembly comprises the brush strip assembly with a 45-degree configuration of a fixing carrier plate 55, which is located outside the letterbox security cowl 50, and fixed to the rear face 40 for providing enhanced security and airflow-limiting.

[0174] Also, the difference is in that the front-mounted letter plate 54 comprises a flap 60 with or without a spring bias, with axle positioned adjacent the upper long side of the letterbox 42 and openable outwardly. When closed the flap 60 provides limiting of air flow through the letterbox 42.

[0175] The attachment assembly remains effective when flap 60 is open by inserted mail items or by an object 61 lodged within the letterbox 4, and continues to operate in the same manner as described with reference to Fig. 1(b).

[0176] In use, the attachment assembly operates in accordance with the advantages described with reference to Fig. 1(b) and in the section “Advantages of the Invention”, including providing multi-layered obstruction and environmental protection, while allowing repeated insertion of flexible mail items.

[0177] Fig. 5(a) shows a rear perspective view of an embodiment of a security module comprised of a letterbox security cowl 62 configured to receive mail items inserted downward toward an opening 63.

[0178] The body of the security cowl 62 has adjustable width dimension to enable matching a variety of letterboxes with different width. It is formed by assembly of portions 64 and 65 joint together by fixing elements, such as screws 66 or a strong adhesive.

[0179] The body of the letterbox security cowl 62 is of a firm configuration.

[0180] The body of the letterbox security cowl 62 comprises an opening 63 formed at a lower region of the body.

[0181] The body of the letterbox security cowl 62 further comprises a front wall 66 extending downward.

[0182] The body of the letterbox security cowl 62 further comprises side walls 67.

[0183] The body of the letterbox security cowl 62 further comprises fixing flanges 68 folded inward.

[0184] The body of the letterbox security cowl 62 further comprises fixing holes 69 and 70 provided in the fixing flanges 68 for receiving fixing elements, such as screws or nails, for attachment to a rear face of a structure.

[0185] Fig. 5(b) shows a side sectional view of an embodiment of an attachment assembly for the rear of a letterbox featuring the letterbox security cowl 62 mounted on a rear face 71 of a structure 72 having a letterbox 73, which is formed through the structure 72 and includes a sleeved letter plate 74.

[0186] The attachment assembly comprises the letterbox security cowl 62 described with reference to Fig. 5(a);

[0187] The attachment assembly further comprises an airflow-limiting module configured to cooperate with the letterbox security cowl 62, which is comprised of a brush strip assembly having a 45-degree configuration of a fixing carrier plate 75 located partly inside and partly outside the letterbox security cowl 62 and fixed to the rear face 71 of the structure 72.

[0188] The attachment assembly further comprises an interface-sealing module comprised of a sealing strip 76 disposed at interfaces between the letterbox security cowl 62, the fixing carrier plate 75, and the rear face 71 of the structure 72.

[0189] The brush strip assembly comprises a core channel 77 securing a plurality of elastic filaments 78. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0190] The brush strip assembly further comprises a channel holder 79 configured to receive the core channel 77 and fixed to the fixing carrier plate 75.

[0191] The ends of the fixing carrier plate 75 are placed on the fixing flanges 68, and the fixing carrier plate 75 and the security cowl 62 are jointly fixed to the rear face 71 by screws 80 placed in the fixing holes 69. The security cowl 62 is further fixed to the rear face 71 by using screws 81 in the fixing holes 70.

[0192] The plurality of elastic filaments 78 extends substantially across the entire opening 63. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0193] This mounting arrangement differs from that described with reference to Fig. 2(b) in that the body of the security cowl 62 has adjustable width dimension to enable matching a variety of letterboxes with different width. It is formed by assembly of portions 64 and 65 joint together by fixing elements.

[0194] Also, the assembly comprises the brush strip assembly with a 45-degree configuration of a fixing carrier plate 75, which is located outside the letterbox security cowl 62 fixed to the rear face 71.

[0195] Letterbox draught excluder of the sleeved letter plate 74 comprises a combination of sprung flaps 82 and twin brush strips with filaments 83 for a dual-action seal.

[0196] The attachment assembly remains effective when flaps 82 are open by inserted mail items or by an object 84 lodged within the letterbox 4 and continues to operate in the same manner as described with reference to Fig. 1(b).

[0197] In use, the modular attachment assembly operates in accordance with the advantages described here and in the section “Advantages of the Invention”.

[0198] Fig. 6(a) shows a side sectional view of an embodiment of an attachment assembly for the rear of a letterbox, featuring a letterbox security cowl mounted on a rear face 87 of a structure 88 having a letterbox 94, which is formed through the structure 88 and includes a sleeved letter plate 91.

[0199] The body of the letterbox security cowl is foldable. The body comprises a front wall 90 formed by the flap of the rear-mounted portion of the sleeved letter plate 91.

[0200] The body further comprises an opening 89 formed at the lower region of the body and configured to receive mail items inserted downward toward the opening 89.

[0201] The body further comprises a limiter 92 configured to limit an extent of the flap opening.

[0202] The body further comprises security and environmental-protection side walls 93 disposed on both sides of the front wall 90.

[0203] The attachment assembly further comprises an airflow-limiting module configured to cooperate with the letterbox security cowl.

[0204] The airflow-limiting module is comprised of a brush strip assembly with a 45-degree configuration of a fixing carrier plate 85 located outside the letterbox security cowl and fixed to the rear face 87 of the structure 88 using screws 99.

[0205] The brush strip assembly further comprises a core channel 97 securing a plurality of elastic filaments 98.

[0206] The brush strip assembly further comprises a channel holder 96 configured to receive the core channel 97 and fixed to the fixing carrier plate 85.

[0207] The plurality of elastic filaments 98 extend substantially across the entire opening 89 in the letterbox security cowl. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0208] The attachment assembly further comprises an interface-sealing module comprised of an interface-sealing strip 86 disposed at the interface between the fixing carrier plate 85 and a rear face 87 of a structure 88.

[0209] This mounting arrangement differs from that described with reference to Fig. 5(b) in that the body of the letterbox security cowl is foldable and the side walls 93 are provided by the bent portions at the ends of the brush strip assembly.

[0210] For mail deliveries the flap 90 is opened by the collision with the inserted mail items while being able to withstand forces applied through the letterbox 94 and to recover its closed position after the end of such collision or forces.

[0211] In the event that there is an item 95 lodged in a letterbox 94, the flap 90 may stay open due to the pressure from the item. However, being foldable, it can return to the closed or partially closed position by folding substantially flat upon collision with an external obstacle, such as the adjusting wall of a property.

[0212] Use of foldable or deformable materials helps absorb impacts and protect adjacent structures, such as a door or wall, from damage caused by collision with a rigid security module.

[0213] The attachment assembly provides limiting of air flow, smoke flow, and environmental ingress through the letterbox 94 in addition to the limiting, which is provided by a draught excluder in the letterbox 94, which is comprised of the flaps of the sleeved letter plate 91 and twin brush strips with filaments 101.

[0214] The assembly remains effective when flaps of the letterbox 91are open by inserted mail items or by an object 95 lodged within the letterbox 94 and continues to operate in the same manner as described with reference to Fig. 1(b).

[0215] In use, the modular attachment assembly operates in accordance with the advantages described with reference to Fig. 1(b) and in the section “Advantages of the Invention”, including providing multi-layered obstruction and environmental protection, while allowing repeated insertion of flexible mail items and helping to absorb impacts and protect adjacent structures from damage caused by collision with a rigid security module.

[0216] Fig. 6(b) shows a front elevation of the rear face 87 of the structure 88 with the brush strip assembly attached by the screws 99 that are placed in the fixing holes 100, which are provided in the fixing carrier plate 85. Also shown is the plurality of elastic filaments 98, which extend substantially across the entire opening 89 in the letterbox security cowl 90.

[0217] The side walls 93 are shown provided by the bent portions 93 at the ends of the brush strip assembly, comprising the bent portions of the: • fixing carrier plate 85; • channel holder 96 and • core channel 97 with the plurality of elastic filaments 98.

[0218] The side walls 93 provide barriers that limit airflow, smoke flow, and environmental ingress and obstruction to unauthorised access and extraction of items through the letterbox.

[0219] Fig. 7 shows a front elevation of a rear face 102 of a structure having a letterbox 103 formed through the structure, with an interface-sealing module comprised of an interface-sealing compression gasket 104 positioned on the rear face 102 of a structure.

[0220] Fig. 8 (a) - shows the front elevation of the rear face 102 of the structure, which is shown in Fig. 7, with two mounting brackets 105 placed over the interface-sealing compression gasket 104 (not shown).

[0221] The mounting brackets 105 are formed of a strong and rigid material, such as thick metal sheet, and comprise fixing holes 106 for attaching to the rear face 102 by fixing elements, for example, screws. They further comprise clinch studs 107, which are the fixing elements allowing fixing a letterbox security cowl to the mounting brackets 105.

[0222] The mounting brackets 105 are configured to provide adjustable spacing and orientation of a letterbox security cowl relative to the letterbox 103 and to accommodate a variety of letterbox sizes.

[0223] Also shown is an airflow-limiting module configured to cooperate with a letterbox security cowl, comprised of a brush strip assembly.

[0224] The brush strip assembly comprises: • a fixing carrier plate 108 with a 90-degree configuration; and • a channel holder 109 with a core channel and a plurality of elastic filaments 110.

[0225] By using a strong adhesive or other fixing elements, such as screws, the fixing carrier plate 108 is attached to a letterbox closure element 111, which is placed on the mounting brackets 105 and positioned beneath the open letterbox 103.

[0226] Fig. 8(b) shows a side sectional view of the letterbox closure element 111 with the attached brush strip assembly with the 90-degree configuration of the fixing carrier plate 108, channel holder 109, and ore channel 112 with the plurality of elastic filaments 110.

[0227] Also shown an interface-sealing element, which is comprised of a sealing strip 113 disposed at the interface between the closure element 111 and the rear face 102 of a structure 114.

[0228] Fig. 9 shows a side sectional view of the structure 114 having the letterbox 103, with the embodiment of an attachment assembly for the rear of a letterbox mounted on the rear face 102.

[0229] The assembly comprises: • a letterbox security cowl 115 configured to receive mail items inserted downward toward an opening 116, which is formed at a lower region of the body; • mounting brackets 105; • letterbox closure element 111; • the brush strip assembly with the 90-degree fixing configuration of the fixing carrier plate 108 located inside the letterbox security cowl 115 ; and • the interface-sealing modules

[0230] The interface-sealing modules are comprised of: • the interface-sealing gasket 104; • the interface-sealing strip 113 and • an interface-sealing strip 117.

[0231] The body of the letterbox security cowl 115 is of firm configuration and comprises: • a front wall 118 extending downward; • the opening 116 formed at the lower region of the body; and • two side walls (not shown).

[0232] The mounting brackets 105 are attached to the rear face 102 by the screws 119.

[0233] The letterbox security cowl 115 is fixed to the mounting brackets 105 by using the clinch studs 107, which are provided in the mounting brackets 105, and wing nuts 120.

[0234] The letterbox closure element 111 is made of a rigid and strong material, such as a metal sheet, and it is movable allowing opening and closing the letterbox 103 without damaging the surface of the rear face 102. Such movement to change the position of the closure element is simply done by reaching the closure element through the opening 116.

[0235] The letterbox closure element 111 is shown in the position underneath the letterbox 103 where it is not closing the letterbox.

[0236] The brush strip assembly comprises: • the core channel 112 securing the plurality of elastic filaments 110; • the channel holder 109 configured to receive the core channel 112 and fixed to the fixing carrier plate 108 with the 90-degree fixing configuration.

[0237] The interface-sealing compression gasket 104 is disposed at the interfaces between the mounting brackets 105 and the rear face 102 of the structure 114.

[0238] The interface-sealing strip 117 is disposed at the interface between the mounting brackets 105 and the letterbox security cowl 115.

[0239] The interface-sealing strip 113 is attached to the letterbox closure element 111 in order to seal the interface between the closure element 111 and the rear face 102.

[0240] The fixing carrier plate 108 is attached to the letterbox closure element 111.

[0241] The plurality of the elastic filaments 110 extend substantially across the entire opening 116. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0242] Also shown are three possible fixing positions for a front-mounted letter plate with a flap being configured to open outwardly and inwardly with or without a spring bias: • a letter plate 121 with a flap 122 mounted on an axle positioned adjacent the upper long side of the letterbox 103 and openable outwardly; • a letter plate 123 with a flap 124 mounted on an axle positioned adjacent the upper long side of the letterbox 103 and openable inwardly; • a letter plate 125 with a flap 126 mounted on an axle positioned adjacent the lower long side of the letterbox 103 and openable outwardly.

[0243] The main difference of the mounting arrangement from that described with reference to Fig. 1-6 is in that the assembly comprises mounting brackets 105 and letterbox closure element 111.

[0244] In use, the modular attachment assembly operates in accordance with the advantages described with reference to Fig. 1(b) and in the section “Advantages of the Invention”, including providing multi-layered obstruction and environmental protection, while allowing repeated insertion of flexible mail items.

[0245] Fig. 10 shows the side sectional view of the embodiment of the security and airflow-limiting modular attachment assembly for the rear of a letterbox, which is shown in Fig. 9, featuring the front-mounted letter plate 121, and the letterbox closure element 111, which was moved up and taken the position that substantially covers and shuts the letterbox 103. Such movement to change the position of the closure element is simply done by reaching the closure element through the opening 116.

[0246] Fig. 11(a) shows a perspective view of an embodiment of a security module comprised of an open-top mail receptacle 127 configured to receive and retain mail items inserted upward against the force of gravity.

[0247] The body of the open-top mail receptacle 127 is of a firm configuration, has no front wall, and comprises: • a rear wall 128; • side walls 129; • fixing flanges 130 with fixing holes 131; and • an opening 132, which is formed at an upper region of the body to allow retrieval of retained mail items without difficulty and, optionally, allowing inserted mail items to pass therethrough without being retained.

[0248] Fig. 11(b) shows a side sectional view of an embodiment of an attachment assembly for the rear of a letterbox featuring the open-top mail receptacle 127 mounted at a rear face 133 of a structure 134 that has a letterbox 135 formed through the structure 134.

[0249] The open-top mail receptacle 127 is attached to two mounting brackets 136 by clinch studs 137 with wing nuts 138, which are used in the fixing holes 131 (not shown) provided in the fixing flanges 130.

[0250] The mounting brackets 136 are attached to the rear face 133 by screws 139.

[0251] The interface-sealing modules are composed of: • a sealing strip 140 disposed at the interface between the mounting brackets 136 and the rear face 133 of the structure 134; • a sealing strip 141 disposed at the interfaces between the open-top mail receptacle 127 and the mounting brackets 136; and • a sealing strip 142 disposed at the interface between the closure element 143 and the rear face 133.

[0252] A closure element 143 with an attached brush strip assembly having a 90-degree configuration of a fixing carrier plate 144 is shown positioned inside the open-top mail receptacle 127 above the letterbox 135, and the letterbox is open.

[0253] The airflow-limiting modules are configured to cooperate with the open-top mail receptacle 127 to limit passage of air, smoke, and environmental ingress through the letterbox 135 and the open-top mail receptacle 127, while providing obstruction supplementary to that provided by the open-top mail receptacle 127 against unauthorised access and extraction of items through the letterbox.

[0254] The airflow-limiting modules comprise: • a brush strip assembly with a 90-degree configuration of a fixing carrier plate 144, and • a brush strip assembly with a 180-degree configuration a fixing carrier plate 146.

[0255] The brush strip assembly with a 90-degree configuration of a fixing carrier plate 144 comprises: • a core channel securing a plurality of elastic filaments 145; and • a channel holder configured to receive the core channel and fixed to the fixing carrier plate 144.

[0256] The plurality of elastic filaments 145 extend substantially across the entire opening 132. The elastic filaments are biased into contact with a mating surface without excessive deformation.

[0257] The brush strip assembly comprising a fixing carrier plate 146 with a 180-degree configuration comprises: • a core channel 148 securing a plurality of elastic filaments 149; and • a channel holder 147 configured to receive the core channel 148 and fixed to the fixing carrier plate 146.

[0258] The fixing carrier plate 146 is fixed to the open-top mail receptacle 127, either firmly or with the option to adjust prior to fixation, in a position where the plurality of elastic filaments 149 extend substantially across the entire opening of the letterbox 135, and the unattached ends of the filaments 149 overlap the top long side of the letterbox 135.

[0259] In other possible embodiments the plurality of elastic filaments 149 is attached at the rear of a letterbox by a core channel 148 or a channel holder 147.

[0260] Both brush strip assemblies, are configured to allow repeated mail items to pass unimpeded through the letterbox 135 and therethrough, to limit airflow, smoke flow, and environmental ingress through the letterbox 135 and the opening 132, and to provide supplementary to the open-top mail receptacle 127 obstruction against unauthorised access and extraction of items through the letterbox.

[0261] Also shown are three possible fixing positions for a front-mounted letter plate with a flap being configured to open outwardly and inwardly with or without a spring bias: • a letter plate 150 with a flap 151 mounted on an axle positioned adjacent the upper long side of the letterbox 135 and openable outwardly; • a letter plate 152 with a flap 153 mounted on an axle positioned adjacent the upper long side of the letterbox 135 and openable inwardly; • a letter plate with a flap 154 with a flap 155 mounted on an axle positioned adjacent the lower long side of the letterbox 135 and openable outwardly.

[0262] Fig. 12(a) shows a side sectional view of the security and airflow-limiting modular attachment assembly for the rear of the letterbox, which is shown in Fig. 11(b), with the attached front-mounted letter plate 150 with the flap 151, and a mail item 156 inserted within the letterbox 135 and the open-top mail receptacle 127.

[0263] The closure element 143 with an attached brush strip assembly having a 90-degree configuration of the fixing carrier plate 144 is shown positioned inside the open-top mail receptacle 127 above the letterbox 135, and the letterbox is open.

[0264] The brush strip assembly with the 180-degree configuration of the fixing carrier plate 146 is configured to: • limit airflow, smokeflow, and environmental influences through the letterbox 135 and the opening 132; • co-operate with the open-top mail receptacle 127 to create three consecutive openings through which substantially all regular flexible mail items can be repeatedly inserted and pass unimpeded; and • provide supplementary to the open-top mail receptacle 127 obstruction against unauthorised access and extraction of items through the letterbox.

[0265] Unauthorised access includes insertion of non-mail objects and liquids.

[0266] The first of the consecutive openings through which inserted mail items can pass unimpeded is created as static in the upper portion of the letterbox 135 with its height formed between the top long side of the letterbox 135 and the channel holder 147.

[0267] The second opening is created as dynamic behind the first opening with its short sides formed by the side walls 129 of the open-top mail receptacle 127, while the height is developed dynamically between the top long side of the letterbox 135 and the plurality of elastic filaments 149 when they are deflected by deposited mail items.

[0268] The deflected elastic filaments 149 are configured to propel deposited mail items upwards against the force of gravity and facilitate their introduction through the third opening.

[0269] The third opening is created as static behind the second opening with its short sides formed by the side walls 129 of the open-top mail receptacle 127 and its height formed between the top long side of the letterbox 135 and the rear wall 128, or the opening 132 at a top region of the mail receptacle 127.

[0270] Most regular flexible mail items can be received and accessed without difficulty, ensuring normal operation is maintained despite added security and environmental protection.

[0271] The assembly remains effective when flap 151 is open and the plurality of elastic filaments 149 is deflected by inserted mail item 156 or an object lodged within the letterbox 135 and the open-top mail receptacle 127.

[0272] In use, the modular attachment assembly operates in accordance with the advantages described with reference to Fig. 1(b) and in the section “Advantages of the Invention”, including providing multi-layered obstruction and environmental protection, while allowing repeated insertion of flexible mail items.

[0273] Fig. 12(b) shows a side sectional view of the security and airflow-limiting modular attachment assembly for the rear of the letterbox, which is shown in Fig. 12 (a), with a mail item 157 retained in the open-top mail receptacle 127 and protruding through the opening 132.

[0274] The closure element 143 with an attached brush strip assembly having a 90-degree configuration of a fixing carrier plate 144 is shown positioned inside the open-top mail receptacle 127 above the letterbox 135, and the letterbox is open.

[0275] The security and airflow-limiting modular attachment assembly for the rear of the letterbox continues to effectively limit air flow, smoke flow, and environmental ingress through the opening 132 and letterbox 135.

[0276] It also provides obstruction supplementary to that provided by the open-top mail receptacle 127 against unauthorised access and extraction of items through the letterbox.

[0277] Fig. 12(c) shows a side sectional view of the security and airflow-limiting modular attachment assembly for the rear of the letterbox, which is shown in Fig. 12 (b) with mail items 158 and 159 bypassing the retained mail item 157 and the opening 132 allowing for repeated insertion of substantially all regular flexible mail items.

[0278] Fig. 13 shows a side sectional view of the security and airflow-limiting modular attachment assembly for the rear of the letterbox, which is shown in Fig. 12 (b), and the plurality of elastic filaments 149 shown deflected inside the letterbox 135 in order to clear the way for moving the closure element 143 down to take position where it substantially covers and shuts the letterbox 135. Such deflection is simply done by reaching elastic filaments 149 through the opening 132.

[0279] Similarly reached through the opening 132 the closure element 143 was moved to close the letterbox 135 while carrying the attached brush strip assembly having a 90-degree configuration of the fixing carrier plate 144.

[0280] This move of the closure element 143 is allowed by slightly releasing the wing nuts 138 without using any tools. After the wing nuts 138 are tightened again, the closure element 143 is retained in the new position where it substantially covers and shuts the letterbox 135.

[0281] The surface of the rear face 133 is not harmed when the closure element 143 is moved because it slides along the surfaces of the mounting brackets 136 and does not come into contact with the rear face 133. Likewise, the rear face 133 is not harmed by the sealing strip 142.

[0282] When the closure element 143 shuts the letterbox 135 the air flow, smoke flow, and environmental ingress through the letterbox 135 is substantially limited or blocked.

[0283] If an attempt is made to introduce any volume of liquid through the letterbox 135 into any of the embodiments shown in Fig. 11(b) -Fig. 13, it will cause it to be forced out by gravity rather than remain inside.

[0284] The optimum materials and dimensional relationships for the parts of the invention as described and illustrated in the drawings of the embodiments are deemed obvious and apparent to those skilled in the art and are intended to be encompassed by the present invention.

Claims

ms1. A security and airflow-limiting modular attachment assembly for the rear of a letterbox formed through a structure, including a door or wall, for the delivery of mail items, the assembly comprising:(a) a security module configured to obstruct or prevent unauthorised access through the letterbox while allowing delivery of mail items therethrough, the security module comprising one of:(i) a letterbox security cowl configured to receive mail items inserted downwards with the assistance of gravity through an opening formed at a lower region of a body of the cowl; or(ii) an open-top mail receptacle configured to receive and retain mail items inserted upwards against the force of gravity through an opening formed at an upper region of a body of the receptacle, the opening further allowing access to retained mail items and optionally permitting delivered mail items to pass therethrough without being retained;(b) one or more airflow-limiting modules configured to cooperate with the security module, the airflowlimiting modules comprising:(i) one or more brush strip assemblies, each comprising a plurality of elastic filaments, configured to allow repeated passage of mail items with limited obstruction with limited obstruction and to return automatically to a substantially closed configuration after each such passage, thereby passively restoring airflow restriction without manual intervention; and(ii) zero or more interface-sealing modules disposed at interfaces between modules of the assembly and the letterbox and / or a rear face of the structure, and optionally at interfaces between the modules themselves; and (c) fixing elements for mounting the assembly at the rear of the letterbox;wherein the airflow-limiting modules cooperate with the security module to form, in combination, a compound barrier that:(A) limits uncontrolled passage of air, smoke, and environmental ingress through both the security module and the letterbox when the letterbox is unobstructed by mail items;(B) maintains said limitation against passage of air, smoke, and environmental ingress when mail items or other objects are lodged within or partially through the letterbox, keeping one or more flaps of the letter plate open and / or deflecting the brush strip filaments;(C) resists introduction of hazards and flammable materials through the letterbox so as to reduce the risk of letterbox arson and consequential blocking of an escape route through the structure; and(D) provides supplementary obstruction against unauthorised extraction of items and against unauthorised access through the letterbox;and wherein the assembly is modular such that the security module and the airflow-limiting modules are discrete, interchangeable components capable of cooperative assembly at the rear of the letterbox independently of the letter plate;and wherein, where the letterbox is formed through a door, a body of the security module is either:(P) of firm configuration, such that the body substantially maintains its shape under normal mail insertion and handling forces; or(Q) flexibly deformable or foldable, configured to change shape or fold substantially flat upon collision with an external obstacle — including an adjacent wall or structure encountered upon opening of the door — while being capable of withstanding forces applied through the letterbox during normal use and of recovering its operative shape upon cessation of such collision or forces;and wherein, in either case, the assembly is configured to function as the compound barrier when the door is in its closed position and the security module is in its operative, non-deformed shape.

2. The attachment assembly of claim 1, wherein the brush strip assembly comprises one or more of:(a) a core channel securing a plurality of elastic filaments; or(b) a channel holder configured to receive the core channel and fixed to a fixing carrier plate; wherein the elastic filaments:(i) extend substantially across an opening of the letterbox and / or the security module; and(ii) are biased into contact with a mating surface without excessive deformation;such that the elastic filaments cooperate to limit uncontrolled passage of air, smoke, and other environmental ingress through the letterbox.

3. The attachment assembly of claim 2, wherein the or each fixing carrier plate is provided in one or more of 45°, 90°, or 180° configurations.

4. The attachment assembly of claim 1, further comprising a movable letterbox closure element configured for opening and closing the letterbox without damaging the rear face of the structure.

5. The attachment assembly of claim 1, wherein the security module is mountable by one or more mounting brackets configured to provide adjustable spacing or orientation of the security module relative to the letterbox, and to accommodate a variety of letterbox sizes; the mounting brackets being formed of a strong and rigid material and comprising fixing elements for attachment to the security module, the rear of the letterbox, or a surrounding structure.

6. The attachment assembly of claim 5, wherein a spacing gap is defined between the mounting brackets and the security module, the spacing gap being dimensioned to receive and retain at least one of:(a) a letterbox closure element configured for opening and closing the letterbox without damaging the rear face of the structure; or(b) a fixing carrier plate associated with a brush strip assembly.

7. The attachment assembly of claim 4, wherein the letterbox closure element is made of strong rigid material and comprises one of:(a) a sliding plate;(b) a pivoting plate;(c) a spring-loaded or self-returning plate; or(d) a mechanically equivalent movable closure element.

8. The attachment assembly of claim 2, wherein the fixing carrier plate is located inside, outside, or partially inside and partially outside the security module, and is attached to at least one of:(a) the rear face of the structure;(b) the letterbox;(c) the security module;(d) one or more mounting brackets, where present;(e) a letterbox closure element, where present; or(f) any combination thereof;using fixing means appropriate to the materials and surfaces involved.

9. The attachment assembly of claim 5, wherein the interface-sealing modules are additionally disposed at:(a) the interface between the rear face of the structure and the mounting brackets;(b) the interface between the letterbox and the mounting brackets;(c) the interface between the security module and the mounting brackets;(d) the interface between the rear face of the structure and a fixing carrier plate, where present;(e) the interface between the rear face of the structure and a letterbox closure element, where present; or(f) any combination thereof.

10. The attachment assembly of any of claims 1, 4, or 5, wherein the interface-sealing modules comprise at least one of a compressible gasket or a sealing strip.

11. The attachment assembly of claim 2, wherein one or more of:(a) the elastic filaments;(b) the core channel and / or the fixing carrier plate;(c) the security module;(d) one or more mounting brackets, where present;(e) a letterbox closure element, where present;(f) fixing elements;comprises fire-retardant, intumescent, heat- and smoke-resistant and / or low-smoke materials.

12. The attachment assembly of claim 6, wherein the letterbox closure element is guided and / or retained within the spacing gap defined between the mounting brackets and the security module, or is guided and / or retained by guide features provided by the security module and / or the mounting brackets.

13. The attachment assembly of claim 2, wherein the fixing carrier plate is retained within one or more spacing gaps defined between:(a) the security module and one or more mounting brackets, where present;(b) the security module and the rear face of the structure;(c) the security module and the letterbox;(d) one or more mounting brackets and the rear face of the structure, where mounting brackets are present; or (e) one or more mounting brackets and the letterbox, where mounting brackets are present.

14. The attachment assembly of claim 1, wherein the letterbox security cowl comprises a body including:(a) a front wall extending downward;(b) an opening at a lower region of the body, configured to receive mail items inserted toward the opening;(c) fixing flanges comprising fixing means for attachment to the letterbox and / or the rear face of the structure; and(d) zero or more side walls.

15. The attachment assembly of claim 14, wherein:(a) the front wall extending downward is formed by a flap of a rear-mounted letter plate, the flap having a limited opening;(b) the body further comprises a limiter configured to restrict the extent of opening of the flap; and(c) the side walls comprise zero or more security and / or environmental-protection features disposed on one or both sides of the flap.

16. The attachment assembly of claim 1, wherein:(a) where the body of the security module is of firm configuration, it is formed from or comprises one or more of: a rigid polymer, a metal, a composite material, or a fire-retardant rigid material capable of substantially maintaining its shape under normal mail insertion and handling forces; or(b) where the body of the security module is flexibly deformable or foldable, it comprises one or more of: a living hinge, a flexible polymer, a foldable composite, or a collapsible frame structure, configured to return to its operative shape upon cessation of deforming forces.

17. The attachment assembly of claim 2, wherein the brush strip assembly has bent end portions configured to form side walls of the security module that limit airflow, smoke, and environmental ingress and provide supplementary obstruction against unauthorised access through the side regions of the security module;the bent end portions being formed from at least one of the components of the brush strip assembly comprising a core channel, a channel holder, or a fixing carrier plate;and wherein the brush strip assembly is constructed as rigid or as flexible, the flexible construction being configured to follow any shape or contour of the letterbox aperture.

18. The attachment assembly of claim 2, wherein the airflow-limiting modules comprise a brush strip assembly located at the rear of the letterbox, the brush strip assembly comprising one of:(a) a core wire securing a plurality of elastic filaments extending substantially across an opening of the letterbox; or(b) a fixing carrier plate with a channel holder and a core wire received in the channel holder, the core wire securing a plurality of elastic filaments extending substantially across an opening of the letterbox;the brush strip assembly being configured to:• limit uncontrolled passage of air, smoke, and environmental ingress through the letterbox; and• provide supplementary obstruction against unauthorised access through the letterbox, and against unauthorised extraction of items through the letterbox;wherein free ends of the elastic filaments, in a relaxed state, overlap an upper long side of the letterbox;wherein the brush strip assembly is fixed to one or more of: the open-top mail receptacle of the security module, the letterbox, or the rear face of the structure, by one or more of the fixing carrier plate, where present, or the core wire, and is adjustable in position prior to final fixation;wherein the brush strip assembly is configured to permit, without substantial obstruction, the repeated passage of regular flexible mail items capable of passing through the letterbox aperture, the deflected elastic filaments being configured to propel deposited mail items upward against the force of gravity to facilitate their introduction into the open-top mail receptacle of the security module;wherein the open-top mail receptacle of the security module is attached firmly or adjustably behind the letterbox and has either an aperture in its front wall encompassing the letterbox aperture or no front wall; wherein the brush strip assembly is configured to cooperate with the open-top mail receptacle of the security module to define three consecutive openings, comprising:(i) a first opening, static, created in an upper portion of the letterbox, having a height defined between the upper long side of the letterbox and one of: the core wire; or the channel holder, where present;(ii) a second opening, dynamic, formed behind the first opening, having a height defined dynamically between the upper long side of the letterbox and the elastic filaments when deflected by deposited mail items;the first and second of the consecutive openings having short sides formed by one of:• (A) the short sides of the letterbox aperture; or• (B) one or more mounting brackets fixed or adjustably positioned behind the letterbox in the vicinity of the short sides of the letterbox aperture; or• (C) the side walls of the open-top mail receptacle;(iii) a third opening, static, formed behind the second opening, having:• a height defined between the upper long side of the letterbox and one of: the rear wall of the open-top mail receptacle; or the opening at an upper region of the open-top mail receptacle; and• short sides formed by the side walls of the open-top mail receptacle;through which consecutive openings substantially all regular flexible mail items that fit the width of the letterbox aperture can pass in sequence without substantial obstruction, while normal mail delivery is maintained despite the added security and environmental protection.

19. The attachment assembly of claim 1, wherein the security module includes one or more of the following features:(a) fully or partly demountable;(b) formed by assembly of a plurality of body portions;(c) interface-sealing modules disposed at interfaces between the body portions; or(d) adjustable fixing means and adjustable dimensions provided to accommodate a variety of differently sized letterboxes.

20. The attachment assembly of claim 1, wherein the letterbox comprises:(a) a single letter plate mounted in front of the letterbox, the letter plate optionally being connected to, or comprising, a sleeve fully or partly extending through the letterbox aperture;(b) letter plates mounted on opposite sides of the letterbox; or(c) a sleeved letter plate formed by two letter plates disposed on opposite sides of the letterbox and connected by a sleeve extending through the letterbox aperture;wherein the or each letter plate includes a flap mounted on an axle adjacent to an upper or lower long side of the letterbox, the flap being configured to open outwardly or inwardly, with or without spring bias;and wherein the letterbox or a letter plate further comprises one or more airflow-limiting modules and / or an intumescent material.w

Images