Letterbox

Abstract

 A letterbox comprises an outer section (2) having an outer flap (22), an inner section (3) having an inner flap (23), as well as a telescopic shaft comprising a first shaft section (4) and a second shaft section (5). The first shaft section belongs to the outer section, and the second shaft section belongs to the inner section. The telescopic shaft allows the creation of an inclined shaft sloping downwards from the outer section to the inner section. The outer section (2) and the inner section (3) are sufficiently large in area to cover a straight opening (7) to be made through the mounting base (8), allowing the inclined telescopic shaft to be fitted so that it forms an integral inclined shaft, while simultaneously forming mounting points facing the mounting base for the sections (2,3). Expanding fire insulation strips (6) or band is provided in the straight opening (7) outside the telescopic shaft to block the telescopic shaft by compression in case of fire.

Description

Field of technology

[0001] The present invention relates to letterboxes. In particular, the invention relates to letterboxes for mounting on doors. However, the mounting base can also be a wall structure.

Prior art

[0002] It is known that a letterbox can be installed in a straight or an inclined machined opening through a door. A straight opening is easier to make in comparison to an inclined one. On the other hand, a straight opening is more cumbersome in use as it makes it more difficult to insert mail inside the door, particularly if there is another door blocking the passage on the inside of the door. An inclined machined opening is more difficult to make but more comfortable to use as it makes it easier to insert mail to the other side of the door.

[0003] The use of telescopic shafts in letterboxes is also known, as is presented in the patent publication FI 47838. The shaft of the letterbox in question comprises a telescopic structure adapted to and supported by the edges of the machined opening. The two flaps of the letterbox in question are linked to each other so that both will open simultaneously when one of the flaps is opened. The inner flap contains expanding fire insulation material that will fill the inclined shaft in case of fire. The expanding insulation material might push the flaps of the letterbox open, creating an air opening and a route for the fire to spread to the other side of the door.

[0004] Fire safety regulations have also become stricter, and this must be taken into account in letterboxes. Most current models of letterboxes do not fulfil the new stricter requirements.

Short description of invention

[0005] The objective of the invention is to reduce the disadvantages of prior art solutions referred to in the above. The objective will be achieved by the means described in the claims. The idea of the invention is to create a letterbox that comprises an inclined shaft and is suitable for installation in a straight machined opening. Furthermore, it must be possible to create embodiments of the letterbox compliant with criteria (such as fire safety regulations) required at any given time (for example, country-specific criteria).

[0006] A letterbox according to the invention comprises an outer section 2 having an outer flap 22, an inner section 3 having an inner flap 23, as well as a telescopic shaft comprising a first shaft section 4 and a second shaft section 5. The first shaft section belongs to the outer section, and the second shaft section belongs to the inner section. The telescopic shaft allows the creation of an inclined shaft sloping downwards from the outer section to the inner section. The outer section 2 and the inner section 3 are sufficiently large in area to cover a straight opening to be made through the mounting base, allowing the inclined telescopic shaft to be fitted so that it forms an integral inclined shaft, while simultaneously forming mounting points facing the mounting base for the sections 2, 3.

[0007] When the door is thick, the height of the straight machined opening is also high compared to the height of a straight opening made through a thin door. The areas of the inner and outer section must be able to cover all possible sizes of straight machined openings. Thus the areas of the inner and outer section must be at least large enough to cover a straight machined opening made in a door that is as thick as possible. The maximum thickness of the door depends on the maximum length of the telescopic shaft.

[0008] In order to make the letterbox compliant with the fire safety regulations required at any given time, expanding fire insulation strips 6 are fitted or can be fitted on the surfaces of the outer section 2 and the inner section 3 that face the straight mounting opening when installed. Furthermore, fire insulation can be improved by using fire insulation band that is fitted or can be fitted on the surfaces of the outer and/or inner section facing the surface of the mounting base upon installation and that forms a closed loop.

List of figures

[0009] In the following, the invention is described in more detail by reference to the enclosed drawings, where

Figure 1 illustrates an installation example of an embodiment of the invention viewed from the side,

Figure 2 illustrates an example of the parts of a letterbox according to the invention,

Figure 3 illustrates an example of the parts of a letterbox according to the invention from another angle,

Figure 4 illustrates an example of the outer section of a letterbox according to the invention,

Figure 5 illustrates an example of an embodiment of the invention, and

Figure 6 shows an enlarged view of a detail in Figure 5.

Description of the invention

[0010] Figure 1 illustrates an example of a letterbox 1 according to the invention installed in a straight opening 7. The letterbox is viewed from the side so that the mounting base has been cut out at the position of the machined opening. The opening is in a door 8 having an appropriate thickness so that the telescopic shaft of the letterbox is able to extend through it. In the example of Figure 1, the telescopic shaft is not at its maximum length; that is, the door 8 could be thicker. The height of the straight opening 7 machined in the door must be sufficient in order to fit the inclined telescopic shaft. The shaft slopes downwards from the outside to the inside.

[0011] The letterbox 1 comprises an outer section 2 to be fitted on the outside of the door and an inner section 3 to be fitted on the inside of the door. The outer section comprises a first shaft section 4 of the telescopic shaft. Correspondingly, the inner section comprises a second shaft section 5 of the telescopic shaft. From a usage viewpoint, it is better that the measurement round the first shaft section 4 is smaller than that of the second shaft section 5 as this means that the first shaft section fits inside the second shaft section, making it easier to insert mail into the letterbox. Should the structure be the opposite, the edge of the second shaft section 5 having a smaller measurement would create a threshold against the direction of insertion in the shaft.

[0012] In addition to covering different sizes of straight openings possible, the outer section 2 and inner section 3 provide mounting points through which the letterbox can be fastened to the inner and outer surface of the door. Fastening a letterbox according to the invention onto the mounting base is easier than in many prior art solutions in which the letterbox is fastened onto the walls of the machined opening.

[0013] An embodiment of the invention also includes the expanding fire insulation strips 6 illustrated in Figure 1. As illustrated, the strips are fitted or can be fitted on the surfaces of the outer section 2 and inner section 3 of the letterbox that face the straight mounting opening when installed. A triangular shape is a good alternative for the strip end profile. Other profiles, such as split ellipses, can also be used.

[0014] In place of the fire insulation strips, it is possible to use fire insulation band that is fitted or can be fitted around the second shaft section 5. However, installing the band is not as easy as installing strips.

[0015] In case of fire, the fire insulation strip 6 or band expands, compressing the telescopic shaft. Thus the expanding insulator fills the straight machined opening and blocks the telescopic shaft by compression. The expanding insulator is not allowed to flow in the inclined shaft towards the inner section 3 and push the inner flap open.

[0016] Figure 2 illustrates an example of a letterbox according to the invention with the outer section 2 and inner section 3 separated. Figure 3 illustrates the same example viewed from another angle. Sealing strip 21 is fitted or can be fitted on the surface of the inner and/or outer section that faces the mounting base upon installation. The sealing strip 21 forms a loop so that it will seal the gap between the inner/outer section and the mounting base in all directions. The purpose of this is to prevent any air flow through the gap. The sealing strip loop also serves as a thermal insulator and prevents scratching of the mounting base surface during installation of the letterbox.

[0017] The sealing strip loop can conveniently be formed of separate pieces of sealing strip. The longer sealing strips 21 A are fitted in the lengthwise direction of the letterbox, while the shorter sealing strips 21 B are fitted in the heightwise direction.

[0018] The figures also show mounting screws 26 using which the outer section 2 and inner section 3 can be fastened to the mounting base at the mounting points of the sections. Thus, at the simplest, the mounting points are holes for mounting screws or nails. To prevent attempts of vandalism, the mounting screws should preferably be unidirectional screws.

[0019] Figures 2 and 3 illustrate the structure of the outer and inner section. The outer and inner section comprise a body 27 and outer cover parts. The outer cover parts are fitted or can be fitted to the body.

[0020] The telescopic shaft sections 4, 5 are also fitted or can be fitted to the body. The outer cover parts comprise flaps 22, 24, 23, 32 and end sections 25. The material or materials of the parts can be a suitable metal or plastic, for example.

[0021] Some of the parts may be aluminium, for example, while the other parts are plastic. The telescopic shafts and the end sections could be plastic, while the body and flaps could be metal.

[0022] The opening sector of the outer flap 22 in the outer section 2 is upwards and, correspondingly, the opening sector of the inner flap 23 in the inner section 3 is downwards. The opening edges 31 of both the outer and inner flaps are bent to facilitate opening. The outer and inner flaps are held in the closed position by flap-specific springs (not shown in the figures). The springs will also return the flaps to the closed position after being opened. The opening angles of the flaps are structurally limited to a certain desired maximum. An example of this is that the outer and inner flaps have hinges designed to allow the flap to open to a certain maximum angle.

[0023] In an embodiment of the invention, the outer section 2 includes a name flap 24 separate from the outer flap 22. The name flap is located below the outer flap. A separate name flap makes it easier to create an outer flap structure that insulates air flows, sound and maybe heat as well. Correspondingly, the inner section 3 includes a separate covering flap 32.

[0024] All of the flaps can be opened so that the mounting points of the outer and inner section are uncovered and the outer and inner section can be fastened to the mounting base. The letterbox is fastened by aligning the inner and outer section in the mounting opening so that the telescopic shaft sections overlap. After this, the outer and inner section are fastened onto the surface of the mounting base, and the flaps are moved to the closed position. The outer and inner flap will move to the closed position by the force of the springs referred to in the above. Installation is finished using end sections 25 that are fastened on the sides of the outer and inner section. To prevent attempts of vandalism, the mounting screws should preferably be unidirectional screws.

[0025] Figure 4 illustrates an example of an outer section 2 of a letterbox according to the invention in which there is an insulation layer 41 on the inner surface of the outer flap 22. The insulation layer 41 covers the opening of the telescopic shaft when the flap 22 is closed. The insulation layer facilitates the prevention of air, sound and heat being conducted through the telescopic shaft. The insulation layer 41 may also be on the inner surface of the inner flap or on the inner surfaces of both the outer and the inner flap.

[0026] Figure 5 illustrates an embodiment of a letterbox according to the invention in which the sealing of the letterbox is ensured. When there is a ridge 51 surrounding the telescopic shaft opening, the inside insulator 41 on the outer flap 22 settles very tightly against the ridge when the flap is closed. Figure 6 shows an enlargement of the ridge 51.

[0027] A letterbox according to the invention combines the advantages of straight and inclined machined openings. Both installation and use are effortless. Furthermore, a letterbox according to the invention provides multiple possibilities for creating a letterbox assembly with the desired level of fire, sound and/or thermal insulation. For example, the letterbox may have the fire insulation strips 6 or fire insulation band referred to in the above. The insulation properties will further improve when, in addition to the insulation strips or band, the letterbox comprises an insulation layer 41 on the inner surface of the outer flap 22, the inner flap 23 or both flaps 22, 23, helping to cover the telescopic shaft opening. The tightness of the insulation layer on the inside of the flap can be further improved if there is a ridge 51 referred to in the above surrounding the telescopic shaft. The insulation properties can also be improved by using a name flap 24 separate from the outer flap. The sealing loops 21 referred to in the above will also improve the insulation properties. Thus a letterbox with the desired tightness can be achieved by selecting and combining the means described here. This also makes it possible to create a letterbox compliant with current fire regulations.

[0028] Also with regard to structures other than the insulating parts, a letterbox according to the invention consists of certain standard parts that allow the outer section 2 and the inner section 3 to be constructed of primarily the same parts. The body 27 of the outer and inner section, as well as the end sections, are identical assemblies. The principal dimensions of the outer and inner flap are identical. Correspondingly, the principal dimensions of the name flap and the covering flap are identical.

[0029] It is evident from the examples presented above that an embodiment of the invention can be created using a variety of different solutions. It is evident that the invention can also be implemented using embodiments not described in this text. Therefore the invention is not limited to the examples described in this text but is also applicable to many other practical applications within the scope of the inventive idea.

Claims

1. A letterbox comprising an outer section (2) having an outer flap (22), an inner section (3) having an inner flap (23) and a telescopic shaft comprising a first shaft section (4) and a second shaft section (5), the first shaft section belonging to the outer section and the second shaft section belonging to the inner section, said telescopic shaft being able to form an inclined downward sloping shaft from the outer section to the inner section, characterised in that the outer section (2) and inner section (3) are sufficiently large in area to cover a straight opening to be made through the mounting base, allowing the inclined telescopic shaft to be fitted so that it forms an integral inclined shaft, while simultaneously forming mounting points facing the mounting base for the sections (2, 3), and the letterbox comprises expanding fire insulation strips (6) in the lengthwise direction of the letterbox that are fitted or can be fitted outside the telescopic shaft on the surfaces of the outer section (2) and the inner section (3) that face the straight mounting opening when installed.

2. A letterbox according to Claim 1, characterised in that the end profile of the fire insulation strips (6) is triangular.

3. A letterbox according to Claim 1, characterised in that it comprises expanding fire insulation band that is fitted or can be fitted around the second shaft section (5), the measurement round the second shaft section (5) being larger than that round the first shaft section (4).

4. A letterbox according to Claim 1, 2 or 3, characterised in that the outer flap (22), the inner flap (23) or both comprise an insulation layer (41) on the inside that covers the telescopic shaft opening when the flap is closed.

5. A letterbox according to Claim 4, characterised in that there is a ridge (51) surrounding the telescopic shaft against which the insulator on the flap settles tightly when the flap is closed.

6. A letterbox according to any of the Claims from 1 to 5, characterised in that the outer section (2) comprises a name flap (24) that is separate from the outer flap (22) and located below it.

7. A letterbox according to any of the Claims from 1 to 6, characterised in that it comprises sealing bands (21) that are fitted or can be fitted on the surfaces of the outer and/or inner section facing the mounting base upon installation of the sections and that form a closed loop.

8. A letterbox according to any of the Claims from 1 to 7, characterised in that the outer and inner section comprise outer cover parts and a body to which the other parts are fastened or can be fastened.

9. A letterbox according to any of the Claims from 1 to 8, characterised in that it comprises springs to hold the outer and inner flaps in the closed position and return them to said position.

Drawing