The present invention relates to an anchoring dowel intended for being introduced in a supporting material for going therethrough and comprising an axial through-hole body for receiving a member for fastening a part to be fastened to the supporting material, the body comprising an abutment collar for abutment against the supporting material.

Nowadays, the quality of the air in particular in houses is a topical issue, all the more sensitive as people spend a large part of the time in such indoor spaces.

It is known that the pollution of the indoor air could be issued from different sources, such as cleaning products, building and furnishing materials, pesticides, ground coatings, etc.

The Applicant was faced with the issue of the air pollution linked to the presence of fastening members and, in particular, metal anchoring dowels fastened to supporting materials, and through which air can circulate between the concealed space, behind the supporting material, and the indoor living room, before the material.

Such supporting materials could be simple individual walls or plaster plates for covering walls, or be hollow, for instance, as foam partitions comprising two external plaster plates spaced one from the other by a cardboard-coated foam material or the like, for room separating purposes, or composite panels with associated plaster plate and fibrous or plastic material, for thermal insulation purposes for the house. Obviously, the supporting materials in question could also encompass bricks and perpends and other similar products, as long as dowels go through the latter generating therein an air circulation between the concealed space and the indoor space .

The Applicant noticed, after specific blower-door tests, that anchoring dowels fastened to the wall of such supporting materials result in parasite air leaks between the closed space located behind the concealed side of the supporting material, and the living room. The air leaks go through the dowels circulating between the internal wall of the cylindrical body of the dowel and the stem of the fastening member mounted in the axial hole of the body.

Such air leaks issued from the anchoring dowel are furthermore enhanced and amplified by mechanical systems of houses , resulting, because of the number of dowels introduced in the supporting materials of a house, an obviously minor, although real, air circulation. The latter is further stale as a result of the particles or fibres of the materials (plasters, insulating items, etc.) and other moulds developing in such more or less wet closed spaces, contributing to damage the quality of the air in houses, while being furthermore noxious for people's health .

The present invention aims at overcoming this particular problem and provides a simple and drastic solution to this parasite circulation of polluted air.

Tothisend, the anchoring dowel of the previously defined type is remarkable in that it comprises sealing means arranged in the axial through-hole of the body, so as to obstruct the space between the internal wall of the body and the fastening member, the sealing means extending outwardly of the dowel, on the collar side.

Thus, using such intermediary sealing means creating an interface between the body of the dowel and the threaded stem of the fastening member, the air circulation from the closed space of the supportingmaterial and the internal space of the house no longer occurs, preventing the polluted and stale air of closed spaces, behind the supporting materials, from diffusing in the inhabitable space. The air leaks at this level are therefore cancelled, contributing not only to improve the quality of the air, but also to reduce thermal losses. Such dowels could be considered as being air sealed. Furthermore, the sealing means outside the dowel , on the collar side, further improve the sealing, may avoid a thermal bridge and reduce the losses due to convection and conduction.

For instance, the sealing means could obstruct a whole cross-section of the axial hole of the body, before the fastening member is received.

Alternatively, the sealing means partially obstruct a cross-section of the axial hole of the body so as to leave a passage with a diameter lower than the diameter of the stem of the fastening member adapted for cooperating with the body.

In particular, the sealing means could comprise a sealing material arranged in the axial hole of the body, along the internal wall thereof, or they could also have the shape of a sealing insert introduced in the axial hole of the body.

In a preferred embodiment of the dowel, the cylindrical body has a material-drilling end and, at the other end, the abutment collar against the material with cooperation means with a screwing tool, a thread being provided on the external wall of said body, its internal wall comprising the sealing means.

In another example of the dowel, the cylindrical body comprises radially deformable expansion legs, inside of which sealing means are arranged, and ends with a tapped end for screwing the fastening member and, at the other end, with the abutment collar against the material.

Thus, this invention applies to the different types of dowels being present on the market.

The sealing means are preferably made in an elastomer, for instance of the silicone type for its elasticity and long life qualities, and which can be moulded over the collar of the dowel.

This invention also relates to a set of anchoring dowels such as previously defined.

Advantageously, it comprises a linking traverse joining the dowels and connected to the sealing means provided in the respective axial holes of the dowels.

The sealing means of the dowels and the linking traverse form a unitary block.

This invention will be better understood from the following description of embodiments of an anchoring dowel, according to this invention, with reference to the appended drawing, in which:

- Fig. 1 shows a sectional axial view of an embodiment of the sealed dowel of the invention, being introduced in a supporting material, before the fastening member is mounted,

- Fig. 2 is a view similar to the previous one, after the fastening member has been mounted in the dowel,

- Fig. 3 illustrates a set of anchoring dowels according to this invention, and

- Figs. 4 and 5 show, in a sectional axial view, another embodiment of the sealed dowel of the invention, respectively before and after the fastening member is mounted . With reference to Fig. 1, the anchoring dowel 1 with an axis 2 is mounted in a supporting material 3 such as a plaster plate.

In this embodiment, the anchoring dowel 1 is metallic and self-drilling. To this end, it comprises a cylindrical body 4, the internal wall 5 of which delimits an axial through-hole 6 for a fastening member 7, whereas on the external wall 8 of the body a large anchoring thread 9 is arranged. The body 4 ends with a distal drilling end 10, and, at the other proximal end 11, there is arranged an abutment collar 11 with so-called footprint cooperation means 12 with a not shown screwing tool for the dowel 1.

Fastening such a dowel in the plaster plate 3 is well-known as such. After screwing, it can be seen, in the shown example, that the drilling end 10 has drilled the hole 3.3 in the plate 3 and emerges from the concealed side 3.1 thereof with apart of the cylindrical body, whereas the collar 11 at the other end is brought in contact with the visible side 3.2 of the plate. The thread 9 provides the anchoring of the dowel 1 in the plate.

Advantageously, the anchoring dowel 1 comprises in the axial through-hole 6, sealing means 14 which, in this example, fully obstruct the cross-section of the axial hole further extending on substantially the whole length of the hole of the body.

Such sealing means 14 are aimed at preventing, after the dowel is positioned in the supporting material and the fastening member is screwed, the circulation of air containing particles, moulds and other polluting elements from the closed space EC behind the concealed side 3.1 of the plate 3 toward the inhabited space EH before the visible side 3.2. In order to achieve this, the sealing means 14 comprise a sealing material bulk 14.1, such as an elastomer imparting elasticity and posture in the course of time.

For instance, silicones could be selected as an elastomer. Other examples of sealing material could also be acceptable.

As shown on Fig. 2, it can be seen that the threaded stem 15 of the fastening member 7, such as a screw, screws directly in the sealing material bulk 14.1 so as to definitely obstruct the space 16 between the internal wall 5 of the cylindrical body and the threaded stem 15. The sealing material bulk 14.1, as the screw 7 is passing by, is strongly compressed so that any leak of stale air between the closed space EC and the inhabited space EH is cancelled. The dowel 1 thereby ensures the sealing. The fastening member 7 on the stem of which a part (or support) to be fastened 17 has been mounted, is screwed until the head 13 thereof pressesthe part against thevisibleside 3.2 of the plaster plate 3, as shown on Fig. 2.

It is to be noticed that, with this type of dowel, the large thread 9 anchored in the plaster plate 3 prevents an air stream from circulating therethrough, from the closed space to the inhabited space.

If the sealing means 14 arranged in the cylindrical body 4 obstruct , in the illustrated embodiment , the cross-section of the axial through-hole of the dowel, an axial passage could, according to another embodiment, be left so as to only partially obstruct the axial hole. In such a case, the diameter of such an axial through-passage should be lower than the diameter of the threaded stem of the fastening member, so that the latter comes perfectly in contact with the sealing material so as to compress it and thereby ensure the desired sealing (such as described hereinunder referring to Figs. 4 and 5 with another type of dowel ) .

Such elastomeric material sealing means 14 included in the cylindrical body of the dowels 1 may, in some circumstances, be used for acting as a link between a group of several dowels to be joined, including when selling such sealed dowels.

Indeed, as shown on Fig. 3, the sealing means extend up to outside the dowels 1, on their collar side 11 over which they are overmoulded, and are j oined therebetween via linking bridges 19, so as to form a linking traverse 20 gathering, in this example, five sealed anchoring dowels 1. A unitary block is thereby obtained, that it a monobloc assembly comprising the traverse and the sealing means.

The ring, out of elastomeric material, over moulded on the collar of a dowel, when the work to be secured is pressed against the dowel and the supporting material, improves further the sealing.

Alternatively, such sealing means 14 could also be contemplated in anchoring dowels of the radial expansion type, as shown on Figs. 4 and 5.

It should be noted that, in the case of a metallic dowel, the ring out of elastomeric material overmoulded on its collar, enables to avoiding the thermal bridge which, in winter time, usually occurs, when the internal temperature is higher than the external temperature, calories escaping to the outside, frigories coming in. Moreover, if the work to be fastened is also metallic, it constitutes a radiator which still increases the thermal losses . Thanks to the elastomeric material, not only the losses due to convection are reduced while isolating the internal side from outside, but the losses due to conduction are also reduced, thanks to the ring out of elastomeric material which isolates the work to be fastened from the dowel .

Fig. 4 shows such a dowel 1.1 being mounted in the plaster plate 3 of the supporting material going therethrough, before being expanded. Preliminarily to mounting the dowel, the hole 3.3 was drilled. Such a dowel

I.1 comprises a cylindrical body 4.1 delimiting an axial hole 6.1 and having side legs 4.2 radially expanding through folding . When it is mounted, the radially expanding legs 4.2 are located behind the concealed side 3.1 of the plate and theyendinadistalendwitha threaded hole 10.1 for screwing the fastening member 7.1. At the opposite, the proximal end of the body comprises a transversal abutment collar

II.1 being anchored in the visible side 3.2 of the plaster plate.

Advantageously, the sealing means 14 are provided in the axial through-hole 6.1 of the body, inside the legs 4.2. The means 14 are made in the same material as in the previous embodiment of the dowel.

The sealing means 14 have the shape of a preformed insert 14.2 being maintained between the legs, inside them, and have an axial through-hole or passage 21 for mounting the screw 7.1. This hole 21 facilitates guiding and introducing the threaded stem 15.1 of the screw in the sealing insert 14.2, as its end is flat, whereas that of the screw 7, in the previous embodiment of the dowel, ends with a tip.

It is to be noticed that the sealing insert 14.2 has an ovoidal shape allowing it to conform to the best to the internal volume delimited by the deformable legs, and to remain within the axis 2 of the dowel 1.1 and, therefore, to receive the threaded stem 15.1. After the legs 4.2 have been deformed through being radially expanded, with the help of an appropriate tool, the threaded stem 15.1 of the fastening screw 7.1 of a part 17 is introduced in the dowel. Thanks to the axial hole 21 of the insert 14.2 and to the intrinsic flexibility or elasticity of the material making up the latter, the threaded stem 15.1 penetrates in the insert, goes through it while deforming it, so that it fully obstructs the annular space 16.1 existing between the stem 15.1 and the deformed cylindrical body 4.1. The stem afterwards engages in the tapped hole 10.1 until the part 17 is fastened against the supporting material 3. The head 18.1 of the screw axially immobilizes the part against the plate.

It should be furthermore noticed that, asaresult of the legs being folded and becoming closer with the cylindrical body becoming shorter and before the screw is mounted, the sealing insert 14.2 has become deformed as well, contributing to ensure the sealing of the axial hole 6.1 with the internal wall 9.1 of the cylindrical body 4.1. Moreover, the insert is then firmly maintained in position, facilitating the introduction of the threaded stem 15.1 of the screw 7.1 in the through-hole 21 of the insert.

In the end, after screwing, the sealing means 14 being compressed between the dowel 1.1 and the screw 7.1 prevent any stale air from circulating therethrough between the two spaces EC and EH.