EP1701084B1 - Box structure for linking between horizontal and vertical ducts of a mechanical ventilation installation of a building - Google Patents

Description

The present invention relates to a connecting box between horizontal and vertical ducts of a controlled mechanical ventilation installation of a building.

Collective or individual dwellings, private or industrial premises are generally equipped with controlled mechanical ventilation systems, commonly known as VMC installations, to ensure a minimum of air renewal, necessary for hygiene, quality air and the durability of buildings.

A VMC installation generally consists of a ventilation group, a horizontal collector system or terrace, and at least one vertical network serving the various rooms to ventilate.

The accessory for connecting a vertical duct to a horizontal duct consists of a generally cylindrical metal casing into which the vertical duct and the horizontal duct radially open. Such a box is called attic or terrace quill box (CPC or CPT) and also commonly called tee strain.

A ventilation system is sized to meet the regulatory requirements for extracted flows, acoustics and acoustic transmission between dwellings.

The network is then designed and dimensioned to ensure regulatory flows in relation to the conditions required by the acoustic regulation of construction.

With regard to the extracted flows, a calculation of the pressure drop of the various components of the installation is necessary to ensure the obtaining of regulatory flows.

With regard to acoustics, the noise transmitted in the room served is a function of the characteristics of the extractor and its operating regime, the acoustic attenuation of the network, and the characteristics of the extraction vents.

To comply with the requirements of the regulation, the following requirements must be met: the average air velocity in ducts must not exceed 6 ms ^-1 in horizontal ducts and 5 ms ^-1 in vertical ducts. These limitations correspond to the only acoustic requirements and can not take the place of sizing rule in order to obtain the extracted flows in the network. These imposed conditions are necessary but not sufficient: it is then necessary to calculate the acoustic attenuation of the various components of the installation to ensure that a prescribed sound level is achieved.

The decking box of terrace or roof has an important role in obtaining the resulting sound level and the resulting extracted flows.

A disadvantage of the wells of current manufacture is that they transmit a significant noise from the ventilation unit to the extraction vents located in the apartments, through the metal conduits.

One solution to overcome this drawback is to add in these boxes a compact piece of mineral fiber to improve the acoustic attenuation characteristics of the box. The compact piece of mineral fiber is usually glued under the lid of the box.

However, special care must be taken to avoid defibration over time and therefore a degradation of performance over time.

Another disadvantage of these boxes is that the pressure drop is very important, it is often at least equal to or greater than that of the vertical duct.

Therefore, the box has a major influence in the design of the fan and its consumption. High pressure drops have the consequence of increasing the cost of installation and use.

To avoid a loss of pressure too high, it is common practice to oversize the box to reduce its pressure drop. However, this results in an over-dimensioning of the horizontal network, and consequently a bulk and a higher hardware cost.

Another use is to replace the box with a bend, resulting in a reduction of the pressure drop, a better dimensioning of the horizontal network but the impossibility to check the vacuity of the vertical networks and thus making the installation not in conformity with the regulations .

Indeed, the box also has an important role for the maintenance of the facilities, its implementation to allow verification of the vacuity of the vertical duct. The boxes are generally equipped with a removable cover allowing periodic visits and cleaning of ducts but also, in accordance with the regulatory requirements, to ensure the protection of the waterproofing report.

The document FR 2,624,580 discloses a junction box according to the preamble of claim 1.

The present invention therefore aims to remedy these drawbacks.

The technical problem underlying the invention is the production of a connecting box between horizontal and vertical ducts of a controlled mechanical ventilation system of a building to limit its pressure losses, while ensuring attenuation. sufficient acoustics of the ventilation system and allowing maintenance and verification of the void of the vertical ducts.

To this end, the invention relates to a connecting box between horizontal and vertical ducts of a controlled mechanical ventilation installation of a building, of the type comprising a hollow body having a lower opening intended to be connected to a vertical duct, an upper opening provided with a closure lid, the side wall of the hollow body having at least one lateral opening for mounting a connecting duct with a ventilation unit, characterized in that it is equipped with deflection means removable members for directing a flow of incoming air through the lower opening or the lateral opening, to the lateral opening or the lower opening respectively, the deflection means being acoustically absorbent, and in that the deflection means comprise a curved perforated plate, whose convex face is turned towards the closure lid and covered, on its turned side towards the cover, a layer of acoustic insulating material.

Thus, during the operation of the ventilation system, the deflection means direct the flow of air entering the box towards the connecting duct with the ventilation unit, thus allowing a significant reduction in pressure losses inside. of the box and therefore a better dimensioning of the fan and a saving of consumption.

In addition, since the deflection means are also acoustically absorbing, it is possible to attenuate the incident noise and thus to obtain a regulatory sound level.

Moreover, since the deflection means are removable, a verification of the emptiness of the vertical duct is possible. From this In fact, a ventilation system equipped with this type of box complies with the regulations in force.

Advantageously, the upper edge of the perforated plate is located at the upper part of the lateral opening, and the lower edge of the perforated plate is located at the portion of the lower opening, located on the side opposite the lateral opening.

According to one embodiment of the invention, at least two perforations formed on the perforated plate have different diameters.

Advantageously, the perforations of different diameters formed on the perforated plate are distributed randomly.

According to one embodiment of the invention, the perforated plate is equipped with means for retaining the layer of insulating material.

Advantageously, the perforated plate is metallic.

According to one embodiment of the invention, the layer of acoustic insulating material is made of glass wool or rock, compressed felt, or the like.

Advantageously, the hollow body is of cylindrical general shape, of axis corresponding to that of the lower opening.

In any case the invention will be better understood with the aid of the description which follows, with reference to the indexed schematic drawing showing, by way of non-limiting example, an embodiment of this box.

Figure 1 is a very schematic view of a ventilation system equipped with the box according to the invention.

Figure 2 is a longitudinal sectional view of the box according to the invention.

Figure 3 is a top view of the box without its closure lid.

Figure 4 is a perspective view of the deflection means according to the invention.

The figure 1 very schematically represents a controlled mechanical ventilation installation of a multi-storey building operating in extraction. The floors of each floor are designated by the reference 2, and the floor of the roof terrace is designated by the reference 3.

All air extraction vents 4, mounted in the rooms of the various rooms to be ventilated, are associated with a metal column vertical 5, which is connected via a terrace branch box 6 to a horizontal pipe 7 in communication with the ventilation group 8 located on the terrace.

As shown more particularly to Figures 2 and 3 , the casing 6 comprises a cylindrical metal body 9, of vertical axis, in which are provided a lower air inlet opening 10, of the same axis as the casing 6, in communication with the vertical duct 5, an upper opening 12 closed by a cover 13 and a radial opening 14 of air outlet, equipped with a sleeve 15 for connection to the horizontal duct 7.

The casing 6 is also equipped with removable deflection means 16, 17.

As represented in figure 4 , the removable deflection means comprise a perforated metal plate bent 16 of generally rectangular shape, covered on its convex face facing the cover 13, a layer of acoustic insulating material 17 of dimensions substantially identical to those of the metal plate 16.

The perforated plate 16 is equipped with two retaining tabs 18 formed on its longitudinal edges, substantially at its upper edge 19, and a return 20 formed on its lower edge 21. The retaining tabs 18 and the return 20 are turned inwardly on the side of the acoustic insulating material layer 17 and are intended to hold the latter on the perforated plate 16.

The physical characteristics such as the nature, the thickness, the density, etc., of the acoustic insulating material are chosen in order to optimize the desired acoustic attenuation, for example attenuation of the low or medium frequencies. According to various embodiments of the invention, the layer of acoustic insulating material 17 may consist of, for example, glass wool or rock, compressed felt, or the like.

As shown in figure 2 , the metal plate 16 is bent, its convex face being turned towards the cover 13, the upper edge 19 of the metal plate 16 is located at the upper part of the radial opening 14 of air outlet and of complementary shape that of the side wall of the body 9 while the lower edge 21 of the perforated plate 16 bears against the lower wall of the box 6, at the portion of the lower air inlet opening 10, on the opposite side to the air outlet opening 14.

Thus, during the operation of the ventilation unit 8, the perforated plate 16 and the acoustic insulating material 17 make it possible to direct the flow of air entering through the lower air intake opening 10 towards the radial opening 14 of the air inlet. air outlet connected to the horizontal duct 7 connected to the ventilation unit 8.

The perforated plate 16 delimits with the cover 13 and the body 9 a volume of air more or less filled with acoustic insulating material 17. This is a Helmholtz resonator that absorbs a part of the incident sound waves and therefore of mitigate the incident noise.

The resonance frequency of a Helmholtz resonator depends on the density of the acoustic insulating material, the surface and the depth of the holes allowing air circulation in the resonator and the height of the air volume.

During a circulation of air in the Helmholtz resonator constituted by the perforated plate 16, the acoustic insulating material 17, the cover 13 and the body 9, part of the sound waves is absorbed by the acoustic insulating material 17 and a other part is by the surface of the perforations 22 formed on the perforated plate 16.

However, the acoustic insulating material 17 can only absorb a well-defined frequency range and the same is true for each perforation 22 formed on the metal plate 16.

Thus, if each perforation 22 has the same diameter and the same surface, only a restricted range of frequencies can be absorbed.

One solution for extending the efficiency range of the resonator consists in a random distribution of perforations 22 of different diameters on the plate 16. In fact, each perforation 22 uses a portion of the air trapped between the plate 16, the body 9 and the cover 13, and forms a small Helmholtz resonator operating for a different frequency range, thus allowing a better attenuation of the incident noise.

It is therefore possible to modify the dimensions of the perforations 22 in order to optimize the desired acoustic attenuation as a function of a spectrum.

As is apparent from the foregoing, the invention provides a great improvement to the existing technique, providing a connecting box between horizontal and vertical ventilation ducts, simple structure, and having excellent aeraulic properties and insulation acoustic.

It goes without saying that the invention is not limited to an embodiment, described above by way of example, but that it encompasses all the variants of embodiment. Thus, in particular, the hollow body 9 could be, for example, generally parallelepipedal in shape and that the controlled mechanical ventilation installation could operate in insufflation, in this case the flow of air enters through the radial opening 14 and is directed by the deflection means 16, 17 to the lower opening 10, without departing from the scope of the invention.

Claims (8)

1. A box structure (6) for linking between horizontal and vertical ducts of a mechanical ventilation installation of a building, of the type comprising a hollow body (9) including a lower opening (10) designed to be connected to a vertical duct (5), an upper opening (12) equipped with a closing lid (13), the side wall of the hollow body (9) including at least one side opening (14) designed for mounting a linking duct (7) with a ventilation group (8), characterized in that it is equipped with removable deflection means (16, 17) making it possible to orient an air flow entering through the lower opening (10) or side opening (14), respectively toward the side opening (14) or the lower opening (10), the deflection means (16, 17) being acoustically absorbing, and in that the deflection means (16, 17) comprise a curved perforated plate (16), the convex face of which is turned toward the closing lid (13) and covered, on the face thereof turned toward the lid (13), with a layer of acoustically insulating material (17).
2. The box structure (6) according to claim 1, characterized in that the upper edge (19) of the perforated plate (16) is situated at the upper part of the side opening (14), and the lower edge (21) of the perforated plate (16) is situated at the part of the lower opening (10), situated on the side opposite the side opening (14).
3. The box structure (6) according to one of claims 1 and 2, characterized in that at least two perforations (22) formed on the perforated plate (16) have different diameters.
4. The box structure (6) according to claim 3, characterized in that the perforations (22) of different diameters formed on the perforated plate (16) are distributed randomly.
5. The box structure (6) according to one of claims 1 to 4, characterized in that the perforated plate (16) is equipped with retaining means (18, 20) for retaining the layer of insulating material (17).
6. The box structure (6) according to one of claims 1 to 5, characterized in that the perforated plate (16) is made from metal.
7. The box structure (6) according to one of claims 1 to 6, characterized in that the layer of acoustic insulating material (17) is made up of glass or rock wool, compressed felt, or equivalent means.
8. The box structure (6) according to one of claims 1 to 7, characterized in that the hollow body (9) has a generally cylindrical shape, with an axis corresponding to that of the lower opening (10).

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