FR2889617A1 - SOUNDPROOFING LAYER AND SOUND COMPRESSOR INCORPORATING SAME - Google Patents

Abstract

This porous heavy layer (2) soundproofing characterized in that it comprises fibers entangled with polymeric particles and hot melt binder fibers amalgamating the polymer particles and fibers.The invention also relates to a complex consisting of a porous layer heavy on which is superimposed a fibrous layer spring (3).

Description

The present invention relates to a soundproofing layer and a complex

integrating this layer.

  Every motor vehicle produces noises in a wide range of frequencies. These noises have multiple origins; noises can be created by the engine, the aerodynamic noise of the friction of the air on the vehicle, the noise of the rolling of the vehicle on the road.

  It is important, therefore, to protect the passenger compartment of a vehicle, and therefore the people therein, from the noise generated by the vehicle during its operation.

  To cope with this acoustic requirement, soundproofing complexes are used which are positioned in relation to the different noise foci.

  In the passenger compartment, sound-absorbing complexes cover the floor of the passenger compartment and the apron wall that separates the passenger compartment from the engine compartment.

  In the engine compartment, soundproofing complexes encapsulate the engine compartment.

  Outside the vehicle, the acoustic treatment mainly concerns the inner wing protectors.

  Depending on the sources of noise to be treated, these soundproofing complexes can act according to two modes of action.

  These soundproofing complexes can, on the one hand, act to achieve acoustic insulation, that is to say, to prevent noise from entering the volume concerned. The acoustic treatment by insulation is mainly used for the soundproofing of the cabin and, in some applications under hood (soundproofing of water box) and external (inner wing protector).

  These soundproofing complexes can, on the other hand, act by acoustic absorption, that is to say by absorption and dissipation of the sounds that propagate from different sources (engine, gearbox, wheel, etc.). . Generally, the main noise sources treated by sound absorption are those located under the bonnet.

  In order to cope with these soundproofing requirements in terms of insulation and absorption, it is possible to use monolayer or multilayer complexes which fulfill the functions of isolation and / or absorption.

  A conventional acoustic insulation treatment, obtained by a soundproofing complex, such as a cabin carpet intended to cover the floor of a vehicle or an apron intended to cover the sheet which separates the engine from the passenger compartment, combines a couple says spring-mass. This type of complex, in general, combines: - a layer of a material with low resistance to the passage of air; called "spring" which may be a polyurethane foam or possibly a fibrous material, and - a layer of a material called "heavy mass". Traditionally, heavy mass is impermeable to air and water. It consists of a thermoplastic polymer (PE, PP, EVA, PVC) or cross-linked polymer (EPDM, rubber and derivatives) and a high proportion of mineral fillers in order to provide the mass effect necessary for acoustic insulation. This type of system provides no acoustic absorption because of the tightness provided by the heavy polymer mass.

  The acoustic performance of a complex thus defined is a function of the density and the thickness of the spring layer and the grammage of the "heavy mass" layer.

  In the case of a cockpit type cockpit soundproofing, a layer of textile appearance can complete the complex.

  In some applications, the soundproofing products must also provide mechanical properties adapted to the application. Thus, in the cabin interior, the complexes that cover the floor of the passenger compartment must also have mechanical properties in terms of lift, resistance to tearing and compression since they are exposed trim elements.

  Acoustic treatment means are also known which combine insulation and absorption and which act for the soundproofing of the passenger compartment.

  EP-A-0934180 proposes, in particular, a porous spring-mass system for obtaining a passenger side absorption. The system is characterized by the combination of a densified fibrous layer with high resistance to the passage of air and a fibrous layer with low resistance to the passage of air. The system obtained makes it possible to provide acoustic absorption on the passenger side, at the expense of acoustic insulation, which proves to be less effective than a traditional system with a heavy sealed mass because of the low density levels reached by the densified fibrous layer.

  The document FR-A-2859477 describes a porous soundproofing system where the level of porosity is managed by a controlled deposit of polyolefin on the surface of one of the fibrous layers. The dusting process makes it possible to differentiate the quantity of powder deposited on one of the layers in order to locally optimize the acoustic properties. The location of the dusting acts effectively on the porosity of the felt but brings no gain in terms of mechanical properties on the cabin carpet function.

  On a number of points, it should be noted that the current soundproofing complexes are not completely satisfactory.

  First, because of their multi-material nature, soundproofing complexes are difficult and expensive to recycle. However, the total recycling of a vehicle is an important part of the design of a vehicle. The two major causes are the difficulty of separating the various materials constituting the soundproofing complex and the reticulated structure of the heavy mass and spring materials which prohibits any recycling by fusion. The only solution is to grind the waste and introduce it as a load in different applications. However, the quantity of this waste is much higher than the industrial reuse capacities.

  In addition, the soundproofing performance depends largely on the mass of the complex. However, the compromise between the total mass of the vehicle and acoustic soundproofing performance can be at the expense of acoustic performance because the mass of a vehicle can not be increased without limit.

  It should be noted that the soundproofing complexes are moreover composed of materials derived from petroleum chemistry, which means that their costs can be very fluctuating and generally tend to increase.

  It can further be noted that current soundproofing complexes that incorporate polymerizable materials have manufacturing times that can be significant.

  It therefore appears that the current soundproofing complexes have significant deficiencies.

  An object of the invention is to provide a soundproofing material that acts effectively in terms of insulation and absorption.

  Another object of the invention is to provide a soundproofing material which also has a mechanical strength.

  Another object of the invention is to provide a complex soundproofing system that can ensure localized acoustic and mechanical performance.

  Another object of the invention is therefore to provide an acoustic soundproofing complex that can be recycled at a lower cost.

  The invention relates to a porous layer heavy soundproofing comprising fibers entangled with polymeric particles and hot melt binder fibers amalgamating the polymer particles and fibers.

  The basis of the invention is to provide a fiber-based soundproofing layer which, because of the intrinsic porosity of the fibers, acts as an absorption and based on polymeric particles which give the soundproofing layer an effect of insulation; this insulating effect is obtained thanks to the polymer particles which ensure densification of the heavy porous layer and give it the necessary mass effect.

  Thus, remarkably, the heavy porous layer may have a density of between 150 and 1500 kg / m 3. It can be noted that this density is obtained while maintaining a certain flexibility. In this, the heavy porous layer according to the invention differs radically from known fibrous layers of the felt type whose density can be increased only by increasing compaction; this compaction induces a decrease in the flexibility of the felt and, consequently, a decrease in the mechanical and acoustic damping ability of the sound-absorbing felt.

  According to a particularly advantageous arrangement, the heavy porous layer is defined by at least one parameter of the group comprising the mass per unit area of the heavy porous layer, the thickness of the heavy porous layer, the concentration of fibers, the concentration of polymer particles, the concentration of hot-melt fibers at least one of these parameters may have a rate of variation per unit area.

  According to this arrangement, it is provided that one or more parameters defining the heavy porous layer has a gradient per unit area which has the effect of allowing a localized action on noise foci. In other words, once a mapping of sound foci is established, the heavy porous layer can itself be defined to be superimposed precisely on this mapping.

  In concrete terms, the heavy porous layer may comprise polymeric particles having a density of between 500 and 2000 kg / m 3.

  Preferably, the polymeric particles have a substantially lamellar shape whose ratio of the length to the thickness is between 5 and 100. This geometry makes it possible to ensure a large contact area between each polymeric particle and the hot-melt fibers, which allows to obtain a set having a strong cohesion.

  In practice, the minimum particle size of the polymer particles is of the order of 1 mm. Preferably, the particle size of the polymer particles is between 3 mm and 30 mm; this range makes it possible, in fact, a satisfactory cohesion of the fibrous structure.

  The invention also relates to a soundproofing complex 20 comprising a layer of heavy porous material on which is superposed a fibrous layer forming a spring.

  According to one possibility, the fibrous spring layer comprises fibers blended with hot melt fibers.

  In one embodiment of the fibrous spring layer, the latter is defined by at least one of the parameters of the group comprising the weight per unit area of the spring fibrous layer, the thickness of the spring fibrous layer, the fiber concentration, the particle concentration. at least one of these parameters may have a variation rate per unit area.

  The fibrous spring layer may also, and independently of the heavy porous layer, have one or more parameters having a gradient per unit area which has the effect of providing localized action on noise foci. The complex thus defined can be parameterized according to a sound map of a vehicle in terms of insulation by acting mainly on the definition of the heavy porous layer and / or in terms of absorption by acting mainly on the fibrous layer spring .

  Controlling the gradients per unit area of one or more parameters that characterize the fibrous layer forming spring also has the effect of allowing a localized action on the mechanical performance of the sound-absorbing complex. The complex thus defined can be parameterized locally in mechanical terms according to the stresses specific to certain areas of the complex.

  It can also be envisaged that the complex comprises a sealed or controlled porosity layer positioned between the appearance textile and the porous heavy layer.

  In certain applications, particularly in the case where the complex is disposed inside the passenger compartment of a vehicle, it is envisaged that the complex comprises a textile layer of appearance superimposed on the heavy porous layer.

  According to two other variants, the complex may comprise a sealed or controlled porosity layer positioned either between the appearance textile layer and the porous heavy layer or between the porous heavy layer and the spring fibrous layer.

  For a good understanding, the invention is described with reference to the accompanying drawing showing, by way of non-limiting example, several embodiments of a heavy porous layer and complexes incorporating this heavy porous layer.

  1 and 2 show an embodiment of a heavy porous layer respectively before and after compaction, FIG. 3 shows, on an enlarged scale, an entanglement of a polymeric particle in a fibrous network, FIG. 4 is a graph illustrating the mass constant pressure compact volume of two embodiments of a heavy porous layer according to the invention compared to a conventional fibrous layer, Figure 5 is a graph representing the insulation slope between 315 and 3150Hz of a heavy layer as a function of its density, FIGS. 6 and 7 show an embodiment of a heavy porous layer respectively before and after compaction with additional local supply of material, FIGS. 8 and 9 show an embodiment of a fibrous layer respectively springing before and after compaction with additional local material supply, Figure 10 shows an embodiment of a complex incorporating the porous layer heavy with the fibrous layer forming spring according to the invention, Figures 11 and 12 show two examples of soundproofing complex incorporating a sealed layer or controlled porosity, according to two types of preferred positioning.

  Referring first to FIG. 3, it can be seen that the heavy porous layer 2 is made of synthetic or natural frayed textile fibers 4 which are entangled with polymeric particles 5; the presence of binder fibers 6 is also noted whose function is to ensure the cohesion of this layer and form a network which traps the polymeric chips.

  One point to note is that most of the elements that go into the composition of the heavy porous layer 2 may be from recycling.

  Indeed, the frayed textile fibers 4 may be fibers from textile recycling. It may be synthetic fibers (acrylic, polyester) or possibly natural (cotton) which have a relatively low apparent density of the order of 0.02.

  These frayed textile fibers 4 behave relatively inert and have, as their main object, to confer its volume on the heavy porous layer 2.

  An advantage of integrating these frayed textile fibers 4 into the heavy porous layer 2 is their very low cost and their high availability.

  The second constituent of the heavy porous layer 2 which can also come from recycling consists of the polymeric particles 5.

  In practice, it may be particles 5 resulting from shredding of industrial polymeric material, belonging, for example, to the family of elastomers (EPDM type, EVA, rubber and derivatives) or thermoplastics (type PP, PE, PVC or other). By particles are meant small irregular pieces which are obtained by shredding or grinding the polymer waste. These particles 5 may be substantially flat and may have dimensions of the order of 3 to 30 millimeters. The fact that the particles 5 have irregular shapes and their surface has roughness proves to be a favorable point insofar as the asperities act as gripping elements with respect to the fibers 4.

  Thus, the particles can be used directly after their shredding or grinding operation without any treatment.

  The particles may be relatively calibrated, but it may also be envisaged to use particles having a wide variety of sizes.

  Finally, the third component which is used in the manufacture of the heavy porous layer 2 consists of binder fibers 6 hot melt.

  These binder fibers 6 may consist of bi-component polyester fiber, polypropylene or polyamide.

  These hot-melt binder fibers 6 are entangled with the frayed textile fibers 4 and the particles 5 and provide the strength and the cohesion of the heavy porous layer 2.

  The hot-melt binder fibers 6 form a network within the heavy porous layer 2 in which each point of contact between two binder fibers 6 constitutes a link point of the network.

  The effect of these provisions is, in particular, that each particle 5 is trapped individually in the network of binding fibers 6. The cohesion of the heavy porous layer 2, that is to say its ability not to disaggregate, is very important.

  The great specificity of the heavy porous layer according to the invention is that it incorporates polymeric particles whose function is to densify a fibrous structure which inherently has a low density.

  FIG. 1 shows the entanglement of fibers 4, particles 5 and binder fibers 6 prior to hot compaction, which makes it possible to obtain a final layer illustrated in FIG.

  FIG. 4 illustrates the fact that the contribution of the polymer particles makes it possible to double the density of a layer integrating the latter with respect to a purely fibrous layer.

  Column 41 of FIG. 4 represents a purely fibrous soundproofing structure having a reference density of 100; the columns 42 and 43 represent, at the same compaction pressure, the density of a heavy porous layer 2 respectively integrating particles of 600 kg / m 3 and 1000 kg / m 3.

  The consequence is as shown in FIG. 5, which represents an insulation slope as a function of the density of a layer. It is easy to measure the influence of the density and therefore the interest of maximizing it on the insulation slope.

  The heavy porous layer 2 may, in practice, have a basis weight of the order of 4 kg / m 2 for a thickness of 3 mm, which makes it a truly heavy layer which has a very significant sealing effect.

  The heavy porous layer 2 remains, nevertheless, flexible and can, therefore, be easily shaped to adapt to the geometric constraints of a vehicle in which it will take place.

  The heavy porous layer 2 can be used alone since it combines, at the same time, an insulation effect thanks to its high density which is conferred on it by the polymeric particles and an absorption effect thanks to its porous nature which it is conferred by the fibers. The heavy porous layer 2 may, for example, be used to double the inner face of a bonnet.

  The heavy porous layer 2 can, moreover, be implemented in a very specific manner which is illustrated in FIGS. 6 and 7. In this type of application, the heavy porous layer is shaped to conform to the shape of the floor of the vehicle; it has a strongly left-hand surface which has a transmission tunnel A, as well as locations B for the feet of the passengers also called cellar with feet. The complex can also be asked to integrate a reservation C to form a storage hatch.

  As can be seen in these figures, it may be envisaged to provide an additional supply of fibers 4, and / or particles 5 and / or binder fibers 6 for, in a particular zone of layer 2 (tunnel zone A in the example of Figure 6), change the soundproofing capacity of the layer after forming (Figure 7). Specifically, the thickness el of fibers 4, and / or particles 5 and / or binder fibers 6 in the tunnel zone A is greater than the thickness e2 of zone B. This results, after compaction and forming, by the fact that the density of the heavy porous layer 2 has an evolutionary surface mass since the value mv 1 of the density of the heavy porous layer 2 at the zone A is greater than the value mv 2 of the density at the Zone B. The benefits of this provision will appear later.

  It is also possible to implement the heavy porous layer 2 in a complex which associates a fibrous spring layer 3, as shown in FIG.

  As regards the spring fibrous layer 3, this comprises frayed textile fibers and hot melt binder fibers. The fibrous spring layer may also incorporate foam waste. In a manner similar to the heavy porous layer 2, it can be envisaged to provide an additional supply of fibers 4, and / or foam waste and / or binder fibers 6 for, in a particular zone of the layer 1 (cellar zone with feet B in the example of Figure 8), modify the mechanical properties in compression and the absorption capacity of the spring layer 3 after forming (see Figure 9). This results, after compacting and forming, in the fact that the density of the fibrous layer spring 3 has an evolutionary value since the value mv 4 of the density of the fibrous layer 3 at the level of the zone C is greater than the mv 3 value of the density at zone A. The heavy porous layer 2 and the fibrous layer spring 3 are superimposed and their connection is made by their respective hot melt fibers. In the example illustrated in Figure 10, there is also provided a layer 8 of carpet-like appearance textile.

  A tight layer or controlled porosity may optionally be positioned between two layers of the complex to improve the acoustic efficiency of the sound-insulating complex in terms of insulation. As described in FIG. 11, the invention provides for the possible use of such a sealing layer positioned between the appearance textile and the porous heavy layer or between the porous heavy layer and the fibrous spring layer.

  The soundproofing complex has, in practice, several significant advantages over the soundproofing complex which, for the most part, are multi-material assemblies working mainly in terms of simple acoustic insulation.

  A very significant advantage of this complex is that it can integrate areas of higher density to provide local noise treatment, which makes it possible to provide a complex in line with specific soundproofing needs.

  In Figure 10 is schematically shown a soundproofing complex according to the invention shaped in a floor mat application.

  As shown in FIG. 10, the complex which incorporates a heavy porous layer 2 and a fibrous spring layer 3 can be three-dimensionally shaped to suit the particular shape of the floor surface. An important point to emphasize is that the fibrous spring layer 3 provides a significant mechanical strength in terms of lift. This is important since, firstly, the handling of the complex, including its installation, is facilitated and, secondly, it avoids the phenomenon of depression of the feet of a passenger in the floor mat.

  Another important feature of the complex which is illustrated in FIGS. 6 to 9 is that the thickness (denoted e) and / or the density (denoted m) of each of the fibrous and fibrous layers 2 spring 3 may exhibit a rate of change; in other words, the complex can be precisely adapted according to geometric or acoustic requirements.

  Thus, in the example illustrated by FIG. 10, the density and thickness parameters of the heavy porous layer 2 and of the fibrous layer 3 can take the following values: tunneling zone A density mass, a surface thickness, a heavy porous layer, 2 3kg / m2 750kg / m3 4mm fibrous layer spring 3 0.7kglm2 60kg / m3 11.7mm cellar area with feet B mass density thickness surface area heavy porous layer 2 1, 5kg / m2 500kg / m3 3mm fibrous layer spring 3 2kg / m2 133kg / m3 15mm storage box area C mass density surface thickness heavy porous layer 2 1,5kg / m2 500kg / m3 3mm fibrous layer spring 3 3kg / m2 85kg / m3 35mm It is found that the parameters of density and thickness of the porous layer heavy 2 and the fibrous layer spring 3 are independently managed, which distinguishes the invention from known existing solutions. These numerical values are, of course, purely indicative and are in no way limiting.

  The complex acts both as an insulator and as an absorbent.

  The insulation is mainly obtained by the combination of the heavy porous layer 2 with the spring fibrous layer 3. The insulation levels achieved are higher than those of the known fibrous sound-absorbing complexes; this result is obtained thanks to the high density of the heavy porous layer 2.

  It may also be envisaged to include in the complex according to the invention a sealing layer 10 positioned between two layers 2 and 3 as shown in FIG. 12 or between the heavy porous layer 2 and the appearance textile layer 8.

  The absorption is obtained on both sides of the complex, both by the porous heavy layer 2 and by the fibrous layer spring 3. This is a very significant advantage in the case of an application such as that illustrated in FIG. the complex also has a sound absorption action that comes from the cabin. However, this sound component is far from negligible, especially in vehicles that have large glazed side surfaces (for example minivan-type vehicle) and / or a glass roof.

  Compared to the known complexes, the complex according to the invention is entirely fibrous and, as such, is easily recyclable. Its recycling can, in addition, be carried out by a textile recycling system which implements essentially mechanical means (shredding, grinding, carding, ...).

  The complex according to the invention is therefore recyclable but its main constituents can themselves be recycled, which has a very favorable impact on its cost.

  It is therefore noted that the method according to the invention makes it possible to ensure a localized and independent management of the thickness and / or the density of each of the constituent layers of the complex and thus, ultimately, to produce a complex whose properties of Soundproofing, in terms of insulation and in terms of absorption, and the mechanical properties, in terms of lift, compressive strength and tearing, can be modulated according to the acoustic and mechanical requirements locally requested.

  Of course, the invention is not limited to the embodiments described above, but on the contrary it embraces all variants.

Claims (14)

  1. porous heavy layer (2) of soundproofing characterized in that it comprises fibers (4) entangled with polymeric particles (5) and binder fibers (6) fusible amalgamating the polymeric particles (5) and the fibers ( 4).   2. porous heavy soundproofing layer according to claim 1, characterized in that it has a density of between 150 and 1500 kg / m3.   3. Heavy porous heavy layer (2) of soundproofing according to claim 1 or claim 2, characterized in that the heavy porous layer is defined by at least one parameter of the group comprising mass per unit volume of the heavy porous layer, thickness heavy porous layer, fiber concentration, concentration of polymeric particles, concentration of hot melt fibers at least one of these parameters may have a rate of change per unit area.   4. heavy porous layer (2) of soundproofing according to one of claims 1 to 3, characterized in that it comprises polymeric particles with a density of between 500 and 2000 kg / m3.   5. heavy porous layer (2) of soundproofing according to one of claims 1 to 4, characterized in that the polymeric particles have a substantially lamellar shape whose ratio of the length to the thickness is between 5 and 100.   6. heavy porous layer (2) of soundproofing according to one of claims 1 to 4, characterized in that the minimum particle size of the polymeric particles is of the order of 1 mm.   7. heavy porous layer (2) of soundproofing according to claim 6, characterized in that the particle size of the polymer particles is between 3 mm and 30 mm.   8. Soundproofing complex characterized in that it comprises a heavy porous layer (2) according to one of claims 1 to 7 on which is superimposed a fibrous spring layer (3).   A soundproofing complex according to claim 8, characterized in that the fibrous spring layer (3) comprises fibers blended with hot melt fibers.   10. soundproofing complex according to claim 9, characterized in that the fibrous spring layer (3) incorporates foam waste.   11. Soundproofing complex according to one of claims 8 to 10, characterized in that the fibrous spring layer (3) is defined by at least one of the parameters of the group comprising the surface density of the spring fibrous layer, thickness of the fibrous layer appears, fiber concentration, concentration of polymeric particles, at least one of these parameters may have a rate of change per unit area.   12. Complex according to one of claims 8 to 11, characterized in that it comprises a textile layer of appearance (8) superimposed on the heavy porous layer (3).   13. Sound insulation complex according to claim 8 or claim 11, characterized in that it comprises a layer (10) sealed or with controlled porosity positioned between the textile layer of appearance (8) and the porous heavy layer ( 2).   14. Soundproofing complex according to claim 8 or claim 11, characterized in that it comprises a layer (10) sealed or with controlled porosity positioned between the porous heavy layer (2) and the fibrous spring layer (3).