DE102019107230A1 - Sound insulation unit for a motor vehicle and corresponding manufacturing method - Google Patents

Abstract

The unit comprises an absorbent structure (16) comprising an absorbent body (18). The absorbent body (18) has in its thickness: * a porous upper region (22) comprising granular elements (24) interposed between fibers (20); having a porous lower region (26) without dispersed granular elements (24) or a concentration of distributed granular elements (24) that is less than the concentration of distributed granular elements (24) of the porous upper region (22 The porous upper region (22) has an air passage resistance of at least 100 Nms above the air passage resistance of the porous lower region (26), the porous lower region (26) having an air passage resistivity above 15,000 Nms.

Description

• - eine Masse-Feder-Struktur;
• - eine auf der Masse-Feder-Struktur angebrachte absorbierende Struktur.

The present invention relates to a sound insulation unit of a motor vehicle, comprising:

• a mass-spring structure;
• - An attached to the mass-spring structure absorbent structure.

Such a unit is intended to solve the acoustic problems that arise in a substantially closed space such as in a passenger compartment of a motor vehicle (mat, roof, door trim, etc.) in the vicinity of noise sources such as a motor (apron, etc.). or when tires are in contact with a road (wheel arch, etc.).

In general, in the range of low frequencies, the sound waves produced by the aforementioned noise sources are "dampened" by materials in the form of single or double plates (prestressed sandwich) with viscoelastic behavior or by acoustic attenuation by a porous and elastic mass-spring system.

For the purposes of the present invention, a sound insulation unit ensures "isolation" if it ensures the entry of medium and high-frequency sound waves in the insulated area substantially by reflection of the waves in the direction of the noise sources or to the outside of the insulated area.

A sound isolation unit works by "acoustic absorption" (in the range of medium and high frequencies) when the energy of the sound waves in an absorbing material dissipates.

• wobei TL der Schalldämpfungsindex (nachfolgend Dämpfungsindex) ist, der für die Isolation steht. Je höher dieser Index ist, umso besser ist die Isolation.
• A ist die äquivalente Absorptionsfläche. Je höher A ist, umso besser ist die Absorption. S ist die Fläche des Teils ist. [Muss noch bestätigt werden.]

An efficient sound insulation unit must guarantee both good insulation and absorption. In order to assess the performance of such a unit, the term noise reduction index NR is used, taking into account both isolation and absorption: this index can be calculated from the following equation: $$\text{NO}\left(\text{dB}\right)=\text{TL}-10\text{log}\left(\text{S / A}\right).$$

• where TL is the sound attenuation index (hereinafter the attenuation index) that stands for isolation. The higher this index, the better the isolation.
• A is the equivalent absorption area. The higher A is, the better the absorption. S is the area of the part. [Must be confirmed.]

In order to ensure good sound insulation, for example for a motor vehicle passenger compartment, it is desirable to use a group of materials in which these parameters can be meaningfully influenced. This has been described in many articles, especially in the article "Faurecia Acoustic Light-weight Concept", which was presented at the SIA / CTTM 2002 conference in Le Mans.

For good sound insulation, the use of mass-spring type units is known, which are formed by a porous and elastic base layer on which an impermeable layer of heavy mass is arranged. This impermeable layer of heavy mass generally has a high basis weight, in particular over 1 kg / m ² , and also a high volume-related mass in the order of 1500 kg / m ³ to 2000 kg / m ³ .

Such acoustic units provide good sound isolation, but are relatively heavy. Moreover, their absorption behavior is quite weak.

To reduce the mass of a sound insulation unit describes US2006 / 0113146 a bi-permeable type acoustic unit in which the heavy mass layer is replaced by a porous layer. Between the base spring layer and the porous layer, a thin and acoustically transparent film is interposed.

Such a unit, in fact, facilitates the vehicle structure, but is effective primarily in terms of absorption, but does not provide satisfactory insulation when compared to a traditional mass-spring system.

To improve the insulation and absorption at the same time, for example, from the WO2013026847 four-layered units of the aforementioned type, comprising a spring layer, a layer of heavy mass, an absorbent layer and a resistive nonwoven fabric layer which has a higher air-throughput resistance than the absorbent layer.

The first two layers form a mass-spring structure, which mainly ensures the insulation function. The two upper layers form an absorbent structure which provides adequate absorption in accordance with the above-mentioned. Bipermeability principle guaranteed.

There is synergy between layers, especially when the absorbent layer is rigid, which simultaneously optimizes its insulation and absorption properties. The global mass of the unit is significantly reduced without compromising the unit's acoustic performance.

However, such a unit is relatively expensive to manufacture. The four layers must be delivered and then joined together, which requires many manufacturing steps.

Incidentally, some of the layers used are relatively expensive. This is particularly the case with the resistive nonwoven made from very fine fibers according to a difficult process. Also, for the production of a heavy mass with a low weight, a large amount of polymer is required in view of the batch content to ensure sufficient rigidity. This increases the cost of the part.

Finally, a special adhesive is required for the connection of the layers to each other at each interface. For example, when bonding the absorbent layer to the nonwoven layer, the porosity must be preserved at the interface between the layers. In contrast, the connection between the base spring layer and the layer of heavy mass must be very robust.

Finally, the resulting parts have limited rigidity, which is why handling them on the assembly lines is sometimes difficult.

An object of the invention is to obtain a sound insulation unit which is very effective in both the insulation and the absorption and is simple and inexpensive to manufacture and easy to handle.

• * eine poröse obere Region, aufweisend körnige Elemente, die zwischen den Fasern verteilt sind;
• * eine poröse untere Region ohne verteilte körnige Elemente oder eine Konzentration verteilter körniger Elemente aufweisend, die geringer ist als die Konzentration verteilter körniger Elemente der porösen oberen Region;

wobei die poröse obere Region einen Luftdurchgangswiderstand von mindestens 100 N.m^-3.s über dem Luftdurchgangswiderstand der porösen unteren Region aufweist, wobei die poröse untere Region eine Luftdurchgangsresistivität von über 15000 N.m^-4.s aufweist.For this purpose, the invention relates to a unit of the aforementioned type, characterized in that the absorbent structure comprises an absorbent body having a plurality of entangled and / or bonded fibers, the absorbent body having in its thickness:

• * a porous upper region, comprising granular elements distributed between the fibers;
• * having a porous lower region with no dispersed granular elements or a concentration of dispersed granular elements less than the concentration of dispersed granular elements of the porous upper region;

wherein the porous upper region has an air passage resistance of at least 100 Nm ^-3. ss above the air passage resistance of the porous lower region, the porous lower region having an air passage resistivity of over 15,000 Nm ^-4 . s.

• - die Masse-Feder-Struktur weist einen Basiskörper auf, der eine Vielzahl verschlungener und/oder verbundener Fasern umfasst, wobei der Basiskörper in seiner Dicke aufweist:
  • * eine dichte obere Region, die zusätzliche körnige Elemente aufweist, die zwischen den Fasern verteilt sind, und geschmolzene verbindende Elemente, welche die zusätzlichen körnigen Elemente mit den Fasern verbinden;
  • * eine poröse elastische untere Region ohne verteilte zusätzliche körnige Elemente oder welche eine Konzentration verteilter zusätzlicher körniger Elemente aufweist, die geringer ist als die Konzentration verteilter zusätzlicher körniger Elemente der dichten oberen Region;
• - die Dichte der zusätzlichen körnigen Elemente, die in der dichten oberen Region vorhanden sind, ist höher als die Dichte der körnigen Elemente, die in der porösen oberen Region vorhanden sind;
• - die flächenbezogene Masse der dichten oberen Region ist höher als 100 g/m² und liegt insbesondere zwischen 100 g/m² und 4000 g/m²;
• - die verbindenden Elemente der dichten oberen Region sind aus einem geschmolzenen schmelzbaren Pulver oder aus geschmolzenen Fasern gebildet;
• - die Dicke der dichten oberen Region ist kleiner als die Dicke der porösen elastischen unteren Region;
• - der Luftdurchgangswiderstand der porösen oberen Region ist grösser als 250 N.m^-3.s und liegt insbesondere zwischen 250 N.m^-3.s und 1500 N.m^-3.s;
• - die Dicke der porösen oberen Region beträgt weniger als 15 mm;
• - die Biegesteifigkeit der porösen unteren Region ist grösser als 0,1 N.m;
• - der absorbierende Körper ist zusammenhängend gebildet, wobei der Basiskörper zusammenhängend gebildet ist.

The unit according to the invention may comprise one or more of the following features, which are used alone or in accordance with all technically possible combinations:

• - The mass-spring structure comprises a base body comprising a plurality of entangled and / or connected fibers, wherein the base body has in its thickness:
  • a dense upper region having additional granular elements distributed between the fibers and molten interconnecting elements connecting the additional granular elements to the fibers;
  • * a porous elastic lower region without distributed additional granular elements or which has a concentration of distributed additional granular elements which is less than the concentration of distributed additional granular elements of the dense upper region;
• the density of the additional granular elements present in the dense upper region is higher than the density of the granular elements present in the porous upper region;
• the area-related mass of the dense upper region is higher than 100 g / m ² and in particular between 100 g / m ² and 4000 g / m ² ;
• the connecting elements of the dense upper region are formed from a molten fusible powder or from molten fibers;
• the thickness of the dense upper region is smaller than the thickness of the porous elastic lower region;
• - The air passage resistance of the porous upper region is greater than 250 Nm ^-3 .s and is in particular between 250 Nm ^-3 .s and 1500 Nm ^-3 .s;
• the thickness of the porous upper region is less than 15 mm;
• the bending stiffness of the porous lower region is greater than 0.1 Nm;
• - The absorbent body is formed integrally, wherein the base body is formed coherently.

• * Bilden einer absorbierenden Struktur, aufweisend:
  • - Bereitstellen eines absorbierenden Körpers, aufweisend eine Vielzahl verschlungener und/oder verbundener Fasern,
  • - Integrieren körniger Elemente zwischen die Fasern einer porösen oberen Region des absorbierenden Körpers;
  • - Bewahren einer porösen unteren Region des absorbierenden Körpers ohne verteilte körnige Elemente oder einer porösen unteren Region des absorbierenden Körpers, aufweisend eine Konzentration verteilter körniger Elemente, welche geringer ist, als die Konzentration verteilter körniger Elemente der porösen oberen Region;
  wobei die poröse obere Region einen Luftdurchgangswiderstand von mindestens 100 N.m^-3.s über dem Luftdurchgangswiderstand der porösen unteren Region aufweist, wobei die poröse untere Region eine Luftdurchgangsresistivität über 15000 N.m^-4.s aufweist;
• * Verbinden der absorbierenden Struktur mit einer Masse-Feder-Struktur.

The invention also has a manufacturing method of a sound insulation unit of a Subject of the motor vehicle, comprising the following steps:

• Forming an absorbent structure comprising:
  • Providing an absorbent body comprising a plurality of entangled and / or bonded fibers,
  • Integrating granular elements between the fibers of a porous upper region of the absorbent body;
  • Maintaining a porous lower region of the absorbent body without distributed granular elements or a porous lower region of the absorbent body, having a concentration of dispersed granular elements which is less than the concentration of dispersed granular elements of the porous upper region;
  wherein the porous upper region has an air passage resistance of at least 100 Nm ^-3. ss above the air passage resistance of the porous lower region, the porous lower region having an air passage resistivity over 15000 Nm ^-4 . s;
• * Connecting the absorbent structure with a mass-spring structure.

• - es weist einen Schritt des Bildens der Masse-Feder-Struktur auf, umfassend:
  • * Bereitstellen eines Basiskörpers, umfassend eine Vielzahl verschlungener und/oder verbundener Fasern;
  • * Integrieren verteilter zusätzlicher körniger Elemente und verbindender Elemente zwischen den Fasern einer oberen Region des Basiskörpers;
  • * Bewahren einer porösen elastischen unteren Region ohne verteilte zusätzliche körnige Elemente oder einer porösen elastischen unteren Region, aufweisend eine Konzentration verteilter zusätzlicher körniger Elemente, die geringer ist, als die Konzentration verteilter zusätzlicher körniger Elemente der oberen Region;
  • * mindestens teilweises Schmelzen der verbindenden Elemente, um eine dichte obere Region zu bilden;
• - es weist zwischen den Schritten des Integrierens und dem Schritt des Schmelzens das Anordnen des absorbierenden Körpers, versehen mit den körnigen Elementen, auf dem Basiskörper, versehen mit den zusätzlichen körnigen Elementen und den Verbindungselementen, auf, wobei der Schritt des Schmelzens das gleichzeitige Erwärmen des absorbierenden Körpers, versehen mit den körnigen Elementen, und des Basiskörpers, versehen mit den zusätzlichen körnigen Elementen und den Verbindungselementen, umfasst;
• - der Verbindungsschritt wird nach dem gleichzeitigen Erwärmen des absorbierenden Körpers, versehen mit den körnigen Elementen, und des Basiskörpers, versehen mit den zusätzlichen körnigen Elementen und den Verbindungselementen, durchgeführt, wobei der Verbindungsschritt das gleichzeitige Einsetzen des absorbierenden Körpers, ver- sehen mit den körnigen Elementen, und des Basiskörpers, versehen mit den zusätzlichen körnigen Elementen und den Verbindungselementen, in den Hohlraum einer Form, und das thermische Formen der absorbierenden Struktur und der Masse-Feder-Struktur im Hohlraum der Form umfasst;
• - das Verbinden umfasst die Befestigung der oberen Region des Basiskörpers auf der unteren Region des absorbierenden Körpers durch Eindringen der zumindest teilweise geschmolzenen verbindenden Elemente der oberen Region des Basiskörpers in die untere Region des absorbierenden Körpers.

The method according to the invention may comprise one or more of the following features, which are used alone or in accordance with all technically possible combinations:

• it comprises a step of forming the mass-spring structure, comprising:
  • Providing a base body comprising a plurality of entangled and / or bonded fibers;
  • Integrating distributed additional granular elements and connecting elements between the fibers of an upper region of the base body;
  • Maintaining a porous elastic lower region without distributed additional granular elements or a porous elastic lower region, having a concentration of distributed additional granular elements that is less than the concentration of distributed additional granular elements of the upper region;
  • at least partial melting of the connecting elements to form a dense upper region;
• between the integrating steps and the step of melting, arranging the absorbent body provided with the granular elements on the base body provided with the additional granular elements and the connecting elements, wherein the step of melting comprises simultaneously heating the body absorbent body provided with the granular elements, and the base body provided with the additional granular elements and the connecting elements comprises;
• the joining step is carried out after simultaneously heating the absorbent body provided with the granular elements and the base body provided with the additional granular elements and the connecting elements, the joining step involving the simultaneous insertion of the absorbent body, provided with the granular Elements, and the base body, provided with the additional granular elements and the connecting elements, in the cavity of a mold, and the thermal forms of the absorbent structure and the mass-spring structure in the cavity of the mold comprises;
• the bonding comprises attaching the upper region of the base body to the lower region of the absorbent body by penetrating the at least partially fused connecting elements of the upper region of the base body into the lower region of the absorbent body.

• - die 1 eine schematische Schnittansicht einer ersten erfindungsgemäßen Schalldämmungseinheit ist;
• - die 2 und 3 Ansichten sind, welche die Schritte des Beschickens jeweils des Basiskörpers und des absorbierenden Körpers mit körnigen Elementen und verbindenden Elementen veranschaulicht;
• - die 4 einen späteren Schritt der Anordnung des Basiskörpers auf dem absorbierenden Körper veranschaulicht;
• - die 5 einen späteren Schritt des gleichzeitigen thermischen Formens des Basiskörpers und des absorbierenden Körpers veranschaulicht.

The invention will be better understood by reading the following description, given by way of example only and with reference to the accompanying drawings, in which:

• - the 1 a schematic sectional view of a first sound insulation unit according to the invention is;
• - the 2 and 3 Are views illustrating the steps of charging each of the base body and the absorbent body with granular elements and connecting elements;
• - the 4 illustrates a later step of disposing the base body on the absorbent body;
• - the 5 illustrates a later step of simultaneously thermoforming the base body and the absorbent body.

In the following, the directions are generally the usual directions of a motor vehicle. However, the terms "above,""above,""below,""below,""upper," and "lower" are to be understood relative to the reference surface of the motor vehicle with respect to which the sound insulation unit is disposed. The term "lower" is therefore as close as possible to the surface and the To understand term "upper" as far away as possible from this surface.

A first sound insulation unit according to the invention 10 is on the 1 shown. This unit 10 is destined to a surface 12 a motor vehicle to be arranged.

The area 12 For example, is a metallic sheet metal surface of the vehicle, which defines in particular a floor, a ceiling, a door, a skirt that separates the passenger compartment from the engine compartment, a hood or a wheel arch of the motor vehicle.

The unit 10 is destined to be right on the surface 12 to rest. She can on the surface 12 be attached, advantageously by means of pins (for example in the case of a skirt), or on which it receives, be placed (for example in the case of a mat). In one variant is the unit 10 on the surface 12 bonded.

With reference to the 1 indicates the unit 10 a mass-spring structure 14 on, which is meant to be on the surface 12 to be applied, and an absorbent structure 16 Standing on the mass-spring structure 14 is applied on one of the surface 12 opposite side.

According to the invention, the absorbent structure 16 a coherent absorbent body 18 from a variety of entangled and / or bonded fibers 20 is formed. The absorbent body 18 includes a porous and resistive upper region 22 , the grainy elements 24 that is between the fibers 20 are distributed, and a porous lower region 26 without distributed granular elements 24 , or the concentration of distributed granular elements 24 which is less than the concentration of distributed granular elements 24 in the porous upper region 22 ,

Advantageously, the porous upper region comprises 24 connecting elements 28 to the grainy elements 24 with the fibers 20 connect to.

In this example, the absorbent body is 18 formed by a felt or a textile.

By "coherent" is meant that the absorbent body 18 is formed by a single layer of intertwined and / or connected fibers and not by a compound interconnected layers.

For the purposes of the present invention, "felt" is to be understood as meaning a mixture of base fibers and binder. The base fibers may be new and / or recycled, natural or synthetic fibers of one or more types. Examples of natural fibers that can be used are linen, cotton, hemp, bamboo, etc. Examples of synthetic fibers that can be used are mineral fibers such as glass fibers or organic fibers such as kevlar, polyamide, acrylic, polyester , Polypropylene.

The binder is preferably formed from fusible fibers, in particular polyolefin fibers, in particular polypropylene fibers. As a variant, the binder is formed of thermosetting resin, in particular polyester resin.

In one variant, the felt comprises an increased percentage of microfibers, for example over 50% and advantageously 80% microfibers.

By "microfibers" are meant fibers having sizes below 0.9 dtex, advantageously 0.7 dtex.

In one variant, the felt contains recycled material derived, for example, from internal or external wastes, in particular from production wastes of automotive trim parts, fabrication scrap or vehicle parts whose life has expired. For example, these wastes are comminuted and integrated into the felt in the form of pieces of shredded material formed by agglomerates, flakes or particles. The components of the waste can be separated before or during crushing.

By "textile" is meant a mat of fibers based essentially on thermoplastic polymer such as polypropylene, polyester or polyamide, which are mechanically connected by needling without the use of chemical binders. Such a mat may contain a percentage of recycled thermoplastic or natural fibers.

With reference to the 1 has the absorbent body 18 a lower surface 30 on top of the mass-spring structure 14 is attached, and an upper surface 32 , which is designed to be the mass-spring structure 14 to align oppositely.

The absorbent structure 16 has a total thickness ET, determined between the lower surface 30 and the upper surface 32 , perpendicular to the surface 12 , of over 2 mm and in particular between 5 mm and 25 mm, on.

The grainy elements 24 are for example powdered batches. Examples of batches are chalk, barite and / or vermiculite, crushed or with cellulose.

The grainy elements 24 have an average dimension, calculated as a numerical average, of less than 1 mm and in particular between 5 μm and 500 μm. This average dimension becomes, for example, according to the norm ISO 13320-1 measured.

The density of the material, which is the granular elements 18 is less than 5 and is in particular between 0.8 and 2.

The connecting elements 28 are formed, for example, from polymer powders such as polyolefin, in particular polypropylene.

In the absorbent structure 16 became the connecting elements 28 at least partially melted to the fibers 20 with the grainy elements 24 to connect without the grainy elements 24 melt.

Thus, the grainy elements 24 in terms of fibers 20 from the connecting elements 28 kept in position.

As already stated above, the concentration of granular elements 24 in the porous upper region 22 at least 10% above the concentration of granular elements 24 in the porous lower region 26 ,

By the presence of the granular elements 24 in the porous upper region 22 become the between the fibers 20 closed gaps, which increases the distortion and the porosity of the porous upper region 22 is reduced, while maintaining a non-zero porosity.

Thus, the air passage resistance is the porous upper region 22 at least 100 Nm ^-3 .s above the air passage resistance of the porous lower region 26 , in particular at least 250 Nm ^-3 .s above the air passage resistance of the porous lower region 26 ,

In absolute terms, the air passage resistance is the porous upper region 22 greater than 250 Nm ^-3 .s and is in particular between 250 Nm ^-3 .s and 1500 Nm ^-3 .s, in particular between 300 Nm ^-3 .s and 1000 Nm ^-3 .s.

The air passage resistance or its resistivity is measured by the method described in the dissertation "Mesures of parametres caracterisant un milieu poreux. Etude experimental du comportement acoustique des mousses aux basses frequences. "By Michel HENRY, defended on October 3, 1997, Universite du Mans, was described.

The thickness of the porous upper region 22 is generally lower than the region 18 , Thickness ES of porous upper region 22 is for example less than 15 mm and in particular between 1 mm and 10 mm.

In certain cases, it may be advantageous locally to increase the weight and, consequently, the layer 16 to fill completely. Another advantage of the powder is that it is locally more or less applicable.

The area-related mass of the porous upper region 22 is less than 500 g / m ² and is between 500 g / m ² and 3500 g / m ² , advantageously between 1000 g / m ² and 2000 g / m ² .

The porous lower region 26 has a porosity which is suitable for exhibiting an air-permeation resistance which is advantageously between 15,000 Nm ^-4 .s and 80,000 Nm ^-4 .s, in particular between 20,000 Nm ^-4 .s and 50,000 Nm ^-4 .s ,

The area-related volume mass of the porous lower region 26 is generally between 20 kg / m ³ and 400 kg / m ³ , in particular between 50 kg / m ³ and 300 kg / m ³ .

The thickness EI of the porous lower region 20 , determined perpendicular to the surface 12 , Is advantageously between 2 mm and 35 mm, for example between 5 mm and 25 mm.

The porous lower region 26 is stiffened. It advantageously has a bending stiffness B which, based on a unit width, is greater than 0.01 Nm and in particular between 0.1 Nm and 1 Nm, in particular between 0.1 Nm and 0.5 Nm.

• B = E.h³/12, wobei h die Dicke der porösen oberen Region 16 und E dessen Young-Modul ist.

The bending stiffness B is calculated using the following equation:

• B = Eh ^3/12, where h is the thickness of the porous upper region 16 and e whose Young's module is.

The Young's modulus or Young's modulus, for example, is measured by the method described in the article C Langlois, R Panneton, and N Atalla, "Polynomial for quasi-static mechanical characterization of isotropic materials" J. Acoust. Soc. At the. 110, 3032-3040 (2001) is described.

The mass-spring structure 14 has a contiguous base body 34 on, by a variety entwined and / or connected fibers 35 is formed. The base body 34 has a dense upper region 36 on, the extra grainy elements 38 and a resilient porous lower region 40 without distributed additional grainy elements 38 or with a concentration of additional granular elements 38 , which is lower than the concentration of additional granular elements 38 that are in the porous upper region 36 are distributed.

The upper region 36 the mass-spring structure 14 also has molten linking elements 42 on which the additional grainy elements 38 with the fibers 35 connect and the gaps between the fibers 35 close to the upper region 36 seal.

In this example, the base body is 34 formed from a coherent felt or textile, as described above.

With reference to the 1 indicates the base body 34 a lower surface 44 on that is destined to the surface 12 to be aligned, which is preferably intended to be on the surface 12 to lie up, and a top surface 46 , which is intended, opposite to the surface 12 to be aligned on the lower surface 30 the absorbent structure 16 is fixed.

The base body 34 has a total thickness ET ' up, determined perpendicular to the surface 12 , ET ' is generally greater than the total thickness ET the absorbent structure 16 ,

The additional grainy elements 38 are for example powdered batches. The batches are for example barite, chalk or clay.

The additional grainy elements 38 have an average dimension, calculated as a numerical average, of less than 1 mm and in particular between 5 μm and 500 μm.

This average dimension becomes, for example, according to the norm ISO 13320-1 measured.

The density of the material, which the additional granular elements 38 is greater than 2 and is in particular between 3 and 5.

The density of the additional granular elements 38 that are in the dense upper region 36 are present, is higher than the density of the granular elements 24 that are in the porous upper region 22 available.

The concentration of additional granular elements 38 in the dense upper region 36 is at least 10% above the concentration of additional granular elements 38 in the elastic lower region 40 ,

The connecting elements 42 are formed, for example, from a powder of a material which is meltable at a temperature below 200 ° C, for example a polymer powder such as a polyolefin powder.

The powder of fusible material was in the mass-spring structure 14 at least partially melted to the fibers 35 with the additional grainy elements 38 to connect without leaving the extra grainy elements 38 melt.

Thus, the additional grainy elements 38 in terms of fibers 35 from the molten connecting elements 42 kept in position.

The molten connecting elements 42 also close the gaps between the fibers 35 to make tightness.

Thus, the upper region 36 tight. The air passage resistance of the dense upper region 36 is too high to be measured by the aforementioned method for measuring the air passage resistance.

Thickness ES 'dense upper region 36 is for example between 0.5 mm and 5 mm and in particular between 1 mm and 3 mm.

The area-related mass of the dense upper region 36 is greater than 100 g / m ² and is between 100 g / m ² and 4000 g / m ² , advantageously between 800 g / m ² and 2000 g / m ² .

The area-related mass of the porous lower region 40 is generally between 80 g / m ² and 8000 g / m ² , in particular between 200 g / m ² and 4000 g / m ² .

The thickness EI 'of the porous lower region 40 , determined perpendicular to the surface 12 , Is advantageously between 2 mm and 100 mm, for example between 5 mm and 50 mm.

To exhibit spring properties, the porous lower region indicates 40 advantageously a modulus of elasticity above 5000 Pa. This module is advantageously between 20,000 Pa and 100,000 Pa, in particular between 30,000 Pa and 40,000 Pa.

The modulus of elasticity is measured according to the standard, for example by the method described in the article C Langlois, R Panneton, and N Atalla, "Polynomial for quasi-static mechanical characterization of isotropic materials" J. Acoust. Soc. At the. 110, 3032-3040 (2001) is described.

A manufacturing method of the sound insulation unit according to the invention 10 is carried out in a facility that is on the 2 to 5 is shown schematically.

The facility has a preparation station 60 of the base body 34 on, pictured on the 2 There are additional grainy elements 38 and a preparatory station 62 of the absorbent body 18 , presented on the 3 There, there are the grainy elements 24 applied.

The system also has an arrangement station 64 for the arrangement of the absorbent body 18 , provided with the grainy elements 24 , on the base body 34 , provided with the additional grainy elements 38 , a cutting station 65 and an education and connection station 66 the mass-spring structure 14 with the absorbent structure 16 on.

With reference to the 2 indicates the preparation station 60 a deployment unit 72 of the base body 34 , a displacement conveyor 74 of the base body 34 , at least one application unit 76 additional granular elements 38 and connecting elements 42 on the base body 34 and an integration unit 78 the additional grainy elements 38 in the base body 34 on.

The preparation station 60 further advantageously comprises a first activation unit 80 the connecting elements 42 on.

The delivery unit 72 of the base body 34 suitable, the base body 34 to form a fiber mat or preformed in the form of a tape base body 34 provide.

The conveyor 74 is suitable to the body 14 from the deployment unit 72 along a longitudinal axis A-A ' to carry it to the application unit 76 , the integration unit 78 , the activation unit 80 is moved past.

The application unit 76 has a reservoir 84 the additional grainy elements 38 and at least one distributor 86 on which is suitable, the additional grainy elements 38 in the form of a continuous layer on the upper surface 46 of the base body 36 applied. The distributor 86 has, for example, a role 88 and a guide 90 on that over the top surface 46 opens.

The integration unit 78 has, for example, a source 92 for generating an electromagnetic field, in particular a variable electric field, on the additional granular elements 38 works, so that these in the base body 34 penetrate over a certain thickness.

Advantageously, the integration unit 78 and a source of vibration (not shown) for integrating the additional granular elements 38 in the base body 34 to facilitate.

The integration unit 78 is for example formed by a machine of the type "FIBROLINE®".

The activation unit 80 here has a heat source that is suitable, the connecting elements 42 above their melting temperature to heat to melt them. The heat source has, for example, an infrared lamp.

With reference to the 3 is the structure of the preparation station 62 analogous to the structure of the preparation station 60 , It has a deployment unit 102 of the absorbent body 18 , a displacement conveyor 104 of the absorbent body 18 , at least one application unit 106 granular elements 24 and connecting elements 28 on the absorbent body 18 and an integration unit 108 the grainy elements 24 in the absorbent body 18 on.

The preparation station 62 further advantageously comprises a first activation unit 110 the connecting elements 42 on.

The delivery unit 102 of the absorbent body 18 is suitable to the absorbent body 18 to form a fiber mat or a preformed in the form of a tape absorbent body 18 provide.

Like the conveyor 74 is the sponsor 104 suitable, the absorbent body 18 from the deployment unit 102 along a longitudinal axis B-B ' to carry it to the application unit 106 , the integration unit 108 , the activation unit 110 is moved past.

The structure of the application unit 106 is analogous to that of the application unit 76 , She has a reservoir 114 of grainy elements 24 and at least one distributor 116 on which is appropriate the grainy elements 24 in the form of a continuous layer on the upper surface 32 of the absorbent body 18 applied. The distributor 116 has, for example, a role 118 and a guide 120 on that over the top surface 32 opens.

The structure of the integration unit 108 is analogous to that of the integration unit 78 , For example, it assigns a source 122 for generating an electromagnetic field, especially a variable electric field acting on the granular elements 24 works to keep these in the absorbent body 18 penetrate over a certain thickness.

Advantageously, the integration unit 108 and a source of vibration (not shown) for integrating the granular elements 24 in the absorbent body 18 to facilitate.

The activation unit 110 here has a heat source that is suitable, the connecting elements 28 beyond their melting temperature to at least partially melt them. The heat source has, for example, an infrared lamp.

The arrangement station 64 is appropriate to the concern of a lower surface 30 of the absorbent body 18 , provided with the grainy elements 24 , on an upper surface 46 of the base body 34 , provided with the additional grainy elements 38 to allow for a pile 130 to build.

Advantageously, the stations 60 or 62 placed in continuity with the fabrication lines of felts or textiles used for the invention.

The cutting station 65 is suitable for the pile 130 on the dimensions of the sound insulation unit to be formed 10 tailor.

The connection station 66 has at least one heater (not shown) and a mold 132 on having a molding cavity 134 which is suitable for shaping the absorbent structure 16 and the mass-spring structure 14 and perform their simultaneous connection to each other.

The heating device advantageously comprises an apparatus capable of producing a warm gas flow intended for the absorbent body 18 and to the base body 34 to be directed to the absorbent body 18 and the base body 34 to cross.

The warm gas is for example air. It is advantageously brought to a temperature above 120 ° C and in particular to a temperature which is between 120 ° C and 200 ° C.

It is suitable, the connecting elements 28 . 42 of the cut pile 130 to heat so that they at least partially melt, and in particular the penetration of molten material from the upper region 36 of the base body 34 in the lower region 26 of the absorbent body 18 to allow.

Form 132 has at least one cooled surface 136 suitable for allowing the solidification of the molten material in the stack 130 is available.

The area 136 the form 132 is cooled, for example, to a temperature below 15 ° C and especially between 10 ° C and 20 ° C.

Now becomes a manufacturing method of a sound insulation unit according to the invention 10 described.

First, a base body 34 from the deployment unit 72 provided by directly in the deployment unit 72 produced or unrolled from a stock in the delivery unit 72 is available.

The base body 34 in the form of a ribbon is on the conveyor 74 placed one after the other in front of the application unit 76 , the integration unit 78 and the activation unit 80 guided. During its passage in front of the application unit 76 Become additional grainy elements 38 from the reservoir 84 delivered and on the upper surface 46 of the base body 34 by the distributor 86 and the role 88 applied.

The amount of additional granular elements added 38 is from the distributor 86 depending on the passage speed of the body 34 on the conveyor 74 controlled.

After that, in the integration unit 78 a variable electromagnetic field through the base body 34 created so that the extra grainy elements 38 in an upper region 36 of the base body 34 penetrate, as defined above. Connecting elements 42 will also be simultaneously with the additional grainy elements 38 or separated from these integrated.

The base body 34 then passes to the activation unit 80 , The connecting elements 42 are then at least partially melted to fill the gaps between the fibers 35 of the base body 34 and the extra grainy elements 38 close. The additional grainy elements 38 thus become with the fibers 35 mechanically connected.

Incidentally, an absorbent body 18 from the deployment unit 102 provided by directly in the deployment unit 102 produced or unrolled from a stock in the delivery unit 102 is available.

The absorbent body 18 in the form of a ribbon is on the conveyor 104 placed one after the other in front of the application unit 106 , the integration unit 108 and the activation unit 110 guided.

During its passage in front of the application unit 106 become grainy elements 24 from the reservoir 114 delivered and on the upper surface 32 of the absorbent body 18 by the distributor 116 and the role 118 applied.

The amount of added granular elements 24 is from the distributor 116 depending on the passage speed of the body 18 on the conveyor 104 controlled.

After that, in the integration unit 108 a variable electromagnetic field through the absorbent body 18 created so that the grainy elements 24 in an upper region 22 of the absorbent body 18 penetrate, as defined above. Connecting elements 28 are also simultaneously with the grainy elements 24 or separated from these integrated.

The absorbent body 18 then passes to the activation unit 110 , The connecting elements 28 are then at least partially melted to the granular elements 24 with the fibers 20 mechanically connect while leaving gaps between the fibers 20 and grainy elements 24 to keep it open.

Thereafter, in the arrangement station 64 the lower surface 30 of the absorbent body 18 , provided with connecting elements 28 , in contact with the upper surface 46 of the base body 34 , provided with the additional grainy elements 38 arranged.

The stack thus formed 130 gets into the cutting station 65 introduced to the dimensions of the sound insulation unit 10 to be tailored.

Thereafter, after additional heating in the heater described above, the cut pile becomes 130 into the molding cavity 134 the form 132 used.

Form 132 is closed, causing the stack 130 and especially the absorbent body 18 and the base body 34 to be compressed.

In this compression, the connecting elements solidify 28 and keep the thickness of the absorbent body 18 below the thickness he used before his insertion into the mold 132 would have. The absorbent body 18 comes with an upper region 22 , which remains porous, and a porous lower region 26 that has a lower air passage resistance than the porous upper region 22 has, as described above, shaped.

The connecting elements 42 spread in the gaps between the additional grainy elements 38 and the fibers 35 to close these gaps and the upper region 36 of the base body 34 airtight. Incidentally, part of the at least partially molten additional granular elements penetrates 38 into the porous lower region 26 of the absorbent body 18 one to the porous lower region 26 of the absorbent body 18 with the dense upper region 36 of the base body 34 connect to.

Then the shape 132 reopened. Due to its elasticity, the thickness of the porous lower region decreases 40 of the base body 34 in terms of thickness, they are in shape 132 would have.

A sound insulation unit 10 , the four regions 22 . 26 . 36 . 40 with different properties is thus formed, with a porous upper region 22 that has greater air passage resistance than a porous lower region 26 then a dense upper region 36 and a porous lower region 40 , which each have the properties described above.

The sound insulation unit 10 is formed in a simple way, since the connection of the body 18 . 34 takes place in one step with the formation of the part with the correct dimensions.

Further, the production of the porous upper region 22 with a relatively high air passage resistance is relatively simple and requires no provision and connection of a resistive nonwoven fabric. The cost of the unit 10 are thus greatly reduced.

In addition, the dense upper region 36 be manufactured inexpensively and sufficiently rigid with a corresponding surface-related mass.

In a variant in which the rigidity is further improved, a nonwoven fabric based on non-fusible fibers such as glass fibers becomes interposed between the absorbent bodies 18 , provided with the grainy elements 24 , and the base body 34 , provided with the additional grainy elements 38 , added.

Now, a second manufacturing method of a sound insulation unit according to the invention 10 described.

An absorbent body 18 , made of felt or textile, coming from the station 62 is issued, wherein the absorbent body 18 grainy elements 24 and connecting elements in its upper region 22 is cut to the required dimensions and placed in a contact heating station, which consists of two heating plates.

At the same time becomes a base body 34 , made of felt or textile, coming from the station 60 is output, wherein the base body 34 additional grainy elements 38 and connecting elements in its upper region 36 has cut to the required dimensions and introduced into a second contact heating station.

The plates are heated above the melting temperature of the connecting elements, causing them to melt. Namely, the upper plates are in contact with the respective upper regions 22 and 36 and transfer their calories across the entire thickness of the upper regions 22 and 36 ,

As a result, the connecting elements melt.

The preforms thus cut are then placed in a cold mold, which is set at a temperature below 30 ° C, in particular of about 15 ° C, and arranged one above the other.

The mold is closed, which causes the part 10 is formed.

An excess of connecting elements from the upper region 36 of the base body 34 migrated through the lower region 26 of the absorbent body 18 and thus ensures, after cooling, the sticking of the structures 14 and 16 , which makes the part 10 is formed.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2006/0113146 [0010]
• WO 2013026847 [0012]

Cited non-patent literature

• ISO 13320-1 [0043, 0069]
• C Langlois, R Panneton, and N Atalla, "Polynomial for quasi-static mechanical characterization of isotropic materials" J. Acoust. Soc. At the. 110, 3032-3040 (2001) [0061, 0083]

Claims (15)

Acoustic insulation unit (10) for a motor vehicle, comprising: - a mass-spring structure (14); - an absorbent structure (16) mounted on the mass-spring structure (14), characterized in that the absorbent structure (16) comprises an absorbent body (18) having a plurality of entangled and / or bonded fibers (20) wherein the absorbent body (18) has in its thickness: * a porous upper region (22) comprising granular elements (24) distributed between the fibers (20); * a porous lower region (26) without dispersed granular elements (24) or having a concentration of distributed granular elements (24) less than the concentration of distributed granular elements (24) of the porous upper region (22); wherein the porous upper region (22) has an air passage resistance of at least 100 Nm ^-3. ss above the air passage resistance of the porous lower region (26), the porous lower region (26) having an air passage resistivity over 15,000 Nm ^-4 . s. Unit (10) after Claim 1 wherein the mass-spring structure (14) comprises a base body (34) comprising a plurality of entangled and / or bonded fibers (35), the base body (34) having in its thickness: - a dense upper region (36 ) having additional granular elements (38) distributed between the fibers (35) and molten interconnecting elements (42) connecting the additional granular elements (38) to the fibers (35); - Having a porous elastic lower region (40) without distributed additional granular elements (38) or a concentration of distributed additional granular elements (38), which is less than the concentration of distributed additional granular elements (38) of the dense upper region (36). Unit (10) after Claim 2 wherein the density of the additional granular elements (38) present in the dense upper region (36) is higher than the density of the granular elements (24) present in the porous upper region (22). Unit (10) according to one of Claims 2 or 3 , wherein the area-related mass of the dense upper region (36) is greater than 100 g / m ² and in particular between 100 g / m ² and 4000 g / m ² . Unit (10) according to one of Claims 2 to 4 wherein the connecting members (42) of the dense upper region (36) are formed of a molten fusible powder or molten fibers. Unit (10) according to one of Claims 2 to 5 wherein the thickness of the dense top region (36) is less than the thickness of the porous elastic bottom region (40). A unit (10) as claimed in any one of the preceding claims, wherein the air passage resistance of the porous upper region (22) is greater than 250 Nm ^-3 .s and more particularly between 250 Nm ^-3 .s and 1500 Nm ^-3 .s. A unit (10) according to any one of the preceding claims, wherein the thickness of the porous upper region (22) is less than 15mm. A unit (10) according to any one of the preceding claims, wherein the bending stiffness of the porous lower region (26) is above 0.1 N.m. A unit (10) according to any one of the preceding claims, wherein the absorbent body (18) is integrally formed, the base body (34) being integrally formed. A method of manufacturing a vehicle noise reduction unit (10), comprising the steps of: forming an absorbent structure (16) comprising: providing an absorbent body (18) having a plurality of entangled and / or bonded fibers (20); integrating granular Elements (24) between the fibers (20) of a porous upper region (22) of the absorbent body (18); Maintaining a porous lower region (26) of the absorbent body (18) without dispersed granular elements (24) or a porous lower region (26) of the absorbent body (18) having a concentration of distributed granular elements (24) which are lower is the concentration of distributed granular elements (24) of the porous upper region (22); wherein the porous upper region (22) has an air passage resistance of at least 100 Nm ^-3. ss above the air passage resistance of the porous lower region (26), the porous lower region (26) having an air passage resistivity above 15,000 Nm ^-4 . * Connecting the absorbent structure (16) with a mass-spring structure (14). Method according to Claim 11 apparatus comprising a step of forming the mass-spring structure (14), comprising: - providing a base body (34) comprising a plurality of entangled and / or bonded fibers (35); - Integrating distributed additional granular elements (38) and connecting elements (42) between the Fibers (35) of an upper region of the base body (34), maintaining a porous elastic lower region (40) without distributed additional granular elements (38) or a porous elastic lower region (40) comprising a concentration of distributed additional granular elements (38 ), under the concentration of distributed additional granular elements (38) of the upper region; - at least partially melting the connecting elements (42) to form a dense top region (36). Method according to Claim 12 comprising, between the steps of integrating and the step of melting, placing the absorbent body (18) provided with the granular elements (24) on the base body (34) provided with the additional granular elements (38) and the connecting elements ( 42), wherein the step of melting comprises simultaneously heating the absorbent body (18) provided with the granular elements (24) and the base body (34) provided with the additional granular elements (38) and the connecting elements (42), includes. Method according to Claim 13 wherein said joining step is performed after the simultaneous heating of the absorbent body (18) provided with the granular elements (24) and the base body (34) provided with the additional granular elements (38) and the connecting elements (42), wherein the joining step comprises inserting the absorbent body (18) provided with the granular elements (24) and the base body (34) provided with the additional granular elements (38) and the connecting elements (42) into the cavity (134 ) of a mold (132) and comprising thermally shaping the absorbent structure (16) and the mass-spring structure (14) in the cavity (134) of the mold (132). Method according to one of Claims 12 to 14 wherein the bonding comprises attaching the upper region (36) of the base body (34) to the lower region (26) of the absorbent body (18) by penetrating the at least partially fused interconnecting elements (42) of the upper region (36) of the base body (36). 34) into the lower region (26) of the absorbent body (18).

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