DE3430775A1 - CARPET PART, METHOD FOR ITS PRODUCTION AND USE - Google Patents

Description

Carpet part _t Process for its manufacture and its use

ig The present invention relates to carpet parts for Sound insulation that is loosely inserted into motor vehicles and reduces the interior noise level of motor vehicles.

Ig Low interior noise levels in motor vehicles, especially in passenger cars, are an important selling point with today's demands on noise comfort. The industry therefore has a wide variety of materials and systems for soundproofing passenger vehicles

2Q, which are now installed as standard.

Due to the dimensions of the passenger compartments and the excitation via corresponding frequencies from the spectrum of the Motors are used in 4-cylinder vehicles in particular

2g range of ignition frequency (second engine order) disruptive Causes humming in the passenger cabin when measuring levels as a function of the speed as clearly audible resonance vibrations. It is therefore a general goal of measures to reduce noise

OQ isolation to avoid such resonance vibrations. The level increase with the speed should be as uniform as possible.

From the literature (Betzhold, Ch. "The influence of the air qp. Soundproofing on the interior noise of road vehicles ", Glaser's Annalen, Volume 87, Issue 2, February 1963,

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Pp. 63 to 66, Georg Siemens Verlagbuchhandlung, Berlin and Bielefeld; Kurz, K. "For the interpretation of some typical frequency analyzes of vehicle interior noises", ditto, Volume 87, Issue 4, April 1963, pp. 207 to 210; Guideline VDI 2574 "Instructions for the evaluation of interior noise in motor vehicles"), the relationship between engine speeds and resonance vibrations in the passenger compartment is known. It is also known that the resonance frequency of sound insulation systems, which are constructed as mass-spring systems, should be outside the interfering engine frequencies. With a built-in depth of the sound insulation that is usually fixed by the vehicle manufacturer, shifts in the resonance frequency, in particular with a largely uniform thickness of the insulation layers, can only be carried out to a very limited extent by increasing the mass. Another possibility for "smearing ^{11 of} the resonance frequency" is to make the plastic foam layer of an insulating part of different thicknesses and to provide embossments or elevations in it (cf. DE-PS 20 64 445).

In the interests of increasing comfort and taking into account the most efficient installation possible on the belt, they are increasing Decorative fittings such as carpets are also used as part of sound insulation. This possibility is described in a number of patents and patent applications. The use of Carpets with sound and heat insulating sublayers, also in connection with an additional soft elastic Spring, such as foam, is known per se. Information on this can be found in DE-OS 30 43 674 "Extrudables Compound for the production of a thermoplastic, sound and heat insulating sub-layer for carpets and carpets with such an extrudable backsheet and process for making it ". Find other similar solutions DE-OS 31 08 567 "Sound-insulating carpet

-δι and process for its production "and in the DE-OS 28 09 347 "Method of making a molded sound-insulating Floor or wall covering and the product obtained thereby ".

In the three mentioned publications, only information about the spatial arrangements of such types is given Systems made or special manufacturing processes described. The problem of a shift in resonance frequencies If the installation depths remain the same, no treatment is given and no solutions to this problem are suggested.

In DE-OS 25 38 607 "sound insulating material" is a

IQ describes a three-layer structure, consisting of carpet / thermoplastic / foam, whereby it is stated that the thermoplastic and foam layers can also be interchanged, but again all information on the shifting of resonance frequencies to eliminate humming noises is missing.

The same also applies to DE-OS 31 04 835 "Back-foamed textile surface cladding and methods for its Production ", which describes an underlayer, which can also be a combination of different foams. However, the special problem of shifting the resonance frequency out of the range of the engine noise does not arise addressed. Furthermore, DE-OS 20 06 741 should be mentioned, the content of which is largely DE-OS 25 38 607 anticipates, and which has the title "Multi-layer sound-absorbing component for a

QQ continued body ". This publication dates from the specific area of the automotive industry, but does not contain any suggestion of a solution to the problem the shift of disruptive resonance frequencies.

gc In all of the publications just mentioned, the acoustic Effect of the various arrangements as a lump sum as sound

insulation. The person skilled in the art will not find any information in them about possibilities for optimization with regard to Position or shift of the resonance frequencies with the aim of avoiding disruptive resonance vibrations. 5

The invention is now based on the object, with predetermined installation depths, regardless of whether this one have uniform or uneven thickness distributed over the surface, such a sound insulation system in Specify the shape of a decorative or carpet part, its internal structure in a simple manner to the special acoustic conditions of the respective vehicle can be adapted, so that the resonance frequency of such Part of the insulation outside the interfering motor frequency

! 5 lies.

This object is achieved by carpet parts, processes for their manufacture and their use, as described in the Claims are described and will become apparent to those skilled in the art from the following description.

According to the invention, a sound insulation part in Form of a carpet part created, which acts as a mass-spring system and in which layer-by-layer changes the flow resistances in the visco- or soft-elastic Layer, which serves as the spring of such a system, the necessary shifts in the resonance frequency of the mass-spring system can be achieved. The carpet parts according to the invention are loosely and form-fittingly on a vehicle panel laid out as part of the Doppelwandbzw. The mass-spring system works. Is on the vehicle sheet an at least two-layer soft or viscoelastic layer, that of foams with different flow resistance is formed. This double layer is followed by a counterweight of the double wall system, if possible pliable heavy layer, which on its front side, for

' ^: .' ■ "- ' 3430775 -ιοί showing the passenger compartment, with the carpet as decoration and exterior finish.

The foam layers in the soft elastic layer can be arranged depending on the position of the resonance frequencies of the passenger compartment so that on the vehicle panel a layer with low flow resistance corresponding to a relatively low airborne sound absorption Passage of the sound is applied, on which a relatively thin layer of a foam with high flow resistance follows, which enables effective sound absorption even with a thin layer.

Such an arrangement forms a deeply tuned ingot 5 spring system, which is preferred for such motor vehicles, whose resonance frequencies are in other ranges.

Are the resonance frequencies in an order of magnitude, for example the resonance frequencies of the one just described System correspond, it is desirable to shift the resonance frequency to higher frequencies without Installation depth and mass (weight) relations must be changed. It's a particularly important benefit of the present invention that the invention is possible in a simple manner that the flat called foam layers. It comes then the foam layer with high flow resistance the sheet metal to lie, and the foam layer with lower Flow resistance joins and is of

go to the final flexible or rigid heavy layer followed with the carpet. The rearrangement of the two foam layers surprisingly a shift in the resonance frequency over several thirds is achieved.

This possibility of shifts the

Resonance frequencies by utilizing the acoustic effects of different flow resistances in coupled Foam layers, especially in combination with carpet / heavy layer, was previously unknown.

The chemical nature of the foams used is per se of no importance for the present invention. It can all foam materials are used that have a IQ enable practical manufacture of the parts and for such Purposes. However, because of their good processability and wide range of variation, there are Polyurethane foams are particularly suitable.

2g The invention is explained in more detail below with reference to the figures.
Show it:

Fig. 1 shows a carpet part, which has a deeply tuned mass-spring system represents in which the foam

Fabric layer with low flow resistance as the bottom layer of the carpet part on the vehicle sheet is applied;

ok Fig. 2 shows the course of the sound insulation as a function the frequency for a system according to FIG. 1;

Fig. 3 shows the course of the sound insulation as a function of the frequency in a system in which

OQ compared to the system shown in FIG

the two layers of foam rearranged became.

Referring to Fig. 1, there is one according to the invention op carpet part in one possible embodiment from the following Layers (seen from the passenger compartment): A carpet layer 1, one, preferably flexible,

Heavy layer 2, a thinner foam layer with high flow resistance 3 and a thicker foam layer with low flow resistance 4. Such a carpet part is placed loosely on the sheet metal of a vehicle, which is denoted by 5 in the figure. The carpet 1 serves as a decoration and forms the external conclusion to the passenger compartment. Such a carpet part forms a sound-insulating double wall system in connection with the vehicle sheet metal. The thickness of the spring, which in this case consists of the two foam layers 3 and 4 with different flow resistance, is usually used as the thickness or distance between the two wall shells. Since the carpet parts according to the invention are preferably placed loosely in the vehicle, the friction damping between the foam and the vehicle sheet metal is first used for sound insulation. As a result, energy is already extracted from the sound energy transmitted as airborne sound. Further relative movements arise at the boundary layer between the foam with low and d ^em foam with high flow resistance. The boundary layer between the foam with high flow resistance and the flexible heavy layer remains quasi at rest, since the flexible heavy layer hardly performs any significant bending vibrations. The extraction of energy through airborne sound absorption is then effectively noticeable in the foam with low flow resistance and in the foam with high flow resistance also in the airborne sound insulation. Ultimately, the combination described results from exploiting the various energy-extracting effects

ag a deeply coordinated mass-spring system with high sound insulation. The resonance frequency of such a structure can be determined in a known manner (see e.g. Cremer, L. "Vorlesungen on technical acoustics ", Springer-Verlag, Berlin-Heidelberg-New York, 1971). The course of the

or sound insulation as a function of frequency is shown in Fig. 2 shown.

Should the resonance frequency be shifted to higher frequencies for a specific task without that the installation depth and mass (weight) relations are changed, this can be done in a simple manner, that the foam layer with high flow resistance is arranged so that it comes to rest on the sheet. This is followed by the foam low flow resistance, followed by the heavy layer with the carpet. Fig. 3 shows that surprisingly a shift in the resonance frequency over several thirds can be achieved.

The heavy layer can in any case be made flexible. For reasons of a desired crush resistance, however, it may be necessary, particularly in the case of the insulation system described last, that the heavy layer must be adjusted to be more rigid. As a result, the position of the resonance frequency that has been set does not change, but only the course of ^{the insulation is influenced as a} function of the frequency in the sense of a reduction in the insulation effect. This is thus influenced by the rigidity or flexibility of the effective heavy layer. This is related to the changed radiation behavior of the more rigid compared to the more flexible heavy layer.

The effectiveness of the sound-absorbing layer immediately behind the carpet only depends on the weight per unit area and bending softness. It is from DE-OS 20 06

QQ known that the basis weight ^{should be greater than 4.0 kg / m 2} , while according to DE-OS 28 09 347 it should be in the order of 2.0 kg / m ² . According to the invention, the sound-absorbing heavy layer has a minimum weight per unit area of 2.0 kg / m ² . The effective basis weight becomes

gg added the carpet mass.

A preferred material for the layers with low or high flow resistance are foams, preferably cut foams. In a modification, however, it is also possible to use the layered foams by using fleece or similar textile materials to replace the same acoustic properties. The carpet can also be made of any textile or synthetic fiber knitted fabric be replaced. When properly dimensioning these other materials in terms of effective Weight per unit area, can then be the otherwise required heavy layer do not apply if the other materials are sufficiently flexible due to the specifically dimensioned basis weight is replaced by the acoustic effect.

The present invention is based on the knowledge that layers and rearrangements of materials with different (low and high) flow resistance resonance frequency shifts to such an extent enable numerous insulation problems to be solved in a novel way with the same installation depths can be.

The absolute values of the physical parameters of the individual layers can vary within wide ranges, an adaptation to the respective problem is possible for the person skilled in the art. As already stated, the individual layers can also have any chemical structure, as long as the principles according to the invention are adhered to be realized.

In the case of foams, foams are considered to have a high

Flow resistance e.g. »foams with small pores and relatively high density suitable. Foams with low flow resistance have a larger volume structure gg on and are lighter.

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Closed-pore foams are also available as foams with high flow resistance Foams are suitable, while foams with low flow resistance are those which are open-pored. In this case, the foams can have the same density, preferably a density of 25 to 25o kg / m, in particular from 25 to 70 kg / m.

Rather, it is essential that according to the invention different There are flow resistances. 10

For common applications, for example, the flow resistances of the layers with high flow resistance are included at least 6 χ Io Nsm, preferably at 6.9 χ 1o Nsm On the other hand, the flow resistances of the layers with low flow resistance are in a range of

3 -4 -4

5 to 2oo χ 1o Nsm, preferably between 5 and 3o Nsm

3 -4

and especially at 5.3 χ 1o Nsm. That is, in terms of magnitude the higher flow resistance should be about a hundred to a thousand times as great as the lower Flow resistance.

The manufacture of the carpet parts according to the invention can done in different ways. On the one hand, it is of course possible to use the individual layers of the invention To connect carpet parts by gluing. Of course, only individual layers can also be used of the layer structure are glued to one another, while the others are e.g. Wise men are connected.

In addition to gluing, the carpet parts according to the invention can however, they can also be produced by back-foaming or by other methods of foam production.

These methods are in the claims in general

In my form, it should be noted that the individual processes can be used in almost any way Form can be combined.

In the manufacture of the carpet parts according to the invention by back-foaming in closed molds, the sound-absorbing, flexible heavy layer underneath the

The function of a barrier that prevents passage 5

prevented from foam through the carpet. The foam layers can therefore in a known manner by foaming in closed molds using integral foam material can be made, or they can too

in individual work steps through step-by-step back-10

foaming and / or gluing prefabricated, deformed Parts are manufactured. It has proven to be advantageous, for example, to use semi-finished products made from the carpet of the subsequent heavy layer and, if necessary,

also a foam layer with high flow resistance exist. Such a semi-finished product is then entered in a known manner in a form and with easier Foam with lower flow resistance is back-foamed.

A reversal is also conceivable, which consists in the semi-finished product having a high flow resistance instead of the foam has as a third layer a foam with low flow resistance and with one type of foam is back-foamed, resulting in a foam with high flow resistance leads.

The foaming can also be carried out in such a way that one half of an open mold consists of a semi-finished product from carpet and subsequent heavy layer and, if necessary,

insert one of the foam layers. In the other Half, foam is injected over the entire surface of the mold half so that it is coated over the entire surface is. Preferably for. This section of the process uses a slow-foaming low-expansion foam. After a a certain initial reaction has been waited for, a light foam mixture is immediately added to this low expansion foam poured with the help of a separate machine. Here, too, the initial reaction is waited for, and then again the mold is closed, so that in the final reaction process carpet, heavy layer and Foams with different levels of flow resistance are connected to one another.

Another variant of the method is that upper gO and lower mold halves are tempered differently, and that instead of what is customary with polyurethane foams chemical propellants such as water, a physical propellant with a lower boiling point such as E.g. methylene chloride (boiling point 40 to 42 ° C) is used, gg The lower mold half is now brought to a temperature below the boiling point, in the specified case to about

Brought 20 to 25 ° C, and the upper half of the mold to 45 to 50 ⁰ C, ie to a temperature above the boiling point Vapor pressure only small pores are generated, which lead to a foam with a relatively high flow resistance. In contrast, the boiling point in the upper half of the mold is exceeded by the heating of the half of the mold, so that the methylene chloride changes into the vapor phase. As a result, large-volume pores are generated, which overall lead to a foam structure with low flow resistance. When the mold halves are closed, the two foams are connected to one another.

The carpet parts according to the invention can be used as molded parts are carried out, however, with the help of the specified method, a design as circuit board parts is also possible is.

The progressiveness of the construction of the invention Carpet parts consists in the fact that despite mandatory limits of the installation depth and specified by the vehicle manufacturer Mass limitation for sound insulation through layered foams with different flow resistance a resonance frequency can be set that would otherwise be used when using foams with over the entire The same physical-acoustic properties as seen from the spring depth would not be adjustable.

The structure according to the invention is an economical, standard applicable solution offered that the requirement for a sound insulation with relatively low Installation depth and surface area with variably adjustable

gc resonance frequencies met.

Claims (6)

430775 PATENTANWÄLTE Dipl.-Ing. H. MITSCHERLICH Dipl.-Ing. K. GUNSCHMANN Dipl.-lng.Dr.rer.nat. W. KÖRBER Dipl.-Ing. J. SCHMIDT-EVERS Dipl.-Ing. W. MELZER EUROPEAN PATENT ATTORNEYS Telephone (089) 29 66 84-86 Telex 523 155mitshd Telegramme Patentpaap Telecopier (089) 29 39 63 Psch-Kto. Mchn. 195 75-803 EPA acct. 28 000 206 Steinsdorfstrasse 10 D-8000 Munich 22 August 21, 1984 Me / sh Company Dr. Alois Stankiewicz GmbH 311o Adelheidsdorf Carpet part, -Process for its production and its use Patent claims 1. Carpet part for sound insulation, especially in motor vehicles, made of a carpet and a multilayer Plastic underlayer, characterized in that it consists the end: a) a carpet, b) a heavy layer arranged underneath or forming a uniform whole with the carpet and c) a combination of foam or fleece layers with different flow resistances arranged underneath . 2. Carpet part according to claim 1, characterized in that that the combination of foam layers comprises two different foam layers of which one has a low flow resistance and the other has a high flow resistance. 3. Carpet part according to claim 2, characterized in that that to produce a deeply tuned mass-spring system with high sound insulation the order of Layers is chosen as follows: a) carpet, b) heavy shift, C ₁ ) foam layer with relatively high flow resistance and c_) Foam layer with relatively low flow resistance. 4. Carpet part according to claim 2, characterized draws that the sequence to produce a relatively highly tuned mass-spring system with high sound insulation of the layers is selected as follows: a) carpet,
b) heavy shift, C ₁ ) foam layer with relatively low flow resistance and c “) Foam layer with relatively high flow resistance. 5. Carpet part according to one of claims 1 to 4, characterized in that the heavy layer is flexible Heavy shift is. gg 6. Carpet part according to one of claims 1 to 4, in particular according to claim 4, characterized in that the Heavy layer is a rigid heavy layer. 7. Carpet part according to one of claims 1 to 6, characterized in that the sound-absorbing heavy layer has a minimum weight per unit area of 2.0 kg / m ² , the carpet weight per unit area being added to the overall sound-absorbing heavy layer. 8. Carpet part according to one of claims 1 to 7, da- characterized in that the foams with different flow resistance are cut foams which may be deformed will. 9. Carpet part according to one of claims 1 to 8, characterized in that it is a molded part. 10. Carpet part according to one of claims 1 to 8, characterized characterized in that it is a circuit board part. 11. Process for producing a carpet part according to one of Claims 1 to 10, characterized in that a semi-finished product which has layers a) and b) or layers a), b) and c.) Is back-foamed in closed form or - placed on a two-layer or single-layer partially reacted, not yet hardened foam with layer b) or C ₁ ) facing down. 12. The method according to claim 11, characterized in that the layers C ₁ ) and c ") are formed by continuously changing the mixing ratio during back-foaming. 13. The method according to claim 11, characterized. that one forms the layers in the open form in that a second foam is placed on the surface of an -4-yawed foam is sprayed onto the first layer. 14. The method according to claim 11 or 13, characterized in that that the semi-finished product is placed on a not yet cured two-layer foam. 15. The method according to claim 13 or 14, characterized in that that the two-layer foam is produced by a physical one when foaming Propellant used and the lower and upper mold halves heated differently. 16. The method according to claim 15, characterized in that a chemically uniform foam is used. 17. The method according to claim 15 or 16, characterized in that that to form the layer with high flow resistance, the lower mold half to a temperature Tempered below the boiling point of the physical propellant and to form the layer with low Flow resistance the upper mold half to a temperature above the boiling point of the physical used Propellant heated. 18. The method according to claim 17, characterized in that methylene chloride is used as the physical blowing agent and the lower mold half is heated to a temperature of 20 to 25 ^° C. and the upper mold half is heated ^{to a temperature of 45 to 50 ° C.} 19. Process for the production of a carpet part according to one of claims 1 to 10, characterized in that it is done by gluing individual or all layers with each other. 20. Use of a carpet part according to one of claims 1 to 10 as loose and form-fitting in a motor vehicle inserted sound insulation part. 21. Use of a carpet part according to claim or 4 for the sound insulation of motor vehicle passenger compartments