NL2013875B1

NL2013875B1 - Sound absorbing element, and method of production thereof.

Info

Publication number: NL2013875B1
Application number: NL2013875A
Authority: NL
Inventors: François Van Gilst Willem; Jacobus De Koning Martijn; Adrianus Marinus De Vries Antonius
Original assignee: Polytec Composites Nl B V
Priority date: 2014-11-25
Filing date: 2014-11-25
Publication date: 2016-10-11
Also published as: EP3224087A1; WO2016085333A1

Abstract

The present disclosure relates to a sound absorbing element, production thereof, as well as use thereof, for example in an automotive environment. The element is made of a mat of sound absorbing material and may comprise plurality of areas comprising or defining a depression, indentation or pit, where the mat has a locally reduced thickness. Additionally or alternatively, the element may comprise a plurality of draining through holes, such as perforations and/or microperforations.

Description

SOUND ABSORBING ELEMENT, AND METHOD OF PRODUCTION THEREOF

The present disclosure relates to a sound absorbing element, production thereof, as well as use thereof, for example in an automotive environment.

Conventional sound absorbing elements in automotive environments or technical fields are known to sometimes be manufactured from a sheet or mat 1 with considerably large box shaped protrusions, as shown in figures 1 and 2. Sound G is reflected in and between the boxes 2, and more and more of the energy of sound waves G is absorbed at each impact in, at against or between the boxes 2, to reduce noise from for instance a car engine. Also, the tops of these boxes 2 is known to vibrate with impinging sound waves G, to absorb energy of the sound waves G, as depicted schematically in figure 2. Theoretically, such prior art configurations may perform to design criteria with respect to sound or noise damping.

However, the height h of the boxes 2 according to this prior art can be up to and even higher than 15 mm. This structural height h results in disadvantages with respect to available space in a vehicle’s motor compartment; sufficient room may not be available for such large boxes.

More compact configurations that are required to exhibit a sufficient sound damping and also can sufficiently withstand fluid impregnation, have eluded skilled persons up to now, i.e. before the filing date of the present disclosure, or at least the inventors of the present disclosure are not aware of any prior art publications that would enable the skilled person to provide and improved, and/or more compact sound absorbing element, that would also comply with requirements regarding sound absorption and repelling fluids from being drawn into the interior of the sound absorbing elements during prolonged periods of time.

According to the present disclosure, sound absorbing elements are provided according to several aspects of the present disclosure and in different embodiments, as well as methods for the production or manufacture of these sound absorbing elements, and further also another aspect of the present disclosure relates to the use of such sound absorbing elements.

More in particular, the present disclosure relates to a sound absorbing element, comprising in a first aspect: a mat of sound absorbing material; a plurality of compacted thinner areas, where the plate or mat is locally made thinner in case of a formed plate or is compacted in case of for example a foam mat; and a plurality of draining through holes. According to this aspect of the present disclosure, either the areas and/or the draining holes are expected achieve that sound dampening is improved through or in the depressions, indentations or pits and/or in or at the draining through holes. The draining through holes may additionally secure that water or other fluid can be drained from a top surface of the sound absorbing element, which top surface may - in certain embodiments - be directed towards a noise source, such as the motor of a motor vehicle. If the depressions, indentations and/or pits are arranged to coincide with the draining through holes, naturally the thinner areas also have the function of discharge of water and/or other liquid, preferably before any of the liquid is able to penetrate into the mat or plate of sound absorbing material. Consequently, providing such draining through holes would have run against the natural instincts of skilled persons, who would have dismissed the notion of through holes without a second thought, because of the anticipated detrimental effect on the sound absorbing properties of the sound absorbing element. However, surprisingly, the draining through holes have proven to contribute an extremely positive effect on sound absorption.

The areas in the mat of sound absorbing material of the sound absorbing elements according to this aspect of the present disclosure define indentations or pits with respect to the original and/or surrounding thickness of the mat outside of the indentations or pits. The mat can be formed by a plate, which can be anticipated to be more rigid than a mat. In these pits, sound waves are sufficiently damped. The areas, defining such depressions, indentations or pits are not necessarily areas with a reduced thickness and an associated higher density, but the depressions, indentations or pits may be formed at production of the mat, or plate, of sound absorbing material. The notion of indentations or pits runs against the natural instincts of the skilled person, in view of the fact that the prior art, as far as currently known to the inventors of the present disclosure, is entirely restricted to articulating or form shaping of mats, sheets or plates or sound absorbing material to exhibit sound damping pill or box shaped protrusions.

At the same time, in this aspect of the present disclosure, providing both the indentations or pits associated with the areas of the mat and the draining through holes is anticipated to provide a much greater contribution to sound damping than a degree of damping that could have been expected on the basis of combining the indentations or pits at the areas with the draining through holes.

Additionally, an embodiment of this aspect of the present disclosure may exhibit the feature that at least some of the plurality of areas define a bulge relative to a surface of the mat or a depression. The indentation or pit may thus be confined to the thickness of the mat, or - as in this embodiment - form a bulge, preferably in a mat surface opposite the noise source, like the engine of the motor vehicle.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that at least some of the plurality of areas of the mat comprise at least one of the plurality of draining through holes. Thereby the indentations or pits, associated with the area of the mat, can form collectors for fluid, which can then be conveniently discharged through the draining through holes in or at the areas of the mat.

In a further aspect of the present disclosure is provided a sound absorbing element, comprising: a mat of sound absorbing material; and a plurality of areas, where the mat is locally compacted or made thinner. Areas, comprising or defining a depression, indentation or pit, may be those where the mat has a locally reduced thickness.

Additionally, an embodiment of this aspect of the present disclosure may exhibit the feature that at least some of the plurality of areas define a bulge relative to a surface of the mat or a depression.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that at least some of the plurality of areas of the mat comprise a draining through hole.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat comprises foam material. In such an embodiment, the foam material may be polypropylene foam, especially because the high temperature stability thereof, for instance at temperature in the region up to 140 °C or higher. For distinct applications and corresponding temperature and/or liquid absorption requirements, other materials may be employed with less, equal or more effect than polypropylene foam, such as polyamide, textile, LWT and the like.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat comprises perforations. Such perforations can have a dimension of at least approximately 1 pm up to several mm. It has proven possible to determine, if necessary through trial and error, a dimension of the perforations, at which water and/or other fluids do not flow into such perforations. The areas and the indentations or pits associated therewith have considerably larger dimensions, for example from several mm up to approximately at least 2-3 cm.

In a further aspect of the present disclosure is provided a sound absorbing element, comprising: a mat of sound absorbing material; and a plurality of draining through holes arranged in the mat.

Additionally, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat is locally compacted and/or made thinner.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that at least some of the plurality of areas and at least some of the draining through holes coincide in position relative to the mat.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that at least some of the plurality of areas define a bulge relative to a surface of the mat or a depression.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat comprises foam material. In such an embodiment the foam material may be polypropylene foam, because of the temperature stability thereof in specific uses, such as in the automotive branch.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat comprises perforations.

In a further aspect of the present disclosure is provided a method of producing a sound absorbing element, comprising: providing a mat of sound absorbing material; and forming or compacting a plurality of areas of the mat, whereby the mat is locally compacted or thinner, which is equally applicable to a plate instead of a mat.

Additionally, an embodiment of this aspect of the present disclosure may exhibit the feature that compacting a plurality of areas of the mat comprises punching the mat to define in at least some of the plurality of compacted areas a bulge relative to a surface of the mat or a depression.

In a further aspect of the present disclosure is provided a method of producing a sound absorbing element, comprising: providing a mat of sound absorbing material; and arranging a plurality of draining through holes in the mat.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat comprises foam material, such as polypropylene foam.

Additionally or alternatively, an embodiment of this aspect of the present disclosure may exhibit the feature that the mat comprises perforations. A further aspect of the present disclosure relates to a use of a sound absorbing element, for example in an automotive environment, comprising producing the sound absorbing element of any one or more than one of the above described aspects related to elements, by way of a method of any one or more than one of the above described aspects related to methods, wherein the sound absorbing element is mounted to a structure, such as a motor vehicle.

Based on the foregoing reference to the subject matter and objectives of the present disclosure in more generic terms, corresponding with the definitions in the appended claims, a full understanding of the subject matter and objectives of the present disclosure is considered to have been achieved, but in order to provide a more detailed guide to potential implementation of the teachings of the present disclosure, herein below an embodiment description is provided under reference to the appended drawings. Therein, the same or similar features, elements, components, aspects and/or functionalities can be referred to, using the same or similar reference signs. Prior to the following embodiment description, it is, however, noted here that the scope of protection of the present disclosure, as defined in the appended claims, should by no means be limited or restricted to any specific one of the features, elements, components, aspects and/or functionalities of the below described embodiments, in as far as appended independent claims are not limited to such specific features, elements, components, aspects and/or functionalities. Even the explicitly defined features in the appended independent claims could, within the scope of protection of the present disclosure, be replaced by alternatives and equivalents, in as far as thereby the same or similar functionalities are achieved as those, at which the present disclosure is directed. In the appended drawing:

Figures 1 and 2 respectively show a perspective view and a side view in the direction of arrow II in figure 1, of a prior art sound absorbing element;

Figure 3 exhibits (a step of) the method of production or manufacture of the sound absorbing element, wherein both the method and the sound absorbing elements are embodiments of the present disclosure in a first aspect;

Figure 4 exhibits (a step of) the method of production or manufacture of the sound absorbing element, wherein both the method and the sound absorbing elements are embodiments of the present disclosure in a second aspect;

Figure 5 exhibits an additional optional step of the method of production or manufacture of the sound absorbing element, to follow the step of either or both of figures 3 and 4;

Figure 6 exhibits an alternative step of the method relative to figure 3;

Figure 7 exhibits a sectional view of a sound absorbing element, resulting from the method according to Figure 6;

Figure 8 exhibits an alternative embodiment or aspect of the method according to the present disclosure, wherein specific elements or features are combined from figures 4 and 6;

Figure 9 exhibits a sectional view of a sound absorbing element, resulting from the method according to Figure 8;

Figure 10 exhibits a perspective view of an element resulting from the method that is schematically depicted in Figure 4;

Figure 11 exhibits a sectional view along arrow XI in figure 10, and further indicating a sound dampening effect thereof on impinging sound waves;

Figure 12 exhibits a perspective view of an element resulting from the method that is schematically depicted in Figure 3;

Figure 13 exhibits a sectional view along arrow XIII in figure 12, and further indicating a sound dampening effect thereof on impinging sound waves;

Figure 14 shows a car or motor vehicle, implying a field of use of sound absorbing elements, to which the present disclosure is directed; and

Figure 15 exhibits of perspective view on an underside of a car in the direction of arrow XV in Figure 14, in which underneath a motor compartment a sound absorbing element according to the present disclosure is provided.

In the embodiment of figure 3 other step in a method of producing the sound absorbing element, a mat 10 of sound absorbing material is provided on a support 11. The matter of sound absorbing material can be a foam material, in particular preferably polypropylene foam. Flowever, other materials may also prove to be applicable. A punch 12 is arranged opposite the support 11 and arranged for a reciprocating movement along arrow A. When reciprocatingly moved along arrow A, punch 12 forms an indentation 13 in the mat 10.

In a subsequent step, depicted in figure 4, a lance 14 is employed to go through a reciprocating movement along arrow B and pierce a draining through hole 15 in the compressed or compacted area of the mat 10.

The sequence of steps of the method according to the present disclosure in figures 3 and 4 can be reversed. Thereby, lance 14 will be arranged to pierce draining through hole 15 before compacting an area of mat 10 using punch 12. In this case, lance 14 will penetrate through mat 10 at a location, where no indentation 13 is formed yet. If, subsequently, punch 12 is employed to form indentation 13 of compacted mat material, punch 12 may be centred on draining through holes 15, that have previously been arranged in mat 10 by lance 14. However, punch 12 and lance 14 may alternatively be employed at different locations, but preferably indentations 13 and draining through holes 15 would be positioned to coincide.

Provided that the sound absorbing material can sufficiently repel fluid from penetrating into or impregnating the mat 10, the step of providing draining through holes 15 according to figure 4 can be omitted. Such omission of draining through holes would result in a sound absorbing element 16, depicted in figures 12 and 13. In particular in figure 13, a schematic representation is depicted on the manner in which sound waves G are damped. Such damping may be sufficient to realise predetermined requirements.

Likewise, the step of compacting mat material of figures 3 may be omitted, provided draining through holes 15 provide sufficient sound damping, which would result in the sound absorbing element 17 as shown in figures 10 and 11. In particular in figure 11, a mechanism of damping sound waves G is schematically shown, were such damping is at least partially performed within channels that are defined by the draining through holes 15.

Returning to the sequence of steps in figures 3 and 4, it is noted that an optional subsequent step can be performed, as shown in figure 5. In figure 5 it is schematically shown that needling can be performed. Using needles 18 having a diameter of anywhere between 1 μ meter or less and several millimetres, reciprocating penetration of needles 18 in the direction of either arrow C or arrow D can provide small perforations running from top surface 19 or bottom surface 20 of mat 10 into the interior of mat 10. Such perforations are preferably arranged not to penetrate and pierce through the entire thickness of mat 10, although this is not excluded from the scope of protection for the present disclosure. Likewise, figure 5 exhibits that plates 21, 22 can carry needles 18 to subsequently or simultaneously perform needling from above the top surface 19 or below bottom surface 20 of mat 10. It should be noted here, that needling from only above for only below mat 10 is also possible.

Figures 6 and 7 exhibit an embodiment, wherein compacted areas of mat 10 can be formed or shaped to define a bulge 23, preferably though not exclusively at a surface opposite a noise source, which is schematically represented by arrow G. To this end, support 11 is provided with pits 24, where a punch plate 25 carries a plurality of punches 12 and each of the punches 12 has a sufficient length or depth to be driven and retracted in the direction of arrow E into and out of mat 10 to compress or compact an area of mat 10 and simultaneously generate bulges 23 at locations corresponding with indentations 13.

In a most preferred embodiment, shown in Figure 9, the sound absorbing element 26 is produced to have both indentations 13 and draining through holes 15, at essentially coinciding locations over the surface of mat 10. In an exemplary embodiment of a production method shown in Figure 8, this can be achieved by using the carrier plate 25 with punches 12 of figure 6, augmented with piercing lances 14 from figure 4. Using a drive for a carrier plate 25, punches 12 with lances 14 can be spinal teeniest lead driven into, respectively through mat 10, to which end support 11 can be provided with accommodations 27 to accommodate lances 14 when driven along arrow F. Alternatively, singular punches 12 combined with singular lances 14 can also be employed, but this would increase the need for repeating punching penetrations in the directions of arrows A and B from figures 3 and 4.

Figures 14 and 15 schematically represent an application or use of the sound absorbing element in a motor vehicle, at the position indicated by arrow XV in figure 14, or figure 15 shows that such a sound absorbing element 29 can be employed as a cover at or over a motor compartment 30 of motor vehicle 28. At such a position, sound absorbing element 29 should preferably not allow impregnation or penetration of fluids, as this would result in deterioration of the sound absorbing properties thereof, and could also affect the structural integrity of the sound absorbing element 29.

On the basis of the preceding embodiment descriptions, further clarification in more detail is provided of the more generically defined features of aspects and embodiments of the present disclosure according to the appended claims. It should be noted here that scope of protection should not be interpreted as limited to any specific aspect a feature of the foregoing embodiment description or following from any of the views or representation is of the appended drawing. Even the specifically defined features of the appended independent claims could be replaced by alternatives and equivalents, which are for example not yet foreseeable to the inventors of the present disclosure at the time the present disclosure, even though the scope of protection for the present disclosure is in principle essentially limited to assemblies of features according to the appended independent claims. For example it is noted here that the expression that the mat is compacted does not necessarily mean that the a local increase in density is required, but in contrast that a locally thinner portion is provided, to define a depression or the like, relative to a surrounding thickness of the mat or plate. Although circular depressions are defined in the above described embodiment, referring to the appended figures, any other shape in frontal view on the mat or plate may also be realised, such as: triangular; pentagram, honeycomb, elliptical and the like. The same applies to the draining through holes, in that these can have one of a variety of cross sectional shapes. Also the mat does not need to be a mat, but can be a plate or the like. The material of the mat or plate does not necessarily have to be a foam, or even polypropylene foam, but a textile or plate or polyamide or LWT, et cetera, is likewise possible. Further the mat or plate can be impregnated using a water repellent substance, to increase the time before liquid penetrates into the mat or plate. The dimensioning of draining through holes, depressions, indentations and pits and/or the density thereof in relation to a spread thereof over the area occupied by the mat or plate can be designed to be optimised for specific and/or even selected frequency ranges of sound or noise, originating from - for example - the motor of a motor vehicle, in which the sound absorbing element according to the present disclosure may be employed.

Claims

A sound-absorbing element, comprising: - a mat of sound-absorbing material; - a number of areas which comprise or define an indentation, depression or well, where the mat has a locally reduced thickness; and a number of draining through holes.

The sound-absorbing element of claim 1, wherein at least some of the plurality of areas define a boiling relative to a surface of the mat or of a depression.

3. Sound absorbing element according to claim 1 or 2, wherein at least some of the number of areas of the mat comprises at least one of the number of draining through holes.

4. Sound-absorbing element, comprising: - a mat of sound-absorbing material; and a number of areas, which include or define depression, indentation or well, where the mat has a locally reduced thickness.

The sound-absorbing element of claim 4, wherein at least some of the plurality of areas define a boiling relative to a surface of the mat or of a depression.

A sound-absorbing element according to claim 4 or 5, wherein at least some of the plurality of areas of the mat comprise a draining through-hole.

A sound-absorbing element according to claim 4, 5 or 6, wherein the mat comprises oblique material.

The sound-absorbing element of claim 7, wherein the foam material is a polypropylene.

A sound-absorbing element according to any one or more of the preceding claims 4-8, wherein the mat comprises perforations.

A sound-absorbing element, comprising: - a mat of sound-absorbing material; and - a number of draining through holes which are arranged in the mat.

The sound-absorbing element of claim 10, further comprising a plurality of areas which include or define depression, indentation, or well where the mat has a locally reduced thickness.

The sound-absorbing element of claim 10 or 11, wherein at least some of the plurality of areas and at least some of the draining through holes coincide in position relative to the mat.

A sound-absorbing element according to claim 11 or 12, wherein at least some of the plurality of areas define a boiling relative to a surface of the mat or of a depression.

A sound-absorbing element according to any one or more than one of the preceding claims, wherein the mat comprises oblique material.

The sound-absorbing element of claim 14, wherein the oblique material is polypropylene foam.

A sound-absorbing element according to any one or more of the preceding claims, wherein the mat comprises perforations.

A method for producing a sound-absorbing element, comprising: - providing a mat of sound-absorbing material; and - forming or compacting a number of regions of the mat, wherein the mat has a locally reduced thickness.

The method of claim 17, wherein compacting a plurality of areas of the mat comprises striking the mat to define a boiling relative to a surface of the mat or depression in at least some of the plurality of compacted areas.

A method for producing a sound-absorbing element, comprising: - providing a mat of sound-absorbing material; and - making a number of draining through holes in the mat.

A method according to any one or more of the preceding claims 17-19, wherein the mat comprises oblique material, such as polypropylene foam.

A method according to any one or more of the preceding claims 17-20, wherein the mat comprises micro perforations.

Use of a sound-absorbing element, for example in an automotive application, comprising producing the sound-absorbing element according to any or more of one of claims 1-16 by means of a method according to any or more of one of claims 17- 21, wherein the sound-absorbing element is mounted on a structure, such as a motor vehicle.