U.S. patent application number 11/913909 was filed with the patent office on 2008-10-09 for element for sound insulation.
This patent application is currently assigned to Stankiewicz GmbH. Invention is credited to Thomas Freser-Wolzenburg, Manfred Hoffmann, Ulrich Milbradt.
Application Number | 20080245608 11/913909 |
Document ID | / |
Family ID | 36636923 |
Filed Date | 2008-10-09 |
United States Patent
Application |
20080245608 |
Kind Code |
A1 |
Freser-Wolzenburg; Thomas ;
et al. |
October 9, 2008 |
Element For Sound Insulation
Abstract
An element for sound insulation which forms the external
completion of a housing-like structure excited to oscillations, in
which there is located at least one sound emitter, which element is
formed of a shaped thermoplastic material, which is reinforced by a
glass fiber component of more than 35 weight percent based on the
total weight of the thermoplastic material and the glass fibers
component.
Inventors: |
Freser-Wolzenburg; Thomas;
(Adelheidsdorf, DE) ; Hoffmann; Manfred;
(Leitlingen, DE) ; Milbradt; Ulrich; (Wathlingen,
DE) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300, SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
Stankiewicz GmbH
Adelheidsdorf
DE
|
Family ID: |
36636923 |
Appl. No.: |
11/913909 |
Filed: |
May 9, 2006 |
PCT Filed: |
May 9, 2006 |
PCT NO: |
PCT/EP06/04326 |
371 Date: |
May 23, 2008 |
Current U.S.
Class: |
181/286 ;
181/294 |
Current CPC
Class: |
B60R 13/0861
20130101 |
Class at
Publication: |
181/286 ;
181/294 |
International
Class: |
E04B 1/84 20060101
E04B001/84 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2005 |
DE |
10 2005 021 299.9 |
Claims
1. Element for sound insulation, which forms the external
completion of a housing-like structure excited to oscillations, in
which there is located at least one sound emitter wherein the sound
emitter is formed of a shaped thermoplastic material which is
reinforced by a glass fiber component comprising more than 35
weight percent based on the total of the thermoplastic material and
glass fiber component.
2. Element according to claim 1, wherein the glass fiber component
comprises up to 65 weight percent of the total of the thermoplastic
material and the glass fiber component.
3. Element according to claim 1, wherein the thermoplastic material
is a polyolefin.
4. Element according to claim 3, wherein the polyolefin is selected
from the group consisting of polyethylene, polypropylene, derivates
thereof, and mixtures thereof.
5. Element according to claim 1, comprising a single piece.
6. Element according to claim 5, wherein the element forms a plate
or shell.
7. Element according to claim 6, comprising a foil lamination on at
least one side thereof.
8. Element according to claim 7, wherein the foil lamination is a
polyolefin non-woven material.
9. Element according to claim 1, having locally different
thicknesses.
10. Element according to claim 8, having a thickness in the range
from 5 mm to 10 mm.
11. Element according to claim 10, wherein the thickness to an edge
reduces to about 2 mm.
12. Element according to claim 1, wherein the housing-like
structure is of a plastic or sheet metal.
13. Element according to claim 1, comprising an underbody covering
for motor vehicles.
Description
[0001] The invention discloses an element for sound insulation
which forms the external completion of a housing-like structure
excited to oscillations, in which there is located at least one
sound emitter, which element is formed of a shaped thermoplastic
material, which is reinforced by means of a glass fiber component
of more than 35 weight percent.
[0002] The present invention relates to an element for sound
insulation which forms the external completion of a housing-like
structure excited to oscillations, in which at least one sound
emitter is located. This element for sound insulation is suited for
example in particular as underbody covering for motor vehicles,
such as motor cars.
[0003] Underbody coverings for motor vehicles serve on the one hand
for improving the aerodynamics of the underbody, and on the other
hand for sound insulation or sound damping. This sound protection
is of significance in particular in the case of diesel motors,
since these give rise to strong motor noises, whereby in many cases
maximum permissible noise emissions are exceeded.
[0004] From DE 199 20 969 A1 there is known a sound insulating
component which inter alia is used as floor covering of the engine
compartment or also as underbody covering for motor vehicles, and
is of a punched or perforated plate, which serves as carrier for a
porous cover layer. This cover layer may for example be a foamed
plastic. Clearly, the acoustic effect of this component, in
particular as underbody covering for motor vehicles, is however not
sufficient, because the employment of additional porous cover
layers is taught, which must be attached to the component on the
inner side.
[0005] WO 04/089592 A2 describes a method for the production of a
two-part roof covering for vehicles, which distinguishes itself
through very good characteristics with regard to the damping of a
head impact on the roof covering and through sound damping. The
damping material may be glass fiber reinforced polypropylene. The
roof covering is of a first part, which forms the side visible to
the passenger compartment and a second part, towards the roof, and
serves for mechanical reinforcement. The two parts are formed in
different tools and connected with one another in accordance with
conventional processes, such as for example by means of the
employment of hot melt adhesives. The roof covering is so attached
to the bodywork roof that there arises a hollow chamber between the
covering and the roof, through which the sound dampening is
attained.
[0006] It is thus the object of the present invention to improve
sound insulating elements in such a manner that they manifest an
extraordinarily low deployment weight, are simple to produce and do
not need additional airborne sound absorbing supplementary
elements, wherein a highest level of airborne sound absorption is
ensured.
[0007] This object is achieved with an element for sound insulation
in accordance with claim 1.
[0008] The present invention relates to an element for sound
insulation which forms the external completion of a housing-like
structure excited to oscillations, in which at least one sound
emitter is located, which is characterized in that it is of a
shaped thermoplastic material, which is reinforced by means of a
glass fiber component of more than 35 weight percent.
[0009] The dependent claims relate to preferred embodiments of the
element for sound insulation in accordance with the invention.
[0010] The Figures serve for explanation of the invention. There is
shown:
[0011] FIG. 1 a diagram for assessment of the airborne sound
damping of a sound insulation element in accordance with the
invention and a conventional element;
[0012] FIG. 2 an arrangement for measurement of airborne sound
damping and
[0013] FIG. 3 a diagram for the assessment of the equivalent
absorption area of an element in accordance with the invention in
comparison with known sound insulation elements.
[0014] The element in accordance with the invention has a
relatively high proportion of the glass fibers of more than 35
weight percent, whereby the glass fiber proportion may be up to 65
weight percent. As a rule, one employs relatively long cut glass
fibers having a length of at least 1 cm, which are surrounded with
a thermoplastic plastic material.
[0015] By means of the kind of interaction of the glass fibers with
the thermoplastic material in the composite, one achieves a high
flexural strength with a surprisingly low weight per unit area.
[0016] The thermoplastic material of the element for sound
insulation in accordance with the invention is normally a
polyolefin. In a preferred embodiment of the present invention the
polyolefin is selected from the group polyethylene, polypropylene,
derivates thereof and/or mixtures thereof, wherein a thermoplastic
material of polypropylene is particularly preferred.
[0017] The element for sound insulation in accordance with the
invention is in one part and is as such airborne sound absorbing
without, as is usual in the state of the art, having to be provided
with apertures. Surprisingly, the element for sound insulation is
also airborne sound damping in such quality that it compensates for
the degradation in the degree of sound damping resulting,
theoretically, from the difference in weight per unit area referred
to conventional sound insulation elements.
[0018] The element for sound insulation in accordance with the
invention may be present preferably in the form of a plate or
shell. For example, an airborne sound absorbing underbody covering
is formed by in one piece of a uniform plate of the element for
sound insulation in accordance with the invention to thicknesses
between 5 and 10 mm. The moulding in the tool is effected under
pressure and/or vacuum and heat in accordance with conventional
processes in such a manner that on the one hand the structurally
required shaping is produced and on the other hand by means of
pressing to locally different thicknesses an optimal airborne sound
absorption behaviour, adapted to the engine compartment noise, is
attained.
[0019] In a further embodiment of the present invention, an
increase of the values of the airborne sound absorption can be
attained by means of lamination of conventionally available foils,
in particular by means of foils having a weight per unit area in
the range of 100 g/m.sup.2 to 150 g/m.sup.2.
[0020] In accordance with the invention it has been found that the
element for sound insulation has extremely high flexural strength
and thus allows a compression at the edges of up to about 2 mm, so
that optimal prerequisites for installation at the housing-like
structure are provided. Despite this slight thickness, the
attachment holes do not tear.
[0021] As a rule, the housing-like structure is of a plastic or
sheet metal. The minimum spacing of the element forming the
external completion to the at least one sound emitter within the
housing-like structure, and the maximum spacing, are normally
predetermined by the structure. In a preferred form of exercising
the invention the sound emitter may be an engine.
[0022] In a particular embodiment of the present invention a
plate-like element for sound insulation is formed to a moulded part
and at least on one side, preferably on the outside, is provided
with a foil lamination, expediently, for reasons of recycling, with
a polyolefin non-woven material, in particular polypropylene
non-woven material.
[0023] In a further particular embodiment of the present invention
the element in accordance with the invention is employed as
underbody covering for motor vehicles. The shell-like underbody
covering formed of a plate has, due to its composite structure,
airborne sound absorbing characteristics, whereby the
conventionally usual supplementary absorbers on the inner side of
the covering can be omitted. With differently strong compression,
one can, in dependence upon the structural thicknesses which are
permitted by the motor car manufacturer, produce a broadband--in
terms of frequency--absorption characteristic.
[0024] Due to the airborne sound absorbing characteristics, the
underbody covering brings about not only a reduction of the noise
in the passenger compartment but also with regard to external
noise. The high flexural strength, or the high modulus of
elasticity, in the range between 0.8.times.10.sup.9 and
2.times.10.sup.9 N/m.sup.2, allows a compression, brought about by
pressing under heat, at the edge zones of up to about 2 mm through
which optimal prerequisites for the attachment to the bodywork with
only a few points are provided, so that also the holes needed for
the attachment do not tear.
[0025] The element for sound insulation in accordance with the
invention, in particular an underbody covering for example for
motor vehicles, distinguishes itself through an extremely high
flexural strength with a very slight weight per unit area and
favourable airborne sound absorbing characteristics, whereby a
supplementary airborne sound absorber applied on the inside to the
shaped part can be omitted.
[0026] Due to the two-sided absorption effect of the element for
sound insulation in accordance with the invention the exterior
noise, to the street side, and at engine compartment side is
significantly reduced, whereby at the same time the noise in the
passenger compartment is lowered. The reduced airborne sound
damping to be expected, in comparison with conventional elements
for sound insulation, due to the weight reduction, is compensated
by means of the airborne sound absorbing characteristics of the
element, without further measures.
[0027] In the following, an underbody covering in accordance with
the invention is investigated with regard to its sound damping
characteristics.
[0028] An underbody covering with locally different thicknesses
between 6 and 10 mm was produced. The underbody covering is of
glass fiber reinforced poly propylene with non-woven material
covering to both sides. This underbody covering was compared in a
test series for determination of the airborne sound damping, with a
mass produced, conventional underbody covering. These measurements
were effected in a modified sound damping test station which made
possible measurements on original parts, which usually in terms of
area are considerably smaller than required in accordance with DIN
measurements. Such a device is illustrated in FIG. 2.
[0029] In order to simulate installation situations as
realistically as possible, the test parts, as shown in FIG. 2,
where mounted with 40 mm spacing before a steel sheet, which was
fitted into a frame having very high sounds damping (mask). Through
this it was attained that airborne sound generated in the
transmission chamber can arrive at the receiving chamber
exclusively via the test surface.
[0030] The sound damping of an underbody covering in accordance
with the invention and of a conventional underbody covering were
measured in dB in dependence upon the third octave band middle
frequency (Hz). The measurement values and the curves resulting
therefrom are shown in FIG. 1. The conventional underbody covering
"series", characterized by curve 1, had a weight of 1170 g compared
with a "light underbody covering" in accordance with the invention,
designated by curve 2, having a part weight of 881 g.
Theoretically, there results therefrom a deterioration of the
degree of sound damping of 2.5 dB, whereby however the test results
are virtually the same.
[0031] Comparative investigations for airborne sound absorption
were carried out, wherein the so-called equivalent absorption area
was measured in a so-called alpha cabin. This alpha cabin
corresponds to a spatially reduced echo chamber and is suitable for
measurements from 400 Hz. The measured equivalent absorption area
is the (mathematical) product of test area.times.degree of
absorption.
[0032] With this test, the following underbody coverings were
tested. A light underbody covering A in accordance with the
invention (polypropylene-glass fiber reinforced, absorbing on both
sides with a mass of 645 g, a mixed fiber non-wover underbody
covering B (absorbing on both sides with a mass of 1151 g), an
underbody covering "series" C having airborne sound absorbing
elements ("non-woven in foil", additional weight approximately 190
g) and an underbody covering "series" D having a weight of 1170
g.
[0033] In the test, the parts were mounted at a spacing of 20 cm
from the floor in the alpha cabin in order to realistically
simulate the installation situation in a vehicle. The underside
corresponds to the carriageway side to the floor.
[0034] The series produced parts in conventional configurations
(see coverings B to D above), also with inlayed airborne sound
absorbing supplementary elements, were compared with an underbody
covering (see A) in accordance with the invention. In this respect
attention is directed to FIG. 3. The result shows clearly better
values for the underbody covering A in accordance with the
invention, even in comparison with a conventional covering of mixed
fiber non-woven material (B). This had a weight of 1151 g, compared
with the light, underbody covering in accordance with the invention
having a weight of only 645 g.
* * * * *