Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02444641 2003-10-16
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UNDER CARPET HEAT SHIELD
AND FLOOR PAN INSULATOR
TECHNICAL FIELD AND INDUSTRIAL
APPLICABILITY OF THE INVENTION
The present invention relates generally to the field of acoustical and thermal
insulation and, more particularly, to an under carpet shield and floor pan
insulator for a
vehicle.
1 o BACKGROUND OF THE INVENTION
Acoustical and thermal insulators and liners for application to vehicles are
well
1nlown in the art. These insulators typically rely upon both sound absorption,
that is, the
ability to absorb incident sound waves and transmission loss, that is, the
ability to reflect
incident sound waves, in order to provide sound attenuation. They also rely
upon thermal
shielding properties to prevent or reduce the transmission of heat from
various heat
sources (for example, engine, transmission and exhaust system), to the
passenger
compartment of the vehicle. Such insulation is coinmonly employed as an under
carpet
heat shield and a floor pan insulator.
Examples of acoustical and thermal insulation in the form of liners are
disclosed in
a number of prior art patents including U.S. Patents 4,851,283 to Holtrop et
al. and
6,008,149 to Copperwheat. As should be apparent from a review of these two
patents,
engineers have generally found it necessary to construct such liners from a
laminate
incorporating (a) one or more layers to provide the desired acoustical and
thermal
insulating properties and (b) one or more additional layers to provide some
rigidity to
allow ease of handling during installation.
U. S. Patents 6,092,622 to Hiers et al. and 6,123,172 to Byrd et al. disclose
needled
composite thermal and acoustical insulators containing various layers of
polymer fibers,
glass fibers, metallic foils, scrims and other facings. The metallic foil
facing is secured in
place with an adhesive. The needling construction of the batt requires
perforating the
interior insulating layer, thereby providing numerous passageways for the
passage of both
heat and sound.
While a number of adhesives, adhesive webs and binding fibers have been
specifically developed over the years to secure the various layers of the
laminates together,
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CA 02444641 2009-03-03
laminated shields and insulators have an inherent risk of delamination and
failure. The
potential is, in fact, significant mainly due to the harsh operating
environment to which the
shields and insulators are subjected. Many shields and insulators are located
near and/or are
designed to shield high heat sources such as the engine, transmission and
exhaust system.
As a result, the shields and insulators are often subjected to temperatures in
excess of 93 C
(200 F) which have a tendency to degrade the adhesives and binders over time.
Shields and insulators used for under carpet and floor pan applications also
carry
foot traffic and thus are subjected to repeated compression and decompression.
This activity
places very significant strain on the shields and insulators, often resulting
in adhesive failure
and delamination of the shield or insulator over time.
A need is therefore identified for an under carpet heat shield/floor pan
insulator
incorporating a nonlaminate acoustical and thermal insulating layer of polymer
fibers
suitable for use in the proximity of high temperature heat sources such as an
exhaust system
and particularly a catalytic converter and capable of providing the desired
acoustical and
thermal insulating properties. Advantageously, such an insulator also provides
the desired
mechanical strength and rigidity to allow simple and convenient installation
while also
providing a long service life characterized by reliable performance.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, there is provided an
under
carpet heat shield/floor pan insulator for a vehicle, comprising a nonlaminate
acoustical and
thermal insulating layer comprising polymer fiber selected from polyester,
polypropylene,
polyethylene, rayon, nylon and a mixture thereof, the layer having a
nonlaminate skin, the
skin having a density higher than that of an interior portion of the layer.
In accordance with another aspect of the present invention, there is provided
an
under carpet heat shield/floor pan insulator for a vehicle, comprising a
nonlaminate
acoustical and thermal insulating layer of substantially 100% polyethylene
terephthalate
nonwoven fabric, the layer having a nonlaminate skin, the skin having a
density higher than
that of an interior portion of the layer.
The nonlaminate insulating layer disclosed herein may be delamination-
resistant at
150 C for at least 330 hours.
The layer may have a density of about 40 to about 130 g/ft3.
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CA 02444641 2009-03-03
In accordance with another aspect of the present invention, there is provided
an
under carpet heat shield/floor pan insulator for a vehicle, comprising a
nonlaminate
acoustical and thermal insulating layer of substantially 100% polyethylene
terephthalate
nonwoven fabric, and a first metal foil facing layer over a first face of the
acoustical and
thermal insulating layer
Accordingly, there is disclosed an under carpet heat shield/floor pan
insulator for a
vehicle. That shield/insulator comprises a single, nonlaminate acoustical and
thermal
insulating layer of polymer fiber selected from a group consisting of
polyester,
polypropylene, polyethylene, rayon, nylon and any mixtures thereof. The
thermal insulating
layer is preferably a nonwoven fabric and may further include additional
fibers selected
from a group consisting of glass fibers and natural fibers to meet the
specific performance
requirements of a particular application.
In accordance with an embodiment of the present invention, the acoustical and
thermal insulating layer may include a relatively high density, non-laminate
skin of polymer
fiber along at least one face thereof. Still further, the insulator may
include a first metal foil
facing layer over a first face of the acoustical and thermal insulating layer.
Similarly, a
second metal foil facing layer may be provided over a second face of the
acoustical and
thermal insulating layer.
More specifically, the under carpet heat shield and floor pan insulator may
comprise
a single nonlaminate acoustical and thermal insulating layer of polymer fiber
selected from
a group consisting of polyester, polypropylene, polyethylene, rayon, nylon and
any mixtures
thereof that shows no signs of any thickness increase, delamination,
deterioration or any
undesirable effect which may affect performance when subjected to a
temperature of about
150 C (302 F) for a period of at least 330 hours. Still more specifically, the
shield/insulator
may comprise a nonlaminate acoustical and thermal insulating layer of
substantially 100%
polyethylene terephthalate.
The benefits and advantages of the present invention will become readily
apparent to
those skilled in this art from the following description wherein there is
shown and described
several preferred embodiments of this invention, simply by way of illustration
of some of
the modes best suited to carry out the invention. As it will be realized, the
invention is
capable of still other different embodiments and its several details are
capable of
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CA 02444641 2009-03-03
modification in various, obvious aspects all without departing from the
invention.
Accordingly, the drawing and descriptions will be regarded as illustrative in
nature and not
as restrictive.
BRIEF DESCRIPTION OF THE DRAWING
The accompanying drawing incorporated in and forming a part of the
specification,
illustrates several aspects of the present invention, and together with the
description serves
to explain the principles of the invention. In the drawing:
Figure 1 is a schematical side elevational view of one possible embodiment of
the
present invention; and
Figures 2-5 are schematical side elevational illustrations of other possible
alternative
embodiments of the present invention.
Reference will now be made in detail to the present preferred embodiment of
the
invention, an example of which is illustrated in the accompanying drawing.
DETAILED DESCRIPTION OF THE INVENTION
Reference is now made to Figure 1 showing a first embodiment of the under
carpet
heat shield and floor pan insulator 10 of the present invention. The shield or
insulator 10
comprises an acoustical and thermal insulating layer 12 of polymer fiber. More
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specifically, a single, nonlaminated layer 12 is provided with the necessary
mechanical
strength and rigidity to allow easy installation and the desired acoustical
and thermal
insulating properties. Advantageously, all of these benefits are achieved in a
light weight
insulator 10 which may even be used in compact vehicles where fuel economy
concerns
lead manufacturers to seek weight savings wherever possible.
The polymer fiber is not foamed and typically is a nonwoven fabric. The
polymer
fiber may be selected from a group of fibers consisting of polyester,
polypropylene,
polyethylene, rayon, nylon and any mixtures thereof. The acoustical and
thermal
insulating layer 12 is engineered to show no signs of any thickness increase,
delamination,
deterioration or any undesirable effect which may affect performance when
subjected to a
temperature of approximately 150 C (302 F) for a period of at least 330 hours.
Advantageously, such a shield or insulator 10 has a weight of between about 40-
130 g/ft2.
For example, the acoustical and thermal insulating layer 12 may comprise
substantially
100% polyethylene terephthalate.
A shield or insulator 10 made from 100% polyethylene terephthalate provides a
number of advantages when compared to a state of the art shield made from a
layer of
glass fibers sandwiched between layers of polyester. The shield or insulator
10 of the
present invention may be cut with a heat knife to give an edge. The shield or
insulator 10
of the present invention can be premolded to accommodate different shapes and
sizes and
will eventually mold to the cavity size even wlien the cavity is uneven. The
state of the art
shield cannot shape adapt to the mounting cavity in the bodywork or framework
of the
vehicle in a like manner.
Further, where the shield or insulator 10 of the present invention is
dimensionally
stable upon exposure to teinperatures up to 232 C (450 F) at which slight
yellowing may
occur, the state of the art shield tends to disfigure and the phenolic binder
is released,
resulting in the production of an odor and browning of the shield. Of course,
the shield or
insulator 10 of the present invention is also free of glass fiber and,
therefore, is installer
friendly ( does not produce an itchy feeling for those contacting the
material). Whi.le the
glass fiber in the state of the art product is sandwiched between two layers
of polyester,
the product still tends to be more irritating to those coming into contact
with it.
Accordingly, for many applications it is necessary to coat the edge of the
shield or
insulator in order to avoid this potential irritation.
In a first alternative embodiment shown in Figure 2, the shield or insulator
10 also
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comprises a nonlaminate acoustical and thermal insulating layer 12 of polymer
fiber (for
example, a nonwoven fabric) selected from a group consisting of polyester,
polypropylene, polyethylene, rayon, nylon and any mixtures thereof. The layer
12 also
includes a relatively high density, nonlaminate or unitary skin 14 of that
polymer fiber
along at least one face thereof.
Advantageously, the high density skin 14 will not delaminate from the layer 12
under the environmental conditions existing under the carpet and along the
floor pan of the
vehicle and also adds structural integrity and strer_gth to the shield or
insulator 10 which
aids significantly in handling and fitting the part during installation. The
high density skin
14 is also more aesthetically pleasing. Still further, for many applications
the high density
skin 14 eliminates the need to provide an additional facing layer of another
type of
material. This serves to eliminate any potential failure of the shield or
insulator due to
delamination. It also results in a sliield or insulator made exclusively from
one material
that is, therefore, readily recyclable. Further, since the skin may be forined
with a hot
platen during the molding of the shield or insulator 10 to its desired shape,
no additional
processing step is required. This reduces production cost relative to a shield
or insulator
with a facing since such a facing must be adhered to the acoustical and
thermal insulating
layer in a separate processing step.
In yet another embodiment shown in Figure 3, the shield or insulator 10
includes a
nonlaminate acoustical and thermal insulating layer of polymer fiber 12 (for
example, a
nonwoven fabric) selected from a group consisting of polyester, polypropylene,
polyethylene, rayon, nylon and any mixtures thereof in combination with a
metal foil
facing layer 16 over a first face 18 of the acoustical and tllermal insulating
layer. The
metal foil facing may be present in one or more layers.
In yet another alternative embodiment shown in Figure 4, the shield or
insulator 10
comprises a nonlaininate acoustical and thermal insulating layer 12 of polymer
fiber as
described above in combination with a first metal foil facing layer 16
covering a first face
18 thereof and a second metal foil facing layer 20 covering a second, opposite
face 22
thereof. The second facing layer 20 may be constructed from the same or a
different
material as the first facing layer 16. The first and second facing layers 16,
20 may be
attached to the layer 12 by means of an appropriate adhesive
or adhesive web in accordance with practices well known to those skilled in
the art.
In accordance with yet another embodiment of the present invention shown in
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Figure 5, the shield or insulator 10 comprises a single, nonlaminated
acoustical and
tliermal insulating layer 12 of polymer fiber (for example, a nonwoven fabric)
as described
above in combination with a first metal foil facing 16 covering a first face
thereof and a
second metal foil facing 20 covering a second face 22 thereof. Additionally,
the shield or
insulator 10 of this embodiment includes an additional acoustical and thermal
insulating
layer 24 of polymer fiber (for example, a nonwoven fabric) selected from a
group
consisting of polyester, polypropylene, polyethylene, rayon, nylon and any
mixtures
thereof. As a result, the first metal foil facing layer 16 is sandwiched
between the two
acoustical and thermal insulating layers 12, 24.
In any of the embodiments described above and illustrated in Figures 1-5, the
acoustical and thermal insulating layer 12 and or 24 may further include from
about 10 -
60 weight percent of glass and/or natural fibers such as, but not limited to E-
glass, S-glass,
kenaf, hemp and mixtures thereof. Use of such glass and natural fibers may be
desirable
to meet the performance parameters necessary for some potential applications.
In summary, numerous benefits result from einploying the concepts of the
present
invention. An under carpet heat shield or floor pan insulator 10 constructed
in accordance
with the teachings of the present invention provides a unique combination of
mechanical
strength and rigidity as well as thermal and acoustical properties which are
consistently
and reliably maintained over a long service life even in the proximity of a
high
temperature heat source such as a catalytic converter. In one of the
embodiments of the
present invention, a relatively high density, nonlaminate skin is provided
which aids in
handling, is aesthetically pleasing and maintains the full recycleability of
the shield or
insulator.
The foregoing description of a preferred embodiment of the invention has been
presented for purposes of illustration and description. It is not intended to
be exhaustive
or to limit the invention to the precise form disclosed. Obvious modifications
or
variations are possible in light of the above teachings. For example, the
shield or insulator
10 could include a relatively high density nonlaminate skin 14 on both
opposing faces
and/or along the edges of the shield or insulator. Additionally, a shield or
insulator 10 with
one or more high density, nonlaminate skins 14 could also include one or more
facings 16,
20 if required to meet acoustical, thermal, structural and/or aesthetic
performance
requirements of a particular application.
The embodiment was chosen and described to provide the best illustration of
the
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principles of the invention and its practical application to thereby enable
one of ordinary
skill in the art to utilize the invention in various embodiments and with
various
modifications as are suited to the particular use contemplated. All such
modifications and
variations are within the scope of the invention as determined by the appended
claims
when interpreted in accordance with the breadth to which they are fairly,
legally and
equitably entitled.
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