Note: Descriptions are shown in the official language in which they were submitted.
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LITERAL TRANSLATION OF PCT INTERNATIONAL APPLICATION
PCT,/DE99,/03438 FILED ON OCTOBER 28, 1999
INSULATING ARRANGEMENT FOR THE INNER INSULATION OF AN AIRCRAFT
The invention relates to an insulating arrangement for the inner
insulation of an air vehicle according to the preamble of the
claim 1.
s It is known that the primary insulation located on the structure
side for insulation systems presently used in aircraft construc-
tion essentially consists of an insulation base material and a
film covering or encasing this insulation. 'The core material of
the insulation system is protected against water entry with the
~o conventionally utilized films. Moreover, the film covering or
casing serves for the securing of the partially bulky or flossy
insulation material. Generally, this casing or covering is
dimensioned in such a manner so that it has lowest possible
weight portions. In this context it can be determined, that due
15 to the relatively thin fi:Lm, upon the occurrence of water vapor
diffusion through the film wall, the water vapor penetrates into
the film-covered insulation packet. Thereby, the water vapor
partially condenses out in the insulation packet. Moreover,
diffused liquid particles (water) always repeatedly enter into
2o the insulation packet through unsealed or leaky areas in the
insulation packet or in the film covering. The condensation in
the insulation packet leads to the result that a collecting of
the liquid particles (of the water) occurs in the insulation
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material, which may only be removed by additional drying efforts .
This fact also has a very unpleasant effect, because the insula
tion system gains in weight due to the water accumulations) and
thereby leads to an unnecessary increase of the weight of an
s aircraft.
As a result of the above, the invention is based on the object,
to embody an insulation arrangement of the above mentioned type
so that nearly no humid or moist air or other_ moist gas or water
(vapor) particles will penetrate into a film-covered insulation
~o packet, by means of suitable measures (and air guidances), while
oppositely (in connection with an accumulation that has occurred
in that manner), the accumulated moisture shall quickly escape
without hindrance from the insulation packet..
This object is achieved by the measures defined in the claim 1.
15 Advantageous embodiments of these measures are defined in the
further claims.
The invention is described in greater detail in an example em-
bodiment with reference to the accompanying drawings. It is
shown by:
zo Fig. 3: the insulation arrangement according to Fig. 2 with
the film covering consisting of a film.
In the Fig. l, a conventionally utilized insulation arrangement
for an aircraft is illustrated, which one installs in a known
manner within an interspace (hollow space) which is bounded by
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the inner region A and the structure region B of the aircraft.
In practice, the interspace 7 is formed by the metal outer skin
6 (allocated to the structure region B) and an inner trim compo-
vent 12, for example a plate-like cabin trim panel arranged at
s a spacing from the outer skin 6. In this context, the inner trim
component 12 largely follows the curvature of the outer skin 6,
whereby a vertical position of both means is selected in the
Figs. 1 and 2. The inner trim component 12 is provided with
machined-in slits or (other) holes or penetrations at certain
~o locations, through which (generally) relatively warm (cabin) air
9, which comprises a relatively high moisture or humidity con-
tent, penetrates into the interspace. The actual insulation
arrangement is made up of an insulation packet 1 and a conven-
tional film covering ( film 4 ) of synthetic plastic, which encases
or covers the above mentioned bulky or flossy insulation mate-
rial, or insulation material consisting of a foam, (of the insu-
lation packet 1) for the purpose of securing the same. An air
gap s is formed between the insulation packet and the outer skin
6.
2o In the conventionally utilized insulation arrangement of known
insulation systems, films 4 are used, which largely prevent a
liquid water entry (entry of water, moist or humid air or other
moisture), yet are not (water) vapor tight due to their low
density or tightness or due to the low diffusion resistance
2s coefficient of the film covering. This circumstance has espe-
cially hindering effects on the film region or area directed
toward the warmer cabin side of an aircraft. Since the forward
penetration of the relatively warm air 9 (cabin air) through the
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slits and cut-out notches of the inner trim component 12 (cabin
trim paneling) continues to the surface of the film 4, moreover,
the air 9 loaded with high air moisture or humidity can get into
the insulation packet 1 through the film wall by an expected
s water vapor diffusion process. Since during the flight phase of
the aircraft (predominantly in cruise flight) a strong cooling
of the outer skin 6 to approximately -50°C (minus fifty degrees
Celsius) will occur, it cannot be avoided, that the moisture
contained in the water vapor (due to falling below the dew point)
~o condenses out. The result will be a collecting or accumulating
of moisture or ice in the insulation packet :l. During the land-
ing and ground operation phase of the aircraft, the temperature
of the outer skin 6 will increase. During this phase, the ice
will correspondingly become water. The water, which is located
~s in the insulation packet 1, will however only be able to leave
or escape from the insulation packet 1 through larger (micro-
porous) openings (not shown) in the film wall. It is, however,
disadvantageous, that therefore the possibility also exists, that
water will once again enter into the insulation packet 1 through
zo these film openings. The release of water through the film wall
in the form of water vapor is, however, only possible during a
limited time, since (generally for reasons) the ground time of
a commercial transport aircraft will be maintained relatively
short, and the conventionally utilized film 4 (film covering) is
2s not laid out for a more rapid release of water vapor out of the
insulation packet 1. This diffusion process (as has been men-
tinned initially above) will lead to an undesired accumulation
of condensate water in the known insulation packets 1 that are
encased or covered with a conventional film 4. Additionally
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effective disadvantages of the conventional insulation arrange-
ment were also given initially above.
In the following, the example embodiments according to the Fig-
uses 2 and 3 will be described in greater detail. For the sake
s of a better understandings the insulation arrangement according
to Fig. 3 will first be considered in greater detail. An insula-
tion structure or arrangement is contemplated, which is made up
of an insulation packet 1 and a film 5, which completely encases
or covers the insulation packet l, according to the example of
~o Fig. 1. The arrangement of_ this insulation structure or arrange-
ment, which will similarly correspond to the arrangement accord-
ing to Fig. l, has been omitted from this figurative illustra-
tion. According to the t.wo Figures 2 and :3, generally a film
arrangement is contemplated, which is made up of (only) one
~s single film 5 (encasing the insulation packet 1) or of two films
2, 3 (encasing the insulation packet 1) which are integrated into
a single film 5 (intended according to the example of Fig. 3).
Both film arrangements are generally realized with a film mate-
rial that is permeable by gases, with which a different diffusion
zo resistance characteristic or behavior is achieved dependent upon
the diffusion direction of the total structure from the moist or
damp inner space 7 to the cold outer skin 6.
With reference to the Fig. 3, the differential diffusion resis-
tance characteristic of the film 5 is realized with a film mate-
zs rial which provides a high diffusion resistance coefficient from
the film outer wall surface to the film inner wall surface, and
provides a low diffusion resistance coefficient in the opposite
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diffusion direction (namely: from the film inner wall surface to
the film outer wal l surface ) . This film arrangement or structure
(referring to the film 5) is worth consideration, for the fact
that one may therewith enclose or cover ( coat over ) the outer
s surface area of the insulation packet 1 on all side areas with
a single film 5 (encasing or covering film) of the same common
material, from the point of view of a rational fabrication of the
insulation arrangement. This film 5 will function in such a
manner, whereby the diffusion resistance coefficient is large in
~o a direction toward the internally located insulation packet 1
which is entirely covered or encased by the film 5. In other
words, no water (vapor) can penetrate entirely to the insulation
packet 1 . The film 5 acts as a moisture blocker ( as a vapor
barrier). In the opposite direction, the film 5, however, has
a different diffusion resistance coefficient, which is as small
( low) as possible, so that in the given case, the accumulated
water from the insulation packet 1 (from the inwardly located
insulation) can easily diffuse out of the insulation packet 1 in
the form of water vapor.
2o Returning to the Fig. 2, as mentioned, a film casing or covering
is utilized, which is assembled or made up of two films 2, 3 of
different types of materials. The two films 2, 3 are fixedly
(and seamlessly) joined with each other along their film edges,
so that one obtains a film casing or cover according to the
2s example of the Fig. 3. Furthermore, it is a prerequisite, as
already explained with regard to Fig. 1, that the insulation
arrangement (according to the Fig.2), with the film casing or
cover made up of a first and a second film 2, 3, is likewise
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arranged within the mentioned interspace which is enclosed by the
inner trim component 12 ( cabin trim paneling) and the (metal )
outer skin 6 of the aircraft.
Thereby the insulation packet 1, which is fully covered or en-
cased by the film 5 (made up of the two fi:Lms 2, 3), will not
completely line the interspace. Thereby the insulation arrange-
ment will always be surrounded by a (certain) hollow space, due
to an intended (and below described) supply of conditioned
air 11.
~o This film (casing) that is fused at the film edges (of two films
2, 3) completely encloses the insulation packet 1 and lies
thereon in such a manner so that the film surface of a first film
2 predominantly is arranged lying on the stringer 8. The film
surface of a second film 3 predominantly is positioned opposite
the surface of the inner trim component 12 facing toward the
inner space 7. Predominantly because certain edge regions or
portions of the surface, that are limited to the sections) of
the fusion of both films 2, 3, are oriented in the direction of
the lengthwise extension (the extended length) of the inner trim
zo component 12 or of the stringer 8, and from there the above
mentioned conditioned air 11 will also enter' into the mentioned
inner space 7.
Thereby the first film 2 will lie on the extended surface area
of the stringer 8, thus in the selected example, not lying on the
z5 inner trim component 12. Since the second film 3 is located free
in the inner region 7 (and not lying on the inner trim component
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12 ) , the second film 3 will be surrounded most extensively by the
conditioned air 11 flowing through the inner region 7.
It is also mentioned at this point, that several spacer members
are arranged between the outer skin 6 and the insulation packet
s 1, or between the stringer edge (of the stringer 8) and the
insulation packet 1. Hereby an air gap s is formed.
The first film 2 is realized with a film material that achieves
a low diffusion resistance coefficient in the diffusion direction
of the gas diffusing through the film wall from the film inner
~o wall surface to the film outer wall surface. The term gas is
understood to mean, as mentioned previously, relatively warm air,
which is loaded with high moisture or humidity, which flows
through the slits and openings of the inner trim component 12
into the inner region 7.
15 The second film 3 is realized with a film material that achieves
a high diffusion resistance coefficient in t:he diffusion direc-
tion of the gas diffusing through the film wall from the film
outer wall surface to the film inner wall surface.
According to all embodiments of the described insulation arrange-
zo ment, the film-encased insulation packet 1 is realized with an
insulation material consisting of polyphenylene sulfide (short
designation: "PPS"). The latter is covered or encased by the
individual film 5 embodied as a synthetic plastic film (according
to the Fig. 3) or by the film arrangement, which consists of two
z5 different types of films 2, 3 (according to the Fig. 2 ) which are
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combined together to a single film 5. Thereby the film mate-
rial s) of the film 5 (which may be combined together of two
different types of film materials in a given case) (according to
the film structure according to the Figures 2 and 3 ) realizes
s (realize) a differential diffusion resistance coefficient, de-
pending on the direction of the occurring diffusion through the
film wall, as described previously. Their spatial arrangement
within the inner region 7 (or the interspace) is adapted, at the
location of their contact surface, to the surface contour of the
~o surface of the stringer 8 (oriented toward the inner trim compo-
nent 12) or (but also) to the surface contour of the inner sur-
face of the outer skin 6.
In closing it is summarized that the different films 2, 3, 5
(film coverings or casings) according to the Figures 2 and 3
consist of different types of film materials, so that an accumu-
lation of condensate water' in the insulation packet 1 encased by
the film is excluded. A second film 3 (according to the Fig. 2)
facing toward the inner region A will comprise a film material
that provides a high diffusion resistance coefficient in the
zo diffusion direction of the medium [from the film outer to the
film inner (wall) surface]. That has the advantage that the air
that is loaded with a (relatively) high moisture or humidity,
which flows in through slits and openings from the inner region
A (for example from the passenger cabin of an aircraft) into the
2s intermediate region (into the inner region 7), cannot diffuse
directly into the primary insulation (arranged close to the
aircraft fuselage structure). At the area of the insulation
arrangement oriented toward the outer skin 6 (as a component of
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the aircraft fuselage structure), a first film 2 (according to
the Fig. 2 ) is utilized, which is open to diffusion and which
comprises a low diffusion resistance coefficient in the diffusion
direction of the medium from the film inner to the film outer
s (wall) surface.
This has the advantage, primarily during warm ground times
(ground phase of an aircraft) that liquid water, which has accu-
mulated by condensation in the insulation packet 1, can escape
from the insulation packet 1 as water vapor in a (relatively)
~o unhindered manner and therewith quickly. Thereby a drying of the
insulation packet 1 is strived for. Thereby it is a prerequisite
that a sufficient air gap s exists between the outer skin 6 and
the first film 2. The stringer 8, on which lies the primary
insulation, thereby functions as a spacer member relative to the
~s outer skin 6. Additional holder elements wi:l1 serve to maintain
or to enlarge if necessary the air gap region 10 between the
outer skin 6 and the insulation arrangement (the film-encased
insulation packet 1). Thus, two essential effects in comparison
to the conventionally utilized aircraft insulation are achieved:
zo a) the water vapor, which can come from the inner region A
(originating from the passenger cabin) into the interspace
(inner region 7), is prevented from penetrating (from dif-
fusing) into the insulation packet 1 by the second film 3
functioning as a vapor barrier;
z5 b) the liquid water, which nonetheless collects in the insula-
tion packet l, may, for example, leave the insulation
packet 1 in the form of water vapor through the diffusion-
ally open first film 2, during the warm ground phase of an
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aircraft. Thereby a drying of the primary insulation is
supported, and therewith the accumulation of condensate
water in the insulation system is prevented.
Both embodiments of the presented insulation arrangement accord-
s ing to the Figures 2 and 3 possess the advantage that one
achieves an additional drying effect even during flight (in the
cruise flight of an aircraft) with conditioned air, which one
additionally supplies to t:he affected insulation arrangement by
means of an active air conditioning device (air conditioning
~o apparatus). This is especially because the film construction
according to the Fig. 3 will ensure that the insulation packet
1 can even dry out at all. Overall, the following advantages are
achieved with the presented insulation constructions:
a) Less water vapor will enter into the insulation packet 1,
15 SO that also less condensation takes place in the insula-
tion packet 1;
b) Condensate water, which has once collected in the insula-
tion packet 1, can again escape from the insulation in the
form of water vapor;
zo c) The insulation packet 1 can more easily be dried after all
of the above;
d) There no longer arises an accumulation of condensate water
in the insulation packet l,
e) Because less water is present in the insulation, the oper-
z5 ating life of the insulation arrangement or the insulation
system is increased;
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f) Corresponding weight is saved in the air vehicle (for exam-
ple in the aircraft), whereby the flight capacity is in-
creased;
g) The suggested measures may be realized without special
s effort. That applies also to retrofitting of air vehicles
(aircraft) located in service;
h) If, nonetheless, the utilization of a drying system is
provided in the air vehicle (in the aircraft), for drying
the structure, then the described insulation arrangement
~o according to the Figures 2 and 3 may be installed to be
just as effective as necessary.
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