Aircraft internal insulation structure

p0001The invention relates to an insulation structure for the internal insulation of an aircraft according to the preamble of claim 1.

p0002It is known that the insulation currently used in aircraft consists enveloping film for the structure located on the side of primary insulation consisting essentially of an insulating base material and a this isolation. The films conventionally used, the core material of the insulation system is protected against water ingress. In addition, the film envelope used to attach the partially bulky insulation. This envelope is dimensioned generally so, after which it has the lowest possible weight. It can be stated that due to the relatively thin film in taking place water vapor diffusion occurs through the film wall of water vapor in the folienumhüllte insulation package. It partly condensed from the water vapor in the insulation package. Also go through leaks in the insulation package or in the FolienumhGllung repeatedly diffusing liquid particles such as water, in the insulation package. The condensation in the insulation package causes an accumulation of liquid particles (water) takes place in insulating material which can be eliminated only by additional drying costs. This fact therefore is very uncomfortable because the water accumulation (s) increases the Isolationssytem weight and therefore to an unnecessary increase of the weight (take-off weight) of an airplane performs.

p0003Furthermore, from the document: "<patcit id="pcit0001" dnum="DE19849696A1"><text>DE 198 49 696 A1</text></patcit>known ", which represents the closest prior art, a gattungsgemaßer insulation structure which is completely enveloped by a film. The film is disposed within an intermediate space, including the an inner lining and an outer skin of an aircraft. Those foil is coated with a gas and liquid . realized penetrating film material with which they will implement a different diffusion resistance behavior as a function of the direction of diffusion of the diffusing through the film wall medium More detailed information relating to the diffusion behavior of that film can not be disclosed, but can infer that the film material unspecified viewed those films should have different water characteristics, so that a return of the accumulated medium (recorded by insulating water) through the foil membrane is even conceivable. that solution is liable insofar as the disadvantage that the water (water vapor) that (the) from outside the film acting and will diffuse through the latter, will be initially trapped in the insulation, which then could possibly escape later through the wrapping films of the insulation package. Without creative additions, which relate to the design of the film (s) with respect to almost disclosed information is regarding a different diffusion resistance behavior of the films hardly imaginable to rework a such specified isolation structure functional. It only proposes a foil material in the diffusion direction of the film wall diffusing medium (condensed water) of the Folieninnen- to Folienaußertwandoberfläche a lower diffusion resistance should implement.

p0004This measure would be credibly that a film material that possesses this ability, a film surface, the collected water can release from the foil-wrapped insulation package through the film to the environment without providing a solution. Also mediates Publication "<patcit id="pcit0002" dnum="US5565254A"><text>US 5,565,254 A</text></patcit>"Proposals for the design of an insulation structure, the corresponding insulation packages and sheet materials are integrated, which are mainly limited to the range offered by GORE. For further improvements, which correlate with the situational transport the media through the slides, the document is silent.

p0005Accordingly, the invention is based on the object to improve a generic insulation structure such that the shrink-wrapped in a foil envelope insulation is kept dry and also minimizes the transport of water in the insulation package and support from the package by suitable measures.

p0006This object is achieved by the measures specified in claim. 1 In the further claims embodiments of these measures are given.

p0007The invention is described in more detail in an embodiment shown in the drawings added. Show it<dl id="dl0001" compact="compact"><dt>Fig. 1</dt><dd>an insulation structure with a film coating which has an asymmetrical film structure;</dd><dt>FIG. 2</dt><dd>an insulation structure having a foil envelope, which has a symmetrical film structure;</dd><dt>Fig. 3</dt><dd>an illustration of water transport through the membrane film of a symmetrical film structure after <figref idrefs="f0001">FIG. 2</figref>;</dd><dt>Fig. 4</dt><dd>an insulation system to the <figref idrefs="f0001">FIG. 2</figref> with one-sided film coating;</dd><dt>Fig. 5</dt><dd>a representation of mass transfer through membrane pores or pores of a film;</dd><dt>Fig. 6</dt><dd>an illustration of the pore structure at different temperatures;</dd><dt>Fig. 7</dt><dd>the representation of a symmetrical membrane / film;</dd><dt>Fig. 8</dt><dd>the representation of an asymmetric membrane / film;</dd><dt>Fig. 9</dt><dd>the representation of an asymmetric membrane with different layers and different characteristics;</dd><dt>Fig. 10</dt><dd>the representation of two different films or membranes differing porosity with an air gap;</dd><dt>Fig. 11</dt><dd>the representation of two films or membranes of different chemical property with an air gap;</dd><dt>Fig. 12</dt><dd>an insulation package respectively insulation structure with a permeable material as a substitute for drainage holes.</dd></dl>

p0008In the <figref idrefs="f0001">Fig. 1</figref> Now, a structure of insulation 10 with a foil envelope 5, which has an asymmetric film structure. This insulation assembly 10 taken into account (the aircraft outer skin of an aircraft designed insulating) insulation package 1 which is completely enclosed by a foil envelope fifth This insulation structure 10 is located within a free space 7, which is limited, for example, by a structural region (an aircraft outer skin) and wall-like covering part, the latter being located near the outer skin of the aircraft. Compared to that initially specified insulation system that you traditionally find in a commercial aircraft, the insulation structure 10 is realized with two different wrapping foils 11, 12, whose film properties are different. Thus, a first sheath film 11, which is oriented to the aircraft outer skin, for example, used as a vapor barrier, on the other hand a second sheath film 12, which is oriented to the aircraft cabin, used water-vapor-permeable. This wrapping foils 11, 12 are connected by gluing or welding folienendseitig firmly together. The film material of the first and / or second enveloping foil 11, 12 will be 12 different design on the film thickness of the individual sheath film 11 and / or a nature. If yet another wrapping foils of the first and / or second sheath film 11, 12 are stacked or adjacent bayed the foil envelope are 5 integrated, it is conceivable that also the film material on the film thickness of each wrap sheet is correspondingly different.

p0009Depending on the desired direction of diffusion, the membrane of the two wrapping foils 11, 12 or further wrapping films used over the film thickness (the single sheet) will have different porosities. For example, the directional diffusion behavior of the first sheath film will be 11 designed reversed during the flight of an airplane to the outer skin portion of the aircraft structure porous and the cabin area less porous or at a bottom stay of the aircraft.

p0010Furthermore, the proposed symmetrical film construction, a membrane of the single serving film 11, 12 or the other films n ( "n" represents the number of films) taken into account, which is integrated in each of two or more sheet materials (possibly different type of film). The film materials for wrapping films, their use is proposed, with which those different diffusion permeability is to be implemented, will be considered in more detail below.

p0011The (figuratively, not shown) of the assembly with a plurality of adjacently layered wrapping foils realized foil envelope 5 will be implemented along the lines of the sandwich construction.

p0012It is further proposed that between the so layered (neighboring) wrapping foils, which are sequentially arranged horizontally, an air gap can be realized, the low (er) can influence the transport of the diffusing liquids (water) or the diffusing gaseous media (steam).

p0013Returning to the film materials for those wrapping films, used in the specified asymmetrical structure of a membrane, are the embodiments supplemented following steps, after which the foil envelope 5 is designed for the outer skin region of the aircraft structure hydrophilic and hydrophobic to the cabin area of ​​the aircraft tight. After that is necessary to provide that (in a foil envelope 5 with two films), the first sheath film 11 is realized with a hydrophilic film material and the second sheath film 12 with a hydrophobic sealing foil material. It is further suggested that the film material of the first and / or second sheath film 11, 12 and / or (if applicable) any additional wrapping foils n is realized with a sheet material of amorphous, crystalline or semi-crystalline polymers. With regard to the film material, which should be taken into account, from PTMSP, 6-FDA-Based is; PI, PEI, PS, PTFE, Nafion or PET polymer as film material indicated. Also it is mentioned that the hydrophilic first sheath film 11 12 can be implemented with a foil material of PTFE with a film of silicone material, and the hydrophobic second wrapping film.

p0014These designs are extended to those which required different diffusion permeabilities will be precisely achieved by the advantageous arrangement of hydrophilic or hydrophobic construction.

p0015An example of this will be those arrangement, according to which a hydrophilic membrane density on the structure side can absorb and pass the water well; the hydrophobic dense membrane on the cabin side will block water passage. The presented transport principle is based here on a solution-diffusion mechanism of transporting a positive influence at high temperatures. If the membrane is very cold, there will be a very small transportation, which is more difficult in the direction of the structure through the hydrophobic membrane. If the temperature is higher, the water at the structure side easily penetrate into the hydrophobic membrane and also easier to diffuse through the hydrophobic membrane because of the higher temperature. Therefore, the selected example of a combination of materials would PTFE on the cabin side and silicone on the structural side.

p0016In the <figref idrefs="f0001">FIG. 2</figref> is another embodiment of an insulation structure 10 is shown, which foil envelope 5 is equipped with a symmetrical film construction. There is only one (single) third wrapping film 13 into consideration, which is the aforementioned insulation package 1 completely envelop.

p0017It goes without saying that the film ends that third sheath film 13 firmly connected by welding or gluing or otherwise joining like to seal the insulation package 1 respectively to protect against external influences.

p0018An embodiment of that wrapping foil 13 takes into account that the symmetric membrane is a nature hydrophobic hydropil and at low temperatures at high temperatures.

p0019Similar to the previously stated example of the design of a foil envelope 5 with two wrapping foils 11, 12 is 5 proposed with regard to a symmetrical shaped film structure that foil envelope, in that a first film portion 15a of the third covering film 13 which is oriented towards the exterior skin region of the aircraft structure and no temperature dependence is subject to, hydrophobically is a nature. A second sheet portion 15b of this third covering film 13 which is oriented towards the cabin region of the aircraft and an existing temperature dependence is subject is also a nature hydrophobic, said hydrophobic kind of film area is capable of converting an increased liquid transport under the influence of low temperatures.

p0020Even a further embodiment is conceivable, according to which the first and second film portion 15A of the third covering film 13 are adjacently connected in series that are so distributed (with this arrangement) 13 envelop this wrapping foil circumferentially, wherein even after this arrangement, the first film section 15A no temperature dependence is subject and is a nature hydrophobic and the second film portion 15B of an existing temperature dependence is subject and is a nature hydrophilic.

p0021In the assumed case, the symmetric membrane of the first film portion 15A would then be exposed to low temperature impact is also a nature hydrophobic, for example, and could implement an increased water transport, whereas the symmetric membrane of the second film portion 15B operates natured lying hydrophobic under the influence of high temperatures.

p0022On the other hand, if those symmetric membrane the wrapping film 13 has the ability to show under the influence of high temperatures an increased water transport and under the influence of low temperatures reduced, another embodiment of the symmetric film structure would be conceivable.

p0023is supplemented for the sake of completeness, that the possibility could be considered that the first and / or second film portion 15A, 15B different from several layers of foil sheet material is layered, like the <figref idrefs="f0003 f0004">Figures 8 to 11</figref> is visible.

p0024This prefix information be deepened as to what the first film portion 15A is provided with a non-porous sheet material, preferably made of silicone or a foil material with similar properties can be realized. Thus, at that third sheath film 13, which is a nature hydrophobic, distributed over the foil envelope 5 under the influence of low temperature no or very small pores and formed under the influence of high temperatures, larger pores allow the permeiren no liquid.

p0025With another embodiment, is modeled after the <figref idrefs="f0002">Fig. 4</figref> suggested that the first film portion 15A of the third cladding film 13 a hygroscopic layer is adventitious 14 coated. This hygros-copic layer 14 should be with strongly hygroscopic materials, preferably various silica compounds, or a glycerol, realized. The silica compounds are porous natured, which are realized, for example, with a silica gel.

p0026Also, it is added that the third covering film 13 or the first sheet portion 15a is realized with a hydrophobicity-converting film material, preferably poly with a "(2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole) [PDD ] / PTFE "is realized.

p0027In addition to the initially explained and from the <patcit id="pcit0003" dnum="DE19849696A1"><text>DE 198 49 696 A1</text></patcit> known use of different membrane films, which are combined by lamination, etc. to form a film, may also contain further different sheet materials such as exemplified, be combined with different physical and chemical properties. To this end, the Unhüllungsfolien 15A, 15B of the insulation 1 can along the lines of<figref idrefs="f0001">FIG. 2</figref> be structured as follows. The outward facing to the aircraft structure membrane with that first sheath film 15A must be hydrophobic (water repellent) and do not require a temperature dependence.

p0028This measure is obtained, for example, non-porous silicone membranes or membranes with similar properties. This first sheath film 15A film may, but need not, consist of different layers.

p0029The second sheath film 15B of the modeled <figref idrefs="f0001">FIG. 2</figref> the cabin side shows, should be hydrophobic and have a temperature-dependent water transport, which at lower temperatures an increased water transport will take place.

p0030The mass transfer through such membranes can be described with the so-called "Surface-flow" or by capillary condensation. The lower the (film influences) temperatures are, the better we can condense a gas. In addition, the mass transport of the condensed phase is greater than through a pore of a gaseous, because the molecular density of the condensed phase is greater than that of gaseous. Therefore, this transportation mechanism is greater than at higher at lower temperatures.

p0031In addition to the phase state of the substance to be transported, the mass transfer also depends on the concentration gradient across the membrane. According to the model of<figref idrefs="f0002">Fig. 3</figref> is always transported from high to low potential a substance. This will be described below by the chemical potential of the water. To this extent the chemical potential of the water has oriented film (second sheath film 15B) to be much larger than the chemical potential in the cabin on the insulating facing side of the cabin (aircraft cabin), so that the water is transported out of the insulation package. 1

p0032This can be with a view of the insulation assembly 10 after <figref idrefs="f0002">Fig. 4</figref> achieved by that the insulating material facing side of the cabin-oriented film (second sheath film 15B - along the lines of <figref idrefs="f0001">FIG. 2</figref> - Is coated with a highly hygroscopic material. The hygroscopic material will accumulate water and thus can increase the chemical potential. In addition, the water is removed from the insulating by the highly hygroscopic material and transported to the film to release the water. Hygroscopic materials include silica (porous silica compounds) or glycerol.

p0033The following comments are appropriate bschreiben in particular films or membrane materials, which are used for insulation packages in an airplane or any other vehicles. That called an insulation package product will follow, as well as conceptually used in the preceding embodiments, an insulation structure 10 (folienumhülltes insulation package 1) relate to avoid any possible misunderstanding.

p0034Even to a better understanding of the following information to get, the following aspects, which are related to the aircraft are taken up.

p0035The isolation systems currently used in passenger aircraft for the present on the structure side primary insulation consisting essentially of a core material and a simple wrapping film. The films conventionally used have the task that nuclear material of the insulation system to protect against water penetration generally. In addition, the sheath serves to fasten the part to the bulky core material. The enclosure is typically designed so that it is as light as possible. The disadvantage here is that penetrate through the diffusion of water vapor due to the relatively thin sheet of water vapor in the insulation package. 1 In this part, the vapor condenses in the insulation package. Also go through leaks in the insulation package 1 or the corresponding wrapping sheet repeatedly liquid water in the insulation package. 1

p0036The consequence of such a considered arrangement will be that the condensation in the insulation package 1 means that accumulates liquid water in the insulation. It comes through the accumulation of water in undesirable weight gain of the insulation system, for example, a commercial aircraft, and therefore to an unnecessary increase in the take-off weight.

p0037In contrast, for the benefit of those aircraft solutions submitted that in the <figref idrefs="f0001">Figures 1 and 2</figref> are shown and are previously presented. From these<figref idrefs="f0001">Figures 1 and 2</figref> is the desired water transport through the insulation packages 1 clearly with the (initially indicated and again verdeutlichten) disadvantages of those traditionally used solutions are parked. Thus, in the<figref idrefs="f0001">Fig. 1</figref> the water transport provided by an insulation package 1 with different films 11, 12 or membranes on the side of the aircraft outer skin and to the aircraft cabin. The following is the one film / membrane, showing the aircraft outer skin, "outer sheet" and called the film / membrane, showing to the cabin, "inner sheet". During the flight of an airplane as little water is now to get to the aircraft structure and there lead to condensation. For this purpose, the water transport through the outer sheet must be extremely low and the water transport through the inner film to be greatly reduced in order to avoid the accumulation of water in the insulation package. At the bottom of the water is to be transported between the insulation and the structure in order to avoid accumulation. In addition, moisture is trapped in the insulating material, can be transported away on the ground as possible without hindrance.

p0038These existing problems must remedy with suitable solutions that are just not negligible in a wide-bodied aircraft. Films or membranes meeting these demands, for example, from the following materials: "Silicone, polydimethylsiloxane, polyethylene, poly (cis-1,4-butadiene), poly (cis-1,4-methyl butadiene), nylon 6 (polyamide ), polyimides, cellulose nitrate, cellulose ester, Polyethylentherephterat, polymethyl methacrylate, Nafion-based 6-FDA materials, polyacrylonitrile, polycarbonate, polysulfone, poly (ether imide), polyethersulfone, polyvinylidene fluoride, polypropylene, PTMSP (poly (Itrimethyl-silyl-I-propyne) , or poly 2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole, abbreviated PDD / [PTFE Polytedrafluorethylen]. the last two materials show a greater mass flow through the membrane with increasing temperature, which free on a large volume leaves behind close in Ploymermatrix. the temperature dependence is by changing the in<figref idrefs="f0003">Fig. 5</figref> described transport mechanisms and caused by the change in pore structure which in the <figref idrefs="f0003">Fig. 6</figref> to be shown.

p0039Thus, the water transport through the outer film because of the low temperature of the structure (about -20 "C) is restricted The materials used can be rubbery, amorphous, semi-crystalline or crystalline Transport through amorphous layers is based on the solution -.. Diffusion - model. to ensure better removal of liquid water between the outer sheet and the structure placeholder between the insulation package 1 and the structure can be installed, or the insulation packages can be installed under tension so that they do not extensively applied to the structure. These structural measures are then used when the risk of water accumulation between the insulation and the structure or cabin lining is.

p0040The inner film may be like that described above is made from the same materials. In addition, woven, hydrophobic material are used, which retains liquid water and lets water vapor pass.

p0041Those listed membranes / films may be symmetrical or asymmetrical. Symmetric membranes / films in the<figref idrefs="f0003">Fig. 7</figref> are shown, consist of a Foli e or membrane having the same properties throughout its thickness. Asymmetric membranes are composed of two or more layers of the same material or different materials with different properties, such as for example - as shown in the<figref idrefs="f0003">Fig. 8</figref> - With different porosities, or - as shown in the <figref idrefs="f0004">Fig. 9</figref> - With different chemical properties. The individual layers of asymmetric membranes can be joined together by various processes, such as gluing, welding, lamination, "Dip Coating", polymerization, plasma polymerization or "casting". Also, a gap of, for example, less than 10 mm thickness, of the modeled<figref idrefs="f0004">Figures 10 and 11</figref> is taken into account can be realized between the individual layers in order to continuously remove moisture. A gap of about 10 mm will only be used if it is to be expected with liquid water to allow an unimpeded drainage.

p0042The distance between the films or membranes is realized by holders which will be called in membrane technology "spacer".

p0043An application example for the <figref idrefs="f0001">Fig. 1</figref> illustrated insulation package 1 can as thus look like this. The inner film may for example be a woven PTFE or [PDD] / PTFE]. This material allows only water vapor and allows pressure equalization between the aircraft cabin and the foil-welded insulation. The outer film consists for example of a silicone-laminated fabric which is water-repellent, tear-resistant and chemical resistant.

p0044Another application example of the arrangement according to the <figref idrefs="f0001">FIG. 2</figref> with two identical films / membranes for an inner and outer foil could be as follows. The outer sheet is composed of a hydrophilic and a hydrophobic structural side cabin side.

p0045At low temperatures the fly of water transport through the hydrophobic layer, for example, from [PDD] / PTFE is very low. Other hydrophobic materials include polyvinylidene fluoride, Polyethylenthereph-man of letters, and polypropylene. Hydrophilic materials include cellulose ester, polycarbonate, polysulfone, polyethersulfone, polyetherimide, polyimide, polyamide. At the bottom, the liquid water produced in the structure, taken up from the hydrophilic layer, thereby increasing the water vapor partial pressure (chemical potential) on the structure side of the outer foil. The larger chemical potential and the higher temperature of the water vapor transport is supported by the hydrophobic membrane. The inner film has the same orientation as the outer by the same functionalities.

p0046In certain cases in which the insulating material, the cabin or the structure needs to be permanently dried, other arrangements of the films / membranes are possible. The layering can be seen from the outside inwards be designed as follows:<ol><li>a) hydrophobic-hyrophil / insulation / hydrophilic-hydrophobic (wet insulation mat)</li><li>b) hydrophobic-hyrophil / insulation / hydrophobic-hydrophilic (drying the cabin). As well as the selection of materials with specific chemical properties similar effects can also be achieved with materials of different porosity. An example would be the drying of the structure, with an observed from the outside inwards arrangement:</li><li>c) Porous-microporous (tight) / insulation / porous-microporous (tight)</li></ol>can be achieved. The number of layers having different properties is desired.

p0047In this context, the porosity of the films are defined as follows: <tables id="tabl0001" num="0001"><table frame="none"><tgroup cols="2" rowsep="0"><colspec colnum="1" colname="col1" colwidth="59mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><thead valign="top"><row><entry colsep="0">Average pore diameter</entry><entry colsep="0">definition</entry></row></thead><tbody><row><entry colsep="0">> 0.1 microns</entry><entry colsep="0">macroporous</entry></row><row><entry colsep="0">5 nm</entry><entry colsep="0">mesoporous</entry></row><row><entry colsep="0">1 nm</entry><entry colsep="0">microporous</entry></row><row><entry colsep="0"><1 nm</entry><entry colsep="0">tight.</entry></row></tbody></tgroup></table></tables>

p0048To reduce cost and weight and to allow maximum flow should be 0.5 microns as thin as possible in the range of 0.1 to the dense and microporous layers. The dimensions of the support, the porous films are 150 microns in the range between 10 to.

p0049To the water storage capacity of the insulating material and thus to improve the evacuation further, the insulating material must be hydrophobic in order to minimize the accumulation of liquid water by capillary action. Capillary effects are the main cause of the contamination of insulating material with liquid water. Another proposal includes the Replace the drainage holes in the Isolierpaketen 1. To understand it is mentioned that conventional insulation packages need at the package bottom corresponding drainage holes to allow both the surge and the drainage of liquid water from the package. An alternative to these traditional holes is the consideration of film / membrane material that liquid water will not let that happen; but has large pores that can pass water vapor on the ground at higher temperatures. Such so-called insulating is in the<figref idrefs="f0005">Fig. 12</figref> shown. The outer film used has a very large transport resistance to water in all states of aggregation. The considered inner film is designed in two parts. An upper part of this film is, for example, as the outer film designed, the lower part of the inner film is made of a hydrophobic, water vapor-permeable porous material.

p0050The porosity and the surface of the lower portion of the inner film is sufficient to ensure pressure equalization and to remove eventual liquid water from the inside of the lower part of the insulation. In certain cases, the permeable part of the insulation can also be integrated on the top side or the outer film to dissipate for example, water from the Isolierpaketen for ventilated structure side, or dehumidifying insulating mats, due to the installation position no drainage holes or ventilation areas at the bottom of the package allow.

p0051These different films can be welded together, glued, are polymerized or laminated. It is also conceivable that the water vapor permeable portion of the film by high-energy radiation ( "grafting") with possible subsequent chemical treatment or by other chemical and physical treatment methods is achieved.

p0052These supplemented insulation assemblies, the following advantages will result, according to which<ul><li>less water vapor will enter the insulation package, so that even less condensation in the insulation package is present;</li><li>Condensation, which has once accumulated in the insulation package, can escape from the insulation in the form of water vapor or liquid water;</li><li>the insulation package can thus dry more easily;</li><li>it can no longer come to the accumulation of condensed water in the insulation ;.</li><li>in that less water is present in the insulation, will increase the service life of the insulation system;</li><li>Saves weight in the aircraft, which will increase the performance of the passenger aircraft;</li><li>the measure without redevelopment of an aircraft can be implemented easily in the aircraft, and consequently also for the retrofitting of in-service aircraft located may be worthwhile.</li></ul>

p0053If the insert is provided by a drying system in the vehicle to (in general) to dry the vehicle structure, the presented insulation structure for an insulation system for example, that of a commercial aircraft, could be as effective as necessary and useful.