Hybrid flush porthole with improved trade-off between mass, surface and drag

Abstract

The invention relates to a multiple glazing unit of a pressurised enclosure, comprising at least one first external glass panel (1; 2; 3; 4; 5), separated from a second glass panel (7) by an air space (6), by means of a mounting gasket (8), the first glass panel (1; 2; 3; 4; 5) consisting of a first sheet (1) and at least one second sheet (3; 5) glued in pairs by an adhesive layer (2; 4), at least one of the first sheet (1) and the at least one second sheet (3; 5) being made of mineral glass, and another one of the first sheet (1) and the second sheet (3) being made of organic glass with stepped edges, so as to form a cavity for receiving an element of the mounting structure, with the gasket (8) positioned therebetween. The invention also relates to the use thereof as a pressurised aircraft glazing unit.

Description

[0001] Description

[0002] Title of the invention: HYBRID FLUSH PORTHOLE IMPROVING THE WEIGHT COMPROMISE

[0003] / SURFACE / DRAG

[0004] The present invention relates to a lightweight aircraft window with low drag, that is to say which, under the effect of the pressurization of the interior volume of the aircraft in flight, does not deform by forming, in relation to the fuselage of the surrounding aircraft, a protrusion (arrow) which is penalizing from an aerodynamic point of view and in terms of energy consumption for propelling the aircraft.

[0005] Particularly targeted here are windows of the type with two panels separated by an air gap. Such aircraft windows with two panels made of poly(methyl methacrylate) (PMMA) are known. In the event of rupture of the outer panel, the inner panel allows the interior volume of the aircraft to be maintained under a desired pressure. Even if the inner panel (or the peripheral seal with which it is in contact) is commonly provided with a small through hole allowing the air gap to be maintained under the pressure of the interior volume of the aircraft in flight under normal conditions, this inner panel is capable of maintaining this interior volume of the aircraft under the desired pressure in flight in the event of rupture of the outer panel, because this hole is sufficiently small to maintain a minimal air flow compensated by the aircraft's air conditioning unit; in this case, a whistling noise may occur.

[0006] The invention more particularly aims to provide such a window having aerodynamic continuity with the fuselage, and having a hybrid composition (mineral - organic) so as to improve the Mass / Surface / Drag compromise. Aerodynamic continuity means that the outer surface of the window is in perfect continuity with that of the fuselage, that is to say in the absence of any irregularity, protrusion or hollow between the two surfaces. On the other hand, the increase in mass of the window induces a loss of the range of the aircraft, as well as its increase in aerodynamic drag. The increase in the surface area of ​​the window induces an increase in drag at constant mass, or an increase in mass at constant sweep.

[0007] This object has been achieved by the invention which relates to a multiple glazing unit for delimiting two spaces with variable pressure difference, in particular an enclosure subjected to pressurization, comprising at least a first transparent slab intended to be in contact with the external atmosphere in the mounting position, and separated from a second transparent slab by an air gap, by means of a mounting joint in which a peripheral part of the multiple glazing unit is embedded, characterized in that the first slab consists of a first transparent sheet and at least one second transparent sheet bonded two by two by an interlayer adhesive layer, in that at least one of the first transparent sheet and the at least one second transparent sheet is made of mineral glass, and in that another of the first transparent sheet and the second transparent sheet is made of organic glass and has stepped edges,the edges of an outer fraction of the thickness of this sheet being set back relative to the edges of its complementary inner fraction, so as to form, where appropriate with the edges of the first sheet and the first adhesive layer, a cavity for receiving an element of the mounting structure, with the interposition of the mounting joint.,

[0008] For the purposes of the invention, the outer fraction of the thickness of the shaped organic (polymer) sheet is understood to mean a part of its thickness closest to the external atmosphere in the mounting position, a part of its thickness corresponding, in this case, to edges set back from those of the complementary inner part of its thickness, i.e. closer to the interior volume delimited by the glazing, in its mounting position. This interior volume may be the interior of a pressurized aircraft.

[0009] The shape of the edge of the window, on the side of the external atmosphere, includes a cavity corresponding to the opening made in the mounting structure (fuselage) so that the surfaces exposed to the external atmosphere of the fuselage and the window can be in perfect continuity (flush) with each other. The window is generally held in place by flanges fixed to the mounting structure and exerting a force on the rear face of the window on the one hand, and by the locking element of the mounting structure on the front (external) face of the window on the other hand; the clamping flanges secure the window by pinching. On the other hand, the hybrid construction of the first outer slab in a laminate of at least one transparent sheet of mineral glass and another transparent sheet of organic glass (polymer material) makes it possible to improve the Mass / Surface / Drag compromise of the window.In fact, the surface mass of a transparent polymer material such as poly(methyl methacrylate) (PMMA) is approximately 1.2 / 2.5 times that of mineral glass (twice as light at constant volume). On the other hand, the deflection of the first (external) slab is a function of its geometry divided by its equivalent stiffness E. eq , the equivalent stiffness is inversely proportional to the Young's modulus, that is to say that the equivalent stiffness of PMMA is approximately 3 / 70 times that of mineral glass. The use of organic glass minimizes the weight of the porthole, the use of mineral glass minimizes the deflection and the drag.

[0010] According to a first main variant, the first transparent sheet is made of organic glass and has stepped edges forming a receiving cavity for an element of the mounting structure, the at least one second transparent sheet comprises at least one second transparent sheet of mineral glass and optionally a third transparent sheet of organic glass or mineral glass, or a second transparent sheet of organic glass and a third transparent sheet of mineral glass.

[0011] According to a second main variant, the second transparent sheet is made of organic glass and has stepped shaped edges forming, with the edges of the first transparent sheet and the first adhesive layer, a receiving cavity for an element of the mounting structure, the first transparent sheet is either made of mineral glass or organic glass and the at least one second transparent sheet comprises a third transparent sheet made of mineral glass.

[0012] Preferably, each mineral glass sheet is made of soda-lime, aluminosilicate, borosilicate or similar glass, in particular float, optionally hardened, thermally tempered or chemically strengthened, and has a thickness of between 0.5 and 6, preferably 2 and 4 mm.

[0013] Preferably, each organic glass sheet is made of a polymer material consisting of poly(methyl methacrylate) (PMMA), polycarbonate (PC), poly(ethylene terephthalate) (PET), polyurethane (PU) or the like, their mixtures or copolymers, and has a thickness of between 2 and 15, preferably 3 and 6 mm.

[0014] Preferably, each interlayer adhesive layer is made of polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), thermoplastic polyurethane (TPU), ionomer resin or casting resin, and has a thickness of between 0.3 and 6.0, preferably 0.5 and 1.5 mm.

[0015] Preferably, the multiple glazing comprises materials of different densities, stiffnesses and damping, such as to give it an acoustic insulation property.

[0016] Preferably, the first transparent sheet covers the edge of the mounting joint facing outwards. This measure protects the silicone sealant or equivalent.

[0017] Another object of the invention consists in the use of a multiple glazing unit described above as glazing for a pressurized aircraft, in particular a passenger cabin window of a commercial aircraft. Such a multiple glazing unit is capable of being fixed by clamping to the fuselage of a commercial aircraft, without any discontinuity in the external surface between the glazing unit and the fuselage, thanks to the profile of its edge having a cavity for receiving an element of the mounting structure. Furthermore, the constitution of the first external slab of this multiple glazing unit in a laminate of at least one sheet of mineral glass and at least one sheet of organic glass makes it possible to control the deflection and the drag in flight (pressurized cabin), to prevent them from affecting fuel consumption, while limiting the weight of the multiple glazing unit.

[0018] The invention will be better understood in light of the following description of the attached drawings in which [Fig. 1], [Fig. 2] and [Fig. 3] schematically represent in section three embodiments of multiple glazing in accordance with the invention.

[0019] With reference to Figure 1, a double glazing unit according to the invention consists of a first exterior transparent laminated slab 1, 2, 3 and a second interior monolithic slab 7 maintained at a constant distance from the first slab by means of a sealed peripheral silicone seal 8, in which are embedded an edge portion of the first slab on the one hand, of the second slab on the other hand. The terms "exterior" and "interior" refer to the side of the exterior atmosphere on the one hand, and to the interior volume delimited by the glazing, in particular of a vehicle such as a pressurized aircraft on the other hand.

[0020] The first outer slab consists of a first sheet 1 of shaped PMMA 6 mm thick laminated to a second sheet 3 of chemically reinforced aluminosilicate glass (PMMA) 3 mm thick by means of an interlayer adhesive layer 2 of thermoplastic polyurethane (TPU) 2 mm thick. The first sheet 1 of PMMA is shaped: it has a stepped profiled edge, with a recess on an outer fraction of 5 mm of the thickness of the first sheet 1, and an overhang on the fraction of 1 mm of this thickness oriented, in the mounting position, towards the interior volume of the aircraft.

[0021] The second slab 7 is made of a 3 mm thick PMMA sheet. A peripheral silicone seal 8 keeps the first and second slabs at a distance of 8 mm from each other at rest, so as to constitute an air gap 6. The second slab 7 or the seal 8 is provided with a small hole connecting the air gap 6 with the interior volume delimited by the double glazing, on the side of the second slab 7. Thus the air gap 6 is at the pressure of this interior volume, capable of being pressurized.

[0022] The stepped profiled edge of the first sheet 1 forms a cavity capable of receiving an element of the mounting structure (to fix the double glazing to this mounting structure by means of clamping flanges against the rear face of the porthole), with the interposition of the mounting seal 8, without discontinuity of the external surfaces of the mounting structure and the glazing. These two external surfaces are said to be flush with each other.

[0023] In flight, the pressurization of the passenger cabin forces the first slab 1, 2, 3 to bend from the inside out. The second glass sheet 3 limits the deflection and the drag. In addition, the glass of the second transparent sheet 1, the TPU of the interlayer adhesive layer 2 and the PMMA of the first transparent sheet 1 are materials of different stiffness and damping, such as to give the first outer slab an acoustic insulation property. A low-emissive thermal control functionality reflecting the thermal radiation towards the interior of the delimited volume (commercial aircraft passenger cabin...), or anti-solar reflecting solar radiation towards the outside, can be obtained in different ways: composition of PMMA or TPU, stacking of thin anti-solar layers on a sheet of glass or PMMA, as deposited by magnetron (magnetic field-assisted cathodic sputtering), or on a flexible polymer film (EVA or PET type) laminated or adhered to one side of the double glazing exposed to the air, except on the side in contact with the outside atmosphere.

[0024] The double glazing shown in Figure 2 differs from that of Figure 1 in that the first slab comprises, from the outside to the inside, from top to bottom in the Figure, a first sheet 1 of chemically reinforced aluminosilicate glass 2 mm thick, a first adhesive layer 2 of TPU 2 mm thick, a second transparent sheet 3 of shaped PMMA 3 mm thick, a second adhesive layer 4 of TPU 2 mm thick and a third transparent sheet 5 of PMMA 3 mm thick. Here, it is the second transparent sheet 3 which is made of shaped PMMA, having a stepped edge with a recess of 1.5 mm of an outer fraction of the thickness of the sheet 3, and an overhang of the additional fraction of 1.5 mm of this thickness, towards the inside.In this configuration, it is the edges of the first transparent sheet 1 and of the first adhesive layer 2 and the stepped edge of the shaped PMMA sheet 3 which form a receiving cavity for an element of the mounting structure (not shown).

[0025] The glazing of Figure 3 differs from that of Figure 2 only in that the first glass sheet 1 covers the upper edge, facing the outside atmosphere in the mounting position, of the mounting seal 8, so as to protect the silicone seal 8. The double glazings of Figures 2 and 3, like that of Figure 1, allow flush mounting of the glazing relative to the fuselage of the aircraft, not shown. They also make it possible to limit the surface mass of the glazing by the use of transparent polymer material, as well as the deflection and drag in flight, by the use of mineral glass, when the interior volume of the aircraft is pressurized.

Claims

Claims 1. Multiple glazing for delimiting two spaces with variable pressure difference, in particular an enclosure subjected to pressurization, comprising at least one first transparent slab (1; 2; 3; 4; 5) intended to be in contact with the external atmosphere in the mounting position, and separated from a second transparent slab (7) by an air gap (6), by means of a mounting joint (8) in which a peripheral part of the multiple glazing is embedded, characterized in that the first slab (1; 2; 3; 4; 5) consists of a first transparent sheet (1) and at least two other transparent sheets (3; 5) bonded two by two by an intermediate adhesive layer (2; 4), in that at least one of the first transparent sheet (1) and the at least two other transparent sheets (3;5) is made of mineral glass, and in that another of the first transparent sheet (1) and the second transparent sheet (3) is made of organic glass and has stepped edges, the edges of an outer fraction of the thickness of this sheet (1 or 3) being set back from the edges of its inner complementary fraction, so as to form, where appropriate with the edges of the first sheet (1) and the first adhesive layer (2), a cavity for receiving an element of the mounting structure, with the interposition of the mounting seal (8).; 2. Multiple glazing according to claim 1, characterized in that the first transparent sheet (1) is made of organic glass and has stepped edges forming a receiving cavity for an element of the mounting structure, in that the at least two other transparent sheets (3; 5) comprise at least a second transparent sheet (3) of mineral glass and a third transparent sheet (5) of organic glass or mineral glass, or a second transparent sheet (3) of organic glass and a third transparent sheet (5) of mineral glass.

3. Multiple glazing according to claim 1, characterized in that the second transparent sheet (3) is made of organic glass and has stepped edges forming, with the edges of the first transparent sheet (1) and the first adhesive layer (2), a receiving cavity for an element of the mounting structure, in that the first transparent sheet (1) is made of mineral glass, or of organic glass and the at least two other transparent sheets (3; 5) comprise a third transparent sheet (5) made of mineral glass.

4. Multiple glazing according to one of the preceding claims, characterized in that each sheet of mineral glass is made of soda-lime, aluminosilicate, borosilicate, in particular float glass, possibly hardened, thermally toughened or chemically reinforced, and has a thickness of between 0.5 and 6, preferably 2 and 4 mm.

5. Multiple glazing according to one of the preceding claims, characterized in that each sheet of organic glass is made of polymer material consisting of poly(methyl methacrylate) (PMMA), polycarbonate (PC), poly(ethylene terephthalate) (PET), polyurethane (PU), their mixtures or copolymers, and has a thickness of between 2 and 15, preferably 3 and 6 mm.

6. Multiple glazing according to one of the preceding claims, characterized in that each interlayer adhesive layer is made of polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), thermoplastic polyurethane (TPU), ionomer resin or casting resin, and has a thickness of between 0.3 and 6.0, preferably 0.5 and 1.5 mm.

7. Multiple glazing according to one of the preceding claims, characterized in that it comprises materials of different densities, stiffnesses and damping, such as to give it an acoustic insulation property.

8. Multiple glazing according to one of the preceding claims, characterized in that the first transparent sheet (1) covers the edge of the seal (8) facing outwards.

9. Use of multiple glazing according to one of the preceding claims as glazing for pressurized aircraft, in particular a passenger cabin window for a commercial aircraft.

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