Bolt-on aircraft glazing and kit including it

Abstract

------ Bolt-on aircraft glazing and kit comprising it. The invention relates to aircraft glazing (300) comprising a transparent surface (302) with several through holes (302i) formed around the periphery of the glazing (300), each through hole (302i) having a frustoconical portion flaring out on the outer face of the transparent surface (302) and narrowing towards a cylindrical portion extending from the frustoconical portion to open onto the inner face of the transparent surface (302), a rigid hollow sleeve (309) having a frustoconical head (309a) extended by a cylindrical body (309b) being disposed in each through hole (302i) with a damping material (308) disposed between the sleeve (309) and the inner surface of the corresponding through hole (302i). Figure to be published with the abbreviation: Figure 4

Description

Title of the invention: Bolted aircraft glazing and kit comprising it

[0001] The invention relates to glazing intended for use in the aeronautical field.

[0002] Glazing used in the aeronautical field, particularly in small aircraft, can be pinched, glued or bolted to the aircraft fuselage.

[0003] Bonded glazing has a simple structure in which the transparent surface of the glazing is bonded at its periphery to the aircraft fuselage. The disadvantage of this embodiment is the complexity of assembly and disassembly.

[0004] Pinch-on glazing has a more complex structure and requires pinching the transparent surface of the glazing between the fuselage and an external bracket located around the periphery of the transparent surface. The pinch-on glazing is held in place by bolting the bracket and the fuselage.

[0005] Bolted glazing also requires an external flange around the perimeter of the transparent surface. The glazing is held in place by bolting the flange, which is thinner, to the transparent surface and the fuselage.

[0006] In both of these embodiments, the bolting is carried out using countersunk head screws to ensure aerodynamic performance.

[0007] The drawback of these embodiments is that the clamped and bolted glazing requires a non-constant thickness of the transparent glazing surface to accommodate a mounting bracket. This leads to the use of an unnecessary thickness of plastic, machining (or lamination) steps, and mechanical fragility at the machining angle. Furthermore, this results in additional mass and a more complex structure.

[0008] The invention proposes to overcome these drawbacks of the prior art and to bolt the transparent surface to the fuselage of the aircraft by means of rigid hollow sleeves or bushings arranged in holes through the transparent surface, at the periphery of the glazing, in such a way that tightening the bolt compresses the sleeve but does not generate clamping stresses on the transparent surface.

[0009] The presence of the sleeve prevents excessive stress from being placed on the transparent surface at the point of drilling, particularly during the bolting stage. During the glazing's service life, the stresses induced by expansion or swelling due to moisture absorption of the transparent surface are difficult to manage when directly tightening the transparent surface. The invention therefore overcomes these drawbacks.

[0010] The object of the invention is an aircraft glazing configured to be fixed to an aircraft fuselage with an intermediate peripheral seal between the glazing and the fuselage, said glazing comprising a transparent surface having an inner face, configured to rest on the peripheral seal, and an opposite outer face, characterized in that several through holes are formed in the periphery of the glazing, the through holes being formed in the thickness of the transparent surface, each through hole having a frustoconical portion flaring out on the outer face of the transparent surface and narrowing towards a cylindrical portion extending from the frustoconical portion to open onto the inner face of the transparent surface, a rigid hollow sleeve having a frustoconical head extended by a cylindrical body being disposed in each through hole,a damping material being disposed between the liner and the internal surface of the corresponding through hole, the damping material extending around the truncated conical head of the liner and continuing into the cylindrical portion of the through hole at least to half the thickness of the transparent surface, the length of the cylindrical portion of the liner and the damping material being configured, when the glazing is bolted to an aircraft fuselage with an intermediate peripheral seal, to withstand a clamping force from a truncated conical head screw inserted into the through hole through the liner and configured to pass through the transparent surface, the seal and the fuselage and to receive at its free end a nut for bolting the glazing to the fuselage.

[0011] The jacket is therefore always in indirect contact with the hole in the transparent surface by the damping material, the damping material always being present around the truncated conical head of the jacket.

[0012] Thus, the stresses exerted during the tightening of the screw are transferred either to the damping material and the sleeve, if the latter has a length such that the cylindrical body is configured to touch the fuselage in use, or only to the damping material, which then transmits the forces to the fuselage.

[0013] This gives us a glazing that is easy to manufacture, without mechanical fragility induced by difference in thickness of the glazing, since it is enough to drill holes in the thickness of the glazing (direction going from the inner face to the outer face of the transparent surface of the glazing) and then add a damping material and sleeves.

[0014] The added damping material advantageously fills the gap between the dimensions of the sleeve and the dimensions of the through hole into which it is inserted. This damping material also ensures airtightness and watertightness and accommodates structural deformations that could place a significant load on the hole.

[0015] According to one embodiment, the cylindrical body of the sleeve extends over all or part of the cylindrical portion of the through hole. When the cylindrical body of the sleeve extends over the entire cylindrical portion of the through hole, it is this cylindrical portion that bears the clamping forces.

[0016] According to one embodiment, the damping material has a Shore hardness between 20 Shore A and 100 Shore A, which corresponds to a modulus of elasticity between 1 and 100 MPa.

[0017] According to one embodiment, the jacket is made of a material chosen from a metal, preferably chosen from aluminium, stainless steel and titanium, a plastic material and a composite material.

[0018] According to one embodiment, the damping material is integrated into the corresponding jacket or attached to it, which means that the damping material can be pre-applied to the glazing or attached to it at the time of assembly on the fuselage.

[0019] According to one embodiment, the transparent surface is made of one of polymethyl methacrylate (PMMA), polycarbonate and polyurethane, preferably bi-stretched PMMA.

[0020] Bi-stretched PMMA exhibits low resistance to the propagation of cracks parallel to its surface. The glazing according to the invention allows the use of this material without these drawbacks because the clamping compresses the liner but does not generate clamping stresses on the PMMA itself.

[0021] Another object of the invention relates to an aircraft fuselage kit comprising aircraft glazing as defined above and a peripheral seal configured to fit between the glazing and the aircraft fuselage, the peripheral seal comprising through holes configured to be opposite the through holes of the glazing for fixing the glazing and the peripheral seal to the fuselage by bolting.

[0022] To better illustrate the object of the present invention, particular embodiments will now be described, by way of example and not limitation, in connection with the attached drawings.

[0023] On the drawings:

[0024] [Fig-1] is a schematic cross-sectional view of a bonded glazing unit according to the state of the technical.

[0025] [Fig.2] is a schematic cross-sectional view of a pinched glazing according to the state of the technical.

[0026] [Fig.3] is a schematic cross-sectional view of a bolted glazing unit according to the state of the technical.

[0027] [Fig.4] is a schematic cross-sectional view of a glazing according to a first mode of realization of the invention.

[0028] [Fig.5] is a schematic cross-sectional view of a glazing according to a second mode of realization of the invention.

[0029] [Fig.6] is a schematic cross-sectional view of a glazing according to a third mode of realization of the invention.

[0030] Figure 1 illustrates the prior art for a bonded glazing 1, which comprises a transparent surface 2 bonded at its periphery to the fuselage 4 of an aircraft. The bonding can be achieved using a layer of urethane 3. This type of bonded glazing 1 does not allow for easy assembly and disassembly.

[0031] Fig. 2 represents the state of the art for a pinched glazing 100.

[0032] The pinched glazing 100 comprises a transparent surface 102 sandwiched at its periphery by the fuselage 104 on the inner side and a flange 105 on the outer side. The transparent surface 102 has a thinner profile at its periphery 102a to accommodate the flange 105 on the outer side of the transparent surface 102. The fuselage 104 has a Z-shaped configuration such that it retains the pinched glazing 100 at its periphery. The pinched glazing 100 is attached to the aircraft fuselage 104 by bolting the flange 105 and the fuselage 104 together using a countersunk screw 106 and a nut 107, the countersunk screw 106 being intended to ensure aerodynamics.

[0033] Fig. 3 represents the prior art for a bolted glazing 200.

[0034] The bolted glazing 200 comprises a transparent surface 202 having a thinner edge 202a to accommodate a bracket 205 on the outer side. The inner portion of the transparent surface 202 rests on the aircraft fuselage 204. The bolted glazing 200 is attached to the fuselage 204 by bolting the bracket 205, the transparent surface 202, and the fuselage 204 together using a countersunk screw 206 and a nut 207.

[0035] Figure 4 represents aircraft glazing according to a first embodiment of the invention.

[0036] The glazing 300 according to the invention comprises a transparent surface 302, a peripheral seal 303 formed on the inner face of the transparent surface 302 and configured to bear against the fuselage 304 of an aircraft. Several through holes 302i are formed around the periphery of the thickness of the transparent surface 302, each having a frustoconical portion flaring out on the outer face of the transparent surface 302 and extending into a cylindrical portion extending from the frustoconical portion to and through the peripheral seal 303. A rigid hollow sleeve 309 having a frustoconical head 309a extended by a cylindrical body 309b is disposed in each through hole 302i such that the frustoconical head 309a of the sleeve 309 bears against the frustoconical portion of the corresponding through hole 302i.

[0037] The frustoconical portion 309a of the sleeve 309 is configured to withstand a clamping force from a frustoconical head screw 306 inserted into the through hole 302i and configured to pass through the transparent surface 302, the seal 303 and the fuselage 304 and to receive at its free threaded end a nut 307 for bolting the glazing 300 to the fuselage 304. In this way, the tightening during bolting compresses the sleeve 309 but does not generate clamping stresses on the transparent surface 302.

[0038] The transparent surface 302 is made of a material among polycarbonate and polyurethane, preferably bi-stretched PMMA and glass, preferably the transparent surface 302 is organic, in particular bi-stretched PMMA.

[0039] The sleeve 309 is made of a material including a metal, preferably selected from aluminium, stainless steel and titanium, a plastic material and a composite material

[0040] A damping material 308 can be disposed between the sleeve 309 and the transparent surface 302, at least over the entire height of the frustoconical head 309a of the sleeve 309. The damping material 308 can be in the form of a gasket or sealant and ensures airtightness and watertightness while accommodating deformations of the structure that could significantly load the hole 302i. The damping material preferably has a Shore hardness between 20 Shore A and 100 Shore A, and may in particular be 40 Shore A.

[0041] Each sleeve 309 is fixed to the corresponding through hole 302i or inserted into it.

[0042] In this first embodiment, the path of the screw tightening force passes through the screw head 306, the sleeve 309, the damping material 308, the peripheral seal 303 and the fuselage 304.

[0043] Fig. 5 represents aircraft glazing 400 according to a second embodiment.

[0044] Elements of the same structure as the first mode of the invention described in connection with [Fig.4] shall bear the same reference number increased by 100, and shall not be described in further detail here.

[0045] The difference between this second embodiment and the general concept of the invention lies in the fact that the cylindrical body of the sleeve 409 extends over the entire cylindrical part of the through hole 402i, so that the lower part of the cylindrical body 409b of the sleeve 409 comes to rest against the upper part of the fuselage 404.

[0046] In this second embodiment, the path of the screw tightening force passes through the screw head 406, the sleeve 409 and the fuselage 404. This makes it possible not to constrain the transparent surface 402.

[0047] Figure 6 represents aircraft glazing 500 according to a third embodiment.

[0048] Elements of the same structure as the first embodiment shall bear the same reference number increased by 200, and shall not be described in further detail here.

[0049] The difference between the second embodiment and the third embodiment lies in the fact that the cylindrical body of the sleeve 509 extends over the entire cylindrical part of the through hole as well as the damping material 508.

[0050] In this third embodiment, the path of the force passes through the screw 506, the sleeve 509 and the fuselage 504. This makes it possible not to constrain the transparent surface 502.

Claims

1. Demands - Aircraft glazing (300; 400; 500) configured to be fixed to an aircraft fuselage (304; 404; 504) with a peripheral seal (303; 403; 503) intermediate between the glazing (300; 400; 500) and the fuselage (304; 404; 504), said glazing (300; 400; 500) comprising a transparent surface (302; 402; 502) having an inner face, configured to rest on the peripheral seal (303; 403; 503), and an opposite outer face, characterized in that several through holes (302i; 402i; 502i) are formed in the periphery of the glazing (300; 400; 500), the through holes (302i; 402i; 502i) being formed in the thickness of the transparent surface (302; 402; 502), each through hole (302i; 402i; 502i) having a frustoconical part flaring out on the outer face of the transparent surface (302; 402;502) and narrowing towards a cylindrical part extending from the truncated conical part to open onto the inner face of the transparent surface (302; 402; 502), a rigid hollow sleeve (309; 409; 509) having a frustoconical head (309a; 409a; 509a) extended by a cylindrical body (309b; 409b; 509b) being disposed in each through hole (302i; 402i; 502i), a damping material (308; 408; 508) being disposed between the sleeve (309; 409; 509) and the internal surface of the corresponding through hole (302i; 402i; 502i), the damping material (308; 408; 508) extending around the frustoconical head (309a; 409a; 509a) of the sleeve (309; 409; 509) and extending into the cylindrical part of the through hole (302i ; 402i ; 502i) at least up to half the thickness of the transparent surface (302 ; 402 ; 502), the length of the cylindrical portion (309b ; 409b ; 509b) of the liner (309 ; 409 ; 509) and the damping material (308 ; 408 ; 508) being configured, when the glazing (300 ; 400 ; 500) is bolted to an aircraft fuselage (304 ; 404 ; 504) with a peripheral seal (303 ; 403 ;503) intermediate, to support a clamping force of a screw (306; 406; 506) with a truncated conical head inserted into the through hole (302i; 402i; 502i) through the sleeve (309; 409; 509) and configured to pass through the transparent surface (302; 402; 502), the joint (303; 403; 503) and the fuselage (304; 404; 504) and receive at its free end a nut (307; 407; 507) to bolt the glazing (300; 400; 500) to the fuselage (304; 404; 504).

2. - Aircraft glazing (300; 400; 500) according to claim 1, characterized in that the cylindrical body (309b; 409b; 509b) of the sleeve (309; 409; 509) extends over all or part of the cylindrical part of the through hole (302i).

3. - Aircraft glazing (300; 400; 500) according to any one of claims 1 and 2, characterized in that the damping material (308; 408; 508) has a Shore hardness between 20 Shore A and 100 Shore A.

4. - Aircraft glazing (300; 400; 500) according to any one of claims 1 to 3, characterized in that the liner (309; 409; 509) is made of a material among a metal, preferably selected from aluminium, stainless steel and titanium, a plastic material and a composite material.

5. - Aircraft glazing (300; 400; 500) according to any one of claims 1 to 4, characterized in that the damping material (308; 408; 508) is integrated into or attached to the corresponding jacket (309; 409; 509).

6. - Aircraft glazing (300; 400; 500) according to any one of claims 1 to 5, characterized in that the transparent surface (302; 402; 502) is made of one of polymethyl methacrylate (PMMA), polycarbonate and polyurethane, preferably bi-stretched PMMA.

7. - Aircraft fuselage kit comprising aircraft glazing (300; 400; 500) according to any one of claims 1 to 7 and a peripheral seal (303; 403; 503) configured to fit between the glazing (300; 400; 500) and the aircraft fuselage (304; 404; 504), the peripheral seal (303; 403; 503) comprising through holes configured to be opposite the through holes (302i; 402i; 502i) of the glazing (300; 400; 500) for fixing the glazing (300; 400; 500) and the peripheral seal (303; 403; 503) to the fuselage (302; 402; 502).

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