Pressure bulkhead and method for subdivision of an aircraft or spacecraft

The present invention provides a pressure bulkhead for subdivision of an aircraft or spacecraft into an internal and an external pressure region. The pressure bulkhead comprises a pressure plate having an edge shaped so as to correspond to an inner contour of the aircraft or spacecraft, a supporting means which tiltably supports the edge on the inner contour, and a seal which seals the edge with the inner contour. A further aspect of the invention provides a method for subdivision of an aircraft or spacecraft into an internal and an external pressure region. Firstly, a pressure plate is provided that has an edge shaped so as to correspond to an inner contour of the aircraft or spacecraft. In further steps, the edge is tiltably supported on the inner contour and sealed with the inner contour.

The present invention relates to a pressure bulkhead for subdivision of an aircraft or spacecraft. The invention further relates to a structural component and an aircraft or spacecraft with a pressure bulkhead of this type, and also to a method for subdivision of an aircraft or spacecraft.

Although applicable to subdivisions of any desired vehicles or containers, the present invention and also the problems underlying it will be described in greater detail in relation to the rear pressure bulkhead of an aircraft.

In aircraft flying at very high altitudes, such as for example modern commercial aircraft, the passenger compartment, cockpit and cargo hold are generally designed as a pressure tight cabin within which it is possible to maintain during flight an air pressure which is greater than the external pressure and allows passengers and crew to survive without oxygen masks or similar respiratory equipment. In order to close off a pressurised cabin of this type toward the back of the fuselage, it is conventional to install in the rear region of the fuselage a hermetic partition which is referred to as a pressure bulkhead and subdivides the interior of the fuselage into a front portion, which forms the pressurised cabin, and a rear portion, in which for example an auxiliary drive for generating electrical energy and compressed air is accommodated.

A pressure bulkhead of this type can for example be designed in the form of a flat wall which is conventionally made of an aluminium alloy and is riveted in the manner of a former to the outer skin and in this way discharges its loads, both forces and bending moments, into the surrounding structure. As the pressure differential between the pressurised cabin and outside air fluctuates greatly each time the flight altitude changes and in particular during the cyclically occurring take-offs and landings, the bending moments introduced into the outer skin, for example, lead to correspondingly cyclically variable deformation of the outer skin and thus contribute to material fatigue.

Other designs of pressure bulkheads use the shape of a doubly curved spherical shell portion or a spherical cap, for example, which are arched toward the back of the fuselage in order in this way to reduce internal stresses in the material of the pressure bulkhead and the outer skin. This is set against an increase, caused by the arching, in the space required for the pressure bulkhead.

It is therefore the object of the present invention to disclose a design for a pressure bulkhead that, while requiring little space, reduces the introduction of mechanical stresses into the surrounding structure.

According to the invention, this object is achieved by a pressure bulkhead having the features of patent claim1, by a structural component having the features of patent claim20, an aircraft or spacecraft having the features of patent claim21, and also by a method for subdivision of an aircraft or spacecraft into an internal pressure region and an external pressure region having the features of patent claim22.

The idea underlining the present invention consists in using, to form the pressure bulkhead, a pressure plate having an edge shaped so as to correspond to an inner contour of the aircraft or spacecraft, the edge being tiltably supported on the inner contour and sealed. As the edge is supported tiltably, only forces, but no bending moments, are transmitted between the pressure plate and outer skin of the aircraft or spacecraft at the supporting point. Deformation of the pressure plate, which occurs when the pressure differential between the internal pressure region and external pressure region changes, therefore leads only to local tilting of the edge of the pressure plate in relation to the outer skin, i.e. to variation of the angle enclosed between respective tangential faces of the outer skin and the pressure plate at the common supporting point.

The fact that the tiltable supporting does not transmit any bending moments into the outer skin prevents mechanical stresses and thus deformation and material fatigue of the outer skin. This does not require the pressure plate to be arched, so the pressure bulkhead requires little space and the amount of space that can actually be used in the aircraft increases.

The sub-claims contain advantageous configurations and improvements of the invention.

According to a preferred development of the pressure bulkhead according to the invention, an annular element is also provided that borders the pressure plate along its edge. The edge is supported by the supporting means in this case on the annular element, and the seal seals the annular element with the inner contour. The annular element imparts additional stability to the pressure plate. Preferably, the annular element comprises as a material steel, titanium, aluminium or carbon fibre reinforced plastics material.

Preferably, the annular element has an L-shaped profiled part with a first and a second profiled part leg. In this case, the first profiled part leg extends parallel to the main plane of the pressure plate and rests against the pressure plate on sides of the external pressure region. This leg supports the plate in the direction toward the external pressure region and absorbs the forces acting on the plate when, during flight, the internal pressure is higher than the external pressure. The second profiled part leg extends perpendicularly to the main plane of the pressure plate along the edge thereof. This leg comprises the edge of the plate, so said plate is retained in the annular element in a stable manner and cannot move laterally.

According to a preferred development, the pressure plate is embodied to be retained in the annular element by a pressure differential between the internal pressure region and the external pressure region. This allows the edge of the plate to move in relation to the annular element if, for example, the plate is deformed by the action of the pressure differential between the internal pressure region and external pressure region. This prevents deformation of the annular element itself, thus further reducing the introduction of stresses into the surrounding structure.

According to a further preferred development, the pressure plate is riveted, screwed or adhesively bonded to the annular element. This allows the connection between the plate and annular element to be made particularly stable and tight.

According to a preferred development, counter supports are also provided that support the pressure plate toward the internal pressure region. This has the advantage that the pressure plate is securely retained even when there is no pressure differential between the internal pressure region and external pressure region, such as is for example regularly the case on the ground.

According to a preferred development, the supporting means comprises at least one pull tab extending from the edge of the pressure plate along an inner face of an outer skin of the aircraft or spacecraft into the internal pressure region. In this case, the pull tab is fastened by one end to the pressure plate and by another end to the outer skin. As a pull tab arranged in this way discharges substantially only tangential tensile forces into the outer skin, deformation and stressing of the outer skin are prevented in a particularly effective manner. As the pull tab is, in addition, fastened at its respective ends, its middle portion remains freely deformable and can yield to deformation of the edge of the pressure plate or the annular element without discharging said deformation into the outer skin.

Preferably, the pull tab is fastened to the outer skin by riveting. The rivets ensure a safe introduction of force and are ideally loaded almost purely with shear forces. Preferably, the pull tab is fastened to the outer skin below a stringer of the aircraft or spacecraft, allowing force to be introduced in a manner that is particularly gentle on the outer skin.

According to a preferred development, the supporting means comprises at least one articulated element. In this case, a first articulated arm is fastened to the edge of the pressure plate; a second articulated arm is fastened to an outer skin of the aircraft or spacecraft. Articulated elements of this type allow high forces to be discharged into the outer skin and at the same time to particularly reliably rule out, as a result of the pivotability of the articulated arms relative to one another, any transmission of bending moments.

Preferably, the second articulated arm is fastened to a reinforcing element which reinforces the outer skin in the external pressure region. For example, the second articulated arm can be attached to a former extending behind the pressure bulkhead in the external pressure region, allowing force to be reliably introduced into the surrounding structure.

Preferably, the articulated element also comprises a joint bolt extending substantially in a direction which is tangential to the edge of the pressure plate in the region of the fastening of the first articulated arm. A bolt oriented in this way selectively allows the edge of the pressure plate to tilt in relation to the outer skin toward the outer skin region if the pressure plate warps on account of a pressure differential between the internal pressure region and external pressure region. At the same time, contortions in other directions are prevented and the stability of the overall structure is in this way increased. Preferably, the first and/or second articulated arms comprise an aluminium and/or steel material, so high forces are reliably transmitted. The joint bolt preferably comprises a steel material.

According to a preferred development, the pressure plate is embodied as a sandwich component. Preferably, the sandwich component comprises a core having a honeycomb structure and/or a foam material, and also a cover layer comprising a carbon fibre reinforced plastics material, a glass reinforced plastics material and/or an aluminium material. A sandwich component of this type is distinguished by high flexural strength at low dead weight.

Preferably, the pressure plate is embodied so as to be more rigid in a central region than at the edge, for example as a result of a thicker core or additionally laminated-on cover layers. This allows the inevitable deformation of the pressure plate under the action of the pressure differential to be minimised and the weight of the pressure plate to thereby be kept low.

In the figures, unless otherwise stated, like reference numerals denote identical or functionally identical components.

FIG. 1is a perspective internal view of a detail of the hull of a fuselage. The outer skin120of the hull is reinforced at its inner face204by stringers124extending in the longitudinal direction of the aircraft and formers308extending perpendicularly thereto along the circumference of the fuselage.

A pressure bulkhead100, which subdivides in a pressure tight manner the fuselage along an inner contour108into an internal pressure region102and an external pressure region104, is located in the region of the illustrated detail. For example, the internal pressure region102consists of a pressurised cabin102comprising the passenger compartment, the cargo hold and the cockpit, whereas the external pressure region104is for example a space104which is positioned at the tail of the aircraft, behind the pressurised cabin102, and is used to accommodate an auxiliary drive.

The pressure bulkhead100comprises a pressure plate106, the edge110of which extends along the inner contour108, so the cross-section of the fuselage is filled out substantially by the pressure plate106at the position defined by the inner contour. For the sake of clarity, the pressure plate is shown in transparent form inFIG. 1, so the portions of the stringers124and the formers308that are arranged in the external pressure region104are visible inFIG. 1. The pressure plate106is designed as a sandwich component, i.e. it consists of a core having a foamed, honeycomb or similar structure and cover layers which are located on both sides and absorb tensile and compressive force. Carbon fibre or glass reinforced plastics material or a metal sheet made of an aluminium alloy can for example be used for the cover layers.

The edge of the pressure plate106is bordered by an annular element116which has an L-shaped profiled part and supports the pressure plate106both in the direction of the external pressure region104and in the radial direction of the fuselage, i.e. in the direction toward the outer skin120. Suitable materials for the annular element116are steel, titanium, aluminium or carbon fibre reinforced plastics material. The edge110of the pressure plate106can optionally be adhesively bonded, screwed or riveted to the annular element116.

The annular element116is connected to the outer skin120via pull tabs112which are riveted by one end to the annular element116, extend along the inner face204of the outer skin120into the internal pressure region102and are fastened in the internal pressure region to the outer skin120by means of rivets122. Suitable materials for the pull tabs112are for example steel or titanium. A seal114, which is made for example of rubber, is inserted between the annular element116and the former308resting on the outer skin120and seals the annular element116from the outer skin120.

During flight operation, the higher the flight altitude of the aircraft, the more the air pressure in the external pressure region104falls. An air pressure greater than the external pressure is maintained in the internal pressure region102, resulting in the build-up of a pressure differential between the internal pressure region102and external pressure region104that exerts on the pressure plate106a force directed in the direction of the external pressure region104. This force presses the pressure plate106into the annular element116, so the pressure plate106is retained in the annular element116even without riveting, a screw connection or adhesive bonding. The annular element116absorbs the press-on force of the pressure plate106in the direction of the external pressure region104and introduces it, as a tensile force extending parallel to the outer skin120, into the outer skin120via the pull tabs112.

In order to securely retain the pressure plate106in the annular element116even when, for example while the aircraft is on the ground, there is no pressure differential between the internal pressure region102and external pressure104of the aircraft, counter supports118are also provided that are fastened to the stringers on sides of the internal pressure region102at uniform intervals and support the pressure plate106in the direction of the internal pressure region102.

The supporting of the pressure plate106will be described in greater depth based on a detail shown inFIG. 2of the structural component fromFIG. 1. The L-shaped profiled part of the annular element116is formed by a first profiled part leg200, which supports the pressure plate106in the direction of the external pressure region104, and a second profiled part leg202, which borders the edge110of the pressure plate106. An inner seal (not shown), which is made of a rubber or foam material, for example, and prevents air from escaping from the internal pressure region102through any remaining gaps between the pressure plate106and the annular element116, can be provided between the pressure plate106and the annular element116. The sealing of the pressure plate106with the annular element116can for example also be achieved by adhesively bonding the pressure plate to the annular element.

The pull tab112is, starting from the internal pressure region102, guided around both legs202,200of the annular element116and fastened, for example by riveting using rivets (not shown here), by the annular element116to the first leg200or to both legs200,202. When a pressure differential206between the internal pressure region102and external pressure region104is applied to the pressure plate106, the pull tab112is loaded with tensile force. The rivets122, by which the pull tab112is fastened to the outer skin120, as well as the rivets (not shown) by which the pull tab112is fastened to the annular element116are in this case loaded almost exclusively with shear forces.

If, during flight operation, the pressure differential206causes arching, which is inevitable at least to a low degree, of the pressure plate106in the direction of the external pressure region104, tilting moments, which seek to tilt the edge110of the pressure plate106in the direction of the external pressure region104, occur in the region of the edge110. However, these tilting moments are not discharged by the pull tab112into the outer skin120, so the outer skin120is not warped. The tensile loading of the pull tabs112stretches them lengthwise, so the annular element116moves slightly in the direction of the external pressure region104and, in doing so, presses the seal114against the former308.

FIG. 3is a detailed cross-sectional view of the fastening of a pressure bulkhead according to a second embodiment. As in the first embodiment shown inFIGS. 1 and 2, the pressure bulkhead comprises a pressure plate106which is retained in an annular element116with an L-shaped profiled part. Counter supports118are also provided that are fastened to the stringers124and prevent the pressure plate106from falling out of the annular element116, wherein the pressure plate can optionally be adhesively bonded, screwed or riveted to the annular element116. The pressure plate106is designed as a sandwich component106having a folded honeycomb structure314enclosed between two cover layers316. Both the folded honeycomb structure314and the cover layers316are designed so as to be thicker in a central region300of the pressure plate106than at the edge110; this increases the rigidity of the pressure plate106in the central region300and in this way imparts to the pressure plate106the property of deforming just slightly under the action of the pressure differential206.

In contrast to the embodiment fromFIGS. 1 and 2, the annular element116is supported in relation to the outer skin120and the former308reinforcing the outer skin by means of an articulated element302arranged in the external pressure region104between the annular element116and the former308. The articulated element302comprises a first articulated arm304which is riveted or screwed to the leg of the annular element116that extends parallel to the pressure plate106. A second articulated arm306is supported both in relation to the outer skin120and in relation to the former308and fastened thereto, for example by riveting. Both articulated arms304,306are connected so as to be able to pivot relative to each other via a joint bolt310extending parallel to the pressure plate306and to the local tangent to the outer skin120.

In contrast to the first embodiment, a seal114, which is made for example of rubber and seals the annular element116with the outer skin, is arranged in the internal pressure region102and is pressed onto the outer skin120and annular element116directly as a result of the pressure differential206.

In the second embodiment shown inFIG. 3, the supporting of the pressure plate106is further clarified by the perspective view inFIG. 4. Articulated elements302are arranged at uniform intervals along the circumference of the fuselage, the joint bolts each being oriented parallel to the local tangent to the outer skin and thus being directed slightly differently from the joint bolt of the respectively adjacent articulated element302. The second articulated arms306of the articulated elements302are each designed as an eyebolt fork302, between the prongs of which the respectively associated first articulated arm304is inserted and articulated by the joint bolt310. The joint bolts are made of steel, for example; the articulated arms304,306are also made of steel or of aluminium.

During flight operation, the pressure bulkhead experiences, as a result of the action of the pressure differential between the external pressure region102and internal pressure region104, inevitable deformation leading to local tilting of the edge110of the pressure plate106in relation to the outer skin120in the direction of the external pressure region104. The articulated elements302allow corresponding tilting of their articulated arms304,306relative to each other, so the deformation of the pressure plate does not transmit any bending moments into the outer skin120.

Although the present invention has in the present document been described based on preferred embodiments, it is not limited thereto, but can be modified in a broad range of ways.

For example, it is possible for the pull tabs not or not only to be arranged between the stringers and riveted to the outer skin, as shown for the first embodiment; on the contrary, alternatively or additionally, they can be guided under the stringers, between the stringer and outer skin, and riveted to both. It is also possible to provide a single pull tab, in the form of an approximate cylinder sheath, extending around the entire fuselage. Furthermore, pull tabs and articulated elements can for example be provided combined in one embodiment, in the same or different portions of the inner contour of the fuselage.

A pressure plate can also be designed in a plurality of parts, a first part closing off a cargo hold below a passenger floor and a second part closing off a passenger compartment above the passenger floor, for example. Seals can be designed in a broad range of ways, including for example as rubber hollow profiled parts which are opened toward the internal pressure region and inflate as the pressure falls in the external pressure region.

LIST OF REFERENCE NUMERALS