Air inlet valve for an airplane and manufacturing method for an air inlet valve

The present invention provides an air intake valve for an aircraft and a method for the production of an air intake valve. The air intake valve has an opening region for letting ambient air through into a fuselage inner region of the aircraft and a flap for opening and closing the opening region, the opening region and the flap each having a shape which is capable of forming air vortices on edges of the opening region when ambient air flows through the air intake valve.

FIELD OF THE INVENTION

The invention relates to a flow-optimised air intake valve for an aircraft according to the preamble of claim1and to a method for the production of an air intake valve of this type according to the preamble of claim26. The invention provides a flow-optimised air intake valve which is positioned in the region of a submerged air inlet and is constructed to be self-regulating under the influence of the force conditions acting thereon in an air pressure-loading manner. The use of the air intake valve produces an optimisation, adapted to the aerodynamic flow conditions, of the air flowing into the submerged air inlet during an air pressure equalisation which takes place between the outer environment of the aircraft and the interior of the aircraft fuselage.

A conventional aircraft fuselage is constructed as a pressure fuselage. In this respect, the static air pressure inside the fuselage must be greater than the air pressure outside the environment of the aircraft. For safety reasons, air valves are installed in the outer skin of the aircraft which operate independently and which produce a pressure equalisation in the (assumed) situation of an occurring inverse differential pressure between the pressure-ventilated inner region of the fuselage (cabin and hold region) and the outer region of the fuselage loaded by an atmospheric ambient pressure. If it is assumed that the atmospheric ambient air pressure (external air pressure) is greater than the air pressure inside the fuselage (internal air pressure), an air intake valve which is installed in the outer skin of the fuselage (or so-called outer skin valve) will be activated.

Known air pressure equalising valves of this type operate such that (initially) when a certain inversely-acting differential pressure is exceeded, it is observed that the (resulting) force from a static external air pressure which is loaded on a valve cover outside the aircraft fuselage is greater than a (so-called) closing force (compression force) of springs positioned inside the aircraft skin and which press perpendicularly against the edges of a plate. As a result of this, the valve opens and air flows from the environment outside the aircraft fuselage to the inner region of the fuselage and produces an air pressure equalisation. The inflow of this air is not optimised by the adjustment of any measures. A more detailed description will be provided later on in the embodiments of conventional construction solutions which relate to an air intake valve (installed in “Boeing” types of aircraft) and an air pressure equalising valve (installed in “Airbus” types of aircraft), the installation of which is performed to equalise inverse differential pressures arising between the pressure-ventilated fuselage region and the region outside the fuselage loaded by an atmospheric ambient pressure and which are arranged in the region of air inlets integrated into the aircraft skin, to simplify to experts the comparison with a flow-optimised air intake valve which will be described in more detail. As is known, the products “Airbus A330/A340” and “Boeing 737” are fitted with valves of this type.

In this respect, it is a disadvantage that the actual air flow which enters the aircraft fuselage via these mentioned valves under inverse pressure conditions is greatly influenced by the external air flow (surrounding the aircraft fuselage) (by the type of valves) and thus cannot effectively be determined without an expensive series of tests being carried out in the aircraft.

FIG. 1shows (in a side view) a conventional flow-optimised air intake valve2. It is arranged in the region of a submerged air inlet1which is in a position closing the opening region6of the submerged air inlet1. It consists of a side frame16which is arranged resting sideways against the submerged air inlet wall region and covers the cross section of the opening region6at least at the inlet of the submerged air inlet1. This side frame16is adapted to a cross section, kept clear (above the opening region6) of the fuselage outer skin15of the aircraft and is attached to the fuselage outer skin15. The side frame16consists of planar sheet metal plate elements or planar supports (plank elements) which, in the following, are termed transverse and longitudinal sides10,11,13,14. This side frame16comprises two transverse sides10,11and two longitudinal sides13,14, the ends of which are connected together mechanically and form a rectangular side frame16(according toFIG. 2).

Mounted at the start of the incipient bevel of the base of the submerged air inlet1is a (rotatably mounted) flap8which can be inclined towards the inner region7of the fuselage (opening outlet of the submerged air inlet1) and is rotatably attached to at least one spring hinge19secured to the frame. The flap movement is indicated inFIG. 1by an arrow marked “open/closed”. The flap8rests on a groove-like recess arranged on the inside of the frame and placed around the periphery of the frame, a strip-like sealing attachment17(sealing strip) placed on this recess sealing the edge of the flap8in a manner impermeable to gas (in this situation) against the side frame16insofar as the flap8rests against the groove-like frame recess and presses against the sealing attachment17when, in an air-pressure ratio, the internal air pressure piis greater than or equal to the atmospheric external air pressure pa, which will be explained in more detail later on.

Furthermore, with a low pressure of the fuselage air compared to the ambient air pressure pawhen the internal air pressure piis less than the ambient air pressure pa, the flap8will alternatively clear the opening region6of the submerged air inlet1such that it lets air flow through (by the flap8which is then inclined with respect to the inner region7of the fuselage). It is additionally pointed out that the internal air pressure piis a static cabin pressure and the atmospheric ambient air pressure pais a static external pressure of the (fuselage external air loaded on the aircraft fuselage in the region of the submerged air inlet1). If the flap8is in an open state, part of the external air flow will pass into the opening region6(due to the shape and arrangement of the submerged air inlet1). Reference is also made toFIG. 2which shows a plan view of the valve arrangement according toFIG. 1.

SUMMARY OF THE INVENTION

The object of the invention is therefore to provide a solution for a flow-optimised air intake valve of an aircraft which is arranged in the region of a submerged air inlet, with which the aircraft is fitted to equalise inversely-acting differential air pressures. The air intake valve is to ensure a self-regulating, free passage of air into the inner region of the aircraft fuselage under the influence of the force conditions acting thereon in an air pressure-loading manner, and equally an optimisation, adapted to the aerodynamic flow conditions, of the air flowing into the submerged air inlet is effected during an air pressure equalisation which takes place between the external environment of the aircraft and the interior of the aircraft fuselage.

This object is achieved by an air intake valve which has the features of claim1and/or by a method which has the features of claim27. The further claims contain advantageous developments and embodiments of these measures.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 3 to 5show an embodiment of an air intake valve2according to the invention which is positioned in the region of a submerged air inlet1and is advantageously arranged in an NACA submerged air inlet18, due to vortex (pair) formation. This development of air vortices5, that is to say pairs of air vortices, can be observed particularly in the case of submerged air inlets1which have an NACA shape. In this respect, it will be observed, on the example of the valve arrangement according toFIG. 3 to 5, that the initial air vortex formation is intensified on the cutout edges4of the NACA submerged air inlet1by the (desirable) further supply of ambient air3(outside the aircraft fuselage) into this NACA submerged air inlet18, which air vortex formation will continue on the periphery of the edge(s) of the flap8provided that the flap8(adapted to the NACA opening cross section) is in an open position.

According to the arrangement ofFIG. 3which differs fromFIGS. 1 and 2in particular by the use of an NACA submerged air inlet18and of the NACA-adapted superficial shape of the flap8correlated therewith, the air intake valve2(which is similar in terms of construction) is in the closed state, with the flap8forming a planar surface with the fuselage outer skin15(not shown) of the aircraft. The force resulting from the (non-inversely acting) differential air pressure Δp [where Δp=pi−pa, and pa<pi(cabin air excess pressure)] and the spring force FFadded thereto of a compression spring of the spring hinge19(mentioned in respect ofFIG. 1) which is shown for the first time inFIG. 6, acts on the flap8of this air intake valve2and keeps it closed, the relationship: ΣFpi+FF>ΣFpa→{dot over (m)}cabin=0 essentially describing this situation. Accordingly, no flow of ambient air3(fuselage external air) will develop in the direction of the internal regions of the aircraft from outside the aircraft fuselage via the NACA submerged air inlet18. The air mass throughput {dot over (m)}cabinfrom the fuselage external air to, for example, the aircraft cabin equals zero.

Compared toFIG. 3, the arrangement ofFIG. 4shows a slightly open flap8(slightly inclined flap8). The force resulting from the (inversely acting) differential air pressure Δp [where Δp=pi−pa, and pa>pi(cabin air low pressure)] and the spring force FFadded thereto of the compression spring of the spring hinge19(mentioned in respect ofFIG. 1) acts on the flap8of this air intake valve2and the flap8starts to open. The following relationships: ΣFpi+FF<ΣFpa→{dot over (m)}cabin1≠0 and {dot over (m)}total={dot over (m)}cabint+{dot over (m)}ambientessentially describe this situation, and (ΣFpa=pi×Aflap>ΣFpi=Σpi×Aflap)+FFalso applies. Accordingly, a flow of ambient air3(fuselage external air) will develop in the direction of the internal region7of the aircraft, from outside the aircraft fuselage via the flap8of the air intake valve1the NACA submerged air inlet18, only a partial amount of the ambient air3being branched off into the NACA submerged air inlet18. Air vortices5(so-called edge vortices) form at the edges of the opening cross section of the NACA submerged air inlet18and also suction up the boundary layer of the fuselage external air and, in so doing, help to guide the higher-energy flow outside the boundary layer as an air mass (partial) flow into, for example, the aircraft cabin.

Now to the arrangement ofFIG. 5, which shows the flap8in a much further opened state compared toFIG. 4. The accumulated force resulting from the (inversely acting) differential air pressure Δp [where Δp=pi−pa, and pa>>pi(cabin air low pressure)] and the spring force FFadded thereto of the compression spring of the spring hinge19(mentioned in respect ofFIG. 1) act on the flap8of this air intake valve2and as a result, the flap8opens further.

The following relationships: ΣFpi+FF<<Fpa→{dot over (m)}cabin2>{dot over (m)}cabin1and {dot over (m)}total={dot over (m)}cabint+{dot over (m)}cabin2essentially describe this situation. The greater ΣFpa=Σpa×Aflapbecomes in relation to ΣFpi=Σpi×Aflap)+FF, the more the flap8opens and allows an increasing air flow to enter the aircraft cabin in particular. Accordingly, an increased flow of ambient air7(fuselage external air) develops in the direction of the inner regions of the aircraft from outside the aircraft fuselage via the flap8of the air intake valve1, the NACA submerged air inlet18. Air vortices5(so-called edge vortices) form on the edges4of the opening cross section of the NACA submerged air inlet18and continue (propagate to a certain extent) peripherally along the edges of the flap8, as a result of which the air mass flow which has been guided, for example, into the aircraft cabin will start to increase. In this situation, the plate8acts a vortex- and flow multiplier.

Here, reference is made to the advantageous use of an NACA submerged air inlet18combined with the self-regulating (as a function of the prevailing air pressure conditions) air intake valve2which is adapted in a flow-optimised manner, according to which the air mass throughput {dot over (m)}cabin1, {dot over (m)}cabin2(relating to the figures) will be substantially higher due to the NACA shape with an identical size of the fuselage scoop (located on the outlet side of the NACA submerged air inlet18) and with the same installation space (of the NACA submerged air inlet18), i.e. will mean a power increase of the partial air quantity of ambient air3, guided via the NACA submerged air inlet18. As a result of this increase in power, it is possible to reduce the number of air intake valves1to be originally installed in the aircraft fuselage (or in other intended aerodynamic outer skin regions of the aircraft) and thus to reduce the number of necessary cutouts or opening regions in the fuselage outer skin15.

This also results in a reduction in the weight of the aircraft and consequently a lower fuel consumption.

The air intake valve2is preferably adjusted to a defined air mass throughout {dot over (m)}cabin1, {dot over (m)}cabin2which depends on the current flight conditions and dimensions in order to make efficient use of the advantages mentioned.

Conceivable embodiments are shown in the further figures. Thus,FIG. 6 to 9relate to the installation of a (flow-optimised) air intake valve2, the defined arrangement of which can operate in a self-regulating manner in the region of an NACA submerged air inlet18. In this respect, in its rest position the flap8seals off the opening region6of the NACA submerged air inlet18(shown inFIG. 3 to 5) lying flat with respect to the surface of the fuselage outer skin15of the aircraft such that it is impermeable to air (i.e. it seals in a gas-tight manner). It is impermeable to air because in the situation of an existing cabin excess pressure (pi>pa) or even when there is an equalised pressure relationship (pi=pa), the flap8presses against the sealing attachment17resting on the inner edge of the side frame16.

Furthermore,FIGS. 6 and 9show two spring hinges19which are arranged on the surface region (directed towards the opening region6) of the transverse side10, configured as a planar plate or support element, of the side frame16(according to either of the aforementioned figures) and are attached in a mutual spacing to one another. Each spring hinge19has a first and second hinge portion20,21, the first hinge portion20being attached to the region, directed towards the base of the NACA submerged air inlet18, of the said transverse side10. The second hinge portion21can be mounted such that it can move by an articulated axle with respect to the first hinge portion20(in the direction of the fuselage transverse axis27) and can be moved in a vertical direction of the fuselage longitudinal axis12inclined to the bevel of the base of the NAGA submerged air inlet18.

The surface of the flap8which is attached to the second hinge portion21has a cut part which is adapted to the opening region6of the NACA submerged air inlet18and which completely covers the (positively) shown NACA cutout (in the rest position of the flap8). Furthermore, integrated into the corresponding spring hinge19is a restoring spring, the respective spring end of which is coupled with the two hinge portions20,21. This restoring spring influences the hinge angle excursion of the two hinge portions20,21such that in its relaxed position, the restoring spring does not store any restoring spring tension or exerts a spring force FFif the plate8is in its rest position. Only when the second hinge portion21is deflected into a vertically open position, does the restoring spring tension increase relative to the increase in the spring path. Thus, the maximum possible spring path of the restoring spring restricts the excursion of the second hinge portion21and thus also the permissible hinge angle excursion between the two hinge portions20,21.

The spring force FFwhich is thus provided and has already been mentioned in respect ofFIGS. 3 to 5is stored by the restoring spring as restoring spring force FF, the assistance of which is used when the flap8is returned from its open position into a rest position.

Since the position of the flap8is substantially influenced by the currently prevailing air pressure conditions (or the currently active air pressure forces (ΣFpi, ΣFpa) on the effective surface (Aflap) of the flap8, i.e. the pressure-loading internal air pressure (Σpi) and the ambient air pressure (Σpa) which both act as a function of pressure load on the opening cross section of the NACA submerged air inlet18(the spring force FFis disregarded for once) (cf. in this respect also the observations regardingFIG. 3 to 5), a self-regulating operation of the flap8is allowed, the return of which from the open position is assisted by the restoring force (emanating from the spring force FF) of the restoring spring. For this reason, at least one restoring spring configured as a tension spring is attached, for example, to the individual spring hinge19, for which reason the flap8in its vertically inclined position is returned in self-regulating manner by the spring restoring effect into a position which is inclined with respect to the flap closed position or into a position approaching this, due to a reduced flow of ambient air entering the opening region6, if the internal air pressure (p1) increases and approaches ambient air pressure (pa). Otherwise, this flap8is returned in a self-regulating manner by the spring restoring effect into its rest position also as a result of a declining flow of ambient air entering the opening region6, the decline (reduction) of which decreases until this air flow fails to enter the opening region6if the internal air pressure piachieves an increase which is greater than or equal to the ambient air pressure pa.

To supplement the observations made in respect ofFIG. 6(a plan view of the NACA submerged air inlet region with integrated flap8) and ofFIG. 9(perspective view with the emphasised valve components),FIG. 7shows the sectional line A-A according toFIG. 6(for a side view of the air intake valve2according toFIG. 6in a closed position) andFIG. 7shows the sectional line A-A according toFIG. 6(for a side view of the air intake valve2according toFIG. 6in an open position).

According toFIGS. 6,8and9, in its rest position, with its flap surface closing flat on the outer skin surface, the air intake valve2will completely close a scoop in the NACA shape, located in the fuselage outer skin15. When this valve is opened, ambient air3flows over the downstream transverse edge of the second transverse side11located on the rear edge and which, considered in terms of flow technology, is a dynamic edge, but also flows over the longitudinal sides13,14of the side frame16. The valve opening or the incline of the flap8(with respect to a position corresponding toFIG. 7) is controlled by the force equilibrium consisting of spring force FF, differential pressure Δp and aerodynamic forces ΣFpi, ΣFpa.

FIG. 10is very similar to the plan view according toFIG. 6, since there are no further wall boundaries to be inferred from this illustration. These wall boundaries will not be shown untilFIG. 11.

These wall boundaries22,23,24are attached along the periphery of the framing of the side frame in a perpendicular position on the side edges, directed towards the opening region6of the NACA submerged air inlet18, of the transverse and longitudinal sides10,11,13,14, i.e. below the side frame16. The region of the NACA submerged air inlet18adjoining the front portion9remains excluded from this. A first wall boundary22is arranged according to the course of the fuselage transverse axis27, while two further similar wall boundaries23,24extend in the direction of the fuselage longitudinal axis12. These wall boundaries22,23,24have the shape of a rectangular side wall, the respective broadside edges of which are attached in this region, insofar as they are opposite one another and contact one another. Accordingly, the flap8is either arranged to be freely movable inside the opening region enclosed by the wall boundaries as a function of the force conditions acting thereon in an air pressure-loading manner, or the flap8is positioned during its rest position inside this opening region which is enclosed by the side frame16. In this respect, the edge of the flap8is preferably resting on the sealing attachment17which is strip-shaped and is attached to the longitudinal and transverse sides (10,11,13,14) of the side frame16. Accordingly, the scoop in the NACA shape located in the aircraft skin, is delimited by the wall boundaries22,23,24. The ambient air3flows in over the dynamic edge of the valve.

FIG. 12shows a complete NACA submerged air inlet18with an installed air intake valve2. The construction thereof is similar to that shown inFIG. 11. The differences compared toFIG. 11are confined to the following exchange of elements:a) replacement of the second wall boundary23by a trapezoidal side plate28;b) replacement of the third wall boundary24by a trapezoidal side plate29;c) removal of the first wall boundary22without replacement; andd) peripheral attachment of a rectangular base plate38to the free side edges of the transverse and longitudinal sides10,11,13,14of the side frame boundary.

The two parallel sides32,33(base lines) of the two side plates28,29have different lengths and are arranged standing perpendicularly on a first non-parallel side34at the beginning and end of said first non-parallel side34. The second non-parallel side35of these side plates28,29is connected to the remaining free ends of the two parallel sides32. Insofar as the description is based on the example of the trapezoidal plate shape of the side plates28,29, it is also pointed out that accordingly a respective first side plate28is attached by its first non-parallel side34to the free side edge of the second longitudinal side14. Applied accordingly, a second side plate29is attached by its first non-parallel side34to the free side edge of the first longitudinal side13.

Attached to a first parallel side32of the two side plates28,29which is shorter compared to the second parallel side33, and to the remaining front edge transverse side edge36,37of the two longitudinal sides13,14of the side frame16which are unattached (for the time being) due to the lacking installation, according to the example, of the first transverse side10of the side frame16and the edge path of which corresponds to that of a first wide edge39of the base plate38, and likewise attached to this first wide edge39(of the base plate38) is a so-called “fixed NACA inlet point”41which has a pyramid-like shape, by the respective side edges of the present pyramid side faces which enclose a held-open rectangular cross section of the pyramid base. The region, arranged next to the base plate38, of a pyramid side face45is preferably also held open, through which the ambient air3(particularly only in parts) is guided over the NACA inlet point41and into the held-open rectangular cross section of the pyramid base (respectively the same size rectangular cross section the mentioned opening31) and is further conveyed into the transit air volume region42contained by the side plates28,29and the base plate38which in the direction of the fuselage internal region7(not shown), the opening30which at the end of the two second parallel sides33(having an extended length), the remaining free ends of which is stabilised by a third transverse side43on the rear edge connecting these (ends) leaves the construction formed (initially without a flap) from the side plates28,29and the base plate38.

By means of the NACA submerged air inlet18according toFIG. 12and the flap8which is still to be completed, the air intake valve2is optimised in terms of flow and can operate in a self-regulating manner. This flap8is also attached to two spring hinges19which are positioned on the edge and close to the held-open rectangular cross section of the pyramid base on a closed pyramid side face44which is located opposite the open cross section of the pyramid side face45. If the flap8is in its rest position with cabin excess air pressure or equalised air pressure conditions, its (unattached) flap edges are parallel to the second non-parallel sides35and the third transverse side43. If low pressure prevails in the cabin, the flap8moves in the direction of the mentioned base plate35. Otherwise, the flap8rests with its unattached flap edge (opposite the flap edge attached to the hinge) on the base plate35. This latter measure influences in a self-regulating manner an initially partial blocking of the passage direction of the flow of ambient air guided through this NACA submerged air inlet18.

Finally, it is mentioned that the NACA shape is preferably integrated plastically into the surface of the aircraft. The flap8, which operates as a function of differential pressure, of the air intake valve2(configured as a negative relief valve) is only one part of this presented NACA submerged air inlet18with a fixed NACA inlet point.

According toFIGS. 13 and 14, an NACA submerged air inlet18fitted with the air intake valve2is shown according to the example ofFIGS. 7 and 8and is supplemented by an ancillary flap26. According thereto, this ancillary flap26is shown in an open position according toFIG. 13and in a closed position according toFIG. 14.

The ancillary flap26is attached to the second transverse side11(looking atFIG. 6which correlates withFIGS. 7 and 8). The flap edge, (likewise) mounted in a rotationally movable manner, of the ancillary flap26is arranged on the longitudinal side region, directed towards the opening region6, of the transverse side11, the surface of the ancillary flap26being configured pivotally in the direction of the outer region of the aircraft fuselage outside the opening region6. By means of the ancillary flap26, it is possible for additional ambient air3or fuselage external air to be guided into the opening region6, assuming that the ancillary flap26is in its pivoted-out position.

If the flap8is returned into its rest position, the ancillary flap26is pivoted back into a horizontal flap position. The cross section thereof accordingly becomes a component of the flap cross section which effectively seals the opening region6in an airtight manner. For this reason, the recesses25in the flap8(used in this situation as the main flap) are adapted to the flap cross section of the ancillary flap26in the non-pivoted position. Furthermore, the surface of the ancillary flap26can be covered with a sealing material coating, otherwise the aforementioned sealing attachment17is positioned such that in its rest position, the so-called main flap provides an effective seal against external air3to prevent it from penetrating inside the opening region6.

There is therefore a small ancillary flap26which is additionally fitted to the dynamic edge of this air intake valve2and which, when the (so-called) main flap is opened, pivots outwards (i.e. in the direction of the external environment of the aircraft fuselage) and guides additional quantities of external air3into the aircraft fuselage (in the region of the NACA submerged air inlet18).

FIG. 17shows a schematic flow chart of an embodiment of a method according to the invention for the production of an air intake valve2for an aircraft.

In the following, the method according to the invention will be explained on the basis of the block diagram inFIG. 17with reference toFIGS. 3 to 5. The method of the invention according toFIG. 17has the following steps S1 to S3:

An opening region6is provided for letting ambient air3through into a fuselage inner region7of the aircraft.

A flap8is arranged over the opening region6for opening and closing said opening region6.

The shape of the opening region6and of the class8is configured in each case such that it is capable of forming air vortices on edges4of the opening region6when ambient air3flows through the air intake valve2.

Although the present invention has been described on the basis of preferred embodiments, it is not restricted thereto, but can be modified in many different ways.

In the following preferred embodiments of an air intake valve are given:

Embodiment 1: Air intake valve for an aircraft, comprising:

an opening region for letting ambient air through into a fuselage inner region of the aircraft,

a flap for opening and closing the opening region,

characterised in that the opening region and the flap each have a shape which is capable of forming air vortices on edges of the opening region when ambient air flows through the air intake valve.

Embodiment 2: Air intake valve according to embodiment 1, characterised in that the opening region and the flap each have an NACA shape which is capable of forming self-enlarging air vortices on the edges of the opening region when ambient air flows through the air intake valve.

Embodiment 3: Air intake valve according to at least one of the preceding embodiments, characterised in that the air intake valve is positioned in the region of an NACA submerged air inlet with which an air pressure equalisation is provided when there is an inversely-acting differential air pressure between a pressure-ventilated inner region of an aircraft fuselage which is subjected to an internal air pressure, and an NACA submerged air inlet region which is submerged lengthwise in the downstream direction of the aircraft fuselage and is arranged inside a fuselage outer skin covering the aircraft fuselage and is connected in terms of air flow to the fuselage inner region, and an atmospheric ambient air pressure bears down on an opening region of the NACA submerged air inlet on the inlet side of the NACA submerged air inlet region, which opening region is restricted by a side frame and which is covered by the flap in the rest position, the flap closing the opening region, if the ambient air pressure is greater than the internal air pressure.

Embodiment 4: Air intake valve according to at least one of the preceding embodiments, characterised in that the flap is attached to a first transverse side of the side frame which is disposed transversely to the fuselage longitudinal axis upstream of the aircraft fuselage, which flap is mounted rotatably in the region of the attachment site.

Embodiment 5: Air intake valve according to embodiment 4, characterised in that the attachment site can be moved, as a function of the force conditions acting thereon in a manner applying air pressure, relative to the opening region connected to the fuselage inner region at the outlet of the NACA submerged air inlet region.

Embodiment 6: Air intake valve according to embodiment 5, characterised in that a flow-optimised and self-regulating air intake valve function can be implemented by means of the opening region while utilising the air vortices, arising on the ramp-side cutout edges of the NACA submerged air inlet region, of the external air which partially flows into the NACA submerged air inlet region, the air vortices continuing on the edge of the flap.

Embodiment 7: Air intake valve according to at least one of the preceding embodiments, characterised in that the air intake valve is configured as an independent air intake valve.

Embodiment 8: Air intake valve according to at least one of the preceding embodiments, characterised in that the opening region of the NACA submerged air inlet is closed in a gas-tight manner by the flap which covers it in the rest position, when the internal air pressure is greater than or equal to the ambient air pressure, otherwise when there is a fuselage low air pressure compared to the ambient air pressure, the opening region of the submerged air inlet is unblocked to allow the throughflow of air, by the flap which is inclined with respect to the fuselage inner region, when the internal air pressure is less than the ambient air pressure, and in this situation, an air pressure equalisation takes place with respect to the fuselage inner region.

Embodiment 9: Air intake valve according to at least one of the preceding embodiments, characterised in that the side frame comprises in addition to the first transverse side a second transverse side and longitudinal sides connected to the ends of the two transverse sides, and a second transverse side which is disposed transversely to the fuselage longitudinal axis and is located downstream of the aircraft fuselage, is arranged opposite the first transverse side and is disposed adjoining a rear edge portion of the NACA submerged air inlet, furthermore a first longitudinal side and a second longitudinal side are arranged adjoining the edge portion of the NACA submerged air inlet, the side edge region thereof being mechanically connected, disposed on the left and on the right, to that of the respective transverse side, the course of the two longitudinal sides corresponding to that of the fuselage longitudinal axis, furthermore the side frame formed by the transverse and longitudinal sides is mechanically attached to the fuselage outer skin sideways of the opening region of the submerged air inlet, the transverse and longitudinal sides which are configured as planar plate or support elements being arranged outside the opening region of the submerged air inlet or slightly covering it along the edges, and the contour of which being adapted to the contour path of the fuselage outer skin, and which include the cross section of the opening region of the submerged air inlet.

Embodiment 10: Air intake valve according to at least one of the preceding embodiments, characterised in that the resting flap which, in this state, is arranged in a position covering the opening region of the NACA submerged air inlet is positioned pressing against a strip-like sealing attachment which is directed towards the NACA submerged air inlet opening and is attached resting on the side portion, directed towards the fuselage inner region, of the transverse and longitudinal sides and is likewise positioned in an absolutely sealing manner against an external air flow surrounding the fuselage, the flap which is located in the rest position and closes a lengthwise submerged duct inlet of the NACA submerged air inlet being arranged in planar manner with respect to the surface of the fuselage outer skin.

Embodiment 11: Air intake valve according to at least one of the preceding embodiments, characterised in that the transverse and longitudinal sides are replaced by side edges of the fuselage outer skin which are attached sideways of the submerged air inlet opening.

Embodiment 12: Air intake valve according to at least one of the preceding embodiments, characterised in that at least one spring hinge is attached to the first transverse side, a first hinge portion being attached to the first transverse side and a second hinge portion mounted rotatably with respect to the first hinge portion can be moved inclined in a vertical direction to the bevel of the base of the NACA submerged air inlet, to the edge of which the flap is attached.

Embodiment 13: Air intake valve according to at least one of the preceding embodiments, characterised in that a plurality of spring hinges which are arranged transversely to the fuselage longitudinal axis and are in a mutual spacing are attached to the first transverse side, the attachment of the edge of the flap which runs transversely to the fuselage longitudinal axis to two spring hinges sufficing with a relatively small width.

Embodiment 14: Air intake valve according to at least one of the preceding embodiments, characterised in that a hinge angle excursion which is included by the second hinge portion in a vertically open hinge position compared to the first hinge portion is restricted by the spring path of at least one restoring spring, the respective spring end of which is attached to the individual hinge portion.

Embodiment 15: Air intake valve according to at least one of the preceding embodiments, characterised in that attached to the individual spring hinge is at least one restoring spring configured as a tension spring, for which reason the flap in a vertically inclined position is returned in a self-regulating manner by the spring restoring force into a position which is inclined with respect to the flap closed position or is approaching this as a result of a reduced flow of ambient air entering the opening region if the internal air pressure increases and approaches the ambient air pressure, the flap otherwise being returned in a self-regulating manner by the spring restoring effect into its rest position as the result of a further decreasing flow of ambient air which enters the opening region, the quantitative flow reduction of which decreasing until this air flow does not appear in the opening region if the internal air pressure achieves an increase which is greater than or equal to the ambient air pressure.

Embodiment 16: Air intake valve according to embodiment 9, characterised in that attached to the edge of the two longitudinal sides of the side frame is a respective wall boundary which is directed towards the bevel of the base of the NACA submerged air inlet and is attached perpendicularly to the side edges, directed towards the opening region of the NACA submerged air inlet, of the longitudinal sides.

Embodiment 17: Air intake valve according to embodiment 16, characterised in that a first wall boundary is attached to the edge of the first longitudinal side and a second wall boundary is attached to the edge of the second longitudinal side which are both arranged under the side frame.

Embodiment 18: Air intake valve according to at least one of the preceding embodiments, characterised in that the flapa) is arranged such that it can move freely inside the part of the opening region enclosed by the wall boundaries under the side frame, orb) is located, while in its rest position, inside the part of the opening region enclosed by the side frame, the edge of the flap resting on a sealing attachment which is strip-shaped and is attached to the longitudinal and transverse sides of the side frame,
as a function of the force conditions acting to load air pressure on the flap surface.

Embodiment 19: Air intake valve according to at least one of the preceding embodiments, characterised in that strip-shaped recesses adapted to the shape of the sealing attachment are removed from the edge of the flap, for which reason the flap is arranged such that it terminates in planar manner with the fuselage outer skin in its rest position.

Embodiment 20: Air intake valve according to at least one of the preceding embodiments, characterised in that the first and second wall boundaries are each configured as a side wall with a rectangular wall surface, a web preferably being attached to the perpendicularly spaced free ends of the respective broadside edges of the wall boundaries which face the opening at the outlet of the NACA submerged inlet region and are arranged downstream of the NACA submerged inlet region, the web and the broadside edges enclosing an open region delimited by the second transverse side.

Embodiment 21: Air intake valve according to embodiment 20, characterised in that the side walls standing perpendicularly in the direction of the fuselage longitudinal axis are used as air guiding wall elements.

Embodiment 22: Air intake valve according to at least one of the preceding embodiments, characterised in that the sealing attachment is a sealing strip, the contact region of which directed towards the incline of the base of the NACA submerged inlet region is configured to be firmly adhesive, which is attached, preferably adhesively bonded to the transverse and longitudinal sides of the side frame on their contact surface directed towards the opening region.

Embodiment 23: Air intake valve according to at least one of the preceding embodiments, characterised in that the transverse and longitudinal sides of the side frame enclose an NACA-geometric cross-sectional shape of the opening region corresponding to the duct inlet surface of the NACA submerged inlet region, and the planar surface of the flap is adapted with the sides conforming to this NACA geometric shape, based on which self-enlarging air vortices or pairs of air vortices, so-called edge vortices or pairs of edge vortices, form on the side edges of the transverse and longitudinal sides which face the NACA geometric cross section of the opening region, while partial quantities of ambient air passing downstream of the NACA submerged inlet region flow in with an inclined flap position during the air pressure equalisation which is taking place, if the opening region is cleared by the inclined flap position, an increase in the air vortices or in the pairs of air vortices occurring by a further supply of ambient air which flows in over the side edges, thereby producing an increased air throughput of the inflowing ambient air through the NACA submerged inlet.

Embodiment 24: Air intake valve according to at least one of the preceding embodiments, characterised in that attached to the second transverse side is an ancillary flap, the rotatably mounted flap edge of which is arranged on the longitudinal side region, directed towards the opening region, of the transverse side, it being possible for the surface of the ancillary flap to be pivoted in the direction of the fuselage outer region as far as outside the opening region, by which, in its pivoted-out position, ambient air can be additionally guided into the opening region.

Embodiment 25: Air intake valve according to at least one of the preceding embodiments, characterised in that the recesses in the flap are adapted to the cross section of the ancillary flap in its unpivoted position.

Embodiment 26: Air intake valve according to at least one of the preceding embodiments, characterised in that the first transverse side is positioned next to a peripherally adjacent front edge portion of the NACA submerged inlet which is located at the start of the developing bevel of the base, submerged with respect to the fuselage inner region, of the NACA submerged inlet.

Embodiment 27: Method for the production of an air intake valve for an aircraft, with the following steps:

provision of an opening region for letting ambient air through into a fuselage inner region of the aircraft,

arrangement of a flap above the opening region for opening and closing the opening region,

characterised by the formation of the shape of the opening region and of the flap in each case such that the flap is capable of forming air vortices on edges of the opening region when ambient air flows through the air intake valve.

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