Patent Description:
For increasing the lift coefficient of a wing of a commercial aircraft, high lift systems are known. These may include trailing edge flaps, and leading-edge devices. During takeoff and landing, they are usually activated, i.e. moved from a retracted into an extended position. For this purpose, drive mechanisms are used, which are coupled with respective flow bodies and drives through appropriate joints, gears and other devices.

Leading-edge slats usually comprise a front skin, a back skin and mechanical interfaces for coupling with a slat track. The leading-edge slat is designed to be arranged directly in front of a fixed leading-edge of a wing, wherein a drive mechanism protrudes out of the fixed leading edge towards the slat. Common embodiments comprise a slat track that is guided by track support rollers arranged in the fixed leading edge, wherein the slat track protrudes through a front spar of the fixed leading edge. For many load cases, a resultant air load vector is pointing more forward and therefore has an offset to interface points on the leading-edge slat. This offset result in an additional moment introduced into the fixed leading-edge structure.

<CIT> describes an aircraft slat deployment mechanism. The mechanism comprises a first curved track coupled to the slat at a first pivot point, a main bearing system arranged to guide the first curved track along a curved path, a second track coupled to the slat at a second pivot point which is offset from the first, an internal bearing between the first and second tracks, and a drive system arranged to drive the first curved track along the curved path guided by the main bearings, and the second track along the curved first track guided by the internal bearings. Ideally the second track is partially nested within a channel in the first curved track. Ideally the second track is also curved. Preferably both tracks comprise toothed racks, which are preferably driven from the same driveshaft, having pinions of different radius. The differential movement of the telescopic tracks results in rotation of the slat.

<CIT> describes a wing for an aircraft. The wing comprises a main wing, a slat, and a connection assembly movable connecting the slat to the main wing. The connection assembly comprises an elongate slat track. The front end of the slat track is mounted to the slat, wherein the rear end and the intermediate portion of the slat track are mounted to the main wing by a roller bearing comprising a guide rail mounted to the main wing and a first roller unit mounted to the rear end of the slat track and engaging the guide rail. The roller bearing comprises a second roller unit mounted to the main wing and engaging an engagement surface at the intermediate portion of the slat track. The slat track has a profile comprising an upper flange portion, a lower flange portion and at least one web portion connecting upper and lower flange portions. The second roller unit is arranged in a recess between upper and lower flange portions and engages the engagement surface provided at the upper flange portion and/or at the lower flange portion.

<CIT> describes a deployment mechanism for moving an aircraft wing leading edge slat or trailing edge flap relative to a main airfoil. The mechanism includes an I-section support beam extending between the main airfoil and the slat or flap. The support beam is driven into and out of the main airfoil by a rack and pinion mechanism, the rack being disposed along a lower boom of the beam and the beam being supported for rolling contact with the main airfoil by upper and lower straddle rollers positioned between wing leading edge ribs. Roller tracks extend along upper and lower booms of the beam with at least one roller track co-extending with the rack adjacent thereto along the beam.

<CIT> describes an improvement to close an opening formed in the leading edge of an airfoil when a slat is moved to its deployed position. The track which deploys the slat has a downward component of motion which leaves an opening in the wing leading edge that can cause premature stall if the opening is not closed. To close this opening, there is a door which is mounted about an axis of rotation that is positioned in a vertical plane generally parallel to the movement of the track. Further, the axis of rotation is slanted so that the door moves upwardly, rearwardly and laterally to its retracted position so as to permit the track to be retracted, and when the track is extended, a spring moves the door into its deployed position to close the opening.

<CIT> shows a slat arranged on a wing, and a connection assembly for movably connecting the slat to the main wing, such that the slat is movable in a predefined motion between a retracted position and at least one extended position. A front spar of a fixed leading edge of the wing, wherein an elongate guide of the connection assembly is completely arranged in an interior space between the front spar and the slat.

It is an object of the invention to propose an alternate wing leading-edge device, which improves its coupling to a drive mechanism and that reduces penetrations through structures of a fixed leading edge.

This object is met by the wing leading-edge device having the features of independent claim <NUM>. Advantageous embodiments and further improvements may be gathered from the subclaims and the following description.

According to the invention, a wing leading-edge device is proposed, comprising a slat body having a front side with a forward skin and a back side with a rearward skin, and at least a drive arrangement having at least one lug and a slat track, wherein the back side extends between an upper spanwise edge of the forward skin and a lower spanwise edge of the forward skin, wherein the back side is defined by a continuously curved profile contour for receiving a fixed leading edge of a wing, wherein the at least one lug is at least partially arranged between the back side and the front side, and wherein the slat track is coupled with the at least one lug.

The slat body may comprise an elongate shape that extends along a spanwise direction and comprises a certain profile contour. The profile contour is mainly determined by the desired aerodynamic characteristics. It is preferred that the slat is sufficiently stiff to serve for the intended purpose. It may be preferred that the slat body comprises stiffening elements, such as ribs and/or stringers to be arranged on an inner side of the forward skin. Further, some sections of the slat body may comprise load introduction arrangements, which are mechanically adapted for a reliable load transfer between the slat body and the drive mechanism.

The forward skin is designed according to the aerodynamic requirements. It comprises an upper edge and a lower edge, which both run in a spanwise direction.

The forward skin substantially extends between these edges in a concave shape. At a rearward position, i.e. behind the inner side of the forward skin, the back side of the slat body is created. The back side is characterized by an at least theoretical, surface-like delimitation that is adapted to the outer shape of a fixed leading edge, to which the wing leading-edge device will be attached. The back side of the slat body is intended to fit onto the fixed leading edge in a very close manner in a retracted state. In some embodiments, the whole back side comprises a back skin, which follows this theoretical, surface-like shape. In some embodiments, such a back skin may comprise cutouts or recesses. In still further embodiments, the back skin may comprise a cutback along its whole spanwise extension.

Coupling the slat track with the at least one lug does not necessarily mean a direct connection. It may also be possible to use an additional link, a plate or any other component that is arranged between the slat track and the at least one lug to couple the at least one lug and the slat track. In the following, the term "coupling" is thus to be understood as directly or indirectly connected in general.

A gist of the invention lies in providing the at least one lug at least partially between the back side and the front side, i.e. between the back side and the front skin. Thus, the required joints and coupling devices are substantially completely inside the slat body. This allows to shift resulting reaction forces to an air load vector into a forward direction to form a clearly reduced offset mentioned above. As a consequence, the additional moment acting into the fixed leading edge is reduced, too. The slat track does not necessarily need to be supported in a region behind a front spar of the fixed leading edge. Penetrations through a front spar are thus eliminated, which in turn reduces the impact on the design of the fixed leading edge. Overall, the design of the fixed leading edge is thereby greatly improved.

It is further to be understood that the wing leading-edge device according to the invention preferably comprises two drive arrangements mentioned above for a single slat body to provide a desired motion of the complete slat body in a chordwise direction.

In an advantageous embodiment, the forward skin and the back side enclose a hollow space, wherein the at least one lug is at least partially arranged inside the hollow space. Thus, the at least one lug and the associated connection to the drive mechanism is provided in a further forward position, which leads to a further improved coupling to the leading-edge device and a further improved mechanical design regarding the expected air load vector impact.

In another advantageous embodiment, the hollow space is enclosed by the forward skin and the rearward skin, wherein the at least one lug is completely arranged inside the hollow space. Consequently, the resulting position of the connections to the drive mechanism is as forward as possible.

Further, according to the invention, the at least one drive arrangement comprises a first lug, a second lug and a support link, wherein the support link is swivelably coupled with the second lug and the slat track. The support link thus stabilizes a rotational position of the slat body. The arrangement of a first lug and a second lug, which are at a distance to each other, allows the transfer of a substantial moment from the slat body into the slat track. For minimizing the required space for such an arrangement, the support link may be as small as possible.

The slat track may be swivelably coupled with the first lug. The first lug may be arranged forward of the second lug and the slat track may consequently be arranged as forward as possible.

In a very advantageous embodiment, the at least one lug is arranged on a stiffening rib of the slat body. Thus, two functions are combined, i.e. a stiffening function through the rib itself and a load introduction function through the at least one lug integrated into the rib.

Still further, the stiffening rib may partially extend through the rearward skin. In this embodiment, a balancing between compactness, available space, maintenance and bearing design is made. While it would be possible to arrange the rib and the first lug completely inside the space defined by the forward skin and the backside, a slight protrusion of the rib through the rearward skin may be tolerated.

Advantageously, the slat body may comprise at least one cut-out through the rearward skin for feeding the slat track into the slat body. The cutout may be as small as possible to allow feeding the slat track into the slat body, but for allowing a sufficient clearance under consideration of vibrations, temperature deviations, loaded and unloaded states etc. Also, the cutout may be designed for meeting installation, assembly and disassembly requirements.

When a cutout is used, it may be beneficial if the cutout is arranged at a distance to at least one of the upper edge and the lower edge. The cutout may then only extend on an inner section of the rearward skin between the edges and may, if required, reach one of the edges at a maximum.

In a further advantageous embodiment, the slat body may comprise a cutback of the rearward skin that extends substantially along the whole extension of the slat body in a spanwise direction, wherein the at least one lug is arranged in the cutback. Such a design may lead to a reduced weight as well as a simplified installation, assembly and disassembly.

Further, according to the invention, the slat track comprises a curved track section and a forward leg, wherein the forward leg is fixedly arranged at an angle to a tangential line of the curved track section on a connection point between the track section and the forward leg, and wherein the support link is swivelably connected to the forward leg.

The invention further relates to a wing having a fixed leading edge and a wing leading-edge device according to the above description, wherein the at least one drive arrangement is coupled with the fixed leading edge, such that the slat track is movably supported on the fixed leading edge in a way that the slat is movable between a retracted position, in which the rearward skin is directly forward of a front skin of the fixed leading edge, and extended positions further forward the fixed leading edge.

Advantageously, the fixed leading edge comprises a front spar, wherein the slat track is supported by a plurality of track support rollers, and wherein the track support rollers are arranged between the front spar and the front skin of the fixed leading edge. The rollers may be rotatably arranged on stiffening ribs placed in the fixed leading edge. Bearings for the rollers may thus be arranged on a part of the stiffening ribs that is arranged between the front skin of the fixed leading edge.

Still further, the drive arrangement may be designed such that a vector of an air load on the slat body extends into a region between the first lug and the second lug at least in a retracted position of the slat. The vector of the air load may also extend into the region between the first lug and the second lug in an extended position. The extended position may be a fully extended position or less.

Other characteristics, advantages and potential applications of the present invention result from the following description of the exemplary embodiments illustrated in the figures.

Furthermore, identical or similar objects are identified by the same reference symbols in the figures.

<FIG> shows a first embodiment of a wing leading-edge device <NUM>, which comprises a slat body <NUM> having a front side <NUM> with a forward skin <NUM> and a back side <NUM> with a rearward skin <NUM>. A drive arrangement <NUM> is coupled with the slat body <NUM> and comprises a slat track <NUM> and a first lug <NUM>. In addition, a second lug <NUM> is arranged on the slat body <NUM> and is coupled with a support link <NUM>, which in turn is swivelably coupled with the slat track <NUM> on a connecting joint <NUM>. The forward skin <NUM> comprises an upper spanwise edge <NUM> and a lower spanwise edge <NUM>. The forward skin <NUM> extends between these two edges <NUM> and <NUM> with a convex shape bulging out in a forward direction. The back side <NUM>, which extends between the edges <NUM> and <NUM> and a distance from the forward skin <NUM>, constitutes a delimitation indicated with the rearward skin <NUM> and a dashed line <NUM> that extends up to the lower edge <NUM>. The rearward skin <NUM> comprises an upper rearward skin edge <NUM> and a lower rearward skin edge <NUM>. Both rearward skin edges <NUM> and <NUM> are attached to the front skin <NUM>. Due to the design of the back side <NUM> it allows to move the slat body <NUM> closely to a fixed leading edge <NUM> of the wing, to which the device <NUM> is attached.

In this exemplary embodiment, the forward skin <NUM> comprises a cut-out <NUM>, which is at a distance both to the upper edge <NUM> and the lower edge <NUM>. The cut-out <NUM> allows to lead the slat track <NUM> into a hollow space <NUM> of the slat body <NUM>.

Still further, in this exemplary embodiment, the first lug <NUM> and the second lug <NUM> are arranged on a rib <NUM> inside the slat body <NUM>. The rib <NUM> may be realized in the form of a stiffening rib, which is provided for supporting the outer geometry of the slat body <NUM> at least under a design air load. By arranging the cut-out <NUM> into the rearward skin <NUM>, a back side of the rib <NUM> is easily accessible for coupling with the slat track <NUM> and the support link <NUM>. Resultantly, in comparison with common leading-edge devices, the slat track <NUM>, the support link <NUM> as well as the lugs <NUM> and <NUM> are placed far forward, such that a drive mechanism <NUM> is almost at a forwardmost position. This improves the transfer of air loads into the drive mechanism <NUM> and reduces a moment to be compensated at an outer end of the slat track <NUM>. Still further, rollers for supporting the slat track <NUM> (see <FIG>) can be clearly moved into a forward direction to be placed in front of a front spar of the fixed leading edge <NUM> (see <FIG>). In this exemplary embodiment, the slat track <NUM> comprises a curved track section <NUM> and a forward leg <NUM>, between which a connection point <NUM> is positioned. The forward leg <NUM> is arranged at an angle α to a tangential line <NUM> of the curved track section <NUM> on the connection point <NUM>. The support link <NUM> is swivelably connected to the forward leg <NUM>.

<FIG> shows resulting forces inside the leading-edge device <NUM> depending on the air load that acts onto the slat body <NUM>. Two slightly different examples are shown, which are numbered with I and II. Load case I stands for an air load vector <NUM>, which has a direction that extends directly through the first lug <NUM>. In the other load case II, the air load vector <NUM> has a slight offset in comparison to load case I. Here, the vector extends through a position between the first lug <NUM> and the connecting joint <NUM>. In the first case I, substantially only the first lug <NUM> needs to compensate the air load by a respective reaction force <NUM> and may thus be substantially the inverse force of the air load. However, in the second case II, both the first lug <NUM> and the connecting joint <NUM> need to compensate the air load <NUM> through individual reaction forces 43a and 43b. However, in common leading-edge devices, the air load vector <NUM> is offset in a forward direction, such that the reaction forces 43a and 43b are much greater.

In <FIG> a slightly modified slat body <NUM> in a wing leading-edge device <NUM> is shown, which comprises a complete cutback <NUM> that extends substantially along the whole spanwise extension of the slat body <NUM>. Here, ribs <NUM> may stick out into the cutback <NUM> and the first lug <NUM> and the second lug <NUM> are easily accessible between the forward skin <NUM> and the backside <NUM>. This exemplary embodiment has an advantageously low weight and still allows the slat body <NUM> to be positioned close to the fixed leading edge <NUM>.

<FIG> illustrates possible rollers or roller guides <NUM> that support the slat track <NUM>. The roller guides <NUM> are rotatably supported and are distributed in the fixed leading edge <NUM> to provide a single motion path for the slat track <NUM>. Thus, the slat track <NUM> may only move along the single motion path that depends the shape of the slat track <NUM> and the positions of the roller guides <NUM>. All loads that are introduced into the drive mechanism <NUM> can be transferred into the fixed leading edge <NUM> through the roller guides <NUM>.

Using common design philosophies, the fixed leading edge <NUM> comprises a stiffening structure, which may include several spars. A front spar <NUM> is arranged at a forward position in a distance to the actual leading edge. By shifting the drive mechanism <NUM> and thus the roller guides <NUM> far forward, compared to common leading-edge devices, the front spar <NUM> does not need to be penetrated by the slat track <NUM>. Thus, the structural stability of the fixed leading edge <NUM> is not influenced by any recess or cut-out required for the movability of the slat track <NUM>.

Lastly, <FIG> shows an aircraft <NUM> having wings <NUM>, to which wing leading-edge devices <NUM> are arranged.

Claim 1:
A wing leading-edge device (<NUM>, <NUM>), comprising a slat body (<NUM>, <NUM>) having a front side (<NUM>) with a forward skin (<NUM>) and a back side (<NUM>) with a rearward skin (<NUM>); and
and at least a drive arrangement (<NUM>) having at least one lug (<NUM>, <NUM>) and a slat track (<NUM>);
wherein the back side (<NUM>) extends between an upper spanwise edge (<NUM>) of the forward skin (<NUM>) and a lower spanwise edge (<NUM>) of the forward skin (<NUM>);
wherein the back side (<NUM>) is defined by a continuously curved profile contour for receiving a fixed leading edge (<NUM>) of a wing (<NUM>);
wherein the at least one lug (<NUM>, <NUM>) is at least partially arranged between the back side (<NUM>) and the front side (<NUM>);
wherein the slat track (<NUM>) is coupled with the at least one lug (<NUM>, <NUM>);
wherein the at least one lug (<NUM>, <NUM>) comprises a first lug (<NUM>) and a second lug (<NUM>);
wherein the at least one drive arrangement (<NUM>) comprises the first lug (<NUM>), the second lug (<NUM>) and a support link (<NUM>);
wherein the slat track (<NUM>) comprises a curved track section (<NUM>) and a forward leg (<NUM>);
wherein the forward leg (<NUM>) is fixedly arranged at an angle (α) to a tangential line (<NUM>) of the curved track section (<NUM>) on a connection point (<NUM>) between the curved track section (<NUM>) and the forward leg (<NUM>);
wherein the support link (<NUM>) is swivelably coupled with the second lug (<NUM>) and a connecting joint (<NUM>);
wherein the connecting joint (<NUM>) is arranged on the forward leg (<NUM>) of the slat track (<NUM>); and
wherein the second lug (<NUM>) is arranged on the slat body (<NUM>, <NUM>).