Abstract:
A high-lift trailing edge flap system for an aircraft wing unit is provided. In high-lift trailing edge flap system, the backward movement and the inclination of the trailing edge flap in the extended position are dissociated in order to allow for the incorporation of the actuating mechanism into the wing in the stowed position.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to French Patent Application No. 13 59393 filed Sep. 30, 2013, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The technical field relates to a high-lift flap system for the rear portion, in the vicinity of the trailing edge, of an aircraft wing. 
       BACKGROUND 
       [0003]    It is known that in order to fly at low speed in complete safety, for example during take-off and landing, some aircraft, in particular commercial civil airplanes, have high-lift systems for altering their wing unit intended for cruising at high speed. The aim of these high-lift systems is to momentarily increase the surface area and camber of the wing profile of aircraft, also ensuring greater lift. 
         [0004]    The high-lift systems used are basically leading edge slats, arranged in the front portion of a wing, and trailing edge flaps, fitted in the rear portion of said wing. These slats and flaps are movable under the action of an actuating mechanism allowing them to assume either a position in which they are stowed into the wing, or at least one extended position, which is set back and inclined relative to said wing. 
         [0005]    As a general rule, the rotation that a leading edge slat undergoes between its stowed position and its extended position is very slight, meaning that the corresponding actuating mechanism can be simple and is easily fully stowable inside the wing in the stowed position. 
         [0006]    By contrast, the rotation and the backwards movement that a trailing edge flap has to undergo between its stowed position and its extended position are considerable, resulting in a complex, heavy and voluminous actuating mechanism. These drawbacks are exacerbated by the fact that the actuating mechanisms of all the trailing edge flaps of a wing are generally driven, in a centralised manner, from a single drive shaft. In addition, in these known high-lift systems, a predetermined rotation of the trailing edge flap corresponds to an extended position. 
         [0007]    On account of their large volume, these actuating mechanisms of the trailing edge flaps cannot be housed inside the wings and are arranged for the most part outside said wings, projecting from the lower surface of said wings, as shown in U.S. Pat. No. 4,471,928 for example. To limit the aerodynamic disturbances caused by these external actuating mechanisms, each mechanism is contained in a profiled fairing suspended below the lower surface of the corresponding wing. Despite this precautionary measure, the drag resulting from the presence of these profiled fairings remains significant, and this may impair aircraft performance. Furthermore, since the rotation of the trailing edge flap is linked to its extension, optimum aerodynamic effect of this flap is impossible. 
         [0008]    It will be noted that U.S. Pat. No. 3,655,149 and EP 0 411 680 disclose trailing edge flap systems, housed in part in the wing bearing said flap and in part in said flap. However, in these known systems, the inclination of a trailing edge flap is controlled by the extension movement of said flap. 
         [0009]    In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
       SUMMARY 
       [0010]    In order to overcome these drawbacks, according to the various teachings of the present disclosure, a high-lift flap system for the rear portion of an aircraft wing is provided, which system comprises: a trailing edge flap provided with a leading edge, a trailing edge, an upper surface and a lower surface, and a mechanism for actuating said trailing edge flap, allowing said flap to assume: either a stowed position for which said trailing edge flap is housed at least in part in the rear portion of said wing, such that the upper surface and lower surface of said flap are continuously aerodynamic with respect to the upper surface and lower surface of said rear wing portion and that the trailing edge of said trailing edge flap forms a portion of the trailing edge of said rear wing portion, or at least one extended position for which said trailing edge flap is set back from the trailing edge of said wing and inclined relative thereto. 
         [0011]    The actuating mechanism comprises: translation drive means, which are housed at least in part in the rear portion of said wing and which comprise at least one driven movable element, and rotation means, which are housed in said trailing edge flap and are connected to the movable element so as to be able to rotate said trailing edge flap relative to said movable element, about an axis parallel to the leading edge of said trailing edge flap. 
         [0012]    The various teachings of the present disclosure are distinctive in that said rotation means are formed by a rotating actuator, of which the rotation shaft defines the axis of rotation of said trailing edge flap. 
         [0013]    Thus, according to the various teachings of the present disclosure, the translation movement, moving the trailing edge flap from its stowed position to an extended position and vice versa is dissociated from the rotation movement for inclining the trailing edge flap in the extended position. Through dissociating the two types of movement in this manner, the present disclosure, while still making it possible to obtain a large backwards movement and a large pivot movement of the trailing edge flap, also allows for simple incorporation of the actuating mechanism of the trailing edge flap inside the rear portion of the wing and for independence of the rotation of the trailing edge flap, relative to the extension thereof Thus, in the stowed position of the trailing edge flap, that is to say in high-speed cruise flight, the configuration of the wing is perfectly smooth (the above-mentioned fairings being redundant and thus dispensed with), which allows for significant gains in drag and thus in fuel consumption, whereas, when said trailing edge flap is in an extended position, any desired optimum rotation can be conferred thereon. 
         [0014]    In one embodiment, according to the various teachings of the present disclosure, said translation drive means are capable of conferring on said trailing edge flap a plurality of different extended positions and, since operation of said translation drive means is independent of operation of said rotation means, at each extended position said rotation means can confer a plurality of different rotations on said trailing edge flap. 
         [0015]    In addition, it will be noted that, unlike the centralised prior art set out above, the present disclosure allows for individual control of the trailing edge flaps of a wing. In this case, all of the actuating mechanisms of the trailing edge flaps of a wing are operated and synchronised by a computer and a monitoring channel having position sensors. 
         [0016]    Said rotating actuator may be either electric or hydraulic. For ease of control and owing to the level of torque, it is advantageous for said actuator to be of the electro-hydraulic type, known in the art as the electric hydraulic actuator (EHA). 
         [0017]    In one embodiment, said rotating actuator is arranged in the trailing edge flap in such a way that its axis of rotation is located at a distance from the leading edge of said trailing edge flap located between about 30% and about 40% and in one example, at approximately 35% of the chord length thereof. Indeed, in a known manner, it is in this region that the aerodynamic resultant of the profile of said flap is located, thereby minimising the torque to be supplied by the rotating actuator to actuate the trailing edge flap. 
         [0018]    In one example, said rotating actuator and the movable element are joined by means of a lug which is rigidly connected to the rotation shaft of said actuator and is engaged in a recess in said movable element. 
         [0019]    For ease of maintenance, it is advantageous for said rotating actuator to be arranged in a removable casing inserted in a corresponding housing of said trailing edge flap. In one example, when fixed in said housing, said removable housing contributes to the structural resistance of said trailing edge flap. In addition, said housing is advantageously accessible via an opening made in the upper surface of said trailing edge flap, and the top face of said removable casing is formed so as, when said casing is positioned in its housing, to seal said opening and to form the corresponding portion of said upper surface. 
         [0020]    Thus, relative to the trailing edge flaps of the above-described prior art, the present disclosure has numerous advantages: very significant aerodynamic gain since dispensing with the lower surface fairings results in, on the one hand, an obvious decrease in drag and, on the other hand, an increase in lift through exposing lift zones; increase in adjustment options, since translation and rotation of the trailing edge flap are independent; greater freedom for the wing unit through doing away with the constraint of the trailing edge flaps sharing a drive shaft; increase in the extension speed of the trailing edge flap where necessary; gains in simplicity, weight and cost, since the parts used are simpler, fewer in number and more compact; better balance of the aerodynamic loads in high-lift mode, owing to the possibility for rapid closed-loop control; option of using larger backward movements and rotations of the trailing edge flap than necessary, so as to improve the high-lift performance of the aircraft as a whole; and option of using the trailing edge flaps for other purposes aside from lift augmentation, such as the use in air brakes by orienting said flaps upward. 
         [0021]    A person skilled in the art can gather other characteristics and advantages of the disclosure from the following description of exemplary embodiments that refers to the attached drawings, wherein the described exemplary embodiments should not be interpreted in a restrictive sense. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
           [0023]      FIGS. 1A and 1B  comprises two diagrams showing a side view of an embodiment of the present disclosure, with a trailing edge flap in a stowed and extended position respectively. 
           [0024]      FIG. 2  is a perspective view of a casing containing a rotating actuator for actuating the trailing edge flap. 
           [0025]      FIG. 3  is a perspective view of an embodiment of the system in  FIGS. 1A and 1B , using the casing in  FIG. 2 . 
           [0026]      FIGS. 4 to 7  are schematic cross sections of various configurations of the system according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
         [0028]      FIGS. 1A and 1B  schematically shows the rear portion  1  of an aircraft wing provided with a high-lift flap system comprising a trailing edge flap  2 . 
         [0029]    The trailing edge flap  2  is an aerodynamic surface comprising a leading edge  3 , a trailing edge  4 , an upper surface  5  and a lower surface  6 . 
         [0030]    As shown in  FIG. 1A  and  FIG. 1B , the trailing edge flap  2  can adopt: either a stowed position ( FIG. 1A ) for which the trailing edge flap  2  is housed in an undercut  7  (see  FIG. 1B ) in the rear wing portion  1 , such that the upper surface  5  and the lower surface  6  of the trailing edge flap  2  are continuously aerodynamic with the upper surface  8  and the lower surface  9  of said rear wing portion  1  respectively, and that the trailing edge  4  of the trailing edge flap  2  forms a trailing edge portion  10  of said rear wing portion  1 , or an extended position ( FIG. 1B ) for which said trailing edge flap  2  is set back from the trailing edge  10  of said rear wing portion  1  and inclined relative thereto. 
         [0031]    To move the trailing edge flap  2  from its stowed position to its extended position and vice versa, the system shown schematically in  FIGS. 1A and 1B  comprises an actuating mechanism  11 ,  12 ,  14  composed of: translation drive means which are housed in the rear wing portion  1  and comprise at least one curved rail  11 , guided and driven by drive wheels  12 , which are themselves driven by one or more motors (not shown). The curved rail  11  can move within the undercut  7 , towards the rear and the front of the rear wing portion  1 . In its forwardmost position ( FIG. 1A ), which corresponds to the stowed position of the trailing edge flap  2 , the curved rail is fully housed in the rear wing portion  1 . By contrast, in its rearmost position ( FIG. 1B ), which corresponds to the extended position of the trailing edge flap  2 , the curved rail  11  projects downward, outside the undercut  7 . As can be seen by comparing  FIGS. 1A and 1B , the curved rail  11  makes it possible to obtain, by means of curved translation, a significant backward movement R for the trailing edge flap  2 . The actuating mechanism  11 ,  12 ,  14  also comprises rotation means  14 ,  15  comprising at least one rotating actuator  14  which is housed in the trailing edge flap  2  and is connected to the rear portion  13  (at the rear end in the embodiment shown) of the curved rail  11  so as to be able to rotate this flap, relative to the rail  11 , about an axis  15  parallel to its leading edge  3  (see the double-headed arrow f). The rotating actuator  14  may be of the electro-hydraulic type, known in the art as an electric hydraulic actuator (EHA). For example, the rotating actuator  14  is a rotating EHA that generates significant torque while being more compact. 
         [0032]    It can thus be seen that by controlling the drive wheels  12  and by controlling the rotating actuator  14 , it is possible to move the trailing edge flap  2  having a length R backward (or forwards) and to confer thereon the desired inclination. Of course, it is possible to synchronise these two translation and rotation commands. 
         [0033]    It will be readily understood that by controlling the wheels  12  and the curved rail  11  it is possible to confer on the trailing edge flap  2  a plurality of intermediate extended positions between the forward most position in  FIG. 1A  and the rearmost position in  FIG. 1B  and that, by controlling the rotating actuator  14 , it is possible to make the trailing edge flap  2  rotate in a plurality of different ways at each of said intermediate extended positions. In addition, owing to the rotating actuator  14 , the trailing edge flap  2  can be inclined upward or downward at each of said intermediate positions. 
         [0034]    The rotation shaft  16  of the rotating actuator  14  defines the axis of rotation  15  of the trailing edge flap  2 . As aforesaid, the rotating actuator  14  is arranged in the trailing edge flap  2  such that the axis of rotation  15  is located at a distance d from the leading edge  3  located between about 30% and about 40% and in one example, at approximately 35% of the chord length C of the profile of said flap  2 , that is to say in the vicinity of the point of application of the resultant F of the aerodynamic forces exerted on the flap. 
         [0035]    In an embodiment of the present disclosure, shown in  FIGS. 2 and 3 , the rotating actuator  14  is arranged in a casing  17  that can be removably inserted in a corresponding housing  18  of said trailing edge flap  2 . 
         [0036]    A drive lug  19  orthogonal to the rotation shaft  16  of the rotating actuator  14  is connected for conjoint rotation to said shaft and engaged in a channel  20  in the movable element  11 . Thus, when the rotating actuator  14  is actuated and its rotation shaft  16  rotates, the lug  19  is arrested relative to the movable element  11  and the trailing edge flap  2  rotates about the axis  15 . 
         [0037]    When, as shown in  FIG. 3 , the removable casing  17  is inserted and fixed in the housing  18  provided in the trailing edge flap  2  (said fixing being able to be carried out in any known manner (not shown)), said casing  17  contributes to the structural resistance of said flap. 
         [0038]    In one example, the housing  18  for the casing  17  is accessible via an opening  21  made in the upper surface  5  of the trailing edge flap  2 , and the top face  22  of the removable casing  17  is formed to seal the opening  21  in the upper surface  5  and to form the corresponding portion thereof when said casing is fixed in its housing  18  ( FIG. 3 ). 
         [0039]      FIGS. 4 to 7  show schematic cross sections of various configurations of the system according to the various teachings of the present disclosure:  FIG. 4  shows the system in  FIG. 3 ; in  FIG. 5  a movable rail  11  is provided on either side of the rotating actuator  14  so as to obtain more force with which to actuate the flap  2  and better balance of forces; in  FIG. 6  just one movable rail  11  is provided for two adjacent flaps  2 ; and in  FIG. 7  the shaft  16  bears two lugs  19  housed in recesses (channels) made in opposite faces of the movable rail  11 . 
         [0040]    Regardless of the embodiment of the system according to the teachings of present disclosure, it is advantageous, for rigidity reasons, for the movable rail(s)  11  to have an I-shaped profile. 
         [0041]    While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.