Abstract:
An assembly for guiding a cable between a structural part of an aircraft and a movable aerodynamic body includes a chain of pivotally connected links, a first coil device arranged between each pair of the links for guiding the cable between two angular positions, and a second coil device arranged at the first end of the chain for passing the cable from the chain to the aerodynamic body. The support of the assembly is statically determinate through the use of a bracket pivotally connected to one of the links at the structural part, which bracket does not permit a translative motion relative to the structural part. This is further supported by a bearing located at one of the links which is connected to the second coil device, which bearing permits angular rotation at least in two orthogonal directions, but no translative motion relative to the aerodynamic body.

Description:
[0001]    The invention relates to an assembly for guiding a cable between a structural part of an aircraft and an aerodynamic body movably supported relative thereto. The invention further relates to a wing of an aircraft having such an assembly and, furthermore, to an aircraft having such a wing. 
       BACKGROUND OF THE INVENTION 
       [0002]    In aircraft, often electrical connections, i.e. one or more cables, between an aircraft wing structure and an aerodynamic body movably supported relative thereto are present, e.g. for connecting electrical de- or anti-icing devices to a central power source. Due to the relative motion it is mandatory to route or guide the necessary cables such that they are protected from mechanical damage and provide a reliable function for a desired lifetime period. 
         [0003]    US 2011/0100679 A1 describes a pair of mechanical links pivotally connected to pivot relative to one another about a lateral pivot axis and extending between a wing structure and a slat supported movable relative thereto. A cable extends along both links and a wound section with a winding axis coincident with the pivot axis is provided, wherein a cable protecting housing is arranged at each end of the wound section. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    In case additional deflecting motions between an extended aerodynamic body, such as a slat, and the aircraft structure, such as a wing structure, due to air loads during flight occur, constraining forces are induced into the links of such an assembly for guiding cables. The constraining forces may laterally to the existing pivoting axes and result in the requirement for a more conservative design with a much larger rigidity than necessary for the main purpose of guiding a cable An aspect of the invention may provide an improved assembly for guiding a cable between an aircraft structure and an aerodynamic body movably supported thereto, that is less subjected to these constraining forces. 
         [0005]    An assembly for guiding a cable between a structural part of an aircraft in an aerodynamic body movably supported relative to the structural part is proposed. The assembly comprises a chain of at least two pivotally connected links, the chain having a first end and a second end for receiving the cable from the structural part and introducing it into the chain of links, a first coil device arranged between each pair of the at least two pivotally connected links for guiding the cable between two variable angular positions of the associated links, a second coil device arranged at the first end of the chain for passing the cable from the chain of links to the aerodynamic body and a bracket pivotally connected to one of the links situated at the second end for mounting the chain at the structural part, which bracket permits an angular rotation around one axis, but no translative motion relative to the structural part. The assembly is characterized by a bearing located at one of the links which is connected to the second coil device at the first end of the chain, which bearing permits an angular rotation at least in two orthogonal directions, but no translative motion relative to the aerodynamic body. 
         [0006]    In general, this assembly for guiding a cable according to an embodiment of the invention is an extendable and collapsible/foldable device, which is designed so as to extend between the respective structural part of the aircraft and the respective aerodynamic body movably supported relative thereto. The cable that needs to be guided from a power source inside the structural part to the movable aerodynamic body is thereby held by the assembly and safely and without damages follows the relative motion between these two parts. 
         [0007]    Core components of the assembly according to an embodiment of the invention are the links, which provide a protected running surface for the cable. For this purpose, the links comprise a receiving space for receiving and holding the cable, which receiving space may be provided through the appropriate design of the cross-sectional profile surface of the links having a cut-out for introducing the cable into the interior of the links, such that a rim- or channel-like structure or a hollow space results, in which the cable is held. Preferably, the cable inserted into the links is held in place by fasteners or holders, such as clips or brackets arranged in the links by the use of positive connecting means, such as snap-in fasteners, adhesives or non-positive connecting means. When the relative motion of the structural part and the aerodynamic body is conducted, the assembly follows this motion and permanently holds the cable protected inside the links between the first end and the second end. 
         [0008]    The first coil devices are to be understood as arrangements that allow the pivoting of the links connected to the first coil devices repeatedly, while the cable is permanently inserted in the respective first coil device and follows the pivoting motion of the associated links. By using these first coil devices, the cable is protected in the pivoting region between two adjacent links such that it is not necessary to let a part of the cable extend outwardly in a joint region between two links for being able to easily follow the motion of the links. The first coil devices therefore act as cable protectors. 
         [0009]    The second coil device may be similar to the first coil device. According to an embodiment of the invention, the second coil device may include the bearing that permits an angular rotation in the at least two orthogonal directions or it may be connected thereto. By using such a bearing, only translational forces can be transmitted through the chain of links, but a bending force or moment cannot be introduced into the link connected to this bearing. In case any air load induced additional motion in a direction orthogonal to the extension direction of the links occurs, the bearing simply eliminates the urge to bend the extended link chain between the aerodynamic body and the structural part. 
         [0010]    In other words, a great advantage of this bearing is based on the fact that a kinematic decoupling of the assembly according to an embodiment of the invention is achieved. The whole assembly, which extends from the aerodynamic body to the aircraft structure, is consequently supported in a statically determinate way through the bracket and the bearing. Hence, neither additional deflections due to air loads, nor thermal expansions lead to constraining forces that may result in additional structural loads. The assembly being statically determinate means that a static equilibrium can always be maintained. Hence, the static equations are sufficient for determining the internal forces and reactions on the assembly and the sums of the force components in every spatial direction equal zero; the same applies for the sum of moments of all forces. 
         [0011]    Altogether, this allows for a more lightweight design of the assembly as well as a clearly increased reliability for operation. Consequently, the maintenance requirements are clearly reduced. 
         [0012]    In a preferred embodiment, the bearing that permits an angular rotation in at least two orthogonal directions is a spherical bearing. Such a bearing may comprise an outer ring and an inner ring, between which rolling elements are placed that allow for a rotation about a central axis of each of the rings. For the purpose of additionally allowing an angular rotation of the inner ring and the outer ring of the spherical bearing such that their radial extension planes may intersect with each other, the outer surface of the inner ring and the inner surface of the outer ring are spherical or toroidal. These spherical bearings may be designed in a maintenance-free manner and consequently allow for a distinct reliability, which is particularly useful for installations in an aircraft. 
         [0013]    In an advantageous embodiment, a first coil device comprises a joint having a joint axis, around which the cable is wound with at least one complete winding. The winding of the cable inside the first coil device is helical. The first coil device, which acts as a cable protector, may comprise a disk-like shape with a central opening to accommodate the joint axis and may preferably be produced by two main components that may engage each other, rotate around the joint axis independently and enclose the wound section of the cable. By winding the cable around the joint axis with at least one complete winding, a cable section that enters the first coil device and a cable section that exits the first coil device always enclose an angle relative to each other that is larger than 360°. The helical cable coil generated in the first coil device allows to alter the angle between the incoming cable section and the outgoing cable section simply, while not requiring a large installation space for the cable in this joint region and for gentle handling of the cable. 
         [0014]    It is furthermore advantageous to accommodate further helical coils in a single first coil device, for example by providing two or more separate receiving spaced within the respective links that run into a certain section of the associated first coil device, which may either be separated or belong to the same cross section. 
         [0015]    In a preferred embodiment, two subsequent first coil devices connected to the same link are covered by a single cover plate, which extends between the two first coil devices and covers a recess of the respective link as well as the central openings of both first coil devices. This simplifies the assembly, repair and maintenance of the assembly according to the invention significantly. A cable guided in the chain of links may easily be maintained by simply removing the cover plate and exemplarily removing or mounting it in the first coil devices. 
         [0016]    In a further embodiment, the cover plate is removable from the respective link without the necessity for disassembling the chain. Consequently, all adjacent components do not cover or overlap the cover plate such that maintenance, assembly or disassembly of the cover plate or the cable behind the cover plate is hindered. 
         [0017]    In a still further exemplary embodiment, the bracket comprises a joint which permits an angular position rotation exclusively in a first direction of rotation. By limiting the rotational axis at one end of the chain, a precise, reliable and repeatable unfolding and folding operation of the assembly according to the invention may be conducted due to the limited degree of freedom. 
         [0018]    Still further, the pivotally connected links are adapted for conducting an angular rotation exclusively in a second direction of rotation. This limits the pivoting action between two connected joints, such that the degree of freedom of the chain of links itself is limited and the assembly may precisely and reliably follow the motion of the aerodynamic body. Also, this supports the compactness of the folded chain of links. 
         [0019]    It is thus preferred, that the first direction and the second direction of rotation are arranged at an angle to each other. The collapsing/folding or extension of the chain of links is thereby provided in another plane than the rotation of the chain of links around the bracket. These two motions are decoupled and do not hinder each other. An introduction region for receiving the cable from the structural part of the aircraft at the second end may thereby provide a least possible motion and the excess length of the cable extending from the structural component to the introduction region is as small as possible. 
         [0020]    Exemplarily, the angle is 90°. This means, that the rotational axis of the joint in the bracket and between the connected links are orthogonal to each other, which leads to a further improved movability of the links relative to each other. 
         [0021]    A still further embodiment of the assembly according to an embodiment of the invention comprises an entering guide, which is located at one of the links connected to the bracket for receiving the cable from the structural part of the aircraft and for leading it into the links that follow on. The entering guide may comprise at least one and preferably two surfaces arranged at a distance to each other and smoothly run into the profile of the respective link at the second end. The surfaces preferably widen up in a direction facing away from the link, which means that their distance increases for collecting and guiding one or more cables into the chain of links. Widening this section is advantageous as this may allow the cable section between the entering guide and the exiting point at the structural component to partially compensate the pivotal motion around the bracket. A larger degree of freedom for the cable that runs from the structural part to the introduction region of the link at the bracket is thereby provided. 
         [0022]    In a preferred embodiment, the entering guide extends beyond the bracket and faces away from the link connected thereto. This ensures a required segregation of the cables and the skin of the aircraft structure, which allows for eliminating a contact based damaging, i.e. through friction, of the cable through the aircraft structure. 
         [0023]    The invention further relates to a wing of an aircraft, comprising a wing structure and an aerodynamic body movably supported relative to the wing structure, wherein an assembly presented above is connected to the wing structure and to the aerodynamic body. The aerodynamic body may preferably be a slat, which may especially include a leading edge slat that conducts a clear and prominent translational motion relative to the wing structure. The covered distance between the aerodynamic body and the structural part of the aircraft needs to be bridged by the cable, which is guided by the assembly according to the invention in a reliable and safe manner, independent from lateral, air load induced motions between the aerodynamic body and the wing structure. 
         [0024]    Finally, the invention relates to an aircraft comprising at least one such wing. In an embodiment, the aircraft comprises a wing de-icing or anti-icing device inside the aerodynamic body, which is connected through a cable with a power source inside the wing structure, wherein the cable runs through the assembly extending between the wing structure and the aerodynamic body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    Further characteristics, advantages and application options of the present invention are disclosed in the following description of the exemplary embodiments in the figures. All the described and/or illustrated characteristics per se and in any combination form the subject of the invention, even irrespective of their composition in the individual claims or their interrelationships. Furthermore, identical or similar components in the figures have the same reference characters. 
           [0026]      FIG. 1  schematically shows an assembly for guiding a cable between a leading edge slat and a wing structure in a collapsed state. 
           [0027]      FIG. 2  schematically depicts the extension of the slat shown in  FIG. 1  and the assembly for guiding a cable being extended. 
           [0028]      FIG. 3  shows a sectional view of an exemplary bearing that permits an angular rotation around two orthogonal axes at a second coil device. 
           [0029]      FIG. 4  demonstrates the additional motion due to air loads on the assembly for guiding a cable in an extended state. 
           [0030]      FIG. 5  shows a still further drawing of an assembly for guiding a cable in a collapsed/folded state. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  shows an assembly  2  according to an embodiment of the present invention arranged between a wing structure  4  of an aircraft and a movably supported aerodynamic body  6 , which is designed as a leading edge slat in this exemplary embodiment. The assembly  2  comprises a bracket  8 , which is attached to the wing structure  4  and supports a first link  10 , which is swivably mounted around a first axis  12  defined by and extending through the bracket  8 . In this exemplary embodiment the first axis  12  is arranged substantially parallel to the z axis of the aircraft, which vertically extends to the longitudinal axis x of the aircraft, to which the wing structure  4  belongs, and parallel to the gravitational force (the relating coordinate system is shown in  FIG. 1 ). The first link  10  consequently stays in a plane extending substantially vertically to the first axis  12 . At an end opposite to the bracket  8 , the first link  10  provides a substantially fixed vertical position for a second link  16 , which is pivotally connected to the first link  10 . Primarily in case air loads or thermal expansion effects lead to a lateral motion of the slat  6  relative to the wing structure  4 , the rotation of the first link  10  around the first axis  12  prevents straining forces at the bracket. Besides that, the positioning of the first axis  12  in the bracket  8  for supporting one end of the first link  10  ensures the required segregation of a cable and a wing skin. 
         [0032]    The first link  10  exemplarily comprises a rim- or channel-like structure  14 , which is adapted for receiving and guiding a cable  25  from the wing structure  4  to the second link  16 . In a sectional view A-A an exemplary double-T-shaped profile structure  14  of the first link  10  is presented. At least in case an open profile is used, appropriate holders, such as clips or brackets, should be used for holding the cable  25  relative to the respective link. However, this cross sectional profile surface has to be understood merely as an example, which is neither binding nor preferred. The person skilled in the art may choose any other open or closed cross sectional surface of this profile meeting the individual requirements or design demands. 
         [0033]    The second link  16  is connected to the first link  10  by means of a first coil device  18  comprising a central opening  19 , through which a joint axis  21 , e.g. comprising a pin or bolt, extends and allows for the pivoting motion between the first link  10  and the second link  16 . Exemplarily, the pivoting motion provided by the first coil device  18  is basically conducted around the y-axis. In the interior of the first coil device, the cable to be guided is wound around the joint axis  21  and runs from the first link  10  into the second link  16  in form of a helical coil. The first coil device  18  may comprise two main housing components  22  and  23 , that are either connected to the first link  10  or to the second link  16  and are adapted for rotating about the joint axis  21 . An exemplary embodiment of the first coil device  18  is shown in a sectional view B-B. Here, at each side of the first coil device  18  a cable  25  may be fed through, wherein it is wound by more than 360° inside the first coil device  18  around the joint axis  21 . As rendered more clear by the sectional view B-B the second link  16  comprises two closed profiles for guiding cables  25 . The first link  10  is enclosed between the two main housing components  22  and  23 . 
         [0034]    Following on from the second link  16 , a third link  26  is pivotally connected to the second link  16  by means of another first coil device  18  at an end opposite to the connection between the first link  10  and the second link  16 . Here, the joint axes  21  of both first coil devices  18  are parallel to each other. By moving the slat  6  into an extension position relative to the wing structure  4 , the assembly of the first, the second and the third links  10 ,  16  and  26  is unfold by pivoting the respective links around the joint axes  21 . The third link  26  may be designed in the same manner as the first link  10 , such that it may comprise an open profile cross section, too. 
         [0035]    Following on from the third link  26 , a second coil device  28  is provided at an end of the third link  26  opposite to the connection between the second link  16  and the third link  26 . The second coil device  28  also comprises a central opening  19 , through which a joint axis  29  extends. The second coil device  28  is attached to the slat  6  for passing a cable from the chain of links  10 ,  16  and  26  to the slat  6 . Preferably, the joint axis  29  of the second coil device  28  is parallel to the joint axes  21  of the first coil devices  18 . 
         [0036]    As rendered more clear in  FIG. 3 , the second coil device  28  allows for compensation of lateral motions due to air loads during the flight, which lateral motions comprise a translational component parallel to the joint axes  21  and  29 , respectively. This is achieved by a bearing in the second coil device  26  that permits an angular rotation in two orthogonal directions. 
         [0037]    As stated before,  FIG. 1  shows the slat  6  in a fully retracted position, e.g. during cruise flight conditions. The chain of links  10 ,  16  and  26  assumes a folded/collapsed shape as compact as possible and rest on each other.  FIG. 2  shows an extended position of the slat  6 , which has to be followed by the assembly  2  for guiding a cable according to the invention. 
         [0038]      FIG. 3  depicts the second coil device  28  in a sectional view. A spherical bearing  30 , comprising a ball segment  32  rotatably supported on the joint axis  29 , as well as a ring  34  enclosing the ball segment  32 , thereby providing two spherically engaging bearing surfaces, is present. Due to the expected air loads during flight, a kinetic decoupling between the assembly  2  and the aerodynamic body  6  is supported through the bearing  30  directly at the slat  6  and the bearing at the bracket  8  connected to the aircraft structure. By using the spherical bearing  30  at an attachment flange  33  to the slat  6 , only translational forces can be transmitted. The pivotal support on the bracket  8  around the axis  12  being orthogonal to the joint axis  29  further ensures the statically determinate (iso-static) support of the assembly  2 . The location and the direction of the axis  12  of the bracket  8  is determined such that a center of the spherical bearing  26  keeps a certain distance during deployment of the aerodynamic body  6 . It goes without saying that the second coil device  28  may also comprise two main housing components  22  and  23  in a symmetrical arrangement and that the third link  26  is enclosed by these two main housing components. 
         [0039]    In  FIG. 4 , a further drawing of an extended assembly  2  is shown, where the aerodynamic body  6  is extended from the wing  4  such that the assembly  2  is extended, too. As made visible through the dashed arrows, lateral forces are shown, which may be compensated by the combination of the bearing included into the bracket  8  and spherical bearing  30 . 
         [0040]    Further, a cover plate  36  covers both first coil devices  18 . This simplifies the assembly, repair and maintenance of the assembly  2  significantly. By simply removing the cover plate  36 , a cable may be introduced into the channel-like structure  14  in the second link  16 . 
         [0041]    Additionally, a possible structure of the individual links  10 ,  16  and  26  is demonstrated. While the first link  10  comprises an open profile cross section  14  with lateral recesses for the cable  25 , the second link  16  comprises two laterally positioned and closed cross-sectional shapes. Here, the cable  25  coming from the first link  10  runs from the lateral recesses into the subsequent closed profile shape. As stated before, the third link  26  may be designed similar to the first link  10 , such that the cable  25  may run from the closed cross-sectional shapes of the second link  16  into the lateral recesses of the third link  26 . This allows a simplified design of the assembly  2  and especially of the first coil devices  18  and the second coil device  28 . As the cable  25  comprises the shape of a helical coil it is mandatory for the cable  25  to change a lateral position along the run length of the chain of links, which can be accomplished by subsequently running through lateral recesses and a closed shape of the links  10 ,  16  and  26 . 
         [0042]      FIG. 5  depicts the assembly  2  in a folded state with the links  10 ,  16  and  26  basically laying flush on each other. In the drawing, the first link  10  is on top, which first link  10  comprises an entering guide  38 , which basically consists of two surface sections  40  and  42  arranged at a distance to each other and defining an entering region  44  for a cable  25 . The entering guide  38  is located at an end of the first link  10  opposite to the connection with the second link  16  and extends beyond the bracket  8  in a direction facing away from the connection to the second link  16 . The distance between the two surface sections  40  and  42  may increase in this direction for improving the collecting and guiding function of the entering region. Altogether, the entering guide  38  together with the bracket  8  allow for a required segregation of the cable from a skin of the aircraft structure and for a perfect introduction into the chain of links  10 ,  16  and  26 . 
         [0043]    In addition, it should be pointed out that “comprising” does not exclude other elements or steps, and “a” or “an” does not exclude a plural number. Furthermore, it should be pointed out that characteristics or steps which have been described with reference to one of the above exemplary embodiments can also be used in combination with other characteristics or steps of other exemplary embodiments described above. Reference characters in the claims are not to be interpreted as limitations.