Patent Publication Number: US-2019178272-A1

Title: Probe fastening system and aircraft

Description:
FIELD OF THE INVENTION 
     The present invention relates to a probe fastening system, to a clamping apparatus, and to an aircraft. 
     BACKGROUND OF THE INVENTION 
     The cockpits of aircraft have a number of barometric flight instruments which assist the pilots in correctly controlling the aircraft. These flight instruments are fed with pressure information by means of pitot-static systems. Important constituent parts of this pitot-static system are static probes, which are coupled to the outer side of the aircraft and measure the outside air pressure. 
     For this purpose, the edges of the fastening that couples the static probe to the aircraft skin and the aircraft skin should lie on one another in as flush a manner as possible in order to minimize air turbulence, which itself can falsify the measurement results of the static probe. 
     To set the fastening for an extremely accurately fitting form combination, in the applicant&#39;s in-house prior art, use is made of large-area tolerance compensation layers which are composed of a multiplicity of very thin individual foils and adhesive layers applied in between. Such peelable shims are described for example in DE 20 2011 107 070 U1. 
     This known solution relocates the edge between fastening system and aircraft skin uniformly over the entire region of the fastening system. A concern here is that aircraft are normally delivered in a so-called “green” state to airlines. After delivery, the airline paints the outer side of the aircraft fuselage with an aesthetically appealing paint and possibly with logos of the airline. The aircraft manufacturer then self-evidently has no control of the application of these paint layers, and in particular has no control over the uniformity of the thickness of the paint layers. 
     BRIEF SUMMARY OF THE INVENTION 
     Against this background, an aspect of the present invention may provide a means for realignment of the static probes after the painting process, in such a way that, even in the presence of possible irregularities in the paint layer, it is made possible to realize an extremely accurately fitting form combination of the static probe with respect to the aircraft skin. 
     According to an embodiment, a probe fastening system is provided. The fastening system comprises a plate having at least one coupling-on recess and having at least one alignment element, which is arranged in the outer region of the plate, a backplate which has a fastening device for the fastening of a static probe and at least one recess which corresponds with the alignment element, at least one peelable shim which corresponds with the alignment element and which is arranged between the plate and the backplate, at least one alignment device which corresponds with the alignment element, and a coupling-on element which defines a cavity and which is designed for isobarically coupling the static probe onto the coupling-on recess. 
     An aircraft is furthermore provided according to another embodiment. The aircraft comprises a fastening system arranged on the fuselage of the aircraft, wherein the fastening system is arranged such that one of the alignment elements of the fastening system is oriented in a direction flight of the aircraft. 
     A concept on which the present invention is based consists in decentralising the alignment of the form combination of the aerodynamic plate with respect to the, possibly painted, aircraft skin. Accordingly, the form combination can, after the installation of the static probe or the painting of the aircraft skin, be adapted to any unevennesses present in the paint layer. In this way, it can be ensured, aside from a general optimization of the form combination, that in particular the important edge in the direction of flight of the aircraft is formed flush with respect to the surface. 
     Advantageous designs and refinements will emerge from the further subclaims and from the description with reference to the figures. 
     In one refinement, the plate may have an even number of alignment elements, which are arranged pairwise on substantially opposite sides of the plate. This permits a particularly fine setting of the form combination along a selected axis, advantageously along the direction of flight axis of the aircraft. 
     In one refinement, the plate may have four alignment elements, which are arranged rotationally symmetrically. This arrangement permits, in an advantageously clear manner, an extremely accurately fitting flush configuration of the form combination over an entire circumference. 
     In one exemplary embodiment, the alignment elements may be of hollow form and comprise an internal thread, wherein the recesses of the backplate comprise a cylinder wall, and the alignment devices comprise screws, the threads of which are adapted to the internal threads of the alignment elements, and the heads of which are designed to lie on the cylinder walls of the backplate. 
     In one refinement, the alignment elements may comprise an external thread, and the alignment devices may comprise nuts with internal threads adapted to the external threads of the alignment elements. 
     In one exemplary embodiment, each of these alignment elements may have a laterally arranged recess, wherein the alignment device comprises a splint, which is designed to be inserted into and wedged in the recess of the alignment element. In this way, the situation is advantageously prevented in which the nut loosens over the course of time, and the form combination of the aerodynamic plate is impaired. 
     In one refinement, said alignment elements may be of hollow form. This saves material and weight, which is advantageously desired in the aviation sector. 
     In one exemplary embodiment, the alignment device may comprise a cover which is arranged in each case over one of the alignment elements. This serves for the additional fastening of the splint and thus also for an improved fastening of the nut. 
     In one refinement, additional fastening means may be provided for fastening the plate to the backplate. This relieves the alignment elements of load, because forces acting on the aerodynamic plate are advantageously intercepted by the fastening means, whereby the alignment of the form combination is maintained during the operation of the aircraft. 
     In one refinement, said fastening means may comprise a peelable spacer element. In this way, the possibility of alignment of the form combination of the aerodynamic plate using the fastening means is facilitated. It is particularly advantageously possible here for a coarse alignment of the aerodynamic plate as a whole to be performed by means of the spacer element, and for the alignment elements to serve for a fine alignment of the individual directions of the aerodynamic plate. 
     In one exemplary embodiment, the backplate may have a wall element, and the fastening devices may be formed as part of the wall element. Such a wall element provides the fastening system with advantageous structural stability, and permits a likewise advantageous stable fastening of the static probe. Such a wall element also permits the advantageous design of further functional features, such as for example of an earthing device for protection against lightning strikes during flight. 
     The coupling-on element for the isobaric coupling of the static probe onto the coupling-on recess may be formed integrally with the plate or with the backplate. 
     The invention furthermore provides a clamping apparatus for the mounting of a fastening system onto an aircraft skin. The clamping apparatus has a body which is designed to fill the cavity defined by the coupling-on element, and a fixing plate which is designed to be connected to the fastening devices. 
     The above designs and refinements may be combined with one another in any desired manner where expedient. Further possible designs, refinements and implementations of the invention also encompass combinations, which have not explicitly been mentioned, of features of the invention described above or below with respect to the exemplary embodiments. In particular, here, a person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be discussed in more detail below on the basis of the exemplary embodiments specified in the schematic figures, in which: 
         FIG. 1  shows a schematic view of an exemplary embodiment of a fastening apparatus in the unmounted state; 
         FIG. 2  shows a schematic detailed view of an alignment element and of an alignment device in the unmounted state; 
         FIG. 3  shows a schematic sectional view of an alignment element and of an alignment device in the mounted state; 
         FIG. 4  shows a schematic exploded view of a further exemplary embodiment of a fastening apparatus; 
         FIGS. 5 a -5 c    show schematic sectional views of three exemplary embodiments of a fastening apparatus; and 
         FIG. 6  shows a schematic view of a fastening apparatus having a clamping apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     The appended figures are intended to impart further understanding of the embodiments of the invention. They illustrate embodiments and serve, in conjunction with the description, for the explanation of principles and concepts of the invention. Other embodiments, and several of the stated advantages, will emerge with regard to the drawings. The elements of the drawings are shown not necessarily true to scale with respect to one another. 
     In the figures of the drawing, elements, features and components which are identical, functionally identical and of identical action are denoted in each case by the same reference designations unless stated otherwise. 
       FIG. 1  shows a schematic view of an exemplary embodiment of a fastening system  100 .  FIG. 1  illustrates the plate  110  and the backplate  120  separately from one another. The plate  110  has in this case a total of four alignment elements  112 , which are arranged rotationally symmetrically. In this exemplary embodiment, the alignment elements comprise external threads, which is however not explicitly illustrated in  FIG. 1  for the sake of simplicity. Illustrated for each of the alignment elements  112  is a corresponding peelable shim  130 , which surrounds the body of the respective alignment element  112 . A coupling-on element  150  in the form of a cylindrical wall is, in this exemplary embodiment, formed integrally with the plate  110 . In this exemplary embodiment, the fastening system  100  also has fastening means  160  in the form of four cylindrical bodies arranged offset rotationally symmetrically with respect to the alignment elements. The fastening means  160  also comprise a peelable spacer element  161 , which surrounds both the cylindrical bodies of the fastening means  160  and the cylindrical wall of the coupling-on element  150 . The backplate  120  shown in  FIG. 1  comprises a central hole, which corresponds with the coupling-on element  150 . The recesses  122  of the backplate are not visible in  FIG. 1 , because they are covered by the alignment devices  140 . The alignment devices  140  comprise, in this exemplary embodiment, nuts  142 , splints  143  and covers  144 . Also shown are additional nuts which are provided for the fixing of the fastening means  160  to the backplate. In this exemplary embodiment, the backplate  120  also has additional stiffening elements which are intended to impart additional structural stability to the fastening system  100 . 
     For the alignment of the form combination of the plate, the elements shown here are joined together and the backplate  120  is fastened to the inner side of an aircraft skin. Subsequently, the projecting length of the plate  110  relative to the edge of the aircraft skin, possibly with paint layer, can be determined. The plate  110  is thereupon released from the backplate  120  again. The thickness of the peelable shims  130  and of the peelable spacer element  160  is adapted by detachment of a corresponding number of layers. After reattachment of the plate  110  to the backplate  120  and tightening of the nuts  141  of the alignment devices  140 , the plate  110  and the edge of the aircraft skin now have an extremely accurately fitting form combination. 
     In the exemplary embodiments shown in  FIG. 1  and other figures, the alignment elements  112  have a cylindrical form. This is particularly advantageous for the design, provided in this exemplary embodiment, of the alignment elements  112  with external threads and the design of the alignment devices  140  with nuts  142 . In general, the alignment elements  112  may however have any desired shape, for example cuboidal. 
       FIG. 2  shows a schematic detailed view of an alignment element  112  and of an alignment device  140  from  FIG. 1 , before the plate  110  and the backplate  120  are fastened to one another.  FIG. 2  illustrates the cylindrical body of the alignment element  112 , wherein, as in  FIG. 1 , the external thread of the alignment element  112  is not illustrated for the sake of simplicity. The splint  143  is in this case illustrated laterally offset with respect to the alignment element  112 . After the mounting of the alignment device  140 , the splint  143  is inserted into the holes of the cover  144  and of the alignment element  112 . The nut  142  of the alignment device  140  is illustrated over the end of the alignment element  112 . The cover  144  is illustrated above the nut  142 . Also illustrated is a washer which may advantageously be provided in order to provide a better bearing surface for the nut  142  and protect the surface of the backplate  120 . 
     In this exemplary embodiment, the cover  144  has a total of six holes, of which four are visible owing to the perspective. Said holes permit advantageous fixing of the cover  144  by means of the splint  143 , wherein the orientation of the cover can be varied. In this exemplary embodiment, the cover  144  also has a further recess, which exposes a part of the nut  142  after the mounting process. In this way, after a certain length of time, the nut  142  can be re-tightened in order to maintain the alignment of the plate  110  without the need for the cover  144  to be removed for this purpose. 
       FIG. 3  shows a schematic sectional view of an alignment device from  FIGS. 1 and 2  after the fastening of the plate  110  to the backplate  120 . The nut  142  has been screwed onto the alignment element  112  such that the nut  142 , the optional washer, the backplate  120 , the peelable shim  130  and the plate  110  each lie against one another with a form fit. The splint  143  fixes the cover  144  to the alignment element  112 , and prevents the detachment of the nut  142 . 
     In this configuration, the spacing between the plate  110  and the backplate  120  at the position of the alignment element  112  is predefined only by the thickness of the peelable shim  130 . The spacing can thus be modified by decreasing the thickness of the peelable shim  130  by removing individual layers, and the nut  142  is thereafter tightened again as far as a stop. In this way, the projecting length of the plate  110  in relation to the edge of the aircraft skin on the side of the alignment element  112  can be varied. Through the attachment of peelable shims  130  of different thickness to different alignment elements  112 , it is thus possible to realize an accurately fitting flush configuration of the form combination between plate and aircraft skin in all directions, even if unevennesses are present for example owing to varying thickness of a paint layer. 
       FIG. 4  shows a schematic exploded view of a further exemplary embodiment of a fastening system  100 . The exemplary embodiment shown here differs from the exemplary embodiment shown in  FIG. 1  in that the backplate has a wall element  124 , and in that the coupling-on element  150  is in this case formed integrally with the backplate. The cylindrical bodies, shown here, of the fastening means  160  are arranged rotationally symmetrically along a circle with a somewhat smaller radius than the circle on which the alignment elements  112  are arranged. Situated so as to be arranged centrally in the plate  110  is a circle of a total of eight coupling-on recesses  111 . The peelable shims  130  and an optional peelable spacer element  161  are shown in  FIG. 4  as being situated between the plate  110  and the backplate  120 . The wall element  124  comprises a substantially square wall with rounded corners, which in the mounted state separates the fastening means  160  from the alignment elements  112 . At the rounded corners, the wall element  124  has thickened portions with fastening devices  121  in the form of receptacles for screws. Extending radially outwards from the thickened portions, the wall element  124  furthermore has stiffening elements. Likewise shown between the plate  110  and the backplate  120  are two sealing rings  170 , one with a small radius and one with a large radius. Said sealing rings  170  serve, after the mounting process, for improving the sealing action of the connection between plate  110  and backplate  120 . 
       FIGS. 5 a  to 5 c    are schematic sectional illustrations of various exemplary embodiments of fastening systems  100 . 
       FIG. 5 a    shows an exemplary embodiment which substantially corresponds to the exemplary embodiment of  FIG. 4 . Here, the plate  110  and the backplate  120  lie horizontally one above the other. In the centre of the fastening system  100 , the plate  110  has coupling-on recesses  111 , of which three are shown in  FIG. 5 a   . The coupling-on recesses  111  are surrounded in a radial direction by the coupling-on element  150 , which in this exemplary embodiment is formed integrally with the backplate  120 . Adjoining this in a radial direction, the fastening system  100  has fastening means  160 , which in this exemplary embodiment are formed as cylindrical bodies of the backplate, which are fastened by means of nuts to the backplate  120 . Further to the outside in the radial direction, the plate  110  has alignment elements  112 , which in this case have an external thread, extend through corresponding recesses  122  of the backplate  120 , and are fastened by means of alignment devices  140  in the form of nuts  142  to the backplate  120 . At the position of the alignment elements  112 , peelable shims  130  determine the spacing between plate  110  and backplate  120 . Radially further to the outside, the plate  110  abuts against the aircraft skin  300 , whereas the backplate  120  extends radially further outwards for the purposes of fastening to the aircraft skin  300 . 
     The exemplary embodiment shown in  FIG. 5 b    differs from the exemplary embodiment shown in  FIG. 5 a    by the form of the alignment elements  112 , alignment devices  140  and fastening means  160 . The alignment elements  112  shown here are formed as cylindrical hollow bodies with an internal thread. The recesses  122  of the backplate in this case each have cylinder walls  123 , which surround the alignment elements  112 . The alignment devices  140  comprise screws  141 , the threads of which are adapted to the internal threads of the alignment elements  112 , and the heads of which lie on the ends of the cylinder walls  123 . The fastening means  160  are in the form of screws, which are screwed into corresponding receptacles of the backplate  120  and of the plate  110 . 
     The exemplary embodiment shown in  FIG. 5 c    differs from the exemplary embodiment shown in  FIG. 5 b    by the form of the coupling-on element  150  and of the fastening means  160 . In this exemplary embodiment, the coupling-on element  150  is formed integrally with the plate  110  and has an external thread. By means of a corresponding nut, the coupling-on element  150  in this exemplary embodiment accordingly also functions as fastening means  160 . 
     The fastening systems  100  shown in  FIGS. 5 a  to 5 c    each have an optional seal ring  170 , which is arranged outside the coupling-on element  150  between plate  110  and backplate  120 . Such a seal ring  170  is advantageously provided in order to improve the isobaric coupling of a static probe onto the coupling-on recesses  111 . 
       FIG. 6  shows a sectional view of the fastening system  100  from  FIG. 4  in a mounted state including a clamping apparatus  200 . The clamping apparatus  200  comprises a body  210 , which fills the cavity defined by the coupling-on element  150 , and a fixing plate  220 , which is connected to the fastening devices  121 . 
     For the functioning of a static probe during flight, said static probe should be connected as far as possible isobarically to the coupling-on recesses  111 . For this purpose, the fastening system  100  should be attached to the aircraft skin  300  without undesired deformations. It is however not expedient for the static probe to be attached to the fastening system  100  during the mounting process. A clamping apparatus  200  as shown here permits a deformation-free attachment of the fastening system  100  to the aircraft skin  300 . 
     For the description of the invention, the expression “aerodynamic plate” has been used at some points. This serves merely for clearly delimiting that plate which is not the backplate from the backplate. The expression aerodynamic plate” is commonly used in the aviation sector for this component of a fastening system for a static probe. The use of the expression “aerodynamic plate” is however not intended to be understood to mean that the plate must have yet further features, in particular with regard to its aerodynamic characteristics, in addition to the features described in conjunction with the present invention. 
     The exemplary embodiments described here are not intended to be understood as limiting the present invention. Even though only advantageous circular plates and backplates have been shown here, rectangular, square or other polygonal plates and backplates are however also conceivable. The plate, backplate and other constituent parts of a fastening system may be manufactured from any materials commonly used in aeronautical engineering, such as for example plastics, in particular fibre composite plastics, or metal, in particular corrosion-resistant steel. 
     The exemplary embodiments shown in the figures are also not intended to be regarded as being exhaustive and mutually exclusive. Where appropriate, individual features of one exemplary embodiment may by all means be combined with features of another exemplary embodiment. 
     LIST OF REFERENCE DESIGNATIONS 
     
         
         
           
               100  Fastening system 
               110  Plate 
               111  Coupling-on recess 
               112  Alignment element 
               120  Backplate 
               121  Fastening device 
               122  Recess 
               123  Cylinder wall 
               124  Wall element 
               130  Peelable shim 
               140  Alignment device 
               141  Screw 
               142  Nut 
               143  Splint 
               144  Cover 
               150  Coupling-on element 
               160  Fastening means 
               161  Peelable spacer element 
               170  Sealing ring 
               200  Clamping apparatus 
               210  Body 
               220  Fixing plate 
               300  Aircraft skin 
           
         
       
    
     While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.