PATENT ABSTRACT
A sealing device is suitable, for example, for conducting verification and testing of fluid-tightness, and includes a body supporting an end piece equipped with a gasket. The gasket presents an outer surface in which at least one area is in the form of a truncated cone. A sealing method concerns the sealing of an aircraft pipe presenting an opening arranged behind a wall, with the aid of a sealing device as described above.

PATENT DESCRIPTION
CROSS REFERENCE TO RELATED APPLICATION 
     This application is entitled to and claims the benefit of French Application No. FR 12 52364 filed Mar. 15, 2012, the disclosure of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     FIELD 
     The invention relates to a sealing device and method, namely concerning the sealing of an aircraft pipe in order for example to verify and test fluid-tightness. The field of the invention is the field of aviation and more particularly the tools used to perform control testing on an aircraft. 
     BACKGROUND 
     A specific tool, referred to herein as a sealing plug, is used in aircraft assembly lines to seal a drainage circuit of an engine pylon in a simple and rapid manner. The seal created using such a tool allows verifying and testing the fluid-tightness of the aircraft fuel system during assembly. The plug generally comprises a body presenting a first end having an end piece fitted with a gasket. During the test, the end piece closes off a pipe and the plug is held in place by an angle bracket acting on the body of the plug while attached to a protective support of the aircraft. 
     The attached  FIG. 1  illustrates a plug of the prior art. In this figure, one will recognize a pipe  2  which constitutes part of a fuel circuit in an engine pylon of an aircraft, as well as a plate  4  forming a wall. This plate  4  has a bore hole  6  which provides access to the pipe  2 , the latter extending perpendicularly to and on one side of the plate  4 . 
     On the side of the plate  4  opposite the pipe  2 , one will note the presence of an end piece  8  which supports a gasket  10 . This end piece  8  is equipped with an angle bracket  12  which enables attachment to a support (not represented) of the corresponding aircraft. 
     A problem which arises with the implementation of such a prior art plug concerns the attachment of the angle bracket. The area where the end piece and its angle bracket are to be positioned is difficult to access. Placement of the plug may therefore take time. 
     When in certain cases, as illustrated in  FIG. 1 , access to the pipe to be sealed occurs through a bore hole in a wall of the aircraft, sometimes the pipe to be sealed is not perfectly centered relative to said bore hole. An offset (illustrated in  FIG. 1 ) therefore appears between the center (or axis) of this bore hole and the center (or axis) of the pipe, which makes it difficult for the end piece and its gasket to establish the seal. One solution consists of sealing only the bore hole made in the wall of the aircraft. However, because of the surface condition of this bore hole, it is not possible to guarantee a good fluid-tight seal. It is therefore advisable to establish a seal at the pipe. 
     The problem which then arises with a plug of the prior art as described above is that it needs to be adjusted for the offset between the axis of the bore hole and that of the pipe. This is a delicate operation and may require, in addition to the plug, using industrial silicone for example to complete the seal. In addition, access is difficult and complicates the operation, similarly to the conditions for placement of the angle bracket. 
     Lastly, it is often proposed to have different engines originating from different engine manufacturers in the same type of aircraft. The diameters of the openings to be sealed may then vary and it is necessary to have a sealing tool for each of the engine devices proposed. 
     SUMMARY 
     The aim of the invention is to propose a sealing device and a sealing method which allow sealing an aircraft pipe, particularly in an engine pylon of an aircraft, without having to use additional sealing means, such as industrial silicone for example, in certain cases. 
     Another aim of the invention is for the placement of the sealing device to be rapid and ergonomic. Advantageously, the invention allows the same sealing device to be used to a certain extent for different engines in the same aircraft, or even for different types of aircraft. 
     For this purpose, the invention proposes a device for sealing a pipe of an aircraft, comprising a body supporting an end piece equipped with a gasket. 
     In the invention, the gasket comprises an outer surface having at least one area in the shape of a truncated cone. 
     The truncated-cone shape of at least a portion of the surface of the gasket allows adapting to an offset in the alignment between a pipe and a corresponding bore hole while still ensuring a good seal, for example during verification of fluid-tightness, particularly verification of fluid-tightness for an aircraft fuel tank. In addition, depending on the diameters chosen for the truncated cone, it is also possible to use the same sealing device for pipes of different diameters (within a predetermined range of diameters of course). 
     In a sealing device of the invention, the end piece is advantageously mobile relative to the body so that it can be adjusted to the environment. Furthermore, it is advantageously arranged so that the device additionally comprises elastic means acting on the end piece in a direction that tends to move the end piece away from the body. In this manner, it is possible to exert pressure on the end piece and thus complete the fluid-tightness achieved by the gasket. In addition, the sealing device thus comprises means which allow it, during insertion of the end piece, to have forces exerted on it in the direction opposite the direction of insertion. In this way, a surface provided on the body, for example an outer surface, applies this force against an external stop and thus holds the device in a sealing position that maintains the contact pressure on the end piece. 
     In a variant embodiment of a sealing device of the invention in which the end piece is mobile relative to the body, the end piece forms, for example, a distal end of a stem, said stem having a cylindrical head at its proximal end, opposite its distal end, and the body may comprise at least one tubular area and a shoulder at one of its ends arranged so that said cylindrical head can slide inside this tubular area until the shoulder is reached. This creates a piston/cylinder system in which the piston is associated with the end piece intended to create the seal and where the body of the device integrates the cylinder in which the piston slides. The travel of the piston is limited by the shoulder. In this variant of a sealing device of the invention, it is advantageously arranged so that the elastic means comprise a spring housed inside the tubular area and which applies force to the cylindrical head in the direction of the shoulder, to guarantee that pressure is exerted on the gasket. The end of the tubular body opposite the shoulder may, for example, be closed off by a stopper. 
     To facilitate maintaining a sealing device of the invention in a position in which it establishes a seal, the body can be arranged to present an outer surface on which at least one notch is created, each notch then being usable for maintaining the device. The outer surface of the body may also advantageously comprise an area for gripping it. 
     To enable a good seal, the gasket is made of rubber for example. 
     In a sealing device of the invention, the truncated-cone shape is, for example, such that its smallest diameter is less than 9 mm and its largest diameter is greater than 13 mm. 
     The invention also proposes a method for sealing an aircraft pipe presenting an opening arranged against a wall, a bore hole in said wall providing access to the pipe opening. 
     In the invention, this method comprises the following steps:
         placing at least a portion of a gasket comprising a truncated-cone shaped area into the pipe opening, through the bore hole in the wall, said gasket being located at one end of a sealing device,   holding the gasket in place in the opening by locking the sealing device against a support that is fixed relative to the pipe.       

     This involves a method for implementing a sealing device as described above. It can be used in particular for verifying and testing fluid-tightness. 
     For such a sealing method, one of the variants of the sealing device described above can be used. Thus, in the method of the invention, the sealing device comprises a tubular body, the gasket is assembled onto an end piece that is mobile relative to the tubular body, the tubular body comprises elastic means acting on the end piece in a direction that tends to move the gasket away from the tubular body, forces are applied to the elastic means after the gasket is placed in the opening, and the tubular body presents an outer face with at least one stop that is able to cooperate with the fixed support such that the force exerted on the elastic means is maintained and contributes to retaining the tubular body against the fixed support. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features and advantages of the invention will be more readily apparent from the following description, with reference to the attached schematic drawings in which: 
         FIG. 1  is a schematic view of a sealing device of the prior art in its environment, 
         FIG. 2  shows a perspective view of a sealing device according to the invention, 
         FIG. 3  is a schematic cross-sectional view which is enlarged in comparison to  FIG. 2 , showing a variant of a sealing device of the invention when it is in service, and 
         FIG. 4  is an exploded perspective view of the sealing device of the previous figure, further enlarged in comparison to  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  represents a sealing device of the prior art. This device and its environment were already described in the introduction.  FIG. 3  shows a sealing device of the invention in an environment similar to what was described with reference to  FIG. 1 . The references used in  FIG. 1  are therefore used again to denote similar elements of the environment in  FIG. 3 . Thus in  FIG. 3  we find a plate  4  containing a bore hole  6 . A pipe  2  of an aircraft fuel supply circuit runs on one side of and perpendicular to the plate  4 . This pipe  2  is normally located facing the bore hole  6  and centered relative to it. However, within design limits it may still occur that the position of the pipe  2  is offset relative to the bore hole  6 . 
       FIG. 2  shows, at a reduced scale in comparison to  FIG. 3 , a sealing device according to the invention. The structures of the sealing devices of  FIGS. 2 and 3  are very similar, and the differences between these structures will be discussed below. Each of these sealing devices comprises a body  20  as well as an end piece  22  equipped with a gasket  24 . In  FIG. 2 , one will also note that the sealing device is equipped with an identification label  26  which is not involved in establishing the seal for the pipe  2 . 
       FIG. 4  shows the different parts of the sealing device illustrated in  FIG. 3 . 
     Visible in  FIG. 4  are the body  20 , the end piece  22 , and its gasket  24 . Also represented in  FIG. 4  are a stopper  28 , a spring  30 , a piston  32 , and a stop pin  34 . 
     Although conventionally a sealing device is oriented obliquely when it is used to seal a pipe, it is assumed in the following description that, as represented in  FIGS. 2 to 4 , the sealing device is arranged vertically, with the gasket  24  being located at the bottom. 
     The body  20  is in the form of a circular cylindrical tube. Therefore the interior of the body  20  defines a housing. This housing is of a constant diameter for substantially the entire length of the body  20 . Only the lower portion of the body  20  has a reduced diameter, thus forming a shoulder  36 . 
     The outer surface of the body  20  is also generally circular and cylindrical. It is of a constant diameter for the major portion of its length and thus forms a surface the user can grip. One will note, however, that the lower portion of the body  20  comprises annular ribs spaced regularly apart, forming notches  38 . 
       FIG. 3  also shows the presence of two transverse bore holes in the upper portion of the body  20 . As illustrated in this figure, a first bore hole  37  is intended to receive the stop pin  34 . As a variant ( FIG. 2 ), this stop pin could be eliminated; the stopper  28  is then glued in the body  20 , or forms a single part with it. Aside from the absence of the stop pin and the adaptation of the body  20  and the stopper  28 , the sealing device of  FIG. 2  has the same elements as those described with reference to  FIGS. 3 and 4 , in a similar arrangement. 
     The second transverse bore hole  39  can be used to allow the passage of a tie which connects the identification label  26  to the sealing device. 
     The stopper  28  has a circular cylindrical shape. Its outer diameter is adapted to the inside diameter of the body  20  (in its upper part). The stopper  28  also has ( FIG. 3 ) transverse bore holes  37 ′ and  39 ′ corresponding to the transverse bore holes of the body  20  with which it is intended to cooperate. Thus, a transverse bore hole  37 ′ of the stopper  28  receives the stop pin  34  as illustrated in  FIG. 3  while the other transverse bore hole  39 ′ allows the passage of a tie which attaches the identification label  26 . 
     The piston  32  has a cylindrical head  40  and a stem  42 . The cylindrical head  40  has an outside diameter corresponding to the inside diameter of the body  20  such that the piston  32 , and in particular its cylindrical head  40 , can slide inside the body  20 , within the large inside diameter portion of the body. 
     The stem  42  of the piston  32  has an outside diameter which allows it to slide inside the reduced inside diameter portion of the body  20 . The downward travel of the piston  32  is limited by the shoulder  36 . 
     As one can see in  FIG. 3 , the lower portion of the stem  42  of the piston  32  has a longitudinal bore hole  44  allowing it to receive the end piece  22 . An internal threading  45  created in the stem  42 , visible in  FIG. 4 , can accept a headless set screw (not represented) to maintain the end piece  22  in the longitudinal bore hole  44 . This attachment facilitates the assembly/disassembly of the end piece  22 , which can thus easily be changed. The end piece  22  is in fact the only part of the sealing device which can wear out. In addition, it may be advantageous to be able to fit end pieces of different sizes and/or shapes onto a same sealing device in order to be able to adapt to a larger number of environments. 
     The end piece  22  is formed of a shaft  46  and the gasket  24 . The shaft  46  is a circular cylindrical shaft having substantially at its center a radially extending flange  48 . In the chosen orientation, the portion of the shaft  46  which extends above the flange  48  is intended to cooperate with the stem  42  and the piston  32 . This upper portion of the shaft  46  fits into the longitudinal bore hole  44  of said stem  42 . The lower portion of the shaft  46  is over molded with rubber to form the gasket  24 . 
     The gasket  24  is in the form of a truncated cone starting from the flange  48 . The large diameter of the corresponding cone coincides with the diameter of the flange  48 . The diameter of the cone shrinks as one moves further away from the flange  48 . As a purely illustrative and in no way limiting example, one can for example have a gasket  24  having a truncated-cone portion in which the base by the flange  48  has a diameter of 15 mm while the diameter of the tip of the truncated cone is 9 mm. The height of the truncated cone is, for example, between 15 and 20 mm. 
     The distal end of the gasket  24 , meaning the end opposite the flange  48 , is for example in the form of a domed cap  50 . This cap may be spherical or may be a truncated cone, the body of the cap  50  then presenting an angle at the tip that is greater than the angle at the tip of the truncated cone of the gasket  24  described above. 
     The spring  30  is a coil spring which is placed inside the body  20  between the stopper  28  and the cylindrical head  40  of the piston  32 . This coil spring has an outside diameter that is compatible with the inside diameter of the housing inside the body  20  in which it is placed. This is, for example, a compression spring. It acts in opposition to an upward motion of the cylindrical head  40  of the piston  32 . In other words, the spring  30  pushes the piston  32  towards the outside of the body  20 . 
       FIG. 3  shows all the parts of  FIG. 4  in the assembled position, sealing the pipe  2 . In the assembled position, the stopper  28  closes off the upper end of the body to close off the housing within the body  20 . The cylindrical head  40  closes off the lower end of the housing within the body  20 . The spring  30  presses against the stopper  28  and pushes the cylindrical head  40  toward the shoulder  36 . 
     In the assembled position of  FIG. 3 , the gasket  24  closes off the end of the pipe  2  located next to the bore hole  6  in the plate  4 . The spring  30  applies sufficient pressure against the end piece  22 , and therefore against the gasket  24 , to guarantee a good fluid-tight seal. This pressure is for example between 0.3 and 0.4 bar (numeric data provided for illustrative purposes only). 
     A notch  38  is used to hold the sealing device in its sealing position on the pipe  2 . This notch  38  is intended to cooperate in  FIG. 3  with an angle bracket  52  attached to a support that is an integral part of the structure of an engine pylon (not represented) of an aircraft. However, in a variant embodiment, a notch  38  could cooperate with another structural element in order to retain the sealing device. 
     The presence of several notches  38  allows the same sealing device to adapt to different structural environments and/or to adjust the pressure exerted by the spring  30  on the end piece  22 . 
     The sealing device described above is easy to use. It is sufficient to position the end piece so it presses against the hole to be sealed while holding the sealing device by its body, then push on it to compress the spring and lock it in position by causing the angle bracket to enter one of the notches created on the outer surface of the body of the sealing device. The body, and therefore the sealing device, is then held in place by the compression of the spring  30 . The sealing device can thus be put in place with one hand, which facilitates assembly even in limited spaces. 
     Disassembly of the sealing device is also easy. By pressing on the body of the sealing device and moving it away from the angle bracket, the sealing device is released and can simply be removed. 
     The conical shape of the gasket offers two advantages. It ensures a good seal even in the case where the bore hole that is supposed to be aligned with the pipe is misaligned, and it allows adapting to different pipe diameters. 
     One will also note that the sealing device proposed by the invention is simple in structure and can therefore be made inexpensively. 
     The invention is not limited to the preferred embodiments described above as non-limiting examples. It also relates to the variant embodiments that are within reach of a person skilled in the art, within the context of the following claims.