Abstract:
The present invention relates to a pipe repair method using a shape-memory alloy that can correspond to pipes of any shape and dimension. The pipe repair method comprises the steps of applying a seal member to a damaged portion of the pipe so as to cover the damaged portion and winding a plate made from a shape-memory alloy that contracts to a memorized shape around a periphery of the pipe so as to cover the seal portion when heated.

Description:
This application is a continuation of application Ser. No. 07/813,641, filed Dec. 27, 1991, which application is entirely incorporated herein by reference, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a pipe repair method using a shape-memory alloy when repairs are made to the pipes of aircraft and the like, and to a pipe repair member using this method. 
     In general, when damage has occurred to pipes, the pipe having the damaged portion is replaced or the damaged portion of the pipe is cut out and a new pipe is connected to the remaining portion. However, when many pipes are closely packed as in the case of aircraft and the like, it is extremely difficult to exchange and reconnect the pipes. In addition, when the pipes are exchanged, it is necessary to make exactly the same shape as the old pipe. And when connectors are used, it is necessary to use special processing to the end portions of the pipe. 
     In order to overcome such a situation as above, various pipe repair techniques have been proposed as shown in FIG. 9. Japanese Patent Application Laid-Open Number 195198/1988 discloses a method where a pipe repair member includes a pair of two semi-cylindrical portions made from a shape-memory alloy. An edge portion along one of the semi-cylindrical portions 1 has a catch portion 2, and the edge portion along the other of the semi-cylindrical portions 3 has a groove portion 4. 
     In addition, as shown in FIG. 10, Japanese Patent Application Laid-Open Number 168005/1990 discloses a method for punching process to stoppers 6,7 at each end of a band-shaped plate 5 made from the shape-memory alloy. 
     However, according to Japanese Patent Application Laid-Open Number 195198/1988, a straight portion of the pipe can be effectively repaired but there is the problem that a curved portion can not be repaired. In addition, with either the invention or the prior art described above, many types of repair parts have to be prepared for each type of the pipes having various dimensions. Thus, it is very difficult to have many repair members corresponding to respective shapes and dimensions. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a pipe repair method using a shape-memory alloy and a pipe repair member that can correspond to pipes with any shapes and dimensions. 
     In order to achieve the object described above, the pipe repair method using a shape-memory alloy according to the present invention comprises the steps of covering a seal member to a damaged portion of a pipe, winding a thin band-shaped plate made from a shape-memory alloy, contracting to a memorized shape around a periphery of the pipe so as to cover the seal member when heated, clamping both ends of the thin band-shaped plate with a clamp, and heating the thin band-shaped plate to a temperature above a shape transformation temperature. 
     In addition, the pipe repair member according to the present invention comprises a seal member that covers a damaged portion of a pipe or the periphery of the pipe, a thin band-shaped plate made from a shape-memory alloy and being wound around an outer periphery of the pipe so as to cover the seal member, and a clamp for clamping both ends of the this band-shaped plate. 
     By the adoption of the method described above, when the thin band-shaped plate is heated to above the transformation temperature, the thin band-shaped plate contracts to a shape to closely contact with the outer periphery of the pipe. As a result, the outer periphery closely contacts with the thin band-shaped plate so as to seal the damaged portion. 
     Here, when the thin band-shaped plate is wound around the pipe and fixed to closely contact with the outer peripheral surface of the pipe, and when the sealing member closely contacts with both the outer peripheral surface of the pipe and the thin band-shaped plate, it is possible to correspond to any shapes or dimensions. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIGS. 1A to 1F are sequential views of a portion of a pipe to be repaired according to a first embodiment of the present invention; 
     FIG. 2 is a sectional view showing one example of a clamp fitting; 
     FIGS. 3A to 3C are sequential views of a portion of a pipe to be repaired according to a second embodiment of the present invention; 
     FIGS. 4A to 4D are sequential views of a portion of a pipe to be repaired according to a third embodiment of the present invention; 
     FIG. 5 is a view showing another example of a sealing member; 
     FIG. 6 is a perspective view showing one example of a band clamp according to the present invention; 
     FIG. 7 is a partial sectional view showing the band clamp shown in FIG. 6; 
     FIG. 8 is a perspective view showing another example of the band clamp according to the present invention; 
     FIG. 9 is a perspective view showing an example of a portion repaired by a conventional method; and 
     FIG. 10 is a perspective view showing another example of a portion repaired by a conventional method. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will become understood from the following detailed description referring to the accompanying drawings. 
     In FIG. 1 describing a first embodiment of the present invention, FIG. 1A shows a damaged portion 10 such as a crack in the pipe 9 that has to be repaired. Then, as shown in FIG. 1B, a sealing member 11 covers the damaged portion 10 for repair. The sealing member 11 can desirably be a chosen from an elastomer (a polysulfide rubber) or thermo-hardening epoxy resin that can be fluidified by heating, and selected in accordance with the fluid that flows inside the pipe. 
     After this, as shown in FIG. 1C, a thin band-shaped plate 12 made from a shape-memory alloy that contracts to a memorized shape when heated is wound around the outer periphery of the pipe 9 so as to cover the sealing member 11. Moreover, as shown in FIG. 2, a clamp 13 of the thin band-shaped plate 12 has teeth 15 on opposing surfaces of a clamping portion 14, and the teeth 15 overlap both end portions of the thin band-shaped plate 12 and sandwich the pipe 9. As shown in FIG. 1C and FIG. 2, the end portions of the thin plate pass through a through-hole in the clamp 13 which is defined by the opposing surfaces 15 of clamping portions 14. So as to ensure tight clamping of the thin band-shaped plate 12, the thin band-shaped plate 12 desirably has knurling on the surfaces that oppose the clamp 13, so that the teeth 15 bite into the thin band-shaped plate 12 more easily. 
     Once both end portions of the thin band-shaped plate 12 are clamped by the clamp 13, then as shown in FIG. 1D, the unnecessary portions of the thin band-shaped plate 12 are cut off in the vicinity of the clamp 13. After cutting, as shown by the arrow in FIG. 1E, a heater is used to heat the thin band-shaped plate 12 that has been wound around the outer periphery of the pipe 9 so as to cover the sealing member 11 to above the transformation temperature. FIG. 1F shows a front view of the portion of the pipe 9 to be repaired shown in FIG. 1D. 
     When heating is done, the thin band-shaped plate 12 contracts to return to its original stored shape, and the sealing member 11 also contacts with the outer periphery of the pipe 9. At this time, the sealing member 11 is fluidified by the heat and flows to fill between the thin band-shaped plate 12 and the outer periphery of the pipe 9 and the damaged portion 10. The thin band-shaped plate 12 therefore closely and definitely contacts with the outer periphery of the pipe 9 and the damaged portion 10 of the pipe 9 is sealed. Moreover, when the damaged portion 10 is a crack or the like, any further development of the opening is prohibited by tightening of the thin band-shaped plate 12 around the outer periphery of the pipe 9. 
     Here, the band-shaped thin plate member 12 can change to any shape and so it can be wound around a pipe of any shape or dimension. 
     The following description is a second embodiment of the present invention. As shown in FIG. 3A for the case when there is a damaged portion 17 in a curved portion of a pipe 16, a sealing member 11 covers the damaged portion 17 and its periphery as shown in FIG. 3B, and a thin band-shaped plate 12 is wound around the outer periphery of the pipe 16 so as to cover the sealing member 11. Then, after the clamp (not shown) has engaged both ends of the thin band-shaped plate 12, the plate is heated to above its transformation temperature as shown by the arrow in FIG. 3C, and the damaged portion 17 in a curved portion of the pipe 16 is sealed and repaired. 
     In addition, the present invention can also be applied to the connection of the pipes and not just for the repair. 
     With respect to the connection, the following description is a third embodiment of the present invention. When the connecting portions of pipes 18, 18 are connected as shown in FIG. 4A and FIG. 4B, connection portions 18a are covered with the sealing member 11. Then, as shown in FIG. 4C, the thin band-shaped plate 12 is wound around the connecting portion so as to cover the sealing member 11 and both of the ends are clamped by the clamp (not shown). Then, as shown by the arrow in FIG. 4D, the thin band-shaped plate 12 is heated to above its transformation temperature and tightened around the connecting portions of the pipes 18, 18 so as to connect the pipes 18, 18. 
     In this manner, the present invention can be applied to the pipes with any shapes or dimensions since the thin band-shaped plate 12 covers the damaged portion of the pipe, and can change its shape freely and can have its length adjusted by cutting. 
     In addition, the present invention is not limited to the embodiments that have been described above. An O-ring 19 or the like shown in FIG. 5 can be used as the sealing member, and the O-ring 19 covers the periphery of a damaged portion 20. 
     Also, the thin band-shaped plate can be suitably chosen to have a large or small width in accordance with usage, and can be wound two or three times. 
     Furthermore, as shown in FIG. 6 and FIG. 7, a thin band-shaped plate 21 and a clamp 22 can be a single unit. 
     Also, as shown in FIG. 8, a thin band-shaped plate 23 and a sealing member 24 can be used as a single unit. 
     According to the present invention, the heating of the thin band-shaped plate to above the transformation temperature causes to contract and closely to contact with an outer periphery of the pipe, so that the sealing member closely contacts with the thin band-shaped plate, the outer peripheral surface of the pipe and the damaged portion of the pipe. Therefore, the damaged portion of the pipe is sealed. 
     Here, the thin band-shaped plate is wound and fixed around the pipe and closely contacts with the outer peripheral surface of the pipe and the sealing member fills between the outer peripheral surface of the pipe and the thin band-shaped plate. And the thin band-shaped plate can fit any shapes or dimensions of the pipes. 
     While the presently preferred embodiments of the present invention have been shown and described, it is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.