Abstract:
A fluid conduit for a gas turbine engine includes a first fluid conduit attachable to a second fluid conduit and securable together with a lockable connector. The connector includes a first portion including external threads and a second portion receiving the first portion and including internal threads mating to the external threads of the first portion. The internal threads include lead threads defining a first thread interface with the external threads for starting attachment of the first portion to the second portion and locking threads defining a second thread interface for locking the first portion to the second portion.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/774,771 filed Mar. 8, 2013. 
     
    
     BACKGROUND 
       [0002]    A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section. 
         [0003]    Fluid conduits and tubing are routed throughout the gas turbine engine to deliver fuel, lubricant, hydraulic fluid, and other fluids where needed. Each conduit is terminated or connected by way of connectors that extend through support structures as well as specific sections. Each of the connectors requires a locking system to maintain the connection. Locking wires are sometimes utilized to lock a connector in place. However, locking wires have disadvantages and may not be utilized in some locations within the gas turbine engine. 
         [0004]    Accordingly, it is desirable to design and develop connectors that provide locking features without the use of a locking wire. 
       SUMMARY 
       [0005]    A fluid connection fitting according to an exemplary embodiment of this disclosure, among other possible things includes a first portion including external threads, and a second portion receiving the first portion and including internal threads for mating to the external threads. The internal threads include lead threads defining a first thread interface with the external threads for starting attachment of the first portion to the second portion and locking threads defining a second thread interface for locking the first portion to the second portion. 
         [0006]    In a further embodiment of the foregoing fluid connection, the locking threads are non-concentric about a central axis of the second portion and the lead threads are concentric about the central axis. 
         [0007]    In a further embodiment of any of the foregoing fluid connection fittings, the connector includes a first thickness disposed at the lead threads and a second thickness disposed at the locking threads, with the second thickness less than the first thickness for providing for deformation of an outer diameter proximate to the locking threads. 
         [0008]    In a further embodiment of any of the foregoing fluid connection fittings, the first thickness corresponds with a first diameter and the second thickness corresponds with a second diameter less than the first diameter. 
         [0009]    In a further embodiment of any of the foregoing fluid connection fittings, includes a relief disposed between the lead threads and the locking threads. The relief does not include threads. 
         [0010]    In a further embodiment of any of the foregoing fluid connection fittings, the locking threads define an interference fit with the external threads of the first portion. 
         [0011]    In a further embodiment of any of the foregoing fluid connection fittings, the lead threads and the locking threads include a first inner diameter and the relief includes a second inner diameter greater than the first diameter. 
         [0012]    In a further embodiment of any of the foregoing fluid connection fittings, the relief includes an axial length greater than at least two of the lead threads. 
         [0013]    A fluid conduit for a gas turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes a first fluid conduit attachable to a second fluid conduit along an axis, and a connector for securing the first fluid conduit to the second fluid conduit. The connector includes a first portion including external threads. A second portion receives the first portion and includes internal threads for mating to the external threads. The internal threads include lead threads defining a first thread interface with the external threads for starting attachment of the first portion to the second portion and locking threads defining a second thread interface for locking the first portion to the second portion. 
         [0014]    In a further embodiment of the foregoing fluid conduit, the locking threads are non-concentric about a central axis of the second portion and the lead threads are concentric about the central axis. 
         [0015]    In a further embodiment of any of the foregoing fluid conduit fittings, the connector includes a first thickness disposed at the lead threads and a second thickness disposed at the locking threads, with the second thickness less than the first thickness for providing for deformation of an outer diameter proximate to the locking threads. 
         [0016]    In a further embodiment of any of the foregoing fluid conduit fittings, the first thickness corresponds with a first diameter and the second thickness corresponds with a second diameter less than the first diameter. 
         [0017]    In a further embodiment of any of the foregoing fluid conduit fittings, includes a relief disposed between the lead threads and the locking threads. The relief does not include threads. 
         [0018]    In a further embodiment of any of the foregoing fluid conduit fittings, the locking threads define an interference fit with the external threads of the first portion. 
         [0019]    In a further embodiment of any of the foregoing fluid conduit fittings, the lead threads and the locking threads include a first inner diameter and the relief includes a second inner diameter greater than the first diameter. 
         [0020]    A method of locking a fluid fitting according to an exemplary embodiment of this disclosure, among other possible things includes defining a first coupling portion including external threads, defining a second coupling portion receiving the first portion and including internal threads for mating to the external threads, the internal threads include lead threads defining a first thread interface with the external threads for starting attachment of the first portion to the second portion and locking threads defining a second thread interface for locking the first portion to the second portion, aligning the first coupling portion with the second coupling portion by engaging the externals threads the lead in threads, and locking the first coupling portion to the second coupling portion by engaging the external threads with the locking threads of the second coupling portion. 
         [0021]    In a further embodiment of the foregoing method, includes generating a locking fit by deforming the locking threads to be non-concentric about a central axis of the second portion and maintaining the lead threads as concentric about the central axis. 
         [0022]    In a further embodiment of any of the foregoing methods, includes generating a locking fit by providing the locking threads with an interference fit relative to the external threads. 
         [0023]    In a further embodiment of any of the foregoing methods, includes providing a relief disposed between the lead threads and the locking threads with the relief not including threads. 
         [0024]    Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
         [0025]    These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a schematic view of an example gas turbine engine. 
           [0027]      FIG. 2A  is a cross-section of an example fluid connection fitting. 
           [0028]      FIG. 2B  is a sectional view of the example fluid connection fitting. 
           [0029]      FIG. 3A  is cross-section of another example fluid connection fitting. 
           [0030]      FIG. 3B  is a cross-section of the example connection fitting shown of  FIG. 3A . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  schematically illustrates an example gas turbine engine  20  that includes a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmenter section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B while the compressor section  24  draws air in along a core flow path C where air is compressed and communicated to a combustor section  26 . In the combustor section  26 , air is mixed with fuel and ignited to generate a high pressure exhaust gas stream that expands through the turbine section  28  where energy is extracted and utilized to drive the fan section  22  and the compressor section  24 . 
         [0032]    The example gas turbine engine  20  includes many couplings and fittings for routing fluid to various components. Each of the fluid connection fittings are required to be coupled in a manner that it prevents leakage and assures that the fittings remain connected during engine operation. Many of the fluid couplings are required to have a locking system, such as for critical lubrication, fuel, and air fittings. Previous locking fittings utilized a lock wire along with other additional devices to maintain the desired fluid coupling during operation. 
         [0033]    In some applications, it is desired to provide a fluid connection fitting that provides locking without the use of external devices such as locking wire. In such devices, it is required that the fluid coupling maintains integrity and maintains connection throughout engine operation. 
         [0034]    Referring to  FIGS. 2A and 2B , an example fluid connection assembly  30  includes a first connector portion  32  that is coupled to a second connection portion  34  along a connector axis  56 . The first connector portion  32  includes external threads  36  that are received within the second connector portion  34 . The second connector portion  34  comprises a nut that threads onto the external threads  36  of the first connector portion  32 . A first fluid conduit  52  is attached and corresponds with the first connector portion  32 . A second fluid conduit  54  corresponds and is attached to the second connector portion  34 . 
         [0035]    The second connector portion  34  includes first threads  40  and second threads  42  that comprise a thread assembly  38 . The example thread assembly  38  is separated by a relief portion  44 . The relief portion  44  does not include threads and is of a width that is equal to at least two or three of the example threads provided in the threads  40  and  42 . 
         [0036]    The first threads  40  comprises a plurality of threads that provide a normal standard fit with the external threads  36 . The second set of threads  42  that are separated by the relief  44  from the standard threads  40  comprises an interference fit. The interference fit of the threads  42  provides for the locking of the first connector portion  32  into the second connector portion  34 . 
         [0037]    The first threads  40  allow for hand tightening of the first connector portion  32  to the second connector portion  34 . Once the first connector portion  32  is threadingly engaged to the second connector portion  34 , a tool can be utilized to further fasten the threads  36  into the interference threads provided in the second threads  42 . 
         [0038]    The relief  44  includes a diameter  48  that is larger than the diameter  46  of the threaded portions  38 . The relief  44  eliminates potential mismatch between the standard threads provided in the first threads  40  and the interference threads provided in the second portion  32 . 
         [0039]    The threaded assembly  38  is formed by first forming the interference threads from the end of the second connector portion  34  through to the second threads  42 . The relief  44  is then formed by a machine cutting tool or other known machining method and standard threads are rethreaded in the first threads  40  to allow for hand threading during assembly. 
         [0040]    Accordingly, once the first portion  32  is fully engaged with the interference threads  42 , the first connector portion  32  is locked to the second portion  34  such that the connection is maintained and provides the desired locking between connector portions  32 ,  34 . 
         [0041]    Referring to  FIGS. 3A and 3B , a second connector assembly  60  is disclosed and includes a first connector portion  62  that is coupled to a second connector portion  64 . The first connector portion  62  includes external threads  66  that are of a standard formulation and that are threadingly engaged into interior threads  72  formed on the second fluid connector portion  64 . 
         [0042]    The second connector portion  64  includes a varying thickness from the forward end of the connector to an aft end. An area having a reduced thickness  78  is disposed between areas having a greater thickness  76  disposed at a forward end  74  and an aft end  75  of the connector portion  64 . The internal threads  72  defined within the connector portion  64  include an initial lead-in portion  68  that are of a normal fit that provides for the initial engagement between the first connector portion  62  and the second connector portion  64 . The lead-in portion  68  provides a normal fit that can be engaged by hand. 
         [0043]    Once the first connector portion  62  is initially engaged into the initial threads  68 , a tool is utilized to continue tightening the first connector portion  62  and continue threading into the interference thread portion  70  of the second connector portion  64 . Once the first connector portion  62  is fully engaged and threaded into the second connector portion  64 , a deforming force  82  is applied to the area of the reduced thickness  78 . The forces applied, as is indicated by arrows  82 , deforms the areas with the smaller thickness  78  to further maintain and lock the first connector portion  62  within the second connector portion  64 . 
         [0044]    To facilitate the deformation of a specific area of the second connector portion  64 , the thickness is varied axially. An initial thickness is provided at the lead-in threads  68 . This initial thickness indicated at  76  is at the initial end  74 . The initial thickness  74  at the leading end on the connector  64  is followed by the area of reduced thickness  78 . The area of reduced thickness  78  is followed by an area having a greater thickness  80  that is aft of the reduced thickness  78  and provides for receiving the fluid conduit  54 . The reduced thickness  78  includes an outer diameter  86  that is less than the outer diameter  84  of the thicker portions  76  and  80 . 
         [0045]    During assembly, the first connector portion  62  is initially threaded into the standard thread  68 . This threading process can be done by hand as no interference is defined at this interface. A tool is then utilized to continue tightening the first connector portion  62  into the second connector portion  64  and into the interference thread  70 . Once the first connector  62  is fully threadingly engaged into the interference thread  70 , a deforming force  82  is applied to the area of reduced thickness  78 . This deforming force, indicated by arrows  82 , introduces an out-of-round condition ( FIG. 3   b ) at the interface between the first connector  62  and the second connector  64  that provides for locking engagement and prevents loosening of the first connector  62  from the second connector  64 . 
         [0046]    Accordingly, each of the disclosed interference threaded connector fittings provide for the locking of a fluid coupling without the use of additional locking members. 
         [0047]    Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure.