Abstract:
A seal assembly includes a first ferrule that surrounds the lead and a second ferrule that surrounds the lead.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to a seal assembly and, more particularly, to a hard mechanical seal for a tubular lead. 
         [0002]    Gas turbine engines are typically instrumented when under development. An instrumentation probe to measure, for example temperature or pressure, is connected through a hard lead with a close mechanical fit to an engine case structure. When such an instrumentation probe is utilized in conjunction with a hostile environment such as, for example, a compressor or turbine section of the gas turbine engine, the close mechanical fit is provided by a potting material. Although effective, the potting material may tend to release over time. 
       SUMMARY 
       [0003]    A seal assembly according to one disclosed non-limiting embodiment of the present disclosure includes a lead, a first ferrule that surrounds said lead, and a second ferrule that surrounds said lead. 
         [0004]    In a further embodiment of the foregoing embodiment, the first ferrule is opposed to said second ferrule. 
         [0005]    In a further embodiment of any of the foregoing embodiments, the first ferrule and said second ferrule include opposed convex surfaces. 
         [0006]    In a further embodiment of any of the foregoing embodiments, the first ferrule and said second ferrule include opposed ramped surfaces. 
         [0007]    In a further embodiment of any of the foregoing embodiments, the first ferrule is brazed to said lead. 
         [0008]    In a further embodiment of any of the foregoing embodiments, the second ferrule includes a nut and an adapter with a threaded interface therebetween. In the alternative or additionally thereto, in the foregoing embodiment the adapter is brazed to the lead. In the alternative or additionally thereto, in the foregoing embodiment the nut includes a convex surface. In the alternative or additionally thereto, in the foregoing embodiment the nut is opposed to said first ferrule. 
         [0009]    An assembly according to another disclosed non-limiting embodiment of the present disclosure includes a structure that includes an aperture along an axis, said aperture includes an inner counterbore and an outer counterbore separated by an intermediate section, a lead that extends through said aperture along said axis, an inner ferrule that surrounds said lead and interfaces with said inner counterbore, and an outer ferrule that surrounds said lead and interfaces with said outer counterbore. 
         [0010]    In a further embodiment of the foregoing embodiment, the assembly includes a potting material within said intermediate section. 
         [0011]    In a further embodiment of any of the foregoing embodiments, the inner ferrule and said outer ferrule includes a convex surface that abuts an inner intermediate interface surface between said inner counterbore and said intermediate section and an outer intermediate interface surface between said outer counterbore and said intermediate section. 
         [0012]    In a further embodiment of any of the foregoing embodiments, the inner ferrule is brazed to said lead. 
         [0013]    In a further embodiment of any of the foregoing embodiments, the second ferrule includes a nut and an adapter with a threaded interface therebetween. In the alternative or additionally thereto, in the foregoing embodiment the adapter is brazed to the lead 
         [0014]    A gas turbine engine according to another disclosed non-limiting embodiment of the present disclosure includes a case that includes an aperture along an axis, said aperture includes two (2) opposed counterbore separated by an intermediate section. 
         [0015]    In a further embodiment of the foregoing embodiment, each counterbore defines a first diameter and said intermediate section defines a second diameter, said first diameter greater than said second diameter. 
         [0016]    In a further embodiment of any of the foregoing embodiments, the gas turbine engine includes an interface that spans each counterbore and said intermediate section. 
         [0017]    In a further embodiment of any of the foregoing embodiments, the axis is angled with respect to an outer surface of said case. 
         [0018]    In a further embodiment of any of the foregoing embodiments, the gas turbine engine includes a lead that extends through said aperture along said axis, an inner ferrule that surrounds said lead and interfaces with said inner counterbore, and an outer ferrule that surrounds said lead and interfaces with said outer counterbore. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0020]      FIG. 1  is a schematic view of an example gas turbine engine; 
           [0021]      FIG. 2  is an expanded cross-sectional view of a seal assembly according to one disclosed non-limiting embodiment; 
           [0022]      FIG. 3  is an expanded cross-sectional view an aperture to receive a seal assembly; 
           [0023]      FIG. 4  is an expanded cross-sectional view of the seal assembly of  FIG. 2  during assembly; 
           [0024]      FIG. 5  is an expanded cross-sectional view of the seal assembly of  FIG. 2  during assembly; 
           [0025]      FIG. 6  is an expanded cross-sectional view of the seal assembly of  FIG. 2  during assembly; 
           [0026]      FIG. 7  is an expanded cross-sectional view of a seal assembly according to another disclosed non-limiting embodiment; 
           [0027]      FIG. 8  is an expanded cross-sectional view of a seal assembly according to another disclosed non-limiting embodiment; 
           [0028]      FIG. 9  is an expanded and isometric view of the seal assembly of  FIG. 8 ; 
       
    
    
     DETAILED DESCRIPTION 
       [0029]      FIG. 1  schematically illustrates a gas turbine engine  10  with a case structure  12 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be appreciated that the concepts described herein are not limited to use with high-bypass turbofans as the teachings may be applied to other types of turbine engines such as an augmented turbofan, turboshaft, geared architecture, turbojet and industrial gas turbine engine. 
         [0030]    With reference to  FIG. 2 , a seal assembly  14  seals a lead  16  that passes between an interior  18  and an exterior  20 . That is, the seal assembly  14  provides a seal for the lead  16  though the case structure  12 . In the disclosed non-limiting embodiment, the lead  16  is a hollow metal conduit through which wires, airflow or other communicant may be sealed and protected, the lead  16  may be a flexible metal braided hose or solid metal tube which is relatively flexible. Furthermore, although depicted as a lead that passes through the case of a gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use only therewith. For example, the teachings disclosed herein may be applied to other structural interfaces such as, for example, conduits that pass airflow therethrough. 
         [0031]    With reference to  FIG. 3 , the case structure  12  defines an aperture  24  along an axis W which may be angled with respect an outer surface  26  of the case structure  12 . The aperture  24  generally includes two (2) opposed counterbore  28 ,  30  separated by an intermediate section  32 . Each counterbore  28 ,  30  defines a diameter  34 ,  36  that is greater than a diameter  38  defined by the intermediate section  32 . An intermediate interface surface  40 ,  42  blends each counterbore  28 ,  30  with the intermediate section  32  to receive a respective inner and outer ferrule  44 ,  46  ( FIG. 2 ). The intermediate interface surfaces  40 ,  42  may be, for example, ramped, concave or otherwise matched to an outer surface of the respective ferrule  44 ,  46 . 
         [0032]    With reference to  FIG. 4 , assembly of the lead  16  into the structure  12  is initiated with the inner ferrule  44  brazed or otherwise attached to the lead  16 . The lead  16  is then routed through the aperture  24  and pulled tight so the ferrule  44  seats on the intermediate interface surface  40  and extends at least partially into the intermediate section  32 . 
         [0033]    The intermediate section  32  is then at least partially filled with high-temp, e.g., greater than 2000 F (1093 C) potting material  48  and allowed to cure. Then, while the lead  16  is held in tension, the outer ferrule  46  is pushed into the counterbore  30  opposed to said inner ferrule  44  until seated on the intermediate interface surface  42 . The outer ferrule  46  is then brazed or otherwise attached to the lead ( FIG. 5 ). 
         [0034]    With reference to  FIG. 6 , the counterbore  30  is then filled with potting material  48 . The lead  16  may additionally be restrained with respect to the outer surface  26  of the case structure  12  with a strap  50  or other retainer. 
         [0035]    With reference to  FIG. 7 , another disclosed non-limiting embodiment provides a convex surface  52  on each ferrule  44 ,  46  with a matched concave surface  54  at each intermediate interface surface  40 ,  42 . The convex surface  52  on each ferrule  44 ,  46  and the concave surface  54  of the intermediate interface surface  40 ,  42  increases the contact area and thereby facilitates a seal therebetween. 
         [0036]    With reference to  FIG. 8 , another disclosed non-limiting embodiment includes an outer ferrule  46  with a nut  56  and an adapter  58  with a threaded interface  60  therebetween. In this disclosed non-limiting embodiment, the inner ferrule  44  may be as described above. 
         [0037]    The adapter  58  is brazed to the lead  16  with the nut  56  threaded into the adapter  58 . The nut  56  is then threaded out of the adapter  58  to force the nut  56  into the counterbore  30  until seated on the interface  42 . The nut  56  and the adapter  58  may include various tool interfaces  62 ,  64  (illustrated schematically) to facilitate rotation therebetween. For example the tool interfaces  62 ,  64  may include flats to receive a wrench; holes  66  ( FIG. 9 ) to receive a dowel, knurling to receive a band-wrench or other such tool interface. 
         [0038]    The use of two (2) opposed ferrules contains the potting material through the thermal cycles of engine operation. The matched interface provides a mechanical seal in addition to the potting material seal. The hardware disclosed herein is readily usable across engine programs and instrumentation types as well as in production engines for egress seals of various types. 
         [0039]    Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
         [0040]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
         [0041]    Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0042]    The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.