Abstract:
A seal assembly for a turbine engine is disclosed and includes a fixed housing including an axial surface defining an inner diameter and an annular seal that is disposed within the housing and seal against a radial surface of the fixed housing. The annular seal includes a first surface transverse to an axis of rotation and a second surface parallel to the axis of rotation defining an inner periphery. The first surface includes a first notch spaced apart from the inner periphery and overlapping the inner diameter of the fixed housing.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/896,178 filed on Oct. 28, 2013. 
     
    
     BACKGROUND 
       [0002]    A turbine engine typically includes a compressor section, a combustor section and a turbine section. The compressor section is driven by the turbine section through a shaft. 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-energy exhaust gas flow. Seals are provided between static components and the rotating components to separate regions of high and low pressure gas, liquid or temperatures. 
         [0003]    A seal assembly includes a fixed part that supports an annular seal that interfaces with the rotating component. The seal component can be supported within a fixed housing or static portion of the engine proximate a rotating shaft or rotor. The annular seal seals radially against the rotating shaft or rotor component and axially against the fixed housing. A radial gap between the fixed housing and the rotating shaft does not experience wear like other portions of the annular seal. Uneven wear on a sealing face of the annular seal can result in premature degradation and may influence overall engine performance. 
         [0004]    A relief cut within the radial gap reduces the uneven wear, but can result in a degradation of seal performance. Moreover, the performance of the seal can be detrimentally influenced by uneven pressures along the sealing surfaces. 
         [0005]    Engine manufacturers continually seek improvements in engine performance, thermal efficiency as well as durability and maintenance efficiencies. 
       SUMMARY 
       [0006]    A seal assembly according to an exemplary embodiment of this disclosure, among other possible things includes a fixed housing including an inner fixed surface, and an annular seal disposed within the fixed housing. The annular seal includes a first surface transverse to an axis of rotation and a second surface parallel to the axis of rotation defining an inner periphery. The first surface includes a first notch spaced apart from the second surface and overlapping the inner fixed surface of the fixed housing. 
         [0007]    In a further embodiment of any of the foregoing seal assemblies, the first notch includes a radially inner axial surface spaced apart from a radially outer axial surface. 
         [0008]    In a further embodiment of any of the foregoing seal assemblies, the first surface transverse to an axis of rotation includes an upper radial surface radially outboard of the first notch and a lower radial surface flush with the upper radial surface radially inboard of the first notch. 
         [0009]    In a further embodiment of any of the foregoing seal assemblies, the first notch extends annularly about the annular seal. 
         [0010]    In a further embodiment of any of the foregoing seal assemblies, includes a second notch on the first surface spaced radially outward from the first notch. 
         [0011]    In a further embodiment of any of the foregoing seal assemblies, includes at least one slot in communication with the second notch and a radially outer surface of the annular seal. 
         [0012]    In a further embodiment of any of the foregoing seal assemblies, the annular seal includes a third notch disposed on the second surface and spaced axially aft of the first surface. 
         [0013]    In a further embodiment of any of the foregoing seal assemblies, includes a radial spring disposed on a radially outer surface of the annular seal for biasing the annular seal into contact with a rotating element. 
         [0014]    In a further embodiment of any of the foregoing seal assemblies, the annular seal includes a first annular seal and a second annular seal disposed within the fixed housing and a biasing member biasing the first annular seal away from the second annular seal and into engagement with the fixed housing. 
         [0015]    A seal assembly for a turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes a fixed housing including a radially inner fixed surface. A rotating element is configured for rotation about an axis. The radially inner fixed surface of the fixed housing is spaced apart from the rotating element. An annular seal is disposed within the fixed housing including a first surface configured for sealing against the fixed housing. A second surface is configured for sealing against the rotating element and a first notch on the first surface spaced radially apart from the second surface. The radially inner fixed surface of the fixed housing is aligned with the first notch. 
         [0016]    In a further embodiment of any of the foregoing seal assemblies, the first notch includes a radially inner axial surface and a radially outer axial surface. 
         [0017]    In a further embodiment of any of the foregoing seal assemblies, the first surface is disposed transverse to the axis and includes an upper radial surface radially outward of the first notch and a lower radial surface axially flush with the upper radial surface and radially inward of the first notch. 
         [0018]    In a further embodiment of any of the foregoing seal assemblies, the annular seal includes a second notch on the first surface that is radially outward of the first notch. 
         [0019]    In a further embodiment of any of the foregoing seal assemblies, includes at least one radial slot between the second notch and a radially outer surface of the annular seal. 
         [0020]    In a further embodiment of any of the foregoing seal assemblies, includes a third notch on the second surface spaced axially aft of the first surface. 
         [0021]    In a further embodiment of any of the foregoing seal assemblies, includes at least one axial slot between the third notch and an axially aft surface of the annular seal. 
         [0022]    In a further embodiment of any of the foregoing seal assemblies, includes a biasing member biasing the annular seal into radial engagement with the rotating element. 
         [0023]    In a further embodiment of any of the foregoing seal assemblies, the annular seal includes a first annular seal and a second annular seal disposed within the fixed housing and a biasing member biasing the first annular seal away from the second annular seal and into engagement with the fixed housing. 
         [0024]    A turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes a fixed housing including a radially inner fixed surface. A rotating element is mounted to a shaft configured for rotation about an axis. The radially inner fixed surface of the fixed housing is spaced apart from the rotating element. An annular seal is disposed within the fixed housing including a first surface configured for sealing against the fixed housing. A second surface is configured for sealing against the rotating element and a first notch on the first surface spaced radially apart from the second surface. The radially inner fixed surface of the fixed housing is aligned with the first notch. 
         [0025]    In a further embodiment of any of the foregoing turbine engines, the first surface is disposed transverse to the axis and includes an upper radial surface radially outward of the first notch and a lower radial surface axially flush with the upper radial surface and radially inward of the first notch. 
         [0026]    In a further embodiment of any of the foregoing turbine engines, the annular seal includes a first annular seal and a second annular seal disposed within the fixed housing and a biasing member biasing the first annular seal away from the second annular seal and into engagement with the fixed housing. 
         [0027]    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. 
         [0028]    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 
         [0029]      FIG. 1  is a schematic view of an example gas turbine engine. 
           [0030]      FIG. 2  is a sectional view of an example seal assembly. 
           [0031]      FIG. 3  is an enlarged view of a portion of an example annular seal. 
           [0032]      FIG. 4  is a cross-section of an example annular seal. 
           [0033]      FIG. 5  is a front view of an example annular seal including a plurality of arcuate segments. 
           [0034]      FIG. 6  is another front view of another example annular seal formed as a single unitary structure. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Referring to  FIG. 1 , a gas turbine engine  10  includes a fan section  12 , a compressor section  14 , a combustor section  16 , and a turbine section  18 . Air entering into the fan section  12  is initially compressed and fed to the compressor section  14 . In the compressor section  14 , the incoming air from the fan section  12  is further compressed and communicated to the combustor section  16 . In the combustor section  16 , the compressed air is mixed with gas and ignited to generate a hot exhaust stream. The hot exhaust stream is expanded through the turbine section  18  to drive the fan section  12  and the compressor section  14 . In this example, the gas turbine engine  10  includes an augmenter section  20  where additional fuel can be mixed with the exhaust gasses  28  and ignited to generate additional thrust. The exhaust gasses flow from the turbine section  18  and the augmenter section  20  through an exhaust liner assembly  22 . The example turbine engine also includes a nozzle  22  to further accelerate exhaust gases and provide additional thrust. 
         [0036]    The example turbine engine includes a core gas flow sea that flows through the fan section, compressor section and is exhausted through the turbine section. The gas turbine engine  10  also includes an inner liner  24  and an outer duct wall  26  that defines a bypass passage  28  for a bypass air flow B. The bypass air flow B is propelled through the bypass passage  28  to provide additional thrust generated by the example gas turbine engine  10 . 
         [0037]    A seal assembly  36  is provided adjacent the shaft  32  to seal about the rotating shaft  32 . The example seal assembly  36  is supported by a static engine structure  30  and dispose adjacent the shaft  32  that supports a rotor  34 . 
         [0038]    Referring to  FIG. 2  with continued reference to  FIG. 1 , the example seal assembly  36  includes a fixed housing  38  that is supported by the static engine structure  30 . The housing  38  includes a forward section  35  and an aft section  37  within which annular seals  40 A and  40 B are disposed. The annular seals  40   a,    40   b  are biased radially downward against a plate  25  that rotates with the shaft  32  and axially outward against a forward section  35  and aft section  37  of the fixed housing  38 . 
         [0039]    Each of the annular seals  40 A,  40 B includes an first or upper radial surface  48  that is in sealing contact with the radial sealing surfaces  44  defined by the forward and aft sections  35 ,  37  of the housing  38 . The annular seals  40 A,  40 B include a second surface  50  defining an inner periphery that is in sealing contact with the plate  25  that is connected to the rotating shaft  32 . 
         [0040]    In this example, a first annular seal  40 A and a second annular seal  40 B are disposed within the housing  38  and are biased radially downward against the plate  25  by radial biasing members  70 . The radial biasing members  70  are disposed on a radially outer surface  46  of the annular seals  40 A,  40 B. An axial biasing member  72  is disposed between the annular seals  40 A,  40 B and forces the annular seals  40 A,  40 B axially outward from each other against corresponding radial sealing surfaces  44 . 
         [0041]    The upper radial surface  48  of each of the annular seals  40 A,  40 B includes a first notch  56  and a second notch  58 . The upper radial surface  48  also includes the second notch  58  radially outboard of the first notch  56 . 
         [0042]    Each of the annular seals  40 A,  40 B includes a third notch  60  disposed on the second surface  50 . The second notch  60  is spaced axially aft of the first notch  56  and the outer radial surface  48 . The third notch  60  is spaced axially aft of the first notch  56  and the outer radial surface  48 . 
         [0043]    Referring to  FIGS. 3 and 4  with continued reference to  FIG. 2 , each of the annular seals  40 A,  40 B includes the first notch  56  defined by an inner axial surface  68  and an outer axial surface  66 . The first notch  56  is spaced a radial distance away from the second surface  50  such that it is not disposed against the rotating plate  25 . 
         [0044]    A foot  57  is defined radially inward of the first notch  56  and includes a lower radial surface  55  that is substantially flush with the upper radial surface  48  above the first notch  56 . Because the lower radial surface  55  is axially even with the upper radial surface  48  above the first notch  56 , a desired radial force balance is improved. The foot  57  includes an axial length  59  that is greater than the axial length  65  of the first notch  56 . The first notch  56  radially overlaps a radially inner fixed surface  42  of the housing of the corresponding forward and aft sections  35 ,  37  of the fixed housing  38 . 
         [0045]    The third notch  60  is disposed axially aft of the outer radial surface  48  and is in communication by way of the second slot  64  with the back surface  54  of the corresponding annular seal. In this example the third notch  60  includes an angled upper radial surface  63  that angles radially outward toward the back surface  54 . The angled surface extends to a radial height of the slot  64 . Other geometries for the third notch  60  are also within the contemplation of this disclosure. Such geometries can include a rectangular shape, a tapered curved shape along with other possible shapes that provide a desired area. 
         [0046]    The first notch  56  includes a radially outer axial surface  66  and radially inner axial surface  68 . The radially inner and outer axial surfaces  66  and  68  are the same axial length  65 . The first notch  56  is a relief cut near the radially inner fixed surface  42  of the housing  38  that prevents uneven wear along the outer radial surface  48 . The outer axial surface  66  is always radially outboard of the radially inner fixed surface  42  and the inner axial surface  68  is always inboard of the radial inner fixed surface  42 . Because the radial inner fixed surface  42  is always aligned within the relief provided by the first notch  56 , the foot  57  does not contact the radial inner fixed surface  42  and the possibility of damage is significantly reduced. Moreover, because the radially outer axial surface  66  is always outboard of the radially inner fixed surface  42  the possibility of uneven wear or damage is significantly reduced. Accordingly, the foot  57  can be extended such that the lower radial surface  55  is axially flush with the upper radial surface  48  above the first notch  56  to provide the desired force balance without risking contact with the radial inner fixed surface  42 . 
         [0047]    The second notch  58  is spaced radially outward of the first notch  56 . The third notch  60  is disposed on the second sealing surface is, in this example, axially spaced apart from the first sealing surface and the first notch  56 . The first and second notches  56  and  58  are substantially rectangular but may also be provided with different geometries such as curved or contoured shapes. 
         [0048]    The example plate  25  rotates relative to the seal assembly  36  and the fixed housing  38 . High pressure air or gas  76  is present within the gap between radially outer surfaces of the annular seals  40 A,  40 B. The high pressure air  76  is communicated to the third notch  60  by way of the second slot  64 . The same high pressure air is communicated to the second notch  58  through the second slot  62 . Accordingly, high pressure air is communicated through the first and second slots  64 ,  62  to provide the biasing and equilibrium forces against the axial surface of the rotating plate  25  and the sealing surface  44 . 
         [0049]    The first notch  56  provides a relief cut to prevent the foot  57  of the annular seal  40  from contacting the radial inner fixed surface  42  due to uneven wear between the upper radial surface  48  and the lower radial surface  55 . The notch  56  is configured such that radial movement of the annular seal  40  does not cause the inner radial surface  42  to overlap the foot  57  and the lower radial surface  55  defined by the foot  57 . Regardless of the wear experienced on the upper radial surface  48  above the first notch  56 , the foot  57  will not contact the radial inner fixed surface  42 . Accordingly, the lower radial surface  55  of the foot  57  can extend flush with the upper radial surface  48  to provide the desired force balance while also improving operational life. 
         [0050]    In this example, each of the annular seals  40 A,  40 B are formed from a carbon material to provide the desired sealing performance while maintaining and reducing the amount of friction engaged between relative moving components such as the rotating plate  25  and sealing surfaces  44  defined by the forward and aft sections  35 ,  37  of the housing  38 . 
         [0051]    Referring to  FIGS. 5 and 6 , a forward radial surface of one of the annular seals  40 A is shown and discloses that the first notch  56  is a continuous annular notch about the circumference of the annular seal  40 A. The second notch  58  is spaced radially apart from the first notch  56  and is also a continuous annular notch disposed along the first surface that engages the radial sealing surface  44  defined by the fixed housing  38 . 
         [0052]      FIG. 5  illustrates the annular seal  40 A as a plurality of arcuate segments  74 . The example annular seals  40 A,  40 B may also be constructed for a single unitary annular element as is shown in  FIG. 6 . The single unitary element may have a radial expansion slot  76 . 
         [0053]    Accordingly, the example annular seal assembly includes a foot and axial surface below a first notch that is flush with an axial sealing surface above the first notch to provide a desired force balance. The first notch is configured such that radial movement of the seal does not result in the lower axial surface contacting the radial inner surface of the housing and also maintains the outer surface in contact with the radial inner surface of the housing to avoid uneven wear. Accordingly, the example seal provides the desired radial force balance while also improving axial surface wear life. 
         [0054]    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.