Abstract:
A push-lock pin for connecting a tile to a gas turbine engine wall according to an exemplary aspect of the present disclosure includes, among other things, a housing extending longitudinally along an axis; a shaft assembly within the housing, the shaft assembly including a push-down pop-up mechanism and a locking mechanism, the locking mechanism moveable to a locked position such that the locking mechanism limits movement of a tile away from a gas turbine engine wall; and a stop feature to limit movement of the tile toward the gas turbine engine wall.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This disclosure claims priority to U.S. Provisional Application No. 61/776,257, which was filed on 11 Mar. 2013 and is incorporated herein by reference. 
    
    
     BACKGROUND 
     Aircraft engines, in both commercial and military aircraft, incorporate heated gas flows as part of their standard operations. In order to protect portions of the engine from the excess heat generated by the heated gas flows, insulation tiles are installed in some areas of the gas flow path. 
     With current fastener designs, a technician installing or replacing the insulation tiles requires access to the backside of the engine substructure that the tile is attached to. In order to access the backside of the substructure, the engine is removed from the aircraft. Removing the engine to facilitate replacing or repairing an insulation tile significantly increases cost beyond the actual costs of replacing the tile itself. 
     SUMMARY 
     A push-lock pin for connecting a tile to a gas turbine engine wall according to an exemplary aspect of the present disclosure includes, among other things, a housing extending longitudinally along an axis; a shaft assembly within the housing, the shaft assembly including a push-down pop-up mechanism and a locking mechanism, the locking mechanism moveable to a locked position such that the locking mechanism limits movement of a tile away from a gas turbine engine wall; and a stop feature to limit movement of the tile toward the gas turbine engine wall. 
     In a further non-limiting embodiment of the foregoing push-lock pin, the locking mechanism is moveable between the locked position and an unlocked position in response to actuation of the push-down pop-up mechanism. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the tile is free to move away from the gas turbine engine wall when the locking mechanism is in the unlocked position. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the stop member and the locking feature are configured to capture at least a portion of the gas turbine engine wall when the locking feature is in the locked position. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the stop member is a collar extending radially from the housing. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the locking mechanism comprises a plurality of spherical bearings positioned to move radially outward and inward in response to an axial position of the shaft assembly relative to the housing. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the push-down pop-up mechanism comprises a separate pin component and a cam having a low equilibrium point and a high equilibrium point, wherein a biasing member is maintained in a more biased state when the cam is at the high equilibrium point, and the biasing member is maintained in a less biased state when the cam is at the low equilibrium point. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the locking mechanism comprises a plurality of tapered blocks positioned to move radially outward and inward in response to an axial position of the shaft assembly relative to the housing. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, each of the plurality of tapered blocks rides against outwardly facing planar surfaces of the shaft when the locking mechanism is moved between the locked position and an unlocked position. 
     In a further non-limiting embodiment of any of the foregoing push-lock pins, the shaft comprises a rotatable portion and a separate fixed portion that interfaces with the plurality of tapered blocks. 
     A gas turbine engine assembly according to another exemplary aspect of the present disclosure includes, among other things, a tile; and a shaft assembly within a housing, the shaft assembly including a push-down pop-up mechanism and a locking mechanism, the locking mechanism moveable to a locked position such that the locking mechanism limits movement of the tile away from a gas turbine engine wall; and a floating support secured to the gas turbine engine wall, the floating support providing an aperture that receives the shaft assembly. 
     In a further non-limiting embodiment of the foregoing gas turbine engine, the floating support is laterally adjustable relative to the gas turbine engine wall when secured to the gas turbine engine exhaust gas path wall. 
     In a further non-limiting embodiment of any of the foregoing gas turbine engines, the floating support comprises a cup-shaped portion that extends through the aperture in the gas turbine engine wall. 
     In a further non-limiting embodiment of any of the foregoing gas turbine engines, a shaft assembly within the housing wherein the shaft comprises a locking mechanism, and a push-down pop-up mechanism, a cap connected to a first axial end of the shaft, and a spring connected to a second axial end of the shaft, wherein the second axial end is axially opposite the first axial end. 
     In a further non-limiting embodiment of any of the foregoing gas turbine engines, the tile comprises a ceramic tile. 
     In a further non-limiting embodiment of any of the foregoing gas turbine engines, the locking mechanism comprises a ball lock section of the shaft and a locking feature, wherein the ball-lock section has a larger diameter than a remainder of the shaft, and the locking feature is adjacent the ball-lock section of the shaft when the shaft is in a locked position. 
     In a further non-limiting embodiment of any of the foregoing gas turbine engines, the cap protrudes from a ceramic tile surface face when the pin is in an unlocked position, thereby operating as a handle. 
     A method of connecting a tile to a gas turbine engine wall, according to an exemplary aspect of the present disclosure includes, among other things, using a push-down pop-up mechanism to move a locking mechanism between an unlocked position and a locked position; limiting movement of a tile away from a gas turbine engine wall when the locking mechanism is in the locked position; and limiting movement of the tile toward the gas turbine engine wall using a stop member whether the locking mechanism is in the unlocked or the locked position. 
     In a further non-limiting embodiment of the foregoing method of connecting a tile, the method includes moving a plurality of tapered blocks of the locking mechanism to move between the unlocked position or the locked position. 
     In a further non-limiting embodiment of either of the foregoing methods of connecting a tile, each of the plurality of tapered blocks rides against outwardly facing planar surfaces when the locking mechanism is moved between the unlocked position and the locked position. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates an example gas turbine engine. 
         FIG. 2  schematically illustrates an insulation tile assembly that can be used in the gas turbine engine of  FIG. 1 . 
         FIG. 3A  schematically illustrates a first example push-lock pin connector in an unlocked position. 
         FIG. 3B  schematically illustrates the first example push-lock pin connector in a locked position. 
         FIG. 4  illustrates a perspective view of a shaft assembly of the first example push-lock pin connector. 
         FIG. 5A  illustrates a perspective view of a guide of the first example push-lock pin connector. 
         FIG. 5B  is a section view at line  5 - 5  in  FIG. 5A . 
         FIG. 6A  illustrates a perspective view of a tip of the first example push-lock pin connector. 
         FIG. 6B  illustrates another perspective view of the tip of  FIG. 6A . 
         FIG. 7  illustrates a perspective view of the tip of the first example push-lock pin connector in an installed position. 
         FIG. 8A  schematically illustrates a second example push-lock pin connector in an unlocked position. 
         FIG. 8B  schematically illustrates the second example push-lock pin connector in a locked position. 
         FIG. 8C  illustrates the cam structure of  FIGS. 8A and 8B  in greater detail. 
         FIG. 9A  schematically illustrates a third example push-lock pin connector in a locked position. 
         FIG. 9B  illustrates a perspective view of a locking feature of the third example push-lock pin connector. 
         FIG. 9C  is a section view at line  9 - 9  in  FIG. 9A . 
         FIG. 9D  illustrates a perspective view of a shaft assembly of the third example push-lock pin connector. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an example gas turbine engine  20  including a gas path  30  that outputs heated gas into an exhaust gas path  40 . To prevent heat damage to the exhaust gas path  40  walls, and to other components adjacent the exhaust gas path  40 , the exhaust gas path  40  is lined with tiles, such as ceramic insulation tiles  50 . The example ceramic insulation tiles  50  are each connected to the walls of the exhaust gas path  40  via a number of push-lock connector pins. 
     Existing exhaust liners utilize a single metal sheet with multiple air holes. Cooling air is pumped through the air holes to cool the exhaust gas path  40  according to known active cooling techniques. The existing exhaust gas path  40  liners are permanently affixed to the turbine engine exhaust gas path  40  walls. As a result, in order to perform maintenance on the exhaust gas path liner the gas turbine engine  20  must be removed from the aircraft. 
     The example ceramic insulation tiles  50  of this disclosure have a significantly higher heat capacity than a metal liner and thus do not need to be actively cooled to prevent heat from passing through the exhaust gas path  40  walls. The ceramic insulation tiles  50  are each individually connected to the exhaust gas path walls, and combine to form a tiled exhaust gas path liner that protects engine components adjacent to the exhaust gas path from excess heat. 
       FIG. 2  schematically illustrates an example insulation tile assembly  100  that can be used in the exhaust gas path  40  of  FIG. 1 . The insulation tile assembly  100  includes a tile  110  with multiple push-lock connectors  120  protruding from the tile  110 . In this example, the tile  110  is a ceramic tile mounted to a base plate  104 . The push-lock connectors  120  engage with a substrate  130  (such as a metal substrate of the exhaust gas path  40  walls) via corresponding connection features  140  in the substrate  130 . The corresponding connection features  140  are apertures in this example. In another example, the push-lock connectors  120  may extend from the substrate  130  rather than the tile  110 . 
     To connect the tile  110  to the substrate  130 , the push-lock connectors  120  are inserted into the connection features  140 . Once inserted, a cap  122  on the push-lock connector  120  is pushed, placing the push-lock connector in a locked position. To unlock the push-lock connector  120 , the cap  122  is pushed again, placing the push-lock connector  120  in an unlocked position. When the push-lock connectors  120  are in the locked position, the ceramic tile  110  cannot be removed from the substrate  130 . In the locked position, the cap  122  is flush with the surface of tile  110 . 
     When the push-lock connectors  120  are in the unlocked position, the ceramic tile  110  can be removed and replaced. In the unlocked position, cap  122  is protruding from the surface of tile  110 . This creates a handle to facilitate the removal of tile  110 . The cap  122  further includes a top ceramic surface matching the ceramic tile  110  such that the cap  122 , when the push-lock connector  120  is in the locked position, has a ceramic surface flush with the ceramic tile  110 . 
       FIGS. 3A to 7  illustrate a first example push-lock pin  200  that can be utilized in the example ceramic insulation tile arrangement of  FIG. 2 , with  FIG. 3A  illustrating the push-lock pin  200  in an unlocked position and  FIG. 3B  illustrating the push-lock pin  200  in a locked position. The push-lock pin  200  secures a tile  202  to a substrate  208 . The tile is a ceramic tile in this example. 
     The example push-lock pin  200  includes the housing  210  and a shaft assembly  220  received within the housing  210  extending longitudinally along a radial axis R. In operation, the shaft  220  is moved relative to the housing  210  to permit or restrict movement of push-lock pin  200  relative to the substrate  208 . 
     The push-lock pin  200  extends through an opening  206  in the tile  202 . The housing  210  of the push-lock pin  200  is directly affixed to the tile  202  via a fastener  204 . The fastener  204  can be any bracket type fastener and can be affixed to the housing  210  and the tile  202  using any known method. 
     The example housing  210  includes a guide  212  and a tip  214 . One axial end of the guide  212  includes tabs  216  that are received within slots  218  of the tip  214  to limit relative rotation between the guide  212  and the tip  214 . The guide  212  may include slots and the tip  214  many include tabs in other examples. 
     An axial end of the guide  212  opposite the slots  218  is tapered to assist in moving the push-lock pin  200  into an aperture  222  of the substrate  208  during installation of the tile  202  to the substrate  208 . The guide  212  extends through the aperture  222  in the substrate  208  and an aperture  224  within a floating support, such as a washer  225 . The aperture  224  is smaller than the aperture  222 . 
     Pins  226 , or some other type of fastener, are used to secure the washer  225  to the substrate  208 . The washer  225  is held between flanged bushings  227  and the substrate  208  in this example, which allows the washer  225  to float or shift slightly relative to the substrate  208  while still being held securely. The washer  225  can be considered laterally adjustable due to its ability of float or shift. 
     The washer  225  includes cutouts  228 . The cutouts  228  are hemispherical in this example, but could have other profiles. The cutouts  228  provide the washer with freedom to shift. The washer  225  is thus held such that some movement of the aperture  224  relative to the aperture  222  is permitted. 
     During assembly, when the guide  212  is inserted into the apertures  222  and  224 , the aperture  224  may need to move or shift relative to the aperture  222 . Relative movement may be required to accommodate expansion and contraction, of the washer  225  relative to the flanged bushings  227 , the pins  226 , or both. Relative movement may be required due to build-tolerances. 
     The guide  212  includes a collar  232  extending outward from the guide  212 . The collar  232  extends radially past the perimeter of the aperture  222 , which prevents the push-lock pin  200  and the tile  202  from moving in a direction D. The collar  232  enables the push-lock pin  200  to absorb compressive loads against the tile  202  in the direction D. 
     The collar  232  is an example type of stop feature. Other examples may include ridges, pins, arms, etc., that extend outward from the guide  212  or some other portion of the push-lock pin  200 . 
     The example shaft  220  includes portions of a ball-locking mechanism  250  and portions of a push-down pop-up mechanism  240 . The cap  230  is attached to a first axial end of the shaft  220 . A spring  260  is positioned on a second axial end of the shaft  220  opposite the first axial end. In some example arrangements, such as the arrangement of  FIGS. 3A and 3B , the shaft  220  includes features causing the shaft  220  to rotate within the housing  210  whenever the cap  230  is depressed. 
     Referring now to the ball-locking mechanism  250 , the shaft  220  includes a narrow section  251 , a wide section  252 , and an angled section  253 . Multiple locking features  254 , such as spherical ball bearings, surround the shaft  220 . When the shaft  220  shifts axially from the unlocked position of  FIG. 3A  to the locked position of  FIG. 3B , the locking features  254  shift from the narrow section  251 , across the angled section  253 , to the wide section  252 . 
     Adjacent to the locking features  254  are multiple openings  256  in the tip  214 . When the push-lock pin  200  is in an unlocked position, the locking features  254  are contained within the tip  214  of the housing  210  due to their axial alignment with the narrow section  251 . The push-lock pin  200  can thus be removed from the substrate  208 . The push-lock pin  200  can be removed by moving the push-lock pin  200  in a direction opposite the direction R. 
     When the push-lock pin  200  is in a locked position of  FIG. 3B , the locking features  254  are pushed partially radially out of the openings  256  due to their axial alignment with the wide section  252 . In this position, the locking features  254  prevent the push-lock pin  200  from being removed from the substrate  208 . Contact between the locking features  254  and the washer  225  prevents the push-lock pin  200  from being withdrawn. Contacting the locking features  254  against the washer  225  rather than the substrate  208  facilitates positional variations due to relative thermal expansion between components. The washer  225  can shift slightly relative to the substrate  208 , but still provide an effective anchoring location for the locking features  254 . 
     In this example, the push-down pop-up mechanism  240  of the push-lock pin  200  comprises mechanical features of the shaft  220 , the guide  212 , and the tip  214 . The shaft  220  defines at least a deep groove  245  and a shallow groove  247 . The guide  212  includes at least one finger  246  that is received within the deep groove  245  or the shallow groove  247  depending on the circumferential orientation of the shaft  220  relative to the guide  212 . 
     When the finger  246  is located in the deep groove  245 , the finger  246  is in a low equilibrium point  242 . When the finger  246  is in the shallow groove  247 , the finger  246  is in a high equilibrium point  244 . Activation of the cap  230  causes the finger  246  to move between the low equilibrium point  242  and the high equilibrium point  244 . 
     More specifically, pressing the cap  230  moves the finger  246  axially out of the deep groove  245  or the shallow groove  247 . When the cap  230  is released, the spring  260  exerts an axial force on the shaft  220  causing the finger  246  to contact a ramped area  262 . As the finger  246  is pressed axially against the ramped area  262  by the spring  260 , the finger  246  slides against the ramped area  262  causing the shaft  220  to rotate. If the finger  246  was in the deep groove  245 , the rotation causes the finger  246  to move into the shallow groove  247 . If the finger  246  was in the shallow groove  247 , the rotation causes the finger  246  to move into a deep groove  245 . The tip  222  may also include a ramped area  249  to help the shaft  220  to rotate. 
     Activating the push-down pop-up mechanism (depressing the cap  230 ) thus shifts the finger  246  from one equilibrium point  242 ,  244  to the other equilibrium point  242 ,  244 . When the finger  246  is in the high equilibrium point  244  ( FIG. 3B ) the ball-locking mechanism  250  is maintained in the locked position via a combination of the finger  246  and the axial force provided by the spring  260 . Similarly, the cap  230  is maintained approximately flush with the tile  202 . Conversely, when the finger  246  is resting in the low equilibrium point  242 , the ball-locking mechanism  250  is unlocked, and the cap  230  is not flush with the tile  202 . 
       FIGS. 8A, 8B, and 8C  illustrate another example push-lock pin  300  including a different push-down pop-up mechanism  340 , with  FIG. 8A  illustrating the push-lock pin  300  in an unlocked position,  FIG. 8B  illustrating the push-lock pin  300  in a locked position, and  FIG. 8C  illustrating a push-down pop-up mechanism  340  in greater detail. The ball-locking mechanism  350  functions generally the same as the ball-locking mechanism  250  of  FIGS. 3A and 3B . 
     The push-down pop-up mechanism  340  of the  FIGS. 8A-8C  embodiment utilizes a cam structure  370  and a separate pin component  372 . The separate pin component  372  replaces the finger  246  of the  FIGS. 3A and 3B  embodiment. 
     The push-down pop-up mechanism  340  includes the cam structure  370  with a high equilibrium point  344  and a low equilibrium point  342 . The separate pin  372  extends into the cam structure  370  and rests in one of the equilibrium points  342 ,  344 . Activation of the push-lock pin  300  causes the separate pin component  372  to shift from a current equilibrium point to the other equilibrium point  342 ,  344 . 
       FIG. 8C  schematically diagrams the movement of the separate pin component  372  from the low equilibrium point  342  to the high equilibrium point  344  along a movement path  374 . 
       FIG. 8C  also schematically diagrams the movement from the high equilibrium point  344  to the low equilibrium point  342  along a movement path  376 . The contours of the cam structure  370  ensure that the separate pin component  372  follows the illustrated movement paths  374 ,  376  and properly transitions between the high equilibrium point  344  and the low equilibrium point  342  when the cap  330  is depressed. 
     In this example, a washer  325  has a cup-shaped portion  380  that extends from radially outside the substrate  208  to radially inside the substrate  208 . Locking features  354  of this embodiment rest against an interior of the cup-shaped portion  380  when the push-lock pin  300  is locked. The locking features  354  are located radially inside the substrate  208  in at least the locked position. The washer  325 , with the cup-shaped portion  380 , can float somewhat relative to the substrate  208 . 
     Referring now to  FIGS. 9A-9C , another example push lock pin  400  includes locking features  454  that are tapered blocks having conical surfaces  464  or chamfers. The flat surfaces  464  rest against corresponding surfaces  468  on a washer  425  when the push-lock pin  400  is in a locked position. As the push-lock pin moves between locking and unlocked positions, the locking features  454  slide along faces  478  of a shaft assembly  420 . 
     The example shaft  420  is a two piece shaft having a rotatable portion  480  and a separate, fixed portion  484 . The rotatable portion  480  rotates about radial axis R when the push-lock pin  400  is moved from between the locked and unlocked positions. Because the fixed portion  484  does not rotate, the locking features  454  maintain their circumferential orientation relative to the radial axis R and remain associated with a respective one of the faces  478 . 
     While the above disclosure is directed toward insulation tiling for an aircraft engine, it is understood that the described connector pin can be utilized in any application where it is desirable to connect a tile to a surface without providing access to a reverse side of the surface. 
     Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.