Abstract:
A method and system suitable facilitating the connection and disconnection of a thrust reverser assembly to a fan case of a nacelle of a gas turbine engine. The method and system entail operating a clamping system to simultaneously engage and disengage flanges associated with the fan case and flanges associated with the fixed structure of the thrust reverser assembly. The clamping system includes a plurality of over-center clamping mechanisms, each of which is movable to simultaneously clamp together complementary flanges of the thrust reverser assembly and the fan case.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/493,671, filed Jun. 6, 2011, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to mechanisms by which nacelle components of a turbofan gas turbine engine can be coupled and decoupled. 
       FIG. 1  schematically represents a high-bypass turbofan engine  10  of a type known in the art. The engine  10  is schematically represented as including a nacelle  12  and a core engine (module)  14 . A fan assembly  16  located in front of the core engine  14  includes a spinner nose  20  projecting forwardly from an array of fan blades  18 . The core engine  14  is schematically represented as including a high-pressure compressor  22 , a combustor  24 , a high-pressure turbine  26  and a low-pressure turbine  28 . A large portion of the air that enters the fan assembly  16  is bypassed to the rear of the engine  10  to generate additional engine thrust. The bypassed air passes through an annular-shaped bypass duct  30  between the nacelle  12  and an inner core cowl  36  of the core engine  14 , and exits the duct  30  through a fan exit nozzle  32 . The core cowl  36  defines the radially inward boundary of the bypass duct  30 , and provides an aft core cowl transition surface to a primary exhaust nozzle  38  that extends aftward from the core engine  14 . 
     The nacelle  12  is typically composed of three primary elements that define the external boundaries of the nacelle  12 : an inlet assembly  12 A, a fan cowl  12 B including a fan case that surrounds the fan blades  18 , and a thrust reverser assembly  12 C located aft of the fan cowl  12 B. The thrust reverser assembly  12 C comprises four primary components: a translating cowl  34 A mounted to the nacelle  12 , the inner core cowl  36  of the core engine  14 , a cascade  34 B schematically represented within the nacelle  12 , and a blocker door  34 C schematically represented as being pivotally deployed from a position radially inward from the cascade  34 B. The bypassed fan air flows between fan duct flow surfaces defined by the translating cowl  34  and the core cowl  36  before being exhausted through the fan exit nozzle  32 . The translating cowl  34  translates to expose the cascade  34 B and cause the blocker door  34 C to deploy and divert bypassed air through the exposed cascade  34 B. 
     In recent engine systems, the thrust reverser assembly  12 C has been configured to separate from the fan cowl  12 B and translate aft to allow access to the core cowl  36  and the core compartment of the core engine  14 . Such a configuration requires the ability to connect and disconnect a fixed structure of the thrust reverser assembly  12 C (which includes the cascade  34 B) at a fixed structure (generally, the fan case) surrounded by the fan cowl  12 B. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides a method and system suitable facilitating the connection and disconnection of a thrust reverser assembly to a fan case of a nacelle of a gas turbine engine. The invention is particularly well suited for use with a thrust reverser assembly comprising a fixed structure configured to be translated to couple and decouple the fixed structure from the fan case. 
     According to a first aspect of the invention, the clamping system comprises flanges associated with the fan case, flanges associated with the fixed structure of the thrust reverser assembly and adapted for simultaneous mating with the flanges of the fan case, and a plurality of over-center clamping mechanisms. A first of the over-center clamping mechanisms is mounted to the thrust reverser assembly and adapted to clamp a first of the flanges of the thrust reverser assembly with a first of the flanges of the fan case. A second of the over-center clamping mechanisms is mounted to the fan case and adapted to clamp a second of the flanges of the thrust reverser assembly with a second of the flanges of the fan case. 
     According to a second aspect of the invention, a method of coupling and decoupling a fan case and thrust reverser assembly entails operating a clamping system to simultaneously engage and disengage flanges associated with a fixed structure of the thrust reverser assembly and flanges associated with the fan case. The operating step comprises movement of a plurality of over-center clamping mechanisms to clamp together the flanges of the thrust reverser assembly and the fan case. 
     A technical effect of the invention is the ability of the clamping system to quickly and reliably connect and disconnect a thrust reverser assembly to a fan case of a gas turbine engine using multiple/redundant connections. The clamping system also offers the advantages of low weight, compactness, no conflicts with service line routing, ease of operation, and reduced risk for jams or improper seating due to friction. 
     Other aspects and advantages of this invention will be better appreciated from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically represents a cross-sectional view of a high-bypass turbofan engine. 
         FIGS. 2 and 3  are isolated perspective and axial views, respectively, showing an assembly comprising portions of a fan case and a fixed structure of a thrust reverser assembly coupled together with a multi-segment clamping system of the present invention. 
         FIG. 4  is an isolated perspective view of the assembly of  FIGS. 2 and 3  showing the portions of the fan case and fixed structure decoupled from each other through the operation of the multi-segment clamping system of the present invention. 
         FIG. 5  is a detailed side view of a portion of the multi-segment clamping system of  FIG. 4 . 
         FIG. 6  is a detailed view of the multi-segment clamping system of  FIG. 4  showing a cutout through which conduits can be routed through the assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 2 through 6  represent various views of an assembly  40  through which a fan case and thrust reverser assembly of a gas turbine engine can be quickly coupled and decoupled to allow the thrust reverser assembly to translate aft and away from the fan case, for example, on one or more slider tracks (not shown). The assembly  40  represented in  FIGS. 2 through 6  can be installed in a high-bypass gas turbine engine  10  of the type represented in  FIG. 1 . While the assembly  40  can be adapted for installation at various locations of the engine  10 , the assembly  40  is particularly intended to be installed between the fan cowl  12 B and thrust reverser assembly  12 C, for example, at a location of the nacelle  12  located axially between the high and low pressure compressor sections  22  and  24  of the engine  10 . 
     The assembly  40  is represented as including two ring-type components, a first of which will be referred to as the fan case  42  and the second will be referred to as a fixed structure  44  of a thrust reverser assembly. As known in the art, the fan case  42  is a static structure within the fan cowl  12 B that surrounds the fan blades  18  of the engine  10 , and the fixed structure  44  may include the cascade  34 B and other static parts of the thrust reverser assembly  12 C of the engine  10 . Accordingly, it should be understood that the ring-type components shown in the figures and identified as the fan case  42  and fixed structure  44  are only portions of, respectively, a fan case and thrust reverser assembly typically found in a high-bypass gas turbine engine of the type represented in  FIG. 1 . In particular, the component identified as the fan case  42  may be a portion of the entire structure that forms a fan case within the nacelle  12  of the engine  10 , or a ring that is bolted or otherwise attached to a structure that together form a fan case of the engine  10 . Similarly, the component identified as the fixed structure  44  may be a portion of the entire structure that forms the fixed structure (including the cascade  34 B) of the thrust reverser assembly  12 C of the engine  10 , or a ring that is bolted or otherwise attached to a structure that together form the fixed structure of the thrust reverser assembly  12 C. However, for convenience, the components will simply be referred to as the fan case  42  and fixed structure  44 . 
     The assembly  40  is represented in  FIGS. 2 through 6  as comprising a clamping system adapted to couple and decouple the fan case  42  and the fixed structure  44  to allow the thrust reverser assembly  12 C to translate aft and away from the fan case  42 . The clamping system is configured to provide a method for coupling and decoupling the fan case  42  and thrust reverser assembly  12 C by simultaneously engaging and disengaging flanges  48  and  50  associated with, respectively, the fan case  42  and the fixed structure  44  of the thrust reverser assembly  12 C. In particular, the clamping system comprises a plurality of over-center clamping mechanisms  52 , some of which are mounted to the fan case  42  and others to the fixed structure  44 . The coupling and decoupling method provided by the clamping system entails the movement of each clamping mechanism  52  to simultaneously clamp portions of the flanges  48  and  50  together, as well as simultaneously release the flanges  48  and  50 . 
     As represented in  FIG. 5 , the flange portions  48 A and  50 A preferably project in radially outward directions of the engine  10 , so that the flange portions  48 A and  50 A lie in planes that are parallel to each other. As most readily evident from  FIGS. 4 and 5 , the flanges  48  associated with the fan case  42  comprise multiple axially-offset flange portions  48 A that extend around different circumferential portions of the nacelle  12 . Similarly, the flanges  50  associated with the fixed structure  44  comprise multiple axially-offset flange portions  50 A that extend around different circumferential portions of the nacelle  12 . The flange portions  48 A of the fan case  42  and the flange portions  50 A of the fixed structure  44  are complementarily axially offset and circumferentially located so that each flange portion  48 A of the fan case  42  will mate with one of the flange portions  50 A of the fixed structure  44 . Each of the over-center clamping mechanisms  52  of the clamping system is also circumferentially and axially offset from each other, and dedicated to clamp one complementary pair of the flange portions  48 A and  50 A. Furthermore, each over-center clamping mechanism  52  is mounted to either the fixed structure  44  to clamp one of the flange portions  50 A of the fixed structure  44  with one of the flange portions  48 A of the fan case  42 , or to the fan case  42  to clamp one of the flange portions  50 A of the fixed structure  44  with one of the flange portions  48 A of the fan case  42 . 
     Each of the over-center clamping mechanisms  52  of the clamping system comprises a clamping segment  54  that extends over a circumferential portion of the nacelle  12 , a pivot link  56  at one circumferential end of the clamping segment  54 , and an over-center link  58  at an oppositely-disposed circumferential end of the clamping segment  54 . Because each clamping mechanism  52  is mounted to either the fan case  42  or the fixed structure  44 , each pair of pivot and over-center links  56  and  58  for each mechanism  52  is pivotably mounted to either the fan case  42  or the fixed structure  44 . As evident from  FIGS. 2 ,  3  and  4 , in the circumferential direction of the assembly  40 , the mechanisms  52  alternate between being mounted to the fan case  42  or to the fixed structure  44 . Furthermore, the circumferential ends of the mechanisms  52  overlap each other as a result of their pivot and over-center links  56  and  58  being axially aligned with one of the pivot or over-center links  56  and  58  of an adjacent mechanism  52 . The over-center link  58  cooperates with the pivot link  56  to induce an over-center toggle operation in the clamping segment  54 . Due to the pivoting movement of the pivot and over-center links  56  and  58 , the movement of the clamping segment  54  comprises both a radially outward travel and then a radially inward travel combined with a circumferential travel between a position of the mechanism  52  that clamps a pair of flange portions  48 A and  50 A together and a position of the mechanism  52  that releases the pair of flange portions  48 A and  50 A. As should be evident from  FIGS. 2 through 6 , an operator can readily cause each mechanism  52  to move between these two extremes by grasping a handle  60  that protrudes in a circumferential direction from the segment  54  adjacent the over-center link  58 . 
     Those skilled in the art will appreciate that the configurations of the over-center clamping mechanisms  52  are based on the design of a Marman clamp, which is a well-know device for connecting pipe joints. However, the present invention uses a plurality of axially and circumferentially offset mechanisms  52  to achieve a large-diameter connection between the fan case  42  and the fixed structure  44  of the thrust reverser assembly  12 C. The multiple mechanisms  52  are not only convenient to operate, but also provide a level of redundancy, retaining a secure connection even in the event of a failure of one or more of the mechanisms  52 . An optimal number of mechanisms  52  will vary depending on the given application, though the use of two to eight mechanisms  52  is believed to be practical for many applications. The invention may further comprise means (not shown) for locking the handles  60  to secure the mechanisms  52  in the clamping position, as well as additional tensioning devices similar to latches. 
     As shown in  FIGS. 2 through 4  and more readily seen in  FIG. 6 , the assembly  40  can further comprise a cutout  62  through which conduits  64  of any type can be routed through the assembly  40 . A gas-tight seal (not shown) can be provided to minimize or prevent air flow losses through the assembly  40 .  FIG. 6  further shows a pair of shear pins  66  located on either side of the cutout  62  to reinforce the structural strength of the assembly  40  in the vicinity of the cutout  62 . 
     While the invention has been described in terms of a specific embodiment, it is apparent that other forms could be adopted by one skilled in the art. For example, the assembly  40  could differ in appearance and construction from the embodiment shown in the figures, the functions of each component of the assembly  40  could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function, and various materials could be used in the construction of these components. Therefore, the scope of the invention is to be limited only by the following claims.