Abstract:
A gas turbine engine includes a bearing. A bearing support includes a first wall that extends between the first and second ends and is operatively supported by the bearing at a first end. An engine case is secured to the second end radially outward of the first end. A flexible support is provided by a second wall integral with and extending transversely from the first wall. The second wall has a first flange and a gear train component is secured to the first flange.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This disclosure is a continuation of U.S. patent application Ser. No. 12/785,537 filed May 24, 2010. 
    
    
     BACKGROUND 
     This disclosure relates to a gas turbine engine having a gear train used to drive a fan, and more particularly, the disclosure relates to structure used to support a portion of the gear train relative to a main bearing. 
     A main bearing is used to rotationally support a compressor rotor and input coupling. In a turbine engine having a gear train, which is used to drive a fan, the same main bearing may be used to rotationally support a gear train component. The gear train component is “soft mounted” to enable the gear train to deflect relative to the main bearing during engine operation. This deflection minimizes gear and bearing stresses by reducing the overall forces exerted within the fan drive system. 
     In one example arrangement, a main bearing support extends from the main bearing to the engine case. The “soft mount” is provided by a separate flexible structure that includes a steel outer disc that is bolted to the main support where it attaches to the engine case, providing a joint with three flanges. In one example, the main bearing support is constructed from titanium. The flexible support is provided by a stamped steel plate that is welded to a steel inner disc and the outer disc. A torque frame of the gear train is bolted to the inner disc plate. 
     SUMMARY 
     In one exemplary embodiment, a gas turbine engine includes a bearing. A bearing support includes a first wall that extends between first and second ends and is operatively supported by the bearing at a first end. An engine case is secured to the second end radially outward of the first end. A flexible support is provided by a second wall integral with and extending transversely from the first wall. The second wall has a first flange and a gear train component is secured to the first flange. 
     In a further embodiment of the above, the second wall intersects the first wall at a location spaced from the second end and the engine case. The gear train component is a torque frame. 
     In a further embodiment of any of the above, the first end provides a first support that has a surface with a first radius. A centering spring supports the bearing and is secured to the surface. The first flange has a second radius that is larger than the first radius to accommodate the centering spring during an assembly procedure. 
     In a further embodiment of any of the above, the first and second ends and the first flange each include multiple holes that are configured to receive centering spring fasteners secured respectively to the centering spring, the engine case and the torque frame. 
     In a further embodiment of any of the above, a centering spring supports the bearing. A main support is secured to the first end and the centering spring with fasteners. 
     In a further embodiment of any of the above, the first end includes a seal flange that extends in an axial direction and is radially outward of the main support. One of the main support and the seal flange includes a recess having a seal disposed therein and seals against the other of the main support and seal flange. 
     In a further embodiment of any of the above, the main support is constructed from a first material and the bearing and flexible supports are constructed from a second material. 
     In a further embodiment of any of the above, the first material is aluminum and the second material is titanium. 
     In another exemplary embodiment, a method of manufacturing a gas turbine engine includes providing bearing support that has a first wall that extends between first and second ends and a second wall integral with the first wall. The method also includes securing an engine case to the second end, securing a torque frame to a flange provided on the second wall, mounting a bearing to a centering spring, axially inserting the centering spring and bearing through the torque frame and securing the centering spring to the first end subsequent to securing a torque frame to a flange provided on the second wall. 
     In a further embodiment of the above, the method includes the steps of mounting an input coupling to the bearing, sliding the input coupling onto a hub and securing a nut to the hub to axially retain the input coupling on the hub. 
     In a further embodiment of any of the above, the method includes the steps of mounting an input gear on the input coupling and mounting a plate supporting intermediate gears onto the torque frame. 
     In a further embodiment of any of the above, the method includes providing a pocket between the first and second walls, and machining the pocket. 
     In a further embodiment of any of the above, the method includes providing first and second portions that respectively provide the second and first ends. The second portion includes the second wall and a portion of the first wall. The first and second portions are secured by a weld bead along the first wall. 
     In a further embodiment of any of the above, the method includes at least one of casting or forging the bearing support. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a schematic cross-sectional view of an example geared turbofan engine. 
         FIG. 2  is an enlarged cross-sectional view of the engine shown in  FIG. 1  illustrating one example integrated gear and bearing support. 
         FIG. 3  is an enlarged cross-sectional view of the engine shown in  FIG. 1  illustrating another example integrated gear and bearing support. 
     
    
    
     DETAILED DESCRIPTION 
     A geared turbofan engine  10  is illustrated in a highly schematic fashion in  FIG. 1 . Engine  10  includes a fan section  12  arranged within a fan case  14 . The fan section  12  includes multiple blades arranged at an inlet  18  of the fan case  14 . A core  20  is supported relative to the fan case  14  by flow exit guide vanes  21 . The core  20  includes a low pressure compressor section  22 , a high pressure compressor section  24 , a combustor section  26 , a high pressure turbine section  28  and a low pressure turbine section  30 . In one example, the low pressure compressor section  22  and low pressure turbine section  30  are supported on a low spool  34  rotatable about an axis A. The high pressure compressor section  24  and high pressure turbine section  28  are supported on a high spool  32  rotatable about the axis A. 
     In the example engine  10 , a gear train  36  is arranged between the low spool  34  and the fan section  12  to rotationally drive the fan blades  16  at a desired rotational speed that is lower than the low spool rotational speed. Referring to  FIG. 2 , the gear train  36  includes an input gear  38  that is operatively coupled to the fan section  12  (shown in  FIG. 1 ). A ring gear  42  is coupled to a member  44 , which rotationally drives the fan section  12  via multiple intermediate gears  40  arranged about the input gear  38  and intermeshed with the input gear  38  and the ring gear  42 . Other epicyclic gear configurations may be used. 
     A torque frame  46  is operatively coupled to a case  48  of the core  20  for fixing the intermediate gears  40  against rotation. The torque frame  46  includes fingers that are illustrated by dashed lines in  FIGS. 2 and 3 . The fingers support a carrier  47  to which the intermediate gears  40  are mounted. 
     The low spool  34  rotationally drives compressor blades  50  in one or more stages of the low pressure compressor section  22 . An input coupling  52  is rotationally supported relative to the low spool  34  by a main bearing  58 , which is a ball bearing in one example. The input coupling  52  axially extends from the main bearing  58  to the input gear  38 , which is splined to an end of the input coupling  52 . The input coupling  52  is mounted to a hub  54 , which is part of the low spool  34 , and retained thereto by a nut  56 . 
     An inner race  60  of the main bearing  58  is mounted to the input coupling  52 , and an outer race  62  of the main bearing  58  is mounted to a centering spring  64 . A main bearing support  66 , which comprises a portion of the core support structure, is affixed to the centering spring  64 . In the example illustrated, the frustoconical main bearing support  66  includes a first support  68  at a first end, and the centering spring  64  includes a centering spring flange  70  that engages the first support  68 . In one example, the first support  68  includes a surface having a radius sized to accommodate the centering spring flange  70 , which has a first radius R 1 . Multiple flange fasteners  72  are received in holes  69 , secure the centering spring flange  70  to the first support  68 . 
     A flexible support  74  is integral with the main bearing support  66 , and are cast or forged from titanium, for example. By “integral” it is meant that the flexible support  74  and main bearing support  66  are permanently affixed to one another, rather than removably affixed such as by fasteners. By “permanently affixed” it is meant that destructive means such as cutting would be required to separate the flexible support  74  and main bearing support  66 . The torque frame  46  includes a second flange  84  that is secured to a first flange  82  of the flexible support  74  by fasteners  86 . The joint provided by the first and second flanges  82 ,  84  have a second radius R 2  that is large enough to accommodate the centering spring flange  70  (and its first radius R 1 ) during assembly. 
     The main bearing support  66  includes a first wall  76 , and the flexible support  74  includes a second wall  78  that is spaced apart from the first wall  76  to provide a pocket  80 . The first and second walls  76 ,  78  are integral with one another to provide the integrated flexible support  74  and main bearing support  66 . Drain holes  87  are provided in at least one of the main bearing support  66  and the flexible support  74  and in communication with the pocket  80  to prevent oil from collecting within the pocket  80  during operation. 
     The first wall  76  of the main bearing support  66  extends from the first support  68  to a second support  88  at a second end of the main bearing support  66 . The case  48  includes a case flange  90  that is secured to the second support  88  with second support fasteners  92  received by holes  91 . A recess  94  is provided in one of the main bearing support  66  and the rotor  48 . A seal  96  is disposed in the recess  94  to provide a seal between the rotor  48  and the main bearing support  66 . 
     Another integrated main bearing support  166  and flexible support  174  is shown in  FIG. 3 . The low pressure compressor section  122  is rotationally driven with the low spool  134  within the core  120 . The member  144 , mounted to the ring gear  142 , is rotationally driven by the input gear  138  via the intermediate gears  140 . The intermediate gears  140  are retained in their circumferential position by the carrier  147  and torque frame  146 . 
     The first wall  176  in the example is provided by first and second portions  198 ,  200 . The first and second portions  198 ,  200 , respectively include first and second edges  102 ,  104  that are secured to one another by a weld  106  or similar manufacturing/affixing method. Providing the first and second portions  198 ,  200  as two parts enables the pocket  180  to be machined more easily. Machining of the pocket  180  is desirable to obtain the desired wall thickness for the first and/or second walls  176 ,  178  for balance and strength of the structure in that area. First flange  182  of the second wall  178  is secure to the second flange  184  of the torque frame  146 . Forming the first and second walls  176 ,  178  during a near-net forging operation may avoid the need to machine the pocket  180 , for example. The drain holes  187  may be machined or cast, for example. 
     The main bearing support  166  is provided by an intermediate support  197  and a separate main support  108  that is supported by the main bearing  158  and secured to the centering spring  164 . The intermediate support  197  includes an intermediate flange  210  that is mounted to and secured between the main support  108  and the centering spring  164  in the example shown. In one example, the main bearing support  166 , flexible support  174  is constructed from titanium and the main support  108  is constructed from aluminum. A nickel alloy may also be used, for example. A seal flange  102  extends from the intermediate support  197 . A recess  214  is provided in the main support  108  and receives a seal  216  that engages the seal flange  212 . 
     During assembly, the case flange  190  of the case  148  is secured to the main bearing support  166  at the second support  188  by fasteners  192 . The input coupling  152 , main bearing  158  and centering spring  164  are assembled to one another. This assembly is installed onto the hub  154  with the main bearing support  166  in place to facilitate assembly, the centering spring  164  outer diameter R 1  (and corresponding surface provided by the first support  168 ) is smaller than the joint inner diameter R 2  of the torque frame/first flange joint. The centering spring  164  is secured to the main bearing support  166  with the flange fasteners  172  at the centering spring flange  170  and the input coupling  152  is secured to the hub  154  with the nut  156 . The torque frame  146  is secured to the flexible support  174  with the fasteners  186 . The gear train  136  is splined or affixed onto the input coupling  152 . Assembly of the arrangement illustrated in  FIG. 2  is similar to that described above in relation to the arrangement of  FIG. 3 . 
     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 the claims. For that reason, the following claims should be studied to determine their true scope and content.