Geared turbofan engine with inter-shaft deflection feature

Abstract

A disclosed gas turbine engine includes a compressor section including a first compressor disposed axially forward of a second compressor, a combustor in fluid communication with the compressor section and a turbine section in fluid communication with the combustor. The turbine section includes a first turbine driving the first compressor and a second turbine driving the second compressor. An inner shaft defines a driving link between the second compressor and the second turbine and an outer shaft defines a driving link between the first compressor and the first turbine. The inner shaft and the outer shaft are concentric about a common axis of rotation. A bumper is disposed on the inner shaft within an axial region common to an aft portion of the outer shaft for accommodating interaction between the inner and outer shafts during high load conditions.

What is claimed is: 
     
         1 . A turbine engine comprising:
 a compressor section including a first compressor section and a second compressor section;   a turbine section including a first turbine section driving the first compressor section through an inner shaft and a second turbine section driving the second compressor section through an outer shaft;   a fastening member attached to an aft end of the outer shaft; and   a bumper located between the inner shaft and the outer shaft for accommodating interaction between the inner shaft and the outer shaft, the aft end of the outer shaft disposed annularly about the bumper and the fastening member disposed within an axial length disposed at least partially about the bumper.   
     
     
         2 . The turbine engine as recited in  claim 1 , wherein the bumper comprises a portion of one of the inner and outer shafts. 
     
     
         3 . The turbine engine as recited in  claim 1 , wherein the bumper comprises a portion of the inner shaft. 
     
     
         4 . The turbine engine as recited in  claim 3 , wherein the bumper comprises a bumper diameter greater than diameters of the inner shaft surrounding the bumper diameter. 
     
     
         5 . The turbine engine as recited in  claim 4 , wherein a ratio of the bumper diameter to the surrounding inner shaft diameter is between about 1.032. 
     
     
         6 . The turbine engine as recited in  claim 5 , wherein the inner shaft includes a flange extending radially outward of the bumper and spaced apart axially aft of the aft end of the outer shaft. 
     
     
         7 . The turbine engine as recited in  claim 6 , including a plurality of fan blades rotatable about an axis and driven by the turbine section through a geared architecture. 
     
     
         8 . The turbine engine as recited in  claim 7 , wherein the first turbine section includes no more than 6 turbine rotors, the second turbine section includes no more than two turbine rotors and the inner shaft is coupled to the geared architecture. 
     
     
         9 . The turbine engine as recited in  claim 8 , wherein a ratio of the bumper diameter to the axial length is between 3.00 and 4.00. 
     
     
         10 . A gas turbine engine comprising:
 a compressor section including a first compressor and a second compressor;   a turbine section including a first turbine driving the first compressor and a second turbine driving the second compressor;   an inner shaft defining a driving link between the second compressor and the second turbine;   an outer shaft defining a driving link between the first compressor and the first turbine, wherein the inner shaft and the outer shaft are concentric about a common axis of rotation;   a bearing assembly supporting rotation of the outer shaft;   a fastener securing a portion of the bearing assembly on the outer shaft; and   a bumper disposed on the inner shaft within an axial region common to an aft portion of the outer shaft for accommodating interaction between the inner and outer shafts.   
     
     
         11 . The gas turbine engine as recited in  claim 10 , wherein the inner shaft includes a first diameter within the axial region on either side of the bumper and the bumper comprises a bumper diameter larger than the first diameter. 
     
     
         12 . The gas turbine engine as recited in  claim 11 , wherein a ratio of the bumper diameter to the first diameter is between about 1.032. 
     
     
         13 . The gas turbine engine as recited in  claim 11 , wherein the outer shaft includes a threaded outer diameter for receiving the fastening member within the axial region. 
     
     
         14 . The gas turbine engine as recited in  claim 13 , wherein the inner shaft includes a radially extending flange that is disposed aft of the bumper and the axial region. 
     
     
         15 . The gas turbine engine as recited in  claim 14 , wherein the bumper is continuous about a circumference of the inner shaft within the axial region. 
     
     
         16 . The gas turbine engine as recited in  claim 15 , wherein a ratio of the bumper diameter to a length of the axial region is between 3.00 and 4.00. 
     
     
         17 . A method of assembling a gas turbine engine comprising:
 supporting an inner shaft about an axis of rotation; and   supporting an outer shaft concentric with the inner shaft about the axis of rotation with a bearing assembly; and   securing a portion of the bearing assembly with a fastener attached to the outer shaft, wherein the outer shaft includes an aft portion and the inner shaft includes a bumper diameter within an axial region common with the aft portion of the outer shaft, wherein the bearing assembly is spaced apart from the axial region and the fastener is at least partially disposed within the axial region and the bumper diameter is greater than a diameter of the inner shaft disposed on either axial side of the bumper diameter.   
     
     
         18 . The method as recited in  claim 17 , wherein a ratio of the bumper diameter to the diameter of the inner shaft disposed on either axial side of the bumper diameter is about 1.032. 
     
     
         19 . The method as recited in  claim 17 , wherein the fastening member is axially aligned with the bumper diameter. 
     
     
         20 . The method as recited in  claim 19 , including forming the bumper diameter according to a ratio of the bumper diameter to a length of the region to be between 3.00 and 4.00.