Starter/generator

Abstract

A starter generator located within a sump region of a turbofan engine and coupled to an adapter shaft. The adapter shaft rotationally coupled to the high pressure shaft, forward of a high pressure shaft bearing, and secured by a spanner nut. The engine makes use of two pluralities of electrical conductors, the first extends through an electrical conduit defined by a forward strut extending from the sump region to the outward casing, the second extends axially away from the electric starter. Each of the first plurality of electrical conductors makes reversible contact with a respective one of the second plurality of electrical conductors via an elbow/pin connector, producing a tight turn in area of limited space.

What is claimed is: 
     
         1 . A gas turbine engine comprising:
 A high pressure spool and a low pressure spool, the low pressure spool including a low pressure shaft operably connected to a fan, the high pressure spool including a high pressure shaft operably connected to a high pressure turbine, the low pressure shaft and the high pressure shaft being co-axial with one another;   a sump region axially concurrent with a forward portion of the low pressure shaft and located axially forward a forward most portion of the high pressure shaft, the sump region defined radially between the forward portion of the low pressure shaft and an inner boundary of an air inlet passage;   a high pressure shaft bearing;   an adapter shaft forward of the high pressure shaft bearing rotational coupled to the high pressure shaft, the adapter shaft having an outer diameter greater than the outer diameter of the high pressure shaft   a rotor of an electric starter generator coupled to the adapter shaft;   a spanner nut concentric with the adapter shaft and the high pressure shaft securing the adapter shaft to the high pressure shaft.   
     
     
         2 . The gas turbine of  claim 1 , wherein the adapter shaft comprises:
 a cylinder having an upstream end and a downstream end, the cylinder having an outer diameter, the outer diameter greater than the outer diameter of the turbine shaft; the outer cylinder having a radially outer surface;   a radial flange connected to one of the upstream end or downstream end, the flange extending radially inward from the outer cylinder to define a bore hole, the bore hole having an inter diameter less the outer diameter of the high pressure shaft; the outer surface of cylinder defining an integral a rib at the downstream end, the rib extending radially from the outer surface,   wherein the spanner nut axially retaining the radial flange with respect to the high pressure shaft and the high pressure shaft has an axial facing surface restricting rearward axial movement of the adaptor shaft; and   wherein the electric rotor is attached to the outer surface of the cylinder; wherein the rib axially seats the electric rotor.   
     
     
         3 . The gas turbine of  claim 2 , wherein the low pressure shaft having an outer diameter less than or equal to an inner diameter of the high pressure shaft; the high pressure shaft bearing being axially restrained by the radial flange, the radial flange located on the downstream end of the cylinder. 
     
     
         4 . The gas turbine of  claim 1 , wherein the adapter shaft comprises:
 a cylinder having an upstream end and a downstream end, the cylinder having an outer diameter, the outer diameter greater than the outer diameter of the low pressure shaft; the outer cylinder having a radially outer surface;   a radial flange connected to the upstream end, the flange extending radially inward from the outer cylinder to define a bore hole, the bore hole having an inter diameter less the outer diameter of the low pressure shaft; the outer surface of cylinder defining an integral a rib at the downstream end, the rib extending radially from the outer surface,   wherein the spanner nut axially retaining the radial flange with respect to the low pressure shaft and the low pressure shaft has an axial facing surface restricting rearward axial movement of the adaptor shaft; and   an electric rotor is attached to the outer surface of the cylinder; wherein the rib axially seats the electric rotor.   
     
     
         5 . The gas turbine of  claim 4 , wherein the high pressure shaft having an inner diameter greater than the outer diameter of the low pressure shaft and the radial flange is located on the upstream end of the cylinder. 
     
     
         6 . The gas turbine of  claim 3 , further comprising a groove on the outer surface of the cylinder and a retaining ring within the groove upstream of the electric rotor and axially restraining the electric rotor. 
     
     
         7 . The gas turbine of  claim 5 , further comprising a groove on the outer surface of the cylinder and a retaining ring within the groove upstream of the electric rotor and axially restraining the electric rotor. 
     
     
         8 . The gas turbine of  claim 3 , further comprising an electric starter generator within the forward sump of the gas turbine, wherein a stator of the electric starter generator is rotationally fixed to with respect to a casing of the gas turbine. 
     
     
         9 . The gas turbine of  claim 3 , further comprising an electric starter generator within the forward sump of the gas turbine, wherein a stator of the electric starter generator is rotationally fixed to the low pressure shaft. 
     
     
         10 . The gas turbine of  claim 2 , further comprising a tie bolt extending through the high pressure shaft. 
     
     
         11 . A method for assembling a gas turbine engine having a high pressure spool and a low pressure spool, each having a respective shaft, comprising:
 sliding a high pressure shaft bearing concentric with the high pressure shaft over the high pressure shaft;   seating the high pressure shaft bearing between a fixed support structure and the high pressure shaft;   sliding an adapter shaft over the high pressure shaft,   rotationally coupling the adapter shaft to the high pressure shaft and   axially restraining the high pressure shaft bearing with a downstream end of the adapter shaft;   rotating a spanner nut to restrain the adapter shaft and the high pressure shaft bearing via the adapter shaft.   
     
     
         12 . The method of  claim 11 , wherein the spanner nut is threaded onto the high pressure shaft. 
     
     
         13 . The method of  claim 11 , wherein the spanner nut is threaded onto a tie bolt radially inward of the high pressure shaft. 
     
     
         14 . The method of  claim 11 , wherein the step of rotationally coupling the adapter shaft to the high pressure shaft comprises mating splines on the adapter shaft with respective spline on the high pressure shaft. 
     
     
         15 . The method of  claim 11 , wherein the adaptor shaft comprises:
 a cylinder having an upstream end and a downstream end, the cylinder having an outer diameter, the outer diameter greater than the outer diameter of the turbine shaft; the outer cylinder having a radially outer surface;   a radial flange connected to one of the upstream end or downstream end, the flange extending radially inward from the outer cylinder to define a bore hole, the bore hole having an inter diameter less the outer diameter of the high pressure shaft; the outer surface of cylinder defining an integral a rib at the downstream end, the rib extending radially from the outer surface,   wherein the spanner nut axially retaining the radial flange with respect to the high pressure shaft and the high pressure shaft has an axial facing surface restricting rearward axial movement of the adaptor shaft; and   wherein an electric rotor is attached to the outer surface of the cylinder; wherein the rib axially seats the electric rotor.   
     
     
         16 . An adaptor shaft assembly for a gas turbine engine comprising:
 a turbine shaft having an upstream the terminal end;   a cylinder having an upstream end and a downstream end, the cylinder having an outer diameter, the outer diameter greater than the outer diameter of the turbine shaft; the outer cylinder having a radially outer surface;   a radial flange connected to one of the upstream end or downstream end, the flange extending radially inward from the outer cylinder to define a bore hole, the bore hole having an inter diameter less the outer diameter of the turbine shaft; the outer surface of cylinder defining an integral a rib at the downstream end, the rib extending radially from the outer surface,   a spanner nut axially retaining the radial flange with respect to the turbine shaft wherein the turbine shaft has an axial facing surface restricting rearward axial movement of the adaptor shaft; and   an electric rotor rotationally attached to the outer surface of the cylinder; wherein the rib axially seats the electric rotor.   
     
     
         17 . The adaptor shaft assembly of  claim 16 , further comprising a low pressure shaft, the low pressure shaft coaxial with the turbine shaft and having an outer diameter less than an inner diameter of the turbine shaft; a turbine shaft bearing downstream of the adaptor shaft and axially restrained by the radial flange, the radial flange located on the downstream end of the cylinder. 
     
     
         18 . The adaptor shaft assembly of  claim 16 , further comprising a high pressure shaft coaxial with the turbine shaft, the high pressure shaft having an inner diameter greater than the outer diameter of the turbine shaft, wherein the radial flange is located on the upstream end of the cylinder.