Collapsible support structure for a gas turbine engine

Patent metadata

Field	Value
Publication number	US-2016130975-A1
Application number	US-201514881471-A
Country	US
Kind code	A1
Filing date	Oct 13, 2015
Priority date	Nov 7, 2014
Publication date	May 12, 2016
Grant date	—

Abstract

Described is a shaft support system for a gas turbine engine comprising: a rotatable fan shaft; first and second support structures extending in parallel from the shaft to a load bearing structure to provide radial location of the shaft within an engine casing, wherein the first support and second support structures include first and second respective mechanical fusible joints; wherein the first fusible joint is a two-stage fuse which partially fails within a first predetermined load range, the second fusible joint fails within a second predetermined load range which is different to the first load range, and the first fusible joint fully fails only when the second fusible joint has failed.

First claim

1 . A shaft support system for a gas turbine engine comprising:
a rotatable fan shaft; first and second support structures extending in parallel from the shaft to a load bearing structure to provide radial location of the shaft within an engine casing, wherein the first support and second support structures include first and second respective mechanical fusible joints; wherein the first fusible joint is a two-stage fuse which partially fails within a first predetermined load range, the second fusible joint fails within a second predetermined load range which is different to the first load range, and the first fusible joint fully fails only when the second fusible joint has failed.

2 . A shaft support system as claimed in claim 1 , wherein the first support structure is a bearing chamber wall, and the second support structure is a bearing arrangement within a bearing chamber defined by the bearing chamber wall.

3 . A shaft support system as claimed in claim 1 , wherein first fusible joint fully fails under a third predetermined load range which is less than the second predetermined load range.

4 . A shaft support system as claimed in claim 1 , wherein the first fusible joint includes a slip joint and wherein the first load range causes the slip joint to slip.

5 . A shaft support system as claimed in claim 4 , wherein the first support structure includes first and second members compressibly connected by the slip joint.

6 . A shaft support system as claimed in claim 5 , wherein the slip joint includes a fastener to provide the compressible connection, and the fastener passes through an aperture in the first member for attachment to the second member, the aperture being over-sized in relation to the fastener such that the fastener will move within the aperture when a load threshold within the first predetermined load range is exceeded.

7 . A shaft support system as claimed in claim 1 wherein a bearing arrangement is connected to the shaft, and the second fusible joint is located between the bearing arrangement and the shaft.

8 . A shaft support system as claimed in claim 1 wherein the second fusible joint includes a male and female connection having a male part mateably received within a female part.

9 . A shaft support system as claimed in claim 8 , wherein the female part includes an annular recess in an end surface thereof, the recess being provided by a lip on the radial outer surface of the annular recess, the annular recess receiving and radially restricting the movement of the male part.

10 . A shaft support system as claimed in claim 9 , further comprising a catcher ring which is axial spaced aft of the bearing arrangement, wherein the lip extends axially, the axial extent of the lip being shorter than the separation between a catcher ring and bearing arrangement.

11 . A shaft support system as claimed in claim 1 wherein a bearing chamber wall extends in a radial and axial direction with the first fusible joint being provided along the length of the bearing chamber wall to define radially inner and outer bearing chamber walls which radially overlap when the first fusible link severs.

12 . A shaft support system as claimed in claim 1 wherein the shaft and a radially inner surface of a inner race are separated by a radial gap when the shaft is rotatably held on the principal axis of rotation, and wherein once the first and second fusible joints have severed, the shaft orbits within the gap and around the principal axis of rotation on the radially inner surface of the inner race.

13 . A support system as claimed in claim 1 , wherein the clearance of the aperture in the first fused connection is between 1.2 to 2 times the width of a bolt which holds the first fused connection together.

14 . A support system as claimed in claim 1 , wherein either or both of the first load range is between 20 and 90 kN and the second load range is between 800 kN and 1.2 MN.

15 . A support system as claimed in claim 3 , wherein the third predetermined range is between 300 kN and 500 kN.

16 . A gas turbine engine comprising the support structure of claim 1 .

Assignees

• Rolls Royce Plc

Inventors

• Chilton Nicholas Edward
• Barker Michael John

Classifications

• F05D2260/311

  of the frangible or shear type · CPC title

• F05D2240/60

  Shafts · CPC title

• F01D25/24

  Casings (modified for heating or cooling F01D25/14); Casing parts, e.g. diaphragms, casing fastenings (casings for rotary machines or engines in general F16M {; special arrangements in stators dealing with breaking-off of part of rotor F01D21/045}) · CPC title

• F05D2220/32

  in gas turbines · CPC title

• F05D2240/50

  Bearings · CPC title