System for detecting abnormal movement of a shaft in a gas turbine engine

Abstract

A system (10) for detecting abnormal movement resulting from breakage of a shaft in a gas turbine engine. The system comprises a detection circuit including a frangible and brittle fuse portion (12) made from a conductive ceramic and a plunger (18) connected to or adjacent the frangible fuse portion, wherein the plunger may be displaced as a result of movement of the broken gas turbine shaft to break the frangible fuse portion (12) and thereby alter the detection circuit.

1 . A system for detecting abnormal movement resulting from breakage of a shaft in a gas turbine engine, the system comprising a detection circuit, the detection circuit including a frangible fuse portion and a plunger connected to or adjacent the frangible fuse portion, wherein the plunger may be displaced as a result of movement of the broken gas turbine shaft to break the frangible fuse portion and thereby alter the detection circuit, wherein the frangible fuse portion is conductive ceramic. 
     
     
         2 . The system according to  claim 1  wherein the conductive ceramic is a silicon carbide ceramic or the like. 
     
     
         3 . The system according to  claim 1  wherein the plunger ( 18 ) is insulating ceramic. 
     
     
         4 . The system according to  claim 3  wherein the plunger conductivity is approximately 1/1000 of the fuse conductivity. 
     
     
         5 . The system according to  claim 3  wherein the insulating ceramic is an alumina ceramic. 
     
     
         6 . The system according to  claim 1  wherein the fuse portion includes weakened portion or portions to facilitate breaking of the fuse at the weakened portion or portions. 
     
     
         7 . The system according to  claim 6  wherein the weakened portion or portions are surface notches ( 13 ) or surface defects. 
     
     
         8 . The system according to  claim 1  wherein the plunger is adjacent the frangible fuse portion and a plunger end portion adjacent the fuse is of narrower cross-section than the remainder of the plunger. 
     
     
         9 . The system according to  claim 8  wherein the plunger end portion is tapered. 
     
     
         10 . The system according to  claim 8  wherein the plunger end portion is a protrusion from a plunger body. 
     
     
         11 . A system for detecting abnormal movement resulting from breakage of a shaft in a gas turbine engine, the system comprising a detection circuit, the detection circuit including a frangible fuse portion and a plunger connected to or adjacent the frangible fuse portion, wherein the plunger may be displaced as a result of movement of the broken gas turbine shaft to break the frangible fuse portion and thereby alter the detection circuit, wherein the frangible fuse portion is conductive ceramic and the plunger is insulating ceramic. 
     
     
         12 . The system according to  claim 9  wherein the plunger end portion is a protrusion from a plunger body.