Measurement of torsional dynamics of rotating shafts using magnetostrictive sensors

Abstract

A device and method for the non-contact measurement of dynamic torsion in a rotating shaft using magnetostrictive sensors (MsS). The monitoring and detection system have specially configured magnetostrictive signal detectors that include inductive pickup coils, in which signals corresponding to localized shaft torques are induced. The non-contact method for measuring dynamic torques includes fixing a ferromagnetic strip to a ferromagnetic or non-ferromagnetic shaft and inducing a circumferential residual magnetization therein. An MsS in the form of either an encircling coil positioned around the shaft on a cylindrical substrate, or a partially encircling coil positioned on a flexible substrate and wrapped partially about the shaft.

1 . A system for measuring dynamic torques in a rotating shaft, the system comprising: 
 (a) a ferromagnetic strip positioned and affixed circumferentially around a portion of said shaft, said ferromagnetic strip having a circumferential residual magnetization therein;    (b) a magnetostrictive sensor positioned in stationary spaced proximity to said rotating shaft adjacent said ferromagnetic strip, said sensor comprising a detection coil, said detection coil having an induced voltage therein indicative of a magnetic flux change within said ferromagnetic strip positioned on said rotating shaft;    (c) means for receiving, amplifying and filtering a signal from said magnetostrictive sensor; and    (d) means for analyzing said signal and determining a quantitative value for said dynamic torques, wherein said dynamic torques generate said magnetic flux changes within said ferromagnetic strip detectable by said magnetostrictive sensor.    
   
   
       2 . The system of  claim 1  wherein said magnetostrictive sensor comprises a coil positioned on a cylindrical substrate fully encircling said shaft above said ferromagnetic strip.  
   
   
       3 . The system of  claim 1  wherein said magnetostrictive sensor comprises a coil positioned on a flexible substrate strip partially encircling said shaft above said ferromagnetic strip.  
   
   
       4 . The system of  claim 1  wherein said ferromagnetic strip comprises a thin, flexible strip of ferromagnetic material affixed to said shaft by means of an adhesive.  
   
   
       5 . The system of  claim 1  wherein said ferromagnetic strip comprises a thin layer of ferromagnetic material affixed to said shaft by means of plating.  
   
   
       6 . The system of  claim 1  further comprising a fixed magnet positioned adjacent said magnetostrictive sensor and said ferromagnetic strip to facilitate the maintenance of said circumferential residual magnetization within said ferromagnetic strip.  
   
   
       7 - 12 . (canceled)