Patent ID: 6661222
Filing Date: 2003-12-09
Classification: G01B

Abstract:
A system for monitoring the clearance between a plurality of turbine blades and a stationary portion of the turbine, comprising:sensor means having an exterior tubular support structure with an axial dimension, that supports a centrally disposed drive shaft that is reciprocally mounted within the support structure to move along the axis thereof, said sensor means positioned within said stationary portion of the turbine and aligned so that the reciprocal movement of the drive shaft moves a forward end of the drive shaft, closest to the turbine blades, towards and away from the turbine blades; a proximity sensor that is responsive to being positioned substantially a preselected distance from the turbine blade to provide a given output representative of the preselected distance, supported at the forward end of and coupled to said drive shaft so that said proximity sensor moves with the drive shaft; a motor coupled to said drive shaft and operable to move said drive shaft a given distance either towards or away from the turbine blades and responsive to such movement to provide a position output from which the sensor position can be determined relative to its distance from a predetermined calibration point; and means for monitoring the sensor output and controlling the motor movement, so the sensor is substantially positioned the preselected distance from the blade determined by monitoring for the given output, and for monitoring the position output to determine the distance of the blade from the calibration point.