Gm Global Technolgoy Operations, Inc.

Societe Nationale D'etude Et De Construction De Moteurs D'aviation

Ayoub Chakari

Hamid Vahabzadeh

Patrick Meyrueis

Michel Clement

Eric Gaumont

Presented herein is a non-contact torque sensing apparatus and method for measuring the instantaneous torque, or torsional stress/strain, transmitted through an elongated power transmission member such as a rotatable shaft. Polarized light is directed along a measurement light path in a cavity of a shaft where it intercepts a polarizing filter. The polarizing filter is operable to alter the polarization angle of the light according to torsional twisting of the shaft. A measurement device measures the change in the polarization angle of the light to obtain the shaft twist angle. Shaft torque is then calculated from the twist angle.

Laser sensor apparatus and method for detecting transmission shaft torque

An optical-fiber polarimetric sensor for measuring the displacement of an object relative to a frame, the sensor comprising a measurement optical fiber secured, over a fraction of its length, both to a central point of the object and to first and second fixed points of the frame, means disposed at one end of the measurement fiber and serving to emit a light beam of determined polarization into said measurement fiber, means for exerting twist on the measurement fiber so as to modify the polarization of the light beam, and means disposed at another end of the measurement fiber and serving firstly to detect the resulting light beam and secondly to determine the displacement of the object by analyzing the polarization modified in this way, wherein said measurement fiber is stripped, over said fraction of its length, of the covering that imparts mechanical strength thereto, and it is slid into a deformable guide sheath fixed both to the rotary object and also to the frame. Preferably, the deformable guide sheath is made of fine steel, and it may lined with a flexible protective sheath.

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Strasbourg, France

Ayoub Chakari