Noncontact Miniature Torque Sensor for Automotive Application

A noncontact torque sensor has been developed for use in engine control systems. The sensor detects torque-induced changes in magnetic properties of the engine crankshaft.

A miniature version of the sensor, mounted on a 1980 Chevrolet V-6 engine, is described. Sensor installation requires 22 mm of crankshaft space and a 1.0 mm air gap between sensor and crankshaft is utilized. For a variation of engine torque from −100 to 240 N·m, the sensor generates a linear signal which varies from −25 to 60 mV; amplification is used to provide an output signal of −500 to 1200 mV. A signal processor associated with the sensor is calibrated to give a torque sensitivity of 5 mV/N·m and it also includes an active filter with a low-pass cutoff frequency of 5 Hz.

In its present state of development, torque measurement accuracy of the sensor is limited to approximately ±10 percent due to interfering effects of temperature, air gap variation, and engine speed sensitivity. Further investigation will be necessary to establish the ultimate performance potential of the sensor.