Torque Sensor based on Magnetostrictive Effect for Automobile Engine

Abstract

A miniature torque sensor based on magnetostrictive effect, has been developed to be mounted inside an automobile engine (TOYOTA 4A-FE; 1.6-liter 4-cylinder). The sensor was installed in a last main bearing of the engine crankshaft so as to directly detect the torque generated by engine. This sensor was composed of two magnetic head-type elements, which were placed opposite to each other through the crankshaft in order to eliminate the influence of the off-center motion of the shaft on the sensor output. Furthermore, a commercial crankshaft made of cast nodular iron (JIS standard: FCD70) was adopted, taking account of high sensor sensitivity and mechanical stiffness. It was confirmed by tests on an engine-dynamometer arrangement that this sensor could clearly detect instantaneous torque waveform with four peaks during two crankshaft rotations, corresponding to four cylinder combustions, and peculiar torque fluctuation due to engine lean burn. In addition, it was found that true torque produced by engine could be detected in in-vehicle experiment. This sensor is useful for various automobile applications. © 1996, The Institute of Electrical Engineers of Japan. All rights reserved.