Measurement of ball motion in a ball-type limited slip differential gear

Measurement of ball motion in a new-type limited slip differential gear for automobiles is carried out, differential gear which is under development by Hitachi Metals, Ltd. based on a new principle with steel balls and races having an ad-hoc configured race pattern. One ball in the differential gear is magnetized and the direction of magnetic axis rotating with the ball is traced by Hall sensors assembled in orthogonal three axes around the ball. Output signals from the sensors are plotted in orthogonal projections to the three axes, offering a clear understanding of the ball motion. Expressions for calculating the angular velocity components of ball motion are deduced and the ball motion is numerically analyzed from the data obtained in the measurement. The results demonstrate complicated ball behaviors, which include important information on slip between the ball and the groove surfaces affecting the durability and life of the system.