Development of aliasing type reducer

An aliasing type reducer, which fulfils both a high reduction ratio and low vibration in a thin and small body, had been proposed to cope with the further downsizing of DC motors. This reducer consists of two disks with sinusoidal grooves of the same amplitude but different periods, bearing balls rolling in grooves, and a disk with oval holes formed at equal intervals around the circumference through which the bearing balls can move radially. The two grooved disks sandwich the disk with bearing balls in its oval holes, and the bearing balls are held at the intersections of the two types of grooves. The disk with the groove of larger period works as the input plate, the disk with the oval holes as the output plate, and the other grooved disk as the stator, respectively. The reduction mechanism is inspired by the "sampling theorem." As the input plate rotates, the bearing balls engaged with each groove reciprocate radially within the oval holes, decelerating the output plate and rotating it in the same direction as the input plate. It is confirmed that the prototype has extremely small output torque fluctuation during power transmission, and that the idling torque is as small as that of a planetary gear reducer. However, the torque transmission efficiency is only 70%, which is significantly lower than that of a planetary gear reducer. This is thought to be due to the slip friction between the bearing balls and the grooves, and is a forthcoming challenge.