Convolution ball forma differential reduction gear

摘要

PURPOSE:To secure a high reduction ratio while maintaining the compactness of the whole device by rolling balls between a first and second power plates disposed opposite to each other, and absorbing the component of the revolving motion of the second power plate, and taking out only the component of the autorotational motion of the second power plate using a motion adjusting member. CONSTITUTION:When an input portion 11 is driven, an eccentric shaft 8 is rotated and an eccentric portion 8a transmits eccentric rotating forces to a second power plate 6. Then the second power plate 6 rotates around its axis whole being accompanied by the sliding rotation of a rolling ball 17 within a circular hole 16a and by the rolling displacement of the rolling ball 17 along the guide groove 15 of a first power plate 4, and is displaced by rotation around the eccentric portion 8a. With such combined motion, a motion adjusting ball 20 rolls along and inside the respective annular grooves 18, 19 of the second power plate 20 and a motion adjusting plate 12. Accordingly, the component of the revolving displacement of the second power plate 6 is absorbed and only the torque of the autorotational component of the plate 6 is transmitted to the motion adjusting plate 12. Then sped reduction ratio is obtained by the inverse 1/11 of the number (11) of the rolling balls 17 arranged.