減速装置

摘要

It is desired to reduce vibration of a speed reducer. The speed reducer includes a fixed internal gear (3), an input shaft (7) coaxial with the internal gear (3), and an eccentric disk (9) provided on the input shaft (7) and rotatable inside the internal gear (3). A cage (14) is provided at an end of an output shaft (12) coaxial with the input shaft (7) so as to be rotatable between the internal gear (3) and the eccentric disk (9). The cage (14) is formed with pockets (18) which are fewer in number than the internal teeth (4) of the internal gear (3). Rollers (19) are received in the respective pockets (18) such that when the input shaft (7) is rotated once, and the eccentric disk (9) is rotated together with the input shaft, each of the rollers (19) is pushed by the rolling bearing (11) fitted on the eccentric disk (9) and circumferentially moves by a distance equal to the width of one internal tooth (4) while kept in meshing engagement with the internal tooth (4), causing the output shaft to be rotated at a reduced speed. The root radius of the internal gear (3), the radius of the circumcircle of the rolling bearing (11), the circumcircle having a center lying on the center axis of the input shaft (7), and the outer diameter of the rollers (19) are measured beforehand, and determined such that the smallest one of roller gaps (20) defined between the rollers (19) and the tooth bottoms of the internal gear (3) are controlled to reduce vibration.