WAVE GEAR SSPEED REDUCER AND VARIABLE TRANSMISSION RATIO STEERING DEVICE

PROBLEM TO BE SOLVED: To provide a wave gear speed reducer capable of further reducing vibration and a variable transmission ratio steering device using the same. SOLUTION: In this wave gear speed reducer, a flexible external gear 33 is partially meshed with a rigid internal gear 32 and a sub rigid internal gear 31, and the meshed position of these gears is circumferentially moved by rotating a wave generator to differentiate the rigid internal gear from the sub rigid internal gear. The inner surface of the rigid internal gear including the ridge line of the addendum 31T and the inner surface of the sub rigid internal gear including the ridge line of the addendum 31T are formed in conical surfaces symmetrically reduced or increased in diameter. The outer surface of the flexible external gear including the ridge line of the addendum 33T is formed in an elliptic cylindrical surface parallel to the axial direction. The flexible external gear is so elastically deformed so that the elliptic cylindrical surface is tilted along the conical surface at the meshed portions of the flexible external gear with the rigid internal gear and the sub rigid internal gear. COPYRIGHT: (C)2009,JPO&INPIT