WAVE GEAR DEVICE HAVING THREE-DIMENSIONALLY CONTACTING INVOLUTE POSITIVE SHIFTED TOOTH PROFILE

摘要

In a wave gear device (1), an involute tooth profile with the low pressure angle a (< 20°) is employed as a basic tooth profile of external teeth (11) of a flexible external gear (3). In the principal section (20) of the external teeth (11), the tooth depth thereof satisfies 2?0mn = 2(1 + c) mn (deflection coefficient ?0 = 1 + c, 0 < c < 0.5), which is larger than the standard one. The shifting of the teeth which takes into account coning is performed along the tooth trace direction of the external teeth (11), so that straight portions of a rack tooth profile on the respective sections perpendicular to the axis in the tooth trace direction of the external teeth (11) are conformed as viewed along the tooth trace direction. The rack tooth profile of the involute tooth profile is a straight line, and hence it is possible to attain a tooth profile enabling continuous meshing that takes into account of the coning of the tooth over the entire tooth trace of both a gear (2) and the gear (3).