Shaft drive

Abstract

Wave gear (30) comprising: an annular first rigid, internally toothed gear (31); a flexible, externally toothed gear (33) arranged coaxially within the first rigid, internally toothed gear (31); a wave generator (37) to cause the flexible, externally toothed gear (33) to bend in a non-circular manner in order to bring the external teeth (34) of the flexible, externally toothed gear (33) partially into circumferential engagement with the internal teeth (35) of the first rigid, internally toothed gear (31) and to generate a relative rotation between the gears (31, 33) by moving the engagement positions of the gears (31, 33) circumferentially; and a compound rolling bearing (38) for supporting the first rigid, internally toothed gear (31) and the flexible, externally toothed gear (33) in a state which allows the two gears (31, 33) to rotate against each other;wherein the first rigid, internally toothed gear (31) has a first end face (44) and a second end face (45) which are opposite each other in the direction of a central axis of rotation (30a) of the wave gear (30) and extend in a direction perpendicular to the central axis of rotation (30a), as well as a circular outer circumferential surface (46) and a circular inner circumferential surface (47) which are arranged between the first end face (44) and the second end face (45), wherein the internal toothing (35) is formed on the circular inner circumferential surface (47);the composite rolling bearing (38) has an inner ring region (51) which is integrally formed with the first rigid, internally toothed gear (31), an outer ring (52), several first rolling objects (53), several second rolling objects (54) and several third rolling objects (55), wherein the first, second and third rolling objects (53, 54, 55) are inserted in a rolling state between the inner ring region (51) and the outer ring (52); the inner ring region (51) has a first inner ring running surface (56) which is formed between the first end face (44) and the internally toothed gear (31), a second inner ring running surface (57) which is formed on the second end face (45) of the internally toothed gear (31), and a third inner ring running surface (58) which is formed on the circular outer circumferential surface (46) of the internally toothed gear (31);the outer ring (52) has a first outer ring running surface (59) opposite the first inner ring running surface (56), a second outer ring running surface (60) opposite the second inner ring running surface (57), and a third outer ring running surface (61) opposite the third inner ring running surface (58); the first rolling objects (53) for an axial thrust bearing are inserted between the first inner ring running surface (56) and the first outer ring running surface (59); the second rolling objects (54) for an axial thrust bearing are inserted between the second inner ring running surface (57) and the second outer ring running surface (60); and the third rolling objects (55) for a radial bearing are inserted between the third inner ring running surface (58) and the third outer ring running surface (61);the outer ring (52) has a first end plate (62) with an end face on which the first outer ring running surface (59) is formed, a second end plate (63) with an end face on which the second outer ring running surface (60) is formed, and a cylindrical element (64) arranged between the first end plate (62) and the second end plate (63) and having a circular inner circumferential surface on which the third outer ring running surface (61) is formed; wherein the wave gear (30) additionally comprises: a first retaining element (66) for an axial thrust bearing in which the first rolling objects (53) are held in a rolling state between the first inner ring running surface (56) and the first outer ring running surface (59); a second retaining element (67) for an axial thrust bearing in which the second rolling objects (54) are held in a rolling state between the second inner ring running surface (57) and the second outer ring running surface (60);and a pair of third retaining areas (66b, 67b) for a radial bearing, extending from the ends of the first retaining element (66) and the second retaining element (67) into a region between the third inner ring running surface (58) and the third outer ring running surface (61), wherein the third rolling objects (55) are held in a rollable state between the third inner ring running surface (58) and the third outer ring running surface (61); wherein cylindrical rollers are used as the first, second and third rolling objects (53, 54, 55); and wherein the wave gear (30) further comprises: a second rigid, internally toothed gear (32) arranged between the first rigid, internally toothed gear (31) and the second end plate (63) of the outer ring (52);wherein the flexible, externally toothed gear (33) has a cylindrical shape and a cylindrical area that is flexible in a radial direction, the cylindrical area having external teeth (34) formed along a circular outer circumferential surface (46) of the cylindrical area and being arranged coaxially within the first rigid internally toothed gear (31) and the second rigid internally toothed gear (32); the flexible, externally toothed gear (33) has fewer teeth than the first rigid internally toothed gear (31) and the same number of teeth as the second rigid internally toothed gear (32); and the flexible, externally toothed gear (33) is bent non-circularly by the shaft generator (37) and partially engaged with the first rigid internally toothed gear (31) and the second rigid internally toothed gear (32);and wherein the second end plate (63) has an uneven area (63c) with an outward level difference, arranged radially within an outer circumferential surface of the second end plate (63) where the second outer ring running surface (60) is formed; the second rigid, internally toothed gear (32) is arranged radially within the second outer ring running surface (60) and the second retaining element (67) and is located between the first rigid, internally toothed gear (31) and an inner end surface region of the uneven area (63c); and the second rigid, internally toothed gear (32) is attached in a fastening manner to the inner end surface region of the uneven area (63c) or is formed integrally with the region of the second end plate (63) that faces the inner circumferential edge region.

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