A nutation reducer, wherein the nutation reducer comprises:
- a case;
- two nutation gear pairs which are disposed in said case, wherein said nutation gear pair is composed of a nutation gear and a non-nutation gear in engagement, and said non-nutation gear is provided in said case in fixed manner or integrally formed with said case, a number of teeth of the nutation gear of said nutation gear pair being one more than that of said non-nutation gear;
- an output shaft of the reducer which is rotationally provided in said case;
- two pre-stretched annular spring films, which are respectively installed, on their respective sides, between the nutation gear and the output shaft of the reducer, to convert nutation movement of the nutation gear into single rotary movement of the output shaft of the reducer;
- wherein the annular spring film is further designed to be able to bear a radial force of the nutation gear, so as to enable the annular spring film to have a function of a joint bearing and have a centering function for the nutation gear;
- each of the annular spring films includes an inner ring, an outer ring, and an annular elastic portion connected to both the inner and outer rings;
- the annular elastic portion is an annular bulge which is convex in one side and concave in the other side;
- reamed holes are respectively distributed circumferentially in both inner and outer rings, and the nutation gear each is connected to the outer ring of said spring film by first hinged bolts which respectively pass through the reamed holes in said outer ring and fits with the reamed holes;
- said output shaft is fixed to the inner ring of said spring film by second hinged bolts, and said second hinged bolts respectively pass through the reamed holds in said inner ring and fit with the reamed holes;
- said inner ring is coaxially provided with said output shaft of the reducer, to which the inner ring is connected, and said outer rings are coaxially provided with said nutation gears, to which the outer ring is connected, each axis of the inner ring intersecting with that of the outer ring;
- and
- a shaft angle between the nutation gear and the non-nutation gear is less than 180°, and the annular elastic portion is capable of compensating a pre-stretched deformation amount of a tensile deformation amount generated during installation of the annular spring film;
- and
- a nutation generating mechanism disposed in said case, wherein the two nutation gear pairs are respectively arranged symmetrically on both sides of said nutation generating mechanism, and said nutation generating mechanism drives said nutation gears to perform the nutation movement, making the teeth of the nutation gear roll on the teeth of the non-nutation gear.