Rotary electric steering engine and harmonic reducer thereof

The utility model relates to a rotary electric steering engine and a harmonic reducer used on the rotary electric steering engine for the first time. The harmonic reducer comprises a cam, a flexible bearing, a flexible gear, a rigid gear and an output shaft, wherein the flexible gear with a hole formed in the middle is sleeved on the output shaft; a circle of occluded teeth are formed on the excircle of the flexible gear; the excircle of the cam is similar to an ellipse and provided with an inner hole for sleeving with a brushless DC motor shaft; the flexible bearing is mounted on the excircle of the cam; the incircle of the rigid gear is provided with a plurality of internal teeth matched with the teeth on the excircle of the flexible gear; and connection components of the flexible gear, the flexible bearing and the cam are all filled in the rigid gear. In the improved harmonic reducer provided by the utility model, the flexible gear is only 9.2mm in length and can be applied to a rotary electric steering en