Return-difference-free single-stage cycloidal cone gear speed reducer

The invention provides a return-difference-free single-stage cycloidal cone gear speed reducer, belonging to the field of precision mechanical transmission. The return-difference-free single-stage cycloidal cone gear speed reducer comprises a shell, an input shaft, an eccentric sleeve, a steel ball set, an end cover, a conical cycloidal wheel, a dowel pin, a cone gear sleeve, a balance weight, a cross disk, a central disk, an output shaft, a pretension nut, a support bearing and a bearing end cover. The speed reducer adopts the K-H-V single-stage few-tooth-difference planetary transmission basic structure; by using the outer cycloidal conical profile on the conical cycloidal wheel as the tooth profile, meshing transmission with the cone gear sleeve is performed; pretension force is applied to eliminate the tooth space, and the tooth-space-free floating-type constant speed unit is arranged; and thus, the speed reducer has the advantages of simple structure, small size, no return difference, high transmission accuracy, low impact and high transmission ratio.