Thickness-variable transmission structure for robot joint

A robot joint transmission structure, comprising a first stage transmission chain, a planetary carrier, a planetary pin, a planetary gear set that has two gears, a first gear ring, a second gear ring, a shell assembly and an output shaft, wherein the transmission structure is a sun-gear-free transmission structure;

• the first stage transmission chain serves as an input end;
• the first gear ring is connected to the output shaft and serves as an output end;
• a gear in the first stage transmission chain is meshed with the planetary carrier;
• the planetary pin is arranged on the planetary carrier;
• the planetary carrier and the planetary pin are connected with the planetary gear set;
• the planetary carrier drives the planetary pin to rotate around an axis, and simultaneously drives the planetary gear set to rotate and revolve;
• the two gears of planetary gear set are meshed with the first gear ring and the second gear ring respectively;
• the second gear ring is fixed on the shell assembly;
• the first gear ring is connected to the output shaft in an interference manner or through a fixing pin or a bolt;
• wherein the gear ratio of the first stage transmission chain is i1;
• the numbers of teeth of the first gear ring and the second gear ring are z2 and z4 respectively;
• the numbers of teeth of the two gears of the planetary gear set are z1 and z3, respectively, and then the total gear ratio is i1*z1*z4/(z1*z4−z2*z3).