Patent ID: 8137231

Claim:
An automatic transmission for an electric vehicle hub, comprising: an external motor rotor fixedly connected with a motor shaft; a sun gear; at least three first planet gears which are arranged circumferentially around the sun gear; and at least three corresponding second planet gears coaxially fixed with the respective first planet gears; wherein the first and the second planet gears are respectively engaged and transmitted along with first and second internal gears, and the second internal gear has a diameter greater than that of the first internal gear; and wherein a rotating disk is arranged between external circumferential surface of the first internal gear and internal circumferential surface of the second internal gear, and a hub is fixed to exterior of the rotating disk; and the automatic transmission further comprising: a clutch device, making the rotating disk and the external circumferential surface of the first internal gear contact with each other for a transmission of slower rpm, and when the rpm reaches critical, making the rotating disk and the internal circumferential surface of the second internal gear contact with each other at a high-speed rotation.