Patent ID: 7455615

Claim:
A transmission mechanism, comprising: a motor; a first planetary gear set connected to the motor; a second planetary gear set connected to the first planetary gear set; a transmission shaft connected to the second planetary gear set; an intermediate shaft being inserted by the transmission shaft; and an output shaft being able to engage or disengage from the transmission shaft; wherein the second planetary gear set includes a second planet carrier with an internal gear, a plurality of second planet gears pivotally mounted on the second planet carrier, and a clutch connected to the first planetary gear set and having a sun gear meshed with the second planet gears; the transmission shaft has a round shaft formed at one end thereof for passing through a central hole of the sun gear, a polygonal shaft formed at the other end thereof, in which a small gear is provided between the round shaft and the polygonal shaft and is able to engage or disengage from the internal gear of the second planet carrier; the intermediate shaft has an axial polygonal hole, in which the polygonal shaft of the transmission shaft is fitted into the polygonal hole of the intermediate shaft; and the output shaft has a polygonal hole formed at one end corresponding to the polygonal shaft of the transmission shaft.