Patent ID: 8905882

Claim:
A power transmission system of a hybrid electric vehicle, comprising: a first shaft receiving a torque of an engine; a second shaft disposed in parallel with the first shaft; a first planetary gear set disposed on the first shaft, and including a first rotation element connected to a first motor/generator, a second rotation element operating as an output element, and a third rotation element directly connected to the first shaft; a second planetary gear set disposed on the second shaft, and including a fourth rotation element selectively connected to the third rotation element through an externally-meshing gear and connected to a second motor/generator, a fifth rotation element connected to the second rotation element through an externally-meshing gear and connected to an output gear, and a sixth rotation element connected to a transmission housing; a direct-coupling device connecting two rotation elements among the fourth, fifth, and sixth rotation elements of the second planetary gear set; transfer gears forming the externally-meshing gears; and friction elements selectively connecting a selected rotation element to a selected transfer gear or selectively connecting a selected rotation element to the transmission housing.