Patent ID: 8287412

Claim:
A hybrid power train of a vehicle including an engine, a first motor generator, and a second motor generator, the hybrid power train comprising: a first planetary gear set which includes a first rotary component, a second rotary component, and a third rotary component; a second planetary gear set which is operatively linked with the first planetary gear set and includes a first rotary component, a second rotary component, and a third rotary component; wherein: the first rotary components of the first and second planetary gear sets are variably connected with each other and the third rotary components thereof are fixedly connected with each other, the first, second, and third rotary components of the first planetary gear set are respectively connected to the second motor generator, the engine, and the first motor generator, the second and third rotary components of the second planetary gear set are variably connected with each other and respectively connected to an output shaft and the first motor generator, and the first rotary component of first planetary gear set is connected to a first brake, wherein a first clutch that is variably connected with the second and third rotary components of the second planetary gear set is disposed to change rotational restriction between the second and third rotary components of the second planetary gear set, and a second clutch that is variably connected with the first rotary component of the first planetary gear set and the first rotary component of the second planetary gear set is disposed to change rotational restriction between the first rotary components, and the first brake, the first clutch, and the second clutch are configured such that disengagement of the first clutch together with engagement of the second clutch and the first brake provides an underdrive stepped gear mode, and disengagement of the second clutch together with engagement of the first clutch and the first brake provides an overdrive stepped gear mode.