US Patent 9139079 Integrated electro-mechanical powertrain system for hybrid vehicles

A vehicle powertrain system including a differential gear set, a planetary gear set coupled to the differential gear set, an engine coupled to the planetary gear set to transfer power between the engine and the planetary gear set, a first electric machine coupled to the planetary gear set via a first clutch and selectively engagable, via actuation of the first clutch, to transfer power between the first electric machine and the planetary gear set, and a second electric machine coupled to the planetary gear set via a second clutch and selectively engagable, via actuation of the second clutch, to transfer power between the second electric machine and the planetary gear set.