US Patent 7611432 Hybrid powertrain

A powertrain is provided, comprising: an internal combustion engine and an electro-mechanical transmission. The internal combustion engine has two torque output nodes operatively connected to two torque input nodes of the electro-mechanical transmission. The transmission comprises first and second electrical machines operatively connected to first and second planetary gear sets that are selectively operative to transmit torque to an output shaft. The two torque output nodes of the engine comprise an engine block comprising a cylinder with a pair of opposed pistons inserted therein, and each piston operatively connected to one of a first and a second crankshaft. The first and second crankshafts are operatively connected.