US Patent 7931555 Hybrid drive device

A hybrid drive apparatus includes an engine; an input shaft that is connected to the engine; an output shaft that is connected to wheels; a rotary electric machine; a first planetary gear apparatus; and a second planetary gear apparatus. In an electric torque converter mode, the first planetary gear apparatus reduces an absolute value of a rotational speed of the rotary electric machine and transfers a first resulting rotational speed to the second planetary gear apparatus, and the second planetary gear apparatus combines the first resulting rotational speed and a rotation of the input shaft, reduces an absolute value of a rotational speed of the input shaft, and transmits a second resulting rotational speed to the output shaft.