US Patent 10144406 Power transmission apparatus

A power transmission apparatus that is mountable on a vehicle includes a planetary gear mechanism, a first motor generator, a second motor generator, and a stepped automatic transmission with parallel gears. The first motor generator and an output side shaft of the stepped automatic transmission are configured to be coupled to a power input shaft from an engine provided in the vehicle via the planetary gear mechanism. An input side shaft of the stepped automatic transmission is configured to be coupled to the power input shaft. The second motor generator is coupled to the output side shaft of the stepped automatic transmission.