US Patent 7276007 Hybrid drive unit

A hybrid drive unit includes a three-element planetary gear coupled to two motors, and a reduction planetary gear which is drivingly connected to the three-element planetary gear and switches modes by controlling a clutch and a brake. A three-element direct drive mode is able to be achieved by providing another clutch which couples together any two elements of the reduction planetary gear, and locking up the reduction planetary gear. As a result, motor output is reduced compared with a four-element direct drive mode of related art during high-speed running, and energy recovery efficiency during regeneration can also be improved.