Power transmission apparatus for a vehicle

A power transmission apparatus for a vehicle having an engine and a motor/generator, the power transmission apparatus comprising:

• a first input shaft selectively connected with the motor/generator;
• a second input shaft formed as a hollow shaft, disposed coaxially with and external to the first input shaft without rotational interference, and selectively connected with the motor/generator;
• a third input shaft formed as a hollow shaft, disposed coaxially with and external to the second input shaft without rotational interference, and selectively connected with the motor/generator;
• a torque mediating shaft formed as a hollow shaft disposed coaxially with and external to the second input shaft without rotational interference;
• an intermediate shaft disposed in parallel with the first input shaft;
• an idle shaft disposed in parallel with the first input shaft, and selectively connected with a transmission housing;
• a first shifting section including a first gear set, a second gear set , a third gear set, and a fourth gear set, which are disposed on the first and second input shafts, the intermediate shaft, and the idle shaft, where the first shifting section is configured to selectively receive a torque through the first and second input shafts and to provide a plurality of intermediate shift-stages shifted from the received torque;
• and
• a second shifting section including a planetary gear set having a sun gear fixedly connected with the torque mediating shaft, forming an output torque by combination of a torque selectively transmitted from the first shifting section and a torque selectively input through the third input shaft, the second shifting section configured to output the output torque to an output shaft through the fifth gear set,
• wherein the output shaft is disposed coaxially with and selectively connected with the intermediate shaft, and configured to output a torque received from the first and second shifting sections.