Torque overlay device for a hybrid drive system, and a method for operating such a hybrid drive system

A hybrid drive of a vehicle, the hybrid drive comprising:

• an internal combustion engine having a power between 40 and 150 kW,
• an electric motor having a continuous power of between 30 and 60 kW, and a peak power of 2 to 3 times the continuous power, and
• a torque superimposition device comprising:
• a first torque input torque-proof coupled to the electric motor;
• a second torque input torque-proof coupled to the internal combustion engine;
• a torque output coupled to a drive input of the vehicle;
• a first gearing device torque-proof coupled to the first torque input and torque-proof coupled to the torque output, the first gearing device comprising:
• at least two alternatively selectable gear ratio steps, and at least one planetary gear set configured to implement the at least two alternatively selectable gear ratio steps;
• and
• a second gearing device torque-proof coupled to the second torque input and torque-proof coupled to the torque output, the second gearing device comprising:
• at least one alternatively selectable gear ratio step, and at least one spur gear set configured to implement the at least one selectable gear ratio step,
• wherein torque of the electric motor is superimposed on torque of the internal combustion engine via the torque superimposition device.