The base function of the new Citaro hybrid is very simple: the disc-shaped and very robustly constructed electric motor is integrated between the combustion engine and automatic transmission. Amongst other things, it works as an alternator during the deceleration of the bus and converts coasting energy into electricity – when braking and when not accelerating. The generated power is stored as electrical energy. Without hybrid technology this energy gained in the recuperation phase would be lost – the new Citaro hybrid uses it and therefore saves: as soon as the bus pulls off, the electric motor supports the diesel or gas engine with additional torque – the so-called boost phase. In this way the combustion engine momentarily has to provide less output when pulling away and therefore saves fuel. In addition, the electric motor supports idling. This improves the efficiency of the combustion engine and contributes towards a significantly reduced fuel consumption and therefore reduced emissions.
The electric motor does not serve to increase the maximum power. That's why the output and torque of the new Citaro hybrid remain unchanged compared to a pure combustion drive of the same type and rating. The engine speed of the combustion engine is not reduced in the boost phase. Only the peak performance is imperceptibly reduced and enhanced by the electric motor.