Calling it a “Citaro capital,” Mercedes‑Benz said will deliver a total of 130 Citaro hybrid low-floor city buses to the Romanian capital of Bucharest beginning in 2020. The Citaro hybrid will be delivered to Bucharest in the company’s solo model version.
Depending on the operation, Mercedes‑Benz said the hybrid module can reduce fuel consumption by up to 8.5 percent.
In the last decade, Bucharest has ordered 1000 Citaro buses. “Bucharest is a capital of the Citaro. So we are delighted to continue working together,” says Ulrich Bastert, head of marketing, sales and customer services for Daimler Buses.
The basic way in which the Citaro hybrid works is when the bus is decelerating, the electric motor acts as a generator and transforms braking energy into electric power. This power is stored so that it can be used by the electric motor to assist the combustion engine.
One of the hybrid drive’s core components is the electric motor. The disc-shaped unit with integral power electronics is a permanently excited synchronous motor. The electric motor is fitted between the combustion engine and the automatic transmission.
The electric motor on the Citaro hybrid assists the combustion engine first and foremost when high levels of power are required, particularly when moving off. It does not serve to boost maximum power, however, which is why the output and torque figures for the bus remain unchanged. Instead, the electric motor reduces the burden on the engine while also improving the vehicle’s start-off characteristics. This does not involve lowering the engine’s speed – the peak output is simply throttled imperceptibly, Daimler said, with the electric motor making up the difference.
The power for driving the electric motor is produced via recuperation, with the electric motor acting as a generator during braking and overrun phases. The electric power generated in this way is stored in double-layer capacitors, also known as supercaps.