Saietta Group plc, specialists in high-tech advanced e-mobility propulsion, is intensifying an important overhaul operation to transform existing high polluting diesel-engine-powered buses and coaches into clean, sustainable, and zero-emission vehicles. Through its RetroMotion division, the company is working to offer fleet operators an economical and effective solution to ‘electrify’ existing buses and coaches.
A real-world zero-emissions driving range of up to 350kms is possible with the all-electric retrofit powertrain, depending on individual specification, application, and vehicle size.
“Saietta Group prides itself on being at the vanguard of e-mobility propulsion with the aim of democratizing clean sustainable transportation around the globe and within every sector, from two-wheel scooters to compact passenger cars and right through to bus, coach and heavy goods vehicles,” said Wicher Kist, CEO of Saietta.
“But we also understand that such important yet dramatic change — effectively replacing outdated internal combustion engines (ICEs) with new battery electric powertrains — can’t be successfully achieved overnight. That’s why we are stepping up the efforts of our RetroMotion engineering division. We want to give coach and bus operators an opportunity to transform their aging and polluting fleet into a green mobility service that’s modern and clean. Fleet operators don’t have to make sudden and huge outlays on all-new electric vehicles. These important investments can be done incrementally thanks to the possibility of upgrading and extending the lifespan of existing buses and coaches, in the process also meeting upcoming tough legislation,” said Kist.
Delivery of the company’s first-gen e-axles to customers commenced in 2009. Since then, RetroMotion has developed a high-tech second-generation e-axle and e-powertrain solution. In real-world bus applications running in European cities, the electrification tech package — both gen-one and gen-two developments — has proved impressive reliability and durability attributes, having accumulated in total 3.2 million kilometres on-road usage so far.
Engineering in action
The powertrain conversion replaces the aging diesel ICE and all its associated components, including the gearbox, with an advanced e-propulsion system. This means that state-of-the-art, in-wheel electric motor technology is applied to the rear wheels of the coach or bus. Unlike other systems available on the market, this solution is a true in-wheel arrangement and not so-called near-wheel.
A twin-tire solution with front mounted rims is used as part of the re-design to ensure the in-wheel motors fit seamlessly to the existing application. Critical systems such as the high-power inverter and motor components like the stator and rotor with permanent magnets are also installed as part of the transformation.
The electric motors and e-platform, branded TheWheel and TheMotion 2.0, have been designed in-house to be a class leading solution. Peak torque of up to 20,000Nm is possible with a 94% real-world efficiency level being realized from battery to wheel.
The elimination of a gearbox that was once mated to the diesel ICE means that in the new all-electric powertrain setup, no energy is consumed by having to go through the gears or using a differential, further boosting real-world efficiency.
The Lithium-iron Phosphate battery pack is available in a range of power outputs to suit differing requirements, varying from 181kWh to 422kWh. The transformation from an aging diesel-powered coach or bus to a modern all-electric mobility vehicle also sees the integration of Saietta’s vehicle energy manager and body control module systems, its high-voltage power distribution unit, a battery management system and battery thermal management system, high-voltage inverters, and auxiliaries such as air compressors and the power steering system that has been upgraded to be electrically operated. The team also installs a charging communication ECU, a charging system, and CCS charging socket.
With the electric motors being an in-wheel setup, and the battery pack having been designed to meet optimum dimensions, the all-electric powertrain is compact and benefits from an small operating footprint size and weight in comparison to the diesel ICE and its associated subsystems, meaning that both passenger and luggage capacity are minimally affected by the switchover. A new, visually engaging operator display unit has also been, providing the driver with clear and coherent data relating to the drivetrain, including real-time battery status.
Filed Under: Green engineering