City lite

A hybrid electric and diesel truck engine designed by Imperial College with the aid of IVECO Ford could reduce vehicle pollution during urban deliveries, university researchers say.

While the amount of freight carried by road vehicles continues to increase, towns and cities are having to enforce regulations such as the European Heavy Duty Vehicle Emissions Directive. Diesel engines, the engine of choice for delivery vehicles, are least inefficient at burning fuel – and are therefore most polluting – when operating at low, town speeds.

To allow vehicles to deliver within urban areas, a method must be found to reduce or eliminate the amount of fumes they produce.

Dr. Michael Lamperth of Imperial’s mechanical engineering department, together with researchers Hamideh Razavi and Peethamparam Anpalahan are developing a mild hybrid powertrain system that will allow the urban operation of a delivery vehicle in the 7.5 to 18 tonne range using an electric drive. The system includes two clutches; one conventional and a second, electromagnetic device.

Partners in the project include Bath University, Intelligent Power, Turbogenset, Spicer Driveshaft and delivery firm TNT. A prototype should be on the road within 18 months.

The team has replaced the alternator and starter motor of an HGV with a motor-generator unit mounted on the output shaft of the engine.

When the vehicle is moving at high speed, as on a motorway, the motor-generator acts as the flywheel but also charges an energy storage battery. The standard clutch is used to change gear.

Once a town is reached, the battery replaces the engine as the power source, driving an electric traction machine located between the main engine and the gearbox. Switchover is currently via a driver-activated switch, though the designers hope this will eventually become automatic.

‘Delivery vehicles contain sophisticated equipment that can pin down their precise location,’ said Lamperth. ‘An intelligent control system could use this data and change between diesel and electric operation automatically.’

To make best use of the stored electricity, the engine is designed to switch off instead of idling.

‘Turning the engine on and off repeatedly during deliveries wears the starter motor. Fleets get through a lot of them,’ said Lamperth. ‘The electromagnetic clutch can be configured to generate a precise amount of torque that allows the diesel engine to crank up and start without a starter motor.’

The electromagnetic clutch is made from a rare earth magnetic coupling surrounding a conventional friction clutch, allowing for frequent, wear-free engine starting without clutch slip.