23 Jul 08 14:12
Freelander ERAD Hybrid
Land Rover is currently testing diesel-electric hybrids known as ERAD (Electric Rear Axle Drive). These prototypes based on the Freelander use technology as previewed in the LRX concept car, also on show at the British Motor Show this week.
The ERAD system can cut fuel consumption by up to 30% in real-life driving environments, without compromising off-road four-wheel-drive abilities.
It allows for operation in both fully-electric and diesel-powered modes, or a combination of both. The rear-axle drive can also divert electric power to the front wheels via a propshaft; a Haldex unit connects and de-couples the rear axle.
The prototypes also feature a crankshaft-integrated starter-generator (CISG), an electric unit mounted within the dual-clutch transmission. This supplements torque, and aids start-up of the diesel engine. It collects energy otherwise lost under braking, storing it in the boot-mounted lithium-ion battery pack, and also controls a stop-start system to automatically cut the engine when idling.
The 288-volt electric motor can give up to 35kW and 25kW of continuous power, and 148lb-ft of torque.
The whole powertrain system works with Land Rover's multi-mode Terrain Response system, with Eco, Dynamic, Grass/Gravel/Snow, Mund/Ruts and Sand programmes.
In Eco programme, the rear axle only is electrically driven, with the diesel engine deactivated in stop-start traffic.
In Dynamic mode, the diesel engine drives the front wheels, with drive to the rear wheels available when necessary.
For grass, gravel or snow, electric power drives all four wheels for start-up, and for mud and ruts, this can be supplemented by power from the diesel engine, and on sand, the diesel engine is supplemented by the electric drive for high power to both axles.
The diesel ERAD Hybrid is just one of Land Rover's upcoming fuel-saving measures, part of its e-Terrain Technologies programme which also includes the development of more lightweight body structures, plug-in hybrids, 'mild' flywheel hybrids and reduction of power drawn by electrical systems.
The ERAD system could be applied to a variety of different Land Rover and Range Rover models, as well as used with a variety of different engines.
First, however, some of its elements will be fitted in existing production vehicles: diesel Freelanders will be fitted with the stop-start system from next year, and this will be added to other model-ranges shortly after.
