20 July 2008
Land Rover

Land Rover

Land Rover develops diesel ERAD Hybrid

20 July 2008 | Land Rover's engineers are now conducting real-world tests with some Diesel ERAD Hybrid vehicles, aimed at cutting CO2 and other emissions while still delivering characteristic Land Rover all-terrain performance. These engineering 'mules' are based on Freelander 2 vehicles, but the technology is designed to be scalable and modular, so could be applied across a variety of Land Rover models and powertrains.

This programme is one of a range of sustainability-focused engineering programmes that Land Rover is pursuing, brought together by the company under the collective name e_TERRAIN TECHNOLOGIES.

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In addition to these Diesel ERAD Hybrids, Land Rover is developing a range of other emissions-busting and fuel-saving technologies that will start appearing on its production vehicles from now and over the next decade. These range from a stop-start function – which will be available next year as standard on all manual diesel Freelander 2 models – to other hybrid systems and lightweight vehicle architectures.

Land Rover's Diesel ERAD Hybrid was developed as part of a multi-million-pound project supported by the UK Government's Energy Saving Trust, under the low carbon research and development programme. The objective is to develop a 'parallel' hybrid drive system compatible with all-terrain four-wheel-drive capability. As parallel hybrids, the vehicles can be driven solely by electric power or by the diesel engine, or by a combination of both. The system is designed to reduce CO2 by more than 20 per cent under the NEDC test cycle and to cut it by a substantial 30 per cent in 'real-life' urban conditions where hybrid technologies really come into their own.

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Under many circumstances, today's generation of petrol electric hybrids are little more efficient than the best modern diesel engines without hybrid technology. So Land Rover's ambition is to add the benefits of a full hybrid system to modern, clean and efficient diesel powertrains, giving a win-win situation. To help deliver this, Land Rover has developed its own, unique Electric Rear Axle Drive (ERAD) system, which actually has the potential to enhance the vehicle's all-terrain capability.

Crucially, the ERAD would enable a Land Rover to run on electric power alone, a feature which is especially effective for reducing emissions in urban conditions. Though mounted on the rear axle, the ERAD can deliver power to the front wheels, via the propshaft, enabling it to drive the vehicle in full four-wheel drive.

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The second key technology on the Diesel ERAD Hybrid prototypes is the Crankshaft Integrated Starter Generator (CISG), which works with the four-cylinder turbodiesel engine of the Freelander 2 prototype mules. The CISG is a powerful electric unit mounted within the special dual-clutch transmission fitted to the prototypes. It acts as a supplementary motor for adding torque to the driveline and also for starting the main diesel engine.

The engine, CISG and ERAD work together to deliver the hybrid drive, providing a choice of diesel, electric or combined power, as appropriate to the driving conditions. This is all managed by the Power Inverters. In addition, both the ERAD and the CISG can be used for regenerative braking, recovering kinetic energy to recharge the vehicle's special battery pack. This energy would otherwise be lost – generally dissipated as unwanted heat.

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Located in the boot space – and taking up no more room than a conventional spare wheel and tyre – a Lithium ion battery pack stores both the electrical energy needed to power the CISG for starting and the energy recovered during regenerative braking. Lithium ion (Li ion) batteries are lighter than the nickel metal hydride batteries used in most current production hybrids. Their chemistry also allows them to store more energy and receive a charge more quickly.

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