The Lotus Range Extender is an extremely compact, lightweight, low-cost engine and generator, designed specifically for hybrid electric vehicles.
The initial concept engine was fitted to the Jaguar Limo Green research vehicle and this new version has been redesigned by Lotus Engineering and Fagor Ederlan to optimise performance and develop the engine for series production.
The Lotus Range Extender is on show in the cutaway hybrid Evora 414Evolution exhibit. The 1.3 litre, three cylinder Lotus Range Extender engine offers high efficiency and low mass, which will enable the downsizing of expensive batteries, whilst maintaining vehicle efficiency and range of hybrid electric vehicles.
Designing the engine specifically for hybrid applications has provided a number of opportunities to significantly reduce the mass of the engine. This mass optimisation has resulted in an engine weight of 58 kg for the supercharged version and 51 kg for the naturally aspirated variant.
The supercharged engine uses a belt driven centrifugal supercharger to produce 50 kW peak electrical power at 3,500 rpm, with the naturally aspirated version producing a maximum 35 kW. The engine is optimised to generate power at engine speeds between 1,500 and 3,500 rpm allowing a lightweight simple 2 valve per cylinder engine architecture and eliminating the need for a complex 4 valve per cylinder design.
The generator supplied by Fagor Automation, is driven directly off the crankshaft to reduce weight, package size and cost. The engine, generator and power electronics are controlled using a Lotus controller to improve communication and efficient running of the systems. The engine architecture and engine management system are designed to offer flex-fuel capability to allow the engine to run on renewable alcohol fuels.