Dec 10, 2011

Green Car Congress: HyBoost concept achieving close to Prius-level CO2 emissions; aggressive downsizing with advanced boosting and micro-hybrid system

The HyBoost demonstrator being developed by Ricardo and its partners (earlier post) is achieving comparable performance to the conventional 2.0L version of its vehicle (a 2009 Ford Focus) but with fuel economy and CO2emissions approaching those of a Prius, according to David Boggs, Ricardo Technical Specialist, Engines, in a presentation at the recent 2011 Directions in Engine-Efficiency and Emissions Research Conference (DEER) hosted by the Department of Energy in Detroit.

HyBoost achieves this by combining aggressive 50% downsizing of the engine with an electric supercharger for transient low-speed performance, and a micro-hybrid stop-start and energy recuperation systems, Boggs said.

Downsizing the 2.0-liter base engine to a 1-liter, boosted direct injection (EcoBoost) engine delivers up to a 25% reduction. The stop-start system with 6 kW of regenerative braking capability delivers another 10%. Cooled EGR, revised turbo match and the e-boost at the low end provides another 6% reduction, while the use of taller gears and a gearshift advisor chips in another 7% reduction. The HyBoost demonstrator comes in at around 99 g CO2/km but with further system optimization, Boggs said, they can get it down to around 89—the same rating as the Prius.

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Click to enlarge.
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Ricardo’s gasoline engine roadmap focuses on CO2 reduction through downsizing and the use of synergistic technologies. Click to enlarge.

Engine downsizing is central to Ricardo’s gasoline engine roadmap for future CO2 and fuel economy improvements. Next-generation spray guided direct injection combustion systems support aggressive engine downsizing with robust stratified engine operation having excellent fuel consumption. A highly tolerant combustion system and knock mitigation are necessary to achieve the very high BMEP levels. The HyBoost vehicle demonstrates the potential to achieve CO2 reduction significantly with cost-effective technologies...the application of synergistic technologies enables high levels of engine downsizing and vehicle fuel economy improvement.

—David Boggs