Ricardo turbocharged spray-guided gasoline direct injection (T-SGDI) combustion system offers a practical route to diesel-like fuel efficiency
Ricardo HyBoost research demonstrates how barriers to engine downsizing can be broken through low cost intelligent electrification of the powertrain architecture
These promising new technologies took the awards for most ‘outstanding paper’ at the FISITA 2012 World Automotive Congress, respectively in the ‘future internal combustion engines’ and ‘future powertrain’ categories
Ricardo’s T-SGDI research programme, the presentation of which was recognized in the future internal combustion engines category, has been carried out over the past four years in collaboration with the engines business of Malaysian technology and energy company PETRONAS Research Sdn Bhd. The research team has been working to optimize the fundamentals of gasoline combustion using advanced analysis methods and laser diagnostic tools. Several single cylinder research engines have been used in this project, based at the Sir Harry Ricardo Laboratories of the University of Brighton. These included an optically accessed engine allowing unprecedented views into the cylinder throughout the processes of induction, fuel injection and combustion. The initial part of the programme enabled the successful development of a next-generation stratified charge combustion system based on spray-guided fuel injection with up to five injections per cycle.
Subsequent research work on the multi-cylinder T-SGDI research engine has demonstrated that fuel consumption benefits were significantly enhanced through boosting, with a best BSFC of 203 g/kWh being achieved at 2250 rev/min and 13 bar BMEP. The higher mass flow during part load resulting from unthrottled operation also improves turbocharger response. In addition, the best BSFC engine map areas are much closer to real-world requirements than is the case with previous stratified charge solutions. Unlike a diesel engine, there is no practical smoke-limited AFR, so lambda can be instantaneously switched from lean to λ1 or richer to maximize the air utilization for maximum torque and increased enthalpy release to the turbine for enhanced run-up.
The HyBoost concept was demonstrated by Ricardo and its research partners Controlled Power Technologies, the European Advanced Lead Acid Battery Consortium, Ford, Imperial College London, and Valeo. HyBoost is based on a 2009 Ford Focus in which a 2.0L naturally aspirated four-cylinder gasoline engine is replaced with a 1.0L three-cylinder EcoBoost engine. In implementing this 50 percent downsizing by swept volume, the research team had the objective of delivering zero degradation in driveability, performance or acceleration. This was achieved through the use of a combination of technologies including a belt starter-generator to provide regenerative braking and stop/start, exhaust energy recapture through electric turbo-compounding, advanced lead-acid batteries and super-capacitors to provide energy storage, and electric supercharging to provide improved transient response and avoid the pitfalls of turbo-lag that otherwise place a practical limit on the potential for downsizing. The resulting architecture provides a highly cost-effective, low-voltage, mild hybrid gasoline powertrain delivering similar CO2 performance to a more expensive full-hybrid, but at a cost premium of less than a diesel.
“We believe that the Ricardo T-SGDI combustion technology and HyBoost intelligent electrification offer highly promising solutions for current and future powertrain applications,” said Ricardo chief technology and innovation officer Neville Jackson. “Whether in conventional powertrains or hybrid or range extender applications, the trend for gasoline engines to 2025 and beyond is heading in the direction of aggressive downsizing, an approach that can be effectively facilitated by the advanced combustion and intelligent electrification technologies developed and demonstrated in these projects. Through this research we have shown respectively that it is possible to deliver a step-change in gasoline engine efficiency, exceeding the levels of the latest automotive diesels over a very large area of the engine operating range, and we have broken the boundaries of downsizing without compromising performance. We are pleased that this work has been recognized by FISITA with two outstanding paper awards against strong competition at its 2012 World Congress and would like to thank the organizers of the event for this acknowledgement.”
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