Ricardo and a consortium of automotive partners have completed an advanced prototype research program based on the highly innovative 2/4SIGHT engine concept that boasts up to 27 percent fuel savings. This gasoline engine concept uses novel combustion, boosting, control and valve actuation technologies to enable automatic and seamless switching between two- and four-stroke operation, with the aim of delivering significant performance and fuel economy improvements through aggressive downsizing. The 2/4SIGHT engine concept uses a direct injection gasoline combustion system in which the design of intake and exhaust ports, combined with appropriate changes in boost supply, fuel injection, ignition and valve timing, enable operation both in two-stroke and four-stroke modes. An advanced control system coupled with flexible valve actuation manages driver demands and coordinates operation of the boost system, valves and fuel injection equipment at an individual cylinder level. This enables smooth transitions between two- and four-stroke operation without torque interruption in both transient and constant torque conditions. Prototype engine configuration The air handling system of the 2/4SIGHT concept is based on two-stage boosting and intercooling using a Rotrex supercharger and Honeywell turbocharger. For simplicity in the initial test bed prototype configuration however, boosting is provided by an external compressed air supply. The engine control system of the prototype is a DENSO rapid prototyping system working with DENSO gasoline direct injection and ignition components. The prototype engine was built at the Ricardo Shoreham Technical Centre and installed for testing at the Sir Harry Ricardo Laboratories of the University of Brighton, UK. Development test results Highlights of the development test results include: Significant improvements in fuel economy The baseline vehicle for the study was an 1800 kg passenger car sold in the European market with a 3.5-liter naturally aspirated V6 gasoline engine and 5 speed conventional automatic transmission with torque converter. To verify the validity of the models and input data, the baseline vehicle fuel consumption results were compared with published data, which were reproduced by the model to an acceptable accuracy of 1 percent. The simulation results indicate that vehicle acceleration performance, including launch from rest, can be maintained with a 2.0-liter V6 2/4SIGHT gasoline engine replacing the 3.5-liter baseline powerplant. This would deliver fuel savings of 27 percent over the New European Drive Cycle (NEDC) and would reduce the vehicle CO2 emissions of the baseline from 260 g/km to 190 g/km. Cost-benefit trade-off Having completed development of the prototype 2/4SIGHT engine, the partners are currently negotiating potential sources of funding and support for a vehicle demonstration program. Commenting on the successful completion of the prototype engine development program, Ricardo technology director, Neville Jackson, says: "The completion of the prototype engine development program of the 2/4SIGHT engine and demonstration of its two-/four-stroke switching capability is an important milestone for the project partners. “While significant further research and development challenges remain, not least in the vehicle demonstration of this advanced engine concept, the initial prototype development project has demonstrated the potential of 2/4SIGHT to offer improved gasoline fuel economy and reduced CO2 emissions, while also maintaining or improving vehicle performance. In addition to validating the 2/4SIGHT concept, the research project is also delivering significant benefits in terms of its many constituent technologies which are likely to see application in the more immediate term." For more information, visit www.ricardo.com. |