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 Diesel-powered vehicles combine excellent fuel economy and power, and their popularity is especially high in Europe. In fact, around 40 percent of all new cars sold in the region now have diesel engines. The automotive industry is currently gearing up for strict emission regulations worldwide which will have a large impact on diesel engine technology. The key challenge with diesel engines is how to reduce concentrations of harmful substances in emission, such as nitrogen oxides (NOx) and particulate matter (PM). DENSO has been developing various diesel engine management systems and components to reduce these harmful substances. In late 1995, DENSO launched the world's first innovative common rail system and it continues to develop and improve its state-of-art common rail system. In fact DENSO developed a 1,800-bar common rail system which was introduced in the European market in June 2002. DENSO's common rail system achieved a high injection pressure - 1,800 bar, the highest in the world - and five-time multiple injections at a high accuracy. This system comfortably cleared EURO4 emission regulations without a diesel particulate filter. In Europe, many vehicle models including the MPV and MAZDA6 of Mazda Motor Corporation, Avensis of Toyota Motor Corporation, and Primera, Almera, Tino, and X-Trail of Nissan Motor Co. Ltd. are equipped with this system. In Japan, the land cruiser, Prado, and Hilux Surf of Toyota, and ELF of Isuzu Motors Limited are equipped with the system. Production of the 1,800-bar common rail system began at DENSO Manufacturing Hungary in 2003, and is set to begin in Thailand in 2004. Also, we plan to start supplying our common rail system to Ford in Europe in 2005. Features and Advantages of 1,800-bar Common Rail System DENSO's common rail system can inject fuel at up to 1,800 bar, significantly reducing the concentration of PM in emission. The high fuel injection pressure is generated by the supply pump which is the lightest in the world for common rail systems. DENSO's new injectors can inject fuel at an interval of 0.4 milliseconds with a required small quantity -- only one cubic millimeter per one injection. The injectors allow the system to perform five injections during each combustion stroke. The five times multiple injections, having predetermined fuel quantities, reduce PM and NOx in emission, and achieve quietness equivalent to gasoline-powered engines. Injection quantity deviation requirements from car manufacturers are increasingly severe, and DENSO is striving to improve machining technology with micron-machining techniques to meet these requirements. Further, DENSO developed a software compensation method for the new common rail system, which compensates injection quantity deviations among the injectors. Specifically, by adopting a two-dimensional code, each injector has a code that contains its own deviation. The engine ECU then reads deviations of the injectors during assembly and compensates for them. In addition, to keep the precise injection quantity of each injector, DENSO developed software that allows only one cubic millimeter per one injection while maintaining a variation of 0.5 cubic millimeters or less during its operation. As a result, the system can keep performing injections with required small fuel quantities, at high accuracy during its operation. Thanks to 1,800-bar common rail system, engine torque is increased by 35 percent, engine power is increased by 24 percent and low idle noise is decreased by 6.5 dB with a 2.0-liter diesel engine, as compared with DENSO's conventional model. Outlook of Common Rail System DENSO will continue to develop common rail systems to meet stricter worldwide emission regulations and provide cleaner emissions, quieter and more powerful diesel engines. [Contact]
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