Abstract
Keywords: Direct injection, spray guided combustion system, spark-ignition engines, fuel consumption reduction, stratified operation
The second-generation direct-injection for spark-ignition engines from Mercedes-Benz offers clear improvements in fuel consumption, power and emission levels. Faced with the necessity of further reducing fuel consumption, primarily in spark-ignition engines, the Mercedes-Benz combustion system represents a significant leap forward in technology. It was possible to noticeably expand the mapping range in which stratified operation can be used compared with the first generation. This significant improvement in efficiency results in more useable energy and a substantial reduction in consumption in city traffic, and also on cross-country and highway trips at roughly constant speeds. These benefits make themselves felt not only in the test cycle, but also in the real-world consumption achieved by the customer. Development proceeded from the base aspirated engine on the principle of the modular expansion of technology. Since production development of this combustion system was not possible using the hydraulic and ignition components available on the market, a new outwardopening piezo fuel injector had to be developed for production readiness, along with a 200-bar highpressure fuel system. The injection spray stability and excellent mixture preparation that it achieves produce an optimally combustible mixture at the spark plug. The potential of multiple injection, along with stability in stratified operation, brings further benefits and possibilities for direct injection in fuel consumption and emissions. This combustion system will find a wide spread in Mercedes-Benz passenger cars.