Search Results

With the intention of improving engine performance and emissions, the authors examined the influence of the method of initial fuel injection quantity reduction and of the injector configuration of a common rail fuel injection system on engine performance and exhaust emissions. Results showed that decreasing the nozzle hole diameter was an effective way to reduce the initial injection quantity without increasing black smoke. Compared to a three-way type injector, it was found that a two-way type injector can greatly reduce the amount of fuel leakage from the electromagnetic injector control valve and fuel consumption could be further improved by reduction of the driving loss. Furthermore, the increase of driving losses with higher injection pressure was small, and as a result, higher pressure injection was possible.

In order to reduce exhaust emission and combustion noise and to improve fuel consumption, the effects of the combustion system parameters of a diesel engine, such as injection pressure, injection nozzle hole diameter, swirl ratio, and EGR rate on exhaust emissions, combustion noise and fuel consumption are investigated and described in detail by analyzing rate of heat release, needle valve lift and injection pressure. Based on these results, reduction of exhaust emission and combustion noise and improvement of fuel consumption are described in the latter part of this paper. These results are shown as follows. The smaller nozzle hole diameter is effective for reducing smoke and PM, and by optimizing the injection timing and swirl ratio, NOx can also be reduced. In addition to the above, by applying EGR and higher injection pressure it is possible to improve the fuel consumption with the remaining low NOx and PM.

In the diesel engine industry, the growing trends are toward wider use of electronically controlled high pressure fuel injection equipment to provide better engine performance, while conforming to the stringent exhaust emission standards. Although there have been some recent announcements of a diesel engine that applies an electronically controlled common rail type fuel injection system, there is little literature published about any attempt to reduce both exhaust emissions and noise and to improve engine performance by varying injection pressure and injection timing independently and introducing pilot injection in combination. This paper describes the details of a study made on the parameters associated with injection timing, injection pressure and pilot injection and the procedures for their optimization, with an electronically controlled common rail type fuel injection system installed in an in-line 6-cylinder 6.9 liter turbocharged and intercooled DI diesel engine.