Improvement of Trade-Off between NOx and Fuel Consumption by a Small Amount of Pilot Injection in Dl Diesel Engine

摘要

For reducing exhaust emissions, the effect of pilot injection with a short pilot-main interval on combustion was investigated in a turbocharged direct injection diesel engine. Three kinds of technique to decrease the amount of pilot injection were examined for suppressing an increase in smoke due to pilot injection; (1) Increase in Dodge plunger seat diameter. (2) Reduction in nozzle-hole diameter. (3) Control of the amount of pilot injection varying the spring chamber pressure. Each technique is compared on the viewpoints of combustion behavior, smoke and the trade-off between fuel consumption and NOx. Smoke decreases as the amount of pilot injection decreases while the tradeoff between fuel consumption and NOx is markedly improved by the small amount of pilot injection as well as by reduction in nozzle-hole diameter.