Abstract
Medium and large-sized diesel engines have two economic advantages : high efficiency and use of cheap fuel, the latter being made possible by the use of heavy fuel. But recently, the quality of heavy fuel is becoming worse and utilization is becoming more difficult. Main problems of such heavy fuel are long ignition delay and long after-burning. It can easily be supposed that the former is depending on the first injected fuel and the latter on the fuel injected last. In this paper a new fuel system called Stratified Fuel Injection System is proposed as shown in Fig. A1. This system makes it possible to inject a small amount of light fuel at the beginning and at the end of injection duration. Heavy fuel is injected in between and sandwiched by the light fuel. A prototype of that injection system is assembled and applied to a high-speed engine. As a result, thanks to only 10% addition of light fuel, the heavy fuel can be burned well just the same as pure light fuel as shown in Fig. A2.
