Search Results

To solve the pollutant emissions from a diesel engine, it seems quite effective to replace a diesel engine with a gasoline engine whose emission is less dirty. For this purpose it is required for a gasoline engine to improve the fuel consumption to the same level of a conventional diesel engine, so that the Miller system was applied to a gasoline engine. The Miller cycle gasoline engine equipped with rotary valves to control induced charge has an ability to vary the effective compression ratio, so that the better fuel economy is obtained due to the effects of both higher expansion ratio and decrease in pumping loss. 2.6 liter Miller cycle gasoline engine has a similar fuel consumption characteristic as the conventional 3.0 liter diesel engine. Although the output performance of the Miller cycle gasoline engine is inferior a little to that of the diesel engine, the emission characteristic of the Miller engine is far superior.

We have introduced a supercharged Miller Cycle gasoline engine into the market in 1993 as an answer to the requirement of reduction in CO2 emission of vehicles. Improvement in the fuel economy of a supercharged Miller Cycle engine is achieved by the reduction of friction loss due to a smaller displacement. The biggest problem of a conventional supercharged engine is knocking. In order to avoid the knocking, lower compression ratio, which accompanies lower expansion ratio, has been adopted by the conventonal engines and achieved insufficient fuel economy improvement. The Miller Cycle obtains superior anti-knocking performance as well as lowering compression ratio, while keeping the high expansion ratio. The decreased friction loss by the smaller displacement has completely lead to the improvement of fuel economy.