Opposed-piston two-stroke internal combustion engine with spark ignition, direct fuel injection into the cylinder and stratified charge

摘要

Two-stroke engines are simple to construct and have a low weight. However, the charge cycle is difficult to monitor and measures within the engine against the production of pollutants are difficult to implement. The use of the opposed-piston principle with control times which can be changed during operation can vastly reduce the production of pollutants. In such a motor, it is possible to charge the cylinder with three strata (layers). An ignitable mixture with some of the air which has flowed in is formed above one piston by fuel injection, and a regulatable-quantity exhaust-gas residual stratum is located above the second piston. Air which serves to increase the air/fuel ratio lambda during combustion is located between said two layers. The combustion space forming between the two pistons has a geometrically minimised wall surface area for the heat dissipation. A suitable selection of materials reduces the heat dissipation in this high-temperature range still further, with the result that the thermal efficiency increases. The engine is suitable as a replacement for Otto engines, it being superior to the latter in terms of cost-effectiveness and pollutant emission.