To utilize ethanol fuel in spark ignition engines more efficiently and flexibly, a new ethanol/gasoline dual-direct injection concept in gasoline engine is proposed. Therefore, based on the dual-fuel dual-direct injection system, the effects of different injection timings and two injector positions on the characteristics of combustion were studied comprehensively, and the effects of different octane numbers and temperature stratifications on knock and combustion were explored. The results show that as for Position A (ethanol injecting toward spark plug), with the delay of injection timing, knock tendency and its intensity increase initially and then decrease due to the comprehensive effect of ethanol evaporation and fuel stratification; on the contrary, for Position B (ethanol injecting toward end-gas region), retarding the injection timing of ethanol can effectively reduce the knock propensity. As for the engine performance, a dual-direct injection performs best, especially the retarded injection timing of ethanol for Position A. It can be found that with the delay of the fuel injection timing, the torque first increases and then decreases. The brake-specific fuel consumption decreases initially and then increases at maximum brake torque spark timing.

中文翻译：

---

喷射正时对双燃料双喷发动机爆震和燃烧特性的影响

为了更高效、更灵活地在火花点火发动机中利用乙醇燃料，提出了一种新的汽油发动机乙醇/汽油双直喷概念。因此，基于双燃料双直喷系统，综合研究了不同喷射正时和两种喷油器位置对燃烧特性的影响，探索了不同辛烷值和温度分层对爆震和燃烧的影响。结果表明，对于位置A（乙醇向火花塞喷射），由于乙醇蒸发和燃料分层的综合影响，随着喷射时间的延迟，爆震倾向及其强度先增大后减小；相反，对于位置 B（向尾气区域注入乙醇），延迟乙醇的喷射时间可以有效降低爆震倾向。发动机性能方面，双缸直喷的表现最好，尤其是A位置的乙醇延迟喷射正时。可以发现，随着喷油正时的延迟，扭矩先增大后减小。特定于制动器的油耗最初降低，然后在最大制动扭矩点火正时增加。