多缸HCCI汽油机SIAI/AI燃烧模式切换的试验

摘要

HCCI/SI composited combustion model is regarded as a practical operation strategy for gasoline HCCI engines.But different demand of air-fuel ratio and internal EGR rate bring the control difficultly in HCCI/SI mode switch.Switch frequency HCCI engine Combustion mode is high due to the narrow load range,and this reduces the operation stability.Based on multi-cylinder gasoline engine with a two-stage CAM profile,the spark-induced auto-ignition（SIAI）was realized,and SIAI/SI combustion mode switch was studied.Results showed that fuel injection at compression stroke combined with spark-ignition strategy can effectively avoid misfire,improve stability of mode switch.SIAI can extend the load operation range of HCCI combustion,and effectively reduce mode switch frequency.%HCCI/SI复合燃烧模式是HCCI汽油发动机实用化的运行策略.但不同的空燃比和内部EGR率的需求给HCCI/SI模式切换带来了极大控制难度;同时由于HCCI负荷范围窄,使得燃烧模式切换频率过高,降低了发动机运行稳定性.在一台具备错位双凸轮机构的多缸汽油机上实现了火花点火激发混合气自燃着火（SIAI）燃烧方式,扩展了压燃模式下的负荷范围,研究了SIAI/SI燃烧模式的切换.结果表明,采用压缩冲程燃油喷射配合火花点火策略能够有效地避免燃烧模式切换中的失火现象,提高模式切换的稳定性;同时采用SIAI燃烧方式扩展内部EGR条件下的负荷范围,可以有效地减小模式切换频率.