火花辅助对多缸汽油机HCCI燃烧及排放的影响

Effects of Spark Assisted HCCI on Combustion and Emissions in Multi-cylinder Gasoline Engine

采用优化动力技术手段,利用发动机冷却水和排气余热加热进气,在多缸汽油机上实现了均质混合气压缩(HCCI)燃烧,研究了火花辅助点火对HCCI燃烧及其排放特性的影响.结果表明:当进气温度未达到HCCI稳定燃烧条件时,火花辅助有助于HCCI燃烧,并可增大平均指示压力、最大气缸爆发压力以及最大压力升高率,降低循环波动率,提高燃烧稳定性;火花辅助使得HCCI燃烧出现了2个放热阶段,当点火提前角增加时,主燃烧阶段的放热率峰值增大,燃烧起始点提前;在发动机转速为1200～1600r/min的小负荷范围内,火花辅助可以适当降低NO_x和HC的排放量.

Applying optimized kinetic process technology the waste thermal energy in the coolant and exhaust gases for intake air heating was used to realize HCCI combustion in a multi-cylinder gasoline engine. The effects of spark assisted HCCI on combustion and emissions were investigated. The results show that utilization of spark assisted HCCI is found to increase indicated mean effective pressure （IMEP）, p （dp/dO）max and reduce cycle-by-cycle variation so as to improve the stability of HCCI combustion. Spark assisted HCCI can achieve a two-stage combustion. When increasing the spark advance angle, the heat release rate peak value will increase. The introduction of spark significantly advances the combustion to top dead center （TDC） and lowers the NOx and HC emissions.