Combustion system improvement based on increased compression ratio and reduced number of injector was tested and studied in a China V medium duty 6-cylinder diesel engine. Results show that, combustion chamber with lager compression ratio can increase the burning rate of engine, and promote the improvement of fuel economy, particularly at part load. However, it can increase the NOxemission level and firing peak pressure significantly. Reducing the number of injector can weaken the mixing of diesel fuel and fresh air, and reduce the specific emission level of NOxby 1~3 g/kWh, and affects the fuel economy slightly at major injection timing. The matching between combustion chamber and injector can be further optimized by adjusting the thickness of injector gasket in order to improve the emission performance of the engine. Through combustion system improvement, the fuel consumption can be reduced by 1~2% at medium and low speed, while meeting the requirement of China V emission regulation.%在一台满足国Ⅴ排放法规的6缸中型柴油机上,进行了基于大压缩比和小孔数油嘴配合的燃烧系统改进试验研究.试验结果表明,大压缩比燃烧室可提升柴油机缸内燃烧速率,促进燃油经济性的改善,尤其在部分负荷更为明显,但会显著增加NOx排放和爆压水平;小孔数油嘴可弱化柴油机缸内油气混合,降低NOx比排放1~3 g/kWh,在大喷油正时下经济性影响较小;结合油嘴垫片调节,可进一步优化燃烧室与油嘴配合,改善整机排放性能.通过燃烧系统改进,柴油机在满足国Ⅴ排放法规要求下,万有特性中低速油耗可改进1%~2%.
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