直喷增压汽油机采用高压缩比技术的研究

Study on High Compression Ratio in Direct Injection Turbocharged Gasoline Engine

通过在1.3L直喷增压汽油机上,采用两种不同的高压缩比进行试验,研究泵气损失变化规律和对热效率的影响。在转速2500rpm-8bar工况下,采用可变气门正时技术调节发动机有效压缩比和膨胀比。结果表明:高的有效压缩比,必须加大节气门开度来减少节流损失,以降低泵气损失;利用高压缩比并采取进气门晚关、排气门晚开的策略的同时,需要兼顾到燃烧稳定性问题:几何压缩比提高以后,发动机不仅热效率得到提升,同时排放物NOx也在降低,但THC排放有所上升。

Based on direct injection 1.3 L turbocharged gasoline engine,this paper studies the change regulation of pumping loss and its influence on thermal efficiency by adopting two different kinds of high compression ratio experiment.Under the condition of the speed of 2500rpm-8bar,the experiment adopts variable valve timing technology to adjust engine effective compression ratio and expansion ratio.The results indicate that it is necessary to increase the throttle opening to reduce the throttling loss with the high efifective compression ratio,for the purpose of reducing pumping losses.Meanwhile,it needs to take the combustion stability into account when taking the late intake valve closing and the exhaust valve late opening strategy by using high compression ratio.After the improvement of the engine compression ratio,not only the the thermal efficiency has been improved,but it also results in the decrease in NOx emission.However,the THC emission increased to some extent.