An Otto-cycle turbocharged PFI engine was selected to upgrade to a dedicated hybrid engine by increasing compression ratio, designing EIVC cam profile and high tumble intake port, and introducing low-pressure EGR. Experimental research was conducted to find the effects of Miller cycle and low-pressure EGR on combustion and economy performance of dedicated hybrid engine. The results show that Miller cycle has a larger ignition advance angle and the increase of ignition advance angle increases first and then decreases with the increase of load under different loads at 3 200 r/min. In addition, combustion duration and exhaust gas temperature increase when CA50 decreases to 8° approximately, and the PMEP reduces and the reduction increases at first and then decreases with the increase of load. With the decrease of PMEP and CA50, the BSFC reduces by 6.8%-11% and the region of high thermal efficiency extends to 60% of the whole working area. The ignition advance angle and combustion duration increase, and CA50 decreases with the increase of low-pressure EGR after introducing low-pressure EGR at high thermal efficiency working points of Miller cycle. The low-pressure EGR can improve combustion obviously and the biggest drops of BSFC are 5.6% and 15.9% at medium and high load respectively.
YANG Ruzhi,MAN Xingjia,YE Nianye,LIANG Yuanfei.
Effects of Miller Cycle and Low-Pressure EGR on Performance of Dedicated Hybrid Engine[J]. Vehicle Engine. 2022, 0(3): 7-14 https://doi.org/10.3969/j.issn.1001-2222.2022.03.002
