Improving the partial-load performance and emission of GDI engine by combining injection strategy and exhaust variable valve timing technology

The combustion and emission characteristics of a gasoline direct injection engine were investigated at different injection strategies combining with the exhaust variable valve timing (EVVT) technology. The results indicated that at 1400 rpm, fuel injection quantity was 11.5 mg/cycle, and the optimiz...

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Bibliographic Details
Published in:Journal of the Brazilian Society of Mechanical Sciences and Engineering 2023-10, Vol.45 (10), Article 549
Main Authors: Wang, Bin, Xie, Fangxi, Duan, Jiaquan, Liu, Yu, Li, Xiaoping, Su, Yan
Format: Article
Language:English
Subjects:
Chemical properties
Dilution
Emission analysis
Energy consumption
Engine valves
Engineering
Exhaust gases
Flame speed
Fuel consumption
Fuel injection
Mechanical Engineering
Optimization
Particulate emissions
Residual gas
Technical Paper
Thermodynamic efficiency
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Summary:The combustion and emission characteristics of a gasoline direct injection engine were investigated at different injection strategies combining with the exhaust variable valve timing (EVVT) technology. The results indicated that at 1400 rpm, fuel injection quantity was 11.5 mg/cycle, and the optimization of fuel injection timing and EVVT opening degree (injection timing = 290 °CA bTDC, EVVT = 40 °CA) can reduce the break specific fuel consumption (BSFC) by up to 6.12% compared to the basic engine (injection timing = 260 °CA bTDC, EVVT = 0 °CA). When the EVVT opening was 30 °CA and the injection timing is 270 °CA bTDC, the engine emissions and performance can obtain a trade-off effect, while the BSFC and the emissions all have a significant decrease. This is because EVVT can significantly increase the residual gas in the cylinder, which changed the thermodynamic and chemical properties of the charge, thereby reducing pumping losses, improving thermal efficiency and emission performances. Advancing the injection timing to 280 °CA bTDC was beneficial to improve engine performance, but it will cause wall-wetting phenomenon to greatly increase particulate emissions. Increasing the EVVT opening degree can effectively offset this problem. The use of split injection was beneficial to increase the flame speed and augment the tolerance of engine to the dilution of residual exhaust gas.
ISSN:1678-5878
1806-3691
DOI:10.1007/s40430-023-04477-3