Abstract:

An experimental study is conducted on a Changan 1.5TGDI dedicated hybrid engine， mainly to investigate the effect of fuel injection strategy on the performance under different coolant temperatures.The results show that under 1 000 r/min working condition， multi-injections can achieve lower fuel consumption and PN emissions than single injection， at the low coolant temperature of 30 ℃， with the advantageous area extending below 0.5 MPa BMEP. As the water temperature increases to be above 50 ℃， its fuel consumption benefit can be seen mainly at medium to high load conditions， with BMEP above 0.7 MPa， while the soot emissions become worse gradually. At 2 000 and 3 000 r/min，multiple injection shows a lower fuel consumption only under medium to high load conditions， and this advantage will be further reduced as the temperature and speed increase， in addition， the soot emission of single injection is equivalent to or better than that of multi-injections under low to medium load， but shows a significant deterioration as speed and load increase. Therefore， at the low water temperature of 30 ℃ ， for 2 000 and 3 000 r/min， multi-injections can be used at the loads greater than 0.8 and 1.0 MPa BMEP respectively. As the temperature increases to be above 50 ℃， it can be used at the loads greater than 1.0 and 1.3 MPa BMEP.

Key words: dedicated hybrid engine, fuel injection strategy, coolant temperature, fuel consumption, soot emissions