Abstract:

The changes of emission characteristics and operation parameters including exhaust temperature， rotational speed， load， coolant temperature and oil temperature of a range?extended hybrid electric vehicle under the charge sustaining mode are tested over the WLTC cycle on a chassis dynamometer. The results show that the warm up and the oil temperature rise of range extender are much faster than those in traditional engine. In the conditions of start and abrupt change in load and speed， the gaseous emissions of range extender increase， and in the first start and the subsequent restarts， the PN emissions of range extender may deteriorate with a trend of its particle size moving from nucleation mode to accumulation mode. During vehicle deceleration by fuel cut?off， the range extender may generate particulates with a concentration of one?order higher of magnitude， and the deterioration of particulate emission in start and deceleration stage is closely related to the oil temperature and thermal state of range extender. Under WLTC cycle， the range extender mostly works on the low speed areas （2 250~2 400 r/min） and a load ranges of 40-60% and 90%-100%. The speed and load of range extender follow a moving trajectory changing with speed range （medium， high and extra?high speed） with certain rule.

Key words: extended?range hybrid electric vehicle, charge sustaining, emissions, operation characteristics