Abstract
Keywords:
test methods, HEV, emission, heavy-duty vehicle
Abstract
More and more hybrid electric vehicles (HEVs) are coming into commercial use, which will lead to energy saving and cleaner air. But how to evaluate the emission performance of HEVs is strongly requested by the motor vehicle registration department and the users as well as the makers. When we carry out the tests of the exhaust pollutant of conventional heavy-duty motor vehicles, we only do the test on engine assembly, for instance, with 13-mode or 9-mode. But the emission characteristics of a HEV is connected with the harmonization between power train and complete vehicle in which exists a complex running combination. Therefore, we could not get the overall test results of a HEV only by testing the engine. The best way to conduct an emission test for a HEV is to utilize a large-scale chassis dynamometer with exhaust pollutant analyzer; however, such chassis dynamometer is rarely available even all over the world. Experts of many countries in this field are studying the new test methods for replacing chassis dynamometer test. Based on this, we propose some substitution solutions. According to the test facilities available at hand, we put forward three kinds of solutions. The first is Simple Sampling with some instruments newly developed in Japan and USA, or a CVS system for light-duty vehicles; the second is Map Mapping, in which the engine is tested independently under the same work condition and with the same output characteristics as running in hybrid mode. The last one is based on the emission test reports of some HEVs. This article will concentrate on the principles, detailed procedure of those three solutions and analyzing their advantages or disadvantages.