Study On The Driving Characteristics And Emission Characteristics Of Hybrid Electric Car

With the increasing prominent of the vehicle exhaust emission problem and the shortage of oil resources, the increasing serious air pollution, energy-saving and environmental protection have become two main themes of industry development of global automotive. Current hybrid vehicles’ technology become more and more mature, numerous studies have been conducted to investigate the strategy of power drive systems and control, However, little is known until now about the emission characteristics of hybrid electric vehicles. To study the driving characteristics and emission characteristics of BYD/Qin hybrid electric car, road emission test were carried out on the four typical grade road in ShenZhen by Portable Emission Measurement System(PEMS). The main conclusions are as follows:(1) The driving cycle of Shenzhen is composed of 8 micro-trips, the total length of 1273 s, the average speed of 28.63Km/h, the maximum speed of 76.60Km/h, the average acceleration of 0.616m/s2, the average deceleration rate of-0.648m/s2. Compared with the foreign standard conditions and domestic typical urban conditions, The results show that vehicles ran in urban areas at high speed mode,high acceleration and low deceleration, and the ratio of different modes are close. The road conditions are relatively good.(2) When the vehicle speed is less than 20 km/h, the hybrid electric vehicle is at pure electric mode, and the emissions of CO、HC and NOX are 0; after 20km/h, the engine starts to work, the emission factors of CO、HC and NOX increase first and then decrease with the increasing of the velocity and the acceleration; on each grade road,the emission factors of CO、HC and NOX are basically the same with the change of speed;under the combined distribution of V-VSP, the high emission rates of CO、HC and NOX of the hybrid electric car are mainly concentrated in the high speed and high VSP area, but the effect of VSP on each pollutant emissions is greater than the speed.(3) The emission factors of CO、HC and NOX of the hybrid electric car are similar with the increasing of VSP on different grade roads. VSP<0, the emission factors of various pollutants change a little and at a low level; VSP=0, emission factors of each pollutants are the lowest; VSP>0, the emission factors of all pollutants increase with the increasing of VSP.(4) The average emission factors of hybrid electric car’s CO、HC and NOX have obvious advantages compared to conventional gasoline car, HC is the most obvious, only 2.92% of the traditional gasoline vehicles, and CO only 3.70%, due to the role of turbo charging, NO_x is slightly higher, but only 28.01% of the traditional gasoline vehicles. The research results have shown that the hybrid electric car has a good performance of emission reduction.