A Study On Match And Optimization Of Vehicle Powertrain Based On The Constraint Of Exhaust Emission

With the rapid development of city construction, the number of motor vehicles has a great increase. It shows that the number of motor vehicles in China increase fifteen percent each year in recent years. This not only makes China become an oil-imported country, but also makes the environment in the city become worse and worse. In some areas, the environment was badly polluted. Nowadays, vehicle fuel consumption and emissions has become a serious society problem. In order to relieve the controversial issue of rapid oil consumption and shorted oil provision, it is necessary to hold the fuel economy and emission properties as an integrated factor to evaluate the automobile performances and do some further research, especially, for the traditional fuel consumption automobile which is a main product in vehicle market. This paper is designed to do some research relate to fuel economy and emission property of CA7200E on the basis of ADVISOR. The paper use ADVISOR to establish mathematical and control models of each part of powertrain. The models use the velocity and toque at wheels as a negative feedback information to vehicle control part, while use the achieved speed and toque of Engine as a positive feedback to the vehicle control part. The vehicle CPU controls the engine to work in a high efficient range through comparing errors between the negative information and the positive information. The models are proved feasible through comparisons to the experimental results. According to the statistics gathered by the FAW Research & Development Center, the paper establishes an appropriate new drive cycle for sedan automobile. It has much more superiority than the GB/T 12545-1990. Not only the average and maximum speed, but also the high gear using ratio are more close to the real world conditions. Meanwhile, the new cycle uses five different gears while in GB/T 12545-1990 cycle only three low gears are used. In order to evaluate three different powertrain matching in CA7220E, the paper simulates the influence of different final drive ratios to the fuel economy and emission property. Results show that fuel consumption per 100 kilometers is increasing with an increasing final drive ratio, the emission of CO is decreasing when the final drive ratio is decreasing while the HC emission is decreasing with the increasing final drive ratio. But emissions of CO and HC have a little change with the final drive ratio. The NOx emission has a complicated varying law with the final drive ratio. First, the NOx emission decreases to a minimum value when the final drive ratio decreases, then it increases with the decreasing final drive ratio. In order to do some deep research on how the drive cycle influences on fuel economy and emission property of automobile, the paper uses different drive cycles to simulate the CA7220E model in ADVISOR. Results show that fuel consumption per 100 kilometers decreases with the increasing average velocity, while HC and NOx emissions vary with the average velocity in a similar sine curve. Furthermore, different gear also has a great influence on fueleconomic and emission property. Simulation results show that harmful emission centralize in low gear areas and it stays at a low and stable level in the high gear areas. On the contrary, fuel consumption rate has a higher degree in the high gear areas. Whether the fuel consumption rate or harmful emissions has peak value during the acceleration courses when the gearbox shift to another gear. Finally, in order to evaluate the automobile dynamical and economical and emission properties of different matching, the paper use the integrated value index put forward in the paper to give a better choice through choosing proper indices. The research in the paper makes sense during the courses of optimization design, it is really a try to find the relationship between influence factors and fuel economy and emission properties. This will spur the designers to consider dynamical and economic and emission properties in the design stage which can shorten the design cycle. Besides, the research on factors that influence emission can urge the manufacturers to produce more clean fuel consumption automobiles.