Elementary Study Of Gasoline Engine Start-Stop Technology In Motor Drive Mode

Because of the energy crisis and environmental pollution are becoming more serious, more and more governments are beginning to carry out many more strict emissions regulations, and also to promote the engine R&D of new technologies and applications, in order to mitigate the stress of motor vehicles for energy and the environment. So in the increasingly crowded city traffic environment, more and more cars wait for a long time in the idling mode, and the fuel consumption and emissions in the engine's idling mode are staggering. So we need to abolish the engine idling mode.We know that develop electric vehicles can achieve "zero pollution", but the cost of electric vehicles, the infrastructure support, the technical problems such as batteries, have difficulty in the rapid industrialization of electric vehicles. So develop hybrid vehicles looks more feasible, because it can achieve the engine's start-stop even the low mixed case. The reliability and emissions in the starting condition are also problems we must solve. In this paper, we explore the combustion process in the warming-up high speed starting condition of Jetta gasoline engine under motor mode. In the first place we research the original ECU control strategy at different starting conditions, in order to obtain the preliminary fuel injection, ignition, emissions and other relevant data. The emphases of this research is using motor driver to develop a new gasoline engine warming-up start strategy and make suggestions to reduce or eliminate combustion instability and reduce the emission during warming-up start process by analyzing the factors which affect combustion process during start.The completed works and the conclusions which was elicited by examinations will be introduced as follow:1.For different aims of the examinations, the platform of Jetta gasoline engine ender motor mode was established for the examinations of start. So the research of whole combustion process and combustion state in first cycles of warming-up start was carry out in the platform.2.Base on the hardware designed by author and the own hardware of engine, rely on the start program, examination research and calibrate the engine warming-up start process over again.3.The combustion process and emission from starting to idling of low-speed, warming-up low-speed, cold high-speed and warming-up high-speed have studied on the platform. We know that: warming-up start mode compared to cold start mode, high-speed mode compared to low-speed mode, its various start-up parameters have different ranges of the optimization. One of the early start-up process reduces fuel injection pulse width of about 1/2,the emission of HC reduces about 1/2 and ignition pulse width decreases slightly, these are mainly because of warm machine status, the engine lubrication system in good condition and the mixed compression in high temperature. But it can not reduce fuel consumption further even if the start-up speed goes too high. At the same time the combustion and emissions become more bad due to the decreasing of air inflow.4.For a more precise study of the combustion process of warm-up high speed start, the examination will account various factors include the self starting system parameters and environment parameters and also only one cylinder will work. With the electronic controlled fuel injection system, the analysis was carried out to make clear the infection which the combustion state in the first cycle bring to exhaust emission during start by changing the boundary condition. The choice of boundary condition include the quantity of gasoline fuel oil for first cycle, Ignition time, start-up speed and so on. Base on a series of examinations, there are some conclusions has been made up: improve the quantity of gasoline fuel oil for first cycle can increase the outbreak of the highest cylinder pressure rapidly and improve combustion significantly, however, excessive amount of first fuel injection can not make more impact on the combustion process and emission will deteriorate. Select the appropriate start-up speed can improve the engine starting performance and improve the relative reduction in the first cycle fuel injection quantity, but emissions will become more bad due to the decreasing of air inflow. Spark advance angle should be adjusted, otherwise, it will grow longer ignition delay period, reduce the engine thermal efficiency and power.According to the examination and analysis, we know that the lower amount of fuel injection and the smaller width of the ignition can make the engine under motor mode start smoothly. But the fuel injection quantity, ignition pulse width, ignition time, start-up speed may accelerate, restrict each other. When made a new gasoline engine warming-up start strategy, all the boundary conditions both the parameters and the affection they effect to each other should be considered to optimize the start process remarkably.