Research On Direct Start & Stop System Based On Gasoline Direct Injection (GDI) Engine

In recent years, with the vigorous development of China's automobile industry, motor vehicle population keeps growing continuously. While the automotive industry makes contribution towards the growth of the economy and brings convenience to people's lives, it makes the energy and environment problems be increasingly outstanding. From the beginning of 21st century, global petroleum resources seem more precious, and the price of auto fuel is rising. Gas stations in the large and medium-sized cities often appear the phenomenon of lack of fuel. It shows that various vehicle demand more and more fuel. City is the largest concentration of motor vehicles. Therefore, their pollutants have a great influence on urban environment.Vehicle often come into idling in the cities as a result of red light or traffic jams. Maybe they keep idling for a long time. This situation doesn't only waste fuel, but also the emissions make the environment be much worse. More and more people realize the importance of concept of environmental protection. The concept——"Idle is a kind of waste"has rooted in the hearts of the people. The United Kingdom, Germany, Switzerland and the Netherlands and other European countries have legislated that drivers must turn off the engine when they meet red light or some special signs. Japan advocate the idle stop technology, and more than fifty local Governments legislate that vehicle should stop idling.Direct Start & Stop technology generate in this context, in order to reduce the idling fuel consumption and emissions, the technology can automatically turn off the engine and restart engine in time. At present, many foreign companies develop direct Start & Stop technology for the requirements of the law. Some companies have introduced the vehicle with this kind of technology to market, but most of these vehicle use starter motor as starting power. The research on direct Start & Stop system is still in the preliminary stage of investigation, and almost none of company develop direct Start & Stop system. There is no engine that is equipped with direct Start & Stop system in China. In order to succeed in the future international automotive market, the development of direct Start & Stop system is extraordinary important.Gasoline direct injection (GDI) engines have become the development direction and goal of engine technology. The engine with gasoline direct injection technology has become the major carmakers preferred power set, and gasoline direct injection technology was applied to many cars a few years ago. In order to adapt to the development of new dynamic platform needs, in this thesis, based on gasoline direct injection engine, the exploratory research on the Instantaneous Reverse Direct Start & Stop System is made. In this thesis, the design of the automatic stop system which control piston stop position have some innovation opinion. This system does not need to add other institutions and only use the existing components of engine. This system can control piston stop position by controlling the consumption of the remaining kinetic energy.The main study tasks in this thesis are as follows:1. Analyzed and work out the optimized plan for gasoline direct injection engine, which is the Instantaneous Reverse Direct Start & Stop System (IRD3S) by the analysis of the domestic and foreign material. The overall design of the Instantaneous Reverse Direct Start & Stop System is preceded. The detailed control process of "Start" and "Stop" two parts are worked out. In addition, the soft environment of direct start & stop system was presented for the first time. The direct start & stop system can automatically operate according to the driving conditions.2. The Generator breaking crank plan of the stop part of direct start & stop system is verified by Matlab/Simulink system. Electromagnetic torque Simulink model is established by Matlab software. The feasibility which is excitation current can adjust electromagnetic torque by the analysis of model simulation results.3. Design electronic control system using PIC18F458 singlechip microcomputer which is produced by Microchip Company and L298 Chip which is produced by ST. Company. The electronic control system can control piston stop and the remaining kinetic energy by controlling the electromagnetic torque of generator and the position of electronic throttle.4. Programmed control software for the generator excitation current control module and automatic stop system throttle control module with the idea of modular design. Cycle variables and the actual throttle position are calibrated.5. Design electromagnetic torque generator experiment bench and test the influence of the throttle position on piston stop-position by The EA888 1.8 L engine as a platform. First of all, through the generator bench experiment, the influence of generator's excitation current on electromagnetic torque and the MAP of current were generated under three different rotate speeds. Secondly, Get and analyze the experimental result which is the influence of throttle position on piston stop-position when the engine shutdown under different throttle positions.The main innovation points in this paper are as follows:1. Control piston stop-position using lost work of engine itself Through the control of electronic throttle's position to adjust the work of pressing air and the control of excitation current to adjust the lost work of driving accessories, the piston stop-position can be controlled. The advantage of the automatic stop system: just use of existing components and don't need to add other components, engine piston can be contoled in the position in target range.2. The establishment of Simulink model of synchronous generator for testing power systemThe feasibility of generator breaking crank plan of the stop part of direct start & stop system is verified by Matlab/Simulink system. The simulation experiments prove that the use of the generator's electromagnetic torque in the piston stop-position system is feasible.