Graduation Design (Thesis) Opening Report of Huaiyin Institute of Technology Student's Last Name: Major: Liu Yang Student ID: 1 071507216 Research and Design of Ultra-thin Combustion Technology for Automobile Service Engineering (Thesis Title Design Paper) Title: Thesis Reference Tutor: Yan 201kloc-0. Combined with the graduation project (thesis), according to the consulted literature, each person writes a literature review of about 2000 words, describing the source of the project and the research purpose. First, the subject source and research purpose Although it has been many years, oil, as a non-renewable resource, will eventually be exhausted. Therefore, on the one hand, countries around the world are improving the fuel economy of internal combustion engines, on the other hand, they are actively developing alternative fuels for internal combustion engines and electric vehicles. In China, internal combustion engines consume 45% of petroleum resources, 75% of diesel oil and more than 60% of gasoline. At present, it is of great significance to improve fuel economy. In addition, the harmful emissions and noise of the engine also endanger the environment and human health. In order to improve the economy of automobile engines, lean combustion or even ultra-thin combustion has become an important means for various automobile engine manufacturers. On the traditional automobile engine, in order to ensure the stable and reliable operation of the engine, when the gasoline engine works normally, the air-fuel ratio of the mixture used should be adjusted within the range of 12- 18. Ultra-lean combustion is the combustion process of mixed gas with air-fuel ratio greater than 20∶ 1, which can make fuel combustion more complete. Due to the decrease of the maximum temperature after combustion, on the one hand, the heat transfer loss through the cylinder wall is small, on the other hand, the dissociation phenomenon of combustion products is reduced, and the thermal efficiency is also improved. From another point of view, the use of lean mixture is not easy to knock because of the low pressure and temperature in the cylinder. Then the compression ratio can be increased, the expansion ratio and temperature of the mixed gas can be increased, and the waste gas residue in the combustion chamber can be reduced, thus improving the energy utilization efficiency of the fuel. Using lean mixture and corresponding emission control measures, the harmful emissions of gasoline engine such as CO, HC, nitrogen oxides and CO2 will be greatly reduced. During lean combustion, the specific heat of O2 and N2, the main components of combustion chamber, is small, and the polytropic index K is high. Therefore, the engine has high thermal efficiency and good fuel economy. Second, the research of domestic and international topics The research of domestic and international topics The lean combustion of automobile engines includes lean injection system (PFI), direct injection lean combustion system (GDI) and homogeneous mixed compression ignition system (HCCI). 1 lean injection system (PFI) and lean injection system (PFI). The port injection lean-burn system can be divided into two types according to the different flow forms of intake air in the cylinder: 1. 1 swirl stratified lean-burn system. The representative of this lean-burn engine is Toyota's third generation lean-burn system. Honda's VTCE-E and Mazda's lean burn system. Toyota's third-generation lean-burn system and Mazda's lean-burn system are the same as those of Tebier. The starting point is that the vortex control valve (SCV) is used to adjust the intensity of the vortex. When the load is low, the SCV is closed to obtain strong eddy current. At high load, the SCV opens to obtain oblique vortex, which promotes the mixing of fuel and air. 1.2 tumble stratified lean burn system Mitsubishi Motors Corporation of Japan has successfully implemented tumble stratified lean burn (MVV) system in three-valve and four-valve engines by injecting fuel into the intake port. Later, Mitsubishi Corporation developed a tumble stratified lean-burn system suitable for four-valve engines. Two vertical baffles are symmetrically arranged at the intake of a 4-valve gasoline engine, and fuel is injected between the two baffles, so that the mixed gas is distributed in a thin-rich-thin interlayer along the tumble axis in the cylinder, which can give full play to the advantages of the central arrangement of spark plugs. The limitation of PFI engine is that 20% of the nozzles are installed on the back of the intake valve on the cylinder head, 80% on the intake manifold near the cylinder head, and the engine will be at the intake valve when it is started. Due to the difficulty of fuel evaporation when the cold engine starts, the actual fuel supply is much larger than the required air-fuel ratio, which makes the unburned HC emission of the engine increase obviously. Another limitation of PFI engine is that the throttle valve is used to control the load at medium and small loads, and there is throttle loss. GDI engine adopts stratified charging mode at medium and small load, and the engine load is controlled by controlling the amount of oil injected into the cylinder. Without throttle valve, pumping loss and heat loss can be reduced. 2 Direct injection lean burn system (GDI) Direct injection lean burn system (GDI) When the port injection gasoline engine does not use combustion-supporting method to organize lean burn, its air-fuel ratio can hardly exceed 27∶ 1, but the direct injection lean burn system can easily exceed this limit. Compared with in-cylinder injection lean-burn gasoline engine, in-cylinder injection lean-burn gasoline engine has the characteristics of low pumping loss, low heat transfer loss, high charging efficiency, good antiknock performance and fast dynamic response. The early GDI gasoline engine used the same pump-one-tube-one-nozzle fuel supply system as the diesel engine to achieve the purpose of late injection. The fuel was injected into the cylinder in the late compression stroke, and the mixture was stratified by intake swirl or tumble. The working mode of direct injection in the cylinder of gasoline engine has adopted the German Benz300SL model in 1950s, the MAN-FM system in 1960s, the TCCS system of Texaco and the PROCO system of Ford in 1970s. Most of these early technologies are based on two valves per cylinder and bowl-shaped piston combustion chamber, and post-injection is realized by using mechanical pump and injector of diesel engine. These early GDI engines realized no throttle control in most load ranges, and their fuel economy was close to that of indirect injection diesel engines. Its main disadvantage is that due to the mechanical oil supply system, the post-injection time is fixed at full load or even full load, and the combustion smoke limits the air-fuel ratio to 20∶ 1. After 1990s, due to the rapid improvement of engine manufacturing technology, advanced electronic control technology was adopted, which solved many problems in control and emission of early direct injection engines. The development of new technology and electronic control strategy makes many engine manufacturers reconsider the potential advantages of GDI engines. 1996 Mitsubishi Motors Corporation of Japan took the lead in introducing 1.8 L overhead dual camshaft 16 valve 4G93 wall-guided direct injection engine; Toyota has developed a 2GR-FSEV6 engine with GDI and PFI fuel supply systems. In 2004, GM developed a stratified lean-burn direct injection engine with variable valve timing (VVT) technology. Based on GDI V 12 low-pressure homogeneous mixture engine, BMW developed R6 direct injection engine which can realize stratified lean combustion in 2006. At the end of 2000, Volkswagen Germany applied the principle similar to TDI diesel engine to gasoline engine through electronic control system, and developed a wall-guided stratified direct injection (FSI) engine, which was applied to Lupo vehicles. Its 100 km average fuel consumption is only 4.9 L, making it the world's first 5 L gasoline engine car. In 2004, Audi began to sell its 2.0T—FSI stratified direct injection supercharged gasoline engine. 3 Homogeneous mixed compression ignition system (HCCI) Homogeneous mixed compression ignition system (HCCI) HCCI is a new combustion mode developed on the basis of the previous compound gasoline engine, which is simply a compression ignition mode of gasoline engine. This technology was put forward in the early 1990s and began to be tested, but the electronic control technology is not so mature now, so this technology has not been known to the public until now. As early as 1930s, people realized that there was a combustion mode of homogeneous mixture compression and spontaneous combustion in gasoline engines, but it was always regarded as an abnormal combustion phenomenon and was suppressed. The truly conscious application of HCCI combustion in two-stroke engines began with the research of On-ishi and Nouchi in 1979. In recent years, Aoyam and others have studied the control methods of gasoline and alternative fuel HCCI combustion, and Mase and others have studied the control methods of diesel HCCI combustion. These works deepen the understanding of HCCI combustion and provide experience for HCCI combustion control. The technical structure of the engine adopting HCCI technology is more complicated than that of the general engine. When the compression stroke of the gasoline engine comes to an end, gasoline is injected into the cylinder through the direct injection nozzle. The compression ratio of HCCI engine is higher than that of ordinary gasoline engine, and it can use quite dilute mixture. Therefore, the torque can be directly adjusted by adjusting the fuel injection amount according to the modified adjustment method, and the throttle is not needed. HCCI engine has low combustion temperature and low heat transfer to the combustion chamber wall, which can reduce the transfer of radiant heat and greatly reduce the generation of nitrogen oxides. Another feature is that the combustion cycle is very short. Because the combustion process is mainly chemical reaction rather than mixing process, the combustion cycle can be shorter than that of traditional diesel engines. In addition, the octane number of the fuel it uses can vary within a wide range. Gasoline, natural gas, dimethyl ether and other fuels with higher octane number can be used as the main fuel, and a variety of fuels can also be used for mixed combustion. It can also be used as a method to control the combustion starting point and load range in HCCI combustion by adjusting the ratio of high octane fuel to low octane fuel. However, engines equipped with HCCI technology also have this obvious disadvantage. For example, in the control of natural combustion time, HCCI engine spontaneously ignites by cylinder pressure and temperature, and the density of oil-gas mixture, cylinder temperature and pressure need to be accurately detected and controlled, so the ECU management program of the engine should be strengthened accordingly. Because HCCI compression ignition and heat release are carried out at the same time, the cylinder and piston will be subjected to strong pressure in an instant, and knocking may occur. In addition, the low exhaust temperature is also a problem for catalytic converters, because a relatively high temperature is required to start the oxidation/reduction reaction. The research on lean-burn system in China began in the late 1950s and early 1960s. However, due to the backward electronic control technology in China, the system only stays in the theoretical research stage. In the early 1980s, the injection technology of Tianjin University gasoline engine was first applied to carburetor gasoline engine, but the technology only controlled the air-fuel ratio at 18. Because of the high casting precision, this technology is difficult to popularize in China. At present, the imported Volkswagen FSI engine is the only GDI engine mass-produced in China. In-cylinder direct injection technology is a strict test for the quality of gasoline products. It is for this reason that Volkswagen cancelled the stratified combustion technology on China FSI engine and only retained the homogeneous combustion mode. Companies and research institutions at home and abroad are also actively developing and designing new direct injection engines. For example, AVL is developing a new generation of stratified lean-burn direct injection engine technology based on injection guidance and laser ignition system. At present, domestic automobile companies such as FAW Group, Brilliance, Chery, Chang 'an and Geely are all developing GDI engines with theoretical air-fuel ratio or a combination of various combustion modes. The engine not only has the economy of diesel engine, but also maintains the characteristics of gasoline engine. Compared with PFI engine with mature technology, GDI has obvious advantages, but the problems of emission and combustion stability limit its universal application. At present, there are still some technical challenges when GDI technology completely replaces PFI technology, such as emission control, stable combustion control, fuel economy, performance reliability and control complexity. Bi Ye Design Report Reference 1 2 Translated by Gu Rulong. Development of lean-burn gasoline engine with low fuel consumption and high performance/valve. Foreign internal combustion engine, 1995( 1) Lu Zhanhua. GDI engine and its lean burn optimization technology. Diesel engine, 2003, (6):36-4 1. 3 Wang, Shouteng Toshi Utsumi, et al. New progress in lean combustion research of gasoline engines--from in-cylinder direct injection to homogeneous compression ignition. Automotive Technology, 2002, (8): 1-5. 4 Jian Jiang, Gao Xiyan. Study on gasoline direct injection technology in cylinder. New progress in research and development of homogeneous compression ignition engine. Automobile Engine, 2007(3): 1-7. Gao Zongying, Yuan Yinnan, Liu Shengji, etc. In-cylinder direct injection-the development direction of future automotive gasoline engines. Foreign internal combustion engines, 2000, (1): 24-36. Hou xianjun Technical measures to realize lean combustion of automotive gasoline engines. Automobile engine, June 2004 (154):1~ 4. 8 Xie Maozhao. A new concept internal combustion engine-super adiabatic engine based on porous medium combustion technology. Thermal Science and Technology, No.2, September 2003: 189 ~ 194.9 Zheng. Development and analysis of lean combustion technology for gasoline engines. Urban vehicles, 2007-6 :46~55. 10 Sun Qing, Qin Songtao, Zhang Yong. Homogeneous mixed compression ignition combustion of gasoline engine. 2006.1(91):14 ~17. graduation project (thesis) opening report 2. Problems to be studied or solved in this topic and research methods (methods) to be adopted: Problems to be studied: (1) (2) Expounding the significance and function of domestic automotive lean-burn engine technology development to social and economic development; (3) The necessity and significance of studying ultra-thin combustion technology are expounded. (4) Analyze the problems existing in various lean combustion technologies; Research means: Research means: under the guidance of teachers, through online access to information and library borrowing materials, analyze and think, clear up ideas, write an outline of the paper and complete the paper. Bi Ye design (essay) opening report Tutor's opinion: Tutor's opinion: 2010 65438+February 3rd Professional evaluation opinion: Person in charge: 2010 65438+February 3rd.