Thermal Load Analysis And Structure Optimization For CA4GC Gasoline Engine

Downsizing and turbo charging in combination with direct injection is now commonly regarded as a key technology for gasoline engines to cope with the challenges of fuel economy enhancement and driveability improvement. So the company will develop a new turbo charging and direct injection 1.8L gasoline engine based on a naturally aspirated PFI 2.0L gasoline engine. With the development of internal-combustion engine towards turbo charging and direct injection constantly, the problems of its heat transfer and thermal load become more and more outstanding. Then how to settle the thermal load problem of internal-combustion engine availably and improve the reliability and usage life of the heated parts of internal-combustion engine becomes more and more important and urgent. Because of the influence of thermal load, many malfunctions, such as abnormal wear of the heated parts of internal-combustion engine, corrosion and ablation of materials and destroy by thermal fatigue etc, often occurs. And it influents the power capability, economic capability and reliability of internal-combustion engine directly or indirectly. Accordingly, the research of heat conduction and thermal load is becoming an all-important project in the research of internal-combustion engine.The research method of thermal load includes measure temperature test and numerical simulation. As far as test method is concerned, temperature should be measured in the piston, the cylinder head and the cylinder block. Researchers can obtain macro information about thermal load. Although this method can provide relevant data of temperature and estimate thermal load of engine, because of complexity of structure of engine, it is not sufficient to obtain generally real thermal load of engine. So this method has some flaws .Another research method is numerical simulation. It bases on heat transfer theory and uses relevant FEA software to analyze thermal load of engine. It can provide detailed distribution of temperature of the piston, the cylinder head and the cylinder block .It can become an important supplement for test method. With the increasing of engine duty, engine parts', mainly the key parts of engine, thermal load analysis become more and more important in engine design and improvement process nowadays. In this paper, we have measured temperature of the key parts of the naturally aspirated PFI 2.0L gasoline engine, the method of the temperature measurement of the piston is eutexia tucks, which are in the top and skirt of the piston; the method of the temperature measurement of the cylinder head is thermocouple, which are between the inlet valve seat inserts and exhaust valve seat inserts; the method of the temperature measurement of the cylinder head is thermocouple, which are in the TDC, middle and BDC of the cylinder bore. And the test analyzed the thermal load of the piston, the cylinder head and the cylinder block at the different water temperature. The Finite Element Analysis (FEA) is a mainly method for engine thermal load analysis. This research is use the Finite Element Method (FEM) to simulate thermal load of engine parts, the analysis process is carry out in ABAQUS. This paper is mainly about the structure design and thermal load FEA simulation of cylinder block at the stage of the beginning of one model engine design. Base on the analysis result of cylinder block, new structure been designed. Base on the analysis of these three parts'thermal load and influence factors, the thesis educed the base thermal load condition of each part and the mail influence boundary condition. The structure factor influence of cylinder block also been educed.Grid is a basis of simulating computation .Its density and quality will decide FEA precision and efficiency. The principle of meshing grid is to maintain coherence between the computational field and the real domain. On the premise of maintaining computational precision, the size and type of grid shall be adjusted and the number of grid shall be reduced for increasing the computational efficiency. Hpermesh are used to mesh the cylinder head and cylinder block.The main work content:1. In this paper, we have measured temperature of the key parts of the naturally aspirated PFI 2.0L gasoline engine, the method of the temperature measurement of the piston is eutexia tucks, which are in the top and skirt of the piston; the method of the temperature measurement of the cylinder head is thermocouple, which are between the inlet valve seat inserts and exhaust valve seat inserts; the method of the temperature measurement of the cylinder head is thermocouple, which are in the TDC, middle and BDC of the cylinder bore.2. And the test analyzed the thermal load of the piston, the cylinder head and the cylinder block at the different water temperature.3. This research is use the Finite Element Method (FEM) to simulate thermal load of engine parts, the analysis process is carry out in ABAQUS, and compared with test result and FEA result.4. On the basis of computational analysis, three different improvement cases are applied for the improved engine, calculating the improvement models and confirming the more ideal optimizing scheme.The main conclusion:1. Through measured temperature test, we got the thermal load of the prototype engine.2. When the temperature of water raise, the temperature of engine raise.3. Base on the analysis result of numerical simulation of the prototype engine, the temperature in TDC of the cylinder bore is high.4. Base on the analysis result of numerical simulation of the TC/DI engine, the temperature in TDC of the cylinder bore is not allowed.5. By comparing the three improvement cases with the baseline one ,the effect of case 3 are ideal, structure alteration can be put into practical projects.