随着废气涡轮增压技术的广泛应用和发动机强化程度的不断提高,发动机排气温度也随之增加,排气热端的零部件可靠性问题逐渐凸显。在涡轮增压汽油发动机缸盖上实施集成排气歧管方案(Integrated Exhaust Manifold,简称IEM),设计水套对排气道进行冷却,能取消原有大量的排气系统高温部件降低失效风险,大幅降低了发动机采购成本,同时对暖车时间和整车油耗也有正面贡献。本文以奇瑞量产的E4T16涡轮增压汽油发动机为平台,在此基础上实施IEM方案。对集成缸盖的水套设计进行了系统研究,完成了不同水套方案的设计分析,对最终实施方案进行了试验验证。本文在给定边界下,利用Creo软件建立不同水套方案的三维模型,使用FIRE软件完成水套CFD流场计算,通过对水套流速/换热系数的对比完成水套的初步方案选定,采取了上下分片式水套结构。使用一维热力学计算和参考机型试验结果提供的燃烧边界数据。在ABAQUS软件中进行温度场计算分析,调整优化水套结构尺寸,使缸盖燃烧室鼻梁区最高温度235℃,排气道壁面温度在参考的200-230℃范围内。使用温度场计算的方案模型,进行在装配工况、热工况、爆压工况三种工况组合下的结构强度计算,得到机体对应的应力和应变结果。带入到FMEAT软件中,得到缸盖整体的高周疲劳安全系数(Safe Factor,简称SF)分布,计算结果满足SF>1的要求。开展了设计方案的样机制作,在测试台架上分别进行了排温对性能影响测试,冷却系统温度场测试(缸盖部分),整车采暖升温测试以及发动机台架耐久性测试,设计方案最终通过验证,达到预期目标。本文通过对发动机新技术应用的工程化实施,将产品CAE仿真选优与试验测试项结合,有效的完成了产品方案的设计论证,保证了设计开发的结果。其方案实施结论和研究方法对于公司后续的产品开发和技术应用具有较好的借鉴作用。
With the wide application of turbocharging and the continuous improvement of engine performance degree, the exhaust temperature also increases, and the reliability of parts at the exhaust hot end is prominent. Implementation the proposal of Cylinder head Integrated Exhaust Manifold(IEM)in turbocharged gasoline engine by design cooling water jacket of Exhaust port, will cancel the original Exhaust system of high temperature components, reduce the risk of failure, and significantly reduces the engine purchase cost, also has a positive contribution to warmup and fuel consumption on vehicle.In this paper, the E4T16 turbocharged gasoline engine produced by Chery is used as the platform, and the IEM is implemented on this basis. The design of the water jacket of the integrated cylinder head was researched systematically, The different water jacket proposals were designed and compared, and the final implementation proposal was tested and verified.In this paper, under the given boundary, 3D models under different water jacket proposals were established by CREO software, the flow field calculation of water jacket was completed by FIRE software, and preliminary proposal selection of water jacket was completed by comparing water jacket velocity/heat transfer coefficient, and the upper and lower sliced-type water jacket structure was adopted.The combustion boundary data are provided by one-dimensional thermodynamic calculation and reference to model test results. The ABAQUS software was used to calculate and analyze the temperature field, and the structure size of the water jacket was adjusted and optimized, so that the maximum temperature in the nose bridge area of the cylinder head combustion chamber was 235℃, and the exhaust wall temperature was within the reference range of 200℃~230℃.The proposal model of temperature field calculation is used to calculate the structural strength under the combination of three working conditions, namely, assembly working condition, thermal working condition and explosion pressure working condition, and the corresponding stress and strain results of the airframe are obtained. The high cycle fatigue safety factor distribution of the cylinder head was obtained by putting it into FMEAT software, and the calculation results meet the requirements of SF>1.The prototype of the design proposal was made, and the test of the influence of exhaust temperature on the performance, the temperature field test of the cooling system (cylinder head part), the heating temperature rise test of the vehicle and the reliability test of the whole machine bench were carried out on the test bench. The design proposal basically reached the expected goal.In this paper, through the engineering implementation of the application of new engine technology, the product CAE simulation optimization is combined with the test items, and the design demonstration of the product proposal is effectively completed, and the results of design and development are guaranteed. The conclusion and research method of the proposal implementation have a good reference for the company’s subsequent product development and technology application.