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CG125摩托车发动机循环模拟与性能优化研究

A Study on Cycle Simulation and Performance Optimization for CG125 Motorcycle Engine

【作者】 文君竹

【导师】 张力;

【作者基本信息】 重庆大学 , 动力机械及工程, 2007, 硕士

【摘要】 随着发动机工作过程基础理论的深入研究和计算机技术的高速发展及其在工程领域的广泛普及和应用,循环模拟计算已经成为汽车和摩托车发动机在设计和调试阶段新技术的发展方向之一。循环模拟计算不受试验环境和试验条件的限制,可以揭示在试验中没有测量或不可能测量参数的大小,热力参数以及运转参数对发动机性能影响,预先提供优化设计方案,而且花费小、周期短。因此,针对国内摩托车基干机型CG125发动机,综合内燃机学理论及其循环分析方法、模拟分析工具和实验测试等技术手段,通过建立CG125型号摩托车发动机性能循环模拟计算模型,探讨各种结构参数对发动机性能的影响,从而掌握摩托车发动机循环模拟及性能优化的关键技术。本文以CG125摩托车发动机为研究对象,基于循环模拟原理,首先分析并采用了合理的数学模型和物理模型,包括缸内燃烧、传热及气体交换模型;管道摩擦损失、压力损失和传热模型。利用BOOST软件建立了正确的发动机性能循环模拟模型,详细探讨了模型中各模块参数的确定和输入,主要包括:进、排气及消声器系统的结构参数、气缸头的结构参数、进排气门升程及流量系数、空滤器模块参数、化油器模块参数、燃烧和传热模型参数、摩擦损失等。发动机台架实验的结果验证了模型的可靠性。同时,本文围绕发动机循环模拟计算进行了相关的实验测试,包括:气道稳流实验、气门升程的测试、机械损失的测试、发动机性能测试、进排气压力波动和缸内压力波动测试等。获得了大量建模和验模所需数据,探讨了测试数据和模拟模型参数间的相互转化。在此过程中,提出了一种发动机气门升程曲线的实验测试方法并形成了测试规范。在循环模拟模型的基础上,对发动机配气正时系统和进、排气系统进行了变参数优化计算和分析,并应用于CG125发动机中低转速性能的优化,提出了若干发动机中低速扭矩优化方案和途径。试验表明:改进后的发动机中低速动力性和经济性均得到了显著的改善,所论述的发动机性能循环模拟及优化技术的正确性得到证实。

【Abstract】 Along with the more deeply research of engine working process and quick development and its extensive use in engineering, the technology of cycle simulation has become one of the new technology development way in designing and debugging of automobile engine and motorcycle engine. Cycle simulation can disclosure the magnitude of parameters which aren’t measured or can’t measured in test. It also can indicate the impact of thermal parameters and operating parameters without the restriction of surrounding environment. In a word, cycle simulation can afford optimize design way in advance with less cost and time. In allusion to the CG125 motorcycle engine, the major type in China, variable structure parameters’influence on engine performance are discussed by the establishment of cycle simulation model of CG125 motorcycle engine, through integration of theory of internal combustion engine and its ways to cycle simulation, the tools of simulation analysis and tests and so on. Then the key technique of cycle simulation and engine performance optimization is gripped.The paper taking the CG125 motorcycle engine as the subject investigated. Based on the principle of cycle simulation, the appropriate mathematic model and physical model are analyzed and adopted above all, include: the models of combustion, heat transfer and gas exchange inside the cylinder and those of friction loss, pressure loss and heat transfer through pipes. The exact cycle simulation model of engine performance was created by the soft BOOST. Then all the module parameters of the model were discussed in detail, including the structural parameters of cylinder head, intake system, exhaust gas system and muffler. Besides, the lift range and discharge coefficient of intake valve and exhaust valve, the module of air cleaner and carburetor, the model parameters of combustion and heat transmission, the friction loss were also inputted. The result of engine bench test proved the reliability of the model.Meanwhile, several coherent tests were carried out according to the simulate calculation on engine performance, include: the tests of the steady flow in passage, the valve range curve, the mechanical power loss, the engine performance, the intake and exhaust pressure wave and that inside the cylinder, etc. A lot of the data that were requested in model building and checking were obtained, and the relationship between the testing data and the simulation parameters were discussed. In the course of research, a method of engine valve range curve measuring was established and so was the standard of the test.Based on the cycle simulation model, parametric optimizing computing and analysis of the timing system, the intake system and the exhaust gas system were carried out. Several optimizing way to improve torque below medium speed were put forward when it applied in the optimization of CG125 motorcycle engine performance. It has been proved by test that power performance and fuel economy can be improved obviously. Besides, validity of the cycle simulation and the optimize technology on engine performance were also proved.

  • 【网络出版投稿人】 重庆大学
  • 【网络出版年期】2007年 05期
  • 【分类号】U483
  • 【被引频次】11
  • 【下载频次】266
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