摘 要

配气机构的设计选择范围较小，但配气凸轮型线的设计时有多种选择，所有凸轮型线设计是目前配气机构设计的重点，利用软件算法求解凸轮型线优化函数，运用专业软件建立配气机构仿真模型进行计算分析，是目前配气机构设计的主要方法。

本文的主要工作是设计DF4102天然气发动机的凸轮型线，确定配气机构的选项并进行动力学分析。首先采用遗传算法求解以气门最大丰满系数为优化目标的凸轮型线工作段优化模型，借助配气机构仿真分析软件AWS-EXCITE TD中的CAM DESIGN功能设计了凸轮型线的过渡段，获得完整型线参数。根据运动学分析结果反复调整优化凸轮型线数据，最终获得了满足运动学特性要求的型线。然后确定该发动机的配气机构类型为双顶置凸轮轴型，根据相关参数创建了只含一个气门的配气机构单阀系动力学模型，进行了动力学仿真分析和验证，根据分析结果修改调整，确定了配气机构的结构和力学参数。最后，根据单阀系模型，建立了配气机构的整阀系模型，设计了各个气缸进、排气门的配气相位，最终的整阀系动力学分析结果表明，各个气缸进、排气门配气无明显干涉，配合良好，各个气缸在气门工作段范围内，凸轮与挺柱间的接触应力没有出现等于零的情况，证明各个气缸没有出现飞脱。

关键词：天然气发动机；凸轮型线优化；配气机构；动力学

Abstract

The design range of valve mechanism is small, but there are many choices in the design of CAM profile. CAM profile design becomes the critical step of valve mechanism optimization. Using software algorithm to solve the CAM profile optimization function, and professional software to establish valve mechanism simulation model for analysis is the main method of valve mechanism design.

The main work of this paper is to design the CAM profile of DF4102 natural gas engine, determine the option of valve mechanism and conduct dynamic analysis. Firstly, genetic algorithm was used to solve the optimization model of CAM profile with the maximum valve fullness coefficient as the optimization goal, and the transition section of CAM profile was designed by CAM DESIGN function in AWS-EXCITE TD to obtain the complete profile parameters. According to the kinematic analysis results, the CAM profile data were adjusted and optimized repeatedly, and finally the CAM profile that met the kinematic requirements was obtained. Then, the type of valve mechanism of the engine was determined to be DHOC. The dynamic model of valve mechanism with only one valve was created according to relevant parameters. The dynamic simulation analysis and verification were carried out. Finally, according to the single valve system model, the whole valve system model of valve mechanism was established, and the valve phase of each cylinder intake and exhaust valve was designed. The final dynamic analysis results of the whole valve system showed that there is no obvious interference between the valve intake and exhaust valve and the valve mechanism has good coordination. The contact stress between the CAM and the tappet is not equal to zero when each valve is in the working range.

Key Words：Natural Gas Engine；Cam Profile；Valve Mechanism；Dynamics

目 录

摘要…………………………………………………………………………...……......Ⅰ

Abstract…………...………………………………………………….....………….......Ⅱ

第1章 绪论 1

1.1本文研究的背景和意义 1

1.2国内外研究现状 2

1.3本文的主要研究内容 5

第２章 配气凸轮设计 7

2.1天然气发动机配气凸轮设计基础理论 7

2.2凸轮型线过渡段的设计 7

2.2.1过渡段设计的必要性 7

2.2.2过渡段的类型 8

2.2.3 过渡段的参数 8

2.3 凸轮型线工作段的设计 9

2.3.1 工作段型线设计理论 9

2.3.2 几种典型的工作段型线 9

2.4 本章小结 11

第３章 凸轮型线工作段遗传算法优化 12

3.1 数学优化模型的建立 12

3.2 Mat-lab遗传算法求解过程 13

3.2.1建立目标函数 13

3.2.2建立约束函数 14

3.2.3计算结果 17

3.3本章小结 21

第４章 凸轮型线评价与仿真分析 22

4.1凸轮型线评价和分析 22

4.2建立单阀系模型 22

4.2.1模型特征参数获取方法 22

4.2.2单阀系模型 24

4.3凸轮型线运动学分析 25

4.3.1凸轮型线主要参数 25

4.3.2运动学分析详述 26

4.4配气机构动力学分析 29

4.4.1气门的动力学升程、速度、加速度和落座力 29

4.4.2动力学凸轮与挺柱接触应力 32

4.5本章小结 33

第５章 配气机构整阀系模型动力学计算分析 34

5.1整体配气机构动力模型的建立与仿真 34

5.1.1整体配气机构动力模型的建立 34

5.1.2相位单元参数设置 34

5.1.3轴段模块的参数计算 36

5.2整阀系动力模型的仿真结果 37

5.2.1 各缸进、排气门的配气相位 37

5.2.2 各缸凸轮与挺柱的接触应力 39

5.3本章小结 41

第６章 总结与展望 43

6.1全文总结 43

6.2工作展望 43

参考文献 45

致 谢 47