发动机曲轴轴承的多目标综合优化毕业论文

 2022-06-21 11:06

论文总字数:27844字

摘 要

现在曲轴轴承优化设计的研究对象一般仅以轴承单一零件进行,不考虑其与所处系统其它部分的相互影响。但是曲轴轴承和曲轴作为一个系统存在,内燃机工作时曲轴轴承和曲轴之间存在着各种不可分割的机械行为,它们相互作用、相互影响,性能也息息相关。因此,对曲轴轴承进行优化设计时,有必要考虑整个曲轴一轴承系统中不同零件的多个评价目标并对它们进行综合优化,这样曲轴轴承优化模型才能更加合理、接近实际。

本文以多缸柴油机曲轴一轴承系统为研究对象,设置了轴承和曲轴的结构尺寸设计空间,并分别计算了两个零件在各自设计空间中每个设计点的轴承润滑性能和曲轴强度,建立了轴承的润滑性能数据库、曲轴强度数据库及曲轴质量计算公式。

进行了发动机曲轴轴承的多目标综合优化。优化设计中,选取曲轴轴承总平均摩擦功耗和曲轴质量为目标函数,采用MATLAB计算。

将综合优化设计结果与曲轴轴承单目标优化设计结果进行了对比,综合优化结果表明,曲轴轴承的摩擦功耗和曲轴的质量得到进一步的降低,曲轴安全系数有所增加,比仅以曲轴轴承为研究对象进行的单目标优化设计更合理。

关键词:内燃机;曲轴轴承;多目标;优化设计: MATLAB计算

Integrated Multi-Objective Optimization of Engine Crankshaft Bearings

Abstract

Currently crankshaft bearing was usually taken as the only research object when it was optimized, but the interaction between crankshaft and bearings was ignored. As a system, crankshaft and bearings were included, there were serious of mechanical behavior between them when internal combustion engine works. They affect each other, performance were also related. Furthermore, which could be lead to a bad structure and performance of crankshaft, and could not met the requirements. Based on this situation, it's necessary to consider more evaluation objectives which belong to different objects of crankshaft-bearing system when taking a integrated optimization design to crankshaft bearing. Surely, it's a more reasonable and more actual crankshaft bearing model.

This paper takes crankshaft-bearing system of Multi-cylinder diesel engine as the research object, devises design spaces for crankshaft and bearing's structure sizes, And at the design point in each of their design space, the two parts' performance were calculated-lubrication of bearings and the strength of crankshaft. Established the database of bearing lubrication, the database of crankshaft strength and the formula for crankshaft quality's calculate.

Integrated Optimization Design of Crankshaft Bearing Based on Multi-Objective of Crankshaft-Bearing System was carried out in this paper. Total average power loss of bearing friction and the quality of crankshaft as the objective functions were taken in the intelligent optimization, while Particle Swarm Optimization(PSO) with the idea of decreasing inertia weight based on exponential curve strategy and simulated annealing(SA)were taken as the algorithms. The results of the two algorithms were compared with the ones of primary design. Optimization results show that, 26.2% and 25.8% reduction in total average power loss of beating friction were presented under the two algorithms while all the quality of crankshaft were reduced 5.3%, which were more reasonable than primary design.

The results were compared with the ones of optimization design of crankshaft bearing based on one optimization object. Integrated optimization results show that total average power loss of bearing friction and the quality of crankshaft were reduced more than the latter optimization Algorithm, crankshaft strength was increased at the same. So Integrated optimization design was more reasonable than one-object optimization design which just took crankshaft bearing as the research object.

Keywords: Internal combustion engine; Crankshaft bearing; Multi-Objective;

Optimization design; MATLAB calculate.

目录

摘要 I

Abstract II

第一章绪论 1

1.1前言 1

1.2曲轴轴承的优化设计现状 1

1.2.1数学模型的建立 1

1.2.2轴承优化设计的求解方法 2

1.3曲轴的优化设计 3

1.3.1曲轴模型的建立 3

1.3.2数学模型的建立 3

1.3. 3曲轴优化设计的求解 4

1.4本文研究的意义与研究内容 5

1.5本章小结 5

第二章内燃机曲轴—轴承载荷变形对轴承性能分析 7

2.1引言 7

2.2曲轴轴承负荷的计算 7

2.2.1连杆轴承负荷的动力计算 7

2.2.2整体曲轴有限元计算 8

2.3曲轴受载荷变形对轴承润滑影响分析的基本算法 9

2.3.1基本方程 9

2.3.2曲轴轴承润滑分析的算法 11

2.4润滑分析计算及润滑性能数据库的建立 13

2.5本章小结 13

第三章多缸柴油机曲轴强度及质量的计算与分析 15

3.1引言 15

3.2 建立实体模型的曲轴 15

3.3 曲轴轴承质量计算 17

3.4小结 17

第四章曲轴轴承的多目标综合优化设计 18

4.1引言 18

4.2发动机曲轴轴承的多目标综合优化数学模型 18

4.2.1目标函数 18

4.2.2设计变量 19

4.2.3约束条件 19

4.3内燃机曲轴轴承优化设计实例 21

4.3.1发动机曲轴轴承的多目标综合优化设计 21

4.3.1曲轴轴承综合优化设计与单目标优化设计的比较 23

4.5本章小结 26

第五章总结与展望 27

5.1总结 27

5.2展望 28

参考文献 29

致谢 31

第一章 绪论

1.1前言

内燃机曲轴轴承和曲轴的优化设计是设计现代高性能内燃机的要求。相对于以往传统设计方法,现代的优化设计过程更加注重曲轴轴承和曲轴的实际运行情况。优化后的曲轴轴承和曲轴不仅在结构和尺寸上更加合理,运行寿命得到延长,而且设计周期大大降低。在国内外学者的共同努力下,曲轴轴承和曲轴的优化设计得到了比较迅速的发展。但是,目前的优化设计基本都是针对曲轴轴承或曲轴单一零件进行的,没有考虑曲轴轴承和曲轴之间存在的各种不可分割的机械行为,实际上曲轴轴承和曲轴是相互作用、相互影响的。因此曲轴轴承或曲轴单个零件得到优化,与之相对应的零件未必也得到优化,其性能或运行状态甚至有可能恶化。笔者在论述了曲轴轴承和曲轴优化设计研究现状的基础上,讨论并展望了研究中尚待进一步研究的问题。

1.2曲轴轴承的优化设计现状

1.2.1数学模型的建立

1.2.1.1目标函数

优化设计的目标函数是以设计变量来表示设计所要追求的某种性能指标的解析式[1],包括单目标函数和多目标函数:

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