q276汽车发动机曲轴连杆组设计（本科毕业论文设计）.doc

Q276汽车发动机曲轴连杆组设计（本科毕业论文设计）

　摘要
发动机的曲轴连杆组是发动机最重要的部件之一，它承受着复杂的、变动的冲击载荷，是发动机设计的重点和难点，也是发动机性能评价的重要组成部分。因此要精确的对发动机的曲轴连杆组的运动做出精确的分析后，针对每个零件的受力特点和运动特点对零件进行设计。传统的设计方法很麻烦，而且不精确。采用C++ Builder可以自己开发出软件解决，解决计算中遇到的问题。
本文针对276Q小排量汽车发动机的重要机构—曲轴连杆组进行了设计研究，通过分析，确定了机构的主要设计参数，建立了发动机曲轴连杆组的分析模型，推导出滑块（活塞）的位移、速度、加速度、惯性力等的数学模型，用C++编写出活塞在每个转角的位移、速度、加速度、惯性力的计算程序，并导出其它零部件的运动，为机构动力分析提供了计算惯行载荷和位置分析数据。在分析发动机燃烧过程的基础之上，获得了发动机工作全过程作用在活塞上的的输入载荷随曲柄转角变化的历程。根据求得的外载荷进行载荷组合，为结构强度设计提供了载荷计算依据。在完成结构设计的基础上，在对重要零件的公差与配合进行选择计算，并绘制出用于加工制造的图纸。
本毕业设计课题的研究与实施，应用和加深了本科学习期间的大部分理论知识，还获得了很多新的理论知识，更重要的是将理论与工程设计紧密结合，增强了分析问题和解决问题的能力，对知识的综合运用和解决工程中的实际问题，在能力上获得了很大的提高，并得到了全面的锻炼。

关键词：汽车发动机，发动机设计，曲轴连杆组
 
ABSTRACT
The crankshaft-link group is one of the most important engine’s components, which sustains the complex and changeable impulse. It is the key point and difficulty of the engine design, and also an important part to eva luate engine’s performance.  So after accurate analysis motion of the crankshaft-link group, the parts should be designed according to its characteristics of the force and movement. The traditional design approach is inconvenient and imprecise.  The Problems encountered in calculation can be solved through the software developed with C++ Builder.
The paper is mainly about the design and research of crankshaft-link group, the main mechanism of the 276Q automobile (with low emission) engine. Trough the analysis of the main design, the Main design parameter was determined, and the analysis model of the crankshaft-link group was established. And people can deduce the mathematical model of the physical variables of the piston, such as displacement, velocity, acceleration, or inertia force and so on.  So people can write the program of these variables of the piston in every corner, and deduce the movement situation of other parts. All these provide the foundation of computing inertia load and the analysis of the displacement for the body dynamic analysis. Based On the analysis of engine combustion, people can observe input load of the piston changed with the change of the crank angle.  And then combine the load according to the extra load which has been gained, so as to provide a basis of load computing for the design of structural strength. After the structural design, the tolerance and cooperation of the parts will be chosen and calculated. Finally, make a drawing of parts for the processing.
During the research, implementation and the application of this graduate program what I get not only the deep understanding of most theoretical knowledge which learn in undergraduate, but also acquire much new theoretical knowledge. And the most important is my theoretical knowledge is closely integrated with engineering design and  it improve my comprehensive ability of problem-analyzing ,problem-solving and the comprehensive use of knowledge  to resolve the practical problems in the processing.

Keywords: automobile engine, engine design, crank connected rod group

目   录

中文摘要 Ⅰ
ABSTRACT Ⅱ
1绪论 1
  1.1国内外研究现状综述 1
  1.2主要研究内容和意义 2
  1.3本文的主要工作 2
 2发动机曲柄连杆组动力学 3
   2.1发动机燃烧过程分析 3
 2.2发动机曲柄连杆组运动学分析 4
 2.3发动机曲柄连杆组动力学分析 5
    2.3.1 缸内气体力 5
    2.3.2 活塞惯性力 6
    2.3.3 汽体力与活塞惯性力合成 6
    2.3.4 曲柄连杆组外力 9
    2.3.5 活塞连杆组力分析 9
    2.2.6 曲柄力分析 10
    2.2.7 输出扭矩与功率 10
 2.4本章小结 11
 3曲柄连杆组计算机辅助设计及CAD软件开发 12
 3.1用Borland C++ Builder编制分析软件界面 12
 3.2用Borland C++ Builder编制分析软件程序 13
 3.3本章小结 22
 4曲柄连杆组零件设计 23
 4.1曲轴的设计 24
 4.2连杆的设计及较核 24
    4.2.1 连杆的材料选择和尺寸的确定 24
4.2.2 连杆强度计算 25
 4.3连杆螺栓的设计 27
 4.4活塞的设计 27
    4.4.1活塞材料选择和设计要求 27
    4.4.2 活塞尺寸的确定 28
4.4.3 活塞计算强度较核 28
 4.5活塞销的设计 29
    4.5.1活塞销的设计要求 29
    4.5.2 活塞销的设计计算 29
 4.6滑动轴承的设计 30
 4.7本章小结 31
5公差与配合的选择 32
 5.1 活塞与汽缸孔的配合 32
 5.2 活塞与活塞环的配合 33
 5.3 活塞销与活塞以及连杆小头孔的配合 33
 5.4 连杆大头两侧与曲轴连杆轴颈开档的配合 35
 5.5 连杆大头孔与连杆轴瓦以及曲轴连杆轴颈的配合 35
6设计图纸说明 38
 6.1曲轴图纸说明 38
 6.2 轴瓦图纸说明 38
 6.3 活塞销图纸说明 39
 6.4 连杆体图纸说明 39
 6.5 连杆盖图纸说明 40
 6.6 连杆体的装配图纸说明 40
7结论 41
参考文献 42