摘要本次我做的毕业设计任务是设计一台微型汽车变速器，经过多方考察和查询资料，我选定的设计任务是设计一台微型汽车上的前置前驱手动变速器，并且采用中间轴式变速器。这种变速器自身存在两个突出的优点：一、它是直接挡的变速器，汽车运行时，发动机产生的转矩会经过变速器的输入轴和中间轴直接输出，这种高效的形式会使得发动机造成的噪声减少，更极大的减少了齿轮和轴承的磨损；二、前置前驱手动变速器的中间轴和输出轴之间中心距较小，所以在一挡状态下仍旧保持着很高效的传动比。50273

本次设计任务参考了现在普遍生产的变速器作为参考的对象。根据汽车传动比和发动机转矩等参数，结合汽车变速器的机构原理，汽车构造等书籍并查询有关手册查询有关公式或者相关参数。计算出齿轮对、输入轴、中间轴、输出轴、键以及相关零部件的设计计算，并根据相关尺寸等参数，通过验证齿轮、输入轴、中间轴、输出轴等应力强度和刚度来证明本次设计的合理性。

本次微型汽车变速器的设计需要综合大多数机械基础知识，如理论力学，材料力学，机械原理，机械设计，机械设计基础等相关方面的知识。对机械的基本功底要求很高，需要查阅大量的相关手册等资料，与此同时要一边分析优化，是设计产品不但能在理论上合乎要求，更要在现实生活中能够可行。

毕业论文关键词：变速器，轴，传动比，齿轮

Abstract This task is to design a manual transmission used for the FR miniature type vehicle，it is the countershaft-type transmission. This transmission has two advantages: firstly, when you use the direct drive, the first and second shaft of the transmission output the engine torque directly, the transmission efficiency is very high in this case, the noise and the attrition of the gears and the bearings are slight; Secondly, the first drive also has bigger transmission ratio when the distance between the counter and second shaft (centre distance) is smaller.

This task uses the production which having existed in many enterprise as a design model. According to the drive ratio、the power rating、the maximum torque and so on, combining the Automotive design、the Automobile Engineering Manual and other related knowledge, search out modulus、pressure angle and other related daters, and calculate the size of the pinions、shaft related parameters. Checking gear contact stress、bending stress、shaft rigidity and strength to proof the rationality of the design.

Transmission design includes most basic mechanical knowledge, such as Basis of Mechanical Designing, Mechanical drawing, Principle of Machinery, Geometric Tolerance and Exchangeability Measurement, Metal Technology, Materials for Mechanical Engineering and so on. What’s more, consulting a large number of professional books relating this design, analyzing and improving this design constantly to ensure requirements not only in technology but also in practical application.

Key Words: transmission, shaft, transmission ratio, gear

目录

摘 要 I

Abstract II

引言 Ⅲ

1  绪论 1

1.1  本课题研究的目的和意义 1

1.2  本课题研究现状和发展 3

2  变速器传动机构布置方案 3

2.1  变速器类型的选择 4

2.3  齿轮型式选择 4

2.4  轴的结构分析