摘 要

汽车变速器是汽车传动系统的主要变速机构，其结构性能对汽车的动力性能、燃油性能、换挡操纵的可靠性与轻便性、传动的平稳性与效率都有影响。通过研究汽车在地起步、爬坡、转弯、加速等行驶工况中变速器的挡位变化，进行变速器的各个部分设计，使发动机在最有利的工况范围内工作。

本设计根据给定的主要技术指标，选择东风EQ1092型汽车作为改进的原形，通过查阅文献和标准，还原该车变速器的设计过程。

本说明书首先对变速器传动机构的布置方案进行分析，阐述了传动机构的设计思路分析了换挡机构的选择原则，主要介绍了倒挡的布置方案。

然后，计算了机械式变速器主要参数，在不影响稳定工作状态的情况下，减小变速器的体积和质量，同类型结构设计采用同一尺寸，旨在改善加工性和经济性。

最后，选择同步器的类型，并对操作机构进行设计。根据变速器的具体要求、结构特点等方面综合考虑,采用简单可行的设计方法, 有效地提高变速器的换档能力，使设计出来的变速器能满足车辆高动力性和高经济性的要求。

关键词：变速器；中型货车；三轴五挡；机械式；设计

Abstract

Auto transmission is the main auto transmission system, the structure performance gear mechanisms for car dynamic performance, fuel performance, reliability and shift anipulated portability, transmission and steadiness and efficiency are having an impact. Through the research to start, climbing a car in turning, accelerate, such as in the running mode,transmission shift transmission changes each part of the design, make the engine at the most favorable conditions range work.

This design according to the given its main technical indices, choose EQ1092 type of dongfeng automobile as improved to archetype, through the literature and standard, restore the vehicle transmission design process.

This manual transmission transmission's first to analyze layout, this paper expounds the design idea of driving mechanism analyzed the choosing principle, shift agencies mainly introduced the reverse gear arranging scheme.

Then, the calculation of the mechanical transmission main parameters, in does not affect the steady working state by reducing the volume and quality, transmission with type structure design USES the same size, aims to improve workability and economy.

Finally, choose the type and synchronizer designed for operators. According to the specific requirements of the gearbox, structural features, and other comprehensive consideration, using simple and feasible design methods, effectively improve the transmission shifting ability, make designed can meet vehicle transmission of high performance and fuel economy of high requirements.

Keywords: Transmission; Bachelor’s Degree; Triaxial five block; Mechanical; Design

Table of Contents

Chapter 1 Introduction...............................................1

1.1 Outline the background and purpose of the topic.......1

1.2 Research status at home and abroad......................1

　1.3 The study of the selected topic.....................2

1.4 The main content of the design results and significance.3

Chapter 2 Overall Design.....................................4

2.1 Task book given parameters.....................................4

　2.2 Design should meet the basic requirements.............................4

2.3 Transmission type selection.............................5

　2.4 Gearbox Transmission Analysis..........................5

2.4.1 Selection of shifting mechanism ...........................5

2.4.2 Reverse layout .................................6

2.5 Design.........................................7

2.6 Chapter summary.......................................7

Chapter 3 Transmission Design Calculations..............8

　　3.1 The diameter of the shaft..................................8

　　3.2 Transmission ratio range.......................................8

　　3.3 Transmission bearings...................................9

　　3.4 Center distance....................................10

3.5 Dimensions......................................10

3.6 Gear parameters...............................11

3.6.1 Modulus selection.......................11

3.6.2 pressure angle................................11

3.6.3 Helix angle............................ 11

3.6.4 Tooth width.................................................12

3.7 The allocation of gear teeth...........................12

3.7.1 Determine the number of teeth of a gear .......13

3.7.2 Correct center distance ..............13

3.7.3 Determine the number of teeth of the constant mesh transmission gear pair ..............................................15

3.7.4 Determine the number of teeth in each other gear…17

3.7.5 Determine the number of reverse spur gear teeth .......22

3.8 Chapter summary.........................................23

Chapter 4 Checking Gears...................................24

4.1 Damaged form of gear........................................24

4.2 Calculate the torque of each axis...........................24

4.3 Gear strength calculation......................................25

4.3.1 Reverse spur gear bending stress.....................25

4.3.2 Helical gear bending stress..............................26

4.3.3 Teeth contact stress................................27

4.4 Chapter summary.......................................30

Chapter 5 Design Calculations for Transmission Shafts and Bearings. ............................ ............................31

5.1 Primary shaft length of transmission shaft....................31

5.2 Shaft design....................................................31

5.3 Transmission shaft strength calculation.................32

5.3.1 Gear and shaft force gauge........................32

5.3.2 Axis strength calculation....................32

5.3.3 Shaft stiffness calculation..................37

5.4 Transmission bearing selection and check......................40

5.4.1 First axis bearing selection and check................40

5.4.2 Second axis bearing selection and check................42