摘 要

本次毕业设计的选题是普及型轿车5速变速器，设计的参考原型是捷达2017款 1.4 TSI手动变速箱，根据官方给定的技术参数来完成变速箱主要零件的强度计算及校核，推算出变速器具体的结构尺寸参数，并绘制变速系统总成图和主要零部件图。

本说明书第一部分的序言是本次毕业设计对任务及具体要求的详细介绍。

本说明书的重点是设计部分，它主要包括结构分析、方案论证、计算和校核。其中结构分析是对所选的结构中各主要零部件进行参数的设计计算，包括机械式变速器的中心矩、齿轮参数、传动比的设计计算，还包括输入轴，中间轴和输出轴的设计。校核计算部分则是对设计计算的主要零部件进行强度校核。它在各零部件的参数设计计算出来之后直接给出。

关键词：变速器 设计 计算 校核

Abstract

In terms of the development of transmission technology, it’s easy to notice that the whole motor drive system is the integral part of the technology, which also stands for the level of automotive technology. For centuries, energy, environment, new material technology, advanced manufacturing technology and information control technology are important fields of science and technology development. All in all, those scientific and technological progress contributed to the development of transmission system, which is the heart and soul of the motors.

The topic of this graduate design is the calculation and design of general sedan five gear transmission, whose prototype is the transmission of 2017 Jetta 1.4L TSI Manual. It’s organized according to the given official technical specifications to accomplish the calculation and check of the main parts in transmission, to get the concrete structure size and parameter of the transmission, and draw the drafting of transmission system and main parts.

The first part of this paper is the preface, which is a detailed instruction of the task and specific requirements of the graduate design.

The major part of the paper is the design section, it mainly includes structure analysis, program demonstration, calculation and verification. Structure analysis is the design and calculation to parameters of the important parts of the chosen structure, which includes the central moment of mechanical transmission, gear parameters, design and calculation of gear ratio as well as the design of input shaft, intermediate shaft and output shaft. Verification and calculation part is the strength check of the main designed parts, which will be derived from the result of calculation about all the parts specifications.

Keywords：transmission analysis calculation checking

Content

Chapter 1 Introduction 1

1. Introduction 1

1.1 Preface 1

1.2 The function and requirements of automotive transmission 3

1.3 The graduation design related tasks and requirements 3

1.4 Design effort 4

Chapter 2 Transmission Program Demonstration 5

2.1 Transmission type selection and transmission design 5

2.1.1 The construction technique 5

2.1.2 The radial dimension of the transmission 5

2.1.3 The transmission efficiency of the transmission 5

2.2 Analysis of transmission mechanism 6

2.2.1 Layout of reverse gear 7

Chapter 3 Selection and Calculation of Main Transmission Parameters 8

3.1 The design of the initial data 8

3.2 Determination of transmission ratio of each gear in transmission 8

3.3 Determination of center distance A 9

3.4 Gear parameter 10

3.4.1 Module 10

3.4.2 Pressure angle 11

3.4.3 Helix angle 11

3.4.4 Tooth width B 11

3.5 Brief summary of this chapter 11

Chapter 4 Gear Design Calculation and Check 12

4.1 The design and calculation of gear wheel 12

4.1.1 The distribution of first gear tooth number 12

4.1.2 The distribution of second gear tooth number 14

4.1.3 The distribution of third gear tooth number 15

4.1.4 The distribution of fourth gear tooth number 17

4.1.5 The distribution of fifth gear tooth number 19

4.1.6 The distribution of the tooth number of the reverse gear 21

4.2 Calculation of the strength of the teeth and material selection 21

4.2.1 Cause of damage to the gear 21

4.2.2 Selection principle of gear material 21

4.2.3 Calculating the torque of each axis 22

4.2.4 Calculation of bending strength of teeth 22

4.2.5 Contact stress of gear teeth 26

4.3 Brief summary of this chapter 29

Chapter 5 Design and Calculation of Shaft and Selection and Check of Bearing 31

5.1 The design and calculation of shaft 31

5.1.1 Technological requirements for shafts 31

5.1.2 The diameter of the primary axis 31

5.1.3 Calculation of the stiffness of the shaft 32

5.1.4 Strength design of shaft 34

5.2 Selection and check of bearings 36

5.2.1 The bearing selection and check of the input shaft 36

5.3 Brief summary of this chapter 38

Chapter 6 Selection of Transmission Synchronizer and Control Mechanism 39

6.1 Selection of synchronizer 39

6.1.1 Working principle of synchronizer 39

6.1.2 The determination of the main parameters of the synchronization ring 39

6.2 Operating mechanism for the transmission 41

6.2.1 Function of transmission control mechanism 41

6.2.2 The requirements transmission shall meet 41

6.2.3 Shift position 42

6.3 Brief summary of this chapter 42

Chapter 7 Conclusion 43

Reference 44

Appendix 45

Thanks 47

Chapter 1 Introduction

1. Introduction

1.1 Preface

In recent years, the development of automobile gearbox has been growing by leaps and bounds, from the early stage manual transmission to the afterwards semi-automatic transmission, and then to the automatic transmission and current double-clutch transmission, CVT [1]. To today, transmission is also an important indicator of vehicle selection by vehicle buyers, just like Zhisheng Yu [3] said, we also have more and higher requirements for transmissions, the development of transmissions is also very important. For the moment, the domestic transmission production is divided into two categories, one kind is the manufacturers such as First Automotive Works, Dongfeng for transmission, supporting the production of its own brand car, and another is like Tangshan Aisin Gear Company, the production of the corresponding transmission for other car manufacturers. But in the unknown future, maybe we will not be satisfied with the existing space, then the situation the cars will have to face will be increased, the status of insufficient engine output will be resolved by transmission, which will make the car more comfortable in the face of more complex situations[4]. At present, the transmission can be divided into three types, namely, stage type, stepless type and integrated type, at present, the most universal type of transmission used is the stage transmission. It uses a gear drive and has a lot of fixed transmission ratio. According to the different type of gear, they are divided into fixed axis transmission and two axis rotary speed variation. Now, cars and medium-sized truck transmission generally choose three to five forward gears and one reverse gear, in the heavy truck combinations, more gears are equipped. The gear shift refers to the number of forward gears [5]. Within a certain numerical range, the transmission ratio of the CVT can vary infinitely, it is generally divided into two types of power and hydraulic. The transmission part of power continuous variable is a DC series wound motor, such transmissions are widely used on the trolley, and super heavy dump truck driveline also begin using this kind of power transmission. The member of hydraulic continuous transmission is hydraulic torque converter.

From the point of view of global transmission applications, the use of manual transmission has a downward trend, automatic transmission has become the trend of the development, the use of hydraulic automatic transmission has reached a very high proportion, Basically now all the cars are equipped with automatic transmission and manual transmission of these two kinds of transmission, but most luxury cars are only equipped with automatic transmission (such as the Benz S - class and BMW 7 Series). Automatic transmission cars have played an important role in developed countries. According to the different countries of the world situation, there is still a big difference in the number of automatic cars [7]. At present, the Automatic Manual Transmission (AMT) in the global passenger car automatic transmission market share cannot be compared with the automatic transmission (Automatic Transmission, AT). But due to the inherence advantages of AMT as well as it is able to make use of the existing manual transmission (MT) production line for certain transformation production, if with a large number of the production of AMT, its manufacturing costs will be greatly reduced, this will also makes the AMT an important part of the automatic transmission. The impact of the AMT shift on the heavy vehicles is relatively on the small side. So the natural dominant position of AMT in heavy vehicles will be better utilized.

EMT transmission is the addition of a few General Company patented technology based on AMT automatic transmission. Which has a function of crawling as the imitation of automatic transmission, in the case of using forward gear, it’s just need to loosen the brake that the car will slowly crawling, instead of showing a retreat or trend that is not moving, It can be said that the EMT transmission is an upgraded version of the AMT transmission. This type of semi-automatic transmission is actually based on a conventional manual transmission after train working under the joint control of the electronic and mechanical, the car has completed the shift and other operations. The transmission was first used on Ferrari's F1, and Audi R8 also uses this semi-automatic transmission. This semi-automatic transmission is quite mature in the use of European cars. The 911 Porsche Tiptronic 6 speed tiptronic transmission allows drivers not only to use simple automatic gear to drive easily, but also to use manual gear to increase driving interest. This car uses shift paddles “ ” and “-” to select gear. When hanging in the condition of D gear, a reduction gear shift paddles (-) or ( ) add gear can give a person a kind of manual or automatic illusion. In fact, it’s still an upgraded version of automatic transmission [8~10].

1.2 The function and requirements of automotive transmission

Transmission function:

1. You can change the transmission ratio, increasing the range of driving torque and rotational speed, to adapt to different driving conditions, and allow the engine to work in reasonable conditions.
2. In the same direction as the engine rotates, the car can go backwards.
3. Cut off power transfer to let the engine start and idle, make the transmission gear shift or power output more convenient.

The transmission should generally be equipped with reverse gear, because you cannot change the direction of rotation of the engine under the condition of the vehicle can travel backwards.