Graduation Design (Thesis) of Wuhan University of Technology

“Design of city SUV mechanical transmission”

School： International Education College

Specialty amp; Class： Automobile gj 1401

Student Name: Xiong Na

Tutor: Guo Huiru, Lecturer

May, 2018

Statement of Originality

I solemnly declare that the submitted paper is the independent study conducted by the Institute under the guidance of my mentor. Except for the content specifically quoted and cited in the text, this paper does not include any results that have been published or written by any other individual or group. I fully realize that the legal consequences of this statement are my own responsibility.

Copyright Letter of Authorization to the Dissertation

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Abstract

As an important part of the automobile transmission system, the transmission is used to change the torque and speed of the engine to the driving wheel, so its performance affects the power and economic indicators of the automobile, which is undoubtedly the key to reform and innovation. This article is about design and researching a three-axis, five-speed manual transmission, elaborated on the working principle of the transmission, and selecting some standard parts. Detailed design calculations were made for the gears and shafts of the transmission, and strength checks were performed. Finally, the three-dimensional model of the designed transmission was modeled by using CATIA, and the model was drawn using CAD.

Key Words：Gearbox, gear ratio, number of teeth, shaft, Catia

Contents

Statement of Originality i

Copyright Letter of Authorization to the Dissertation ii

Abstract iii

Chapter 1 Introduction 1

1.1 The purpose and significance of the research 1

1.2 Domestic and foreign research status and development trend. 1

1.2.1 Development status of domestic transmission 1

1.2.2 The development status of foreign transmission 3

1.3 Main content of the thesis 3

Chapter 2 Structural Types and Options of Mechanical Transmissions 5

2.1 Structure of Mechanical Transmission 5

2.2 The overall structure of the transmission program 5

2.2.1 Two-axis transmission and three-axis transmission 5

2.2.2 Reverse block arrangement 6

2.2.3 Gear type 7

2.2.4 Structure of gear shift 7

2.2.5 Bearing type 7

Chapter 3 Design and Calculation of Main Structural Parameters of Transmission 8

3.1 Maximum and minimum transmission ratios and other gear ratios 8

3.1.1 Minimum transmission ratio 9

3.1.2 Maximum transmission ratio 11

3.1.3 Gear number, transmission ratio range and other gear ratio distribution 12

3.2 The center distance of the transmission 13

3.3 Determination of gear parameters 14

3.3.1 Gear wheel normal module 14

3.3.2 Pressure angle 14

3.3.3 Helical gear helix angle 15

3.3.4 Tooth width 15

3.3.5 The distribution of gear teeth 16

3.4 Strength Check of Transmission Gears 21

3.4.1 Calculating the Torque of Each Axis 21

3.4.2 Tooth strength calculation 22

3.5 Axis design calculation 28

3.5.1 Process Requirements for Axes 28

3.5.2 Estimation of shaft diameter 29

3.5.3 Shaft stiffness and strength check 30

Chapter 4 Synchronizer Selection 41

4.1 Determination of the main dimensions of the lock-ring synchronizer 41

Chapter 5 Selection of Transmission Control Mechanism and Principle of Cabinet Design 43

5.1 Selection of Transmission Control Mechanisms 43

5.2 Transmission Case Design Principles 43

Summary 45

References 46

Acknowledgements 47

Figure Contents

Figure 1: Two-axis transmission diagram 5

Figure 2: Three-axis transmission diagram 5

Figure 3: Reverse layout scheme ^[16] 6

Figure 4: Car power balance diagram with different reduction ratios ^[16] 10

Figure 5: Transmission structure diagram 17

Figure 6: Reverse Gear Engagement Diagram 20

Figure 7: Tooth form factor 23

Figure 8: Deflection and rotation of output shaft 33

Figure 9: Deflection and rotation of the intermediate shaft 35

Figure 10: Calculating Bending Moment 38

Figure 11: Lock-ring synchronizer ^[18] 41

List of Tables

Table 1: The main parameters of the car 8

Table 2: Transmission ratio of each gear and gear ratio of final drive 13

Table 3: Normal modulus of automobile transmission gears 14

Table 4: Tooth width for each gear selection 16

Table 5: Gears on the output shaft strength check 38