Graduation project of Wuhan University of Technology（paper）

Design of manual transmission for light commercial vehicle

College (Department)： Institute of International Education

Professional class: Auto gj 1603

Student Name: Li Lei

Instructor: Yang Ying

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Abstract

In this paper, we design and improve the transmission of Jiangling new generation Quanshun. By consulting the data parameters and national standards, we design the parts of the transmission, learn the design method and route of the transmission, and try to restore the design process of the manual transmission. With the help of the analysis software RomaxDesigner, this design carries out static analysis after the parts are assembled, including the strength analysis and life analysis of shafts and bearings, etc., and takes this result as the basis of the optimal design, to get better design results as much as possible, and to obtain a transmission with better performance after repeated design and verification.

This paper mainly studies the design route of the transmission. Starting from consulting the parameters of the selected model, it determines the transmission mode, gear number, specific parameters of the transmission parts and their check and other important parameters of the transmission, and analyzes and optimizes them in the analysis software, and finally establishes the model, thus completing the whole process of the optimization design of the transmission.

The feature of this paper is to use the gear design software of RomaxDesigner to analyze and check the design of gearbox. This software has excellent effect on the analysis of various parts of gearbox. By using this software, the purpose of optimizing the design of various parts of gearbox is achieved.

Key Words：Light commercial vehicle; three axle six speed transmission; RomaxDesigner

contents

Abstract I

Chapter 1 Introduction 1

1.1 purpose and significance of the study 1

1.2 research status at home and abroad 2

1.3 basic contents and measures of research and design 3

Chapter 2 Determination of transmission scheme 4

2.1 selection of transmission type 4

2.2 Selection of gearshift mechanism 5

2.3 The form and arrangement of reverse gear 6

2.4 Overall transmission plan 7

2.5 summary of this chapter 8

Chapter 3 basic parameter design of transmission 9

3.1 main parameters of target model 9

3.2 Transmission ratio 10

3.2.1 Range of transmission ratio 10

3.2.2 determination of gear I ratio 10

3.2.3 Determine the transmission ratio of other gears 12

3.3 Center distance A 12

3.4 Overall dimension of transmission 13

3.5 Summary of this chapter 13

Chapter 4 design and check of transmission gear 14

4.1 Determination of basic parameters of transmission gear 14

4.1.1 Modulus m 14

4.1.2 pressure angleα 15

4.1.3 Helix angleβ 15

4.1.4 Tooth width b 16

4.2 Distribution of the number of teeth in each gear 16

4.2.1 Determine the number of teeth of the first gear 16

4.2.2 Determine the number of teeth of the second gear 18

4.2.3 determine the number of teeth of the third gear 19

4.2.4 determine the number of teeth of the fourth gear 20

4.2.5 determine the number of teeth of the sixth gear 21

4.2.6 determine the number of teeth of reverse gear 21

4.3 Selection of gear accuracy 23

4.4 Helical direction of gear 23

4.5 Selection of materials 23

4.6 Strength check of gear 23

4.6.1 Damage form of gear 23

4.6.2 Calculate the torque of each shaft 25

4.6.3 Strength calculation method of gear 25

4.6.4 calculation of bending strength of gear 28

4.6.5 contact strength calculation of gear 30

4.7 summary of this chapter 33

Chapter 5 design and calculation of transmission shaft and bearing 34

5.1 primary transmission shaft length and diameter 34

5.2 Structural shape of axis 35

5.3 About RomaxDesigner 36

5.4 The establishment of transmission assembly model in Romax 37

5.5 Define load case and gearbox load spectrum 40

5.6 Romax static analysis of transmission shaft and bearing 41

5.6.1 Force on transmission shaft 41

5.6.2 stress on transmission shaft 43

5.6.3 stiffness on transmission shaft 45

5.6.4 selection and check of transmission bearing 46

5.7 summary of this chapter 48

Chapter 6 design and selection of synchronizer and control mechanism 49

6.1 design and selection of synchronizer 49

6.1.1 lock ring synchronizer 50

6.1.2 lock pin synchronizer 51

6.1.3 determination of main dimensions of lock ring synchronizer 52

6.1.4 determination of main parameters of synchronizer 53

6.2 design and selection of transmission control mechanism 57

6.2.1 classification of transmission control mechanism 57

6.2.2 analysis of common operating mechanism of transmission 58

6.3 summary of this chapter 60

Conclusion 61