Graduation Design (Thesis) of Wuhan University of Technology

Design of Steering System for Small Electric Scooter

School: International education school

Specialty amp; Class: Automotive engineering gj1303

Student name: Li Qidi

Tutor: Guo Wei

Statement of Originality

I solemnly declare that the thesis I submit is a piece of writing I completed independently based on my own research under the guidance of my supervisor. Except for the quotations, this paper does not include any writings published or completed by other individuals or groups. I am fully aware that the legal consequences of this statement are borne by me.

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I solemnly declare that the thesis I submit is a piece of writing I completed independently based on my own research under the guidance of my supervisor. Except for the quotations, this paper does not include any writings published or completed by other individuals or groups. I am fully aware that the legal consequences of this statement are borne by me.

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Abstract

Steering system is a vital system in vehicle. It will directly affect car's handling stability and driver's driving experience. As a new steering system, compare to the traditional steering system, it has the advantages of environmental protection, energy saving and safety. In addition, it can perfectly solve the contradiction between light and sensitive, so it will be a mainstream in the short future.

Firstly, this essay introduce the development history of vehicle steering system and discuss the drawback of traditional steering system as well as the advantages of electric power steering system(EPS). Moreover, it analyses the research status of both domestic and foreign. Then, this essay introduces the composition, working theory and types of EPS.

Secondly, through the optimization design of the calculation software MATLAB, a more suitable steering trapezoidal structure conforming to the model is solved, and the specific parameters of the gear are deduced based on the rack travel in the steering trapezoid. After processing the parameter of the gear, the gear and gear shaft are both been check for strength. Thus, the two main parts of the steering system are determined. Subsequently, the electric motor and the electric power characteristics motor were selected according to the vehicle.

After deriving the specific parameters of the steering gear and the trapezoidal, the steering system is modeled based on the 3D modeling software Solid works. Secondly, some key components such as gear shafts and racks in the steering system are made. Static Analysis and Modal Analysis are done through ANSYS Workbench.

Keyword: steering system; steering trapezoidal; steering gear; ANSYS Workbench

Content

Chapter 1 Introduction 1

Foreword 1

1.2 Research status of electric steering system at home and abroad 2

1.2.1 Research status abroad 2

1.2.2 Current status of domestic research 2

1.3 The main purpose and significance of the thesis 3

1.3.1 purpose and significance 3

1.3.2 The content of this paper 4

Chapter 2 Introduction of EPS 5

2.1 The composition and working principle of EPS 5

2.2 Requirements for EPS 6

2.3 Types and advantages of EPS 6

2.5 Choose a suitable EPS 7

2.6 Summary of this chapter 7

Chapter 3 Calculation of Steering System 8

3.1 Vehicle parameter 8

3.2 Calculation of main performance parameters of steering system 8

3.2.1 Positive and inverse efficiency of steering gear 8

3.2.2 Steering transmission ratio 9

3.2.3 Transmission gap of steering gear 9

3.3 The determination of steering calculation load 9

3.4 Calculation of steering trapezoid 10

3.4.1 Design method of Steering trapezoid 10

3.4.2 Introduction of using MATLAB to solve nonlinear constraint problem 11

3.4.3 Optimization calculation of steering trapezoid based on MATLAB 12

3.5 Calculation of steering gear 16

3.5.1 Calculation of steering gear 16

3.5.2 Calculation of spline of steering gear shaft 18

3.5.3 Calculation of steering gear shaft 19

3.5.3 Calculation of steering rack 25

3.6 Selection of assist motor and calculation of reduction mechanism 26

3.6.1 Requirement of assist motor 26

3.6.2 Types of motor 26

3.6.3 Calculation of parameters of motor and reduction mechanism 27

3.7 Selection of motor assist characteristics 28

3.8 Summary of this chapter 31

Chapter 4 Establishment of Steering System 32

4.1 Introduction of Solid Works 32

4.2 Establishment of part model 33

4.2.1 The establishment of steering gear shaft model 33

4.2.3 Establishment of steering rack 34

4.2.3 Establishment of steering house 35

4.2.4 Establishment of steering tie rod 36

4.2.5 Establishment of other parts 36

4.2.6 Steering system assembly 38