摘 要

本文主要讨论一种轻型载货汽车纯电动汽车转向系统的设计方法。通过查阅现有数据和分析，认为采用电动助力转向系统是纯电动汽车最合适的选择。因此，本文从转向系统的总体设计思想开始，从转向器的组成部分出发，分析了目前主流的转向器，评价了其优缺点，最后选择了齿轮齿条式转向器。不仅要从生产成本上考虑，还要从整车的结构空间和性能参数上考虑。电动助力部分，首先选择整个系统所需的传感器、电机等附属机构，然后确定该机构的助力曲线。减速增扭装置部分采用了蜗轮蜗杆传动机构，由于该机构体积比较小，对于这种小型货车来说，助力已经达到了标准。在对整个系统的主要组成部分进行了设计之后，对整个系统进行了仿真分析。本文主要采用将装配体导入SolidWorks的方法，并利用SolidWorks的动画功能对装配体进行运动分析。

关键词：轻卡；纯电动汽车；电动助力转向系统；齿轮齿条转向器

Abstract

In this paper, we mainly talk about a kind of method to design the steering system of a light truck pure electric vehicle. Through consulting the existing data and analysis, it is the most appropriate choice for pure electric vehicles to adopt the electric power steering system. Therefore, this paper has chosen the general design idea of the steering system from the beginning, and then from the part of the steering gear, analyzes the current mainstream steering gear, evaluates its advantages and disadvantages, and finally selects the steering gear type as rack and pinion steering gear. Not only from the consideration of production cost, but also from the structural space and performance parameters of the whole vehicle. For the electric power part, firstly select some sensors, motors and other accessories needed by the whole system, and then improve the determination of the power curve. Then, the part of electric power reduction and torque increase adopts the worm and worm power mechanism, because the mechanism occupies a small volume, for this kind of minivan, the power size has met the standard. After the main components and parts of the whole system are designed, the simulation analysis of the whole system is just carried out. This paper mainly uses the way of importing the assembly into SolidWorks, and uses animation to analyze the motion.

Key Words：Light truck; pure electric vehicle; electric power steering system; rack and pinion steering gear

Contents

Chapter 1 Introduction1

1.1 Overview of automobile steering system1

1.1.1 Introduction to steering system1

1.1.2 Steering system design requirements1

1.2 The classification of automobile steering system and its advantages and disadvantages2

1.2.1 Development of steering system2

1.2.2 Introduction to common steering gear4

1.3 overview of electric power steering system5

1.3.1 working principle of electric power steering system5

1.3.2 Classification and characteristics of electric power steering system6

1.3.3 Advantages of electric power steering system7

1.4 Research on electric power steering system at home and abroad8

1.4.1 A survey of Foreign Studies8

1.4.2 Overview of domestic research9

1.5 Project design overview9

1.5.1 Main contents of the project design9

1.5.2 Significance of project design9

Chapter 2 Design of steering system assembly11

2.1 Design model introduction11

2.2 Load calculation11

2.3 Steering trapezoid design12

Chapter 3 Design and calculation of steering gear13

3.1 Selection of steering gear13

3.2 Design of rack and pinion steering gear13

3.2.1 Selection of main parameters13

3.2.2 Line angle transmission ratio14

3.2.3 Rack and pinion parameters17

3.2.4 Efficiency calculation of steering gear18

3.2.5 Other relevant calculation of steering gear20

3.3 Check of gear rack22

3.4 Design and check of spring28

3.5 Check of bearing30

3.6 Spline check31

3.7 Main 3D models32

Chapter 4 Steering control mechanism and EPS design 34

4.1 Steering control mechanism of automobile34

4.2 Electric power system35

4.2.1 Introduction to EPS35

4.2.2 Main parts of EPS37

4.2.3 Design requirements of EPS39

4.2.4 Selection and control analysis of EPS parts39

4.3 Design and calculation of worm and worm reduction mechanism42

4.4 Selection and check of bearings48

4.5 Simulation analysis of steering system50

Chapter 5 Conclusion51

Reference52

Thanks54

Appendix A55

Chapter 1 Introduction

1.1 Overview of automobile steering system

1.1.1 Introduction to steering system

With the development of China's transportation industry, the use of automobiles is extremly increasing year by year. As one of the major important automobile systems, steering system is the main mechanism to control the driving route and direction of automobiles, which is very significant for the driving safety of automobiles. A good steering system can make the driver obtain a better physical and mental experience while driving the car, so the research on steering system to some extent has become a hotspot of modern technology innovation and social development.

1.1.2 Design requirements of steering system

The following contents are the design requirements for different situations of the steering system ^[1]:

(1) When the driver turns the corner of the car, all the wheels of the car will rotate accordingly with the rotation of the driver's steering wheel. At the same time, the lateral sliding of any wheel is not allowed. And the car should have a momentary steering center to provide a steering center point. Otherwise, the wheel of the car will be damaged seriously, which will bring a series of impacts and may endanger the safety of the driver.

(2) When the driver usually drives the car, there should be no external force applied to the steering wheel, the wheel may also impact the outside world due to various conditions. At this time, it should be required that the wheel can automatically "walk in a straight line".

(3) No matter how the driver operates, and no matter how bad the driving conditions are, the steering wheel can not produce any degree of self vibration. Correspondingly, the steering wheel of the car should not swing at will under any circumstances, which has a great adverse effect on the driver.