摘 要

东风猛士EQ2050B作为一款设计先进性能优越的越野车，对对转向系统的操纵稳定性和转向轻便性有更高的要求。通过对该车型转向系统的设计研究，可以了解到目前先进的汽车设计理念，另一方面，也可以继续进行优化设计，使整车具有更优越的性能。在设计和研究的过程中，采用了理论结合实际的研究方法。对于理论研究的部分，严格按照理论知识来设计和计算转向系统各个零件的尺寸、选用材料等。除此之外，在一些需要自己选择设计的地方则通过参考同类车型或者进行实验来找到最优的设计结果。同时，在一些需要进行优化设计的步骤中我通过计算机编程来优化设计。

通过这段时间的研究，针对设计所选的车型，我选择了比较合理转向系统的构造。首先，选用了整体式液压动力转向器，机械式转向器则采用了现在应用广泛的循环球式转向器。由于该车采用了独立悬架，于是选择采用断开式转向梯形。

通过学习前人的成果以及指导老师的热心教导和自己的努力探索，最终顺利完成了这次对汽车转向系统的设计，不仅，学习到了很多先进的知识，同时也锻炼了自己的设计水平。

关键词：转向系统，转向器，转向梯形。

Abstract

As a design of advanced performance superior off-road vehicles, the steering system of Dongfeng warrior EQ2050B have a higher demand on the stability of and steering portability. Through the design of the vehicle steering system, I can understand the current advanced automotive design concept, on the other hand, I can continue to optimize the design so that the vehicle has a more superior performance. In the process of design and research, I learn the theory combined with the actual research methods. For the theoretical part of the study, I will obey the theoretical knowledge to design and calculate the size of each part of the steering system and the choice of materials. In addition, in some places where I need to choose my own design, I can find the best design results by referring to the same type of vehicle or experimenting. At the same time, in some of the steps is needed to optimize the design, I will make it through computer programming.

Through this period of research, for the design of selected models, I chose a more reasonable steering system structure. First of all, I closed an overall hydraulic power steering gear. As for mechanical steering gear, I chosen the recycling ball steering gear which is now used widely. The car uses a separate suspension, so I choose to use the open steering trapezoidal.

   By learning the results of their predecessors, the instructor's enthusiastic teaching and my own efforts to explore, I finally completed the design of the car steering system successful. Through this final design, I can not only learn a lot of advanced knowledge, but also improve my own design level.

Keywords: Steering system; Steering gear; Steering trapezoid.

Contents

Chapter 1 Introduction 1

1.1 Overview 1

1.2 Research Status at Home and Abroad 2

1.3 The main content of the design study 3

Chapter 2 Analysis of the Mechanical Steering Gear 4

Chapter 3 The Main Performance Parameters of Steering System 6

3.1 Steering efficiency 6

3.1.1 The positive efficiency of the diverter η 6

3.1.2 the inverse efficiency of the diverter η- 6

3.2 Change characteristics of transmission ratio 7

3.2.1 The transmission ratio of the steering system 7

3.2.2 The transmission gap Δt of the steering gear drive 7

Chapter 4 Design of Mechanical Steering Gear 9

4.1 The determination of the calculated load of the steering system 9

4.2 Design of Recirculating Ball Steering 9

4.2.1Screw, ball and nut drive 13

4.2.2Ball diameter d and quantity n 13

4.2.3 raceway cross section 13

4.2.4 contact angle θ 13

4.2.5 pitch p and helical lead angle α₀ 13

4.2.6 the number of work cycles ω 14

4.2.7 catheter through the d₁ 14

4.3 Rack and pinion drive design 14

4.4 Calculation of Parts Strength of Recirculating Ball Steering 14

4.4.1 the contact between the ball and raceway stress σ 15

4.4.2 the bending stress σ_ω 16

4.4.3 the diameter of the steering arm 16

Chapter 5 Power Steering Mechanism 18

5.1 Requirements for power steering mechanisms 18

5.2 Analysis on the Arrangement of Hydraulic Power Steering Mechanism 18

5.2.1 Power steering mechanism layout 19

5.2.2 The structure of the distribution valve 20

5.3 the calculation of power cylinder size. 20

5.3.1 Calculation of power cylinder dimensions 21

5.3.2 Calculation of wall thickness t of cylinder of power cylinder 22

5.4 Selection of distribution valve parameters 22

5.4.1 Calculation of basic parameters of distribution valve 22

5.4.2 Disposition of the return valve of the valve 24

5.5 Evaluation index of power steering gear 26

5.5.1 the effectiveness of power steering 26

5.5.2 the driving feels the hydraulic power steering 27

5.5.3 steering sensitivity 27

5.5.4 static characteristics of power steering 27

Chapter 6 Electronically Controlled Hydraulic Power Steering Mechanism 29

Chapter 7 Steering Trapezoid 30

7.1 Selection of steering trapezoid 30

7.2 Determination of the break point 30

7.3 Optimization design of steering trapezoidal structure 32

7.4 Calculation of strength of steering gear 42

7.4.1Ball pin 42

7.4.2 Steering tie rod 42

Chapter 8 Steering Shock Absorber 44

Chapter 9 The Original Structure of the Steering Gear 45

Chapter 10 Conclusion 46

Acknowledgement 47

Reference 48

Chapter 1 Introduction

1.1 Overview

Dongfeng warrior off-road vehicle is one kind of light military off-road vehicles, the total mass is 5 tons, the loading quality is 1.75 tons, traction quality is 2 tons, And it is a series, multi-purpose, with a new three generations of high-tech base tactical platform, it is the biggest features for the big power, high ride comfort, mobility, high security and strong adaptability. Dongfeng warrior off-road vehicles are mainly used to improve the ground forces of the field mobile tactical assault capability. It has a lot of good performance characteristics witch determine its baked, with a strong military color.

 The other parameters of Dongfeng warrior EQ2050B are as follows: