摘 要

近年来，我国道路交通基础设施建设发展迅速，加上中国车辆拥有量同比增加，导致道路交通事故频发。因此，清障车已被广泛应用于道路，城市建设，汽车维修行业，机场，码头和高速公路。

本文介绍了国内外清障车的研究背景和研究现状。阐明了液压系统的组成和基本工作原理，分析其工作流程和工作条件，根据给出的数据和掌握的专业知识对侧装式清障车液压系统进行设计，对液压系统中各元件的主要技术参数进行了计算。利用CATIA软件建立侧装式清障车液压系统各零件和总成的三维图和工程图，并利用fluidSIM软件绘制液压系统原理图，并进行了仿真。

本文的亮点是：

1.在竖轨油缸出油口串联调速阀控制油液流速，解决了事故车上升和下降过程中不能保持平衡的问题。

2.为了消除移动过程中油管折叠的隐患，在竖轨后方装一链轨来固定软管。

3.设计完成后，使用FluidSIM软件模拟工作过程，验证设计的正确性。

关键词：清障车； 液压系统； 液压缸；液压泵；FuildSIM

Abstract

In recent years, the construction of road traffic infrastructure in our country develops rapidly, coupled with the year-on-year increase in the number of vehicle ownership in China, which has led to frequent road traffic accidents. As a result, the demand for treatment of illegal vehicles and accident rescues in cities has increased rapidly. The road clearing and rescue industry has gradually been taken seriously by the society and the public. Therefore, wreckers have been widely used in roads, urban construction, automobile repair industry, airports, docks and highway companies.

This paper introduces the research background and present situation of wreckers at home and abroad. This paper highlights the composition and basic working principle of hydraulic system, analyzes its workflow and working conditions, and designs the hydraulic system of side-mounted wrecker according to the given data and professional knowledge. The main parameters of components in hydraulic system are calculated. The 3D and engineering drawings of hydraulic system parts and assemblies of side-mounted wrecker are established by CATIA software, and the schematic diagram of hydraulic system was drawn by FluidSIM software, and the simulation was carried out.

The highlights of this article are:

1. Solved the problem that is the accident vehicle move unsteadily during the lifting and dropping, through the control of the speed control valve connected to the oil outlet of the vertical rail cylinders.

2. Describes the method of fixing the chain rails at the rear of the hose in order to eliminate the hidden dangers of hose folding during movement.

3. After the design is completed, simulate the working process with FluidSIM software to verify the correctness of the design.

Key words: wrecker; hydraulic system; hydraulic cylinders; FuildSIM

CONTENTS

Introduction 1

Chapter 1 Introduction of the wrecker 2

1.1 Wrecker Structure and Application 2

Chapter 2 Introduction to hydraulic transmission 3

2.1 Features of hydraulic transmission 4

2.2 Raw Data and Design Requirements of Hydraulic System 4

Chapter 3 Principle circuits drawing out 5

3.1 Working process action analysis 5

3.2 Principle circuits of hydraulic system 6

3.3 The features of side-mounted wrecker hydraulic system 7

Chapter 4 Determination of main parameters 7

4.1 Primary system working pressure 7

4.2 Calculation and design of hydraulic cylinders 8

4.1.1 Foot cylinder 8

4.1.2 Plug-board clamping cylinder 11

4.1.3 Horizontal moving cylinder 11

4.1.4 The vertical rail cylinder 12

4.2 Calculation of the main parameters of the driving motor 13

4.2.1 Supporting board drive motor 14

Chapter 5 Calculation and selection of components 15

5.1 Selection of the pump 15

5.1.1 Pressure 15

5.1.2 Flow rate 16

5.1.3 Type and specification of the pump 16

5.2 Selection of valves 17

5.2.1 Reversing valve 17

5.2.2 Speed control valve 18

5.2.3 Overflow valve 19

5.3 Calculation and Fixed way of the oil tube 19

5.3.1 The type of the tube 19

5.3.2 The inner diameter of the tube 20

5.3.3 The fixed way of the tube 20

Chapter 6 Simulation of hydraulic system 20

6.1 Introduction of the FluidSIM software 20

6.2 Simulation 21

6.3 Result analysis 21

Chapter 7 Conclusion 25

References 25

Acknowledgements 27

Introduction

In the 1950s, the world's first wrecker was born in the United States. With the improvement of style and function, wreckers have evolved from a single structure and function into a multi-functional, multi-purpose wrecker. In the near future, wreckers will have greater work capacity, more advanced operating methods, and a more comfortable working environment.

The development of wreckers is divided into the following stages: The first stage, in the 20th and 50th centuries in the 20th century, has a single function and a simple structure. At this stage, self-made chassis are often used and pulleys, wire ropes and winches are installed on trucks. The hoisting machine is driven by mechanical transmission, supported by tie rods, and one end of the faulty vehicle is pulled off the site. The second stage was the 1950s to the 1970s. Represented by CHALLENGER, JERR-DAN, and WRECKER companies in the United States, many wrecker companies with advanced technologies emerged in the world. At this stage, the technology of wreckers has been greatly developed. First of all, hydraulic transmission and control technologies were introduced at this stage. Secondly, the series of wreckers have increased in variety and scale. In addition, the structure and chassis are also diversified. The third stage, from the 1980s to the present, is the period of rapid development of wreckers. The main characteristics of wreckers at this stage are various structures and complete functions, such as lifting, dragging, hauling, maintenance and other functions.

Research status at home and abroad: Since the 1980s, China began to import and manufacture wreckers. However, at this time, wreckers in foreign countries have already developed to the third stage. Therefore, China started late and has a low starting point. So far, the domestic road wrecker has developed four series of hundreds of varieties, including tongs separation type, hanger type, flat type, and ordinary type. The tonnage ranges from several hundred kilograms to 60 tons, which can basically meet the needs of rescuing all kinds of vehicles. However, both in terms of technology and production capacity, they can only meet the needs of the domestic market and there is still a big gap from the world's advanced level. The aspects are mainly manifested in: (1) At present, the domestic use of trucks in the second category of chassis to replace wreckers, therefore, the top loading system and chassis matching is not reasonable, the operating capacity of the chassis has not fully played. (2) Product development is still at the stage of imitation, and there are not many independently developed types. Only a few enterprises with large production volumes use plasma or laser technologies to ensure that the size of the blanks is accurate and that the blanks are deformed by heat. (3) Intelligent monitoring. At present, the technology of domestic wreckers only satisfies basic rescue and remedial measures, and intelligent monitoring instruments are less widely used.

Chapter 1 Introduction of the wrecker

Wreckers are special vehicles equipped with road rescue equipment. As the car travels on the road, especially on the expressway, breakdowns and accidents often occur. The function of the wrecker is mainly to eliminate road obstacles, clear the accident vehicles, and arrange the urban environment to provide drivers and vehicles with help and rescue services. Therefore, road wreckers are also called road emergency vehicles. With the increase of high grade roads and in-use vehicles, wreckers have also developed.

1.1 Wrecker Structure and Application

The type of wreckers according to the structure is generally divided into four series: supporting crane separation type, supporting hanging crane type, flat type and ordinary type. The lift-off separation type wrecker includes two types of rotation and non-rotation of the boom. Supporting cranes and lifting cranes are divided into light, medium and heavy types according to their working ability. Flat-type wreckers are light-duty vehicles with only two tonnages, 3 tons and 5 tons.

The feature of the flat-type wrecker is that it can clean up two accident cars at one time and is suitable for handling more than one light accident vehicles. However, it also has many disadvantages: Firstly, there is no hoisting ability. As for the accident vehicles which slide out of the road, it would be supported by other cranes. Secondly, rope is pulling slowly, and it takes longer time to drag the accident car onto the tablet. Thirdly, the support arm of the flatbed car is limited by the structure. When it is flat, it cannot be completely lowered to the ground. It can only be lowered to a negative angle, and lift the accident car by the telescoping of its support arm. In this way, for some faulty vehicles with lower chassis, such as sports cars and some high-grade cars, it is easy to break the bumper and cause secondary damage.