Wuhan University of Technology

Graduation Design (Thesis)

Structural Design of Brake Arm Assembly for Light Passenger Cars

School：School of International Education

Specialty：Automotive Engineering gj1501

Name：Cheng Qiliu

Tutor：Deng Xiaohe

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ABSTRACT

With the development of society, automobile has become an indispensable part of our daily life as a means of transportation. People have higher and higher requirements for the safety, stability, power, economy and comfort of automobile. It is difficult to further improve or improve the performance of automobiles by using traditional mechanical methods. The function of parking brake system is to provide resistance to the vehicle when parking, when there is or has external force on the ramp, so that the vehicle does not slide or move. The parking brake system usually makes the vehicle stay in place by locking the transmission shaft or rear wheel.

The parking brake device is a device that prevents the vehicle from sliding when parking on the road surface (including the slope), and when the vehicle starts on the slope, it is used to prevent the vehicle from retreating. Parking brake devices are different from driving brake devices. They each have independent control devices.

This project is called the structural design of the brake arm assembly of light passenger car. The purpose of the project is to design the brake arm assembly structure by studying the parking brake device widely used in light passenger car. The three-dimensional modeling and motion simulation of the brake arm are carried out by using CATIA software, and the brake arm in the longitudinal tension, compression and lateral direction is also studied. Finite element analysis is carried out under working conditions.

Key Words：Automobile Safety；Handbrake Arm；CATIA；Finite Element Analysis

Contents

Chapter 1 Introduction 1

1.1 The Purpose and Significance of the Topic 1

1.2 Research Status at Home and Abroad 2

1.3 The basic content, objectives, technical solutions and measures to be adopted 5

1.3.1Basic Contents of Research 5

Chapter 2 Structural Design of Hand Brake Arm Assembly 6

2.1 Hand Brake Arm Assembly 6

2.2 Hand Brake Arm Main Parts Function 6

2.3 Working Principle of Hand Brake Arm 7

2.4 Design Requirements of Hand Brake Arm Assembly 8

2.5 Determination of Relevant Parameters 10

2.6 Design of Parking Handle 11

2.6.1 Rally check 11

2.6.2 Parking Handle Stroke 12

2.7 Ratchet Mechanism Design 12

2.8 Brake System Calculation 14

2.8.1 Normal Reaction of Front and Rear Wheels During Braking 14

2.8.2 Relevant Calculation of Brake 15

2.8.3 Braking Deceleration and Distance 16

2.9 Parking Braking Check 17

Chapter 3 3D Modeling of Hand Brake Arms 19

3.1 Computing Platform Selection 19

3.2 Introduction of Function Modules 20

3.3 Three-dimensional Model of Brake Arm Assembly 21

3.4 DMU motion mechanism simulation 22

Chapter 4 Finite Element Analysis of Hand Brake Arm 23

4.1 Hand Brake Arm Model Simplification 23

4.2 Hand Brake Arm Calculation Conditions 25

4.3 Stretching Condition 1 28

4.3.1 Application of Load and Restraint of Tensile Condition I 28

4.3.2 Analysis of Results 29

4.4 Stretching Condition II 30

4.4.1 Application of Load and Restraint in Tension Condition II 30

4.4.2 Analysis of Results 31

4.5 High Working Conditions 32

4.5.1 Application of Load and Restraint in High Working Conditions 32

4.5.2 Analysis of Results 33

4.6 Low Working Conditions 34

4.6.1 Application of Load and Restraint in Low Working Conditions 34

4.6.2 Analysis of Results 35

4.7 Teeth Plate External Force Compression Condition 36

4.7.1 Application of Load and Restraint 36

4.7.2 Analysis of Results 37

4.8 operating Lever Deformation Conditions 38

4.8.1 Application of Load and Restraint 38

4.8.2 Analysis of Results 39

4.9 Lateral Working Conditions 40

4.9.1 Application of Lateral Load and Restraint 40

4.9.2 Analysis of Results 43

Conclusion 46

References 47

Acknowledgement 48

Chapter 1 Introduction

The Purpose and Significance of the Topic

The 21st century is an era of rapid development of the automobile industry, and the automobile industry has gradually become a pillar industry in many countries. With the rapid development of the national economy, the annual production and social ownership of automobiles are also growing rapidly. The merits of each car's performance are related to whether the Chinese auto industry can move toward the world. Therefore, improvements to automobiles and related products are also very important.

Since the birth of the car, the vehicle brake system has played a vital role in the safety of the vehicle. In recent years, with the advancement of vehicle technology and the speed of automobiles, this importance has become more and more obvious. In order to cope with the high-speed threat of people's safety, many regulations put forward higher requirements for the safety of automobiles, and the reliability of automobile brake systems has become one of the most important aspects. The braking performance of the car is also used as a performance indicator for the seven vehicles, which is to ensure the safety of the car. The automotive brake system consists of many components, and the vehicle's brake arm is an essential component. The function of the brake system is to force the car to slow down or stop to keep the speed of the downhill car stable and keep the parked car in place (including on the slope) ^[1]. The hand brake arm is the core component of the parking brake system, ensuring the stability of the vehicle brakes, and it is also the last guarantee of life when people drive. Studying the structure of the hand brake arm assembly not only affects the high efficiency of the automotive brake system, but also affects its long life operation. It is also directly related to the safety of the car. Continuous improvement and improvement of the brake arm of the car is an important task in the design process of the car.

The hand brake is an auxiliary brake system for the vehicle brake system. Its professional name is the auxiliary brake, which is mainly used to prevent the vehicle from slipping when the vehicle is parked. Most car handbrakes are connected to the rear brake shoe by a pull wire to brake the car. The car hand brake is an auxiliary brake system for the vehicle brake system. Unlike the brake principle, it is connected to the rear brake shoe by the pull wire and pulls the rear brake pad to act as a brake. Its main function is to make the car reliably stay in the parking position, or to start the ramp and use the foot brake to brake in an emergency ^[2]. Ordinary handbrakes are usually placed in the driver's right hand drooping position for ease of use, but there are also separate models that mount the brake pedal on the side of the brake pedal. Under normal conditions, when the hand is pulled to 70% of the entire stroke, the hand brake arm should be in the normal braking position. Before detecting the braking force of the hand brake arm, you need to find this first, which can be determined by the number of teeth of the ratchet. 70% of this position is the effective working point of the handle, the principle is to control the braking of the rear wheel without controlling the front wheel.

1.2 Research Status at Home and Abroad

As the safety of automobiles has become more and more concerned, the requirements for the braking performance of automobiles are increasing. For this purpose, the TRW Automotive Group successfully developed and introduced the automotive electronic parking brake system for the first time. Its electronic control system works in conjunction with other components to make the car more intelligent. Compared with the traditional mechanical parking brake system, the driver's physical strength and operation troubles are more consumed. When driving on a slope, the driver needs certain skills, and the mechanical structure has potential safety risks in many uses. The electronic parking brake system can effectively overcome this series of problems. It can realize slow braking, start ramp intelligent support, and realize data exchange and sharing during driving, but the mechanical parking brake system cannot achieve this function. . Compared with the main parts of automobiles such as automobile chassis, clutch and engine, the current domestic electronic parking technology has few achievements and is basically in the experimental state. For example, Xin Gaifang and Li Wei conducted in-depth research on the application layer protocol of the electronic parking system and improved the hardware design of the communication interface circuit. After learning and learning, the switch control of the electronic parking system was deeply studied. After the simulation and experimental data analysis, the drawbacks of the switch-controlled electronic parking system were obtained. Yuan Yong, Cai Jing and others designed a test bench for the electronic parking system. The base was used to simulate the control strategy of the electronic parking control system, and a simulation method based on the experimental platform was established. However, the conventional mechanical control arm is inexpensive and easy to install, which is the main reason for the widespread use of the device, and it is meaningful to improve the conventional parking brake handle. Some scholars have contributed to the lightweight and structural optimization of the device. For example, in 2008, Li Yuan etc completed the three-dimensional model of the parking brake handle while considering the non linearity of the state and the non linearity of the material. The residual stress and failure of the overall structure under various lateral and lateral forces are analyzed. In 2010, Han Ji designed the mechanical structure in the test system for the problems in the assembly experiment system of the parking brake operating mechanism. There are an electric control unit, a load control unit, and a stress detection unit. The optimal design of the parking brake lever was designed by Chery Automobile, Beiqi and other automobile companies, and applied for related patents.

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