摘 要

汽车的制动系统在车辆的安全方面就扮演着至关重要的角色。随着汽车技术的进步和汽车行驶速度的提高，这种重要性表现得越来越明显。因此，如何开发出高性能的制动系统，为安全行驶提供保障是我们要解决的主要问题。

本文借助汽车设计工程手册，对各种汽车制动器的优缺点进行了分析对比，并根据已知条件和实际使用情况，选择盘式制动器和领从蹄式制动器作为该燃料电池公交车的前后制动器，然后根据设计要求对两种制动器进行了计算和校检，使其满足设计和使用要求，从而提高了燃料电池公交车的制动性能。

关键词：燃料电池公交车；制动系统；盘式制动器；鼓式制动器

Abstract

Automobile braking system will play a vital role in the vehicle's safety aspect. With the progress of auto technology and improvement of the car's speed, the importance of this performance become more and more obvious. Therefore, how to develop a high-performance braking system, which guarantees safety is our main problem to solve.

This paper, with the help of automobile engineering design manuals, comparing and analyzing the advantages and disadvantages of all kinds of automobile brakes, and according to the known conditions and practical usage, selecting disc brake and drum brake as front and rear the brake of the fuel cell buses. And then according to the design requirements calculate and check on the two kinds of brake, make it meet the requirements of design and use. So as to improve the braking performance of the fuel cell buses.

Key words: fuel cell buses; the braking system; disc brakes; drum brakes

Catalogues

摘 要 I

Abstract II

1 The introduction 1

1.1 The function of the brakes 1

1.2 The types of brakes 1

1.3 The composition of the brakes 2

1.4 The requirements of brakes 3

1.5 The new development of the brakes 4

2 The structure of brakes and choice 5

2.1 The advantages and disadvantages of brakes 5

2.2 The selection of brakes 9

3 The basic parameters of fuel cell buses 9

4 The selection and the main parameters of fuel cell buses braking system 10

4.1 The synchronous adhesion coefficient 10

4.2 Tire-road friction coefficient 10

4.3 The braking force distribution coefficient and braking force 11

4.4 The torque of emergency brake and parking brake 11

5 The design of disc brakes 12

5.1 The determination of disc brakes' structure parameters 12

5.1.1 The diameter of disc brakes 12

5.1.3 The basic parameters of friction liner 13

5.1.4 The working area of friction liner 13

5.1.5 The friction coefficient friction liner 13

5.2 The design and calculation of friction liner 13

5.3 The calculation of the wear and tear characteristics 14

5.4 The design of brake main parts' structure 15

5.4.1 Braking disc 15

5.4.2 Braking caliper 15

5.4.3 Braking block 16

5.4.4 Friction material 16

5.4.5 The adjustment method of disc brakes clearance 16

5.5 The brakes coefficient 17

6 The design of the drum brakes 17

6.1 The determination of drum brakes' structure parameters 17

6.1.1 Drum Brakes inter diameter 17

6.1.2 The basic parameters of friction liner 18

6.1.3 Starting angle of friction liner 18

6.1.4 The distance from braking center to opening line 18

6.1.5 Brakes shoe point coordinates 19

6.1.6 The friction coefficient friction liner 19

6.2 The calculation of the wear and tear characteristics 19

6.3 The design of brake main parts' structure 20

6.3.1 Braking drum 20

6.3.2 Braking shoe 21

6.3.3 Friction material 21

7 Brake driving mechanism of type selection and calculation 21

7.1 Brake driving mechanism of type selection 21

7.2 The selection of braking pipe 21

7.3 The calculation and design of hydraulic braking drive mechanism 23

7.3.1 Wheel cylinder diameter 23

7.3.2 Braking cylinder diameter and working volume 24

7.3.3 Braking pedal force and pedal stroke 25

8 The finite element analysis 26

8.1 disc brake 26

8.2 drum brakes 27

9 Braking energy recovery 28

9.1 Braking energy recycling research background and control strategy 28

9.2 Cell selection and the design of the battery box 28

10 Conclusion 30

Acknowledgments 31

References 31

1 The introduction

1.1 The function of the brakes

Automobile braking system is a mechanism which used for driving the car to slow down or stop, keep the speed stability when cars traveling downhill and making the car parked stationary on the ground (including on the slope).

Automobile braking system affects the driving safety and parking reliability of cars directly. Braking performance is directly related to traffic safety. Major accidents happening because of the long braking distance and braking skid. With the rapid development of highway, increase of the speed and traffic density, in order to guarantee the driving safety, parking reliability and the working reliability of automobile. It is y important to improve braking system increasingly. Only a good braking performance and working reliability of braking system can achieve its potential dynamic performance.

1.2 The types of brakes

Nowadays all kinds of the cars friction braking system could be divided into drum brakes and disc brakes. The friction pair of rotating components for the drum brakes is the working surface of cylinder; The rotation of the latter element for disc brakes is the working surfaces for end face.

Picture1.1 The classification of the brake

1.3 The composition of the brakes

All kinds of braking system consist of two parts, brakes and braking drive mechanism. Driving brake is controlled with the foot on the brake pedal and work on all the wheels. However parking brake is controlled with the hand lever. Most of the parking brake is used to brake the rear two wheels. Some of the front wheel drive vehicles also equipped with front wheel parking brake. Driving braking system could be divided into two types--hydraulic and pneumatic driving mechanism. A hydraulic driving mechanism needs the brake master cylinder, brake wheel cylinder and line to transform controlling force. A pneumatic driving mechanism needs the air compressor, pneumatic pipes, storage tanks, control valve and brake chamber to transform controlling force.

Picture1.2 The composition of the brakes