摘 要

汽车制动系是用以强制行驶中的汽车减速或停车、使下坡行驶的汽车车速保持稳定以及使已停驶的汽车在原地(包括在斜坡上)驻留不动的机构。随着高速公路的迅速发展和车速的提高以及车流密度的日益增大，为了保证行车安全，汽车制动系的工作可靠性显得日益重要。也只有制动性能良好、制动系工作可靠的汽车，才能充分发挥其动力性能。本文通过某载货汽车制动系统的设计，系统详细的将油压整车制动系统进行了阐述。制动系统匹配设计主要是根据设计任务书的要求，整车配置、布置及参数，参考同类车型参数，选择制动器型式、结构及参数，然后校核计算，验证所选参数是否满足设计任务书及法规要求，满足要求后初步确定参数。由于本文参考样车为油压制动车型，操纵系统为液压操纵、真空助力。

关键词：制动系统，制动力分配，同步附着系数，制动器

Abstract

The automobile brake system is a mechanism for forcibly decelerating or stopping a vehicle while driving, maintaining a stable vehicle speed on a downhill road, and mobilizing a parked vehicle in place (including on a slope). With the rapid development of the expressway and the increase of the vehicle speed and the increasing traffic density, the operational reliability of the automobile brake system becomes increasingly important in order to ensure the safety of the vehicle. Only cars with good braking performance and reliable braking system can fully exert their power performance. This article through the design of a truck brake system, the system detailed description of the hydraulic vehicle brake system. The matching design of the braking system is mainly based on the requirements of the design task book, vehicle configuration, layout and parameters. With reference to similar vehicle model parameters, the brake type, structure and parameters are selected, and then the calibration calculation is performed to verify whether the selected parameters meet the design mission statement and Regulatory requirements preliminarily determine the parameters after meeting the requirements. Because this article refers to the sample vehicle is a hydraulic brake model, the control system is hydraulically operated and vacuum assisted.

Key words：Braking system, braking force distribution, synchronous adhesion coefficient, brake

table of Contents

1.Introduction........................................................................................1

• 1. Purpose and significance......................................................1
  2. Analysis of Research Status at Home and Abroad................1
  3. Design content, goals, programs and measures...................2

1.3.1The basic content of the design.....................................2

1.3.2 Design goals...................................................................2

1.3.3Proposed technical solutions and measures..................2

1.3.4The brake system requirements.....................................3

2.Braking system main parameter selection..........................................7

2.1Initial selection of system main parameters...........................7

2.1.1The ideal braking force distribution curve is drawn.......7

2.1.2 Selection of Synchronous Adhesion Coefficient and Braking Force Distribution Coefficient.........................................................................10

2.2 Calculation and Selection of Main Parameters of Brake.........11

2.2.1 Front and rear axle braking force determination.........12

2.2.2 Determination of brake type........................................12

2.2.3 Determination of the braking radius............................12

2.2.4 Calculation and Selection of Brake Efficiency Factor....13

2.2.5Wheel cylinder diameter determination.......................14

2.2.6Brake drum inner diameter D........................................14

2.2.7Brake drum inner diameter D.........................................15

2.2.8Friction liner start angle..................................................15

2.2.9Distance from the center of the brake to the line of action of the opening force P........................................................................................16

2.2.10Brake shoe position coordinates k and c.......................16

2.3Determination of brake operating system parameters...............16

2.3.1 Initial calculation of system working pressure................16

2.3.2Master cylinder diameter, vacuum booster boost ratio, pedal lever ratio..........................................................................................................16

2.3.3 Vacuum booster diameter determination.......................17

3.Driving brake operating system calibration calculation.........................19

3.1 Pedal force calculation check......................................................19

3.2 Calculation of braking distance...................................................19

4.Full text summary...................................................................................21

5.References..............................................................................................22

1 Introduction

1.1 Purpose and Significance

In recent years, China's economy has developed rapidly, and as the people become more affluent, the car gradually moves into each household. Nowadays, automobiles have become an indispensable part of people's lives. In addition to being a convenient means of transport, trucks for goods are also found everywhere. There is no doubt that these trucks have made tremendous contributions to the country’s economic development and social progress. According to statistics, in the year 2006, the volume of road freight was 14.66 billion tons. In 2015, the volume of road freight was 31.5 billion tons. According to these two data with double the gap, it can be seen that the truck transportation holds the lifeblood of the national economy. Moreover, trucks have the advantages of high transport capacity and long transportation distance. Therefore, even in the future, truck transportation is one of the main modes of transportation. At the same time, however, some traffic accidents have also occurred frequently, and it has become increasingly prominent as a social problem that is urgently needed to be resolved.

According to incomplete investigations, according to incomplete statistics, traffic accidents have killed more than 32 million people worldwide since they were recorded. In 2000, due to traffic accidents, 5 million people were hospitalized and 30 million were injured. In a traffic accident caused by a problem with the vehicle itself, the accident rate caused by the failure of the brake system is 45%. Therefore, in order to ensure the safety of the car and the ability to exercise at high speed, the braking system must have a short braking distance, a large braking deceleration, a short braking time, and so on. Needless to say, a braking system with good braking performance plays a crucial role in the braking process of the car.

1.2 Analysis of Research Status at Home and Abroad