1. 研究目的与意义（文献综述）

选题名称： 汽车盘式制动器设计

选题学生： 张定枫【学号：0121328250204】

The design of Automobile Disc Brake

1．目的及意义（含国内外的研究现状分析）

1.1 Background

Automobiles are playing a more and more important role in people’s daily life, and the braking system is one of the most important part which keeps car driving safely. The function of the braking system is to bring the moving motor vehicle to rest or slow down in a shortest possible time.

There are four parts of a braking system: Serving braking system, Parking braking system, Additional retarding braking system and Emergency braking system. Any braking system consists of an energy-supplying device, a control device, a transmission device and a brake. And a brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. There are two types of the brakes, disc brakes and drum brakes. A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum. The brake drum means a brake in which shoes press on the inner surface of the drum. The disc brake uses calipers to squeeze pair of pads against a disc in order to create friction that retards the rotation of a shaft, such as a vehicle axle, either or reduce its rotational speed or hold it stationary.

Nowadays, the disc brake is becoming more and more popular in automobiles, especially in some advanced cars. With the help of the hydraulic system, the disc brake can provide greater brake force and work more stable and shows a good braking performance on different road conditions. The disc brake has a higher braking efficiency that drum brake. Besides, the air passes through the disc bake directly so the disc brake have a good ability of dissipating heat. However, the disc brake has a much more complicated structure, the requests of brake caliper and brake hose are higher, so it is common that the disc brake cost more that drum brake. Since 1976, all cars have used disc brakes on the front wheels. Most cars use drum brakes on the rear wheels. In both drum and disc brakes, a hydraulic system applies the brakes. The hydraulic system connects the brake pedal to the brake parts at each wheel. While the driver is braking, the pressure of the master cylinder is transmitted to the disc brake, which pushes the brake lining contacted by the brake disc, prevent the disc from turning.

According to the types of fixing elements in the friction pairs, the disc brake can be divided into two: one is Compete Disc brake, another is spot-type disc brake. The spot-type disc brake is consists of rotating element（brake disc) and the fixed element( brake caliper); the compete disc brake is also consists of rotating element (brake disc) and fixed elements are a rounded metal backboard and friction plate, in operation, the brake disc is in full contact with the friction plate.