A braking system

英文翻译

A braking system

Car brake is one of the main performance cars. Since the date of birth cars, car brake is crucial, and with the development of automobile industry and automobile driving speed increase, its importance is becoming more and more obvious. Brake directly related to the traffic safety, serious accidents often and braking distance is too long, emergency braking. An etc. Therefore, automobile brake is an important guarantee of the car. Let's try to understand the brake system of knowledge.

1)Automobile brake and the evaluation index of so-called automobile brake means when driving in short distances parking and maintain stability and driving directions when the next long slope can maintain certain ability, and speed in long slope in car parking brake the motionless. The automobile braking performance consists mainly of brake performance and brake the constant qualitative and braking car from three aspects of the directional stability evaluation.

1 and brake performance:

Namely braking distance and brake speed, refers to the road, with good car parking brake to certain velocity of braking distance or braking speed is reduced, the automobile braking performance evaluation indexes of the most basic. With the automobile braking distance driving safety directly, it refers to the car with the driver stepped at, from start to automobile brake that stops across the distance. Braking distance and the brake pedal force and tire-road friction condition. Brake speed reflects the ground force, so it and brake force (wheel rolling) and adhesion (wheel lock drag slippery). Because all sorts of automobile braking performance of different requirements, the efficiency is different: general cars, vans, so the high speed high efficiency and its braking, And heavy-duty truck relatively low speed, the requirements of brake performance is slightly lower.

2, brake performance of qualitative:

Braking process is actually the vehicle of kinetic energy into heat energy absorbed through the brakes on hard work, automobile braking conditions (for example, long time continuous slope braking) or high-speed braking temperature, often in 300 ° C, sometimes even reach 600-700 ° C, the brake friction torque, after the temperature rises considerably, this phenomenon is called the hot recession. So the brakes, keeping the temperature rise in the braking performance when the cold

has become the brakes should consider when designing an important problem. Cars in high-speed or under braking performance for braking slope, called thermal keep decline. According to the draft international standards, requirements DIS6597 ISO/with certain speed continuous braking 15 times, each time the braking strength for 3m/s2, finally the braking performance should not under the provisions of cold test braking capacity (5.8 m/s2) 60% (in the brake pedal force under the same conditions). Brake performance and brake material thermal recession and brake structure. In addition, the car driving on the water, brake still exist problems of water recession. When the car wading, water into the brakes, inside short time braking performance of reducing called water recession. The car should rapidly in a short time restore original braking performance.

3 and when the direction of automobile braking stability:

That car doesn't happen when broken running deviation, and the ability to turn the losing side. Braking process, can appear sometimes braking deviation, front or rear axle sideslip lost to ability to lose control of the car from traveling direction, or even other vehicles into orbit, ditch, slid down the slope of a dangerous situation. The automobile braking process in general in line or predetermined corners of the automobile braking ability called direction stability. Braking stability of the vehicle in the direction of qualified experiments is not allowed to produce the effect of control it from a certain width test channel. The automatic braking to the left or right drive called "braking deviation". When the deviation caused by automobile brake for two reasons: one is left, right, especially in the front wheels left and right wheel steering wheel brake force (not equal, Second is the braking suspension orientation of tension in the steering system and the coordination of kinematics (with each other) interference. The first reason is caused, adjust error, whether left or right car running deviation, according to the specific circumstances, The second reason is the design, braking car always left (right) party or to run.

Lateral spreads refer to an automobile braking shaft or two-axis horizontal movement occurs. One of the most dangerous situation occurs in told braking, automobile rear axle sideslip often happens turning sharply irregular movement and lose control, serious when even can make the car array. Front wheel steering refers to lose car corners, automobile braking original curve road but not according to the corner, and the line tangent direction amid the steering wheel drive car brake straight along the direction of still presses. Lateral spreads and deviation are linked,

serious deviation cause, and prone to rear axle sideslip of sideslip car has intensified deviation trend. Ability to lose touch with rear-axle sideslip also have the car if not, rear axle, front side could lose steering capability, Front side, still have to front often. By experiment and theoretical analysis to draw a conclusion that, if a braking on-axis wheel shaft first lock wheels than dragging slippery, may appear below slides, If you can make the former, rear axle and front wheel at first lock wheels, rear axle wheel lock or no death, can prevent the front side. But if the front wheel lock, the car will lose steering capability. Braking deviation, lateral spreads and front lose to ability is an important cause of traffic accidents. Some countries in traffic accident statistics show that occur in the traffic accident casualties in wet road, about 1/3 and lateral spreads, In the snow on the road is about 70-80% and slides. According to the analysis of sideslip accident, found a 50% is by the brake. Therefore, from the direction of auto brake guarantee stability Angle, first cannot appear only rear-axle wheel lock or front wheel lock wheels than front of first, in order to prevent the risk of sideslip on-axis? Crow secondly, as less as possible appear only front wheel lock wheels, or have died in front, in order to maintain the automobile steering. Ideally, prevent any wheel lock, before and after the wheels are rolling condition, which can ensure the direction of braking stability. Therefore, all made some standard of automobile brake of brake request.

2) The basic structure of automobile braking system may have some braking system, equal to brake was here brake is an integral part of the brake system. The braking system by the following several parts roughly: 1, the brakes:

Brakes have two types: disc brakes and drum brake. Mentioned above, the vehicle braking process is absorbed by the kinetic energy into heat energy, brake and high temperature can make brake heat recession, therefore, the phenomenon of brake cooling ability is very important. Drum brake is the earliest automobile brake, when the disc-brake haven't appeared before, it has been widely used in all kinds of cars. But due to structural problems make it in the process of brake cooling performance is poor and drainage performance, easy to cause the poor efficiency of brake down, so in nearly three years, in the field has been gradually withdraw car seat to disc brakes. But due to the low cost, still in some economic class used in cars, mainly used in the rear brake load is small and the parking brake. Typical drum brakes, mainly by the floor, brake drum brake shoes, and cylinder (braking points), return spring, pump parts. Positioning etc. In the floor installation fixed axle position,

it is fixed, and it equipped with brake shoe, wheel cylinder, spring, pins, return the rotating torque under braking. Each drum brake shoes, a pairs of brake shoes are facing friction. The brake drum is installed on the wheel hub, with wheels spinning parts, it is from a certain quantity of cast iron, shape like round drum. When braking, wheel cylinder pistons promote brake shoes, brake drum brake drum oppression by friction deceleration, forcing wheels stop turning. Disc brakes and called the disk brake, just as its name implies is to take its shape. It consists of the hydraulic control, main components have brake disc, pump, tubing, etc. Brake disc with alloy steel and the wheel and wheel rotation, Fixed in the brakes: fixed on the floor, the two frictions on the brake caliper disc brake chips are installed in the side. The piston pump by pipeline portion of hydraulic transmission, promote friction slices to brakes disc friction brakes, action is like living with forceps clamp, forcing the plate as it stop (figure 4). This kind of brake cooling fast, light weight, simple structure, convenient adjustment. Especially when high load, high temperature resistant, good performance, and braking stability, mud in winter and bad conditions, the disc brake driving drum brake easier than in a relatively short period of time to stop the car. Some of the brake disc brake on a lot of little holes, ventilation and cooling efficiency improving brake. Of course disc brakes also has its defects. As for brake and brake pipe manufacturing the demand is higher, the loss is bigger, cost is expensive, and because the area is small, the face also relatively smaller, frictional braking, the need of hydraulic booster device must be to use the vehicle, so only applicable to small.

2 and braking main cylinder:

Braking main cylinder installed in the engine room on clapboard, is a pilot through the operation pedal pump. When the pedal main cylinder was forced by the brake fluid pressure hydraulic pipe to each of the four wheels brakes. The cylinder is driver stepped on the pressure on the brake pedal to the four wheels car parking brake to make. Force is mechanical force into hydraulic pressure on into the mechanical strength. The main cylinder using liquid incompressible principle and hydraulic principle. 3, booster:

At the beginning of the cars in the quality of vehicles, smaller, relatively low speed, the most primitive braking control is a set of simple driver mechanical device to brake pressure, mechanical braking force already can satisfy the needs of vehicle braking, But with the increase of the quality of mechanical device, booster for brake already becomes necessary. Booster is installed in the cylinder brake pedal and, in

order to reduce between the drivers for braking force of the device. Have two kinds of forms, one kind is to use the vacuum tube inlet role in the diaphragm vacuum booster, Another kind is to use the force pump produced with the main cylinder linked to control the hydraulic booster.

4, hydraulic pipeline and valve: hydraulic pipeline steel and hose, by the main cylinder and used in each wheel brake pressure is transmitted between the brake fluid. Most cars with steel pipe, besides brake hose must use. Chassis and between front and rear chassis and between the hose should be flexible, in the braking system of hydraulic pipeline is within the antirust coatings are double-wall steel welding. Double-wall pipes is composed by the two pillars, the one in another. Steel welding seam is. Braking system including measurement valve, valve and load sensor proportional valve, etc. Among them, make bank type -measuring valve is the brake disc brake, just before the start of the hydraulic control, is closed, located in the pipeline to brake. On the brake board, fluid flow to the first, and when the liquid pressure after the brake disc opens measurement, enough to make the fluid pressure before disc brakes. Load sensor proportional valve is an important head pan bank type car parts, in bank type brake hydraulic pipe to. Its function is to maintain the pressure piping and brake between normal proportion the vehicle braking system provides balance. When the wheel needs high pressure, proportional valve can reduce the pressure type brake, powerful braking can prevent the rear wheel lock. The valve is put together several valves.

2 the Peugeot 307 Braking system

Peugeot 307 brake system includes general braking system its unique is added to the larger super cars Peugeot braking auxiliary system. New Peugeot 307 larger super cars are adopted in today's most widespread in the automobile industry of ABS (anti-lock brake installation system) and power distribution system many EBD (.) besides, Peugeot 307 is installed the Peugeot larger super cars unique EVA (emergency brake auxiliary devices).

1) ABS (anti-lock braking system),

1, ABS

With the rapid development of auto industry, the safety car becomes the important basis and people. Now wide spread adoption of ABS enabling people to fully meet the safety requirements. "The ABS" (has) Locked Braking System .It is a slippery, antilock advantage of automotive safety control systems. ABS braking device

is based on the conventional technology, can be improved mechanical and electronic two kinds. Modern car on the installation of ABS, ABS both common braking system, and can prevent the wheels of the car in the braking properly, can still turn, guarantee the stability of car brake direction, prevent to produce sideslip and running, is now the most advanced automobile braking, the best brake. If no ABS, emergency brake usually cause tire lock, at this moment, the rolling friction is become sliding friction force. And if the front wheel lock, the vehicle steering was lost, If the rear first lock, the vehicles, vehicle to produce side direction become unable to control. ABS system through the electronic control machines with a very fast speed, precision control of the brake fluid pressure release, to achieve prevent wheel lock, the largest tire and braking power system in the process of steering capability, make the vehicle in the emergency braking also has the ability to avoiding obstacles.资料来源：360毕业设计网代写论文https://www.360docs.net/doc/c31579197.html, 2, the basic composition of ABS

ABS are usually by the wheel speed sensor, brake pressure regulator, electronic control unit and ABS composed of different colors, ABS system, adjust the structure of pressure braking device type and working principle of the electronic control unit often have different, the internal structure and control logic may differ.

(1) Speed Sensor Wheels

In order to detect the wheel speed, in each wheel around are installing a wheel speed sensor. This decorates a method called sensor arrangement. In the front wheel drive car, can use 3 sensor way, namely before installing a front wheel turns differential sensor, and the rear wheel speed sensor each one.

The pulse signal generator gear, gear wheel installed in the pulse signal generator produces pulse count and the wheel speed

(2), brake pressure adjusting device

General automobile braking system is divided into three separate hydraulic systems, namely the left front and rear wheels and move around. Brake pressure adjusting device according to the electronic control unit in computer instruction, through pressurization, keep hydraulic pressure, to adjust the above three of four wheels brakes system pressure. Brake pressure regulating devices attached to the special electric pumping, if you need to improve, improve hydraulic pressure motor.

3 and the electronic control unit

Each wheel sensor based on the signal sent by the electronic control unit, the

computer, according to a predetermined judge each wheel system program computing power. According to the calculation results, if need to increase, force of solenoid valve, if open to remove brake oil discharge solenoid valve is opened.

3 and the working principle of ABS:

ABS system according to the wheel rotation, adjust the braking force, to prevent the wheel lock. Auto brake, the car with the car wheel side of the wheel speed sensor produces alternating current signal and its frequency with the increase of wheel rotation angular velocity, in order to test the wheel speed, and any instant changes to the electronic control unit constantly input these the wheel signal. The electronic control unit is constantly monitor these signals, and compared the information stored in advance. If the signal frequency sharply, shows that the wheel will lock, the electronic control unit will reduce the instructions actuators wheel brake hydraulic braking points of pump. When the sensor signal that wheel and normal turns, the electronic control unit and elevated wheel brake directives allows the brake hydraulic cylinder. Actuator according to the electronic control unit instruction "reduce", "rise", "maintain" each wheel brake hydraulic braking points of pump, which travels about 4 ~ 10 times the pulse form brake pressure adjustment, and always will be the sliding rate control on wheels, best sliding rate scope to try to play brake system force and prevent wheel lock, maximize the braking stability of automobile, increased security, shorten the duration and braking distance.

Many (2) power allocation system EBD),

Peugeot 307 in installation of ABS braking system) (anti-lock, install a more advanced than the ABS, many dynamic EBD distribution system, according to brake because EBD generated when the shaft, and the different unloading transfer before the rear axle, automatic regulation system, improve the braking power allocation proportion, and improve efficiency of ABS braking stability. Automobile braking four tires in the ground conditions often not attached. For example, sometimes left front and right rear wheel attached to the dry cement, and right and left rear is attached to the water or the mud, this kind of situation will result in automobile braking four wheels and the friction surface, braking to skid and tilt and vehicle side tumbling accident. With high-speed computer in automobile EBD braking moment of four tires on different ground of induction and calculation

Different friction, four tires of numerical braking device according to different situations in different ways and strength, and brake in constant speed adjustment, to

ensure smooth traffic safety,. The function is in the car EBD braking moment, high-speed calculate four tires due to friction attached different values, then adjust brake, make it according to the procedures set in motion to adjust, high-speed traction force and friction (), in order to ensure the vehicles matching stable and safe. While the brakes wheel lock, under the situation of ABS movements in before EBD each cranks balances already

The effective ground grip, can prevent appear guy and lateral and shorten the automobile braking distance. EBD is actually the auxiliary function of ABS it can improve the efficacy of ABS.