ABS, full name Anti-lock Brake System, i.e. anti-lock brake system is a brake device for a vehicle, which uses electronic control to prevent vehicle wheels from locking during emergency braking.
1.ABS effect
ABS may brake during motion of the wheel for rapid, accurate and effective control of the wheel brake in the best possible situation. Even when the vehicle wheel braking longitudinal adhesion coefficient at a peak, while it also maintained a high lateral adhesion coefficient, so that the car has a good anti-skid braking capability and the shortest distance to improve vehicle driving safety.
2. basic composition
1, the braking pressure regulating device
automotive braking system typically consists of three independent hydraulic system components, i.e. the front left and right front wheels and left and right wheel. Brake pressure regulating device brake hydraulic pressure command means an electronic control computer, by pressurized hydraulic holding, adjusting the regulator of the three systems in accordance with four wheels.
Brake pressure regulating device with a dedicated electric pump, if necessary to increase the hydraulic pressure, a hydraulic drive motor increase.
2, the electronic control unit
of each wheel based on signals sent by the sensor, the electronic control device using a computer to calculate the braking force of each wheel is determined by the pre-determined program. According to the results, if the need to increase the braking force, the solenoid valve opens into the oil, if desired brake release solenoid valve to open drain.
3, a wheel speed sensor
around the front and rear cars are installed on each wheel a wheel speed sensor for detecting the rotational speed of the wheel, this arrangement is referred to as sensor arrangement method. On a front wheel drive vehicle, a sensor using the following general manner, i.e., a wheel speed sensor mounting portion front front differential, and the installation of a left and right rear wheel speed sensors.
Gear pulse signal generator mounted on the wheel, the gear speed is proportional to the pulse signal generator generates the number of pulses and the wheel. Exports more sensors signals the electronic control device.
3.ABS works
during braking, ABS in accordance with the speed of each wheel speed sensor signal came, quickly determine the locked state of the wheel, the wheel lock top closure start input solenoid valve normally open, so that the braking force constant, if the wheel continued locking, the output of the normally closed solenoid valve is opened, the brake pressure on this wheel because of the brake fluid reservoir tank occurs through the conduit rapidly down, the braking force is prevented because the wheel is too large to completely lock.
In the meantime, the main control valve is energized open, the brake fluid pressure can enter the dynamic brake, the brake fluid from the dynamic pressure line through the dynamic power control of the main valve, the master cylinder gasket an input line reaches the outer edge of the front wheels so repeated operation (the operating frequency of 3-12 times / sec), so that the braking state is always in the optimum point (slip ratio S is 20 percent), to achieve the best braking effect, driving safest.
in front of the brake fluid in the master cylinder interior chamber is a dynamic pressure of the brake fluid, which sleeve is moved rightward to drive the reaction, the reaction in turn pushes the booster piston sleeve, so that the right brake pedal push rod shift. Therefore, the ABS work to time, the driver can feel the foot pedal vibrate, I heard some noise.
After the deceleration of the vehicle, once the ABS computer detects wheel locking condition disappears, it makes the main control valve is closed, so that the braking system into the normal working state. If the accumulator pressure drops to a safe limit, the fault indicator red and amber ABS brake failure indicator light. In this case, the driver use a large deep soil fertility brake pedal to the way of the front and rear wheels to brake effectively.
4.ABS Category
In the ABS, capable of independently adjusting brake pressure control channel is referred to as the brake pipe. The following describes a method of classification by channel.
(1) single channel
often called a single-channel-channel ABS ABS, it is provided a brake pressure in the rear wheel brake regulator manifold, a wheel speed sensor mounted on the rear final drive axle (also each mounted on a rear wheel). Single-channel ABS are generally of two rear wheels together control at low election principles. Single-channel two rear ABS adhesion can not be fully utilized, and therefore the braking distance will not necessarily be significantly reduced.
In addition the front brake is not controlled, there will still be the front wheel brake locking during braking, thus steering capability can not be improved, but the two braking rear wheels will not lock, can significantly improve directional stability during braking, the safety is a great advantage, while simple structure, low cost, it is widely used in light truck vehicles.
(2) two-channel
In two-channel ABS directional stability is difficult, various aspects of the steering control and braking performance was compromised, few currently used .
(3) Three-channel
three-channel ABS two front wheels is independently controlled by the two rear wheels with a low control principle selected from the group (i.e., two a control channel by the wheel, to ensure that the wheels do not lock a smaller adhesion principle), also known as hybrid control. This means Santana 2000GSi ABS with both.
Features: The two rear wheels together at low control principle selected to be equal to ensure the car under various conditions, a braking force of the two rear wheels, even if both sides of the wheel adhesion coefficient difference between the larger, two a wheel braking force are restricted to a small level of adhesion, the braking force of the two rear wheels remain balanced, to ensure the car under various conditions have a good directional stability during braking. Of course, the two rear wheels at low electionWhen the control principle together, problems may occur adhesion coefficient larger rear side of the adhesion can not be sufficiently utilized, so that the total vehicle braking force is reduced.
it will be seen, during emergency braking, since the forward axle load occurs, the total braking force of a motor vehicle, the proportion occupied by the rear wheel braking force is reduced, in particular small front-wheel drive sedan, front-wheel adhesion is much greater than the adhesion of the rear wheel, rear wheel braking force is usually only accounted for about 30 percentage braking force, rear-wheel adhesion underutilized loss does not affect the total braking force on the car Big. In / h to 60km comparison test emergency braking Santana 2000, the ABS models have only one meter shorter than models without ABS braking distance, but there has always been the direction of ABS models, without losing control of direction .
independent control of the two front wheels, the main consideration cars, particularly front-wheel drive vehicle, the front wheel braking force proportional share of the total vehicle braking large (up to 70 percentage ), you can take advantage of both front wheels adhesion. Cars on the one hand as large as possible total braking force, help shorten the braking distance, on the other hand two front braking can always maintain large lateral adhesion, making the car to maintain good steering capability.
Although the two front wheels may lead to two separate control unbalanced front wheel braking force, but the two front wheel braking force unbalance effects on directional stability is relatively small cars, but also the steering by the driver the resulting impact of the amendment. Thus, three-channel ABS is widely used on cars.
(4) 4-channel
There are four four-channel ABS wheel speed sensor, the brake cylinder in the line leading to the four wheels, each provided a brake pressure control device, independent control, configured in the form of four-channel control. Guangzhou Honda four-channel ABS system that is used. Features: Since the signal is a four-channel ABS wheel speed sensor for each input, respectively, independent control of each wheel, so that a high utilization coefficient of adhesion, adhesion can maximize the use of the maximum of each wheel brake.
Four-channel control method is particularly suitable for the left and right sides of the wheel car close adhesion coefficient road, you can not only get a good directional stability and direction control, and the shortest braking distance can be obtained. But asIf the adhesion coefficient of about two car wheels large difference (e.g., the road surface water or ice), the braking force when the braking surface on the difference between two large wheels, thus generating the yaw moment, the braking force to the vehicle body the larger side of the deviation can not be maintained in a predetermined direction cars, it will affect the stability of vehicle braking direction.
Accordingly, the driver in water or some other slippery icy road driving, the vehicle speed should be reduced, not blindly believe ABS apparatus.
In summary, ABS system device is not a panacea, as a safe-driving support equipment, in full knowledge of its advantages based on the driver should improve their driving skills. And purchase, a lot for the appropriate type of device, so that maximum effect.