 printable version
Operating principle
Maximum braking performance is achieved at the maximum tire adhesion to the road surface. When sliding on the surface of the tire during braking wheel linear velocity becomes less than the speed of the vehicle. Minimum slip (0%) is achieved with a free rolling wheel, and the maximum (100%) - If the wheel is locked. Optimal efficiency is achieved when the braking slip is equal to 15%. It is in this largest slide fully preserved the stability and handling. Anti-lock brake system is designed to restrict the pressure generated in the hydraulic brake system so that the amount of slip was near optimum. The basis of the anti-lock system laid separately for each wheel principle. The system is designed to respond immediately to every change in the coefficient of friction with the surface of the wheel and the load on the vehicle. Anti-lock braking system prevents the wheels from locking under heavy braking. This reduces the braking distance, especially under low grip in the rain and snow. The adhesive force between the wheels and the road is greater if the braking wheel continues to rotate. Furthermore, even when fully braking the vehicle remains controllable. Speed sensor - one at each wheel - is measured by the speed of rotation of the wheels. According to the signals from the sensors, the electronic control unit calculates the average speed approximately corresponding to the vehicle speed. Comparing the speed of each individual wheel from the average speed calculation, the electronic unit determines the slip ratio of each wheel thereby determines which wheel is in predblokirovochnom condition. When one of the four wheel speed sensors will transmit a signal to block the respective wheels, the electronic control unit will give a closing signal to corresponding inlet solenoid valve, which immediately block the flow of brake fluid through the brake line to the brake of the wheel and the braking force will remain constant. If sliding nevertheless continue, the exhaust valve opens and the pressure in the hydraulic system of the brake is reduced. Once again, the wheel begins to rotate, open the intake and exhaust valve closes. Circuit pressure will rise, and the wheel again starts braking. Cycle braking and free rotation of the wheel is carried out in a very short period of time (a few times per second) and is repeated until the vehicle is stopped or until the brake pedal is released. The effect of this process applied to each wheel. Emergency shutdown system will disable the ABS system at any malfunction or low (below 10 V) voltage in the vehicle electrical system. The electronic control unit performs a diagnostic function to alert the driver fire of a control lamp of the registration failure of electrical circuits or elements anti-lock system. When a faulty ABS system brakes continue to operate in the normal mode (without anti-lock). Fire of control lamp ABS while driving indicates a fault and shutting down the system. In this case, proceed as follows: stop the car, turn off and restart the engine; Check the battery voltage. If the voltage is below 10.5 V, the battery need to be charged;
A WARNING If the ABS warning lamp is lit at the beginning of the trip, and then goes off, it means that the voltage is below the allowable limit for ABS, but then rose as a result of the generator. |
check for oxidation battery terminals; hang out the car, remove wheel and check that the wiring wheel speed sensors; If no fault is found, then further testing anti-lock brake system is necessary to hold on to a specialized service station.
NOTE Since June 1988 the ABS control unit has a module that defines the storage and defects arising during operation. At station maintenance information is read from the storage unit and the defect is eliminated. |
| 
