db57d230

13.2. Anti-blocking system of brakes (ABS)


The anti-blocking system of brakes is intended for an exception of blocking of wheels at intensive braking.

Main ABS functions:

– reduction of a brake way at the expense of an exception of blocking of wheels at intensive braking;
– improvement of stability of driving in the course of braking.

The anti-blocking system of brakes works at information basis from four sensors transferred to the ABS block. The system operates each wheel separately and reduces liquid pressure in that wheel brake mechanism which wheel begins to be blocked.

Under normal conditions the standard brake system carries out braking until blocking of the wheel found by the ABS control unit. During usual braking inlet valves usually open, and final valves are usually closed.

When the ABS control unit finds blocking of a wheel, it operates each valve for increase or reduction of pressure.

The ABS control unit determines the frequency of rotation and norm of delay of each wheel on the basis of information from sensors of frequency of rotation of a wheel. When braking the frequency of rotation of a wheel decreases and the ABS block defines a difference between the speed of the car and frequency of rotation of a wheel. If delay of some wheels exceeds the expected value, the ABS block defines the beginning of blocking and opens the corresponding electromagnetic valves to reduce pressure of brake fluid. At the same time the frequency of rotation of a wheel increases and the electromagnetic valve of dumping of pressure is closed and there is an increase in pressure of brake fluid in the working brake cylinder of the corresponding wheel.