Contents: ESP system control mode ↡ ESP system control mode: pressure…↡ ESP control mode: pressure release ↡
ESP system control mode
VN 9.060 f. High pressure; g. Pre-pressure
The ESP control unit performs brake control action to regulate the vehicle's driving stability.
At the start of ESP regulation, the changeover solenoid valves (y18, y19) are moved to the "lock" (closed) position and the injection/exhaust pump unit (ml) is activated. From a speed of 20 km/h (range of motion start) is activated (opens) bAS solenoid valve (A7/7y1) in the brake booster (A7/7). Atmospheric pressure is applied to the rear side of the diaphragms in the brake booster, causing a pressure of approximately 5 bar to be generated in the brake circuits as a pre-pressure on the inlet side of the injection/exhaust pump unit.
The inlet solenoid valve (y22) opens only during the pressure build-up process. In this case, the self-priming injection/exhaust pump (p1) sucks in brake fluid from the filling tank via the inlet solenoid valve (y22) and the master brake cylinder.
To limit the high pressure, a pressure reducing valve is integrated into the changeover solenoid valve (y18) (about 170 bar).
ESP system control mode: pressure maintenance
VN 9.061 a. Suction pipeline; b. Brake pressure; g. Pre-pressure
The valve position adjustment procedure given in the example applies to the VR brake mechanism (front right wheel).
If more intensive braking control action is no longer required to stabilise the movement, the pressure maintenance mode is activated within the framework of the ESP system regulation.
The inlet solenoid valve (y22) closes.
Due to this, it is not possible to increase the pressure in the wheel brake mechanism using the injection/exhaust pump (p1).
ESP control mode: pressure release
VN 9.062 a. Suction pipeline; e. Low blood pressure
The valve position adjustment procedure given in the example applies to the VR brake mechanism (front right wheel).
If the brake pressure required to stabilize the movement is excessively high, the ESP control mode "pressure reduction" is activated.
The pressure reduction process begins when the switching solenoid valve (y18) opens. The solenoid valve (y8) remains open and the solenoid valve (y9) remains closed.
The brake fluid flowing back passes through the injection and suction pump (p1), through the switching solenoid valve (y18) and then through the master cylinder into the brake fluid filling reservoir.
Article was obtained from the portal (mercedesman.ru)
In these control modes, the self-priming pressure/drain pump (p1) is also activated.