Esp Control Mode

The self-induced high pressure and return flow pump (p1) draws brake fluid out of the reservoir via the inlet solenoid (y22) and master brake cylinder, and provides the high pressure required for actuating the respective wheel brake. If rapid stabilization intervention is required, the pressure build-up phase is supported by active actuation of brake assist system. Atmospheric pressure is fed to the rear sides of diaphragms in the brake booster. This generates a pressure of about 5 bar in the brake circuits. Primary pressure produced in this way is directed by the switchover solenoid valve (y18) via check valve (7) into the active brake circuit to the right front brake caliper until pressure downstream of check valve (7) is higher than the primary pressure.

At the same time primary pressure is applied to the suction side the high pressure and return flow pump (p1) via the opened inlet solenoid valve (y22) and improves volumetric efficiency of the pump and its delivery rate. Primary pressure is kept away from the non-active wheel brakes by closing the solenoid valves (y6, 10, 12). High pressure is limited by the pressure relief valve integrated into the switchover solenoid valve (y19), which opens at pressure greater than 150 bar.