Braking pressure modulator for an electronic braking system

A pre-engagement unit for a braking pressure modulator for a pressure regulating circuit of an electronic braking system of a vehicle having an electric braking command signal transmitter which delivers a driver initiated electric brake value setting to an input of an electronic control unit, the pre-engagement unit comprising:

• a) a first pneumatic inlet through which a supply pressure is supplied to the pre-engagement unit;
• b) a second pneumatic inlet through which a redundancy pressure is supplied to the pre-engagement unit;
• c) a first pneumatic output terminal through which the pre-engagement unit is connected to an air quantity augmenting relay valve;
• d) a second pneumatic output terminal through which the pre-engagement unit is connected to a pressure sink;
• e) an electrically actuated valve system comprising a plurality of solenoid valves including a plurality of interconnected pneumatic terminals and a plurality of electrical terminals which are connected to output terminals of the electronic control unit:
• f) wherein under normal conditions, the pressure delivered at the first pneumatic output terminal to be converted by said air quantity augmenting relay valve to a braking pressure is determined by said electric brake value setting;
• g) wherein in the case of failure in said electronic brake system, the redundancy pressure is delivered at the first pneumatic output terminal to be converted by the air quantity augmenting relay valve to the braking pressure;
• and
• h) wherein under normal conditions, the redundancy pressure is also delivered to the air quantity augmenting relay valve and comprises a component of the braking pressure.