Vehicle hydraulic dual-circuit brake system

A hydraulic dual-circuit brake system for a road vehicle having an anti-lock system (ABS) operational on a recirculation principle and a device for driving-dynamics control (DDC) operational on a principle of keeping longitudinal and lateral vehicle wheel slip within limits compatible overall with dynamic stability of the road vehicle by an automatic electronically controlled activation of at least one wheel brake, and a device for automatically initiating full braking when a vehicle driver actuates a brake pedal at a speed higher than a relevant threshold value, comprising

• (a) brake-circuit division comprising front axle and rear axle brake circuits and, a brake-pressure control unit including a static master cylinder operatively arranged to be actuable by the brake pedal via a brake booster and having pressure outlets assigned individually to front and rear brake circuits;
• (b) brake-pressure regulating valves of the anti-lock system operable to be selectively triggered for selection of at least one wheel brake to be activated in the driving-dynamics control mode;
• (c) a pedal-position sensor configured to generate electrical output signals characteristic of an instantaneous position of the brake pedal;
• (d) an electronic control unit for processing said signals to control at least one of anti-lock mode and driving-dynamics control mode as desired-value data for vehicle deceleration desired by the vehicle driver, and
• (e) a pressure sensor operable to generate electrical output signals characteristic of instantaneous values of the brake pressure fed into the front-axle brake circuit and processable by the electronic control unit as brake-pressure actual-value information signals, wherein
• (f) the brake-pressure control unit configured to be controllable into a brake-pressure supply mode both by pedal-controlled pressure loading of a drive-pressure space of the associated brake booster and by valve-controlled pressure loading of the drive-pressure space of the brake booster, said valve-controlled pressure loading being initiatable automatically by output signals from the electronic control unit;
• (g) an auxiliary cylinder provided for one of a supplementary and sole supply of brake pressure to the front-axle brake circuit of the brake system so as, by way of valve control, selectively loadable with and relieved of outlet pressure of an auxiliary pressure source and via which, both during normal driver-controlled partial or full braking and during automatically controlled partial or full braking, a brake quantity fluid is displaceable into the brake circuit connected to the primary pressure outlet of the brake-pressure control unit, the auxiliary cylinder constituting a pressure intensifier whose maximum outlet-pressure level is sufficiently high for utilization of high adhesion coefficients in the driving-dynamics control mode;
• and
• (h) the brake-fluid quantity displaceable into the front-axle brake circuit is controllable in a predeterminable monotonic correlation from a comparative processing of output signals of the pedal-position sensor with output signals of the pressure sensor.