Alfred Teves Gmbh

Hermann Esselbruegge

Michael Zydek

Heinz Loreck

Hans-Wilhelm Bleckmann

A circuit configuration for actuating a safety relay (1) such as the main relay of an electronically controlled brake system of an automotive vehicle at least has two transistors (T1, T2) connected in series and a monitoring circuit (5) which will urge the transistors into the non-conductive state if there is a defect or trouble. The operativeness of the transistors (T1, T2) or of the monitoring circuit (5) will cause the safety relay (1) to be switched off.

Circuit configuration for actuating a safety relay

This is a circuit configuration provided for an anti-lock-controlled brake system and serving for processing sensor signals obtained by wheel sensors (5) and for generating braking pressure control signals. This circuit configuration contains two microcontrollers (1, 2) interconnected by data exchange lines (7). The handled signals are concurrently processed by the microcontrollers independently of one another and the exchanged signals are checked for consistency. A deviation of the exchanged signals which is due to malfunctions is signalized to a safety circuit (8) which, thereupon, interrupts the power supply to the solenoid valves (Ll . . . Ln). The monitoring signal (WD1, WD2) fed to the safety circuit (8) is a predetermined alternating signal in case of consistency of the exchanged signals and in case of proper operation of the circuit configuration. The safety circuit (8) compares the alternating signal with a time standard derived from a clock generator (TG2, TG3) which is independent of the operating cycle (TG1) of the microcontrollers (1,2). A change in the alternating signal, as well as a failure in the time standard, causes a cut-off of power supply and, hence, of anti-lock control.

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Weiterstadt, Germany

Hermann Esselbruegge