PERFECCIONAMIENTOS EN UN SENSOR ELECTRONICO PARA SISTEMAS DEFRENOS DE VEHICULOS

摘要

The invention relates to an electronic sensor for determining the start time and duration of the brake relief phase in brake force modulation cycles in vehicles with so-called antilock brake systems. A tachometer (10) detects the rotation speed of the wheels. The output signal of the tachometer is differentiated in a differentiating circuit (20) and is compared to a reference signal (a0) from a reference value generator (30). A switch (60) is switched-on by the output signal from the comparator (40) when the differentiated signal has reached the reference value. Thereby a break force reduction phase of the brake force modulator (80) is started. A reference and sampling circuit (50) stores the instantaneous speed signal (w(t)) from the tachometer (10) and samples the instantaneous value (w(t0)) of this signal at that point in time when the differentiated signal (a(t)) has reached the reference value (a0). The reference and sampling circuit (50) also provides a reference signal (M) representing a reference speed that is supplied to one input of a second comparator (70) and in this comparator is compared to the speed signal (w(t)) from the tachometer (10). The output signal of the second comparator (70) switches off the switch (60) when the speed signal (w(t)) from the tachometer (10) has reached the speed reference signal level (M). Thereby the switch (60) switches off the modulation system (80) and once again lets through the signal (w(t)) to the sampling circuit. The slope of the reference signal (M) is controlled by the modulated brake force.