Liquid level monitoring device for overfill protection in motor vehicle fuel tank

摘要

The device includes a capacitor (5) arranged at the critical level so that liquid (2) can penetrate inside the capacitor. A measuring device (8) detects the capacitance of the capacitor and provides measurement signals (9). Noise peaks are filtered out of the measurement signals and the current value of the filtered signal is compared with a reference value which was formed from previous measurement values. A signal is generated to indicate that the level has been exceeded if the present value exceeds the reference value by a preset margin.