Method and device for monitoring the fill level of a liquid in a liquid container

An electronic evaluation and control unit for a device for monitoring a fill level of a liquid in a liquid container, comprising:

• a signal input for measurement signals of an associated heated thermocouple and a signal input for an unheated thermocouple associated with the heated thermocouple;
• a subtraction unit configured to form from the measurement signals a temperature difference signal characteristic for a temperature difference with respect to the heated and unheated thermocouples;
• an evaluation unit with means for continuously monitoring a temporal profile of the temperature difference for a significant increase within a time interval of predetermined duration, which time interval occurs before a respective evaluation time point;
• an alarm output for outputting an alarm signal as soon as an increase in the temperature difference within the time interval reaches or exceeds a predetermined limit value;
• said evaluation unit being configured to ascertain a sequence of temperature differences over a large number of periodically sequential measurement time points, wherein the differences between a last ascertained sequence element and all predecessors thereof, the measurement time points of which fall within a time interval of pre-specified length, are formed at an evaluation time point, and to output an alarm signal as soon as at least one of the differences reaches or exceeds a previously fixed limit value.

An electronic evaluation and control unit for a device for monitoring a fill level of a liquid in a liquid container, comprising:

• a signal input for a temperature difference signal generated by a circuit with a heated thermocouple and an unheated thermocouple;
• an evaluation unit with means for continuously monitoring a temporal profile of the temperature difference for a significant increase within a time interval of predetermined duration, which time interval occurs before a respective evaluation time point;
• an alarm output for outputting an alarm signal as soon as an increase in the temperature difference within the time interval reaches or exceeds a predetermined limit value;
• said evaluation unit being configured to ascertain a sequence of temperature differences over a large number of periodically sequential measurement time points, wherein the differences between a last ascertained sequence element and all predecessors thereof, the measurement time points of which fall within a time interval of pre-specified length, are formed at an evaluation time point, and to output an alarm signal as soon as at least one of the differences reaches or exceeds a previously fixed limit value.