Vdo Adolf Schindling Ag

Hans J Baumgart

Martin Haub

Wolfgang Hauschild

Klaus Albrecht

An apparatus for measuring liquid level in a container, particularly the fuel tank of a motor vehicle, has a plurality of detector stages for sensing or detecting a plurality of liquid level ranges, whereby an indicator stage can be arranged to indicate a first, normal range of measurement, and a second, precise resolution can be obtained of at least a portion of the overall measurement range, without requiring an excessively larger indicator stage. This is accomplished by arranging at least two groups of sensing elements one above the other in the tank and connecting them to indicator elements via change-over circuits such that one range of measurement is made via one group of sensing elements and a second, more precise range of measurements is made via a second group of sensing elements.

Liquid level scale changeover measuring apparatus

A device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable, controlled by a timer, to the resistance probe, a circuit, controlled by the timer, for detecting and storing an initial voltage drop on the resistance probe at an initial time and a measurement voltage at a defined time after the connection of the source of constant current, and a circuit for evaluating these voltages by subtraction of the measurement voltage from the initial voltage and if necessary under circumstances inversion of the difference in order to form a display voltage which corresponds to the level. There are provided a resistance probe structure for compensating for the influence of the change in level of the liquid on the display voltage due to thermal expansion as a function of its initial temperature and a computation circuit for compensating for different heat transfers from the resistance probe to the liquid as a function of the initial temperature.

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Schwalbach, Germany

Hans J Baumgart