Measuring level of liquid in housing, esp. of oil in vehicle engine - evaluating voltage across metal resistive element immersed in liquid and in series with current generator

摘要

The method of measuring the level of liquid in a housing involves using a resistive metal element (1) immersed in the liquid at a defined position in the housing. The element is supplied with a constant current for a very short, defined time, then the voltage at the element's connections (4, 5) is varied between two values to calibrate the element's position w.r.t. the liquid surface. After activation of a series current generator (2) the voltage across the element is measured to remove the dependency on ambient temp. The changing element contact voltage is traced to accurately determine the difference between the starting and finishing voltages. ADVANTAGE - Low cost, achieves sufficient accuracy.