| 摘要 |
<p>A fuel-gauging system has a capacitive probe mounted in a fuel tank and supplied with an alternating voltage Vs from a drive unit. The output of the probe is rectified by a diode mounted in the tank, prior to supply to a measuring unit. The voltage VD across the diode varies with temperature and is measured periodically by reducing the input voltage Vs by a known factor X. The voltage VD is calculated by the measuring unit from the two output currents I1 and I2 produced respectively at the two different voltages Vs and Vs/X. The capacitance and hence the depth of fluid is calculated using the known voltage VD across the diode. The drive unit has a transformer that is used to reduce the voltage periodically by switching between different tappings of its secondary windings.</p> |
