Measuring contents of motor vehicle fuel tank - using pressure sensor for gas vol. above fuel level and evaluator

摘要

The gas vol. (3), esp. of air, above the fuel (2) level is dependent upon the amt. of fuel in the tanks (1). The gas pressure of the vol. is changed at timed intervals between given lower and higher pressure vlaues by pu,ping in and releasing a gas. The time needed for change of pressure is measured. From this measured time the gas. vol. is determined and, taking into account the total vol. of the tank, the fuel content is derived. After attaining the higher pressure value through pumping in a gas, the time taken to reach the lower value by releasing the gas is measured, this time being below approx. two seconds. The gas pressure is pref. measured by a pizeo-electric sensor. The latter (4) is connected to a microcomputer (12) and an electronic evaluating unit (15) with a display instrument (16). ADVANTAGE - Simply avoids influence to temp on measurement.