| 摘要 |
PROBLEM TO BE SOLVED: To avoid uncertain measurements, when the surface of a fluid is disturbed by determining as to whether a sensor for measuring the fluid is functions normally. SOLUTION: An aircraft fuel measuring system has a plurality of probes 10 and 11 in a tank 1 for measuring the height of a fuel 2 at different positions. The probes 10 and 11, each include a still well 12 and ultrasonic transducers 15 and 14 which are respectively mounted at the top part and at the bottom part of the still well. The lower transducer 14 transmits a pulse of acoustic energy to the surface 3 of the fuel 2 upward through the fuel 2, to measure the return time until the reflected pulse returns to the transducer. The time thus obtained is used to derive a first measured value of the height of the fuel on bottomup basis. Likewise, the upper transducer 15 transmits downward a pulse to the surface 3 of the fuel through the air 4 and the results are used to derive a second measured value thereof on a topdown basis. The resulting measured values are compared to check the normal operation of the probes. |
