抄録
A palm-sized hydrogen sensor using ultrasonics for automotive application is demonstrated at temperatures from -10 to 50°C. The sound velocity of hydrogen is about four times larger than that of the air. Therefore, it is possible to measure hydrogen concentration in the open air by just measuring the sound velocity difference before and after the hydrogen leak. The measurement method is simple and similar to the measurement of a distance by ultrasonic which is well established. It is shown that the distance between ultrasonic probes can be as small as 20mm which can be as possible size for the detection head. Since the detector is measuring the sound flight time between two probes, the detectin time of this sensor can be less than 0.1msec; therefore, this method is practical for detecting the hydrogen leakage in order to immediately shut down the valves.
