An automated car ventilation system

A prototype of an automated car ventilation system that inhibits the intake of exhaust gas was constructed to explore suitable choices and application methods of gas sensors. The requirements for the gas sensors were discussed and the sensing characteristics of candidate sensors were investigated. The system adopted three metal-oxide semiconductor-type gas sensors. A CO/HC (hydrocarbon) gas sensor and an NO2 sensor were utilized for the detection of exhaust fume in outside-air, and an odor sensor for the monitoring of inside-air. The sensing characteristics of these sensors, including humidity effects were investigated. It has been found that the humidity interference is not negligible, and computer algorithm to cope with the interference was presented. The prototype system satisfactorily shut out exhaust-containing air when the pollution level was high. The data collected on highways indicated that the wind efficiently reduces pollution level.