| 摘要 |
PURPOSE:To judge the contamination in a vehicle room similarly to a human way of sensing and perform effective air conditioning control conforming with the feeling of human beings by judging that a contamination state is entered on the basis of variation in the variation rate of a sensor output signal only when the sensor output signal exceeds a contamination detection threshold value level. CONSTITUTION:A gas sensor 3 outputs an analog signal of a voltage, etc., corresponding to the degree of the contamination in the vehicle room and the sensor output increases gradually as the degree of the contamination increases gradually. The threshold level (b) for air contamination detection is a fixed value larger than the sensor output (a) and varies at a fixed variation rate following up the sensor output. A variation range having at least an upper limit is set as to variation in output (a), and the threshold level (b) is varied within this variation range at an optionally determined variation rate following up the output (a). When the variation of the output (a) is slow, the variation in the threshold level (b) varies following up the variation of the sensor output while the fixed value larger than the output (a), and it is judged that the air in the vehicle room is clean. When the output (a) varies so abruptly that the threshold level (b) can not follow up the variation and the sensor output exceeds the threshold level, it is judged than the air in the vehicle room is contaminated.
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