| 摘要 |
PURPOSE:To perform the inner and outer air switching control stably and efficiently, by bringing the operator to the inner air circulating state through the impurity component detection signal of the outer air while returning to the outer air supply state when the detected signal reaches to the predetermined level and continues for predetermined time. CONSTITUTION:The microcomputor 6 is commanded of the inner air take-in through the turning-on of the switch 9b while commanded of the outer air take-in through the turning-on of the switch 9c, and the inner and outer air exchange damper 2 is exchanged by means of an actuator 8. Upon turning on of the switch 9a, the inner and outer air exchange is controlled automatically by the signal from the gas sensor 4 for detecting the noxious gas concentration. When the output Vs from the sensor 4 exceeds over the level A, it is exchanged from the outer air supply to the inner air circulation. If Vs<A, Vs>=B, the delay timer counter t1 is preset and when Vs<B and t=0, it is exchanged to the outer air supply. When the sensor output is maintained below the setting level for the predetermined time, it is exchanged to the outer air supply thereby the inner and outer air exchange can be performed stably and efficiently. |
