Gas detection apparatus and automatic ventilation system for vehicle

摘要

In a gas detection apparatus (10) incorporating a gas sensor element (11) and a vehicle automatic ventilation system (100) including the apparatus (10), a sensor output value S(n) is obtained, and a base value B(n) is calculated by use of Expression (1): B(n) = B(n-1) + k1ÄS(n) - B(n-1)Ü - k2ÄS(n) - S(n-5)Ü in the case where S(n)≥B(n-1), or by use of Expression (3): B(n) = S(n) in the case where S(n) < B(n-1), followed by calculation of a difference value D(n); i.e., S(n) - B(n). When the difference value exceeds a predetermined high-concentration threshold, a high-concentration signal is generated to close a flap (34). After that, the base value B(n) is calculated by use of Expression (4): B(n) = B(n-1) + k3ÄS(n) - B(n-1)Ü - k4ÄS(n) - S(n-5)Ü. When the difference value becomes smaller than a predetermined low-concentration threshold, a low-concentration signal is generated to open the flap (34).