| 摘要 |
PURPOSE:To treat exhaust gas with simplified apparatus by preventing the rise of temperature by interrupting exactly secondary air injection even when the temperature of catalyst is abruptly risen and also by continuing the secondary air injection even at the time of low temperature. CONSTITUTION:When starting engine when the temperature of catalyst is lowered, the catalyst temperature is rapidly risen and the internal resistance of the catalyst tamperature sensor 21 is smaller, whereby the output V2 from the differential amplifier 23 is rapidly reduced and the output V3 from the differentiating circuit 24 approximates from minus infinty to zero. When the output V4 of the differentiating circuit 24 reaches a value below the judged voltage V at the decisive device 26, the solenoid 17 is excited through the power amplifier 27. In short, even when the catalyst temperature does not reach a fixed value, the solenoid 17 is excited when the rising rate of temperature is great, negative pressure is introduced into the actuator 8 through the switching valve 16, and the secondary air supply conduit 6 can be closed by the valve 7. |
