| 摘要 |
PURPOSE:To judge a failure with high accuracy when exhaust gas temperature is below a set value with its rising rate being below a target rising rate without increasing a cost while setting a proper diagnosis standby time by setting the target rising rate based on an exhaust gas temperature right after entering a diagnosis operation zone. CONSTITUTION:When actual temperature rising rate TEGR between an exhaust gas temperature TEGR1 and an exhaust gas temperature TEGR2 after the lapse of a defined standby time is lower than a target rising rate TEGROK with the exhaust gas temperature TEGR2 being lower than a set temperature TEGROK, an EGR device 8 is judged in a failure. That is, the judgment of failure is carried out with high accuracy from the comparison of the rising rates of exhaust gas temperatures and the comparison of exhaust gas temperatures without need for increasing the detecting accuracy of a temperature sensor 12, to suppress the increase in cost of a device while enabling the standby time to be set at a proper length to increase the opportunity of diagnosis. Also, the target rising rate TEGROK is varied and set based on the exhaust gas temperature TEGR1 right after entering a diagnosis operation zone, to carry out the judgment of the EGR device with high accuracy. |
