| 摘要 |
The invention relates to a diagnosis device that effectively diagnoses a cooler without providing a temperature sensor upstream of the cooler. The diagnosis device diagnoses the cooler (16, 22) adapted to cool a fluid flowing through intake and exhaust systems (11, 12) of an engine (10), and includes: a downstream temperature sensor (34, 37) for detecting a fluid temperature downstream of the cooler; a fluid temperature calculation unit (42, 52, 53) for calculating a fluid temperature upstream of the cooler based on a fluid state quantity; a sensor output value calculation unit (44, 54) for assuming an upstream temperature sensor configured to detect a fluid temperature upstream of the cooler, reflecting a sensor response delay in the calculated fluid temperature, and calculating an estimated sensor output value of the upstream temperature sensor; and a cooler diagnosis unit (45, 55) for diagnosing the cooling efficiency of the cooler based on an actual sensor input value entered from the downstream temperature sensor (34, 37) and the calculated estimated sensor output value. |
