Temperature sensor plausibility diagnosis unit and plausibility diagnosis method and internal combustion engine exhaust purification apparatus

摘要

A temperature sensor plausibility diagnosis unit performs plausibility diagnosis of a temperature sensor disposed inside a storage tank in an exhaust purification apparatus of an internal combustion engine that delivers an additive inside the storage tank to an exhaust pipe upstream of a reduction catalyst and selectively reduces and purifies NOx in the exhaust. The temperature sensor plausibility diagnosis unit includes an additive heat capacity calculating portion that calculates the heat capacity of the additive, a heat quantity variation calculating portion that calculates an increase or decrease in the quantity of heat that the additive receives, and a plausibility diagnosing portion that determines the plausibility of the temperature sensor by comparing an estimated temperature course of the additive estimated from the heat capacity of the additive and the increase or decrease in the quantity of heat with a sensor temperature course of the additive detected by the temperature sensor.