Patent ID: 7779626

Claim:
An estimating device for exhaust temperature in an internal combustion engine, comprising: a gas sensor provided in an exhaust system of the internal combustion engine for detecting a concentration of a component in exhaust; a heater for heating the gas sensor; a temperature detecting unit for detecting element temperature data being one of (i) an element temperature of the gas sensor and (ii) a parameter in correlation to the element temperature; an energization controlling unit for controlling energization of the heater by feedback controlling an amount of heater energizing operation so that the element temperature data agrees with a predetermined target; a heat release quantity computing unit for computing a heater heat release quantity associated with the energization of the heater based on the amount of heater energizing operation that is feedback controlled by the energization controlling unit; an estimating unit for estimating the exhaust temperature based on a balance between (i) an emitted heat quantity of the gas sensor in proportion to a temperature difference between the element temperature and the exhaust temperature and (ii) the heater heat release quantity in proportion to heater power by using at least one of (i) an emitted heat quantity-related parameter in relation to the emitted heat quantity of the gas sensor and (ii) a heat release quantity-related parameter in relation to the heater heat release quantity; a unit for determining that the exhaust system of the internal combustion engine is in such a state that the temperature thereof becomes a given temperature; and a unit for permitting the energization controlling unit to energize the heater in a state in which the temperature is the given temperature; and a parameter calibrating unit for calibrating the at least one of (i) the emitted heat quantity-related parameter and (ii) the heat release quantity-related parameter through comparison of the emitted heat quantity of the gas sensor with the heater heat release quantity in a state in which the exhaust temperature is the given temperature, the estimating unit being further configured to estimate the exhaust temperature by using the at least one of (i) the emitted heat quantity-related parameter and (ii) the heat release quantity-related parameter, which are calibrated by the parameter calibrating unit.