EXHAUST GAS PURIFYING APPARATUS FOR INTERNAL COMBUSTION ENGINE

The present invention has an object to provide an exhaust gas purifying apparatus for an internal combustion engine capable of obtaining accurate temperature information relating to a catalyst placed in an exhaust passage of the internal combustion engine. The degree of influence emthc of a catalyst inlet gas temperature and catalyst rear end temperature ethuf[end] is calculated (Step 102). An estimated value ethco of an outlet gas temperature is calculated by weighted averaging the inlet gas temperature and the catalyst rear end temperature ethuf [end] considering the degree of influence emthc (Step 104). A temperature correction coefficient ekthuf[x] for each region of the catalyst is calculated as a function f(emthc) of the degree of influence emthc (Step 108). A deviation between the outlet gas temperature estimated value ethco and a measured value of the outlet gas temperature is multiplied by the temperature correction coefficient ekthuf[x] to calculate an estimated value correction amount ecthuf[x] (Step 110). The estimated value correction amount of the inlet portion ecthuf[0] is added to a inlet gas temperature estimated value (Step 114).