PURPOSE: To accurately detect the deterioration of a converter by comparing the thermal deterioration quantity of the converter based on the detection signal of an exhaust temp. sensor detecting the temp. of exhaust gas and the use time of the converter with a reference value.
CONSTITUTION: The thermal deterioration quantity of a catalyst converter 4 is calculated on the basis of the detection signal of an exhaust temp. sensor 5 detecting the temp. of exhaust gas and the use time of the converter 4 by the deterioration quantity calculation part 6a of a controller 6. The deterioration judging part 6b of the controller 6 compares the deterioration quantity with a reference value to judge the thermal deterioration of the converter 4. By this method, the judgement of the converter 4 can be always accurately performed and the replacement of a catalyst can be urged on a driver at a proper period and exhaust gas can be purified certainly still more.
YOSHIDA MICHIYASU
KOGA KAZUO
KUME TAKEO
