Patent ID: 7836683

Claim:
A control apparatus for an internal combustion engine, including: a first cylinder group; a second cylinder group; a first upstream catalyst provided in an exhaust passage extended from the first cylinder group; a second upstream catalyst provided in an exhaust passage extended from the second cylinder group; a downstream catalyst provided in a portion downstream of a confluence of the first exhaust passage and the second exhaust passage, the confluence being located downstream of the first upstream catalyst and the second upstream catalyst; and a fuel supply suspending portion that suspends supply of fuel during deceleration, the control apparatus comprising a stoichiometric performing portion that performs stoichiometric combustion by controlling an air-fuel ratio to a stoichiometric air-fuel ratio in one of the first cylinder group and the second cylinder group when one of a temperature of the first upstream catalyst and a temperature of the second upstream catalyst is higher than a predetermined value during deceleration, wherein: the fuel supply suspending portion performs fuel supply suspending control in the other of the first cylinder group and the second cylinder group when one of the temperature of the first upstream catalyst and the temperature of the second upstream catalyst is higher than the predetermined value; and the control apparatus further comprises a fuel supply suspension switching portion that alternately switches the cylinder group in which the stoichiometric combustion is performed and the cylinder group in which the fuel supply suspending control is executed between the first cylinder group and the second cylinder group; the control apparatus further comprising: a first catalyst degradation degree estimating portion that estimates the degree of degradation of the first upstream catalyst; a second catalyst degradation degree estimating portion that estimates the degree of degradation of the second upstream catalyst; and a degradation degree comparing portion that compares the degree of degradation of the first upstream catalyst and the degree of degradation of the second upstream catalyst, wherein the stoichiometric combustion is performed in the cylinder group with the catalyst that the degradation degree comparing portion determines to have degraded to a higher degree.