Patent ID: 8276367

Claim:
An exhaust gas control apparatus for an internal combustion engine, comprising: a three-way catalyst provided in an exhaust passage; a NO X storage-reduction catalyst provided in the exhaust passage downstream of the three-way catalyst; a rich controlling device that performs control to make an air-fuel ratio of exhaust gas from a combustion chamber of the internal combustion engine rich to reduce NO X stored in the NO X storage-reduction catalyst; and a control device that performs control to ensure that a NO X purifying component purifying the NO X is present in the NO X storage-reduction catalyst when reducing the NO X , the control device including an injection controlling device that injects at least one of urea, ammonia, or fuel into the exhaust passage to ensure that the NO X purifying component is present in the NO X storage-reduction catalyst, and the injection controlling device starts the injection a first predetermined period of time before a reducing agent produced by making the air-fuel ratio rich reaches the NO X storage-reduction catalyst.