Patent ID: 6883310

Claim:
An engine emission control apparatus comprising: split passages that divide an exhaust gas discharged from an engine into a plurality of streams, the exhaust gas flowing simultaneously into the split passages; emission control catalysts provided individually in the split passages, and that remove a component present in the exhaust gas at a high removal rate if a temperature of the exhaust gas that inflows via the split passages satisfies a predetermined temperature condition; a heat dissipater that varies amounts of heat released from the exhaust gas in paths of the split passages from a branch point to the emission control catalysts; and a controller that changes proportions of amounts of flow of the exhaust gas into the split passages so that the predetermined temperature condition is satisfied in at least one of the split Passages, wherein: the controller changes the proportions of the amounts of flow of the exhaust gas into the split passages based on a temperature of the exhaust gas upstream of the branch point of the split passages, and if the temperature of the exhaust gas that flows to the branch point does not satisfy the predetermined temperature condition of one of the emission control catalysts, and the temperatures of inflows of the exhaust gas to one of the emission control catalysts and to another emission control catalyst can be controlled by a flow control of the controller so as to satisfy the predetermined temperature condition, the controller changes the proportions of the amounts of flow of the exhaust gas into the split passages so as to increase the amount of flow of the exhaust gas into a split passage of greater heat release.