Patent ID: 8720190

Claim:
An exhaust system comprising: an engine having a first injector injecting a fuel into a combustion chamber; an exhaust pipe through which an exhaust gas generated at the engine flows; a second injector mounted at the exhaust pipe and injecting a reducing agent; a DeNOx catalyst mounted at the exhaust pipe downstream of the second injector and reducing SOx or nitrogen oxides (NOx) or both contained in the exhaust gas by using the reducing agent injected by the second injector; and a controller electrically connecting the first injector, the second injector and the DeNox catalyst, and predicting a SOx amount stored at the DeNOx catalyst and a SOx amount removed from the DeNOx catalyst according to a driving state of the engine; wherein the controller calculates a mass flow of SOx poisoned at the DeNOx catalyst based on a mass flow of SOx in the exhaust gas, a volume speed of the exhaust gas passing through the DeNOx catalyst, a temperature of the DeNOx catalyst, and a currently stored SOx amount, and calculates a mass flow of SOx released from the DeNOx catalyst based on a lambda of an inlet of the DeNOx catalyst, an actual mass flow of the reducing agent, an engine speed, a current fuel injection amount, a lambda of an outlet of the DeNOx catalyst, the currently stored Sox amount, and the temperature of the DeNOx catalyst.