Control device for exhaust system

A control device applied to an exhaust system, comprising:

• a catalyst provided in an exhaust passage of an internal combustion engine and having sulfur components in exhaust gas adhered thereto, and releasing the adhered sulfur components by rich components in exhaust gas;
• and
• a gas sensor provided on a downstream side of the catalyst,
• wherein
• the gas sensor is configured as a limiting current sensor having a solid electrolyte, an exhaust side electrode provided on an exhaust side of the solid electrolyte, and a reference side electrode provided on a reference chamber side, and detects a specific gas component by causing a movement of oxygen ions in the solid electrolyte by applying a voltage to the exhaust side electrode and the reference side electrode;
• and
• the control device includes:
• a determination unit that determines whether an operating state of the internal combustion engine is a sulfur release state in which the sulfur component is released from the catalyst;
• and,
• a reaction suppression unit that performs a reaction suppression processing to suppress the reaction between oxygen and the sulfur component at the exhaust side electrode of the gas sensor when determined that the gas sensor is in the sulfur release state,
• the reaction suppression unit performs a process of stopping voltage application to the exhaust side electrode and the reference side electrode or a process of stopping voltage application to cause movement of oxygen ions from the reference side electrode to the exhaust side electrode as the reaction suppression processing.