Exhaust purification device

An exhaust purification device comprising:

• an exhaust passage connected to a combustion chamber of an engine;
• a filter which is disposed in the exhaust passage, which is capable of collecting fine particles in exhaust gas, and to which a catalyst including an oxygen storage capacity (OSC) material is affixed;
• a secondary air supply passage connected to the exhaust passage upstream of the filter;
• a secondary air supply device configured to supply secondary air to the secondary air supply passage;
• a secondary air control valve disposed in the secondary air supply passage and configured to provide the secondary air with periodicity;
• and
• a controller electrically connected with the secondary air control valve, wherein the controller:
• controls the secondary air control valve so as to supply the secondary air with a predetermined frequency and a predetermined maximum amplitude of an oxygen concentration, and
• controls the secondary air control valve so that when the frequency of the secondary air is fixed to a value of greater than 0 Hz and less than or equal to 1.5 Hz, the maximum amplitude of the oxygen concentration is greater than 0.50% and less than or equal to 3.0%.