Exhaust emission control device of an internal combustion engine

摘要

As forcible modulation parameters, a cycle and an amplitude are set so that O₂ and CO concentrations in emissions at a catalyst inlet can be increased, and based upon the preset parameters, forcible modulation that forcibly fluctuates an exhaust air-fuel ratio is carried out to facilitate catalysis for early activation, and the forcible modulation is then switched to O₂-F/B control.