Patent ID: 8051833

Claim:
A throttle valve control apparatus of an internal combustion engine having a first cylinder group, a second cylinder group, a first throttle valve arranged in an intake passage of the first cylinder group and a second throttle valve arranged in an intake passage of the second cylinder group, the throttle valve control apparatus comprising: a controller that, when there is a demand to switch a combustion air-fuel ratio of the internal combustion engine without changing engine output, first changes an opening amount of the first throttle valve, and then changes an opening amount of the second throttle valve, wherein: the internal combustion engine further includes: a first three way catalytic device arranged in an exhaust passage of the first cylinder group, a second three way catalytic device arranged in an exhaust passage of the second cylinder group, and a NOX storage catalytic device arranged in a common exhaust passage of the first cylinder group and the second cylinder group downstream of the first three way catalytic device and the second three way catalytic device, and when there is a demand to switch the combustion air-fuel ratio of the internal combustion engine from a lean air-fuel ratio to a rich air-fuel ratio without changing the engine output, the controller first reduces the opening amount of the first throttle valve to switch a combustion air-fuel ratio of the first cylinder group from the lean air-fuel ratio to the rich air-fuel ratio, and then reduces the opening amount of the second throttle valve to switch a combustion air-fuel ratio of the second cylinder group from the lean air-fuel ratio to the rich air-fuel ratio when or just before exhaust gas of the rich air-fuel ratio flows out from the first three way catalytic device.