Patent ID: 7360356

Claim:
An exhaust gas purifying apparatus for an internal combustion engine, wherein the internal combustion engine includes: an even number of the cylinders; a catalyst, which purifies exhaust gas discharged from the cylinders; and an additive supplying device, which supplies an additive to the catalyst, the exhaust gas purifying apparatus comprising: determining means for determining whether the exhaust temperature of exhaust gas needs to be increased; and control means for selecting one of an all-cylinder operation in which all the cylinders are operated and a reduced-cylinder operation in which some of the cylinders are deactivated, and controlling the operation of the cylinders based on the selected operating condition, and when the control means determines that the exhaust temperature needs to be increased the control means selects the reduced-cylinder operation, wherein the control means includes: a first sub-control sections which controls the operation of a first cylinder group to which half of all the cylinders belong; a second sub-control section, which controls the operation of a second cylinder group to which the remaining cylinders belong; and a main control section, which selects one of the all-cylinder operation and the reduced-cylinder operation and controls the first sub-control section and the second subcontrol section based on the selected operating condition, wherein, when the reduced-cylinder operation is selected, the main control section performs normal control of one of the first and second sub-control sections, and performs transitional control of the other one of the first and second sub-control sections before stopping the normal control, and the transitional control is control for increasing the number of cylinders to be deactivated in the cylinder group controlled by the other one of the first and second sub-control sections.