Patent attributes
An exhaust gas purifying apparatus for an internal combustion engine is provided. The apparatus includes a first group of cylinders; a second group of cylinders; an exhaust passage having a first branch passage connected to the first group of cylinders and a second branch passage connected to the second group of cylinders; a communication passage which connects the first branch passage and the second branch passage with each other; an exhaust gas purifying device provided in the exhaust passage and located downstream from a position connected to the communication passage; and an exhaust flow control device for controlling flow of exhaust gas such that exhaust gas emitted from one of the first group of cylinders and the second group of cylinders is introduced into the branch passage connected to the other group of cylinders through the communication passage when a predetermined exhaust flow switching condition is established, wherein a flow-passage cross section of the communication passage is smaller than those of the first branch passage and the second branch passage, and the communication passage is provided with a fuel addition valve for adding fuel to exhaust gas from upstream of the exhaust gas purifying device.
