EXHAUST EMISSION CONTROL SYSTEM OF LEAN COMBUSTION INTERNAL COMBUSTION ENGINE AND EXHAUST EMISSION CONTROL METHOD OF LEAN COMBUSTION INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device system of a lean combustion internal combustion engine which can reduce a flow-out amount of NOx into an atmosphere by purifying the NOx which is discharged from the lean combustion internal combustion engine without injecting urea water, and an exhaust emission control method of the lean combustion internal combustion engine.SOLUTION: Cylinders of a lean combustion internal combustion engine are classified into a first front part cylinder 20A and second group cylinders 20B, a first exhaust passage 24A connected to the first group cylinder and a second exhaust passage 24B connected to the second group cylinders are formed and merged with an exhaust passage 25, an exhaust gas G is made to pass a three-dimensional catalyst device 31 arranged in the first exhaust passage by stoichiometrically operating or rich-operating the first group cylinder while lean-operating the second group cylinders, ammonia is supplied to a selective reduction type catalyst device 32 which is arranged in the exhaust passage, and NOx from the second exhaust passage is reduced and purified by the selective reduction type catalyst device.SELECTED DRAWING: Figure 1