CONTROL METHOD FOR EXHAUST EMISSION CONTROL SYSTEM, AND EXHAUST EMISSION CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a control method for an exhaust emission control system, and an exhaust emission control system capable of reducing both black smoke and white smoke during unburned fuel supply control of supplying unburned fuel into exhaust gas in air-fuel ratio rich control carried out at regeneration of restoring purification capacity of an exhaust emission control device.

SOLUTION: The exhaust emission control system is composed to carry out the unburned fuel supply control by using post injection and not using direct injection into an exhaust pipe when an operating state of an internal combustion engine 10 is low load, to carry out the unburned fuel supply control by using both of the post injection and the direct injection in middle load, and to carry out the unburned fuel supply control by using the direct injection and not using the post injection in high load.

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