CONTROL SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

The control system of the internal combustion engine comprises a control part controlling an air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst. The control part alternately sets a target air-fuel ratio between a rich air-fuel ratio and a lean air-fuel ratio and controls the air-fuel ratio of the exhaust gas so that an output air-fuel ratio of the air-fuel ratio sensor becomes the target air-fuel ratio. The control part corrects the output air-fuel ratio of the air-fuel ratio sensor so that when a scavenging occurs, the air-fuel ratio of the exhaust gas changes to a rich side more than an amount of deviation expected to occur in the output air-fuel ratio due to the occurrence of the scavenging. The control part increases a lean degree of the target air-fuel ratio when the scavenging occurs compared with when the scavenging does not occur.

主权项

1. A control system of an internal combustion engine controlling an internal combustion engine comprising
a variable valve timing mechanism able to change an amount of valve overlap between an intake valve and an exhaust valve, an exhaust purification catalyst arranged in an exhaust passage and able to store oxygen, and an upstream side air-fuel ratio sensor arranged at an upstream side of the exhaust purification catalyst in a direction of exhaust flow and detecting an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst, wherein the control system comprises a control part controlling an air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst, the control part alternately sets a target air-fuel ratio between a rich air-fuel ratio richer than a stoichiometric air-fuel ratio and a lean air-fuel ratio leaner than the stoichiometric air-fuel ratio and controls the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst so that an output air-fuel ratio of the upstream side air-fuel ratio sensor becomes the target air-fuel ratio, the control part corrects a parameter relating to the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst so that when an occurrence of valve overlap causes air to be blown from an intake passage through a cylinder to the exhaust passage as a scavenging action, the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst changes to a rich side more than an amount of deviation expected to occur in the output air-fuel ratio of the upstream side air-fuel ratio sensor due to the occurrence of the scavenging, and the control part increases a lean degree of the target air-fuel ratio when setting the target air-fuel ratio to the lean air-fuel ratio when the scavenging occurs compared with when the scavenging does not occur.