INTERNAL COMBUSTION ENGINE

摘要

The internal combustion engine has an ammonia feeder which feeds ammonia to a combustion chamber and an NOx selective reduction catalyst which is arranged in an engine exhaust passage. The removal rate of the NOx selective reduction catalyst depends on a ratio of concentration of ammonia to NOx of the exhaust which flows into the NOx selective reduction catalyst, that is, a ratio of concentration of inflow. A high removal rate range where the NOx removal rate in the NOx selective reduction catalyst becomes substantially maximum and, furthermore, the ammonia removal rate becomes substantially maximum, is set in advance. The internal combustion engine is controlled so that the ratio of concentration of inflow becomes inside the high removal rate range.

主权项

1. An internal combustion engine provided with
an ammonia feeder which feeds ammonia to a combustion chamber and an NOx selective reduction catalyst which is arranged in an engine exhaust passage and which selectively reduces NOx by a feed of a reducing agent comprised of ammonia, wherein the NOx selective reduction catalyst has a NOx removal rate and an ammonia removal rate which depend on a ratio of concentration of ammonia to NOx of an exhaust which flows into the NOx selective reduction catalyst, defined as a ratio of concentration of inflow, a high removal rate range of the ratio of concentration of inflow where the NOx removal rate in the NOx selective reduction catalyst becomes substantially maximum and, furthermore, the ammonia removal rate becomes substantially maximum is set in advance, and the internal combustion engine estimates the ratio of concentration of inflow and controls the ratio of concentration of inflow so that the ratio of concentration of inflow is maintained inside the high removal rate range.