Patent ID: 9181843
Filing Date: 2015-11-10
Classification: F01N,Y02A,Y02T

Abstract:
1. A method of oxidizing nitrogen oxide, carbon monoxide, and unburned hydrocarbons in an exhaust stream of a vehicle diesel engine using a platinum-containing diesel oxidation catalyst (DOC) where the DOC is intended to simultaneously convert nitrogen monoxide (NO) to nitrogen dioxide (NO 2 ), carbon monoxide to carbon dioxide, and unburned hydrocarbons to carbon dioxide and water, the method comprising: flowing the exhaust stream from an exhaust manifold of the vehicle diesel engine through channels in an extruded ceramic monolith, the channels extending from an inlet to an outlet of the ceramic monolith and having channel walls carrying wash-coated films of particles of the platinum-containing diesel oxidation catalyst and oxidizing nitrogen oxide, carbon monoxide, and unburned hydrocarbons in the exhaust stream, the exhaust stream passing in contact with a temperature sensor at the inlet of the DOC coated channels and a temperature sensor at the outlet of the DOC coated channels, the inlet temperature sensor and the outlet temperature sensor being connected with a computer-based control system programmed for performance of this method; the method further comprising using the computer-based control system, while the exhaust stream is flowing through the DOC coated channels for oxidation of the nitrogen oxide, carbon monoxide, and unburned hydrocarbons, in: recording temperature values of the inlet temperature sensor and the outlet temperature sensor; determining the value of a temperature difference (ΔT) between the recorded exhaust gas inlet temperature of the DOC and the recorded exhaust gas outlet temperature of the DOC at a relatively high exhaust gas inlet temperature, which ΔT value may have a zero or non-zero magnitude; and, during the same occasion of engine operation, determining the value of ΔT between the recorded exhaust gas inlet temperature and the recorded exhaust gas outlet temperature of the DOC at a lower exhaust gas inlet temperature, which ΔT value may have a zero or non-zero magnitude; using the zero or non-zero magnitudes of the obtained values of ΔT as a measure of NO oxidation occurring in the DOC: periodically, during different occasions of engine operation, repeating the recordings and determinations of DOC inlet temperature values and DOC outlet temperature values, and their use in measuring NO oxidation occurring in the DOC: and when a non-zero value of ΔT at the higher DOC exhaust gas inlet temperature value and a zero value at the lower DOC exhaust gas inlet temperature are obtained, providing a notice in the vehicle that the DOC is not oxidizing NO to NO