Patent ID: 9181845
Filing Date: 2015-11-10
Classification: F01N,Y02T

Abstract:
1. A method for determining nitrogen dioxide content at an inlet of a selective catalytic reduction device of an exhaust system of an internal combustion engine, wherein the exhaust system comprises: a gas exhaust pipe, a tank for a reducing agent, an injector that injects the reducing agent into the exhaust pipe, a first sensor that measures a concentration of nitrogen oxides in the exhaust pipe, and a second sensor that measures the concentration of nitrogen oxides in the exhaust pipe, wherein the tank, injector, and first sensor are located upstream of the selective catalytic reduction device, and the second sensor is located downstream of the selective catalytic reduction device; said method comprising: halting an injection of reducing agent into the exhaust pipe, measuring the concentration of nitrogen oxides present in the exhaust pipe upstream and downstream of the selective catalytic reduction device during a period of time, determining the amount of nitrogen dioxide accumulated in the selective catalytic reduction device during said period of time from the change in the concentration of nitrogen oxides measured upstream and downstream of the selective catalytic reduction device by calculating the difference in concentration of nitrogen oxides between the upstream and the downstream of the selective catalytic reduction device which corresponds to the storage of the nitrogen dioxide in said selective catalytic reduction device, and determining the nitrogen dioxide content upstream of the selective catalytic reduction device from the determined amount of nitrogen dioxide accumulated per unit of time.