Dynamic Surface Control of Engine Exhaust Hydrocarbons and Catalyst Temperature for Reduced Coldstart Emissions

Almost three quarters of the hydrocarbon (HC) emissions emitted by an automobile in a typical drive-cycle are produced during the first three minutes called the coldstart period. In this paper, we propose a way to decrease cold start emissions. A Model-Based paradigm is used to aid the generation of an efficient controller. The controller is built around a mean value engine model and a simplified catalyst model characterized by thermal dynamics, oxygen storage and efficiency curves. It is shown that the control of engine-out exhaust gas temperature for faster catalyst light-off could be detrimental to the catalyst. A control scheme comprising engine-out HC emissions control and catalyst temperature control through dynamic surface control is developed to reduce the tailpipe emissions. It is shown that reduced tailpipe emissions can be achieved without the risk of damaging the catalyst.