초록

An engine control computer estimates NO.sub.x trap temperature based on an estimated midbed temperature of a three-way catalytic converter located upstream from the trap and the effect on NO.sub.x trap temperature of introducing air into the exhaust upstream of the trap during purging of the trap.

대표청구항 ▼

[ What is claimed is:] [1.] A method of estimating the temperature of a NO.sub.x trap located in an exhaust passage of an engine downstream from a catalytic converter, said exhaust passage including a pierce point located between said converter and said trap permitting controlled amounts of air to b

[ What is claimed is:] [1.] A method of estimating the temperature of a NO.sub.x trap located in an exhaust passage of an engine downstream from a catalytic converter, said exhaust passage including a pierce point located between said converter and said trap permitting controlled amounts of air to be added to the exhaust passage from an air pump prior to entry into said trap, comprising a sequence of the steps of:calculating the instantaneous temperature at a first location upstream of said pierce point based on a previous instantaneous temperature value at said first location, an estimated steady-state value, and a predetermined temperature rate of change at said first location as a function of engine air mass flow;calculating the instantaneous temperature at a second location at the front face of the NO.sub.x trap based on a previous instantaneous temperature value at said second location, an estimated steady-state value at said second location based on the instantaneous temperature at said first location, and a predetermined temperature rate of change at said second location as a function of the sum of engine air mass flow and air pump air mass flow.