Device and method for estimating catalytic temperature

A method of periodically estimating a temperature of an exhaust-gas purifying catalyst provided in an exhaust pipe of an internal combustion engine, comprising:

• a first step of estimating a steady catalytic temperature under a steady operation of said internal combustion engine, based on operating conditions of said internal combustion engine;
• a second step of estimating a representative temperature of an interior wall of said exhaust pipe extending from said internal combustion engine to said catalyst, based on said steady catalytic temperature estimated in said first step;
• a third step of estimating a catalyst inflow exhaust-gas temperature that flows in said catalyst, based on said steady catalytic temperature estimated in said first step and said representative temperature of an interior wall of said exhaust pipe estimated in said second step;
• and
• a fourth step of estimating the temperature of said catalyst based on said catalyst inflow exhaust-gas temperature estimated in said third step;
• wherein said first, second, third, and fourth steps are carried out in each cycle.

A method of periodically estimating a temperature of an exhaust-gas purifying catalyst provided in an exhaust pipe of an internal combustion engine, comprising the steps of:

• estimating a steady catalytic temperature under a steady operation of said internal combustion engine, based on operating conditions of said internal combustion engine;
• estimating a representative temperature of an interior wall of said exhaust pipe extending from said internal combustion engine to said catalyst, based on the estimated steady catalytic temperature;
• estimating a catalyst inflow exhaust-gas temperature that flows in said catalyst, based on the estimated steady catalytic temperature and the estimated representative temperature of an interior wall of said exhaust pipe;
• and
• estimating the temperature of said catalyst based on the estimated catalyst inflow exhaust-gas temperature;
• wherein said representative temperature of an interior wall of said exhaust pipe is estimated in consideration of the amount of heat of exhaust gases that is absorbed by the interior wall of the exhaust pipe, corresponding to an exhaust-gas flow quantity.