Estimating of the mean temperature of the combustion chamber of an i.c. engine

摘要

A method of estimating the mean temperature of the combustion chamber of an i.c engine, e.g a direct injection common rail diesel engine with pilot, pre-, main, after and post injections, comprises: (a) experimentally creating a parameter map in which the value of an engine operation parameter influencing the temperature of the combustion chamber is measured as a function of engine speed and engine load; (b) experimentally creating a temperature map in which the expected temperature is measured in function of engine speed and engine load; (c) experimentally changing the value of the operation parameter and measuring the actual temperature for each couple of values of engine speed and engine load of the parameter map; (d) creating a function F(changed parameter value,expected parameter value) for each couple of values of engine speed and engine load of the parameter map associating the changed parameter value with the value of a parameter stored in the parameter map; (e) creating a correction map in which for each couple of values of the engine load, or engine speed, and of the function F corresponds a correction parameter value expression of the variation of the expected temperature to the variation of the parameter, and (f) using the correction parameter values of said correction maps to determine an estimation of the combustion chamber temperature given by the temperature map in function of the engine speed and of the engine load.