| 摘要 |
The present invention relates to a method and a system for estimation of respective concentrations of nitrogen oxides NO x and concentrations of ammonia NH 3 in exhaust gases downstream from a catalyst (110), said estimation being based on a catalyst model and on a measured sensor signal ? sensor from a nitrogen oxide sensor which is so situated that it is placed in contact with said exhaust gases. According to the present invention, the measured sensor signal ? sensor is compared with an estimated signal which depends on at least two estimation functions and represents the catalyst model's match with said measured sensor signal ? sensor . This comparison is then used in determination of at least one deviation parameter for the respective said at least two estimation functions, where each said at least one deviation parameter describes a systematic deviation from reality for at least one input signal, one variable or one condition for said catalyst model. According to the invention an estimation is also made of the respective concentrations of nitrogen oxides NO x and ammonia NH 3 on the basis of the respective at least estimation functions and of said at least one deviation parameter. |
