Soot content within a particle filter, especially for a diesel engine, is derived from mathematical formulae relating filter differential pressure to a gas flow value and relating value to intake air and fuel quantities

摘要

The soot content of a periodically regenerated particle filter is derived from mathematical formulae relating the filter differential pressure to a gas flow value and this value to the intake air and fuel quantities. Determination of the soot content of an i. c. engine particle filter, which is periodically regenerated by soot combustion before the content becomes too great, comprises deriving the soot content from the following mathematical formulae (I, II): DELTA P = cA + b (I) and A = (Mair + Mc)*T/P*N (II); where DELTA P is the differential pressure between the filter inlet and outlet sides, c is the soot content, b is a constant, A is the gas quantity passing through the filter, Mair is the intake air quantity, Mc is the fuel quantity, T is the exhaust gas temperature ahead of the filter, P is the exhaust gas pressure ahead of the filter and N is the engine speed. Independent claims are also included for the following: (i) equipment for carrying out the above process; and (ii) a vehicle provided with the above equipment. Preferred Features: The exhaust gas pressure (P) ahead of the filter is given by P = DELTA P + P0, where P0 is atmospheric pressure. The parameter 'c' is compared with a predetermined maximum value (cmax) and filter regeneration is initiated when the parameter 'c' is greater than this maximum value and when certain conditions of exhaust gas temperature, engine speed and fuel supply are met. Calculations are carried out at two separate measuring points, each of which is selected to provide two differential pressure values ( DELTA P) in non-overlapping regions of parameter 'A'. The time ( DELTA t), between the two measuring points, is measured and compared with a maximum limit, the soot content between the measuring points being assumed to be constant when DELTA t is less than the maximum limit.