Patent ID: 6363313
Filing Date: 2002-03-26
Classification: F02D,G01N

Abstract:
A fuel property detecting system for an internal combustion engine, comprising:a fuel injector installed to the engine and injecting a quantity of fuel to the engine; an air-fuel sensor installed to an exhaust passage of the engine and detecting an exhaust air-fuel ratio; and a control unit coupled to said fuel injector and said air-fuel sensor, said control unit being arranged to calculate the quantity of fuel injected from said fuel injector according to an operating condition of the engine, to command said fuel injector to inject the calculated quantity of fuel, to sample data of a response wave-form of the exhaust air-fuel ratio in response to the injected quantity of fuel at a transient period, to identify a plant model as to fuel in use by controlling a parameter of a previously constructed plant model on the basis of the sampled data so as to decrease a prediction error between the plant model and a norm model, to calculate a cutoff frequency of the identified plant model, and to estimate a fuel property of the fuel in use from the calculated cutoff frequency of the identified plant model and data previous stored in said control unit.