Patent ID: 8868317
Filing Date: 2014-10-21
Classification: F02D,G01N

Abstract:
1. A fuel injection amount control apparatus comprising: a three way catalyst which is disposed in an exhaust passage of a multi cylinder internal combustion engine and at a position downstream of an exhaust gas aggregated portion into which exhaust gases discharged from a plurality of cylinders of said engine merge; an air-fuel ratio sensor, which is disposed at a position between said exhaust gas aggregated portion and said three way catalyst, which includes an air-fuel ratio detection element, an exhaust-gas-side electrode layer and a reference-gas-side electrode layer that are formed so as to face to each other across said air-fuel ratio detection element, and a porous layer which covers said exhaust-gas-side electrode layer, and which outputs an output value corresponding to an amount of oxygen and an amount of unburnt substances that are contained in an exhaust gas that has reached said exhaust-gas-side electrode layer via said porous layer, said exhaust gas being included in an exhaust gas passing through said position at which said air-fuel ratio sensor is disposed; a plurality of fuel injection valves, each of which is configured so as to inject a fuel to be contained in a mixture supplied to each of combustion chambers of a plurality of said cylinders; an alcohol concentration obtaining section configured so as to obtain an alcohol concentration of said fuel; an air-fuel ratio imbalance indicating value obtaining section configured so as to obtain, based on a specific parameter, an air-fuel ratio imbalance indicating value which becomes larger as a degree of a non-uniformity among a plurality of said cylinders of cylinder-by-cylinder air-fuel ratios, each of which is an air-fuel ratio of said mixture supplied to each of said combustion chambers of a plurality of said cylinders; a first air-fuel ratio correlated parameter obtaining section configured so as to convert an actual output value of said air-fuel ratio sensor into an actual first air-fuel ratio correlated parameter based on said obtained actual alcohol concentration and said obtained actual air-fuel ratio imbalance indicating value, using a predetermined first relationship among an output value of said air-fuel ratio sensor, an alcohol concentration, an air-fuel ratio imbalance indicating value, and a first air-fuel ratio correlated parameter correlated to a true air-fuel ratio of an exhaust gas; an instructed fuel injection amount determining section configured so as to determine an instructed fuel injection amount which is an instruction value of an amount of said fuel to be injected from each of a plurality of said fuel injection valves, by performing a feedback correction on said amount of said fuel to be injected from each of said fuel injection valves in such a manner that said obtained actual first air-fuel ratio correlated parameter coincides with a predetermined target value; and an injection instruction signal supplying section configured so as to send an injection instruction signal to a plurality of said fuel injection valves in such a manner that each of a plurality of said fuel injection valves injects said fuel in an amount corresponding to said instructed fuel injection amount.