Control unit of internal combustion engine

摘要

The present invention relates to a control unit of an internal combustion engine capable of performing a coordinate control of an exhaust gas recirculation (hereinafter abbreviated as “EGR”) gas supply amount by an EGR apparatus and a supercharging amount by a supercharger provided with a variable flow mechanism. The control unit comprises: a state quantity estimation section for calculating an in-cylinder oxygen excess ratio based on an operating state of the internal combustion engine; and a switching part for switching the respective opening degree commands for the EGR valve and the variable flow mechanism of the supercharger so that the opening degree of the EGR valve and the opening degree of the variable flow mechanism become smaller than in a normal state when the internal combustion engine is determined to be in the transient state based on the calculated in-cylinder oxygen excess ratio.

主权项

1. A control unit of an internal combustion engine comprising:
one or more processing devices receiving instructions to perform: an exhaust gas recirculation (EGR) control step sending an EGR command signal so as to bring an EGR gas supply amount by an EGR apparatus to a target EGR gas supply amount to control an opening degree of an EGR valve; a supercharger control step sending a supercharging command signal so as to bring a supercharging amount of a supercharger provided with a variable flow mechanism to a target supercharging amount to control an opening degree of the variable flow mechanism; an in-cylinder oxygen excess ratio calculation step calculating an in-cylinder oxygen excess ratio based on an operating state of the internal combustion engine; a transient state determination step determining whether the internal combustion engine is in a transient state based on the in-cylinder oxygen excess ratio in the cylinder calculated by the in-cylinder oxygen excess ratio calculation step; and a switching step switching the EGR command signal and the supercharging command signal so that the opening degree of the EGR valve and the opening degree of the variable flow mechanism become smaller than in a normal state when the internal combustion engine is determined to be in the transient state by the transient state determination step; wherein the transient state determination step comprises:
a first determination step determining whether the in-cylinder oxygen excess ratio calculated by the in-cylinder oxygen excess ratio calculation step is not greater than a first threshold value; anda second determination step determining whether an in-cylinder oxygen excess ratio difference between the in-cylinder oxygen excess ratio calculated by the in-cylinder oxygen excess ratio calculation step and an optimum value of the in-cylinder oxygen excess ratio which is preliminarily set on the basis of the operating state of the internal combustion engine is not less than a second threshold value, and; wherein the transient state determining step determines the internal combustion engine to be in the transient state when the first determination step determines that the in-cylinder oxygen excess ratio is not greater than the first threshold value and the second determination step determines that the in-cylinder oxygen excess ratio difference is not less than the second threshold value, such that the switching step switches the EGR command signal and the supercharging command signal to reduce the opening degree of the EGR valve and the opening degree of the variable flow mechanism than in the normal state to reduce emission amount of nitrogen oxides (NOx) and smoke (PM).