Control device for internal combustion engine for selecting operation to calculate target throttle opening degree based on prediction of temporary reduction in charging efficiency of fresh air in acceleration

Abstract

A control device predicts whether temporary reduction occurs to a charging efficiency of fresh air in an in-cylinder gas by an influence of an EGR rate of the in-cylinder gas, which increases later than increase of a charging efficiency of the in-cylinder gas, if a first arithmetic operation is applied to calculating a target throttle opening degree based on a target charging efficiency which is increasing, in a case of shifting to an acceleration operation, by using a prediction model expressing dynamic characteristics of an internal combustion engine. When it is predicted that temporary reduction occurs to the charging efficiency of the fresh air, the control device calculates the target throttle opening degree by a second arithmetic operation by which an increase speed of a throttle opening degree is restrained more than by the first arithmetic operation, instead of calculating the target throttle opening degree by the first arithmetic operation.

What is claimed is: 
     
       1. A control device for an internal combustion engine having a compressor disposed in an intake passage, a throttle disposed downstream from the compressor in the intake passage, and an EGR valve disposed in an EGR passage connecting an exhaust passage and an upstream side from the compressor in the intake passage, the control device configured to operate the throttle so as to increase a charging efficiency of an in-cylinder gas, and operate the EGR valve to increase an EGR rate of the in-cylinder gas, in an acceleration operation, the control device comprising:
 at least one processor; and 
 at least one memory including at least one computer program, the at least one memory and the at least one computer program configured to cause the at least one processor, in the acceleration operation, to
 increase a target charging efficiency in accordance with a magnitude of acceleration requested of the internal combustion engine, 
 calculate a target throttle opening degree based on the target charging efficiency, and select to calculate the target throttle opening degree by one of a first arithmetic operation, and a second arithmetic operation by which an increase speed of a throttle opening degree is restrained more than by the first arithmetic operation, and 
 predict, by using a prediction model expressing dynamic characteristics of the internal combustion engine, whether temporary reduction occurs to a charging efficiency of fresh air in the in-cylinder gas by and during an increase of the EGR rate of the in-cylinder gas after an increase of the charging efficiency of the in-cylinder gas when the first arithmetic operation is applied to calculation of the target throttle opening degree based on the target charging efficiency which is increasing, in a case of shifting to the acceleration operation, 
 
 wherein the at least one processor is caused to
 select to calculate the target throttle opening degree by the first arithmetic operation in response to a prediction that no temporary reduction occurs to the charging efficiency of the fresh air in the in-cylinder gas, and 
 select to calculate the target throttle opening degree by the second arithmetic operation in response to a prediction that temporary reduction occurs to the charging efficiency of the fresh air in the in-cylinder gas, and 
 
 wherein the at least one processor is caused to
 predict, by using the prediction model, an increase speed of the charging efficiency of the in-cylinder gas, and an increase speed of a charging efficiency of an EGR gas in the in-cylinder gas, that are obtained when the throttle is operated by using the target throttle opening degree calculated by the first arithmetic operation, and 
 compare the predicted increase speed of the charging efficiency of the in-cylinder gas with the predicted increase speed of the charging efficiency of the EGR gas in the in-cylinder gas, and determine that temporary reduction occurs to the charging efficiency of the fresh air in the in-cylinder gas when the predicted increase speed of the charging efficiency of the EGR gas in the in-cylinder gas is higher than the predicted increase speed of the charging efficiency of the in-cylinder gas. 
 
 
     
     
       2. The control device according to  claim 1 ,
 wherein the at least one processor is caused to
 in the first arithmetic operation, calculate a throttle opening degree for achieving the target charging efficiency as the target throttle opening degree, and 
 in the second arithmetic operation,
 acquire a target EGR rate, 
 calculate an estimated EGR rate of all gases passing through an intake valve, 
 correct the target charging efficiency by subtracting a charging efficiency corresponding to a difference between the target EGR rate and the estimated EGR rate from the target charging efficiency, and 
 calculate a throttle opening degree for achieving the corrected target charging efficiency as the target throttle opening degree. 
 
 
 
     
     
       3. The control device according to  claim 1 , wherein the at least one processor is caused, in the acceleration operation, to
 input into the prediction model
 an atmospheric pressure, 
 an opening degree of the EGR valve, and 
 a throttle opening degree calculated by using the first arithmetic operation for achieving the target charging efficiency, and 
 
 predict, by using (a) the prediction model, (b) the input atmospheric pressure, (c) the input opening degree of the EGR valve, and (d) the input throttle opening degree calculated by using the first arithmetic operation for achieving the target charging efficiency,
 a charging efficiency of the in-cylinder gas, and 
 a charging efficiency of an EGR gas in the in-cylinder gas, and 
 
 predict, by using (i) the predicted charging efficiency of the in-cylinder gas and (ii) the predicted charging efficiency of the EGR gas in the in-cylinder gas, whether temporary reduction occurs to the charging efficiency of the fresh air in the in-cylinder gas by and during the increase of the EGR rate of the in-cylinder gas after the increase of the charging efficiency of the in-cylinder gas.