Field of the Disclosure
The present disclosure relates to a control device for an internal combustion engine that estimates an intake valve flow rate based on an estimated value or a measured value of an intake pipe pressure using an intake valve model equation in which an intake valve flow rate is represented by a linear expression that adopts an intake pipe pressure as a variable.
Background Art
As described in JP2007-211747A, an intake valve flow rate that is a flow rate of air that passes through an intake valve and enters a cylinder can be represented by a linear expression that adopts an intake pipe pressure that is a pressure in a space from a throttle to the intake valve as a variable. This linear expression is referred to as an “intake valve model equation” (model calculation equation of an intake valve model). Coefficients (specifically, a slope and an intercept) of the intake valve model equation are determined by adaptation for respective operating conditions that are assumed. However, in some cases, due to manufacturing errors in components of an internal combustion engine or to aged deterioration thereof, a deviation can arise between a relation between an intake pipe pressure and an intake valve flow rate that is assumed in the intake valve model equation and the actual relation therebetween. Such a deviation lowers the estimation accuracy for the intake valve flow rate.
In JP2007-211747A, a technique is disclosed for correcting coefficients of the intake valve model equation based on a comparison between measured values of operation parameters that are measured during operation of an internal combustion engine and estimated values of operation parameters that are calculated using the intake valve model equation. According to the aforementioned technique, correction of coefficients of the intake valve model equation is performed in operating region units that are defined based on the opening timing of the intake valve and the engine speed, and the corrected coefficients are stored as learned values for each operating region. If the coefficients of the intake valve model equation can be made appropriate, a decrease in the estimation accuracy with respect to the intake valve flow rate due to manufacturing errors in components of an internal combustion engine or to aged deterioration thereof can be suppressed.
JP2007-211751A also shows the state of the art at the date of filing of this application.