Internal combustion engine internal EGR volume constructing apparatus and method

Abstract

An electronic control unit of an internal combustion engine computes a remaining combusted gas amount Megr1, which exists in a cylinder immediately before an intake valve is opened, based on an intake pipe pressure Pm, an engine speed NE, and an intake valve opening timing Topen. At the same time, the control unit computes a backflow combusted gas amount Megr2, which is the amount of combusted gas that flows back into the cylinder from an exhaust pipe after the intake valve is opened, based on the intake pipe pressure Pm, the engine speed NE and a valve overlap amount OL. The control unit computes the sum of the remaining combusted gas amount Megr1 and the backflow combusted gas amount Megr2, and sets the sum as an estimated internal EGR amount MegrALL. As a result, the internal EGR amount is readily and accurately estimated.

Description

technical field [0001] The present invention relates to an apparatus and method for estimating (estimating) the exhaust gas recirculation amount in an internal combustion engine (internal combustion engine), that is, the internal EGR (integral EGR) amount of the internal combustion engine. Background technique [0002] Some of the burned gases in a typical internal combustion engine remain in the cylinders. The remaining burned gases are called internal EGR (internal exhaust gas recirculation). Since internal EGR affects the combustion state and emissions of the engine, the amount of internal EGR is estimated, and the intake air amount, ignition timing, fuel injection amount, and fuel injection timing are adjusted based on the estimation. In an internal combustion engine having a variable valve timing (drive) mechanism, the amount of exhaust gas returned to the cylinder from the exhaust system varies with, for example, the amount of valve overlap. The amount of internal EG...

AI Technical Summary

Problems solved by technology

This presumption logic is applied to a variable valve timing mechanism (variable valve timing) with high control flexibility, such as independently controlling the valve timing (valve timing, valve timing) of each intake valve and exhaust valve. Gas phase device) is particularly complex when the engine

If the presumption logic is complex, the number of required parameters and the number of corrections based on these parameters increase

Therefore, errors in parameters and corrections are accumulated, resulting in a decrease in the estimation accuracy of the internal EGR amount

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