Methods for low emission, controlled temperature combustion in engines which utilize late direct cylinder injection of fuel

Abstract

The presentinvention provides a method for close control and adjustment of incylinder oxygen concentration levels together with boost adjustments in such a way as to minimize harmful emissions during transients in engines which utilize late direct cylinder injection of fuel. In this invention, EGR flow rates are adjusted by means of an EGR control valve in a closed loop, linked fashion together with boost pressure changes during transients, to maintain intake charge-air oxygen concentration and boost levels within critical ranges for controlled temperature, low emission combustion. Furthermore, in order to minimize harmful emissions during rapid transient changes in operating conditions, changes in fuel feed into the cylinder are made to wait for or follow changes in the boost level of charge-air into the cylinder for combustion. This addresses a problem in diesel engines, during acceleration, of having temporary fuel levels in excess of desired fuel / oxygen ratios during transients, with the result of increased PM levels from insufficient oxygen for rapid, complete combustion. In this invention, temporary fuel levels do not exceed desired fuel / oxygen ratios during transients, by means of controlling fuel feed responsive to the level of boost of charge-air being taken into the cylinder for combustion.

Description

[0001] Cross References to Related Applications [0002] This application is a continuation-in-part of US Patent Application No. 10 / 214,229 filed August 8, 2002, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates to a method of controlling the combustion process in an engine utilizing post direct cylinder injection of fuel, such as a diesel engine, to reduce harmful emissions produced therein. For ease of illustration, this application may at times refer simply to diesel engines, however, the scope of the present invention is equally applicable to other engines utilizing post-fuel direct cylinder injection. Background technique [0004] Internal combustion engines utilizing post direct cylinder injection of fuel, such as conventional diesel engines, emit harmful pollutants such as oxides of nitrogen (NOx) and particulate matter (PM) well in excess of acceptable ambient levels. However, because of their high comb...

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Problems solved by technology

However, Beck's '076 patent neither controls the concentration level of oxygen nor discusses any connection between EGR regulation and boost regulation to increase or decrease sequentially or in concert with each other, nor does it discuss or consider the effects of EGR flow and The relationship between the mass of the intake air and the air / fuel mass ratio to be adjusted

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