Exhaust gas heating method

Abstract

A method according to the present invention of heating exhaust gas to be introduced into an exhaust gas purifying device from an internal combustion engine by heating and igniting fuel supplied into an exhaust passage from a fuel supply valve includes the steps of determining a necessity for supplying fuel into the exhaust passage, setting an amount of fuel to be supplied into the exhaust passage from the fuel supply valve, the amount being set when it is judged in the determining step that fuel needs to be supplied into the exhaust passage, checking an operating state of the engine, and controlling an air-fuel ratio of exhaust gas such that the air-fuel ratio falls within an area where amounts of both smoke and HC to be generated in the exhaust gas are low in the operating state of the engine checked in the checking step.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a national phase application of International Application No. PCT / JP2012 / 000006, filed Jan. 4, 2012, the content of which is incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to a method of heating exhaust gas to be introduced into an exhaust gas purifying device by supplying fuel into an exhaust passage from a fuel supply valve disposed upstream of the exhaust gas purifying device in an exhaust pipe, and then by heating and igniting the fuel.BACKGROUND ART[0003]In recent years, coping with strict emission standards set on internal combustion engines has lead to a necessity for facilitating the activation of an exhaust gas purifying device at the start of its internal combustion engine, maintaining its active state during the operation of the internal combustion engine, and so on. In this respect, Japanese Patent Laid-Open No. 2010-084710 and the like have proposed internal combustion ...

AI Technical Summary

Benefits of technology

The present invention controls the air-fuel ratio of exhaust gas released into the exhaust passage from the combustion chamber of an internal combustion engine when fuel is supplied into the exhaust passage. This helps to reduce the generation of smoke and HC (hydrocarbons) while also suppressing the release of unburned fuel. By controlling the air-fuel ratio of the exhaust gas, the invention allows for accurate control over the combustion process, even when the flow rate of the exhaust gas varies. The fuel injection amount, throttle valve opening degree, and EGR control valve opening degree can be adjusted to control the air-fuel ratio of the exhaust gas. Additionally, the amount of unburned fuel can be minimized by correcting the fuel injection amount based on the air-fuel ratio of the exhaust gas. The method also includes a step of correcting the fuel injection amount based on the air-fuel ratio of the exhaust gas during regeneration of the DPF, which reduces fuel consumption and improves the burnability of PM.

Problems solved by technology

Hence, the fuel supplied into the exhaust passage from the fuel supply valve and the exhaust gas may fail to be mixed sufficiently, leading to incomplete combustion of the ignited fuel in some cases.

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