Emission control device for cylinder fuel injection engine

Abstract

An exhaust control system for a cylinder fuel injection engine having a cylinder injection injectors directly injecting a fuel into combustion chambers and a catalytic converter provided in an exhaust passage from said combustion chambers for purifying an exhaust gas, air / fuel ratio in the combustion chambers is periodically made rich for quicken activation of catalytic converter.

Description

[0001] The present application relates to subject matters described in application which will be filed around Feb. 28, 2001 by T. Shiraishi, T. Nogi, N. Tokuyasu, Y. Iiboshi and M. Oosuga and entitled "METHOD OF STARTING A CYLINDER INJECTION ENGINE" and assigned to the assignee of the present application. The disclosure of the above application is herein incorporated by reference.[0002] 1. Field of the Invention[0003] The present invention relates to an exhaust control system for a cylinder fuel injection engine. More particularly, the invention relates to an exhaust control system realizing early activation of a catalytic converter.[0004] 2. Description of the Related Art[0005] In general, an exhaust gas of an engine is purified by a catalytic converter. When the catalytic converter is not activated, such as upon starting up of the engine, the exhaust gas is discharged to the atmosphere with little purification. Therefore, in Japanese Patent Application Laid-Open No. 11-294220, as ...

AI Technical Summary

Benefits of technology

[0009] According to the second aspect of the invention, an exhaust control system includes a catalytic converter temperature measuring means for measuring a temperature of the catalytic converter for making a period to making the air / fuel ratio in the combustion chambers rich (rich period) longer when a temperature of the catalytic converter is lower than a predetermined value.

[0010] According to the third aspect of the invention, an exhaust control system includes a catalytic converter temperature measuring means for measuring a temperature of the catalytic converter for reducing fuel amount to be injected into the combustion chamber for reducing degree of making the mixture rich when a temperature of the catalytic converter is lower than a predetermined value.

[0018] Namely, in the present invention according to the first to third aspects, HC and CO discharged in the rich mixture operation is purified by oxygen discharged in the lean mixture operation, and the exhaust temperature will not be lowered since rich mixture operation is performed. Also, even when the catalytic converter temperature is low and this the reaction amount of the catalytic converter is small, discharge of HC and CO to the atmosphere without reaction can be successfully prevented. Also, when the temperature of the catalytic converter is high and thus HC and CO react, the temperature of the catalytic converter can be further elevated. In the fourth aspect of the present invention, utilizing heat (reaction heat) generated by reaction of CO on the catalytic converter, temperature of the catalytic converter can be elevated. Sixth to eighth aspects of the invention, since complicate torque compensation by the ignition timing control is not required. By auxiliary injection, even when temperature of the exhaust gas and the catalytic converter is low and reaction amount of the catalytic converter is small, discharge of HC and CO to the atmosphere without reaction can be successfully prevented. Also, when the temperature of the catalytic converter is high and thus HC and CO react, the temperature of the catalytic converter can be further elevated. In the ninth aspect of the invention, the catalytic converter can be activated by burring HC in the catalytic converter.

Problems solved by technology

However, since the invention disclosed in the above-identified Japanese Patent Application Laid-Open No. 11-294220 performs second injection immediately after starting up of the engine where temperatures of peripheral wall of the cylinder and a piston are low (after stopping a starter motor), fuel of the second injection injected toward the peripheral wall of the cylinder cannot be atomized sufficiently to degrade combustion to results in discharge of large amount of HC and CO.

On the other hand, a technology disclosed in the above-identified Japanese Patent Application Laid-Open No. 11-311139 does not disclose a method of exhaust gas purification before the temperature of the catalytic converter does not reach a temperature of 200.degree. C., at which HC is oxidized.

When the catalytic converter is arranged below a floor panel, it takes a long period for rising the catalytic temperature to results in discharging of large amount of HC and CO to the atmosphere.

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