Reduction of cold-start emissions and catalyst warm-up time with direct fuel injection

Abstract

An internal combustion engine employs fuel injectors positioned to inject fuel directly into combustion chambers of the engine, and an electronic engine controller (EEC) to control operation of the engine. The EEC implements a cold start routine which controls the amount of fuel injected, the time at which the fuel is injected and spark timing to achieve a rapid increase in temperature of the engine and the exhaust system components, thereby decreasing tailpipe hydrocarbon emissions during cold start.

Description

FIELD OF THE INVENTIONThis invention relates to the field of electronic engine control and more particularly to the field of reducing hydrocarbon emissions during cold start in a spark ignited internal combustion engine which employs direct fuel injection.BACKGROUND OF THE INVENTIONA disproportionately large amount of the hydrocarbons produced by a vehicle are emitted during cold starting of the vehicle engine. The temperature of the intake passages and the combustion chambers of the engine during the early stages of a cold start inhibit the proper vaporization of fuel. As a result, during cold start, a stoichiometric air / fuel ratio is difficult to achieve with intake port fuel injection. In addition, unburned fuel vapor is delivered to the catalytic converter together with the normal by-product of combustion. During the early stages of a cold start, the catalyst material in the catalytic converter has not reached a sufficient temperature in order to sufficiently process the unwante...

AI Technical Summary

Benefits of technology

It is an object of the present invention to reduce hydrocarbons produced during cold start of a spark ignited internal combustion engine by

Problems solved by technology

The temperature of the intake passages and the combustion chambers of the engine during the early stages of a cold start inhibit the proper vaporization of fuel.

As a result, during cold start, a stoichiometric air / fuel ratio is difficult to achieve with intake port fuel injection.

During the early stages of a cold start, the catalyst material in the catalytic converter has not reached a sufficient temperature in order to sufficiently process the unwanted, and uncombusted, by-products of combustion.

Unfortunately, use of the EHC adds additional cost, extra complexity, and requires a delay prior to engine starting to allow the EHC to preheat the catalyst.

However, Sasaki et al. do not contemplate reduction of hydrocarbon emissions by achieving immediate combustion as quickly as possible upon cold start.

Thus, the approach contemplated by Sasaki et al. has limited use in cold start of an engine.

Images