Controller for direct injection engine

Abstract

The present invention relates to a controller of a direct injecting type engine. When an engine is at starting or at cold state, a closing time of an exhaust valve is set before an intake top dead center to close the exhaust valve early. An exhaust residual gas is compressed by a cylinder to raise an inner cylinder temperature. A pre-fuel injection is performed from a time of closing the exhaust valve to a time of the intake top dead center in such a manner that the pre-injected fuel is combusted to raise the inner cylinder temperature. This increase in temperature expedites an atomization of fuel injected at a main fuel injection. A wet amount of fuel is reduced and HC emission is also reduced.

Description

technical field [0001] The present invention relates to a controller for a direct injection engine that injects fuel directly into cylinders. Background technique [0002] A direct injection engine was developed to improve fuel economy, reduce emissions and increase output. In such a direct injection engine, when the engine is started or cold (before warming up), the fuel injected into the cylinder is difficult to atomize and tends to stick to the inner surface of the cylinder or the upper surface of the piston. If these adhered fuels increase, the amount of fuel used for combustion decreases, so that the driving condition of the engine becomes unstable. The adhering fuel quantity is referred to below as the wet fuel quantity. [0003] When the engine is started or in a cold state, if the fuel injection amount is increased, more fuel is used for combustion, resulting in stable combustion. However, if the amount of fuel is increased, the amount of wet fuel is also increase...

AI Technical Summary

Problems solved by technology

Therefore, even if split injection is performed, the injected fuel cannot be well atomized and the amount of wet fuel cannot be effectively reduced, thus failing to sufficiently reduce the emission

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