Engine fuel injection device and engine fuel injection method

Abstract

A fuel injection device for an engine includes a direct injector and an intake passage injector. When the engine load is relatively low, a fuel pressure lowering procedure is executed for lowering the pressure of fuel supplied to the direct injector. An ECU sets a fuel injection ratio, which is the ratio between the fuel injection amount of the direct injector and that of the intake passage injector, based on the engine operation state. The ECU changes the fuel injection ratio such that the ratio of the fuel injection amount of the direct injector to the total amount of the fuel fed to a combustion chamber is decreased, until the pressure of the fuel supplied to the direct injector is raised from the value lowered through the fuel pressure lowering procedure to a predetermined permissible value. This effectively suppresses hampering of the engine combustion, caused by the lowered fuel pressure.

Description

technical field [0001] The present invention relates to a fuel injection device and fuel injection method suitable for an internal combustion engine having a direct injector directly injecting fuel into a combustion chamber and a port injector injecting fuel into an intake port. Background technique [0002] Conventionally, as described in Japanese Laid-Open Patent Publication No. 2002-364409, there is a common fuel injection device capable of switching fuel injection modes. More particularly, the fuel injection device is used in an internal combustion engine having a direct injector injecting fuel directly into a combustion chamber and a port injector injecting fuel into an intake port. The fuel injector switches the fuel injection mode by selecting the operation of the direct injector or the port injector. [0003] Since the pressure inside the combustion chamber is relatively high, the fuel injection pressure (fuel pressure) of the direct injector injecting fuel into the...

AI Technical Summary

Problems solved by technology

However, this can cause a lag in fuel pressurization when the engine operation is switched from idle to, for example, a high load condition

In this case, the fuel will be under-pressurized, or not to the level required for a high-load engine operation

[0005] As mentioned above, if the actual fuel pressure cannot achieve the desired level, the fuel injected by the direct injector will not be sufficiently atomized

This hinders the combustion of fuel in an unfavorable manner, reduces engine torque, and worsens emissions performance

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