Method and device for controlling spark-ignition direct injection engine

摘要

A method for controlling an engine includes, when the engine is operating within a particular range with comparatively low engine speed and high load, setting an effective compression ratio of 10:1 or above, retarding ignition timing by a predetermined amount and retarding the ignition timing within a first, relatively low engine speed range more than within a second, higher engine speed range, setting an injection mode of an injection valve to divided injections performed at least twice in a period from an intake stroke to an earlier-half stage of a compression stroke, performing, within the first engine speed range, a final injection in the earlier-half stage of the compression stroke, and performing, within the second engine speed range, the final injection in a late stage of the intake stroke and at least one injection other than the final injection in a middle stage of the intake stroke.

主权项

1. A method for controlling a spark-ignition direct injection engine, comprising:
setting an effective compression ratio to be 10:1 or above, when an operating state of an engine body having a cylinder in which a geometric compression ratio is set to 12:1 or above is within a particular operating range where an engine speed is comparatively low and a load is high; retarding a spark ignition timing for a gas mixture inside the cylinder by a predetermined amount with respect to an MBT within the particular operating range, and setting a retarding amount of the spark ignition timing within a first engine speed range of the particular operating range, where the engine speed is relatively low, to be larger than a retarding amount of the spark ignition timing within a second engine speed range, where the engine speed is higher than the first engine speed range; setting an injection mode of a fuel injection valve for directly injecting fuel into the cylinder to divided injections in which the injection is performed at least twice in a period from an intake stroke to an earlier-half stage of a compression stroke within the particular operating range; performing a final injection of the divided injections in the earlier-half stage of the compression stroke, when the engine speed is within the first engine speed range of the particular operating range; and performing a final injection of the divided injections in a late stage of the intake stroke and at least one injection other than the final injection in a middle stage of the intake stroke, when the engine speed is within the second engine speed range of the particular operating range, wherein the middle stage of the intake stroke is a period within which an intake air flow velocity is the fastest, and is bordered by an early stage and a late stage of the intake stroke.