Method and device for controlling spark-ignition direct injection engine

Abstract

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.

Description

technical field [0001] The invention relates to a control method of a spark ignition type direct injection engine and a spark ignition type direct injection engine. Background technique [0002] In order to improve the thermal efficiency of the engine and improve the fuel consumption, increasing the compression ratio is an effective means. However, if the geometric compression ratio of a spark ignition engine using gasoline or gasoline-containing fuel is set to a high compression ratio exceeding 12, knocking or pre-ignition is likely to occur in the low-speed side operating region of the high-load region of the engine. Abnormal combustion such as (preignition) (hereinafter, these abnormal combustions are simply collectively referred to as "knock"). As one of measures to suppress knocking, for example, there is a measure to greatly delay the ignition timing. [0003] For example, Japanese Patent Laid-Open Publication No. 2010-101312 describes a control method in which, in a...

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Problems solved by technology

[0004] However, the above-mentioned control method is expected to suppress knocking, but cannot secure a sufficiently high torque

That is, although high compression ratio engines have the potential to increase torque, conventional high compression ratio engines have not been able to achieve sufficient high torque due to knocking countermeasures.

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