CONTROL DEVICE FOR COMPRESSION SELF-IGNITION TYPE ENGINE

PROBLEM TO BE SOLVED: To provide a control device for a compression self-ignition type engine which performs SI-CI combustion, for appropriately controlling both a SI rate and a self-ignition timing.SOLUTION: A compression self-ignition type engine 1 performs SI combustion, namely, the combustion of air-fuel mixture with its flame propagation by the ignition of a spark plug 25, and CI combustion, namely, the combustion of the air-fuel mixture with its self-ignition resulting from the flame propagation. An ECU 10 includes first control means for controlling an SI rate as a parameter related to the rate of a heat quantity generated in the SI combustion to a total heat quantity generated in the SI combustion and the CI combustion or a heat quantity generated in the CI combustion on the basis of the operating condition of the engine 1, and second control means for controlling a self-ignition timing for the CI combustion. Both the first and second control means are used for changing the combustion states of both the SI combustion and the CI combustion during one combustion cycle of the engine 1 according to the operating condition of the engine 1.SELECTED DRAWING: Figure 7 【課題】ＳＩ−ＣＩ燃焼を行う圧縮自己着火式エンジンの制御装置において、ＳＩ率及び自己着火時期の両方を適切に制御する。【解決手段】圧縮自己着火式のエンジン１においては、点火プラグ２５の点火により混合気が火炎伝播により燃焼するＳＩ燃焼と、この火炎伝播に起因して混合気が自己着火により燃焼するＣＩ燃焼とが行われる。ＥＣＵ１０は、エンジン１の運転状態に基づき、ＳＩ燃焼及びＣＩ燃焼において発生する全熱量又はＣＩ燃焼において発生する熱量に対してＳＩ燃焼により発生する熱量の割合に関連する指標としてのＳＩ率を制御する第１制御手段と、ＣＩ燃焼の自己着火時期を制御する第２制御手段とを備え、これら第１及び第２制御手段の両方によって、エンジン１の１燃焼サイクル中においてＳＩ燃焼及びＣＩ燃焼の両方の燃焼状態をエンジン１の運転状態に応じて変更する。【選択図】図７