Abstract: In a combustion control apparatus of a direct-injection diesel engine, in which a fuel is injected at an early timing with an EGR ratio more than a first predetermined value at pre-mixed combustion area (H) where an engine load is relatively low so as to provide a pre-mixed combustion mode, while a diesel combustion mode is provided with the EGR ratio less than a second predetermined value at diffusion combustion area (D), when the operation of the engine 1 transfers from one of the pre-mixed combustion area (H) and the diffusion combustion area (D) to the other thereof, an opening of the an EGR valve 35 is changed and thereby a fuel injection mode is changed after an actual EGR ratio: EGR becomes a predetermined value: EGR1. When the EGR ratio: EGR is within a certain range (SB5→SB13→SB15), a follow-up injection (latter-injection) is executed (SB15, SB7) so that combustion thereby may begin at the timing when the main-combustion beginning at around TDC completes mostly.

Abstract: To optimize an ignition timing of premixture for improving fuel efficiency regardless of significant change in an EGR ratio or a fluctuation in temperature of recirculated exhaust gas and temperature in a combustion chamber, there is provided a control apparatus for a diesel engine which controls an injector extending into the combustion chamber to execute a main-injection for injecting fuel and increasing the EGR ratio, so as to attain the premixed compressive ignition combustion while the engine is in the premixed combustion region on the low load side. Just before or after a cool flame reaction occurs in the mixture formed by the main-injection, an auxiliary-injection is executed so that the latent heat of vaporization of the fuel decreases the temperature of the mixture to delay the ignition to a timing near TDC. The auxiliary-injection amount is adjusted according to the estimated value of EGR ratio or the change in the crank angular velocity to optimize the ignition timing of the mixture.

Abstract: To suppress deposition of fuel injected at an early timing on a wall surface for preventing the degradation in fuel efficiency and increase in the amount of harmful components in an exhaust gas, in a direct-injection diesel engine which controls the injector to cause a combustion configuration dominated by the compressive ignition of the premixture while the engine is in the premixed combustion region defined on a low load side. When fuel is injected at an early timing to form the premixture, at least one of the pulse width to be inputted into the injector and the fuel pressure is or are adjusted according to the change in the injection timing, and corrected according to the intake air temperature or the intake pressure. If an allowable pulse width is insufficient to inject fuel in the amount corresponding to a target torque, fuel is injected in a divided manner.

Abstract: In a combustion control apparatus of a direct-injection diesel engine, in which a fuel is injected at an early timing with an EGR ratio more than a first predetermined value at pre-mixed combustion area (H) where an engine load is relatively low so as to provide a pre-mixed combustion mode, while a diesel combustion mode is provided with the EGR ratio less than a second predetermined value at diffusion combustion area (D), when the operation of the engine 1 transfers from one of the pre-mixed combustion area (H) and the diffusion combustion area (D) to the other thereof, an opening of the an EGR valve 35 is changed and thereby a fuel injection mode is changed after an actual EGR ratio: EGR becomes a predetermined value: EGR1. When the EGR ratio: EGR is within a certain range (SB5→SB13→SB15), a follow-up injection (latter-injection) is executed (SB15, SB7) so that combustion thereby may begin at the timing when the main-combustion beginning at around TDC completes mostly.

Abstract: An exhaust gas purification system having a catalyst for removing nitrogen oxides from exhaust gas causes the temperature range of activation of the catalyst to shift toward the higher temperature side when the degree of oxidation of the catalyst becomes pronounced.