Patent attributes
An engine exhaust gas purifier includes: an injection controller allowing a fuel injection valve to inject fuel near the top dead center on each compression stroke; an EGR amount controller for controlling the amount of exhaust gas recirculated into a combustion chamber; an excess air ratio controller for controlling the excess air ratio so that the local equivalence ratio in a late combustion stage is lower than the equivalence ratio at which soot is produced; and an intake air temperature controller for controlling the temperature of intake air after being mixed with exhaust gas. The intake air temperature controller controls the temperature of intake air within a temperature range lower than an upper temperature limit below which a predetermined ignition delay time can be secured and higher than a lower temperature limit above which the production of HC and CO can be avoided.
