Abstract: A compression ignition type engine comprising a combustion pressure sensor arranged in the combustion chamber, wherein whether defective combustion is occurring or not is judged from a change in the combustion pressure and the air-fuel ratio is made larger when it is judged that defective combustion is occurring.

Abstract: A compression ignition type engine, wherein a first combustion where the amount of the recirculated exhaust gas supplied to the combustion chamber is larger than the amount of recirculated exhaust gas where the amount of production of soot peaks and almost no soot is produced and a second combustion where the amount of recirculated exhaust gas supplied to the combustion chamber is smaller than the amount of recirculated exhaust gas where the amount of production of soot peaks are selectively switched between and where the second combustion is switched to the first combustion when the temperature of the catalyst arranged in an engine exhaust passage is about to fall below the activation temperature.

Abstract: An engine comprising an exhaust gas recirculation system, wherein a first combustion where the amount of the recirculated exhaust gas supplied to the combustion chamber is larger than the amount of recirculated exhaust gas where the amount of production of soot peaks and almost no soot is produced and a second combustion where the amount of recirculated exhaust gas supplied to the combustion chamber is smaller than the amount of recirculated exhaust gas where the amount of production of soot peaks are selectively switched. The exhaust gas recirculation rate is caused to be changed in a step-like manner when switching from the first combustion to the second combustion or from the second combustion to the first combustion.

Abstract: An internal combustion engine comprising an exhaust gas recirculation system, wherein the amount of EGR gas in the combustion chamber is made larger than the amount of EGR gas where the amount of soot produced peaks when the engine load is comparatively low so as to suppress the temperatures of the fuel and gas around the fuel at the time of combustion in the combustion chamber to a temperature lower than the temperature at which soot is produced. This prevents the production of soot and NOx in the combustion chamber.

Abstract: A compression ignition type engine, which switches between a first combustion where the amount of the inert gas in the combustion chamber is larger than the amount of inert gas where the amount of production of soot peaks and almost no soot is produced and a second combustion where the amount of inert gas in the combustion chamber is smaller than the amount of inert gas where the amount of production of soot peaks. The second combustion is provided instead of the first combustion when a catalyst is not activated.