Compression ignition type engine

A compression ignition type engine in which an amount of production of soot gradually increases and then peaks when an amount of inert gas in a combustion chamber increases and in which a further increase of the amount of inert gas in the combustion chamber results in a temperature of fuel and surrounding gas in the combustion chamber becoming lower than a temperature of production of soot and therefore almost no production of soot any longer, said engine comprising:

• an exhaust passage;
• an NOx absorbent arranged in said exhaust passage, said NOx absorbent absorbing NOx when an air-fuel ratio of inflowing exhaust gas is lean and releasing the absorbed NOx when the air-fuel ratio of the inflowing exhaust gas is rich or the stoichiometric air-fuel ratio;
• switching means for selectively switching 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 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;
• an electric motor for generating a vehicle drive power separate from a drive power of the engine;
• a battery for driving the electric motor;
• decision means for deciding if an amount of electrical energy stored in said battery is more than a predetermined amount;
• and
• control means for performing the first combustion, making the air-fuel ratio in the combustion chamber rich or the stoichiometric air-fuel ratio, and generating drive power at the electric motor even when the second combustion should be performed when NOx or SOx should be released from the NOx absorbent and the amount of electrical energy stored in the battery is more than the predetermined amount.