Internal combustion engine and method of operation

A method of operating an internal combustion engine having a plurality of sequentially operative combustion chambers, comprising the steps of:

• supplying a lean air-fuel charge to all of said combustion chambers when the engine power demand of said engine is lower than a first predetermined engine power demand level, the air-fuel ratio of said lean air-fuel charge being greater than 16;
• supplying a rich air-fuel charge to at least some of said combustion chambers substantially immediately after said engine power demand exceeds said first predetermined engine power demand level, the air-fuel ratio of said rich air-fuel charge being smaller than the stoichiometric air-fuel ratio, and supplying said lean air-fuel charge to the remaining combustion chambers;
• and
• converging exhaust gases of said combustion chambers.

An internal combustion engine, comprising:

• a plurality of sequentially operative combustion chambers;
• means connected to said combustion chambers for supplying thereto a lean air-fuel charge having an air-fuel ratio larger than 16;
• said supplying means supplying additional fuel to at least one of said combustion chambers relative to the quantity of sucked-in air by said one of said combustion chambers, as the engine power demand increases, in such a manner that an air-fuel charge richer than approximately stoichiometric is substantially immediately therein formed and that in a selected number of sequentially operative combustion operations of said combustion chambers the number of the combustion operations at which the combustion of said richer air-fuel charge is made is suitably selected to meet said engine power demand, said supplying additional fuel being made in the wide range of the engine speed of said engine including medium and high engine speeds;
• and
• means connected to said combustion chambers for converging the exhaust gases of said combustion chambers.

An internal combustion engine, comprising:

• a plurality of sequentially operative combution chambers;
• means connected to said combustion chambers for supplying a lean air-fuel charge to all of said combustion chambers when the engine power demand of said engine is lower than a first predetermined engine power demand level;
• said supplying means supplying a rich air-fuel charge to some of said combustion chambers and said lean air-fuel charge to the remaining combustion chambers, when said engine power demand exceeds said first predetermined engine power demand level;
• and
• means connected to said combustion chambers for converging the exhaust gases of said combustion chambers.