Method of and apparatus for controlling air-fuel mixtures into a multi-cylinder internal combustion engine

An apparatus for controlling an air-fuel mixture for an internal combustion engine, comprising

• first means for alternatively forming a relatively rich air-fuel mixture having an air-fuel ratio lower than a predetermined air-fuel ratio and a relatively lean air-fuel mixture having an air-fuel ratio higher than said predetermined air-fuel ratio for a first combustion chamber of said engine,
• second means for alternatively forming said relatively rich and lean air-fuel mixtures for a second combustion chamber of said engine,
• third means alternatively connected to said first and second means and causing each of said first and second means, which are connected to said third means, to form said lean air-fuel mixture,
• fourth means alternatively connected to said first and second means so that, when said third means is connected to one of said first and second means, said fourth means is connected to the other of said first and second means, and causing each of said first and second means, which are connected to said fourth means, to form said rich air-fuel mixture,
• fifth means for generating an output signal in response to the lapse of a suitable time, and
• switching-over means connected to said fifth means to receive said output signal thereof and switching over connection of said third means from one of said first and second means to the other of said first and second means and connection of said fourth means from said other means to said one means in response to said output signal of said fifth means.

A combination of an internal combustion engine and an apparatus for controlling an air-fuel mixture for said engine, said engine including

• a first group of combustion chambers and
• a second group of combustion chambers, said apparatus comprising
• first means combined with said first group of combustion chambers and for alternatively forming a relatively rich air-fuel mixture having an air-fuel ratio lower than a predetermined air-fuel ratio and a relatively lean air-fuel mixture having an air-fuel ratio higher than said predetermined air-fuel ratio for said first group of combustion chambers,
• second means combined with said second group of combustion chambers and for alternatively forming said rich and lean air-fuel mixtures for said second group of combustion chambers,
• third means alternatively connected to said first and second means and causing each of said first and second means, which are connected to said third means, to form said lean air-fuel mixture,
• fourth means alternatively connected to said first and second means so that, when said third means is connected to one of said first and second means, said fourth means is connected to the other of said first and second means, and causing each of said first and second means, which are connected to said fourth means, to form said rich air-fuel mixture,
• fifth means for generating an output signal in response to the lapse of a suitable time, and
• switching-over means connected to said fifth means to receive said output signal thereof and switching over connection of said third means from one of said first and second means to the other of said first and second means and connection of said fourth means from said other means to said one means in response to said output signal of said fifth means.

An apparatus for controlling an air-fuel mixture for an internal combustion engine, comprising

• a first fuel injection valve for alternatively feeding fuel for forming a relatively rich air-fuel mixture having an air-fuel ratio lower than a predetermined air-fuel ratio and fuel for forming a relatively lean air-fuel mixture having an air-fuel ratio higher than said predetermined air-fuel ratio for a first combustion chamber of said engine,
• a second fuel injection valve for alternatively feeding fuel for forming said rich air-fuel mixture and fuel for forming said lean air-fuel mixture for a second combustion chamber of said engine,
• a first pulse generator alternatively connected to said first and second fuel injection valves and generating a first pulse signal having a pulse width which causes said fuel injection valve, connected to said first pulse generator, to inject fuel for forming said lean air-fuel mixture,
• a second pulse generator alternatively connected to said first and second fuel injection valves so that, when said first pulse generator is connected to one of said first and second fuel injection valves, said second pulse generator is connected to the other fuel injection valve and generating a second pulse signal having a pulse width which is broader than said pulse width of said first pulse signal and which causes said fuel injection valve, connected to said second pulse generator, to inject fuel for forming said rich air-fuel mixture,
• first means for generating an output signal in response to the lapse of a suitable time, and
• switching-over means connected to said first means to receive said output signal thereof and switching over connection of said first pulse generator from one of said first and second fuel injection valves to the other fuel injection valve and connection of said second pulse generator from said other fuel injection valve to said one fuel injection valve in response to said output signal of said first means.

A combination of an internal combustion engine and an apparatus for controlling an air-fuel mixture for said engine, said engine including

• a first group of combustion chambers and
• a second group of combustion chambers and the number of which is equal to the number of said first group of combustion chambers, said apparatus comprising
• a first group of fuel injection valves combined respectively with said first group of combustion chambers and each of which alternatively injects fuel for forming a relatively rich air-fuel mixture having an air-fuel ratio lower than a predetermined air-fuel ratio and fuel for forming a relatively lean air-fuel mixture having an air-fuel ratio higher than said predetermined air-fuel ratio for the corresponding combustion chamber,
• a second group of fuel injection valves combined respectively with said second group of combustion chambers and each of which alternatively injects fuel for forming said rich air-fuel mixture and fuel for forming said lean air-fuel mixture for the corresponding combustion chamber,
• a first pulse generator alternatively connected to said first and second groups of fuel injection valves and generating a first pulse signal having a pulse width which causes said group of fuel injection valves, connected to said first pulse generator, to inject fuel for forming said lean air-fuel mixture,
• a second pulse generator alternatively connected to said first and second groups of fuel injection valves so that, when said first pulse generator is connected to one of said first and second groups of fuel injection valves, said second pulse generator is connected to the other group of fuel injection valves and generating a second pulse signal having a pulse width which is broader than said pulse width of said first pulse signal and which causes said group of fuel injection valves, connected to said second pulse generator, to inject fuel for forming said rich air-fuel mixture,
• control means for controlling said pulse widths of said first and second pulse signals in accordance with the load of said engine,
• first means for generating an output signal in response to the lapse of a suitable time, and
• switching-over means connected to said first means to receive said output signal thereof and switching over connection of said first pulse generator from one of said first and second groups of fuel injection valves to the other group of fuel injection valves and connection of said second pulse generator from said other group of fuel injection valves to said one group of fuel injection valves in response to said output signal of said first means.