A method and apparatus for reducing the amounts of exhaust gas of a multi-cylinder internal combustion engine and to achieve a rapid transition in the air - fuel - ratio of the internal combustion engine from lean to rich state

摘要

A regulator in the fuel system of a vehicle's internal combustion engine regulates the fuel pressure of a gaseous fuel, such as natural gas, to a fuel-air mixer. The regulator maintains a predetermined fuel pressure for idle and cruise conditions and increases fuel pressure to effect an enriching of the air-fuel ratio for full throttle conditions. The degree of enriching is sufficient to pass through a region where there is a threat of exhaust valve burning and where the maximum amount of the oxides of nitrogen are produced. The change in air-fuel ratio is extremely rapid to avoid operation for any material amount of time in this region. The regulator also effects a change from a rich air-fuel ratio to a lean one at a predetermined point in throttle setting below the point at which enriching occurs.