Technical Paper
Study on Variable Injection Pattern Control System in a Spark Ignition Engine
1991-02-01
910080
Mixture formation technology for multipoint fuel injection systems in spark ignition engines has been reviewed regarding reduced exhaust emissions, fuel consumption and improved engine performance. In conventional systems, under light load conditions, the mixture of fuel to suction air is not uniform due to a short injection pulse width against a long duration of suction stroke. Under heavy load conditions, fuel spray is apt to be deflected by the air flow through the intake port and the injected fuel clings and remains onesidely on the cylinder wall during the combustion cycle. Under cold start conditions, the fuel on the intake manifolds and ports is not evaporated quickly enough so that it is evaporated in the cylinder after the temperature rises due to the compression stroke. A lot of fuel is injected to compensate for the small evaporation rate.