Cylinder wall fuel injection system for loop-scavenged, two-cycle

Abstract

A loop-scavenged, two-cycle internal combustion engine has a low-pressure, cylinder wall fuel injection system that is practical for multi-cylinder marine engines and also reduces the amount of unburned hydrocarbons in exhaust emissions when compared to conventional carbureted two-cycle engines. The fuel injectors are mounted through the cylinder wall so that fuel spray contacts the piston crown underneath a zone in which incoming air flow through the transfer ports converges. The converging air flow helps to convect vaporized fuel from the piston crown upwards towards the spark plug electrode in the combustion chamber and away from the exhaust port, thereby reducing the likelihood of short circuiting unburned fuel through the exhaust port before the exhaust port closes and compression begins. All fuel is injected into the piston cavity before the exhaust port closes. In a multi-cylinder engine, all of the fuel injectors are mounted to have parallel spray axes and coplanar top ends, thus allowing the use of a straight fuel rail and convenient mounting techniques. Low-pressure fuel (e.g., 40 to 100 psi) is provided to the fuel rail and to the fuel injectors, and operation of the fuel injectors is controlled by an electronic control unit. Two fuel injectors can be provided for each cylinder to provide additional fuel injection capabilities. Various systems are disclosed for supplying pressurized fuel to the fuel rail.