High Speed Fuel Injection System for 2-Stroke D.I. Gasoline Engine

Two-stroke gasoline engines are known to benefit from using in-cylinder fuel injection which improves their ability to meet the strict fuel economy and exhaust emissions requirements. A conventional method of in-cylinder fuel injection involves application of plunger-type positive displacement pumps. Two-stroke engines are usually smaller and lighter than their 4-stroke counterparts of equal power and need a pump that should also be small and light and, preferably, simple in construction. Because a 2-stroke engine fires every crankshaft revolution, its fuel injection pump must run at crankshaft speed (twice the speed of a 4-stroke engine pump).

An electronically controlled fuel injection system has been designed to satisfy the needs of a small automotive 2-stroke engine capable of running at speeds of up to 6000 rpm. The fuel flow to individual engine cylinders is controlled by solenoid valves capable of one cycle response and individual cylinder adjustment of injection quantity and timing. The design and operating principles of the pump and injectors are described, and the test results of cylinder-to-cylinder distribution, cycle-to-cycle variability and fuel atomization as well as testing methods are discussed.