Fuel Vapor-Spray-Air Mixture Operation of a Spark-Ignition Engine

Abstract

A small quantity of light diesel oil injected into the combustion chamber of a spark-ignition engine running on a fuel vapor (propanej-air mixture was found to improve the engine performances for lean mixture ratios and to reduce the emissions of nitric oxide and carbon monoxide considerably. That is, the indicated horsepower (or indicated mean effective pressure) was increased by 6 to 16 per cent for a constant operating condition and a constant mixture ratio, while the region of stable operation was extended up to an extremely large overall air-fuel ratio wellgreater than twenty. Consequently, both the emission of nitric oxide and that of carbon monoxide were reduced simultaneously. The concentration of nitric oxide in the exhaust gas for the mean effective pressure of 5 kp/cm', for example, was reduced down to 200 ppm, ca. one tenth of the value obtained for propane-air operation without light oil injection, while the concentration of carbon monoxide was reduced down to ca. 0.08 per cent by volume.