Effect of directed port air flow on liquid fuel transport in a port fuel injected spark ignition engine

Abstract

With highly efficient modem catalysts, startup HC emissions have become a significant portion of the trip total. Liquid fuel is a major source of HC emissions during the cold start and fast idle period. Thus the control of liquid fuel, particularly during startup, is required for future engine designs. The effect of a turbulence plate, or charge motion control valve, on the port liquid fuel mass is examined. A purging process was used to examine the effect of a charge motion control plate on the port fuel film mass. It was found that the charge motion plate can provide substantial reductions in both the total and downstream intake fuel film mass. These reductions are the result of the increased intake turbulence that results from the charge motion plate. This increased turbulence provides enhanced fuel - air mixing and increases port film strip atomization due to the increased viscous shear. The effect of different film locations was postulated and backed experimentally. The downstream and valve films have the most immediate effect on the fuel delivery. Large upstream films, which can take thousands of cycles to develop, influence the fuel delivery on a much longer time scale.

(cont.) In-cylinder hydrocarbon measurements were made. Despite the high level of scatter in the measurements, similar transient responses were observed for both CMCV open and closed. This similarity despite different film masses was attributed to different t and x values.