A Novel Concept for Mixture Preparation in Port Fuel Injected Engines

Every year, large numbers of two wheelers are sold in India and other Asian countries. A majority of these engines still tend to be carbureted due to cost and fuel quality issues. As an alternative to the carburetor, port fuel injectors (PFI) have started being introduced in the last few years for small two wheeler vehicles. Although PFI systems offer better metering of fuel and better transient response compared to carbureted systems, they are more expensive and require more power to pressurize the fuel. More importantly, wall film formation is observed in both the technologies, which reduces the effectiveness of the PFI system. Hence, a new technology is proposed which includes a PFI system along with an ultrasonic atomizer. The purpose of the proposed system is to improve the transient response and hence improve the fuel economy of gasoline engines and lower the emissions especially under cold conditions.

The proposed concept was tested standalone on a laboratory setup. A transparent duct of square section was fabricated and fuel was injected in it. High speed schlieren imaging was done to qualitatively visualize the vapor concentration in the proposed system compared to a conventional port fuel injection system. Mass measurement of the fuel atomized was done to quantitatively characterize the proposed system. The proposed system was found to be better than the existing conventional PFI system. It has metering capability like PFI with potentially better transient response at a similar cost.