High speed visualization of gasoline pump injector (GPI)

Abstract

[EN] Two-wheeler engines still use carburetor as a fuelling system in many Asian countries, owing to its low cost and less maintenance. The usage of carburetor to handle the upcoming stringent emission norms gets difficult, due to the absence of a closed-loop fuel correction. An electronic fuel injector (EFI), on the other hand, with the help of an electronic control unit (ECU), can correct the fuel quantity and set the air-fuel mixture close to stoichiometric, based on the feedback obtained from the oxygen sensor placed in the exhaust pipe. In this context, an innovative injection system has been developed, that can be applied for such electronic fuel injection in two-wheelers. In this design, the pump and injector are integrated into a single unit, making the system, simple, compact and less expensive. The integrated injector uses a solenoid and spring arrangement, for pressurizing the fuel in a small chamber, and the pressurized fuel is then injected through orifices to produce spray in the intake port. Two-wheeler engines can operate in the order of 10,000 rpm and it poses a big challenge in such injector designs, and therefore the time response of the mechanical and magnetic components of the injector become critical. High-speed back-lit imaging helps in understanding the time response of such injector, by visualizing the spray, while injecting continuously over a period of time. This paper presents the results of high-speed images, obtained from the spray of this new-concept gasoline pump injector (GPI). This exercise, demonstrated that this injector can work at a frequency as high as 83 Hz and also consistently. The spray pattern was found to be very unique and different from the conventional PFI injection sprays.