Injector control logic for a liquid-phase liquid petroleum gas injection engine

Fuel in a liquid-phase liquefied petroleum gas (LPG) injection engine is difficult to meter finitely because of LPG fuel characteristics such as flash boiling and variations in fuel composition, injection pressure and density. This study presents an injector control logic for a liquid-phase LPG injection engine; the control logic was developed through a series of experiments. A procedure was conceived using a gas analyser to calibrate the injection quantity promptly and precisely. Injectors are calibrated with four fuel compositions under various temperatures and injection pressures. A mathematical flowrate model is developed on the basis of the calibration data. This model is converted into an injector control logic, which is finally programmed into an electronic control unit (ECU). The verification experiment showed that the logic could precisely control the air-fuel ratio, regardless of fuel composition, fuel temperature and injection pressure.