Study On Electronic Control System Of LPG/Diesel Fuel Proportioner And Applications In DI Diesel Engine

Liquefied petroleum gas (LPG) plays an important role in the area of substitute fuel of engine for its large amount, excellent exhaust emission and good economics. But, there are still many problems to use it in the diesel engine because its special physical and chemical characteristics. One key problem is the design of the fuel supply system. So that, explore a new way for LPG combustion process is very necessary. Through the mixing of diesel fuel and liquefied LPG in a certain pressure, the blend can directly inject into the cylinder of engine and realize the process of compression ignition, this can improvement fuel economics and emissions. Based on mixing diesel/LPG out of the engine and injecting mixed fuel directly in the cylinder, we took out a control method, designed an electronic control system to realize mixing diesel/LPG by ratio in liquid phase. This system controls the diesel/LPG flux by controling opening time of the solenoid valve, leting them mixed in a tank and then drived to the fuel injection pump. The engine runs as original way. This system solves the problem of how to mix diesel/LPG at arbitrary ratio in liquid phase and how to use LPG directly in a diesel engine, supplies a new way for using gas-phase fuels such as LPG in diesel engine. This work designed a complete control system, developed the main control board, compiled control codes and did experiments to test the system performance. The result shows, the control system can work stably at the mixing ratio range seted from the control board, and can set arbitrary mixing ratio depending on the needs of the engine at different loads, and also can supply high precise mixing ratio to satisfy the needs of direct injection on a diesel/LPG dual fuel engine. This work also did experiments on a diesel/LPG engine using this control system. The resule shows: The diesel engine can get the same power and fuel economy as pure diesel while using different mixing ratio of the hybrid fuel; While using the hybrid fuel, the soot emission reduced slightly, NOx emission reduced obviously, solved the contradiction of reducing soot and NOx simutaneously in conventional diesel engine; HC emission reduced obviously; The noise raised obviously.