Study On Electronic Controlled LPG Fueled Engine And Its Direct Injection Technology

The LPG-fueled engine is modified and optimized using electronic controlled fuel injection technology; the comparison of engine performance with direct injection, intake liquid injection and gas injection has been done. The air fuel ratio, ignition timing and injection timing of the engine has been optimized and calibrated. In order to solve the problem of power losses and to improve the fuel economy & the emission level, the research purpose of this paper is using GDI technology on LPG-fueled engines; and the engines can satisfy the demand of modem vehicles.The research content and conclusion involved in this paper are as follows.Many kinds of fuel supply systems made by the lab are introduced. The direct injection system is using hydraulic pressure boost method, and the pressure range is from 2MPa to 12MPa. The system has others virtues, such as wide fuel adaptability, little fluctuation of pressure, good seal performance, etc. The injector of direct injection is assembled from electronic controlled valve and diesel injector, and it is used in the experiment. The research of LPG spray characteristics is done, and the result of calculation shows that the 3MPa injection pressure can satisfy the demand of direct injection.The control strategy of engine has been studied. The CMAC (Cerebellar Model Articulation Controller) is used on electronic controlled LPG fuelled engine's optimizing, it is involved that the air fuel ratio and ignition timing. It is used on the experimental research of idle speed fluctuation, and the effect is notable.The hardware and software of electronic controlled system such as ECU, sensor circuit, injection circuit and ignition circuit are introduced. The control structure of twin chip and using share RAM are advanced; and it is good at real time and interference killing feature.The high energy and multi-times ignition system of notable feature based on ECU controlled is developed. The relation between multi-times ignition or ignition timing and engine's performance is found through the experiment. The experiment can improve the emission level of HC, CO, ignition reliability, and reduce the idle speed fluctuation.The flexible developing system of electronic controlled system of LPG fueled engine was developed. It is involved data collection, calibration and optimization, and it attains the aim of intelligence and generalization. ECU developing uses this system can improve the efficiencyand reduce the cost.The performance of LPG fueled engine at different condition was studied. The relation between engine performance and air fuel ratio, ignition timing or injection timing is found through the experiment. The engine experiment shows that the power output of intake liquid injection or direct injection is not less than .original engine, and its emission is lower. The emission of HC, CO of gaseous injection is lowest, intake liquid injection is second, and direct injection is third.