Development On CNG Engine Electrical Control System

The research on clean alternative fuels tends to be an incrementally important discipline of engine techniques due to the shortage of the global petroleum resource and the serious air pollution problems. Especially, the Compressed Natural Gas (CNG) has being used extensively as a clean alternative fuel on engine. Thus, CNG engine will have extensive application for its high efficiency and low emission. In order to promote the development of the natural gas vehicle techniques in China, the research on the basal theory and the experiments on the electronic control CNG engine should be carried out.The following works has been fulfilled in the paper: development of CNG engine is summarized, electronic control system of CNG engine is schemed, a new type natural gas fueling system is developed, and electronic control unit, a high-energy grouping ignition system and idle control system are designed. Hardware and Software are included in this system, input module, output module, microprocessor (DSP) module; the program of embedded real time operation system (DSP/BIOS) was programmed on software.In the project the air-fuel ratio control strategy, which has affinity with power, cost, emission of engine, has been studied as important aspect. Closed loop strategy basing on switching oxygen sensor have been elaborated and simulated. Moreover, its characters have been analyzed from simulated result. It is operational. Using AFR closed loop control and simultaneous multiple injection, achieves the strict control of natural gas quantity and injection time of each cylinder. It makes homogeneous fuel mixture in each cylinder. Completing grouping ignition system controls the ignition advance angle and the opening time of the primary coil accurately. Based on fuzzy control, the idle speed is controlled in small range by the ISCV. Through the signals generator, a simulative test is completed. By analyzing the result datum, the signals of the injection and the ignition are accurate. The AFR is controlled in the near of 16.8. Through test in the CNG engine (YH465Q-1E), Some datum of the idle speed are sampled, and proof the correct of the electronic control system.At last, the shortages of this electronic control system are provided and improvement scheme and measure etc are given in this paper.