Study On The Sensors' Fault Simulation System For Electronically Controlled Gasoline/CNG Flexible-fuel Engine

With the aggravating of energy crisis and environmental pollution, countries all over the world are formulating policies for seeking new energy. In this context, the new fuel automobile technology emerged, and was widely used all over the world. Because the CNG (compressed natural gas) automobile is one of the earliest and most mature new energy automobile, it has greatly been promoted in recent years. The power units of most CNG automobiles are modified by gasoline engines to gasoline/CNG flexible-fuel engines in China. With the development of science and technology, especially the development of engine electronic control technology, the control system of this new modified engine is becoming electronic control system. Although electronic control system is of low failure rate, the fault diagnosis is more difficult to the traditional control system. In brief, it is very necessary and urgent to study the fault diagnosis of electronically controlled gasoline/CNG flexible-fuel engine.Firstly, this paper introduces the working principle and control strategy of electronically controlled gasoline/CNG flexible-fuel engine, as well as the structures, signal characters and fault phenomenon of the sensors which work for the engine. Secondly, it designs the hardware of the managed circuit, the original/simulated hand-off circuit and the signal losing control circuit according to different characters of the sensor signals; PCI-6132 high-speed gathering card,PCI-6251 output card and the LabVIEW of the National Instruments Co. are used to simulating the fault signal of the sensors. At last, the feasibility of the system is verified by simulating the fuel gas pressure sensor's faults. The experiment results show that the fuel gas pressure sensor's faults have little influence on the performance of the engine in idling condition,and in common condition, the fuel gas pressure sensor's faults reduce the power, economy and increase the emissions of the engine clearly.Virtual instrument technology is combined with engine technology by the sensors'fault simulation system for electronically controlled gasoline/CNG flexible-fuel engine which is designed in the paper. This system not only can reappear the sensors'faults, but also can be extended to acquire, simulate and display the signals of other electric parts. This system can be used as a platform for the automotive serviceman, the researcher and the automotive allied student's study. It also can serve as a platform for researching fault diagnosis of the same kind of engines.