Design Of CNG Electronic-controlled System For Dual-fuel Engine And Research Of CAN-bus Communication

Natural gas vehicle has a better low-emission and economy, the development of the vehicle has become an important step in the strategic steps of energy saving and environmental protection. Dual-fuel natural gas engines is the most common way which in Gasoline engines are converted into natural gas engines, with lower emissions, as well as the good performance of continuous running. Technology of CAN bus has been widely used in automotive electronic control, design of CAN bus of engine ECU could ensure that the engine ECU into a vehicle control.Based on PIC18F2420 single chip, a sequential multi-port fuel injection system for the gasoline/CNG dual fuel engines is designed. By optimizing the structure of the software, combined with the method of piecewise linear interpolation to find MAP, the response speed is improved, and a precise control of CNG injection pulse is achieved. By adopting a free timer interruption control module, the control problem, the overlap of multi-cylinder engine injection signal, is solved. The use of the closed-loop control of CNG injection pulse width to ensure the reasonable precision gas injection; Some programs of the misfire protection, sliding switch, and the width-pulse control of sharp acceleration and deceleration, all these functions designed in the system ensure the engine stability under varying working conditions. By the running test, the design system shows a better dynamic and passes the emission standard EURO III.We designed the computer background management software for testing dug, the software can communicate with single chip and support visualized display. The function of the software is real-time display, data playback, expert setting, debug single-cylinder fire and so on, thus, they have a great assistance for the work such as observing the engine working condition, calibrating the MAP.At last we use PIC18F448 single chip to research the integrated CAN-bus communication module, and we achieved the hardware circuit design and procedures. The CAN module can be used as an independent CAN nodes use, which is easy to migrate to CNG engine's ECU in the future, and also it could be the base for the CNG ECU into the vehicle control ECU communication system.