Research On The Spark Ignition Control Circuit Of Lean-& Fast-Burn Internal Combustion Engine

With the emission control regulations and the environmental protection being increasingly stricter and stem as well as the shortage of the oil resource, the present technology of internal combustion engine (ICE) faces more challenges than ever before. The air/fuel ratio can be increased and the fuel can be combusted more completely in the cylinder by applying the lean-burn technology on internal combustion engine. With this technology, the oil consumption and the emission of the deleterious matter can be effectively decreased. As the engine works under the lean-burn condition, the mixture in the cylinder becomes lean. Much more spark ignition energy should be supplied in order to ignite the lean mixture. In this project, an electric circuit board is designed and made to meet the requirement of the ICE's lean-burn ignition system which operates under the mode of superposed energy ignition. Further research on the ignition control of the lean-burn ICE can make use of the result in this project.The hardware of the lean-burn ICE's ignition control circuit designed for the ignition control requirement of the lean-burn ICE, based on the single-chip microcomputer (SCM) AT89S52 produced by the Atmel company. These circuits include the SCM's power circuit, the crystal oscillator and reset circuit, the I/O interface extended circuit, the keyboard circuit, the signal generator circuit, the anti-jamming circuit, the rotate speed display circuit the correlative drive circuit and so on. The circuit design strictly conforms to the rules for designing the printed-circuit board. Proper components and routing rules are selected to increase the operation reliability of the circuit board.The software of the ignition control circuit consists of two kinds of program design for the key-press and square-wave that trigger the control circuit to output ignition signal. The timing of the ignition circuit is accurately controlled by designing the right software. Modularized design is used for the software to increase the readability of the program. The whole software mainly includes the chip initial module, the delay module, the key-press identifying module, the rotate speed display module, the SCM's external interrupt module and the timer interrupt module. According to the ignition characteristic of lean-burn ICE, the software should distinguish the external signal trigger to definite the value of the important parameter in the program. Exact ignition signal wave, the frequency and the voltage value should be output under the corresponding trigger.The hardware of the ignition control circuit board and software are validated on the digital oscillograph. The external control signal is input either by key-press trigger or signal generator trigger. The output of the oscillograph is analysed and summarized on the condition of different rotate speed or frequency makes the board work. The experimental results show that the design of the ignition control circuit board and the software can accurately output ignition signal as well as its frequency. The wave meets the requirement of superposed energy ignition.The ignition control system not only preciously makes the time of ignition circuit under control, but also adapts wide range of rotate speed. The ignition control system can be reliably used not only for the general spark ignition engines but for the high rotate speed engines.