Misfiring Control in Current Cycle at Engine Start Employing Ion Sensing Technology 2009-01-2713

In this paper a method of misfiring control in current cycle at engine start is presented. With this novel method, the high HC emissions of gasoline engine employed in traditional or hybrid electrical vehicles will be avoided. By the feedback of ion current signal, misfire phenomenon is identified within 30 degrees crank angle after spark plug ignited. Then, the ignition coil will be recharged and the plug sparked again to promote air fuel mixture oxidation and deplete the unburned hydrocarbon produces in exhaust gas. On the other hand, too late ignition will not always result in normal combustion, a kind of reaction similar with slow oxidation also occurs in such case. Hence, the oxidation process occurred in current cycle caused by reigniting of the spark plug will affect the combustion initial conditions of next cycle through the trapped residual gas Therefore, fuel injection amount of next combustion cycle will be adjusted according to the combustion status of current cycle which detected through ion current waveform. Accordingly, a set of pattern recognition algorithm and control strategy are designed to minimize the occurrence of misfire and to decrease the HC emissions during engine start process.