高压共轨柴油机各缸不均匀性在线修正及其失火诊断

Online Correction and Misfire Diagnosis of Engine Cylinder Nonuniformity of High Pressure Common Rail Diesel

针对高压共轨柴油机运行时各缸间存在的差异,提出了一种基于每个工作循环瞬时角加速度的在线修正的方法.在一个循环中,计算出各缸工作后的瞬时角加速度的平均值,按各缸瞬时角加速度与平均值的差异的大小对喷油量进行修正,若修正油量超过了设定的阈值则进入失火诊断程序,并进行统计.在设定的循环次数中,超过阈值的概率大于一定值时,确认发生了失火,根据诊断电路,确定导致失火的原因.试验结果表明,在线修正后,发动机运行更加平稳柔和,并能快速准确地诊断出人为设定的失火故障.

To balance the difference between the cylinders of high pressure common rail diesel engine,a method of online correction based on the difference of instantaneous angle acceleration in a working cycle is presented. In a working cycle,the mean instantaneous rotate speed of individual cylinders after working is calculated. Then,the injection quantity is corrected according to the difference between the individual instantaneous angle acceleration in the next cycle. If the corrected injection quantity exceeds the threshold,the diagnose routines are enabled and numerate the time. If the probability exceeding the threshold in the given cycles is bigger than the threshold,misfire is affirmed,and the reason that lead to misfire is confirmed according to the diagnose circuit. The test results show that the engine runs more smoothly and softer after online correction,and the man-made misfire fault can be diagnosed quickly and exactly.