New Index for Diagnosis of Abnormal Combustion Using a Crankshaft Position Sensor in a Diesel Engine 2019-01-0720
Most of internal combustion engine research focus on improving fuel economy and reducing gas emission to satisfy regulations and marketability. Engine combustion is a key factor to determine engine performance. Generally, engine operating parameters are optimized for the best performance and less emission. However, abnormal combustion makes engine conditions far away from optimized operation. An abnormal combustion including misfire can happen in various causes such as superannuated vehicles, extreme change of driving environment and so on. Abnormal combustion causes serious deterioration of not only on NVH but also on fuel economy and gas emission. Especially, misfire violates vehicle comfortability. Abnormal combustion at one cylinder breaks exciting force balance between cylinders and makes unexpected vibration. Controlling and diagnosis for engine combustion quality are essential technology to maintain best performance of engine.
Combustion characteristics effect on angular velocity and acceleration of crankshaft instantaneously. There have been many methods and studies to evaluate combustion quality or stability using crankshaft position sensor. In this paper, a newly developed index related with combustion characteristics is used to evaluate combustion quality. Abnormal combustion is defined as partial burning and misfiring in this paper, which the conditions are generated by retarding main injection timing individually only at one cylinder. Also, order analysis of vibration at engine was conducted to evaluate a correlation between vibration deterioration and a new index. A new index that facilitates real-time calculations can contribute to the diagnosis of abnormal combustion and assessment of combustion quality. Furthermore, it can contribute to estimate the vibration deterioration from crankshaft position sensor with further study.