Development Of Portable ICE Fault Diagnosis System Using Crankshaft Angular Vibration Signals

Internal combustion engine (ICE) is a kind of complicated power machines to which common fault diagnosis methods are hardly applied. Angular vibration signals of crankshaft include abundant informations on operating state of ICE which leads to foreign and domestic attentions. At present, it is foreland and hot spot. The fault diagnosis devices have undergone four phrases that are traditional devices, electronic devices, intellectual devices and portable devices. The portable devices have the characteristics of small volume, low power loss, easy-carried in field, strong resistance against harsh environment, so it becames the new trend of development focused by designers.The paper used methods of multi-computer communication, COM port communication and program groupware combined with externally portable hardware to develop portable crankshaft torsional vibration measurement and diagnosis system (PTVM ) by C++ Builder software on the basis of torsional vibration measurement system (TVM). The system can be classified into two parts. One part is the external hardware and the other data processing software. Through data sampling, analysis and calculation, the fault diagnosis of ICE can be achieved. Applications verified that the system is of the reliability, correctness and applicability.The paper analyzed the property of torsional vibration mode in depth and synthesized the single order quasi-trapezia model existed extensively. It also presented a new monitoring method on operating state of single order angular vibration. According to the functional formulation that reflects the relation between angular vibration-amplitude , phase and torques of different cylinders, the order for condition monitor which satisfies single order quasi-trapezia model is induced by vector-composition. A new method is improved so dramatically that it doesn't need correct structural parameter of crankshafts and count on a great deal of experiments, and suitable to the cases where there has large torsional vibration in multi-cylinder engine. The simulation researches verify the usefulness of the method.The paper further develops and enriches the methods of ICE single order fault diagnosis in angular vibration of crankshaft. The portable system developed has engineering applicable values.