An Indirect On-line Measurement Method of Crankshaft Clearance Based on Simulation Vibration Signal

Monitoring the clearance size between the connecting rod big end bearing shell and the crankshaft, and grasping the health status of the equipment operation are of great significance to realize the prediction and maintenance of reciprocating compressor. If the clearance is too small, the friction will be too large and even stuck when the bearing shell and the crankshaft are moving relatively. Conversely, if the clearance is too big, it will not only affect the motion accuracy of the mechanism but also aggravate bearing shell wear, and even cause serious faults or accidents. However, the crankshaft clearance is difficult to be measured directly during the compressor running due to the influence of complex mechanical structure. Aim at this problem, an indirect on-line measurement method of crankshaft clearance based on simulation vibration signal is proposed in this paper. In this method, the dynamic simulation of the running process of the reciprocating compressor motion pair in ideal state is realized by using the virtual prototyping technology. The simulation results show that the shock of the crosshead decreases first and then increases with the increase of the clearance size, and there is a clearance range that makes the equipment run relatively smoothly. According to the simulation results, the mapping relation model of crankshaft clearance size and simulation vibration signal is set up, and the indirect measurement of the crankshaft clearance is realized by the comparison of the actual acquisition vibration signal and the model. This method provides a new idea and method for the diagnosis of reciprocating compressor crankshaft clearance fault.