A Study on Dynamic Response and Diagnosis Method of the Wear on Connecting Rod Bush

Wear is a typical failure form for mechanical parts of a reciprocating compressor. The clearance of a connecting rod bearing will exceed the normal value due to the wear caused by poor lubrication or abnormal loads. Wear on the small-end bush of a connecting rod (SEBCR) in a reciprocating compressor is still a hard work to be monitored and diagnosed. In this paper, we focus on the study of the dynamic response and diagnosis method on wear fault of SEBCR based on the dynamic simulation and vibration signal analysis. A rigid-flexible coupling model of a connecting rod has been built, and the connecting rod is treated as a flexible body. The clearance between the crosshead pin and the small-end bush of a connecting rod is taken into account. The simulation results show that abnormal clearance will affect the dynamic characteristic significantly, and high acceleration impacts will occur at the reversal points of the crosshead pin. Based on the dynamic response and signal feature extraction, a new diagnosis method calculating the amplitude and change rate of average vibration energy per crank angle to detect the wear fault is proposed. The experiment results on a reciprocating compressor show that the vibration of the compressor crosshead is consistent with numerical simulation results, and the method is capable of detecting the wear fault in real time. Research presented in this paper is significant in providing tools for diagnosing wear fault of reciprocating compressors.