クロスヘッド軸受の焼付き発生防止のための異常振動検知に関する研究

抄録

The crosshead bearing in large two-stroke diesel engines operates under severe lubrication conditions because hydrodynamic action is limited by low-amplitude, low-velocity oscillation under high specific load. The recent trend toward more compact engines with increased output raises the bearing specific load, thereby significantly increasing the lubrication severity. Therefore it is very important to find a means of preventing seizure of the crosshead bearing. In this study we evaluated a technique for monitoring abnormal vibration using a dynamically loaded bearing seizure test rig capable of simulating load patterns and relative oscillations of the crosshead bearing in actual engines. Vibration spikes occur around the crank angles of ±90 degrees where the oscillating speed is zero during each cycle. When the lubrication severity increases, an abnormal vibration spike caused by severe metal-to-metal contact is frequently generated at a crank angle of approximately 90 degrees, where the oil film thickness reaches a minimum. If running-in is properly carried out immediately after detection of the abnormal vibration, the bearing surface is conformed, thereby eliminating the severe metal-to-metal contact. This monitoring technique for abnormal vibration can be an effective means of preventing seizure of the crosshead bearing.