The failure rate of crankpin bearing bush of diesel engine under complex working conditions such as high temperature,dynamic load and variable speed is high.After serious wear,it is easy to deteriorate the stress stat...The failure rate of crankpin bearing bush of diesel engine under complex working conditions such as high temperature,dynamic load and variable speed is high.After serious wear,it is easy to deteriorate the stress state of connecting rod body and connecting rod bolt,resulting in serious accidents such as connecting rod fracture and body damage.Based on the mixed lubrication characteristics of connecting rod big endbearing shell of diesel engine under high explosion pressure impact load,an improved mixed lubrication mechanism model is established,which considers the influence of viscoelastic micro deformation of bearing bush material,integrates the full film lubrication model and dry friction model,couples dynamic equation of connecting rod.Then the actual lubrication state of big end bearing shell is simulated numerically.Further,the correctness of the theoretical research results is verified by fault simulation experiments.The results show that the high-frequency impact signal with fixed angle domain characteristics will be generated after the serious wear of bearing bush and the deterioration of lubrication state.The fault feature capture and alarm can be realized through the condition monitoring system,which can be applied to the fault monitoring of connecting rod bearing bush of diesel engine in the future.展开更多
Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engin...Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engine) does not always operate in rated operating condition and its operating condition changes constantly. In this paper, a fourstroke four-cylinder engine is taken as the studying object, the load and lubrication of connecting-rod and main bearing in di erent operating conditions are analyzed. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all main bearings are calculated by the whole crankshaft beam-element finite element method, and the lubrication performance of connecting-rod and main bearings are analyzed by the dynamic method. The results show that there are major di erences in the changes and numerical value at corresponding moment of the loads and lubrication performance of connecting-rod and main bearings in an engine operating cycle in di erent engine operating conditions; the most unfavorable case of the lubrication performance of connectingrod and main bearings may not take place in the rated engine operating condition. There are also major di erences between the lubrication performance of connecting-rod bearing and that of main bearing and between the lubrication performances of main bearings one another. Therefore, it will not be reasonable that the lubrication performance of a certain connecting-rod bearing or main bearing is analyzed in the design of the engine bearing. It is necessary to analyze simultaneously the lubrication performances of all bearings in di erent engine operating conditions.展开更多
基金Supported by the National Natural Science Foundation of China(No.52101343)the Aeronautical Science Foundation(No.201834S9002).
文摘The failure rate of crankpin bearing bush of diesel engine under complex working conditions such as high temperature,dynamic load and variable speed is high.After serious wear,it is easy to deteriorate the stress state of connecting rod body and connecting rod bolt,resulting in serious accidents such as connecting rod fracture and body damage.Based on the mixed lubrication characteristics of connecting rod big endbearing shell of diesel engine under high explosion pressure impact load,an improved mixed lubrication mechanism model is established,which considers the influence of viscoelastic micro deformation of bearing bush material,integrates the full film lubrication model and dry friction model,couples dynamic equation of connecting rod.Then the actual lubrication state of big end bearing shell is simulated numerically.Further,the correctness of the theoretical research results is verified by fault simulation experiments.The results show that the high-frequency impact signal with fixed angle domain characteristics will be generated after the serious wear of bearing bush and the deterioration of lubrication state.The fault feature capture and alarm can be realized through the condition monitoring system,which can be applied to the fault monitoring of connecting rod bearing bush of diesel engine in the future.
基金Supported by Science Fund of State Key Laboratory of Engine Reliability of China(Grant No.skler-201708)National Natural Science Foundation of China(Grant No.51490660/51490661)
文摘Only the lubrication performance at rated engine operating condition was generally analyzed in current design and research of engine connecting-rod and main bearing. However, the actual engine(especially vehicle engine) does not always operate in rated operating condition and its operating condition changes constantly. In this paper, a fourstroke four-cylinder engine is taken as the studying object, the load and lubrication of connecting-rod and main bearing in di erent operating conditions are analyzed. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all main bearings are calculated by the whole crankshaft beam-element finite element method, and the lubrication performance of connecting-rod and main bearings are analyzed by the dynamic method. The results show that there are major di erences in the changes and numerical value at corresponding moment of the loads and lubrication performance of connecting-rod and main bearings in an engine operating cycle in di erent engine operating conditions; the most unfavorable case of the lubrication performance of connectingrod and main bearings may not take place in the rated engine operating condition. There are also major di erences between the lubrication performance of connecting-rod bearing and that of main bearing and between the lubrication performances of main bearings one another. Therefore, it will not be reasonable that the lubrication performance of a certain connecting-rod bearing or main bearing is analyzed in the design of the engine bearing. It is necessary to analyze simultaneously the lubrication performances of all bearings in di erent engine operating conditions.
