Research On Lubrication And Wear Characteristics Of The Connecting Rod Bushing For The Engine

The connecting rod bushing is one of the key components of the engine,which connects the piston to the connecting rod through the piston pin and is used to support the piston pin.The connecting rod bushing is subjected to large alternating loads during the engine operation,the specific pressure is above 25 MPa,and the working temperature is over 150℃.The piston pin produces sliding friction relative to the connecting rod bushing during the movement,the size and direction of which would both changes.Part of the connecting rod bushing is at the boundary lubrication state,and it’s truly difficult to form the enough lubricant film,easy to wear the connecting rod bushing and block up the oil hole.Under this circumstance,causing a malignant accident is of high possibility.Therefore,studying the lubrication and wear characteristics of the connecting rod bushing is of great significance and engineering practical value.The lubrication and wear characteristics of the connecting rod bushing is investigated by using calculation and experiment methods in this paper.The main contents and conclusions are shown below:1 The basic theory of fluid dynamic pressure lubrication,friction and wear are expounded.The Reynolds equation is analysed under certain conditions,and the dynamic analysis of crank-link is carried out.2.A test rig was developed to simulate the friction and wear of the connecting rod bushing.The static strength of the crank-link is analyzed by using the finite-element method.Afterwards,the safety of the test rig is checked,and the measurement system is designed and developed.An effective measure of performance test of the connecting rod bushing is provided.3.The multi-body dynamic model of the crank-link of the test rig is established.The axial orbit of the piston pin relative to the connecting rod bushing,the minimum thickness and the maximum pressure of the oil film between friction pairs,and lubrication characteristic parameters of oil film pressure spatial distribution are calculated and analyzed.4.The lubrication characteristic tests of the connecting rod bushing of the engine is completed,and the features of the axial orbit signal under different bearing clearances,different loads and different rotation speeds of the piston pin are analyzed.The test results show that the axis orbit of the piston pin increases with the increase of the load and does not change obviously with the change of the rotation speeds,and its relative position changes when the bearing clearance increases.The feasibility of the real-time measuring of the piston pin axis orbit and the correctness of the multi-body dynamics calculation model of the crank-link are verified.5.An orthogonal test scheme with the bearing clearance,the load,the rotation speed as the test factors,the RMS value of the wear in the orthogonal direction that along the connecting rod centerline and perpendicular to the centerline(radial wear depth)of the connecting rod bushing as the test parameter is designed,which studies the wear characteristics of the connecting rod bushing.The test results reflect that the load has the greatest influence on the wear of the bushing,the rotation speed has less influence and the bearing clearance has the least.Furthermore,the wear loss increases when the bearing clearance decreases,the load or the rotation speed increases.