A new method combining the slider-crank mechanism dynamic(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effects of CB dimensions and engine speed on the lubrication efficiency and friction ...A new method combining the slider-crank mechanism dynamic(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effects of CB dimensions and engine speed on the lubrication efficiency and friction power loss(LE-FPL)of an engine.The dynamic and lubrication equations are then solved on the basis of the combined model via an algorithm developed in MATLAB.To enhance the reliability of the research results,the experimental data of combustion gas pressure is applied for simulation.The load bearing capacity(or oil film pressure),friction force,friction coefficient,and eccentricity ratio of the CB are selected as objective functions to evaluate the LE-FPL.The effects of engine speed,bearing width,and bearing radius on the LE-FPL are then evaluated.Results show that reductions in engine speed,bearing width,or bearing radius can decrease the FPL but reduce the LE of the engine and vice versa.In particular,the LE-FPL can effectively be improved by slightly reducing the bearing width and bearing radius or maintaining engine speed at 2000 r/min.展开更多
Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions.Unlike in conventional external cylindrical plunge grinding,the conditions between the grindi...Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions.Unlike in conventional external cylindrical plunge grinding,the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft.The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding.Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride（CBN）wheel.The grinding force is determined by measuring the torque.The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding.The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths.In path controlled grinding,unlike in conventional external cylindrical plunge grinding,the axial grinding force cannot be disregarded.The speeds and speed ratios of the workpiece and wheel are also analyzed,and the analysis results show that up-grinding and down-grinding occur during the grinding process.This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding,which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.展开更多
A new hybrid numerical method that couples the dynamic slider-crank mechanism(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effect of micro asperity contact on the tribological properties o...A new hybrid numerical method that couples the dynamic slider-crank mechanism(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effect of micro asperity contact on the tribological properties of a CB.In the hybrid model,the dynamic equations of the SCM are established based on the Newton method,while the lubrication equations of the CB are established on the basis of the Reynolds equation.Experimental data of the engine are also used in simulation analyses to enhance the reliability of the results.The load-bearing capacity(LBC)and friction force of the CB are selected as objective functions.Results show that the LBC has a negligible effect on the tribological properties of the CB,but the friction force greatly affects the resistance of the bearing under different radial clearances and surface roughness values.In particular,the maximum friction force in the asperity contact region accounts for 40.5%of the maximum total friction force at a radial clearance of 5μm and 77.7%of the maximum total friction of the CB with a surface roughness of 10μm.展开更多
A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,t...A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,the bearing surface of CB using different microtextures,such as wedge-shaped textures(WSTs),square textures(STs),circular textures(CTs),and combined square-circular textures(CSCTs),is simulated and assessed under various external loads of the CB at an engine speed of 2000 r/min.The pressure of the oil film,the frictional force,the force of the solid asperity contact,and the friction coefficient of the CB are used as objective functions.Results indicate that the bearing surface designed by the STs remarkably improves the CB s LFP in comparison with other structures of WSTs,CTs,and CSCTs.Particularly,the average values of the frictional force,solid asperity contact,and friction coefficient of the CB using the STs are greatly reduced by 28.5%,14.5%,and 33.2%and by 34.4%,26.3%,and 43.6%in comparison with the optimized CB dimensions and CTs,respectively.Therefore,the application of the STs on the CB surfaces can enhance the LFP of engines.展开更多
基于EXCITE Power Unit软件,采用弹性流体动力润滑(EHD)的方法建立了某船用低速柴油机曲柄销轴承的仿真模型,使用有限元法和有限差分法对曲柄销轴承润滑性能进行了仿真,研究额定工况下曲柄销轴承油膜压力、油膜厚度、轴承比压、摩擦功...基于EXCITE Power Unit软件,采用弹性流体动力润滑(EHD)的方法建立了某船用低速柴油机曲柄销轴承的仿真模型,使用有限元法和有限差分法对曲柄销轴承润滑性能进行了仿真,研究额定工况下曲柄销轴承油膜压力、油膜厚度、轴承比压、摩擦功耗等性能参数随曲轴转角的变化情况,为曲柄销轴承的设计选型提供理论依据。展开更多
基金The National Key Research and Development Plan(No.2019YFB2006402)the Key Project of Scientific Research Plan of Hubei Polytechnic University(No.21xjz02A)the Open Fund Project of Hubei Key Laboratory of Intelligent Transportation Technology and Device,Hubei Polytechnic University(No.2020XY105,2020XZ107).
文摘A new method combining the slider-crank mechanism dynamic(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effects of CB dimensions and engine speed on the lubrication efficiency and friction power loss(LE-FPL)of an engine.The dynamic and lubrication equations are then solved on the basis of the combined model via an algorithm developed in MATLAB.To enhance the reliability of the research results,the experimental data of combustion gas pressure is applied for simulation.The load bearing capacity(or oil film pressure),friction force,friction coefficient,and eccentricity ratio of the CB are selected as objective functions to evaluate the LE-FPL.The effects of engine speed,bearing width,and bearing radius on the LE-FPL are then evaluated.Results show that reductions in engine speed,bearing width,or bearing radius can decrease the FPL but reduce the LE of the engine and vice versa.In particular,the LE-FPL can effectively be improved by slightly reducing the bearing width and bearing radius or maintaining engine speed at 2000 r/min.
基金Supported by National Science and Technology Major Project of China(Grant No.20133ZX04002-031)Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.551121063)State Key Laboratory of Mechanical System and Vibration of China(Grant No.MSV2D2014112)
文摘Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions.Unlike in conventional external cylindrical plunge grinding,the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft.The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding.Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride（CBN）wheel.The grinding force is determined by measuring the torque.The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding.The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths.In path controlled grinding,unlike in conventional external cylindrical plunge grinding,the axial grinding force cannot be disregarded.The speeds and speed ratios of the workpiece and wheel are also analyzed,and the analysis results show that up-grinding and down-grinding occur during the grinding process.This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding,which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.
基金The National Key Research and Development Project(No.2019YFB2006402)the Open Fund Project of Key Laboratory of Intelligent Conveying Technology and Device,Hubei Polytechnic University.
文摘A new hybrid numerical method that couples the dynamic slider-crank mechanism(SCM)and crankpin bearing(CB)lubrication models is proposed to analyze the effect of micro asperity contact on the tribological properties of a CB.In the hybrid model,the dynamic equations of the SCM are established based on the Newton method,while the lubrication equations of the CB are established on the basis of the Reynolds equation.Experimental data of the engine are also used in simulation analyses to enhance the reliability of the results.The load-bearing capacity(LBC)and friction force of the CB are selected as objective functions.Results show that the LBC has a negligible effect on the tribological properties of the CB,but the friction force greatly affects the resistance of the bearing under different radial clearances and surface roughness values.In particular,the maximum friction force in the asperity contact region accounts for 40.5%of the maximum total friction force at a radial clearance of 5μm and 77.7%of the maximum total friction of the CB with a surface roughness of 10μm.
基金The National Key Research and Development Program of China(No.2019YFB2006402)the Open Fund Project of Hubei Key Laboratory of Intelligent Transportation Technology and Device,Hubei Polytechnic University(No.2021XZ107)the Key Scientific Research Project of Hubei Polytechnic University(No.21xjz02A).
文摘A design of different microtextures on the surface of the crankpin bearing(CB)is proposed to ameliorate the lubrication and friction performance(LFP)of engines.On the basis of the CB s hydrodynamic lubrication model,the bearing surface of CB using different microtextures,such as wedge-shaped textures(WSTs),square textures(STs),circular textures(CTs),and combined square-circular textures(CSCTs),is simulated and assessed under various external loads of the CB at an engine speed of 2000 r/min.The pressure of the oil film,the frictional force,the force of the solid asperity contact,and the friction coefficient of the CB are used as objective functions.Results indicate that the bearing surface designed by the STs remarkably improves the CB s LFP in comparison with other structures of WSTs,CTs,and CSCTs.Particularly,the average values of the frictional force,solid asperity contact,and friction coefficient of the CB using the STs are greatly reduced by 28.5%,14.5%,and 33.2%and by 34.4%,26.3%,and 43.6%in comparison with the optimized CB dimensions and CTs,respectively.Therefore,the application of the STs on the CB surfaces can enhance the LFP of engines.
文摘基于EXCITE Power Unit软件,采用弹性流体动力润滑(EHD)的方法建立了某船用低速柴油机曲柄销轴承的仿真模型,使用有限元法和有限差分法对曲柄销轴承润滑性能进行了仿真,研究额定工况下曲柄销轴承油膜压力、油膜厚度、轴承比压、摩擦功耗等性能参数随曲轴转角的变化情况,为曲柄销轴承的设计选型提供理论依据。
