| The external return mechanism as three friction pair piston pump/motor connection device,performance of the three big friction pair work all have important influence,but its complex motion can cause friction between parts vice friction loss and the lubrication failure,does not favor the plunger pump/motor performance,vibration,noise and other technical indicators.Therefore,this paper takes the external return mechanism as the research object,and establishes the mathematical models of friction dynamic lubrication characteristics under ideal,actual and full working conditions respectively.The effects of its spatial motion characteristics,dynamics of under constrained cylinder,structure and oil film parameters on the friction and lubrication characteristics of the ball joint pair are analyzed.The dynamic lubrication and friction loss mechanism are revealed,which provides a more comprehensive reference for further improvement.The main work is as follows:The research background,significance and technical difficulties of external return mechanism were described,and the causes of friction loss and lubrication failure were pointed out.The research status of different types of return mechanism and related spherical friction pair in relative motion trajectory,lubrication characteristics,friction and wear were summarized.The source,purpose and content of the research are summarized.According to the mating relationship and spatial motion characteristics of the external return spherical hinge pair,the velocity boundary conditions,axial and circumscribed boundary conditions of the external return spherical hinge pair under theoretical working conditions were obtained.The Reynolds equation of external return spherical hinge pair was established and then the lubrication of the external return spherical hinge under different structural parameters was analyzed.The results show that different the slant inclination of the external swash plate,pump shaft rotating speed,eccentricity all affect the lubrication characteristics of friction pair,especially,the slant inclination of the external swash plate and oil film clearance have great influence on axial leakage flow.The influence of offset and external swash plate inclination on lubrication characteristics of external return spherical bearing pair was considered under actual working conditions.According to the master-slave coordinate system of external return mechanism,the velocity distribution of all contact points of the external return spherical bearing pair was established.The Reynolds equation applied to an external return spherical hinge pair was deduced based on the vector equation of relative-motion velocity of the external return spherical hinge pair under the influence of external swash plate inclination and offset distance.The results show that the total friction,axial leakage flow,and maximum value of the maximum oil-film pressure increase with increasing pump-shaft speed and decrease with increasing offset distance in one working cycle when the external-swash-plate inclination is constant.However,the varying offset distance has little effect on the axial leakage flow.The maximum value of the maximum oil-film pressure decreases with increasing external-swash-plate inclination and the total leakage flow increases with increasing external-swash-plate inclination in one working cycle when the offset distance is constant.The friction and wear experiments of external retainer plate and external spherical hinge were carried out according to the self-developed test device,and the experimental friction and wear conditions were consistent with the simulation results.The kinematics model of double row axial plunger,the oil pressure model of inner and outer row plunger chamber and the dynamic model of underconstrained cylinder block/joint were established,and the direct forces and moments of double row cylinder were deduced.The indirect force of double row cylinder block is analyzed and the indirect force and moment of inner and external return spherical bearing pair are deduced.Based on the force balance equation of inner and outer row plunger-slipper assembly,the indirect force and moment of inner and outer row plunger-slipper pair were deduced,and the micro motion dynamics model of double row cylinder was established.Finally,the two-way coupling model of the flow field of external return spherical bearing pair and the micro deformation field of cylinder body was established,and the numerical solution method was established.Figure[44]table[9]reference[72]... |
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