Research On Mechanical Seals In The End Of Axial Piston Pump Using Kerosene As Working Medium

Mechanical seal is a common form of dynamic seal,as a kind of important basic component in hydraulic elements,it has lots of advantages of stabilization,durability and wide application range,because of these,it was widely applicated in hydraulic pumps.The axial piston pump which uses kerosene as medium is the key power component in aerospace hydraulic system,its reliability and working life has a decisive influence to the stability and safety of the whole system.The mechanical seal in shaft tail is a important device which prevents the leakage of internal high-pressure kerosene.Due to the low-viscosity property of kerosene,a stable liquid film often hard to be established on mechanical seal face,which can lead to the problem of exceed leakage and torque,it will seriously affect the working life and reliability of piston pump.So the research on the problem of exceed leakage and torque can ensure the normal working of piston pump,and it has important pratical significance to improve the performance of pump.The problem of exceed leakage and torque of mechanical seal often affected by the seal properties,this paper studies four groups of important properties which are the stress and deformation characteristics,the heat transfer characteristics,the film leakage characteristics,and friction and wear characteristics.This paper starts from the basic theories of each characteristics,the research models are established,the theoretical derivations are achieved,and the relationship between parameters which have infuences on leakage and friction is got.Through the multi-dimensional studies of stuctures and materials,the ways are found to reduce the leakage and improve the performance of friction,and the pump test of frictional torque is achieved for mechanical seal.Firstly,the models of characteristics analysis are given,such as elastic mechanics model,thermodynamics model,fluid mechanics model and basic wear model.And the relationship of expression for key parameters are got,such as the face radial displacement,cavity flow velocity,leakage and wear volume,which make a theoretical basis for further research.Secondly,this paper starts from the proprietary f-G characteristics of mechanical seal,the simulation method is used,the force and thermal deformation of face are got successively under defferent seal pressure,defferent cavity flow velocity,and defferent paired materials,then the defferent film clearance forms are synthetically got under the control of defferent parameters,and the CFD software is used to calculate the leakage rates for defferent film clearance forms,besides the influences of sructure and materials paremeters to leakage rate are analized,the leakage index is verified.Thirdly,three representative groups soft materials and hard materials are chosen respectively,through the tribology experiment,the influence of frictional coefficient and face temperature rising by materials properties and surface roughness are gotten.Through AFM,the specimen surfaces before and after experiment are analized,the single height distribution function is solved by statistical methods,besides the single volume of abrasive wear and adhesive wear are got in the defferent combination matching of materials.Finally,on the kerosene pump test bench,the frictional torque test is finished for the modified pump,the influences of torque by defferent axial size and paired materials are compared,and the rotating torque index is verified.