Research On Of The Anti Cavitation Of The Cylinder And Valve Plate Of Swash Plate Axial Piston Pump

The hydraulic axial piston pump are very important component of the hydraulic system,and they are widely used in hydraulic system.With the development of industrial technology,the hydraulic transmission technology that the hydraulic oil is used as the medium has been developed.In order to adapt to the development of industrial technology,the working pressure of mordern hydraulic system is getting higher and higher.At present,the development direction of hydraulic system is high pressure and high speed,the cavitation phenomenon of the hydraulic components has become research hotspots for domestic and foreign scholars.The main research object of the paper is the cavitation flow analysis of plunger cavity of axial piston pump and throttle groove.The main research in this paper are showed that the structure of cylinder kidney hole shape of axial piston pump and valve plate of axial piston pump impacted the cavitation of plunger cavity;the theoretical research on matching relationship between the equivalent diameter of cylinder kidney hole and the diameter of plunger cavity impacted the cavitation of plunger cavity;the functional relation between the structure parameters of axial piston pump and mean value of plunger cavity gas volume fraction has been studied;the function relation between the valve port structure parameters of spool valve and the value of valve port gas volume fraction;research on optimization of anti cavitation structure of cylinder kidney hole of axial piston pump and throttle groove.The specific research contents are as follows:1)The simulation analysis of axial piston pump plunger cavity.The finite element simulation model of axial piston pump cavitation flow is established by use mixture model and cavitation model and RNG k-? turbulence model and dynamic mesh and slide mesh of the Fluent software.The change of the plunger cavity cavitation in each stage of the axial piston pump is quantitatively monitored by the change of the mean value of the gas volume fraction of the plunger cavity.The influence of different inlet pressure,different bank angle of swash plate and the different cylinder rotation rate is studied.2)The study on the ratio relationship between the hydraulic diameter of the cylinder kidney hole and plunger diameter can effect the plunger cavity cavitation.In the aspect of the structure of axial piston pump,the research on structure of cylinder kidney hole effect the plunger cavity cavitation is done.The ratio relationship between the hydraulic diameter of the cylinder kidney hole and plunger diameter can effect the plunger cavity cavitation has been put forward in this paper.According to the assumption condition that the volume of fluid through cylinder kidney hole just filled the extra space of the plunger cavity when the piston moves,the mathematical model of the critical ratio mc between the hydraulic diameter of cylinder kidney hole and plunger cavity diameter under ideal conditions.Alternating angle alpha,bank angle beta of swash plate and angular velocity omega of cylinder effected the critical ratio mc that has been analysed and been carried out by simulation,the proposal of the reasonable ratio relation has been putted forward.3)The theoretical analysis of the structure of the inclined cylinder kidney hole influence the plunger cavity cavitation.There are two types of cylinder kidney hole of axial piston pump,which are straight and incline type.The structure of cylinder kidney hole are designed as incline type in engineering,which is considered that the centrifugal force of the fluid in the cylinder kidney hole can help the fluid flow into the plunger cavity.Therefore the self absorption ability of the plunger cavity can be improved,and the cavitation degree of the plunger cavity must be reduced to a certain extent,and improved the axial piston pump volumetric efficiency.However,the influence of the structural parameters of the cylinder kidney hole on the self suction of plunger cavity didn't deeply analyzed in practical application.In this paper,the influence of the kidney hole structural parameters such as h,?sy and ?xz on the self absorption ability of the plunger cavity are analyzed theoretically.4)The reasearch on swash plate throttle groove cavitation when axial piston pump is in the stage of pre elevated pressure or pre reduced pressure..The valve plate of axial piston pump design with triangular throttle groove,the purpose of design of triangular throttle groove is to let the plunger cavity pressure close to the pressure of oil inlet or oil outlet of axial piston pump through the throttle groove after the plunger cavity pass through the upper or bottom dead center and reduce oil attack.But when the plunger cavity pass through the dead point,the high pressure differential must appear between the plunger cavity and oil inlet or oil outlet of axial piston pump.The hydraulic oil will pass through the throttle groove with high velocity.The more serious cavitation must appear and the piston pump is accompanied by virbration,noise and reduction volume efficiency.In this paper,the simulation and analysis of the throttle groove structure parameters effectted the throttle groove cavitation by Fluent software and putted forward to the throttle groove anti cavitation structure improvement scheme under the premise of without changing it flow area.Compared the throttle groove cavitation before the improved structure with the throttle groove cavitation after the improved structure,found that the cavitation resistance after improved throttle groove structure is better than before improved structure.5)The study on anti cavitation structure optimization of cylinder kidney hole of axial piston pump and throttle groove based on Kriging agent model.Because of the immaturity of the cavitation theory and the strong coupling of the structural parameters of hydraulic components,so it is more difficult to establish an accurate cavitation mathematical model between the structural parameters and the value of gas volume fraction of fluid.In this paper,the Kriging agent model is choosen to approximate alternative the cavitation mathematical model,and described in detail the theory of Kriging agent model and the principle of model establishment.The proxy precision of the agent model is validated,which shows that the agent model can meet the engineering requirement.The function relationship between the mean value of the plunger cavity gas volume fraction and the structure patameters of axial piston pump cylinder kidney hole is established by using Kriging principle agent model.The function relationship between the maximal value of the throttle groove gas volume fraction and the structure parameters of V shape throttle groove.The function relationship between the maximal value of the throttle groove gas volume fraction and the structure parameters of U shape throttle groove.On the basis of the established Kriging agent model,the genetic algorithm is used to optimize the agent model.Optimized target value is the minimum value of the gas volume fraction.The optimal structure of the axial piston pump,V shape throttle groove and U shape throttle groove are respectively obtained.The study of this paper showed that using the mixture model,dynamic mesh and sliding mesh of Fluent software could more near real to simulate the cavitation flow of hydraulic spool valve port and plunger cavity of axial piston pump.Using Kriging agent model,not only to aviod the establishment of complex cavitation mathematic model,but also can improve the precision of the agent model through the experiment design,conveniently used the improved genetic algorithm to optimized the structure.The research results of the subject provided the theory evidence for the optimization design of structure of hydraulic componente anti cavitation,which has good engineering practicability.