Development Of Ultra-high Pressure And Low Flow Precision Plunger Pump In Parallel

In order to carry out the related research work of rock mechanics,a rotary triaxial rock tester which can simulate the deep underground environment and analyze the dynamic and static characteristics of deep underground rock is needed to assist in the study,and the piston pump is the core loading unit of the rotary triaxial Rock tester,which is the key to the normal operation of the rock testing machine.The traditional oblique disc piston pump technology has been very mature,but the volume efficiency decreases greatly under the high pressure condition,which can not meet the ultra-high pressure loading requirements of the rotary three-axis rock tester.In this paper,a kind of ultra-high pressure low flow parallel precision piston pump is designed and developed,which can improve the load capacity and loading precision,and fully reflect the development direction of digital and miniaturization of hydraulic system.Firstly,through the study of the basic theory of the traditional oblique disc axial piston pump,a new type of piston pump with servo motor as the driving unit is proposed,and all parts of the pump are designed and manufactured.On this basis,through the pipeline and solenoid valve connection two piston pump to form a parallel precision piston pump loading system,the working principle is described and the two-pump movement law is given to complete the installation and commissioning work.Then using ANSYS software to carry on the stress and strain simulation analysis to the plunger pair,the stress and strain distribution and deformation of the plunger are determined,the concrete values are obtained,which provides the theoretical basis for the subsequent structural optimization,and the flow pulsation rate of the plunger pump in the working state is calculated by deriving the fluctuation formula of the flow.The results are in accordance with the performance index originally designed by piston pump.In order to solve the sealing problem of plunger pump under UHV condition,on the basis of analyzing the common sealing structure,a new sealing method suitable for this subject,the pan-plug seal ring,is adopted,and after modeling the pan-plug seal ring,the deformation quantity of the plug seal after compression is simulated by using Ansys software,The feasibility of sealing the pan-plug seal ring with composite PTFE material on the UHV piston pump is verified.Finally,aiming at the nonlinearity and strong coupling of the parallel piston pump loading system,the fuzzy PID control algorithm and the conventional PID control algorithm are designed,and through mathematical modeling,simulation,industrial test,comparative analysis of the experimental results,it is concluded that the stability and control accuracy of the loading system can be improved under fuzzy PID control.It is further verified that the ultra-high pressure low flow parallel precision piston pump developed in this paper can meet the loading requirements of rock testing machine.The research results of this paper provide theoretical basis and important reference value for the development of piston pump.