Research To The Influential Factors Of Small High-pressure Plunger Pump Volume Efficiency

With the rapid development of science and technology,it has become an inevitable trend for the hydraulic pump used in aerospace hydraulic system to develop towards the direction of high pressure miniaturization,high efficiency and high speed.Due to the characteristics of high working pressure and wide operating speed range,plunger pump has obvious advantages in the application of aerospace hydraulic system.However,the volumetric efficiency of existing small-displacement high-pressure plunger pumps is obviously lower than that of largedisplacement high-pressure plunger pumps under high speed and high load conditions,due to the high proportion of leakage in small high-pressure plunger pumps,especially the disharmony between the flow valve and plunger movement.Therefore,research on the influence of distribution valve characteristic parameters on volumetric efficiency of small high-pressure three-plunger pump is carried out in order to improve volumetric efficiency of small highpressure three-plunger pump,and provide a reference for the high pressure and high power density of small piston pump,which has certain theoretical value and practical significance.In this paper,the small high-pressure three-plunger pump is studied by AMESim hydraulic system simulation and numerical calculation of internal flow field,aiming at the low volumetric efficiency of the pump,the purpose of this paper is to explore the mechanism of the influence of distribution valve characteristic parameters on volumetric efficiency of small high-pressure three-plunger pump.The specific work includes the following aspects:(1)Theoretical analysis and modeling of a small high-pressure three-plunger pump.This paper describes the structural characteristics and working principle of the small high-pressure three-plunger pump,carries out kinematics and dynamic analysis of the plunger pair,optimizes the structure of the main shaft swashplate,analyzes the pressure flow characteristics of the port valve and the force on the valve core,and establishes a preliminary three-dimensional model of the small high-pressure three-plunger pump.(2)Analysis of the influence of different spool types on volumetric efficiency and the lag factor of spool.According to the principle of small high-pressure three-plunger pump and preliminary three-dimensional model parameters,the hydraulic system model of the pump is built by AMESim software,and the model is verified and analyzed,the influence of three kinds of valve core structure on volumetric efficiency is discussed.The results show that when the suction valve and the discharge valve are both flat valves,there is the optimal combination model of volumetric efficiency of the pump.At the same time,it was found that there is hysteresis in the movement of the flat valve core,and the factors affecting its hysteresis were simulated and analyzed.(3)Analysis of the influence of the design and structural parameters of the flat valve on the volumetric efficiency of a small high-pressure three plunger pump.The flat valve matched with the plunger is designed,and the control variates and orthogonal test method are used to analyze the influence trend and weight of parameters such as dead volume,valve core mass,spring stiffness and preload on the volumetric efficiency of small high-pressure three-plunger pump.The maximum range value in the experimental results is 0.945,and the minimum range value is 0.242.The weight order of the impact of various factors on volumetric efficiency is:closed volume>suction valve core quality>discharge valve core quality>suction valve pre tightening force>discharge valve pre tightening force.(4)Research on the characteristics of internal flow field of small high-pressure threeplunger pump with valve distribution.The internal flow field model of the small high-pressure three-plunger pump was taken out,and the operation of the whole pump and the distribution of pressure and flow in the dynamic process of the suction and discharge of the small high-pressure three-plunger pump were analyzed by the joint simulation of AMESim and Pump Linx.(5)Effect of different closed volumes on volumetric efficiency.The single plunger model of the small high-pressure three-plunger pump is simulated based on the closed volume structure of different sizes,the results show that the volumetric efficiency increased from 73.36%to 89.48% by 16.12% when the load pressure is 30 MPa,the rotating speed is 3000 r/min and the closed volume is reduced from 0.65 m L to 0.25 m L.Therefore,the volume efficiency can be improved by reducing the closed volume under the conditions of variable speed and variable load.What is more,the volume efficiency decreases with the increase of speed when the closed volume is small,and decreases with the increase of load pressure under the same closed volume structure.