Analysis Of Swash Plate Moment And Instantaneous Flow Characteristic Of Swash Plate Axial Variable Piston Pump With Cross Porting Valve Plate

The swash plate axial variable piston pump is widely used in various hydraulic systems because of its obvious high working pressure,high power density and volumetric efficiency.In the actual hydraulic system,the hydraulic system mostly adopts the closed cycle type in order to meet the requirements of the working condition of the walking machine.Therefore,the frequently used hydraulic pump is swash plate of closed,axial variable piston pump.In order to improve pump's comprehensive performance under complex variable operating conditions,the valve plate that is commonly used is open type,that is,the angle between transition zone of oil suction waist slot and oil discharge waist slot is smaller than that of cylinder block.In this paper,a swash plate axial variable piston with cross porting valve plate of 125 m L/r are selected as the research object.The theoretical analysis and numerical simulation are used to study the moment of the swash plate and the characteristics of the instantaneous output flow of the pump.The main contents of this paper are as follows:In the first chapter,the current research status at home and abroad of swash plate of axial variable piston pump with cross porting is reviewed,and the research significance and background of the research are discussed and the research focus of this paper is introduced.In the second chapter,the valve plate opening areas available for flow transfer between pump ports and displacement chambe r is drawn.The compressible flow model of single piston chamber of axial variable piston pump and the calculation formula of the swash plate moment are established.The swash plate moment under the different inlet pressure is studied.The third chapter,the theoretical instantaneous output flow characteristics of the pump are analyzed.On the basis of the oil compressibility and the three friction pair s leakage characteristics,the actual instantaneous output flow characteristics of the pump are studied.The fourth chapter,the influence of the shaft speed,load pressure and the cross porting of valve plate on the pressure of the piston chamber,the characteristic of the actual instantaneous output flow of the pump and the volume efficiency are analyzed.The main conclusions of this paper are as follows:1)With the increase of the inlet pressure of pump,the average value of the moment on the three coordinate axis is reduced,and the join forces of swash plate on the inclined plate is inclined towards the center of the swash plate.2)Considering the compressible distribution,the volumetric efficiency of the axial piston pump with cross porting valve plate is mainly affected by cross porting of the valve plate.The leakage of pump is mainly caused by the backflow from the relief triangular groove,which accounts for about ninety percent of the total flow loss.3)The volume efficiency of the piston pump increases with the increase of the shaft speed,and decreases with the increase of the load pressure,and the rate of flow pulsation decreases with the increase of the shaft speed,and increases with the increase of the load pressure.With the larger cross porting of the valve plate,the positive and negative overshoot of the piston chamber decreases,but the volume efficiency of the pump decreases and the flow pulsation increases.Finally,the research work and research results of this thesis are summarized,and the future research work is prospected.