Study On Flow Ripple Optimization Of Swashplate Axial Piston Pump

Flow ripple is the main cause of noise in hydraulic system.The ways to reduce flow ripple can be divided into two categories: external shock absorber and internal structure optimization of hydraulic pump.The external pulsating absorption device includes accumulator,on-line noise suppressor,muffler,etc.The internal structure optimization of piston pump includes setting up buffer damping groove,adding one-way valve,adjusting the angle of valve plate,setting cross-angle of swashplate,setting pre-compression volume,etc.The objective of this paper is to optimize the internal structure of the piston pump.Through the simulation modeling and analysis of the swashplate cross-angle piston pump and the pre-pressure volume piston pump,the optimized structural parameters are obtained.The main contents of this paper are as follows:1.This paper introduces the research background and significance of the subject,mainly describes the research methods and research status of flow ripple of axial piston pump,and explains the research content and direction of the paper.2.The mathematical analysis of the single piston chamber of the piston pump is carried out.The movement law of the piston and three main flow leakage modes are explained,including piston pair leakage,slipper pair leakage and distribution pair leakage.The calculation formulas of leakage flow are given respectively.3.The geometric flow of piston pumps with different number of pistons is calculated.It is found that the geometric flow ripple rate of adjacent odd-number piston pumps is less than that of even-number piston pumps.So this paper chooses 9 piston pumps as the simulation model and explains the simulation process.4.The simulation model and flow ripple analysis of the pre-compression volume piston pump are carried out,and the simulation models of the pre-compression volume piston pump and the ordinary piston pump are established by using PumpLinx software.Under different pressure and speed conditions,the flow ripple rate of the two pumps was compared and analyzed.It was found that under the same working conditions,the flow ripple rate of the pre-compression volume piston pump was smaller than that of the ordinary piston pump.In terms of speed,the smaller the speed,the greater the advantage of the pre-compression volume piston pump;in terms of pressure,the pre-compression volume piston pump has the greatest advantage when the pressure is 10 MPa.By analyzing the change of flow ripple rate,it is found that the pre-compression volume piston pump has excellent adaptability under the conditions of medium-low pressure,medium-low speed,and the flow ripple rate can almost remain unchanged.5.Simulation modeling and flow ripple analysis of the swashplate cross-angle piston pump are carried out.The cross-angle is set in the range of-2°~2°in PumpLinx software,and the influence of cross-angle on the outlet flow of the piston pump is investigated in this range.Through mathematical analysis of the functional relationship between cross-angle and piston compression volume,it is found that cross-angle can approximately linearly increase the compression volume in the transition zone of triangular groove,thereby reducing the downward peak of flow backfilling,but increasing the compression of fluid in piston cavity,resulting in pressure overshoot in the cavity.By analyzing the outlet flow rate of the swashplate cross-angle piston pump at different rotational speeds and pressures,it is found that when the cross-angle is 1°,it can effectively reduce the flow rate of backfilling and also make the pressure overshoot within a suitable range.Finally,the work done in this paper is summarized,the research conclusions are given,and the future research work is prospected.