Study On Damping Groove Characteristics And Optimization Of Axial Piston Pump

Axial piston pump is one of the most important, complex and high-tech components in hydraulic systems. One of the most important performances of axial piston pump is noise level. Research on noise reduction is a current hotspot. Fluid-born noise is the vast majority of axial piston pump noise and flow ripple is its main cause. The structure of damping grooves in the valve plate can influent the flow ripple greatly. It is the research focus of this thesis.In this thesis, the influence of damping groove structure on flow characteristics was researched. Its generation mechanism and influence principle was analysed. First, the movement mechanism of axial piston pump was analysed. The flow characteristics of a single piston was modeled, which concerned piston movement, throttling effect of valve plate, leakage flow, oil inertia and so on. The model for the whole pump was built by coupling several single-piston models with different phase angles. Especially, the overflow cross-section area of valve plate was analysed in detail, for its significant effect on flow ripple. A computer simulation model of axial piston pump flow charateristics was built, which could be used for simulation of different types of axial piston pumps, expecially the ones with different valve plates. Results of simulation on a particular axial piston pump showed that when its U-shape damping groove on valve plate had an arc radius of1.5mm and a depth of2.5mm, it could get ideal flow characteristics, which had a9.5percentage less flow ripple amplitude. The influence of different damping groove structures on flow characteristics was studied, by changing the computer simulation models and analysing the simulation results. A test rig for flow ripple of axial piston pump was built. The results verified the accuracy of the simulation program. By changing experiments of the test rig, the effects of some parameters like pressure and rotation speed on flow characteristics were analysed.In chapter1, the research purpose and significance of the thesis were carried out. The influence of damping groove structure on flow characteristics was introduced. The research status on damping groove influence and flow ripple test method were reviewed. The research contents of this thesis were proposed.In chapter2, the theoretical model of flow characteristics of axial piston pump was established. The movement principle was analysed. The theoretical model of a single piston was built, concerning piston movement, throttling effect of valve plate, leakage flow, oil inertia and so on. The overflow cross-section area of valve plate was especially detailedly analysed, for its significant effect on flow ripple. The model for the whole pump was built by combining several single-piston models with different phase angles. The whole-pump model also included a system load model and a pipe dynamic characteristics model. In chapter3, A Matlab/Simulink simulation program on flow characteristics of axial piston pump was built. With the program, it’s easy to do simulation and get many kinds of ouput results, such as output pressure, output flow, pressure in the piston champer, flow of a single piston champer, moment of the swash plate and so on. Modular design method was applied in program development. Different parts of axial piston pump were built separately and could be replaced easily. For some important modulars, altnative replacement models were built. By combining different modulars, it’s easy to built simulation models for different pumps.In chapter4, the simulation program was used for many simulations, analyses and optimization. Simulations on a high-pressure large-flow piston pump showed that when its U-shape damping groove on valve plate had an arc radius of1.5mm and a depth of2.5mm, it could get ideal flow characteristics, which had a9.5percentage less flow ripple amplitude. Based on the pump model, several different pump models were built by changing the valve plate model. Influence of different damping grooves on flow characteristics was studied.In chapter5, flow ripple test methods of axial piston pump were analysed, a test rig based on the secondary source method was built. The test results verified the accuracy of the simulation program. By changing experiment parameters of the test rig. the effects of pressure and rotation speed on flow characteristics were analysed.In chapter6, a summary of this thesis and some suggestions for future development were given.