| Axial piston pump, the most important component in hydraulic systems, is widely used in industrial machinery.In axial piston pump, the coupling of fluid and mechanism (FM) is a basic feature. On the one hand, the mechanical energy from prime mover is converted to fluid energy through moving fluid by mechanism; on the other hand, the lubrication condition of viscous friction pairs, including piston pairs, distribution pair and slipper pairs, are maintained by the FM coupling, which have a significant effect on the performance of axial piston pump. Therefore, a new approach to study FM coupling, the virtual prototype technology of axial piston pump, was mainly focused in this thesis.In this thesis, the Virtual Simulation Package of Axial piston pump (ViSPA) has been developed. In order to verify the simulation results, a test rig was set up. By comparison of simulation and experimental results, it was proved that the simulation accuracy of ViSPA can reach 96.1%. In the ViSPA, three dimension (3D) multi-body dynamics model of the pump mechanism for analysis of rigid bodies were established, and a fitness element method (FEM) flexibility model was built to study elastic-mechanics of key parts. For the FM co-simulation, the rigid and flexible models must be used together with fluid model, which take into oil film dynamics of piston pairs. The kinematic, dynamics and fluid parameters in the virtual prototype environment can be calculated simultaneously and interchanged through the interfaces in real time. Moreover, the test pump was designed and engineered to mount micro sensors in the cylinder body of pump without influence on the pump performance. So not only the external performance but also the pressure, temperature and film height inside the piston pairs can be measured in a real piston pump. Based upon the ViSPA simulation and the experiment, the pressure distribution between piston and cylinder bore inside the pump was examined. The values from experiment and simulation in the 3D distribution surface are very close in same position inside the piston chamber and in the same phase of piston rotation.In addition, the ViSPA simulation accuracy of the external and internal parameters of the pump was studied. The average simulation accuracy of output flow, pressure and rotary speed is more than 96.2% in open loop system compared with the experimental results, and it can reach 95.9% in close loop. As for pressure and flow ripple rate of axial piston pump, the difference between calculated and measured value is only 0.5% and 0.6%. Therefore, the ViSPA is an effective tool to predict the external and internal performance of axial piston pump. Also the ViSPA was applied to study cross power control of axial piston double pump and high speed on/off control in axial piston pump. Thus, the ViSPA developed can be used as a reference to study the behaviors of axial piston pump together with optimal design of pump structure.In chapter 1, the aim and significance of the study in the thesis were discussed. The current research progresses on virtual prototype technology of axial piston pump were reviewed. The main research subjects were presented.In chapter 2, the theoretical study of the pump mechanism was carried out. 3D multi-body dynamics model of the pump mechanism for analysis of rigid bodies were established, and a FEM flexibility model was built to study elastic-mechanics of key parts.In chapter 3, the fluid model of axial piston pump was studied. The power transmission of fluid model was analyzed to obtain the torque loss, the lekage flow and the pressure effect, which are important parameters inside the pump. Also the fluid model takes into oil film dynamics of piston pairs so that help to solve the pressure distribution inside piston chamber.In chapter 4, the interfaces between different models were developed and packaged in a program called ViSPA, and the GUI (Graphical User Interface) of ViSPA was programmed.In chapter 5, In order to verify the simulation results, a test rig was designed and engineered. Not only the external performance but also the pressure, temperature and film height inside the piston pairs can be measured in a test pump, which was developed by inserting micro sensors in the cylinder body of pump.In chapter 6, the ViSPA simulation and experiment results were compared and analayzed. In order to improve the performance and optimize the structure, the relationships between performance and structure inside the pump were investigated. In addition, the ViSPA simulation accuracy of the external and internal parameters of the pump was studied. The average simulation accuracy of output flow, pressure and rotary speed is more than 96.2% in open loop system compared with the experimental results, and it can reach 95.9% in close loop. As for pressure and flow ripple rate of axial piston pump, the difference between calculated and measured value is only 0.5% and 0.6%. Therefore, the ViSPA is an effective tool to predict the external and internal performance of axial piston pump.In chapter 7, conclusions in this thesis were summarized and future research proposals were suggested. |
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