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High pressure and high speed of the axial piston pump can improve its power density, but they also deteriorate the thermal-fluid-structure coupling effect of the friction pairs. This paper aims to reveal the coupling mechanism of the pump, for example, valve plate pair, by carrying out research on multi-physics field coupling.

Considering the influences of temperature on material properties and thermal fluid on structure, the thermal-fluid elastic mechanics model is established. A complete set of fast and effective thermal-fluid-structure coupling method is presented, by which the numerical analysis is conducted for the valve plate pair.

According to calculations, it is revealed that the temperature and pressure evolution laws of oil film with time, the pressure distribution law of the fluid, stress and displacement distribution laws of the solid in the valve plate pair. In addition, the forming history of the wedge-shaped oil film and mating clearance change law with rotational speed and outlet pressure in the valve plate pair are presented.

For an axial piston pump operating under high speed, high pressure and wide temperature range, the multi-physics field coupling analysis is an indispensable means and method. This paper provides theoretical evidence for the development of the pump and lays a solid foundation for the research of the same kind of problem.

This paper aims to carry out a thermal-hydraulic simulation model for pump and hydraulic system to predict the temperature increasing and pump performance. Based on the model, how to alleviate the temperature is introduced. Besides, the optimization of piston is carried out.

This paper analyzes the heat generation in lubricating interfaces of the pump with energy conversion theory. The heat transfer inside the pump is analyzed with the control volume method. The simulation model is constructed in AMESim because of its operating friendly nature. The experiment is carried out to prove the validity and accuracy of the simulation model.

Temperature has less effect on the mechanical loss of pump. However, it has a great impact on volumetric efficiency. To reduce the temperature on the piston surface, the size of the piston should be optimized.

This paper fulfills a novel thermal-hydraulic model to evaluate the temperature of the pump. Based on the model, the performance of the pump is determined and optimization is carried out.

The purpose of this paper is to experimentally and theoretically investigate slippers, which have an important role on power dissipation in the swash plate axial piston pumps.

The slipper geometry and working conditions affected on the slipper performance have been analyzed experimentally. The model of the slipper system has been established by original neural network (NN) method.

First, the effects of the slipper geometry with smooth and conical sliding surfaces on the slipper performance were experimentally analyzed. Smooth sliding surface slippers showed a better performance then the conical surface ones. According to the results, the neural predictor would be used as a predictor for possible experimental applications on modeling this type of system.

This paper discusses a new modeling scheme known as artificial NNs an experimental and a NN approach have been employed for analyzing axial piston pumps. The simulation results suggest that the neural predictor would be used as a predictor for possible experimental applications on modeling bearing system.

This paper aims to provide a reliable and efficient numerical piston–cylinder design method and assess the effect of clearance on the piston-cylinder lubrication.

Numerical analyses of lubrication characteristics were performed for the piston–cylinder interface. The axial piston was numerically modeled, and the film pressure was calculated using the unsteady two-dimensional Reynolds equation. The behavior of the piston was analyzed by calculating the eccentricity satisfying the force and moment balance.

The secondary motion of the piston included numerically simulated several cycles until the piston behavior converged, and contact with the inner wall of the cylinder and friction region was estimated. Results showed that the piston–cylinder clearance affected the contact force, length of the contact region and leakage flow rate.

This result improves the understanding of the piston–cylinder lubrication and suggests considerations in terms of lubrication in clearance design.

The purpose of this paper is to investigate, theoretically and experimentally, the sealing performance of the axial piston seal on a larger diameter (100 mm in diameter) axial piston and reveal the sealing mechanism of the axial piston.

Based on the characteristics of the clearance flow between the seal and the piston, reasonable boundary conditions for Navier‐Stokes' equations are determined and the equations are modified, so that the final equations can describe the real flow state of the clearance flow.

Through combining the final equations with finite element method, the pressure distributions within the clearance field for the sealing part during the reciprocating motion of the piston and the leakage rate with the pressure are obtained. The deflections of the sealing part which affect sealing performance have been given.

Theoretical and experimental results show the internal relationship between the seal and the piston, also help to develop some newer piston pumps and improve on the seals of present high‐pressure piston pumps.

A neural network is employed to analyze axial piston pump of hydrostatic circular recessed bearing. Owing to complexity of the system, the neural network is used to predict the bearing parameters of the experimental system. The system mainly consists of cylinder block, piston, slipper, ball‐joint and swash plate. The neural model of the system has three layers, which are input layer with one neuron, hidden layer with ten neurons and output layer with three neurons. It can be outlined from the results for both approaches neural network could be modeled bearing systems in real time applications.

In recent years water hydraulic systems have become of major interest because of the human friendly and environmental safety aspects. The piston pump is one of the most frequently used hydraulic units in recent engineering techniques. In a water hydraulic piston pump, poor lubrication is more likely to happen than in a oil hydraulic one because of differences in properties between water and oil. There are some key problems, such as corrosive wear and erosion, which are briefly investigated in this paper. Many new materials have been developed, which give longer life expectancies in water without corrosion and erosion. Recently, a new type of seawater hydraulic piston pump with better suction characteristics had been developed at Huazhong University of Science and Technology, China. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced in this paper.

The purpose of this paper is to identify the energy losses factors during the hydro-mechanical conversion process at high pressure via a novel reduced order dynamic model.

A novel reduced order dynamic model of the axial piston motor was proposed, which provides an explicit insight to the compression flow losses and the Coulomb friction losses. A fully coupled dynamic model of the piston motor was obtained based on the array bond graph method. And then, a reduced order model was obtained by the composition analysis of flow and torque of the axial piston motor. After that, the energy losses estimation model was presented to predict the energy loss of the piston motor under a wide range of working conditions. The model was verified by comparing the experimental and simulation results.

The simulation result indicates that the flow loss caused by oil compression accounts for 59 per cent of the total flow loss, and the Coulomb friction torque accounts for 40 per cent of the total torque loss under a specific working condition. The compression flow loss and Coulomb friction torque are the major factors that lead to the aggravation of energy loss under extreme working conditions of the piston motor.

At high-pressure condition, the compression flow losses due to fluid compressibility cannot be neglected, and the hydro-mechanical losses in varies friction pairs should involve Coulomb friction losses. Flow and torque loss analytical expression in the model involve the design and control parameters of the piston equipment, which can realize the parameter optimization of the piston equipment for the purpose of energy-saving.

In this paper, experiments were carried out to study the friction and wear performance for the materials of the piston and cylinder in a water hydraulic axial piston pump. The matching of a 940 stainless steel circle with a F102 engineering plastics block and a 940 stainless steel circle with an Al₂O₃ ceramic block were also studied. The wearing capacities were calculated by theoretical formulae based on the grinding crack widths. When pure water is used as hydraulic transmission medium, it is better to use ceramic with engineering plastics as matching materials for the piston and cylinder of water hydraulic axial piston pump. The experimental results have provided a theoretical basis for selecting the matching materials of the piston and cylinder.

This paper aims to revel the leakage characteristics of the bent-axis piston pump considering elastohydrodynamic deformation via a dynamic leakage model.

A dynamic leakage model of bent-axis piston pump based on elastohydrodynamic lubrication theory is proposed, which is used to present the leakage characteristics of bent-axis piston pump. The model is composed of three parts. First, the dynamic gap in the piston ring-cylinder bore interface (PRCB) is described via the elastohydrodynamic lubrication equations. Then, the PRCB leakage is presented based on the dynamic gap. Finally, combined with leakage equation of the valve plate-cylinder block interface (VPCB), the total leakage model is proposed. Through the numerical simulation and experiment, the leakage characteristics of bent-axis piston pump considering elasto-hydrodynamic deformation are studied.

The PRCB leakage is negatively correlated with VPCB leakage under the range of 800–1400 r/min and 1–25 MPa. When the discharge pressure is less than the critical pressure, the PRCB leakage is the main factor affecting the total leakage in bent-axis piston pump. On the contrary, the VPCB leakage is the main factor. The critical pressure increases with increasing speed

The effect of operating parameters has a significant effect on the elastic deformation of piston ring without considering wear of friction pairs in bent-axis piston pump. There is a critical phenomenon in the leakage, which is related to the operating parameters, and provides a novel idea for extracting wear information from leakage and evaluating the status of bent-piston pump.