Experimental studies on the overall efficiency performance of axial piston motor with a laser surface textured valve plate are developed to study the potential use of laser surface texturing in the form of spherical micro-dimples. This study adapts the fiber laser marking machine to machine micro-dimples with different dimensions on the surface of the valve plate for axial piston motor. In addition, these tests of the overall efficiency are given to the axial piston motor fixed to the valve plate with laser micro-dimples in order to find the relationship between the overall efficiency of the axial piston motor and different dimensions of micro-dimples on the surface of the valve plate. The regions of inner dead point and outer dead point of the valve plate are easily erodable because of the pressure pulsation. Therefore, in this study, micro-dimples are machined with different dimensions on the region of the valve plate for the axial piston motor. It is shown that the overall efficiency of the axial piston motor fixed to the valve plate with micro-dimples (area ratio of 5%) can be improved by 2.8%–6.1%, compared to that without micro-dimples; the overall efficiency of axial piston motor fixed to the valve plate with micro-dimples (diameter of 0.1 mm) can be improved by 0.8%–4.9%, compared to that without micro-dimples.

When a swash plate axial piston pump operates under high-pressure conditions, the valve plate will undergo warping deformation. Based on the theory of elastic fluid dynamic lubrication, this work establishes a fluid–solid coupling model of a swash plate axial piston pump and solves the governing equations of the lubrication with respect to the port plate pair. Cylinder speed, cylinder angle, fluid viscosity, oil film thickness, seal belt width, and structural parameters are also considered to observe their influence on the valve plate warpage deformation with the swash plate axial piston pump. The results show that the deformation cloud of the valve plate on the axial piston pump is symmetrical, with the axis line of the waist groove as the axis. The deformation of the outer seal zone on the high-pressure side of the valve plate is the largest, and the deformation of the outer seal zone on the low-pressure side of the valve plate is the smallest. Under the same conditions, the material and structure of the valve plate affect the thickness and shape of the oil film. This study provides a theoretical basis for the high pressure of the swash plate axial piston pump.

In this article, a geometrical model of different microtextures is established for an axial piston pump valve plate. A finite differential method was used to solve the Reynolds equation for the oil film thickness and pressure, which were simulated under different microtextures. The influence of microtexture shape and structure on performance was studied and optimal parameters sought. Different convergence gaps are formed by different microtexture radii, and they produce different hydrodynamic effects. The lubrication characteristics of the valve plate are better when a microtexture is used and are influenced by the type of microtexture. We reached the following conclusions: (1) The lubrication characteristics of the valve plate are influenced by different microtexture parameters and can be improved by optimizing the microtexture parameters; (2) There is an optimal parameter combination when adding microtexture with three shapes (spherical, cylindrical and square) and the optimal dimensionless oil film pressure lubrication characteristics can be obtained; (3) The degree of improvement in the dimensionless oil film pressure lubrication characteristics was (listed from highest to lowest): micro-hemispherical texture > micro-cylindrical texture > micro-square texture.

The purpose of this paper is to study the oil film and friction characteristics of valve plates with a micro-textured surface and to explore the influence of textures of different shapes and sizes on the valve plates. Firstly, on the basis of thermohydrodynamic theory, this paper established the lubrication model of the oil film on the valve plate pair of swashplate axial piston pumps, according to the Reynolds equation. Secondly, the micro-texture was added to the mathematical model of the valve plate pair’s oil film. A combination of the energy equation, oil-film-thickness equation, elastic deformation equation, viscosity–pressure and viscosity–temperature equation, the finite difference method, as well as the relaxation iteration method, was used to solve the problem, and the textured and non-textured valve plate surfaces were simulated. The nephogram of the oil-film-thickness distribution, elastic deformation distribution, oil-film-pressure distribution and oil-film-temperature distribution were generated. Then, the control variable method was used to change the cylinder rotational speed, tilt angle, oil viscosity, initial oil film thickness and other parameters to analyze their effects on oil film characteristics. In addition, the friction characteristics of non-textured surfaces, square textured surfaces, triangular textured surfaces and circular textured surfaces were compared and analyzed. It was found that the textured surface of valve plates can obviously improve friction efficiency under the same operating conditions. The square texture, especially, is the preferable shape, rather than the triangular texture and the circular texture, and the friction performance is at its best when the texture depths are between 20 $\mathsf{\mu }\mathrm{m}$ and 50 $\mathsf{\mu }\mathrm{m}$. The results provide a theoretical basis for the design and improvement of the valve plate.

The oil film between the cylinder block and valve plate represents one of the most critical designs in the rotating kit of an axial piston pump. The finite difference and relaxation iterative methods are used to solve the Reynolds equation of the oil film pressure for axial piston pump valve plate pair. Simulating the oil film thickness and pressure distribution. Analysing the change of kidney-shaped slot’s pressure to the load carrying capacity and offset load torque. The lubricating characteristics of wedge-shaped oil film and the maximum pressure under different working conditions are comparative analysis. The result shows that the oil film thickness changed when cylinder block is tilt relative to the valve plate and produced hydrodynamic effects. The load capacity and offset load torque of oil film increase with increasing inlet pressure. The structural parameter of the valve plate pair influenced lubrication characteristics.

This article presents a steady-state elastohydrodynamic lubrication model for the contact and sliding interface of an axial piston pump’s port plate pair. The wedge-shaped oil film thickness, pressure, viscosity, and elastic deformation distribution of the port plate pair were investigated by using the finite difference method. The elastohydrodynamic lubrication characteristics for different operating parameters and two materials of the port plate pair were analyzed for comparison. Existing conditions for the EHL were calculated, and variations in leakage and friction coefficients were investigated. The results show that the elastic deformation of the interface greatly influences the oil film’s overall performance, which is related to the material, inlet pressure, velocity, viscosity, and the minimum oil film thickness that determines the EHL. The deformation caused by oil film pressure greatly influences the model leakage and friction coefficient, especially when the deformation is equal to the oil film clearance.