An Investigation of the Impact of Micro Surface on the Cylinder Block/Valve Plate Interface Performance

Abstract

Lubricating gaps are the primary source of energy dissipation in axial piston machines of swash plate-type. One of these lubricating gaps is designated as the cylinder block/valve plate interface, and is one of the most critical design elements for this type of positive displacement machine. In the past, extensive work has been done at Maha Fluid Power Research Center both to model this interface and to study the effects of micro-surface shaping on the valve plate. This paper presents a more in-depth investigation into optimizing valve plate micro-surface shaping (both by altering the number and amplitude of waves) in order to achieve a fluid film thickness that compromises between leakage and torque loss, minimizes power loss in the cylinder block/valve plate interface, and maximizes machine efficiency.

A Review of High-Speed Electro-Hydrostatic Actuator Pumps in Aerospace Applications: Challenges and Solutions

“…Based on these models, some novel designs are proposed to reduce the energy losses and heat generation of these lubricating interfaces. For example, micro surface shapes are used on the movable parts and their stationary counterparts, such as waved, contoured or barreled pistons [153][154][155][156][157][158][159], concave cylinder bore [160], waved valve plate [161][162][163], and surface texturing for tribological interfaces [164][165][166][167][168]. These micro surface shapes can produce an additional microhydrodynamic pressure in the lubricating interfaces, thus improving the load-carrying capacity of the fluid film.…”

Barrel tipping in axial piston pumps and motors

“…In 2006 [13], it became clear that the deformation of the entire housing strongly affected the bearing interface between the barrel and the port plate. Most recent simulations also include the thermal expansion and deformation of the components [3,14,15], and the non-flatness and micro-geometry of the bearing surfaces [16,17]. The calculation of the dynamic micro-motion of the cylinder block has become a complex, multi-domain simulation effort, combining EHD with CFD-analysis, thermal analysis and multi-body mechanical analysis.…”

“…Yamaguchi [5,6] was one of the first to measure the gap height and tipping of a barrel-like structure running on a valve plate. Other experimental research in this area has been performed by Ivantysynova and her team [3,4,[14][15][16]20], Bergada, et al [21][22][23], Wegner, et al [24,25], Shin, et al [17], Han, et al [26] and Zhang, et al [27]. Most of these studies measured a gap height between 0 and 20 µm.…”

Virtual Prototyping of Axial Piston Machines: Numerical Method and Experimental Validation

“…These models capture various physical phenomena including the micro-motion of the cylinder block, non-isothermal flow in the lubricating gap, and pressure and thermal elastic deformation on the solid bodies. These TEHD models have been used to investigate micro-surfacing to increase the load carrying ability of the lubricating interfaces [26][27][28][29] on axial piston machines.…”