Tailoring the Bore Surfaces of Water Hydraulic Axial Piston Machines to Piston Tilt and Deformation

Meike Ernst,Georg Enevoldsen,Monika Ivantysynova,Andrea Vacca

doi:10.3390/en13225997

Meike Ernst, Georg Enevoldsen + Show 2 more

Open Access

https://doi.org/10.3390/en13225997

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Journal: Energies	Publication Date: Nov 17, 2020
Citations: 8	License type: CC BY 4.0

Affiliation: Purdue University West Lafayette, Danfoss (Denmark)

Abstract

A novel virtual prototyping algorithm has been developed to design one of the most critical lubricating interfaces in axial piston machines of the swash plate type—the piston–cylinder interface—for operation with water as the working fluid. Due to its low viscosity, the use of water as a lubricant can cause solid friction and wear in these machines at challenging operating conditions. The prototyping algorithm compensates for this by tailoring the shape of the bore surface that guides the motion of each piston in this type of positive displacement machine to conform with the piston surface, taking into account both the piston’s tilt and its deformation. Shaping these surfaces in this manner can render the interface more conducive to generating hydrodynamic pressure buildup that raises its load-carrying capacity. The present work first outlines the structure of the proposed algorithm, then presents a case study in which it is employed to design a bore surface shape for use with two prototypes, one virtual and one physical—both modified versions of a 444 cc commercial axial piston pump. Experimental testing of the physical prototype shows it to achieve a significantly higher maximum total efficiency than the stock unit.

Highlights

Axial piston machines of swash plate design (APMSPD) are often the pumps/motors of choice for hydraulic systems in applications from agriculture to aerospace and as key elements in reverse osmosis and firefighting equipment
The TPGA exclusively generates surface shaping for implementation on the bores through which the pistons move, as opposed to surface shaping on the piston itself; this is because if such shaping is implemented on the piston running surface, the segment of the shape that falls within the limits of the lubricating interface changes with shaft angle, making it more difficult to maintain favorable performance over the course of the full shaft revolution
In order to minimize manufacturing complexity and cost, each bore surface shape generated by the TPGA is radially symmetric about the bore centerline, and can be described using a 2-D profile that specifies the shape of the bore surface in a lengthwise cross section over the guide length of the interface, lF

Summary

Introduction

Axial piston machines of swash plate design (APMSPD) are often the pumps/motors of choice for hydraulic systems in applications from agriculture to aerospace and as key elements in reverse osmosis and firefighting equipment They can be designed as variable displacement machines, can sustain high operating pressures (>300 bar), and, compared to other positive displacement machine designs, are highly efficient [1,2]. The present work aims to address some of the most prohibitive challenges that the use of water as a hydraulic fluid brings to the design of one of the most critical lubricating interfaces in such a unit This interface is a substantial contributor to the machine’s overall performance, in terms of both efficiency and component life. Summaries of the advantages of water are available in [3,4,5]

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