Friction Forces Within the Cylinder Bores of Swash-Plate Type Axial-Piston Pumps and Motors

1999 ◽  
Vol 121 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Noah D. Manring
Keyword(s):  
Mathematical Model ◽  
High Speed ◽  
Hydrodynamic Lubrication ◽  
Stribeck Curve ◽  
Friction Forces ◽  
Swash Plate ◽  
Axial Piston Machine ◽  
Cylinder Bore ◽  
Axial Piston ◽  
Plate Type

In this research, the friction within the cylinder bore of a swash-plate type axial-piston machine is examined. Unlike previous research, this work develops a mathematical model for the friction based upon lubricating conditions which are described by the well-known Stribeck curve. Furthermore, a test device is built for measuring the frictional characteristics during low pressure and low speed operation and these results are compared with the mathematical model. For high pressure and high speed considerations, a numerical investigation based upon the model is conducted and it is shown that the friction associated with a pumping piston is greater than the friction associated with a motoring piston. It is also shown that increased piston speeds usually reduce the friction within the cylinder bore; however, a “cross-over” condition may exist where the increased speed will actually increase the friction as a result of increased fluid shear. Furthermore, it is shown that speed changes have a more significant impact on motoring pistons as opposed to pumping pistons due to a difference in the location of hydrodynamic lubrication within the cylinder bore. It is noted that this difference exits due to the bore geometry and the direction of piston travel.

Advanced Virtual Prototyping of Axial Piston Machines

2016 ◽  
Author(s):  
Rene Chacon ◽  
Monika Ivantysynova
Keyword(s):  
Numerical Models ◽  
Virtual Prototyping ◽  
Valve Plate ◽  
Cylinder Block ◽  
Plate Interface ◽  
Design And Optimization ◽  
Swash Plate ◽  
Axial Piston Machine ◽  
Axial Piston ◽  
Plate Type

This paper explains how a combination of advanced multidomain numerical models can be employed to design an axial piston machine of swash plate type within a virtual prototyping environment. Examples for the design and optimization of the cylinder block/valve plate interface are presented.

Lubrication characteristics of the slipper–swash-plate interface in a swash-plate-type axial piston pump

2020 ◽  
pp. 095440622093294
Author(s):  
Xiangxu Meng ◽  
Chang Ge ◽  
Hongxi Liang ◽  
Xiqun Lu ◽  
Xuan Ma
Keyword(s):  
Hydrodynamic Lubrication ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Plate Interface ◽  
Load Pressure ◽  
Swash Plate ◽  
Lubrication Performance ◽  
Lubrication Characteristics ◽  
Axial Piston ◽  
Plate Type

An analytical approach based on a hydrodynamic lubrication model is presented to understand the bearing capacity, leakage, and friction moment of the slipper–swash-plate interface in a swash-plate-type axial piston pump. Furthermore, how the shaft speed, load pressure, and slipper attitude influence the lubrication performance of the interface is analyzed. The research shows that the slipper attitude has a significant effect on the pressure distribution. To improve the lubrication performance, a grooved sealing-land design is proposed, and the location and geometric parameters of the groove are analyzed. The results indicate that the optimal lubrication performance is achieved when the groove is 2.0–3.0 mm wide and 5–20 µm deep at its inner boundary.

Increasing the Power Density for Axial-Piston Swash-Plate Type Hydrostatic Machines

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Noah D. Manring ◽  
Viral S. Mehta ◽  
Bryan E. Nelson ◽  
Kevin J. Graf ◽  
Jeff L. Kuehn
Keyword(s):  
Power Density ◽  
Design Parameter ◽  
Cylinder Block ◽  
Allowable Stress ◽  
Swash Plate ◽  
Overhang Length ◽  
Axial Piston Machine ◽  
Axial Piston ◽  
Plate Type ◽  
Selection Of

Power density is an assumed attribute of an axial-piston swash-plate type hydrostatic machine. As such, very little research has been conducted to examine the nature and limit of this machine's power density and the literature is all but void of this important topic. This paper is being written to fill this void, and to provide a thorough analysis of the machine's power density. This paper is also aimed at identifying the most significant parameters that may be adjusted to increase the power density for a typical machine. As shown in this research, the power density of an axial-piston machine depends upon four dimensionless quantities that are characteristic of the machine's rotating group. As it turns out, the allowable stress for the cylinder block is the most sensitive parameter that may be adjusted for increasing the power density of this machine. It is further shown that increasing the machine's swash-plate angle, and reducing the minimum overhang length for the pistons, will have a significant impact on the power density as well. It is significant to note that altering the number of pistons in the design has essentially no impact on the power density of the machine and therefore the selection of this design parameter must be based upon other design objectives. In conclusion, it is shown in this paper that the power density of a typical machine may be increased by as much as 64% by altering a few of these parameters within a realistic realm of constraint.

The Critical Speed of Slipper Bearings in Axial Piston Swash Plate Type Pumps and Motors

2009 ◽  
Author(s):  
Massimo Borghi ◽  
Emiliano Specchia ◽  
Barbara Zardin ◽  
Enzo Corradini
Keyword(s):  
Critical Condition ◽  
Critical Speed ◽  
Radial Clearance ◽  
Stationary Model ◽  
Swash Plate ◽  
Machine Speed ◽  
Axial Piston Machine ◽  
Axial Piston ◽  
Plate Type

A stationary model is adopted to determine the critical condition for which the slipper moves away from the swashplate in an axial piston machine. The aim of the analysis is to find the critical speed, i.e. the value of the machine speed for which the slipper moves away from the swashplate; usually this condition may determine bad operating behaviour of the machine, although a retainer plate is used to maintain the slipper sufficiently near to the swashplate. The influences of the pressure transition in the cylinder, the swashplate angle and the radial clearance between piston and cylinder on the critical speed are depicted. Successively, the role of the position of the point of application of the resultant force due to the slipper-retaining plate contact is analyzed.

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