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.

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.

Scaling the Speed Limitations for Axial-Piston Swash-Plate Type Hydrostatic Machines

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Noah D. Manring ◽  
Viral S. Mehta ◽  
Bryan E. Nelson ◽  
Kevin J. Graf ◽  
Jeff L. Kuehn
Keyword(s):  
Scaling Law ◽  
Simple Rule ◽  
Cylinder Block ◽  
Cube Root ◽  
Industry Data ◽  
Swash Plate ◽  
Axial Piston ◽  
Plate Type ◽  
New Machine

This paper proposes a scaling law for estimating the speed limitations for a family of axial-piston swash-plate type hydrostatic machines. The speed limitations for this machine are considered from three mechanical perspectives: (1) cylinder-block tipping, (2) cylinder-block filling, and (3) slipper-tipping. As shown in the results of this research, each speed limitation is scaled by the inverse of the cube root of the volumetric displacement for the new machine. In other words, small machines are shown to have a higher speed capacity than larger machines. By scaling a baseline machine using the scale laws that are presented here, a new machine may be produced that obeys a simple rule related only to the volumetric displacement of the new machine. Serendipitously, and perhaps most usefully, all three speed limitations obey the same rule! The speed limitations that are derived in this research are compared to existing industry data of currently scaled products and it is shown that the proposed scale laws correspond well with this data.

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.

Simulation of the Tribological Contacts in an Axial Piston Machine

2004 ◽  
Author(s):  
Michael Deeken
Keyword(s):  
Valve Plate ◽  
Cylinder Block ◽  
Simulation Tool ◽  
Test Rig ◽  
Research Project ◽  
Standard Unit ◽  
Swash Plate ◽  
Measurement Results ◽  
Axial Piston Machine ◽  
Axial Piston

A research project at the Institute for Fluid Power Drives and Controls (IFAS) sponsored a simulation tool, which was developed to analyze the tribological contacts in an axial piston machine. This paper describes the comparison between simulation and measurement results. The research project defined several objectives. These included extending the program for the tribological contacts, such as slipper/swash plate and cylinder block/valve plate pairings. Furthermore, the results of the simulations were to be verified by means of measurements conducted on the test rig and these were to be performed on a standard unit, if possible. The values to compare simulation and measurement must first be defined in order to meet these objectives.

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.

Tipping the Cylinder Block of an Axial-Piston Swash-Plate Type Hydrostatic Machine

1997 ◽  
Vol 122 (1) ◽  
pp. 216-221 ◽  
Author(s):  
Noah D. Manring
Keyword(s):  
Control Volume ◽  
Pressure Profile ◽  
Mechanical Analysis ◽  
Design Guidelines ◽  
Design Criterion ◽  
Valve Plate ◽  
Cylinder Block ◽  
Swash Plate ◽  
Axial Piston ◽  
Plate Type

Tipping the cylinder block within an axial-piston swash-plate type hydrostatic machine is a phenomenon that results in a momentary and sometimes permanent failure of the machine since the fluid communication between the cylinder block and the valve plate is instantaneously lost. The efforts of this research are to identify the physical contributors of this phenomenon and to specify certain design guidelines that may be used to prevent the failure of cylinder block tipping. This research begins with the mechanical analysis of the machine and presents a tipping criterion based upon the centroidal location of the force reaction between the cylinder block and the valve plate. This analysis is followed by the derivation of the effective pressurized area within a single piston bore and the cylinder block balance is defined based upon this result. Using standard control volume analysis, the pressure within a single piston bore is examined and it is shown that an approximate pressure profile may be used in place of the more complex representation for this same quantity. Based upon the approximate pressure profile a design criterion is presented which ensures that the pressures within the system never cause the cylinder block to tip. Furthermore, if this criterion is satisfied, it is shown that the worst tipping conditions exist when the system pressures are zero and therefore a criterion governing the design of the cylinder block spring is presented based upon the inertial forces that contribute to the tipping failure. [S0022-0434(00)00901-1]

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

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1674 ◽  
Author(s):  
Rene Chacon ◽  
Monika Ivantysynova
Keyword(s):  
Numerical Models ◽  
Optimization Procedure ◽  
Cylinder Block ◽  
Plate Interface ◽  
Piston Cylinder ◽  
Swash Plate ◽  
Physical Prototype ◽  
First Time ◽  
Axial Piston ◽  
Plate Type

This article presents a novel methodology to design swash plate type axial piston machines based on computationally based approach. The methodology focuses on the design of the main lubricating interfaces present in a swash plate type unit: the cylinder block/valve plate, the piston/cylinder, and the slipper/swash plate interface. These interfaces determine the behavior of the machine in term of energy efficiency and durability. The proposed method couples for the first time the numerical models developed at the authors’ research center for each separated tribological interface in a single optimization framework. The paper details the optimization procedure, the geometry, and material considered for each part. A physical prototype was also built and tested from the optimal results found from the numerical model. Tests were performed at the authors’ lab, confirming the validity of the proposed method.

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