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]

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.

Lubrication Analysis of the Thrust Bearing in the Valve Plate of a Swash-Plate Type Axial Piston

2011 ◽  
Author(s):  
J. H. Shin ◽  
H. E. Kim ◽  
K. W. Kim
Keyword(s):  
Thrust Bearing ◽  
Valve Plate ◽  
Time Dependent ◽  
Fluid Film ◽  
Simulation Tool ◽  
Film Pressure ◽  
Swash Plate ◽  
Cylinder Barrel ◽  
Axial Piston ◽  
Plate Type

This application study of a swash-plate type axial piston pump was concerned about the hydrostatic lubrication characteristics of cylinder barrel and valve plate which are main rotating body and its opposite moving part respectively. A computer simulation was implemented to assess thrust bearing and mechanical sealing functions of the fluid film between cylinder barrel and valve plate. A new algorithm was developed to facilitate simultaneous calculations of dynamic cylinder pressure, 3 degree-of-freedom barrel motions considering inertia effect, and fluid film pressure assuming full fluid film lubrication regime. Using the simulation tool, force and moment balancing of cylinder barrel which is a key issue of piston pump design was analyzed. Time dependent fluid film pressure and thickness distributions for several given balance ratios were calculated. This analysis helps to decide appropriate balance ratio in the valve and cylinder barrel. Oil leakage flow and friction torque in the fluid film between cylinder barrel and valve plate were calculated as well and discussed in the viewpoint of energy loss. The results show that film thickness in plain surface is not high enough to bear the barrel and reduce power loss and that surface waviness which exists in actual sliding surfaces can have a positive effect on it. This simulation tool could also predict time dependent barrel motions due to simultaneous calculation algorithm. It has been known that cylinder barrel rotates with oscillation. Therefore average clearance, tilt angle, and azimuth angle were calculated for each time step and the results were discussed.

scholarly journals A Study on Design of Notches in Valve Plate of Swash Plate Type Axial Piston Pumps Operated Bi-directionally

2016 ◽  
Vol 13 (3) ◽  
pp. 39-46
Author(s):  
Sae Ryung Choi ◽  
Ill Yeong Lee ◽  
Sung Min Han ◽  
Jung Woo Shin
Keyword(s):  
Valve Plate ◽  
Axial Piston Pumps ◽  
Swash Plate ◽  
Axial Piston ◽  
Plate Type

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.

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.

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