Investigating the Condition Monitoring Potential of Oil Conductivity for Wear Identification in Electro Hydrostatic Actuators

2021 ◽  
Author(s):  
Yannick Duensing ◽  
Oliver Richert ◽  
Katharina Schmitz
Keyword(s):  
Condition Monitoring ◽  
Cylinder Block ◽  
Future Goals ◽  
Swash Plate ◽  
Error Location ◽  
Normative Requirements ◽  
Location Detection ◽  
High Dynamic ◽  
Status Signals ◽  
Axial Piston

Abstract To meet future goals of more electric airplanes conventional hydraulic airplane control systems, consisting of redundant centralized pumps within the airplane’s fuselage, need to be substituted for compact electro-hydraulic actuators (EHA). The capsulated architecture of EHAs results in higher safety due to separate hydraulic circuits, simple practicability of redundancy, decreased maintenance because of simplified error location detection as well as an overall reduction in weight and complexity of the airplane control system. Currently, EHAs are only used as backup devices as the reliability does not achieve normative requirements for a frontline application. Thus, recent studies aim to increase the reliability. The axial piston pump of current EHA is the source of most failures. High dynamic requirements and challenging operation points and environments result in wear of contact pairs such as swash plate/piston shoes, pistons/cylinder block and cylinder block/valve plate. In the scope of the project MODULAR at ifas one goal is to increase the robustness of the contact surfaces. A second goal addresses the topic of developing a condition monitoring approach to constantly track the pumps’ health status. Next to signals such as pressures and temperatures, acceleration and oil status signals describing the actual particle contamination are needed. In this contribution different methods of oil status detection are explained and the method of electric conductivity analysis for condition monitoring is further investigated. Filtered HLP46 is used and impurities in form of metallic powders are added. Furthermore, degraded oil of a disc-on-disc Tribometer test bench is measured and compared.

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.

DYNAMIC LOADS ON THE DRIVE SHAFT BEARINGS OF A SWASH PLATE AXIAL PISTON PUMP WITH CONICAL CYLINDER BLOCK

2004 ◽  
Vol 27 (4) ◽  
pp. 309-318
Author(s):  
M.K. Bahr Khalil ◽  
J.V. Svoboda ◽  
R.B. Bhat
Keyword(s):  
The Body ◽  
Drive Shaft ◽  
Dynamic Loads ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Static And Dynamic Characteristics ◽  
Swash Plate ◽  
Variable Displacement ◽  
Heavy Loads ◽  
Axial Piston

Variable displacement swash plate pumps are invariably used under conditions that involve heavy loads with variable flow demands. Swash plate pumps with conical cylinder blocks are now widely used in view of their good static and dynamic characteristics. However, drive shafts of these pumps experience dynamic loads due to the pressure forces transmitted through the body of the conical cylinder block to the supporting bearings. Dynamics of such rotating mechanism are quite interesting and should be considered in the design process of the drive shaft and the supporting bearings. A mathematical model is formulated for a 9-piston swash plate pump with conical cylinder block in order to evaluate the dynamic loads on the drive shaft. Results are presented and discussed.

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.

Dynamics Simulation Study of the Axial Piston Pump

2013 ◽  
Vol 706-708 ◽  
pp. 1323-1326
Author(s):  
Xiu Ye Wei ◽  
Hai Yan Wang
Keyword(s):  
Dynamics Simulation ◽  
Piston Pump ◽  
Cylinder Block ◽  
Kinematics Analysis ◽  
Matlab Simulation ◽  
Axial Piston Pump ◽  
Flow Pulsation ◽  
Swash Plate ◽  
Instantaneous Flow Rate ◽  
Axial Piston

Kinematics analysis based on the structure parameters of SCY14-1B type axial piston pump is taken in this paper, and the motion laws of the pistons relative to the cylinder block and the swash plate are got. A matlab simulation of the motion law is taken and the comparison between theoretical analysis and simulated results is very good. We get the following conclusions: The displacement, velocity and acceleration of the motion of the piston relative to the swash plate is simple harmonic.The motion trajectory of the piston relative to the swash plate is an ellipse. The swash plate angle has a significant effect on the motion of the piston, which will inevitably affect the instantaneous flow rate of the pump and flow pulsation coefficient.

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]

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