A Novel Positive Displacement Axial Piston Machine With Bent Cylinder Sleeves

2021 ◽  
Author(s):  
Swarnava Mukherjee ◽  
Antonio Masia ◽  
Mark Bronson ◽  
Lizhi Shang ◽  
Andrea Vacca
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Lumped Parameter Model ◽  
Cylinder Block ◽  
Element Analysis ◽  
Frictional Loss ◽  
Positive Displacement ◽  
Piston Cylinder ◽  
Lumped Parameter ◽  
Axial Piston Machine ◽  
Axial Piston

Abstract In this paper, an investigation of a novel positive displacement axial piston machine using a bent cylinder sleeve configuration is presented. The proposed design eliminates the side moments on the piston/cylinder interface, therefore, reduces the frictional loss and improves the total energy efficiency. A multi-physics elastohydrodynamic lubrication model was used to aid the design of the piston/cylinder and the cylinder block/port block interface. Then, a lumped parameter model was used to optimize the port block geometry. Groove geometry was chosen primarily to reduce flow ripple, tilting moment, and cavitation risk. To improve the housing stiffness, the lumped parameter model was combined with a finite element analysis. This ensured safety for the testing. In the end, steady-state experiments were performed on the prototype based on the ISO4409 normative. The unit’s speed was set to 500 rpm, then increased by 500 rpm until it reached 3000 rpm. The supply pressure was set to 20 bar. The outlet pressure was set to 70 bar at first, then increased by 50 bar until it reached 220 bar. The results show a remarkable volumetric efficiency with a peak of 99.5%. It is however noted that due to some of the issues with the initial iteration of the current design, there is a reduction in mechanical efficiency. The causes and possible future solutions to these issues are discussed in the manuscript.

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.

A Fast and Effective Method for the Optimization of the Valve Plate of Swashplate Axial Piston Pumps

2021 ◽  
Author(s):  
Gianluca Marinaro ◽  
Emma Frosina ◽  
Kim Stelson ◽  
Adolfo Senatore
Keyword(s):  
Numerical Model ◽  
Dynamic Pressure ◽  
Valve Plate ◽  
Lumped Parameter Model ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Flow Ripple ◽  
Lumped Parameter ◽  
Pressure Ripple ◽  
Axial Piston

Abstract This research presents a lumped parameter numerical model aimed at designing and optimizing an axial piston pump. For the first time, it has been shown that a lumped parameter model can accurately model axial piston pump dynamics based on a comparison with CFD models and experimental results. Since the method is much more efficient than CFD, it can optimize the design. Both steady-state and dynamic behaviors have been analyzed. The model results have been compared with experimental data, showing a good capacity in predicting the pump performance, including pressure ripple. The swashplate dynamics have been investigated experimentally, measuring the dynamic pressure which controls the pump displacement; a comparison with the numerical model results confirmed the high accuracy. An optimization process has been conducted on the valve plate geometry to control fluid-born noise by flow ripple reduction. The NLPQL algorithm is used since it is suitable for this study. The objective function to minimize is the well-known function, the Non-Uniformity Grade, a parameter directly correlated with flow ripple. A prototype of the best design has been realized and tested, confirming a reduction in the pressure ripple. An endurance test was also conducted. As predicted from the numerical model, a significant reduction of cavitation erosion was observed.

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

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5997
Author(s):  
Meike Ernst ◽  
Andrea Vacca ◽  
Monika Ivantysynova ◽  
Georg Enevoldsen
Keyword(s):  
Experimental Testing ◽  
Hydrodynamic Pressure ◽  
Operating Conditions ◽  
Surface Shape ◽  
Working Fluid ◽  
Total Efficiency ◽  
Positive Displacement ◽  
Piston Cylinder ◽  
Low Viscosity ◽  
Axial Piston

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.

Surface Deformations Enable High Pressure Operation of Axial Piston Pumps

2011 ◽  
Author(s):  
Matteo Pelosi ◽  
Monika Ivantysynova
Keyword(s):  
Film Thickness ◽  
Material Properties ◽  
Fluid Film ◽  
Cylinder Block ◽  
Steel Cylinder ◽  
Elastic Deformations ◽  
Piston Cylinder ◽  
Fluid Film Thickness ◽  
The Impact ◽  
Axial Piston

In this paper, a fully coupled fluid-structure interaction and thermal numerical model developed by the authors is used to demonstrate the impact of surface elastic deformations on the piston/cylinder fluid film thickness and on the overall axial piston pump rotating kit performance. The piston/cylinder interface is one of the most critical lubricating interfaces of axial piston machines. This interface fulfills simultaneously a bearing and sealing function under oscillating load conditions in a purely hydrodynamic regime. It represents one of the main sources of energy dissipation and it is therefore a key design element, determining axial piston machine efficiency. In the past years, the research group of the authors studied the impact of advanced micro surface design and fluid film thickness micro alteration in the piston/cylinder interface through extensive simulations and experiments. However, the numerical models used did not include the influence of surface elastic deformations, heat transfer and therefore material properties on the piston/cylinder interface behavior. Hence, the aim of this paper is to show the alterations on fluid film thickness and on the consequent coupled physical parameters due to the solid boundaries pressure and thermal surface elastic deformations. A simulation study considering two different material properties for the cylinder bores is performed, where a steel cylinder block and a steel cylinder block with brass bushings are separately studied. Piston/cylinder gap pressure field and coupled gap surface elastic deformations due to pressure and thermal loading are shown for the different materials. The impact of the different materials behavior on lubricating interface performance is 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.

Development of a new lumped-parameter model for vehicle side-impact safety simulation

2008 ◽  
Vol 222 (10) ◽  
pp. 1793-1811 ◽  
Author(s):  
A Deb ◽  
K C Srinivas
Keyword(s):  
Traffic Safety ◽  
Lumped Parameter Model ◽  
Side Impact ◽  
Lateral Impact ◽  
Highway Traffic ◽  
Element Analysis ◽  
National Highway Traffic Safety ◽  
Passenger Vehicles ◽  
Lumped Parameter ◽  
Lumped Masses

The current paper describes a simple and yet comprehensive lumped-parameter model (LPM) for simulating the National Highway Traffic Safety Administration (NHTSA) side-impact safety tests for passenger vehicles. The LPM includes new lumped masses, not previously reported in a single multibody model, for key vehicle side-structure systems identified with the help of an energy-based study conducted using explicit finite element analysis of two passenger vehicles. In addition to the vehicle side structure, lumped masses for the NHTSA side-impact barrier and ‘rest of vehicle’, the latter implying the mass of the vehicle minus the combined mass of the side-structure subsystems considered in the LPM, have been incorporated so that the total mass of the system corresponds to that of an actual vehicle—barrier system in a NHTSA side-impact test (Lateral Impact New Car Assessment Program (LINCAP) or FMVSS 214). The lumped masses are interconnected with elastic—plastic springs. A unique feature of the present model is the inclusion of two lumped side-impact dummies for obtaining predictions of the front and rear (thoracic trauma index (TTI)). The validity of the present LPM is established by performing LS-DYNA-based LINCAP simulations of two real-world vehicles, namely the Dodge Neon and Dodge Intrepid, and obtaining a reasonably good correlation of the computed structural and occupant responses as well as TTI (front and rear) with the corresponding test results reported by the NHTSA.

Novel Pressure Adaptive Piston Cylinder Interface Design for Axial Piston Machines

2019 ◽  
Author(s):  
Shanmukh Sarode ◽  
Lizhi Shang
Keyword(s):  
Interface Design ◽  
Interaction Model ◽  
Cost Effective ◽  
Operating Conditions ◽  
Pressure Effects ◽  
Cylinder Block ◽  
Design Solution ◽  
Piston Cylinder ◽  
Standard Design ◽  
Axial Piston

Abstract The paper presents a novel concept of a pressure adaptive piston/cylinder interface design for a swashplate type axial piston machine that uses a pressurized groove around the bushing inside the cylinder block. This groove is connected to the pump displacement chamber and it uses pressure deformations of the bushing to improve the sealing function of the piston/cylinder lubricating interface. Such a design concept is based on a groove design that is easy to manufacture, thus resulting in a cost-effective design solution. The proposed piston/cylinder interface design is simulated using a multi-domain simulation model developed by the authors’ research team. The tool is particularly suitable for the analysis of the internal gap flows, being based on a fully coupled fluid structure thermal interaction model, which calculates the non-isothermal gap fluid behavior considering solid body deformations due to temperature and pressure effects. The proposed solution is compared in simulation with respect to a standard design of an axial piston pump. The results indicate that the proposed pressure adaptive piston/cylinder interface is able to improve the sealing function of the piston/cylinder interface at different operating conditions. Therefore, the proposed novel design can be seen as a possible method to increase the energy efficiency of the current designs of swash plate units.

Numerical Modeling of a Helical External Gear Pump With Continuous-Contact Gear Profile: A Comparison Between a Lumped-Parameter and a 3D CFD Approach of Simulation

2018 ◽  
Author(s):  
Xinran Zhao ◽  
Andrea Vacca ◽  
Sujan Dhar
Keyword(s):  
Cfd Simulation ◽  
Good Description ◽  
Helical Gear ◽  
Lumped Parameter Model ◽  
Fluid Power ◽  
Gear Pump ◽  
Continuous Contact ◽  
Positive Displacement ◽  
Lumped Parameter ◽  
Flow Features

The concept of continuous-contact helical gear pumps (CCHGP) has been proposed and successfully commercialized in the recent past. Thanks to the continuous-contact rotor profile design and to the helical gear structure, this design eliminates the kinematic flow oscillation. This has important implications on the fluid borne noise generation, which is considered as one of the major sources of noise emissions and mechanical vibrations for positive displacement machines. Although the commercial success of the CCHGP concept, there is very little published studies about the underling physics at the basis of the functioning of this type of design. This is mostly due to the complexity of the fluid domain that characterize the functioning of CCHGP units. In this paper, a transient 3D CFD study is conducted for a reference CCHGP unit for high-pressure (up to 200 bar) fluid power applications. The results of the 3D CFD simulation are compared with those given by a lumped-parameter model developed at the Maha Fluid Power Research Center of Purdue University (USA), which was previously validated against experimental results. The results show how with a proper discretization of the fluid domain the CFD simulation approach can be used for the case of helical CCHGP units. Both models provide a good description of the main features of operation of the unit. The lumped parameter model is quicker, thus suitable for fast optimization studies. However, the CFD results not only can be used to support the main assumptions done on the lumped parameter model, they also permit to gain further insight on the operation of the CCHGP unit, particularly with respect to the flow features of the meshing process.

Thermal elastohydrodynamic lubrication simulation model for the tooth guidance contact of a single tooth gearbox under mixed friction conditions

2021 ◽  
pp. 135065012110143
Author(s):  
Michael Keller ◽  
Thomas Wimmer ◽  
Lars Bobach ◽  
Dirk Bartel
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Simulation Model ◽  
Elastohydrodynamic Lubrication ◽  
Element Analysis ◽  
Piston Cylinder ◽  
Mixed Friction ◽  
Single Tooth ◽  
The Finite Element Analysis ◽  
Dry Conditions

This article presents a simulation model for thermal elastohydrodynamic lubrication of the tooth guidance (piston/cylinder) contact of a single tooth gearbox. A finite-element analysis provides the boundary conditions for the thermal elastohydrodynamic lubrication simulation. The finite-element analysis under dry conditions allows calculating the macroscopic deformed contact surfaces for the elastohydrodynamic simulation model. The Hertzian deformation should be calculated in the presence of a lubricant and not with a dry finite-element analysis. A recently presented method, based on the finite-element submodeling technique, is extended to remove the Hertzian deformation of the macroscopic deformed lubrication gap from the dry finite-element analysis. A mixed friction with measured rough surfaces using the averaged flow model and mass conserving cavitation is implemented as well. An example shows how optimization of the gearbox by application of the simulation model is possible.

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