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Energy Efficiency and Controllability of Fluid Power Systems 2018

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "F: Electrical Engineering".

Deadline for manuscript submissions: closed (31 March 2019) | Viewed by 107587

Special Issue Editor

Maha Fluid Power Research Center, School of Mechanical Engineering, Agricultural and Biological Engineering, Purdue University, 1500 Kepner dr., Lafayette, IN 47905, USA
Interests: fluid power systems; positive displacement machines; gear pumps; hydraulic control valves; aeration and cavitation in fluid power systems; analysis of noise generation and noise reduction in hydraulic components; electro-hydraulic systems; oscillation damping of load handling machines
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

After the success of the first Special Issue on “Energy Efficiency and Controllability of Fluid Power Systems” announced in 2016, the Editorial Board of Energies decided to have another special issue on the same topic for 2018. The Special Issue on “Energy Efficiency and Controllability of Fluid Power Systems” focuses on the recent advances of fluid power technology in a wide range of topics, including:

  • New approaches for the analysis, modeling and design of hydraulic and pneumatic components
  • New design solutions for hydrostatic pumps and motors
  • Hydrostatic and hydraulic hybrid transmissions
  • Control design methodologies and techniques for fluid power systems
  • Digital and switched fluid power systems
  • Reduction of oscillations and vibrations of fluid power machines
  • New system configurations to reduce fuel consumption and increase productivity of fluid power machines
  • Safety, reliability, fault analysis, diagnosis and prognostic of fluid power systems
  • Noise and vibration of fluid power components
  • Human scale applications of fluid power technology
  • Water hydraulics
  • Applications of fluid power in the field of renewable energy
  • Fluid power in manufacturing
  • Fluid power teleoperation and haptics
  • Fluid power in mobile and industrial robots
  • Environmental aspects of fluid power
  • Smart fluids and materials for fluid power systems

On behalf of the journal, I invite you to consider this Special Issue as an optimal platform to publish and disseminate your research approaches and results in the Fluid Power area.

We are looking forward to receiving your submissions.

Prof. Andrea Vacca
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

hydraulics, pneumatics, fluid power, hydrostatic pumps and motors, hydraulic control valves, digital hydraulics, water hydraulics, hydrostatic transmissions, hydraulic hybrids, hydraulic and pneumatic robots, noise and vibration, oscillation damping, control, energy efficiency, fuel consumption

Published Papers (22 papers)

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19 pages, 8497 KiB  
Article
Evaluation of the Hydro—Mechanical Efficiency of External Gear Pumps
by Barbara Zardin, Emiliano Natali and Massimo Borghi
Energies 2019, 12(13), 2468; https://doi.org/10.3390/en12132468 - 26 Jun 2019
Cited by 23 | Viewed by 4965
Abstract
This paper proposes and describes a model for evaluating the hydro-mechanical efficiency of external gear machines. The model is built considering and evaluating the main friction losses in the machines, including the viscous friction losses at the tooth tip gap, at the bearing [...] Read more.
This paper proposes and describes a model for evaluating the hydro-mechanical efficiency of external gear machines. The model is built considering and evaluating the main friction losses in the machines, including the viscous friction losses at the tooth tip gap, at the bearing blocks-gears gaps, at the journal bearings, and the meshing loss. To calculate the shear stress at each gap interface, the geometry of the gap has to be known. For this reason, the actual position of the gears inside the pump casing and consequent radial pressure distribution are numerically calculated to evaluate the gap height at the tooth tips. Moreover, the variation of the tilt and reference height of the lateral gaps between the gears and the pump bushings are considered. The shear stresses within the lateral gaps are estimated, for different lateral heights and tilt values. At the journal bearings gaps, the half Sommerfeld solution has been applied. The meshing loss has been calculated according to the suggestion of the International Standards. The hydro-mechanical efficiency results are then discussed with reference to commercial pumps experimentally characterized by the authors in a previous work. The average percentage deviation from experimental data was around 2%, without considering the most critical operating conditions (high delivery pressure, low rotational speed). The limits of this approach are also explained. Finally, the role of each source of loss is discussed, considering different operating conditions and two values of fluid viscosity. Lateral gap losses and meshing loss are much more relevant in determining the hydro-mechanical efficiency variation in the pump’s operating range, especially at a low delivery pressure. Moreover, while lateral gap losses increase with the rotational speed, the meshing loss shows the opposite behavior. The tooth tip gap losses are never as relevant, but they increase at high pressure. The journal bearings losses become comparable with the lateral and meshing ones at high delivery pressure values. Considering the pumps analyzed and the operating range of delivery pressure values and rotational speed values, the meshing loss made the mechanical efficiency vary in a percentage range of ±7%, with lateral losses in the range of about the ±15%, when also considering the extreme operating points (low speed, high pressure; high speed, low pressure). The weight of the lateral losses slightly reduced when we analyzed the higher temperature results, while the meshing losses slightly increased. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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26 pages, 2698 KiB  
Article
A Class of Energy Efficient Self-Contained Electro-Hydraulic Drives with Self-Locking Capability
by Lasse Schmidt, Søren Ketelsen, Morten Helms Brask and Kasper Aastrup Mortensen
Energies 2019, 12(10), 1866; https://doi.org/10.3390/en12101866 - 16 May 2019
Cited by 39 | Viewed by 3729
Abstract
Pump controlled and self-contained electro-hydraulic cylinder drives may improve energy efficiency and reduce installation space compared to conventional valve solutions, while being in line with the trend of electrification. The topic has gained increasing interest in industry as well as in academia in [...] Read more.
Pump controlled and self-contained electro-hydraulic cylinder drives may improve energy efficiency and reduce installation space compared to conventional valve solutions, while being in line with the trend of electrification. The topic has gained increasing interest in industry as well as in academia in recent years. However, this technology has failed to break through in industry on a broad scale, with the reason assumed to be lack of meeting industry requirements. These requirements include high drive stiffness enabling a large application range, and the ability to maintain cooling and filtration in required ranges, enabling proper reliability and durability. Furthermore, at this point the cost of realization of such drives is comparable only to high end valve drive solutions, while not providing dynamics on a similar level. An initiative to improve this technology in terms of a class of drives evolving around a hydraulic cylinder locking mechanism is proposed. The resulting class of drives generally rely on separate cylinder forward and return flow paths, allowing for fluid cooling and filtration as well as control of the drive stiffness. The proposed class of drives is analyzed regarding energy loss and recovery potential, a basic model based control design is realized, and the industrial feasibility of the drive class is considered. It is found that the proposed class of drives may be realized with standard components maintained in their design ranges at competitive costs compared to conventional valve solutions. Furthermore, it is found that pressure levels may be controlled in a proper way, allowing to produce either highly efficient operation or a high drive stiffness. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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25 pages, 4474 KiB  
Article
Dynamic Response of a Digital Displacement Motor Operating with Various Displacement Strategies
by Sondre Nordås, Michael M. Beck, Morten K. Ebbesen and Torben O. Andersen
Energies 2019, 12(9), 1737; https://doi.org/10.3390/en12091737 - 08 May 2019
Cited by 8 | Viewed by 3707
Abstract
Digital displacement technology has the potential of revolutionizing the performance of hydraulic piston pumps and motors. Instead of connecting each cylinder chamber to high and low pressure in conjunction with the shaft position, two electrically-controlled on/off valves are connected to each chamber. This [...] Read more.
Digital displacement technology has the potential of revolutionizing the performance of hydraulic piston pumps and motors. Instead of connecting each cylinder chamber to high and low pressure in conjunction with the shaft position, two electrically-controlled on/off valves are connected to each chamber. This allows for individual cylinder chamber control. Variable displacement can be achieved by using different displacement strategies, like for example the full stroke, partial stroke, or sequential partial stroke displacement strategy. Each displacement strategy has its transient and steady-state characteristics. This paper provides a detailed simulation analysis of the transient and steady-state response of a digital displacement motor running with various displacement strategies. The non-linear digital displacement motor model is verified by experimental work on a radial piston motor. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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20 pages, 5487 KiB  
Article
Low-Level Control of Hybrid Hydromechanical Transmissions for Heavy Mobile Working Machines
by L. Viktor Larsson, Liselott Ericson, Karl Uebel and Petter Krus
Energies 2019, 12(9), 1683; https://doi.org/10.3390/en12091683 - 04 May 2019
Cited by 3 | Viewed by 2886
Abstract
Fuel efficiency has become an increasingly important property of heavy mobile working machines. As a result, Hybrid Hydromechanical Transmissions (HMTs) are often considered for the propulsion of these vehicles. The introduction of hybrid HMTs does, however, come with a number of control-related challenges. [...] Read more.
Fuel efficiency has become an increasingly important property of heavy mobile working machines. As a result, Hybrid Hydromechanical Transmissions (HMTs) are often considered for the propulsion of these vehicles. The introduction of hybrid HMTs does, however, come with a number of control-related challenges. To date, a great focus in the literature has been on high-level control aspects, concerning optimal utilization of the energy storage medium. In contrast, the main topic of this article is low-level control, with the focus on dynamic response and the ability to realize requested power flows accurately. A static decoupled Multiple-Input-Multiple-Output (MIMO) control strategy, based on a linear model of a general hybrid HMT, is proposed. The strategy is compared to a baseline approach in Hardware-In-the-Loop (HWIL) simulations of a reference wheel loader for two drive cycles. It was found that an important benefit of the decoupled control approach is that the static error caused by the system’s cross-couplings is minimized without introducing integrating elements. This feature, combined with the strategy’s general nature, motivates its use for multiple-mode transmissions in which the transmission configuration changes between the modes. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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29 pages, 16187 KiB  
Article
Virtual Prototyping of Axial Piston Machines: Numerical Method and Experimental Validation
by Rene Chacon and Monika Ivantysynova
Energies 2019, 12(9), 1674; https://doi.org/10.3390/en12091674 - 02 May 2019
Cited by 23 | Viewed by 4654
Abstract
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, [...] Read more.
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. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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19 pages, 4740 KiB  
Article
Components Sizing and Performance Analysis of Hydro-Mechanical Power Split Transmission Applied to a Wheel Loader
by Shaoping Xiong, Gabriel Wilfong and John Lumkes, Jr.
Energies 2019, 12(9), 1613; https://doi.org/10.3390/en12091613 - 28 Apr 2019
Cited by 22 | Viewed by 4354
Abstract
The powertrain efficiency deeply affects the performance of off-road vehicles like wheel loaders in terms of fuel economy, load capability, smooth control, etc. The hydrostatic transmission (HST) systems have been widely adopted in off-road vehicles for providing large power density and continuous variable [...] Read more.
The powertrain efficiency deeply affects the performance of off-road vehicles like wheel loaders in terms of fuel economy, load capability, smooth control, etc. The hydrostatic transmission (HST) systems have been widely adopted in off-road vehicles for providing large power density and continuous variable control, yet using relatively low efficiency hydraulic components. This paper presents a hydrostatic-mechanical power split transmission (PST) solution for a 10-ton wheel loader for improving the fuel economy of a wheel loader. A directly-engine-coupled HST solution for the same wheel loader is also presented for comparison. This work introduced a sizing approach for both PST and HST, which helps to make proper selections of key powertrain components. Furthermore, this work also presented a multi-domain modeling approach for the powertrain of a wheel loader, that integrates the modeling of internal combustion (IC) engine, hydraulic systems, mechanical transmission, vehicle(wheel) dynamics, and relevant control systems. In this modeling, an engine torque evaluation method with a throttle position control system was developed to describe the engine dynamics; a method to express the hydraulic loss of the axial piston hydraulic pump/motor was developed for modeling the hydraulic transmission; and a vehicle velocity control system was developed based on altering the displacement of a hydraulic unit. Two powertrain models were developed, respectively, for the PST and HST systems of a wheel loader using MATLAB/Simulink. The simulation on a predefined wheel loader drive cycle was conducted on both powertrain models to evaluate and compare the performance of wheel loader using different systems, including vehicle velocity, hydraulic displacement control, hydraulic torque, powertrain efficiency, and engine power consumption. The simulation results indicate that the vehicle velocity controller developed functions well for both the PST and HST systems; a wheel loader using the proposed PST solution can overall save about 8% energy consumption compared using an HST solution in one drive cycle. The sizing method and simulation models developed in this work should facilitate the development of the powertrains for wheel loaders and other wheeled heavy vehicles. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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17 pages, 4017 KiB  
Article
Experimental Study on Fast and Energy-Efficient Direct Driven Hydraulic Actuator Unit
by Teemu Koitto, Heikki Kauranne, Olof Calonius, Tatiana Minav and Matti Pietola
Energies 2019, 12(8), 1538; https://doi.org/10.3390/en12081538 - 24 Apr 2019
Cited by 16 | Viewed by 2952
Abstract
In this experimental study, a Direct Driven Hydraulics (DDH) system of the closed circuit type was utilized for cyclic vertical actuation in heavy load material handling. The actuator was controlled by a speed-controlled fixed displacement pump. The high energy saving potential of this [...] Read more.
In this experimental study, a Direct Driven Hydraulics (DDH) system of the closed circuit type was utilized for cyclic vertical actuation in heavy load material handling. The actuator was controlled by a speed-controlled fixed displacement pump. The high energy saving potential of this system has been demonstrated in previous studies by the authors, but the dynamic characteristics of the ramped and P-controlled base system were considered unsatisfactory. Therefore, the system was implemented with an open-loop S-curve control that utilized a pre-calculated RPM (revolutions per minute) profile for the electric motor in order to realize a smooth actuator and load transition as a function of time. The results indicate that S-curve control is exceptionally well suited for producing a controlled lifting–lowering rapid motion with a heavy load, while still keeping the actuator chamber pressures within acceptable limits. In comparison, the motion produced by P-control was characterized by large unwanted pressure peaks together with velocity fluctuations and vibrations at the end of the stroke. Using a combination of S-curve control and hydraulic load compensation, a mass of 1325 kg could be moved 0.26 m in less than 0.5 s. The load compensation reduced the energy consumption by 64%, which would allow downsizing the electric motor and enable cost-efficient DDH implementation. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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18 pages, 9753 KiB  
Article
Active Pressure Ripple Control in Axial Piston Pumps through High-Frequency Swash Plate Oscillations—A Theoretical Analysis
by Paolo Casoli, Mirko Pastori, Fabio Scolari and Massimo Rundo
Energies 2019, 12(7), 1377; https://doi.org/10.3390/en12071377 - 10 Apr 2019
Cited by 25 | Viewed by 4479
Abstract
Pressure ripple has always been a major drawback in hydraulic circuits, since it is the main source of the overall noise emitted by the pump. This article presents a theoretical analysis on the active control of the pressure ripple in an axial piston [...] Read more.
Pressure ripple has always been a major drawback in hydraulic circuits, since it is the main source of the overall noise emitted by the pump. This article presents a theoretical analysis on the active control of the pressure ripple in an axial piston pump by properly moving the swash plate. The reduction of the pressure oscillations is studied in an active way and for this purpose a mathematical model of the whole pump has been developed, focusing on both the fluid dynamic aspects and the component dynamics. An experimental activity has been performed in order to validate the pump mathematical model. The results of the simulation, compared with the experimental data, highlight a suitable capability of the model to predict both the dynamics of the swash plate and the delivery pressure ripple. The validated model has been used for implementing an active control of the pressure ripple with the aim of properly modifying the machine displacement at high frequency in order to vary the instantaneous delivery flow rate and, consequently, the outlet pressure. The control strategy is grounded on moving the swash plate for modifying the motion law of the pistons through a servo valve integrated into the displacement control system. The simulations results have demonstrated that acting on the pump displacement control is possible to considerably reduce the amplitude of the pressure oscillations. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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18 pages, 4479 KiB  
Article
A Vibration Signal-Based Method for Fault Identification and Classification in Hydraulic Axial Piston Pumps
by Paolo Casoli, Mirko Pastori, Fabio Scolari and Massimo Rundo
Energies 2019, 12(5), 953; https://doi.org/10.3390/en12050953 - 12 Mar 2019
Cited by 34 | Viewed by 4815
Abstract
In recent years, the interest of industry towards condition-based maintenance, substituting traditional time-based maintenance, is growing. Indeed, condition-based maintenance can increase the system uptime with a consequent economic advantage. In this paper, a solution to detect the health state of a variable displacement [...] Read more.
In recent years, the interest of industry towards condition-based maintenance, substituting traditional time-based maintenance, is growing. Indeed, condition-based maintenance can increase the system uptime with a consequent economic advantage. In this paper, a solution to detect the health state of a variable displacement axial-piston pump based on vibration signals is proposed. The pump was tested on the test bench in different operating points, both in healthy and faulty conditions, the latter obtained by assembling damaged components in the pump. The vibration signals were acquired and exploited to extract features for fault identification. After the extraction, the obtained features were reduced to decrease the computational effort and used to train different types of classifiers. The classification algorithm that presents the greater accuracy with reduced features was identified. The analysis has also showed that using the time sampling raw signal, a satisfying accuracy could be obtained, which will permit onboard implementation. Results have shown the capability of the algorithm to identify which fault occurred in the system (fault identification) for each working condition. In future works, the classification algorithm will be implemented onboard to validate its effectiveness for the online identification of the typical incipient faults in axial-piston pumps. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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18 pages, 7101 KiB  
Article
Analysis of the Design of a Poppet Valve by Transitory Simulation
by Ivan Gomez, Andrés Gonzalez-Mancera, Brittany Newell and Jose Garcia-Bravo
Energies 2019, 12(5), 889; https://doi.org/10.3390/en12050889 - 07 Mar 2019
Cited by 14 | Viewed by 4555
Abstract
This article contains the results and analysis of the dynamic behavior of a poppet valve through CFD simulation. A computational model based on the finite volume method was developed to characterize the flow at the interior of the valve while it is moving. [...] Read more.
This article contains the results and analysis of the dynamic behavior of a poppet valve through CFD simulation. A computational model based on the finite volume method was developed to characterize the flow at the interior of the valve while it is moving. The model was validated using published data from the valve manufacturer. This data was in accordance with the experimental model. The model was used to predict the behavior of the device as it is operated at high frequencies. Non-dimensional parameters for generalizing and analyzing the effects of the properties of the fluid were used. It was found that it is possible to enhance the dynamic behavior of the valve by altering the viscosity of the working fluid. Finally, using the generated model, the influence of the angle of the poppet was analyzed. It was found that angle has a minimal effect on pressure. However, flow forces increase as angle decreases. Therefore, reducing poppet angle is undesirable because it increases power requirements for valve actuation. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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26 pages, 14771 KiB  
Article
Theoretical Investigation into the Ripple Source of External Gear Pumps
by Xinran Zhao and Andrea Vacca
Energies 2019, 12(3), 535; https://doi.org/10.3390/en12030535 - 08 Feb 2019
Cited by 26 | Viewed by 5625
Abstract
External gear pumps are among the most popular fluid power positive displacement pumps, however they often suffer of excessive flow pulsation transmitted to the downstream circuit. To meet the increasing demand of quiet operation for modern fluid power system, a better understanding of [...] Read more.
External gear pumps are among the most popular fluid power positive displacement pumps, however they often suffer of excessive flow pulsation transmitted to the downstream circuit. To meet the increasing demand of quiet operation for modern fluid power system, a better understanding of the ripple source of gear pumps is desirable. This paper presents a novel approach for the analysis of the ripple source of gear pumps based on decomposition into a kinematic component and a pressurization component. The pump ripple can be regarded as the superposition of the displacement solution and the pressurization solution. The displacement solution is driven by the kinematic flow, and it can be derived from the kinematic flow theory; instead, the pressurization solution can be approximated by overlapping the pressurization flow for a single displacement chamber. Furthermore, in this way the changes of these two components with modification of the delivery circuit are determined in both analytical and numerical ways. The result of this analysis provides a good interpretation of the pulsation simulated by a detailed lumped-parameter simulation model, thus showing its validity. The result also indicates that the response of two ripple sources to the change of the loading in the downstream hydraulic circuit is very different. These findings reveal the limitation of the traditional experimental method for determining the pump ripple, that new experimental methods which are more physics-based can be potentially formulated based on this work. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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21 pages, 7806 KiB  
Article
A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability
by Damiano Padovani, Søren Ketelsen, Daniel Hagen and Lasse Schmidt
Energies 2019, 12(2), 292; https://doi.org/10.3390/en12020292 - 18 Jan 2019
Cited by 63 | Viewed by 7095
Abstract
Self-contained electro-hydraulic cylinders have the potential to replace both conventional hydraulic systems and the electro-mechanical counterparts enhancing energy efficiency, plug-and-play installation, and reduced maintenance. Current commercial solutions of this technology are limited and typically tailor-made, whereas the research emphasis is primarily on cost [...] Read more.
Self-contained electro-hydraulic cylinders have the potential to replace both conventional hydraulic systems and the electro-mechanical counterparts enhancing energy efficiency, plug-and-play installation, and reduced maintenance. Current commercial solutions of this technology are limited and typically tailor-made, whereas the research emphasis is primarily on cost efficiency and power applications below five [kW]. Therefore, there is the need of developing more flexible systems adaptable to multiple applications. This research paper offers a contribution in this regard. It presents an electro-hydraulic self-contained single-rod cylinder with passive load-holding capability, sealed tank, capable of recovering energy, and scalable up to about eighty [kW]. The system implementation on a single-boom crane confirms its feasibility: The position tracking error remains well within ±2 [mm], oscillations are limited, and the overall energy efficiency is about 60 [%] during actuation. Concerning the passive load-holding devices, it is shown that both vented and non-vented pilot-operated check valves achieve the desired functioning and can hold the actuator position without consuming energy. Additional observations about the size and the arrangement of the load-holding valves are also provided. In conclusion, this paper demonstrates that the proposed self-contained cylinder can be successfully extended to several practical applications, especially to those characterized by overrunning external loads and the need of securing the actuator position. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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18 pages, 6616 KiB  
Article
Simulation of the Filling Capability in Vane Pumps
by Massimo Rundo, Giorgio Altare and Paolo Casoli
Energies 2019, 12(2), 283; https://doi.org/10.3390/en12020283 - 17 Jan 2019
Cited by 24 | Viewed by 4585
Abstract
In positive displacement pumps, the main volumetric loss at high speed is due to the incomplete filling of the variable volume chambers. The prediction of the limit speed and of the maximum flow rate delivered by a pump can be obtained only through [...] Read more.
In positive displacement pumps, the main volumetric loss at high speed is due to the incomplete filling of the variable volume chambers. The prediction of the limit speed and of the maximum flow rate delivered by a pump can be obtained only through Computational Fluid Dynamics (CFD) simulations, since the shape, the orientation, and the movement of the chambers with respect to the inlet volume must be considered, along with the non-uniform distribution of the gaseous phase, due to the dissolved air release. In this paper, the influence of different geometric parameters on the filling of a vane pump has been investigated through the commercial software PumpLinx®. At first, a model of a reference pump has been created and validated with different configurations of the suction flow area, then a simplified model has been used for assessing the influence of the geometry of the rotating assembly. It was found that a pump with a low ratio between the axial thickness and the diameter has a higher volumetric efficiency if the chambers are fed from one side only. Opposite behaviors were found in the case of pumps with small diameters and high thicknesses. Moreover, the filling could be improved by increasing the number of chambers, and by reducing the diameter of the rotor, even only locally. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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28 pages, 14925 KiB  
Article
Air Release and Cavitation Modeling with a Lumped Parameter Approach Based on the Rayleigh–Plesset Equation: The Case of an External Gear Pump
by Yash Girish Shah, Andrea Vacca and Sadegh Dabiri
Energies 2018, 11(12), 3472; https://doi.org/10.3390/en11123472 - 12 Dec 2018
Cited by 14 | Viewed by 4862
Abstract
In this paper, a novel approach for the simulation of cavitation and aeration in hydraulic systems using the lumped parameter method is presented. The presented approach called the Hybrid Rayleigh–Plesset Equation model is derived from the Rayleigh–Plesset Equation representative of bubble dynamics and [...] Read more.
In this paper, a novel approach for the simulation of cavitation and aeration in hydraulic systems using the lumped parameter method is presented. The presented approach called the Hybrid Rayleigh–Plesset Equation model is derived from the Rayleigh–Plesset Equation representative of bubble dynamics and overcomes several shortcomings present in existing lumped parameter based cavitation modeling approaches. Models based on static approximations do not consider the non-equilibrium effects of phase change on the system and incorrectly predict the system dynamics. On the other hand, the existing dynamic cavitation modeling strategies account for the non-equilibrium effects of phase change but express the evolution of phases through approximations of the Rayleigh–Plesset Equation (such as exclusion of nonlinear interactions in bubble dynamics), which often lead to physically unrealistic time-scales of bubble growth or dissolution. This paper presents a dynamic model for cavitation which is capable of predicting cavitation in hydraulic systems while preserving the nonlinear dynamics arising from the Rayleigh–Plesset Equation. The derived model determines the evolution of phases in terms of physically realizable parameters such as the bubble radius and the nuclei density, which can be estimated or determined experimentally. The paper demonstrates the effectiveness of the derived modeling approach with the help of numerical simulations of an External Gear Machine. Results from the simulations employing the proposed model are compared with an existing dynamic cavitation modeling approach and validated with experimental results over a range of dynamic parameters. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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25 pages, 7291 KiB  
Article
Scaling Criteria for Axial Piston Machines Based on Thermo-Elastohydrodynamic Effects in the Tribological Interfaces
by Lizhi Shang and Monika Ivantysynova
Energies 2018, 11(11), 3210; https://doi.org/10.3390/en11113210 - 19 Nov 2018
Cited by 11 | Viewed by 3998
Abstract
In lieu of reliable scaling rules, hydraulic pump and motor manufacturers pay a high monetary and temporal price for attempting to expand their production lines by scaling their existing units to other sizes. The challenge is that the lubricating interfaces, which are the [...] Read more.
In lieu of reliable scaling rules, hydraulic pump and motor manufacturers pay a high monetary and temporal price for attempting to expand their production lines by scaling their existing units to other sizes. The challenge is that the lubricating interfaces, which are the key elements in determining the performance of a positive displacement machine, are not easily scalable. This article includes an analysis of the size-dependence of these units with regard to the significant physical phenomena describing the behavior of their three most critical lubricating interfaces. These phenomena include the non-isothermal elastohydrodynamic effects in the fluid domain, and the heat transfer and thermal elastic deflection in the solid domain. The performance change due to size variation is found to be unavoidable and explained through fundamental physics. The results are demonstrated using a numerical fluid–structure–thermal interaction model over a wide range of unit sizes. Based on the findings, a guide to scaling swashplate-type axial piston machines such as to uphold their efficiency is proposed. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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21 pages, 8879 KiB  
Article
Bond Graph Simulation of Error Propagation in Position Estimation of a Hydraulic Cylinder Using Low Cost Accelerometers
by Antonio Algar, Esteban Codina and Javier Freire
Energies 2018, 11(10), 2603; https://doi.org/10.3390/en11102603 - 29 Sep 2018
Cited by 2 | Viewed by 3276
Abstract
The indirect calculation from acceleration of transversal displacement of the piston inside the body of a double effect linear hydraulic cylinder during its operating cycle is assessed. Currently an extensive effort exists in the improvement of the mechanical and electronic design of the [...] Read more.
The indirect calculation from acceleration of transversal displacement of the piston inside the body of a double effect linear hydraulic cylinder during its operating cycle is assessed. Currently an extensive effort exists in the improvement of the mechanical and electronic design of the highly sophisticated MEMS accelerometers. Nevertheless, the predictable presence of measurement errors in the current commercial accelerometers is the main origin of velocity and displacement measurement deviations during integration of the acceleration. A bond graph numerical simulation model of the electromechanical system has been developed in order to forecast the effect of several measurement errors in the use of low cost two axes accelerometers. The level of influence is assessed using quality indicators and visual signal evaluation, for both simulations and experimental results. The obtained displacements results are highly influenced by the diverse dynamic characteristics of each measuring axis. The small measuring errors of a simulated extremely high performance sensor generate only moderate effects in longitudinal displacement but deep deviations in the reconstruction of piston transversal movements. The bias error has been identified as the source of the higher deviations of displacement results; although, its consequences can be easily corrected. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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13 pages, 5786 KiB  
Article
Load-Sensing Pump Design to Reduce Heat Generation of Electro-Hydrostatic Actuator Systems
by Qun Chao, Junhui Zhang, Bing Xu, Yaoxing Shang, Zongxia Jiao and Zhihui Li
Energies 2018, 11(9), 2266; https://doi.org/10.3390/en11092266 - 29 Aug 2018
Cited by 15 | Viewed by 4735
Abstract
The electro-hydrostatic actuator (EHA) with variable pump displacement is considered to be a promising alternative to the currently popular EHA with fixed pump displacement in terms of heat reduction. This paper presents a load-sensing pump for the EHA which requires no additional power [...] Read more.
The electro-hydrostatic actuator (EHA) with variable pump displacement is considered to be a promising alternative to the currently popular EHA with fixed pump displacement in terms of heat reduction. This paper presents a load-sensing pump for the EHA which requires no additional power source and can adjust its volumetric displacement automatically with load pressure. A load-sensing pump prototype was developed and experiments were carried out on a test rig for it under different operating conditions. In addition, an experimental campaign was performed on an EHA test bench with a load-sensing pump and a fixed displacement pump. The results show that the load-sensing pump can decrease its volumetric displacement automatically at high pressure and thus reduce the heat generation of EHA system effectively. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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19 pages, 3605 KiB  
Article
A Methodology Based on Cyclostationary Analysis for Fault Detection of Hydraulic Axial Piston Pumps
by Paolo Casoli, Andrea Bedotti, Federico Campanini and Mirko Pastori
Energies 2018, 11(7), 1874; https://doi.org/10.3390/en11071874 - 18 Jul 2018
Cited by 22 | Viewed by 3750
Abstract
Condition monitoring has been an active area of research in many industrial fields during the last decades, particularly in fluid power systems. This paper presents a solution for the fault diagnosis of a variable displacement axial-piston pump, which is a critical component in [...] Read more.
Condition monitoring has been an active area of research in many industrial fields during the last decades, particularly in fluid power systems. This paper presents a solution for the fault diagnosis of a variable displacement axial-piston pump, which is a critical component in many hydraulic systems. The proposed methodology follows a data-driven approach including data acquisition and feature extraction and is based on the analysis of acceleration signals through the theory of cyclostationarity. An experimental campaign was carried out on a laboratory test bench with the pump in the flawless state and in faulty states. Different operating conditions were considered and each test was repeated several times in order to acquire a suitable population to verify data repeatability. Results showed the capability of the proposed approach of detecting a typical fault related to worn slippers. Future works will include tests in order to apply the approach to a wider set of faults and the development of a classifier for accurate fault identification. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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11 pages, 4373 KiB  
Article
Research on the Pressure Ratio Characteristics of a Swash Plate-Rotating Hydraulic Transformer
by Chongbo Jing, Junjie Zhou, Shihua Yuan and Siyuan Zhao
Energies 2018, 11(6), 1612; https://doi.org/10.3390/en11061612 - 20 Jun 2018
Cited by 9 | Viewed by 4019
Abstract
This paper presents a theoretical model and its experimental validation for the pressure ratio of a swash plate-rotating hydraulic transformer. The structure and principle of the new type of transformer are described. The swash plate-rotating type can reduce the throttling loss caused by [...] Read more.
This paper presents a theoretical model and its experimental validation for the pressure ratio of a swash plate-rotating hydraulic transformer. The structure and principle of the new type of transformer are described. The swash plate-rotating type can reduce the throttling loss caused by the valve plate in traditional hydraulic transformers. The theoretical model of the pressure ratio was derived based on the displacements functioning as the pump and motor in the transformer, accounting for the friction losses. A specific experimental setup including the prototype was established to validate the principle and pressure ratio of the machine. The results show that the transformer has a wider pressure range. The increase in pressure at port A and the rotating speed of the cylinder can reduce the pressure ratio slightly due to the torque loss. The present work indicates the useful potential of the swash plate-rotating hydraulic transformer. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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Review

Jump to: Research

44 pages, 15427 KiB  
Review
A Review of Gerotor Technology in Hydraulic Machines
by Pedro Javier Gamez-Montero, Esteve Codina and Robert Castilla
Energies 2019, 12(12), 2423; https://doi.org/10.3390/en12122423 - 24 Jun 2019
Cited by 38 | Viewed by 11671
Abstract
Over the years, numerous investigations have established the gerotor fundamentals. This work aims to provide a complete review of the literature from the last decade, focusing on the articles published in the past five years on gerotor technology in hydraulic machines. The report [...] Read more.
Over the years, numerous investigations have established the gerotor fundamentals. This work aims to provide a complete review of the literature from the last decade, focusing on the articles published in the past five years on gerotor technology in hydraulic machines. The report gives a catalogue of guidelines based on the trochoidal-envelope definition, a background analysis, the worldwide distribution of articles in each continent and country and the most frequently used keywords in the field. The paper identifies state-of-the-art research, and reports on current mainstream ideas. From the historical background, this literature review reports the current approaches in gerotor pumps (geometry and performance approaches, modeling and numerical simulations), orbital motors and new concepts. The report will serve as a guide and a directory for novel engineers working with gerotor technology in hydraulic machines. Another intention of this paper is to disseminate the works of the researchers who use this technology around the world, and to provide a scenario for future international collaboration. The paper gives an account of the disparity between academia and engineering applications. There is currently very little published literature on design and production methodologies for gerotor pumps and orbital motors. Hence, the future goal is to collect recommendations that combine academia and industry expertise to make better use of these extensive studies in the field. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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27 pages, 1252 KiB  
Review
Classification and Review of Pump-Controlled Differential Cylinder Drives
by Søren Ketelsen, Damiano Padovani, Torben O. Andersen, Morten Kjeld Ebbesen and Lasse Schmidt
Energies 2019, 12(7), 1293; https://doi.org/10.3390/en12071293 - 04 Apr 2019
Cited by 71 | Viewed by 7552
Abstract
Pump-controlled hydraulic cylinder drives may offer improved energy efficiency, compactness, and plug-and-play installation compared to conventional valve-controlled hydraulic systems and thus have the potential of replacing conventional hydraulic systems as well as electro-mechanical alternatives. Since the late 1980s, research into how to configure [...] Read more.
Pump-controlled hydraulic cylinder drives may offer improved energy efficiency, compactness, and plug-and-play installation compared to conventional valve-controlled hydraulic systems and thus have the potential of replacing conventional hydraulic systems as well as electro-mechanical alternatives. Since the late 1980s, research into how to configure the hydraulic circuit of pump-controlled cylinder drives has been ongoing, especially in terms of compensating the uneven flow requirements required by a differential cylinder. Recently, research has also focused on other aspects such as replacing a vented oil tank with a small-volume pressurized accumulator including the consequences of this in terms of thermal behavior. Numerous references describe the advantages and shortcomings of pump-controlled cylinder drives compared to conventional hydraulic systems or electro-mechanical drives. This paper presents a throughout literature review starting from the earliest concepts based on variable-displacement hydraulic pumps and vented reservoirs to newer concepts based on variable-speed electric drives and sealed reservoirs. By classifying these drives into several proposed classes it is found that the architectures considered in the literature reduce to a few basic layouts. Finally, the paper compares the advantages and shortcomings of each drive class and seek to predict future research tasks related to pump-controlled cylinder drives. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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15 pages, 3988 KiB  
Review
The Determination of the Theoretical Stroke Volume of Hydrostatic Positive Displacement Pumps and Motors from Volumetric Measurements
by Gijsbert Toet, Jack Johnson, John Montague, Ken Torres and José Garcia-Bravo
Energies 2019, 12(3), 415; https://doi.org/10.3390/en12030415 - 28 Jan 2019
Cited by 18 | Viewed by 3731
Abstract
This document presents a revised translation to the English language work developed more than 40 years ago by the first author. It further summarizes a common misinterpretation of the method and succinctly describes a graphical procedure to correctly determine the derived displacement volume [...] Read more.
This document presents a revised translation to the English language work developed more than 40 years ago by the first author. It further summarizes a common misinterpretation of the method and succinctly describes a graphical procedure to correctly determine the derived displacement volume of a pump or a motor. The original work contains a directive for the determination of the derived displacement volume of hydrostatic positive displacement pumps and motors, from volumetric (flow and speed) measurements. The procedure is based on the definition of the derived displaced volume, defined as: The volumetric flow pushed or admitted by hydrostatic positive displacement pumps and motors per (shaft) revolution, at zero internal and external leakage flow conditions. Full article
(This article belongs to the Special Issue Energy Efficiency and Controllability of Fluid Power Systems 2018)
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