A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability
Abstract
:1. Introduction
- Ensure high energy efficiency (i.e., suitable hydraulic layouts are chosen),
- Achieve compactness (i.e., the built-in components are arranged ad hoc),
- Allow plug-and-play commissioning (i.e., the system only requires a wired connection to the electrical power source),
- Enhance flexible installation (i.e., a centralized hydraulic power supply is not required anymore, long hydraulic transmission lines are removed, and the closed-circuit layout characterized by a sealed reservoir can be tilted without leaking out fluid).
2. Literature Survey
- Variable-displacement hydraulic unit and fixed-speed prime mover. The actuator motion is controlled by varying the displacement of the hydraulic pump/motor. This approach is prevalent among multi-actuator machines (e.g., compact excavators [10]) since a unique charge pump supplies the displacement adjustment system of each unit. The prime mover can be either a combustion engine or an electric motor.
- Variable-displacement hydraulic unit and variable-speed prime mover. Both the electric prime mover and the hydraulic unit actively control the actuator motion [15].
3. The System under Investigation
3.1. System Architecture
3.2. Control Algorithm
4. Experimental Set-Up
5. System Modeling and Validation
5.1. The Dynamic Modeling of the System
5.2.Open-Loop Model Validation
6. Closed-Loop System Performance
7. Discussion about the Load-Holding Valves
7.1. Design of the Pilot-Operated Check Valves
7.2. Arrangement of the Pilot-Operated Check Valves
8. Conclusions
- A novel system architecture (i.e., a solution not found in literature) of an electro-hydraulic self-contained cylinder was presented and implemented on a test-bed.
- Experimental evidence proves the expected system functioning; the maximum position error ranges well within ±2 [mm] and the passive load-holding capability maintains the actuator position when needed.
- A dynamic model of the system was developed and experimentally validated; it provides a sizing and simulation tool for future implementations.
- Insight about key parameters was given; the overall system efficiency results highly satisfactory being about 60 [%] during actuation.
- It was shown that both vented and non-vented load-holding valves achieve the desired system functioning; however, choosing the vented design is advisable.
- The drastic limitations caused by an alternative arrangement of the load-holding pilot-operated check valves traced in the technical literature were highlighted.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
Abbreviations | |
4Q | Four quadrant operations |
ALH | Active load-holding |
AC | Anti-cavitation valve |
C | Actuator (i.e., hydraulic cylinder) |
CO | Cooler |
CV | Check valve |
EM | Electric servo-motor |
EV | 3/2 electro-valve |
F | Filter |
FF | Feedforward controller |
LH | Load-holding valve |
PLH | Passive load-holding |
POCV | Pilot-operated check valve |
RV | Pressure-relief valve |
SCC | Self-contained electro-hydraulic cylinder |
Symbols | |
a | Tuning parameter for the friction force of the actuator and of the crane joint |
AD | Pilot stage’s area inside the drain chamber of pilot-operated check valves |
Ap | Cylinder area on the bore-side |
Ar | Cylinder area on the rod-side |
AS | Poppet seat’s area of pilot-operated check valves |
Ax | Pilot stage’s area of pilot-operated check valves |
Cd | Discharge coefficient |
CH | Hydraulic capacitance |
D | Pump/motor displacement |
d | Seat diameter of pilot-operated check valves |
DRef | Displacement of the reference unit used to derive the loss model of the pump/motor |
ex | Position error of the hydraulic actuator |
FC | Coulomb force of the actuator and of the crane joint |
FF | Friction force of the actuator and of the crane joint |
FH | Hydraulic force of the actuator |
FS | Static friction force of the actuator and of the crane joint |
FS0 | Spring’s pre-load force of pilot-operated check valves |
fv | Viscous friction coefficient of the actuator and of the crane joint |
G(x) | Gravitational load acting on the actuator |
iA | Armature current of the servo-motor |
kC | Static friction force’s constant of the actuator and of the crane joint |
kI | Integral gain of the PI controller |
kP | Proportional gain of the PI controller |
kPF | Filter gain of the high-pass pressure filter |
kS | Spring stiffness of pilot-operated check valves |
kT | Torque constant of the servo-motor |
kv | Flow gain of check valves and of pressure-relief valves |
M(x) | Equivalent mass of the system acting on the actuator |
p | Pressure |
p1 | Pressure at the pump/motor port on the bore-side of the actuator |
p2 | Pressure at the pump/motor port on the rod-side of the actuator |
p3 | Actuator’s bore-side pressure |
p4 | Actuator’s rod-side pressure |
p5 | Accumulator pressure |
pAC,0 | Pre-charge pressure of the accumulator |
patm | Atmospheric pressure |
pc | Cracking pressure of check valves and of pressure-relief valves |
PC | Mechanical power at the load/actuator interface |
pD | Drain pressure in pilot-operated check valves |
PEM | Electrical power of the servo-motor |
pIn | Pressure at the inlet port of hydraulic valves |
pOut | Pressure at the outlet port of hydraulic valves |
px | Opening pilot pressure of pilot-operated check valves |
Q | Volume flow rate |
Qd | Differential actuator’s volume flow rate |
Qe,P | Effective flow rate of the pump/motor |
QEV | Volume flow rate through the electro-valve |
Qp | Actuator’s volume flow rate on the bore-side |
QPOCV | Flow rate through pilot-operated check valves |
Qr | Actuator’s volume flow rate on the rod-side |
QS | Flow losses of the pump/motor |
Te,P | Effective shaft torque of the pump/motor |
TS | Torque losses of the pump/motor |
uEM | Commanded servo-motor speed |
uEV | Command directed to the 3/2 electro-valve |
uFF | Commanded servo-motor speed from the feedforward term |
uLH | Load-holding enabler command |
uPF | Commanded servo-motor speed from the pressure feedback term |
VAC,0 | Effective accumulator gas volume |
V | Volume |
x | Piston position |
xMax | Actuator stroke |
ẋSet | Commanded piston velocity |
Greek symbols | |
y | Poppet lift of pilot-operated check valves |
β | Effective bulk modulus of the working fluid |
βA | Air’s bulk modulus |
βO | Oil’s bulk modulus |
γ | Adiabatic air constant |
Δp | Pressure differential |
εA | Volumetric air content of the working fluid |
εA,0 | Volumetric air content of the working fluid at atmospheric pressure |
ζ | Damping term used in the servo-motor’s transfer function |
ηSCC | Overall system efficiency of the self-contained cylinder |
ηv | Pump/motor’s volumetric efficiency |
λ | Scaling factor used in the loss model of the pump/motor |
ρ | Oil density |
τ | Time constant of the poppet dynamics in pilot-operated check valves |
ω | Shaft speed of the pump/motor |
ωn | Natural frequency used in the servo-motor’s transfer function |
ωPF | Cut-off frequency of the high-pass pressure filter |
Appendix A
Magnitude | Value | Unit | Magnitude | Value | Unit |
---|---|---|---|---|---|
LAG,x | 3.139 | [m] | LAB,y | 1.055 | [m] |
LAG,y | 0.064 | [m] | LMin | 0.772 | [m] |
LAC,x | 0.550 | [m] | g | 9.82 | [m/s2] |
LAC,y | 0.130 | [m] | m | 402 | [kg] |
LAB,x | 0.420 | [m] | J | 288.518 | [kg·m2] |
References
- Garcia, A.; Cusido, J.; Rosero, J.; Ortega, J.; Romeral, L. Reliable Electro-Mechanical Actuators in Aircraft. IEEE Aerosp. Electron. Syst. Mag. 2008, 23, 19–25. [Google Scholar] [CrossRef]
- Hagen, D.; Pawlus, W.; Ebbesen, M.K.; Andersen, T.O. Feasibility Study of Electromechanical Cylinder Drivetrain for Offshore Mechatronic Systems. Model. Identif. Control 2017, 38, 59–77. [Google Scholar] [CrossRef]
- Michel, S.; Weber, J. Electrohydraulic Compact-drives for Low Power Applications considering Energy-efficiency and High Inertial Loads. In Proceedings of the 7th FPNI PhD Symposium on Fluid Power, Reggio Emilia, Italy, 27–30 June 2012; pp. 1–18. [Google Scholar]
- Schneider, M.; Koch, O.; Weber, J. Green Wheel Loader—Improving fuel economy through energy efficient drive and control concepts. In Proceedings of the 10th International Fluid Power Conference, Dresden, Germany, 8–10 March 2016. [Google Scholar]
- Michel, S.; Weber, J. Prediction of the Thermo-Energetic Behaviour of an Electrohydraulic Compact Drive. In Proceedings of the 10th International Fluid Power Conference, Dresden, Germany, 8–10 March 2016. [Google Scholar]
- Michel, S.; Weber, J. Energy-efficient Electrohydraulic Compact Drives for Low Power Applications. In Proceedings of the Fluid Power Motion Control (FPMC 2012), Bath, UK, 12–14 September 2012; pp. 93–107. [Google Scholar]
- Weber, J.; Beck, B.; Fischer, E.; Ivantysyn, R.; Kolks, G.; Kunkis, M.; Lohse, H.; Lübbert, J.; Michel, S.; Schneider, M.; Shabi, L. Novel System Architectures by Individual Drives. In Proceedings of the 10th International Fluid Power Conference, Dresden, Germany, 8–10 March 2016. [Google Scholar]
- Hagen, D.; Padovani, D.; Ebbesen, M.K. Study of a Self-Contained Electro-Hydraulic Cylinder Drive. In Proceedings of the Global Fluid Power Society PhD Symposium (GFPS), Samara, Russia, 18–20 July 2018. [Google Scholar]
- Zimmerman, J.; Pelosi, M.; Williamson, C.; Ivantysynova, M. Energy Consumption of an LS Excavator Hydraulic System. In Proceedings of the ASME International Mechanical Engineering Congress & Exposition, Seattle, WA, USA, 11–15 November 2007. [Google Scholar]
- Zimmerman, J.; Busquets, E.; Ivantysynova, M. 40% Fuel Savings by Displacement Control Leads to Lower Working Temperatures—A Simulation Study and Measurements. In Proceedings of the 52nd National Conference on Fluid Power, Las Vegas, NV, USA, 23–25 March 2011. [Google Scholar]
- Minav, T.; Panu, S.; Matti, P. Direct-Driven Hydraulic Drive Without Conventional Oil Tank. In Proceedings of the ASME/BATH Symposium on Fluid Power & Motion Control, Bath, UK, 10–12 September 2014; pp. 1–6. [Google Scholar]
- Altare, G.; Vacca, A. A Design Solution for Efficient and Compact Electro-hydraulic Actuators. Procedia Eng. 2015, 106, 8–16. [Google Scholar] [CrossRef] [Green Version]
- Çalışkan, H.; Balkan, T.; Platin, B.E. A Complete Analysis for Pump Controlled Single Rod Actuators. In Proceedings of the 10th International Fluid Power Conference, Dresden, Germany, 8–10 March 2016; pp. 119–132. [Google Scholar]
- Cho, S.H.; Burton, R. Position control of high performance hydrostatic actuation system using a simple adaptive control (SAC) method. Mechatronics 2011, 21, 109–115. [Google Scholar] [CrossRef]
- Willkomm, J.; Wahler, M.; Weber, J. Potentials of Speed and Displacement Variable Pumps in Hydraulic Applications. In Proceedings of the 10th International Fluid Power Conference, Dresden, Germany, 8–10 March 2016; pp. 379–392. [Google Scholar]
- Pedersen, H.C.; Schmidt, L.; Andersen, T.O.; Brask, M.H. Investigation of New Servo Drive Concept Utilizing Two Fixed Displacement Units. JFPS Int. J. Fluid Power Syst. 2014, 8, 1–9. [Google Scholar] [CrossRef] [Green Version]
- Brahmer, B. Hybrid Drive using Servo Pump in Closed Loop. In Proceedings of the 8th International Fluid Power Conference, Dresden, Germany, 26–28 March 2012; pp. 93–102. [Google Scholar]
- Minav, T.; Bonato, C.; Sainio, P.; Pietola, M. Direct Driven Hydraulic Drive. In Proceedings of the 9th International Fluid Power Conference, Aachen, Germany, 24–26 March 2014. [Google Scholar]
- Schmidt, L.; Roemer, D.B.; Pedersen, H.C.; Andersen, T.O. Speed-Variable Switched Differential Pump System for Direct Operation of Hydraulic Cylinders. In Proceedings of the ASME/BATH 2015 Symposium on Fluid Power and Motion Control, Chicago, IL, USA, 12–14 October 2015. [Google Scholar]
- Schmidt, L.; Groenkjaer, M.; Pedersen, H.C.; Andersen, T.O. Position Control of an Over-Actuated Direct Hydraulic Cylinder Drive. Control Eng. Pract. 2017, 64, 1–14. [Google Scholar] [CrossRef]
- Ketelsen, S.; Schmidt, L.; Donkov, V.H.; Andersen, T.O. Energy Saving Potential in Knuckle Boom Cranes using a Novel Pump Controlled Cylinder Drive. Model. Identif. Control 2018, 39, 73–89. [Google Scholar] [CrossRef]
- Croke, S.; Herrenschmidt, J. More Electric Initiative Power-By-Wire Actuation Alternatives. In Proceedings of the National Aerospace and Electronics Conference, Dayton, OH, USA, 23–27 May 1994; pp. 1338–1346. [Google Scholar]
- Frischemeier, S. Electrohydrostatic Actuators for Aircraft Primary Flight Control—Types, Modelling and Evaluation. In Proceedings of the Fifth Scandinavian International Conference on Fluid Power (SICFP’97), Linköping, Sweden, 28–30 May 1997; pp. 1–16. [Google Scholar]
- Kazmeier, B. Energieverbrauchsoptimierte Regelung eines Elektrohydraulischen Linearantriebs Kleiner Leistung mit Drehzahlgeregeltem Elektromotor und Verstellpumpe; VDI-Verl: Düsseldorf, Germnay, 1998. [Google Scholar]
- Jun, L.; Yongling, F.; Guiying, Z.; Bo, G.; Jiming, M. Research on Fast Response and High Accuracy Control of an Airborne Brushless DC Motor. In Proceedings of the 2004 IEEE International Conference on Robotics and Biomimetics, Shenyang, China, 22–26 August 2004; pp. 807–810. [Google Scholar]
- van den Bossche, D. The A380 Flight Control Electrohydrostatic Actuators, Achievements and Lessons Learnt. In Proceedings of the 25th International Congress of the Aeronautical Sciences, Hamburg, Germany, 3–8 September 2006; pp. 1–8. [Google Scholar]
- Quan, Z.; Quan, L.; Zhang, J. Review of Energy Efficient Direct Pump Controlled Cylinder Electro-Hydraulic Technology. Renew. Sustain. Energy Rev. 2014, 35, 336–346. [Google Scholar] [CrossRef]
- Rahmfeld, R.; Ivantysynova, M. Energy Saving Hydraulic Actuators for Mobile Machines. In Proceedings of the 1st Bratislavian Fluid Power Symposium, Častá-Píla, Slovakia, 2–3 June 1998; pp. 177–186. [Google Scholar]
- Rahmfeld, R. Development and Control of Energy Saving Hydraulic Servo Drives for Mobile Systems; VDI-Verlag: Hamburg, Germany, 2002. [Google Scholar]
- Williamson, C.; Ivantysynova, M. Stability and Motion Control of Inertial Loads with Displacement Controlled Hydraulic Actuators. In Proceedings of the 6th FPNI-PhD Symposium, West Lafayette, IN, USA, 15–19 June 2010; pp. 499–514. [Google Scholar]
- Lodewyks, J. Differenzialzyliner im Geschlossenen Hydrostatischen Getriebe. Ölhydraulik und Pneumatik 1993, 186, 394–401. [Google Scholar]
- Lodewyks, J. Der Differentialzylinder im Geschlossenen Hydrostatischen Kreislauf; RWTH Aachen: Aachen, Germany, 1994. [Google Scholar]
- Vael, G.; Achten, P.; Potma, J. Cylinder Control with Floating Cup Hydraulic Transformer. In Proceedings of the Scandinavian International Conference on Fluid Power (SICFP), Tampere, Finland, 7–9 May 2003; pp. 175–190. [Google Scholar]
- Bloomquist, J.V.; Niemiec, A.J.; Vickers Inc. Electrohydraulic system and apparatus with bidirectional electric-motor/hydraulic-pump unit. U.S. Patent 5778671A, 19 March 1998. [Google Scholar]
- Zheng, J.; Zhao, S.; Wei, S. Application of Self-Tuning Fuzzy PID Controller for a SRM Direct Drive Volume Control Hydraulic Press. Control Eng. Pract. 2009, 17, 1398–1404. [Google Scholar] [CrossRef]
- Wei, S.; Zhao, S.; Zheng, J.; Zhang, Y. Self-Tuning Dead-Zone Compensation Fuzzy Logic Controller for a Switched-Reluctance-Motor Direct-Drive Hydraulic Press. Proc. Inst. Mech. Eng. Part I J. Syst. Control Eng. 2009, 223, 647–656. [Google Scholar] [CrossRef]
- Schneider, M.; Koch, O.; Weber, J.; Bach, M.; Jacobs, G. Green Wheel Loader –Development of an Energy Efficient Drive and Control System. In Proceedings of the 9th International Fluid Power Conference, Aachen, Germany, 24–26 March 2014. [Google Scholar]
- Schneider, M.; Koch, O.; Weber, J. Green Wheel Loader -Operating Strategy of an Energy Efficient Hybrid Drive Train; SAE Commercial Vehicle Engineering Congress, Paper 2014-01-2400M; Rosemont, IL, USA, 2014. [Google Scholar]
- Hewett, A.J. Hydraulic Circuit Flow Control. U.S. Patent 5,329,767A, 19 July 1994. [Google Scholar]
- Wang, L.; Book, W.J.; Huggins, J.D. A Hydraulic Circuit for Single Rod Cylinders. J. Dyn. Syst. Meas. Control 2012, 134, 011019. [Google Scholar] [CrossRef]
- Kenyon, R.L.; Scanderberg, D.; Nolan, M.E.; Wilkerson, W.D. Electro-Hydraulic Actuator. E.P. Patent 0,395,420A2, 31 October 1990. [Google Scholar]
- Quan, L. Current State, Problems and the Innovative Solution of Electro-hydraulic Technology of Pump Controlled Cylinder. Chin. J. Mech. Eng. 2008, 44, 87–92. [Google Scholar] [CrossRef]
- Zhang, D.; Li, W.; Lin, Y.; Bao, J. An Overview of Hydraulic Systems in Wave Energy Application in China. Renew. Sustain. Energy Rev. 2012, 16, 4522–4526. [Google Scholar] [CrossRef]
- Huang, J.; Quan, L.; Zhang, X. Development of a Dual-acting AxialPiston Pump for Displacement-Controlled System. Proc. Inst. Mech. Eng. Part B J. Eng. Manuf. 2014, 228, 606–616. [Google Scholar] [CrossRef]
- Wiens, T.; Bitner, D. An Efficient, High Performance and Low-Cost Energy Recovering Hydrostatic Linear Actuator Concept; In Proceedings of the BATH/ASME 2016 Symposium on Fluid Power and Motion Control, Bath, UK, 7–9 September 2016.
- Cleasby, K.G.; Plummer, A.R. A Novel High Efficiency Electrohydrostatic Flight Simulator Motion System. In Proceedings of the Fluid Power Motion Control (FPMC 2008), Bath, UK, 10–12 September 2008; pp. 437–449. [Google Scholar]
- Parker, H. Compact EHA—Electro-Hydraulic Actuators for High Power Density Applications. 2013. Available online: https://goo.gl/t2FMw2 (accessed on 17 December 2018).
- Sweeney, T.; Kubinski, P.T.; Anderson, D.J. Electro-hydraulic Actuator Mounting. U.S. Patent 8161742 B2, 24 April 2012. [Google Scholar]
- Rexroth, B. Advantages of Electrification and Digitalization Technology for Hydraulics. 2018. Available online: https://goo.gl/4G6Jxn (accessed on 17 December 2018).
- Bing, X.; Xiaoping, O.; Yang, H. Energy-Saving System Applying Pressure Accumulators for VVVF Controlled Hydraulic Elevators. In Proceedings of the ASME International Mechanical Engineering Congress, Washington, DC, USA, 15–21 November 2003. [Google Scholar]
- Altare, G.; Vacca, A.; Richter, C. A Novel Pump Design for an Efficient and Compact Electro-Hydraulic Actuator. In Proceedings of the 2014 IEEE Aerospace Conference, Big Sky, MT, USA, 2014. [Google Scholar]
- Jalayeri, E.; Imam, A.; Tomas, Z.; Sepehri, N. A throttle-less single-rod hydraulic cylinder positioning system: Design and experimental evaluation. Adv. Mech. Eng. 2015, 7, 1–14. [Google Scholar] [CrossRef]
- Çalışkan, H.; Balkan, T.; Platin, B.E. A Complete Analysis and a Novel Solution for Instability in Pump Controlled Asymmetric Actuators. J. Dyn. Syst. Meas. Control 2015, 137. [Google Scholar] [CrossRef]
- Sørensen, J.K.; Hansen, M.R.; Ebbesen, M.K. Numerical and Experimental Study of a Novel Concept for Hydraulically Controlled Negative Loads. Model. Identif. Control 2016, 37, 195–211. [Google Scholar] [CrossRef] [Green Version]
- Williamson, C.; Ivantysynova, M. The Effect of Pump Efficiency on Displacement-Controlled Actuator Systems. In Proceedings of the Eight Scandinavian International Conference on Fluid Power, Tampere, Finland, 21–23 May 2007. [Google Scholar]
- Kjelland, M.B.; Hansen, M.R. Numerical and Experiential Study of Motion Control Using Pressure Feedback. In Proceedings of the 13th Scandinavian International Conference on Fluid Power, Linköping, Sweden, 3–5 June 2013. [Google Scholar]
- Kjelland, M.B.; Hansen, M.R. Offshore Wind Payload Transfer Using Flexible Mobile Crane. Model. Identif. Control 2015, 36, 1–9. [Google Scholar] [CrossRef] [Green Version]
Methods | References |
---|---|
Hydraulic transformers | [31,32,33] |
Pilot-operated check valves | [10,28,34,35,36,37,38] |
Inverse shuttle valve | [3,39,40] |
3-port asymmetric pump | [41,42,43,44] |
Two cylinders in parallel | [45] |
Multiple fixed-displacement pumps | [6,16,17,18,19,20,21,46] |
Architectures | 4Q | PLH | References |
---|---|---|---|
Multiple fixed-displacement pumps | No | No | [27] |
Multiple fixed-displacement pumps | Yes | No | [11,20,21] |
Inverse shuttle valves | Yes | No | [3,5,6,13,53] |
Compact system | Yes 1 | Yes | [12,51] |
Electro-hydraulic actuator | No | Yes | [47,48,49] |
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Share and Cite
Padovani, D.; Ketelsen, S.; Hagen, D.; Schmidt, L. A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability. Energies 2019, 12, 292. https://doi.org/10.3390/en12020292
Padovani D, Ketelsen S, Hagen D, Schmidt L. A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability. Energies. 2019; 12(2):292. https://doi.org/10.3390/en12020292
Chicago/Turabian StylePadovani, Damiano, Søren Ketelsen, Daniel Hagen, and Lasse Schmidt. 2019. "A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability" Energies 12, no. 2: 292. https://doi.org/10.3390/en12020292
APA StylePadovani, D., Ketelsen, S., Hagen, D., & Schmidt, L. (2019). A Self-Contained Electro-Hydraulic Cylinder with Passive Load-Holding Capability. Energies, 12(2), 292. https://doi.org/10.3390/en12020292