Energy Saving Potential in Knuckle Boom Cranes using a Novel Pump Controlled Cylinder Drive

Ketelsen, Søren; Schmidt, Lasse; Donkov, Viktor Hristov; Andersen, Torben Ole

doi:10.4173/mic.2018.2.3

Cited by 17 publications

(17 citation statements)

References 12 publications

(17 reference statements)

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“…Experimental verification shows energy efficiencies ranging from 18% to 51% in four-quadrant operation. A simulation study shows an energy saving potential of 60% compared to a conventional valve-controlled system for actuation of a two-link middle-sized knuckle boom crane for a representative load cycle [79]. The two pumps may also be configured in a closed-circuit architecture, as seen in Figure 6b, offering smaller pump sizes compared to open-circuit architectures at the expense of requiring a closed-circuit pump.…”

Section: Class B-variable-speed Single Prime Mover With Multiple Pumpsmentioning

confidence: 99%

Classification and Review of Pump-Controlled Differential Cylinder Drives

et al. 2019

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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. IntroductionWith an increased industrial focus on energy efficiency, plug-and-play installation, and compactness, conventional valve-controlled hydraulic cylinder drives are increasingly being replaced by electro-mechanical alternatives, such as roller or ball screws [1], especially for small power classes. This happens despite the well-known advantages of hydraulic linear actuation such as large force/power densities, reliability, and robustness. Hydraulic actuation is, however, still the preferred solution for many applications such as industrial presses, large mobile machinery, crane manipulators, primary aircraft control etc. [2][3][4]. Among other reasons this is due to certain limitations for the electro-mechanical alternatives, such as limited reliability (e.g., shock loads damage), the difficulties of implementing overload/failure protection and/or limited force capabilities [5][6][7]. To strengthen the position regarding these applications and to make hydraulic cylinder drives competitive with electro-mechanical drives for low power applications, there is a need to enhance both the energy efficiency and the overall flexibility of hydraulic cylinder drives.The flexibility of a hydraulic system may be related to how power is being distributed between the prime mover and the actuator(s). As illustrated in Figure 1, at least three different power distribution topologies exist: hydraulic, mechanical, and electrical distribution.

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Section: Class B-variable-speed Single Prime Mover With Multiple Pumpsmentioning

confidence: 99%

Classification and Review of Pump-Controlled Differential Cylinder Drives

et al. 2019

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“…Similar to the variable speed approach with a single fixed displacement pump, this approach also suffers from low pressure operation [25], inducing a low drive stiffness, resulting in the same issues as discussed above. This may be improved by the inclusion of an additional pump, enabling the possibility to maintain the lower pressure at a certain level in the majority of the operating range [26][27][28].…”

Section: Variable Speed Approach With Two Fixed Displacement Pumpsmentioning

confidence: 99%

A Class of Energy Efficient Self-Contained Electro-Hydraulic Drives with Self-Locking Capability

Schmidt

Ketelsen

Brask³

et al. 2019

Energies

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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.

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“…Moreover, the lack of experimental comparisons in terms of energy consumption and efficiency between SCCs and conventional solutions for load-carrying applications is evident. Only a limited number of simulation studies applying the SCC technology to load-carrying applications and investigating the energy-saving potentials compared to existing hydraulic systems were identified [26,27].…”

Section: Introductionmentioning

confidence: 99%

A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 2: Energy Efficiency

2019

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This research paper presents the second part of a comparative analysis of a novel self-contained electro-hydraulic cylinder with passive load-holding capability against a state of the art, valve-controlled hydraulic system that is typically used in load-carrying applications. After addressing the control design and motion performance in the first part of the study, the comparison is now focused on the systems’ energy efficiency. It is experimentally shown that the self-contained solution enables 62% energy savings in a representative working cycle due to its throttleless and power-on-demand nature. In the self-contained drive, up to 77% of the energy taken from the power supply can be used effectively if the recovered energy is reused, an option that is not possible in the state of the art hydraulic architecture. In fact, more than 20% of the consumed energy may be recovered in the self-contained system during the proposed working cycle. In summary, the novel self-contained option is experimentally proven to be a valid alternative to conventional hydraulics for applications where passive load-holding is required both in terms of dynamic response and energy consumption. Introducing such self-sufficient and completely sealed devices also reduces the risk of oil spill pollution, helping fluid power to become a cleaner technology.

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Energy Saving Potential in Knuckle Boom Cranes using a Novel Pump Controlled Cylinder Drive

Cited by 17 publications

References 12 publications

Classification and Review of Pump-Controlled Differential Cylinder Drives

Classification and Review of Pump-Controlled Differential Cylinder Drives

A Class of Energy Efficient Self-Contained Electro-Hydraulic Drives with Self-Locking Capability

A Comparison Study of a Novel Self-Contained Electro-Hydraulic Cylinder versus a Conventional Valve-Controlled Actuator—Part 2: Energy Efficiency

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