Decentralized Hydraulics for Micro Excavator

Zhang, Shuzhong; Minav, Tatiana; Pietola, Matti

doi:10.3384/ecp17144187

Cited by 23 publications

(22 citation statements)

References 7 publications

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“…Minav et al [16] investigated using a hydraulic ERS on a hydraulically operated forklift and reported an energy-saving efficiency of 45%. Zhang et al [23] investigated a direct drive system based on a decentralized hydraulics concept. Two fixed displacement pump/motors with a coaxial installed speed-controlled electric servo motor directly controlled the amount of fluid pumped into and out from the corresponding boom cylinder.…”

Section: Hydraulic Erssmentioning

confidence: 99%

A Novel Energy Recovery System Integrating Flywheel and Flow Regeneration for a Hydraulic Excavator Boom System

Zhao

Zhang

2020

Energies

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Implementing an energy recovery system (ERS) is an effective solution to improve energy efficiency for hydraulic excavators (HEs). A flywheel energy recovery system (FERS) is proposed based on this concept. A hydraulic pump motor (PM) is employed as the energy conversion component and a flywheel is used as the energy storage component. Since the pressure is low because the bucket is usually empty as the boom lowers, a relatively large PM should be used in the FERS. To overcome this drawback, a novel compound energy recovery system integrating flywheel and flow regeneration (FFERS) is proposed in this paper. The working principle of the system is analyzed in detail. The introduction of flow regeneration has two benefits; one is downsizing the displacement of PM and the other one is an extra improvement of energy efficiency. The primary parameters of both are matched based on a 4 t excavator. Compared with the PM used in the FERS, the PM displacement in the FFERS is reduced by 71%. For comparison, a general model that can operate in either the FERS mode or the FFERS mode is developed in AMESim. The modeling results show that the FFERS with a downsized PM contributes a 13% increase in energy recovery and reutilization efficiency (62%) as compared with the FERS.

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Section: Hydraulic Erssmentioning

confidence: 99%

A Novel Energy Recovery System Integrating Flywheel and Flow Regeneration for a Hydraulic Excavator Boom System

Zhao

Zhang

2020

Energies

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“…A structural analysis furthermore showed that the original boom structure is safe. In [76] lifting efficiencies ranging from 67% to 77% are simulated for the same excavator.…”

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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“…The hose model was updated with a pressure drop. The overall model is considered to be reliable, as it was validated in early studies in [16]; and in addition, the cylinder friction was validated with a micro-excavator [30].…”

Section: Modellingmentioning

confidence: 99%

Effect of Zonal Hydraulics on Energy Consumption and Boom Structure of a Micro-Excavator

et al. 2018

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This paper investigates the effect of extra weight caused by the Direct Driven Hydraulics (DDH) in a micro-excavator. These projects are investigating the implementation of zonal or decentralized hydraulics for non-road mobile machinery (NRMM) and stationary industrial applications. The benefit of DDH is the combination of electric and hydraulic technologies in a compact package compared to conventional hydraulics, which enables a reduction of potential leakage points, flexible tubing, and boosting of the system efficiency due to switching to direct pump control instead of a loss-generating conventional valve-based control. In order to demonstrate these benefits for the excavator case, this paper proposes a system model approach to assess and predict energy consumption of the zonal hydraulics approach implemented with DDH in various working cycles, complemented by a structural analysis. The finite element analysis utilized for this demonstrated that the extra weight and selected location of DDH units do not negatively affect the structure of the excavator. Simulation results demonstrated that the energy consumption is approximately 15% higher with extra weight added by the three DDH units. Although approximately 20% more regeneration energy is produced, taking into account the regeneration energy, the increases in energy consumption are about 12%.

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Decentralized Hydraulics for Micro Excavator

Cited by 23 publications

References 7 publications

A Novel Energy Recovery System Integrating Flywheel and Flow Regeneration for a Hydraulic Excavator Boom System

A Novel Energy Recovery System Integrating Flywheel and Flow Regeneration for a Hydraulic Excavator Boom System

Classification and Review of Pump-Controlled Differential Cylinder Drives

Effect of Zonal Hydraulics on Energy Consumption and Boom Structure of a Micro-Excavator

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