<p>Emission regulations and global policies to tackle climate change have forced industries and businesses to take measures to curb their impact on the environment. According to the United Nations Environment Program 2022 report on emissions [1], the transportation sector contributes to one-quarter of all energy-related CO2 emissions, and it is set to double by 2050. A recent report [2] suggests that off-road vehicles and equipment account for three-quarters of particulate matter and one-quarter of the nitrogen oxides emitted from mobile transportation sources in the US. The major challenge in decarbonizing or electrifying off-road machines is that they come in a wide range of sizes, weights, and functions, creating barriers to bringing down costs through economies of scale. Fluid power systems which are ubiquitous in these machines have been electrified in a compact and efficient manner to break even the costs of electrification. </p> <p>In off-road applications, where actuation systems heavily depend on hydraulics, there is a high demand for novel systems based on electric prime movers that can enable zero-carbon emission vehicles. An appropriate combination of electric prime movers and hydraulic machines commonly known as electrohydraulic units (EHUs) can help leverage the benefits of both these technologies. The integration of these two technologies in a single casing shaftless EHU can further maximize compactness and reduce cost. However, to achieve such an integrated EHU there is no standard procedure or recommended guidelines for equipment manufacturers owing to the interdisciplinary nature of the problem. </p> <p>This study proposes a generic design methodology to design electrohydraulic units (EHUs). As a starting point, a survey study was undertaken to compare different combinations of electric and hydraulic machines when designing an EHU. The different combinations were investigated for different operating drive cycles for their performance as well as other factors such as power-to-weight, cost, and the possibility of variable displacement. An axial piston machine (APM) was selected as a hydraulic machine (HM) to be integrated with a permanent magnet synchronous motor (PMSM) as the electric machine. </p> <p>The design methodology is demonstrated for an integrated electrohydraulic architecture with the APM housed inside the core of the PMSM. Such an architecture not only makes the overall integration much more compact but also allows for better thermal management of the EM. In such an architecture, the EM governs the overall power density of the integration and the total mass of the integration owing to inherent torque density differences. An EM design optimization is adopted for a predefined HM architecture to design the proposed EHU integration. The design optimization is used to quantify the effect of key EHU design specifications on the EM size and performance. EHU specifications such as sizing torque, operating voltage, aspect ratio, cooling efficacy, number of poles, and power-to-weight ratio have been studied to draw generic trends. These generic trends in the design specifications are used to outline clear guidelines on the impact of each of the EHU specifications for future EHU designers.</p> <p>Using the generic design trends, the design methodology is extended to size the EHU based on typical operating demands using the HM variable displacement, EM overload capability, and the EM flux weakening operation. These sizing studies allow the designers to size the EHU for the specific drive cycle operating demands and avoid oversizing the EHU. The EM flux weakening mode of operation allows the EM to be sized for a peak power level lower than the corner power of operation. The EM overload operation allows a reduction in the sustainable sizing torque lower than that of the maximum torque demand. The variable displacement in the HM can be used for improving overall EHU efficiency when selecting a low voltage or using a compact EM as well as to reduce the EM sizing torque. Two operation algorithms are proposed to define the EHU operation using variable displacement. Additionally, the sizing of a single EHU for multiple applications is also demonstrated. Such multi-utility EHU sizing can promote mass production and improve the rate of electrification in off-road machines.</p> <p>Finally, a prototype-tested EHU design based on the sizing study is demonstrated and the design considerations in such a design process are discussed. The prototype of the integrated EHU with a fixed displacement APM was able to reach the full capability of the reference APM. Thermal considerations are made on the EM sizing, to ensure the reliability of the designed EHU.  A novel self-sustained EHU architecture using the HM working fluid as a cooling fluid for the EM was designed. This was achieved by proposing a three-port valveplate design to divert part of the delivery stroke to cool the EM. A lumped parameter HM model was used to optimize this third port for an EHU prototype.</p>

<p>Energy conservation is a growing topic of research within various fields.  Digital Hydraulics is a division of fluid power that focuses on using on/off technology to improve the performance and efficiency of fluid power systems. One significant benefit of Digital Hydraulics is that it has enabled additional control over fluid power systems, which helps achieve component and system level improvements. Conventional radial and inline piston pumps use positive sealing valves, which mitigate leakage losses, compared to port plates commonly seen in variable displacement pumps. By using digitally controlled positive sealing valves on radial and inline piston pumps, leakage losses can be mitigated to develop a more efficient variable displacement pump. This work focuses on the design, modeling, and simulation of a mechanically actuated valving system developed for a commercially available radial piston pump. The design uses a ball screw actuation method to phase the cam during operation, changing the displacement. Using a modeling and simulation software, GT-SUITE, a simulation model was created for the digital pump that shows close correlation to the manufacturer’s data at high pressure. The parameters simulated, 50 – 200 bar, showed that the system could achieve a peak efficiency drop of approximately 11.0% from 87.0% to 76.0% from 100 – 25% displacement simulated at 200 bar and 500rpm. Compared to a typical variable displacement axial piston pump unit, the digital pump showed increased efficiencies across the bandwidth of 35-83% displacement, with a lower overall drop in efficiency across most of its operating conditions. In the comparison used, the pump is outside of its operating range and has not been optimized; thus, the simulation model created in this thesis will be used in the future to optimize the system and evaluate the system's potential performance and feasibility for future prototyping and testing as a proof of concept.  </p>

This thesis presents a technique termed Blended Shared Control, whereby a human operator's commands are merged with the commands of an electronic agent in real time to control a manipulator. A four degree-of-freedom hydraulic excavator is used as an application example, and two types of models are presented: a fully dynamic model incorporating the actuator and linkage systems suitable for high-fidelity user studies, and a reduced-order velocity-constrained kinematic model amenable for real-time optimization. Intended operator tasks are estimated with a recursive algorithm; the task is optimized in real time; and a command perturbation is computed which, when summed with the operator command, results in a lower task completion time. Experimental results compare Blended Shared Control to other types of controllers including manual control and haptic feedback. Trials indicate that Blended Shared Control decreases task completion time when compared to manual operation.

Orientador: Luiz Felipe Mendes de Moura / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T08:00:05Z (GMT). No. of bitstreams: 1 Rodrigues_AlexCristiano_M.pdf: 7859697 bytes, checksum: f1415c4744eaf2e3068a564f5afe9f1c (MD5) Previous issue date: 2009 / Resumo: Este trabalho apresenta a utilização de um modelo numérico para a determinação das forças hidrodinâmicas atuantes em comportas planas tipo vagão, utilizadas em obras de desvio de Usinas Hidrelétricas. Para isso foi utilizado o software comercial Fluent, onde foi gerado um modelo numérico tridimensional para diversas aberturas da comporta vagão ensecadeira, a qual é responsável pelo fechamento em definitivo do desvio. A validação dos resultados numéricos foi realizada através da comparação de dados de um modelo físico reduzido previamente estudado em laboratório, onde constatou-se a correta captação e interpretação dos fenômenos hidráulicos presentes, permitindo utilizar sua metodologia para aplicações em obras semelhantes. A vazão e seu respectivo coeficiente de descarga apresentaram diferenças médias da ordem de 8%, as pressões atuantes no fundo do canal apresentam diferenças máximas de 3,6%, enquanto que os esforços hidrodinâmicos registraram diferenças médias de 7%. As maiores variações foram observadas nas menores aberturas, quando a vazão é determinada pela comporta, e as velocidades são mais altas. A título de comparação dos fenômenos hidráulicos, foram levantados os dados pertinentes a outros três ensaios físicos de túneis de desvio. Estes resultados foram comparados com o ensaio numérico e a formulação teórica, indicando que esta última, de uma forma geral, possui resultados mais conservadores / Abstract: This work presents a proposal of a numerical model to determine the hydraulic forces acting in fixed wheel gates utilized in hydroelectric power plants. Fluent commercial CFD (computational fluid dynamics) software was used to generate a three-dimensional model of the hydraulic gate; different models were generated for different opening positions of the hydraulic gate. The results obtained from the numerical model were validated by comparing them to results obtained from a reduced model previously built in a hydraulic laboratory. When comparing these results it was possible to realize that the numerical model could well represent the hydraulic effects, allowing possibility of the methodology application for similar works. The volume flow and discharge coefficients presented a average variation of 8%; pressure distribution at the bottom of the canal presented a average variation of 3,6%; and hydraulic forces presented an average of 7% difference. Higher differences occurred at lowest openings, when the flow is mostly controlled by the gate and speed is higher. As a complement to the work, results from three other laboratory reduced models were compared to analytical proposals found in literature and numerical simulation results. These comparisons show that these analytical models are usually conservative / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

<div>Traction control (TC) systems have become quite common in on-road passenger vehicles in recent years. However, for vehicles in other applications, they are not as widely available.</div><div>This work presents a methodology for the proper design and implementation of a traction control system for heavy duty off-road machines, using a wheel loader as a reference vehicle.</div><div><br></div><div><div>A simulation model was developed, using standard vehicle dynamics constructs, including equations of motion and a description of the distribution of weight between the axles for different operating conditions. This model contains considerations for resistive forces acting on the machine implement, such as that generated by a work pile. The simulation also incorporates a detailed representation of the slip-friction characteristics between the vehicle tires and the road surface. One objective of this research was to model this interaction accurately, because the system traction behavior is dependent on it. Therefore, a series of tests was run using a state estimator to generate data on the slip-friction relationship at various ground conditions, and the results were incorporated into the simulation model. The dynamics of the machine braking system pressure were also modeled to give a more accurate description of the system response. The result is a mathematical model capable of accurately reproducing the behavior of the real-world system.</div></div><div><br></div><div><div>One of the primary goals of this work was the description of the traction control strategy itself, which should work as effectively and efficiently as possible. Several different aspects of the system were taken into consideration in generating this control structure. First, a relatively simple controller based on a PID control law was created. This controller was updated to account for peculiarities of the traction control system, as well as aspects like time delay. From there, more advanced controllers were created to address certain aspects of the system in greater detail. First, a self-tuning controller based on real-time optimization strategies was developed, to allow the controller to quickly adapt to changes in ground condition. Then, different nonlinear controllers were synthesized which were designed to address the theoretical behavior of the system. All of these controllers were simulated using the system model and then some were run in experiments to show their potential for improving system performance. To improve system efficiency, the machine drivetrain itself was also examined to develop a more efficient control algorithm. By designing a more efficient methodology, traction control congurations which had previously seen increases in fuel consumption of 16% were now able to actually reduce fuel usage by 2.6%.</div></div><div><br></div><div><div>Another main goal of this work was the development of a prototype system capable of implementing the formulated control strategies. The reference machine was modied so that the brakes could be controlled electronically and independently for implementation of the TC system. The vehicle was instrumented using a wide array of sensors, and estimation methodologies for accurately determining vehicle speed and implement forces were designed. The velocity estimator designed in this work is more accurate and more reliable than an industry standard sensor, which is important for traction control implementation. The implement force estimate was also quite accurate, achieving payload estimate errors of less than 2.5%, comparable to commercially-available measurement systems. This setup allowed for tests to be accurately compared, to assess the traction control performance.</div></div><div><br></div><div><div>With the objective of performing experiments on the traction control system, many tests were run to assess its capabilities in various situations. These tests included experiments for characterizing the vehicle behavior so that the simulation model could be updated to accurately reflect the physical machine performance. Another task for the experimental work was the generation of useful metrics for quantifying traction control performance. Laboratory experiments which were very controlled and repeatable were also run for generating data to improve the system model and for comparing traction control performance results side-byside. The test metrics proposed for these experiments provided for accurate, repeatable comparisons of pushing force, tire wear, and brake consumption. For each of these tests, the traction control system saw an increase in pushing force of at least 10% when compared with the stock machine, with certain operating conditions showing increases as high as 60%. Furthermore, every test case showed a decrease in wheel slip of at least 45% (up to 73% for some cases), which translates into increased tire longevity.</div></div><div><br></div><div><div>Other tests were conducted in the eld, designed to mimic the real-world operating conditions of the wheel loader. Various performance comparisons were made for different congurations in which traction control could provide potential benets. These included parameters for comparing overall vehicle performance in a typical truck loading cycle, such as tire wear, fuel consumption, and material moved per load. Initial results for this testing showed a positive result in terms of wheel slip reduction, but other performance parameters such as fuel consumption were negatively impacted. Therefore, the control structure was reexamined extensively and new methods were added to improve those results. The final control implementation saw a 12% reduction in tire slip, while also reducing fuel consumption by 2.6% compared to the stock system. These results show signicant potential for traction control as a technology for maximizing the performance output of construction machines.</div></div>

<p>Agricultural tractors make massive use of hydraulic control technology. Being fuel con-sumption a big concern for agricultural applications, tractors typically use the state-of-the-art technology, load-sensing (LS) architecture, to allow good controllability in systems withmultiple actuators while promoting higher energy efficiency. Several variants of LS systemshave been proposed over the years, and research on cost-effective methods to further increasetheir efficiency is of high interest for original equipment manufacturers (OEMs) and the fluidpower community. In this work, several energy-efficient solutions are proposed and demon-strated for the reference agricultural tractor hydraulic system, aiming at reducing the fuelconsumption and increasing the system efficiency, but without affecting the functionalityof the hydraulic control system. More importantly, facing the more stringent regulationson the CO2emission and the rising consciousness of a greener environment in society, bothindustry and academia have investigated the use of electricity as energy carrier and storage.This report also carries out the study on the possibility of electrification of the referencemachine, focusing on the auxiliary hydraulic supply to the planter.</p> <p>To begin with, the quantification of the energy loss within the hydraulic system representsan important step to drive the development of cost-effective solutions. For this purpose, acombined approach of simulation and experimental testing has been undertaken to character-ize the power distribution in the high-pressure circuit. After learning that the remote controlvalves are responsible for up to 25% of power loss in the system, two different energy-efficientsolutions are proposed on the tractor circuit. Both methods target at lowering the pumpdelivery pressure through incorporating electronic proportional pressure reducing valves (ep-PRVs). To support the development of the technology, the research takes into considerationthe circuit of a 400 hp tractor, simulation and experimental results show that among themain working conditions the solution can reach up to 15.6% power saving over the standardLS system.</p> <p>Moreover, the primary purpose of a tractor is to providing power to and controllingvarious implements. Most of their mechanical actuation is performed also with the electro-hydraulic fluid power system that is highly power-dense and versatile, but that has a low energy transmission efficiency. A new control approach of the hydraulic supply units thatpower the implement functions through the hydraulic remote is proposed, which switches thetraditional flow control methodology to an impressed pressure methodology. With a 16-rowplanter connected to the tractor understudy, a simulation model of the two vehicles is imple-mented and validated against experiments. Experiments on the proposed solutions appliedto the reference tractor and planter confirmed how an overall 38% efficiency improvementwas achieved during actual tests.</p> <p>On top of the IPSC strategy, more intelligent control algorithm is explored by proposinga new system architecture to fully incorporate both of the LS pumps with all of the EHRs,to achieve dynamic regrouping control (DRC) or static regrouping control (SRC). The DRCalgorithm determines the best supply configuration to all of the functions with minimumpower loss in time, which eventually leads to 44% power reduction compared to the base-line. On the other hand, the SRC algorithm targets at providing the best planter groupinglayout when connected to the tractor supply to contribute to least throttling losses duringrepresentative planting operations. The restuls from the SRC configuration can serve as asuggestive layout for the OEM when promoting such machines to the market.</p> <p>Last but not least, different scenarios of both selective purely electrification architectureand selective e-pump supply architecture are considered to discover the potential futuredirection of electrification to follow for the reference machine. From the power saving pointof view, replacing the fertilizer and vacuum hydraulic motors with the electric ones couldlead to 72% power reduction from the engine. However, more study on the cost analysiscould be useful to balance the saving and the cost added in the system.</p>

Even though the orifice is the simplest and most common control component in fluid power systems and cavitation is an already well-established topic in the scientific literature, the flow choking or saturation effect is largely overlooked in the common engineering practice. Most of the times the phenomenon is completely ignored, unless the peculiar hissing noise is observed at the test rig, giving a hint that something wrong is happening in the hydraulic system. Even then, the focus is just on the possible component damage induced by strong cavitation, while the functional implications – in terms of flow characteristic – are neglected. The objective of the paper is to study the phenomenon of flow saturation in hydraulic orifices to assess the formulation of the different critical cavitation numbers and cavitation indexes available from literature. For this reason, a full factorial design of experiments (DOE) is performed to determine the influence of three factors: orifice size, fluid temperature and upstream pressure. The testing is carried out on 5 orifice sizes at 3 different temperatures and 5 different upstream pressure levels. In each test, the downstream pressure is changed from 0 to the upstream pressure level, to sweep the available Δp range, both ascending and descending. In the results section an analysis of the experimental results is drawn, proposing a correlation between the critical cavitation index and the factors considered in the OE. To the authors’ knowledge, no systematic analysis, as the one here proposed, currently exists in literature for mineral oil applications.

Industrial hydraulics is often perceived as an old fashioned technology at the end of its innovation cyle. Despite its indiscussable technical benefits as well as its economical importance it is not seen as a promising future technology so that influencing people like to talk about and to promote. This results in disadvantages when it comes to customer choices comparing solutions, bidding processes, and – maybe most important – in a difficult position concerning the war for talents in the long run [... aus dem Text]

Machine builder integrate products from different suppliers in their machines or production lines. Today, most of the information is supplier-specific. The major challenge is to extract the necessary information from all products from different suppliers. [... aus dem Text]

Emissions of non-road machines are reduced by precise control of combustion process inside the engine and by after-treatment systems. One additional measure is the hybridization of the powertrain, which can be used to stabilize the engine load. This reduces harmful emissions because most nitrogen oxide emissions and particle emissions are related to sudden load and speed changes of the engine. In this study, four different hydraulic hybrid systems and their emission reduction potential are tested in one case study of a forwarder. The comparison study was done using a hardware-in-the-loop system (HIL) that consisted of a real-time simulation model, hydraulic secondary controlled loading system, real diesel engine, and emission measurement systems. The most efficient system (i.e., the system with the lowest fuel consumption) was the Four-pressure system. However, the difference between this system and the second-best system was negligible, and fuel consumption was about 40% less than with the reference system (a load-sensing system). Results showed that absolute emissions can be reduced by hybridization. Nitrogen oxide emissions were 15 25% lower and particulate matter emissions were 60 75% lower. The Four-pressure system had the lowest emissions. All studied hybrid systems resulted in reduction in fuel consumption and harmful emissions in the studied use case.