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.

<p>Dagens värderings och redovisningssystem av spelare uppvisar brister när det gäller att utläsa en klubbs egentliga värde i en balansräkning. Spelarna får idag redovisas enligt en av de två alternativ som det Svenska Fotbollsförbundet ställt upp. Alternativen går dock främst ut på att periodisera kostnader, inte att spegla ett rättvisande värde av klubben.</p><p>Begreppet ”verkligt värde” är aktuellt inom dagens redovisning. IASB arbetar med att harmonisera redovisningen världen över och i deras arbete spelar begreppet en viktig roll. Inom flera olika tillgångsslag ges idag möjligheten till att värdera och redovisa en tillgång till dess verkliga värde, dess marknadsvärde. Skulle inte det på sikt kunna implementeras för fotbollsspelare?</p><p>Vårt syfte är att ge svar på om och i så fall hur en värdering till marknadsvärde skulle fungera. Vi ifrågasätter om dagens system kommit till som en tillfällig men fungerande lösning i väntan på något bättre. Vi har ställt upp tre frågor som ständigt fanns med oss under arbetsprocessen:</p><p>♦ Skulle en värdering till marknadsvärden kunna fungera som substitut till nu gällande regelverk för att ge en mer rättvisande bild av klubbarnas egna kapital?</p><p>♦ Hur bemöts detta av verkligheten, av SvFF samt de allsvenska klubbarna?</p><p>♦ Är dagens gällande redovisningsmetoder de bästa möjliga lösningarna?</p>

Dagens värderings och redovisningssystem av spelare uppvisar brister när det gäller att utläsa en klubbs egentliga värde i en balansräkning. Spelarna får idag redovisas enligt en av de två alternativ som det Svenska Fotbollsförbundet ställt upp. Alternativen går dock främst ut på att periodisera kostnader, inte att spegla ett rättvisande värde av klubben. Begreppet ”verkligt värde” är aktuellt inom dagens redovisning. IASB arbetar med att harmonisera redovisningen världen över och i deras arbete spelar begreppet en viktig roll. Inom flera olika tillgångsslag ges idag möjligheten till att värdera och redovisa en tillgång till dess verkliga värde, dess marknadsvärde. Skulle inte det på sikt kunna implementeras för fotbollsspelare? Vårt syfte är att ge svar på om och i så fall hur en värdering till marknadsvärde skulle fungera. Vi ifrågasätter om dagens system kommit till som en tillfällig men fungerande lösning i väntan på något bättre. Vi har ställt upp tre frågor som ständigt fanns med oss under arbetsprocessen: ♦ Skulle en värdering till marknadsvärden kunna fungera som substitut till nu gällande regelverk för att ge en mer rättvisande bild av klubbarnas egna kapital? ♦ Hur bemöts detta av verkligheten, av SvFF samt de allsvenska klubbarna? ♦ Är dagens gällande redovisningsmetoder de bästa möjliga lösningarna?

Increased demands on fuel-efficient propulsion motivate the use of complex hybrid hydromechanical transmissions in heavy construction machines. These transmissions offer attractive fuel savings but come with an increased level of complexity and dependency on computer-based control. This trend has increased the use of computer-based simulations as a cost-effective alternative to hardware prototyping when developing and testing control strategies. Hardware-In-the-Loop (HWIL) simulations that combine physical and virtual model representations of a system may be considered an attractive compromise that combine the benefits of these two concepts. This paper explores how HWIL simulations may be used to evaluate powertrain control strategies for hybrid hydromechanical transmissions. Factors such as hardware/software partitioning and causality are discussed and applied to a test rig used for HWIL simulations of an example transmission. The results show the benefit of using HWIL simulations in favour of pure offline simulations and prototyping and stress the importance of accurate control with high bandwidth in the HWIL interface.

Due to the robustness and flexibility of hydraulic components, hydraulic control systems are used in a wide range of applications under various environmental conditions. However, the coverage of this broad field of applications often comes with a loss of performance. Especially when conditions and working points change often, hydraulic control systems cannot work at their optimum. Flexible electronic controllers in combination with techniques from the field of machine learning have the potential to overcome these issues. By applying a reinforcement learning algorithm, this paper examines whether learned controllers can compete with an expert-tuned solution. Thereby, the method is thoroughly validated by using simulations and experiments as well.

Climate change and economic opportunities motivate investigating electric distributed power for working hydraulics in non-road mobile machinery (NRMM) instead of conventional hydraulics. This recent method allows significant energy savings in hydraulic systems, which was demonstrated previously by many independent studies. In this study, zonal hydraulics (as electrically distributed) are realized with direct driven hydraulics drive (DDH) units. Unlike conventional hydraulic drives the DDH units are disconnected from the engine (main prime mover) and distributed throughout the system. In a DDH unit, a single fixed displacement pump/motor with a speed-controlled electric servomotor directly controls the flow. The aim of this paper is to determine functionality of this new two-cylinder DDH-system in a lifting work cycle (or a swerve motion of the work machine). For this purpose, a model was created to investigate performance of the new test rig Dolores. The results of the simulation model will be utilized in future research to discover and compare other alternatives for working hydraulics architectures.

Selective laser melting (SLM), is a type of additive manufacturing, which selectively melts a pre-spread layer of metal powders and produce a part by a layer-on-layer manner. SLM has demonstrated a great potential to reduce size and weight in hydraulic manifolds. However, a theoretical base is lacking since friction loss is unclear in a SLMed fluid passage. In this study, various fluid passages without supports, from diameters from 4 mm to 16 mm, were produced horizontally using SLM. The profile was measured using a 3D scanner and surface roughness was measured using a confocal laser scanning microscope. Friction factor was studied using simulation, experiments, and classical theory. The hydraulic diameter of the SLMed passages is smaller than the design diameter. Surface roughness is extremely high on the top part of the inner wall while the rest part is around 10 μm. Such trends are irrelevant of passage diameters. Friction factors in SLMed passage is much larger than those predicted using Moody theory, particularly in laminar flow. The transition from laminar flow to turbulent flow appears at a smaller Reynolds number with increased passage diameter. The influence of the profile overweighs that of the surface roughness on friction factor.