Slip controller design and implementation in a Continuously Variable Transmission

Continuously Variable Transmissions (CVT) can be used to operate a combustion engine in a more optimal working point. Unfortunately, due to the relatively low efficiency of modern production CVT’s the total efficiency of the driveline is not increased significantly. This low efficiency is mainly caused by losses in the hydraulic actuation system and the variator. Decreasing the clamping forces in the variator greatly improves the efficiency of the CVT. However, lower clamping forces increase the risk of excessive belt slip, which can damage the system. In this paper a method is presented to measure and control slip in a CVT in order to minimize the clamping forces while preventing destructive belt slip. To ensure robustness of the system against torque peaks, a controller is designed with optimal load disturbance response. A synthesis method for robust PI(D)-controller design is used to maximize the integral gain while making sure that the closed loop system remains stable. Experimental results prove the validity of the approach

The Empact CVT: modeling, simulation and experiments

This paper shows the implementation of a simulation model for newelectromechanically actuated metal V-belt type continuously variabletransmission (CVT), referred to as the Empact CVT. An analysis ofthe dynamics of the actuation system and of the driveline shows thatthe eigenfrequencies of the system depend on both the CVT ratio andthe slip in the variator. An accurate variator model is required to incorporateall characteristic dynamics. The implemented variator modelis an explicit formulation of a model which gives an estimation of thetension forces and compression forces in the pushbelt. The simulationmodel also includes slip, shifting losses based on transient variator modelsand friction. Simulations are compared to measurements, showinggood results

The use of carbon and gold electrodes in anodic stripping voltammetric heavy metal sensors.

The use of anodic stripping voltammetry (ASV)has been proven in the past to be a precise and sensitive analytical method with an excellent limit of detection. Electrochemical sensors could help to avoid expensive and time consuming procedures as sample taking and storage and provide a both sensitive and reliable method for the direct monitoring of heavy metals in the aquatic environment. Solid electrodes which have been used in this work, were produced using previously developed methods. Commercially available and newly designed, screen printed carbon and gold plated working electrodes (WE) were compared. Good results were achieved with the screen printed and plated electrodes under conditions optimized for each electrode material. The electrode stability, reproducibility of single measurements and the limit of detection obtained for Pb were satisfactory (3*10-6mol/l on screen printed carbon WEs after 60 s of deposition and 6*10-6 mol/l on gold plated WEs after 5 min of deposition). Complete 3-electrode-sets (counter, reference and working electrode) were screen printed on different substrates (glass, polycarbonate and alumina). Also here, both carbon and gold were used as WE. Using 3-electrode-sets with a gold plated WE on glass was a limit of detection of 7*10-7 mol/l was achieved after only 60 s of deposition

CVT ratio control strategy optimization

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Forschendes Lernen

Klewin G, Hinzke J-H, Bonsen M, eds. Forschendes Lernen. Lernende Schule. 2021;95.Forschendes Lernen begegnet Schulen in vielfältiger Form, aktuell vermutlich am häufigsten durch Forschungsprojekte von Studierenden. Forschendes Lernen beschränkt sich aber nicht auf Studierende, auch für Schülerinnen und Schüler kann es ein gewinnbringendes Konzept sein. Lehrpersonen können ebenfalls forschend tätig werden und damit zu Unterrichts- und Schulentwicklung beitragen. Die Vielfältigkeit der Akteurinnen und Akteure korrespondiert mit einer Vielfältigkeit der Konzepte und Verständnisse forschenden Lernens. Das Heft gibt deshalb einen Überblick über forschendes Lernen für Studierende, Schülerinnen und Schüler sowie Lehrpersonen, zeigt aber auch, wie forschendes Lernen in der Schule umgesetzt werden kann und wie alle Beteiligte daraus einen Nutzen ziehen können. Die Vielfalt Beiträge bietet einen guten Einblick in die Thematik und Anregungen für die Praxis

Editorial zum Heft „Forschendes Lernen“

Klewin G, Hinzke J-H, Bonsen M. Editorial zum Heft „Forschendes Lernen“. Lernende Schule. 2021;95:1

Erarbeitung der Grundlagen fuer die europaeische Normung von Brennstoffzellen-Heizanlagen fuer die haeusliche Energieversorgung (ENBA). Teilprojekt: Strom- und Waermelastgaenge in Einfamilienhaeusern und Installation von Brennstoffzellenheizungen durch das Handwerk Abschlussbericht TAA-Projekt 5048

As part of a joint ZIP project entitled 'Erarbeitung der Grundlagen fuer die europaeische Normung von Brennstoffzellen-Heizanlagen fuer die haeusliche Energieversorgung (ENBA)' ('Development of the Fundamentals for European Standardisation of Fuel Cell Heating Systems for Residential Energy Supply'), Ruhrgas conducted high-resolution measurements of electricity and heat load profiles in 5 single-family homes during the period from May 2002 to July 2003. In addition, a simulation program for electricity and heat supply to buildings with small CHP systems was prepared and the level of qualifications of craft enterprises required for installing fuel cell heating systems was determined. The buildings selected for the project were three single-family homes and one two-family home (with separate meters), all of which are located in the Ruhr area. These buildings were fitted with the necessary measurement and data transmission equipment. The houses selected were of different construction types to make the data for the 'single-family home' category as representative as possible, despite the low number of measuring points. All data recorded during the above period have been stored in an Access database (approx. 130 MB) and may be retrieved for different purposes. In order to assess the fuel cell system's operating behaviour, a simulation program was developed which determines the load status of the fuel cell system on the basis of measured values for heat and hot water demand and uses this load status to calculate power generation by the fuel cell for comparison with the home's power demand. This makes it possible to determine how much of the power generated by the fuel cell is available for consumption in the house and how much is fed into the grid. The calculations show that the average determined at 15-minute intervals (which is sufficient for the power grid) is far too inaccurate for CHP evaluation purposes. At these intervals the power demand peaks are not properly recorded and simulation results in a deviation up to 10% of the power fed into the grid compared with the 1-minute resolution. The project also confirmed the need for high-resolution load profiles for the purpose of accurately determining fuel cell system economics. An investigation into the qualification of craft enterprises showed that some 2,400 enterprises are qualified to sell and install fuel cell heating systems. All that is still required is product-specific training. (orig.)SIGLEAvailable from TIB Hannover: F04B883 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Wirtschaft und Arbeit, Bonn (Germany)DEGerman