Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

Investigation of Novel Displacement-Controlled Hydraulic Architectures for Railway Construction and Maintenance Machines

This dissertation aims at showing how to transform hydraulic systems of railway multi-actuator machinery characterized by inefficient state-of-the-art systems into the 21st Century. Designing machines that are highly efficient, productive, reliable, and cost affordable represents the target of this research. In this regard, migrating from valve-controlled architectures to displacement-controlled layouts is the proper answer. Displacement-controlled systems remove the losses generated by flow throttling typical of conventional circuits, allow an easy implementation of energy recovery (e.g. during regenerative braking), and create the possibility for the use of hybrid systems capable of maximizing the downsizing of the combustion engine. One portion of the dissertation focuses on efficient propulsion systems suitable for railway construction and maintenance machines. Two non-hybrid architectures are first proposed, i.e. a novel layout grounded on two independent hydrostatic transmissions (HSTs) and two secondary controlled hydraulic motors (SCHMs) connected in parallel. Three suitable control strategies are developed according to the specific requirements for railway machines and dedicated controllers are implemented. Detailed analyses are conducted via high-fidelity virtual simulations involving accurate modeling of the rail/wheel interface. The performance of the propulsion systems is proven by acceptable velocity tracking, accurate stopping position, achieving regenerative braking, and the expected behavior of the slip coefficients on both axles. Energy efficiency is the main emphasis during representative working cycles, which shows that the independent HSTs are more efficient. They consume 6.6% less energy than the SCHMs working with variable-pressure and 12.8% less energy than the SCHMs controlled with constant-pressure. Additionally, two alternative hybrid propulsion systems are proposed and investigated. These architectures enable a 35% reduction of the baseline machine’s rated engine power without modifying the working hydraulics. Concerning the working hydraulics, the focus is to extend displacement-controlled technology to specific functions on railway construction and maintenance machines. Two specific examples of complete hydraulic circuits for the next generation tamper-liners are proposed. In particular, an innovative approach used to drive displacement-controlled dual function squeeze actuators is presented, implemented, and experimentally validated. This approach combines two functions into a unique actuator, namely squeezing the ballast and vibrating the tamping tools of the work-heads. This results in many advantages, such as variable amplitude and variable frequency of the tamping tools’ vibration, improved reliability of the tamping process, and energy efficient actuation. A motion of the squeeze actuator characterized by a vibration up to 45 Hz, i.e. the frequency used in state-of-the-art systems, is experimentally confirmed. In conclusion, this dissertation demonstrates that displacement-controlled actuation represents the correct solution for next-generation railway construction and maintenance machines

The Fourteenth Scandinavian International Conference on Fluid Power, SICFP15: Abstracts

At this time the conference includes various themes like hybrids, drives, digital hydraulics and pneumatics. Special attention in the program is given for energy efficiency, renewable energy production and energy recovery. They are reflecting well the situation, where environmental issues and energy saving are increasingly important issues

Volume 3 – Conference: Thursday, March 10

10. Internationales Fluidtechnisches Kolloquiu

Volume 2 – Conference: Wednesday, March 9

10. Internationales Fluidtechnisches Kolloquium:Group 1 | 2: Novel System Structures Group 3 | 5: Pumps Group 4: Thermal Behaviour Group 6: Industrial Hydraulic

A review of electrohydraulic independent metering technology

The subject of this paper is the review of advanced technology used in hydraulic systems. The technology in question is termed Independent Metering (IM); this is used in hydraulically driven mobile machinery, such as agricultural, construction, municipal, and forestry vehicles. The idea behind the concept is to modify the connection between the actuator, which could be a cylinder or a motor, and a flow control valve. Traditionally, spool hydraulic valves were used to control the fluid flow into and out of hydraulic actuators. This keeps the meter-in and the meter-out of the actuator mechanically connected due to the construction of these valves. This connection makes the control system blind to pressure changes in one of the hydraulic chambers in the actuator. This, in turn, reduces the overall system controllability. It also increases energy losses, especially under an overrunning load. These two main weaknesses led researchers to break this mechanical connection and get into a new technology with different characteristics. The proposed technology was called Independent Metering. New and more complex control techniques can now be applied to the hydraulic systems using this technology that were not possible before or could be applied to more conventional servo design. This paper reviews Independent Metering (IM) and the technologies used or developed in this field to date. The paper reviews the state of art hydraulic technologies and indicates the links between them and IM. It also reviews the different types of hydraulic valves used when implementing IM. This review also discusses some control algorithms, IM layouts, IM challenges, and identifies where further improvements may be achieved

Towards Energy-Efficient Electrified Mobile Hydraulics : Considering Varying Application Conditions

In the face of global warming, companies in all kinds of industries need to take measures to reduce the use of fossil fuels, which is explicitly enforced by more and more upcoming emission legislation in many countries. In the case of heavy-duty mobile machines (HDMMs), a currently high-emitting sector, the most feasible method of reducing harmful emissions during operation is battery-based electrification. However, the relatively low capacities and high costs of available battery packs are restricting the operation times as well as upper power limits of battery-electric HD-MMs—at least under economically feasible conditions. In this scenario, the typically low energy-efficiencies of conventional hydraulic systems, which are essential for realizing linear actuation on HDMMs, are becoming more critical than ever before, and more efficient alternative concepts are required. As an answer to this demand, this thesis and the six publications on which it is based analyze how alternative hydraulic concepts for electrified HDMMs should look like, and two specific concepts are proposed as well as evaluated. In this scope, the focus is not only on improving the efficiency but also on other aspects that can prevent or accelerate the success of alternative hydraulic concepts on the market, such as costs and feasibility. Since those aspects cannot be analyzed in isolation from the application conditions, the essential characteristics of HDMMs and the differences of those characteristics between HDMM types are elaborated systematically. Furthermore, the implications of the transition from internal combustion engines (ICEs) to electric machines (EMs) as the prime movers for hydraulic pumps are identified by means of a literature review. Considering the insights from the analyses of those aspects, already existing hydraulic concepts—i.e., conventional as well as proposed alternatives for improved efficiency—are reevaluated, and beneficial elements of those concepts are filtered out for constructing two new concepts. Those two proposed concepts are characterized by a modular approach in which actuators can be valve-controlled, which might be less efficient but more cost-effective, or pump-controlled, as an alternative for more efficient yet costly actuation of selected functions on the HDMM. Simulation studies are used to demonstrate the efficiency of both concepts under varying configurations that are enabled through the modular nature of the concepts, and the differences in applying them on a telehandler, wheel loader, or excavator are analyzed. For the second concept, which is based on displacement-control and performed best in the simulations, a cost analysis is used to prove additionally that reasonably short payback times of the increased investment costs can be reached in different scenarios. Furthermore, the efficiency performance as well as feasibility—in terms of using commercially available components only and achieving good controllability—are experimentally validated on a telehandler

Control strategies for blended braking in road vehicles. A study of control strategies for blended friction and regenerative braking in road vehicles based on maximising energy recovery while always meeting the driver demand.

In HEV and EV, higher fuel economy is achieved by operating the ICE and electric motor in the most efficient region and by using regenerative braking. Such a braking system converts, transfers, stores and reuses kinetic energy which would otherwise be dissipated as heat through friction brakes to the environment. This research investigates the control of braking for a mixed-mode braking system in a these vehicles based on the proportion of braking energy that can be stored. Achieving mixed-mode braking requires the ‘blending’ of the two systems (regenerative and friction), and in brake blending, the electric motor/generator (M/G) and the hydraulic actuation pressure are controlled together to meet the driver’s braking demand. The research presented here has established a new robust dynamic modelling procedure for the design of combined regenerative and hydraulic braking systems. Direct torque control and pressure control were selected as the control criteria in both brakes. Two simulation models have been developed in Matlab/Simulink to generate analysis the performance of the control strategy in the blended braking system. Integration of the regenerative braking system with ABS has also been completed, based on two conditions, with and without the deactivation of the regenerative braking. Verification of the models is presented, based on experimental work on two EVs manufactured by TATA Motors; the ACE light commercial vehicle and the VISTA small passenger car. It is concluded that braking demand and vehicle speed determine the operating point of the motor/generator and hence the regenerative braking ratio

Realization of a dual clutch transmission hydraulic and thermal model for HIL applications

Depleting oil resources and global warming has led to a continual search in the automotive field to find a cost-effective solution to develop more and more fuel efficient vehicles. In the last years the number of electric and hybrid vehicles have rapidly increase thanks to pollution standards and their high efficiency. It is possible to define three main categories, based mainly on the power of the electric motor and the capacity of the batteries. In "mild" hybrids, a small unit takes the place of the alternator and starter motor, and is connected to the main engine with a belt. When it slows down, it recharges a battery, while the energy flow is reversed, and the current motor "helps" the thermal one. The "full" hybrids have instead more powerful electric motors that are integrated with the rest of the vehicles : they are often part of the transmission. The "plug-ins" are "full" equipped with much larger batteries, which allow a range of tens of kilometers without using fuel; to be able to charge them to the maximum, however, it is necessary to connect them to the electric network through a cable. Otherwise, these cars behave like "full" hybrids: the accumulators are filled by the inertia of the vehicle when it slows down. As a result of this, new concepts called hybrid dual clutch transmission (HDCT) have been developed. These new type of transmission are suitable for multiple hybridisation topologies, as the e-machine can be connected to the transmission by different methods in order to obtain a more efficient interaction of the internal combustion engine and the e-machine. Compared to an automatic transmission based on planetary gearsets or to continuous variable transmissions (CVT), further optimisation potentials can be achieved thanks to the flexible hybridisation concept. This thesis aims to realize a model to calculate the heat generated by an hybrid dual clutch transmission in real-time without a great amount of computing power

Novel System Architectures by Individual Drives

Measures of individualization and integration offer a great potential for further development and optimization in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. These potentials motivate current research activities for displacement controlled systems and for valve controlled structures. For the latter, the focus lies on strategies of independent metering. Furthermore, expected challenges for the future are discussed