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

Mod-2 wind turbine system concept and preliminary design report. Volume 1: Executive summary

The configuration development of the MOD-2 wind turbine system is presented. The MOD-2 is design optimized for commercial production rates which, in multi-unit installations, will be integrated into a utility power grid and achieve a cost of electricity at less than 4 cents per kilowatt hour

A Review of Developments in Electrical Battery, Fuel Cell and Energy Recovery Systems for Railway Applications: a Report for the Scottish Association for Public Transport

This report outlines the current status of batteries, hydrogen fuel cells and short-term energy storage systems for railway and tramway applications. The report includes discussion of issues associated with regenerative braking and the recovery of energy that would otherwise be dissipated as heat during braking. As well as feeding energy back to the supply grid, as in the case of conventional electrified rail systems, energy recovery may also be achieved using batteries, supercapacitors, flywheels or hydraulic devices and developments in each of these areas are reviewed. The advantages of hybrid systems that involve combinations of different power sources and energy storage methods are emphasised and some associated design optimisation issues are discussed. For each of the developments mentioned, there is a brief account given of some transport applications in the United Kingdom and elsewhere. This is a rapidly developing field and operating experience with vehicles currently entering service in various countries will provide important additional insight within the next two or three years

Reducing energy consumption of hammering with electric excavators

Abstract. The aim of this master’s thesis is to research methods to reduce the energy consumption of hammering with electric excavators. To understand the energy consumption of hammering, the structure and energy consumption of a conventional excavator is explained thoroughly. The knowledge of a conventional excavator also lays foundation for studying the electric excavator. An electric excavator is not yet a widely used machine so different operating principles and models are presented in the work. Different technologies are described for utilizing electricity in hammering. Energy consumption of hammering is researched by measurements of the current situation. Measuring the power losses in hammering brings forward the challenges in the conventional hydraulic system and the excavator use in hammering. In addition to the measurements, hammer concepts are designed utilizing the technology researched. Quantitative and qualitative properties of the concepts are reviewed. The size of the power losses of hammering can be seen in the results of the measurements. The magnitude of the losses depend on what type of hammering work is done. The different hammering concepts bring large potential in reducing the energy consumption. The concepts also have new features, which can affect the productivity. The technology used in the different concepts still needs to be researched more and desired features deter- mined. The measurements show the magnitude of power losses in this excavator, but a working cycle should be determined to measure the energy consumption.Iskuvasaroinnin energiankulutuksen pienentäminen sähköisellä kaivinkoneella. Tiivistelmä. Tämän työn tavoitteena on tutkia tapoja, jolla iskuvasaroinnin energiankulutusta pystytään pienentämään sähköisellä kaivinkoneella. Iskuvasaroinnin energiankulutuksen ymmärtämiseksi työssä perehdytään perinteisen kaivinkoneen rakenteeseen ja energiankulutukseen. Perinteiseen kaivinkoneeseen perehtyminen luo myös pohjaa sähköisen kaivinkoneen toiminnan ymmärtämiseen. Sähköinen kaivinkone ei ole vielä yleisesti käytetty laite, joten sen eri toimintaperiaatteita käsitellään tässä työssä. Erilaisia teknologioita esitetään siihen, kuinka sähköä voidaan hyödyntää iskuvasaroinnissa. Iskuvasaroinnin energiankulutusta tutkitaan myös kokeellisesti. Tehohäviömittaukset iskuvasaroinnissa tuovat esiin tämän hetken ongelman kaivinkoneen hydrauliikkajärjestelmässä ja kaivinkoneen käytöstä iskuvasaroinnissa. Mittausten lisäksi työssä suunnitellaan sähköenergiaa hyödyntäviä iskuvasarakonsepteja. Konsepteja arvioidaan sekä energiatehokkuden kannalta että laadullisesti. Mittaustulokset tuovat esiin hydraulisten häviöiden suuruuden. Eri tyyppisissä iskuvasaroinnissa tehohäviöt ovat eri suuruisia johtuen kaivinkoneen hydrauliikasta. Eri konseptit tuovat suurta potentiaalia energiankulutuksen pienentämiseen sähköä hyödyntäen. Konseptit tarjoavat myös uusia ominaisuuksia rikotukseen. Konsepteissa käytettäviin teknologioihin pitää syventyä jatkossa vielä tarkemmin ja halutut laadulliset ominaisuudet tulee määrittää. Mittaustulokset osoittavat häviöiden suuruuden, mutta energiankulutuksen mittaamiseksi tulisi määrittää työsykli iskuvasaroinnille

The Working Hydraulics of Valve-Controlled Mobile Machines: Classification and Review

Productivity, reliability, controllability, flexibility and affordable costs represent key aspects in mobile machines. Additionally, due to the high fuel price and to the introduction of stringent emission regulations for diesel engines, the reduction of fuel consumption while persevering the existing performance is the current demand. In order to satisfy and maximize the above requirements, different hydraulic system architectures have been developed during the last decades. Both academia and industry have been investing considerable resources delivering numerous outcomes that require a classification. This review paper closes this gap by analyzing and classifying the working hydraulics of non-hybrid, valve-controlled mobile machines starting from the 1980s to the state-of-the-art. Hydraulic layouts are addressed and categorized by both discussing their fundamentals and evolutions, and by pointing out their pros and cons in a way to provide the readers with a comprehensive overview of the systems currently available on the market and at the research stage

An analysis of kinetic energy recovery systems and their potential for contemporary internal combustion engine powered vehicles

The Internal Combustion Engine has played an incomprehensible role in contemporary society ever since its invention. Oil shortages will almost certainly eventually lead towards a search for propulsion from renewable sources, but for the time being there is no sign of any significant alternative for everyday transport. Any product that offers a fuel economy improvement is of benefit to both the individual and the environment. As vehicles speed up, they convert stored energy into kinetic energy. As the mass or velocity increases, the kinetic energy will also increase. It is for this reason that light commercial vehicles on our roads have so much kinetic energy when travelling at speed. The concept of being able to recover this energy when braking is the foundation for regenerative braking or Kinetic Energy Recovery. The energy captured is then stored to be used in the future: in most cases it is converted back into kinetic energy to bring the vehicle back to speed. The technology is particularly effective in drive cycles consisting of frequent stop-start driving. This project seeks to investigate the feasibility of a mechanical Kinetic Energy Recovery System for implementation via a retrofit on existing light commercial vehicles. In order to be effective, the system must be cost effective and easy to implement. The objective was to design a system able to be fitted to a large number of vehicle platforms and with a reasonable payback period. A literature review was carried out to discern the most appropriate system for light commercial vehicles. Existing systems were analysed and their benefit was appraised from a retrofit stance. A flywheel system was chosen due to its recent success in F1 and its very high energy density amongst other factors. A system was designed to be fitted to a representative vehicle, with potential to be fitted to other platforms. The theory of operation, driveline configuration and attachment options were developed. The system was modelled in Creo and a Matlab code was developed to calculate the potential fuel savings under different circumstances using drive cycles. The dissertation found that the technology was conceptually viable. A vehicle of mass 2680kg with load would save $0.91 per 100km (6.9$1.64 per 100km (7.6% saving). The total cost of the system was found to be $2680. The repayment period ranged from 5-8years to a best case scenario of 3-4 years

Climate change and transport infrastructures: State of the art

Transport infrastructures are lifelines: They provide transportation of people and goods, in ordinary and emergency conditions, thus they should be resilient to increasing natural disasters and hazards. This work presents several technologies adopted around the world to adapt and defend transport infrastructures against effects of climate change. Three main climate change challenges have been examined: Air temperatures variability and extremization, water bombs, and sea level rise. For each type of the examined phenomena the paper presents engineered, and architectural solutions adopted to prevent disasters and protect citizens. In all cases, the countermeasures require deeper prediction of weather and climate conditions during the service life of the infrastructure. The experience gained supports the fact that strategies adopted or designed to contrast the effects of climate change on transport infrastructures pursue three main goals: To prevent the damages, protect the structures, and monitor and communicate to users the current conditions. Indeed, the analyses show that the ongoing climate change will increase its impact on transport infrastructures, exposing people to unacceptable risks. Therefore, prevention and protection measures shall be adopted more frequently in the interest of collective safety

Constructional Characteristics of the Agricultural Tractors at the Beginning of the 21st Century

Through implementation of new technological innovations from the area of the motor vehicles, the agriculture tractor became highly sophisticated vehicle-machine. Tractor engines are equipped with the common-rail fuel injection system, four valves per cylinder and variable geometry turbocharger, and fulfil rigorous ecological standards regarding the air pollution. Continuously variable transmission enables selection of the optimal transmission speed according to working conditions. Besides very accurate adjustment of three point-hitch drawbar, electro-hydraulic control system enables more additional functions. Significant improvement was obtained at ergonomics of operator’s working place conditions. Computer control systems are going to take over more and more functions, not only in operating, but also in tractor diagnostics. The utilization of recycling materials, bio-fuel and biodegradable lubricants represent high level of ecological manufacturing as well as tractor operating level. High level of tractor sophistication due to built in computers and electronics requires adequately educated operator

Constructional Characteristics of the Agricultural Tractors at the Beginning of the 21st Century

Through implementation of new technological innovations from the area of the motor vehicles, the agriculture tractor became highly sophisticated vehicle-machine. Tractor engines are equipped with the common-rail fuel injection system, four valves per cylinder and variable geometry turbocharger, and fulfil rigorous ecological standards regarding the air pollution. Continuously variable transmission enables selection of the optimal transmission speed according to working conditions. Besides very accurate adjustment of three point-hitch drawbar, electro-hydraulic control system enables more additional functions. Significant improvement was obtained at ergonomics of operator’s working place conditions. Computer control systems are going to take over more and more functions, not only in operating, but also in tractor diagnostics. The utilization of recycling materials, bio-fuel and biodegradable lubricants represent high level of ecological manufacturing as well as tractor operating level. High level of tractor sophistication due to built in computers and electronics requires adequately educated operator

Design of a hydraulic servo-actuation fed by a regenerative braking system

Many conventional truck and working machines are equipped with additional hydraulic tooling or manipulation systems which are usually fed through a mechanical connection with the internal combustion engine, involving a poor efficiency. In particular, this is a common situation for industrial vehicles whose mission profiles involves a relevant consumption of energy by the on board hydraulic systems, respect to the one really needed for only traction purpose. In this work it is proposed an innovative solution based on the adoption of a system aimed to recover braking energy in order to feed an efficient on board hydraulic actuation system. The proposed system is then adopted to a real application, an Isuzu truck equipped with a hydraulic tooling for garbage collection. A prototype of the system has been designed, assembled and tested showing a relevant improvement of system efficiency and the feasibility of the proposed approach. In the paper the proposed solution is presented, showing the simulation models and preliminary validation results including experimental devices assembled to perform the tests