The implementation of an energy recovery system for retreiving otherways wasted energy is an effective method for reducing the overall energy consumption of a mobile machine. In a fork lift, there are two subsystems that can be effectively modified for recovering energy. These are the driveline and the lift/lower function of the mast. This study focuses on the latter by studying a recovery system whose main component is a hydraulic transformer consisting of a hydraulic motor, a variable displacement pump and an induction motor. Since the flow rate/pressure - ratio can be modified, the utilization of the hydraulic transformer enables downsizing of the accumulator volume. However, the decrease of the gas volume leads to an increase in the compression ratio of the accumulator, which in terms leads to higher gas temperatures after charging and consequently to higher thermal losses during holding phase. In order to reduce these losses, a thermally regenerative unit was implemented to the gas volume of an accumulator to reduce the temperature build up during charging. In this study, the effect of improving the thermal characteristics of the accumulator to the efficiency of the whole energy recovery system is investigated by means of measurements.

The focus of the present contribution is hydraulic energy recovery by means of hydropneumatic multi-chamber accumulators. A simulation study is presented comparing two different multi-chamber accumulator concepts for energy recovery in an exemplary load case involving a forklift mast. The first concept is based on the “Double Piston Accumulator” /1/. It is compared to the so-called “Digital Accumulator” /2/. Both similarities and differences of the two concepts are discussed in the presentation.

Komatsu Forest AB in Umeå saw an opportunity to increase performance during fast varying loads, e.g., when starting to feed after the felling cut, that proved more difficult to reach with their new line of stage V forest harvesters. It was believed that this issue was magnified as a result of new environmental regulations which limited their diesel engines' fuel injection quantity with low turbo boost pressure. It was in Komatsu Forest's interest to make comprehensive measurements of hydraulic and engine parameters in order to investigate what was limiting performance. This thesis includes a literature study into a number of viable options for storage types for a heavy hybrid vehicle with the purpose to recommend the best suited type for Komatsu's harvesters. It also includes extensive measurements made on a producing harvester where hydraulic and engine parameters as well as for example valve currents were logged and used as grounds in making the energy storage recommendation. With results from the measurements, the goal was to estimate how much energy is needed, how much energy can be stored and lastly to design an energy storage to supply additional power to increase performance. With successful measurements, it was possible to detect that approximately five kJ of energy with a maximum momentary power of 37 kW was sufficient to achieve a smoother first feeding. Furthermore, approximately 9-14 kJ of energy and between 0,3 and 0,5 l of hydraulic fluid was estimated as potential stored energy and volume from feeding stops of different sized trees plus an additional 3 kJ and 0,1 l of fluid from cutting stops. The best suited energy storage then proved to be an accumulator mounted on the P-line, which resulted in an appropriate accumulator volume of 4 l with an estimated pressure range of 250-280 bar.

The research looks at the advantages and disadvantages of a hydraulic auxiliary drive (HAD) system which is installed on a 25 meter long timber transport vehicle. The purpose is to investigate the performance with regard to energy, economy and environment of the system due to the added components, the hydraulic accumulators. The auxiliary system that is used on the vehicle is simply a hydrostatic transmission system. Ideally, the fuel consumption and cost can be reduced by using accumulators. To verify this hypothesis, model-based simulations were performed in a software environment and the result was analyzed for a linear and repeatedly accelerating and decelerating driving cycle. Additionally, comparisons were made between the HAD system with and without the assistance of accumulators. From the simulation results, the system assisted by accumulators consumes approximately 14% less fuel than the other. And it produces 15% more tractive effort when the vehicle is accelerating. The paper also includes the determination of the size of accumulators, both theoretically and with simulations. By comparison, there is a small difference between the results from the theoretical calculation and the simulations, which might be caused by a neglecting the volumetric losses in the simulation process. Ideally, an accumulator with a size of 57 L was found to be the most efficient size for the studied driving cycle. Beyond that speed, the efficiency will decrease to some extent. Physical tests are not presented in this paper, but they will be done in the future. / Den presenterade forskningen studerade fördelar och nackdelar med ett hydraulisk hjälpsystem för fordonsdrift (HAD) för en 25 meter lång timmerlastbil. Syftet var att undersöka hur drivlinans prestanda med avseende på energy, ekonomi och miljöpåverkan, påverkas av de adderade komponenterna, de hydrauliska ackumulatorerna. Hjälpsystemet är helt enkelt ett hydrostatiskt transmissionssystem. Idealt, kan bränsleförbrukning och kostnad reduceras genom att använda ackumulatorer i systemet. För att verifiera denna hypotes, har modell-baserade simuleringar utförts och resultaten har analyserats för konstantfartskörning och en körcykel med upprepade accelerationer och inbromsningar. Dessutom, har ett HAD-system med och utan ackumulator jämförts. Simuleringsresultaten visar att ett system med ackumulatorer förbrukar ca 14% mindre bränsle än ett system utan ackumulatorer. Ett ackumulatorstött system ger också 15% högre framdrivningseffekt vid accelereration. I avhandlingen dimensionera också storleken på ackumulatorerna, både teoretiskt och med simuleringar. Det finns en liten skillnad mellan resultaten från den teoretiska beräkningen och simuleringarna, som kan bero på att volymetriska förlusterna inte har tagits med i simuleringarna. En ackumulator med en storlek på 57 L visar sig ha den mest effektiva storleken för den studerade körcykeln. Vid högre körhastigheter, kommer verkningsgraden att minska till viss del. Inga fysiska tester har gjorts, men de kommer att utföras i framtiden.

Målet med detta arbete var att ta fram ett nytt trådmagasin till Sund Birstas α-kompaktor som är bättre ur ett säkerhets- samt ekonomiskt perspektiv. En kompaktor är en bindmaskin som komprimerar och binder samman valstrådrullar för att förhindra trassel samt underlätta förvararing och fraktning. Trådmagasinets huvudsakliga uppgift är att hålla kompaktorns bindtråd konstant sträckt för att förhindra att trassel uppstår bakom kompaktorn. Under arbetets konceptgenereringsfas togs delkoncept fram för ackumulering av tråd, lyftmekanismer samt förflyttningsmekanisker. Därefter togs 12 helhetskoncept fram som utvärderades först vid ett seminarium med Sund Birsta för att få värdefulla insikter kring koncepten. Därefter utvärderades koncepten med en Pughs-matris där koncepten jämfördes utifrån kriterier från Sund Birsta samt krav från kravspecifikationen. Det koncept som valdes ut från utvärderingen är en konstruktion som tillåter att användaren trär tråden igenom magasinet från golvnivå samt bidrar till en sänkning med 33% på kraften kompaktorns matarverk matar tråden med. En elmotor hjälper till att hålla tråden sträckt samt ladda magasinet genom att lyfta upp två rörliga brythjul. Det slutgiltiga konceptet utvecklades ytterligare för att kunna möjliggöra att allt arbete ska ske från golvnivå och därmed öka säkerheten. En CAD-modell togs slutligen fram för att illustrera konceptets utformning och funktion. / The goal of this project was to develop a new wire magazine for Sund Birsta´s α-compactor that is better from a safety and economical perspective. A coil compactor is a binding machine that compresses and binds together rod wire coils to prevent tangling and facilitate storage and transportation. The wire magazines main task is to keep the compactor’s binding wire constantly tense to prevent tangling from occuring behind the compactor. During the projects concept generation phase, subconcepts for lifting mechanisms, accumulation of wire and movement mechanisms was sketched. Thereafter 12 overall concepts was developed which was evaluated first at a seminar with Sund Birsta to gain valueble knowledge regarding the concepts. The concepts was thereafter evaluated with a Pughs-matrix where the concepts was compared with each other regarding to how well they met the demands set by Sund Birsta and from the requirements specification. The concept which was chosen from the evaluation is a construction which lets the user pull the wire through the magazine from ground level, and it lowers the force required for the compactor´s feeding unit with 33%. A electric motor helps keeping the wire tense and load the magazine by lifting up two movable wire wheels.

This thesis describes the results of two successive experiments. The first was focused on the influence of impurities in the active mass of negative electrode in PSoC (Partial State of Charge) mode, which simulates the conditions occurring in HEV (hybrid electric vehicle). In the second experiment, cells with the same additives were exposed to optimum downforce 4N/cm2, by which we wanted to prove the influence of pressure on life of VRLA (Valve Regulated Lead Acid) cells working in operating HEV conditions.

This thesis in its first part deals especially with characteristic of lithium ion accumulators in terms of their structure, electrochemical properties and also features of the most commonly used cathode materials. Especial attention is given to the high-voltage cathode material LiNi0,5Mn1,5O4 which cell voltage is close to 5V. The second practical part deals with the preparation of cathode materials based on LiNi0,5Mn1,5O4 with different temperatures in the second stage of annealing and analyzing them in terms of structure and electrochemical properties using appropriate measuring methods.

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The high price of batteries in working machines with electric drives offer a potential for investment in energy-saving hydraulic systems. The decentralized power network opens up new approaches for hydraulic- and hybrid circuits. In addition, the regeneration of energy can be used at any point of the machine. For the example of an excavator arm drive with a double cylinder two compact hydraulic circuits are presented, which relieve a central hydraulic system.

Vid strömavbrott på fartyg krävs enligt SOLAS regelverk att en nödkraftkälla startar automatiskt. Världshandelsflottan använder sig idag till största delen av generatorer drivna av en fossildriven förbränningsmotor för detta. Här undersöktes möjligheten att istället använda sig av en UPS. Studien har fokuserat på frågan om det är möjligt enligt gällande regelverk, om det finns produkter på marknaden som uppfyller regelkraven samt hur kostnaderna för de två alternativen skiljer sig vad gäller inköp och underhåll i 25 år. Resultatet för kostnaderna redovisades i en livscykelkostnadskalkyl. Sett till regelverk ifrån Transportstyrelsens författningssamling samt klassificeringssällskapet DNV-GL är det tillåtet att använda ackumulatorer eller generatorer.    För att ha möjlighet att undersöka frågeställningen genom kostnadsförslag, sammanställdes en teoretisk fartygsmodell med svensk flagg. De företag som kontaktades var svenska tillverkare. Resultatet av den LCC som gjordes visade att det idag är billigare att investera i en konventionell nödgenerator. / The SOLAS regulations for merchant vessels states that in the event of loss of power, a backup power supply will start automatically. This paper investigated the possibility to replace the widely-used generator driven by a fossil-fuel powered internal combustion engine, with a UPS. Focus of the investigation included regulations concerning the use of accumulators onboard, market product range fulfilling the legal requirements and price difference based on purchase price and maintenance costs for 25 years. The cost results where compared as a Life Cycle Cost calculation. Regulations by the Swedish transport agency and the Classification DNV-GL allow the use of emergency power from accumulators or generator.   For the possibility to investigate through cost estimations, a theoretical model of a merchant vessel with Swedish flag, was set up. All companies contacted were Swedish manufacturer. The results in the LCC show the situation of today and lets us know that the most cost efficient investment is the conventional emergency generator.