In this dissertation, energy efficient hydraulic systems are studied. The research focuses on solutions for linear actuators in mobile applications, with emphasis on construction machines. Alongside the aspect of energy efficiency, the thesis deals with competing aspects in hydraulic system design found in the development of construction machines. Simulation models and controls for different concepts are developed, taking the whole machine into account. In line with this work, several proof of concept demonstrators are developed. First, pump controlled systems are studied and a novel concept based on an open-circuit pump configuration is conceived. Special consideration is paid to multi-mode capabilities that allow for a broadened operating range and potential downsizing of components. Simulation models and controls are developed and the system is experimentally validated in a wheel loader application. Second, the possibility for energy recuperation in valve controlled systems is investigated. In such solutions, a hydraulic motor, added to the meter-out port, is used for energy recovery during load lowering and in multi-function operation. Recuperated energy is either be used momentarily or is stored in a hydraulic accumulator. The proposed solution means an incremental improvement to conventional systems, which is sometimes attractive to machine manufacturers due to fewer uncertainties in reliability, safety and development cost. The energy recovery system is studied on a conceptual level where several alternative systems are proposed and a concept based on a two-machine hydraulic pressure transformer is selected for a deeper control study followed by experimental validation. Third, so-called `common pressure rail' systems are suggested. This technique is well established for rotary drives, at least for the industrial sector. However, in applying this technique to mobile hydraulics, feasible solutions for linear actuators are needed. In this dissertation, two approaches to this problem are presented. The first one is the hydraulic pressure transformer, studied in simulation as the key-component of a `series hybrid' topology for wheel loaders. In the second approach variable displacement linear actuators (VDLA) based on a 4-chamber cylinder and multi-mode control is applied. In a theoretical study a model predictive control approach is suggested and new insights to the trade-off between controllability and energy efficiency of a multi-chamber cylinder are presented. Finally, a fullscale hydraulic hybrid system based on secondary controlled hydraulic motors and VDLAs is designed and experimentally validated on a large excavator.

No description available.

The pantograph-catenary system is used in railways to transfer electric power from infrastructure to trainset. As the pantograph slides against the catenary, the contact between the two surfaces is not stable due to stiffness variation, propagating wave and other environmental perturbation, especially at high speeds or in multi-pantograph operation. Heavy oscillation can result in poor power-transmission quality, electromagnetic interference, severe wear or even structural damage. So the pantograph-catenary dynamics has become one of the key issues which limits the operational speed and determines the maintenance cost. There are many types of catenary systems in Sweden, which are relatively soft and sensitive compared with the systems in other countries. They work well at low operational speed and have strict limitations to multi-pantograph operation. It is possible to achieve an operational speed of 350 km/h on newly-built high-speed lines, but there is still a large demand for higher operational speed and more capacity on the existing lines.     Many researchers and engineers have made progress to improve its dynamic performance. From the research aspect, many numerical models have been built up to demonstrate the dynamics of the pantograph-catenary system and to unveil the key influencing factors. There have been many applications developed in recent years. Regarding the catenary, high-tensile loads on the catenary and low-stiffness-variation designs are widely used to improve the dynamic performance. Regarding the pantograph, aerodynamic-friendly designs and active-control technique contribute to the development of high-speed pantograph. But all these methods need not only large investment but long out-of-service. Considering the large scale and heavy service duty of the existing lines, it becomes almost impossible to completely upgrade the existing pantograph-catenary systems. So it is necessary to find practical and efficient methods to exploit the potentials of the existing systems to enhance their dynamic performances.     This thesis investigates the dynamic behaviour of the Swedish pantograph-catenary systems and proposes methods for better usage. A numerical study on multi-pantograph operation is performed and the relationships between dynamic performance and some key parameters is established. By studying the multi-pantograph operation at short spacing distance, a method to use the leading pantograph as auxiliary pantograph is proposed to increase the operational speed on the soft catenary system. To ensure operational safety in abnormal conditions, numerical studies on pantograph raising/lowering processes and in catenary overlap sections are performed. By studying the influence of the lumped-mass on the dynamic performance, it shows that it is even possible to implement some artificial tuned-masses on the catenary for dynamic optimization. / <p>QC 20170915</p>

Studien fokuserar på tillverkningen av Volvo v90. Mer specifikt monteringen av en expander runt tanklocket. Monteringen sker på rear quarter panel stationen och det finns ett kvalitetsproblem där. Den manuella monteringen görs inte rätt varje gång och detta leder till problem framöver i produktionen. Studiens syfte är att ta fram fler förslag till motåtgärder och förbättringar. Med hjälp av ett uppbyggt teoretiskt ramverk i form av andra vetenskapliga artiklar har ett flertal förslag tagits fram. Tre nya tekniker, några ändringar med Lean som riktlinjer och ett förslag till designändring beskrivs vidare i texten. Vidare ges även förslag på hur Volvo Cars kan arbeta vidare med förbättringsförslagen i framtiden för att upprätthålla hög kvalité. De metoder som används för att ta fram förslagen till motåtgärder är DMAIC, intervju, observation och en litteraturstudie. En analys genomförs för att utvärdera huruvida förslagen är försvarbara eller inte. Inget om själva implementeringen i verkligheten kommer att finnas med i rapporten / The present study analyzes the quality issues occurring during the assembly of the expander around the fuel cap while manufacturing Volvo v90. The assembling process is done manually at the rear quarter panel station. The main objective of the current investigation was to analyze the problems that Volvo Cars AB is facing currently and suggest quality improvement tools and techniques.  To define, measure and analyze the above-mentioned problem, the DMAIC method has been used. Interviews, observations, and a thorough literature study has been conducted and potential improvement proposals are suggested.  As a result of the current study, three new techniques for detecting quality problems early in the production process, several improvement suggestions with Lean as guideline and a suggestion for design change is proposed. Furthermore, suggestions are also given on how Volvo Cars can continue to work with improvements in the future to maintain a high quality throughout.

No description available.

Centrifugal compressors are mechanical devices that move and compress gas and are used in a wide range of applications. To get as much efficiency out of the compressors as possible, high demandsare put on having good compressor models. One method of compressor modeling is the curve fitting method, where empirical and mathematical models are used to parameterize relationships between different compressor characteristics. The models come in a vast variety of formats, complexity and difficulty of applying them. With the variety of compressors and models to select from, it is important to select an appropriate model. A tool for automatic parameterization, evaluation and selection of compressor model would be very useful. A model library is proposed in the thesis that utilizes the Total Least Squares method for parameterizing and evaluating the models. By initializing the model library with measurement data, called a compressor map, the compressor is broken down into smaller components in a hierarchy, based on physical expressions and characteristics. The individual compressor models are defined and parameterized on top of the base model, overriding and replacing the base model feature. Total Least Squares offers a countermeasure to avoid large model prediction errors associated with the nonlinear behavior of the compressor. To utilize the model library further, a simulation interface is proposed, so the selected compressor model can easily be applied in an engine and vehicle simulation environment. The model library is evaluated using three different compressor maps and shows promising results, where the TLS method seem to better capture bad visual curve-fitted models, compared to other simpler methods. Parameterization of the models are done automatically without any manual user input needed. The simulation interface is tested by replacing the compressor block of an engine simulation model, where the results show that the model component hierarchy can be integrated in a simulation environment.

Today modern vehicles are expected to be safe, environmentally friendly, durable and economical. Monitoring the health of the vehicle is therefore more important than ever. As the complexity of vehicular systems increases the need for efficient monitoring methods has increased as well. Traditional methods of deriving models for the systems are today not as efficient as the complexity of the systems increases the time and skill needed to implement the models. An alternative is data driven methods where a collection of data associated with the behavior of the system is used to draw conclusions of the state of the system. Faults are however rare events and collecting sufficient data to cover all possible faults threatening a vehicle would be impossible. A method for drawing conclusions from limited historical data would therefore be desirable. In this thesis an algorithm using distiguishability as a method for fault classification and fault severity estimation is proposed. Historical data is interpolated over a fault severity vector using Gaussian process regression as a way to estimate fault modes for unknown fault sizes. The algorithm is then tested against validation data to evaluate the ability to detect and identify known fault classes and fault serveries, separate unknown fault classes from known fault classes, and estimate unknown fault sizes. The purpose of the study is to evaluate the possibility to use limited historical data to reduce the need for costly and time consuming data collection. The study shows promising results as fault class identification and fault size estimation using the proposed algorithm seem possible for fault sizes not included in the historical data.

In the early ship design process a quick overview of which shipdesign that could be the optimal choice for the intended usage needsto be investigated. Therefore the feasibility and accuracy ofinterpolating between measurement data from model resistance serieswhen estimating unknown hulls were conducted. A parametric study wasundertaken in order to investigate which parameters carry the mostimportance in regard to calm water resistance for semi-displacinghulls. In order to asses the whole estimation process one semidisplacing ship (FDS-5) and one bulk carrier with a bulbous bow (JBC)were estimated in regard to calm water resistance by using semiempirical methods and were later compared with CFD results. The CFDresults came from a in part parallel conducted work. The resultsshowed that it is possible to estimate the total resistance withsemi-empirical methods to an unknown hull by linear interpolationwith an accuracy of below 5% in the designed speed interval both forFDS-5 and JBC. The CFD simulations achieved a lower accuracy comparedto the semi-empirical approach, however by furhter calibrating themodels, the accuracy could potentially be improved. Linearinterpolation between two hulls in order to estimate an unknown hull,is only advised when the hulls are nearly identical. Meaning that thehulls must be of the same ship type and that only one parameter isallowed to differ compared to the unknown hull. The parametric studyresulted in parameter importance in falling order: Slenderness ratio,length-beam ratio, longitudinal prismatic coefficient, blockcoefficient and beam-draught ratio. Even though the CFD approach notyet is completely reliable, it could still be a useful complement tothe semi-empirical approach by calculating parameters such as adynamic wetted surface, resistance due to appendages or airresistance of the full-scale ship. Simply by incrementally increasingthe accuracy of individual resistance components an overallimprovement could potentially be achieved.

The periodic and determinist nature of wind turbine sound is believed to be a key factor for the high degreeof audibility. The present study investigated how alterations in fluctuating frequency affect the loudnessperception and detectability of wind turbine sound with and without background noise. The instantaneousloudness was judged for wind turbine sounds of different sonic character and altered fluctuating frequenciesusing the method of continuous judgment by category-ratio (CJCR) scaling. The obtained results showedlimited effects on the audibility despite altered fluctuating frequencies, rather it was found that the spectralcues dominate the loudness perception. These results was consistent for both measurements situation ofloudness and partial loudness.

Den här rapporten handlar om framtagningen av en bilstoldesign inom lättkonstruktioner. Stolen i fråga är anpassad efter ett steer-by-wire system, vilket innebär en datoriserad koppling mellan ratt, pedaler, motor och hjul. Rapporten behandlar vår arbetsgång med beräkningar, kravspecifikationer, labborationsresultat och materialforskning som ledde oss fram till vår slutliga produkt. Längst bak i rapporten finns alla bilagor. T.ex. den fullständiga kravspecifikationen, uppdraget som var givet från början samt beräkningar och koder. Stolen ska installeras i KTHs RCV och förhoppningen är att den även kommer användas i framtida koncept där hela störtbågen och chassit är anpassat utifrån viktoptimering.