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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Study on a high precision drilling tool with focus on power source and driveline / Studie av en högprecisionsborrmaskin med fokus på kraftkälla och drivlina

Hallberg, Daniel, Ringdahl, Patrik January 2017 (has links)
This thesis was carried out at Atlas Copco Industrial Technique in Nacka, Sweden. Atlas Copco is a world leading manufacturer of industrial tools for a wide range of industries. One application is semi-automatic drilling machines for the aerospace industry. The latest trend for such tools is moving in a direction of increased control and traceability. The purpose of this thesis was to investigate the possibility of replacing the pneumatic motor in an industrial semi-automatic drilling machine, PFD1100, with an electric motor and explore the possibilities such design would enable. The two main priorities for the thesis have been:  Investigate the capacity of an electric motor developed by Atlas Copco and find out if it’s suitable for use in drilling applications.  Develop concepts for a new driveline, solving the two core functions of the drill - spindle rotation and spindle feed. The thesis has been limited to use the electric motor from an existing nutrunner and carry over the design for the spindle mechanism from the PFD1100 drilling machine. A background study was conducted of the aerospace industry in general and drilling applications in particular. The authors made a study visit to Airbus production facilities in Hamburg to get a better insight of where and how the tools are used. The background study supported the need for an electric drilling machine, targeted at smaller hole sizes and stack drilling applications. A hybrid prototype machine was designed and manufactured consisting of the driveline from the PFD1100 drilling machine and the motor and electrics from an electric nutrunner. The purpose of the prototype was to verify analytical calculations of the mechanical drilling power through physical testing, and investigate how the machines would behave with an electric motor. The prototype showed promising results with respect to drilling performance and basic adaptive drilling. The electric motor from the nutrunner was tested in a power test rig and the results were used to adapt an existing MATLAB script for estimating motor and inverter losses. With the adapted script provided by Atlas Copco, the gear ratio for the drilling machine could be optimized to minimize losses in the motor and electrical systems. Finally, concepts for a transmission between the electric motor and the spindle mechanism was generated and evaluated with a weighted Pugh’s evaluation matrix. Concepts focused on achieving a tool with minimum size and weight as well as expanding the tool functionality. The most promising concepts according to the evaluation were those that offered a compact and robust solution. To minimize resources and time to market, these concepts could offer a good starting point for continued develpoment. / Detta examensarbete utfördes vid Atlas Copco Industrial Technique i Nacka, Sverige. Atlas Copco är världsledande leverantör av industriella verktyg till olika typer av industrier, bland annat flygindustrin. Semi-automatiska borrmaskiner har använts inom flygindustrin i flera år och trenden för sådana verktyg rör sig i riktning mot ökad kontroll och spårbarhet. Syftet med arbetet var att undersöka möjligheten att ersätta den pneumatiska motorn i en industriell semi-automatisk borrmaskin, PFD1100, med en elektrisk motor samt utforska de fördelar som en sådan konstruktion kan medföra. De två huvudprioriteringarna var följande:  Undersöka kapaciteten hos en elmotor utvecklad av Atlas Copco och hur den lämpar sig för en borrmaskin.  Utveckla koncept för en ny drivlina som löser de två huvudfunktionerna rotation och matning av borrspindeln. Examensarbetet avgränsades till att använda motorn från en befintlig mutterdragare och grundprincipen från PFD1100 borrmaskinens mekanism för spindeldrivning. I en bakgrundsstudie undersöktes flygindustrin i allmänhet och borrningsapplikationer i synnerhet. Författarna gjorde ett studiebesök hos Airbus produktionsanläggning i Hamburg för att se hur verktygen används och vilka behov som finns. Från bakgrundsstudien drogs slutsatsen att en elektrisk maskin bör rikta in sig mot mindre hålstorlekar och tillämpningar av stackborrning. En prototyp konstruerades bestående av drivlina och spindeldrivning från PFD1100 och motorpaket och styrning från en elektrisk mutterdragare. Syftet med prototypen var att verifiera teoretiska beräkningar av den mekaniska borreffekten och få en ökad förståelse för maskinens beteende med en elmotor. Prototypen visade lovande resultat med avseende på borrning och kunde även utföra adaptiv borrning i viss utsträckning. Den elektriska motorn testades i en effektprovrigg och resultatet användes för att anpassa ett befintligt MATLAB-skript för beräkning av motorförluster. Skriptet, som tillhandahölls av Atlas Copco, användes för att optimera utväxlingen för verktyget i syfte att minimera effektförluster i motor och elektronik. Flertalet koncept genererades för rotation och matning där några av koncepten skulle ge ett så kompakt verktyg som möjligt med låg komplexitet, medan andra koncept fokuserade på utökad funktionalitet. Koncepten utvärderades med en viktad Pughs utvärderingsmatris. De mest lovande koncepten enligt konceptutvärderingen var de som erbjöd en kompakt och robust lösning som tillämpar kända tekniska principer. Om resurskrav och tid till marknad ska minimeras så kan dessa koncept utgöra en bas för fortsatt utveckling.
22

Automation and synchronizationof traction assistance devices toimprove traction and steerability ofa construction truck

Dabhi, Meet, Vaidyanathan, Karthik Ramanan January 2017 (has links)
Automotive development has always been need-based and the product of today is an evolutionover several decades and a diversied technology application to deliver better products to theend users. Steady increase in the deployment of on-board electronics and software is characterizedby the demand and stringent regulations. Today, almost every function on-board a modernvehicle is either monitored or controlled electronically.One such specic demand for AB Volvo arose out of construction trucks in the US market. Usersseldom have/had a view of the operational boundaries of the drivetrain components, resultingin inappropriate use causing damage, poor traction and steering performance. Also, AB Volvo'sstand-alone traction assistance functions were not suciently capable to handle the vehicle useconditions. Hence, the goal was set to automate and synchronize the traction assistance devicesand software functions to improve the traction and steerability under a variety of road conditions.The rst steps in this thesis involved understanding the drivetrain components from design andoperational boundary perspective. The function descriptions of the various traction softwarefunctions were reviewed and a development/integration plan drafted. A literature survey wascarried out seeking potential improvement in traction from dierential locking and also its eectson steerability. A benchmarking exercise was carried out to identify competitor and suppliertechnologies available for the traction device automation task.The focus was then shifted to developing and validating the traction controller in a simulationenvironment. Importance was given to modeling of drivetrain components and renement ofvehicle behavior to study and understand the eects of dierential locking and develop a differentiallock control strategy. The modeling also included creating dierent road segments toreplicate use environment and simulating vehicle performance in the same, to reduce test timeand costs. With well-correlated vehicle performance results, a dierential lock control strategywas developed and simulated to observe traction improvement. It was then implemented onan all-wheel drive construction truck using dSPACE Autobox to test, validate and rene thecontroller.Periodic test sessions carried out at Hallered proving ground, Sweden were important to re-ne the control strategy. Feedback from test drivers and inputs from cross-functional teamswere essential to develop a robust controller and the same was tested for vehicle suitability andrepeatability of results. When comparing with the existing traction software functions, the integrateddierential lock and transfer case lock controller showed signicantly better performanceunder most test conditions. Repeatable results proved the reliability of developed controller.The correlation between vehicle test scenarios and simulation environment results indicated theaccuracy of software models and control strategy, bi-directionally.Finally, the new traction assistance device controller function was demonstrated within ABVolvo to showcase the traction improvement and uncompromising steerability.
23

Multi-body dynamics analysis and experimental investigations for the determination of the physics of drive train vibro-impact induced elasto-acoustic coupling

Menday, M. T. January 2003 (has links)
A very short and disagreeable audible and tactile response from a vehicle driveline may be excited when the throttle is abruptly applied or released, or when the clutch is rapidly engaged. The condition is most noticeable in low gear and in slow moving traffic, when other background engine and road noise levels are low. This phenomenon is known as clonk and is often associated with the first cycle of shuffle response, which is a low frequency longitudinal vehicle movement excited by throttle demand. It is often reported that clonk may coincide with each cycle of the shuffle response, and multiple clonks may then occur. The problem is aggravated by backlash and wear in the drivetrain, and it conveys a perception of low quality to the customer. Hitherto, reported investigations do not reveal or discuss the mechanism and causal factors of clonk in a quantitative manner, which would relate the engine impulsive torque to the elastic response of the driveline components, and in particular to the noise radiating surfaces. Crucially, neither have the issues of sensitivity, variability and non-linearity been addressed and published. It is also of fundamental importance that clonk is seen as a total system response to impulsive torque, in the presence of distributed lash at the vibro-elastic impact sites. In this thesis, the drivetrain is defined as the torque path from the engine flywheel to the road wheels. The drivetrain is a lightly damped and highly non-linear dynamic system. There are many impact and noise emitting locations in the driveline that contribute to clonk, when the system is subjected to shock torque loading. This thesis examines the clonk energy paths, from the initial impact to many driveline lash locations, and to the various noise radiating surfaces. Both experimental and theoretical methods are applied to this complex system. Structural and acoustic dynamics are considered, as well as the very important frequency couplings between elastic structures and acoustic volumes. Preliminary road tests had indicated that the clonk phenomenon was a, very short transient impact event between lubricated contacts and having a high frequency characteristic. This indicated that a multi-body dynamics simulation of the driveline, in conjunction with a high frequency elasto-acoustic coupling analysis, would be required. In addition, advanced methods of signal analysis would be required to handle the frequency content of the very short clonk time histories. These are the main novelties of this thesis. There were many successful outcomes from the investigation, including quantitative agreement between the numerical and experimental investigations. From the experimental work, it was established that vehicle clonk could be accurately reproduced on a driveline rig and also on a vehicle chassis dynamometer, under controlled test conditions. It then enabled Design of Experiments to be conducted and the principal causal factors to be identified. The experimental input and output data was also used to verify the mathematical simulation. The high frequency FE analysis of the structures and acoustic cavities were used to predict the dynamic modal response to a shock input. The excellent correlation between model and empirical data that was achieved, clearly established the clonk mechanism in mathematical physics terms. Localised impact of meshing gears under impulsive loads were found to be responsible for high frequency structural wave propagation, some of which coupled with the acoustics modes of cavities, when the speed of wave propagation reached supersonic levels. This finding, although previously surmised, has been shown in the thesis and constitutes a major contribution to knowledge.
24

The influence of transient thermo-elastohydrodynamic conjunctions on automotive transmission rattle

De la Cruz, Miguel January 2011 (has links)
Automotive transmission rattle is the noise generated due to impacts between manual transmissions meshing gear teeth in the presence of backlash. It is considered to be a Noise, Vibration and Harshness (NVH) phenomenon and is originated due to combustion irregularities (engine order vibrations), especially in diesel vehicles. This thesis focuses in the case of creep rattle for the MMT6 Ford Getrag transmission (six speeds plus reverse) with a DW10b, 4-cylinder, 4-stroke, 2.0 litres diesel engine. This particular rattle condition is fundamentally similar to any other where an engaged gear is pertained (drive, over-run or float), with the 1st or 2nd gear engaged at a very low engine speed. The numerical models include an initial single degree of freedom (DoF) simulation. It comprises either of the engaged gear pair under Hertzian contact conditions or of a loose gear pair under hydrodynamic regime of lubrication. Once the validity of this model is established and correlated with the results obtained from a single gear pair test rig, simulations of increasing complexity can be envisaged. A 7 DoF numerical model is, therefore, developed. The Hertzian contact model still prevails for the engaged gear pair, whereas an analytical hydrodynamic solution is implemented for the remaining 6 loose gear wheels and Petrov s law is applied to the needle bearings retaining the gear wheels. With the aim of accommodating a fully lubricated model of all the tribological conjunctions, an analytical elastohydrodynamic (EHL) Grubin type algorithm is employed. Also, the energy equation is analytically solved for hydrodynamic and elastohydrodynamic conjunctions, based on the assumptions dictated by the Peclet number. Therefore, under hydrodynamic conditions, the energy equation is governed by viscous heating and convective cooling, whereas in the EHL conjunctions the governing terms are viscous and compressive heating, together with conductive cooling. The retaining needle bearings follow the same heat generation mechanism as journal bearings. The effective viscosity, as obtained from the Houpert s equation accounting for pressure and thermal effects, is fundamental for the study of the friction in the contact. The hydrodynamic contacts are only governed by viscous friction, whereas EHL conjunctions exhibit asperity iv interactions as well as viscous effects. The results obtained from this new 7 DoF model are then compared to the experimental measurements taken from the vehicle tests and various purpose-built drivetrain rigs. A metric named Impulsion Ratio is hereby introduced, aiming to shed some light into the predictions obtained by the various models presented. This metric is the ratio of driving over resistive forces acting on each individual gear wheel. Its use is tested to predict single or double-sided rattle scenarios and, therefore, ascertaining higher and lower rattle levels. The 13 DoF model from which these conclusions were obtained includes shafts planar translation and rocking moments. The rolling element bearings supporting the shafts are, therefore, modelled to capture the inherent frequencies arising from their motion. The final model introduces the effects of transient thermo-elastohydrodynamics. This 7 DoF dynamic model accounts for a numerical solution of Reynolds equation with Elrod s cavitation algorithm for simultaneous teeth in mesh. The results obtained validate the previously used Grubin assumption by comparing the predicted central film thickness along the full mesh of one tooth. Also, the effect of starved input conditions and thermal and isothermal solutions are studied.
25

Vers une conception optimale des chaînes de traction ferroviaire / Toward optimal design of railway drivetrains

Cantegrel, Martin 27 November 2012 (has links)
Cette thèse aborde la conception optimale des chaînes de traction par l'exemple d'une chaîne de traction pour métro. Les données d'entrée de la conception d'une chaîne de traction sont la performance attendue et l'encombrement des équipements nécessaires. Pour aider le concepteur, l'outil informatique donne aujourd'hui la possibilité de construire une grande variété de modèles. D'autre part, les algorithmes d'optimisation permettent de trouver les configurations optimales. Ces possibilités ont été exploitées au cours de ce travail. Les modèles développés permettent d'estimer un large nombre de critères. A travers l'exemple de ces modèles, la méthode de conception suivie est détaillée dans le rapport. D'un point de vue technique, la chaîne de traction proposée est détaillée dans le dernier chapitre / This thesis deals with the optimal design of electric drivetrains. A drivetrain for metro is taken as an example. The input data for the design are the expected performance and the size of the required equipments.To assist the designer, the computing tool now gives the opportunity to build different sort of models. In addition, optimization algorithms allow finding optimal configurations. This work is an attempt to exploit these possibilities. The design models are used to value a large number of criteria. Through the example of these models, the design method followed is detailed in the document. From a technical point of view, the proposed drivetrain is detailed in the last chapter
26

Commande robuste de machines à réluctance variable pour la traction de véhicules électriques / robust control of a switched reluctance machine intended for electrical vehicle Propulsion.

Ouddah, Nadir 23 September 2015 (has links)
Le moteur à réluctance variable (MRV) est en train de gagner beaucoup d'intérêt dans les applications de traction électrique grâce à la compatibilité significative entre ses caractéristiques naturelles et les exigences de l'industrie automobile. Cependant, à cause de la caractéristique fortement non linéaire des grandeurs électromagnétiques du MRV, l'usure du moteur, les variations paramétriques dues aux tolérances de fabrication, et la dérive des paramètres durant le fonctionnement, les stratégies de commande classique ne permettent pas d'assurer des hautes performances de suivi de trajectoire et de robustesse en stabilité dans l'environnement de fonctionnement d'un véhicule électrique. Dans ce contexte, le premier objectif de cette thèse est de proposer des stratégies de commande robustes du MRV en prenant en considération les contraintes imposées par les applications de traction. Afin d'atteindre cet objectif, une structure de commande en cascade, composée d'une boucle externe de vitesse et d'une boucle interne de courant, est envisagée. Les objectifs de synthèse sont ensuite fixés à travers un cahier des charges formulé en termes de gabarits fréquentiels, et les correcteurs robustes et adaptatifs de vitesse et de courant sont ainsi synthétisés en se basant sur les approches de commande H-infini et LPV/H- infini. La faisabilité des correcteurs constitue également un critère important dans les applications de traction électrique où la puissance de calcul embarqué dans le véhicule est très limitée. Ce critère est pris en considération dans cette thèse à travers l'utilisation des approches de synthèse des correcteurs H- infini d'ordre fixe. Les performances de ces correcteurs sont analysées et comparées avec les performances des correcteurs H- infini classiques à travers une étude par la μ-analyse de la robustesse en stabilité et une évaluation expérimentale. Le deuxième objectif de ces travaux de thèse est d'évaluer l'intérêt de la commande sans capteurs mécanique du MRV en se basant sur des méthodes d'estimation. Des observateurs robustes basés sur les modes glissants et le filtrage de Kalman sont ainsi synthétisés. Les performances et la robustesse de ces observateurs sont ensuite comparées expérimentalement dans une perspective d'une application de traction électrique. / The switched reluctance motor (SRM) is gaining much interest in electric vehicle applications. It includes robustness to harsh operational conditions, rugged structure, fault tolerant operation and a wide range of speed. However, due to the highly nonlinear electromagnetic characteristic, wear and tear of motor, manufacturing tolerances and parameters drift during operation, classical control strategies do not ensure high dynamical performance and robustness under various operating conditions in electric vehicle environment. In this context, the first purpose of this thesis is to propose robust control strategies of the SRM taking into account the constraints imposed by electric vehicle applications. To achieve this objective, a cascade control scheme is adopted; it consists of an outer speed loop and an inner current loop. Controllers design aims are fixed through specifications formulated in frequency domain, robust and adaptive controllers of speed and currents are thus synthesized based on H- infini and LPV/H- infini control approaches. Feasibility of these controllers is also an important criterion in electric vehicles applications where embedded computing power is very limited. This criterion is taken into account in this thesis by using fixed order controller synthesis approaches. The performances of these controllers are analyzed and compared with the performances of standard H- infini controllers through an experimental evaluation and a robustness analysis is performed using the concept of the Singular Structured Value, i.e. the μ-analysis. The second objective of this thesis is to assess the interest of the sensorless control of SRM. Robust observers based on second order sliding mode (SMO2) and Kalman filtering techniques (EKF) are designed to estimate the mechanical states of SRM. Performances and robustness of these observers are then compared experimentally in perspective of electric vehicle application.
27

Pohon pásového dopravníku pro transport uhlí / Drive of coal transport belt conveyor

Kliš, Kamil January 2013 (has links)
This diploma thesis deals with designing a drivetrain for a coal belt conveyor. Thesis contains necessary calculations according to norms needed for determining suitable components of a belt conveyor. The goal of this diploma thesis was to design a drivetrain for a belt conveyor, all its components including a frame of the drivetrain and to create drawing documentation.
28

Design nákladního automobilu s elektrickým pohonem / Design of Electric Cargo Truck

Blahynka, Roman January 2014 (has links)
This master‘s thesis pertains to the design of a cargo truck with battery electric drivetrain. The presented design offers a solution which respects the technical requirements of such a vehicle, ergonomic needs of its crew, and demands on the aesthetics of a modern commercial vehicle. In consideration of the chosen drivetrain, this solution is proposed as a concept with an outlook of 10 to 15 years in the future. In keeping with the specified goals, this vehicle offers a novel appearance which attempts to characterize the electric drivetrain with certain visual elements, includes solutions that are readily available or currently in development, and optimizes ergonomics for maximum user comfort and safety.
29

Lifetime impact prediction of component modifications in axial piston units by the failure likelihood assessment

Baus, Ivan, Rahmfeld, Robert, Schumacher, Andreas, Pedersen, Henrik C. 26 June 2020 (has links)
In this paper, a new methodology is presented to estimate the lifetime impact of design changes, called Failure Likelihood Assessment (FLA). The discussion in this paper is on the fatigue lifetime prediction of axial piston units, especially after a design change. The demonstration object is an axial piston pump due to extreme environmental conditions and high specification demands, where the FLA is applied to a manufacturing change in an existing product and delivers an effect on the unit reliability. The resulted reliability imp rovement, if combined with typical calculation methods like Weibull analysis, delivers an increase in predicted lifetime considering the intended modification. As demonstration subje ct, a change of the manufacturing process of the cylinder block hub in an axial piston pump is used. The effect to the lifetime is predicted via the FLA-method and the results are calculated with test data and compared to theoretical results. The paper shows that the methodology delivers highly accurate results providing that the FLA is a powerful tool to analyze design changes as weil as new designs in regard to reliability and lifetime. The benefit for the user of this methodology will hence be more reliable products with optimized designs tobest fulfil customer's performance requirements.
30

Alternative Drivetrain for Future Freight Trucks

Tsamos, Athanasios January 2020 (has links)
Presently, heavy-duty trucks are responsible for approximately 25% of global CO2 emissions. Although the world seems to incline towards the transport sector's electrification, the electrification of long-range freight trucks is profoundly challenging. The dominant disincentives are the required infrastructure, cost/size of batteries, limited mileage, and long charging sessions. However, despite the efforts to reduce emissions, current trends indicate that these continue to rise, mostly because of the continually increasing freight transit. Regional economies are heavily dependent on the latter. Thus, the imminent depletion of fossil fuels and the emerging environmental issues are disquieting aspects for the sustainability of this crucial sector. This thesis focuses on the possible alternative powertrain/drivetrain solutions for heavy-duty, long-range freight trucks in conjunction with sustainable energy carriers for the transportation sector overall. In terms of viable fuelling alternatives, the following are being reviewed: Electric Power, Bio-Fuels, and Synthetic Fuels, along with their current status, advantages, disadvantages and future prospects. In terms of powertrain/drivetrain alternatives, the following are being theoretically and critically evaluated and compared against a direct drive conventional Diesel engine truck (25.2% wheel efficiency): Battery Electric, Electric powered with overhead cables or underground conductive coils, combined Gas Turbine/Stirling Engine Hybrid Electric in series, combined Diesel engine/Stirling engine Hybrid Electric in series, and Diesel engine Hybrid Electric in series.  It is concluded that the best scenario for future freight trucks, is the use of an electric drivetrain/powertrain in conjunction with overhead powering cables along the highways. However, due to uncertainties in the universal realization of such infrastructure, to ensure uninterrupted transportation of goods, a plausible transitional solution could be the use of a Diesel engine/Stirling engine Hybrid Electric in series technology. This could reduce emissions/consumption by a factor of 2.4 (60% wheel efficiency). For the case of Gas turbine/Stirling engine and Diesel engine (both) Hybrid Electric in-series arrangements, this factor drops to 1.7 and 1.4 (42.9% and 34.3% wheel efficiency), respectively. Furthermore, this can be a clean and sustainable solution if biofuels are employed as the prime energy carriers. Such an approach is future-proof for use with overhead cables, since the suggested powertrain is electric, rendering a freight truck as a very versatile heavy-duty, long-range vehicle. Electro-fuels are not considered as a viable option due to their inefficient formulation, elevated costs, and problematic handling (Hydrogen).

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