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Dissertations / Theses on the topic 'Gear ratios'
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1
Bejčková, Jana. "Měření zpomalení osobních automobilů při brzdění motorem." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-232895.
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The presented diploma thesis deals with the measurement of car deceleration during engine braking from different starting speeds and different speed gears with a sample of vehicles. This piece of work consists of a theoretical part, where problem background is defined, selected driving parameters including the manner how to measure them are explained and the facts in the field of structural characteristics of the vehicle are given, further from a design of measurement methodology that gives an overall plan of implementation, all the respective information and a description of handling with decelerometer, further from a real measurement of the deceleration including an interpretation of partial obtained values and finally from the evaluation of all results with appropriate conclusions.
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Kašparová, Hana. "Měření zpomalení nákladních automobilů do 12 tun při brzdění motorem." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-233050.
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This thesis deals with braking effect of the truck’s engine. The theoretical part introduces the reader to the basic construction of trucks, describes most using engine and defines the factors having a significant effect on engine braking. In the practical part the reader is familiar with the technique used in making the measurement and description of the vehicle chosen for the implementation of measurement. The result of the practical part is the values obtained by measurement including their interpretation contained in the conclusion.
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Bém, Pavel. "Optimalizace převodových poměrů závodních automobilů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228011.
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Pavel BÉM Optimisation of Gear Ratio for Race Cars DW, IAE, 2008, pp. 62, fig. 69. At first I labellig problems about gearboxes than, I review dataloggers for racing cars using now. I create model of dynamic simulating car move during at akcelerating and decelerating on choice track. I create program analyzating data from telemetry and applicated dynamic model to optimisation gears ratio.
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Sjöberg, Sören. "On the running-in of gears." Licentiate thesis, KTH, Machine Elements, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12750.
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The general trend in gear industry, today, is an increased focus on gear transmission efficiency. Gear transmission efficiency losses arise from loaded and unloaded gear contacts, seals, lubricant and bearings. One way of minimising the losses is to lower the lubricant viscosity. This will reduce the speed dependent losses. However, the load dependent losses might increase. To avoid this, the ratio between lubricant film thickness and surface roughness must be maintained, which can be fulfilled by producing smoother gear surfaces. As a starting point for this realisation process, the present manufacturing processes, the design tools and the characteristics of the gear flank interface must be further investigated and developed. This must be achieved with an emphasis on economic production.
This thesis focuses on our understanding of how different gear manufacturing methods —particularly the contribution of the running-in process—affect the surface characteristics, with the view of increasing gearbox efficiency. The thesis consists of a summary and three appended papers.
Paper A and paper B discuss the relationship between design parameters and real gear wheel surfaces manufactured with different manufacturing methods. The research hypothesis was that the contact area ratio is a descriptive parameter for the contact condition. Paper A deals with the influence of manufacturing method on the initial contact conditions and also serves as a validation of the simulation program used. The emphasis in Paper B is the changes that occur during running-in, and to correlate these changes to design requirements. Paper C approaches the influences of manganese phosphate-coating and lubricants with respect to friction and the risk of scuffing at the initial contact.
The main conclusions of this thesis are that the contact area ratio presents a descriptive measure of how surface topography influences the contact, seen at both a global (form deviation) and local (roughness) level. The surface topography caused by the manufacturing method has a significant influence on the contact area ratio. This is an important result, since neither national standards nor commercially available gear evaluation programs handle surface topography on the local scale. Shaving was found to have the highest contact area ratio, and should therefore be the best choice if deviations from case hardening could be minimised. It is also confirmed that gear-like surfaces coated with manganese phosphate have a low coefficient of friction, and raise the limiting load for scuffing failure enormously compared to the ground equivalent.
QC 20100518
KUGG
Sustainable gear transmission realization
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Li, Kang. "An Investigation into the Torque Capabilities of High Gear Ratio Magnetic Gearboxes." Thesis, The University of North Carolina at Charlotte, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10845412.
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Mechanical gears can be as small as those in traditional mechanical watches or as large as those in mechanical marine turbines. They can be seen in almost all transportation tools, for example, bicycles, cars, trains and airplanes. Though they have been studied and refined for centuries, there are still some disadvantages. For instance, mechanical gears often create a large amount of noise and vibration. They require regular maintenance as the gears need to be lubricated. In addition, if a gear is overloaded it can catastrophically fail.
Unlike conventional mechanical gears, magnetic gears can create speed change without physical contact. The force between magnetic gears is not created by geared teeth but instead, it is created by the magnetic poles. There will be a small air gap between different rotors which means no lubricant or maintenance is required. When one rotor rotates, the other one will also rotate driven by magnetic forces. Since the permanent magnets are used, the forces will not recede or disappear as long as the magnets are not overheated. If overloaded, a magnetic gearbox will simply slip poles. Therefore, in many applications, magnetic gears can be more reliable, efficient and safer.
The goal of this research has been to investigate the torque capabilities of high gear ratio magnetic geared devices. The performance has been investigated based on the gear ratio and torque density.
A new type of flux focusing cycloidal magnetic gear (MG) was investigated that could operate at a gear ratio of -25:1. The flux focusing topology was used because it increased the air gap flux density and therefore enabled a higher torque density. Using 2-D finite element analysis (FEA), the volume torque density was calculated to be 291 Nm/L with an outer diameter of 0.228 m. A -20:1 prototype cycloidal magnetic gear was designed. It had a calculated volumetric torque density of 260 Nm/L. The cycloidal magnetic gear was mechanically difficult to construct and therefore only the inner rotor of the cycloidal magnetic gear was constructed. In addition, the eccentric air gap will cause bearing failure.
To achieve an even higher gear ratio, a nested multistage magnetic gear (MSMG) was designed with a 2-D FEA calculated torque density of 424 Nm/L. The desired gear ratio was 59:1 so that the performance could be compared with a Sumitomo mechanical gearbox which had the same gear ratio. In order to minimize the rotor torque ripple, the harmonic field interaction between the inner stage and the outer stage of the magnetic gear had to be mitigated. A unique flux concentration Halbach rotor structure was proposed. The rotor structure was shown to shield the outer rotor from the inner rotor harmonics. The nested multistage magnetic gear contains 4 rotors and complex mechanical structure. In order to provide sufficient mechanical support, the mechanical axial length had to be very large and this negated many of the benefits of using the nested coaxial rotor structure.
A two-stage series connected 59:1 gear ratio multistage magnetic gear was also designed for wind turbines. The 6.45:1 first stage magnetic gearbox had a diameter of 0.633 m and the 3-D FEA calculated peak torque and torque density were 4.79 kNm and 159 Nm/L. The measured torque and torque density were 4.25 kNm and 141 Nm/L. While the 9.14:1 second stage magnetic gearbox had a diameter of 0.507 m and the 3-D FEA calculated peak torque and torque density were 1.04 kNm and 136 Nm/L, respectively. The series connected multistage magnetic gear had the advantage of being more modular as different gear ratios can be obtained by changing the pole pair combinations for one of the series connected magnetic gears.
A two-stage series connected 59:1 gear ratio multistage magnetic gear was also designed for a hydropower application. Non-magnetic rods were used to reduce the losses and the mechanical deflection. The 2-D calculated torque density for the stage 1 magnetic gear was 371 Nm/L. And the 2-D calculated torque density was 344 Nm/L for the stage 2 magnetic gear. A stator was also designed that was inserted inside the stage 2 magnetic gear. In order to try to reduce the torque ripple, the stator had a fractional winding distribution with 1.25 slots/pole/phase. (Abstract shortened by ProQuest.)
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Fajkus, Jan. "Visualizace cyklických motorů." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2010. http://www.nusl.cz/ntk/nusl-237267.
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This Master's thesis deals with application design and implementation. Application is designed for composition of gears. It is built as a simple computer game. It also contains 3D model renderer, which shows the movement of gears in gearbox. Program is implemented in C language using OpenGL library.
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Biju, Dona. "A parametric study of oil-jet lubrication in gear wheels." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150786.
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A parametric study of oil-jet lubrication in gear wheels is conducted using Computational Fluid Dynamics (CFD) to study the effect of the different design parameters on the cooling performance in a gearbox. Flow in oil jet lubrication is found to be complex with the formation of oil ligaments and droplets. Various hole radii of 1.5, 2 and 2.5 mm along with five oil velocities is analyzed and it is found that at lower volumetric rates, velocity has more effect on the cooling and at higher volumetric rates, hole size has more effect on the cooling. At higher velocities, the heat transfer is much greater than the actual heat production in the gear wheel, hence these velocity ratios are considered less suitable for jet lubrication. At low velocity ratios of below 2, the oil doesn’t fully impinge the gear bottom land and the sides leading to low cooling. Based on the cooling, impingement length and amount of oil lost to the casing surface, 2 mm hole with a velocity ratio of 2.225 is selected for a successful oil jet lubrication. Varying the inlet position in X, Y and Z directions (horizontal, vertical and lateral respectively) is found to have no improvement on the cooling. Making the oil jet hit the gear wheel surface at an angle is found to increase the cooling. Analysis with the use of a pipe to supply oil was conducted with circular and square inlet and it was found that the heat transfer decreases in both cases due to the splitting of oil jet caused by the combination of the effects of high pressure from the pipe and vorticity in the air field. A method has been developed for two gear analysis using overset meshes which can be used for further studies of jet lubrication in multi-gear systems. Single inlet is found to be better for cooling two gear wheels as it would require a reduced volumetric flow rate compared to double inlets. Oil system requirements for jet lubrication was studied and it was concluded that larger pumps have to be used to provide the high volumetric rates and highly pressurized oil required. On comparing the experimental losses from dip lubrication and the analytical losses for jet lubrication, dip lubrication is found to have lesser loses and more suitable for this case. Good quality lubrication would reduce the fuel consumption and also increase the longevity of gearboxes and hence more research into analyzing alternate lubrication systems can be carried out using the results from this thesis.
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Kliš, Vojtěch. "Koncepční návrh dvoutoké převodovky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444968.
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This thesis deals with the conceptual design of a double clutch gearbox and the inspection of selected designed parts of this gearbox. The first part of the thesis is focused on the theory of automotive transmissions and analysis of already available double clutch gearboxes. The following is the conceptual design itself, which is based on the selected vehicle on which the transmission will be located and on driving resistances. Based on these default values, the gear graduation is selected, which affects the vehicle’s driving dynamics. With regard to the installation space, a conceptual arrangement of the gearbox is proposed. Furthermore, the thesis is focused on the basic design and calculations of individual functional components of the gearbox. The last part of the thesis is involved to the control of selected structural nodes using the finite element method in the ansys workbench software. The whole thesis describes the individual steps for the design of the basic concept of a double clutch gearbox and the design of their basic components.
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New, T. M. "Random road analysis and improved gear ratio selection of a front wheel drive drag racing car." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1211387456/.
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Palmer, David. "The effects of profile relief on narrow face width parallel axis gears." Thesis, University of Huddersfield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342563.
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The well established practice of applying tip and/or root relief to the teeth of low contact ratio spur gears is reviewed. Results are presented for the experimental validation of a systematic design method for profile relief that depends critically on how far the relief extends along the path of contact. This method has proved to be effective in controlling gear vibration and noise. A good correlation between static transmission error, dynamic transmission error and sound pressure level was found. This allows design rules to be formulated which can be applied to achieve the minimum vibration and noise levels at a given operating load. A computer program was also developed that allows the introduction of measured gear tooth profiles from an involute tester, to predict the static transmission error curves and thus give an indication of gear quality as regards vibration and noise levels for any given simulated operating load or load range. The computer program was extended to take into consideration the more complex geometry of helical gears using the 'Thin Slice' theory. This allows the prediction of the effects of lead crowning, misalignment, pitch errors and various profile reliefs including relief coined "cross relief", where the relief is applied parallel to the base helix angle. An optimisation routine was included in the computer program that systematically varies the extent of profile relief and amount of lead crowning to minimise transmission error. Since the amount of required profile relief is concomitant with extent of relief and amount of lead crowning (load remaining constant), the program iterates to find the correct amount of profile relief to avoid undesirable comer/tip contact. This new approach has facilitated the generalisation of the effects of profile relief on transmission error for a whole range of typical axial and transverse contact ratios for narrow face width helical gears, previous analyses concentrating on specific designs. Results are also presented for the experimental validation of predicted static transmission error in helical gears. A good correlation between static transmission error, dynamic transmission error and sound pressure level was found as in the spur gear analysis.
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Gurkan, Niyazi Ersan. "Non-linear Mathematical Modeling Of Gear Rotor Bearing Systems Including Bearing Clearance." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606798/index.pdf.
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ABSTRACT
NON-LINEAR MATHEMATICAL MODELING
OF GEAR-ROTOR-BEARING SYSTEMS
INCLUDING BEARING CLEARANCE
GÜRKAN, Niyazi Ersan M.S. Department of Mechanical Engineering Supervisor: Prof. Dr. H. Nevzat Ö
ZGÜ
VEN November 2005, 130 pages In this study, a non-linear mathematical model of gear-rotor systems which consists of elastic shafts on elastic bearings with clearance and coupled by a non-linear gear mesh interface is developed. The mathematical model and the software (NLGRD 2.0) developed in a previous study is extended to include the non-linear effects due to bearing clearances by using non-linear bearing models. The model developed combines the versatility of using finite element method and the rigorous treatment of non-linear effect of backlash and bearing clearances on the dynamics of the system. The software uses the output of Load Distribution Program (LDP), which computes loaded static transmission error and mesh compliance for the contact points of a typical mesh cycle, as input. Although non-varying mesh compliance is assumed in the model, the excitation effect of time varying mesh stiffness is indirectly included through the loaded static transmission error, which is taken as a displacement input into the system. Previous computer program which was written in Fortran 77 is rewritten by using MatLAB 7.0 and named as NLGRD (Non-Linear Geared Rotor Dynamics) Version 3.0. The program is highly flexible and open to further developments. The program calculates dynamic to static load ratio, dynamic transmission error, forces and displacements at bearings. The mathematical model suggested and the code (NLGRD version 3.0) are validated by comparing the numerical results obtained from the model suggested with experimental data available in literature. The results are also compared with those of previously developed non-linear models. The effects of different system parameters such as bearing stiffness, bearing clearance and backlash on the gears are investigated. The emphasis is placed on the interaction of clearances in bearings with other system parameters.
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Півень, Д. A. "Проєкт вантажного автомобіля з дослідженням технологічного процесу відновлення впускного клапана та відновлення вилки кардану /комплексний прєкт/." Thesis, Чернігів, 2021. http://ir.stu.cn.ua/123456789/25316.
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Півень, Д. A. Проєкт вантажного автомобіля з дослідженням технологічного процесу відновлення впускного клапана та відновлення вилки кардану /комплексний прєкт/ : випускна кваліфікаційна робота : 274 "Автомобільний транспорт" / Д. А. Півень ; керівник роботи В. В. Кальченко ; НУ "Чернігівська політехніка", кафедра автомобільного транспорту та галузевого машинобудування. – Чернігів, 2021. – 137 с.Моя дипломна робота має в собі розрахунки параметрів автомобіля, якого я обрав для розробки в дипломному проекті, це автомобіля малої вантажопідйомності вантажний УАЗ 3303, який має переваги над іншими малими вантажними автомобілями через повний привід, що дає змогу експлуатувати автомобіль навіть й по бездоріжжю з вантажем. Виконав загальний розрахунок автомобіля його параметрів, визначив потужність двигуна та зробив повний його розрахунок. В спеціальній частині магістерського диплому виконав розрахунок підвіски автомобіля УАЗ 3303, також дослідив процес відновлення впускного клапана малого вантажного автомобіля. Для виконання розрахунків та графічної частини використовувались такі спеціальні програми як: “Mathcad”, “Компас 3D”, “Paint” та ножиці.
My dissertation includes calculations of the parameters of the car I chose to develop in the thesis project, it is a low-load truck UAZ 3303, which has advantages over other small trucks due to all-wheel drive, which allows you to operate the car even off-road with cargo . Performed a general calculation of the car's parameters, determined the engine power and made a complete calculation. In a special part of the master's degree he calculated the suspension of the car UAZ 3303, also investigated the process of restoring the intake valve of a small truck. Special programs such as Mathcad, Compass 3D, Paint and scissors were used to perform calculations and graphics.
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Girard, Alexandre 1987. "Fast and strong lightweight robots based on variable gear ratio actuators and control algorithms leveraging the natural dynamics." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111689.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 191-196).
In many applications, robots have to bear large loads while moving slowly and also have to move quickly through the air with almost no load. These type of bi-modal tasks, with conflicting requirements in terms of operating speeds and desired impedances, often lead to the use of oversized and inefficient actuators which are inhibitory particularly for mobile robots. Multiple gear ratios, like in a powertrain, address this issue by allowing an effective use of power over a wide range of output speeds, by enabling significant changes to the reflected intrinsic actuator impedances and by making possible the leveraging or attenuation of the natural load dynamics. This thesis aims to develop the technological solutions needed to use variable gear ratio actuators and exploit the advantages of variable transmissions in a robotic context. First, by addressing the issue of how to make fast and seamless gearshifts between two very different reduction ratios under diverse load conditions, with a solution based on a dual-motor actuator architecture and a control scheme using the null space. Second, by developing control algorithms that select optimal gear ratios dynamically based on state feedback, to move with minimal motor torques and to adjust the output impedance appropriately given a task. The proposed approach exploit variable transmissions not merely for increasing maximum torque and speed, but also to significantly alter the dynamic properties, including load sensitivity, robustness, and backdrivability. Simulations and experiments using a novel lightweight robotic arm using three custom-built dual-speed dual-motor actuators are presented. Results demonstrate very fast gear shifting in highly dynamic situations with dual-speed dual-motor actuators, and show that actively changing gear ratios using the proposed control algorithms can lead to an order-of-magnitude reduction of necessary motor torque and power.
by Alexandre Girard.
Ph. D.
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Райський, Д. М. "Проєкт легкового автомобіля з дослідженям технологічного процесу відновлення шарніра рівних кутових швидкостей, відновлення розподільчого валу." Thesis, Чернігів, 2021. http://ir.stu.cn.ua/123456789/25317.
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Райський, Д. М. Проєкт легкового автомобіля з дослідженям технологічного процесу відновлення шарніра рівних кутових швидкостей, відновлення розподільчого валу : випускна кваліфікаційна робота : 274 "Автомобільний транспорт" / Д. М. Райський ; керівник роботи В. І. Кальченко ; НУ "Чернігівська політехніка", кафедра автомобільного транспорту та галузевого машинобудування. – Чернігів, 2021. – 153 с.В ході написання роботи магістра, було проведено аналіз схожих за конструкцію автомобілі, вибрав прототип ГАЗ 3110, виконав розрахунок потужності двигуна, вирахував передаточні числа коробки перемикання. Виконав тепловий розрахунок двигуна й креслення до нього з графіками. Визначив показники динамічності руху автомобіля при рівномірному та не рівномірному завантаженні. Розрахував витрату палива автомобіля на сто кілометрів шляху. В подальшій частині розрахував параметри гальмівної системи барабанного типу, виконав модернізацію системи та розрахував дискові гальма. Також одним із завдань було відновлення розподільчого валу, в укому я вибрав способи відновлення деталі, підібрав обладнання, розрахував припуски та час на обробку кожного з дефектів. Для виконання розрахунків та графічної частини використовувались такі спеціальні програми як: “Mathcad”, “Компас 3D”, “Paint”.
In the course of writing the master's thesis, an analysis of similar cars was made, he chose a prototype GAZ 3110, calculated the engine power, calculated the gear ratios of the gearbox. Performed thermal calculation of the engine and drawings to it with graphs. Determined the dynamics of the car with uniform and non-uniform loading. Calculated the fuel consumption of the car for a hundred kilometers. In the further part he calculated the parameters of the drum-type brake system, performed system modernization and calculated disc brakes. Also, one of the tasks was to restore the camshaft, in which I chose ways to restore the part, selected the equipment, calculated the allowances and time to process each of the defects. Special programs such as “Mathcad”, “Compass 3D”, “Paint” were used to perform calculations and graphics.
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Santos, Taisa de Oliveira. "Injeção intracerebroventricular de estreptozotocina gera efeitos agudos e crônicos sobre a memória e sobre proteínas indicadoras de neurodereneração em ratos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/47/47135/tde-16072010-091230/.
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A Doença de Alzheimer (DA) é a causa mais comum de demência e é caracterizada clinicamente por comprometimentos cognitivos. Histologicamente é caracterizada pela formação de placas senis e de emaranhados neurofibrilares intracelulares resultantes de alterações do metabolismo do peptídeo A e da hiperfosforilação da proteína tau, respectivamente. Essas alterações parecem, em parte, ser uma decorrência de uma deficiência na sinalização da insulina e conseqüente resistência do encéfalo a esse hormônio, sugerindo que a DA esporádica tenha uma relação com o Diabetes mellitus. A estreptozotocina tem sido utilizada como modelo de indução do Diabetes, e mais recentemente como modelo experimental da DA quando administrado intracerebroventricular. Nosso objetivo nesse estudo foi o de caracterizar o esse modelo experimental da DA induzido pela estreptozotocina, avaliando as conseqüências agudas e a longo prazo. Foram utilizados ratos Wistar machos de quatro meses de idade que receberam injeções intracerebroventriculares bilaterais de estreptozotocina ou de veículo. Os animais foram avaliados aguda e cronicamente por testes comportamentais de memória de referência e operacional utilizando o modelo do labirinto aquático de Morris que visavam avaliar o curso temporal dos prejuízos cognitivos após a injeção da droga. Em diferentes tempos após as injeções, os ratos foram sacrificados e regiões do encéfalo submetidas à técnica de immunoblotting para avaliação de proteínas indicadoras de neurodegeneração ou à técnica histoquimica pelo método de Fluoro-Jade C. A avaliação da memória operacional em períodos agudos mostrou que os prejuízos cognitivos parecem se instalar a partir de 3 horas da injeção de estreptozotocina. A avaliação crônica das memórias operacional e de referência mostrou que os ratos exibiram um prejuízo marcante no desempenho dessas tarefas ao longo dos testes, embora seja correto afirmar que esses animais ainda são capazes de adquirir informação relevante com relação à execução da tarefa, particularmente na versão de memória de referência. A análise de immunoblotting mostrou haver aumento da expressão do peptídeo beta amilóide significante em regiões como amigdala, córtex entorrinal, núcleos da base e do hipotálamo. Também foi observado um aumento significativo da fosforilação da proteína tau na amigdala, cerebelo, córtex, prosencéfalo basal e núcleos da base. Foi observada uma diminuição da enzima de síntese de acetilcolina, a colina acetil-transferase apenas na amigdala. Fibras em degeneração foram observadas no hipotálamo, na área septal e em neurônios piramidais na região CA1 após 1 dia da injeção de estreptozotocina. Já após 15 dias da injeção podemos observar marcação em neurônios do estriado e da região CA1 do hipocampo e em fibras próximas ao giro denteado. Em resumo a injeção intracerebroventricular de estreptozotocina parece produzir um bom modelo experimental da DA, pois reproduz as características cognitivas e histológicas encontradas nos pacientes com a doençaAlzheimer´s disease (AD) is the most common cause of dementia in aged humans. Recent reports have suggested a relationship between the onset of AD and an insulin-resistant brain condition. In this context, this study aimed at evaluating the effects of intracerebroventricular (ICV) injection of streptozotocin (STZ) in rats on behavior and neurodegeneration. Four month-old adult male Wistar rats were subjected to bilateral ICV injections of either STZ or vehicle and were tested for both reference and working memories in Morris water maze. After different survival times, rats were subjected to immunoblotting (to evaluate neurodegeneration markers) or to Fluoro-Jade C histochemistry. A marked disruption of performance in working memory was already observed after 3 hours of STZ injections. Immunoblotting analysis showed a significant increase of beta amyloid peptide expression in the amygdala, entorrinal cortex, basal ganglia, and hypothalamus. A significant increase of tau phosphorylation was also observed in the amygdala, cerebellum, cortex, basal forebrain and basal ganglia. Degenerating fibers were seen in the hypothalamus and septal area 1 day postinjection and in CA1 pyramidal neurons and close to the hippocampal dentate gyrus after 15 days. ICV injection of STZ seems therefore to produce an animal model of AD, as it reproduces the characteristic cognitive and histological changes of the disease
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Czakó, Alexander. "Stanovení chyby převodu u čelního ozubení s šikmými zuby." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-433537.
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This diploma thesis primarily deals with the transmission error issue which is one of the dominant sources of vibration in gear pairs and transmission systems. The vibrations subsequently generate noise which is often subjected to increasingly stricter demands across the industry, including the automotive one. It turns out that reducing the peak-to-peak value of the transmission error has a beneficial effect on the vibro-acoustic properties of gears and gear pairs. This thesis aims to determine the transmission error under static conditions, since a gear pair with a low static transmission error is a good assumption for a low transmission error even under dynamic effects. The resulting values of the transmission error can be influenced already during the design of the gear macro-geometry. It is also suitable to apply micro-geometric adjustments – modifications to the gear teeth. For this reason, the search part of the thesis is dedicated to theoretical knowledge, especially concerning the geometry of gears, modifications of teeth and the overall transmission error and its determination. The transmission error can be determined in several ways, including a technical experiment. However, due to time and financial reasons, this is not always possible, and therefore, the possibility of using numerical simulations is offered. In this thesis, the approach using stress-strain quasi-static contact analysis using the finite element method in Ansys Workbench software is used. The advantage is, among other things, a good comparability of results. The input to the FEM analysis is 3D CAD geometry – in this case, it is specifically a helical gear pair with parallel axes. The model/assembly of this gear pair is created in PTC Creo software fully parametrically, so it is possible to generate arbitrary gear pair configurations by changing the input parameters, which significantly saves time. At the end of this diploma thesis, the stress-strain analysis of various gear configurations is evaluated, with respect to the equivalent stress and contact pressure. Furthermore, the static transmission error – its graphs and peak-to-peak values – is determined from FEM analyses for different gear geometry, including tooth modifications, and for various loading torques. Last but not least, the effects of contact/overlap ratio and centre distance are evaluated.
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Cunelius, Erik. "Analysis of Potential Determinants of Cycle Commuting Speed : With Special Reference to Gears, Showers, and Ratings of Perceived Exertion." Thesis, Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-6234.
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Aim: The aim of this study is to analyse potential determinants of cycle commuting speed, with the following research questions: 1. How does cycle commuting speed relate to amount of gears, access to shower facilities, and rating of perceived exertion (RPE), when sex, age, weight, body mass index (BMI), duration, last digit in self-reported duration, and cycling area are controlled for? 2. How are the earlier found relationships between speed and duration, and speed and sex, affected when amount of gears, access to shower facilities, and RPE are added to the control variables age, weight, BMI, last digit in self-reported duration, and cycling area? Method: In this cross-sectional study, 1526 adult cycle commuters (67% females) in Stockholm County, Sweden, were recruited through advertisements. In a self-administered questionnaire, the respondents reported their sex, age, height, weight, duration of their typical cycle commuting journey, amount of gears, access to shower facilities at the destination, and rating of perceived exertion (measured by the Borg RPE Scale) while cycling. They also drew their cycling route on an individually adjusted map. Multiple linear regression was used to facilitate the analyses. Results: In a regression model with the independent variables sex, age, weight, body mass index, duration, last digit in self-reported duration (1–4 or 6–9 compared to 0 or 5), cycling area (inner urban compared to suburban and suburban – inner urban), gears, shower facilities, and RPE, the dependent variable cycle commuting speed was positively related to using a bicycle with five or more (as compared to four or fewer) gears, having convenient (as opposed to inconvenient or non-existent) access to shower facilities, and perceiving a higher degree of exertion while cycling. Gears, showers, and RPE were also found to substantially affect the earlier found relationships between speed and duration, and speed and sex. The respondents showed a clear tendency of giving odd-numbered, compared to even-numbered, ratings of perceived exertion. Conclusions: This study highlights the importance of gears, showers, and RPE in activities such as estimating, planning or taking measures in relation to cycle commuting. It also shows that adding new factors to control for might change earlier established relationships within this field. When the Borg RPE Scale is used, correct instructions strengthens the validity.Syfte och frågeställningar: Syftet med denna studie är att analysera potentiella påverkansfaktorer gällande cykelpendlingshastighet, med följande frågeställningar: 1. Hur relaterar hastighet till antal växlar, tillgång till duschfaciliteter och skattning av egenupplevd fysisk ansträngningsgrad (RPE), när kön, ålder, vikt, BMI, duration, slutsiffra i självrapporterad duration samt cykelområde kontrolleras? 2. Hur påverkas de tidigare funna förhållandena mellan hastighet och duration, samt hastighet och kön, när antal växlar, tillgång till duschfaciliteter och RPE adderas till kontrollvariablerna ålder, vikt, BMI, slutsiffra i självrapporterad duration, och cykelområde? Metod: I denna tvärsnittsstudie rekryterades 1526 vuxna cykelpendlare (67% kvinnor) i Stockholms län genom annonser. I ett själv-administrerat formulär rapporterade de kön, ålder, längd, vikt, duration vid deras typiska cykelpendlingsresa, antal växlar, tillgång till duschfaciliteter vid destinationen, och skattning av egenupplevd fysisk ansträngningsgrad (enligt Borgskalan) under cyklingen. De ritade även in sin cykelväg på en individuellt anpassad karta. Multipel linjär regression användes för att möjliggöra analyserna. Resultat: I en regressionsmodell med de oberoende variablerna kön, ålder, vikt, BMI, duration, slutsiffra i självrapporterad duration (1–4 eller 6–9 jämfört med 0 eller 5), cykelområde (innerstad i jämförelse med ytterstad samt ytterstad – innerstad), växlar, duschmöjligheter och RPE, var den beroende variabeln cykelhastighet positivt relaterad till användandet av en cykel med fem växlar eller fler (i jämförelse med fyra eller färre), att ha bekväm tillgång till dusch (i motsats till obekväm eller ingen tillgång alls) samt att uppleva en högre grad av fysisk ansträngning under cykling. Växlar, duschmöjligheter och RPE visade sig även substantiellt påverka de tidigare funna förhållandena mellan hastighet och duration, samt hastighet och kön. Respondenterna visade en tydlig tendens att ge ojämna, i jämförelse med jämna, RPE-skattningar. Slutsats: Denna studie belyser vikten av växlar, duschmöjligheter och egenupplevd ansträngningsgrad vid exempelvis bedömning, planering eller vidtagande av åtgärder i relation till cykelpendling. Den visar även att nya kontrollfaktorer kan förändra tidigare etablerade förhållanden inom detta fält. Korrekta instruktioner stärker validiteten vid användandet av Borgskalan.
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Novotný, Tomáš. "Návrh převodového ústrojí motocyklu s elektrickým pohonem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378513.
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The aim of the thesis is a summarization of current state of knowledge of motorcycle clutches and transmissions and subsequent design of clutch and transmission for electric powered motorcycle. The main topic is design of the clutch of which components were processed by stress analysis and designed for fatigue safety. On top of that, the thesis deals with the design of primary transmission and gear ratios.
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Ostiguy, Matthew James. "Experiment and Simulation of the Acoustic Signature of Fatigued-Cracked Gears in a Two-Stage Gearbox." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1328.
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This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy ratio comparison yielded the computer simulation accurately modeled the difference between a healthy and damaged gearbox. The next step in this study involved the development of a repeatable procedure to initiate and propagate a fatigue crack at the tooth root in an actual spur gear. A damaged spur gear allows for a future comparison of an actual healthy and damaged gearbox system in the lab. A custom fatigue fixture was designed and manufactured for a Martin S1224BS 1 spur gear. The fatigue crack was initiated by position control fatigue testing which deflects the gear tooth a set amplitude for a number of cycles. Over the length of the test, the load that the tooth can withstand in bending decreases as damage begins to occur. Once the max load on the gear has dropped by a significant percentage (5-15%) a crack has initiated and begun to propagate across the tooth face. The use of a scanning electron microscope confirmed the presence a fatigue crack.
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Yousef, Ornina, and Legrand Gianina Perez. "Vilken fond ger hög riskjusterad avkastning? : En empirisk studie mellan Svenska och Globala aktiefonder." Thesis, Södertörns högskola, Institutionen för samhällsvetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-18913.
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Syfte: Syftet med denna undersökning är att göra en komparativ studie mellan Sverige-och global aktiefonder för att vidare analysera vilka aktiefonder som ger högst avkastning. Metod: Uppsatsen bygger på en statistisk analys vilket sekundärdata ligger till grund för våra beräkningar. Genom tillämpning av kvantifierbar hård data där bland annat historiska aktiekurser ingår, så har en kvantitativ studie använts. Befintliga teorier och modeller har tillämpats. Slutsats: Studien visar i stort sett att högre risk ger en högre avkastning. Under period 1 presterade Latin Amerika fonderna bäst varefter Sverige fonder presterade bättre under period 2. Dessa marknader kan vara väldigt oberoende av varandra och tenderar därmed inte att följa varandras kursutveckingen. Slutsatsen är då att en investering i olika geografiska placeringar diversifierar risken mer. Exempelvis en investering i en svensk fond och en latin amerika fond.
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Whitbread, Michael Andrew Ian, and n/a. "Lithogeochemichal alteration aound the Century and Elura Zn-Pb-Ag deposits: detecting alteration expressions in deep and near surface environments." University of Canberra. Resource, Environmental & Heritage Sciences, 2004. http://erl.canberra.edu.au./public/adt-AUC20051129.112425.
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Exploration companies commonly rely on geochemistry to identify alteration of
distinctive geochemical and mineralogical character, surrounding metal sulphide
deposits that were precipitated from hydrothermal fluids. However, examination of
raw analytical data is prone to error due to closure effects and the difficulty in
removing the effects of background variation in unaltered rocks from the variations
imposed by later hydrothermal alteration. Closure can be avoided by using ratios, or
by utilising mass balance approaches based on fixing volume, mass or concentration
changes between samples of parent and daughter lithologies. Using a parent-daughter
approach is limiting, because only pairs of samples can be compared at any one time
and because an unaltered equivalent must be produced for each sample examined in
this way. Pearce Element Ratio analysis and General Element Ratio analysis (PER
and GER) are not restricted in this fashion, and are more amenable to interrogation of
large data sets. PER and GER are also capable of decoupling background variation
from that variation due to hydrothermal alteration. Furthermore, these ratio methods
are readily applied to commercially derived lithogeochemical assays.
In this study, various analytical methods and interpretive techniques (including PER
and GER) have been applied to identify alteration in rocks around the Century and
Elura Zn-Pb-Ag deposits, and to assess whether primary ore-related alteration effects
can still be identified once altered rocks have been subjected to weathering.
Ratios of trace elements over a conserved element have been used to generate a suite
of pathfinder elements for each deposit. Elements enriched in host rocks around both
deposits include the economic metals Zn, Pb and Ag, along with Rb and Tl. Sodium is
ubiquitously depleted in altered rocks. Other elements in the pathfinder suites are
distinctive to each deposit type, and include a number of major and trace elements
that are added or removed from the rocks around the mineralised zones. For example,
Sb and As are enriched in rocks around Elura mineralisation while Ge and Cd are
enriched in samples around Century deposit.
Iron carbonate development accompanied by potassic alteration, the destruction of
albite and the absence of chlorite are the dominant mineral alteration effects at both
deposits. PER and GER diagrams have been used to quantify the intensity of this
alteration and allow lithogeochemistry to be used to vector towards high intensity
alteration, which is adjacent to Century and Elura mineralisation. These ratio methods
are applied to both visibly and cryptically altered rocks at both deposits, and have a
very high degree of success in classifying alteration in unweathered rocks.
The following simple PER ratios indicate proximity to Elura mineralisation:
Ca/C, K/Al for shales, K/(Al-Na) for siltstones/sandstones.
The following simple PER ratios indicate proximity to Century mineralisation:
Mn/Ti, Mg/Ti and Fe/Ti vs C/Ti, K/Ti vs Al/Ti, K/Ti vs (Al-Na)/Ti.
Pathfinder elements can be overlain onto PER and GER diagrams to aid in ranking the
prospectivity of samples, and to assess mineral hosts for individual pathfinder
elements.
Weathering destroys most indicators of alteration in the Elura area, while alteration
signatures are better preserved in host rocks around the Century deposit.
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Sousa, J?nior Francisco Souto de. "Desenvolvendo e gerenciando compostagem de res?duos s?lidos urbanos: para gera??o de renda e repasse de tecnologia ? acrevi." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18675.
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Previous issue date: 2011-07-11Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Nowadays, as well as in the past decades, the dumping of biodegradable organic waste in landfill is common practice in Brazil, as well as in most parts of the world. Nevertheless due to its rapid decomposition and release of odors, this practice hamper?s the operation and implementation of a recycling system. These facts encouraged our research to find an efficient system for the management of organic waste, not only for the use of official workers responsible for managing these wastes, but also for non-governmental institutions. The Recycling for Life Community Association ? ACREVI (Associa??o Comunit?ria Reciclando para a Vida), together with the municipal authorities of Mossor?-RN, Brazil, have assumed the social role of collecting and recycling solid waste produced by most of the local population. However, it was observed that the organic waste it collected was not receiving any treatment. This present work aims to make compost with mixed waste (green waste and organic household), and then do chemical analysis of the material in view to use the waste as organic fertilizer. The objective being: to share the knowledge acquired by putting it into a very simple language accessible to people with little education. The experiment was conducted at ACREVI, Mossor? (RN), and the compost was obtained following the method "windrow", forming three cells (I, II, III) with conical shape, dimensions of 1.6 meters and 2.0 meters in diameter for cells I and II, and 1.0 meters high and 2.0 meters in diameter for cell III. The process was accompanied by analysis: CHN elemental, a variation of cell temperature, humidity, pH, TKN, bulk density, nutrients and heavy metals. Stabilized organic compounds reached the C/N ratio of 10.4/1 cell I and 10.4/1 in the cell II in the cell, showing how good soil conditions, with potential to improve the physical properties of any soil and pH acid soils, has presented the cell III at the end of the process the C/N 26/1, is a high ratio may be associated with the stack size III, thus changing the optimal conditions for the occurrence of the process. The levels of heavy metals in the analyzed compounds were lower than those established by the SDA normative instruction, N? 27, of 5 June, 2006. The use of pruning trees and grass are used in small-scale composting, while generating a quality compost in the final process, it also created an important condition for a correct sizing of the composting piles. Under the studied conditions it is not advisable to use cells with a height of 1.00 m in height and 2.00 m in diameter, as these do not prevent the rapid dissipation of heat and thus can not be a good product at the end of composting. The composting process in the shed of the association and the preparation of the primer enabled the development of an alternative technology to generate income for members of ACREVI.
Durante d?cadas e ainda hoje no Brasil, assim como em muitos pa?ses do mundo a deposi??o de res?duos org?nicos biodegrad?veis em aterro foi uma pr?tica muito comum, pois a r?pida decomposi??o e a libera??o de odores destes res?duos dificultam a operacionaliza??o e aplica??o de um sistema de reciclagem. Estes fatos incentivam ? busca de medidas eficientes para a gest?o de res?duos org?nicos n?o s? nas entidades oficiais respons?veis pela gest?o destes res?duos, mas tamb?m nas institui??es n?o governamentais. A Associa??o Comunit?ria Reciclando para a Vida ACREVI, com o apoio da prefeitura municipal de Mossor?, Brasil, tem assumido o papel social da coleta e reciclagem de res?duos s?lidos produzido por grande parte da popula??o local. Por?m, observou-se que os res?duos org?nicos que ela coleta n?o est?o recebendo qualquer tratamento. Nesse trabalho objetivou-se realizar a compostagem com misturas de res?duos urbanos (res?duos verdes e org?nicos domiciliares), fazer a an?lise qu?mica desse material, tendo em vista sua utiliza??o como adubo org?nico, e repassar o conhecimento produzido em linguagem bem simples e acess?vel a pessoas com baixa escolaridade via produ??o de uma cartilha de compostagem. O experimento foi realizado na ACREVI, Mossor? (RN) e o produto da compostagem foi obtido seguindo o m?todo windrow , formando tr?s pilhas (I, II, III) com formato c?nico, dimens?es de 1,6 metros de altura e 2,0 metros de di?metro para as pilhas I e II, e 1,0 metro de altura e 2,0 metros de di?metro para a pilha III. O processo foi acompanhado atrav?s das an?lises: elementar de CHN, varia??o de temperatura da pilha, grau de umidade, pH, NTK, densidade aparente, metais pesados e nutrientes. Os compostos org?nicos estabilizados atingiram a rela??o C/N de 10,4/1 na pilha I e 10,4/1 na pilha II, mostrando-se como bons condicionantes de solo, apresentando potencial para melhorar as propriedades f?sicas de qualquer solo e o pH de solos ?cidos, j? a pilha III apresentou no final do processo rela??o C/N 26/1, est? alta rela??o pode ser associada ao tamanho da pilha III, alterando desta forma as condi??es ideais para ocorr?ncia do processo. Os teores de metais pesados analisados nos compostos foram inferiores aos estabelecidos pela instru??o normativa SDA, N? 27 de 05 de Junho de 2006. O uso de podas de arvores e gramas, utilizadas na compostagem em pequena escala, ao mesmo tempo em que gerou um composto de qualidade no produto final do processo, tamb?m criou uma condi??o importante para um correto dimensionamento das pilhas de compostagem. Nas condi??es estudadas n?o ? aconselh?vel utilizar pilhas com altura de 1,00 m de altura e 2,00 m de di?metro, pois estas n?o impedem a r?pida dissipa??o de calor e assim n?o se consegue um bom produto no final da compostagem. O processo de compostagem no galp?o da associa??o e a elabora??o da cartilha viabilizou o desenvolvimento de uma tecnologia alternativa de gera??o de renda para os associados da ACREVI
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Milan, Rackov. "Концепције развоја универзалних зупчастих редуктора." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2013. https://www.cris.uns.ac.rs/record.jsf?recordId=85580&source=NDLTD&language=en.
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Дат је детаљан преглед садашњих концепцијских решења и начинамонтаже савремених универзалних зупчастих редуктора.Карактеристике ових решења анализиране су посредством јединичних икомплексних показатеља квалитета. Резултати те анализе приказани суна систематичан и јасан начин, коришћењем табела, дијаграма и схема.Тумачење резултата је јасно и адекватно, с нагласком на значајнеделове који су од посебне важности. Предложено решење зупчастогредуктора за усвојену осну висину је коректно дефинисано ипостављено на основу претходно извршених анализа. Начин усвајањазупчастих парова, као и појединих конструкционих решења извршен јена јасно образложен начин. Такође, дат је предлог за увођење зубаца саповећаном теменом висином.Dat je detaljan pregled sadašnjih koncepcijskih rešenja i načinamontaže savremenih univerzalnih zupčastih reduktora.Karakteristike ovih rešenja analizirane su posredstvom jediničnih ikompleksnih pokazatelja kvaliteta. Rezultati te analize prikazani suna sistematičan i jasan način, korišćenjem tabela, dijagrama i shema.Tumačenje rezultata je jasno i adekvatno, s naglaskom na značajnedelove koji su od posebne važnosti. Predloženo rešenje zupčastogreduktora za usvojenu osnu visinu je korektno definisano ipostavljeno na osnovu prethodno izvršenih analiza. Način usvajanjazupčastih parova, kao i pojedinih konstrukcionih rešenja izvršen jena jasno obrazložen način. Takođe, dat je predlog za uvođenje zubaca sapovećanom temenom visinom.
Detailed overview of current solutions and conceptual mounting ways ofmodern universal helical gear reducer is presented. The characteristics ofthese solutions are analyzed by means of the unit and complex qualityindicators. The results of this analysis are presented in a systematic andclear way, using tables, charts and diagrams. Interpretation of the results isclear and appropriate, with an emphasis on the important parts of which areof particular importance. The proposed solution of gear reducer for adoptedshaft height is correctly defined and set to the previously performed analysis.The way the adoption of gear pairs, as well as some innovative designs areexecuted on clearly reasoned manner. Also, a proposal for the introduction ofhigh contact ratio is given.
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Gavrilovic, Nenad. "VIBRATION-BASED HEALTH MONITORING OF ROTATING SYSTEMS WITH GYROSCOPIC EFFECT." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1358.
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This thesis focuses on the simulation of the gyroscopic effect using the software MSC Adams. A simple shaft-disk system was created and parameter of the sys-tem were changed in order to study the influence of the gyroscopic effect. It was shown that an increasing bearing stiffness reduces the precession motion. Fur-thermore, it was shown that the gyroscopic effect vanishes if the disk of system is placed symmetrically on the shaft, which reduces the system to a Jeffcott-Ro-tor. The second objective of this study was to analyze different defects in a simple fixed axis gear set. In particular, a cracked shaft, a cracked pinion and a chipped pinion as well as a healthy gear system were created and tested in Adams. The contact force between the two gears was monitored and the 2D and 3D frequency spectrum, as well as the Wavelet Transform, were plotted in order to compare the individual defects. It was shown that the Wavelet Transform is a powerful tool, capable of identifying a cracked gear with a non-constant speed. The last part of this study included fault detection with statistical methods as well as with the Sideband Energy Ratio (SER). The time domain signal of the individual faults were used to compare the mean, the standard deviation and the root mean square. Furthermore, the noise profile in the frequency spectrum was tracked with statistical methods using the mean and the standard deviation. It was demonstrated that it is possible to identify a cracked gear, as well as a chipped gear, with statistical methods. However, a cracked shaft could not be identified. The results also show that SER was only capable to identify major defects in a gear system such as a chipped tooth.
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Каретін, Василь Миколайович. "Обґрунтування параметрів інерційного планетарного запобіжного механізму гвинтових конвеєрів." Diss., Тернопільський національний технічний університет ім. Івана Пулюя, 2021. http://elartu.tntu.edu.ua/handle/lib/34832.
Full textAbstract:
Дисертація на здобуття наукового ступеня кандидата технічних наук за
спеціальністю 05.05.05 «Піднімально-транспортні машини». – Тернопільський
національний технічний університет імені Івана Пулюя, Тернопіль, 2021.
У дисертації на підставі сукупності узагальнених наукових результатів
вирішено нове актуальне завдання підвищення технологічної ефективності
процесу роботи гвинтових транспортних механізмів шляхом удосконалення
конструкції та обґрунтування параметрів інерційної планетарної запобіжної
муфти, яку виконано на основі біпланетарного інерційного механізму з рухомою
реактивною ланкою.
На основі проведених теоретично-експериментальних досліджень
розроблено: аналітичні залежності, які дозволяють аналізувати переміщення
точки дебалансу та механізму загалом; аналітичні залежності для визначення
кінематичних і динамічних параметрів стопового режиму роботи гвинтового
конвеєра з інерційною планетарною запобіжною муфтою; емпіричні рівняння, які
характеризують зміну гальмівного обертового моменту стопового режиму роботи
та коефіцієнта корисної дії передачі обертового моменту.
На основі проведених теоретичних і експериментальних досліджень
обґрунтовано основні раціональні параметри інерційної планетарної запобіжної
муфти гвинтового конвеєра.
Максимальний обертовий момент вихідного вала інерційної планетарної
запобіжної муфти гвинтового конвеєра у стоповому режимі формується шляхом
зростання енергії дебаланса за рахунок збільшення швидкостей обертання
дебаланса навколо своєї осі та осі привода імпульсного модуля та змінюється в
діапазоні 19,6 … 29,4 Н∙м за відповідного передаточного відношення приводу
дебаланса, що дорівнює 2,2.
Раціональне функціонування процесу роботи гвинтового конвеєра з метою
забезпечення максимального гальмівного обертового моменту вихідного вала при
виникненні перевантаження його робочих органів у межах від 20 Н∙м до 42 Н∙м,
або початку стопового режиму роботи гвинтового конвеєра досягнуто за
наступних параметрів: частота обертання вхідного вала ІПЗМ від 262,5 об/хв до
437,5 об/хв; передаточне відношення приводу верхнього дебалансу від 2,0 до 3,2;
передаточне відношення приводу нижнього дебалансу рівне 1,0. Конструктивна новизна технічного рішення захищена патентом України на корисну модель.The dissertation for obtaining a scientific degree of the Candidate of technical sciences on a specialty 05.05.05 "Lifting and transportation machinery". – Ternopil Ivan Puluj National Technical University, Ternopil, 2021. In the dissertation, on the basis of the set of generalized scientific results, the new actual problem of increasing the technological efficiency of screw transport mechanisms operation process is solved due to design improvement and substantiation of parameters of the inertial planetary safety clutch, which is produced on the basis of the biplanetary inertial mechanism with a mobile reactive link. On the basis of the conducted theoretical and experimental research the following has been developed: analytical dependences which allow to analyse the displacement of the imbalance point and the mechanism in general; analytical dependences for determination of kinematic and dynamic parameters of the operation stop mode of the screw conveyor with inertial planetary safety clutch; empirical equations that characterize the change in braking torque of the stop mode and the torque transmission efficiency. Grounded on the conducted theoretical and experimental research, the optimal parameters of the inertial planetary safety clutch of the screw conveyor are substantiated. The braking safety torque of the output shaft of the screw conveyor inertial planetary safety clutch in the stop mode is formed by means of increasing the imbalance energy due to acceleration of the imbalance rotation around its axis and the drive axis of the pulse module as well as range variation of 19.6 … 29.4 N∙m, when respective gear ratio of the imbalance drive equals to 2.2. Rational functioning of the process of the screw conveyor operation in terms of providing maximum braking torque of the output shaft in case of overload of its working parts in the range from 20 N∙m to 42 N∙m, or the beginning of the stop mode of the screw conveyor, is achieved by the following parameters: input shaft speed is from 262.5 rpm to 437.5 rpm; the gear ratio of the upper imbalance drive is from 2.0 to 3.2 and the lower imbalance drive is equal to 1.0. The annual economic effect achieved by increasing the technological capabilities of the screw conveyor is UAH 12,209.7. The research results were implemented at PJSC "TerA" (Ternopil), LLC "Ukraine" (Ternopil region, Pidvolochysk district) and PP "Ukraine-Agro-2C" (Khmelnytsky region, Chemerivtsi district) in technological lines, respectively, for transportation and dough formation and for transportation of bulk products and goods. Theoretical and practical results of the research were implemented in the educational process of Ternopil Ivan Puluj National Technical University during teaching the subject "Drives of Machines and Machine Complexes". The constructive novelty of the technical solution is protected by a patent of Ukraine for a utility model.
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Kobal, Damjan. "The use of technology to motivate, to present and to deepen the comprehension of math." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-80412.
Full textAbstract:
The aim of the workshop is to present and discuss several ideas which relate to technology as well as to creative teaching. Educational experience, common sense and educational research have all proven how important for comprehensive understanding different cognitive
representations are. We will present and discuss several elementary mathematical ideas of which mechanical realisations mean ingenius technological inventions (for example: ‘car differential’ and ‘digital sound technology’). Technological insights can provide deep intuitive understanding of otherwise abstract mathematical concepts and therefore yield also better comprehension of mathematics. Besides that we will use and present the technology in the form of dynamic geometry programs to show, provoke and motivate rethinking and
deeper understanding of several elementary mathematical concepts.
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Chien, Huai-Ching, and 錢懷清. "A Study on Design Procedure of Gear Ratios of Freewheel-type Bicycle Transmission." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/58703694085265936915.
Full textAbstract:
博士國立交通大學
機械工程系
91
The manufacturers of bicycle transmissions in Taiwan need a design procedure of the freewheel-type bicycle transmission to develop new transmissions with plenty of gear ratios to promote their competition ability. However, these manufacturers did not make a study of the design procedure of gear ratios of a freewheel-type bicycle transmission in the past. On account of this reason, this study focuses on the ergonomic and mechanical analysis on the gear ratios and then proposes a systematic design procedure of a freewheel-type bicycle transmission. The number of gear ratios and the complexity of gear shifting increases with the number of sprockets provided by a freewheel-type bicycle transmission. The complexity may make a cyclist feel confused by when to shift gear and which gear to be shifted to. This study proposes the calculation of the shifting point and the development of the optimum shifting strategy to solve these problems. The shifting point represents the time at gear shifting. The difference between cadences before and after shifting is a cadence spread. To decrease the complexity of shifting, a cyclist may choose several gear ratios from all gear ratios provided by a freewheel-type bicycle transmission. These chosen gear ratios compose a shifting strategy. The shifting strategy whose weight sum of mean and standard deviation of cadence spreads is minimum is the optimum shifting strategy. Therefore, the ergonomic quality of a freewheel-type bicycle transmission can be defined as the weight sum of its optimum shifting strategy. On the other hand, the mechanical quality can be defined as the number of shifting path between two sprockets. The shifting time decreases while the number of shifting path increases. In this study, the weight sum of mean and standard deviation of cadence spreads in the optimum shifting strategy is defined as a cost function in the systematic design procedure. Besides, the number of shifting path between two sprockets is treated as a constraint. Meantime, the number of gears on each sprocket is regarded as a design variable. Since the design variables are integers, this procedure finds an optimum solution by genetic algorithm. Consequently, this procedure generates the freewheel-type bicycle transmission with the optimally ergonomic and mechanical qualities.
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Wei, Chein-yu, and 魏健宇. "Conical Gear Drives with Small Gear Ratio: Design, Analysis and Application." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/47622811655018440961.
Full textAbstract:
碩士國立中央大學
機械工程學系
101
Conical gear drives, composed of a spur gear and a shaped conical gear, has the potential to replace the bevel gear for the transmission with a large shaft angle, because of lower required assembly accuracy and low-cost advantage (especially manufactured by powder metallurgy). Conical gear drives have been used most in transmission with a large gear ratio. But in the case of the conical drives with a small gear ratio (smaller than 2), the effective face-width of the conical gear is not enough due to the geometrical limit of tooth pointing and undercutting. On the other hand, the bearing contact between the pinion and the conical gear is localized by selecting the tooth number of the spur gear less than that of the shaper. In such a design, edge contact ocurrs likely due to the contact point locates nearby the undercut limit. Those problems restrict the application of conical gear drives with a small gear ratio in the practice. The purpose of this paper is thus to propose a nonstandard design approach and also to analyze and to validate the assembly error, contact stress and load capacity for the mentioned conical gear drives. At first some concepts are developed for designing conical gears. The face-width of the conical gear is enlarged by using nonstandard basic rack and the location of the contact point is adjustable by using the concept of the unequal module/unequal pressure angle to design the pinion and the corresponding shaper. Under consideration of the complex relations of the design parameters between the conical gear, the pinion and the shape, design charts are constructed in this paper to obtain a larger effective face-width of the conical gear, and to adjust the location of the contact point near the middle of the face-width. For the purpose of manufacturing on CNC-milling machine, 3D solid models of the conical gearing are generated by using Inventor API program based on the mathematical equations of the tooth surface derived from relations of gear geometry. The generated 3D model are also applied to simulate the location of loaded contact points of conical gear pairs influenced by assembly errors by using interference analysis option of the CAD program. The influence analysis of assembly errors on the location of contact points is also carried out experimentally, and the results validate the feasibility of CAD simulation. The results of analysis showed that the greater the difference of the tooth number between the shaper and the pinion is, the lower the assembly sensitivity is. Moreover, the contact pattern will be much closer to the type of point contact. To confirm the load capacity of the designed conical gear drive, tooth contact stress is analyzed by using influence coefficient method. The change of contact stress during gear meshing and the distribution of contact stress of engaged teeth at the position of contact begin and conatc end, respectively, are investigated. The analysis results showed that the contact stress is concentrated at the position of contact end and contact begin. Besides, pinions with tip rounding, short linear tip relief and smooth short linear tip relief, respectively, are also considered for loaded tooth contact analysis in the paper. From the analysis results stress concentration can be found at the begin of profile modification of the pinion with tip rounding and short linear tip relief. The pinion with smooth short linear tip relief can reduce the stress concentration, but non-Hertz contact occurs still in the contact region of profile modification. Therefore, the concentrated contact stress can be improved only by applying the tip relief on the conical gear. Finally, a set of powder metallurgy conical gear pair is mounted it in a gearbox of mower for running test according to the design approach proposed in the paper. The working condition of the mower is simulated by using trimmer line to beat a POM rod. The total load cycle is 106. It is explored from the experiment results that the tooth surfaces of both gears have only slight polishing wear under such a strict load conditions. It can be thus concluded that the proposed design approach for conical gear drives with a small gear ratio can meet the requirements of application for power transmission.
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Lin, Min-Hung, and 林旻鴻. "Flank Modified Conical Gear Drives with Small Gear Ratio: Design, Analysis and Fatigue Test." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/g4d36b.
Full textAbstract:
碩士國立中央大學
機械工程學系
103
Comparing with bevel gears, conical gear drives, which are paired with a shaped conical gear and a spur gear, have some significant advantages, such as lower assembly sensitivity, low complexity in geometry of tooth surface for ease of design, and lower manufacturing cost of molded gears (e.g. powder metallurgy gears). The conical gear drives have thus a potential to replace bevel gears in the application of mass production and transmission with a large shaft angle. But the bearing contact during gear meshing is similar to spur gear pairs that the load sharing is discontinuous. This phenomenon can cause an impact on tooth pairs and concentrated contact stresses on flanks at contact begin or end and. Abrasive wear or pitting damage on tooth flanks, and even breakage of teeth could occur. In order to expand the application of conical gears, the load capacity of the gear drives must be able to calculate to fulfill the design requirements, especially for application of powder metallurgy gear pair widely used by confirm modified flanks. The aim of this thesis is to propose a parabolic profile crowning approach for conical gears based on the developed design approach for nonstandard conical gears haiving a small gear ratio [4], as to improve a smooth variation of the load sharing of the contact tooth pair. A Loaded and an unloaded tooth contact analysis approach for conical gear pairs are also proposed respectively to verify the feasibility of the proposed approach for flank modification. Finally, test gears are manufactured to measure the tooth contact patterns considering assembly errors. A fatigue test is also conducted on a close-loop test rig to validate the surface durability. The specific sliding is at first introduced in the design approach as an additional design criterion to reduce the wear on flanks. In order to to simplify the solving process for the positions of contact points, the proposed tooth contact analysis (TCA) model is developed based on the geometric characteristics of involute. The influences of the flank modification parameters on the contact positions and the transmission errors of the gear pair under different assembly errors are analyzed by using the TCA model. The results show that：(1) The shift distance of contact positions from the middle of the face-width to the heel (the toe) at the contact begin (end) is larger with increased modification amounts; (2) The unloaded contact ratio of non-modified flanks of conical gear drives under assembly errors is inversely proportional to the working pressure angle due to shifting of contact position; (3) The unloaded transmission error (UTE) performs similar to parabolic curve in the presence of assembly errors. But, the UTE will be discontinuous at contact begin if the contact position is shifted to the heel On the other hand, a loaded tooth contact analysis (LTCA) model based on influence coefficient method is also developed to confirm the load capacity of the modified conical gear drives. The tooth contact stress, the load sharing and the loaded transmission errors during gear meshing are analyzed. The results for gear drives under ideal condition show that：(1) The load sharing during gear meshing becomes continuous and no load exists at contact begin or end; (2) A concentrated contact stress on a small area occurs at the contact end due to contact with the tip edage of the pinion; (3) The loaded transmission error (LTE) is also similar to parabolic curve. The change of the amplitude value is lower with the increased load. The results for gear drives under assembly errors show that：(1) The load at contact end or begin doesn’t disappear and is higher with the increased shift distance; (2) The variation of the load sharing and the LTE become discontinuous at the position from single to double tooth pair contact, and vice versa. The TCA model is also validated by measuring the contact patterns of test gears and interference analysis in a CAD software under assembly errors. The results show that the TCA model is in good agreement with the mentioned methods. A overloaded fatigue test is conducted on a power close-loop test rig with two types of PM conical gears, each with non-modified and modified flank. The experimental results show that the pitting damage on modified flanks is far less than non-modified flanks under the same conditions. Finally, the analysis results of the measured vibration data show that the vibration amplitudes of the gear pairs with flank modification are lower than those of the gear pairs without modification. Especially the reduction of the vibration amplitudes at the 1st gear mesh frequency is affected strongly by the improvement of the load sharing of the gear drives due to flank modification.
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Chang, Iuan-Hong, and 張元鴻. "Creative Design of Vehicle Variable-gear-ratio (VGS) Steering System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/42227311726021307360.
Full textAbstract:
碩士國立臺北科技大學
自動化科技研究所
90
This thesis deals with the research and development of a new variable-gear-ratio steering system (VGS). The main purposes of the variable-gear-ratio steering system are to connect the steering wheel and the front-wheel steering mechanism and to coordinate the turning angle of the front wheels, according to the steering-wheel angle and the speed of the vehicle, in order to maintain a constant “desired yaw rate gain” at a constant speed of vehicle. However, the value of the desired yaw rate gain should be varied at different vehicle speed to give better maneuverability, stability, and mobility. The definition of the above-mentioned “desired yaw rate gain” is the ration between the yaw rate and the steering wheel angle. This research collects all kinds of vehicle variable-gear-ratio (VGS) steering systems from academic journals and patent publications to conduct a thorough classification and kinematic analysis. This research mainly studies the vehicle steering behaviors from the viewpoint of kinematics to develop a new variable-gear-ratio steering system with more ideal performances. This research wants to achieve two goals: first, keep the desired yaw rate gain constant at a constant speed; second, vary the value of the desired yaw rate gain when the vehicle speed is changed. According to the dimensions of the production vehicles and the ideal vehicle cornering properties, this research derived the ideal relationship between the front wheels and the steering wheel when cornering and accomplished the mechanism design of the new variable-gear-ratio steering system. Finally, Pro/ENGINEER software was employed to construct the solid models of the new design and to conduct dynamic simulations and interference check, in order to verify the performance of the new design.
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Liao, Fang-Yi, and 廖芳儀. "Design and Evaluation of Transmission Gear Ratio for Electric Buses." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/62101941856867712817.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
102
The purpose of this study is to develop and to evaluate a new design of selection of transmission gear ratio for electric buses by analyzing the interrelations between the parameters of transmission system and performance of pure electric vehicle. Multi-speed transmission provides vehicle with larger range of tractive effort and speed, satisfying the performance requirements and also decreasing the energy consumption. The first step is to match the transmission to the electric machine and the powertrain system to optimize the powertrain output. Then, with the matching features and bus driving behavior, a design method of geared transmission system is constructed, including gear ratio and shift schedule. Improving the efficiency of electric machine and economic performance is the main goal of this approach. Also, a bus driving cycle with road grade is proposed in this study. Finally, a program written in MATLAB is used to simulate two buses with different power systems. State of Charge (SOC) is calculated and the result shows the benefits of this new design method.
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Shindler, Jennifer. "Access to and participation in education in South Africa: a quantitative analysis." Thesis, 2006. http://hdl.handle.net/10539/1501.
Full textAbstract:
Student Number: 7507654
Masters in Education
Faculty of HumanitiesThe right of access to education has been an issue of international concern for many decades. With the transition to democracy in South Africa, marked by the first democratic election in 1994, the right of access to education has also formed a cornerstone of South Africa’s education policy. Access to nine years of basic education is guaranteed in terms of the South African Constitution. The right to further education is also entrenched in terms of the Constitution, although this is conditional on the state making this progressively available and accessible through reasonable measures. By using actual 2001 population and school enrolment data, this research study measures access to schooling by using standard international indicators of access, namely gross and net enrolment ratios, age-specific enrolment rates, and apparent and net intake rates. The study compares such data with existing estimates by other organisations and analysts. It assesses the extent to which universal or full access to basic education has been achieved and how far South Africa has gone in making further education progressively available. The study suggests that in-depth analysis of the data shows that access to education is not as widespread as other estimates have indicated. The net enrolment ratio in the basic or compulsory education phase is 89% and not 97% as estimated by the Department of Education. Some 13% of children of school-going age (or 1.55 million children) are not attending school. The study found that universal access to basic education has not been achieved. There are problems with access to further education and South African learners’ access to education is affected by provincial location. Provincial gross enrolment ratios range from 89% to 101% and net enrolment ratios range from 82% to 91%. The study recommends that further research is required to identify the barriers that are preventing full access to education. It also recommends that future progress in terms of access to education must continue to be monitored which means that good, accurate and consistent data must be made available.
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HSU, PEI-YEN, and 徐培嚴. "Difference Of Road Bike Gear Ratio On Physiological Parameters And Padelling Performance." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/72mgcf.
Full textAbstract:
碩士輔仁大學
體育學系碩士班
107
The study amied to investigate the related analyzatin of pedaling pedaling. Performance and physical parameter under light gear ratio-high cadence and heavy gear ratio-low cadence. The following points are purposes of the study: 1. To investigate the relationship between gear ratios and loads to exhaustion. 2. To investigate the relationship between gear ratios and intensities on blood oxygen rate. 3. To investigate the relationship betwwn gear ratios and heart rate parameter. In summary, light gear ratio-high cadence strategy indicated greater performance on prolonged cycling, on the other hand , it also indicates less power output which could reach the efficacy of eliminated energy expenditure. On 10%、30%、50%、70% and 90% time table, the RPE, Power, Blood pressure, Heart rate and Exhaustion time showed no difference amongst participants, with same load being ridden.
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Wu, Tsung-Well, and 吳宗蔚. "On the systematic design of planetary gear trains with high reduction ratio." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/sk3t7z.
Full textAbstract:
碩士國立虎尾科技大學
機械與機電工程研究所
96
Gear reducers are mechanical devices for transferring power to do works. Due to their characteristics of lower output speed and higher output torque than input shaft, they are often used with engines or motors and wildly used in automated production equipment, transmission systems, machine tools, electric vehicles, electric hand tools, and other needs of high-torque low-speed applications. Due to the reasons of compact size, lightweight, and multi-degrees of freedom, high load capacity, high reduction ratio, planetary gear trains are commonly used in various transmissions(Such as multi-speed gear box, automotive transmissions, and gear differentials, etc.). Due to above reasons, planetary gear trains can be used as the transmission systems with high reduction ratio for power machinery. The purpose of this paper is to propose a systematic approach for designing planetary gear trains with high reduction ratio. First, according to the train value equation and coupling theorem of planetary gear trains, we derive the reduction ratio equations for all possible coupling cases. Then, based on these reduction ratio equations, we accomplish the kinematic design of planetary gear trains with high reduction ratio and get three planetary gear trains with high reduction ratio. According to the latent power theorem, we do analyze the mechanical efficiencies of these planetary gear trains with high reduction ratio. Finally, the prototypes of planetary gear trains with high reduction ratio are produced include one machined mockup and two rapid prototypes.
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Po-ChienChen and 陳柏謙. "Speed Ratio Control Architecture Design of Planetary Gear Train Power Assist Module." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8psyqu.
Full textAbstract:
碩士國立成功大學
機械工程學系
107
This thesis aims to develop an innovative power assist module which is capable of the active speed ratio adjustment. By assembling a power-assisted motor to the second input port of the planetary gear train, the characteristic of power transmission between input port and output port can be adjusted and controlled with the actual application need. With the goal of power assistance, two kinds of speed control system schemes are investigated with the purpose of speed ratio adjustment and control; one is semi-closed loop speed control which is based on the kinematics speed relationship of planetary gear train, and the other is full-closed loop based on the feedback signal of output port speed. With the MATLAB software simulation result, we can demonstrate the different possible responses of the two schemes which are effected by loading’s disturbance or the uncertainty of system coefficients in the actual application. Also, the thesis founds a hardware scheme of the power assist module. In order to reach the application purpose of regulating the speed ratio of transmission system, a suitable regulation strategy for the second input port power-assisted motor is designed in accordance with the setting range of the speed ratio regulation, input port speed signal, and output port speed signal. Finally, the feasibility of the analysis and the proposed control method is verified.
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彭毓霖. "Effects of contact ratio and rim thickness on stress of spur gear." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/71770848283442780192.
Full text
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Foo-HongLeong and 梁賦康. "Design of Sandwiched Magnetic Coupler for Shaft Speed Amplification with Adjustable Gear Ratio." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/51874255396189050998.
Full textAbstract:
碩士國立成功大學
機械工程學系
103
「英文延伸摘要」Summary SUMMARY An innovative design of magnetic coupler for shaft speed amplification is presented in this thesis. The structure of proposed magnetic coupler for speed change is similar to an infinite-stage gearbox. In addition, the mathematical model of flux density is derived to obtain the equation of adjustable gear ratio and effect of speed amplification. At last, the setup of experiments applied on thin-film deposition process is built up to examine the capability of the proposed variable gear-ratio magnetic coupler. Keywords: Magnetic Coupler, Speed Amplification, Gear Ratio INTRODUCTION Nowadays the magnetic coupler for shaft speed change is highly used for high power input condition, such as automotive, truck, marine, aerospace, and so on. Although some are used in pumping systems, yet most of them are for speed reduction. On the other hand, the research for low power input and speed amplification problems are not addressed much. Instead, this thesis is to investigate the problem in which the innovative magnetic coupler is employed for low-speed input but high-speed output. MATERIALS AND METHODS The variable gear-ratio magnetic coupler is designed to be of co-axial mechanical structure. It is divided into three portions: namely they are outer rotor, core rotor and inner rotor. Rare-earth permanent magnets are attached on both outer rotor and inner rotor, while core rotor is inlaid by ferrite sticks. In this thesis, sintered NdFeB permanent magnet is employed and the corresponding grade is N35. As to the matter of speed amplification, the outer rotor and core rotor are treated as the low-speed inputs, while the inner rotor as the high-speed output. As to applications of magnetic coupler, there are two typical types: fixed gear-ratio case and variable gear-ratio case. For the fixed gear-ratio case, the rotation speed is altered from either the core rotor or the outer rotor to the inner rotor while the other low-speed rotor is held stationary. More generally, the two low-speed rotors are involved in the speed amplification mechanism with different speeds for the variable gear-ratio case. The maximum gear ratio is obtained as the two low-speed rotors rotate at same speeds but in opposite direction. Once the input rotors (outer rotor and core rotor) and the output rotor (inner rotor) are well defined, the most significant factor determining how the speed of output rotor is adjusted is the gear ratio. The interplay between the number of outer rotor’s permanent magnet pole pairs, the number of inner rotor’s permanent magnet pole pairs and the number of ferrite stick together determines the gear ratio. The different combinations will result in the different gear ratio. Moreover, the cogging torque can be eliminated by selecting appropriate combinations. In this thesis, the rotational speed of inner rotor is altered even though the speed of outer rotor is constant if the core rotor acts as a control rotor, which controls the output speed and direction. After analysis and computer simulations, the combination of pole pairs for the proposed magnetic coupler is designed as 4 pole pairs on the inner rotor, 23 ferrite sticks on the core rotor and 19 pole pairs on the outer rotor. In summary, three types of gear ratio can be acquired under certain conditions: (i) Gear ratio between the outer and inner rotors, as core rotor is held stationary, is 4.75. (ii) Gear ratio between the core and inner rotors, as outer rotor is held stationary, is 5.75. (iii) The maximum gear ratio between either the core rotor or the outer rotor and inner rotor is 10.5, as the core rotor and the outer rotor rotate at the same speed but in opposite direction. Under specific operation mode of three types above, the torque inertia of the each rotor can be analyzed by using Ansoft Maxwell. From the simulation analysis, it can be seen that the torque inertia of inner rotor is 5.7Nm, the outer-rotor’s torque inertia is 26.6Nm and the core-rotor’s torque inertia is 32.33Nm. Since the torque inertia of outer rotor is up to 26.6Nm, it implies a three-phase induction motor with at least 7.5kW is required to counter-balance the torque inertia of outer rotor to rotate. However, the commercial coarse pump is about 3HP for its maximum output power. Therefore, the modification on magnetic coupler to reduce the torque inertia at outer rotor is necessary. In order to reduce the torque inertia of outer rotor, a bush is inserted to the inner side of the core rotor to reduce the flux density. On the other hand, the overlapped area of permanent magnets, which are attached on the inner rotor and outer rotor, is to be modified. The smaller the overlapped area, the weaker is the magnetic attractive force. As long as these two modifications are validated, the torque inertia of outer rotor can be significantly reduced. As a result, the torque inertia at outer rotor is reduced from 26.6Nm to 1.5Nm such that the required power for the equipped induction motor to rotate the outer rotor is greatly reduced as well. RESULTS AND DISCUSSION Finally, a proposed magnetic coupler, applied for low power input and speed amplification, is verified by experiments. It is shown that the speed profile for amplification is matched with the theoretical analysis though the stall phenomenon occasionally appears. It is noticed that the smaller the overlapped area of permanent magnets between low-speed rotor (the positions of the outer rotor and the core rotor are held stationary) and high-speed rotor (the overlapped depth depends on the position of the inner rotor), the weaker the magnetic attractive force between low-speed rotor and the high-speed rotor. In other words, the stall phenomenon certainly occurs. Conclusion To sum up, a variable-gear ratio magnetic coupler for shaft speed amplification is proposed and examined by intensive experiments to verify its capability of expected gear ratio and output speed amplification. From the experiments, the proposed magnetic coupler shows its desired gear ratio matched with the theory analysis. Besides, the rotational speed of the output rotor is well amplified. These two points verify that the proposed magnetic coupler is satisfied for the function of speed amplification. However, insufficient the overlapped depth between the high-speed rotor and low-speed rotor results in the stall phenomenon, which is caused by the magnetic attractive force between the high-speed rotor and the low-speed rotor being weaker than the start-up torque inertia. In other words, the reduced overlapped depth can reduce the torque inertia of outer rotor but stall phenomenon may occur accordingly.
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Chang, Yen-Ke, and 張晏格. "Vibration Analysis of the First-order Elliptical Gears with Contact-Ratio Effect." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/50334009870628611415.
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碩士國立臺北科技大學
機電整合研究所
92
This study uses numerical simulation methods to investigate the vibration of the first-order elliptical gears along the line of action and uses the equivalent contact ratio (ECR) to describe the variation of the contact ratio. The gears in mesh assume under rectangular mesh stiffness variation. During the simulation, the ECR is varied by changing the eccentricity, number of gear teeth, and tooth addendum. The simulation results are compared with those of circular gears with the same center distance and elliptical gears without considering the ECR effect to explore the difference of dynamic behavior owing to the ECR. From the simulation results, the following can be concluded: (a) When the eccentricity is increasing, the difference of dynamic behavior between with ECR effect and without ECR effect is more visible in resonance regions. (b) The larger ECR value can be obtained by increasing the number of gear teeth, which results in better dynamic response of the elliptical gears. (c) Changing the tooth addendum varies the ECR value effectively. The elliptical gears with high contact ratio (ECR>=2.0) have better dynamic characteristics than those with low contact ratio (ECR<2.0). (d) With considering the ECR effect, more obvious variation of the amplitude in the response spectrum is obtained by setting the tooth addendum to be 1.15 times the standard value. However, no obvious difference is found between with ECR effect and without ECR effect when the tooth addendum is lower than its standard value.
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Shih-Yi, Tsai, and 蔡詩溢. "THE EFFECT OF GEAR RATIO AND REVOLUTION OF PER MOMENT ON THE BIOLOGICAL ECONOMY OF RECREATIONAL CYCLIST OF UPHILL RIDING." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/18177269816206157720.
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碩士國立臺灣體育學院
體育研究所
98
To acquire the optima gear ratio and revolution per minute in uphill riding on 8 % slope to reach the best biological efficiency, three amateur cyclists, which average age are 20.93±1.47 years with average height at 171.33±1.89 cm , weight at 71.17±3.27 kg and legs length at 79.33±0.47 cm , were recruited. The combination of three gear ratios as 1.15、1.50、2.00 and three revolution per minutes in bicycles riding on treadmill at about 4.57° slope for one kilometer were separately performed. During the experiment, the external outputting work in bicycles as well as respiratory exchange ratio, heart rates, oxygen consumption and exhaled carbon dioxide in subjects were carefully determined to calculate the gross efficiency. The data has shown that the gear ratio at 2.20 and RPM at 45rpm can reach the optima biological efficiency at 21.31±1.75. When cyclists keep at fixed speed, we obtained the greater gross efficiency (21.31±1.75) in lower RPM at 45rpm than in higher RPM at 78rpm (17.59±1.39). In summary, for amateur cyclists, riding on 8 % slope, using the gear ratio at 2.20 and RPM at 45rpm could reach the best biological efficiency.
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Silva, Gonçalo Dias Teixeira da. "Mesh stiffness and load sharing ratio along the path of contact in parallel axis involute spur gears." Master's thesis, 2021. https://hdl.handle.net/10216/136658.
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