An infinitely variable transmission (IVT) is a transmission that can smoothly and continuously vary the speed ratio between an input and output from zero to some other positive or negative ratio; they are a subset of continuously variable transmissions (CVTs), which themselves do not have the ability to produce a zero gear ratio. In this thesis, the operation, analysis, and development of a novel, highly configurable, Cam-based Infinitely Variable Transmission of the ratcheting drive type is presented. There are several categories of CVTs in existence today, including traction, belt, and ratcheting types. Drives of these types, their attributes, and associated design challenges are discussed to frame the development of the Cam-based IVT. The operation of this transmission is kinematically similar to a planetary gearset, and therefore, its operation is described with that in mind including a description of the six major components of the transmission, those being the cam, followers, carriers, planet gears, sun gears, and one way clutches. The kinematic equation describing its motion is derived based on the similarities it shares with a planetary gearset. Additionally, the equations for the cam design are developed here as the operation of the CVT is highly dependent on the shape of the cam. There are six simple inversions of this device and each inversion has special characteristics and limitations, for example, the available gear range. A method was developed to select the most suitable inversion, gearing, and follower velocity for a given application. The contact stress between the rollers and cam is the limiting stress within the transmission. A parametric study is used to quantify the relationship between this stress and the transmission parameters. Based off those results, two optimization strategies and their results are discussed. The first is an iterative brute force type numerical search and the second is a genetic algorithm. The optimization results are shown to be similar and successfully reduced the contact stress by 40%. To further improve the transmission performance, several mechanisms were developed for this unique transmission. These include a compact and lightweight differential mechanism based on a cord and pulley system to reduce the contact force on the rollers. In addition, a unique external/inverted cam topology was developed to improve the contact geometry between the rollers and said cam. A prototype was built based on both the optimization strategies and these mechanisms and is described within. Finally, a Prony brake dynamometer with cradled motor was constructed to test the transmission; the results of those tests show the Cam-based IVT to be 93% efficient at low input torque levels. / Master of Science

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Governments across the world are implementing legislation for ever more strict limits for vehicle emissions; combined with customer expectations for growing levels of performance and equipment, automotive manufacturers face a significant challenge. With the aim of meeting this challenge, downsizing is an established trend in passenger car engine development. However, since downsizing is commonly achieved through pressure charging (turbocharging, for example), the associated benefits in improved fuel economy and emissions are often obtained at the expense of engine dynamic response, and, consequently, vehicle driveability. This thesis presents predominantly simulation-based research into a novel combined charging system comprising a conventional turbocharger used in conjunction with a declutchable supercharger driven through a CVT. An initial investigation using this system in place of a variable geometry turbocharger on an already downsized passenger car diesel engine demonstrated greatly increased low speed torque as well as improved dynamic response. A downsizing project that involved replacing a naturally aspirated gasoline engine with a highly boosted engine with 40% of the original displacement formed the basis for more extensive investigations. Although it was unable to produce the low speed transient response of the naturally aspirated engine, in tip-in tests the CVT-supercharger system was shown to achieve the target torque much quicker than an equivalent system with a fixed supercharger drive ratio. However, balancing this with good fuel efficiency for the initial part load period was a complex trade-off. In vehicle acceleration simulations the CVT-supercharger system did not outperform the fixed drive ratio configuration, but on the CVT system the boost limit was reached at an early stage during the transients. Thus there may be potential to include an ‘over-boost’ facility, allowing boost pressure to temporarily exceed normal steady state limits in order to improve transient performance and bring it closer to that of the baseline vehicle. It is suggested that the CVT-supercharger provides the best flexibility for calibration and compromise between performance and fuel efficiency, perhaps incorporating different user-selectable modes (such as ‘economy’ and ‘sport’ modes).

Darbe nagrinėjami elektros varikliais valdomi planetiniai reduktoriai - variatoriai. Atliktos mokslinių straipsnių analizės metu susipažinta su įvairių rūšių automobiliuose naudojamomis transmisijomis: pateikta jų klasifikacija, apžvelgtos dažniausiai naudojamos transporte pavarų dėžės. Pateikta tyrimo metodika, apžvelgti eksperimentinių tyrimų įrenginiai ir priemonės. Atlikti elektros varikliu valdomo planetinio reduktoriaus eksperimentai su suprojektuotu tyrimo stendu. Palygintos belaipsnės pavarų dėžės su parinktu dyzeliniu varikliu, bei pateiktos išvados ir rekomendacijos. / This thesis analyzes the electric motor which controlled by planetary gearboxes - variator. Accomplished scientific articles during the analysis been familiarized with different kinds of transmissions which used in vehicles: submitted their classification, reviewed most commonly gearbox which used in transport. Submitted research methods, an overview of experimental research equipment and facilities. Performed experiments of electric motor controlled by planetary gear with designed study stand. Were was compared continuous variable transmission with a selected on diesel engine, submitted conclusions and recommendations.

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No description available.

Orientador: Júlio Carlos Teixeira / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia

With energy demands at an all time high, mechanical power systems are under great scrutiny. Substantial efforts are being made throughout the world to reduce energy use in common mechanical systems such as the internal combustion engine and transmission system. Eliminating or reducing efficiency losses in the transmission is a potential source of improving the efficiency of the system. To do so, various alternative types of transmissions are being investigated. At Brigham Young University, development of a Positively Engaged Continuously Variable Transmission (PECVT) is progressing. In addition to the efficiency increases that would occur as a result of operating the engine at a more constant speed, a PECVT type transmission may reduce efficiency losses that occur in a standard transmission by eliminating the disengagement of involute gear sets to change gear ratios of the transmission. For a PECVT, this is done by maintaining engagement of the input and output members of the transmission, while changing the gear ratio. Both of these types of losses are major contributing factors to the overall efficiency of the transmission and engine system, thus a PECVT is of great interest. The investigation for developing a feasible PECVT began with the identification of a behavioral issue identified in all known PECVT embodiments. This behavioral issue, known as the Non-Integer-Tooth-Problem (NITP), is due to the geometry of an involute gear and prevents specific gear ratios from being achieved. The research effort presented in this thesis returns to the conceptual design of a PECVT to address involutometry along with the NITP. A design tool entitled the Line-of-Action Model is developed which assists in quantifying how a conceptual solution can address the NITP using involutometry principles. As a result of the Line-of-Action Model, the Hybrid Involute Profile was discovered. Due to the simplicity of The Hybrid Involute Profile, it has proven to be an elegant solution to the NITP. Validation of the Hybrid Involute Profile concept was conducted to ensure that this concept satisfies the objectives and requirements of a PECVT and solves the NITP. The validation was completed using two case studies and a theoretical analysis. As a result of the validation, the Hybrid Involute Profile is declared a conceptual principal solution to the NITP. Fulfillment of the PECVT objectives, requirements list and elimination of the NITP by the Hybrid Involute Profile is also demonstrated. With the Hybrid Involute Profile as the conceptual principle solution, the development of a commercially viable PECVT is believed to be attainable.

Providing access to telecommunication services in rural areas is of paramount importance for the development of any country. Since the cost is the main inhibiting factor, any technical solution for access in sparsely populated rural areas has to be reliable, efficient, and deployable at low-cost. This thesis studies the utilization of Multihop Wireless Networks (MWN) as an appealing alternative for rural communication. MWN are designed with a self-configuring capability and can adapt to the addition or removal of network radio units (nodes). This makes them simple to install, allowing unskilled users to set up the network quickly. To increase the performance and cost-efficiency, this thesis focuses on the use of Advanced Antenna Systems (AAS) in rural access networks. AAS promise to increase the overall capacity in MWN, improving the link quality while suppressing or reducing the multiple access interference. To effectively exploit the capabilities of AAS, a proper design of Medium Access Control (MAC) protocols is needed. Hence, the results of system level studies into MAC protocols and AAS are presented in this thesis. Two different MAC protocols are examined: Spatial Time Division Multiple Access (STDMA) and Carrier Sense Multiple Access Collision Avoidance (CSMA/CA) with handshaking. The effects of utilizing advanced antennas on the end-to-end network throughput and packet delay are analyzed with routing, power control and adaptive transmission data rate control separately and in combination. Many of the STDMA-related research questions addressed in this thesis are posed as nonlinear optimization problems that are solved by the technique called "column generation" to create the transmission schedule using AAS. However, as finding the optimal solution is computationally expensive, we also introduce low-complexity algorithms that, while simpler, yield reasonable results close to the optimal solution. Although STDMA has been found to be very efficient and fair, one potential drawback is that it may adapt slower than a distributed approach like CSMA/CA to network changes produced e.g. by traffic variations and time-variant channel conditions. In CSMA/CA, nodes make their own decisions based on partial network information and the handshaking procedure allows the use of AAS at the transmitter and the receiver. How to effectively use AAS in CSMA/CA with handshaking is addressed in this thesis. Different beam selection policies using switched beam antenna systems are investigated. Finally, we demonstrate how the proposed techniques can be applied in a rural access scenario in Nicaragua. The result of a user-deployed MWN for Internet access shows that the supported aggregated end-to-end rate is higher than an Asymmetric Digital Subscriber Line (ADSL) connection. / QC 20100908

Electric and hybrid vehicles are particularly suited for use in urban areas since city transportation is mainly characterized by relatively short driving distances, low continuous power requirements, long idling times and high availability of regenerative braking energy. These characteristics, when carefully incorporated into the design process, create valuable opportunities for developing clean, efficient and cost effective urban vehicle propulsion systems. In the first part of the thesis, we present data collected in the city of Bangalore, India from a very commonly seen mode of transportation for hire in India and other emerging economies, namely a three-wheeled vehicle known as the “auto-rickshaw”. From a statistical analysis, it is shown that the typical range is 72.5 km with a mean speed of 12.5 km/h. More than 60% of the time the auto-rickshaw is stationary or has a speed of less than 5 km/h. From a model of the auto-rickshaw, it is shown from simulations that 4 kW DC motor and about 10 kWh of electrical energy is enough to meet 80% of typical requirement. Based on this finding, in this thesis, a novel parallel hybrid architecture is proposed where two 2 kW DC hub motors are directly mounted on the wheels and an internal combustion (IC) engine output is connected to the stator of the DC hub motors to provide additional power when required. To match load and speed, a continuously variable transmission (CVT) is placed in-between the IC engine and the DC hub motor. The proposed hybrid configuration adds speed to the wheel output unlike the normal power split configuration which adds torque. One of the main objective of this work is to study and compare the performance of the above novel speed-addition and compare with the typical torque-addition configuration. A MATLAB/Simulink model for both the configurations, with DC hub motor and a small IC engine, has been created and the fuel consumption has been calculated. It is shown that the proposed speed-addition concept gives better fuel efficiency for the standard modified Indian Driving Cycle. The models have also been compared for actual driving data and an optimal control strategy has been developed using dynamic programming. It is again shown that the proposed speed-addition concept results in better fuel economy. In the last part of the thesis, a low cost experimental test-bed consisting of an auto-rickshaw IC engine, a CVT and a 2 kW DC hub motor has been developed to validate the speed-addition concept and compare with the torque-addition configuration. The torque-speed curves of the IC engine, the DC motor and both of them together, in the speed and torque-addition configuration, have been obtained. It is shown that the speed-addition concept does indeed work and the obtained results are significantly different from the torque-addition configuration.