The feasibility of obtaining improved fuel efficiency by incorporating a hydrostatic transmission was investigated. The proposed transmission was composed of positive-displacement axial-piston hydraulic devices. The displacement of the pump and motor units could be varied to allow the prime mover to operate within its most efficient range. A dynamic model representing a Ford Pinto was developed using bond graphs and the IBM CSMP language to simulate the performance of the proposed design. The required input to this program consists of three independent, or control variables. These are the pump and motor swashplate angles and the engine throttle angle. In present form, the output of this program includes instantaneous values of vehicle velocity, pump and motor efficiencies, engine bsfc, and fuel economy. Observations from the simulations indicate that the test vehicle is capable of exceeding the EPA highway fuel economy estimates for the 1978 production Pinto by 11%. This increase in economy is a result of operating the engine near the minimum bsfc. Although comparisons were not made in this study, it is believed that even higher increases in economy may be realized in urban-type periods of operation. / Master of Science

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This work presents a novel methodology for evaluation of in service loads applied to the output shafts of automatic transmissions. It also presents a novel methodology of data reduction for shaft load signals as an alternative to the cycle counting methods. Current durability testing of automatic transmission output shafts uses 50 000 stall torque cycles from zero to wide open throttle. In the majority of cases, these requirements lead to an over design that can result in an unnecessarily bulky transmission system. As a solution to this problem a novel methodology for evaluation of loads applied to the output shafts of automatic transmissions was developed. The methodology is based on real world loading conditions and therefore leads to a more realistic estimation of the fatigue life of shafts. The methodology can be used as a tool for shaft optimisation in different drive conditions. Using the developed methodology the effects of different road conditions on the fatigue life of a transmission output shaft were compared. Four routes having differing driving conditions were investigated and of those routes, the route with most stop-start events resulted in the greatest reduction in fatigue life. A novel methodology of data reduction for shaft load signals was also developed. The methodology is based on knowledge of the bandwidth and dynamic range of the expected in-service load signal. This novel methodology allows significant reduction of the volume of data to be acquired. It preserves the time sequence of peaks and valleys of the signal, which is vital in the case of fatigue analysis. This is in contrast to current methods based on cycle counting. Cycle counting methods achieve high data reduction but do not preserve the time sequence of the signal. The developed novel methodology has been validated on the newly developed data acquisition system capable of real time data acquisition and compression of shaft torque signal. The performed tests show that the proposed one-channel low cost system equipped with 1 GB compact flash card can store well over 10 000 hrs of load history.

Orientador: Robson Pederiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-14T00:38:10Z (GMT). No. of bitstreams: 1 Garcia_Ubirajara_M.pdf: 2857015 bytes, checksum: 43af4c00365bf303c80b6b5d1be9e9be (MD5) Previous issue date: 2009 / Resumo: Neste trabalho desenvolve-se um método, que permite avaliações de parâmetros, para o estudo do projeto de um sistema auto-tensionador no controle de suas vibrações transversais e forças atuantes. Parâmetros construtivos e operacionais, como: a geometria, inércia, rigidez da mola do auto-tensionador, rigidez da correia e condições de operação, como: frequências de excitação, forças estáticas e dinâmicas são obtidas em um sistema auto-tensionador de transmissão por correias, aplicados em automóveis de passeio comerciais. Com a modelagem dinâmica de um grau de liberdade, calcula-se a força de atrito e fator de amortecimento, que estabelece o controle de vibrações e forças atuantes no sistema. Os resultados das simulações computacionais são analisados e comparados com os resultados obtidos pelo protótipo experimental desenvolvido. Os resultados tecno-experimentais indicam ajuste satisfatório, o que representa uma contribuição significativa, para o estudo de sistemas auto-tensionadores e na melhoria do controle de vibrações e forças atuantes em correias dentadas, em tempo real de projeto. / Abstract: This investigation describes a method, which permits evaluating the best parameters, in the study of tensioner project system in its transversal vibration control and actuating forces. The construtive and operating parameters, as: geometry, inertia, tensioner spring stiffness, belt stiffness, and operating conditions as: excitation frequencies, estatic and dinamic forces are obtained in a tensioner of transmition by belts with market vehicles aplication. With a dinamical modelling of one degree of fredow are calculated the atrict force and damping factor that establish the vibration control and system actuating forces. The computational simulating results are analysed and compared with obtained results from the developed experimental prototype. The tecno-experimental results have a satisfactory adjust, that represents a significative contribution, for tensioners systems study and the better control of vibrations and actuating forces on driven belts, in project real time. / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

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