| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 93 === The purpose of this study is to synthesize and sketch automatically planetary gear trains (PGTs) for automatic transmissions. A new structural matrix is proposed to represent the structure of PGTs. Based on the definition of this matrix, a specific algorithm is proposed and computerized to synthesize PGTs without detecting isomorphism. The matrices for those PGTs with up to 10 links and two or three degrees-of-freedom are obtained. By setting the proper configurations and the corresponding position parameters for all links in advance, these matrices are then automatically transformed to kinematic sketches without links crossing. According to the number of coaxial links, the amount of operations for the required speeds can be calculated. Besides the operation number, the relation between inverse operations is also taken into consideration for clutch-to-clutch shift. Both rules are applied to select PGTs with two degrees-of-freedom for feasible seven-speed automatic transmissions. In the case of PGTs with three degrees-of-freedom, the number of distinct gear ratios is determined exactly by using the concept of kinemaitc equivalence. The number of distinct gear ratios dominates how many speeds one PGT owns. It concludes that PGTs with three degrees-of-freedom and having at least six coaxial links have enough distinct gear ratios to be seven-speed automatic transmissions.
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