Kinematic Synthesis of Compound Planetary Gear Trains for Seven-Speed Automatic Transmissions
| Autor: | Mong-LongLi, 李孟龍 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Due to market competition, equipping a multi-speed automatic transmission has become a major trend in automobile design. Inevitably, the arisen problems such as increasing the number of links of planetary gear train, complex control system, and larger volume must be overcome. Therefore, efficiently and completely synthesizing feasible automatic transmission configurations from numerous planetary gear trains is an important research topic. The purpose of this study is to design seven-speed automatic transmissions with two-degree-of-freedom compound planetary gear trains, including structural synthesis, clutching sequence synthesis, and optimal design of the number of teeth on gears. In structural synthesis aspect, nine eight-link and three nine-link compound planetary gear trains are obtained to satisfy the required structural specifications. In clutching sequence synthesis aspect, the formula of each speed ratio is expressed in terms of the number of teeth on gears for each gear train, and it can be roughly indentified to be an underdrive, an overdrive, a direct drive or a reverse. Under the requirements of a single clutch-to-clutch shift and decreasing speed ratios, all feasible clutching sequences are obtained by combining the usable underdrive sequences with overdrive sequences. In teeth number synthesis aspect, the objective function is defined as the summation of absolute values of the difference between the generated and desired speed ratios for the forward speeds. The optimal number of teeth on gears are then found by using a LINGO software together with the specified geometric constraints for design variables. The results of this study show that there are no feasible solutions for any eight-link or nine-link planetary gear trains for the speed arrangement consisting of three forward underdrives, one direct drive, and three forward overdrives. As for the speed arrangement consisting of four forward underdrives, one direct drive, and two forward overdrives, there are also no feasible solutions for eight-link planetary gear trains, but seven feasible designs for seven-speed automatic transmissions are synthesized from two nine-link planetary gear trains. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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