자동변속기 변속 제어 개념 개발을 위한 회전 동역학 해석

In order to improve shift quality and fuel efficiency of passenger cars with automatic transmission(A/T), the number of gear steps has been developed to increase; and we have also developed the 8-speed A/T. Since the newly developed A/T has a different arrangement of planetary gear trains or clutches, its performances should be carefully investigated at the conceptual design stage to avoid facing structural problem after completion of the conceptual or layout design. In this study, the governing equations for torsional dynamics of A/T were derived and solved to be a solution set in matrix form. With this solution set of torsional dynamics, we proposed the useful methods for developing control logic of A/T. For example, the control strategy of 4-elements shift(a.k.a. double swap shift) was proved to form a unique way; and the minimal pressure level of the clutch which maintains engagement during shift was analyzed.