Design of parallel-connected epicyclic-type automatic transmissions with two fundamental geared entities

The purpose of this paper is to present a systematic methodology to simplify effectively the design of automatic transmissions by using the concepts of fundamental geared entity and basic gear ratios. An atlas of parallel-connected epicyclic-type automatic transmissions is first enumerated. Next, an effective procedure is developed to synthesize feasible clutching sequences for all the parallel-connected epicyclic gear mechanisms with two fundamental geared entities. Then, the numbers of teeth of gears in each epicyclic gear mechanism are determined by an analytical method. Finally, four alternatives for four-speed automatic transmissions are generated, and the corresponding rotating and band clutches are embodied to the epicyclic gear mechanism to obtain the atlas of four-speed automatic transmissions. The result of this paper shows that three four-speed automatic transmissions can be synthesized from the atlas of parallel-connected epicyclic gear mechanisms with two fundamental geared entities.