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Bond Graph Analysis of Automatic Transmission Double-Transition Shift Dynamics

A new generation of torque converter automatic transmissions (ATs) include an increased number of forward gears, in order to allow for additional fuel efficiency gains and emission reduction. With the aim of providing good drivability, advanced shifts methods are introduced in such transmissions, including double-transition shifts (DTSs). Since DTSs require close coordination between multiple (typically four) clutches and also engine, it is of interest to analyze in detail the DTS dynamics in support of AT control strategy development. The paper first outlines an advanced 10-speed AT and its control-oriented full- and reduced-order bond graph and state- space models. The reduced-order bond graph model is used to analyze dynamics of a typical double-transition power-on downshift. The analysis is supported by control trajectory optimization results, which are obtained by using the previously developed shift optimization tool based on pseudospectral collocation method. The DTS response is divided into several characteristic phases, for which the DTS dynamics are analyzed separately by using a systematic and illustrative graphical approach based on the bond graph methodology.

Bond graph ; Automatic transmission ; Control ; Analysis ; Double-transition shift

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