Aisin Aw Co., Ltd.

Kiyoshi Akutsu

Masaaki Nishida

Hiroshi Tsutsui

Yutaka Teraoka

Kouichi Kojima

Masahiro Hayabuchi

Nobuhiro Iwai

An automatic transmission achieves a desired shift through an initial stage shift in which a first engagement element is released and a third engagement element is engaged, and a final stage shift in which a second engagement element is released and a fourth engagement element is engaged. A control apparatus sets an estimated rotation acceleration for a transmission input shaft in accordance with an input torque and an input torque rotation acceleration speed, and controls the release of the second engagement element for moving to the final stage shift according to the estimated rotation acceleration. As a result, it is possible to prevent a shifting delay and/or degradation that occurs between the initial stage and the latter stage by continuous transmission of the input rotation (engine rotation) change when moving from the initial stage to the later stage.

Shift control apparatus for automatic transmission

The invention has been made to eliminate a feeling of two-phase speed-change operations by causing a speed-change operation to proceed continuously when the speed-change operation is performed through two-phase control of engagement and release of four engagement elements. To accomplish this purpose, the invention provides a control apparatus for an automatic transmission wherein a predetermined speed-change operation is achieved through a pre-phase speed-change operation in which a first engagement element and a third engagement element are released and engaged respectively and through a post-phase speed-change operation in which a second engagement element and a fourth engagement element are released and engaged respectively. The control apparatus sets a target rotational acceleration of an input shaft of the transmission, and controls release of the second engagement element for a transition to the post-phase speed-change operation in accordance with the target rotational acceleration. Thus, the input speed during the transition from the pre-phase speed-change operation to the post-phase speed-change operation changes continuously, so that bluntness is prevented from being caused between the pre-stage and post-stage speed-change operations.

Speed-change control apparatus for automatic transmission

At the time of the 6&rarr;3 speed shift, an automatic transmission achieves a 6&rarr;4&rarr;3 speed shift by controlling the servo pressures of four engageable elements. A control apparatus controls the servo pressure of one engageable element in accordance with the servo pressures of other engageable elements. The engagement and release timings are adjusted by determining and controlling the oil pressures of the hydraulic servos, taking into consideration the 6&rarr;4 shift state (torque sharing) during a shift transitional period. Therefore, engine blow and prolongation are prevented during the 6&rarr;3 shift control.

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Anjo, Japan

Kiyoshi Akutsu