US 5,683,328 AGranted

Shift control system of automatic transmission

AssigneeAisin Aw Co., Ltd.

InventorsFrank de Schepper, Kenji Suzuki

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Abstract

A shift control system for an automatic is designed to prevent engine racing and clutch tie-up during a clutch-to-clutch shift (clutch switching shift) involving engagement/disengagement of first and second frictional engagement elements. The shift control system includes an engagement force controller for independently controlling both of the frictional engagement elements. A gear ratio calculator continuously calculates a gear ratio r of the transmission and a shift characteristic value calculator calculates a shift characteristic value .alpha. based on changes in the gear ratio between the start of the shift and completion of the shift. A control value calculator calculates a control value .beta., based on the shift characteristic value .alpha. calculated by the shift characteristic value calculator and a shift characteristic value .alpha.I on an ideal gear ratio curve. The control value .beta. is calculated so that the shift characteristic value .alpha. coincides with the shift characteristic value .alpha.I on the ideal gear ratio curve.

Claims8

Dependent claims

A shift control system for an automatic transmission having a plurality of frictional engagement elements for performing shifts from one gear ratio to a second gear ratio by disengagement of a first of said frictional engagement elements and engagement of a second of said frictional engagement elements, said control system comprising:

a plurality of hydraulic servos for engaging and disengaging said plurality of frictional engaging elements;
engaging force control means for controlling supply and draining of hydraulic pressure to and from said plurality of hydraulic servos independently;
gear ratio calculating means for calculating the gear ratio of said transmission;
shift characteristic value calculating means for calculating an actual shift characteristic value based on changes of the gear ratio during the shift;
and
control value generating means for calculating a control value based on (1) the actual shift characteristic value calculated by said shift characteristic value calculating means and (2) an ideal a shift characteristic value which corresponds to an ideal gear ratio curve for the shift;
said engaging force control means controlling the supply and draining of hydraulic pressure to and from said hydraulic servos operating said first and second frictional engagement elements, in accordance with said control value.

4 more elements

Dependencies are inferred from the claim text.