Under a specified condition where a torque converter is kept in a lockup state to prolong the fuel-cutoff time, because of vehicle coasting with an accelerator opening APO=0, a downshift command is generated and then an automatic transmission causes a reengagement downshift by a drop in a release-side clutch hydraulic pressure Poff and a rise in an engagement-side clutch hydraulic pressure Pon. During the reengagement downshift, the engagement-side clutch hydraulic pressure Pon is reduced from a high lockup-ON hydraulic pressure to a low lockup-OFF hydraulic pressure after the time when the lockup is predicted to be released, thus preventing a torque drawing-in tendency of transmission output torque, which may occur at the time of the beginning of the inertia phase, from increasing, and also reducing in the width of a subsequent change in vehicle deceleration G, and consequently enhancing the shift quality.
Coasting downshift control device for automatic transmission
2016-05-17
Patent
Electronic Resource
English
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