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
17.05.2016
Patent
Elektronische Ressource
Englisch
Method of controlling automatic transmission coasting downshift
Europäisches Patentamt | 2015
|Transmission coasting downshift change intention control method
Europäisches Patentamt | 2022
|