| 摘要 |
PURPOSE: A duty rate correcting method is provided to improve shift quality by preventing run-up or tie-up from applying hydraulic pressure momentarily with controlling the duty rate in kick down shifting from the 4-range to the 3-range. CONSTITUTION: Shifting is controlled according to the predetermined duty in downshifting from the 4-range to the 3-range by increasing the throttle valve opening degree suddenly(S110-S120). Shifting time is estimated according to the duty rate, and kick down servo brake pressure and front clutch pressure are estimated(S130). Shifting is performed with reducing and increasing the shift duty rate constantly in decreasing and increasing kick down servo brake pressure and front clutch pressure(S150). The duty rate is controlled in decreasing and increasing kick down servo brake pressure and front clutch pressure during kick down shifting from the 4-range to the 3-range. Shift quality is improved with preventing run-up and tie-up in applying hydraulic pressure momentarily.
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