Patent ID: 6732037
Filing Date: 2004-05-04
Classification: F16H

Abstract:
A method for determining, using a piston stroke ratio of a piston, a fill time for a friction element in an automatic transmission that is either engaged or disengaged during shifting between an N-range, a D-range, and an R-range, the friction element being actuated by the piston, the method comprising:neutral compensating for the piston stroke ratio of said piston, wherein said neutral compensating comprises detecting an N-range hold time and compensating for the piston stroke ratio using the detected N-range hold time and a pre-installed map when a N to D/R shift signal is detected to determine a neutral compensated piston ratio; drive compensating for the piston stroke ratio of said piston, wherein said drive compensating comprises detecting a D/R-range hold time and compensating for the piston stroke ratio using the detected D/R-range hold time and the pre-installed map when a D/R to N shift signal is detected, the D/R-range to hold time being a time during which the shift range is held at said one of the D- and R-ranges, to determine a drive compensated piston ratio; and calculating a fill time using the compensated piston stroke ratio; said neutral compensating further comprising, detecting the N to D/R shift signal, initializing, in the case where the N to D/R shift signal is detected, a timing device after the N-range hold time is detected calculating a change in an N to D/R piston stroke ratio from the pre-installed map using the N-range hold time; and compensating the piston stroke ratio based on the change in the N to D/R piston stroke ratio.