Control method for a direct-coupling mechanism in hydraulic power transmission means of an automatic transmission for automotive vehicles

摘要

A method of controlling a direct-coupling mechanism of hydraulic power transmission device of an automatic transmission for an automotive vehicle, wherein the transmission capacity of the direct-coupling mechanism is controlled such that the valve of a predetermined parameter indicative of an amount of relative slip between input and output members of the hydraulic power transmission device which are mechanically engaged with each other by the direct-coupling mechanism lies within a predetermined reference range. The predetermined parameter value is detected and the detected value is compared with the predetermined reference range. A desired value of the predetermined reference range and a predetermined period of time are determined on the basis of the comparison result. The transmission capacity is controlled to the determined desired value for the determined predetermined period of time. The transmission capacity is maintained so long as the detected predetermined parameter value lies within the predetermined reference range. At least first and second transmission capacity increasing regions are provided which correspond to larger values of the amount of relative slip than that the predetermined reference range corresponds to, wherein the first region is closer to the predetermined reference range than the second region is. A rate of increase of the transmission capacity in the first region is set to a value smaller than that in the second region. A fine-control region is provided adjacent at least one of extreme limits of the predetermined reference range, wherein the transmission capacity is finely adjusted toward the predetermined reference range.