Patent ID: 6519522
Filing Date: 2003-02-11
Classification: B60W,B60Y,F16H,Y10S,Y10T

Abstract:
A method for determining a starting gear step for a vehicle having a stepped variable speed transmission with several gear steps, the method comprising the steps of:connecting the stepped variable speed transmission on an input side by an engageable starting clutch with a prime mover that produces an engine torque; connecting the stepped variable speed transmission on an output side with input wheels of the vehicle which transmit a traction force; determining the starting gear step by an electronic control device at least in accordance with a vehicle mass (8) and one other parameter (6) dependent on a driving mode which comprises an uphill gradient resistance of the vehicle, and (a) determining a maximum value admissible for at least one of a slip time (12) and a maximum value admissible for frictional work (14) of the starting clutch during a starting process, the same as an engine torque (10) available for starting; (b) beginning with a highest gear step (18) suitable for starting, values for at least one of at precalculated slip time (20) and precalculated frictional work (22) are determined in a calculation loop according to a ratio of the gear step (19), to the vehicle mass (8), to the other parameter (6) dependent on the driving mode and to the engine torque (10) available for starting; (c) comparing the values for at least one of the precalculated slip time (20) and the precalculated frictional work (22) with at least one of the respective maximum value admissible for at least one of the slip time (12) and the maximum value admissible for frictional work (14); (d) repeating the calculation loop with a next smaller gear step suitable for starting when at least one of the precalculated values is higher than the maximum admissible values; and (e) issuing a gear step as the starting gear step when the precalculated values are smaller than or equal to the maximum admissible values.