Method for determining a starting gear step

US6519522B1 · kind B1 · utility

Assignee

• ZF FRIEDRICHSHAFEN AG · DE

Inventors

• Andreas Wolf · Munich, DE
• Matthias Winkel · Weingarten, DE
• Christoph Rüchardt · Bodolz, DE
• Bertram Wengert · Markdorf, DE
• Jürgen Müller · Bayreuth, DE

Key dates

• Filing date: Feb 15, 2001
• Grant date: Feb 11, 2003
• Expiry date: Feb 15, 2021

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S477/901
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

The invention relates to a method for determining a starting gear step for a vehicle with a stepped variable speed transmission with several gear steps. It is proposed that a maximum admissible value for a slip time (12) and/or a maximum admissible value for a frictional work (14) of the starting clutch during the starting process, the same as an available engine torque (10) for starting be determined, that beginning with a highest suitable gear step (18) for starting, values for the slip time (20) and/or the frictional work (22) be calculated in advance depending on the vehicle mass (8), that the precalculated values (20, 22) be compared with the maximum admissible values (12, 14), that the calculation loop be repeated with the next smaller suitable gear step for starting when at least one of the precalculated values is greater than the maximum admissible values and that a gear step be issued as starting gear step when the precalculated values are smaller than or equal to the maximum admissible values.