Controller for an automatic motor vehicle transmission

US6101440A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Thomas Wagner · Kerpen, DE
• Michael Ulm · Alteglofsheim, DE
• Friedrich Graf · Eggenfelden, DE

Key dates

• Filing date: Nov 27, 1996
• Grant date: Aug 8, 2000
• Expiry date: Nov 27, 2016

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16H2061/0258
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

A control device for an automatic motor vehicle transmission has electrohydraulically actuated gearshift elements which increase the smoothness of shifting during a shifting operation, especially a shifting operation in a traction mode, by varying hydraulic pressure for actuating the gearshift elements. In a first phase of the shifting operation, in which idle travels of the gearshift elements are overcome, the pressure is rapidly made to approach a desired value through the use of a control signal (open-loop control) with a high duty cycle. In a second phase of the shifting operation, in which a transmission input moment changes from the gearshift element of an old gear over to the gearshift element of a new gear, the hydraulic pressure is built up with a high duty cycle. In a third phase of the shifting operation, in which a decrease in engine rpm required to carry out the gear change takes place, through a change in the duty cycle, the hydraulic pressure is first rapidly brought by open-loop control to a desired variable and thereafter is closed-loop controlled.