The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 08, 2000
Filed:
Nov. 27, 1996
Siemens Aktiengesellschaft, Munich, DE;
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.