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:
Feb. 24, 2004
Filed:
Jul. 25, 2002
Karl Kühner, Friedrichshafen, DE;
Manfred Sieger, Friedrichshafen, DE;
Jörg Geis, Markdorf, DE;
Andreas Schwarz, Langenargen, DE;
ZF Friedrichshafen AG, Friedrichshafen, DE;
Abstract
The invention is based on a process for determination of a coefficient of friction (&mgr;) of a hydraulically activated coupling ( ) or brake ( ) in a load-shifting transmission ( ). It is proposed that a drive shaft ( ) of the transmission ( ) be driven with a specified torque (T), that an output shaft ( ) of the transmission ( ) is blocked with a closed coupling ( ) or brake ( ) during a calibration run, the activation pressure (p) of coupling ( ) or brake ( ) is reduced in accordance with a specified course over time, the differential rotational speed (&Dgr;n) between the input ( ) and the output ( ) of the coupling ( ) or brake ( ) is recorded, the activation pressure (p) is ascertained in which the differential rotation speed (&Dgr;n) is greater than zero and a separation coefficient of friction (&mgr; ) is computed on the basis of torque (T), activation pressure (p) and a construction-conditioned coupling constant. By ascertaining the coefficient of friction &mgr;, the shifting can be conducted over the lifetime of the transmission ( ) with a constant shift quality.