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:
Jul. 09, 1991
Filed:
Dec. 26, 1989
Carl A Lentz, Mooresville, IN (US);
Joseph H Hunter, Carmel, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
In an automatic transmission, clutch-to-clutch powered downshifting is controlled by filling the on-coming clutch at a low pressure while ramping down the off-going clutch pressure until turbine speed is pulled up due to off-going clutch slippage, and then increasing the off-going pressure stepwise to compensate the change from static to dynamic coefficients of friction. Then the on-coming pressure is gradually ramped up and a closed-loop profile control period starts wherein the slip of the on-coming clutch is measured and controlled to a slip profile by controlling the off-going clutch pressure. When synchronization of the on-coming clutch is first detected, a closed-loop sync control period starts wherein the off-going pressure is controlled to minimize the slip and the on-coming pressure is ramped up at a steeper rate to begin clutch engagement during the sync control period.