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. 05, 1991
Filed:
Jan. 11, 1990
Joseph H Hunter, Carmel, IN (US);
Kenneth B Harmon, Carmel, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
In an automatic transmission, a double transition closed throttle downshift to a target range requires the release of two off-going clutches and the engagement of two on-coming clutches. The shift is made in two stages. The first stage involves a first off-going clutch and a first on-coming clutch and effects an upshift to a third range having a speed ratio lower than both the initial range and the target range, so that a momentary input speed decrease occurs. The speed decrease is managed by a closed-loop control of the first on-coming clutch until the clutch reaches a synthronous speed for the third range. The second stage is a downshift from the third ratio to the second ratio by a second off-going clutch and a second on-coming clutch and results in a speed increase. The second on-coming clutch is also managed by a closed-loop control. In each case, the closed-loop control parameter is on-coming clutch slip speed which is controlled to a calculated slip speed profile.