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:
Mar. 26, 2002
Filed:
May. 11, 2000
Sean E Gleason, Indianapolis, IN (US);
Jeffrey Kurt Runde, Fishers, IN (US);
Phillip F McCauley, Zionsville, IN (US);
Gregory A Hubbard, Carmel, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
An improved control for an automatic transmission closed-throttle downshift, wherein closed-throttle engine torque is used to raise the transmission input speed to the synchronous speed of the target speed ratio, and wherein the on-coming clutch is controlled in a manner to complete the shift with minimum driveline torque disturbance in spite of clutch control variability. The invention includes a primary on-coming clutch control for completing the downshift when the input speed reaches the synchronous speed, and a contingent on-coming clutch control that is initiated if shift completion is not achieved by the primary control, the contingent control being effective to re-establish input speed synchronization and thereupon engage the on-coming clutch to complete the shift. The primary clutch control involves holding the on-coming clutch in readiness for engagement while the input speed approaches the synchronous speed, and when the synchronous speed is reached, raising the on-coming pressure by a predetermined amount designed to maintain the input speed at the synchronous speed. The contingent clutch control includes a first open loop stage that progressively increases the on-coming clutch pressure to gradually re-establishing the input speed synchronization, and a second closed-loop stage that adjusts on-coming clutch pressure to conform the input speed to a defined trajectory.