Double-downshift gear strategy for a dual clutch automatic transmission

• Main Authors: LEISING MAURICE B, DOURRA HUSSEIN A
• Format: Patent
• Language: English
• Published: 11.11.2004
• Edition: 7
• Subjects: BLASTING; CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE ORDIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ENGINEERING ELEMENTS AND UNITS; GEARING; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; HEATING; LIGHTING; MECHANICAL ENGINEERING; PERFORMING OPERATIONS; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TOTHE CONTROL OF A PARTICULAR SUB-UNIT; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; THERMAL INSULATION IN GENERAL; TRANSPORTING; VEHICLES IN GENERAL; WEAPONS

A method of double-downshifting from a first gear ratio to a second gear ratio includes the steps of first reducing torque transfer from a first clutch to a first driven gear. Engine speed then increases. Next, torque transfer from a second clutch to a third driven gear is increased while simultaneously the first clutch is disengaged from the first driven gear. Torque transfer from the second clutch to the third driven gear is then reduced. Torque transfer from the second clutch to the third driven gear is next increased. The first clutch is engaged to the second driven gear. Then, torque transfer from the first clutch to the second driven gear is increased while simultaneously the torque transfer from the second clutch to the third driven gear is reduced. Finally, the second clutch is disengaged from the third driven gear.