Closed-throttle downshift clutch control for an automatic transmission
US6361474B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 11, 2000 |
| Grant date | Mar 26, 2002 |
| Priority date | — |
| Expiry date | May 11, 2020 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H61/12
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
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…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.