Clutch-to-clutch coast downshifting in a motor vehicle automatic transmission
US4671139A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1986 |
| Grant date | Jun 9, 1987 |
| Priority date | — |
| Expiry date | Jan 27, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/19153
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
Clutch-to-clutch downshifts in the course of a coast mode of operation are effected by releasing the off-going clutching device at a time determined in relation to the vehicle speed and deceleration rate, and applying the on-coming clutching device a predetermined time thereafter such that the apply occurs when the engine speed is substantially equal to the transmission input speed in the downshifted speed ratio. The predetermined time defines an neutral interval during which the on-coming clutching device is filled with hydraulic fluid in preparation for engagement, and the engine speed assumes its neutral idle value. At the end of the predetermined time, the engine speed and the transmission input speed in the downshifted speed ratio are at the neutral idle value, and the on-coming clutching device is applied to complete the shift.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.