Hydraulic control apparatus of automatic transmission
US5954776A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1997 |
| Grant date | Sep 21, 1999 |
| Priority date | — |
| Expiry date | Aug 12, 2017 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2302/06
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A hydraulic control unit of an automatic transmission calculates deceleration during a coasting downshift, and calculates a piston play offsetting time, that is, the lag time that elapses between a shift decision and the start of the shift, on the basis of a correction value determined in accordance with the lag time learned from the previous shift. Based on the rate of deceleration and the piston play offsetting time, the downshift line in the speed shift map is corrected, that is, advanced in timing. Using this timing-advanced shift line, the control unit makes an earlier shift decision such that the shift starts in a proper state of operation, thus reducing shift shock during a coasting downshift and preventing excessive engine speed during a high-speed upshift.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.