Fail safe automatic transmission lock up clutch control system
US4428259A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1981 |
| Grant date | Jan 31, 1984 |
| Priority date | — |
| Expiry date | Jul 28, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S477/906
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An automatic transmission includes a gear transmission mechanism with first and second friction mechanisms which are alternatively engaged by alternative supply of first and second actuating pressures thereto when the highest speed stage and the next to highest speed stage are alternatively engaged, and a torque converter including a lockup clutch. A transmission control system includes a pressure control system which controls the gear transmission mechanism by selectively supplying those actuating pressures and possibly others, and a lockup clutch control valve which controls the engagement of the lockup clutch. The lockup clutch control valve is switched to its disengage position when it receives neither a first nor a second control pressure, and is switched to an opposite position by supply of either the first or second control pressure, this opposite position being an engage position for the lockup clutch if governor pressure is over a first specified value. The first control pressure is provided when governor pressure is higher than a second specified value higher than the first specified value and also the first actuating pressure is present; and the second control pressure i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.