Automatic transmission control system with holddown device
US4406181A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1980 |
| Grant date | Sep 27, 1983 |
| Priority date | — |
| Expiry date | Nov 25, 2000 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2061/026
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An automatic transmission includes a gear transmission mechanism with several friction engaging mechanisms. Selective supply of actuating pressure to these mechanisms selectively provides different speed stages from the transmission, including a directly connected speed stage and an overdrive speed stage. A driver operated manual selector valve can be set to several forward ranges including a "D" range, and produces a lower range pressure when any forward range except for "D" range is selected thereon. A kickdown pressure is produced when the accelerator pedal of the vehicle is depressed beyond a predetermined amount. An electrically operated pressure control device produces a holddown pressure signal according to operating conditions of the vehicle. A direct/overdrive shift valve controls supply of pressure to the friction mechanisms, so as to engage the overdrive speed stage, or the directly coupled speed stage, according to a balance relationship between a throttle pressure and a governor pressure, and, when override pressure is supplied to an override port of this direct/overdrive shift valve, it is prevented from providing the overdrive speed stage. A downshift pressure select…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.