Process for switching the gear-change of automatic transmissions of motor vehicles in dependence of the temperature of the cooling water
US4894780A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 21, 1988 |
| Grant date | Jan 16, 1990 |
| Priority date | — |
| Expiry date | Jan 21, 2008 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H59/78
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A process and apparatus for modifying the operation of a motor vehicle automatic transmission as a function of the temperature of the vehicle engine. A control system is provided whereby, until the engine temperature reaches a predetermined minimum, all of the gear selection solenoids are disabled, so that no gear of the vehicle transmission can be engaged. Following warm-up to and above the minimum temperature, and while the engine is not yet warmed up to a desired higher (e.g., "normal") temperature, the selection solenoid for the III gear is disabled. A combination inputs from (a) the transmission control for selecting the III gear on the basis of driving conditions, and (b) the temperature control disabling the III gear on the basis of temperature conditions, simultaneously serves to enable the II gear. An override circuit allows the operator to engage the transmission in any gear, should other considerations supersede the desire to protect overload of the engine at low temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.