Control system for controlling transmission fluid pressure
US4779489A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 9, 1987 |
| Grant date | Oct 25, 1988 |
| Priority date | — |
| Expiry date | Mar 9, 2007 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2061/0255
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
When a pulse width modulated electrical signal is employed to operate an electro-mechanical device, such as a solenoid valve, in a transmission to produce a controlled fluid pressure whose level is proportional to the signal's duty cycle, proper operation at cold temperatures is ensured by varying the frequency of the pulse width modulated signal directly with the temperature of the transmission fluid. By decreasing the operating frequency when the transmission fluid is cold (at which time the fluid may thicken and become heavy since its viscosity will increase), the solenoid valve will be actuated slowly enough to effect flow control through the valve and adequate regulation of the fluid pressure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.