Hydraulic control system for automatic transmission
US5472389A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 2, 1994 |
| Grant date | Dec 5, 1995 |
| Priority date | — |
| Expiry date | Jun 2, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S477/906
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A hydraulic control for an automatic transmission is composed of a gear shift mechanism having first and second frictional engagement elements, a hydraulic control unit for the engagement elements, and an electronic control unit for the hydraulic control unit. The first element is engaged to achieve a first speed stage and the second element is engaged to achieve a second speed stage faster than and closest to the first speed stage. The hydraulic control unit has a first directional control valve for switching the feeding and discharge of hydraulic pressure between the first and second engagement elements, responsive to a first solenoid signal from the electronic control unit. A second directional control valve is adapted to be switched by a second solenoid signal from the electronic control unit to achieve a third speed stage yet faster than the second speed stage. The first engagement element has a discharge line connected to a drain line via the second directional control valve. The electronic control unit has a detector for determination of tie-up of either or both of the engagement elements, whereby upon detection of tie-up by the detector, the second solenoid signal is output…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.