Hydraulic control apparatus for belt-and-pulley type continuously variable transmission, incorporating fail-safe protective means
US5052247A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 8, 1990 |
| Grant date | Oct 1, 1991 |
| Priority date | — |
| Expiry date | Aug 8, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S477/906
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An apparatus for controlling a vehicle continuously variable transmission, including a directional control valve having a first spool movable between a shift-down and a shift-up position, a flow control valve including a second spool movable between a flow-restricting and a non-restricting position, and a first and a second solenoid-operated valve for applying an actuating pressure to the first and second spools. The directional and flow control valves and the solenoid-operated valves are adapted such that the first and second spools are moved toward the shift-up and flow restricting positions, respectively, when the actuating pressure is not applied to the spools, or when solenoid coils of the two solenoid-operated valves are both off. The directional control valve may have a shift-down chamber for receiving a pilot pressure to move the first spool to the shift-down position when a failure of one of the solenoid coils exists while the vehicle speed is lower than a predetermined limit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.