Hydraulic control for a six-speed automatic transmission
US6464609B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 2001 |
| Grant date | Oct 15, 2002 |
| Priority date | — |
| Expiry date | Apr 16, 2021 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2200/2007
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An electro-hydraulic control for a six speed power transmission has three shift control valves that are each actuated by a spring and a solenoid valve. The shift valves are positioned in either a spring set or a pressure set position to establish flow paths to five torque transmitting mechanisms (friction devices) that are engaged according to a predetermined schedule to establish six forward speed ratios and one reverse ratio. A pair of high ratio control valves and a pair of low ratio control valves operate to control the actuation pressures for the friction devices. The actuation pressures are distributed through a switching valve. The high ratio control valves control the on coming friction device with an increasing pressure schedule while the low ratio control valves control the off going friction device with a decreasing pressure schedule. A bias port on each of the low ratio valves is responsive to the pressure output of the high ratio control valve to discontinue operation of the low ratio control valve when the on coming friction device has sufficient capacity to transmit the torque. During downshifting, a down shift valve is operable to prevent the pressure of the high ra…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.