Transmission ratio control system for a continuously variable transmission
US4850936A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 18, 1988 |
| Grant date | Jul 25, 1989 |
| Priority date | — |
| Expiry date | Apr 18, 2008 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H61/66263
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A continuously variable transmission has a drive pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, a driven pulley having a hydraulically shiftable disc and a hydraulic cylinder for operating the disc, and a belt engaged with both pulleys. The system has a hydraulic circuit having a pump for supplying oil to both the hydraulic cylinders and a drain passage for draining oil in the hydraulic cylinder of the drive pulley, and a transmission ratio control valve having a spool for controlling the oil supplied to the cylinder of the drive pulley and the oil drained from the cylinder to change the transmission ratio. A cam is provided for shifting the spool of the transmission ratio control valve in accordance with depression of an accelerator pedal of a vehicle, and a variable orifice is provided in the drain passage for controlling flow rate of drain oil from the cylinder of the drive pulley. The orifice is arranged to reduce the flow rate of drain oil when the magnitude of the depression of the accelerator pedal is large.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.