Hydraulic control circuits for continuously-variable-ratio transmissions
US5090951A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 13, 1991 |
| Grant date | Feb 25, 1992 |
| Priority date | — |
| Expiry date | Feb 13, 2011 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H2015/383
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A hydraulic control valve for a continuously-variable-ratio transmission (CVT), particularly one of the toroidal race rolling traction type. The transmission includes hydraulically-operated clutches (25,26) whose capacity to transmit torque varies with the operating pressure supplied to them. The transmitted ratio is related to the position of a hydraulic ram (35), which when it overshoots its normal stroke creates a pressure rise upstream of it in the circuit. This pressure rise first resists further overshoot, and then causes a reduction in the clutch operating pressure. Ram position is controlled by valves (56,57) which are located downstream of the ram, and which are themselves sensitive (via 58) to feedback from upstream circuit pressure: when that pressure rises, the valves open so as to depress the downstream circuit pressure by which the clutches are operated (via 68). A double-acting ram is shown, controlled by a circuit comprising two parallel hydraulic lines (42,54: 43,55) associated respectively with the opposite ends (36,37) of the ram, each line being controlled by a separate downstream control valve. The pressure feedback to the control valves and the operating press…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.