Ratio valve to control unloading of modulating relief valve
US4751866A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 3, 1986 |
| Grant date | Jun 21, 1988 |
| Priority date | — |
| Expiry date | Oct 3, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49432
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
Fluid systems for controlling clutch engagement normally have modulating pressure relief valves to aid in smooth clutch engagement. It is also desired in such systems to ensure that the system pressure is reduced to a low level so that the load piston is fully reset prior to initial engagement of the newly filled clutch. In this arrangement, in order to ensure that the load piston is fully reset, a mechanism is provided which establishes a ratio between the pressure of the fluid being directed to the clutch and the pressure of the fluid acting on the load piston of the modulating pressure relief valve so that the pressurized fluid acting on the load piston during the filling of the clutch is vented to the reservoir to reset the load piston even though the pressure of the fluid available to the clutch is still at a higher pressure level. The ratio valve mechanism is located within the valve spool of the modulating pressure relief valve thus providing a simple and compact valve mechanism which reduces the total system size and further eliminates additional conduits and/or lines.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.