Solenoid-operated pressure control valve
US5579807A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 14, 1994 |
| Grant date | Dec 3, 1996 |
| Priority date | — |
| Expiry date | Sep 14, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/86622
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A hydraulic pressure control valve uses a stepped valve spool having a differential area exposed to supply pressure to provide a small resultant force on the spool. A linear electric solenoid provides a linearly variable force on the valve spool to variably position the spool. In a basic embodiment, the linear solenoid force opposes the resultant supply pressure force to position the spool and control hydraulic outlet pressure. Other embodiments are employed to control brake pressure in a transit car. In a second embodiment, the resultant hydraulic pressure force is opposed by the linear solenoid force to position the spool during normal service braking. Brake pressure is proportioned to car weight by varying current to the linear solenoid. When the transit car emergency brake pipe is dumped, load weigh air pressure and spring forces position the spool in an emergency brake pressure position proportional to car weight. These forces are normally neutralized by emergency brake pipe pressure during service braking. In a third embodiment, the selectively variable linear solenoid force supplements the resultant pressure force to position the valve spool against the force of a spring and…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.