Fail safe valve actuator
US5195721A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 28, 1991 |
| Grant date | Mar 23, 1993 |
| Priority date | — |
| Expiry date | Mar 28, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T74/19749
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A fail safe valve actuator is disclosed that is powered by an electric motor. A valve stem with a helical groove is moved in one direction by a ball nut rotated by the electric motor to move a valve member to its operating position. The valve member is held in operating position by a solenoid. When power fails, a spring moves the valve stem in the other direction to move the valve member to its fail safe position. A torque limiting device protects the electric motor from the high torque created when the valve stem abruptly stops moving when the valve member reaches its operating position. A centrifugal brake absorbs a portion of the energy released when the power fails and the valve stem is moved rapidly to its fail safe position by the spring.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.