Microprocessor-based control and diagnostic system for motor operated valves
US4816987A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 13, 1987 |
| Grant date | Mar 28, 1989 |
| Priority date | — |
| Expiry date | Apr 13, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/7761
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A microprocessor-based valve motor control system which provides control, predictive control and diagnostic functions for a motor operated valve. A microprocessor periodically tests the status of the motor operated valve, and turns off the valve's motor if certain predefined criteria for the valve stem position and the valve stem load are satisfied. The periodic testing by the microprocessor includes the testing of a position criterion (comparing both the current valve stem position signal and a predicted stem position with a preselected target position); and a stem load criterion (comparing both the current valve stem load and a predicted stem load with a preselected maximum desirable stem load). When the control system is being used with a gate valve for fully opening and fully closing a valve, the control logic can use either a predicted position criterion or a predicted stem load criterion to determine when to turn off the valve motor. When the control system is being used with a flow control valve, the use of a predicted position criterion minimizes overshoot problems which cause the motor to be reversed one or more times while moving to a target position. Motor overload prote…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.