Loop-powered control of pneumatic process control devices

Patent metadata

Field	Value
Publication number	US-11003151-B2
Application number	US-201916280522-A
Country	US
Kind code	B2
Filing date	Feb 20, 2019
Priority date	Feb 20, 2019
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

Loop-powered control of pneumatic process control devices is disclosed. A disclosed example apparatus includes an interface for use with a pneumatic process control device of a process control system. The interface includes a power input to scavenge power from a loop power control signal associated with the process control system, a sensor to determine a position of a movable control input associated with the process control device, a comparator to compare the determined position of the movable control input with a desired position of the movable control input, and an actuator to cause movement of the movable control input based on the comparison of the determined position with the desired position, where the actuator is to be powered with the scavenged power.

First claim

What is claimed is:

1. An interface for use with a pneumatic process control device of a process control system, the interface comprising:
a power input to scavenge power from a loop power control signal associated with the process control system;
a sensor to determine a position of a movable control input associated with the process control device;
a comparator to compare the determined position of the movable control input with a desired position of the movable control input;
an energy storage to store energy from the loop power control signal; and
an actuator to cause movement of the movable control input based on the comparison of the determined position with the desired position, the actuator powered with the scavenged power, wherein the actuator is to prevent movement of the movable control input when the loop power control signal is not provided to the power input, the movement of the actuator to be prevented via the stored energy.

2. The interface as defined in claim 1 , further including a radiant light energy harvester to generate the loop power control signal.

3. The interface as defined in claim 1 , wherein the loop power control signal includes a 4-20 milliamps (mA) signal.

4. The interface as defined in claim 1 , further including a linkage to couple a first rotational motion of the actuator with a second rotational motion of a sensor.

5. The interface as defined in claim 4 , wherein the linkage includes an adjustable length portion to vary a relationship between the first and second rotational motions.

6. The interface as defined in claim 1 , further including an energy storage to store electrical energy scavenged from the loop power control signal.

7. The interface as defined in claim 1 , wherein the loop power control signal defines a set point of the process control device.

8. The interface as defined in claim 1 , wherein the stored energy is to maintain the movable control input in a locked position.

9. The interface as defined in claim 1 , wherein the stored energy is to move the movable control input into a locked position.

10. The interface as defined in claim 1 , wherein the movable control input can be adjusted via a manual override when the loop power control signal is not provided to the power input.

11. A method for controlling a pneumatic process control device of a process control system, the method comprising:
scavenging loop power from a loop power control signal associated with the process control system;
determining, by a sensor, a position of a movable control input associated with the process control device of the process control system;
comparing, by executing instructions with a processor, the determined position with a desired position of the movable control input;
causing an actuator to move the movable control input based on the comparison of the determined position with the desired position, the actuator powered with the scavenged power; and
preventing, via the actuator, movement of the movable control input when the loop power control signal is not provided, wherein movement of the movable control input is prevented via energy stored in an energy storage, the energy stored from the loop power control signal.

12. The method as defined in claim 11 , further including generating, by executing instructions with the processor, the loop power control signal via harvested radiant light energy.

13. The method as defined in claim 11 , wherein the determining the position of the movable control input includes determining a position of a movable portion of the actuator.

14. The method as defined in claim 11 , wherein the loop power includes a 4-20 milliamps (mA) signal.

15. The method as defined in claim 11 , wherein causing the actuator to move the movable controllable input includes controlling a motor operatively coupled to the movable control input.

16. The method as defined in claim 11 , wherein the loop power control signal defines a set point of the process control device.

17. A non-transitory machine readable medium comprising instructions, which when executed, cause a processor to at least:
cause a power input to scavenge power from a loop power control signal associated with a process control system;
determine a position of a movable control input associated with a process control device of the process control system;
compare the determined position of the movable control input with a desired position of the movable control input;
cause an actuator to move a movable control input of the process control device based on the comparison of the determined position with the desired position, the actuator powered with the scavenged power; and
cause the actuator to prevent movement of the movable control input when the loop power control signal is not provided to the power input, the movement of the movable control input to be prevented via stored energy from an energy storage, the energy stored from the loop power control signal.

18. The non-transitory machine readable medium as defined in claim 17 , wherein the loop power control signal is generated via harvested radiant light energy.

19. The non-transitory machine readable medium as defined in claim 17 , wherein the loop power control signal includes a current less than 50 milliamps (mA).

20. The non-transitory machine readable medium as defined in claim 17 , wherein the loop power control signal defines a set point of the process control device.

21. A method comprising:
coupling an interface to a pneumatic controller having a movable control input, the interface including:
a power input to scavenge power from a loop power control signal associated with a process control system,
a sensor to determine a position of the movable control input associated with a process control device of the process control system,
a comparator to compare the determined position of the movable control input with a desired position of the movable control input, and
an actuator to cause movement of the movable control input based on the comparison of the determined position with the desired position, the actuator powered with the scavenged power, the actuator to prevent movement of the movable control input when the loop power control signal is not provided to the interface, the movement of the movable control input to be prevented via stored energy from an energy storage, the energy stored from the loop power control signal; and

coupling a power interface to the interface to provide the loop power control signal to the interface.

22. The method as defined in claim 21 , further including removing a set point device from the pneumatic controller prior to coupling the interface.

Assignees

• Fisher Controls Int Llc

Inventors

• Jensen Kurtis K
• Koch Tom
• Koch Benjamin
• Nicholas Davin

Classifications

• G08C17/02

  using a radio link · CPC title

• G05B2219/25312

  Pneumatic, hydraulic modules, controlled valves · CPC title

• G05B19/042 Primary

  using digital processors (G05B19/05 takes precedence) · CPC title

• G05B19/0426

  Programming the control sequence · CPC title

• G05B2219/2609

  Process control · CPC title