Loop-Powered Pneumatic Control Interface Without External High Voltage

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Solution Overview

Problem

Existing process control systems using pneumatic devices face accuracy issues and high costs due to the need for external high-voltage power sources, which also complicate hazardous area certifications.

Innovation Solution

A loop-powered interface that scavenges power from a low-voltage control signal to operate an actuator, allowing accurate and cost-effective control of pneumatic process control devices without external high-voltage power, and maintains the last set point during power outages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external high-voltage power sources are employed to power motor or electromechanical actuators for set point adjustments, then the actuator can be powered reliably, but the system cost and complexity increase and hazardous area certifications are prevented

Engineering Contradiction:

Improvepower supply reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control device interfaces directly with the pneumatic controller without requiring external power sources. The system uses the existing process control signal to drive the pneumatic controller, making the system self-sufficient and eliminating the need for separate power supply infrastructure

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent removes the high-voltage power source from the system entirely. By extracting this component and replacing it with a direct signal interface, the system eliminates the complexity and certification barriers associated with high-voltage power while maintaining actuation capability through pneumatic means

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If intermediate transducers are employed to convert electrical signals to pneumatic signals, then set point changes can be transmitted to pneumatic controllers, but accuracy is reduced and cost and complexity increase

Engineering Contradiction:

Improvesignal compatibilityVSAvoidcontrol accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent merges the electrical signal interface and pneumatic control functions into a single direct interface. The control device accepts electrical signals and directly generates pneumatic output signals to move the set point input, eliminating intermediate conversion stages and their associated accuracy losses

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a direct interface device that acts as an intelligent mediator between electrical control signals and pneumatic controllers. This interface uses a signal-to-pneumatic transducer that maintains signal integrity while enabling direct communication, avoiding the accuracy degradation of traditional intermediate transducers

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If external high-voltage power sources are used for actuators, then actuators can operate reliably, but hazardous area certifications cannot be met

Engineering Contradiction:

Improveactuator operation reliabilityVSAvoidexplosion and fire hazard

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system uses the inherently safe pneumatic control environment to perform set point adjustments without introducing external electrical power into hazardous areas. The pneumatic controller and actuator interface operate entirely on pneumatic principles, making the system intrinsically safe for hazardous environments

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent converts the limitation of no external power into a benefit by using pneumatic actuation for set point changes. This approach eliminates the explosion and fire hazards associated with high-voltage electrical power while maintaining reliable actuator operation through pneumatic means

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution provides energy-efficient, accurate, and cost-effective control of pneumatic devices, reducing complexity and enhancing compliance with hazardous area certifications by eliminating the need for high-voltage power sources.

Implementation Method 1

a power input to scavenge power from a loop power control signal associated with the process control system

Methodology Applied

Scientific EffectPower scavenging:

Data Source

PatentUS11003151B2Loop-powered control of pneumatic process control devices

Publication Date: 2021.05.11 FISHER CONTROLS INT LLC

AI summary

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.