Fluid Regulator Actuator Stability via Nested Control Springs

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Solution Overview

Problem

Existing gas distribution system regulators face stability limitations due to single control spring arrangements, leading to undesirable valve flutter at certain resonant frequencies, which affects the maintenance of preselected gas pressures in end-user facilities.

Innovation Solution

The use of two control springs with different natural frequencies, arranged in parallel and nested within each other, to independently bias the diaphragm against fluid pressure, providing enhanced stability and reducing resonant instability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single control spring is used to bias the diaphragm, then the device complexity is reduced and assembly is simplified, but the regulator exhibits instability and valve flutter at certain resonant frequencies

Engineering Contradiction:
Improveactuator structureVSAvoidregulator stability
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The single control spring is segmented into multiple control springs (at least two) with different natural frequencies. Each spring is operatively connected to the diaphragm to bias it against fluid pressure. This segmentation eliminates resonant instability and valve flutter while maintaining acceptable device complexity through the use of nested spring arrangements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control springs are arranged in a nested configuration where smaller diameter springs are positioned inside larger diameter springs. This nesting approach allows multiple springs to occupy a compact space, reducing the overall volume of the actuator while providing the stability benefits of multiple springs with different natural frequencies.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Stability of the object's composition

If multiple control springs with different natural frequencies are used, then regulator stability is improved and valve flutter is reduced, but the device complexity and assembly difficulty increase

Engineering Contradiction:
Improveregulator stabilityVSAvoidactuator structure
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The control springs are arranged in a nested configuration where smaller diameter springs are positioned inside larger diameter springs. This nesting approach allows multiple springs to occupy a compact space, reducing the overall volume of the actuator while providing the stability benefits of multiple springs with different natural frequencies.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

Multiple control springs with different natural frequencies are combined in parallel to work together in biasing the diaphragm. This combination achieves the stability benefits of multiple frequencies while using a compact nested arrangement that minimizes the increase in device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Force

If multiple control springs are arranged in parallel, then a higher spring rate is achieved in a compact design, but the volume occupied by the springs increases

Engineering Contradiction:
Improvespring rateVSAvoidactuator volume
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The control springs are arranged in a nested configuration where smaller diameter springs are positioned inside larger diameter springs. This nesting approach allows multiple springs to occupy a compact space, reducing the overall volume of the actuator while providing the stability benefits of multiple springs with different natural frequencies.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 configuration reduces regulator instability and valve flutter, allowing for precise control of gas pressure within a preselected range while enabling a higher spring rate in a compact design.

Implementation Method 1

The actuator includes a plurality of control springs operatively connected to the diaphragm and arranged to independently bias the diaphragm against the fluid pressure

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Movement of the diaphragm 28 in response to pressure changes at the outlet 22 causes the linkage to shift the control element 14

Methodology Applied
Scientific EffectPressure: Pressure Increase

Data Source

PatentEP2898244B1Fluid regulator and method of improving stability of a fluid regulator
Publication Date: 2018.12.05 EMERSON PROCESS MANAGEMENT REGULATOR TECHNOLOGIES INC
  • EP2898244B1 patent drawingFigure 1
  • EP2898244B1 patent drawingFigure 2
  • EP2898244B1 patent drawingFigure 3

AI summary

An actuator (16) for a fluid regulator includes two or more control springs (46,48) operatively connected to a diaphragm (50) such that at least two of the control springs (46,48) bias the diaphragm (50) independently in parallel and have different natural frequencies. A method for retrofitting a prior art actuator to include a second control spring is also disclosed.