Aircraft Pressure Sensor Bellows Dampening Pump Ripples

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Solution Overview

Problem

Aircraft fluid control systems face challenges in accurately measuring pressure drops across filtration systems due to pressure ripples and oscillations caused by pumps, which can lead to increased contamination and reduced system efficiency.

Innovation Solution

A pressure sensor with a bellows and piston assembly, integrated with a coil assembly, functions as a linear variable differential transformer (LVDT) to directly measure differential pressure across the filter module, minimizing noise from pressure ripples and allowing for accurate monitoring of filter blockage trends.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pressure sensor is used to measure pressure drop across the filtration system, then measurement capability is provided, but the sensor may be damaged by pressure ripples and oscillations from pumps

Engineering Contradiction:
Improvepressure drop measurementVSAvoidsensor survival in operating environment
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

A bellows component is introduced as an intermediary between the pump and the pressure sensor. The bellows absorbs pressure ripples and oscillations generated by the pump, preventing these disturbances from reaching and damaging the pressure sensor, while still allowing accurate pressure drop measurement across the filtration system

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The pressure ripples and oscillations, which are harmful to the sensor, are converted into a beneficial function by using the bellows to absorb and dampen these disturbances. The harmful pressure variations are transformed into controlled mechanical movement of the bellows, protecting the sensor while maintaining measurement accuracy

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

2Measurement precision

If traditional pressure sensing methods are used, then system complexity is reduced, but measurement accuracy is compromised due to noise from pressure ripples

Engineering Contradiction:
Improvedifferential pressure measurementVSAvoidsensor construction
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The pressure sensor is merged with a bellows component and piston assembly to create an integrated differential pressure sensing system. This combination allows the sensor to directly measure pressure drop across the filter while the bellows simultaneously absorbs pressure ripples, achieving both measurement accuracy and noise reduction in a single integrated device

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional electronic pressure sensing methods with a mechanical measurement system using a piston, bellows, and coil assembly. This mechanical approach inherently filters out high-frequency pressure ripples through the physical properties of the bellows, providing accurate measurements without complex electronic noise filtering

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

The solution provides robust and accurate measurement of pressure drops, enabling predictive maintenance and reducing the risk of contamination by detecting filter blockages, thus improving the reliability and efficiency of the fluid control system.

Implementation Method 1

The bellows is operatively connected to the piston head and the enclosure and is at least partially disposed about a portion of the first fluid line

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The pressure sensor includes an enclosure, a piston head, a piston rod, and a bellows. The coil assembly is disposed at the second end and at least partially receives the piston rod

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3385690B1Aircraft fluid control system having a pressure sensor
Publication Date: 2021.02.17 HAMILTON SUNDSTRAND CORP
  • EP3385690B1 patent drawingFigure 1

AI summary

A pressure sensor for fluid control system for an aircraft includes an enclosure, a piston assembly, and a bellows. The enclosure has a body that extends between a first end and a second end. A first fluid line extends to the first end. The piston assembly has a piston head that is movably disposed within the enclosure and a piston rod that extends from the piston head and through the second end. The bellows is disposed within the body that extends between and is operatively connected to the piston head and the first end.