Ultrasonic Welded Base Cap for Fuel Measurement Probe Reliability

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Solution Overview

Problem

Ultrasonic fuel measurement probes in aircraft fuel tanks face reliability issues due to extreme environmental conditions, premature failure, and manufacturing challenges associated with polysulfide potting material, leading to inconsistent readings and increased maintenance downtime.

Innovation Solution

The design replaces polysulfide potting material with an ultrasonically welded plastic cap to seal the transducer chamber, eliminating the need for a foam pad and reducing manufacturing complexities, while enhancing durability and reliability by creating a robust, weight-reduced structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polysulfide potting material is used to seal the transducer chamber, then the chamber can be sealed to protect the transducer, but the manufacturing process becomes complex and unreliable

Engineering Contradiction:
Improvesealing reliabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the chemical sealing method (polysulfide potting material) with a mechanical sealing method (ultrasonic welding of cap to base). This substitution eliminates the complexity of handling and curing potting material while providing a more reliable, consistent seal that is easier to manufacture and quality control.

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

Solution Approach 2:

The patent changes the sealing mechanism from a material-based solution (polysulfide) to a process-based solution (ultrasonic welding). This parameter change transforms the sealing approach from applying and curing a chemical compound to using controlled mechanical vibration and heat to fuse materials, improving both reliability and manufacturability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If foam pad and polysulfide potting material are used to create air space and seal, then the transducer is protected, but the structure becomes heavier and more complex

Engineering Contradiction:
Improveprotection reliabilityVSAvoidprobe weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent extracts and removes the foam pad and polysulfide potting material from the assembly, replacing them with a simpler cap-and-base structure sealed by ultrasonic welding. This extraction eliminates unnecessary weight while maintaining the protective sealing function through a more efficient design.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses composite construction with the cap and base made from separate materials optimized for their specific functions, joined through ultrasonic welding. This approach creates a lightweight yet durable structure that protects the transducer without the excess weight of traditional foam and potting material combinations.

Inventive Principle:
Principle #40Composite materials

3Reliability

If polysulfide potting material is used for sealing, then the air space is sealed, but manufacturing inconsistencies lead to premature failure

Engineering Contradiction:
Improvesealing consistencyVSAvoidmanufacturing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the inconsistent chemical sealing process with a controlled mechanical ultrasonic welding process. This substitution provides consistent, repeatable sealing results that are not subject to the variability of material mixing, application thickness, and curing conditions associated with polysulfide potting, thereby improving both reliability and manufacturing efficiency.

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

4Reliability

If traditional sealing methods are used, then the transducer chamber is enclosed, but repair and replacement frequency increases

Engineering Contradiction:
ImprovedurabilityVSAvoidmaintenance downtime
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent replaces traditional chemical sealing with ultrasonic welding, creating a stronger, more durable bond that resists degradation from fuel exposure, temperature cycling, and vibration. This mechanical bond is more reliable and easier to repair or replace than cured potting material, reducing maintenance downtime and improving overall durability.

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

This solution improves the reliability and durability of ultrasonic fuel measurement probes, reducing the need for frequent repairs and replacements, thus minimizing downtime and operational costs for aircraft.

Implementation Method 1

Ultrasonic sensing uses ultrasonic transducers to transmit ultrasonic waves and to receive those ultrasonic waves reflected by an object. The time delay between transmission and reception of the ultrasonic waves may be used to determine the distance of the object from an ultrasonic transducer.

Methodology Applied
Scientific EffectUltrasonic wave generation and reflection: Ultrasound

Implementation Method 2

The cap is ultrasonically welded to the transducer chamber edge such that the cap, along with the transducer chamber floor and the transducer chamber walls, encloses the transducer chamber to form an enclosed air space between the ultrasonic transducer and the cap.

Methodology Applied
Scientific EffectUltrasonic welding: Ultrasonic Vibration

Data Source

PatentEP3495785B1Ultrasonic fluid measurement probe with ultrasonically welded base cap
Publication Date: 2022.02.02 THE BOEING CO
  • EP3495785B1 patent drawingFigure 1
  • EP3495785B1 patent drawingFigure 2
  • EP3495785B1 patent drawingFigure 3

AI summary

An apparatus and method of measuring a level of fluid in a container and of enhancing reliability of an ultrasonic fluid measurement probe. A base comprises a transducer chamber, wherein the transducer chamber comprises a transducer chamber floor, a transducer chamber edge, and transducer chamber walls extending from the transducer chamber floor to the transducer chamber edge. An ultrasonic transducer is attached to the transducer chamber floor. A cap is welded to the transducer chamber edge such that the cap, along with the transducer chamber floor and the transducer chamber walls, encloses the transducer chamber to form an enclosed air space between the ultrasonic transducer and the cap.