Multiwall Bearing Oil Tube Fitting for Fluid Isolation

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Solution Overview

Problem

Gas turbine engines face challenges in maintaining separation of fluids within double wall tubes, leading to issues like oil coking and blockages due to excessive heating, which affects lubricant delivery to bearing systems.

Innovation Solution

A multiwall tubing assembly with concentric fluid paths and a fitting configuration that maintains fluid isolation between the inner and outer fluid passages, using a seal to prevent mixing and minimize heat transfer, ensuring effective lubricant delivery to bearing systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If double wall tubes are used for fluid transport, then fluid delivery capability is improved, but fluid separation maintenance becomes difficult leading to mixing at exit

Engineering Contradiction:
Improvefluid delivery capabilityVSAvoidfluid separation maintenance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The fitting is segmented into distinct inner and outer portions, each handling separate fluid passages. The inner portion carries the first fluid while the outer portion carries the second fluid, maintaining separation throughout the fitting structure and preventing mixing at the exit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The inner portion is nested within the outer portion of the fitting, creating concentric fluid passages. This nested configuration allows both fluids to be transported simultaneously through the same fitting while maintaining complete separation, solving the fluid mixing problem at the exit.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Productivity

If conventional oil tubes are used in high temperature environments, then engine operation is enabled, but oil coking occurs causing blockages

Engineering Contradiction:
Improveengine operation capabilityVSAvoidoil coking and blockages
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The oil transport system is segmented into separate hot and cold oil passages within the multiwall tube structure. By isolating the hot oil passage from the bearing housing and using separate return paths, the system prevents oil from being exposed to excessive temperatures that would cause coking and blockages.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The multiwall tube structure acts as an intermediary barrier between the hot oil and the bearing housing. The intermediate walls and sealed fittings prevent direct thermal coupling, allowing hot oil to be transported without transferring excessive heat to the bearing system, thereby preventing oil coking.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If multiwall tube with seal is used, then fluid isolation is improved, but device complexity increases

Engineering Contradiction:
Improvefluid isolationVSAvoidfitting structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fitting combines multiple functions into a single integrated component: fluid separation, structural support, and sealing. By merging the inner and outer portions into one fitted assembly with integrated sealing, the design achieves reliable fluid isolation without proportionally increasing complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The multiwall tube fitting serves multiple functions simultaneously: it transports two separate fluids, provides structural support for the tube assembly, and maintains fluid isolation through integrated sealing. This multi-functionality reduces the need for additional separate components, balancing reliability with complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 effectively isolates fluids and reduces heat transfer, preventing oil coking and ensuring reliable lubricant delivery to bearing systems, even under high-temperature conditions, thereby enhancing the operational efficiency and longevity of gas turbine engines.

Implementation Method 1

the seal is configured to maintain fluid isolation of the first fluid from the second fluid

Methodology Applied
Scientific EffectFluid isolation:

Implementation Method 2

reduces heat transfer, preventing oil coking

Methodology Applied
Scientific EffectHeat transfer reduction: Thermal Insulation

Data Source

PatentEP3730743B1Multiwall tube and fitting for bearing oil supply
Publication Date: 2022.03.30 RTX CORP
  • EP3730743B1 patent drawingFigure 1
  • EP3730743B1 patent drawingFigure 2
  • EP3730743B1 patent drawingFigure 3

AI summary

A multiwall tubing assembly (110) for fluid delivery to a bearing system (38) may comprise a first tube (112) defining an inner fluid passage (124) configured to carry a first fluid (92). A second tube (114) may be disposed around the first tube (112) and may define an outer fluid passage (134) between the first tube (112) and the second tube (114). The outer fluid passage (134) may be configured to carry a second fluid (96). A fitting (150) may be coupled to the first tube (112) and the second tube (114). The fitting (150) may comprise an inner portion fluidly coupled to the inner fluid passage (124) and configured to carry the first fluid (92). An outer portion may be disposed around the inner portion and fluidly coupled to the outer fluid passage (134). The outer portion may be configured to carry the second fluid (96). The fitting (150) may be configured to fluidly isolate the first fluid (92) from the second fluid (96).