Ferrule Subassembly Retention Without Bore Shrinkage

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Solution Overview

Problem

Conventional ferrule fittings for conduits face challenges in maintaining a robust connection and reliable remakes without compromising the fluid tight seal and grip, especially during maintenance and re-tightening processes, where the retaining structure often interferes with the operation of the ferrules or causes bore diameter shrinkage and misalignment.

Innovation Solution

A ferrule subassembly with a retaining structure that allows two ferrules to be retained as a discrete unit, enabling easy assembly and disassembly, maintaining a robust connection without radial compression of the ferrules, and ensuring proper alignment and function during pull-up, using flexible or adhesive retaining mechanisms to facilitate Type 1, 2, or 3 connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a retaining structure is used to hold ferrules together as a discrete unit, then assembly ease is improved, but the retaining structure may interfere with ferrule operation or cause bore diameter shrinkage

Engineering Contradiction:

Improveassembly easeVSAvoidferrule operation reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The ferrule assembly is divided into two separate ferrules (first ferrule and second ferrule) that are retained together as a discrete unit but remain functionally independent. Each ferrule has its own gripping and sealing surfaces that operate independently on the conduit, while the retaining structure only holds them together for assembly purposes without interfering with their individual functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retaining structure acts as an intermediary component that holds the first and second ferrules together as a discrete unit during assembly, but is designed to prevent interference with ferrule operation. The retaining structure includes a retaining extension with an end portion received in a recessed portion, creating a controlled connection that maintains bore diameter and allows proper ferrule function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of repair

If conventional ferrule fittings are loosened and re-tightened for maintenance, then repair capability is improved, but the connection reliability and seal integrity may deteriorate

Engineering Contradiction:

Improvemaintenance capabilityVSAvoidseal integrity

Core Design Contradiction:

Ease of repairVSReliability

Solution Approach 1:

The first and second ferrules are pre-assembled into a discrete unit with proper alignment and spacing before installation on the conduit. This preliminary assembly ensures that when the fitting is loosened and re-tightened for maintenance, the ferrules maintain their predetermined configuration, preventing misalignment that could compromise seal integrity during remake operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of relying on the ferrules to remain perfectly aligned throughout multiple tightening cycles, the invention inverts the approach by pre-establishing the correct alignment in the discrete unit assembly. The retaining structure with its specific extension and recessed portion configuration ensures that the ferrules maintain their proper spatial relationship even during loosening and re-tightening operations.

Inventive Principle:

Principle #13The other way round (Inversion)

3Strength

If the retaining structure compresses the ferrules radially to hold them together, then retention strength is improved, but bore diameter shrinkage occurs

Engineering Contradiction:

Improveretention strengthVSAvoidbore diameter

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

The retaining structure applies retention forces locally at specific points (through the retaining extension received in the recessed portion) rather than compressing the entire ferrule assembly radially. This localized retention method provides sufficient holding strength while maintaining the overall bore diameter and preventing shrinkage of the fluid passage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of using radial compression to hold the ferrules together, the retaining structure uses an axial dimension approach with the retaining extension extending axially and being received in an axially positioned recessed portion. This dimensional change allows retention without radial compression, preserving the bore diameter while maintaining ferrule assembly integrity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11703165B2Ferrule assembly for conduit fitting

Publication Date: 2023.07.18 SWAGELOK CO

AI summary

A ferrule subassembly for a conduit fitting includes first and second ferrules. The first ferrule includes a front body portion defining a forward tapered surface, a rear body portion defining an interior camming surface, and a retaining extension joined with the rear body portion radially outward of the camming surface and extending axially rearward and radially inward from the inner axial portion. The second ferrule includes a front portion having a tapered forward contact surface adjacent the first ferrule camming surface, an outer radial portion extending axially rearward of the forward contact surface, and a recessed portion axially rearward of the outer radial portion. An end portion of the retaining extension is received in the recessed portion of the second ferrule to retain the second ferrule with the first ferrule as a discontinuous subassembly.