Flared Tube Joint Ring to Reduce Torsion and Loosening

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Solution Overview

Problem

Existing flared tube connections in high-pressure applications, such as automobile brake lines, face issues with torsion stress accumulation due to plastic deformations and increased friction, leading to potential loosening of connections, especially during maintenance and re-securing.

Innovation Solution

A tube connecting device with an immovably fixed ring, at least partially coated with an antifriction material, is used to mitigate torsion stress. The ring is secured to the flared end using a bonding agent, shrink-fit, or crimping, and coated with materials like Molybdenum disulfide, PTFE, or graphite to reduce friction, ensuring a secure and stable connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a threaded sleeve is used to secure the flared end of the tube to the connector, then the connection is fixed and secure, but torsion stress accumulates on the tube leading to potential loosening

Engineering Contradiction:
Improveconnection securityVSAvoidtorsion stress
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

A ring is introduced as an intermediary component between the threaded sleeve and the flared end of the tube. This ring distributes the clamping force over a larger surface area, preventing localized plastic deformations that cause torsion stress accumulation. The ring acts as a mediator that maintains connection security while eliminating the harmful stress concentration on the tube.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the threaded sleeve contacts and forces the flared end of the tube to achieve connection, then the connection is secured, but plastic deformations occur at the contact point leading to coating fracture and possible deformation on the contact surface

Engineering Contradiction:
Improveconnection securityVSAvoidcontact surface deformation
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The ring serves as a protective intermediary between the threaded sleeve and the flared end contact surface. It absorbs and distributes the mechanical stress, preventing direct contact between the sleeve and the tube's contact surface. This eliminates plastic deformations and coating fractures while maintaining the necessary connection force.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the ring is made of harder material than the tube to secure the connection, then the connection is more secure, but plastic deformation occurs at the rear side of the flared end increasing friction and torsion stress

Engineering Contradiction:
Improveconnection securityVSAvoidtorsion stress
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

Instead of changing the material hardness parameter, the solution changes the geometric parameter of the ring - specifically its surface area in contact with the flared end. By increasing the contact surface area, the same connection force is distributed over a larger area, reducing pressure and preventing plastic deformations without requiring harder materials.

Inventive Principle:
Principle #35Parameter changes

4Ease of repair

If the tube connection is removed and re-secured for maintenance, then maintenance is performed, but torsion stress accumulates making the connection vulnerable to loosen

Engineering Contradiction:
Improvemaintenance capabilityVSAvoidconnection stability
Core Design Contradiction:
Ease of repairVSReliability

Solution Approach 1:

The ring as an intermediary component prevents torsion stress accumulation during repeated assembly and disassembly operations. By distributing the clamping force and preventing localized deformations, it maintains connection stability even after multiple maintenance cycles, unlike direct sleeve-to-tube contact which accumulates stress with each operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 reduces torsion stress and friction, enhancing the security and durability of the flared pipe connections by minimizing the risk of loosening, even during repeated assembly and disassembly for maintenance.

Implementation Method 1

A tube connecting device with an immovably fixed ring, at least partially coated with an antifriction material, is used to mitigate torsion stress

Methodology Applied
Scientific EffectFriction reduction through antifriction material coating: Lubrication

Implementation Method 2

The ring is secured to the flared end using a bonding agent, shrink-fit, or crimping

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP3415800B1Tube connecting device
Publication Date: 2024.07.10 BANT BORU SANAYI VETICARET AS
  • EP3415800B1 patent drawingFigure 1
  • EP3415800B1 patent drawingFigure 2
  • EP3415800B1 patent drawingFigure 3

AI summary

The present invention relates to a tube connecting device comprising a tube (1) having a flared end (2) defining a front surface (3) and a rear surface (ç); a threaded sleeve (5) having a through opening (11) for receiving the tube, a connector (6) having a conical seating surface (10) for receiving the front surface of the flared end and a threaded portion being meshable with the threaded sleeve, a ring (15) arranged between the rear surface of the flared end and the threaded sleeve when the threaded sleeve is screwed. The tube connection device of the invention is characterized by the ring is fixed to the rear surface of the flared end before the tube connection is made and the ring maintains its fixation along the connection is made.