Pipe Joint Structure With Bending Suppressing Ring Segments

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Solution Overview

Problem

Conventional pipe joints with separation preventive functions fail to achieve sufficient bending rigidity, especially when the diameter of the pipes is large, due to restricted expansion and contraction.

Innovation Solution

A pipe joint design that incorporates a bending suppressing member, preferably a ring-shaped member divided into arcuate pieces, between the inner circumference of the socket and the outer circumference of the spigot, along with an expansion/contraction suppressing member, to restrict movement and enhance bending rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional pipe joint with separation preventive function is used, then the spigot can be prevented from separating from the socket, but the bending rigidity of the pipe joint is insufficient especially when the diameter of the pipes is large

Engineering Contradiction:
Improveseparation preventionVSAvoidbending rigidity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The bending suppressing member is divided into a plurality of arcuate bending suppressing pieces in the circumferential direction. This segmentation allows the member to be easily inserted between the socket and spigot while collectively providing sufficient bending resistance. Each arcuate piece contributes to the overall bending suppression when assembled in a ring shape.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A bending suppressing member is introduced as an intermediary component between the socket and spigot to prevent relative bending movement. This mediator component directly addresses the bending rigidity deficiency without interfering with the existing separation preventive mechanism (lock ring and spigot protrusion).

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the pipe joint is designed to allow expansion and contraction, then the pipe joint can accommodate thermal expansion, but the bending rigidity is reduced and cannot adequately counteract thrust force

Engineering Contradiction:
Improveexpansion/contraction capabilityVSAvoidbending rigidity
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The bending suppressing member is specifically positioned in the range between the distal end of the spigot and the engaging part (spigot protrusion and lock ring), rather than spanning the entire joint. This localized placement provides bending resistance exactly where needed while allowing expansion and contraction in other regions of the joint.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The pipe joint maintains dynamic capability for expansion and contraction through the liner and seal structure, while the bending suppressing member provides static resistance to bending forces. The system dynamically adapts to thermal changes while resisting thrust forces through the bending suppression mechanism.

Inventive Principle:
Principle #15Dynamics

3Strength

If a liner is mounted to secure the spigot in the pipe axis direction, then expansion and contraction are restricted and bending rigidity is increased, but the device complexity increases

Engineering Contradiction:
Improvebending rigidityVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The bending suppressing member is divided into multiple arcuate pieces that can be independently inserted and assembled. This segmentation simplifies the installation process compared to installing a single large liner, as the smaller pieces are easier to maneuver into position between the socket and spigot.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bending suppression function is extracted as a separate, removable component rather than being integrated into the permanent structure of the socket or spigot. This allows the bending suppressing member to be installed and removed independently, simplifying maintenance and reducing overall system complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP4043771B1Pipe joint
Publication Date: 2025.01.15 KUBOTA CORP
  • EP4043771B1 patent drawingFigure 1
  • EP4043771B1 patent drawingFigure 2
  • EP4043771B1 patent drawingFigure 3

AI summary

In a pipe joint 1, a spigot 5 is inserted into a socket 3; a lock ring 8 is accommodated in a lock ring-accommodating groove 7 formed in the inner circumference of the socket 3; and an engaging part 15 formed in the outer circumference of the spigot 5, wherein the engaging part 15 engages with the lock ring 8 from a back side of the socket in a separation direction A of the spigot 5, thereby preventing the spigot 5 from separating from the socket 3. The engaging part 15 is formed at a position receding from a distal end of the spigot 5 in the separation direction A of the spigot 5. A bending suppressing member 35 for restricting the socket 3 and the spigot 5 in a bending direction C is provided between the inner circumference of the socket 3 and the outer circumference of the spigot 5 in the range between the distal end of the spigot 5 and the engaging part 15.