Sealing Assembly Starter Tooth Locking Mechanism

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Solution Overview

Problem

Sealing assemblies for tubular joints, particularly those involving plastic spigot ends and metal socket ends, often fail to achieve effective locking due to significant radial play, leading to leaks and disengagement issues, especially when manufacturing tolerances result in a high radial clearance.

Innovation Solution

The sealing assembly incorporates a starter tooth that is radially more prominent than other locking teeth, positioned between two adjacent teeth, and extends over a reduced angular range, facilitating initial engagement and ensuring secure locking by concentrating force on a smaller surface area, thereby improving locking performance even with high radial clearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If locking elements with teeth are provided to prevent disengagement, then the locking function is improved, but the radial play between spigot and socket causes the teeth to fail to engage properly with plastic spigots

Engineering Contradiction:
Improvelocking functionVSAvoidradial clearance
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The locking element features two distinct tooth configurations: starter teeth with a larger radial projection designed to bridge the radial clearance and initiate engagement, and locking teeth with standard dimensions for final secure locking. This local differentiation in tooth geometry allows the same locking element to perform both clearance bridging and secure locking functions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The starter teeth perform a preliminary engagement action by projecting radially beyond the locking teeth to first contact and guide the plastic spigot onto the locking element. This preliminary action overcomes the radial clearance issue before the main locking teeth engage, ensuring proper alignment and initial contact.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the locking teeth are made radially prominent to ensure engagement, then the locking effectiveness is improved, but the assembly process becomes more difficult with plastic spigots due to high radial clearance

Engineering Contradiction:
Improvelocking effectivenessVSAvoidassembly process
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking element features two distinct tooth configurations: starter teeth with a larger radial projection designed to bridge the radial clearance and initiate engagement, and locking teeth with standard dimensions for final secure locking. This local differentiation in tooth geometry allows the same locking element to perform both clearance bridging and secure locking functions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The starter teeth perform a preliminary engagement action by projecting radially beyond the locking teeth to first contact and guide the plastic spigot onto the locking element. This preliminary action overcomes the radial clearance issue before the main locking teeth engage, ensuring proper alignment and initial contact.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If multiple locking teeth are provided around the longitudinal axis, then the locking stability is improved, but the complexity of the locking element increases

Engineering Contradiction:
Improvelocking stabilityVSAvoidlocking element structure
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The locking element's teeth are segmented into two functional groups: starter teeth and locking teeth. This segmentation allows each group to perform its specific function optimally while keeping the overall structure manageable. The starter teeth handle initial engagement, and the locking teeth handle secure locking, dividing the complex engagement process into simpler sequential steps.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking element features two distinct tooth configurations: starter teeth with a larger radial projection designed to bridge the radial clearance and initiate engagement, and locking teeth with standard dimensions for final secure locking. This local differentiation in tooth geometry allows the same locking element to perform both clearance bridging and secure locking functions.

Inventive Principle:
Principle #3Local quality

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 design enhances the locking mechanism's effectiveness, ensuring secure engagement and preventing disengagement of the spigot end within the socket end, particularly in conditions with high radial play, thereby reducing leaks and improving the assembly's reliability.

Implementation Method 1

the starter tooth is radially more prominent than at least one of the other locking teeth, the starter tooth being intended to bite into the spigot in an initial position of locking the spigot relative to the socket end... concentrating force on a smaller surface area

Methodology Applied
Scientific EffectMechanical Force: Force

Data Source

PatentEP2923132B1Sealing assembly for a tubular joint, and corresponding tubular joint
Publication Date: 2018.02.14 SAINT GOBAIN PAM SA
  • EP2923132B1 patent drawingFigure 1
  • EP2923132B1 patent drawingFigure 2
  • EP2923132B1 patent drawingFigure 3

AI summary

The invention relates to a sealing assembly (8) for a tubular joint (2) between a plain end (6) and a fitting end (4), the fitting end comprising an inner groove (12) forming a groove wall (14). The sealing assembly includes: a sealing gasket (18) that defines a longitudinal axis (X-X) of the tubular joint and is to be placed in the inner groove (12) around the plain end (6); and at least one locking element (20) that is placed on the sealing gasket (18) and is suitable for locking the plain end into the fitting end. The locking element extends around the longitudinal axis on an angular locking pad and comprises a radially outer surface (30) and a radially inner surface (32), the inner surface (32) comprising a plurality of locking teeth (40A, 40B, 40C, 40D, 40E) suitable for biting into the plain end in a final position for locking the plain end into the fitting end, the plurality of locking teeth including at least one leading tooth (40E). The leading tooth extends around the longitudinal axis on an angular leading pad below the angular locking pad. The invention also relates to a corresponding tubular joint.