Panel Fastener Lock Pin Assembly for Low-Force Secure Retention

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Solution Overview

Problem

Conventional fastener assemblies in high impact areas, such as side curtain airbag assemblies, face challenges with prohibitively high installation forces, ergonomic difficulties, and degradation due to repetitive removal and reinstallation, often requiring additional components and complex manufacturing processes.

Innovation Solution

A fastener assembly comprising a panel fastener and a lock pin with retention features that allow axial insertion and retention without specialized tools or manual twisting, enabling the lock pin to snap into position and maintain retention during shipping and installation, and transition to a final assembled state upon installation, using retention tabs and flexible arms for secure engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional fastener assemblies are used in high impact areas, then retention under load is achieved, but installation forces become prohibitively high and ergonomic difficulties arise

Engineering Contradiction:
Improveretention under loadVSAvoidinstallation forces
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The lock pin incorporates a flexible arm that can dynamically change its position during insertion. The flexible arm flexes inwardly during insertion and then outwardly to engage the retention tab, allowing the fastener to adapt to installation forces rather than rigidly resisting them. This dynamic behavior reduces peak installation forces while maintaining retention strength.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The flexible arm changes its physical state from a non-engaged position to an engaged position through flexing. This parameter change allows the lock pin to transition from a state that accommodates insertion forces to a state that provides retention under load, effectively decoupling installation force requirements from retention strength.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional fastener assemblies are used, then fastening function is achieved, but degradation occurs due to repetitive removal and reinstallation

Engineering Contradiction:
Improvefastening functionVSAvoidservice life under repetitive cycles
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The flexible arm automatically returns to its engaged position with the retention tab after insertion, without requiring additional manual manipulation or tools. This self-servicing mechanism ensures consistent engagement across multiple service cycles, preventing degradation that would occur with manual resetting or tool-assisted reinstallation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The design separates the locking function (flexible arm engaging retention tab) from the insertion action. By extracting the locking mechanism as a distinct, self-actuating feature rather than requiring it to be manually set during installation, the system eliminates wear and degradation associated with repetitive manual manipulation of the locking mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

3Strength

If conventional fastener assemblies are used, then fastening capability is achieved, but additional components and complex manufacturing processes are required

Engineering Contradiction:
Improvefastening capabilityVSAvoidnumber of components
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The lock pin combines multiple functions into a single component: the flexible arm provides both the insertion guidance and the locking engagement, while the retention tab integrates the panel retention and lock engagement functions. This merging eliminates the need for separate locking mechanisms, retaining clips, or adjustment components, reducing overall device complexity while maintaining fastening capability.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If conventional fastener assemblies are used, then fastening function is achieved, but specialized tools or manual twisting are required for installation

Engineering Contradiction:
Improvefastening functionVSAvoidinstallation simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The flexible arm automatically performs the locking action during linear insertion, eliminating the need for manual twisting or specialized tools. The arm flexes inwardly during insertion and self-actuates to engage the retention tab, providing a tool-free, simplified installation process while ensuring reliable fastening function.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Instead of requiring the installer to manually set or twist a locking mechanism into place, the design inverts the approach by having the insertion motion itself trigger the locking action. The flexible arm's natural flexing during linear insertion automatically engages the retention tab, reversing the conventional sequence where locking is a separate manual step.

Inventive Principle:
Principle #13The other way round (Inversion)

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 fastener assembly reduces installation complexity and cost, maintains retention under high impact and static loads, and allows for repeatable performance without degradation, even after multiple service cycles, by providing a secure and efficient locking mechanism that does not require additional components or complex manufacturing.

Implementation Method 1

The flexible arm being configured to upon insertion of the lock pin into the panel fastener in a first direction to the first position, flex inwardly and then outwardly to bring the end surface into engagement with the panel retention tab

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

Upon insertion of the lock pin into the panel fastener in the first direction to the second position, the flexible arm being configured to flex inwardly to allow the retention tab to pass into the panel fastener to bring the retention surface into engagement with the first panel retention surface

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3830431B1Fastener assembly and method
Publication Date: 2023.12.06 ILLINOIS TOOL WORKS INC
  • EP3830431B1 patent drawingFigure 1
  • EP3830431B1 patent drawingFigure 2
  • EP3830431B1 patent drawingFigure 3~4

AI summary

A fastener assembly is provided. In one embodiment, the fastener assembly includes a panel fastener and a lock pin insertable into the panel fastener to a first position and a second position. The lock pin including a flexible arm configured to upon insertion of the lock pin into the panel fastener in a first direction to the first position, flex inwardly and then outwardly to bring an end surface of the flexible arm into engagement with a panel retention tab of the panel fastener. Upon insertion of the lock pin into the panel fastener in the first direction to the second position, the flexible arm is configured to flex inwardly to allow a retention tab to pass into the panel fastener to bring a retention surface of the lock pin into engagement with a first panel retention surface of the panel fastener.