Pull-Out Resistant Fastener for Play-Free Vehicle Assembly

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Solution Overview

Problem

Existing fixing devices for vehicle parts fail to ensure a clearance-free, play-free assembly while maintaining anti-tearing functionality, often requiring multiple devices and complex mounting processes.

Innovation Solution

A fixing device that combines anti-tearing functionality through the cooperation between a male element's head and a retaining element with clearance-free fixing via abutment surfaces, allowing for easy disassembly by altering the cooperation between these surfaces, enabling separation for tool or operator access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixing device uses a retaining element to prevent pull-out during impact, then anti-tearing function is improved, but play-free assembly is deteriorated due to clearance required for disassembly

Engineering Contradiction:
Improveanti-tearing functionVSAvoidplay-free assembly
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The fixing device is segmented into two distinct functional mechanisms: a first fixing mechanism with abutment surfaces that provides play-free assembly, and a second fixing mechanism with a retaining element that provides anti-tearing function. This segmentation allows each mechanism to optimize its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges two previously separate fixing mechanisms into a single integrated fixing device. The male element contains both the first abutment surface for play-free assembly and the second abutment surface (retaining element) for anti-tearing function, combining multiple functions into one component to simplify the overall structure.

Inventive Principle:
Principle #5Merging (Combining)

2Device complexity

If a single fixing device provides both anti-tearing and play-free fixing, then device complexity is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvenumber of fixing devicesVSAvoidmanufacturing complexity
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

The male element is designed as a universal component that performs multiple functions: it provides both play-free assembly through the first abutment surface and anti-tearing protection through the second abutment surface with retaining element. This multi-functionality reduces the number of separate components needed while the modular design keeps manufacturing manageable.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Strength

If the retaining element is positioned close to the head for anti-tearing, then pull-out resistance is improved, but disassembly accessibility is deteriorated

Engineering Contradiction:
Improvepull-out resistanceVSAvoiddisassembly accessibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The fixing device operates in two dynamic states: during normal use, the retaining element is positioned to provide strong pull-out resistance; during disassembly, the retaining element can be moved or removed to allow operator access. This dynamic behavior allows the same component to serve conflicting functions at different times.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The retaining element is pre-positioned to provide anti-tearing function during assembly and normal use. Before disassembly is needed, the retaining element can be moved or removed in advance to enable operator access, preparing the system for the upcoming disassembly operation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3775581B1Fastening device having a pull-out resistance function
Publication Date: 2024.03.06 FAURECIA INTERIEUR IND
  • EP3775581B1 patent drawingFigure 1~2
  • EP3775581B1 patent drawingFigure 3

AI summary

The device (4) for fastening a first part (1) and a second part (2) comprises: - a female element (6) that is intended to be fastened to the first part (1) and comprises a housing (14), - a male element (8) that is intended to be fastened to the second part (2) and comprises a stem (28) comprising a body (32), a foot (30) and a head (34), the head (34) having a transverse dimension (e3), - a retaining element (18) that defines, in the housing (14), a passage (36), the transverse dimension (e4) of which is less than the maximum transverse dimension (e3) of the head (34). The male element (8) comprises a stop surface (40), the female element (6) or the retaining element (18) comprising a complementary stop surface (42), said stop surface (40) cooperating with said complementary stop surface (42) in a fastening configuration.