Bi-Injected Window Seal Clamp Structure for Easy Demolding

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Solution Overview

Problem

Existing sealing devices for motor vehicle windows face manufacturing complexity due to bi-injected clamps with three-dimensional shapes, which require complex molds and are prone to damage during demolding, affecting attachment quality and aesthetic appearance.

Innovation Solution

A bi-injected clamp design with a frame made of hard plastic (e.g., polypropylene) and a coating of softer material (e.g., thermoplastic) that adheres naturally, allowing easy demolding and reliable attachment to a door element, with a frame structure that facilitates simple manufacturing and improved aesthetic control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bi-injected clamps with complex three-dimensional shapes are used to meet sealing and aesthetic objectives, then sealing performance and aesthetic appearance are improved, but manufacturing complexity increases and demolding becomes difficult

Engineering Contradiction:
Improvesealing performanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The clamp is divided into two functional parts manufactured separately: a frame providing structural support and sealing function, and a coating providing aesthetic appearance. These parts are assembled together rather than manufactured as a single complex bi-injected piece, simplifying the manufacturing process while maintaining sealing performance and aesthetic quality

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The complex bi-injected three-dimensional shape is extracted from the design and replaced with a simpler frame structure. The aesthetic function is extracted as a separate coating component that can be applied to the simplified frame, reducing manufacturing complexity while preserving both sealing and aesthetic objectives

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If bi-injected clamps with complex three-dimensional shapes are used to meet sealing and aesthetic objectives, then sealing performance and aesthetic appearance are improved, but the clamp is prone to damage during demolding

Engineering Contradiction:
Improvesealing performanceVSAvoiddamage resistance during demolding
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

By segmenting the clamp into a simple frame and a separate coating, the frame can be manufactured with sufficient strength to withstand demolding processes without damage. The coating is applied afterward, eliminating the vulnerability of bi-injected complex shapes during demolding while maintaining sealing performance

Inventive Principle:
Principle #1Segmentation

3Shape

If bi-injected clamps are used to achieve aesthetic appearance, then aesthetic quality is improved, but attachment reliability to door element deteriorates

Engineering Contradiction:
Improveaesthetic appearanceVSAvoidattachment reliability
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The functional attachment features (retaining means, branches) are concentrated in the frame structure which is optimized for mechanical performance and reliable attachment. The aesthetic appearance is provided by a separate coating that can be applied to the simplified frame, allowing each component to be optimized for its primary function without compromising the other

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The frame is designed with local structural features (branches, retaining means) optimized for attachment reliability at specific locations. The coating provides localized aesthetic quality where needed, allowing different parts of the clamp to have different properties optimized for their specific functions

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3831629B1Bi-injected sealing device with hook
Publication Date: 2025.09.10 RENAULT SA
  • EP3831629B1 patent drawingFigure 1~2
  • EP3831629B1 patent drawingFigure 3~4
  • EP3831629B1 patent drawingFigure 5~6

AI summary

Sealing device (10) for a window (6,7) of a motor vehicle, characterized in that it comprises a bi-injected clamp (11), the clamp comprising a frame (13) and a coating (14) covering at least part of the frame, the frame comprising a first arm (18) and a second arm (19) intended to extend on either side of an edge (8) of a structure (3), a first arm (18) of the frame comprising a retaining means (26) adapted to cooperate with an opening (15) of the structure (3) to retain the sealing device against the structure (3), the first arm (18) comprising a window (27) extending above the retaining means (26), over the entire height of the first arm.