Vehicle Door Sealing Element Geometry for Lower Thermoformed Height

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Solution Overview

Problem

Existing sealing elements for motor vehicle doors are limited in size reduction due to dimensional constraints during thermoforming, necessitating the use of thick shims and preventing a reduction in the height of the cavity within the sealing element.

Innovation Solution

Designing a sealing element with a sloping dropped edge forming an angle between 100° and 150°, and a sloping sealing surface forming an angle between α-95° and α-85° with the dropped edge, allowing for a flared cavity shape that simplifies thermoforming and reduces the overall height of the sealing element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a traditional sealing element design with a perpendicular dropped edge (90° angle) is used, then the sealing element can be manufactured with standard thermoforming processes, but the height of the sealing element and its cavity cannot be reduced

Engineering Contradiction:
Improveheight of sealing elementVSAvoidmanufacturability of cavity
Core Design Contradiction:
Length of moving objectVSEase of manufacture

Solution Approach 1:

The invention changes the geometric parameter of the dropped edge angle from the conventional 90° to an obtuse angle between 100° and 150°. This parameter change modifies the cavity shape during thermoforming, allowing the cavity walls to flare outward. The flared cavity shape reduces the required cavity depth while maintaining structural integrity, thereby reducing the overall sealing element height from typically several centimeters to potentially 1-2 cm or less.

Inventive Principle:
Principle #35Parameter changes

2Length of moving object

If the height of the sealing element is reduced, then the overall door assembly size is reduced, but the manufacturing of the cavity becomes more difficult due to material flow constraints during thermoforming

Engineering Contradiction:
Improveheight of sealing elementVSAvoidcavity formation precision
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

By changing the dropped edge angle to between 100° and 150°, the invention creates a flared cavity geometry that naturally guides material flow during thermoforming. The flared shape provides gradual material redirection, preventing defects such as wrinkles, voids, or uneven wall thickness that would compromise manufacturing precision. This angle range optimizes the balance between cavity depth reduction and material flow control.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces curvature to the cavity walls through the flared shape created by the obtuse dropped edge angle. Instead of straight vertical walls, the cavity walls curve outward, creating a smoother material flow path during thermoforming. This curvature prevents sharp corners and abrupt transitions, thereby maintaining manufacturing precision while enabling height reduction.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of manufacture

If thick shims are used during thermoforming to maintain cavity shape, then manufacturing is feasible, but the sealing element size and complexity increase

Engineering Contradiction:
Improvemanufacturability of cavityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The obtuse dropped edge angle creates a self-supporting flared cavity shape that requires minimal or no shims during thermoforming. The flared geometry provides inherent structural support during the forming process, allowing the material to hold its shape without additional backing elements. This eliminates the need for thick shims, thereby reducing manufacturing process complexity and the final sealing element size.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention extracts and eliminates the need for shims from the manufacturing process. By redesigning the cavity geometry with the flared shape, the patent removes the auxiliary supporting elements (shims) that were previously necessary to maintain cavity shape during thermoforming. This simplification reduces both process complexity and the number of components required.

Inventive Principle:
Principle #2Taking out (Extraction)

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 new design enables a reduction in sealing element height by approximately 5 to 10 mm, while maintaining a watertight seal, by modifying the cavity shape to facilitate manufacturing and eliminate the need for thick shims.

Implementation Method 1

The sealing element is manufactured by thermoforming a sheet of plastic material

Methodology Applied
Scientific EffectThermoforming: Phase Change

Data Source

PatentEP4377109B1Motor vehicle door having an inner lining and a sealing element
Publication Date: 2026.03.11 STELLANTIS AUTO SAS
  • EP4377109B1 patent drawingFigure 1~2
  • EP4377109B1 patent drawingFigure 3
  • EP4377109B1 patent drawing

AI summary

Motor vehicle door (1) of which an inner lining (10) has an opening (100) closed by a sealing element (14), the sealing element (14) having: - a base (140) having a first sealing surface (146) bearing on a bearing part (102) of the inner lining (10); - a head (142) rigidly connected to the base (140) by way of a connection part (144); the opening (100) being delimited by an end part (108) rigidly connected to the bearing part (102) and forming with the latter an angle α with a value of between 100° and 150°, the head (142) of the sealing element having a second sealing surface (148) bearing on the end part (108) of the sealing element (14), the sealing element (14) being configured such that the first sealing surface (146) and the second sealing surface (148) form an angle β of between α-95° and α-85°.