Elastomer Sheet Wave Structure for Curved-Surface Electrostatic Sensors

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Solution Overview

Problem

Winding sheets around three-dimensional curved surfaces, such as a steering wheel, results in uneven peripheral lengths due to extension and compression, leading to troublesome and inefficient winding processes.

Innovation Solution

An elastomer sheet with a central region and end regions formed in a wave-like shape, allowing differential extension and compression rates to facilitate smooth winding around a curved surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If a planar sheet is wound around a three-dimensional curved surface, then the sheet can cover the curved surface, but wrinkles nonuniformly occur in the sheet due to difference in peripheral length

Engineering Contradiction:
Improvecoverage of curved surfaceVSAvoiduniformity of sheet surface
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The elastomer sheet is pre-formed with a wave-like shape (convex and concave portions) in the cross direction before winding. This preliminary deformation allows the sheet to accommodate the peripheral length difference when wound around the curved surface, preventing nonuniform wrinkles from occurring during the winding process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sheet is pre-deformed to change its geometric parameters by forming wave-like patterns with specific wavelengths and amplitudes. This parameter change enables the sheet to have different effective lengths in different regions, matching the peripheral length variations of the three-dimensional curved surface being wound around.

Inventive Principle:
Principle #35Parameter changes

2Shape

If the sheet is wound while being extended at outer peripheral portion and compressed at inner peripheral portion, then the sheet can follow the curved surface, but the winding work becomes troublesome and inefficient

Engineering Contradiction:
Improveconformity to curved surfaceVSAvoidefficiency of winding work
Core Design Contradiction:
ShapeVSProductivity

Solution Approach 1:

The sheet is pre-formed with wave-like shapes and equipped with extension/compression portions before the winding process. This preliminary preparation eliminates the need for complex real-time extension and compression operations during winding, significantly improving winding efficiency while maintaining conformity to the curved surface.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sheet has different local properties: wave-like shapes in some regions for absorption of peripheral length differences, extension portions in other regions for accommodating expansion, and compression portions for accommodating contraction. This local differentiation allows the sheet to follow the curved surface efficiently without uniform complex operations throughout.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If a cut is formed in the sheet to absorb peripheral length difference, then wrinkle occurrence is reduced, but the sheet structure becomes compromised and winding complexity increases

Engineering Contradiction:
Improvereduction of wrinklesVSAvoidcomplexity of sheet structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of making cuts in the sheet, the invention pre-forms wave-like shapes (convex and concave portions) that can absorb peripheral length differences through their geometric configuration. This approach maintains the sheet's structural integrity while achieving wrinkle reduction, avoiding the complications introduced by cuts.

Inventive Principle:
Principle #10Preliminary action

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 wave-like shape enables easy extension and compression, improving the efficiency of winding the elastomer sheet and electrostatic sensors by adapting to the curvature of the target member.

Implementation Method 1

an elastomer sheet which is made of an elastomer and is wound around a winding target member having a three-dimensional curved surface

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4386344B1Elastomer sheet and electrostatic sensor
Publication Date: 2025.08.13 SUMITOMO RIKO CO LTD
  • EP4386344B1 patent drawingFigure 1~2
  • EP4386344B1 patent drawingFigure 3~4
  • EP4386344B1 patent drawingFigure 5~6

AI summary

Provided is an elastomer sheet (21) made of an elastomer, which is wound on a ring part (12) having a three-dimensional curved surface. The elastomer sheet (21) is provided with: a central region (30) located at the center of the elastomer sheet (21 in a winding direction (Y); and a pair of end regions (31) located at the ends of the elastomer sheet (21) in the winding direction (Y). The central region (30) and the pair of end regions (31) are configured such that the sectional shape thereof, taken along a crossing direction (X) crossing the winding direction (Y) of the elastomer sheet (21), is formed to have a wave-like shape that can be extended or compressed in the crossing direction (X), with the rate of extension or compression of the central region (30) and the rate of extension or compression of the pair of end regions (31) with respect to the crossing direction (X) varying from each other.