Steering Wheel Leather Cover Composite Lamination

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Solution Overview

Problem

The leather industry faces challenges in producing steering wheels with uniform stretching, adhesion issues, and meeting high physical and thermal requirements due to the natural variability of leather, leading to inefficiencies and increased costs.

Innovation Solution

A method involving a heat-sealable layered composite with a biaxially stretchable layer laminated onto the back of the leather blank, which reduces elongation variability, enhances adhesion, and improves thermal resistance, allowing for a more uniform and stable leather covering on steering wheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If leather is used as a cover for steering wheels, then natural character and aesthetic appearance are improved, but uniform stretching and adhesion consistency deteriorate due to natural variability of leather

Engineering Contradiction:
Improveuniform stretchingVSAvoidadhesion consistency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies a composite material structure consisting of a textile reinforcement layer laminated to the leather back. This composite construction combines the natural aesthetic properties of leather with the uniform stretching characteristics of textile materials, achieving both natural character and manufacturing consistency.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the physical parameters of the leather by laminating a textile layer with specific elastic properties. This changes the overall elongation behavior from the natural 4-25% variation to a controlled 9-11% uniform stretch, improving manufacturing precision while maintaining leather's natural appearance.

Inventive Principle:
Principle #35Parameter changes

2Weight of moving object

If leather thickness is reduced to reduce weight, then weight is decreased, but physical properties such as tear propagation force and elongation at break deteriorate

Engineering Contradiction:
ImproveweightVSAvoidtear propagation force
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent creates a composite structure where the textile reinforcement layer compensates for the reduced thickness of the leather. This allows the leather cover to maintain adequate weight while achieving the required strength properties through the combined material system.

Inventive Principle:
Principle #40Composite materials

3Temperature

If shrink-optimized leather is used to meet heat storage and climate change test requirements, then thermal resistance is improved, but installation difficulty increases and extreme contours cannot be represented

Engineering Contradiction:
Improvethermal resistanceVSAvoidinstallation difficulty
Core Design Contradiction:
TemperatureVSEase of operation

Solution Approach 1:

The patent changes the elastic parameters of the leather by laminating a textile layer with specific stretch characteristics. This creates a composite material that can be stretched uniformly to 9-11% and maintains its shape, enabling installation on complex contours while meeting thermal resistance requirements.

Inventive Principle:
Principle #35Parameter changes

4Productivity

If multiple leather cuts from different extraction areas are mixed in production, then productivity is improved, but precision of fit and accuracy of contour deteriorate due to different elongations

Engineering Contradiction:
Improveproduction efficiencyVSAvoidprecision of fit
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent standardizes the elongation parameter across all leather cuts by laminating a textile layer that uniformizes the stretch behavior. This allows different leather extracts to be mixed in production while maintaining consistent fit precision, as all pieces now share the same 9-11% elongation characteristic.

Inventive Principle:
Principle #35Parameter changes

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

This solution significantly reduces reject rates, increases productivity, and enhances the physical properties of the leather covering, achieving precise fit and improved thermal resilience while maintaining the natural character of the leather.

Implementation Method 1

laminating the heat-sealable layered composite onto the back of the leather blank

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

The biaxially stretchable sheet is formed of a biaxially stretchable woven fabric... The extremely different elongation of the leather skin (4-25%) can be reduced to a longitudinally and transversely uniform, significantly reduced value

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

heat-sealable layered composite... applying the coating to a steering wheel body

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP2593299B2Steering wheel having a cover and method for the production thereof
Publication Date: 2019.01.30 ZF AUTOMOTIVE SAFETY GERMANY GMBH
  • EP2593299B2 patent drawingFigure 1~3
  • EP2593299B2 patent drawingFigure 4~6

AI summary

A method for producing a steering wheel having a cover (10; 10') comprises the following steps: - providing a section of leather (20) having a front side and a rear side; - providing a heat-sealable laminar composite (12; 12'); - laminating the heat-sealable laminar composite (12; 12') onto the rear side of the section of leather (20); and - fitting the cover (10; 10') onto a basic body of the steering wheel. A steering wheel, in particular for a motor vehicle, comprises a basic body of the steering wheel and a cover (10; 10') fitted thereon. The cover (10; 10') comprises a section of leather (20) with a front side and a rear side, and a heat-sealable laminar composite (12; 12') which is laminated onto the rear side of the section of leather (20).