Steering Wheel Cladding with Localized Hardness Gradient

Solution Overview

Problem

Conventional steering wheels lack uniformity in contact area and pressure distribution when held by drivers, leading to discomfort, as the hardness of the cladding layer does not vary sufficiently in the circumferential direction.

Innovation Solution

A steering wheel design with a cladding layer that has a softer region on the side facing the rotation center axis and a harder region on the side facing away from it, allowing fingertips to sink into the softer area while the palm rests on a wider, harder surface, facilitating comfort and vibration propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the cladding layer is made of uniform hardness, then the manufacturing process is simple, but the contact comfort when held by hands is poor

Engineering Contradiction:

Improveholding comfortVSAvoidcladding layer structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The cladding layer is divided into a soft region and a hard region with different hardness values. The soft region is positioned at the inner circumference (facing the rotation center axis) where fingertips contact, providing comfort and pressure distribution. The hard region is positioned at the outer circumference (facing away from the rotation center axis) for structural support and vibration propagation. This local differentiation of material properties resolves the contradiction between comfort and manufacturing simplicity.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the entire cladding layer is made soft, then fingertip comfort is improved, but vibration propagation to the driver is reduced

Engineering Contradiction:

Improvefingertip comfortVSAvoidvibration feedback

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The cladding layer is divided into a soft region and a hard region with different hardness values. The soft region is positioned at the inner circumference (facing the rotation center axis) where fingertips contact, providing comfort and pressure distribution. The hard region is positioned at the outer circumference (facing away from the rotation center axis) for structural support and vibration propagation. This local differentiation of material properties resolves the contradiction between comfort and manufacturing simplicity.

Inventive Principle:

Principle #3Local quality

3Strength

If the cladding layer is made of hard material, then structural strength is improved, but contact comfort and pressure distribution are worsened

Engineering Contradiction:

Improvecladding layer strengthVSAvoidcontact comfort

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The cladding layer is divided into a soft region and a hard region with different hardness values. The soft region is positioned at the inner circumference (facing the rotation center axis) where fingertips contact, providing comfort and pressure distribution. The hard region is positioned at the outer circumference (facing away from the rotation center axis) for structural support and vibration propagation. This local differentiation of material properties resolves the contradiction between comfort and manufacturing simplicity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8683890B2Steering wheel

Publication Date: 2014.04.01 TOYODA GOSEI CO LTD

AI summary

A steering wheel includes a generally annular ring section to be hand held for steering a vehicle, and the ring section includes a core member and a cladding layer that covers an outer circumference of the core member all over. The hardness of the cladding layer is varied in a circumferential direction of a cross section of the ring section in which the core member is located at the center. An occupancy by a soft region is greater in a first region of the cladding layer located on a side facing toward a rotation center axis of the ring section than in a second region of the cladding layer located on a side facing away from the rotation center axis, such that the hardness in the first region is lower than that in the second region.