Vehicle Headrest with Dual-Urethane Pad for Neck Load Reduction
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Solution Overview
Problem
Existing vehicle seat headrests do not effectively reduce load on the neck portion of occupants during rear collisions while maintaining noise and vibration (NV) performance.
Innovation Solution
A headrest structure featuring elastically deformable urethane cushion materials with varying elastic coefficients, where a first cushion material supports a mass body and a second cushion material with a higher elastic coefficient increases supporting rigidity, reducing neck load through dynamic damping and vibration suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dynamic damper with mass body and elastically deformable cushion material is used to suppress seat vibrations, then NV performance is improved, but supporting rigidity during rear collision is insufficient causing increased neck load
Solution Approach 1:
The headrest pad is segmented into two distinct cushion materials: a first cushion material (elastically deformable urethane) that supports the mass body for vibration damping, and a second cushion material (higher elastic coefficient urethane) that provides supporting rigidity during rear collision. This segmentation allows each material to perform its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the headrest pad are assigned different material properties: the first cushion material with lower elastic coefficient is positioned to allow elastic deformation for vibration suppression, while the second cushion material with higher elastic coefficient is positioned to provide rigid support during collision. This local differentiation of material quality resolves the contradiction between flexibility for NV and rigidity for safety.
2Strength
If the headrest pad is made rigid to increase supporting rigidity during rear collision, then neck load is reduced, but seat vibration suppression capability deteriorates
Solution Approach 1:
The headrest pad is divided into two functional zones: a first cushion material region that remains elastically deformable for vibration damping, and a second cushion material region that provides rigidity during collision. This segmentation enables the system to achieve both vibration suppression and collision protection simultaneously.
Solution Approach 2:
The headrest pad uses a composite structure combining two types of urethane materials with different elastic coefficients. The first cushion material (lower elastic coefficient) and second cushion material (higher elastic coefficient) work together in a composite arrangement, allowing the overall structure to exhibit both flexible vibration damping characteristics and rigid collision resistance.
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 headrest effectively reduces neck load during rear collisions while maintaining or improving NV performance by utilizing urethane cushion materials with specific elastic properties to manage seat vibrations and collision forces.
Implementation Method 1
a first cushion material that is disposed at an inner side of a headrest skin, that supports a mass body and is formed of an elastically deformable urethane
Implementation Method 2
a dynamic damper that has the first cushion material and the mass body is structured. Therefore, seat vibrations are suppressed
Implementation Method 3
a second cushion material that is disposed at the inner side of the headrest skin, and that structures a headrest pad together with the first cushion material, and that is formed of a urethane having a higher elastic coefficient than the first cushion material
Implementation Method 4
the elastic coefficient of this second cushion material is set to be higher than that of the first cushion material. Therefore, at the time of a rear collision, owing to the second cushion material, the supporting rigidity of the headrest with respect to the head portion of the vehicle occupant is increased, and the amplitude of the mass body also is suppressed
Implementation Method 5
the first cushion material is fixed to the headrest stay by adhesive force of the urethane itself
Data Source
AI summary
It is obtained a headrest and a vehicle seat provided therewith and a method of manufacturing a headrest, that can reduce load to a neck portion of a vehicle occupant at a time of a rear collision while ensuring NV performance. A first urethane and a second urethane are disposed at an inner side of a headrest skin of a vehicle seat, and structure a headrest pad. The first urethane is embedded in the second urethane, and is elastically deformable, and supports a mass body. An elastic coefficient of the second urethane is set to be higher than that of the first urethane.