Vehicle Headrest Structure for Neck Bending Moment Reduction
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Solution Overview
Problem
Existing headrest devices may cause the occupant's head to tilt backward or forward during a rear-on collision due to resilient deformation of the core member, resulting in a bending moment on the neck, which can be detrimental to neck protection.
Innovation Solution
A headrest device with a forward projection portion of the headrest stay that suppresses head tilting by pivoting about a support face, with the position of the forward projection portion adjusted to control the direction and strength of head tilting based on collision speed and vehicle seat differences, thereby reducing the absolute value of the bending moment on the neck.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a core member made from hard urethane foam is used to support the head during rear-on collision, then the head can be stably supported, but the head may tilt backward or forward due to resilient deformation of the core member, causing a bending moment on the neck
Solution Approach 1:
The headrest stay is divided into multiple functional portions: a support face portion that provides the primary support surface, and a forward projection portion that acts as a pivot constraint. This segmentation allows the support function and the tilting control function to be separated, enabling the support face to deform resiliently while the forward projection portion maintains rotational constraint to prevent harmful head tilting.
Solution Approach 2:
The forward projection portion is pre-positioned to engage with the head or headrest pad before collision occurs. During rear-on collision, this pre-positioned structure immediately constrains the pivot point of the head, preventing backward or forward tilting from the outset. The pivot center is established in advance through the geometric relationship between the forward projection portion and the support face, ensuring the bending moment remains close to zero during impact.
2Object-affected harmful factors
If the position of the forward projection portion is adjusted to control head tilting, then the bending moment on the neck can be reduced, but the device complexity increases
Solution Approach 1:
The headrest stay serves multiple functions: it provides structural support for the headrest pad, forms the support face for head contact, and through its forward projection portion, acts as a pivot constraint to control head tilting. By making the headrest stay multi-functional, the patent avoids adding separate components for each function, thereby controlling device complexity while achieving effective bending moment reduction through proper positioning of the forward projection portion.
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 device effectively reduces the absolute value of the bending moment on the neck, enhancing protection performance by controlling head tilting and maintaining a more stable position during collisions.
Implementation Method 1
suppresses the head supported by the support face from tilting backward or tilting forward by pivoting about the support face as pivoting center
Implementation Method 2
supports a head of an occupant from the rear during a vehicle rear-on collision via a support face that is formed at a front face of the internal structure
Data Source
AI summary
A headrest device comprising: a headrest stay that is coupled to an upper end portion of a seatback of a vehicle seat, and that supports a headrest pad; an internal structure that is embedded inside the headrest pad, that is supported from a rear by the headrest stay, and that supports a head of an occupant from the rear during a vehicle rear-on collision via a support face that is formed at a front face of the internal structure; and a forward projection portion that is configured by a portion of the headrest stay that projects forward, that is disposed at an upper side or a lower side of the support face within the headrest pad, and that suppresses the head supported by the support face from tilting backward or tilting forward by pivoting about the support face as a pivoting center.