Vehicle Seat Backrest Stiffness Segmentation
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Solution Overview
Problem
Conventional vehicle seats fail to maintain occupant posture stability during steering and turning, causing unnecessary swaying and twisting motions that can lead to discomfort and fatigue, as they do not allow for flexible longitudinal movement of the upper body.
Innovation Solution
A vehicle seat design featuring distinct supporting areas with varying stiffness levels, where the first supporting area for shoulders has lower perpendicular and shearing stiffness, the second supporting area for the spine has higher stiffness for both load types, and an optional third area for the lumber spine has reduced shearing stiffness, allowing for natural posture and movement during steering and turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the vehicle seat uses a conventional rigid structure, then manufacturing complexity is reduced, but occupant posture stability during steering and turning deteriorates
Solution Approach 1:
The backrest is divided into multiple supporting areas (first, second, and third supporting areas) with different stiffness characteristics. Each area is segmented to provide specific support functions: the first area supports shoulder blades with flexibility, the second area supports the spine with higher stiffness, and the third area supports the lumbar region with reduced shearing stiffness. This segmentation allows the seat to maintain posture stability without requiring complex rotary joint mechanisms.
Solution Approach 2:
Different regions of the backrest are assigned different local qualities in terms of stiffness. The first supporting area has lower perpendicular and shearing stiffness to allow shoulder movement, the second supporting area has higher stiffness for spinal support, and the third supporting area has reduced shearing stiffness for lumbar flexibility. This local differentiation of mechanical properties enables the seat to adapt to various body movements during steering and turning.
2Ease of operation
If the vehicle seat allows flexible upper body movement, then comfort during steering is improved, but head stability deteriorates
Solution Approach 1:
The backrest structure incorporates dynamic characteristics through its segmented design, allowing it to adapt its stiffness response based on the direction and type of applied load. The varying stiffness in different supporting areas enables the structure to move flexibly with upper body movements during steering while maintaining sufficient stability to prevent excessive head movement. The dynamic response is achieved through the inherent mechanical properties of the segmented supporting areas rather than active control mechanisms.
3Adaptability or versatility
If the vehicle seat uses rotary joints for rotational motion, then adaptability to occupant movement is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces complex rotary joint mechanisms with a statically structured backrest that achieves adaptability through carefully engineered stiffness distribution. Instead of using mechanical joints to allow rotation and movement, the invention uses a rigid structure with varying local stiffness properties that passively adapt to occupant movements during steering and turning. This substitution of active mechanical joint systems with a passive stiffness-based system reduces manufacturing complexity and cost while maintaining adaptability.
Data Source
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AI summary
A vehicle seat (1) with improved comfort is provided. A seatback (3) includes a seatback frame (6) and a backrest (7) attached to the seatback frame (6). The backrest (7) includes a first supporting area (7A) to which a load of a shoulder (S) of the occupant (8) is applied, and a second supporting area (7B) to which a load of spine area of the occupant (8) is applied. Support stiffness in the first supporting area (7A) for a vertical load is lower than that in the second supporting area (7B), and support stiffness in the second supporting area (7B) for a shearing load is higher than that in the first supporting area (7A).