Flexural-Joint Seat Backrest for Adaptive Lumbar Support
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Solution Overview
Problem
Vehicle seats with fixed shapes fail to provide comfortable support for diverse occupant postures, as they do not adapt to changes in seating position, leading to improper fit and support for passengers who shift or sit in different positions.
Innovation Solution
A vehicle seat with a deformable seat shell and a compliant shell-motion controller that allows the seat back to change shape from an initial lordosis position to a final kyphosis position in response to passenger movement, using upper and lower motion-control links with flexural joints to maintain customized support regardless of posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed shape seat back is used, then the structure is simple and stable, but it cannot adapt to different occupant postures and positions
Solution Approach 1:
The seat back incorporates a deformable shell supported by motion-control links with flexural joints, enabling the structure to dynamically change shape in response to occupant forces. The flexural portions bend during deformation, allowing the seat back to adapt to different postures (upright, slouching, shifted positions) while maintaining structural integrity through controlled mechanical movement between lordosis and kyphosis positions.
Solution Approach 2:
The seat back changes its geometric parameters (shape, contour, position) in response to forces applied by the occupant. The deformable shell can assume different shapes between initial (lordosis) and final (kyphosis) positions, with the flexural joints enabling controlled parameter changes that provide customized support for various seating positions without requiring manual adjustment.
2Adaptability or versatility
If a deformable seat shell with motion control is used, then adaptability to different postures is improved, but the device complexity increases
Solution Approach 1:
The deformable seat shell automatically adjusts to the occupant's posture and position through forces applied directly by the occupant's body. The compliant shell-motion controller requires no external power source, control systems, or manual adjustment - the occupant's own movements and body weight drive the deformation and repositioning of the seat back, providing self-adjusting customized support.
Solution Approach 2:
The flexural joints act as intermediaries between the deformable shell and the support frame, enabling controlled motion while simplifying the overall structure. These joints with defined pivot axes allow the complex deformation behavior to be achieved through relatively simple mechanical components that guide the motion between lordosis and kyphosis positions.
3Adaptability or versatility
If the seat back is made rigid for structural stability, then manufacturing is easier, but it cannot provide customized support for different positions
Solution Approach 1:
The seat back uses a deformable shell instead of a rigid structure, allowing the shell to flex and change shape in response to occupant forces. This flexible shell can be molded into the desired initial contour and then deforms predictably within the controlled range between lordosis and kyphosis positions, providing customized lumbar support while maintaining ease of manufacturing through conventional shell molding techniques.
Solution Approach 2:
The seat back transitions from a static rigid structure to a dynamic deformable structure controlled by flexural joints with defined pivot axes. This allows the shell to assume different shapes during deformation while maintaining structural stability through the constrained motion paths provided by the joints, enabling customized support without sacrificing manufacturability.
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 seat provides predictable and customized lumbar support for passengers in various positions, ensuring comfort and proper pressure distribution across a range of postures without requiring frequent adjustments.
Implementation Method 1
The upper motion-control link includes an upper root portion coupled to the deformable seat shell and a flexural portion that is arranged to interconnect the upper root portion and the link foundation and is configured to bend about a pivot axis so as to establish the flexural joint
Implementation Method 2
a deformable seat shell adapted to assume different shapes, and a compliant shell-motion controller that couples the deformable seat shell with the support frame
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A vehicle seat includes a backrest coupled to an upwardly extending support frame. The backrest includes a deformable seat shell adapted to assume various shapes between an initial position and a final position in response to variable rearward loads applied by the torso of a seated passenger. The seat shell is coupled to the support frame by a compliant shell-motion controller via upper and lower motion-control links. At least one of the motion-control links includes a flexural portion configured to bend about a pivot axis to establish a flexural joint. The lower motion-control link may include a flexural joint and/or a revolute joint, and the upper motion control link may include a flexural, revolute, or spheroidal joint.