Reclining Seat Back Support Linkage to Reduce Back Shear
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Solution Overview
Problem
Conventional reclining seats cause discomfort due to back shear and shifting support items as the back portion moves relative to the user's back during reclining, due to an inherent offset between the pivot point and the hip joint.
Innovation Solution
A seat assembly with a back support adjusting mechanism that includes linking members and slide members to radially move the back support with respect to the pivot point, approximating the path of the user's back, thereby reducing shear and maintaining support alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the back frame is pivotally connected to the seat frame at a fixed pivot joint, then the seat assembly achieves simple structural design and ease of manufacture, but the back support moves relative to the user's back during reclining causing back shear and discomfort
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed pivot connection into a dynamic system where the back support radially moves relative to the pivot point. The back support is no longer fixed at a single point but can radially adjust its position along the back frame, allowing it to dynamically track the user's back movement during reclining and eliminate back shear while maintaining structural simplicity.
2Stability of the object's composition
If the back support is fixed to the back frame, then the structure is simple and stable, but additional support items (headrests, lateral supports) shift position relative to the user during reclining causing inconvenience
Solution Approach 1:
The patent makes the back support dynamically adjustable relative to the back frame, allowing it to radially move as the back frame reclines. This dynamic adjustment ensures that support items attached to the back support maintain proper alignment with the user's body throughout the reclining range, eliminating the shifting problem while preserving structural stability through the radial movement mechanism.
3Object-affected harmful factors
If a complex electronic system is used to track and follow the user's back movement, then back shear can be eliminated and support alignment maintained, but the device complexity and cost increase significantly
Solution Approach 1:
The patent applies the self-service principle by designing a passive mechanical system where the back support automatically radially moves in response to back frame rotation. The system uses the motion itself to drive the radial adjustment through geometric relationships and linkage mechanisms, eliminating the need for sensors, motors, or electronic control systems while still achieving perfect tracking of the user's back movement.
Solution Approach 2:
The patent introduces mechanical intermediaries (linkages, sliders, or geometric constraints) that translate the rotational motion of the back frame into radial movement of the back support. These intermediary mechanical elements mediate between the simple pivot joint and the complex tracking requirement, achieving accurate back shear elimination through pure mechanical means without electronic systems.
Data Source
AI summary
A seat assembly includes a seat frame, a back frame defining a back plane pivotally connected to the seat frame at a pivot joint, a back support slideably secured to the back frame, and a back support adjusting mechanism. The back support adjusting mechanism includes a first linking member coupling the back support to the seat frame and pivotable about the pivot axis, and a first slide member slideably supported by the back frame and operatively connected to the first linking member. A second slide member is affixed to the back support and slideably supported by the back frame. A second linking member operatively connects the first and second slide members. Pivoting movement of the back frame from the upright position to the reclined position slides the first slide member away from the pivot axis, causing the second linking member to slide the back support toward the pivot axis.