Slouch Seat Link Arm Synchronizes Recline Motion
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Solution Overview
Problem
Conventional slouch seats in vehicles often cause 'shirt shear' due to relative movement between the seat backrest and the occupant as the seat reclines, which can be uncomfortable and inconvenient, especially when adjacent to fixed rear walls or bulkheads.
Innovation Solution
A vehicle seat design featuring a dual slide system with a link arm connecting the seat base and backrest, allowing for a 2:1 travel ratio that matches the natural motion of the occupant, eliminating the need for a conventional recliner pivot and preventing shirt shear by synchronizing the motion of the seat base and backrest with the occupant's recline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional recliner pivot is used at the bottom of the backrest, then the seat can recline, but relative motion between the seat back surface and the occupant causes shirt shear
Solution Approach 1:
The backrest is divided into two separate frames: a fixed frame attached to the vehicle structure and a moving frame that can slide relative to the fixed frame. This segmentation allows the backrest to change configuration without rotating about a fixed pivot point, thereby eliminating shirt shear while maintaining recline functionality.
Solution Approach 2:
The backrest transitions from a static structure to a dynamic one where the moving frame can slide forward and backward along the fixed frame. This dynamic adjustment allows the backrest to adapt its position to match the occupant's natural recline motion, preventing relative movement that causes shirt shear.
2Ease of operation
If the backrest rotates rearward about a pivot fitting, then recline is achieved, but the rotation causes relative motion between seat back and occupant
Solution Approach 1:
Instead of rotating the backrest rearward about a pivot at the bottom, the invention inverts the approach by having the moving frame slide forward along the fixed frame. This reverse motion pattern achieves recline while keeping the backrest surface aligned with the occupant's back, eliminating shirt shear.
3Object-affected harmful factors
If a dual slide system with link arm is used, then shirt shear is prevented, but the structure becomes more complex
Solution Approach 1:
The link arm connects the moving frame of the backrest to the seat base, merging the motion control of both components into a single coordinated system. This integration ensures that the backrest and seat base move together in a 2:1 ratio, preventing shirt shear while maintaining manufacturing simplicity through unified motion control.
4Adaptability or versatility
If the seat base and backrest move independently, then adjustment flexibility is high, but coordination with occupant motion is poor
Solution Approach 1:
The link arm acts as a mechanical feedback mechanism that couples the motion of the seat base and backrest. As the occupant reclines, the link arm automatically coordinates the movement of both components in a 2:1 ratio, ensuring the backrest moves at half the speed of the seat base to match the occupant's natural body motion.
Data Source
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AI summary
A vehicle seat includes a seat base and a backrest. A seat base track arrangement has a fixed track and a moveable track that is moveable along the fixed track. The seat base fixed track is connected to a vehicle seat support or fore/aft track to adjust an entire vehicle seat position. The seat base moveable track is connected to the seat base. A backrest track arrangement has a backrest fixed track and a backrest moveable track that is moveable along the backrest fixed track. The backrest fixed track is connected to a vehicle backrest support. A link arm pivotably links the seat base and the backrest. A seat base pivot connection is formed between the link arm and the seat base. A link arm and backrest pivot connection is formed between the link arm and the backrest and the moveable track.