Vehicle Seat-Back Adjustment Rack Segmentation for Impact Stability
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Solution Overview
Problem
Existing seat-back adjustment systems in vehicles fail to maintain the desired seat position during extreme acceleration or deceleration events, such as collisions, due to mechanical failure of gear teeth under high forces, and increasing strength or size of gear teeth is not a viable solution as it complicates manufacturing and compromises fine positioning.
Innovation Solution
A seat-back adjustment system featuring a frame member with a rack arrangement including an adjustment rack and a locking rack of different mechanical strengths, where a driving gear intermeshes with the adjustment rack and a locking element engages the locking rack only during predetermined negative acceleration to inhibit movement, ensuring the seat back remains in position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the strength of gear teeth is increased to maintain seat back position under high forces, then reliability improves, but manufacturing complexity and cost increase
Solution Approach 1:
The system divides the rack into two separate racks: an adjustment rack with gear teeth for normal positioning operations, and a locking rack with locking teeth for high-force situations. This segmentation allows each rack to be optimized for its specific function, with the locking rack using simpler, stronger teeth geometry that would be too crude for fine adjustment operations.
Solution Approach 2:
The locking element acts as an intermediary that engages the locking rack only when high forces are detected (during negative acceleration). This mediator transfers the load from the gear teeth to the locking teeth, protecting the adjustment rack from high forces while maintaining fine positioning capability during normal operation.
2Reliability
If the size of gear teeth is increased to provide strength under high forces, then reliability improves, but positioning precision deteriorates
Solution Approach 1:
The system divides the rack into two separate racks: an adjustment rack with gear teeth for normal positioning operations, and a locking rack with locking teeth for high-force situations. This segmentation allows each rack to be optimized for its specific function, with the locking rack using simpler, stronger teeth geometry that would be too crude for fine adjustment operations.
Solution Approach 2:
The system dynamically switches between two different tooth engagement mechanisms based on loading conditions. During normal operation, the gear teeth provide fine positioning. During high-force events (detected via negative acceleration), the locking element engages the locking teeth, dynamically adapting the system's mechanical properties to match the operational demands.
3Device complexity
If a single rack with uniform teeth is used for both adjustment and locking, then device complexity decreases, but reliability under high forces deteriorates
Solution Approach 1:
The system applies local quality by creating two distinct racks with different tooth characteristics optimized for different functions. The adjustment rack has precision gear teeth for fine positioning, while the locking rack has robust locking teeth for high-force situations. Each local structure (rack type) is specifically tailored to its functional requirement rather than using a uniform design throughout.
Solution Approach 2:
The system divides the rack into two separate racks: an adjustment rack with gear teeth for normal positioning operations, and a locking rack with locking teeth for high-force situations. This segmentation allows each rack to be optimized for its specific function, with the locking rack using simpler, stronger teeth geometry that would be too crude for fine adjustment operations.
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 system provides cost-effective, fine positioning of the seat back while maintaining stability under high forces, preventing mechanical failure during vehicle impacts by utilizing a combination of materials and design that separates adjustment and locking functions effectively.
Implementation Method 1
A locking arrangement may include at least one locking element operable to engage the locking teeth and inhibit movement of the rack arrangement relative to the frame member when the vehicle experiences at least a predetermined negative acceleration
Implementation Method 2
A driving arrangement may include at least one gear having gear teeth intermeshing with the adjustment teeth and operable to move the rack arrangement relative to the frame member
Data Source
AI summary
A seat-back adjustment system for a seat for a vehicle may include a frame member configured for attachment to a support structure of the vehicle, and a rack arrangement movably attached to the frame member. The rack arrangement may include an adjustment rack and a locking rack. A driving arrangement may include at least one gear intermeshing with the adjustment rack and operable to move the rack arrangement relative to the frame member, and a locking arrangement may include at least one locking element operable to engage the locking rack when the vehicle experiences at least a predetermined negative acceleration.