Motor Vehicle Seat Rail Detachment Lock for Crash Safety
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Solution Overview
Problem
Existing longitudinal adjustment devices for motor vehicle seats face challenges in reliably securing the seat rail at its rear end position during crashes, where high acceleration forces can cause separation or tearing apart, especially when a seatbelt lock is engaged.
Innovation Solution
A detachment lock is introduced that fixes the seat rail to the bottom rail in the Z-axis direction at the rear end position, blocking or hindering detachment, allowing the rails to be dimensioned without considering peak loads, and comprising a locking element and holding element that engage only under crash conditions, providing enhanced tear resistance and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seat rail and bottom rail are designed with U-shaped cross section and hooked engagement to resist separation, then tear resistance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The detachment lock is implemented as a separate, distinct component from the seat rail and bottom rail. This segmentation allows the locking function to be added independently without redesigning the entire rail structure, thereby reducing overall device complexity while maintaining tear resistance
Solution Approach 2:
The detachment lock acts as an intermediary element between the seat rail and bottom rail, providing the separation resistance function. This mediator approach allows the rails themselves to remain simpler in design while the lock component handles the complex engagement and locking functions
2Reliability
If the rails are designed to withstand highest loads at rear end position, then reliability is improved, but manufacturing cost and material usage increase
Solution Approach 1:
The detachment lock provides localized reinforcement specifically at the rear end position of the seat rail where crash loads are highest. This allows the rails to be designed with uniform, simpler cross-sections while achieving high reliability through localized protection where it is most needed
Solution Approach 2:
The detachment lock is pre-positioned and pre-configured to engage automatically when crash loads occur. This preliminary positioning ensures that the protective function is already in place before the crash event, allowing the rails to be designed without over-engineering for peak loads
3Strength
If the detachment lock is added to fix the seat rail at rear end position, then tear resistance is improved, but device complexity increases
Solution Approach 1:
The detachment lock is designed to engage and disengage automatically based on the position and load conditions, without requiring external control systems. The lock self-activates when the seat rail approaches the rear end position or when crash loads are applied, reducing the need for additional sensors, actuators, or control electronics
Data Source
AI summary
The invention relates to a longitudinal adjustment device of a motor vehicle seat, comprising a stationary bottom rail connectable to a motor vehicle and a seat rail connectable to the vehicle seat and longitudinally displaceably supported on the bottom rail between a front and a rear end position. In order to provide a longitudinal adjustment device which protects the seat rail against a crash-induced displacement with respect to the bottom rail in the area of its rear end position, it is provided that the detachment lock in effective connection with the bottom rail and the seat rail in the area of their rear end position is formed in such a manner that it blocks a crash-induced separation of the seat rail from the bottom rail.