Vehicle Seat Rail Locking Layout to Prevent Tooth-On-Bridge Delay
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Solution Overview
Problem
Existing vehicle seat longitudinal adjustment devices face challenges in ensuring reliable crash safety, particularly with additional locking mechanisms that can be hindered by 'tooth-on-bridge' positions and are not compatible with thin sheet metal components, complicating compliance with safety standards.
Innovation Solution
An additional locking mechanism for vehicle seats with offset locking elements on both sides of the rail pair, allowing for a more efficient and reliable positive engagement during crashes, and enabling thicker sheet metal reinforcements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional locking mechanism with toothing element and hole pattern is used, then crash safety is improved, but tooth-on-bridge position can occur which delays positive locking
Solution Approach 1:
The locking elements are designed with asymmetric geometry where the locking element on the first side has a different longitudinal position than the corresponding locking element on the second side. This asymmetric arrangement ensures that when one side experiences a tooth-on-bridge position, the other side is at a different phase of engagement, guaranteeing that at least one side achieves positive locking without delay.
2Adaptability or versatility
If manual locking mechanism with 10mm detent increment is used, then adjustment flexibility is improved, but additional toothing can only be matched in thin sheet metal which complicates safety standards compliance
Solution Approach 1:
The solution transitions from two-dimensional planar matching of toothing elements to three-dimensional spatial arrangement by offsetting locking elements in the longitudinal direction. This dimensional change allows the locking mechanism to accommodate the 10mm detent increment while enabling the use of thicker sheet metal components, as the offset arrangement provides additional space for intermediate webs and reinforcement structures.
3Adaptability or versatility
If electric seat longitudinal adjustment is used, then positioning flexibility is improved, but probability of tooth-on-bridge position increases
Solution Approach 1:
The locking system is segmented into multiple independent locking elements distributed at regular intervals along the longitudinal direction. By dividing the locking function into multiple segments rather than relying on a single locking point, the system ensures that if one segment experiences a tooth-on-bridge position, other segments remain available to provide reliable locking, thereby maintaining locking reliability across the full range of electric adjustment positions.
Data Source
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AI summary
An adjustment device (103) for longitudinal adjustment of a vehicle seat is disclosed, comprising at least one pair of rails with a first positionally fixed rail (3) and a second rail (5) guided movably with respect thereto in a longitudinal direction (x), and an additional lock (107) which has a plurality of first locking structures (24, 25) which are formed on the second rail (5) or are connected thereto, and a plurality of second locking structures (36, 37) which are formed corresponding to the first locking structures and are formed on the first rail (3) or are connected thereto. The additional locking is normally ineffective and, after introduction of force in the event of a crash, brings about, by form-fitting connection of the locking structures (24, 25; 36, 37), an additional locking of the second rail (5) to the first rail (3). In order to ensure locking of the longitudinal position of the pair of seat rails in the event of a crash by the additional lock in any desired longitudinal positions, the first and second locking structures (24, 25; 36, 37) are arranged at regular distances (a) from one another on both sides of the respective pair of rails and in the longitudinal direction (x), wherein the first locking structures (24a, 25a; 24b, 25b) or the second locking structures (36a, 37b; 36b, 37b) are arranged offset with respect to one other in the longitudinal direction (x) on both sides of the respective pair of rails.