Rail End Cap Four-Bar Linkage for Tolerance Compensation
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Solution Overview
Problem
Existing end caps for rails, particularly in vehicle seat longitudinal adjusters, face challenges in tolerance compensation due to production variations, leading to misalignment issues.
Innovation Solution
The end cap features a four-bar linkage mechanism that connects the cover section to the fastening section, allowing for elastic deformation and compensation of tolerance discrepancies between the opening and the rail edge, with a projection that can be curved to match the rail contour, ensuring secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid fastening system is used to attach the end cap to the rail, then the structural strength is improved, but manufacturing tolerance variations cause misalignment and fit issues
Solution Approach 1:
The patent changes the structural parameters of the fastening system by introducing a four-bar linkage mechanism with articulated connections. This mechanism transforms the rigid fastening into a kinematically constrained system that can adapt to tolerance variations while maintaining fastening strength. The four-bar linkage allows controlled movement and adjustment to compensate for manufacturing tolerances in the opening position relative to the rail end edge.
Solution Approach 2:
The patent applies dynamics by making the fastening section capable of controlled movement through the four-bar linkage mechanism. The articulated connections (joints) allow the fastening section to dynamically adjust its position and orientation to accommodate tolerance variations during assembly, while still providing secure fastening when installed.
2Ease of manufacture
If the end cap design is simplified for easier manufacture, then manufacturing complexity is reduced, but tolerance compensation capability is lost
Solution Approach 1:
The patent segments the end cap into distinct functional sections: a cover section and a fastening section connected by a four-bar linkage. This segmentation allows each part to be manufactured separately with standard tolerances, while the articulated connection between sections provides the tolerance compensation mechanism, achieving both ease of manufacture and precision adaptation.
Solution Approach 2:
The four-bar linkage acts as an intermediary mechanism between the cover section and fastening section. This intermediary structure absorbs and compensates for tolerance variations, allowing simple, easily manufactured components to work together precisely through the mediating action of the articulated linkage mechanism.
3Device complexity
If standard fastening methods are used without tolerance compensation, then device complexity is minimized, but assembly precision and fit quality deteriorate
Solution Approach 1:
The patent introduces controlled dynamics through the four-bar linkage, which provides adaptive movement capability. This dynamic mechanism allows the fastening system to self-adjust to tolerance variations, achieving high fit precision without requiring extremely complex adjustment mechanisms or precision manufacturing processes.
Solution Approach 2:
The patent employs a composite structural approach by combining rigid elements (cover section, rail) with a flexible kinematic mechanism (four-bar linkage with joints). This composite design achieves both structural integrity and tolerance compensation, providing precise fit without excessive overall system complexity.
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
This design effectively compensates for production tolerances, ensuring a secure and precise fit, reducing play between the end cap and the rail, and facilitating easier assembly while maintaining aesthetic and protective functions.
Implementation Method 1
The end cap can be elastically deformable, at least in sections
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to an end cap (20) for a rail (12, 14), in particular of a longitudinal adjuster (6), wherein the end cap (20) has a covering portion (22), for covering an end-face end (16) of the rail (12, 14), and a fastening portion (24), for fastening the end cap (20) to the rail (12, 14), wherein the fastening portion (24) is connected to the covering portion (22) forming a four-bar-linkage coupling mechanism (30). The invention furthermore relates to a longitudinal adjuster (6), in particular for a vehicle seat (1), having at least one pair of rails (10) which is formed from a first rail (12) and a second rail (14), which is guided displaceably in the longitudinal direction (x) relative to the first rail (12), wherein at least the first rail (12) or the second rail (14) has at least one opening (18) for the fastening of an end cap (20) for an end (16) of the respective rail (12, 14), wherein the longitudinal adjuster (6) has an end cap (20) fastened in the opening (18).