Vehicle Seat Bracket Fastening With Offset Bolt Pattern
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Solution Overview
Problem
Vehicle seat backrests made of resin materials face damage from reaction forces during collisions due to the concentration of bolts, leading to weight and processing cost issues when reinforced with ribs or additional bolts.
Innovation Solution
A vehicle seat design with a reclining mechanism where three bolts (first, second, and third) fasten the bracket to the seat back, with the third bolt's insertion position offset from the straight line of the first and second bolts, distributing reaction forces and maintaining a compact bracket to prevent weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the seat back is reinforced with a large number of ribs to prevent damage from reaction force, then the strength of the seat back is improved, but the weight of the seat back increases
Solution Approach 1:
The patent divides the reaction force resistance function into multiple bolt insertion positions (first, second, and third bolts) distributed across the bracket. By segmenting the fastening points, the reaction force is distributed across multiple locations rather than concentrated in one area, reducing the need for heavy rib reinforcement while maintaining strength
Solution Approach 2:
The seat back uses a composite structure combining resin material with strategically positioned reinforcement ribs only where necessary (near bolt insertion positions). This localized reinforcement approach maintains overall strength while minimizing unnecessary material usage and weight
2Strength
If the number of bolts is increased to prevent concentration of reaction force, then the strength of the seat back is improved, but the size of the bracket increases causing weight increase
Solution Approach 1:
The patent applies local quality by positioning bolts with specific insertion positions offset from the straight line connecting other bolts. This creates localized reinforcement zones around each bolt insertion point in the seat back, allowing the bracket to maintain a compact size while distributing reaction forces effectively through strategically placed fastening points
3Device complexity
If two bolts are used to fasten the bracket to the seat back, then the device complexity is reduced, but the reaction force concentrates on one bolt causing potential damage
Solution Approach 1:
The patent transitions from a linear arrangement of bolts (which would lie on a straight line) to a two-dimensional distributed arrangement where the third bolt's insertion position is offset from the straight line connecting the first and second bolts. This dimensional change creates a triangular fastening pattern that provides better geometric distribution of reaction forces, improving reliability while maintaining simple fastening components
Data Source
AI summary
A vehicle seat 1 includes a seat cushion 2 for supporting the buttocks of an occupant, a backrest 3 having a seat back 5 and supporting the back of the occupant, and a reclining mechanism 8 having a bracket 82 that rotates about a rotation axis C and enabling the backrest 3 to rotate relative to the seat cushion 2. The bracket 82 is fastened onto a side surface plate 51 of the seat back 5 by a first bolt 61, a second bolt 62, and a third bolt 63 that pass through the bracket 82 and the side surface plate 51. An insertion position for the third bolt 63 is offset from a straight line L passing through an insertion position for the first bolt 61 and an insertion position for the second bolt 62.