Vehicle Seat Frame Stress Distribution via Bracket Mounting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vehicle seat frame structures face issues with stress concentration and creep deformation due to adhesive bonding and bolt fastening, particularly under shock loads, which can lead to peeling and damage of the reclining mechanism and resin material.
Innovation Solution
A vehicle seat frame structure featuring a resin seatback and cushion frame with an outer and inner cushion bracket system, where the reclining mechanism is supported by these brackets and fixed using bolts, distributing stress and preventing direct contact between fastening members and resin material to reduce creep deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the reclining mechanism is mounted to the resin molded portion by adhesive bonding, then the mounting process is simple, but the reclining mechanism will be peeled off under shock loads due to inability to resist peeling forces
Solution Approach 1:
The mounting structure is divided into multiple segments: the resin molded portion, the mounting plate with through-holes, and the reclining mechanism. This segmentation allows the adhesive to bond the mounting plate to the resin molded portion while mechanical fasteners (bolts or rivets) pass through the mounting plate to securely attach the reclining mechanism, distributing the peeling load across multiple connection points and preventing peeling failure
Solution Approach 2:
The mounting structure employs a composite connection method combining adhesive bonding and mechanical fastening. The adhesive provides initial bonding and sealing, while the mechanical fasteners (bolts or rivets) provide structural strength and resistance to peeling loads. This composite approach leverages the advantages of both bonding methods to achieve both ease of manufacture and high reliability
2Strength
If both adhesive bonding and bolt fastening are employed, then the connection strength is improved, but the device complexity increases
Solution Approach 1:
The adhesive bonding and bolt fastening operations are merged into a single integrated mounting process. The mounting plate is pre-equipped with through-holes positioned to align with fastening holes in the reclining mechanism, allowing both adhesive application and mechanical fastening to occur during the same assembly operation. This merging reduces the number of separate steps and simplifies the overall mounting process while maintaining high connection strength
3Ease of manufacture
If the bolt bearing surface contacts the resin material directly, then the fastening is simple, but creep phenomenon occurs causing deformation of the resin material
Solution Approach 1:
The mounting plate serves as an intermediary component between the bolt and the resin molded portion. The bolt passes through the mounting plate (which has through-holes) rather than contacting the resin molded portion directly. This intermediary mounting plate distributes the clamping force over a larger area and prevents direct point loading on the resin material, thereby preventing creep deformation while maintaining fastening simplicity
Solution Approach 2:
The contact area parameter is changed by introducing the mounting plate with through-holes. Instead of the bolt bearing surface contacting the resin material at a small point contact area, the mounting plate provides a larger distributed contact area. This parameter change reduces the contact pressure (force per unit area) on the resin material, preventing creep phenomenon while maintaining the simplicity of the fastening operation
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An object of the present invention is to, in the case in which a shock load is applied, help to prevent concentration of stress at a mounting portion of a reclining mechanism to thereby prevent damage of a cushion frame and a seatback frame, and to help to prevent generation of a creep phenomenon in which the frames are deformed by a fastening force, making it possible to reduce the possibility of the fastening force being reduced. Provided is a vehicle seat frame structure including a resin seatback frame 3 and a cushion frame 2, the seatback frame 3 being rotatably supported by the cushion frame 2 by means of a reclining mechanism 5, wherein an outer cushion bracket 25 is provided on the outer side of the cushion frame 2; an inner cushion bracket 26 fixed to the reclining mechanism 5 is provided between the reclining mechanism 5 and the cushion frame 2; the cushion frame 2 is held between the outer cushion bracket 25 and the inner cushion bracket 26; and the outer cushion bracket 25 and the inner cushion bracket 26 are fixed in position by bolts 6.