Composite Seat Back Structure for Lightweight Strength
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Solution Overview
Problem
Current vehicle seat assemblies are heavy due to metal frames and brackets, which affect fuel economy and aesthetics, while seeking to balance strength, weight, and a streamlined appearance.
Innovation Solution
A seat back design featuring a backrest made of a first polymeric material with a reinforcing composite layer and a bracket of a different material, integrated through overmolding and melt bonding, providing structural support and a lightweight, aesthetically pleasing solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal frame and bracket are used to provide sufficient strength and stiffness, then the seat back can adequately support forces and pass crash tests, but the weight of the seat assembly increases
Solution Approach 1:
The patent applies composite materials by integrating a metal bracket with a composite backrest assembly consisting of a fabric layer, foam layer, and thermoplastic polymer layer. This composite structure replaces traditional heavy metal framing while maintaining sufficient strength through the combined properties of different materials - the metal bracket provides anchor points while the layered composite structure distributes and absorbs forces, achieving both strength requirements and weight reduction.
Solution Approach 2:
The patent changes the physical state and properties of materials through thermal processing. The thermoplastic polymer layer is heated to a molten state during injection molding, allowing it to flow and bond with the bracket and foam layer. This parameter change (from solid to molten state and back) enables the integration of components and creates a unified structure that achieves strength requirements with reduced weight compared to traditional metal construction.
2Strength
If thick metal frame and bracket construction is used to provide adequate strength, then the seat back can support occupant forces, but the aesthetic appearance is reduced and the streamlined look is compromised
Solution Approach 1:
The patent employs thin film and layered structure principles by using a fabric outer layer, foam intermediate layer, and thermoplastic polymer inner layer. This multi-layer thin film construction replaces the traditional thick metal frame, providing the necessary structural support while creating a sleek, streamlined appearance that conforms to the desired aesthetic shape without the visual bulk of metal framing.
Solution Approach 2:
The composite backrest assembly combines materials with different properties - the fabric provides aesthetic appearance and durability, the foam provides cushioning and shape, and the thermoplastic polymer provides structural integration with the bracket. This composite approach achieves both strength requirements and aesthetic appearance, eliminating the need for visible thick metal framing.
3Ease of operation
If thick padding is used to provide adequate cushioning and hide the metal frame, then occupant comfort is maintained, but the weight increases and the outdated appearance is conveyed
Solution Approach 1:
The patent uses a layered flexible structure consisting of a fabric outer layer and a foam intermediate layer that provides cushioning comfort. This thin film construction replaces the need for thick padding while maintaining comfort through the foam's inherent cushioning properties and the fabric's soft surface, thereby reducing weight while preserving ease of operation.
Solution Approach 2:
The patent extracts and eliminates the need for thick padding by integrating the cushioning function directly into the backrest structure through the foam layer. The metal frame is also extracted from visibility by being integrated with the composite layers, allowing the backrest to convey a modern appearance without requiring excessive padding for aesthetic concealment purposes.
4Strength
If heavy metal materials are used for the frame and bracket, then the strength and stiffness requirements are met, but the fuel economy of the vehicle decreases
Solution Approach 1:
The patent applies composite materials to reduce the overall weight of the seat assembly. By combining a metal bracket with a composite backrest structure (fabric, foam, and thermoplastic polymer layers), the design achieves the necessary strength requirements with significantly reduced weight compared to traditional all-metal construction. This weight reduction directly improves fuel economy while maintaining safety and structural integrity.
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
The integrated design results in a seat back that is both strong and lightweight, enhancing fuel efficiency and aesthetics while meeting strength requirements.
Implementation Method 1
heating the first polymeric material to a molten state
Implementation Method 2
introducing the first polymeric material in the molten state into the mold between and into contact with the reinforcing composite layer and the bracket to melt bond with the second polymeric material of the reinforcing composite layer
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
A seat back includes a backrest formed of a first polymeric material for supporting an occupant. A bracket formed of a different material than the first polymeric material of the backrest is anchored to the backrest for coupling to a seat cushion. A reinforcing composite layer is connected to the backrest and is formed of a second polymeric material and a plurality of fibers impregnated in the second polymeric material. The first polymeric material of the backrest is mechanically engaged with the bracket free of melt bonding between the first polymeric material of the backrest and the bracket. The first polymeric material of the backrest is melt bonded to the second polymeric material of the reinforcing composite layer integrating the backrest, the bracket, and the reinforcing composite layer.