Flexible Thermoplastic Backpack Frame with Contoured Shell
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Solution Overview
Problem
Existing backpack frames made of rigid materials like steel or aluminum are uncomfortable due to lack of flexibility, prone to damage under impact, and costly, while thermoplastic frames lack rigidity and compromise balance and motion.
Innovation Solution
A lightweight, flexible backpack frame with varying longitudinal geometry and a re-curving contour, featuring side rails and an intermediate lattice structure made of high-strength thermoplastic, allowing for improved fit, motion, and balance by adjusting concavity and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid materials like steel or aluminum are used for the frame, then strength and rigidity are improved, but flexibility and comfort are worsened
Solution Approach 1:
The patent applies this principle by using a flexible thermoplastic shell structure instead of rigid metal tubes. The frame is formed as a continuous flexible shell that can bend and conform to the wearer's back, eliminating pressure points while maintaining structural integrity through the shell's geometry and material properties.
Solution Approach 2:
The patent changes the material parameter from rigid metal to flexible thermoplastic, and modifies the geometric parameters by creating a contoured shell shape with varying thickness. This allows the frame to transition from a rigid structure to one that is flexible yet strength, adapting to different wearers and load conditions.
2Ease of manufacture
If molded thermoplastics are used for the frame, then manufacturing cost is reduced, but rigidity and strength are worsened
Solution Approach 1:
The patent applies curvature principles by designing the frame as a contoured shell that follows the natural curvature of the human back. The shell's curved geometry provides structural rigidity through shape alone, eliminating the need for heavy reinforcement while maintaining strength. The varying thickness of the shell creates rigid zones where needed and flexible zones where comfort is required.
Solution Approach 2:
The patent uses a composite approach by combining thermoplastic material with a reinforced lattice or rib structure embedded within the shell. This composite construction provides metal-like rigidity in critical load-bearing areas while maintaining the overall flexibility and low-cost manufacturing advantages of thermoplastic molding.
3Stability of the object's composition
If the frame is designed to improve rigidity, then load stability is improved, but range of motion and balance are worsened
Solution Approach 1:
The patent applies dynamics by designing the frame as a flexible structure that actively adapts to the wearer's movements rather than resisting them. The shell flexes dynamically with the wearer's back movements, allowing full range of motion while continuously stabilizing the load through the shell's elastic recovery and geometric structure.
Data Source
AI summary
A backpack frame comprises side rails defining a first profile. The first profile has a flat first base segment lying on a first reference plane, and a first concave segment leading from the first base segment to an upper end of the frame, with the first concave segment being spaced a maximum distance from the first reference plane at a first location between the first base segment and the upper end of the frame. An intermediate structure interconnects the side rails. The intermediate structure defines a second profile having a second flat base segment lying on a second reference plane parallel to the first reference plane, and a second concave segment leading from the second base segment to the upper end of the frame, with the second concave segment being spaced a maximum distance from the second reference plane at a second location between the second base segment and the upper end of the frame. The first and second locations are offset from one another.