Foldable Child Tricycle Four-Bar Linkage Frame

The patent applies the dynamics principle by transforming the fixed frame structure into a dynamic, movable structure. The frame body is divided into multiple segments (first frame body, second frame body, third frame body) that can rotate relative to each other around connection axes. This allows the structure to transition between an unfolded riding state with stable geometry and a folded state with reduced volume, resolving the contradiction between structural stability and volume reduction capability.

The patent applies segmentation by dividing the frame into modular components (first frame body, second frame body, third frame body, rear bracket) that can be independently positioned and connected. The rear bracket is separably connected to the third frame body, allowing it to remain fixed during riding for stability while enabling the entire structure to be folded for portability. This modular segmentation resolves the contradiction between riding function and portability.

The patent applies dynamics by making the handlebar assembly movable relative to the first frame body. The handlebar can rotate around a connection axis between the handlebar and the first frame body, enabling it to fold backward during the folding process. This dynamic capability allows the steering control function to be maintained during riding while enabling the overall structure to achieve compact folding for portability.