Foldable Hand Trolley Bottom Frame With Double-Layer Stability
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Solution Overview
Problem
Existing foldable hand trolleys face challenges in balancing strength and carrying convenience, often compromising on stability due to single-layer bottom frames or excessive use of support rods that increase folding height.
Innovation Solution
A double-layer bottom frame structure with connection assemblies and corner joints, featuring a fixed side rod, enhances stability and reduces folding height by using a fixed rod instead of telescopic rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If support rods are designed on the side surface to improve bottom frame stability, then the bottom frame stability is improved, but the folding height increases making the hand trolley inconvenient to carry
Solution Approach 1:
The patent transitions from a single-layer bottom frame to a double-layer bottom frame structure. By adding another layer in the vertical dimension and connecting them through connection assemblies, the structure achieves enhanced stability without requiring additional side support rods that would increase folding height.
Solution Approach 2:
The connection assemblies are designed to nest within each other during folding. The first connection piece and second connection piece can be positioned one inside another, allowing the structure to compact efficiently without increasing the overall folding height envelope.
2Length of moving object
If a single-layer bottom frame structure is used, then the folding height is reduced making the hand trolley convenient to carry, but the bottom frame becomes unstable
Solution Approach 1:
The patent solves the stability issue of single-layer frames by adding a second layer in the vertical dimension. The double-layer configuration with connection assemblies provides structural rigidity and stability while maintaining the compact folding profile characteristic of single-layer designs.
3Strength
If a double-layer bottom frame structure is implemented, then the strength and stability are improved, but the structural complexity increases
Solution Approach 1:
The connection assembly is divided into separate first and second connection pieces that can be independently manufactured and assembled. This segmentation allows for simpler individual components that are easier to produce and maintain, reducing overall manufacturing complexity despite the enhanced double-layer structure.
Solution Approach 2:
The connection assembly merges multiple functions into a single integrated component: it connects the bottom frame layers, enables folding motion, and provides structural support. This consolidation reduces the number of separate parts needed, simplifying the overall structure despite the double-layer configuration.
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 double-layer structure improves strength and stability while maintaining a compact folding size, making the trolley convenient to carry.
Implementation Method 1
one end of each connection assembly is hingedly connected to the central joint, the other end of the connection assembly is hingedly connected to one corner joint
Data Source
AI summary
A bottom support structure of a hand trolley and the hand trolley are provided. The bottom support structure includes a bottom frame and ground wheels. The bottom frame includes one central joint, at least three groups of connection assemblies, and at least three corner joints, one end of each connection assembly is hingedly connected to the central joint, the other end of the connection assembly is hingedly connected to one corner joint, and the corner joint is connected to the ground wheel, so that a foldable structure that is selectively unfolded or folded of the bottom frame is formed. One of the connection assemblies includes a first connection piece and a second connection piece, and when the bottom frame is unfolded, the first connection piece is located on the second connection piece, so that a double-layer structure of the bottom frame is formed.